Specification [Title of the invention] LUBRICANT FILM-FORMING COMPOSITION AND SCREW JOlNT FOR STEEL PIPE [Technical Field of the Illvention] [OOOl] The present invention relates to a lubricant film-fonning composition and a screw joint for a steel pipe. Priority is claimed on Japanese Patent Application No. 2013-181623, filed Septen~be2r ,2013, tlie contents of which are incorporated herein by reference. [Related Art] [0002] An oil well pipe, which is used to drill an oil well and includes tubing through wvbich a fluid such as crude oil flows and a casing that sllrrol~tidstl ie htbing, is generally assembled by fastening steel pipes having lengths of about several tens of meters with screw joints at a site. Typically, the depth of an oil nrell is 2,000 m to 3,000 111. Howwrever, in recent years, the depth of a deep oil well such as an undersea oil well may reach 8,000 m to 10,000 tn. [0003] On the serew joint for a steel pipe n4iich fastens the oil well pipes, in addition to an axial tensile force caused by the weight of the oil wvell pipes and the joint under the use environment, a coniplex pressure such as internal and external contact pressure, and heat are applied. Therefore, for the screw\: resulting in plastic deformation. An object of fonning the lubricant film on the screw joint for a steel pipe is to prevent seizure even under sucll severe li~bricationc onditions. Therefore, introdnction of a lubricity imparting con~ponentto a fiiction surface and n~aintenanceth ereof are essential. [O059] Therefore, a necessary arnoutit of the lubricant film-forniing cotnposition for filling the small gap 6 of the fitting part between screw threads shown in FIG. 3 needs to be applied. When tlie application amout~its small, due to the hydrostatic pressure generated during the fastening, an action of the oil leaching into the friction surface or an action of the lubricity imparting component flowing around from the other gap cannot be expected. Therefore, it is preferable that the thickness of tlie lubricant film be 10 ~unor more. [0060] Since the fitting parts of the pin 1 and the box 2 collie into contact \$it11 each other during the fastening of the screw joints for a steel pipe, in terms of securing lubricity, it is sufficient to apply the lubricant film only to the fitting part of any one of the pin 1 and the box 2. However, in order to secure antirust properties, it is necessary to form the lubricant films on the fitting parts of both the pin I and tlie box 2. Since the minimum thickness necessary for the antirust properties is also 10 11111, it is preferable that the lubricant frlnl having a thickness of 10 pm or more be fonned on each of both of the fitting parts. Here, as shown in FIG. 1, in a case where the coupling B is fastened to one end of the oil well pipe A at the tinie of shipping, wwrhen the lubricant film is fornled only on the fitting part of one tnetnber of the pin I and the box 2 on a side whore the fastening is perfor~i~edth,e fitting patts of both tlie pin 1 and the box 2 are coated with the lubricant films, and thus the antirust properties are also imparted. However, the lubricant filtns are fortned on both the pin 1 and tlie box 2 (the pin on the left side and the box on the right side in the showvn exaaiple) on tlie opposite side. ed of the lubricant film-forniitig conipositiou of - 21 - this eil~bodimenht as Iligh lubricity, the lubricant filtn does not need to be thick more than necessary. The ruaterial becomes useless when the lubricant film is too thick, and is also against the prevention of the environmental pollution which is one of the objects of this embodiment. Therefore, the upper linlit of the film thickness is preferably about 200 [un although not being particularly limited. A tnore preferable filtn thickness of the lubricant film is 30 to 150 pm. I-Iere, as described belo\\; in a case \vl~ereth e surface rougl~nesso f the applied fitting part needs to be high, it is preferable that the film tl~icknesso f tbe lubrica~itf ilm be greater than the surface rougl~nessR ,,,, of the fitting surface. In a case wllere surface rough~~eisss p rovided, the filtn thickness ofthe lubricant