0001]The present invention relates to a method of manufacturing a surface treated steel strip and surface treated steel strip.
BACKGROUND
[0002]Among the plastic working of the steel plate, in the processing of automobile transmission parts such as forced multistage press molding at high surface pressure, in order to prevent galling seizure or type to the mold of the steel sheet, zinc phosphate on the surface of the steel sheet the by the phosphate crystals precipitated mainly to form a phosphate film, then phosphate coating with reactive soap film composed mainly of sodium stearate (alkali soap) as the upper layer of the phosphate film salt soap treatment have been made. However, phosphate soap treatment, it takes a long reaction time for the formation of reactive soap film and the phosphate coating, the production cost is increased. Further, soap unreacted components, in order to adhesion to the mold as Puresukasu during press molding, frequent cleaning of the mold is important.
[0003]
　Therefore, without reactive soap treatment requiring a long time, in order to prevent galling seizure or type in a multistage plastic working such as a multi-stage press molding at high surface pressure, as an upper layer of phosphate film a technique of forming a lubricating film containing a lubricant component is disclosed (e.g., see Patent Document 1 below.)
CITATION
Patent Document
[0004]
Patent Document 1: JP 2013-104125 JP
Summary of the Invention
Problems that the Invention is to Solve
[0005]
　Here, the process as disclosed in Patent Document 1, practically, it is often performed in the state of the steel strip. If processed is steel strip, in a slitting step located in front of the multistage plastic working, is to pump steel from the steel strip by the pinch rolls is essential. Further, in order to ensure 耐型 galling resistance during multi-stage press molding is it is important to reduce the static friction coefficient of the steel sheet fed from the strip, too lowered coefficient of static friction, the steel sheet pinch rolls slips in, the probability that the blanking occurs becomes high. Thus, roll feed properties and resistance (roll slipperiness), the 耐型 galling resistance during multistage press molding at high surface pressure, a performance which are in a tradeoff relationship with each other. To carry out the continuous multi-stage plastic working while feeding the steel plate from the steel strip, so that the compatibility between resistance to roll slip properties and 耐型 galling properties as described above can be determined.
[0006]
　The present invention has been made in view of the above problems, it is an object of the present invention, which can be implemented together with resistance to roll slip properties and 耐型 galling resistance are conflicting performance, surface and to provide a manufacturing method of processing steel strip and surface treated steel strip.
Means for Solving the Problems
[0007]
　The present inventor has conducted extensive studies to solve the above problems, the following findings were obtained.
(A) prior to forming the lubricating coating layer on the surface of the base material steel plate as the base material, to precipitate the zinc phosphate crystals in an island shape on the surface of the base steel sheet. At this time, as part of the zinc phosphate crystals are exposed (protruded) from the surface of the lubricating film layer, to control the shape of the zinc phosphate crystals. Thus, ultimately, unevenness due to zinc phosphate crystals obtain a surface treated steel strip forms the exposed (protruded) from the surface of the lubricating film layer.
Because (B) zinc phosphate crystals do not have a lubricating property, coefficient of static friction of the surface treated steel strip which irregularities are formed on the surface of the lubricating film layer by zinc phosphate crystals, than the static friction coefficient of the lubricating film layer alone also increased. The coefficient of static friction of the surface treated steel strip, the area ratio of the zinc phosphate crystals are exposed from the surface of the lubricating film layer (hereinafter sometimes referred to as an exposed area ratio) and are correlated. That is, by controlling the exposure area ratio of zinc phosphate crystals, it is possible to control the coefficient of static friction of the surface treated steel strip.
(C) when transporting the surface treated steel strip in a state sandwiched between a pair of pinch rolls, the surface treated steel strip the pressure (surface pressure) is applied by the pinch rolls, the pressure is exposed from the lubricating coating layer not high enough to crush a zinc phosphate crystal. In other words, the unevenness of the surface of the lubricating film layer by the pinch rolls are not flattened. Therefore, coefficient of static friction of the surface treated steel strip under the pinch rolls is maintained at a large value. As a result, the sliding surface treated steel strip under the pinch rolls is suppressed, resistance to roll slipping property under the pinch rolls (low surface pressure) is improved.
(D) On the other hand, when performing multi-stage press molding surface treated steel strip with a press apparatus disposed on the downstream side of the pinch roll, since a very large pressure to the surface-treated steel strip (surface pressure) is applied, the lubricating film layer exposed crushed is zinc phosphate crystals, unevenness of the surface of the lubricating coating layer is flattened. Thus, the coefficient of static friction of the surface treated steel strip under the press apparatus is a static friction coefficient lubricating coating layer has originally. As a result, under the press device so inherent lubricity of the surface-treated steel strip (sliding resistance) is exhibited, thereby improving耐型galling resistance under the press device (high surface pressure).
　The present invention has been completed based on the above findings and has as its gist is as follows.
[0008]
[1]
　and the base steel sheet,
　said the surface of the base steel sheet is formed in an island shape, a needle-like zinc phosphate film layer consisting of zinc phosphate crystals and,
　one surface and the zinc phosphate coating layer of the base steel sheet a Department coated, at least a lubrication film layer comprising, a lubricating component
comprises a,
　the area ratio of the exposed portion of the said zinc phosphate crystals on the surface of the lubricating coating layer is 25% to 90%, the surface treatment steel strip.
[2]
　The zinc phosphate crystals, an average particle diameter in the major axis direction is 25 [mu] m ~ 70 [mu] m, an average particle size in the short axis direction is 3 [mu] m ~ 10 [mu] m, surface treated steel strip according to [1].
[3]
　the adhesion amount of the zinc phosphate coating layer per surface 1.5 g / m 2 ~ 15.0 g / m 2 is, [1] or [2] surface treated steel according to any one of band.
[4]
　the adhesion amount of the lubricant coating layer per surface 1.0 g / m 2 ~ 12.0 g / m 2 is a surface treated steel strip according to any one of claims 1 to 3.
[5]
　The lubricating coating layer, SiO 2 / M 2O (M is an alkali metal.) And alkali metal silicate molar ratio of 2 to 5 represented by an average particle size of any at least of a polyethylene wax or polypropylene wax is 0.1 [mu] m ~ 3.0 [mu] m or the other a polymer wax consisting includes,
　with respect to the total solid mass of the lubricating coating layer, the solid content of the alkali metal silicate is 60 mass% to 90 mass%, the polymer solids content of the wax is 5% to 40% by weight, [1] to the surface treated steel strip according to any one of [4].
