Background technique
[0002]
　In oil well drilling for the mining of crude oil and gas oil, tubing and to let flow a fluid such as crude oil to the inside, oil well pipe is used, such as the casing enclosing the tubing. Oil country tubular goods, are generally connected using Xianyang threaded joints (conclusion). The depth of oil wells, has been conventionally 2000 ~ 3000m. However, in the deep oil well, such as in recent years of offshore oil, there is that depth is reached in 8000 ~ 10000m. The length of the individual of the oil well pipe is typically several tens of meters. Therefore, there is that oil well pipes of the enormous number of such thousand or more are connected.
[0003]
　To pipe thread joint for oil country tubular goods, load such as axial tensile force due to the mass of the oil well pipe and fittings itself in the environment of use, combined with pressure, such as the inner and outer surfaces pressure, and even underground heat is applied. Therefore, the Pipe threaded joint, without also damaged in such a severe environment, it is required to hold the airtightness.
[0004]
　Typical pipe thread joint used for fastening of OCTG, for example as described in Patent Document 1, the pin consists of a portion called pin having a male thread, a portion called a box having a female thread - box structure, and the like. Typically, pins are formed on both end portions of the oil well pipe, the box is formed on both sides of the inner surface of the threaded joint part, called the coupling.
[0005]
　At the time of drop work on the tubing and casing of the oil well, for a variety of reasons, such as trouble, loosen the once entered into a screw joint, after raising their joint once from an oil well, there is possible to drop concluded again. According to the API (American Petroleum Institute) standard, of 10 times in fitting for tubing, three times in the fitting for the casing, even if tightening the (make-up) and loosening (breakout), irreparable called Goring no occurrence of seizure, it is desirable that the air-tightness is maintained.
[0006]
　Upon tightening of threaded joint for oil well pipes, in order to improve the galling resistance and airtightness, the contact surfaces of the lubricant threaded joint, called "compound grease" (i.e., the threaded portion and the unthreaded metal contact portion) It is applied to. The compound grease, is a viscous liquid lubricant containing a heavy metal powder (grease lubrication oil). Examples of compound grease have been described in the API standard BUL 5A2.
[0007]
　Conventionally, in order to improve the improvement and slidability of the retention of compound grease, the one or more layers of the surface treatment it has been proposed to be applied to the contact surfaces of the threaded joint. Surface treatment, for example, nitriding treatment, a variety of plating including zinc-based plating and dispersed plating, or a phosphate chemical treatment.
[0008]
　Compound grease, zinc, lead, containing a large amount of heavy metal powder such as copper. Therefore, the impact on the environment of use, for example the impact on the marine environment and working environment have been pointed out.
[0009]
　In recent years, it is progressing strict regulations on the environment on a global scale. Also already used that in some areas compound grease is restricted. Accordingly, in the excavation of gas wells and oil wells, in order to avoid the impact on the environment and the human body, a threaded joint having excellent galling resistance without using compound grease is demanded.
[0010]
　As a threaded joint which can be used for fastening of OCTG without application of compound grease, the present applicants have previously proposed a pipe thread joint disclosed in Patent Document 2. Pipe threaded joint described in Patent Document 2, at least one of the contact surfaces of the pin and the box is coated with two layers film composed of a viscous liquid or semisolid lubricating coating, a dry solid coating formed thereon ing. Dry solid coating is formed from a thermosetting resin film or an ultraviolet curable resin film such as an acrylic resin. Lubricant film of viscous liquid or semi-solid, there is a sticky, foreign matter is likely to adhere. By forming the dry solid coating on the viscous liquid or semisolid on lubricant film, stickiness is eliminated. Dry solid coating is to be destroyed during the fastening of the threaded joint, it does not interfere with the lubricity of the lubricating coating beneath it.
[0011]
　Further, Applicants have the patent document 3, a thin lubricant film without stickiness, it proposed a threaded joint formed on the threaded portion (pin and box). Lubricating coating described in Patent Document 3 is obtained by dispersing the solid lubricant particles in a solid matrix exhibiting plastic or viscoplastic type rheological behavior (flow properties). The melting point of the solid matrix is ​​preferably in the range of 80 ~ 320 ℃. This lubricating coating, spray coating (hot-melt spray method) in the molten state is formed by spray coating of the spray or an aqueous emulsion, using a powder. Composition used in the hot melt spray method can, for example, polyethylene as a thermoplastic polymer, a wax as a lubricating component (e.g., carnauba wax) and metal soaps (e.g., zinc stearate), and containing a calcium sulfonate as a corrosion inhibitor to.
[0012]
　Further the present Applicants Patent Document 4, the contact surface of the pin to form a solid corrosion protective coating was provided a solid lubricant coating on the contact surface of the box, it has proposed a pipe threaded joint for. The solid corrosion protective coating is an ultraviolet-curing resin as a main component, are preferably transparent. The solid lubricating coating is preferably a thermoplastic polymer, wax, metal soaps, corrosion inhibitors, from a composition containing a water-insoluble liquid resin and the solid lubricant is formed by a hot melt method, the plastic or viscoplastic type rheological behavior a.
CITATION
Patent literature
[0013]
Patent Document 1: Kohyo 2006-526747 JP
Patent Document 2: WO 2006/104251 JP
Patent Document 3: WO 2007/042231 JP
Patent Document 4: WO 2009/072486 No.
Summary of the invention
Problems that the Invention is to Solve
[0014]
　Pipe threaded joint described in Patent Documents 2 to 4, at -10 ℃ ~ + 50 ℃ about cold-warm environment, because it has adhesiveness and lubricity performance of the excellent solid lubricating coating, a sufficient seizure resistance provided. However, when exposed to very low temperature environment such as -60 ℃ ~ -20 ℃, peeling and by the adhesion reduction of the solid lubricant film, made cracking by coating embrittlement is likely to occur, seizure resistance is insufficient. Furthermore, a very high torque and make the tightening of the screw joints and loosening work under such cryogenic environment is required.
[0015]
　The purpose of the present invention, the steel pipe under a very low temperature environment, even if the particular for connecting oil country tubular goods, without using a compound grease, it is possible to suppress the generation of rust, has excellent galling resistance and airtightness, the composition for forming a solid lubricating coating which is used for surface treatment of the surface tackiness hardly pipe threaded joint, the composition pipe thread joint with the formed solid lubricating coating from and production of pipe thread fittings it is to provide a method.
Means for Solving the Problems
[0016]
　The composition according to the present embodiment is a composition for forming a solid lubricating coating to the pipe threaded joint. The above composition contains a binder, a fluorine-based additive, and solid lubricant, and rust-preventive additive. Binding agent contains a ethylene vinyl acetate resin, a polyolefin resin, and following the wax melting point is 110 ° C.. Mass ratio of ethylene vinyl acetate resins to the mass of the polyolefin resin is 1.0 to 1.8. By weight in the wax, the ratio of the combined weight of the polyolefin resin and ethylene vinyl acetate resin is from 0.7 to 1.6.
[0017]
　Pipe threaded joint according to the present embodiment is provided with a pin and the box. Each of the pin and box has a contact surface including a portion contacting with each other. Pipe thread fittings, the solid lubricating coating is formed on at least one of the contact surface of the pin and box.
[0018]
　Method of manufacturing a pipe thread joint according to the present embodiment includes a step of forming the solid lubricating coating by applying the composition onto the contact surface.
[0019]
　Pipe threaded joint having a solid lubricating coating formed using the above composition, even under extremely low temperature environment, without the use of compound grease, suppressing the occurrence of rust, showed excellent galling resistance and airtightness , and the surface is less likely to stickiness.
Brief description of the drawings
[0020]
[1] Figure 1 is a block diagram showing an example of a pipe thread joint of the present embodiment.
FIG. 2 is a diagram showing an example of a fastening portion of the pipe thread joint, a cross-sectional view showing a unthreaded metal contact part of a special threaded joint (shoulder portion and the seal portion).
[Figure 3A] Figure 3A is a cross-sectional view of the contact surface near the case of roughening the contact surfaces themselves pipe thread fittings.
[Figure 3B] Figure 3B is a cross-sectional view of the contact surface near the case of forming a preparatory surface treatment coating for surface roughening on the contact surface of the pipe thread fittings.
[4] FIG 4 is a schematic view of a shear tensile test to measure the adhesion strength of the solid lubricating coating.
FIG. 5 is a low temperature of the solid lubricating coating - is a flow diagram illustrating the steps of an outdoor exposure test.
[6] FIG 6 is a diagram showing the rotational speed of the threaded joint, the relationship between the torque.
[7] FIG. 7 is a schematic diagram of a flat plate sliding test for measuring the coefficient of friction.
[8] FIG. 8 is a diagram showing the relationship between the talc content and the coefficient of friction in the solid lubricating coating.
DESCRIPTION OF THE INVENTION
[0021]
　The inventor of the present application, temperature -20 ℃ ~ + 50 ℃ about not only the low-temperature and low-temperate-tropical areas, even in the case of using a screw joint in the frigid region, which is also to be a temperature such as -60 ℃ ~ -20 ℃, sufficient galling resistance, rust preventing property, including a tightness, results torque required when fastening and loosening of the threaded joint has been studied to realize a threaded joint without becoming extremely high, was obtained the following findings.
　The solid lubricant coating formed on the pipe threaded joint, and compositions for forming a solid lubricating coating in (a solid lubricating coating composition),
　as (1) the binder of the composition (a binder), an ethylene acetate vinyl (EVA) resin, that the polyolefin resin and the melting point is to blend 110 ℃ or less of wax (wAX) in a specific ratio,
　be formulated in a specific ratio and (2) a fluorine-based additive,
　(3) further solid lubricant powder and adding an antirust additive,
by, even when exposed to cryogenic can maintain a high adhesiveness solid lubricating coating. Therefore, a threaded joint can be suppressed enough and a galling resistance and airtightness, and an increase in the torque required when fastening and loosening of the threaded joint at low temperatures. Further,
　(4) blending the talc specific particle size in a specific ratio,
it makes it possible to facilitate the torque adjustment during engagement.
