WO2022234770A1

WO2022234770A1 - Fluorosilicone rubber composition and cured molded product

Info

Publication number: WO2022234770A1
Application number: PCT/JP2022/017893
Authority: WO
Inventors: 修林田
Original assignee: 信越化学工業株式会社
Priority date: 2021-05-07
Filing date: 2022-04-15
Publication date: 2022-11-10
Also published as: JP2022172732A; TW202309198A

Abstract

The present invention is a fluorosilicone rubber composition, wherein the fluorosilicone rubber composition contains: (A) 100 parts by mass of an organopolysiloxane having two or more alkenyl groups bonded to silica atoms per molecule, the number of siloxane units having a fluoroalkyl group being 60 mol% or greater relative to the total number of all siloxane units, and the average degree of polymerization as calculated from the weight-average molecular weight being 2,000 or greater; (B) 5-100 parts by mass of reinforcing silica having a specific surface area according to the BET method of 50 m²/g or greater; (C) 0.1-20 parts by mass of a linear trifluoropropylmethylpolysiloxane in which both ends are blocked by trifluoropropylmethylhydroxysilyl groups; (D) 0.01-5 parts by mass of a linear fluoroxyalkylene-group-containing polymer; and (E) a curing agent in an amount effective for curing. There is thereby provided a fluorosilicone rubber composition having exceptional roll processability despite having a high fluorine content.

Description

Fluorosilicone rubber composition and cured molding

The present invention relates to fluorosilicone rubber compositions and cured moldings.

Silicone rubber has excellent weather resistance, electrical properties, low compression set, heat resistance, and cold resistance. Widely used. In particular, the main chain of the base polymer consists essentially of a repeating structure of (3,3,3-trifluoropropyl)methylsiloxane units having 3,3,3-trifluoropropyl groups as side chain substituents. Fluorosilicone rubber compositions based on fluorosilicone have excellent solvent resistance properties, and are widely used as diaphragms, O-rings, and oil seal materials for parts of transportation equipment and petroleum-related equipment. there is Currently, the demand for silicone rubber is increasing more and more, and the development of silicone rubber having excellent properties is desired.

However, fluorosilicone rubber is known to have strong roll adhesion and poor roll releasability due to the influence of the 3,3,3-trifluoropropyl group. Various compositions have been proposed to improve this roll releasability. For example, a method of adding a perfluoroalkyl group-containing siloxane (Patent Document 1) or adding a polyorganosiloxane containing 5 to 25% by mass of vinyl groups (Patent Document 2) is known. Furthermore, a polyorganosiloxane in which the monovalent organic groups bonded to silicon atoms are selected from alkyl groups, phenyl groups, and vinyl groups, 2 to 25 mol% of the total organic groups are vinyl, and the degree of polymerization is 100 or more; A method for improving roll adhesion by jointly adding 3,3,3-trifluorosilane or a partial hydrolyzed condensate thereof has also been disclosed (Patent Document 3). Furthermore, an improvement has been attempted by blending reinforcing silica surface-treated with silane or siloxane having a γ-trifluoropropyl group and adding silanol-capped siloxane at both ends (Patent Document 4).

However, with these methods, the cost increases because the additives themselves are expensive, and the addition of polysiloxanes with alkyl groups or vinyl groups reduces the inherent oil resistance and fuel oil resistance of fluorosilicone rubber. It has been found that there are negative aspects such as deterioration of

JP-A-3-227352 JP-A-53-146757 Japanese Patent Publication No. 61-57868 JP-A-05-311078

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluorosilicone rubber composition that is excellent in roll processability even with a high fluorine content.

In order to solve the above problems, the present invention
A fluorosilicone rubber composition,
(A) Those having two or more silicon-bonded alkenyl groups in one molecule, and the number of siloxane units having a fluoroalkyl group is 60 mol% or more of the total number of all siloxane units. and an organopolysiloxane having an average degree of polymerization of 2,000 or more calculated from the weight average molecular weight: 100 parts by mass,
(B) reinforcing silica having a specific surface area of 50 m ² /g or more by the BET method: 5 to 100 parts by mass;
(C) a linear trifluoropropylmethylpolysiloxane having both ends blocked with trifluoropropylmethylhydroxysilyl groups: 0.1 to 20 parts by mass;
Provided is a fluorosilicone rubber composition comprising (D) a linear fluorooxyalkylene group-containing polymer: 0.01 to 5 parts by mass, and (E) a curing agent: a curing effective amount.

