JPH0312441A - Sliding composition of fluorine-containing resin having high strength - Google Patents

Abstract

PURPOSE:To obtain a sliding composition of fluorine-containing resin having high strength having excellent wear resistance, strength and hardness, etc., and extremely low friction and frictional coefficient comprising plastic excepting fluorine resin or rubber and surface-treated fluorine resin powder. CONSTITUTION:(A) Plastic excepting fluorine resin or rubber, preferably heat- resistant resin such as epoxy resin or polyamide-imide is mixed with (B) surface- treated resin powder obtained by chemical treatment (preferably alkali metal solution method, especially alkali metal sodium method) or physical treatment (glow discharge, corona discharge or electron rays, especially glow discharge or corona discharge in single gas or mixed gas of ammonia, air or helium is preferable) to afford the aimed sliding composition of fluorine-containing resin having high strength containing 33-99vol% B.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a high-strength fluororesin sliding composition comprising a fluororesin and plastic or rubber, which has significantly improved adhesion to plastics and rubber. .

[Prior art and problems to be solved by the invention] Fluororesins such as tetrafluoroethylene copolymer (PTFE) have excellent properties of low friction, so they can be used alone or in mixtures with other inorganic powders and inorganic fibers. Alternatively, it is a mixture with a thermosetting resin such as an epoxy resin, and is used as a sliding material for various purposes in the form of molded objects (blocks, sheets, etc.) or paints. Solid lubricants based on fluororesin exhibit the lowest coefficient of friction when used as a single fluororesin, but when used as a sliding material, there are problems such as insufficient wear resistance and creep resistance. Due to this problem, they are often used in a composite form by adding fibers or thermosetting resins.

However, due to the hydrophobicity, oleophobicity, and poor reactivity of fluororesin, composite materials suffer from poor adhesion and poor mixing with composite additives, resulting in many problems in terms of mechanical strength. I'm leaving it behind.

In other words, conventionally, fluororesin and other plastics, etc. have been composited together and used as sliding materials, but due to the hydrophobicity, oleophobicity, and poor reactivity of fluororesin, poor adhesion and poor mixing with plastics, etc. occurs, wear resistance,
Deterioration of mechanical properties such as strength and hardness occurs. For this reason,
It is difficult to use under harsh conditions such as under high loads, and it is impossible to add a large enough amount of fluororesin to obtain low friction and wear coefficients. For example, PTF
In a composite system of E and a heat-resistant resin such as an epoxy resin, the content of the fluororesin is usually limited to 20 to 30% by volume. Despite the fact that significantly lower friction and wear coefficients cannot be obtained with such amounts of fluoropolymers,
Mechanical properties such as wear resistance, strength, and hardness often deteriorate.

As described above, there has been a problem in the past that it has not been possible to obtain a sliding material that has excellent mechanical properties such as wear resistance, strength, and hardness, and exhibits extremely low friction and wear coefficients.

In addition, untreated fluororesins have poor compatibility and are limited in the binders that can be used, forcing the use of expensive resins such as epoxy resins and polyamideimide resins, making it difficult to reduce prices.

Furthermore, mixing is difficult, poor dispersion occurs,
There is also the problem of increased prices due to problems such as decreased storage stability.

Conventionally, as a solution to the problems mentioned above, treatments such as the creation of additives that are compatible with fluororesin and microencapsulation have been carried out, but they are expensive and
There is a problem that sufficient performance is not achieved.

The present invention has excellent mechanical properties such as wear resistance, strength, and hardness,
The objective is to provide a material which exhibits extremely low coefficients of friction and wear.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a high-strength fluororesin sliding composition composed of plastic or rubber other than fluororesin and surface-treated fluororesin powder. It is.

[Effect]

Poor physical properties of fluororesin composite systems occur due to the hydrophobicity, oleophobicity, and poor reactivity of the fluororesin surface, so in the present invention, the fluororesin surface is subjected to surface treatment such as chemical conversion treatment or physical treatment. It improves adhesion to plastics and rubber, reduces the labor required for mixing, reduces the incidence of poor dispersion, and improves storage stability.