[0022]
　The composition of the present embodiment has been completed based on the above findings is a composition for forming a solid lubricating coating to the pipe threaded joint. Composition contains a binder, a fluorine-based additive, the solid lubricant and anticorrosive additives. Binding agent contains a ethylene vinyl acetate resin, a polyolefin resin, and following the wax melting point is 110 ° C.. Mass ratio of ethylene vinyl acetate resins to the mass of the polyolefin resin is 1.0 to 1.8. By weight in the wax, the ratio of the combined weight of the polyolefin resin and ethylene vinyl acetate resin is from 0.7 to 1.6.
[0023]
　According to the composition of the present embodiment, it is possible to form the thermoplastic solid lubricating coating without having excellent seizure resistance on the contact surfaces of the pipe thread joint using a compound grease. There is almost no degradation of the solid lubricant film even in very low temperature environments, such as the solid lubricant film is -60 ℃ ~ -20 ℃. Therefore, excellent galling resistance similar to when using compound grease, and exhibits airtightness and corrosion resistance, and further can suppress the increase in the torque required when fastening and loosening of the threaded joint.
[0024]
　Preferably, the composition includes 60 to 80 mass% binder, 8 and to 18% by weight of the fluorine-based additive, and 5-15% by weight of solid lubricant, from 2 to 10 wt% anti-rust additives containing the agent.
[0025]
　The composition may further contain talc 2-15% by weight.
[0026]
　In this case, it is possible to increase the difference between the yield torque and shouldering torque, as a result, it is possible to facilitate the torque adjustment during engagement.
[0027]
　Talc particle size of the composition is 1 ~ 12 .mu.m for example, the specific surface area of the talc ~ 12m 4 2 a / g.
[0028]
　Pipe threaded joint according to the present embodiment is provided with a pin and the box. Each of the pin and box has a contact surface including a portion contacting with each other. Pipe thread fittings, solid lubricant film is formed on at least one of the contact surface of the pin and box. Solid lubricant coating, binder, a fluorine-based additive, containing a solid lubricant and anti-corrosion additive. Binding agent contains a ethylene vinyl acetate resin, a polyolefin resin, and following the wax melting point is 110 ° C.. Mass ratio of ethylene vinyl acetate resins to the mass of the polyolefin resin is 1.0 to 1.8. By weight in the wax, the ratio of the combined weight of the polyolefin resin and ethylene vinyl acetate resin is from 0.7 to 1.6.
[0029]
　Pipe threaded joint according to the present embodiment, since it contains the solid lubricant film can be used without coating a compound grease, is exposed to the cryogenic environment can be maintained high adhesion even. As a result, excellent galling resistance, airtightness, rust resistance is exhibited. Therefore, it is particularly useful for oil well drilling in arctic regions.
[0030]
　In a threaded joint for said pipe, for example, a solid lubricating coating, and 60 to 80 wt% binder, and 8-18 wt% of the fluorine-based additive, and 5-15% by weight of solid lubricant, 2-10 weight % of containing a rust-preventive agent.
[0031]
　In a threaded joint for said pipe, the solid lubricating coating may further contain talc 2-15% by weight.
[0032]
　The solid lubricating coating contained pipe thread joint according to the present embodiment, when talc, it is possible to increase the difference between the yield torque and shouldering torque, as a result, torque adjustment at the time of tightening the threaded joint the can be facilitated.
[0033]
　When a solid lubricating coating contains talc, particle diameter of talc for example, a 1 ~ 12 .mu.m, the specific surface area of the talc for example, 4 ~ 12m 2 is a / g.
[0034]
　Preferably, the tube threaded joint for further includes a solid corrosion protective coating containing an ultraviolet curable resin. On one of the contact surface of the pin and box, the solid lubricant coating is formed. On the other of the contact surface of the pin and box, solid corrosion protective coating is formed.
[0035]
　The thickness of the solid corrosion protective coating, for example, is 5 ~ 50μm.
[0036]
　The thickness of the solid lubricant film is, for example, 10 ~ 200μm.
[0037]
　Preferably, the tubular threaded joint is used for oil country tubular goods.
[0038]
　Method of manufacturing a pipe thread joint of the present embodiment is a manufacturing method of a pipe thread joint having a pin and box. Each of the pin and box has a contact surface including a portion contacting with each other. Method of manufacturing a pipe thread joint of the present embodiment, on at least one of the contact surfaces of the pin and the box, comprising the step of forming the solid lubricating coating by coating the above composition.
[0039]
　Preferably, the manufacturing method includes the step of forming the solid lubricating coating on the pin and one of the contact surfaces of the box. The above manufacturing method further comprises the step of applying the composition for a solid corrosion protective coating comprising the ultraviolet-curing resin on a pin and the other contact surface of the box. The above manufacturing method further comprises a step of forming the solid corrosion protective coating was irradiated with ultraviolet light to the composition for a solid corrosion protective coating.
[0040]
　Hereinafter, the pipe screw joint according to the present embodiment, that the embodiment will be described more specifically for the purpose of illustration. In this case, the pipe threaded joint for oil well pipes for the steel pipe will be explained as a preferred embodiment. However, the present invention is particularly not limited to this embodiment, for example, can be applied to a threaded joint for use in a tube other than OCTG applications.
[0041]
　Figure 1 is a block diagram showing an example of a pipe thread joint of the present embodiment. Pipe thread joint is provided with a steel pipe 2, and a coupling 8. At both ends of a steel pipe 2 pins 6 having a male screw portion 4 on the outer surface is formed. On both sides of the coupling 8, box 12 having an internal thread portion 10 on the inner surface is formed. At one end of the steel pipe 2, it is mounted in a pre-coupling 8 screws. Although not shown, the pin 6 of the steel pipe 2 with the mating member is not mounted box 12 (in the illustrated example left) and a coupling 8 (right side in the illustrated example), a protector for the protection of each screw portion (not shown) is mounted before shipping.
[0042]
　In a typical pipe thread joint, the pipe thread fitting for coupling scheme shown in FIG. 1, the pin 6 is formed on the outer surface of both ends of a steel pipe 2, the box 12 is formed on the inner surface of the coupling 8. On the other hand, without using a coupling, one end of a steel pipe and a pin shape, also pipe threaded joint for integral scheme in which the other end with the box-shaped. Pipe threaded joint of the present embodiment is applicable to any of the coupling type and integral type.
[0043]
　Figure 2 is a cross-sectional view showing an example of a fastening portion of the pipe thread fittings. And the outer peripheral surface near the end face of the distal side of the male thread of the pin 6, the inner peripheral surface of the base portion of the female screw of the box 12, the sealing portion 14 and 16 respectively are formed. And the tip end surface of the pin 6, the surface of the innermost part of the box 12 corresponding to the end face of the tip of the pin 6, the shoulder portion, respectively (also referred to as a torque shoulder) 18 and 20 are formed. Seal portion and the shoulder portion constitute metal contact without a screw (so-called unthreaded metal contact portion) in the threaded joint for pipes. And metal-to-metal contact portion and a threaded portion of the pin 6 and the box 12 are in contact with each other, constitute the contact surface of the tube for the threaded joint. When tightening the male screw and the female screw by inserting the pin 6 in the box 12, the shoulder portion 18 and 20 between the pin 6 and the box 12 is in contact. The torque at this time is referred to as a shoulder ring torque. In addition, when tightening the male screw and the female screw to interfere with the proper torque, in close contact with the seal portion 14 and 16 between the pin 6 and the box 12 metal - metal between the seal is formed, air-tightness of the pipe thread fittings to ensure It is. The torque at this time is referred to as a conclusion torque. Furthermore, when tightening the male screw and the female screw, metal constituting at least one of the pin 6 and the box 12 begins to undergo plastic deformation. The torque at this time is referred to as a yield torque. If you have tightened the external thread and the internal thread in the greater torque than the yield torque, there is that air-tightness of the pipe for the screw joint is reduced. Fastening torque is greater than the shouldering torque, is set within a range smaller than the yield torque. Therefore, when a large difference between the yield torque and the shouldering torque, it is easy to adjust the fastening torque.
[0044]
　As described above, in each of the pin 6 and the box 12, threaded portion, the seal portion and the shoulder portion, which corresponds to the contact surface of the threaded joint. These contact surface, galling resistance, airtightness, and corrosion resistance are required. In the past, it had been coated with a compound grease containing a heavy metal powder to the contact surface. However, now the influence of heavy metals into the human body and the environment is concerned, threaded joint having a solid lubricant film that can be used for fastening of OCTG without application of compound grease was considered. The solid lubricating coating is typically a resin film containing a solid lubricant.
[0045]
　However, in the conventional solid lubricating coating, when exposed to cryogenic environment that also -60 ℃ ~ -20 ℃ at once, cracking due to embrittlement deterioration of the film itself there is a problem that occurs. Further, in the conventional solid lubricating coating, the difference in thermal expansion coefficient between the base material (steel), readily coating decreases the adhesion when returning to the vicinity of room temperature is disadvantageously peeled off.
[0046]
　If the cryogenic environment of -60 ℃ ~ -20 ℃ pipe thread fittings are used, the fastening (make-up) torque increases. Therefore, there is a case where metal contact portions for screw fastening to ensure airtightness without completing properly does not contact with a predetermined surface pressure (referred to as high shouldering). As well as could be if entered into, will burn in the conclusion is likely to occur, loosen at the time of screw loosening (breakout) torque is very high. Further, when the tongue of the ability to be used for fastening the pin and the box is low, there is a possibility not be fastened by a torque insufficiency.
[0047]
　3A and 3B are sectional views of the contact surface near the pipe thread joint of steel pipe of the present embodiment. The contact surface of at least one member of the pin and the box, the surface of the steel pipe 22 constituting the member is covered by the solid lubricating coating 24 formed by later-described composition. The solid lubricating coating 24 can maintain adhesion even when exposed to cryogenic environment of -60 ℃ ~ -20 ℃. The solid lubricating coating 24 further imparts lubricity to the threaded joint. For this reason, while preventing the engagement and increase torque at the time of the loosening can be prevented the seizure of the threaded joint, and it is also possible to ensure air-tightness after the conclusion.
