JPH0737536B2 - Sliding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding material.

[Conventional technology]

Urethane rubber-like elastic materials include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR),
Compared with synthetic rubber materials such as isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR), and acrylic rubber, it has superior lubricity and wear resistance (particularly tear resistance). It is widely used as a paper feed roller for equipment, a kneading roller for food processing equipment, a safety pad or glass run for automobiles, various valves, oil seals, etc., but its sliding characteristics are not satisfactory, and a large driving force is required. Need, make a fricative,
Not only does it cause a streak slip, but also the frictional resistance increases as the time of use increases, the wear increases, and the heat generated in the sliding part also increases, which causes the deformation of the rubber-like elastic body itself. It will be. Further, since the urethane rubber elastic body is inferior in water resistance, its use conditions (atmosphere, time, etc.) must be considerably restricted.

Generally, in order to reduce the frictional resistance of a sliding material having rubber-like elasticity, an ITO resin film is attached to the surface of the sliding material (for example, Japanese Patent Publication No. 46-23681), and a film-forming property is used. For example, apply a liquid in which a solid lubricant such as fluorine resin is dispersed in an organic solvent in which the coalesce is dissolved and bake it, or bake a fluoroalkyl copolymer in which polyfluoroalkyl is copolymerized with other monomers. The method is adopted.

However, each of these methods has the following drawbacks. That is, since the adhesiveness of the fluorine resin film to the substrate is very poor in the method (1), it is necessary to carry out a surface treatment (by alkali metal or ion sputtering) beforehand, even if the surface treatment is not performed. However, the adhesiveness is insufficient and the film often peels off during use, and it is difficult to use for molded products with complicated shapes.
It is superior to method (a) in terms of adhesive strength and reduction of baking temperature, but it is a polymer that does not inherently have properties such as lubricity or a monomer that is randomly or block-shaped by copolymerization. However, there is a drawback that sufficient lubricity does not appear because of the use.

[Problems to be solved by the invention]

As described above, there is a problem that none of the conventional urethane-based rubber-like elastic bodies has satisfactory lubricity, wear resistance, and water resistance.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a urethane-based coating film made of a fluorinated polyether polymer having a unit containing a polar group having reactivity or affinity with the urethane-based rubber-like elastic material. The means for providing the rubber-like elastic body on a part or the whole of the surface thereof is adopted, and its details will be described below.

First. The urethane-based rubber-like elastic body of the present invention is a rubber-like elastic body obtained by the reaction of polyester polyol, polyether polyol, other polyols and isocyanate. As the polyester polyol, a polybasic acid (eg, adipic acid, succinic acid, sebacic acid, phthalic acid, other aliphatic or aromatic dicarboxylic acid, etc.) and a polyhydric alcohol polymer (eg, polyethylene glycol, polydiethylene glycol,
(Polypropylene glycol, polydipropylene glycol, polybutylene glycol, other diol polymers, triol polymers, etc.), which are reaction products with polyester polyols or ring-opening polymers of cyclic esters. Here, the polyhydric alcohol polymer is not particularly limited in its molecular weight, but in order to be a suitable rubber-like elastic material, a polymer of about 1000 to 3000 is suitable. Also,
The polyether polyol is obtained by ring-opening polymerization of an epoxide or tetrahydrofuran, and a polyether polyol obtained by adding an epoxide to a compound having at least two hydrogen atoms to which these cyclic ethers can be added is suitable. This epoxide is, for example, ethylene oxide, propylene oxide, butylene oxide, etc., and the compound that gives a hydrogen atom that can be added to the cyclic ether is, for example, the above-mentioned polyhydric alcohol polymer, polyphenol, polyamide, polyamine, etc., Among them, polyhydric alcohol polymers, that is, the molecular weight is not particularly limited, but polyethylene glycol (molecular weight of about 1000 to 6000), polypropylene glycol (molecular weight of about 1000 to 2000), polytetramethylene glycol and the like are preferable. Further, other polyols are, for example, polybutadiene-based glycols, polyester polyols, polycarbonate polyols and the like, which are composed of a homopolymer of butadiene or a copolymer with acrylonitrile or styrene. Further, the isocyanate is required to be a polyisocyanate having two or more aliphatic or aromatic functional groups, but the more the functional groups are, the easier the crosslinking becomes and the rubber elasticity is lost. Therefore, for example, hexamethylene-1,6 Diisocyanates such as -diisocyanate, toluene-2,4-diisocyanate, metaphenylene diisocyanate, naphthalene-1,5-diisocyanate and diphenylmethane-4,4'-diisocyanate are preferred.