In the present invention, defluorination occurs in the extreme surface layer of the fluororesin particles, and functional groups such as hydroxyl groups and carboxyl groups are generated instead, so that the adhesion to the mating material can be improved. Furthermore, since the interior of the particle is an untreated fluororesin, the properties originally possessed by the fluororesin, such as sliding properties, non-adhesiveness, hydrophobicity, oleophobicity, and heat resistance, are not affected in any way. Because this type of surface-treated fluororesin is used, there is almost no decrease in mechanical properties such as wear resistance, strength, and hardness due to the decrease in friction and wear coefficient that is seen in composite systems using untreated fluororesin. I can't do it. Moreover, the volume percentage is 30~
Since 99% fluororesin can be used, molded bodies and coatings can be obtained that exhibit extremely low friction and wear coefficients and are excellent as sliding materials.

In this way, in the present invention, only the extreme surface layer of the fluororesin powder is activated by surface treatment such as chemical treatment or physical treatment, so it has higher mechanical strength than conventional fluororesin mixtures. can be expressed. Furthermore, since the surface treatment is only on the extreme surface layer, the high sliding properties of the fluororesin powder are not impaired. Therefore, it is possible to obtain a material that has both mechanical strength and excellent sliding properties, which were contradictory in the past. High-strength fluorine-containing resin sliding compositions with such excellent properties can be widely used as sliding materials in the form of molded articles or paints.

As the fluororesin suitable for use in the present invention, PTFE is preferred from the viewpoint of cost and sliding properties, but PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (
Tetrafluoroethylene-ethylene copolymer), PCT
FE (polychlorotrifluoroethylene), ECTF
E (chlorotrifluoroethylene-ethylene co-[combined])
, pVDF (polyvinylidene fluoride), P
The effect can be obtained with synthetic polymers having fluorine atoms in the molecule, such as VF (polyvinyl fluoride).

Furthermore, the average particle diameter of the fluororesin used in the present invention is 5 to
A thickness in the range of 50 μm is most effective.

There are no particular restrictions on the mating material to be composited as long as it is plastic or rubber other than fluororesin, but among them, epoxy, polyphenylene sulfide, polyimide, polyetherimide, polyether ether ketone,
Polysulfone, polycarbonate, polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, polyphenylene oxide, polyarylate, phenol, unsaturated polyester, silicone,
Heat-resistant resins such as polyamideimide are preferred.

Either chemical conversion treatment or physical treatment can be used for surface treatment, but alkali metal solution method, preferably alkali metal sodium method, is suitable for chemical conversion treatment, and glow discharge, corona discharge, or electron beam is used for physical treatment. This treatment method is suitable.

In the treatment using glow discharge, a plasma treatment method is preferable.

In addition, as a treatment agent for the alkali metal sodium method, any commonly used tetrahydrofuran solution of a complex compound of metal sodium and naphthalene or an ammonium solution of metal sodium may be used, but in terms of productivity, treatment cost, and safety of treatment operations. From the viewpoint of properties and the like, a treatment agent using a solution of a complex compound of sodium metal and naphthalene in tetrahydrofuran is preferable. In the case of treatment using the alkali metal sodium method, it is difficult to achieve uniform treatment and control the treatment using dipping and coating methods, which are the same as those used for treating plate-shaped and linear molded products with commercially available treatment agents. Therefore, it is desirable that the weight ratio of metallic sodium and fluororesin powder be in the range of 1:6 to 1:68. This is because when the weight ratio exceeds 1:68, surface treatment becomes impossible, and when the weight ratio falls between 1 and 6, the strength decreases.

That is, when the ratio of metallic sodium and fluororesin powder was mixed in the range of 1:1 to 1 by weight, and the treated fluororesin powder was placed in water, the ratio was 1:1 to 1:0.
All of the fluororesin powders treated at ratios up to 1:68 sank in water, but when the weight ratio exceeded 1:68, they floated on the water surface like untreated fluororesin powders. From this, it can be seen that the processable range is 1:1 to 1:68. Furthermore, a composite was prepared using the treated fluororesin powder with a ratio of tri to 1 x 68, and a bending strength test was conducted. The flexural strength of the composites was improved compared to that of the composites prepared using untreated fluoropolymer powder, but the flexural strength of the composites prepared using fluoropolymer powder treated at a ratio of 1:1 to 1:5 The flexural strength of the composites was equal to or lower than that of the composites treated with untreated fluororesin powder. This seems to be because if the treatment intensity is too strong, the treated layer will easily fall off.

