JPH06207186A - Method for forming sliding film - Google Patents

Abstract

PURPOSE:To provide a sliding film capable of uniform dispersion of the fluororesin on sliding surface, excellent in frictional and wear characteristics without impairing the various excellent properties inherent in fluororesins such as heat resistance, chemical resistance and self-lubricity. CONSTITUTION:A laminate is made by laminating a 1st layer of polyamide-imide with a 2nd layer of PTFE, and then heated at 300 deg.C for 30min to melt the PTFE alone. Thereby, the fluororesin 3 as the 2nd layer is melted on the noncrystalline resin 2 as the 1st layer matrix and penetrated into the molecular structure of the resin 2, thus obtaining a sliding member, on the base 1, where the fluororesin 3 has been finely, homogeneously dispersed in the matrix of the noncrystalline resin 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a sliding film. The sliding member having the sliding coating formed on the base material by the forming method of the present invention is suitable for use as, for example, a guide member for guiding the outer peripheral surface of the piston rod of the shock absorber.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 52-135974.
In the publication, a mixture of PTFE (tetrafluoroethylene resin) powder and polyamide-imide powder is directly applied on a base material, dried at 100 ° C. for 10 minutes, and baked at 280 ° C. for 30 minutes. There is disclosed a sliding member having a sliding coating formed thereon.

As mentioned above, PTFE, FEP, PFA
Fluorine resins such as are not only excellent in heat resistance and chemical resistance, but also have a small friction coefficient and self-lubricating property, so they are widely used in various fields as sliding materials, but as abrasion resistance. Is not necessarily satisfactory, and is used as a mixture with other strong matrix resin materials such as polyimide and polyamide-imide.

[0004]

However, in each of the above-mentioned conventional methods, the matrix film is obtained by mixing the matrix resin material and the fluororesin and applying a solution in a solvent to obtain a sliding film. The fluororesin is unevenly distributed inside, and the sliding film is apt to wear and peel.

That is, the fluororesin has a primary particle diameter of 1 μm or less, which is extremely fine.
If it is positively performed by a roll mill, a homogenizer, etc., the particle size will be about 5 μm. However, fluororesin easily causes adhesion and is usually 10 to 30 μm.
m, the maximum particle size is about 100 μm, and when it is dissolved in a solvent at the same time as the above matrix resin, non-uniform dispersion is likely to occur in the liquid. For this reason, when spray coating or the like with a dry film thickness of 10 to 20 μm is performed on the surface of a substrate using this liquid, dispersion of the fluororesin on the coated surface occurs, and the fluororesin becomes uneven. The dispersed portion becomes a starting point of occurrence of wear and peeling due to local increase in frictional force.

The present invention has been made in view of the above-mentioned conventional problems, and enables the uniform dispersion of the fluororesin on the sliding surface, and has the excellent heat resistance and chemical resistance inherent to the fluororesin.
It is an object of the present invention to provide a sliding film having excellent friction and wear characteristics without impairing various characteristics such as self-lubricating property.

[0007]

A method for forming a sliding film according to the present invention comprises a laminating step of laminating a second layer made of a fluororesin on a first layer made of an amorphous resin to obtain a laminated body, A heating step of heating the laminate to melt the fluororesin.

Examples of the amorphous resin include polyamide imide, polyimide, epoxy, polyurethane, silicone and the like. Examples of the fluororesin include PTF
E, PFA (perfluoroalkoxy resin), FEP
(Tetrafluoroethylene-hexafluoropropylene copolymer resin), ETFE (Tetrafluoroethylene-ethylene copolymer resin), PCTFE (Trifluorochloroethylene resin), PV
Examples thereof include dF (vinylidene fluoride resin).

As a combination of the amorphous resin and the fluororesin, when the fluororesin is melted, the amorphous resin is completely melted or decomposed, and the structure as a layer is not lost. Can be combined. In order to melt the fluororesin, the whole may be heated by atmospheric heating, or only the fluororesin may be heated and melted by high frequency heating.

