WO2017073194A1

WO2017073194A1 - Antivibration rubber composition and antivibration rubber

Info

Publication number: WO2017073194A1
Application number: PCT/JP2016/077131
Authority: WO
Inventors: 渡辺　健太郎; 武司福住
Original assignee: 日信化学工業株式会社
Priority date: 2015-10-27
Filing date: 2016-09-14
Publication date: 2017-05-04
Also published as: JP6525062B2; JPWO2017073194A1; CN108350233A

Abstract

Provided are an antivibration rubber composition in which it is possible to reduce the friction coefficient of the antivibration rubber surface, and antivibration rubber in which the same is used. An antivibration rubber composition characterized by containing (I) 100 parts by mass of a rubber component, and (II) 1-30 parts by mass of a silicone-acrylic graft copolymer resin that is a polymer of a mixture including 50-99 parts by mass of a polyorganosiloxane indicated by general formula (1) and 1-50 parts by mass of acrylic acid ester monomers or methacrylic acid ester monomers. (R¹ is a monovalent hydrocarbon group; R² is a mercapto group, acryloxy-group- or methacryloxy-group-substituted alkyl group, or vinyl group; X is a monovalent hydrocarbon group, alkoxy group, or hydroxyl group; Y is X or -[O-Si(X)₂]_d-X; and two or more among X and Y are hydroxyl groups. Z is an alkyl group, alkoxy group, or hydroxyl group. a is 0-1000, b is 100-10,000, c is 1-10, and d is 1-1000.)

Description

Anti-vibration rubber composition and anti-vibration rubber

The present invention relates to an anti-vibration rubber composition that provides an anti-vibration rubber capable of suppressing abnormal noise generated in an anti-vibration rubber product used in vehicles such as automobiles, and an anti-vibration rubber using the same. More specifically, the present invention relates to an anti-vibration rubber composition and an anti-vibration rubber that are suitable for applications such as an automobile stabilizer bush and a rear suspension bush.

For anti-vibration rubber for automobiles, for example, anti-vibration rubber that is used by inserting metal parts such as stabilizer bushes and rear suspension bushes, contact between the mounting bracket and the surface of the rubber bush when starting, sudden braking, and turning left and right Abnormal noise occurs in the area, and countermeasures are required.

As a countermeasure against this, various studies for reducing the friction coefficient of the rubber surface have been studied. For example, a method of sticking a Teflon (registered trademark) sheet having a low friction coefficient on the contact surface of rubber, a method of adding wax to the rubber component, and a method of adding liquid silicone oil have been proposed (Patent Documents 1 and 2: International Publication No. 2011/021641, JP-A-10-245451).
However, the method of sticking the Teflon sheet is expensive in terms of materials and processes, and the method of adding wax is insufficient in reducing the friction coefficient. In addition, the method of adding silicone oil has an excellent effect in reducing the friction coefficient, but has a problem that the compatibility with the rubber component is poor, the kneading processability is extremely inferior, and mass production is difficult. ing.

In addition, Patent Document 2 discloses acrylic silicone oil, but a change with time due to bleeding on the coating surface occurred, and it was not possible to maintain the use for a long time.

International Publication No. 2011/021641 JP-A-10-245451

The present invention has been made in view of the above circumstances, and an object thereof is to provide an anti-vibration rubber composition that provides an anti-vibration rubber capable of reducing the friction coefficient of the surface, and an anti-vibration rubber using the same. .

As a result of intensive studies to achieve the above object, the present inventors have found that the specific silicone acrylic graft copolymer resin has good compatibility with the rubber, does not excessively bleed on the rubber surface, and is moderate. The anti-vibration rubber comprising a cured product of the anti-vibration rubber composition containing the silicone acrylic graft copolymer resin in the rubber component is known to have a function as a self-lubricant component. The present inventors have found that the friction reducing effect is maintained when used for a part, and have completed the present invention.

Accordingly, the present invention provides the following anti-vibration rubber composition and anti-vibration rubber.
[1]
(I) Rubber component: 100 parts by mass,
(II) Silicone acrylic, which is a polymer of a mixture containing 50 to 99 parts by mass of polyorganosiloxane represented by the following general formula (1) and 50 to 1 parts by mass of an acrylate monomer or methacrylic acid ester monomer Graft copolymer resin: An anti-vibration rubber composition comprising 1 to 30 parts by mass.

Wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ² is an alkyl group having 1 to 6 carbon atoms substituted with a mercapto group, an acryloxy group or a methacryloxy group. X is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, alkoxy group or hydroxyl group having 1 to 20 carbon atoms, Y is X or — [O —Si (X) ₂ ] _d —X is the same or different group, and at least two of X and Y are hydroxyl groups, Z is an alkyl group having 1 to 4 carbon atoms, and 1 to 4 carbon atoms. A is a positive number from 0 to 1,000, b is a positive number from 100 to 10,000, c is a positive number from 1 to 10, and d is a positive number from 1 to 1,000. .)
[2]
(II) silicone acrylic graft copolymer resin,
(I) 100 parts by mass of the polyorganosiloxane represented by the general formula (1),
(Ii) The anti-vibration rubber composition according to [1], which is an emulsion graft polymer of a mixture of 1 to 100 parts by mass of an acrylate monomer or a methacrylic acid ester monomer.
[3]
The anti-vibration rubber composition according to [2], which is an emulsion graft polymer of a mixture of 100 parts by weight of component (i) and 10 to 100 parts by weight of component (ii).
[4]
(II) silicone acrylic graft copolymer resin,
(I) 100 parts by mass of the polyorganosiloxane represented by the general formula (1),
(Ii) 1 to 100 parts by mass of an acrylic ester monomer or a methacrylic ester monomer;
(Iii) a mixture of 0.01 to 20 parts by mass of a functional group-containing monomer copolymerizable therewith, and (i) the component and (ii) and (iii) the sum of the components are in a mass ratio of 50 The anti-vibration rubber composition according to [1], which is an emulsion graft polymer of a mixture in a ratio of 50 to 99: 1.
[5]
The anti-vibration rubber composition according to [4], which is a mixture of 100 parts by weight of component (i), 10 to 100 parts by weight of component (ii), and 0.01 to 20 parts by weight of component (iii).
[6]
[4] or [5], wherein the component (iii) is selected from methacrylic acid, acrylic acid, acrylic amide, allyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate Anti-vibration rubber composition.
[7]
(Ii) The vibration-insulating rubber composition according to any one of [2] to [6], wherein the component is an acrylic ester or methacrylic ester having an alkyl group having 1 to 10 carbon atoms.
[8]
The polyorganosiloxane represented by the formula (1) is a cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer or alkoxysilane, and a silane coupling agent represented by the following general formula (2) The vibration-insulating rubber composition according to any one of [1] to [7], which is a polymer of
R ³ _(4-ef) R ⁴ _f Si (OR ⁵ ) _e (2)
(Wherein R ³ is a mercapto group, an acryloxy group or a methacryloxy group-substituted alkyl group having 1 to 6 carbon atoms, or a vinyl group, R ⁴ is an alkyl group having 1 to 4 carbon atoms, and R ⁵ is carbon. (Equation is an alkyl group of 1 to 4, e is 2 or 3, f is 0 or 1, and e + f is 2 or 3.)
[9]
An anti-vibration rubber comprising a crosslinked product of the anti-vibration rubber composition according to any one of [1] to [8].
[10]
The anti-vibration rubber according to [9], which is for vehicle parts.

The anti-vibration rubber composition of the present invention contains a specific silicone acrylic graft copolymer resin in the rubber component, so that when the anti-vibration rubber made of the cured product of the composition is used for a part such as a stabilizer bush, the friction is obtained. The reduction effect is maintained for a long time.

The anti-vibration rubber composition of the present invention contains (I) a rubber component and (II) a silicone acrylic graft copolymer resin.
Below, each component is explained in full detail.

In the present invention, (I) rubber component includes butadiene rubber (BR), styrene butadiene rubber (SBR), nitrile rubber (NBR), isoprene rubber (IR), diene rubber such as chloroprene rubber (CR), ethylene propylene, and the like. Olefin rubbers such as rubber (EPR, EPDM), butyl rubber (IIR), halogenated butyl rubber such as brominated butyl rubber (Br-IIR), other polyurethane rubber, acrylic rubber, fluoro rubber, silicone rubber, chlorosulfonated polyethylene, etc. Examples thereof include synthetic rubbers, natural rubbers and the like, and these can be used alone or in combination of two or more.

(II) The silicone acrylic graft copolymer resin is a polymer of a polyorganosiloxane represented by formula (1) and an acrylate monomer or a methacrylic acid ester monomer, preferably (i) the following general formula A mixture of the polyorganosiloxane represented by (1) and (ii) (meth) acrylic acid ester monomer, or (i), (ii) and (iii) a functional group-containing monomer copolymerizable therewith. It is obtained by emulsion graft polymerization of a mixture with a monomer.

Here, (i) polyorganosiloxane is represented by the following general formula (1).

Wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ² is an alkyl group having 1 to 6 carbon atoms substituted with a mercapto group, an acryloxy group or a methacryloxy group. X is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, alkoxy group or hydroxyl group having 1 to 20 carbon atoms, Y is X or — [O —Si (X) ₂ ] _d —X is the same or different group, and at least two of X and Y are hydroxyl groups, Z is an alkyl group having 1 to 4 carbon atoms, and 1 to 4 carbon atoms. A is a positive number from 0 to 1,000, b is a positive number from 100 to 10,000, c is a positive number from 1 to 10, and d is a positive number from 1 to 1,000. .)

Here, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl Group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group and other alkyl groups, cyclopentyl group, cyclohexyl group, cycloheptyl group and other cycloalkyl groups, vinyl group, allyl group Alkenyl groups such as phenyl group, tolyl group and naphthyl group, alkenyl aryl groups such as vinylphenyl group, aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group, vinylbenzyl group and vinylphenylpropyl group Alkenyl aralkyl groups such as these, and some or all of the hydrogen atoms of these groups are fluorine Bromine, halogen atom such as chlorine, acryloxy group, methacryloxy group, a carboxyl group, an alkoxy group, an alkenyloxy group, an amino group, and those which are substituted with an alkyl or alkoxy or (meth) acryloxy-substituted amino group. R ¹ is preferably a methyl group.

R ² is a mercapto group, an acryloxy group or a methacryloxy group-substituted alkyl group having 1 to 6 carbon atoms, or a vinyl group. Specifically, a mercaptopropyl group, an acryloxypropyl group, a methacryloxypropyl group, a vinyl group and the like are preferable.

X is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group, and is an unsubstituted or substituted monovalent group having 1 to 20 carbon atoms. Examples of the hydrocarbon group are the same as those exemplified for R ^1. Specific examples of the alkoxy group having 1 to 20 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a hexyloxy group. , Heptyloxy group, octyloxy group, decyloxy group, tetradecyloxy group and the like. X is preferably a hydroxyl group, a methyl group, a butyl group, or a phenyl group.

Y is the same or different group represented by X or — [O—Si (X) ₂ ] _d —X.
d is a positive number of 1 to 1,000, preferably 1 to 200.
Further, in the present invention, from the viewpoint of crosslinkability, it has at least 2, preferably 2 to 4 hydroxyl groups in X and Y, and has at both ends. preferable.

Z is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a hydroxyl group, preferably a hydroxyl group or a methyl group.

If a is greater than 1,000, the strength of the resulting cured product will be insufficient, so a positive number from 0 to 1,000, preferably a positive number from 0 to 200, and b being less than 100, If it is greater than 10,000, the tear strength of the resulting cured product will be reduced, so a positive number of 100 to 10,000, preferably a positive number of 1,000 to 5,000. c is a positive number of 1 to 10, and if it exceeds 10, gelled particles are easily formed during the reaction.
The arrangement of the repeating units may be a block or random.

Such (i) polyorganosiloxane is preferably used in the form of an emulsion, and a commercially available product may be used or synthesized. In the case of synthesis, it can be carried out by a known emulsion polymerization method. For example, it may have a halogen atom such as a fluorine atom, a (meth) acryloxy group, a carboxyl group, an alkoxy group, an alkenyloxy group, a hydroxyl group or an amino group. Using a surfactant, a good cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer, alkoxysilane, and the like, and a silane coupling agent represented by the following general formula (2) are used. It can be easily synthesized by emulsifying and dispersing in water and then adding a catalyst such as an acid as necessary to carry out a polymerization reaction.
R ³ _(4-ef) R ⁴ _f Si (OR ⁵ ) _e (2)
(Wherein R ³ is a mercapto group, an acryloxy group or a methacryloxy group-substituted alkyl group having 1 to 6 carbon atoms, or a vinyl group, R ⁴ is an alkyl group having 1 to 4 carbon atoms, and R ⁵ is carbon. (Equation is an alkyl group of 1 to 4, e is 2 or 3, f is 0 or 1, and e + f is 2 or 3.)

Specific examples of the cyclic organosiloxane include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), 1,1. -Diethylhexamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, 1,1-diphenylhexamethylcyclotetrasiloxane, 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane, 1,3,5,7- Tetramethylcyclotetrasiloxane, 1,3,5,7-tetracyclohexyltetramethylcyclotetrasiloxane, tris (3,3,3-trifluoropropyl) trimethylcyclotrisiloxane, 1,3,5,7-tetra (3 -Mekakuri Xylpropyl) tetramethylcyclotetrasiloxane, 1,3,5,7-tetra (3-acryloxypropyl) tetramethylcyclotetrasiloxane, 1,3,5,7-tetra (3-carboxypropyl) tetramethylcyclotetrasiloxane 1,3,5,7-tetra (3-vinyloxypropyl) tetramethylcyclotetrasiloxane, 1,3,5,7-tetra (p-vinylphenyl) tetramethylcyclotetrasiloxane, 1,3,5, 7-tetra [3- (p-vinylphenyl) propyl] tetramethylcyclotetrasiloxane, 1,3,5,7-tetra (N-acryloyl-N-methyl-3-aminopropyl) tetramethylcyclotetrasiloxane, 1 , 3,5,7-tetra (N, N-bis (lauroyl) -3-aminopropyl) te La tetramethylcyclotetrasiloxane and the like. Preferably, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane are used.

Specific examples of the silane coupling agent include vinyl silanes such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl methyl dimethoxy silane, vinyl methyl diethoxy silane; γ- ( (Meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltripropoxysilane, γ- (meth) acryloxypropyltriisopropoxysilane, γ- (meta ) Acryloxypropyl tributoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxypropylmethyldipropoxysilane, γ Acrylic silanes such as (meth) acryloxypropylmethyldiisopropoxysilane and γ- (meth) acryloxypropylmethyldibutoxysilane; mercaptosilanes such as γ-mercaptopropylmethyldimethoxysilane and γ-mercaptopropyltrimethoxysilane Etc. Alternatively, an oligomer obtained by condensation polymerization of these may be more preferable because generation of alcohol is suppressed. Here, (meth) acryloxy represents acryloxy or methacryloxy.
These silane coupling agents are preferably used in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer or alkoxysilane. The use of 01 to 5 parts by mass is more preferable.

By copolymerizing the silane coupling agent, a polyorganosiloxane having a siloxane unit of c in formula (1) is obtained, and the effect of grafting the monomer of component (ii) or (iii) is obtained.

In the above reaction, a known polymerization catalyst may be used as the catalyst used for the polymerization. Among these, strong acids are preferable, and hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid, citric acid, lactic acid, and ascorbic acid are exemplified. Preferred is dodecylbenzenesulfonic acid having emulsifying ability.
The amount of the acid catalyst used is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer or alkoxysilane, More preferably, it is 0.2 to 2 parts by mass.

Examples of the surfactant used for the polymerization include anionic surfactants such as sodium lauryl sulfate, sodium laureth sulfate, N-acyl amino acid salt, N-acyl taurine salt, aliphatic soap, alkyl phosphate and the like. However, those which are easily soluble in water and do not have a polyethylene oxide chain are preferred. More preferred are N-acyl amino acid salts, N-acyl taurine salts, aliphatic soaps and alkyl phosphates, and particularly preferred are sodium lauroyl methyl taurine, sodium myristoyl methyl taurine and sodium lauryl sulfate.
The amount of the anionic surfactant used is 0.1 to 20 parts by mass with respect to 100 parts by mass of the cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer or alkoxysilane. The amount is preferably 0.5 to 10 parts by mass.

The polymerization temperature is preferably 50 to 75 ° C., and the polymerization time is preferably 10 hours or more, more preferably 15 hours or more. Further, it is particularly preferable to age at 5 to 30 ° C. for 10 hours or longer after polymerization. Further, the pH of the obtained polymerization solution is preferably 6-8.

In the above reaction, for example, the case where octamethyltetrasiloxane is used as the cyclic organosiloxane and γ-methacryloxypropylmethyldimethoxysilane is used as the silane coupling agent is as follows.

In the present invention, (ii) acrylic acid ester monomer or methacrylic acid ester monomer (hereinafter sometimes referred to as acrylic component or (meth) acrylic acid ester monomer) is a hydroxyl group, an amide group, a carboxyl group. Acrylic acid ester monomer or methacrylic acid ester monomer having no functional group such as a group, preferably an acrylic acid ester or methacrylic acid ester having an alkyl group having 1 to 10 carbon atoms, and further an acrylic component polymer A monomer having a glass transition temperature (hereinafter sometimes referred to as Tg) of 40 ° C. or higher, preferably 60 ° C. or higher is preferred. Examples of such monomers include methyl methacrylate, isopropyl methacrylate, ethyl methacrylate, Examples include cyclohexyl methacrylate. The upper limit of Tg is preferably 200 ° C. or lower, more preferably 150 ° C. or lower. The glass transition temperature can be measured based on JIS K7121.

The polyorganosiloxane of formula (1) obtained as described above preferably has 2 to 10 crosslinking points, preferably 2 to 6 crosslinking points per mole of the polymer. (Ii) Graft with component Polymerization can be derived.

In the present invention, (iii) the functional group-containing monomer copolymerizable with the component (ii) includes a functional group such as an unsaturated bond including a carboxyl group, an amide group, a hydroxyl group, a vinyl group, and an allyl group. Specific examples include monomers such as methacrylic acid, acrylic acid, acrylic amide, allyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and these are copolymerized By doing so, it becomes possible to improve the compatibility.

The (II) silicone acrylic graft copolymer resin according to the present invention is first prepared from (ii) the polyorganosiloxane obtained as described above, and (ii) a (meth) acrylic acid ester monomer, preferably (ii) ) And (iii) a mixture of this and a copolymerizable functional group-containing monomer is subjected to emulsion graft polymerization.

In this case, the mass ratio of the polyorganosiloxane of formula (1) to the (meth) acrylic acid ester monomer in the graft polymerization is 50:50 to 99: 1, preferably 70:30 to 99: 1. It is. If the silicone component is less than 50 by mass ratio, sufficient vibration isolation may not be obtained and abnormal noise may occur.

In the case of using a mixture of the above components (i) and (ii), it is preferable to use 1 to 100 parts by weight of component (ii) with respect to 100 parts by weight of component (i), and use 10 to 100 parts by weight. It is more preferable to use 40 to 100 parts by mass.
When a mixture of the above components (i) to (iii) is used, 1 to 100 parts by weight of component (ii) and 0.01 to 20 parts of component (iii) with respect to 100 parts by weight of component (i). It is preferable to use 10 parts by mass of component (ii), more preferably 0.01 to 20 parts by mass of component (iii), and 40 to 100 parts by mass of component (ii). More preferably, 0.01 to 5 parts by mass of the component is used. In this case, it is preferable that (i) :( ii) + (iii) = 50: 50 to 99: 1.

Here, examples of the radical initiator used for graft polymerization include persulfates such as potassium persulfate and ammonium persulfate, aqueous hydrogen persulfate, t-butyl hydroperoxide, and hydrogen peroxide. If necessary, a redox system using a reducing agent such as acidic sodium sulfite, Rongalite, L-ascorbic acid, tartaric acid, saccharides and amines can also be used.
The amount of the radical initiator used is preferably from 0.1 to 5% by mass, more preferably from 0.5 to 3% by mass, based on the total amount of the components (ii) and (iii).

The surfactant already contained in the emulsion when the polyorganosiloxane is already prepared can be sufficiently graft-polymerized, but for the purpose of improving the stability, anionic surfactants such as sodium lauryl sulfate, sodium laureth sulfate, N-acyl amino acid salts, N-acyl taurine salts, aliphatic soaps, alkyl phosphates and the like can be added. Moreover, nonionic emulsifiers, such as polyoxyethylene lauryl ether and polyoxylene tridecyl ether, can also be added.
The amount used in the case of adding the surfactant is preferably 0.1 to 5% by mass of the total amount of the components (ii) and (iii).

Furthermore, a chain transfer agent can be added to adjust the molecular weight and graft ratio of the graft polymer.

The graft polymerization temperature is preferably 25 to 55 ° C, more preferably 25 to 40 ° C. The polymerization time is preferably 2 to 8 hours, more preferably 3 to 6 hours.

The silicone acrylic graft copolymer resin thus obtained is a polymer in which the component (ii) and the component (iii) are randomly grafted to the component (i).

Further, the silicone acrylic graft copolymer resin obtained above is preferably 30 to 50% by mass as a solid content in the emulsion. The viscosity (25 ° C.) of the emulsion is preferably 10 to 5,000 mPa · s or less, and more preferably 50 to 1,000 mPa · s. The viscosity can be measured with a rotational viscometer. The average particle size of this emulsion is preferably 1 μm or less, and preferably 0.1 μm (100 nm) to 0.3 μm (300 nm). The pH is preferably 6-8. The average particle size can be measured by a laser diffraction / scattering particle size distribution measuring device.

Since the obtained silicone acrylic graft copolymer resin is in the form of an emulsion, for example, after concentrating the dispersion by a method such as heat dehydration, filtration, centrifugation, decantation, etc., and then washing with water as necessary. Water is removed by heat drying under normal pressure or reduced pressure, spray drying in which the dispersion is sprayed in an air stream, heat drying using a fluidized heat medium, etc., and then once dried and powdered. The drying temperature is preferably 60 to 105 ° C.
When the obtained powder is slightly agglomerated, it may be pulverized by appropriately using a pulverizer such as a jet mill, a ball mill, or a hammer mill.

In order to remove the cyclic organosiloxane and the surfactant remaining in the obtained silicone acrylic graft copolymer resin, it may be washed. In this case, the solvent is preferably an alcohol organic solvent or a hydrocarbon organic solvent, and examples thereof include lower alcohols having 1 to 4 carbon atoms and aliphatic hydrocarbons having 5 to 20 carbon atoms. More preferred are ethanol, isopropyl alcohol, hexane, and isododecane.
For example, 100 parts by mass of powder is collected in a beaker, and the solvent is added at least 5 times its mass, stirred for several hours, and suction filtered. After that, it is more effective to wash with the same solvent or with a solvent that dissolves in water such as alcohol. In this case, it is usually performed at room temperature (25 ° C.), but it may be heated in some cases.

When washed, it is re-dried to form powder, but the filtered powder may be simply dried at a temperature of 40 ° C. or higher and 200 ° C. or lower for several hours with a dryer, or a fluid dryer or the like may be used. .

The silicone acrylic graft copolymer resin thus obtained preferably has an average particle size of 15 μm or less, particularly 0.1 to 10 μm.
The weight average molecular weight of the silicone acrylic graft copolymer resin is preferably 50,000 to 500,000. If it is less than 50,000, precipitation on the rubber compound surface may become severe, and if it exceeds 500,000, the friction reducing effect may be insufficient. The weight average molecular weight is measured in terms of dimethylsilicone molecular weight from a kinematic viscosity measurement value at 25 ° C. obtained by mixing an emulsion and isopropyl alcohol (IPA), extracting and drying 1 g of the oil in 100 mL of toluene.

(II) The blending amount of the silicone acrylic graft copolymer resin is 1 to 30 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the (I) rubber component. If it is less than 1 part by mass, the effect of reducing friction is poor, and if it exceeds 30 parts by mass, it may precipitate on the surface of the rubber compound and an appropriate effect may not be exhibited.

The anti-vibration rubber composition of the present invention contains, in addition to the above essential components, a vulcanizing agent conventionally used as an additive for rubber (0.1) to 10 parts by mass with respect to 100 parts by mass of the rubber component. Mass parts can be included.
Examples of the vulcanizing agent include sulfur and peroxides, and other compounds and resins can be used as long as they have a vulcanizing effect.

The anti-vibration rubber composition of the present invention further comprises a vulcanization accelerator, a reinforcing agent, a vulcanization aid, a softening agent, a processing aid, an antiaging agent, a filler and the like in (I) 100 parts by mass of the rubber component. Each can be blended in an amount of 0.1 to 10 parts by mass.
Examples of the reinforcing agent and filler include inorganic fillers such as carbon black, acetylene black, graphite, silica, calcium carbonate, talc, and clay. When a reinforcing agent is used, 10 to 200 parts by mass is preferably blended with 100 parts by mass of the rubber component.
Examples of the vulcanization accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, thiurams such as tetraethylthiuram monosulfide, thioureas, guanidines such as diphenylguanidine, thiazoles such as mercaptobenzothiazole and dibenzothiazyl disulfide, Select one or more of higher fatty acids such as stearic acid, such as sulfenamides such as cyclohexylbenzothiazole sulfenamide, butylbenzothiazole sulfenamide, dithiocarbamate such as zinc dimethyldithiocarbamate, etc. Is possible.
Examples of the vulcanization aid include ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanuric acid ester, zinc white, magnesium oxide, zinc oxide and the like.
Antiaging agents include aromatic secondary amines, bisphenols, polyphenols, imidazoles, thioureas, waxes and the like.
Among the above additives, it is particularly preferable to use a vulcanization accelerator and a vulcanization aid in order to accelerate vulcanization.

The anti-vibration rubber composition of the present invention is obtained by kneading, extrusion molding, injection molding and the like of these components with a usual processing apparatus such as a roll, a Banbury mixer, a kneader, etc., to obtain a rubber molded product having a desired shape. .

The anti-vibration rubber can be obtained by vulcanizing this rubber composition by a known method. At this time, the rubber composition can be vulcanized by heating at about 120 to 250 ° C. for 1 to 60 minutes.
The molded product depends on the shape of the object, but when covering the shaft of an automobile, the vehicle part is obtained by vulcanizing and molding into a desired shape such as a cylinder and inserting the object. Can do.
The obtained anti-vibration rubber molded article is excellent in releasability from the mold.

The anti-vibration rubber of the present invention obtained as described above can be used as a protective member for vehicle parts, and can be preferably used for an inset bush such as a stabilizer bush. It can be used for a part that touches and receives rotational force or load.

Hereinafter, although a manufacture example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the following examples, the weight average molecular weight was measured in terms of dimethylsilicone molecular weight based on a kinematic viscosity measurement value at 25 ° C. in which emulsion and IPA were mixed, 1 g of the oil was dried after extraction and dissolved in 100 mL of toluene.

[Production Example 1]
499.6 g of octamethylcyclotetrasiloxane, 0.8 g of γ-methacryloxypropylmethyldiethoxysilane, 5 g of sodium lauryl sulfate dissolved in 45 g of pure water, and 5 g of dodecylbenzenesulfonic acid dissolved in 45 g of pure water were charged into a polyethylene beaker 2L, was uniformly emulsified by a homomixer, water 400g was diluted by adding slowly passed twice through a high pressure homogenizer at a pressure 300 kgf / cm ^2, to give a homogeneous white emulsion. This emulsion was transferred to a 2 L glass flask equipped with a stirrer, thermometer and reflux condenser, subjected to a polymerization reaction at 55 ° C. for 24 hours, aged at 10 ° C. for 24 hours, and then 10 g of 10% by weight aqueous sodium carbonate solution. Neutralized to pH 6.8. This emulsion had a non-volatile content (solid content) of 45.4% by mass after drying at 105 ° C. for 3 hours, and the polyorganosiloxane in the emulsion was a non-flowable soft gel. This polyorganosiloxane has a structure (R ¹ = methyl group, R ² = γ-methacryloxypropyl group, Z 1) having a weight average molecular weight of about 400,000 based on the viscosity measured with a kinematic viscometer of a toluene solution. = Ethyl group, X = OH group, methyl group, a = 0, b = 2,500, c = 1).
To this, 55.5 g of methyl methacrylate (MMA) was added dropwise over 3 to 5 hours, while 1.5 g of t-butyl hydroperoxide as a peroxide and 1 L-ascorbic acid as a reducing agent at 30 ° C. 0.0 g was used for redox reaction to obtain a silicone acrylic graft copolymer resin emulsion having a nonvolatile content of 44.5% by mass and a pH of 6.8.
The emulsion was adjusted to a concentration of 10 to 30% by mass and spray-dried (100 ° C.) to obtain a silicone acrylic graft copolymer resin powder. The obtained silicone acrylic graft copolymer resin had an average particle size of 0.2 μm and a weight average molecular weight of about 300,000.

[Production Example 2]
In Production Example 1, 55.5 g of MMA was replaced with 118.7 g of butyl acrylate (BA) and 6.2 g of 2-hydroxyethyl methacrylate (2-HEMA), and 3.4 g of t-butyl hydroperoxide as a reducing agent. A silicone acrylic graft copolymer resin was obtained in the same manner except that 2.2 g of L-ascorbic acid was used. The obtained silicone acrylic graft copolymer resin had an average particle size of 0.2 μm and a weight average molecular weight of about 300,000.

[Production Example 3]
In Production Example 1, the same method except that 55.5 g of MMA was replaced with 210.5 g of MMA and 3.6 g of BA, 5.8 g of t-butyl hydroperoxide and 3.8 g of L-ascorbic acid as a reducing agent was used. A silicone acrylic graft copolymer resin was obtained. The obtained silicone acrylic graft copolymer resin had an average particle size of 0.2 μm and a weight average molecular weight of about 300,000.

[Comparative Production Example 1]
A silicone acrylic graft copolymer resin was prepared in the same manner as in Production Example 1 except that 55.5 g of MMA was replaced with 611.4 g of MMA, 16.5 g of t-butyl hydroperoxide and 11 g of L-ascorbic acid as a reducing agent were used. Got. The obtained silicone acrylic graft copolymer resin had an average particle size of 0.2 μm and a weight average molecular weight of about 300,000.

[Comparative Production Example 2]
In Production Example 1, the same procedure was followed except that 55.5 g of MMA was replaced with 2.5 g of MMA, 0.07 g of t-butyl hydroperoxide and 0.04 g of L-ascorbic acid as a reducing agent were used. A polymer resin was obtained. The obtained silicone acrylic graft copolymer resin had an average particle size of 0.2 μm and a weight average molecular weight of about 300,000.

Table 1 shows the reaction ratio between polyorganosiloxane and (meth) acrylic acid ester.

[Examples 1 to 4, Comparative Examples 1 to 4]
The silicone acrylic graft copolymer resins obtained in Production Examples 1 to 3 and Comparative Production Examples 1 and 2, natural rubber, butadiene rubber, and carbon black are blended in the amounts shown in Table 2, and additives are blended in the amounts described below. Thus, anti-vibration rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were prepared.
Additives are 3 parts by weight of aroma-based process oil, 5 parts by weight of zinc white 3, 1 part by weight of stearic acid, 2 parts by weight of wax, anti-aging agent N-phenyl-N ′-(1,3-dimethylbutyl)- 2 parts by mass of p-phenylenediamine 6C (manufactured by Ouchi Shinsei Chemical Co., Ltd.), 2 parts by mass of anti-aging agent RD (manufactured by Ouchi Shinsei Chemical Co., Ltd.), 1.5 parts by mass of sulfur, vulcanization accelerator CZ ( 1.5 parts by mass of Ouchi Shinsei Chemical Co., Ltd.) and 0.5 parts by mass of the vulcanization accelerator tetramethylthiuram monosulfide TS (Ouchi Shinsei Chemical Co., Ltd.).

The anti-vibration rubber composition was molded into a shape having a through-hole and vulcanized at 150 ° C. for 30 minutes to produce an anti-vibration rubber. Next, a metal stabilizer bar was loaded into the through hole, the vibration-proof rubber was clamped, the stabilizer bar was twisted ± 10 degrees, and the presence or absence of abnormal noise at that time was confirmed in an environment of 25 ° C.

Claims

(I) Rubber component: 100 parts by mass,
(II) Silicone acrylic, which is a polymer of a mixture containing 50 to 99 parts by mass of polyorganosiloxane represented by the following general formula (1) and 50 to 1 parts by mass of an acrylate monomer or methacrylic acid ester monomer Graft copolymer resin: An anti-vibration rubber composition comprising 1 to 30 parts by mass.

Wherein R 1 is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R 2 is an alkyl group having 1 to 6 carbon atoms substituted with a mercapto group, an acryloxy group or a methacryloxy group. X is the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, alkoxy group or hydroxyl group having 1 to 20 carbon atoms, Y is X or — [O —Si (X) 2 ] d —X is the same or different group, and at least two of X and Y are hydroxyl groups, Z is an alkyl group having 1 to 4 carbon atoms, and 1 to 4 carbon atoms. A is a positive number from 0 to 1,000, b is a positive number from 100 to 10,000, c is a positive number from 1 to 10, and d is a positive number from 1 to 1,000. .)
(II) silicone acrylic graft copolymer resin,
(I) 100 parts by mass of the polyorganosiloxane represented by the general formula (1),
The anti-vibration rubber composition according to claim 1, which is an emulsion graft polymer of (ii) a mixture of 1 to 100 parts by mass of an acrylic ester monomer or a methacrylic ester monomer.
The anti-vibration rubber composition according to claim 2, which is an emulsion graft polymer of a mixture of 100 parts by weight of (i) component and 10 to 100 parts by weight of (ii) component.
(II) silicone acrylic graft copolymer resin,
(I) 100 parts by mass of the polyorganosiloxane represented by the general formula (1),
(Ii) 1 to 100 parts by mass of an acrylic ester monomer or a methacrylic ester monomer;
(Iii) a mixture of 0.01 to 20 parts by mass of a functional group-containing monomer copolymerizable therewith, and (i) the component and (ii) and (iii) the sum of the components are in a mass ratio of 50 The anti-vibration rubber composition according to claim 1, which is an emulsion graft polymer of a mixture in a ratio of 50 to 99: 1.
The anti-vibration rubber composition according to claim 4, which is a mixture of 100 parts by mass of component (i), 10 to 100 parts by mass of component (ii) and 0.01 to 20 parts by mass of component (iii).
6. The protection according to claim 4 or 5, wherein the component (iii) is selected from methacrylic acid, acrylic acid, acrylic amide, allyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate. Vibration rubber composition.
7. The anti-vibration rubber composition according to claim 2, wherein the component (ii) is an acrylic acid ester or a methacrylic acid ester having an alkyl group having 1 to 10 carbon atoms.
The polyorganosiloxane represented by the formula (1) is a cyclic organosiloxane, α, ω-dihydroxysiloxane oligomer, α, ω-dialkoxysiloxane oligomer or alkoxysilane, and a silane coupling agent represented by the following general formula (2) The vibration-insulating rubber composition according to any one of claims 1 to 7, which is a polymer of
R 3 (4-ef) R 4 f Si (OR 5 ) e (2)
(Wherein R 3 is a mercapto group, an acryloxy group or a methacryloxy group-substituted alkyl group having 1 to 6 carbon atoms, or a vinyl group, R 4 is an alkyl group having 1 to 4 carbon atoms, and R 5 is carbon. (Equation is an alkyl group of 1 to 4, e is 2 or 3, f is 0 or 1, and e + f is 2 or 3.)
An anti-vibration rubber comprising a crosslinked product of the anti-vibration rubber composition according to any one of claims 1 to 8.
The anti-vibration rubber according to claim 9, which is used for vehicle parts.