[0048]
　The solid lubricating coating 24 may be contained in a coating on the surface of the steel pipe 22. For example, as shown in Figure 3A, it may be formed to be in direct contact with the surface of the steel pipe 22. As shown in FIG. 3B, although not formed in direct contact with the steel pipe 22 surface, it may be contained in the film formed on the steel tube surface. The solid lubricating coating 24 is preferably disposed on the top surface of the coating on the surface of the steel pipe 22. However, the arrangement of the solid lubricating coating 24 is not particularly limited, for example, the top surface of the coating containing a solid lubricant film 24 may be applied such as coating agent for rust and scratch prevention. Hereinafter, the solid lubricant film 24 directly, is described as an example the case of forming the contact surface of the steel pipe 22.
[0049]
　Incidentally, the interface between the solid lubricant film 24 and the steel tube 22 (i.e., the contact surface of the steel pipe 22) is preferably a rough surface. The roughening, as shown in Figure 3A, can be achieved by direct surface roughening by blasting or pickling of the surface of the steel pipe 22. As shown in FIG. 3B, roughening, prior to forming the lubricating coating 24, surface treatment film surface becomes rough surface (eg, phosphate coating, a porous zinc (alloy) plating film) 26 steel pipe It can also be achieved by previously formed on the surface of the 22.
[0050]
　The solid lubricating coating 24 is formed, for example, in the following manner. To prepare a thermoplastic solid lubricating coating of the composition. By melting the composition at a predetermined temperature, spray, brushing, applied onto the contact surface in a suitable manner, such as spraying and dipping. After coating, air cooling, and solidifying the composition by a known cooling means such as cooling to form a solid lubricant coating 24.
[0051]
　The solid lubricating coating may be formed on the contact surface of both the pin and box. Further, as shown in FIG. 1, the point of fastening the pin and the box at the factory, only one of the contact surfaces of the pin and the box may be formed solid lubricating coating. In this case, than the steel pipes having a length dimension, towards also the coupling of the short dimension than steel pipe, it is easy coating work for preparatory surface treatment and lubricating coating. Therefore, usually, the contact surfaces of the coupling, ie it is preferable to form a lubricating coating on the contact surface of the box.
[0052]
　In the place where the pin and the box has not been entered into at the time of shipment, the contact surface of both the pin and box to form a solid lubricant film, lubricity and may be allowed to grant a rust resistance at the same time. Or, only to form a solid lubricating coating the contact surface of one of the pin and the box (e.g. box), it may form a solid corrosion protective coating on the contact surface of the other (eg, pins). In any case, the seizure resistance to the screw joints, the air-tightness and corrosion resistance can be imparted. The solid corrosion protective coating is preferably a UV-curable coating. Further, the solid corrosion protective coating is preferably formed from subjected to preparatory surface treatment for surface roughening.
[0053]
　Solid lubricant coating is to cover all of at least one of the contact surface of the pin and the box is preferred. However, the solid lubricating coating, a portion of the contact surface only (for example, the seal portion only) may be coated.
[0054]
　[Solid lubricating coating]
　As described above, in this embodiment, the at least one contact surface of the pin and the box constituting the pipe thread joint, to form a solid lubricating coating. This solid lubricant film, it is required to maintain a very low temperature (-60 ℃ ~ -20 ℃) adhesion even when exposed to. Solid lubricant film is further provided, in the time of the conclusion of the steel pipe to each other by a threaded joint, not only the low-temperate-tropical areas (-20 ℃ ~ + 50 ℃) , even in the very low temperature region (-60 ℃ ~ -20 ℃) , or causing high shouldering higher fastening torque, without that screw loosening torque may become high, whereby it is required to be suppressed the occurrence of seizure. Solid lubricant film in addition, it is required to prevent rusting during storage. And about room temperature, in a cryogenic environment, if the adhesion strength of the solid lubricant coating (hardness) is greatly changed, or crack is generated in the solid lubricant film in the cryogenic environment, solid lubricant film when returning to around room temperature peeling occurs. Therefore, a solid lubricating coating further includes between about room temperature and the cryogenic environment, the adhesion strength of the solid lubricating coating (hardness) that does not change greatly demanded.
[0055]
　The composition for forming a solid lubricating coating according to the present embodiment is a substrate of the film. The composition includes a binder that exhibits a high adhesion to a cryogenic temperature from the room temperature, the fluorine-based additive for adhesion and low friction of at cryogenic temperatures, and a solid lubricant to prevent seizure, containing a rust inhibitor for long-term anti-rust of up to be used from the coated.
[0056]
　[Binding agent]
　binding agent of the present embodiment, it consists of a ethylene vinyl acetate resin (EVA), polyolefin resin (PO), and a melting point of 110 ° C. or less of the wax (W). In order to achieve high coating adhesion over a cryogenic from room temperature, and ethylene vinyl acetate resin, a polyolefin resin, the mass ratio of the wax is as follows.
　1.0 ≦ (EVA / PO) ≦ 1.8, and
　0.7 ≦ ((EVA + PO) / W) ≦ 1.6
　above mass ratio is a matter that has been revealed for the first time experimentally in the present invention. Incidentally, EVA, PO and W in the above formulas, respectively, show ethylene vinyl acetate resin, the mass of the polyolefin resin and waxes.
[0057]
　If the mass ratio of ethylene vinyl acetate resin for the polyolefin resin (EVA / PO) is less than 1.0, the adhesion strength of the solid lubricant film is insufficient at a temperature greater than -20 ℃. On the other hand, (EVA / PO) is if it exceeds 1.8, insufficient adhesion strength of the solid lubricant film at -20 ℃ following cryogenic. Cryogenic (-20 ~ -60 ℃), through the low temperature (-20 ~ 0 ℃) and warm Tropical (-10 ~ 50 ℃), in order to maintain a well-balanced adhesion, the lower limit of (EVA / PO) 1.0, the upper limit is 1.8. Order to secure the effect, (EVA / PO) Preferred lower limit of 1.05, more preferably 1.1, still more preferably 1.15, more preferably be 1.2 , more preferably from 1.35. A preferred upper limit for (EVA / PO) is 1.7, more preferably 1.65, still more preferably 1.6.
[0058]
　If the weight for the both resin wax weight ratios but the combined (ethylene vinyl acetate resin and polyolefin resin) ((EVA + PO) / W) is less than 0.7, the hardness of the solid lubricating coating is lowered, the adhesion strength It becomes insufficient. On the other hand, if it exceeds ((EVA + PO) / W) is 1.6, excessively high hardness of the solid lubricant film, in particular the frictional resistance increases at cryogenic temperatures. In this case, the torque at the time of the tightening and loosening of the threaded joint is too high. Therefore, from the viewpoint of hardness and regulation friction suitable for solid lubrication coating threaded joint, a lower limit of 0.7 ((EVA + PO) / W), the upper limit is 1.6. Order to secure the effect, the preferred lower limit of ((EVA + PO) / W) is 0.8, more preferably 0.85, still more preferably 0.9. ((EVA + PO) / W) Preferred upper limit of 1.5, more preferably 1.45, still more preferably 1.4.
[0059]
　The polyolefin resin (PO) is a general term for chain hydrocarbon having a double bond in one place. The polyolefin resin (PO), since a crystalline polymer (polymer), physical properties changed by crystallinity. As the resin of this system, polyethylene, there is such as polypropylene, as a specific example, Cemedine HM712 manufactured by Co., Ltd. (a softening point of 120 ℃), and the like.
[0060]
　Ethylene vinyl acetate resins (EVA) is a copolymer of ethylene and vinyl acetate. As a specific example, HM224 manufactured by Cemedine Co., Ltd. (softening point 86 ℃), and the like.
[0061]
　Wax (W) is, by the friction-reducing solid lubricant film, to suppress the seizure. Wax further adjust the hardness of the solid lubricant film, enhancing the toughness of the solid lubricating coating. As a wax, animal, vegetable, none of mineral and synthetic waxes can be used. Available waxes are, for example, beeswax, spermaceti (or, animal), Japan wax, carnauba wax, candelilla wax, rice wax (or, vegetable), paraffin wax, microcrystalline wax, petrolatum, montan wax, ozocerite , ceresin (or more, mineral), oxidized wax, polyethylene wax, Fischer-Tropsch wax, amide wax, hydrogenated castor oil (castor wax) (or more, synthetic wax) is. Wax has a melting point used as of 110 ℃ or less. If the melting point of the wax is 110 ℃ or less, the difference between the adhesion strength of the solid lubricant film in the vicinity of the room temperature, and the adhesion strength of the solid lubricant film in the cryogenic environment (hardness) is reduced. Thus, in a cryogenic environment, it is possible to suppress the cracking of the solid lubricant film. Further, peeling of the solid lubricating coating upon returning to the vicinity of room temperature can be suppressed. That is, the adhesion strength of the solid lubricating coating (the hardness) can be maintained in an appropriate range, further increases toughness solid lubricating coating. The melting point of the wax is preferably 0.89 ° C. or less, melting point and molecular weight in 90 ° C. or less and more preferably of 150 to 500 paraffin wax. Wax further is preferably a solid at room temperature. The preferred lower limit of the melting point of the wax is 40 ℃. By using a solid wax at room temperature, it is possible to make the adhesion strength of the solid lubricant film at around room temperature in an appropriate range.
[0062]
　The content of the binder to the composition is preferably 60 to 80 mass% (hereinafter, unless otherwise noted, content is described in weight percent). When the content of the binder is 60% or more, further enhanced adhesion of the solid lubricating coating. When the content of the binder is 80% or less, lubricity is better maintained.
[0063]
　As binders, the melting temperature (or softening temperature, hereinafter the same) of 80 ~ 320 ° C. of ethylene vinyl acetate resin, it is preferable to use a polyolefin resin. Molten base (binding agent), it returns to solid when the temperature becomes lower than the melting temperature. The melting temperature is more preferably in the range of 90 ~ 200 ℃. Ethylene-vinyl acetate resin as a film base, the melting temperature of the polyolefin resin is too high, it is difficult to apply in the melt as a hot melt application. On the other hand, when the melting temperature of the binder is too low, a solid lubricating coating is softened when the temperature rises, there may be cases where the performance is lowered.
[0064]
　Contacting surface of the pipe threaded joint for forming a lubricating coating, as described below, due to chemical conversion treatment and plating may be subjected to surface treatment. Adhesion of the solid lubricating coating to the contact surfaces of the steel pipe, film-forming properties and coating properties, the viscosity during melting of the solid lubricating coating, when considering the dispersibility of the solid lubricant, ethylene-vinyl acetate resin and polyolefin resin, melting point, the softening point is preferably a mixture obtained by combining a plurality of types having different properties such as glass transition point.