The average particle diameter of the fluororesin powder used was 5 μm.
It is 50 μm. As described above, in the present invention, it is desirable that the ratio of metallic sodium to fluororesin is within the range of 1:6 to 1:68 by weight.

Further, in the case of treatment using glow discharge or corona discharge, it is preferable to generate glow discharge or corona discharge in a single gas such as ammonia, air, helium, neon, argon, nitrogen, or hydrogen or a mixed gas thereof. For example, when processing by plasma processing, fluororesin powder is placed in a vacuum container equipped with a stirrer, etc., the vacuum container is evacuated to 0°00 t to 0.00001 Torr, and then ammonia and air are added to the vacuum container. , helium, neon,
Either or more of argon and nitrogen may be introduced, turned into plasma by high frequency waves, microwaves, etc., and the fluororesin powder may be treated while stirring for several minutes to several tens of minutes.

The method of compounding the surface-treated fluororesin and the mating material (plastic or rubber other than fluororesin) may be any commonly used method such as kneader single type, roll type, or mill type, and is not particularly limited.

Further, a solvent necessary for mixing and additives such as a plasticizer and a curing agent necessary for molding can be added as appropriate.

The composite system produced according to the above method is a material that has excellent mechanical properties such as wear resistance, strength, and hardness, and exhibits extremely low friction and wear coefficients.

[Effects of the Invention] The present invention provides improved wear resistance, strength, and
This has the effect of providing a material that has excellent mechanical properties such as hardness and exhibits extremely low friction and wear coefficients.

Further, since there are no restrictions on the partner material forming the composite system, it can be selected as appropriate depending on the required properties. This solves the problems traditionally caused by the use of expensive mating materials and high temperature curing, and makes it possible to reduce product prices. Furthermore, due to the poor compatibility of the fluororesin, additives other than the fluororesin to the fluororesin or fluororesin composite system may aggregate during dispersion during the mixing of raw materials in a composite system containing a fluororesin due to surface treatment. This has the effect of solving the problem of difficulty and the problem that the storage stability of the raw material is significantly reduced when the raw material is a solvent dispersion system, and is a means of extending the life of the sliding paint. This can improve the negative effects of initial poor dispersion of raw materials and deterioration over time on mechanical properties such as strength and hardness, sliding properties, dispersibility, and storage stability of composite systems. This has the effect of making it possible to reduce the price.

In the present invention, since the effects as shown above can be obtained,
It can be applied to gears and bearings of electrical and electronic equipment such as compact discs and VTRs that require mechanical properties such as sliding properties, strength, and hardness. It is also suitable for bolts, nuts, etc. that come in contact with water, chemicals, etc. By being applicable to such areas, it is possible to solve the problems of bolts, nuts, etc. rusting and becoming loose, and impairing the purity of water and chemical solutions.

Furthermore, in cases where rubber is required to have sliding properties, such as in automobile wiper blades, it is possible to prevent frictional noise that occurs when the wiper blade and glass rub, and to achieve smooth sliding properties.

As described above, the present invention provides an inexpensive material that has excellent mechanical properties such as wear resistance, strength, and hardness, and exhibits extremely low friction and wear coefficients, and is therefore highly expected to make a contribution to industry. It is an invention.

〔Example〕

PTFE molding powder is treated with a tetrahydrofuran solution of a complex compound of sodium di-earth metal and naphthalene. The treated PTFE molding powder was mixed with polycarbonate, polyarylate, urea resin, and phenol resin, respectively, and plate-shaped composites of Examples 1 to 4 were produced by compression molding. The mixing ratio was 1:1 in terms of volume ratio. Friction coefficient, taper wear and bending strength tests were conducted on this molded body, and untreated PTFE
Performance comparisons were made with composites similarly produced using molding powder (Comparative Examples 1 to 4). This is shown in Table 1~
4.