The first layer made of amorphous resin has a thickness of 20 to 50 μm.
It is preferably formed with a film thickness of m. First layer is 20 μm
In the case of less than, even if the second layer has a minimum thickness of 5 μm as described later,
A large amount of fluororesin that is not impregnated in the amorphous resin remains on the sliding surface, and the amount of wear increases due to sliding. The first layer is 5
If it exceeds 0 μm, the thickness of the sliding coating increases, so that the shear strength of the sliding member provided with the sliding coating on the base material decreases, and the sliding coating is likely to peel off.

The second layer made of fluororesin is 5 to 1
It is preferably formed with a film thickness of 0 μm. The second layer is 5μ
If it is less than m, it is difficult to uniformly form the fluororesin on the first layer. If the second layer exceeds 10 μm, even if the amorphous resin of the first layer is 50 μm at the maximum, a large amount of fluororesin that is not impregnated in the amorphous resin remains on the sliding surface, resulting in a large amount of wear due to sliding. Become.

[0012]

When the laminated body is heated by the sliding film forming method of the present invention and only the fluororesin is melted, the fluororesin of the second layer is melted on the amorphous resin serving as the matrix of the first layer. Therefore, the fluororesin is impregnated into the molecular structure of the amorphous resin. Thus, the fine fluororesin is uniformly dispersed in the matrix made of the amorphous resin.

[0013]

Embodiments of the present invention will now be described with reference to the drawings along with comparative examples. (Examples 1, 3, 7, 9, 11, 12) Laminating step: As shown in FIG. 1 (A), a liquid amorphous resin was formed on the base material 1 that had been alkali-cleaned to improve adhesion. Two
Is applied to form a first layer.

At this time, as the liquid amorphous resin 2,
Polyimide manufactured by DuPont (The structural formula is shown in Chemical formula 1.)
Or polyamide imide manufactured by DuPont Co., Ltd.
Shown in. )It was adopted. Then, these polyimides or polyamide-imides are mixed with N: at a compounding ratio of resin: solvent = 3: 7.
After dissolving in a mixed solvent of methylpyrrolidrin and xylene, 30% of polyimide or polyamideimide is formed on the substrate 1.
Spray coating was performed so that the film thickness was μm. After spray coating, baking was performed at 160 ° C. for 1 hour to form a first layer on the base material 1.

[0015]

[Chemical 1]

[0016]

[Chemical 2]

A fluororesin 3 is applied on this first layer to form a second layer. At this time, as the fluororesin 3, P
TFE (Neoflon (registered trademark) PT manufactured by Daikin Co., Ltd.
FE dispersion (average particle size 5 μm), melting point: 28
0 to 300 ° C.), FEP (Neotron (registered trademark) FEP dispersion manufactured by Daikin Co., Ltd. (average particle size: 5 μ)
m), melting point: 260 to 280 ° C.) or PFA (Neotron (registered trademark) PFA dispersion (average particle size: 5 μm) manufactured by Daikin Co., Ltd., melting point: 300 to 310 ° C.). Then, these PTFE, FEP or PFA are dispersed (Lubron (registered trademark) LD-manufactured by Daikin Co., Ltd.).
1, LD100), and disperse PTFE and F on the first layer.
Spray coating was performed so that EP or PFA had a film thickness of 5 μm.

Thus, as shown in Table 1, various first
Examples 1, 3, 7, 9, 11, 12 having a layer and a second layer
To obtain a laminated body of.

[0019]

[Table 1]

Heating step: 300 ° C. for the laminates of Examples 1, 3, and 9 in which polyamideimide was used as the amorphous resin 2.
X Heat for 30 minutes. In the laminates of Examples 7, 11, and 12 in which polyimide is used as the amorphous resin 2, the polyimide is a thermosetting resin, the thermal decomposition temperature is about 550 ° C., and 0.2 to 0.5 MPa. 30 while applying some pressure
Heat at 0 ° C x 30 minutes.