With such a fluorosilicone rubber composition, even if the fluorine content is high, the fluorosilicone rubber composition is excellent in roll processability.

In addition, the organopolysiloxane of component (A) is linear, and both ends of the molecular chain of the organopolysiloxane are trimethylsiloxy group, dimethylvinylsiloxy group, dimethylhydroxysiloxy group, methyldivinylsiloxy group, and trimethylsiloxy group. It is preferably a group selected from vinylsiloxy groups.

Such component (A) is more preferable as the base polymer of the fluorosilicone rubber composition of the present invention.

Furthermore, the linear fluorooxyalkylene group-containing polymer of component (D) is represented by the following formula (3), (4) or (5);
_HOCH2O ( _CF2O ) _m1 ( _CF2CF2O ) _n1CH2OH ₍ ₃ )
(In the formula, m1 and n1 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)
_CF3O ( _CF2O)m2 ₍ _CF2CF2O _)n2CF3 ₍ ₄ )
(In the formula, m2 and n2 are numbers satisfying the number average molecular weight range of 1,000 to 10,000.)
_HOCH2CF2O ₍ _CF2CF2O ) _n3 ( _CF2O ₎ _m3CF2CH2OH ₍ ₅ )
(In the formula, m3 and n3 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)
is preferably represented by

Such a component (D) is more useful as the roll workability improver of the present invention.

In addition, it is preferable that the curing agent of component (E) is a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst.

Further, it is preferable that the curing agent of the component (E) is an organic peroxide.

By using a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst or an organic peroxide as component (E), the fluorosilicone rubber composition of the present invention can be cured satisfactorily.

In addition, the present invention provides a cured molding made of the cured fluorosilicone rubber composition described above.

The fluorosilicone rubber composition of the present invention provides a cured molded product made of a rubber-like elastic body by molding at the same time as heating and curing.

According to the present invention, it is possible to obtain a fluorosilicone rubber composition that exhibits good roll processability when uncured even if it has a high fluorine content.

As described above, there has been a demand for providing a fluorosilicone rubber composition that is excellent in roll processability even with a high fluorine content.

As a result of intensive studies to achieve the above object, the present inventors have found that a silicon atom bonded to a 3,3,3-trifluoropropyl group is contained in an amount of 60 mol% or more and an average degree of polymerization is 2,000 or more. organopolysiloxane, reinforcing silica, linear trifluoropropylmethylpolysiloxane having both ends blocked with trifluoropropylmethylhydroxysilyl groups, a linear fluorooxyalkylene group-containing polymer, and a curing agent The present inventors have found that a fluorosilicone rubber composition having excellent roll processability even with a high fluorine content can be obtained by blending a silicone rubber composition containing

That is, the present invention
A fluorosilicone rubber composition,
(A) Those having two or more silicon-bonded alkenyl groups in one molecule, and the number of siloxane units having a fluoroalkyl group is 60 mol% or more of the total number of all siloxane units. and an organopolysiloxane having an average degree of polymerization of 2,000 or more calculated from the weight average molecular weight: 100 parts by mass,
(B) reinforcing silica having a specific surface area of 50 m ² /g or more by the BET method: 5 to 100 parts by mass;
(C) linear trifluoropropylmethylpolysiloxane having both ends blocked with trifluoropropylmethylhydroxysilyl groups: 0.1 to 20 parts by mass,
A fluorosilicone rubber composition containing (D) a linear fluorooxyalkylene group-containing polymer: 0.01 to 5 parts by mass, and (E) a curing agent: a curing effective amount.

Although the present invention will be described in detail below, the present invention is not limited to these.

[Fluorosilicone rubber composition]
The present invention is a fluorosilicone rubber composition containing the above components (A) to (E). Each component will be described in detail below.

[(A) Organopolysiloxane]
Component (A) is an organopolysiloxane that is the main ingredient (base polymer) of the present composition. The component (A) organopolysiloxane has two or more silicon-bonded alkenyl groups in one molecule, and the number of siloxane units having a fluoroalkyl group is 60 mol% or more of the total number of all siloxane units. and having an average degree of polymerization of 2,000 or more calculated from the weight average molecular weight.