[6]
　and refining step of refining the surface of utilizing the surface conditioning agent containing colloidal titanium base steel sheet,
　an island on the surface of the base steel sheet which has been subjected to surface refining needle crystals of zinc phosphate Jo to be grown, a zinc phosphate coating layer formation step of forming a zinc phosphate coating layer on a surface of the base steel sheet,
　at least comprising lubrication treatment agent lubricating component, the amount of adhered per side 1.0 g / m 2 ~ 12.0 g / m 2 said to be the base steel sheet and applied to the surface of the zinc phosphate coating layer, to form a lubricating film layer, the zinc phosphate exposed on the surface of the lubricating coating layer the area ratio of the crystal, and a lubrication film layer forming step and 25% to 90%
including a method of manufacturing a surface treated steel strip.
[7]
　In the zinc phosphate coating layer formed step, heating the base steel sheet, a method for producing a surface-treated steel strip according to [6].
[8]
　Heating the base steel sheet by applying steam, a method for producing a surface-treated steel strip according to [7].
Effect of the invention
[0009]
　According to the present invention, it is possible to both achieve a 耐型 galling resistance at resistant roll slip properties and high surface pressure at a low surface pressure, which is a conflicting performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010]
FIG. 1 is an explanatory view of a surface treated steel strip according to an embodiment of the present invention.
Is a [FIG 2] (A) illustrates the structure of a surface treated steel strip according to the embodiment shown schematically. (B) is an explanatory view of the structure of the surface-treated steel strip shown schematically according to the embodiment.
Is a front view showing an example of FIG. 3] (A) zinc phosphate treatment bath to form a zinc phosphate coating layer on the surface of the steel strip. (B) is a plan view showing an example of a zinc phosphate treatment bath to form a zinc phosphate coating layer on the surface of the steel strip.
4 is a flowchart illustrating an example of a flow of a method of manufacturing a surface treated steel strip according to the embodiment.
[5] The耐型galling of the test method is an explanatory view schematically showing.
6 is an explanatory view of the resistance to roll slipping of the test method shown schematically.
7 is an enlarged photograph of the surface treated steel strip of the comparative example.
8 is an enlarged photograph of the surface treated steel strip of the comparative example.
9 is an enlarged photograph of the surface treated steel strip of the present invention embodiment.
FIG. 10 is an enlarged photograph of the surface treated steel strip of the present invention embodiment.
DESCRIPTION OF THE INVENTION
[0011]
　With reference to the accompanying drawings, a description will be given of an example embodiment of the present invention. In the specification and the drawings, components having substantially the same function and structure are a repeated explanation thereof by referring to the figures.
[0012]
(The surface-treated steel strip)
　First, with reference to FIGS. 1 to 2B, the surface treated steel strip according to an embodiment of the present invention will be described in detail. Figure 1 is an explanatory diagram for explaining a surface treated steel strip according to the present embodiment, FIGS. 2A and 2B are explanatory views of the structure of the surface treated steel strip according to the embodiment shown schematically is there.
[0013]
　Surface treated steel strip 10 according to the present embodiment, as detailed below, in which high lubricity treatment is performed in the basis steel sheet 101. Such surface treated steel strip 10, as schematically shown in FIG. 1, in the slitting step located in front of the multistage plastic working, the rolled-up state in a coil shape, unwound by pinch rolls 1, predetermined It will be through plate of sheet passing direction X continuously. Strip passing surface treated steel strip 10 passes through the multi-stage press working using a die 2 corresponding to the product of interest, will be processed into products of interest.
[0014]
　As prior described, in order to prevent galling seizure or type to the mold 2 surface treated steel strip 10 which is passing plate (basis steel sheet 101) decreases the coefficient of static friction of the surface treated steel strip 10 while it is important that, by pinch rolls 1 a surface treated steel strip 10, in order to unravel wound stably from the wound state in a coil shape, the surface treated steel strip 10 is somewhat coefficient of static friction it is important to have a. Therefore, the surface treated steel strip 10 according to the present embodiment, as shown in FIGS. 2A and 2B, to the surface of the base steel sheet 101 as a base material is subjected to a surface treatment as described in detail below surface treatment layer consisting of two layers is formed.
[0015]
　Surface treated steel strip 10 according to the present embodiment, as shown in FIGS. 2A and 2B, the basis steel sheet 101 as a base material, a zinc phosphate coating layer 103 formed on the base steel sheet 101, phosphoric acid It has a lubricating film layer 105 formed on the zinc coating layer 103, a. Incidentally, the zinc phosphate coating layer 103 and lubricant coating layer 105, as shown in Figure 2A, may be formed only on one surface of the base steel sheet 101, as shown in Figure 2B, basis steel sheet 101 may be formed on two surfaces opposite to each other.
[0016]
[About the basis steel sheet 101]
　basis steel sheet 101 is used as the base material of the surface-treated steel strip 10. For basis steel sheet 101 according to this embodiment is not particularly limited, it is possible to use the known steel properties sought in the subject matter is feasible to be manufactured through the subsequent multi-stage plastic working process. There is no particular limitation on the manufacturing method and material of such known steel, from normal cast piece manufacturing process, hot rolling, pickling, cold rolling, annealing, various known processes such temper rolling, etc. or one produced through appropriately. Further, such basis steel sheet 101 is not only carbon steel, it is needless to say may be a special steel such as stainless steel and high alloy steel.
[0017]
　An example of such a base steel sheet 101 can include a hot-rolled steel sheet having the chemical components, such as, for example, it follows.
[0018]
　Hot-rolled steel sheet is an example of a base steel sheet 101 is a mass%, C: 0.070% ~ 0.080%, Si: 0.030% ~ 0.080%, Mn1.15% ~ 1.30%, P: 0.015% ~ 0.028%, S: contains 0.000% to 0.040% the balance being Fe and impurities.
[0019]
　Such hot-rolled steel sheet by using a base steel sheet 101, it becomes possible to improve the strength of the object to be produced.
[0020]
[For the zinc phosphate coating layer 103]
　zinc phosphate coating layer 103 is responsible for increasing the adhesion between the base steel sheet 101 and the lubricant coating layer 105. The zinc phosphate coating layer 103 is composed of needle-like crystals of zinc phosphate which precipitated in a chemical reaction on the surface of the base steel sheet 101 is a set of needle-like zinc phosphate crystals. Needle crystal precipitated zinc phosphate, as schematically shown in FIGS. 2A and 2B, but are not completely covers the surface of the base steel sheet 101, a portion of the surface of the base steel sheet 101 in a state that remains without being coated with the zinc phosphate crystals. As a result, needle-like crystals of zinc phosphate, will be distributed in an island shape on the surface of the base steel sheet 101, the surface of the base steel sheet 101 needles zinc phosphate is not present is present as a flat section and thus. Note the zinc phosphate coating layer 103, the surface of the base steel sheet 101 is divided into a plurality of portions, it appears in a state independent of one another. In the present invention, thus being divided into a plurality of portions on the surface of the base steel sheet 101, the state of the zinc phosphate coating layer 103 which appears in a state independent of one another, it referred to as "islands".