As a result, the fluororesin 3 of the second layer is melted on the amorphous resin 2 serving as the matrix of the first layer, and the fluororesin 3 is impregnated into the molecular structure of the amorphous resin 2.
At this time, in the pressurized product, the fluororesin 3 is impregnated by the pressurization into the molecular structure of the amorphous resin 2. Thus, as shown in FIG. 1B, the amorphous resin 2 is formed on the base material 1.
The fine fluororesin 3 is uniformly dispersed in the matrix consisting of, and as shown in Table 1, Examples 1, 3, 7, 9,
11 and 12 sliding members are obtained. The sliding film of each sliding member is matrix resin: fluorine resin = 4: 1 (weight ratio). (Examples 2, 4, 5, 6, 8, 10) Laminating step: A two-layer film is obtained by laminating the fluororesin 3 on the film-form amorphous resin 2.

At this time, the film-shaped amorphous resin 2 is a polyimide film (manufactured by Toray Industries, Inc., film thickness 30 μm).
m) or a polyamide-imide film (manufactured by Toray Industries, Inc., film thickness 30 μm). Further, as the fluororesin 3, PTFE (same as above), FEP (same as above) or PFA (same as above)
And disperse this PTFE in a dispersion liquid (same as above),
Spray coating was performed on the first layer made of a polyimide film or a polyamide-imide film so that PTFE, FEP or PFA had a film thickness of 5 μm. A two-layer film is thus obtained.

After this, a base material 1 of the same kind as the base material of the above embodiment
After spraying a primer (Polyflon (registered trademark)) 4 having a thickness of 5 to 10 μm thereon, a two-layer film is placed on the primer and dried at 80 ° C. for 10 minutes. Thus, FIG.
A laminated body of Examples 2, 4, 5, 6, 8, 10 shown in (A) is obtained.

Heating step: 300 for the laminates of Examples 5, 8 and 10 in which polyamideimide was used as the amorphous resin 2.
Heat at ℃ × 30 minutes. In addition, polyimide is used as an amorphous resin 2
In the laminates of Examples 2, 4, and 6 adopted as the above, since polyimide is a thermosetting resin and the thermal decomposition temperature is about 550 ° C., a pressure of about 0.2 to 0.5 MPa is applied while applying 3
Heat at 00 ° C x 30 minutes. At this time, what was pressurized is
By pressing, the two-layer film is brought into close contact with the base material 1 and the fluororesin 3 is impregnated into the molecular structure of the amorphous resin 2.

Thus, as shown in FIG. 5 (B), the fine fluororesin 3 was uniformly dispersed in the matrix composed of the amorphous resin 2 on the base material 1, and as shown in Table 1, Examples 2, 4, 5, 6, 8, 10 sliding members are obtained. The sliding film of each sliding member is matrix resin: fluorine resin = 4: 1 (weight ratio). In addition, a two-layer film is heated in a heating step to form a film-like sliding film,
The sliding member can also be manufactured by a method in which this film-like sliding film is attached to a substrate with a primer or the like. (Comparative Example 1) Liquid polyamide-imide (same as above): PTF
E (same as above): PT was added to polyamide-imide at a ratio of 3: 2
A liquid is prepared by dispersing FE (same as above). Examples 1 to 1
This liquid was directly applied to a base material of the same type as the base material of No. 0 with a film thickness of solid content of 30 μm, and this was dried at 100 ° C. for 10 minutes, 280 ° C.
The sliding member of Comparative Example 1 is obtained by firing for 30 minutes. The sliding coating of this sliding member is matrix resin: fluorine resin = 4: 1 (weight ratio). (Comparative Example 2) Polyamide polyamide powder (DuPont Co., Ltd.)
Made, average particle size 50-100 μm), and PTFE (same as above)
And are mixed and dispersed and dissolved in a mixed solvent composed of N-methylpyrrolidrin and xylene. The compounding ratio at this time is polyamideimide: PTFE: mixed solvent = 25: 5: 7.
It is 0 (weight ratio). The sliding member of Comparative Example 2 is obtained by spray-coating this solution on a substrate of the same type as the substrate of Examples 1 to 10 with a solid content of 30 μm, and firing this at 160 ° C. for 1 hour. The sliding coating of this sliding member is matrix resin: fluorine resin = 4: 1 (weight ratio). (Evaluation 1) FIG. 2 shows a sliding film on the sliding member of Example 5, FIG. 3 shows a sliding film on the sliding member of Comparative Example 2, and EPs thereof.
The MA (characteristic X-ray diagram, F element) analysis photograph is shown.