filn~is an intermediate value between the maximum and the minirllum of the film thickness. [0062] The lubricant film-fonning con~positiono f this embodiment may contain a dissolution base for facilitating application. In this case, the conlposition itself is not semi-solid, but may be in a liquid state having excellent applicability. However, \vhen the composition is applied to the fitting part of the scre\v joint for a steel pipe, since the dissolution base generally has volatility, the dissolution base is evaporated and removed from the fonned lubricaut film, and the lubricant film becon~ess emisolid. Ageneral~organics olvel~mt ay be used as the dissolution base. As an example of the dissolution base \vl~ichis appropriately used in this embodiment, there is a petroleum-based solvent including mineral spirits. As the application method, an appropriate method may be selected depending on the ptoperties of the lubricant film-fortning composition of this embodiment. For example, when the lubticant film-forlning compositiot~c ontains the dissolution base and is in a liquid state at roonl telnperature, a general application method such as spray coating, im~nersiono, r brush coating, may be en~yloyed. On the other hand, when the lubricant film-forming conlposition does not contain the dissolution base and is semisolid at room temperature, an application device (for example, a spray gun for hot-melt coating) provided wit11 a heating mechanism may be used for the application in a state where the paraffin wax ~~Ilicish th e solidif~~inagge nt is melted. In this case, in order to fonn the coating film having an unifornl thickness, it is preferable that the lubricant film-forming composition wvl~ich is p~e-heated be applied to the fitting part which is also pre-heated fro111 the splay gun provided with a heat insulating device which can maintain the pre-heated lubricant film-forming cotnposition in a constant temperature. [0064] [Surface Roughness of Fitting Part] 111 the fitting part constitoted by the tlueaded portions 3 and 4 and the unthreaded metal contact portions 5 of tile screw~rjoinfto r a steel pipe coated wit11 the lubricant film-forming composition of this emnbodiment, a surface roughness of 3 to 5 pm can be obtained by cutting work. When the surface ronghness is increased by an appropriate method, the lubricity is fi~rtherim proved. This is because the action of the oil leaching into the friction surface and the action of the lubricity imparting conlponeut flowving around fiotn the other gap due to the h~~drostatpicre ssule action of the fitting part described above occur due to the oil trapped in the fine oneven portions of the surface roughness. The actions can be achieved by surface roughness regardless of the method of imparting the surface rot~gluless. Apreferable surface roughness for enhancing the lub~icityis 5 to 40 pm in terms of R,,,,,. When the surface roughness is higher than 40 CIII in tert11s of R,,,,, the surroundings of the concave pol tions cannot be sufficiently sealed, the hydrostatic pressure action does not - 23 - occur, and thus s~iff~ciclnutb ricity cannot he obtained. A more preferable range of the R,,,, is 10 to 30 11111. [0065] The method of imparting surface roogliness is not particularly limited, and the following methods may be employed. (1) Projection of sand or grid: the surface roughness can be changed by the size of the projected abrasive grain. (2) Corrosion by acids: a method of immersing in a strong acid solution such as a sulfnric acid, a hydrocllloric acid, a nitric acid, and a hydrofluoric acid. (3) Phosphate treatment: treatment of coating manganese phosphate, zinc phosphate, iron nlanganese phosphate, and zinc calcium phosphate (the roughness of crystal surfaces is increased with the growth of generated crystals). (4) Electroplating: copper plating and iron plating (since convex portions are plated first, surfaces beconle slightly rough). As described above, tlie copper plating may also be perfonned to enhance the lubricity of the screw joint for a steel pipe. (5) Dry mechanical plating: a plating method of projecting grains coated \\fit11 a plating material