[0021]
　Zinc phosphate coating layer 103 according to this embodiment is formed on the base steel sheet 101 reformed surface adjusted by using a specific surface modifier as described later, further, the phosphorus to form a zinc phosphate film layer 103 in zinc coating layer formed step, since the basis steel sheet 101 is heated, and a more in major axis direction and minor axis of the particle diameter of zinc phosphate is larger proportion of needle-like crystals. Adhesion amount of the zinc phosphate coating layer 103, per side 1.5 g / m 2 ~ 15.0 g / m 2 is preferably set to. Adhesion amount of the zinc phosphate coating layer 103 is more preferably per side 3.0 g / m 2 ~ 15.0 g / m 2 is. The adhesion amount of the zinc phosphate coating layer 103 that the range described above, the lubricating film layer 105 makes it possible to reliably adhere the base steel sheet 101, a zinc phosphate film in molding processing at high surface pressure without loss of the layer 103, it is possible to retain the lubricating film layer 105 to the final step of reliably molded.
[0022]
　Note that the needle-like crystals of zinc phosphate constituting the zinc phosphate coating layer 103 according to the present embodiment, an average particle diameter in the major axis direction is 25 [mu] m ~ 70 [mu] m, an average particle diameter of 3 [mu] m ~ 10 [mu] m in the minor axis direction it is preferable that. The average particle diameter of the needle-like crystals of zinc phosphate, more preferably from 25 [mu] m ~ 50 [mu] m in longitudinal direction, which is 3 [mu] m ~ 5 [mu] m in the minor axis direction. By having an average particle size zinc phosphate crystals constituting the zinc phosphate coating layer 103 is applied, it is possible to more reliably achieve the adhesion as described above.
[0023]
　Also, needle-like crystals of zinc phosphate constituting the zinc phosphate coating layer 103 according to this embodiment is a needle-like crystals ratio of the average particle size in the long axis direction and short axis direction is 2.5 or more it is preferable. By precipitating needle-shaped crystals of zinc phosphate having such an average particle size, it is possible to more reliably achieve the adhesion between the base steel sheet 101 and the lubricant coating layer 105.
[0024]
　The zinc phosphate coating layer 103 comprises zinc phosphate, it can be formed by using a needle-like crystals known that can be deposited treatment liquid zinc phosphate. Such treatment liquid is not particularly limited for, for example, reactive plastic working for zinc phosphate treatment liquid (more specifically, the processing time for full coverage is not less than 20 seconds reactive plastic working for zinc phosphate treatment solution) can be exemplified. When forming the zinc phosphate coating layer 103 may be contacted with the basis steel sheet 101 by a spray method or dipping method zinc phosphate treatment solution as described above, including zinc phosphate treatment solution as described above reactions the tank may be subjected to electrolytic processing using.
[0025]
　To precipitate the zinc phosphate crystals in an island shape on the base steel sheet 101 before the zinc phosphate crystal is completely cover the entire surface of the base steel sheet 101, it is sufficient to terminate the zinc phosphate treatment. For this purpose, it may be short time limit the contact time and the electrolysis time the base steel sheet 101 and the zinc phosphate treatment solution. That is, using a commercially available plastic working for zinc phosphate treatment solution, it Kiriagere processing in a shorter time than the processing time is indicated. The specific processing time and electrolysis conditions, the processing time (or electrolysis conditions) and the adhesion amount and the relationship that studied in advance and capable of processing time to achieve the preferred deposition amount as described above ( electrolysis conditions) may specify a. Further, in order to precipitate the zinc phosphate crystals in an island shape on the base steel sheet 101, in the zinc phosphate coating layer formation step of forming a zinc phosphate coating layer 103, it is effective to heat the base steel sheet 101.
[0026]
　For whether zinc phosphate crystals precipitated by treatment as described above or islands, the surface of the base steel sheet 101 after the zinc phosphate treatment by microscopic observation, can be determined. Specifically, the surface of the base steel sheet 101 after the zinc phosphate treatment, scanning electron microscope and observed at (Scanning Electron Microscope SEM), when the area of ​​the flat portion obtained by both images processing is 30% or more and it may be determined that zinc phosphate crystals are formed in an island shape. Observation of such zinc phosphate crystals, may be performed before the formation of the lubricating film layer 105 to be described later, it may be performed after the formation. However, when observed after the formation of the lubricating film layer 105, since the observing the zinc phosphate crystals through the lubricating film layer 105, and to perform the SEM observation at a high acceleration voltage. Specifically, the acceleration voltage by a least 20 kV, through the lubricating film layer 105 can be observed crystals of zinc phosphate, it can be determined the area ratio of the flat portion. In the observation before forming the lubricating coating layer 105, it is possible to observe the zinc phosphate crystals at lower accelerating voltage.
[0027]
　Here, in forming a zinc phosphate coating layer 103 on the base steel sheet 101, prior to the zinc phosphate treatment as described above, the refining of the surface of the base steel sheet 101 with a surface modifier containing a colloidal titanium do. Zinc phosphate crystal is coming precipitated from the surface of the base steel sheet 101 component of the surface modifier is not attached, since titanium colloid is coarse colloidal particles, wide of the surface of the base steel sheet 101 which is exposed so that the is is suppressed. As a result, by performing the surface refining at surface conditioner containing colloidal titanium, needle crystals of zinc phosphate having a preferred average particle diameter ratio as described above, it is possible to more reliably deposited .
[0028]
[For lubricating film layer 105 '
　lubricating film layer 105, as schematically shown in FIGS. 2A and 2B, located on the surface of the base steel sheet 101, the surface and the zinc phosphate coating layer 103 of the base steel sheet 101 with covering at least a portion of a layer in which at least a portion of the zinc phosphate crystal is exposed to the surface. The lubricating film layer 105 are at least including a layer of lubricant component preferably consists of a binder component and a lubricating component.
[0029]
　In the surface-treated steel strip 10 according to the present embodiment, by islands of zinc phosphate crystal, as described prior it is formed, lubricating component and a binder component contained in the lubricating film layer 105, FIG. 2A and FIG. as schematically shown in 2B, and thus held between the island-like zinc phosphate crystals. During multistage plastic working (for example, multi-stage during pressing), when high surface pressure is applied to the surface of the surface treated steel strip 10, lubricating component which is held between the island-like zinc phosphate crystals and the basis steel sheet 101 It flows out between the mold. As a result, static friction coefficient of the lubricating film layer 105 is a lubricating performance is expressed by a decrease, 耐型 galling resistance is realized.