The organopolysiloxane of component (A) has an average degree of polymerization of 2,000 or more, preferably in the range of 2,000 to 100,000, more preferably in the range of 2,000 to 50,000. is more preferred, and a range of 2,000 to 20,000 is particularly preferred. If the average degree of polymerization is less than 2000, the fluorosilicone rubber composition of the present invention will not satisfy the properties as a millable rubber, and roll kneadability and the like will be significantly deteriorated, which is not preferable. In the present invention, the average degree of polymerization is a value calculated from the polystyrene equivalent weight average molecular weight in GPC (gel permeation chromatography) analysis measured under the following conditions.

[Measurement condition]
(A) component/developing solvent: tetrahydrofuran (THF)
・Flow rate: 1mL/min
・ Detector: Differential refractive index detector (RI)
・Column: 4 TSKGEL SUPERMULTIPORE HZ-H (manufactured by Tosoh Corporation)
・Column temperature: 25°C
・ Sample injection volume: 10 μL (THF solution with a concentration of 0.1% by mass)
・Molecular weight marker polystyrene

In the present invention, component (A) preferably has a high degree of polymerization (high viscosity) and is a non-liquid organopolysiloxane crude rubber that does not self-flow at room temperature (25°C).

In the component (A), the number of siloxane units having a fluoroalkyl group is 60 mol% or more, preferably 65 mol% or more, based on the total number of all siloxane units. The upper limit is not particularly limited as long as it is 100 mol % or less, preferably less than 100 mol %, more preferably 99.8 mol % or less, and may be 98 mol % or less.

The siloxane unit having the fluoroalkyl group may have one or two fluoroalkyl groups bonded to the silicon atom.

Component (A) is preferably represented by the following average compositional formula (1).
R ¹ _n SiO _(4−n)/2 (1)
(In the formula, R ¹ is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a fluoroalkyl group having 1 to 20 carbon atoms, and n is a positive number of 1.95 to 2.04. is.)

In the average composition formula (1), each R ¹ is independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, or 1 to 20 carbon atoms. , preferably 1 to 10, more preferably 1 to 6 fluoroalkyl groups. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl group, ethyl group, propyl group and butyl group; cycloalkyl groups such as cyclohexyl group; alkenyl groups such as vinyl group, allyl group, butenyl group and hexenyl group; Aryl groups such as a phenyl group and a tolyl group, aralkyl groups such as a β-phenylpropyl group, and the like can be mentioned. Among these, a methyl group, a vinyl group and a phenyl group are preferred, and a methyl group and a vinyl group are more preferred. Examples of the fluoroalkyl group include 3,3,3-trifluoropropyl group, 3,3,4,4,4-pentafluorobutyl group, 3,3,4,4,5,5,5-heptafluoro pentyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and the like. Among them, a 3,3,3-trifluoropropyl group is preferred.

In the average composition formula (1), n is a positive number of 1.95 to 2.04, preferably a positive number of 1.98 to 2.02. When n is in the range of 1.95 to 2.04, the resulting cured product exhibits sufficient rubber elasticity.

The organopolysiloxane of component (A) must have two or more alkenyl groups in one molecule, preferably 2 to 50 alkenyl groups. In the average composition formula (1), the alkenyl group preferably accounts for 0.001 to 10 mol% of the total number of moles of R ¹ , and more preferably 0.01 to 5 mol% of the alkenyl group. . The alkenyl group is preferably a vinyl group or an allyl group, and particularly preferably a vinyl group.

Although the structure of the organopolysiloxane of component (A) is not particularly limited, the main chain consists of repeating diorganosiloxane units (R ¹ ₂ SiO _2/2 ), and both ends of the molecular chain are triorganosiloxy groups ₍ R ¹³ SiO _1/2 )-blocked linear diorganopolysiloxanes are preferred. ^R1 is as described above.

Both ends of the molecular chain of the organopolysiloxane of component (A) are blocked with a group selected from trimethylsiloxy, dimethylvinylsiloxy, dimethylhydroxysiloxy, methyldivinylsiloxy, and trivinylsiloxy. preferable. These terminal groups may be the same at both ends of the molecular chain, or may be different.

These organopolysiloxanes may be used singly or in combination of two or more with different degrees of polymerization and molecular structures.

The content of component (A) in the fluorosilicone rubber composition of the present invention is preferably 44 to 96% by mass, more preferably 50 to 90% by mass, and more preferably 60 to 80% by mass. More preferred.

[(B) Reinforcing silica]
The (B) component, reinforcing silica, acts as a filler that imparts excellent mechanical properties to the resulting fluorosilicone rubber composition. The reinforcing silica may be either precipitated silica (wet silica) or fumed silica (dry silica), and preferably has a large number of silanol groups on its surface.

In the present invention, (B) the reinforcing silica must have a specific surface area of 50 m ² /g or more according to the BET method. It is preferably 100 to 400 m ² /g. If the specific surface area is less than 50 m ² /g, the reinforcing effect of the silicone rubber imparted by the component (B) will be insufficient.

Component (B), the reinforcing silica, may be used in an untreated state, or may be surface-treated with an organosilicon compound such as organopolysiloxane, organopolysilazane, chlorosilane, or alkoxysilane, if necessary. good too. Reinforcing silica may be used singly or in combination of two or more.

The amount of reinforcing silica as component (B) is 5 to 100 parts by mass, preferably 10 to 80 parts by mass, and more preferably 20 to 70 parts by mass per 100 parts by mass of organopolysiloxane as component (A). Department. If the amount of component (B) is more than the above upper limit or less than the above lower limit, not only will the resulting fluorosilicone rubber composition be less processable, but also the silicone rubber obtained by curing the above fluorosilicone rubber composition. Mechanical properties such as tensile strength and tear strength of the cured product become insufficient.

[(C) Linear trifluoropropylmethylpolysiloxane having both ends blocked with trifluoropropylmethylhydroxysilyl groups]
Component (C), a trifluoropropylmethylhydroxysilyl-blocked linear trifluoropropylmethylpolysiloxane, is used as a dispersibility improver (surface treatment agent) for reinforcing silica in the fluorosilicone rubber composition of the present invention. acts as

Component (C) is preferably represented by the following average compositional formula (2).

(Wherein, x is a positive number from 1 to 35.)

In the average composition formula (2), x is a positive number of 1-35, preferably a positive number of 3-15. If x is 35 or less, the number of parts added for dispersing the reinforcing silica is appropriate, and as a result, the decrease in viscosity can be prevented and excellent roll workability, which is the object of the present invention, can be obtained.

The amount of component (C) linear trifluoropropylmethylpolysiloxane added is 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of component (A) organopolysiloxane. Department. If the amount of component (C) added is less than 0.1 part by mass, so-called plasticity reversion will occur. The effect of improving workability cannot be obtained.

[(D) Linear fluorooxyalkylene group-containing polymer]
Component (D) is a straight-chain fluorooxyalkylene group-containing polymer, and in the fluorosilicone rubber composition of the present invention, it acts as a roll processability improver for the resulting fluorosilicone rubber composition.

A commercially available product can be used as the (D) component linear fluorooxyalkylene group-containing polymer. For example, it is sold under the trade name FOMBLIN manufactured by Solvay Solexis. Specifically, FOMBLIN D2 (number average molecular weight 1,500), FOMBLIN M07 (number average molecular weight 5,400), FOMBLIN M15 (number average molecular weight 9,700), FOMBLIN Z03 (number average molecular weight 4,000), etc. mentioned.

Examples of such polymers include those having structures represented by the following formulas (3), (4) and (5).
_HOCH2O ( _CF2O ) _m1 ( _CF2CF2O ) _n1CH2OH ₍ ₃ )
(In the formula, m1 and n1 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)
_CF3O ( _CF2O)m2 ₍ _CF2CF2O _)n2CF3 ₍ ₄ )
(In the formula, m2 and n2 are numbers satisfying the number average molecular weight range of 1,000 to 10,000.)
_HOCH2CF2O ₍ _CF2CF2O ) _n3 ( _CF2O ₎ _m3CF2CH2OH ₍ ₅ )
(In the formula, m3 and n3 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)

In the present invention, the number average molecular weight of the component (D) is the number average molecular weight using perfluoro (polyoxypropylene ethyl ether) as a standard substance in GPC (gel permeation chromatography) analysis measured under the following conditions. Point.