[0065]
　Ethylene-vinyl acetate resin used as the base (binding agent), in order to suppress the rapid softening due to a temperature rise, and particularly preferably a mixture of two or more ethylene-vinyl acetate resins having different melting temperatures. Similarly, the polyolefin resin used as a base (binders) are also particularly preferably a mixture of two or more polyolefin resins having different melting temperatures.
[0066]
　[Fluorine-based additive]
　solid lubricating coating of the present embodiment, the binding agent and base, further containing a fluorine-based additive. Fluorine-based additive to improve the sliding property at the time of sliding. Fluorine-based additive further enhance the toughness of the solid lubricating coating in an extremely low temperature. Fluorine-based additive are, for example, a fluorinated polymer such as perfluoropolyether (PFPE) or a grease-like liquid system. PFPE and fluorinated polymers, the added ease to the binding agent, it is preferable to use a fluorine-based additive. Even basic skeleton perfluoropolyether-modified product such as a fluorinated polyether having a molecular weight of 500-10,000, such as, can be used as the fluorine-based additive.
[0067]
　Suitable content of the fluorine-based additives to the composition, is 8 to 18%. When the content of the fluorine-based additive is 8% or more, further increased the lubricity and adhesion at low temperatures. When the content of the fluorine-based additive 18% or less, the adhesion at room temperature can be maintained better.
[0068]
　[Solid lubricant]
　solid lubricating coating in order to further enhance its lubricity, containing various solid lubricants. The solid lubricant, wherein the means a powder having lubricating properties. Solid lubricant can be roughly divided into the following four types.
　(1) slippery specific crystal structure, for example, shows the lubricity by having a hexagonal layered crystal structure (e.g., graphite, zinc oxide, boron nitride),
　a reactive element in addition to
　(3)(2) shows the lubricity by a chemical reactivity (e.g., certain thiosulfate sulfate type compound), and
　(4) it shows the lubricity due to plastic or viscoplastic behavior under frictional stresses (e.g., polytetrafluoroethylene (PTFE) and polyamide).
[0069]
　In the present invention, any solid lubricant (1) to (4) can also be used. Preferred solid lubricant is (1). It may be used a solid lubricant (1) alone, and (2) and (4) of may be used in combination of at least one solid lubricant. Adhesion, from the viewpoint of anticorrosive properties, graphite is a preferred solid lubricant, and more preferably amorphous graphite from the viewpoint of film formability. The content of the solid lubricant of the solid lubricating coating (and the solid lubrication coating composition) is preferably in the range of 5 to 15 wt%.
[0070]
　The composition for a solid lubricating coating may further contain an inorganic powder for the sliding of the adjustment. Such inorganic powders are, for example, bismuth oxide and titanium dioxide. Inorganic powder may be contained in an amount of in the composition, up to 10 wt% in total.
[0071]
　The solid lubricating coating according to the present invention, is applied, positively contain anticorrosive additives in order to secure the anticorrosive property over a long period of time before it is actually used. Examples of anti-rust additives, aluminum tripolyphosphate, include phosphorous acid Aruminimu and calcium ion exchange silica. Etc. Other commercial reactive water repellent may also be used.
[0072]
　A preferred content of the rust-preventive agent in the composition is 2 to 10 mass%. If it is contained rust additive is more than 2% by weight, rust of the solid lubricant film is further enhanced. If it is contained anti-rust additive is 10 wt% or less, can maintain lubricity and adhesion of the solid lubricant film better.
[0073]
　Friction modifiers]
　The solid lubricating coating composition for further may contain talc as a friction modifier. The talc (Talc), is made by grinding the ore as talc, a white or gray inorganic powder. Talc chemical name is hydrous magnesium silicate, Mg 3 Si 4 O 10 (OH) 2 having a chemical composition of. Talc, SiO 2 about 60 wt%, MgO from about 30 weight percent, and contains about 4.8 wt% water of crystallization. Talc is a true specific gravity of 2.7-2.8, Mohs hardness is 1, in the inorganic mineral lowest. Furthermore, talc is excellent in heat resistance, are chemically stable substances. Therefore, talc, can be used as a filling material. Talc surface, improved dispersibility by chemically or physically binding the treatment material, surface modification talc are also included in the talc of the present embodiment.
[0074]
　Talc, when fastening the screw joint, there is a function to increase the difference in yield torque (high surface pressure time) and the shoulder ring torque (low surface pressure time). If the difference between the yield torque and shoulder ring torque is large, it can afford in the range of the fastening torque when fastening the screw joint. As a result, it becomes easy to adjust the torque at the time of the threaded joint. This effect, talc, when a high surface pressure of the sliding contact surfaces of the threaded joint, resulting in order to maintain the friction coefficient to a suitable level. When the content of talc in the composition took more than 2 wt%, it is possible to increase this effect, as long as 15 wt% or less, less risk to galling resistance. Therefore, it is preferable that the content of the talc is from 2 to 15 mass%. From the viewpoint of the adhesiveness of the seizure resistance and solid coating, more preferred lower limit of the talc content is 3 wt%, more preferably 5% by mass. The more preferable upper limit of the talc content is 10 wt%, more preferably 8% by mass.
[0075]
　Particle size of the talc in the present embodiment is preferably 1 ~ 12μm. When the particle diameter of the talc is 1μm or more, the effect of increasing the difference between the yield torque and shouldering torque can be stably obtained. Equal to or less than talc of particle size of 12μm, there is little fear that the decrease in dispersibility and adhesion of a solid lubricating coating in. The more desirable lower limit of the particle diameter of the talc is 3 .mu.m, more preferably from 4 .mu.m. More preferable upper limit of the particle diameter of the talc is 10 .mu.m, more preferably from 8 .mu.m. The term "particle size" as used herein, refers to a median diameter (D50) determined from particle size distribution.
[0076]
　Particle diameter of talc, for example, using a laser diffraction type particle size distribution measuring apparatus, to create a particle size distribution by accumulation. Then, it can be determined by calculating the median size from the resulting particle size distribution.
[0077]
　The specific surface area of the talc according to the present embodiment, 4 ~ 12m 2 is preferably / g. The specific surface area of the talc 4m 2 If / g or more, increases the affinity of the binder of talc and solid lubricating coating. Therefore, during sliding can be suppressed talc falling off from the solid lubricant film surface. The specific surface area of the talc 12m 2 If / g or less, an effect of increasing the difference between the yield torque and shouldering torque can be stably obtained. A more preferred lower limit of the specific surface area of talc 6 m 2 was / g, more preferably 7 m 2 is a / g. A more preferred upper limit of the specific surface area of the talc 11m 2 was / g, more preferably 10 m 2 is a / g.
[0078]
　The specific surface area of ​​talc, for example, can be determined by the BET method. Specifically, by using a specific surface area automatic measuring device, adsorbing gas (e.g. nitrogen gas) is adsorbed occupied area talc the surface is already known. From the relationship between the amount of adsorption of pressure and gas in the gas, it calculates the monomolecular adsorption by the BET equation. Further, it calculates a specific surface area by applying a suction area occupied per unit gas molecules.
[0079]
　Other Components
　The compositions of the present embodiment, in addition to the above components, surfactants, coloring agents, minor amounts additional ingredients selected from antioxidants, etc., in an amount of 5 wt% or less for example in total it may be. The composition for a solid lubricating coating further extreme pressure agent, if such be 2 wt% or less of a very small amount liquid oil may contain.
[0080]
　In the present embodiment, for forming the solid lubricating coating, a solid lubricating coating composition (hereinafter, also referred to as coating composition) is provided. The coating composition may be a solvent-free even in the composition, or the composition of the solvent-dissolved in a solvent consisting of only a component described above. For solvent-based composition, the weight percent of each component refers to the weight% in the case of the mass of the total of all components other than the solvent contained in the composition taken as 100%. Hereinafter, an example of a method for manufacturing a pipe thread joints using a coating composition.
[0081]
　The coating composition of solventless type, for example, can be prepared by blending such solid lubricants and anticorrosive additives, kneading it in a base in a molten state. It can be used a powder mixture obtained by mixing all ingredients in powder form as a coating composition. The composition of solventless type, lubricant film can be formed in a short time, there is an advantage that no evaporation of the organic solvent that affect the environment.
[0082]
　The coating composition of such a solvent-free type, for example, can form a solid lubricating coating using a hot melt method. In this way, by heating a coating composition (containing bases and various powders described above), to melt the base material, the composition became fluidized state of low viscosity, constant temperature (usually molten state is carried out by spraying from the spray gun having a temperature and a temperature retaining function to the same degree of temperature) of the composition. The heating temperature of the composition is preferably (in the case of a mixture mixture) base and the melting point (melting temperature or softening temperature) than 10 ~ 50 ° C. higher temperatures.
[0083]
　At least one of the contact surfaces of the pin and box to which the composition is applied is preferably preheated to above the melting point of the base temperature. Thereby it is possible to obtain good coverage.
[0084]
　The coating composition is melted by heating in a tank equipped with a suitable stirring device, is supplied to the spray head of the spray gun via a metering pump (held at a predetermined temperature) by a compressor, it is sprayed. Holding temperature within the spray head tank is adjusted in accordance with the melting point of the base in the composition.
[0085]
　Thereafter, cooling the threaded joint, when cooled such as by cooling, a solid lubricating coating composition is solidified, the solid lubricating coating according to the present embodiment is formed on the contact surface. Thus the thickness of the formed solid lubricating coating is preferably in the range of 10 ~ 200μm, and more preferably in the range of 25 ~ 100μm. If the thickness of the solid lubricant film is too small, insufficient lubrication of the pipe thread fittings, seizure is likely to occur at the time of tightening or when loosening. Although the solid lubricating coating comprises also a certain degree of corrosion resistance, the film thickness is too small, corrosion resistance becomes insufficient, corrosion of the contact surfaces is reduced.
