JPH0525237A - Sliding member and staining-resistant member - Google Patents

Abstract

PURPOSE:To obtain a sliding member and a staining-resistant member low in molding shrinkage and excellent in impact resistance, staining resistance and slidability. CONSTITUTION:A sliding member and a staining-resistant member each comprising a polyorganosiloxane thermoplastic resin which is prepared by polymerizing 95-20 pts.wt. at least one vinyl monomer (I) with 5-80 pts.wt. modified polyorganosiloxane (II) obtained by condensing 90-99.8wt.% organosiloxane with 10-0.2wt.% graft-crosslinking agent having both an unsaturated group and an alkoxysilyl group [(I)+(I)=100 pts.wt.], having a grafting ratio of 10wt.% or above and in which the average particle diameter of the dispersed particles of the modified polyorganosiloxane (II) onto which vinyl monomer (I) is grafted is 5000Angstrom or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member and a stain resistant member which have a small molding shrinkage and are excellent in impact resistance, molding workability, stain resistance and slidability.

[0002]

2. Description of the Related Art Polyoxymethylene, nylon 6, nylon 6,6, etc. have been known as materials for sliding members such as gears and bearings. Although these materials have excellent slidability, the molding shrinkage during molding is large, and thus the dimensional stability is poor, and a large or thick molded product is subject to distortion and deformation. Therefore, this is a major obstacle when these materials are used as molding materials for molded products for applications in which dimensional accuracy is required, large-sized applications or applications in which wall thickness is required. On the other hand, nylon 4,6, polyvinylidene fluoride and the like are known as molding materials for stain resistant members such as wash basins and kitchen appliances. These materials have excellent stain resistance, but have a large molding shrinkage during molding, and have the same troubles as the above sliding members.

[0003]

The present invention has been made in view of the above-mentioned problems of the prior art, and has a small molding shrinkage and is excellent in impact resistance, molding workability, stain resistance, and slidability. An object of the present invention is to provide a sliding member and a stain resistant member.

[0004]

The present invention provides a general formula R ¹ _n
An organosiloxane having a structural unit represented by SiO _{(4-n) / 2} (wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, and n is an integer of 0 to 3) ( I) 90-
99.8% by weight and

[Chemical 2] (In the formula, R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) A graft crossing agent (II) having an unsaturated group and an alkoxysilyl group in an amount of 10 to 0.2% by weight
And 5 to 80 parts by weight of the modified polyorganosiloxane (III) obtained by condensing with at least one vinyl monomer (IV) 95 to 20 parts by weight (provided that (III) + (I
V) = 100 parts by weight], the graft ratio is 10% by weight or more, and the average particle size of the dispersed particles of the modified polyorganosiloxane (III) grafted with the vinyl monomer (IV) is 5 It is intended to provide a sliding member and a stain resistant member made of a polyorganosiloxane-based thermoplastic resin having a weight of 1,000 Å or less.

The organosiloxane (I) used in the present invention has a structural unit represented by the above general formula and has a linear, branched or cyclic structure, preferably a cyclic structure. It is an organosiloxane.
Examples of the substituted or unsubstituted monovalent hydrocarbon group possessed by the organosiloxane (I) include a methyl group, an ethyl group, a propyl group, a vinyl group, a phenyl group, and a substituted one thereof with a halogen atom or a cyano group. A hydrocarbon group etc. can be mentioned. Further, in the average composition formula, the value of n is an integer of 0 to 3. Specific examples of the organosiloxane (I) include cyclic compounds such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and trimethyltriphenylcyclotrisiloxane, and A chain or branched organosiloxane can be mentioned.

The organosiloxane (I) is
It may be a polyorganosiloxane that has been condensed in advance and has a polystyrene-equivalent weight average molecule of about 500 to 10,000. When the organosiloxane (I) is a polyorganosiloxane, its molecular chain end is blocked with, for example, a hydroxyl group, an alkoxy group, a trimethylsilyl group, a dimethylvinylsilyl group, a methylphenylvinylsilyl group or a methyldiphenylsilyl group. May be.

Next, the graft crossing agent (II) used in the present invention is a compound having both an unsaturated group represented by the above general formula and an alkoxysilyl group. R in the general formula
² is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and more preferably a hydrogen atom or a methyl group. Specific examples of these compounds include p-vinylphenylmethyldimethoxysilane, 1- (m-vinylphenyl) methyldimethylisopropoxysilane, and 2-
(P-Vinylphenyl) ethylenemethyldimethoxysilane, 3- (p-vinylphenoxy) propylmethyldiethoxysilane, 3- (p-vinylbenzoyloxy) propylmethyldimethoxysilane, 1- (o-vinylphenyl) -1 , 1,2-Trimethyl-2,2-dimethoxydisilane, 1- (p-vinylphenyl) -1,1-diphenyl-3-ethyl-3,3-diethoxydisiloxane,
m-vinylphenyl- [3- (triethoxysilyl) propyl] diphenylsilane, [3- (p-isopropenylbenzoylamino) propyl] phenyldipropoxysilane, 2- (m-vinylphenyl) ethylmethyldimethoxysilane, 2 -(O-Vinylphenyl) ethylmethyldimethoxysilane, 1- (p-vinylphenyl) ethylmethyldimethoxysilane, 1- (m-vinylphenyl) ethylmethyldimethoxysilane, 1- (o-vinylphenyl) ethylmethyldimethoxysilane Besides,
Mention may be made of mixtures thereof.

The graft crossing agent (II) is preferably p-vinylphenylmethyldimethoxysilane, 2-
(P-Vinylphenyl) ethylmethyldimethoxysilane and 3- (p-vinylbenzoyloxy) propylmethyldimethoxysilane, and more preferably p-vinylphenylmethyldimethoxysilane. The proportion of the graft crossing agent used is 0.2 to 10% by weight, preferably 0.5 to 5% by weight, based on the total amount of the components (I) and (II).
When the amount is less than 0.2% by weight, a high graft ratio cannot be obtained in the graft polymerization of the obtained modified polyorganosiloxane (III) and the vinyl monomer (IV), and as a result, the modified polyorganosiloxane (III) The interfacial adhesion between the grafted vinyl polymers is reduced, and delamination occurs, resulting in insufficient impact strength of the polyorganosiloxane-based thermoplastic resin obtained. On the other hand, when the proportion of the graft crossing agent (II) exceeds 10% by weight, the graft ratio increases, but the polymerization of the grafted vinyl polymer decreases with the increase of the graft crossing agent (II), and the vinyl polymer It has a molecular weight, and as a result, sufficient impact strength cannot be obtained.

The modified polyorganosiloxane (III) is condensed by shear-mixing the organosiloxane (I) and the graft crossing agent (II) with a homomixer in the presence of an emulsifier such as alkylbenzene sulfonic acid. Can be manufactured. This emulsifier acts as an emulsifier for the organosiloxane (I) and also serves as a condensation initiator. The amount of this emulsifier used is (I)
Usually, it is 0.1 with respect to the total amount of the components
Is about 5 to 5% by weight, preferably about 0.3 to 3% by weight.
The amount of water used at this time is (I) component and (II)
It is usually 100 to 500 parts by weight, preferably 200 to 400 parts by weight, relative to 100 parts by weight of the component. The condensation temperature is usually 5 to 100 ° C.

The modified polyorganosiloxane (III)
A cross-linking agent may be added as a third component in the production of the above in order to improve the impact resistance of the obtained resin. Examples of the cross-linking agent include methyltrimethoxysilane,
Examples thereof include trifunctional crosslinking agents such as phenyltrimethoxysilane and ethyltriethoxysilane, and tetrafunctional crosslinking agents such as tetraethoxysilane. The amount of the crosslinking agent added is usually 10% by weight or less, preferably 5% by weight or less, based on the total amount of the organosiloxane (I) and the graft crossing agent (II). The polystyrene-converted weight average molecular weight of the modified polyorganosiloxane (III) thus obtained is usually 30,000 to
1,000,000, preferably 50,000-30
It is about 10,000.

Next, the modified polyorganosiloxane (III) thus obtained is graft-polymerized with a vinyl-based monomer (IV) to obtain a graft copolymer [containing a non-grafted (co) polymer]. ] It is possible to obtain a polyorganosiloxane-based thermoplastic resin. In addition,
The polyorganosiloxane-based thermoplastic resin defined in the present invention means a graft-type graft copolymer obtained by graft-polymerizing a vinyl-type monomer (IV) in the presence of a modified polyorganosiloxane (III), It may be a mixture of the graft copolymer and the (co) polymer of the component (IV).

The vinyl-based monomer (I
V) is, for example, styrene, p-methylstyrene,
Aromatic vinyl compounds such as monobromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, α-methylstyrene and sodium styrenesulfonate; methacrylic acid such as methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, butyl methacrylate and allyl methacrylate. Ester compounds; Acrylic ester compounds such as methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl methacrylate and dimethylaminoethyl methacrylate; Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; Olefin such as ethylene and propylene; Butadiene, isoprene, chloroprene Conjugated diolefins such as; maleimide, N-methylmaleimide, N-ethyl Maleimides such as reimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide, tribromophenylmaleimide, N- (p-chlorophenyl) maleimide Examples thereof include compounds; acid anhydrides such as maleic anhydride; and vinyl acetate, vinyl chloride, vinylidene chloride, triallyl isocyanurate, acrylic acid and methacrylic acid, which may be used alone or in a mixture.

Of these vinyl monomers (IV),
Preferred are aromatic vinyl compounds, (meth) acrylic acid ester compounds, vinyl cyanide compounds, maleimide compounds and acid anhydrides. Among them, the aromatic vinyl compound is preferably styrene, α-methylstyrene, p-methylstyrene, the (meth) acrylic acid ester compound is preferably methyl methacrylate, and the vinyl cyanide compound is preferably Acrylonitrile and methacrylonitrile are preferable, and maleimide compounds are preferably maleimide, N-phenylmaleimide, N-cyclohexylmaleimide and tribromophenylmaleimide, and acid anhydride is preferably maleic anhydride. . When the vinyl monomer (IV) contains a cyan vinyl compound, the content of the vinyl cyanide compound is preferably 50% by weight or less.

The composition for charging the vinyl monomer (IV) onto the modified polyorganosiloxane (III) is 5 to 80 parts by weight, preferably 10 to 60 parts by weight, as the component (III).
Parts by weight, more preferably 10 to 40 parts by weight, component (IV) is 95 to 20 parts by weight, preferably 90 to 40 parts by weight,
More preferably 90 to 60 parts by weight [however, (III) +
(IV) = 100 parts by weight], and if the amount of the component (III) is less than 5 parts by weight, sufficient slidability, stain resistance and impact resistance cannot be obtained, while the amount of the component (III) exceeds 80 parts by weight. And the molding shrinkage at the time of molding becomes large, and the moldability decreases.

The graft ratio of the polyorganosiloxane thermoplastic resin of the present invention thus obtained is about 10% by weight or more, preferably about 20% by weight or more, more preferably about 30% by weight or more. If the graft ratio of the polyorganosiloxane-based thermoplastic resin is less than 10% by weight, the molding shrinkage of the resin at the time of molding becomes large, and further the appearance is poor and the impact strength is lowered. This graft ratio can be adjusted by appropriately selecting the amount and type of the polymerization initiator, the polymerization temperature, the polymerization method and the like.

The modified polyorganosiloxane (III) in which the vinyl monomer (IV) in the thermoplastic polyorganosiloxane resin used in the present invention is grafted.
The average particle diameter of the dispersed particles is less than 5,000Å, preferably less than 4,000Å, more preferably less than 3,000Å
It is the following. If the average particle size exceeds 5,000 Å, slidability and stain resistance are insufficient, and molding shrinkage during molding increases, which is not preferable. This average particle diameter can be adjusted by selecting the particle diameter of the modified polyorganosiloxane (III) to be used. The particle size of the modified polyorganosiloxane (III) used is
It can be adjusted by selecting the stirring conditions during the production of the component (III).

In producing the polyorganosiloxane-based thermoplastic resin used in the present invention, for example, modified polyorganosiloxane (III) and vinyl-based monomer (IV) are used.
Is graft-polymerized by ordinary radical polymerization to obtain a composition containing a graft copolymer. here,
Depending on the type of radical polymerization initiator, it is necessary to neutralize the latex of the modified polyorganosiloxane (III), which has been acidified by the alkylbenzene sulfonic acid as described above, with an alkali. Examples of the alkali include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, triethanolamine, triethylamine and the like. Further, as the radical polymerization initiator, for example, cumene hydroperoxide,
Oxidizing agent consisting of organic hydroperoxides such as diisopropylbenzene hydroperoxide and paramenthane hydroperoxide, and sugar-containing iron pyrophosphate formulation, sulfoxylate formulation, sugar-containing iron pyrophosphate formulation / sulfoxylate formulation mixed formulation Redox initiators in combination with reducing agents such as; persulfates such as potassium persulfate and ammonium persulfate; azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 2-carbamoylaza Examples thereof include azo compounds such as isobutyronitrile; organic peroxides such as benzoyl peroxide and lauroyl peroxide, and the above redox initiators are preferable. The amount of these radical polymerization initiators used is usually 0.05 per 100 parts by weight of the vinyl-based monomer (IV) used.
-5 parts by weight, preferably 0.1-3 parts by weight.

The radical polymerization method at this time is preferably carried out by emulsion polymerization or solution polymerization.
In the emulsion polymerization, known emulsifiers, the above radical initiators, chain transfer agents and the like are used. Here, as the emulsifier, anionic emulsifiers such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium diphenyl ether disulfonate, sodium succinate dialkali ester sulfonate, or polyoxyethylene alkyl ester, polyoxyethylene alkyl allyl ether, etc. One or two of the nonionic emulsifiers
There may be more than one species. The amount of the emulsifier used is usually 0.5 to 5% by weight based on the vinyl monomer (IV).
It is a degree. Examples of the chain transfer agent include mercaptans such as t-dodecyl mercaptan, octyl mercaptan, n-tetradecyl mercaptan, and n-hexyl mercaptan; halogen compounds such as carbon tetrachloride and ethylene bromide with respect to the vinyl monomer (IV). Usually 0.02
~ 1 wt% is used. In emulsion polymerization, in addition to a radical polymerization initiator, an emulsifier, a chain transfer agent, etc., various electrolytes, a pH adjusting agent, etc. may be used together, if necessary, with respect to 100 parts by weight of the vinyl-based monomer (IV). , Water 1
0 to 500 parts by weight and the radical polymerization initiator, the emulsifier, the chain transfer agent, etc. are used in an amount within the above range, the polymerization temperature is 5 to 100 ° C., preferably 50 to 90 ° C., the polymerization time is 0.1 to 10 The emulsion is polymerized under the condition of time. In the case of emulsion polymerization, a latex containing a modified organopolysiloxane (III) obtained by condensation of an organosiloxane (I) and a graft crossing agent (II) is added to a vinyl monomer (IV) and a radical initiator. Can also be implemented by adding.

On the other hand, in the case of solution polymerization, the modified polyorganosiloxane (III) and the vinyl monomer (IV) are
It is dissolved in an organic solvent, and a radical initiator, a chain transfer agent if necessary, and various additives are added to this to carry out radical polymerization. Organic solvents used in this solution polymerization include toluene, n-hexane, cyclohexane, chloroform,
Tetrahydrofuran etc. are mentioned. In solution polymerization, a radical polymerization initiator and, if necessary, a chain transfer agent are used in combination, and usually 80 to 500 parts by weight of an organic solvent is added to 100 parts by weight of the vinyl-based monomer (IV) and the radical. Polymerization initiator, chain transfer agent, etc. are used in an amount within the above range, and the polymerization temperature is 5 to 150 ° C., preferably 50 to 1
Solution polymerization is carried out under the conditions of 30 ° C. and polymerization time of 1 to 10 hours. In the case of this solution polymerization, impurities can be significantly reduced as compared with the case of emulsion polymerization. When the polyorganosiloxane-based thermoplastic resin of the present invention is produced by emulsion polymerization, the polyorganosiloxane-based thermoplastic resin is purified by coagulating by a usual salt coagulation method, washing the obtained powder with water, and then drying. In the case of solution polymerization, the unreacted monomer and solvent are distilled off by steam distillation, and the obtained resin mass is finely crushed and dried for purification.

The polyorganosiloxane thermoplastic resin obtained by these methods can be pelletized by a kneader such as an extruder. At this time, other known polymers are usually added in an amount of 99% by weight or less depending on the required performance.
Preferably, about 90% by weight or less may be appropriately blended and used. Examples of such polymers include polybutadiene, butadiene-styrene copolymer, acrylonitrile-butadiene copolymer, polyisoprene, diene rubber such as natural rubber; acrylic rubber, ethylene-propylene copolymer, ethylene-propylene- Diene copolymer,
Olefin rubber such as chlorinated butyl rubber and chlorinated polyethylene; aromatic vinyl-conjugated diene such as styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene-styrene radial tereblock copolymer System block copolymer; hydride of the block copolymer; polypropylene,
Polyethylene, polystyrene, styrene-acrylonitrile copolymer, rubber-reinforced polystyrene (HIPS), acrylonitrile-butadiene-styrene resin (ABS resin), acrylonitrile-ethylene propylene-styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin ( MBS resin), acrylonitrile-
Butadiene-methyl methacrylate-styrene resin, acrylonitrile-n-butyl acrylate-styrene resin (AAS resin), polyvinyl chloride, polycarbonate,
Polyethylene terephthalate, polybutyl terephthalate, polyacetal, polyamide, epoxy resin, polyvinylidene fluoride, polysulfone, ethylene-vinyl acetate copolymer, PPS resin, polyether ether ketone, PPO resin, styrene-methyl methacrylate copolymer, styrene- Maleic anhydride copolymer, rubber modified PP
Examples include O resins, styrene-maleimide copolymers, rubber-modified styrene-maleimide copolymers, polyamide elastomers and polyester elastomers.

If necessary, a slidability-imparting agent may be added to the polyorganosiloxane-based thermoplastic resin of the present invention. Examples of the slidability-imparting agent are polyfluorinated ethylene such as polytetrafluoroethylene; molybdenum sulfide such as molybdenum disulfide; nylon 6, nylon 6,6, nylon 4,6 and the like; polyoxymethylene, wollastonite , Potassium titanate, mica, carbon fiber, silicon carbide whiskers and the like. The compounding amount for enhancing the effect of adding these slidability-imparting agents is 0.5 to 40 parts by weight with respect to 100 parts by weight of the polyorganosiloxane-based thermoplastic resin.
Furthermore, in the polyorganosiloxane-based thermoplastic resin of the present invention, glass fiber, metal fiber, filler,
Pigments, flame retardants, stabilizers, antistatic agents and the like can be added. The compounding method of the polyorganosiloxane-based thermoplastic resin of the present invention is not particularly limited, but for example, it is mixed by a Henschel mixer, a tumbler, etc., and further mixed by a batch kneader, a Banbury mixer, a single screw or two.
Examples thereof include a method of melt mixing with an axial screw extruder.

The present invention is a sliding member and a stain resistant member made of the above polyorganosiloxane thermoplastic resin. Here, the sliding member made of the thermoplastic resin of the present invention is a molded product used for applications requiring slidability, and this molded product also includes film and sheet-shaped products. As the sliding member, for example, in the automotive field, a sliding bearing for steering, a sliding bearing for a shift lever,
Sliding bearings for pedals (accelerators, clutches, brakes), sliding bearings for seat belt winding parts, various switches, various motor internal gears, window regulators,
Door lock inner slide bearings, seat belt buckles, etc. are mentioned. In the field of OA equipment, PPC inner slide bearings, P
PC internal gear, laser printer internal gear, dot printer internal gear, dot printer paper feed roller, dot printer head carriage sliding bearing, facsimile sliding bearing, facsimile gear, other gear applications,
Key applications include keyboards such as key tops, stems, frames, stem-integrated key tops, etc. In the AV equipment field, various audio equipment (VTR, tuner, player, DAT, etc.) gears, rollers, switches, etc. can be mentioned. In the electrical equipment field, gears and sliding bearings for home appliances (air conditioners, hair clippers, washing machines, vacuum cleaners, fans, etc.) are mentioned, and in the general industrial field, various gears (clocks, cameras, toys, etc.), bearing holding Examples include seals for vessels, bearings, sliding bearings for various pumps, sliding bearings for various industrial machines, curtain rail rings and blind gears. Conventionally, in the keyboard field,
The key top is made of ABS resin due to problems such as printability and appearance, and the stem is made of P due to slidability with ABS resin.
OM has been used, and ABS resin has been used for the frame material due to problems of dimensional accuracy and weld strength. However, with the miniaturization of computers, thin keyboards have been preferred, and a design in which a key top and a stem are integrated has come to be desired.

There are two methods to solve this problem. One is to design a stem-integrated key top that is excellent in slidability, printability, and appearance, and the other is to design a stem-integrated key top. Is an ABS resin, and the frame material is a material having good dimensional accuracy, weld strength, and slidability. This suggests that the material of the present invention, which has improved slidability without impairing the characteristics of the ABS resin, is optimal. In addition, the conventional resin gear has a problem of squeaking noise generated during driving, and in recent years, there is a demand for development of a resin gear that does not produce noise due to the trend toward higher quality. Although the mechanism of sound generation has not been clarified yet, it is clear that the material of the present invention is suitable for this application because of its good drivability and no sound generation. Further, the stain resistant member made of the thermoplastic resin of the present invention is a molded product used for applications requiring stain resistance, and the molded product also includes a film and a sheet. Examples of the stain resistant member include a washbasin unit, a kitchen appliance, a panel, a housing, and a conveyor belt. As the molding method of the above sliding member and contamination resistant member, there are injection molding method, compression molding method, transfer molding method, extrusion molding method, hollow molding method, roll processing method,
A vacuum forming method, a powder forming method, an insert forming method, an outsert forming method and the like can be mentioned.

[0024]

EXAMPLES The present invention will be described more specifically below with reference to examples. The parts and% in the examples are parts by weight and% by weight, unless otherwise specified. In the examples,
Various measurement items were as follows. Graft ratio A constant weight (x) of the graft polymerization product was put into acetone and shaken for 2 hours with a shaker to dissolve the free copolymer, and a centrifuge was used to rotate at 23,000 rpm.
Centrifuge for 30 minutes to obtain insoluble matter. Next, it was dried at 120 ° C. for 1 hour using a vacuum dryer, and the insoluble matter weight (y)
Then, the graft ratio and graft efficiency were calculated by the following equations. Graft ratio (%) = {[y / (x × fraction of component (III) in graft polymerization product] × 100)

Average particle size The average particle size of the dispersed particles was confirmed by an electron microscope to find that the particle size of the latex synthesized in advance in the emulsified state directly represents the particle size of the dispersed particles in the resin. The particle size of was measured by a light scattering method. As the measuring instrument, LPA-3100 manufactured by Otsuka Electronics Co., Ltd. is used,
The particle size was calculated using the cumulant method by integrating 70 times. Izod impact strength Measured by ASTM D256 under 1/4 ", 23 ° C, test condition with notch. Unit is kgcm / cm. Dynamic friction coefficient Using Suzuki sliding tester, mating material Steel (S45C) was used as the test piece.The test piece used was a hollow cylindrical shape having an outer diameter of 25.6 mm and an inner diameter of 20.0 mm, and the mating material had the same shape. Is a load of 5 kg and a running speed of 5 in an atmosphere of room temperature of 23 ° C and humidity of 50%.
It was measured at 0 cm / sec. The dynamic friction coefficient is calculated by the following formula. μ = [3 × F × (r ₂ ² −r ₁ ² )] / [P × (r ₂ ³ −r ₁ ³ )] (where μ is the dynamic friction coefficient, F is the force applied to the load cell,
P is the load, R is the arm length to the load cell, r ₁ is the inner diameter, and r ₂ is the outer diameter. ) Contamination resistance Write characters on the resin plate with oil-based magic ink, wipe it off with a wipe, and judge whether the magic ink can be removed or not. ○: Can be taken. ×: It cannot be removed.

Reference Example 1 (Modified polyorganosiloxane R
Production of -1 to 3) 1.5 parts of p-vinylphenylmethyldimethoxysilane and 98.5 parts of octamethylcyclotetrasiloxane were mixed, and this was added to 300 parts of distilled water in which 2.0 parts of dodecylbenzenesulfonic acid was dissolved. , And the mixture was stirred for 3 minutes with a homomixer to emulsify and disperse. This mixed solution was transferred to a separable flask equipped with a condenser, a nitrogen inlet and a stirrer, and heated with stirring at 90 ° C. for 6 hours and cooled at 5 ° C. for 24 hours to complete the condensation. The condensation ratio of octamethylcyclotetrasiloxane in the obtained modified polyorganosiloxane (III) was 92.
It was 8%. Similarly, modified preorganization conditions were changed to obtain modified polyorganosiloxanes having different average particle diameters. The results are shown in Table 1.

[0027]

[Table 1]

Reference Example 2 (Production of Thermoplastic Resins A-1 to 5) In a glass flask having an internal volume of 7 liter and equipped with a stirrer, 100 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate and hydroxylation were added. 0.01 parts potassium, t
-0.1 parts of dodecyl mercaptan and the proportions shown in Table 2 were added to the modified polyorganosiloxane latex of Reference Example 1 and a batch polymerization component consisting of various vinyl monomers, and the temperature was raised with stirring. When the temperature reached 45 ° C, 0.1 part of sodium ethylenediaminetetraacetate, 0.003 part of ferrous sulfate, 0.2 part of formaldehyde sodium sulfoxylate dihydrate and 15 parts of ion-exchanged water
10 parts of an activator aqueous solution and 0.1 part of diisopropylbenzene hydroperoxide were added and the reaction was continued for 1 hour.

Thereafter, 50 parts of ion-exchanged water, 1 part of sodium dodecylbenzenesulfonate, and potassium hydroxide of 0.
02 parts, 0.1 parts of t-dodecyl mercaptan, 0.2 parts of diisopropylbenzene hydroperoxide and an increment polymerization component consisting of various vinyl monomers in the proportions shown in Table 2 were continuously added over 3 hours, The reaction continued. After the addition was completed, the reaction was continued for 1 hour with further stirring, and then 2,2-methylene-bis-
0.2 part of (4-ethylene-6-t-butylphenol) was added, and the reaction product was taken out from the flask. Then, the product is coagulated with 2 parts of potassium chloride, dehydrated, washed with water, and dried to obtain powdery thermoplastic resin A-1.
~ 5 were collected. Table 2 shows the polymerization conversion rate and the graft rate.

[0030]

[Table 2]

Examples 1 to 5 and Comparative Examples 1 to 4 The components shown in Tables 3 to 4 were melt-kneaded at a temperature of 230 ° C. with an extruder having an inner diameter of 40 mm to prepare pellets. These pellets are injected into a 5 oz injection molding machine [manufactured by Toshiba Corporation, IS-
80A] was molded at a molding temperature of 230 ° C. to prepare a test piece, and its physical properties were evaluated. The results are shown in Tables 3-4. The AS resin used is JSR manufactured by Japan Synthetic Rubber Co., Ltd.
AS230, ABS resin manufactured by the same company, JSR
This is ABS # 12.

[0032]

[Table 3]

[0033]

[Table 4]

Examples 6 to 7 and Comparative Example 5 (Feeling test after keystroke durability test) Obtained in Example 1 for the key top material or frame material of the keyboard switch having the stem-integrated key top shown in FIG. Using the obtained pellets or ABS resin [ABS15, manufactured by Nippon Synthetic Rubber Co., Ltd.], a feeling test after a keying durability test was performed. Here, the feeling test after the keystroke durability test was measured as follows. The results are shown in Table 5.