[0030]
　Adhesion amount of the lubricating film layer 105, per side 1.0 g / m 2 ~ 12.0 g / m 2 is the area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105 (per unit area area ratio of) is 25% to 90%. With such an area ratio of the zinc phosphate crystal range which is exposed on the surface of the coating weight and the lubricating film layer 105 of the lubricating film layer 105, together with耐型galling resistance and roll slip properties as described above it is possible to realize.
[0031]
　Deposition amount of the lubricant coating layer 105 is 1.0 g / m 2 for the case of less than the amount of the lubricating component to be retained as a lubricating film layer 105 is insufficient, it is impossible to achieve sufficient耐型galling resistance , which is not preferable. The deposition amount of the lubricating film layer 105 is 12.0 g / m 2 for the case where the excess is the amount of the lubricating component to be retained as a lubricating film layer 105 becomes excessive, it is impossible to realize a resistance to roll slip properties , which is not preferable. Coating weight per one surface of the lubricating film layer 105 is more preferably, 2.0 g / m 2 ~ 9.0 g / m 2 is.
[0032]
　Incidentally, adhesion of the lubricating coating layer 105 is also influenced by the adhesion amount of the zinc phosphate coating layer 103. That is, the amount of lubricating film layer 105 when the adhesion amount of the zinc phosphate coating layer 103 is small, which can hold even less, to the contrary, when the adhesion amount of the zinc phosphate coating layer 103 is large in the lubricating film layer 105 that can hold The amount also increases. For example, the adhesion amount of the zinc phosphate coating layer 103 is 1.5 g / m 2 ~ 8.0 g / m 2 in the case of the coating weight of the lubricating film layer 105 is 1.0 g / m 2 ~ 6.0 g / m 2 is preferably on the order, the adhesion amount of the zinc phosphate coating layer 103 is 8.0 g / m 2 super ~ 15.0 g / m 2 in the case of the coating weight of the lubricating film layer 105 is 6.0 g / m 2 greater ~ 12.0 g / m 2 is preferably about.
[0033]
　Adhesion amount of the zinc phosphate coating layer 103, per side 1.5 g / m 2 ~ 8.0 g / m 2 if the amount deposited is 1.0 g / m 2 ~ 6.0 g / m 2 lubricating film of about the layers 105 becomes possible to suitably close contact with the base steel sheet 101, without loss of the zinc phosphate coating layer 103 in molding at high surface pressure, keeping the lubricating film layer 105 to the final step of the molding it is possible.
[0034]
　On the other hand, in automotive parts such as direct clutch, after receiving a cylindrical molded over multiple stages, there are parts to be molded around the tooth shapes. In these parts, for receiving the repetitive sliding molding at higher surface pressure, the adhesion amount of the zinc phosphate coating layer 103, per side 8.0 g / m 2 or less, the phosphorus by the sliding during the molding process zinc coating layer 103 disappears, decrease in the dimensional accuracy of the finished product, cracks in the middle step of molding may occur. In such a case, the amount of adhesion 8.0 g / m of zinc phosphate coating layer 103 2 super ~ 15.0 g / m 2 , the adhesion amount of the lubricant coating layer 105 is 6.0 g / m 2 super ~ 12.0 g / m 2 is preferably about.
[0035]
　Here, the lubricating coating layer 105 according to this embodiment, as the binder component, SiO 2 / M 2 (in M, is an alkali metal selected from Li, Na, K, etc..) O molar ratio represented by There comprises an alkali metal silicate is 2-5, as the lubricating component, an average particle diameter comprising at least one polymeric wax comprising from one polyethylene wax or polypropylene wax is 0.1 [mu] m ~ 3.0 [mu] m It is preferred.
[0036]
　By the binder component used alkali metal silicate as described above, in addition to it is possible to be held in proper coating in a lubricating component, a solid continuous film which is excellent in heat resistance steel strip surface it is possible to form. As a result, it is possible to seizure Kitsuki property function of preventing metal direct contact with the surface treated steel strip and the mold according to the present embodiment, and rust resistance ability due to the barrier properties of the dense alkaline film expression to become. Here, when the molar ratio is less than 2, since the film strength is sufficiently obtained without plastic working performance is deteriorated, which is not preferable. Further, when the molar ratio is 5 exceeded, in addition to plastic working performance is deteriorated, because the stability of the alkali metal silicate aqueous solution used during film formation becomes poor practicability deteriorated, unfavorably . SiO in an alkali metal silicate 2 / M 2 molar ratio represented by O is more preferably 3-4.
[0037]
　By using a polymer wax as described above as a lubricating component, it is possible to suppress the expansion of the lubricating film layer 105, can be further improved plastic working performance of the lubricating coating layer 105. Here, when the average particle size of the polymer wax is less than 0.1μm, in order to deteriorate the oil resistance of the film becomes remarkable diffusion of the oil into the coating in the surface of the polymer wax is not preferable, high when the average particle size of the molecule wax is 3.0μm exceeded, the dispersion of the polymer wax in the chemical solution becomes worse, undesirable because it becomes difficult to form a uniform film. The average particle size of the polymer wax, more preferably 0.5 [mu] m ~ 1.5 [mu] m. As a lubricating component, by using a polymer wax having a mean particle size as described above, it lubricating component is likely to be filled in the concave portion of the irregularities of the zinc phosphate crystals, resulting lubricating coating layer is zinc phosphate crystals easily exposed from 105 surfaces.
[0038]
　Solids content of the alkali metal silicate is preferably 60 mass% to 90 mass% relative to the total solid weight of the lubricating coating layer 105, the solids content of the polymer wax, lubricating is preferably 5 mass% to 40 mass% relative to the total solid weight of the coating layer 105.
[0039]
　If the solids content of the alkali metal silicate is less than 60% by weight, the continuity of the glassy coating formed by alkali metal silicate is poor, the film strength can be obtained which can withstand plastic working because the likelihood is lowered, unfavorably. Further, when the solids content of the alkali metal silicate is 90 mass% excess, in order to obtain film strength becomes economically disadvantageous saturated, which is not preferable. Solids content of the alkali metal silicate is more preferably 70% to 80% by weight relative to the total solid mass of the lubricating coating layer 105.
[0040]
　If the solids content of the polymer wax is less than 5 mass%, the lubricating film layer 105 is insufficient amount of lubricating component for holding, reduced potential sufficient lubricating performance is expressed, preferably Absent. Also, when the solids content of the polymer wax is 40 mass% excess, the amount of the lubricating component lubricant coating layer 105 holds becomes excessive, reduced possibility of sufficient anti-roll slip properties are expressed In order to, which is not preferable. The solids content of the polymer wax, more preferably 3 wt% to 10 wt% based on the total solids weight of the lubricating coating layer 105.