[0086]
　On the other hand, when the film thickness of the solid lubricant film is too large, not only the solid lubricant film is wasted, it can affect the environment. It is formed as needed and a solid lubricating coating, none of the solid corrosion protective coating to be described later, in the case of forming on the contact surface having an increased surface roughness by surface treatment includes a large thickness than Rmax of the base it is preferred. Otherwise, there is a case where it is not possible to completely cover the base. The film thickness when the base is a roughened surface, the average value of the total thickness of the coating can be calculated area of ​​the film, from the mass and density.
[0087]
　In the case of the solid lubricating coating and the following thin film 25μm may form a thin anticorrosive coating further solid or liquid in the upper layer or lower layer of the coating film.
[0088]
　[Solid corrosion protective coating]
　one of the above-mentioned thermoplastic solid lubricating coating the pin and the box of pipe thread fittings (for example, boxes) in the case of forming only on the contact surface of the contact surface of the other (for example, pin), for example, will be described later it may be only surface treatment, preferably in order to impart a rust resistance, to form a solid corrosion protective coating as a top surface treatment coating layer.
[0089]
　As described above with respect to FIG. 1, until the pipe threaded joint for actual use, the tightening is often protector mounted on the pin and box not performed. The solid corrosion protective coating, and the coating with a force applied during at least the protector mounting is not destroyed, during transportation or storage, it does not dissolve when exposed to condensed water from the relationship between dew point, easily even at high temperatures exceeding 40 ° C. it not soften is required to.
[0090]
　As a film satisfying such properties, it is known that can form a high strength film to form a solid corrosion protective coating from a composition based on a UV-curable resin. As the ultraviolet curable resin, it can be used at least a monomer, an oligomer, a known resin composition composed of a photopolymerization initiator. UV causes a photopolymerization reaction by being irradiated with, as long as it forms a cured film, not particularly limited to the components and composition of the ultraviolet curable resin composition.
[0091]
　Monomers, for example, addition of a polyhydric alcohol and (meth) polyvalent (di- or higher tri) acrylic acid esters, various (meth) acrylate compounds, N-vinyl pyrrolidone, N- vinyl caprolactam, and styrene . As the oligomer, but are not limited to, epoxy (meth) acrylate, urethane (meth) acrylates, polyester (meth) acrylates, polyether (meth) acrylate and silicone (meth) acrylate.
[0092]
　Preferred photopolymerization initiators are compounds having absorption in the wavelength of 260 ~ 450nm. The photopolymerization initiator is, for example, benzoin and its derivatives, benzophenone and its derivatives, acetophenone and its derivatives, Michler's ketone, benzyl and its derivatives, tetralkylthiuram monosulfide, a thioxane, and the like. A particularly preferred light polymerization initiator is a thioxane class.
[0093]
　The solid corrosion protective coating formed from a UV curable resin, from the viewpoint of the film strength and sliding properties, may contain additives selected from lubricants and anticorrosive agents. Examples of additives for improving the film strength is fibrous filler. Fibrous filler is, for example, a needle-shaped calcium carbonate, such as the Maruo Calcium Co., Ltd., "Uisukaru". Examples of lubricants are metal soaps, polytetrafluoroethylene (PTFE) resins such as calcium stearate or zinc stearate. These one or more lubricants, to UV-curable resin 1 in a mass ratio, may be added in an amount of 0.05-0.35. While there may be insufficient film strength is that it 0.05 or less, sometimes more than 0.35 when the coating workability viscosity becomes higher or inviting lowered, lowering the film strength conversely.
[0094]
　Rust inhibitor is, for example, a tripolyphosphate aluminum and phosphorous acid Aruminimu like. Rust inhibitor, relative to the ultraviolet curing resin 1 in a mass ratio, may be added to a maximum of about 0.10.
[0095]
　The solid corrosion protective coating formed from an ultraviolet curing resin is what is often transparent. Inspection visual or image processing of the formed solid corrosion protective coating from the viewpoint of facilitating the (presence or absence of coating, tests such as the uniformity / nonuniformity of the coating thickness) and the solid corrosion protective coating may contain a coloring agent. Colorant used can be selected pigments, dyes, and fluorescent materials. Fluorescent materials may not color the coating under visible light, since under at least ultraviolet to color the coating, in the present invention include in the colorant. These coloring agents may be a commercially available product, quality inspection of the solid corrosion protective coating visually or image processing is possible, it is not particularly limited. Any of the organic colorant and inorganic coloring agents can be used.
[0096]
　The addition of pigment, the transparency of a solid corrosion protective coating decreases or is lost. When the solid corrosion protective coating becomes opaque, inspection of the presence or absence of damage to the pin threaded portion of the base is difficult. Therefore, if you want to use the pigment is preferably lightness of high color of the pigment, such as yellow or white. From the viewpoint of corrosion resistance, the particle size of the pigment is preferably as small, average particle size is preferably used those 5μm or less. Dyes, so does not greatly decrease the transparency of a solid corrosion protective coating, for example, does not cause any trouble even in strong color dyes such as red or blue. The addition amount of pigments and dyes is preferably a maximum of 0.05 with respect to the ultraviolet curing resin 1 in a mass ratio. It exceeds 0.05 when the corrosion resistance may be lowered. More preferred amount by weight ratio of 0.02 or less.
[0097]
　Fluorescent material, a fluorescent pigment may be any of phosphors used in fluorescent dyestuff and fluorescent paint. Fluorescent pigment is divided into day and inorganic fluorescent pigments fluorescent pigments. Inorganic fluorescent pigments are, for example, zinc sulfide or zinc sulfide cadmium-based (metal-activator-containing), halogenated calcium phosphate, include rare earth activated strontium chloro apatite, also be used as a mixture of two or more thereof many. Inorganic fluorescent pigments are excellent in weather resistance and heat resistance.
[0098]
　There are several kinds in the daylight fluorescent pigment, the main flow is of a synthetic resin solid solution type in which pigmented with a fluorescent dye is contained in a colorless synthetic resin. It can also be used fluorescent dye itself. Furthermore, various inorganic or organic fluorescent pigments in the fluorescent paints and fluorescent printing ink, and is used particularly synthetic resin solid solution type, it is possible to use these phosphors as the fluorescent pigments or fluorescent dyes.
[0099]
　Solid corrosion protective coating containing a fluorescent pigment or dye, but under visible light is a transparent colorless or colored, so that the light-emitting-coloring and is irradiated with a black light or ultraviolet light, to check the non-uniformity of the coating of the presence or absence and the coating thickness be able to. Further, since it is transparent under visible light, it is possible to observe the base material under the solid corrosion protective coating. Therefore, inspection of damage to the threaded portion of the threaded joint is not hindered by a solid corrosion protective coating. The addition amount of these fluorescent materials, for UV-curable resin 1 at a weight ratio, it is preferred that up to maximum of about 0.05. It exceeds 0.05 when the corrosion resistance may be lowered. More preferred amount by weight ratio of 0.02 or less. Furthermore not only the solid corrosion protective coating, to enable quality control of the threaded portion of the base, a fluorescent material as a coloring agent, it is particularly preferred to use a fluorescent pigment.
[0100]
　After coating composition mainly composed of a UV-curable resin (including a composition consisting of only the ultraviolet curable resin composition) on the contact surfaces of the threaded joint, an ultraviolet curable resin layer by ultraviolet ray is irradiated to cure the coating solid corrosion protective coating consisting of is formed.
[0101]
　By repeating the coating and the ultraviolet radiation, it may form a solid corrosion protective coating consisting of two or more layers of UV-curable resin layer. If you like this multi-layered solid corrosion protective coating, further increases the film strength, looks like a solid corrosion protective coating is not destroyed even by a force applied at the time of tightening of screw joints, corrosion resistance of the threaded joint is further improved. In the present invention, since the bottom of the solid corrosion protective coating there is no lubricating coating is not necessary the solid corrosion protective coating is destroyed during the tightening of the threaded joint, Write solid corrosion protective coating is not destroyed, the corrosion resistance of the threaded joint higher.
[0102]
　Ultraviolet rays can be irradiated by using an ultraviolet irradiation apparatus having an output wavelength of a general commercial 200 ~ 450 nm range. The illumination source of the ultraviolet light, for example, a high-pressure mercury lamp, ultrahigh-pressure mercury lamp, xenon lamp, carbon arc lamps, metal halide lamps, sunlight, and the like. Irradiation time and the irradiation intensity of ultraviolet can be appropriately set by those skilled in the art.
[0103]
　The solid corrosion protective coating with a thickness (in the case of two or more layers of UV-curable resin layer is a total film thickness) is preferably in the range of 5 ~ 50μm, and more preferably in the range of 10 ~ 40μm. Further, it is preferable to be smaller than the thickness of the solid lubricating coating to be formed on the mating member. If the thickness of the solid corrosion protective coating is too thin, not sufficiently function as a corrosion protective coating, there is a case where the corrosion resistance of the pipe thread joint becomes insufficient. On the other hand, when the film thickness of the solid corrosion protective coating is greater than 50μm, when mounting a protective member such as a highly airtight protector to the pipe end of the oil country tubular goods, it may be solid corrosion protective coating is destroyed by the force at the time of protector attached , also the corrosion resistance of the pipe thread joints becomes insufficient. Further, since it is discharged to the environment become abrasion powder in the working environment is pressure. The thickness of the solid corrosion protective coating is to inhibit and larger than the thickness of the solid lubricant film of the other party member, the lubrication performance of the lubricant film.
[0104]
　The solid corrosion protective coating consisting mainly of ultraviolet curing resin, since it is transparent film, it is possible to observe the state of the green body without removing the coating, that an inspection of the threaded portion of the front clamping carried from the top of the film it is possible. Accordingly, the solid corrosion protective coating, the threaded portion is formed on the outer surface, forming a more contacting surface of susceptible pin to damage, typically formed on the outer surface of a steel pipe tube end, susceptible pin to damage the presence or absence of damage to the threaded portion, it is possible to easily inspect leaving the coating.
[0105]
　[Background Processing
　screw portion and the sealing portion is the contact surface of the pipe thread joint is formed by cutting, including threaded, it is generally the surface roughness is about 3 ~ 5μm. When the surface roughness of the contact surface is larger than this, it is possible to enhance the adhesion of the coating to be formed thereon, it can be a result improve the performance such as the seizure resistance and corrosion resistance as. For this purpose, at least one member of the pin and box, preferably to the contact surface of both members, prior to the film formation, it is preferably subjected to surface treatment capable of increasing the surface roughness.