onto an iron core wing a centrifugal force or air pressure, such as zinc blasting and zinc-ironalloy blasting. [0066] Such surface roughness imparting nletliods are easily performed on the box 2 side, but may also be perfornled 011 the pin 1 side or perfortned on both of tlie sides. In addition, since the niethods (3) to (5) are methods of fonning a base treahnent film having a high surface rou~ghness, contact between nletals is prevented by the film when e enhancement of the lubricity and the antirust properties - 24 - can be simultaneously obtained. For this reason, tlie methods (3) to (5) are preferable. Particularly, the manganese phosphate film has coarse surface grains and good oil holding properties of the oil, and thus is more appropriate. [0067] Depending on the material of the oil well pipe A, there niay be cases where the phosphate treatment cannot be perfortned due to high alloys. 111 this case, after performing the iron plating described in (4), the phosphate treatment may be performed. In a case of the base treatment fillns of (3) to (5), it is preferable that the thicknesses of tlie base treatment fil~nsb e greater than tlie surface mughliess imparted by the methods because the holding properties of the oil and the adhesion of the base film are enhanced. Therefore, it is appropriate that tlie film thickness of the base treatment film is 5 to 40 pm. [Examples] [0068] The lubricant film-forming eolnpositions of Exarnples 1 to 6 and Comparative Examples 1 to 9 showw~~iai Table 1 Itrere prepared. As described above, all % is shown in mass%. Among the used coniponents, the parafin wax was Parafin Wax 155 manufactured by Nippon Seiro Co., Ltd., calcium sulfonate was Calcinate (registered trademark) C-400W manufactured by Chen~turaC orporation, and petrolatum was was OX-1749 manufactured by Nippon Seiro Co., Ltd.. As the other components, chetnicals for illdustrial use were used. Commercially available eolupound grease of Comparative Exatnple 2 \\'as Type 3 nianufach~redb y Showa Shell Sekiyu K. K., and co~nmerciallya vailable biodegradable grease 3 was Bioteinp PL innnufactured by Kyodo Yushi Co., Ltd.. Aminera1 oil of Example 6 and Co~nparativeE xample 9 was a purified mineral oil raw material (viscosity grade: VG32) manofactured by Idemitsu Kosan Co., Ltd., and graphite was AGE-5 manufactured by Ito Graphite Co., Ltd.. [0069] [Table 11 - 60% Example I Paraffin wax 20% Pentaerythritol tetraoleate 70% Exatnple 2 Paraffin wax 15% Lithium hydroxystearate 15% Pentaerythritol tetraoleate 65% Example 3 1 Paraffin wax 10% Calcium hydroxystearate 12.5% ~ydrox~stea;icac id lithium 12.5% I Trimethylolpropane coconut oil fatty acid ester 40% 1Example 4 1 Paraffin wax 20%- I Trimethylol propane trioleate 80% Exa~nple 5 Paraffin wnu 10% Stearic acid litluum 10% Pentaelythritol tetraoleate 59.5% Paraffin wax 8.5% Example 6 Lithiutn hydroxystearate 17% Mineral oil 8% V " . L L ~ U " , ' L " ~ Example 1 Petrolatum wax 20% Stearic acid calciom 20% Cotnparative Exatnple 2 Commercially available compound grease I Comparative Example 3 Cotnmercially available biodegradable grease u'aprrrtc I% Basic calcium sulfonate 60% Comparative Trimethylol propane trioleate 70% Exanlple 4 Paraffin wax 30% Comparative Pentaerythritol tetraoleate 70% Example 5 Stearic acid calcium 30% Comparative Paraffin \\?ax 70% - Example 6 Lithium hydroxystearate 30% Colnparative Trimetl~ylolpropane coco~lut oil fatty acid ester 30% Example 7 Parafin wax 30% Stearic acid calcium 40% Co~n~arative Pentaerythritol tetraoleate 85% ~ x ~ t n p8l e Paraffin wax 5% Litlliurn hy~lroxystearate 10% Pentaerythritol tetraoleate 44% Comparative Paiaffin wax 4% Example 9 Lithium hydroxystearate 32% Mineral oil 10% Graphite 10% [0070] The lubricant film-forming compositiotl was applied to a surface of an appropriate base body for the test of each performance, thereby fornling a lubricant film. The application wwfas perfornled by the bnisli coating. Regardiug the formed lubricant film, biodegradability, lubricity, antirust properties, stickitless resistance, and corrosiveness to copper were examined by the methods described belo\\?. The test results