From FIG. 2, it can be seen that in the sliding member of Example 5, the white dots indicating the F element are dispersed, and the fluororesin is dispersed almost uniformly on the sliding surface. On the other hand, FIG.
From the results, it can be seen that in the sliding member of Comparative Example 2, white dots indicating the F element are unevenly distributed, the fluororesin is present with a particle size of about 10 μm, and there are many places where no fluororesin is present. . (Evaluation 2) The friction coefficient and the wear amount of the sliding members of Examples 1 to 10 and Comparative Examples 1 and 2 were measured. The friction coefficient is a result measured by a thrust type tester under a lubrication speed of 60 m / min, load: 9.8 MPa, mating material: gray cast iron FC25, and lubrication. In addition, the amount of wear was measured by a thrust type tester at a sliding speed of 60 m / min and a load of 9.8 MP.
a, Counterpart material: gray cast iron FC25, test time: 1 hour,
It is a measurement result under lubrication. The results are shown in Table 2. In addition,
In Table 2, "*" indicates that seizure occurred before the test load.

[0027]

[Table 2]

According to the sliding members of Examples 7 to 9 in Table 2, the first layer made of an amorphous resin was formed to have a film thickness of 20 to 50 μm, and the second layer made of fluororesin was made to be a film of 5 to 10 μm. It can be seen that it is preferable to form a thick film. In addition, Example 7
Examples 1 to 6 and Example 10 excluding the sliding member
The average friction coefficient was determined for the sliding member of No. 12 and the sliding members of Comparative Examples 1 and 2, and the results are shown in FIG. 4 together with the maximum value and the minimum value.

From Table 2 and FIG. 4, the sliding members of Examples 1 to 6 and Examples 10 to 12 are compared with the sliding members of Comparative Examples 1 and 2, matrix resin: fluorine resin = 4: 1. It can be seen that the friction coefficient and the wear amount are excellent even though they are equal in (weight ratio). Also, in terms of the variation of the friction coefficient, it is understood that the sliding members of Examples 1 to 6 and Examples 10 to 12 have a smaller difference than the sliding members of Comparative Examples 1 and 2.

Furthermore, the sliding member of Examples 2 and 4 in which the amorphous resin 2 and the fluororesin 3 are sequentially coated on the substrate 1, and the Example 1 in which a two-layer film is formed and attached to the substrate 1
It can also be seen that there is no difference in the friction and wear characteristics when comparing Nos. 1 and 12.

[0031]

As described above in detail, in the method for forming a sliding film of the present invention, since the constitution described in the claims is adopted, it is possible to uniformly disperse the fluororesin on the sliding surface. This makes it possible to reduce friction and friction without deteriorating various properties such as excellent heat resistance, chemical resistance and self-lubricating property of fluororesin.
A sliding film with excellent wear characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sliding member showing a forming method of Example 1 and the like.

FIG. 2 shows a sliding film in a sliding member of Example 5 1
It is an X-ray photograph of 000 times.

FIG. 3 shows a sliding film in a sliding member of Comparative Example 1
It is an X-ray photograph of 000 times.

FIG. 4 is a graph showing a difference in friction coefficient between an example and a comparative example.

FIG. 5 is a cross-sectional view of a sliding member showing a forming method of Example 2 and the like.

[Explanation of symbols]

 2 ... Amorphous resin 3 ... Fluorine resin

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Claims (1)

[Claims] 1. A laminating step of laminating a second layer made of a fluororesin on a first layer made of an amorphous resin to obtain a laminated body, and a heating step of heating the laminated body to melt the fluororesin. And a method for forming a sliding film, comprising: