JP2520423B2 - Lubricating rubber composition - Google Patents

Description

The present invention relates to a lubricating rubber composition.

[Conventional technology]

Conventionally, diene rubbers have excellent oil resistance, abrasion resistance, rubber elasticity, mechanical strength, etc., and dust boots such as oil seals, glass runs, constant velocity joints, various valves, toner seals, etc. However, in recent years, with higher performance and higher speed of machines and automobiles, those used for sliding parts have been required to have even better lubricity. Also, copiers, printers,
For equipment used indoors, such as information-related equipment such as facsimile machines and computers, the noise generated when they operate is a significant problem as noise, and therefore has a noise reduction function and excellent sliding characteristics. The demand for rubber molded products has increased. More recently, in optical devices such as compact disks, video disks, and optical files that use semiconductor lasers, in order to correctly read the bit information on the disk surface at the spot connected by the condenser lens, these devices must be externally used. There has been a demand for a sliding material having excellent lubricating properties, which also has a good vibration damping action against vibrations applied to the material.

For the purpose of satisfying these requirements, many attempts have been made to use a synthetic resin having good slidability, for example, polyamide, polyacetal, polyolefin, fluororesin, or to blend various elastomers with these resins. The properties of the rubber itself such as sealability, followability, vibration damping properties, sound-absorbing properties, etc. are hardly utilized, and the diene rubber composition of the conventional compounding composition can be said to have satisfactory sliding properties. Not only requires a large driving force, generates a frictional noise, causes stick-slip, but also increases the frictional resistance with prolonged use time, intensifies abrasion, and further generates heat in sliding parts. And the rubber-like elastic body itself is deformed. Generally, in order to reduce the frictional resistance of a sliding material having a rubber-like elastic body, for example, on the surface of the rubber-like elastic body, for example, Japanese Patent Publication No.
As shown in Japanese Patent Publication No. JP-A-57-32950, a method of laminating a fluororesin film (abbreviated as a sticking method). Method of applying (abbreviated as fusion method), method of applying and baking liquid in which solid lubricant such as fluororesin is dispersed in organic solvent in which film-forming polymer is dissolved (abbreviated as application method) or fluororesin A method (abbreviated as mixing method) has been adopted in which a solid lubricant such as the above or a lubricating oil such as a silicone oil is separately or simultaneously mixed with the rubber elastic body, but each of these methods has the following drawbacks. There is.
That is, in the sticking method or the fusion method, the adhesiveness of the fluororesin film or the olefin resin film to the substrate is very poor, and particularly in the case of the fluororesin film, a surface treatment (treatment by alkali metal or ion sputtering or the like is performed beforehand). ) Is required, even if the surface is treated with a fluororesin film or an olefin resin, the adhesion is insufficient and the film peels well during use. However, since it is difficult to use for molded products with complicated shapes and the film thickness is large, it adversely affects various characteristics such as excellent sealing properties, followability, and vibration damping properties that the rubber-like elastic body originally has. There are drawbacks such as exerting it. And, in the following coating method, in terms of adhesive strength, it is superior to the above-mentioned sticking method and fusion method,
Since a polymer that does not originally have lubricity is used, it is difficult to exert sufficient lubricity. Further, in the mixing method, when a solid lubricant is blended, a small amount causes poor lubricity, and a large amount. In the case of, the original characteristics of the rubber-like elastic body are obstructed, and when blending a lubricating oil, it tries to develop the sliding characteristics by leaching the lubricating oil during sliding. The coefficient is not stable at a small value, the oil leaches out when the temperature rises, the moldability is poor, and the oil easily separates during molding or kneading.
There are many problems such as impairing various properties of the base material, contamination of the sliding surface with oil and easy adhesion of dust, and abnormal wear once the oil runs out.

[Problems to be solved by the invention]

As described above, in the conventional technology, the functions originally possessed by the rubber-like elastic body such as the sealing property, the following property, the sound deadening property, and the vibration damping property are not deteriorated, and the friction coefficient is stable at a small value. However, there is a problem that a material having a small wear coefficient cannot be obtained, and that many rubber-like elastic bodies having excellent characteristics are not suitable for sliding materials that require a low friction coefficient.

[Means for solving problems]

In order to solve the above problems, the present invention provides 3 to 100 parts by weight of an organopolysiloxane or a fluoropolymer containing at least one type of an isocyanate group or a cyanate group per 100 parts by weight of a diene rubber. This is a means for producing a lubricating rubber composition blended with parts by weight. The details are described below.

First, the diene-based rubber of the present invention is obtained by homopolymerizing or copolymerizing a diene monomer, and has properties originally possessed by a rubber-like elastic body such as sealing property, conformability to deformation, vibration damping property, and sound deadening property. Examples of the elastic rubber include natural rubber, and synthetic rubber such as butadiene rubber, isopropylene rubber, chloroprene rubber, styrene butadiene rubber, and acrylonitrile butadiene rubber.
However, the diene-based rubber of the present invention does not include an acrylonitrile-butadiene-based resin such as an ABS resin that does not originally have the characteristics of the rubber-like elastic body.

Next, in the present invention, an organopolysiloxane containing at least one kind of an isocyanate group and a cyanate group is a homopolymer of organopolysiloxane such as dimethylsiloxane, methylphenylsiloxane, trimethylfluoropropylsiloxane, or two or more kinds. A copolymer in which an isocyanate group and a cyanate group are introduced. Specifically, an isocyanate group-containing organopolysiloxane Cyanate group-containing organopolysiloxane [Wherein R is an alkylene group, m = 5-10000, n = 2
~ 100. ] Etc. can be illustrated.

Further, the isocyanate group in the present invention, the fluorine-containing polymer containing at least one kind of group of cyanate group is a polyfluoroalkyl or polyfluoroether in which at least one kind of isocyanate group, cyanate group is introduced. This polyfluoroalkyl is a polymer having a polyfluoroalkyl group having 2 to 20 carbon atoms, and for example, Can be cited as an example. The polyfluoroether is a polymer having —C _X F _2X —O— [wherein X is an integer of 1 to 4] as a main structural unit and having an average molecular weight of 500 to 50,000, and specifically, OCN- _{C 6 H 3 (CH 3)} -NHCOCF 2 C 2 F 4 O m CF 2 O n
_{CF 2 CONH- (CH 3) C} 6 H 3 -NCO ( molecular weight: about _{2000), NCOCH 2 -CF 2 OC} 2 F 4 O m CF 2 O n CF 2 -CH 2 OCN
(Molecular weight about 2000), NCOCH ₂ (CF ₂ ) ₂ O (CF ₂ ) ₄ O (CF ₂ ) ₂ CH ₂ OCN, etc.

Further, the liquid diene polymer containing a hydroxyl group in the present invention is obtained by homopolymerization or copolymerization of a diene monomer, and has a molecular weight of 500 to 50,000, preferably 500 to 10,000, Content is 0.1-1
It is of 0.0meq / g and is liquid at room temperature. Then, specific examples of the liquid diene-based polymer include butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, and butadiene-polymer.
Examples thereof include isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate and the like.

The diene rubber and the liquid diene polymer described above are not particularly limited, but a vulcanizing agent for rubber may be used in combination. Examples of the vulcanizing agent include sulfur vulcanizing type and organic peroxide vulcanizing type, but not to mention the crosslinking reaction of the diene rubber itself, when the liquid diene polymer coexists, It is desirable to cause a crosslinking reaction between the liquid diene polymers and between the diene rubber and the liquid diene polymer.

In this invention, when an organopolysiloxane or a fluorine-containing polymer is blended with a diene rubber to obtain a rubber composition having excellent lubricity, the reason why only an isocyanate group or a cyanate group exhibits a particularly good effect is not clear. However, many fillers that are widely used in diene rubbers, such as carbon black, silica, clay, kaolinite, mica, etc., often have active hydroxyl groups on their surface and have high reactivity with the hydroxyl groups. Due to the isocyanate group or the cyanate group, the lubricating substance is firmly held on the surface of the filler, which makes it difficult to desorb,
It is presumed that good lubricity can be obtained for a long time even during sliding without "bleeding out" during molding. Such a thing can also be said for the liquid diene-based polymer having a hydroxyl group as described above, and an organopolysiloxane or a fluorine-containing polymer and a liquid diene having at least one kind of an isocyanate group or a cyanate group. The organopolysiloxane or fluorine-containing polymer has strong compatibility with part or all of the functional groups that the polymer has and the organopolysiloxane or fluoropolymer has good compatibility with the diene polymer of the liquid diene polymer. From the diene polymer can be uniformly dispersed in the structure of the diene polymer, and further a network of the diene polymer formed by crosslinking the organopolysiloxane or the fluoropolymer or the diene rubber and the liquid diene polymer. Since it is firmly held in the mesh, it is not affected by external stress such as shearing force or compressive force caused by sliding or heat. It is difficult to dissociate even when stimulated, and its movement within the material structure is restricted, so that it exerts excellent lubricity over a long period of time without adversely affecting the heat resistance and mechanical strength originally possessed by rubber elasticity. It can be presumed to be possible. Therefore, the functional group contained in the organopolysiloxane or the fluoropolymer is preferably present at both ends rather than at one end because it increases the number of reaction points.
A part of the skeleton of the liquid diene-based polymer or diene-based rubber is composed of the organopolysiloxane or the fluorine-containing polymer, and these lubricating substances can be used without destroying the network structure of the rubber elastic body. It occupies a larger surface area and can exhibit excellent lubricity and wear resistance.

In the present invention, the mixing ratio of the organopolysiloxane or the fluoropolymer is preferably 3 to 100 parts by weight based on 100 parts by weight of the diene rubber. This is because if the amount is less than 3 parts by weight, the effect of improving the lubricity is insufficient, and conversely, if the amount is more than 100 parts by weight, the mechanical strength of the diene rubber is significantly reduced, which is not preferable. When the liquid diene polymer is used in combination, the total amount of the organopolysiloxane or the fluoropolymer and the liquid diene polymer is 5 to 100 parts by weight based on 100 parts by weight of the diene rubber. desirable. This is because if the amount is less than 5 parts by weight, the effect of improving the lubricity cannot be expected, and if the amount exceeds 100% by weight, the original mechanical strength of the diene rubber is significantly reduced, which is not preferable. The mixing ratio of the liquid diene yarn polymer to the organopolysiloxane or the fluorine-containing polymer is not particularly limited, but from the viewpoint of fully exerting the effects of the present invention, the organopolysiloxane or the fluorine-containing polymer is used. It can be said that it is preferable that the amount of the liquid diene yarn polymer has a hydroxyl equivalent which corresponds to the chemical equivalent of the isocyanate group or the cyanate group contained in the polymer.

Here, as described above, it is desirable to use a vulcanizing agent for rubber in order to crosslink the diene rubber and the liquid diene polymer, but the addition amount of the vulcanizing agent at that time is diene rubber and liquid. Taking into consideration the type of diene polymer, the composition ratio, the type of vulcanizing agent, and the like, in general, the amount may be 0.1 to 20.0 parts by weight.

Further, for the lubricating rubber composition of the present invention, various additives commonly used in the rubber industry can be appropriately used. Examples of the additive include carbon black, silica, clay, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum oxide, talc, mica, kaolinite, bentonite, shirasu, silicon carbide, aramid resin, and phenol resin. Such as powder or fiber filler, zinc white, vulcanization aid such as fatty acid, guanidines, sulfides, vulcanization accelerators such as aldehyde-amines, zinc stearate,
Stabilizers such as lead phosphite and barium phosphite, plasticizers such as dimethyl phthalate and dioctyl phthalate, antiaging agents such as amines and phenols, such as 2,6-di-t-butyl-p-cresol Examples thereof include antioxidants, ultraviolet absorbers such as acrylonitrile derivatives, flame retardants such as antimony oxide and zircon oxide, and colorants such as cadmium yellow, phthalocyanine blue and titanium white.

As described above, the method of mixing the main raw material and other various raw materials in the present invention may be a well-known method, and is not particularly limited. In other words, each raw material is open roll, Banbury mixer,
Even if they are mixed at the same time using a conventional mixer such as a kneader, or for the purpose of efficiently reacting the hydroxyl group contained in the liquid diene polymer with the isocyanate group or the cyanate group of the organosiloxane or the fluoropolymer, It is also possible to mix only these main components in advance and then add other raw materials as appropriate, such as mixing in stages. Further, in order to improve the dispersibility of the organopolysiloxane or the fluoropolymer, these components may be dissolved in a solvent such as fluorochlorohydrocarbon in advance and supplied to the mixer as a solution. The mixture thus prepared may be molded using a molding machine such as pressing, rolling, extrusion or a rubber injection molding machine.

[Action]

As described above, the structure of the lubricating rubber composition of the present invention has a strong affinity or reactivity with the organopolysiloxane having excellent lubricity or the functional group of the fluorine-containing polymer with the diene rubber and other coexisting additives. It will be firmly held as shown. When a liquid diene-based polymer is used together, the function of the functional group of the liquid diene-based polymer and the good compatibility with the diene-based rubber are added to form a homogeneous and complex and strong network structure. The above-mentioned lubricating substance incorporated in the above does not easily fall off, is finely and uniformly dispersed in the tissue, does not destroy the basic structure of the rubber elastic body, and has a mechanical strength,
It is possible to obtain a molded product that is stable in a state of a low friction coefficient for a long period of time while maintaining most of the heat resistance and has excellent wear resistance.

〔Example〕

The raw materials used in the following examples and comparative examples are collectively shown as follows. The abbreviations are shown in []. The mixing ratios of these raw materials are all expressed in parts by weight.

Diene rubber Acrylonitrile butadiene rubber [NBR] (Nippon Synthetic Rubber Co., Ltd .: JSR237H), styrene butadiene rubber [SBR] (Same company: JSR150)
2), Chloroprene rubber [CR] (Toyo Soda Kogyo Co., Ltd .: B-1
1), liquid diene polymer hydroxyl group-containing liquid diene polymer [HO-PB] (manufactured by Idemitsu Petrochemical Co., Ltd .: terminal hydroxyl group-containing polybutadiene R-45HT, molecular weight 2800, hydroxyl content 0.83 meq / g), functional group such as hydroxyl group Group-free liquid diene polymer [LNBR] (Nippon Synthetic Rubber Co., Ltd .: JSR N-280, acrylonitrile content 32%), organopolysiloxane, isocyanate group-containing organopolysiloxane [OCN-
SIL] (Shin-Etsu Chemical Co., Ltd. 5600 molecular weight silicone oil X22-160C 56g and 2,4-tolylene diisocyanate
Compounded with 3.5 g and stirred at room temperature for 1 hour to obtain silicone oil containing isocyanate groups at both ends), Organopolysiloxane containing epoxy groups [EP-SIL]
(Manufactured by the same company: epoxy-modified silicone oil KF102), carboxyl group-containing organopolysiloxane [HOOC-S
IL] (Same as above: Carboxyl-modified silicone oil X2
2-3701E), non-functional organopolysiloxane [SIL] (manufactured by the same company: Silicone oil KF96 3000), fluoropolymer, isocyanate group-containing polyfluoroether [OCN-FC
O] (Ikoku Montefruos Company: Fomblin Z DISOC-2000,
Molecular weight _{2000) OCN-C 6 H 3} (CH 3) -NHCOCF 2 C 2 F 4 O m CF 2 O n
CF ₂ CONH- (CH ₃ ) C ₆ H ₃ -NCO, isocyanate group-containing polyfluoroalkyl [OCN-F
C) Cyanate group-containing polyfluoroalkyl [NCO-FC] NCOCH ₂ (CF ₂ ) ₃ CH ₂ OCN, Epoxy group-containing polyfluoroalkyl [EP-FC] Amino group-containing polyfluoroalkyl [H ₂ N-FC] C ₆ F ₁₃ SCH ₂ CH ₂ OCO (CH ₂ ) ₅ NH ₂ Hydroxyl group-containing polyfluoroether [HO-FCO] (Fomblin Z DOL- 2000, molecular weight _{2000) HOCH 2 -CF 2 OC 2} F 4 O m CF 2 O n CF 2 -CH 2 OH, non-functional polyfluoroether [FCO] (Indonesian Montefluos Co.: Fomblin Z 25, molecular weight about 15,000 _{) CF 3 O-CF 2 OC} 2 F 4 O m CF 2 O n CF 3, the catalyst dibutyltin dilaurate [catalyst -1], n, n-dimethylbenzylamine [catalyst -2], various additives carbon powder [C -1] (Asahi Carbon Co., Ltd .: HAF), Carbon powder [C-2] (Same company: FEF), Carbon powder [C-3] (Same company: SEF), Magnesium oxide [MgO] (Kyowa Chemical) Kogyo Co., Ltd., Talc [Talc] (Nippon Taishi Seiren Co., Ltd.), Calcium Carbonate [Carbon Cal] (Shiraishi Kogyo Co., Ltd.), Light Carbonate Cal Cium [light carbon] (manufactured by the same company), sulfur [sulfur] (manufactured by Hosoi Chemical Co., Ltd.), zinc white [vulcanization aid-1] (manufactured by Mitsui Kinzoku Co., Ltd.), stearic acid [vulcanization aid-2] , N-cyclohexyl-2-benzothiazolylsulfenamide [vulcanization accelerator-1] (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), tetramethylthiuram disulfide [vulcanization accelerator-
2] (manufactured by the same company), dioctyl phthalate [DOP] (manufactured by Kurogane Kasei Co., Ltd.), wax-based antioxidant (aged-1) (manufactured by Ouchi Shinko Chemical Industry Co., Ltd .: Sunnock CW), 6-ethoxy-1. , 2-Dihydro-2,2,4-trimethylquinoline [Ohbo-2] (manufactured by the same company) Examples 1 to 8: Diene rubber and isocyanate group-containing organopolysiloxane or isocyanate group- or cyanate group-containing The fluoropolymer and the other various additives were blended in the proportions shown in Table 1 and in the proportions shown in Table 2, thoroughly mixed with an open roll, and heated at 170 ° C. for 5 minutes by pressing. 150mm long, 150mm wide, 2m thick
A plate-shaped rubber vulcanizate of m was obtained. About this molding JIS-K
In accordance with 6301, tensile rupture strength, tensile rupture elongation and hardness (JIS-A) are measured, and surface pressure 3kg / cm ² , speed 1m / min, mating material using thrust type friction wear tester The coefficient of friction was calculated when bearing steel (SUJ2) was used. The results of these measurements are summarized in Table 3.

Examples 9 to 17: Mold vulcanizates in the proportions shown in Tables 4 and 5 in the same manner as in the groups of Examples 1 to 8 except that a hydroxyl group-containing liquid diene polymer was used. did. Similar properties were measured for each of the obtained molded bodies, and the obtained results are summarized in Table 6.

Comparative Examples 1 to 16: Raw materials were blended in the proportions shown in Tables 7 to 10, and Comparative Examples 1 and 4 to 16 were the above-mentioned Example 1, and Comparative Example 2 was the Example 6. Further, for Comparative Example 3, the same operation as in Example 7 was performed to produce a vulcanized molded body. The same measurements as in Examples 1 to 17 were performed on the obtained molded bodies, and the results are summarized in Tables 11 and 12.