Such urethane-based rubber-like elastic body is made into a prepolymer composed of various polyols and isocyanates, and a crosslinking agent such as 1,4-butanediol, methylenebisdichloroaniline, trimethylolpropane or triisopropanolamine is added thereto. It may be crosslinked, or a urethane thermoplastic elastomer which is a block copolymer composed of a combination of three components of a bifunctional polyol that constitutes a soft segment, a short chain glycol that constitutes a hard segment and a diisocyanate. However, this does not hinder the present invention.

Next, the polar group showing reactivity or affinity for the urethane-based rubber-like elastic body of the present invention, for example, -NCO,
-OH, -COOH, -NHR ₁ (wherein R ₁ is hydrogen, an alkyl group or an alkoxy group), -SH, —COOCH ₃ , —SO ₃ H, —SO ₂ F, etc., and a fluorinated polyether polymer having a unit containing such a polar group is —C _X F _2X —O— (where X is 1 Is a polymer having an average molecular weight of about 1000 to 10000 as a main structural unit, and the perfluoropolyether group improves lubricity and wear resistance, and the polar group is a fluorinated polyether polymer. It helps improve the adhesion between the united film and the urethane-based rubber-like elastic material. As described above, the urethane-based rubber-like elastic material of the present invention is formed on the basis of a urethane bond formed by the reaction of an isocyanate with an active hydrogen group. It may also include a bond such as --NCO or --O at the side chain or terminal.
Since functional groups such as H and -NH ₂ often remain, they have reactivity with active hydrogens such as urethane bond and urea bond, -OH group or -NH ₂ group among the polar groups described above. Show −N
CO, Etc., or —OH reactive with a side chain or a terminal —NCO group, —NHR ₁ , —COOH, —SH and the like are preferable,
Those in which these groups are located at both ends of the fluorinated polyether polymer are the most effective and are particularly preferable. Also, −
Fluorine-containing polyether polymer having a unit containing NCO and fluorine-containing polyether polymer having a unit containing -OH further improve abrasion resistance, so that different polar groups are contained. It is also possible to use together different kinds of fluorinated polyether polymers having units. The specific examples of the above fluorinated polyether polymers are as follows, and it goes without saying that they may be used alone or in combination. That is, _{HOOC-CF 2 OC 2 F 4} O m CF 2 O n CF 2 COOH, _{H 3 COOC-CF 2 OC 2} F 4 O m CF 2 O n CF 2 COOCH 3, HOCH 2 -CF 2 OC 2 F 4 O m CF 2 O n CH 2 OH, Etc., and a method in which a fluorine-containing polyether polymer in which the polar group is a hydroxyl group and an isocyanate containing no various polyfluoropolyether group are used together, or a fluorine-containing polyether polymer in which the polar group is an isocyanate group It is also possible to employ a method in which a diamine, a triamine, a diol or a triol having no various polyfluoropolyether groups are used together.

The fluorinated polyether polymer of the present invention reacts with a urethane-based rubber-like elastic body or a fluorinated polyether polymer as long as it does not adversely affect its properties such as lubricity, abrasion resistance and adhesion to a substrate. An organopolysiloxane or polyfluoroalkyl polymer having a polar group having a polar property may be appropriately added, but in order to maintain extremely excellent abrasion resistance, the fluorinated polyether polymer is the main structural unit. Is desirable.