[0041]
　Lubricating film layer 105 according to this embodiment may utilize a lubricant treatment agent obtained by mixing a lubricating component, such as described above in a solution or dispersion of the binder component as described above, formed by coating. Here, as the solvent used, water, an organic solvent may be either a mixture thereof, working environment is an aqueous solvent (water, or a mixed solvent of water miscible organic solvents, such as water and alcohol) and it is preferably used. To such solvents, 60% to 90% by weight of the binder component with respect to the total solid content weight of the lubricating treatment agent (e.g., an alkali metal silicate) and 5 mass relative to the total solids weight of the lubricating treatment agent % to 40 wt% of the lubricating component (e.g., a polymer wax) was added and,, and in the proper coating and dried to form a solid content of the lubricating coating layer 105 as described above .
[0042]
　In order to increase the dispersibility of the lubricating component may be added with any known surfactant to said lubricant treatment agent. Further, in order to adjust the viscosity of the lubrication treatment agent, in a range that does not affect the film strength of the lubricating film layer 105 may be added the viscosity modifier. As such a viscosity modifier, it is possible to use those generally used, such as hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylic acid amide, sodium polyacrylate, polyvinyl pyrrolidone, organic polymer type up such as polyvinyl alcohol viscosity agent, and the like. When using such viscosity modifier, the content thereof, relative to the total solid weight of the lubricating coating layer 105 is preferably less than 10 wt%.
[0043]
　The lubrication treatment agent when applied over matrix substrate 3 and the zinc phosphate coating layer 103 is dipped, shower ringer process, it is possible to use a known method such as roll coating process. Also, coating the surface of the green body substrate 3 and the zinc phosphate coating layer 103 is only to be sufficiently covered with the lubrication treatment agent, the temperature and application time of the lubricating treatment agent is not particularly limited. Further, the invention is not particularly limited either drying temperature of lubrication treatment agent, depending on the components contained in the lubrication treatment agent may be appropriately set.
[0044]
[Area ratio (25% to 90%) for the zinc phosphate crystals exposed on the surface of the lubricating film layer 105 '
　in the lubricating film layer 105 according to the present embodiment, as shown in FIGS. 2A and 2B, by some of the zinc phosphate crystals (zinc phosphate coating layer 103) is exposed on a part of the surface of the lubricating film layer 105, reduction of static friction coefficient of the lubricating film layer 105 is well prevented extent. As a result, it is possible to also achieve a resistance to roll slipping property when unwinding steel from the steel strip.
[0045]
　When the area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105 is less than 25%, the degree of suppression of decrease in the static friction coefficient of the lubricating coating layer 105 is insufficient, sufficient anti-roll it is not possible to realize a sliding property, it is not preferred. Further, when the area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105 is 90% exceeded, the degree of suppression of decrease in the coefficient of static friction of the lubricating film layer 105 becomes excessive, sufficient anti it is not possible to realize a mold galling property, which is not preferable. The area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105, and more preferably from 30% to 60%.
[0046]
　By adhering amount of the lubricant coating layer 105 and the area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105 is within the above range, the static friction coefficient of the lubricating coating layer 105 according to this embodiment is a 0.10-0.20. Static friction coefficient of the lubricating film layer 105 is more preferably 0.12 to 0.15.
[0047]
　Incidentally, the adhesion amount of the zinc phosphate coating layer 103 by a preferable range as described above, can be in the more reliably the above range of area ratio of the zinc phosphate crystals is exposed to the lubricating coating layer 105 to become.
[0048]
　Further, zinc phosphate crystal is exposed and on the surface of the lubricating film layer 105 and the area ratio of (zinc phosphate coating layer 103) to the 25% to 90%, per side 1.5 g / m 2 - 15 .0G / m 2 and a zinc phosphate coating layer 103 needs to be an island shape, to achieve this, a method such as the extension of the rise or the processing time of the temperature of the zinc phosphate treatment may be considered. However, since the temperature of the zinc phosphate treatment bath water is the solvent, raising the processing temperature above 100 ° C. is substantially difficult, while the crystalline zinc phosphate coating to be deposited and to extend the processing time Steel will be densely generated on the strip surface, a zinc phosphate coating layer 103 disappears in islands. Also, increase in the temperature of the zinc phosphate treatment bath is a problem of increasing energy costs due to the need to raise the temperature of the entire processing bath. Furthermore, If the extension of the processing time performing zinc phosphate treatment at a constant length zinc phosphate treatment bath there is a problem that productivity is lowered.
[0049]
　Therefore, per side 1.5 g / m 2 ~ 15.0 g / m 2 as an example of a method of forming a zinc phosphate coating layer 103 of the island, a partially temperature the temperature of the zinc phosphate treatment bath with steam how to increase is proposed. According to this method, in addition to increasing the deposition amount of zinc phosphate crystals, by a zinc phosphate crystals more needles (sharp form), it raises the bulk of the zinc phosphate crystals, lubricating film layer so out many head of the zinc phosphate crystals from. Zinc crystals themselves phosphate has no sliding resistance at Teimen pressure, the static friction coefficient is large. On the other hand, the high surface pressure collapsed zinc phosphate crystals, since the manner contributes to sliding properties with lubricating coating layer of the high surface pressure moldability =耐型galling resistance (simulated by L-press molding) Conventional It is equally and maintain.
[0050]
　Here, per side 1.5 g / m 2 ~ 15.0 g / m 2 shows an example of an apparatus for forming a zinc phosphate coating layer 103 of the island-like Figure 3A, the B. The Figure 3A, in the apparatus shown in B, and the surface of the base steel sheet 101 which is Tsuban in zinc phosphate treatment bath 20, is configured to apply steam generated by the heater 21. In zinc phosphating bath 20 in the steam that is generated in the heating of the heater 21, it is addressed is stirred by a stirrer 22 in the surface of the base steel sheet 101. In forming the zinc phosphate coating layer 103 performs partial heating in zinc phosphate treatment bath 20, if increasing the processing temperature by applying steam to the surface of the base steel sheet 101, a zinc phosphate film without the overall processing bath 20 to a significant high temperature, and in short processing time without impairing productivity, easily it becomes possible to form a zinc phosphate film layer 103 into an island shape. Steam temperature promotes higher formation of zinc phosphate coating layer 103. Therefore, the steam temperature is preferably at least 100 ° C., more preferably at least 120 ° C.. With energy costs as the temperature increases the vapor rises, since the effect is saturated, steam temperature is preferably at 200 ° C. or less.
