JP5188763B2 - Wear resistant low friction resistance electrodeposition coating - Google Patents

Description

  The present invention relates to an improvement in the abrasion resistance of a lubricating electrodeposition coating film containing a fluororesin, particularly polytetrafluoroethylene (PTFE), under high load conditions.

Electrodeposition coating can be used for traditional spray painting, including electrostatic coating, because it can be applied to a substrate with a complex shape with a uniform film thickness, and because it uses water-based paint, VOC can be reduced. Instead it has become popular. On the other hand, fluororesins, especially PTFE, are known to have low adhesion and low frictional resistance and excellent heat resistance. Utilizing this property of fluororesin, fine powder of fluororesin is dispersed in the electrodeposition paint to form an electrodeposition coating with low friction resistance, and molybdenum disulfide (MoS), a solid lubricant, is applied to the electrodeposition paint. It is known that ₂ ) is dispersed to form a low friction-resistant coating film.

JP-A-1-201373 Japanese Patent Laid-Open No. 5-117556 JP 2001-19897 A JP 2002-38078 A JP 2002-275393 A JP 2004-277565 A JP-A-6-287485 JP 2005-154579 A

  Of these, Patent Documents 5 and 6 blend a layered inorganic compound such as an alkali metal titanate in addition to the fluororesin, and measure the static friction coefficient and wear resistance of the coating film using the same probe. However, for example, sliding parts of automobile parts listed in Patent Document 7 are required to have wear resistance under a load condition much higher than a load applied to a probe for measuring a static friction coefficient.

  In Patent Document 8, a fluororesin fine powder and graphite are blended in an electrodeposition paint, and this paint is electrodeposited on a card reader to improve card slip and antistatic performance. For comparison, an electrodeposition coating using molybdenum disulfide in combination with PTFE instead of graphite is also disclosed, but the test was evaluated based on the number of passes when a squeak (squeak) starts to occur when the card is passed through the card reader. Yes. However, under such test conditions, the load applied at right angles to the card path of the card reader is almost negligible.

  Unlike card readers, for engine parts such as engine pistons, compressor pistons, intermediate shafts, steering joints, door hinges, window regulators, seat adjusters, seat belt brackets, and similar general machine parts and molds Such a lubricious electrodeposition coating film is required to have wear resistance under higher load conditions.

The present invention relates to a solid lubricant comprising a mixture of molybdenum disulfide (MoS ₂ ) and polytetrafluoroethylene (PTFE) in a weight ratio of 5:95 to 70:30. And the solid lubricant dispersed in a weight ratio of 95: 5 to 50:50, and an electrodeposition coating material for forming a high load resistance lubricating coating film, and the electrodeposition coating material with respect to the substrate. The present invention relates to a method for forming a lubricating film that exhibits wear resistance under high load conditions, characterized by being coated.

Further, the present invention is that the resin solids of the paint made of an alkyd resin as a reference, was blended with molybdenum disulfide _(MoS 2) _0.3~15wt% and polytetrafluoroethylene (PTFE) 3~23.8wt% The present invention relates to an electrodeposition coating, and a method of forming a lubricious film that exhibits wear resistance under high load conditions, characterized by electrodeposition coating the electrodeposition coating on a substrate.

Furthermore, the present invention relates to 2.5 to 33.3 wt% of molybdenum disulfide (MoS ₂ ) and 5.3 to 95.0 wt of polytetrafluoroethylene (PTFE), based on the resin solid content of a coating made of polybutadiene resin. The present invention relates to a method of forming a lubricating coating that exhibits wear resistance under high load conditions, characterized by electrodeposition coating of the electrodeposition coating on the substrate.

PTFE has the lowest coefficient of friction among solid lubricants, but the usable temperature is up to about 260 ° C., and load resistance decreases at higher temperatures. Although MoS ₂ is inferior to PTFE in the coefficient of friction, since it is an inorganic substance, the usable temperature is higher than that of PTFE, and the load resistance is not lowered at a high temperature. Therefore, the ratio of MoS _{2 to} PTFE is critical when trying to obtain a coating film having a friction coefficient as low as possible and having a large load resistance by using both in combination. It is also important that these solid lubricants are present in the coating film as much as possible. The present invention has a ratio of MoS ₂ to PTFE in which a low coefficient of friction and load resistance are satisfactorily balanced, and electrodeposition containing PTFE and MoS ₂ at a ratio that provides a balanced coefficient of friction and load resistance. Provide a coating.