In order to form such a film of a fluorinated polyether polymer, generally, an organic solvent (for example, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, ethyl acetate and isoamine acetate, diethyl ether, dioxane, etc. Ethers, methylchloroform, trichloroethylene, tetrachloroethylene, tetrachlorodifluoroethane, 1,1,2-trichloro-1,2,2
-Urethane coating solution obtained by dissolving or dispersing a fluorinated polyether polymer in halogenated hydrocarbons such as trifluoroethane [CFC 113] or a mixture of two or more thereof with an appropriate viscosity. It may be sprayed on the rubbery elastic body or immersed in the coating liquid, but the dipping method is preferable from the viewpoint of reducing the consumption of the coating liquid. The concentration of the fluorinated polyether polymer in this coating solution is not particularly limited, but the cost is 0.3 to 10.0.
It can be said that the amount is preferably about 0.5% by weight, especially about 0.5 to 5.0% by weight, considering the characteristics of the thin film to be formed. Further, after the coating film is formed, it is dried, and the surface thereof is polished with a soft cloth or paper to give a gloss. However, it is preferable that the excess fluorinated polyether polymer is simultaneously removed by such an operation. This is because when the coating is too thick, it contains an excessive amount of fluorinated polyether polymer in the coating, and as a result, it has many free reactive groups that are not involved in the adhesion with the urethane rubber elastic body. This is because lubricity and wear resistance, which are indispensable for sliding materials, are adversely affected. The main purpose of the drying after forming the coating film is to remove the organic solvent, but in order to enhance the reactivity between the polymer in the coating film and the substrate, it may be heated during the drying or a heat treatment after drying. May be inserted as appropriate.

〔Example〕

The raw materials used in Examples and Comparative Examples are summarized below. In addition, in order to simplify the substance names or structural formulas, the numbers added at the beginning of each raw material will be used, and the compounding ratios will all represent% by weight.

(1) Urethane-based rubber-like elastic body Polyester-type urethane rubber (Tigers Polymer Co., Ltd .: Typeren TR100-7, hardness JISA scale 70), (2) Fluorinated polyether polymer (Made in Italy by Montefluos: Huonpurin Z-DISOC,
Average molecular weight of about _{2000), HOOC-CF 2 OC} 2 R 4 O m CF 2 O n CF 2 COOH ( manufactured by the same company: Fuonburin Z-DIACID, about average molecular weight 200
_{0), HOCH 2 -CF 2 OC} 2 F 4 O m -CF 2 O n CF 2 CH 2 OH ( manufactured by the same company: Fuonpurin Z-DOL, about average molecular weight 200
_{0), F 3 C-CF} 2 OC 2 F 4 O m CF 2 O n CF 3 ( manufactured by the same company: Fuonburin Z-25, average molecular weight of about 1600
0), (3) Organopolysiloxane Carboxyl group-containing polysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd .: carboxyl-modified silicone oil X-22-3701)
E), hydroxyl group-containing polysiloxane (manufactured by the same company: Silicone diol X-22-160C), amino group-containing polysiloxane (manufactured by the same company: amino-modified silicone oil X-22-3801C), (4) fluoroalkyl polymer hydroxyl group-containing polysiloxane Fluoroalkyl Polymer C ₈ F ₁₇ C ₂ H ₄ OH Copolymer of Perfluoroalkyl and Methyl Methacrylate (Nippon Yushi Co., Ltd .: Hydroxyl Group-Containing Perfluoroalkyl Copolymer, Modeper F100), Examples 1 to 3: Urethane As a rubber-like elastic body, a test piece for a friction / wear test was prepared from a plate-shaped molded product of the above raw material. On the other hand, as the fluorinated polyether polymer, the raw materials and were used, as shown in the table. And
These fluorinated polyether polymers were dissolved in Freon 113 so as to have a concentration of 2.0% to obtain a coating solution for dipping the urethane rubber elastic test piece. The test piece immersed in this coating solution was dried and heat treated at 70 ° C for 1 hour. After the test, it was used for measurement of lubricity, abrasion resistance, water repellency, etc. For the lubricity and wear resistance, use a thrust type friction tester (made in-house), load 3 kg / cm ² , speed 1 min / min.
The bearing steel (SUJ2) was tested under the condition of m, and the lubricity was judged from the magnitude of the friction coefficient, and the wear resistance was judged from the stability of the change over time of the friction coefficient. For water repellency, the contact angle of the test piece with water was determined using a goniometer contact angle tester manufactured by Elma Optical Co., Ltd. The results obtained are summarized in the table.