[0051]
　The per side 1.5 g / m to the steel strip when exposed to steam on the surface of the base steel sheet 101 in the zinc phosphate treatment bath 20 as 2 ~ 15.0 g / m 2 zinc phosphate coating is formed in an island form that reason is not clear. However, the surface of the base steel sheet 101, the growth of the zinc phosphate crystals from a portion of the growing point of the zinc phosphate crystals is inhibited, while the zinc phosphate film is formed in an island shape, it is formed in an island shape zinc phosphate crystals, by the steam, 100 rises and is activated ℃ above, its growth by contact with the zinc phosphate treatment solution in the zinc phosphate treatment bath 20 is further promoted, per side 1.5g / m 2 ~ 15.0 g / m 2 is estimated that it would be able to form a zinc phosphate coating in an island shape.
[0052]
　Incidentally, per side 1.5 g / m 2 ~ 15.0 g / m 2 apparatus for forming a zinc phosphate coating layer 103 of the island is not particularly limited. May be of a type shed direct steam to the base steel sheet 101, after mixing with the zinc phosphate treatment solution, it may be of a type shed direct steam to the base steel sheet 101. The stirred steam generated from the heater 21 installed in the wall surface of the zinc phosphate treatment bath 20 with a stirrer 22, the basis steel sheet 101 at the same time as the zinc phosphate treatment solution may be one type hits steam.
[0053]
　Incidentally, FIG. 3A, by using the apparatus shown in B, and it becomes possible to make the zinc phosphate coating layer 103 and the island shape, the maximum value of the adhesion amount of the zinc phosphate coating layer 103 by blowing steam the 15.0 g of / M 2 is about. The adhesion amount of the zinc phosphate coating layer 103 per surface 1.5 g / m 2 ~ 15.0 g / m 2 by a, the lubricating film layer 105 makes it possible to reliably adhere the base steel sheet 101, a high surface without loss of the zinc phosphate coating layer 103 also molded in the pressure, it is possible to retain the lubricating film layer 105 to the final step of reliably molded.
[0054]
　Above with reference to FIGS. 1 to 3, the surface treated steel strip 10 according to the present embodiment has been described in detail.
[0055]

　Next, a method for measuring various physical values of which are implemented by the surface treated steel strip 10 according to the present embodiment will be briefly described.
[0056]
　First, the average particle size and zinc phosphate crystals constituting the zinc phosphate coating layer 103, an average particle diameter of the polymer wax contained in the lubricating film layer 105, field emission scanning electron microscope (Field Emission Scanning Electron Microscope: FE-SEM) using, such like to observe the surface of the steel sheet at a low acceleration voltage, can be measured by a known measurement method.
[0057]
　The coating weight per one surface of the zinc phosphate coating layer 103 and lubricant coating layer 105 can be measured by a known measurement method such as a weight method.
[0058]
　Note that the thickness of the zinc phosphate coating layer 103 and lubricant coating layer 105, it can be measured by observing the cross-section of the surface treated steel strip with an electron microscope such as SEM, the thickness of the lubricating film layer 105 is possible to measure in the following manner. First, the cross-section of the surface treated steel strip 10 along the depth direction from the surface, the glow discharge optical emission spectrometer: by (Glow Discharge Spectroscopy GDS), components of the lubricating film layer 105 (e.g., Si) and zinc phosphate crystal component (e.g., Zn) measuring the emission spectrum intensity of. Such measurements can be obtained two peaks corresponding to the components in the emission spectrum. Here, each 50% value of the peak intensity of the two components (Si, the 50% value of the base steel sheet side, Zn 50% value of the surface layer side of the strip) thickness corresponding to between the lubricating coating layer it can be a thickness of 105.
[0059]
　As for the area ratio of the zinc phosphate crystals exposed on the surface of the lubricating film layer 105, the surface of the surface treated steel strip 10 was observed by an electron microscope such as SEM, zinc phosphate crystals are detected within the field of view the area by identifying a known method, can be obtained. Here, in particular the area ratio, observe the plurality of locations of the surface of the surface treated steel strip 10, it is preferable to calculate the average of the specified area ratio.
[0060]
　The static friction coefficient of the lubricating coating layer 105 can be measured by various test methods, such as round bead pull test detailed below.
[0061]
　Although the method of measuring various physical values ​​of which are implemented by the surface treated steel strip 10 according to the present embodiment it has been briefly described. The above method of measurement is only an example, it is possible to identify the Property values ​​by other known measurement methods.
[0062]
(Method for producing the surface-treated steel strip)
　Subsequently, with reference to FIG. 4, a method for manufacturing the surface-treated steel strip 10 according to the present embodiment. Figure 4 is a flow chart showing an example of a flow of a method for producing a surface-treated steel strip 10 according to the present embodiment.
[0063]
　In the method of manufacturing a surface treated steel strip 10 according to the present embodiment, first, for a given base steel sheet 101 is wound steel strip, if necessary, it is carried out pretreatment such as degreasing or cleaning treatment that (preprocessing step S101).
[0064]
　Thereafter, the surface of the base steel sheet 101, are tempered by the surface conditioning agent containing colloidal titanium (temper step S103). This makes it possible to titanium colloid having a coarse particle size to the surface of the base steel sheet 101 is attached.
[0065]
　Subsequently, by a method as described prior to precipitate a needle crystal zinc phosphate on the surface of the base steel sheet 101 after the surface refining (zinc phosphate coating layer formed step S105). Thus, the needle-like crystals of zinc phosphate in an island shape on the surface of the base steel sheet 101 is deposited, so that the zinc phosphate coating layer 103 is formed. As described above, the deposition of zinc phosphate, 3A, by performing in the apparatus shown in B, suitably it is possible to form a zinc phosphate film layer 103 into an island shape.
[0066]
　Then, by the lubricating treatment agent is coated on the base steel sheet 101 and the zinc phosphate coating layer 103, dried at suitable drying conditions, to form the lubricating film layer 105 (lubricating film layer forming step S107). This makes it possible that the surface treated steel strip 10 as shown in FIGS. 2A and 2B is produced.
[0067]
　Then, if necessary, to the surface treated steel strip 10 to be manufactured, it is also possible to carry out the known post-processing (post-processing step S109).
[0068]
　Above with reference to FIG. 4, an example of a flow of a method of manufacturing a surface treated steel strip 10 according to the present embodiment has been briefly described.
Example
[0069]
　Hereinafter, while showing Examples and Comparative Examples, a method of manufacturing a surface treated steel strip and surface treated steel strip according to the present invention will be specifically described. Note that the embodiments described below is a mere example of a method for producing a surface-treated steel strip and surface treated steel strip according to the present invention, a method for producing a surface-treated steel strip and surface treated steel strip according to the present invention is described below It is not limited to the example shown in FIG.