are collectively shown in Table 2. [007 11 [Biodeg~adability] The biodegradability of the lubricant film-fonning composition was evaluated by the OECD 301D Closed Bottle method wvl~ichi s generally employed as an evaluation method of biodegradability, for the purpose of evaluating the enviro~lniental effect on the ocean. Specifically, for each co~nponenitn the composition, the biodegradability after 28 days elapsed in water (BOD2s) was measured by the abovedesc~ ibedte st method, and the value of the BOD26 of the entire co~npositionw hic11 is the sum of the blending ratios of the correspo~ldirigc onlponents was obtained. A case wvllere the obtained BOD28 value of the composition is less than 20% was evaluated as poor, a case of 20% or higher and less than 60% was evaluated as fair, a case of 60% or higher and less than 80% was evaluated as good, and a case of 80% or higller was evaluated as excellent. Excellent arid good which indicate a BOD28 value of 60% or higher are considered as a passing. [0072] [Lubricity] The lubricity was evaluated by a friction test in wvliicli fastening and loosening of the screw joint for a steel pipe shown in FIG. 4 are siniulated. First, the test was - 28 - pe~fortnedb y rotating a conical specinlen (Disk corresponding to the box) coated \vith the lubricant filnl to be tested on the snrface and at the same time, pressing a cylindrical specimen (Pin) fro111 above. The load was increased from I .O ton by iricrenlents of 0.1 tons and the lubricity was evaluated by the maxinlum load (hereinafter, OK load) at which seizure does not occur. In FIG. 4, Lubricant means the lubricant film. [0073] The test conditions of the fiiction test are as folloms. Contact type: line contact between the cylinder (pin) and the cone (disk); Material: SM95TS n~atiufacturedb y Nippon Steel & Sumitomo Metal Corporation (low alloy carbon steel for a screw joint); Surface treatment: manganese phosphate treatment only on the disk surface; Lubricant film: fortned by applying tlie lubricant film-fornling composition to be tested by the brush coating on the nlanganese pl~osphatef ilm of the disk surface: the film thichiess is 50 PI; Test load: 5 tons at tlie rnaxinlun~a; nd Rotational speed of the disk: 20 lym. LO0741 A case \vbere the OK load is less than 2.0 tons was evaluated as poor, a case of 2.0 tons or higher and less than 3.0 tons was evaluated as fair, a case of 3.0 tons or higher and less than 4.0 tons \\,as evaluated as good, and a case of 4.0 tons or higher \vas evaluated as excellet~t. Excellent and good at \vliich the OK load is 3.0 tons or higher are considered as a passing. [Antirust Properties] The evaluation of the antin~spt roperties was perfornled by a salt spray test (antirust test) specified in JIS 22371. The lubricant film was formed with a thickness of 30 ptn on the surface of a steel sheet (50 mm x 100 mm, and a thickness of 2 aim) which is made of the same material as that of the friction test, which is ground witllo~lt performing a surface treatment thereon, and was used as a specimen. The application \\as performed by the brush coating. The salt spray test was perfomled for 500 hours, and presence or absence of the occunence of rust was checked. A case \\(here slight rnst had occurred after the test for 500 hours mas evaluated as not good, and a case where no nlst had occurred was evaluated as good. Good \vllich indicates that rust did not occur is considered as a passing. [0076] [Stickiness Resistance] The evaluation of the stickiness resistance was performed by a foreign matter adhesion test (stickiness test) shown in FIG 5. The lubricant film-forming composition to be tested was applied to one surface of a specimen (50 x 50 mtn) made of carbon steel after grinding by the brush coating, thereby fornliug a lubricant filtn. The lubricant fill11 surface was caused to face downward, was settled on a petri dish paved with po\vder (No. 4 quartz sand) for 30 seconds, and the amount of the adhered powder was obtained by the wveigllt difference of the specimen before and after the settlement. Furthermore, the specimen was cause to stand upright, and air blowing at 0.4 MPa was performed