Table 1 Polycarbonate composite (molding conditions i 100 kg/
c11.280”C) Urea resin composite (molding conditions: 250 kg/cT,
150°C) Phenolic resin composite (molding conditions: 350 kg/c)
J.

160°C) Table 2 Polyarylate composite (molding conditions: 200 kg/c)
d.

270'C) As can be seen from the results of the above examples, the coefficient of dynamic friction is not the same as that of the molded product made using untreated PTFE, and it is possible to improve the wear resistance against rough wear and the bending strength. Therefore, it becomes possible to develop a material that has both sliding properties and mechanical strength.

The PTFE molding powder is treated with two upper He-plasma and air-plasma. The plasma generation conditions were a high frequency output of 60 W and a container internal pressure of 0.02 Torr. Molded objects were produced using the treated PTFE molding powder in the same manner as in Examples 1 to 4, and the friction coefficient, taper wear, and bending strength tests were conducted to examine the effects of different surface treatment methods on physical properties. The results are shown in Table 5.6.

He-Plasma Air-Plasma As seen in the above examples, there is almost no difference depending on the surface treatment method, so a similar composite can be produced using any treatment method.

Process each powder of PFA, FEP, ETFE (ethylene-tetrafluoroethylene co-fc combination), and PCTFE (polychlorotrifluoroethylene) with a tetrahydrofuran solution of a complex compound of sodium metal and naphthalene in Sugo 1 Raw 1. . Example 4 The treated four types of fluororesin
and polycarbonate in the same manner as in Example 1.
3 to 16 molded bodies were produced.

Friction coefficient, taper wear and bending strength tests were conducted on this molded body, and untreated PFA, FEP, ETFE,
Performance comparisons were made with composites similarly prepared using each PCTFE powder (Comparative Examples 5 to 8). This result is shown in Table 7.
~10.

Table 7 Table 8 PFA composite (molding conditions; 100 kg/cd, FEP
Composite (molding conditions; 100 kg/cd, 280°C) Table 9 Table 10 ETF Snake composite (molding conditions; 100 kg/cd, 26
0°C) PCTFE composite (molding conditions: 100 kg/cd, 2
60° C.) As seen in the results of the above examples, the effect can be obtained if the synthetic polymer has a fluorine atom in the molecule. Therefore, it is possible to appropriately select the type of fluororesin depending on the application.

11 Treat PTFE molding powder with a tetrahydrofuran solution of a complex compound of metal sodium and naphthalene. This treated PTFE molding powder was mixed with a mixed powder of epoxy resin and phenol resin, and a plate-shaped composite was produced by compression molding (Example 17). The mixing ratio was 99:1 by volume.

This composite was tested for friction coefficient, thrust wear, taper wear, creep resistance, compressive strength, and release performance after polishing of the composite, and the performance was compared with a commercially available Teflon plate (Comparative Example 9). The results are shown in Table 11.

Table 11 Chemical conversion treated PTFE composite (molding conditions: 200 kg/Cl
1゜100°C x 1 minute, 200°C x 30 minutes) As seen in the results of the above examples, thrust wear, taper wear, creep resistance, and compressive strength were significantly improved, and friction coefficient and thrust wear were significantly improved. In terms of taper wear and mold releasability, the results are almost comparable to those of Teflon. This chemical conversion treated PTFE molded body can be formed at about half the curing temperature of a normal Teflon plate, and is a material that surpasses Teflon plates in many physical properties.

Mixed gas with a volume ratio of 5 parts ammonium gas to 100 nitrogen gas, high frequency output 50 W, and internal pressure in the container 0.02
The PTFE molding powder is processed by plasma generation under Torr conditions.

Further, the PTFE molding powder is treated with a tetrahydrofuran solution of a complex compound of sodium metal and naphthalene.

These treated PTF molding powders were mixed with butadiene rubber (BR), nitrile rubber (NBR), and styrene-butadiene rubber (SBR) to prepare filled rubbers of Examples 18 to 23. The compounding method is to add 30 parts by weight of surface-treated PTFE powder to 100 parts by weight of rubber, and add a vulcanizing agent (sulfur).
, add stearic acid, an appropriate amount of anti-aging agent,
, Kneading is performed using a Lee mixer. The vulcanization conditions are 1
The temperature was set at 45°C for 30 minutes.