The coating material used in the present invention comprises an electrodeposition coating material that is a matrix of a solid lubricant, and fine powders of PTFE and MoS ₂ as a solid lubricant added thereto. Electrodeposition paints and their coating methods are well known in the paint art and do not themselves constitute the present invention, so a detailed description will not be necessary here. Electrodeposition paints are classified into anionic and cationic types, each containing a water-soluble or water-dispersible vehicle resin that is negatively or positively charged, and optionally a curing agent thereof. Since the electrodeposition paint serves as a matrix for the solid lubricant, it may be either an anionic type or a cationic type. In the present invention, the term “resin solids” refers to the total amount of this vehicle resin and, if present, the curing agent.

  The paint generally contains conventional additive components. Examples thereof are coloring and rust preventive pigments, neutralizing agents, water-miscible organic solvents, surfactants and the like, but the electrodeposition paint used in the present invention can of course also contain these conventional additive components.

PTFE and MoS ₂ are well known as solid lubricants and are commercially available. From the viewpoint of easy dispersion in the paint, their average particle size is preferably in the range of 0.2 to 10 μm.

As described above, there is a certain blend ratio between PTFE having a relatively low coefficient of friction and MoS ₂ having a relatively high load capacity, which satisfies a low coefficient of friction and load resistance. To do. According to the present invention, in order to obtain a high-load-resistant lubricating coating film, a solid lubricant comprising a mixture of molybdenum disulfide and polytetrafluoroethylene in a weight ratio of 5:95 to 70:30 is used as an electrodeposition coating. It is necessary to disperse the electrodeposition paint resin solids and the solid lubricant in a weight ratio of 95: 5 to 50:50.

Further, according to the present invention, when the coating material consisting of alkyd resins, the resin solids on the _basis, and MoS 2 0.3~15wt%, comprises PTFE3～23.8Wt%, more preferably, _MoS 2 3 It is necessary to contain ˜7.5 wt% and PTFE 5.0 to 23.8 wt%. And at that time, it is preferable to adjust the total amount of both in the range of 5.3-25 wt% of solid content. In other words, MoS ₂ requires at least 0.3 wt% or more of the resin solid content in order to satisfy the high load resistance, and PTFE requires at least 3 wt% or more based on the resin solid content in order to satisfy the low friction property. It needs to be. However, if the total amount of these solid lubricants is too large, the dispersibility, film-forming property, etc. are adversely affected, so that it is preferable that the amount does not exceed 50 wt%, preferably 25 wt%. In addition to PTFE and MoS ₂ in this range, graphite may be used in combination.

Further, according to the present invention, in the case of a coating made of a polybutadiene resin, it contains 2.5 to 33.3 wt% of MoS _{2 and} 5.3 to 95.0 wt% of PTFE, more preferably based on the resin solid content. MoS ₂ 4.3 to 21.4 wt% and PTFE 8.8 to 90.0 wt% are required to be included. And at that time, it is preferable to adjust both the total amount in the range of 17.6-100 wt% of solid content. In other words, MoS ₂ requires at least 2.5 wt% of the resin solid content to satisfy the high load resistance, and PTFE requires at least 5.3 wt% based on the resin solid content to satisfy the low friction property. It is necessary to be above. However, if the total amount of these solid lubricants is too large, the dispersibility, film-forming property, etc. are adversely affected. In addition to the PTFE and MoS ₂ in this range, graphite may be used in combination as in the case of a coating made of an alkyd resin.

  The base material, that is, the object to be coated with the electrodeposition paint, is a steel machine part or a mold that requires surface lubricity. The electrodeposition coating film of the present invention can be formed by electrodepositing these substrates as a cathode in the case of a cationic electrodeposition coating, and as an anode in the case of an anion electrodeposition coating, washing with water and then curing by heating. The dry film thickness of the coating film is generally 5 to 30 μm.

  The following examples are illustrative of the invention and are not intended to be limiting. In these, “parts” and “%” are based on weight unless otherwise specified.

[Part I]
Example 1
To an anionic alkyd resin of trade name S-161-LP manufactured by Dainippon Ink & Chemicals, Ltd., 10 parts of MoS ₂ (12.5% of solids) and 10 parts of PTFE (solids) with respect to 80 parts of resin solids. 12.5%) was added, and this was electrodeposited onto a blasted steel plate to a dry coating thickness of 10 μm, washed with water and heated at 230 ° C. for 20 minutes to obtain a test coating.

Example 2
In Example 1, MoS ₂ was changed to 6 parts (7.5% solid content) and PTFE was changed to 14 parts (17.5% solid content) to obtain a test coating film having a dry film thickness of 10 μm under the same conditions. .

Example 3
In Example 1, the resin solid content was changed to 90 parts of MoS ₂ (5.6% with respect to the solid content) and 5 parts of PTFE (5.6% with respect to the solid content), and electrodeposition was performed under the same conditions. The test coating film having a dry film thickness of 10 μm was obtained.