Tables 3 and 6 summarizing the results of Examples 1 to 8 and Examples 9 to 17 and Comparative Examples 1 to 8 and Comparative Examples 9 to 16
The following can be seen from Tables 11 and 12 that summarize the results of. That is, all of Examples 1 to 17 have a small friction coefficient, and especially Examples 9 to 17 in which the hydroxyl group-containing liquid diene polymer is used together have a lower friction coefficient.
This is apparent when comparing Examples 2 and 10, 3 and 11 and 4 and 12, respectively. Further, even if the organopolysiloxane or the fluorine-containing polymer is added as the lubricity-imparting agent at the same ratio, it is polyfluoroether that greatly contributes to the improvement of lubricity. Comparison with 3, 4 or 5 as well as examples 11 and 10
Or it is clear from the comparison with 13. Further, Examples 1 to
From the standpoint of mechanical strength, 17 shows a very high retention rate even though a lubricity-imparting agent such as an organopolysiloxane or a fluoropolymer is added. For example, Examples 1 to 5 and 8 in which a wetting agent is added to Comparative Example 1 which is an NBR type composition, and Examples 9 to 13, 16, and 17 in which a liquid diene polymer is further added are the same as the original comparison. It retains high mechanical strength compared to Example 1 and
Example 8 which was compounded in a large amount of 70 parts by weight had the lowest mechanical strength among these, but still had a high retention rate of 71% in tensile breaking strength, 85% in tensile breaking elongation and 94% in hardness. Is shown. In contrast, Comparative Examples 1 to 1 containing no organopolysiloxane or fluoropolymer
3. In the case of a functional group which is contained but is outside the limitation of the present invention,
That is, Comparative Examples 6, 7, 9, 10, 11, 14, 15 and 16
Has a high coefficient of friction. Further, even if the lubricity-imparting agent limited in the present invention is used, in Comparative Example 5 in which the addition amount exceeds 70 parts by weight and Comparative Example 13 in which the liquid diene polymer does not contain a hydroxyl group,
Even if the coefficient of friction is low, the mechanical strength is not satisfactory, and in Comparative Example 8 and Comparative Example 12 in which organopolysiloxane or a fluorine-containing polymer is used and a non-functional group is added. The friction coefficient was low, but the mechanical strength was also low and was unsatisfactory.

〔effect〕

As described above, the lubricating rubber composition of the present invention has excellent lubricity in addition to excellent sealing properties of the diene rubber elastic body, followability to deformation, vibration damping properties, sound deadening properties, and the like. Since it has both properties, stability and reliability against long-term sliding are extremely high.For example, automobiles, office equipment, information equipment, automatic control equipment, aerospace equipment, medical equipment, other electrical and electronic equipment, general It can be widely used as equipment and parts in all fields such as industrial machinery. Among them, paper feed rollers for copiers, toner seals, toner blends, sound deadening gears, kneading rollers in the food industry, packing for taps for cold and hot water, elevator guide shoes, dust boots for automobile joints, safety pads, grass run or wiper blades. Since it is a suitable material for various shock absorbers, various valves, oil seals, etc., it can be said that the significance of the present invention is extremely great.

Claims (2)

(57) [Claims] 1. An organopolysiloxane or a fluorine-containing polymer containing at least one of an isocyanate group and a cyanate group is mixed in an amount of 3 to 100 parts by weight with respect to 100 parts by weight of a diene rubber. Lubricating rubber composition. 2. A total amount of 100 parts by weight of a diene rubber, an organopolysiloxane containing at least one kind of an isocyanate group or a cyanate group or a fluoropolymer and a liquid diene polymer containing a hydroxyl group. 5. A lubricating rubber composition, characterized in that 5 to 100 parts by weight are compounded.