[0106]
　Examples of such surface treatment, blasting shape projects a blasting material such as spherical shot material or horn-shaped grid member, or, by soaking sulfuric, hydrochloric, in a strong acid solution such as nitric or hydrofluoric acid include pickling roughening the skin. These are processes which can increase the surface roughness of the base material itself.
[0107]
　As an example of another of the underlying processing, phosphate chemical conversion treatment, oxalate chemical conversion treatment, chemical conversion treatment such as boric acid salt chemical conversion treatment, and it includes a metallic plating. These are methods in which a large surface roughness, and a high adhesion underlayer film formed on the base material surface. In the chemical conversion treatment, a large chemical conversion film surface roughness consisting of acicular crystals are formed. As metallic plating, (because the convex portions are plated preferentially a slightly rougher surface) copper by electroplating method, iron, plating such as their alloys, zinc or zinc iron core - Iron the particles coated with alloy and projected using centrifugal force or air pressure, the zinc or zinc - iron alloy particles are deposited impact plating of a porous metal coating of zinc or zinc alloy is formed, or, in the metal composite metal plating, and the like to form a dispersed coating the solid fine particles.
[0108]
　Also surface treatment of the contact surfaces In either method, it is preferable that the surface roughness Rmax is set to be a 5 of 5 ~ 40 .mu.m by roughening by surface treatment. Rmax is less than 5 .mu.m, there is the adhesion of the film to be formed thereon becomes insufficient. On the other hand, if Rmax exceeds 40 .mu.m, friction becomes high, the film can not withstand the high surface pressure receiving shear force during the compression force, which may be easily broken or peeled off. Surface treatment for surface roughening may be used in combination of two or more processes. It may be subjected to different surface treatment with the pin and the box.
[0109]
　From the viewpoint of adhesion of the solid corrosion protective coating or solid lubricating coating, preparatory surface treatment which can form a porous coating is preferred. In particular manganese phosphate, zinc phosphate, and phosphate treatment using iron phosphate manganese or zinc phosphate calcium, zinc or zinc by impact plating - Formation of coating iron alloy is preferred as preparatory surface treatment. Manganese phosphate coating from the standpoint of adhesion of the coating formed on the above, from the viewpoint of corrosion resistance, zinc or a zinc sacrificial protection ability of zinc can be expected - iron alloy coating are preferred.
[0110]
　Particularly preferred as a base treatment of the solid lubricant film is a manganese phosphate chemical conversion treatment, Particularly preferred as a base treatment of the solid corrosion protective coating is zinc or zinc by zinc phosphate chemical conversion treatment, and impact plating - is the iron alloy plating .
[0111]
　Zinc or zinc is formed by coating and impact plating formed by phosphating - Iron alloy coating are both porous coating. When thereon to form a solid corrosion protective coating or a solid lubricating coating, the adhesion of the coating is increased by the so-called "anchor effect" of the porous coating. As a result, it becomes difficult to occur the peeling of the solid lubricating coating even after repeated tightening and loosening is metal-to-metal contact is effectively prevented, galling resistance, airtightness, the corrosion resistance is further improved.
[0112]
　Phosphating may be carried out by immersion or spraying in a conventional manner. As the chemical conversion treatment liquid, an acidic phosphating solution for a typical galvanized material can be used. For example, it is possible to phosphate ion 1 ~ 150g / L, zinc ions 3 ~ 70g / L, nitrate 1 ~ 100g / L, the zinc phosphate conversion treatment of nickel ions 0 ~ 30g / L exemplified. Further, manganese phosphate-based chemical conversion treatment solution which is commonly used threaded joints can also be used. Solution temperature may at 0.89 ° C. from room temperature, the treatment time may be performed by for up to 15 minutes depending on the desired film thickness. In order to promote a film of, before the phosphate treatment, it is also possible to supply the surface conditioning for an aqueous solution containing colloidal titanium on the treated surface. After phosphating, after washing with water or hot water, it is preferably dried.
[0113]
　Impact plating can be carried out and mechanical plating of colliding a particle and the object to be plated in a rotating barrel, by a projection plating to collide with the object to be plated particles using a blasting apparatus. Since the present invention may be Hodokose plating only on the contact surface, it is preferable to employ a localized plating is possible projection plating. For example, iron-based nuclei surfaces of zinc or zinc alloy (e.g., zinc - iron alloy) a projection material composed of particles coated with, can be projected on the contact surface to be coated. It is preferred that the content of zinc or zinc alloy in the particles is in the range of 20 to 60 wt%, the particle diameter of the particles is preferably in the range of 0.2 ~ 1.5mm. By the projection, only zinc or zinc alloy is a coating layer of the particles adheres to the contact surface, the porous coating is formed on the contact surface consisting of zinc or zinc alloy. This projection plating, irrespective of the material of the steel, it is possible to form a good plating film adhesion to the steel surface.
[0114]
　The thickness of the impact zinc formed by plating or zinc alloy layer is preferably from both sides of the corrosion resistance and adhesion is 5 ~ 40μm. If it is less than 5 .mu.m, while there is a sufficient corrosion resistance can not be secured, and when it exceeds 40 .mu.m, may be adhesion to the lubricating coating decreases rather. Similarly, the scope of the 5 ~ 40μm thickness of the phosphate coating is preferred.
[0115]
　Another surface treatment, although roughening effect is not, a particular single-layer or multi-layer electroplating, is particularly effective in enhancing the seizure resistance when used as an underlying solid lubricating coating. Examples of such plating, Cu, single-layer plating by Sn or Ni metal, or JP monolayers plated by Cu-Sn alloy as described in 2003-074763 discloses a Cu layer and a Sn layer 2-layer plating of news Ni, Cu, include three-layer plating by Sn layers. For steel pipe Cr content is 5% or more of steel, Cu-Sn alloy plating, two-layer plating of Cu plating -Sn plating, three-layer plating of Ni plating -Cu plating -Sn plating is preferred. More preferably, two-layer plating of Cu plating -Sn plating, and Ni strike plating -Cu plating -Sn 3-layer plating of plating, which is an alloy plating of the Cu-Sn-Zn. Such metal or metal alloy plating can be carried out according to the method as described in JP-A-2003-074763. For multilayer plating, the lowermost plated layer (usually Ni plating) is referred to as a strike plating, it is preferable that a plating layer of very thin less than the film thickness 1 .mu.m. Plating thickness (total thickness in the case of multilayer plating) is preferably in a range of 5 ~ 15μm.
Example
[0116]
　Below, a description will be given of an embodiment of the present invention. However, the present invention is not intended to be limited by the examples. In an embodiment, the contact surface of the pin pin surface, the contact surface of the box that the box surface. Further, percentages and parts in the examples, unless otherwise specified, respectively% by weight and parts by weight.
[0117]
　[The present invention Example 1]
　Nippon Steel Sumitomo Metals Co., Ltd. of pipe thread fittings VAM21 (registered trademark) (outer diameter: 24.448cm (9-5 / 8 inch), wall thickness: 1.199cm (0.472 inch)), steel grade carbon steel (C: 0.21%, Si: 0.25%, Mn: 1.1%, P: 0.02%, S: 0.01%, Cu: 0.04% , Ni: 0.06%, Cr: 0.17%, Mo: 0.04%, balance: the pin surface and the box surface of iron and impurities), were subjected to a surface treatment as follows.
[0118]
　Pin surface was finished by machine grinding (surface roughness of 3μm), it was immersed in the chemical conversion treatment solution for zinc phosphate of 75 ~ 85 ℃ 10 minutes, forming a thickness 10μm of the zinc phosphate coating (surface roughness 8μm) did. On the other hand, the box surface was finished by machine grinding (surface roughness of 3μm), in a manganese phosphate chemical conversion treatment solution of 80 ~ 95 ℃ and immersed for 10 minutes, with a thickness of 12μm manganese phosphate coating (surface roughness 10μm) the formed.
[0119]
　下記組成を有する固体潤滑被膜形成用組成物を撹拌機付きタンク内で１２０℃に加熱して塗布に適した粘度を有する溶融状態にし、一方、上記のように下地処理したピン表面及びボックス表面も誘導加熱により１３０℃に予熱した後、保温機能付きの噴霧ヘッドを有するスプレイガンを用いて、基剤樹脂が溶融状態になった表１の本発明例１に示す固体潤滑被膜形成用組成物を、ピン表面とボックス表面の両方に塗布した。冷却後に平均厚さ３０μｍの固体潤滑被膜が形成された。なお表１は、本発明例１、後述する本発明例２～８、比較例１～６のそれぞれについて、潤滑被膜形成用組成物の成分組成（質量％）、ポリオレフィン樹脂に対するエチレン酢酸ビニル樹脂の質量比（ＥＶＡ／ＰＯ）、ＷＡＸに対する前記両樹脂の質量和との割合（（ＥＶＡ＋ＰＯ）／Ｗ）及び組成物全体に対する結合剤の質量割合の和（質量％）を表している。
[0120]
[Table 1]

[0121]
　The composition of the lubricating coating composition of the present invention Example 1 is as follows. It should be noted that, as described above, the content (%) is, in particular, shows a mass% unless otherwise specified.
　(Binder)
　　, ethylene vinyl acetate resin: 21.6 percent
　　, polyolefin resin: 16%
　　wax (paraffin wax, melting point ℃ 69): 32.4 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 10%
　　- fluorinated polymer: 4%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 5 Pasento
　　-graphite fluoride (CFx): 4%
　(rust-preventive
　　agent) , Ca ion exchange silica: 5 %
　　, phosphorous acid aluminum: 2%
[0122]
　For the present invention in Example 1, it was carried out at a low temperature of tightening and loosening test of repeated up to 10 times of the pipe thread fittings (tightening speed 10rpm, tightening torque 42.8kN · m) at about -40 ℃. Specifically, after cooling the peripheral screw fastening unit to about -40 ℃ by dry ice, it was tightening and loosening test. As a result, even when cooled to -40 ° C., cracking or peeling the solid lubricating coating was not or to occur. Burn-in status of the pin and the box of the contact surface after repeated conclusion (the number of times that can be entered into without causing a burn-in (up to 10 times), It should be noted that, in the case of with recoverable minor burn, continue tightening to repair) investigate the did. The results are shown in baking occurrence of Table 2. After cooling to -40 ℃ as in the well first second and subsequent result of the tightening and loosening test, no generation of seizure, could be ten times fastening and loosening.
[0123]
[Table 2]

[0124]
　As shown in Table 2, JIS Z2371: was carried salt spray test according to 2000. As a result, the present invention Example 1 did not rust even after 1000 hours. In the present study, if no rust 750 hours, long-term rustproofing performance in actual tubes be sufficient is known from previous experience.
[0125]
　In addition, the ambient temperature is at room temperature (about 25 ℃) and -40 ℃, in order to measure the adhesion strength of the solid lubricant film, were carried out shear tensile test (Shear TEST). Hereinafter, a specific method of the shear tension test, will be described with reference to FIG.
[0126]
　First, a length 75 mm, width 25 mm, two metal plates having a thickness of 0.8 mm (for example carbon steel) were prepared 28 and 30, the 25 mm × 25 mm area of ​​the two metal plates, having a thickness of 50μm solid to form a lubricating coating 32. Specifically, 50μm of the PTFE-made sheet 34 is thick, sandwiched in position between the metal plate 28 and 30 as a sheet for setting the film thickness, coated with a solid lubricating coating composition was heated to 120. ° C. after the two metal plates (the vertical direction in FIG. 4) pressed by cooling, to form a coating film 32.
[0127]
　Next, remove the PTFE sheet 34, the one end of each of the metal plates 28, 30 gripping with a suitable chuck 38, and located throughout the schematic illustrated chamber 42, the chamber 42 25 It was held in ℃ or -40 ℃. In this state, the load F when the chuck 38 away from each other about the length direction of the metal plate (i.e. the direction in which acts a shear force to the film 32) is moved at 50 mm / min, the film 32 is broken the (kPa) was measured. Table 2 shows the results. The present invention Example 1, as compared with the conventional Comparative Examples 1 and 2 described below, 25 ° C., to -40 ℃ both temperature co, it was confirmed that high remarkably adhesion strength. Pass line of adhesion strength was 25 ℃, -40 ℃ both 1500kPa or more.
[0128]
　Furthermore, the actual tightening and loosening test threaded joint which forms the same solid lubricating coating and when performed (box), were examined the deterioration degree of the solid lubricating coating is exposed to outdoor environment after exposure given time at low temperature (low temperature - outdoor exposure test). More specifically, as schematically illustrated in the flow chart of FIG. 5, first ensure that there is no peeling or cracking in the solid lubricating coating of a threaded joint in the initial state (step S1), and then, the protector the threaded joint in the attached state exposed for 24 hours at a low temperature of -60 ℃ (step S2), and then, to confirm the state of peeling or cracking Remove the protector (step S3). Next, attach the protector to the screw joint, exposed again for 24 hours at a low temperature of -60 ℃ (step S4), and then, to confirm the state of peeling or cracking Remove the protector (step S5). Finally, (once a day) regularly outdoors while peppered the water of the shower left for 1 year (step S6), and low-temperature degradation of solid lubricant coating of a threaded joint, ie low temperature - peeling due to the ambient temperature cycle a-cracking of the situation was investigated (step S7).
[0129]
　The above-mentioned low temperature - Table 2 shows the results of outdoor exposure test. In the present invention Example 1, even when exposed to a low temperature of -60 ° C. a total of 48 hours, low temperature - even under the temperature difference at ambient temperature, after outdoor exposure for one year even cracking of the solid lubricant film, peeling, blistering (lifting of the film) was not at all occur. Note Table 2, Inventive Example 1, Inventive Examples 2-8 to be described later, for each of Comparative Examples 1-6, above seizing occurrence, salt spray test, shear tensile test and low temperature - the result of outdoor exposure test It represents.
[0130]
　[Inventive Example 2]
　on the pin surface and the box surface of the present invention Example 1 The same carbon steel pipe thread fittings as used in, subjected to surface treatment as follows.
[0131]
　Pin surface was finished by machine grinding (surface roughness of 3μm), was immersed in the chemical conversion treatment solution for zinc phosphate of 75 ~ 85 ℃ 10 minutes, forming a thickness 8μm of zinc phosphate coating (surface roughness 8μm) did. Further on it, as a UV-curable resin composition for forming a coating film, acrylic resin-based ultraviolet curable resin coating material, to 1 part resin in the paint, aluminum phosphite 0.05 parts of the anti-rust agents in the mass ratio and a polyethylene wax 0.01 parts of a lubricant coating was applied by adding, by irradiating ultraviolet rays under the following conditions to cure the coating, thereby forming an ultraviolet curing resin film having a thickness of 25 .mu.m. The formed solid corrosion protective coating is a colorless and transparent, it was possible to inspect the male threaded portion with the naked eye or magnifying glass from the top of the coating.
[0132]
　UV lamp: air-cooled mercury lamp
　UV lamp output: 4kW
　ultraviolet wavelength: 260nm
[0133]
　The box surface was finished by machine grinding (surface roughness of 3 .mu.m), first Ni strike plating by electroplating, then subjected to a Cu-Sn-Zn alloy plating to form a total 8μm thickness of the plated film. Then, the molten state having a viscosity suitable for coating by heating to 120. ° C. with a stirrer with a tank a lubricating coating composition having the following composition, whereas, the box surface also induction heating was primed as above was preheated to 130. ° C. was thus coated with a solid lubricating coating composition in a molten state by a spray gun having a spray head with a heat insulation function. After cooling, the average thickness of 50μm solid lubricating coating was formed.
[0134]
　The composition of the lubricating coating composition of the present invention Example 2 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 17%
　　, polyolefin resin: 12.2%
　　wax (paraffin wax, melting point ℃ 69): 36.8 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 10%
　　- fluorinated polymer: 7%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 10%
　(rust-preventive
　　agent) , Ca ion exchange silica: 5%
　　, phosphorous acid aluminum: 2%
[0135]
　The present invention example 2, the test loosening and tightening of the repetition of the pipe thread joints was conducted in the same manner as Working Example 1. The results are shown in Invention Example 2 of Table 2. Various excellent effect similar to that of the present invention Example 1 was confirmed.
[0136]
　[The present invention Example 3]
　In the present invention Example 1 with the same screw type, seizure is likely to occur 13Cr steel than carbon steel (C: 0.19%, Si: 0.25%, Mn: 0.9%, P: 0.02%, S: 0.01%, Cu: 0.04%, Ni: 0.11%, Cr: 13%, Mo: 0.04%, the balance being iron and impurities) made of pipe thread fittings ( outer diameter: 24.448cm (9-5 / 8 inch), wall thickness: 1.105cm to (0.435 inches)) pin surface and the box surface was subjected to surface treatment as follows.
[0137]
　Pin surface was finished by machine grinding (surface roughness of 3 .mu.m), as an ultraviolet curable resin coating composition, an acrylic resin-based UV-curable resin coating material, relative to 1 part resin in the paint, anti at a mass ratio 0.05 parts of tripolyphosphate aluminum rust agent, 0.01 parts of polyethylene wax lubricant, and a coating material obtained by adding a fluorescent pigment 0.003 parts of coating was irradiated with ultraviolet rays to cure the coating under the following conditions, the thickness to form a 25μm of ultraviolet curing resin coating. Formed coating was colorless and transparent, and can be inspected from the top of the coating the external thread portion with the naked eye or magnifying glass.
[0138]
　UV lamp: air-cooled mercury lamp
　UV lamp output: 4kW
　ultraviolet wavelength: 260nm
[0139]
　The box surface was finished by machine grinding (surface roughness of 3 .mu.m), first Ni strike plating by electroplating, then subjected to a Cu-Sn-Zn alloy plating to form a total 8μm thickness of the plated film. Then heated to 120. ° C. with a stirrer with a tank a lubricating coating composition having the following composition, having a viscosity suitable for coating, base is the composition in a molten state, whereas, as described above after the foundation treated box surface is also preheated to 130 ℃ by induction heating, it was coated with a solid lubricating coating composition for forming a molten state by a spray gun with a spray head with a heat insulation function. After cooling, the average thickness of 25μm solid lubricating coating was formed.
[0140]
　The composition of the lubricating coating composition of the present invention Example 3 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 22%
　　, polyolefin resin: 21%
　　wax (paraffin wax, melting point 69 ℃): 31 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 10%
　　Fluorine polymer: 4%
　(solid
　　lubricant) - PTFE: 10 Pasento
　(rust-preventive agent)
　　, phosphorous acid aluminum: 2%
[0141]
　For the present invention Example 3, the test loosen the tightening of the repetition of the pipe thread fittings, it was carried out in the same manner as the first example of the present invention. The results are shown in the present invention Example 3 of Table 2. Similar various excellent effects as Working Example 1 and 2 were confirmed.
[0142]
　[Inventive Example 4]
　Inventive Example 1 and the same pipe thread fittings, using a steel type, after the surface treatment of the present invention Example 2 was formed on the pin and box, the lubricating coating composition having the following composition stirrer was heated in a tank 120. ° C. per has a viscosity suitable for coating, base is the composition in a molten state, whereas, after preheated to 130. ° C. by also induction heating undercoat treated box surface as described above , it was coated with a solid lubricating coating composition for forming a molten state by a spray gun with a spray head with a heat insulation function. After cooling, the average thickness of 30μm solid lubricating coating was formed.
[0143]
　The composition of the lubricating coating composition of the present invention Example 4 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 26%
　　, polyolefin resin: 16%
　　wax (paraffin wax, melting point 69 ℃): 37 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 9%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 5 Pasento
　　-graphite fluoride (CFx): 4 Pasento
　(rust-preventive agent)
　　, phosphorous acid aluminum: 3%
[0144]
　The present invention example 4, the test loosening and tightening of the repetition of the pipe thread joints was conducted in the same manner as Working Example 1. The results are shown in the present invention example 4 in Table 2. Similar various excellent effects as the present invention Examples 1-3 was confirmed.
[0145]
　[Inventive Example 5]
　Inventive Example 1 and the same pipe thread fittings, using a steel type, after the surface treatment of the present invention Example 2 was formed on the pin and box, the lubricating coating composition having the following composition stirrer was heated in a tank 120. ° C. per has a viscosity suitable for coating, base is the composition in a molten state, whereas, after preheated to 130. ° C. by also induction heating undercoat treated box surface as described above , it was coated with a solid lubricating coating composition for forming a molten state by a spray gun with a spray head with a heat insulation function. After cooling, the average thickness of 30μm solid lubricating coating was formed.