[0070]
　In the following examples, reference to "%" means "% by mass" unless otherwise specified. In the following examples, the adhesion amount are both mean coating weight per one side.
[0071]
(1) zinc phosphate-treated steel plate
　with respect to both surfaces of the cut plate of SPH590 steel sheet having a thickness of 3.2 mm (tensile strength 590MPa or more hot-rolled steel sheet) (300 mm × 300 mm), a zinc phosphate treatment by immersion went. Against both surfaces of the steel sheet during the immersion treatment for the present embodiment in that, the 100 ° C. ~ 120 ° C. in steam by the steam generated from the heater installed in the wall of the apparatus are stirred at a stirrer for 5 seconds It addressed. The immersion time was varied between 5 seconds to 120 seconds by adjusting the deposition amount of zinc phosphate crystals, to obtain a zinc phosphate-treated steel sheets shown in Table 1. Adhesion amount of the zinc phosphate crystals was determined by change in mass before and after the zinc phosphate-treated steel plate.
[0072]
(2) formation of lubrication film
　added binder ingredients shown in below, the lubricating components and extreme pressure additives in pure water (deionized water), enough agitation to disperse, solid content of 20% with pure water diluted as to prepare a chemical solution used in the coating. The chemical solution was applied by one side by a bar coater to the surface of the zinc phosphate treated steel plate, dried at 60 ° C., the lubricating film formed on the surface, creating the lubricated steel sheet. Adhesion of the lubricating coating was calculated from the mass change of the lubricating film forming the front and rear of the steel sheet.
[0073]
　Chemical
　(2-1) A) binder component
　　Sodium metasilicate (SiO 2 / Na 2 O molar ratio of: 4)
　　Acrylic resin (monomer composition: 8% of acrylic acid, 52% methacrylic acid, butyl acrylate 40% )
　B) lubricating components
　　, an organic polymer compound: polyethylene wax (molecular weight 20000, average particle size 3 [mu] m)
　　, the solid lubricant: molybdenum disulfide (average particle diameter 2 [mu] m)
　　- soap: sodium stearate
　C) extreme pressure additive
　　and Asia phosphoric acid ester
　D) solids content
　　solid content of sodium metasilicate relative to the total solid content of & lubricating film layer: 88%
　　solid content of the polyethylene wax with respect to the total solid content of & lubricating film layer: 5%
[0074]
　Chemical
　(2-2) A) binder component
　　Sodium metasilicate (SiO 2 / Na 2 O molar ratio: 5)
　　Acrylic resin (monomer composition: 8% of acrylic acid, 52% methacrylic acid, butyl acrylate 40% )
　B) lubricating components
　　, an organic polymer compound: polyethylene wax (molecular weight 2000, average particle size 0.5 [mu] m)
　　, the solid lubricant: molybdenum disulfide (average particle diameter 2 [mu] m)
　　- soap: sodium stearate
　C) extreme pressure additive
　　· phosphite
　D) solids content
　　solid content of sodium metasilicate relative to the total solid content of & lubricating film layer: 80%
　　solid content of the polyethylene wax with respect to the total solid content of & lubricating film layer: 5%
[0075]
　Chemical
　(2-3) A) binder component
　　Sodium metasilicate (SiO 2 / Na 2 O molar ratio: 2)
　　Acrylic resin (monomer composition: 8% of acrylic acid, 52% methacrylic acid, butyl acrylate 40% )
　B) lubricating components
　　, an organic polymer compound: polyethylene wax (molecular weight 10000, average particle size 1.0 .mu.m)
　　, solid lubricant: molybdenum disulfide (average particle diameter 2 [mu] m)
　　- soap: sodium stearate
　C) extreme pressure additive
　　· phosphite
　D) solids content
　　solid content of sodium metasilicate relative to the total solid content of & lubricating film layer: 60%
　　solid content of the polyethylene wax with respect to the total solid content of & lubricating film layer: 30%
[0076]
(3) crystal size
　of the steel sheet surface after zinc phosphate treatment, was observed by SEM at an acceleration voltage 5 kV, 500-fold magnification. The area ratio of the zinc phosphate crystals exposed on the surface, the image was binarized to calculate the area of the crystalline portion. Further, by selecting crystals exposed on the surface at 4 or more of any measures the length of the major and minor axes, and calculating an average crystal size was a crystal size of zinc phosphate.
[0077]
(4) Evaluation methods
a-1)耐型galling properties
　to simulate multi-stage plastic working at high surface pressure, as outlined in Figure 5, using the L-shaped press-forming equipment, a lubricated steel sheet L performs multistage ironing by bending to the sample side of the following procedures, and evaluated the lubrication performance. At this time, when the molding number galling on the surface of the steel sheet in the following two occurs, because no can multistage forming, galling or 3 times was as acceptable steel sheet does not occur. Incidentally, the × those galling below 2 times occurs, galling or 3 times was expressed as ○ what did not occur.
[0078]
a-2) Procedure
　The procedure (1) General rust-preventive oil, the amount of adhesion 1.5 g / m 2 such that a is applied to both surfaces of the sample.
　Step (2) punch and die clearance, is set so that the thickness -0.25 (thickness reduction width = 0.15 mm), performed first ironing the (L next molding) to the sample.
　To ironing the L-shaped sample in step (3) Step (2), while compressing a further -0.25 pitch clearance, repeated until galling occurs mold on the surface of the steel sheet, the ironing number of mold galling occurs Ask.
[0079]
b-1) resistance to roll slip properties
　to simulate resistance to roll feed resistance at high surface pressure, sandwiching the front and back surfaces of the steel sheet in Marugata beads as outlined in Figure 6, still from the load when pulling out the steel to calculate the coefficient of friction. In static friction coefficient of 0.09 or less, it is impossible to apply a force for feeding the steel plate, that the sheet passing in the real line is difficult, and, in excess static friction coefficient of 0.20, feed the steel plate required force is too large in order, has been confirmed that, each sheet passing of the real line is difficult. Therefore, coefficient of static friction was passed steel sheet is 0.10 to 0.20. Incidentally, the static friction coefficient is denoted as × those outside the within the range was expressed as ○ what is within the range.
[0080]
b-2) Procedure
　The procedure (1) General rust-preventive oil, the amount of adhesion 1.5 g / m 2 such that a is applied to both surfaces of the sample.
　Step (2) is pressed against both sides of the steel plate round bead (R5) sandwiched by the load 1 [kN], pull the steel sheet, to calculate the coefficient of static friction when unplugging.
[0081]
[Table 1]

[0082]
(5) Evaluation Results
　Table 1 shows the evaluation results when the adhesion amount of the zinc phosphate crystals formed lubricating film on various different zinc phosphate-treated steel sheet.