Regarding this filled rubber, the friction coefficient was measured and the minute t- was generally observed, and a comparison was made with a filled rubber similarly prepared using untreated PTFE mono 1 noding powder. The results are shown in Table 12.

Table 12 Sliding properties of surface-treated PTFE-containing rubber Example 18 above
By using the PTFE molding powder subjected to chemical conversion treatment and plasma treatment from 23 to 23, a rubber material having slipperiness can be obtained. Therefore, rubber S! If wiper blades and the like, where frictional noise is a problem, are made from this composite, the frictional noise of rubber can be eliminated.

In addition, in the rubber system containing untreated PTFE shown as a comparative example, the non-adhesion of PTFE suffered during the mixing process, and there was no increase in torque indicating progress of dispersion during mixing with rubber, and PTFE
FE was not uniformly dispersed, the rubber after vulcanization had a powdery state, and the coefficient of dynamic friction also varied greatly.

PTFE lubricant powder is treated with a tetrahydrofuran solution of a complex compound of sodium metal and naphthalene. The treated PTFE lubricant powder was mixed with commercially available urethane and epoxy resin paints, respectively, to prepare the coating films of Examples 24 and 25. The mixing ratio in terms of solid content was 60 parts by weight of the urethane and epoxy resin paint to 10 parts by weight of the PTFE lubricant powder.

Friction coefficient and thrust wear tests were conducted on this coating film, and the performance was compared with coating films similarly prepared using untreated PTFE lubricant powder (Comparative Examples 16 and 17). The results are shown in Table 13.14.

Table 13 Table 14 Urethane paint (film forming conditions: infrared drying 60-80'CX2
Time) Epoxy resin (film forming conditions: infrared drying 60-80°
(CX10 minutes hot air circulation drying 140°C x 20 minutes) As seen in the results of the above examples, excellent abrasion resistance can be obtained even when used as a paint.

Actual cliff■1/2 Main process Mixed gas at a volume ratio of 100 parts helium gas to 5 parts ammonia gas, high frequency output 50 W, container internal pressure 0.02
Plasma is generated under Torr conditions and PTFE lubricant powder, PFA powder, and FEP powder are treated respectively.

Also, tetrahydrofuran, a complex compound of sodium metal and naphthalene? Each of the PTFE resin powder, PFA powder, and FEP powder is treated with the liquid.

These six types of powder were mixed with commercially available polyamide-imide varnish and phenol varnish, and the dispersibility and storage stability after dispersion were examined. For comparison, similar tests were also conducted on the three types of untreated perfluoro resin powders mentioned above. The results are shown in Table 15.

Table 15 Dispersibility and storage stability of polyamide-imide varnish composite system Table 16 Dispersibility and storage stability of phenol varnish composite system The storage stability of is significantly improved. Therefore, it is possible to reduce the labor required for dispersion. In addition, since the storage stability is significantly improved, it is possible to reduce the number of cases where the product becomes unusable during storage and is discarded, which is a great advantage in terms of production.

Claims (7)

[Claims] (1) A high-strength fluororesin sliding composition comprising plastic or rubber other than fluororesin and surface-treated fluororesin powder. (2) The fluororesin is a perfluoro resin consisting of one or more of a tetrafluoroethylene polymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. Certain claims (1)
The high-strength fluororesin sliding composition described above. (3) The high strength fluororesin sliding composition according to claim 1, wherein the surface treatment is either a chemical conversion treatment or a physical treatment. (4) The high-strength fluororesin sliding composition according to claim (3), wherein the chemical conversion treatment is a treatment using an alkali metal solution method. (5) The high-strength fluororesin sliding composition according to claim 3, wherein the physical treatment is any one of glow discharge, corona discharge, and electron beam treatment. (6) The treatment using glow discharge or corona discharge generates glow discharge or corona discharge in a single gas such as ammonia, air, helium, neon, argon, nitrogen, or hydrogen or a mixture thereof to treat the fluororesin powder. The high-strength fluororesin sliding composition according to claim (5). (7) The high-strength fluororesin sliding composition according to claim (1), which contains the surface-treated fluororesin powder in a volume percentage of 30 to 99%.