Example 4
In Example 1, MoS ₂ was changed to 3 parts (3.3% based on solid content), PTFE was changed to 7 parts (7.8% solid content), and electrodeposition was applied under the same conditions as in Example 1. A test coating film having a dry film thickness of 10 μm was obtained.

Comparative Example 1
In Example 1, MoS ₂ was not added, PTFE was changed to 20 parts (25% based on solid content), and electrodeposition was applied under the same conditions as in Example 1 to obtain a test coating film having a dry film thickness of 10 μm. It was.

Comparative Example 2
In Example 1, MoS ₂ was changed to 14 parts (17.5% of solid content) and PTFE was changed to 6 parts (7.5% of solid content), and electrodeposition was applied under the same conditions to obtain a test coated plate.

Comparative Example 3
In Example 1, MoS ₂ was changed to 7 parts (7.8% solid content), PTFE was changed to 3 parts (3.3% solid content), electrodeposition was applied under the same conditions, and a dry film thickness of 10 μm was tested. A coated plate was obtained.

Measurement of Static Friction Coefficient Using a surface testing machine (Shinto Kagaku Co., Ltd. tribogear type HEIDON 14FW) equipped with a probe with a 5 mm diameter SUS304 ball attached to the tip, one ball (9.8 N) was used to load the ball. The static friction coefficient of the coating film was measured by sliding it 10 mm in the direction at a speed of 600 mm / min. The results are shown in Table 1.

High load conditions in a wear test outside diameter 25.6 mm, friction tester having a probe having a tip steel ring radial width 2.8 mm (Shinko Engineering Co. SFWT-PD (RD) -SM5000 -N2000-P5.5-OB150 (D300) -L1000-SS) and rotating the ring in one direction at a load of 350 N and 3,500 N at a speed of 500 rpm until the film thickness reaches 50% of the initial value. The wear resistance was evaluated with the total number of revolutions. The results are shown in Table 2.

As shown in Tables 1 and 2, generally, the coefficient of static friction is inversely proportional to the MoS ₂ / PTFE ratio, and the wear resistance tends to be directly proportional to MoS ₂ / PTFE. It can be seen that when MoS ₂ is in the range of 3 to 15 wt% and PTFE is in the range of 3 to 20 wt% with respect to the minute. The total amount of MoS ₂ and PTFE to the resin solids content of at this time, it was found that preferably in the range of 10 to 25 wt%.

[Part II]
Example 5
MoS ₂ fine powder and PTFE fine powder are mixed at a ratio of 0/100, 5/95, 10/90, 30/70, 50/50, 70/30, 90/10 and 100/0 by weight, and various A solid lubricant mixture in a proportion of 5% was prepared.

  The weight ratio of resin solids to solid lubricant is 95/5, 90/10, 80/20, 70/30 to an anionic alkyd resin of trade name S-161-LP manufactured by Dainippon Ink & Chemicals, Inc. Each lubricant mixture was added so that it would be 60/40, and this paint was electrodeposited onto a steel plate degreased with a solvent to a dry film thickness of 10 μm, washed with water and baked for 20 minutes at 230 ° C. Got.

Example 6
The solid lubricant mixture prepared in Example 5 was added to an anionic polybutadiene resin having a trade name of BN-1015 manufactured by Nippon Soda Co., Ltd., and the weight ratio of the resin solid content to the solid lubricant was 95/5, 90/10, Each lubricant mixture was added to 85/15, 80/20, 70/30, 60/40 and 50/50, and this paint was electrodeposited to a dry film thickness of 10 μm on a steel plate degreased with a solvent. And then baked at 230 ° C. for 20 minutes to obtain a test coating film.

In Examples 5 and 6, the weight ratio of paint resin solids, MoS ₂ and PTFE is shown in Table 3.

Using a surface testing machine (Tribogear type HEIDON 14FW manufactured by Shinto Kagaku Co., Ltd.) equipped with a probe with a 5 mm diameter SUS304 ball attached to the tip, the ball is unidirectional with a load of 1 kg (9.8 N). The tester was set in advance so that the test piece was automatically stopped when the coefficient of static friction of the test coating film reached 0.4, at a speed of 3000 mm / min (50 mm / s). The durability of the friction resistance was evaluated by the number of reciprocating slides until the static friction coefficient reached 0.4. The results are shown in Table 4 for Example 5 and in Table 5 for Example 6, respectively.

Table 6 shows the blending ratio (wt%) of MoS ₂ with respect to the resin. Further, based on the test results in Tables 4 and 5, the number of sliding operations was 1800 based on the alkyd resin base of Example 5. The region where the number of times of sliding is 3200 times or more in the polybutadiene resin base of Example 6 is indicated by a dotted line. Table 7 shows the blending ratio (wt%) of PTFE with respect to the resin. Further, in the same manner as in Table 6, the region in which the number of sliding is 1800 times or more based on the alkyd resin base of Example 5 is included. A region indicated by a thick line frame and having a polybutadiene resin base of Example 6 having a sliding frequency of 3200 times or more is indicated by a dotted line.

From Tables 6 and 7, in order to obtain a desired high load-resistant lubricating coating film in any alkyd resin-based and / or polybutadiene resin-based electrodeposition paint, MoS ₂ and PTFE are used as the electrodeposition paint. The solid lubricant consisting of a mixture having a weight ratio of 5:95 to 70:30 is 95: 5 to 50:50 by weight ratio of the electrodeposition coating resin solids and the solid lubricant (MoS ₂ + PTFE). It was found that the dispersion was effective.

Further, considering the types of resins used as the base material for the electrodeposition paint, Table 4 and Tables 6 and 7 show that MoS ₂ having a high rub resistance with an alkyd resin base and a sliding frequency of 1800 times or more and The blending ratio of the solid lubricant made of PTFE is within the range of 0.3 to 12.5 wt% for MoS ₂ and within the range of 4.7 to 23.8 wt% for PTFE with respect to the resin solid content (within the bold frame) The blending ratio of the solid lubricant exhibiting higher friction resistance with the sliding frequency of 2000 times or more is within a range of 0.3 to 7.5 wt% of MoS ₂ with respect to the resin solid content. PTFE Was found to be in the range of 5.0 to 23.8 wt%. The total amount of MoS ₂ and PTFE to the resin solids at this time, it is preferable to adjust within a range of 5.3~12.5wt% (see Table 4).

Therefore, considering the above results in light of the results of Part I, the blending ratio of the solid lubricant exhibiting high friction resistance based on the alkyd resin is such that MoS ₂ is 0.3 to 15 wt% with respect to the resin solid content. % Range, PTFE is preferably in the range of 3 to 33.8 wt%, more preferably in the range of MoS _{2 in} the range of ₃ to 7.5 wt%, and PTFE in the range of 4.7 to 23.8 wt%. Is to adjust in. Moreover, it is preferable to adjust the total amount of MoS ₂ and PTFE with respect to the resin solid content at this time within the range of 5.3 to 25 wt%.

Further, Table 5 and Table 6, Table 7, the mixing ratio of the polybutadiene resin basis number of slides consists of MoS ₂ and PTFE exhibits high abrasion resistance of more than 3200 times the solid lubricant, the solid content of the resin MoS ₂ is in the range of _2.5 to 33.3 wt%, PTFE is in the range of 5.3 to 95.0 wt% (refer to the inside of the one-dot chain line), and the number of sliding is more than 5800 times The blending ratio of the solid lubricant exhibiting high friction resistance is such that MoS ₂ is in the range of 4.3 to 21.4 wt% and PTFE is in the range of 8.8 to 90.0 wt% with respect to the resin solid content. I understood that. The total amount of MoS ₂ and PTFE to the resin solids at this time, it is preferable to adjust within a range of 17.6~100wt% (see Table 5).

Claims (6)

For electrodeposition paint
The weight ratio of the resin solids of the coating consisting of alkyd resin to the solid lubricant consisting of molybdenum disulfide and polytetrafluoroethylene is 95: 5 to 80:20, and
An electrodeposition coating material for forming a high-load-resistant lubricating coating film , wherein the weight ratio of the molybdenum disulfide and the polytetrafluoroethylene is dispersed so as to be 5:95 to 50:50 . The weight ratio of the resin solids to the solid lubricant is 90:10 to 80:20, and
The electrodeposition coating material for forming a high-load-resistant lubricating coating film according to claim 1, wherein a weight ratio of the molybdenum disulfide to the polytetrafluoroethylene is 10:90 to 30:70 . A method for forming a lubricating coating film that exhibits wear resistance under high load conditions, wherein the electrodeposition coating composition according to claim 1 is electrodeposited onto a substrate. For electrodeposition paint
The weight ratio of the resin solids of the paint consisting of polybutadiene resin to the solid lubricant consisting of molybdenum disulfide and polytetrafluoroethylene is 85:15 to 50:50, and
An electrodeposition coating material for forming a high-load-resistant lubricating coating film , wherein the weight ratio of the molybdenum disulfide and the polytetrafluoroethylene is 10:90 to 70:30 . The weight ratio of the resin solids to the solid lubricant is 80: 20-60: 40, and
The electrodeposition coating material for forming a high-load-resistant lubricating coating film according to claim 4, wherein a weight ratio of the molybdenum disulfide to the polytetrafluoroethylene is 10:90 to 50:50 . A method for forming a lubricating coating film that exhibits wear resistance under high load conditions, wherein the electrodeposition coating composition according to claim 4 or 5 is electrodeposited onto a substrate.