[0146]
　The composition of the lubricating coating composition of the present invention example 5 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 21.6 percent
　　, polyolefin resin: 16%
　　wax (polyethylene wax, melting point ℃ 110): 32.4 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 10%
　　- fluorinated polymer: 4%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 5 Pasento
　　-graphite fluoride (CFx): 4%
　(rust-preventive
　　agent) , Ca ion exchange silica: 5 %
　　, phosphorous acid aluminum: 2%
[0147]
　For the present invention Example 5, the test loosen the tightening of the repetition of the pipe thread fittings, it was carried out in the same manner as the first example of the present invention. The results are shown in the present invention Example 5 of Table 2. Compared to the present invention Examples 3 and 4, probably because the sum of the proportions by weight of the binder was as low as 70%, although the adhesive strength of the shear tension test at 25 ° C. was sufficient, the tensile shear at -40 ℃ test adhesion strength of was slightly lower. In the present invention Example 5, the difference between the adhesion strength of about room temperature, and the adhesion strength of the cryogenic environment is increased. Furthermore, although until the seventh time in the tightening and loosening test at -40 ℃ the seizure did not occur, with minor burn occurs in the threaded portion on the 8th, it was to complete the care to test up to 10 th. In addition, low temperature - even in the outdoor exposure test, or is exposed to a low temperature, low temperature - even if or receive the temperature difference between the ambient temperature, but is cracking and peeling did not occur, minor solid after outdoor exposure of one year the peeling of the lubricant film (floating coat) is generated was observed. However, this peeling was level with no problem in practical use.
[0148]
　[Inventive Example 6]
　Inventive Example 1 and the same pipe thread fittings, using a steel type, after the surface treatment of the present invention Example 2 was formed on the pin and box, the lubricating coating composition having the following composition stirrer was heated in a tank 120. ° C. per has a viscosity suitable for coating, base is the composition in a molten state, whereas, after preheated to 130. ° C. by also induction heating undercoat treated box surface as described above , it was coated with a solid lubricating coating composition for forming a molten state by a spray gun with a spray head with a heat insulation function. After cooling, the average thickness of 30μm solid lubricating coating was formed.
[0149]
　The composition of the lubricating coating composition of the present invention Example 6 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 20.5%
　　, polyolefin resin: 19.5%
　　waxes (polyethylene wax, melting point ℃ 78): 36 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 8%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 7 Pasento
　(rust-preventive agent)
　　, Ca ion exchange silica: 3%
　　, phosphorous acid aluminum: 4%
　(friction modifier)
　　, talc (particle diameter 4.5 .mu.m, a specific surface area of 9.5 m 2 / g): 2%
　particle diameter of the talc laser diffraction type particle size distribution measuring apparatus (manufactured by Shimadzu Corporation, was SALD-2000J) with a determined as described above. The specific surface area of the talc was determined as described above.
[0150]
　For the present invention Example 6, the test loosening and tightening of the repetition of the pipe thread fittings, was carried out in the same manner as the first example of the present invention. The results are shown in the present invention Example 6 of Table 2. Similar various excellent effects as the present invention Examples 1 to 4 were confirmed.
[0151]
　For invention sample 6, further the difference between the yield torque and shouldering torque was measured as follows. Prepare the threaded joint samples were fastened with a suitable torque wrench. By performing even tightening give further torque after engagement, to produce a torque chart as shown in FIG. Shouldering torque, the difference between the yield torque and yield torque and the shouldering torque was measured on the torque chart. Shouldering torque shoulder portion is in contact, the torque value when the torque change began away from the first linear zone (elastic deformation range). On the other hand, yield torque is the torque value at which plastic deformation starts. Specifically, it occurs after reaching the shouldering torque, a torque value when started away from the second linear region. The results are shown in the present invention Example 6 of Table 2. If the difference between the yield torque and shouldering torque of the present invention Example 3 was 100, the difference between the yield torque and shouldering torque of the present invention Example 6 exhibited 120 becomes excellent over torque performance.
[0152]
　[Invention Example 7]
　Inventive Example 1 and the same pipe thread fittings, using a steel type, after the surface treatment of the present invention Example 2 was formed on the pin and box, the lubricating coating composition having the following composition stirrer was heated in a tank 120. ° C. per has a viscosity suitable for coating, base is the composition in a molten state, whereas, after preheated to 130. ° C. by also induction heating undercoat treated box surface as described above , it was coated with a solid lubricating coating composition for forming a molten state by a spray gun with a spray head with a heat insulation function. After cooling, the average thickness of 30μm solid lubricating coating was formed.
[0153]
　The composition of the lubricating coating composition of the present invention Example 7 is as follows.
　(Binder)
　　, ethylene vinyl acetate resin: 20.5%
　　, polyolefin resin: 19.5%
　　waxes (polyethylene wax, melting point ℃ 78): 33 Pasento
　(fluorine-based
　　additive) , PFPE (perfluoropolyether): 8%
　(solid lubricant)
　　, earthy graphite (average particle size 7Myuemu): 7 Pasento
　(rust-preventive agent)
　　, Ca ion exchange silica: 3%
　　, phosphorous acid aluminum: 4%
　(friction modifier)
　　, talc (particle diameter of 3.3μm, specific surface area 12.0M 2 / G): 5 Pasento
　particle size and specific surface area of the talc was obtained in the same manner as in the present invention example 6.

The scope of the claims
[Claim 1]
　A composition for forming a solid lubricating coating to the pipe threaded joint,
　a binder,
　a fluorine-based additive,
　and solid lubricant,
　contains a rust preventive additive,
　said binder is
　ethylene vinyl acetate and resin,
　and a polyolefin resin,
　the melting point is contained and 110 ℃ or less of wax,
　the ratio of the mass of the ethylene vinyl acetate resin with respect to the mass of the polyolefin resin is 1.0 to 1.8, and
　with respect to the mass of the wax , wherein the ratio of the total mass of the polyolefin resin and the ethylene-vinyl acetate resin is from 0.7 to 1.6 composition.
[Claim 2]
　A composition according to claim
　1, and 60 to 80 wt% of said
　binder, and 8-18% by weight of the fluorine-based
　additive, and said solid lubricant of from 5 to 15
　wt%, 2 - characterized in that it contains a 10 wt% the rust-preventive additive composition of claim 1.
[Claim 3]
　Furthermore a claim 1 or composition according to claim 2,
　characterized in that it contains talc 2 to 15 wt%, the composition.
[Claim 4]
　A composition according to claim 3,
　particle diameter of the talc is the 1 ~ 12 .mu.m, specific surface area of the talc ~ 12m 4 2 characterized in that it is a / g, the composition.
[Claim 5]
　A pipe thread joint comprising a pin and the box,
　each of said pin and said box is provided with a contact surface including a portion in contact with each other, said pipe thread joint, said pin and at least one of the contact surfaces of the box comprising a solid lubricant film above,
　the solid lubricant coating,
　a binder,
　a fluorine-based additive,
　and solid lubricant,
　contains a rust preventive additive,
　wherein the binding agent is
　a ethylene vinyl acetate resins,
　polyolefin and resin,
　and contains a melting point of 110 ℃ or less of the wax,
　the ratio of the mass of the ethylene vinyl acetate resin with respect to the mass of the polyolefin resin is 1.0 to 1.8, and
　with respect to the mass of the wax, the polyolefin resin and wherein the ratio of the total mass of the ethylene-vinyl acetate resin is from 0.7 to 1.6 pipe threaded joint.
[6.]
　A pipe thread joint according to claim 5,
　wherein the solid lubricating coating is
　60 to 80 mass% of the binder,
　and 8-18% by weight of the fluorine-based additive,
　the 5 to 15 wt% a solid lubricant,
　comprising a 2-10 wt% of the anti-rust additive, pipe threaded joint.
[7.]
　A pipe thread joint according to claim 5 or claim 6,
　wherein the solid lubricating coating is further
　characterized by containing 2 to 15 wt% of talc, Pipe threaded joint.
[8.]
　A pipe thread joint according to claim 7,
　wherein a particle diameter of 1 ~ 12 .mu.m talc, specific surface area of the talc 4 ~ 12m 2 , characterized in that a / g, Pipe threaded joint.
[9.]
　Furthermore a pipe thread joint according to any one of claims 5 to claim 8,
　comprising a solid corrosion protective coating containing an ultraviolet curable resin,
　the solid lubricant coating, one of the said pin and said box is formed on the contact surface, the solid corrosion protective coating is characterized by being formed on said pin and the other of the contact surface of the box, pipe threaded joint.
[10.]
　A pipe thread joint according to claim 9,
　wherein the thickness of the solid corrosion protective coating is 5 of 5 ~ 50 .mu.m, Pipe threaded joint.
[11.]
　A pipe thread joint according to any one of claims 5 to claim 10,
　wherein the thickness of the solid lubricating coating is 10 - 200 .mu.m, Pipe threaded joint.
[12.]
　A pipe thread joint according to any one of claims 5 to claim 11,
　characterized in that it is used for oil country tubular goods, pipe threaded joint for.
[13.]
　And a pin and the box, each of said pin and said box is provided with a contact surface including a portion in contact with each other, to said pin and at least one of said contact surface of said box comprises a solid lubricating coating, the pipe threaded joint a manufacturing method,
　and further comprising a step of forming the solid lubricating coating composition was applied on the contact surfaces according to any one of claims 1 to 4 to the contact surface the method of manufacturing a pipe thread fittings.
[14.]
　A method of manufacturing a pipe thread joint according to claim 13,
　wherein in the step of forming a solid lubricating coating, the solid lubricating coating was formed on the pin and one said contact surface of the box,
　the production method further,
　the pin and the other of the contact surfaces of the box, a step of applying a composition for a solid corrosion protective coating comprising the ultraviolet-curing resin,
　irradiating ultraviolet light to the composition for coated the solid corrosion protective coating It said solid characterized in that it comprises a step of forming a corrosion protective coating, the manufacturing method of the pipe thread fittings and.