Comparative Examples 1 to 7: Instead of the fluorinated polyether polymer in Examples 1 to 3 above, different polymers as shown in the table were used.
Examples 1 to 1 except that (Comparative Example 1 has no polymer)
A test piece similar to 3 was prepared. However, in Comparative Example 7, the copolymer was added to a mixed solution (1: 1) of cyclohexanone and methyl isobutyl ketone at a concentration of 3%.
A coating liquid was prepared by dissolving together with a curing agent (hexamethylene diisocyanate) and a catalyst (dibutyltin dilaurate). The conditions of drying and heat treatment after immersion in this coating solution are exactly the same as those in the examples. The measurement results of the obtained test pieces are also shown in the table.

As is apparent from the table, in Examples 1 to 3, not only the coefficient of friction is low, but there is little fluctuation during the sliding period, and a stable low value is maintained even for long-term sliding. In addition, all of them show very excellent wear resistance. On the other hand, the friction coefficient in Comparative Example 1 in which the coating film was not formed on the surface of the base material was relatively low at the initial stage of sliding, but sharply increased with the elapse of sliding time, and did not exceed 120 minutes. The test piece generated heat enough to cause thermal deformation (the values in parentheses in the table are estimated values). Further, Comparative Example 2 using a fluorinated polyether polymer having no polar group and a polysiloxane containing a reactive group, Comparative Examples 3, 4 and 5, and a fluoroalkyl polymer containing no polyether ( The friction coefficient in Comparative Example 6 using (including a hydroxyl group as a polar group) increased with the passage of sliding time even when the value was very low at the initial stage of sliding, and a comparison using the fluoroalkyl copolymer (10) was made. The friction coefficient in Example 7 was a high value from the initial stage of sliding, and gradually increased as the sliding time passed. Therefore, Comparative Example 1
It can be said that the abrasion resistance and wear resistance of No. 7 are far inferior to those of Examples 1 to 3. Further, the water repellency in Examples 1 to 3 was superior to that in Comparative Example 1 as is clear from the table.

〔effect〕

As described above, the sliding material of the present invention is coated in close contact with the elastic body in addition to the characteristics such as the excellent sealability of the urethane rubber elastic body, the followability to deformation, and the vibration damping property. Since the lubricating thin film also has excellent abrasion resistance, abrasion resistance, and water resistance, it has extremely high stability and reliability against long-term sliding. For example, automobiles, office equipment, automatic control It can be widely used as parts in all fields such as equipments, aviation / space equipments, medical equipments, other electric / electronic equipments, and general industrial machinery. Above all, it is a suitable material for a paper feed roller of a copying machine, a kneading roller in the food industry, a safety pad of an automobile, a glass run or a wiper blade, various shock absorbing materials, various valves, an oil seal, etc. It can be said that the significance is extremely large.

Claims (1)

[Claims] 1. A part of the surface of a urethane-based rubber-like elastic body is coated with a film made of a fluorinated polyether polymer having a unit containing a polar group showing reactivity or affinity with the urethane-based rubber-like elastic body. Alternatively, a sliding material characterized by being provided in all.