on the lubricant film having the powder adhered thereto from a distance of 150 tntn for 10 seconds. Tlie amount of the adhered powder \vhich remains after the air blo\ving was obtained from the weight difference. A case wvhere the amount of the adhered powder after the air blowing is 5 g or higher was evaluated as poor, a case of 2.5 g or higher arid less than 5 g was evaluated as fair, a case of 1 g or 11igller and less than 2.5 g \ifas evaluated as good, and a case of less tlian 1 g \vas evaluated as excellent. Excellent and good \vhicIi indicate an amount of less than 2.5 g are considered as a passing. In addition, when the adhesion anlount is less than 2.5 g \vl~ich is considered as a passing in the test, even on the film formed on an actual pipe, it is confirmed that the adhered foreign matter can be si~nilarlyre ~ilovedb y general air blowing (a static pressure of 10 kPa and a flo\v rate of 2.0 m3/min). [0078] [Corrosiveness to Copper] For the corrosiveness to copper, the lubricant film-foonning cornposition to be tested was applied to a pure copper plate to fom~a lubricant filrn having a thickness of 50 pm, and the copper plate was exposed to the atmosphere at 80°C for 2 hours and was left at root11 teniperature for 4 \\leeks. The corrosiveness to copper was evaluated by the discoloration of the copper plate after being left for 4 weeks. Acase where slight discoloration has occurred was evaluated as not good, a case ~vlieren o discoloration bad occurred was evaluated as good, and good at which no discoloratioti had occurred is considered as a passing. [0079] [Table 21 [OOXO] As can be seen frotn Table 2, the lubricant film formed of the lubricant filmfoniiing composition according to this enibodinient showed performance \\~11ichis considered as a passing at all the test iten~sre garding the biodegradability, the lubricity, the antirust properties, the stickitless resistance, and the corrosiveness to copper. On the other hand, Comparative Exati~pless ho\ved itisufTicietit results in a few test items. [Industrial Applicability] [OOSl] According to the present invetition, it is possible to provide a lubricant filtnforming compositiot~h aving excellent lubricity, antit~~psrto perties, biodegradability, stickiness resistance, and corrosiveness to copper and a screwv joint for a steel pipe having the lubricant film-fonning coti~position. [Brief Description of the Reference Sjrntbols] [0082] 1: PIN 2: BOX 3: MALE THREADED PORTION 4: FEMALE THREADED PORTION 5: UNTHREADED METAL CONTACT PORTION 6: SMALL GAP OF FITTING PART BETWEEN SCREW THREADS A: OIL WELL PIPE B: COUPLING [Document Type] CLAIMS 1. A lubricant film-fom~ingc omposition, comprising, as a composition: 40 to 80 mass% of a base oil consisting of one or more selected from pentaerythritol fatty acid ester and trimethylolpropane fatty acid ester; 5 to 20 mass% of a solidifping agent consistiug of paraffin wax; and I0 to 40 mass% of a solid lubricant consisting of one or tnore selected from alkali metal salt of llydroxystearic acid and alkali earth metal salt of hydroxystearic acid, wherein a total contei~ot f the base oil, the solidieing agent, and the solid lubricant is 85 mass% or more and I00 tnass% or less, and the lubricant film-forming conlposition does not contain heavy metals. 2. The lubricant film-fom~ing composition according to claitn 1, wherein the base oil consists of one or inore selected ftom pentaerythritol tetraoleate, trimetl~ylopl ropane trioleate, and trinletliylol propane triisostearate. 3. The lubricant film-forming cotnposition according to claim 1 or 2, wherein the solid lubricant consists of one or more selected from calcium hydroxystearate, .lithium li~rdroxystearate,a nd sodiu~nl~ ydroqatearate. 4. A screw joint for steel pipe, the scre\v joint comprising: a pin; and a box, wherein each of the pin and the box has a threaded portion and an unthreaded metal colltact portion as fitting parts, the screw joint for steel pipe is provided with a lubricant film, whicll is formed of the lubricant film-forming composition according to any one of clainls 1 to 3, on a surface of the fitting part of at least one of the pin and the