Feeling Test after Keystroke Durability Test For a keyboard switch having a stem-integrated keytop as shown in FIG. 1, a feeling test after 3 million times of keystrokes was performed by MOD manufactured by Aiko Engineering Co., Ltd.
Performed using EL-1305D. Maximum pressing force change rate; Maximum pressing force change rate = [(P ₀ −P ₃₀₀ ) / P ₀ ] × 1
00 (%) (In the formula, P ₀ represents the maximum pressing force before the durability test, and P ₃₀₀ represents the maximum pressing force after the durability test.) Change rate of click rate; Change rate of click rate = K ₀ −K ₃₀₀ (%) [In the formula, K ₀ represents the click rate before the durability test, and K ₃₀₀ represents the click rate after the durability test. Here, when the maximum pressing force is P and the minimum pressing force is B, the click rate is [(P−B)
/ P] × 100 (%). Hook rate; Hook rate = H (%) (In the formula, H represents the number of times the stem was hooked when the key top was pressed 100 times after the durability test.)

[0036]

[Table 5]

The feeling test after the keystroke durability test is an index for judging whether or not the material can be actually used for a keyboard. As is clear from Table 5, Example 1
No.2 pellets were used for keyboards, regardless of whether they were used as a keyboard-integrated key top material or a frame material for the maximum pressing force change rate, click rate change rate, and catch rate. In this case, the feeling is the same as when it was designed, and no defects such as the key not returning do not occur, and it can be seen that it is a useful material.

Examples 8 to 10 and Comparative Examples 6 to 7 (Evaluation of Squeaking Characteristics of Resin Gear) Pellets obtained in Example 1 and A used in Example 6
BS resin or POM [Polyplastics Co., Ltd.
Manufactured by DURACON M90-44], and a JIS3 class gear having the shape shown in Table 6 is molded, and the noise level (150 rpm, 400 g.
cm) and the sound pressure at 10,000 Hz was measured. The results are shown in Table 7.

[0039]

[Table 6]

[0040]

[Table 7]

In recent years, it has been required to eliminate an unpleasant squeak noise when using a resin gear. The evaluation of the squeaking sound characteristic of the resin gear is an index showing this required characteristic. As is clear from Table 7, in the gears using the pellets of Example 1 (Examples 8 to 10), it is possible to reduce the noise level simply by using one of the gears regardless of the mating material. . In addition, the frequency of unpleasant sounds such as keys is actually 10,000 Hz
In all of Examples 8 to 10, the sound pressure is 0, and it can be seen that it can be used as a resin gear that does not generate any unpleasant squeak noise.

[0042]

The sliding member and stain resistant member of the present invention are
It has little molding shrinkage and is excellent in impact resistance, stain resistance, and slidability. As described above, a sliding member and a stain resistant member having a small molding shrinkage and a sliding property have never existed before. As described above, the sliding member and the stain resistant member of the present invention have excellent performance, and their industrial significance is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a keyboard switch having a stem-integrated key top.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Kamiya             2-11-21 Tsukiji, Chuo-ku, Tokyo, Japan             Naru Rubber Co., Ltd.

Claims (2)

[Claims] 1. The general formula R ¹ _n SiO _{(4-n) / 2} (wherein R
¹ is a substituted or unsubstituted monovalent hydrocarbon group, and n is an integer of 0 to 3), and 90 to 99.8 wt% of the organosiloxane (I) having a structural unit represented by Chemical Formula 1 [Chemical 1] (In the formula, R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) A graft crossing agent (II) having an unsaturated group and an alkoxysilyl group in an amount of 10 to 0.2% by weight.
And 5 to 80 parts by weight of the modified polyorganosiloxane (III) obtained by condensing with at least one vinyl monomer (IV) 95 to 20 parts by weight (provided that (III) + (I
V) = 100 parts by weight], the graft ratio is 10% by weight or more, and the average particle size of the dispersed particles of the modified polyorganosiloxane (III) grafted with the vinyl monomer (IV) is 5 A sliding member made of a polyorganosiloxane-based thermoplastic resin having a weight of 2,000Å or less. 2. A stain resistant member comprising the polyorganosiloxane thermoplastic resin according to claim 1.