[0083]
　As apparent from Table 1, have preferred zinc phosphate coating layer and a lubricating coating layer, satisfies the exposed area ratio of the zinc phosphate crystals No. 2 to 4 and 6 ~ 10, 12 ~ 15, 17 ~ 18 and 20 exhibited sufficient performance to achieve both 耐型 galling resistance and roll slip properties.
[0084]
　On the other hand, the adhesion amount of the zinc phosphate coating layer is 0 or the missing NO. 1,19 is the coefficient of static friction is reduced, it resulted in 耐型 galling property and anti-roll slipperiness poor. Be adhered amount and an upper lubricating coating of zinc phosphate coating layer satisfy the preferred condition, average particle sizes of or short axis direction of the long axis of the zinc phosphate crystals is outside the scope of the present invention NO . 11,24,29,30,31 is static friction coefficient is lowered, it resulted in anti-roll slipperiness poor. Zinc phosphate crystals are more exposed No. 5, in order lubricating film itself is low, resulted in 耐型 galling resistance is poor. NO. 16, the exposure area ratio of the zinc phosphate crystals is small, the coefficient of static friction does not become 0.10 or more.
[0085]
　Figure 7-10 shows an enlarged photograph of the surface treated steel strip of Comparative Example and Inventive Example. Comparative Example shown in FIG. 7 (No.30), the coating weight 1.9 g / m of the island-like zinc phosphate coating layer 2 , the long diameter 100 [mu] m, the adhesion amount 3.3g of minor 20 [mu] m, a lubricating coating layer (solution 2-1) / m 2 , a 10% zinc phosphate exposed area of each of Comparative example shown in FIG. 8 (No.31), the coating weight 4.5 g / m of the island-like zinc phosphate coating layer 2 , diameter 200 [mu] m, minor 50μm coating weight 3.3 g / m of the lubricating film layer (solution 2-1) 2 , 24% zinc phosphate exposure area ratio. The present invention example shown in FIG. 9 (No.14), the coating weight 8.0 g / m of the island-like zinc phosphate coating layer 2 , the long diameter 64 .mu.m, the adhesion amount 3.7 minor 7 [mu] m, a lubricating coating layer (solution 2-1) g / m 2 , and 80% zinc phosphate exposure area ratio, the present invention example shown in FIG. 10, the adhesion amount 8.0 g / m of the island-like zinc phosphate coating layer 2 , diameter 31 .mu.m, minor 4 [mu] m, a lubricating coating coating weight 3.7 g / m of layer (solution 2-1) 2 , a zinc phosphate exposed area of 60%.
[0086]
　In the present invention example, by increasing the partial temperature the temperature of the zinc phosphate treatment bath with steam, in addition to increasing the deposition amount of zinc phosphate crystals, zinc phosphate crystals more needles (sharp shape) with, bulkiness of the zinc phosphate crystals is increased, the head of the zinc phosphate crystals had become out many from the lubricating film layer. Zinc crystals themselves phosphate has no sliding resistance at Teimen pressure, static friction coefficient was increased. On the other hand, the high surface pressure collapsed zinc phosphate crystals, since the manner contributes to sliding properties with lubricating coating layer of the high surface pressure moldability = 耐型 galling resistance (simulated by L-press molding) Conventional to have been equally maintained. Thus, it becomes possible to both achieve the anti-roll slip properties and 耐型 galling resistance are conflicting performance.
[0087]
　Having described in detail preferred embodiments of the present invention with reference to the accompanying drawings, the present invention is not limited to such an example. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various changes and modifications , also such modifications are intended to fall within the technical scope of the present invention.
DESCRIPTION OF SYMBOLS
[0088]
　　　1 pinch rolls
　　　2 die
　　10 surface-treated steel strip
　　20 zinc phosphate treatment bath
　　21 heater
　　22 agitator
　101 base steel sheet
　103 zinc phosphate coating layer
　105 lubricating film layer

WE CLAIM

And the base steel sheet,
　the formed in an island shape on the surface of the base steel sheet, and the needle-like zinc phosphate film consisting of zinc phosphate crystal layer,
　and a portion of the surface with the zinc phosphate coating layer of the base steel sheet coated, at least a lubrication film layer comprising, a lubricating component
comprises a,
　the area ratio of the exposed portion of the said zinc phosphate crystals on the surface of the lubricating coating layer is 25% to 90%, a surface treated steel strip.
[Requested item 2]
　The zinc phosphate crystals, an average particle diameter in the major axis direction is 25 [mu] m ~ 70 [mu] m, an average particle size in the short axis direction is 3 [mu] m ~ 10 [mu] m, surface treated steel strip according to claim 1.
[Requested item 3]
　The adhesion amount of the zinc phosphate coating layer per surface 1.5 g / m 2 ~ 15.0 g / m 2 is a surface treated steel strip according to any one of claims 1 or 2.
[Requested item 4]
　The adhesion amount of the lubricant coating layer per surface 1.0 g / m 2 ~ 12.0 g / m 2 is a surface treated steel strip according to any one of claims 1 to 3.
[Requested item 5]
　The lubricating coating layer, SiO 2 / M 2 (in M, an alkali metal.) O and alkali-metal silicate salt molar ratio of 2 to 5 represented by an average particle size of 0.1 [mu] m ~ 3. includes a polymer wax consisting of at least one of polyethylene wax or polypropylene wax is 0 .mu.m, and
　the total solid content mass of the lubricating coating layer, the solid content of the alkali metal silicate is 60 mass % and 90 wt%, solid content of the polymer wax is 5 mass% to 40 mass%, the surface treated steel strip according to any one of claims 1-4.
[Requested item 6]
　And refining step of refining the surface of the base steel sheet by using a surface modifier comprising titanium colloid,
　growing a needle crystal of zinc phosphate in an island shape on the surface of the base steel sheet which has been subjected to surface refining by, the the formation steps zinc phosphate coating layer to form a zinc phosphate coating layer on the surface of the base steel sheet,
　at least comprising lubrication treatment agent lubricating component, the amount of adhered per side 1.0 g / m 2 ~ 12. 0 g / m 2 wherein the base steel sheet and applied to the surface of the zinc phosphate coating layer so that the area of forming a lubricating film layer, an exposed portion of the said zinc phosphate crystals on the surface of the lubricating coating layer rate and a lubrication film layer forming step and 25% to 90% including a method of manufacturing a surface treated steel strip.
[Requested item 7]
　In the zinc phosphate coating layer formed step, heating the base steel sheet, a method for producing a surface-treated steel strip according to claim 6, wherein.
[Requested item 8]
　Wherein the basis steel sheet is heated by applying steam, a method for producing a surface-treated steel strip according to claim 7.