[Measurement condition]
・Developing solvent: methyl (perfluorobutyl) ether (trade name: NOVEC HFE7100, manufactured by 3M)
・Flow rate: 0.6mL/min
・ Detector: Differential refractive index detector (RI)
・ Column: 2 TSKGEL SUPERHM-M (manufactured by Tosoh Corporation)
・Column temperature: 40°C
・ Sample injection volume: 10 μL (NOVEC HFE7100 solution with a concentration of 0.1% by mass)
・Molecular weight marker perfluoro (polyoxypropylene ethyl ether)

The blending amount of component (D) is 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass, per 100 parts by mass of organopolysiloxane as component (A). If the amount of component (D) is too small, the roll processability of the fluorosilicone rubber composition will not be improved. occurs, which is economically unfavorable.

[(E) curing agent]
(E) The curing agent is not particularly limited as long as it can cure the fluorosilicone rubber composition of the present invention. (E) component may be used individually by 1 type, and may use 2 or more types together. Component (E) includes, for example, (E-1) organic peroxide curing agent and (E-2) addition reaction type curing agent. The amount of component (E) is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 40 parts by mass, and still more preferably 0.2 parts by mass, based on 100 parts by mass of organopolysiloxane (A). ~10 parts by mass.

(E-1) Organic peroxide curing agent (E-1) Examples of the organic peroxide curing agent include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methyl benzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, di-t-butyl peroxide, t-butyl perbenzoate, 1,6 -hexanediol-bis-t-butyl peroxycarbonate and the like.

The amount of the organic peroxide curing agent is preferably 0.1 to 10 parts by mass, particularly preferably 0.2 to 5 parts by mass, per 100 parts by mass of component (A). If the amount is 0.1 part by mass or more, curing will be sufficient, and if the amount is 10 parts by mass or less, the cured silicone rubber will not turn yellow due to decomposition residues of the organic peroxide.

(E-2) Addition Reaction Curing Agent As (E-2) addition reaction curing agent, an organohydrogenpolysiloxane and a hydrosilylation catalyst are preferably used in combination.

As the organohydrogenpolysiloxane, preferably 2 or more, more preferably 3 or more, more preferably 3 to 200, still more preferably about 4 to 100 hydrogen atoms bonded to silicon atoms in one molecule ( That is, if it contains a hydrosilyl group), its structure may be linear, cyclic, branched or three-dimensional network structure. The hydrosilyl group may be at the end of the molecular chain, in the middle of the molecular chain, or at both.

The organohydrogenpolysiloxane may be any organohydrogenpolysiloxane known as a cross-linking agent for addition reaction-curable silicone rubber compositions. For example, an organohydrogenpolysiloxane represented by the following average compositional formula (6) can be used.
R ² _p H _q SiO _(4-pq)/2 (6)
(R ² is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, p is 0<p<3, q is 0<q≦3, and 0<p+q≦3.)

In the average composition formula (6) above, each R ² is independently a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, which does not have an aliphatic unsaturated bond. Preferably. Specifically, alkyl groups such as methyl group, ethyl group and propyl group, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group and tolyl group, benzyl group, 2-phenylethyl group, 2-phenylpropyl group and the like. and the like. Among them, an alkyl group is preferred, and a 3,3,3-trifluoropropyl group in which some or all of the hydrogen atoms in the alkyl group are substituted with halogen atoms, preferably fluorine atoms, etc., 3,3,4,4, 4-pentafluorobutyl group, 3,3,4,4,5,5,5-heptafluoropentyl group, and 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, etc. may be a fluoroalkyl group of

In the average composition formula (6), p is 0<p<3, preferably 0.5≦p≦2.2, more preferably 1.0≦p≦2.0, and q is 0<q≦ 3, preferably 0.002≤q≤1.1, more preferably 0.005≤q≤1, and p+q is 0<p+q≤3, preferably 1≤p+q≤3, more preferably 1.002≤ It is a positive number that satisfies p+q≦2.7.

The organohydrogenpolysiloxane preferably has a viscosity at 25°C of 0.5 to 10,000 mPa·s, more preferably 1 to 300 mPa·s. In the present invention, viscosity is a value measured at 25° C. using a rotational viscometer according to the method described in JIS K 7117-1:1999.

Examples of organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris(hydrogendimethylsiloxy)methylsilane, tris(hydrogen dimethylsiloxy)phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane/dimethylsiloxane cyclic copolymer, both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, both ends trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane Copolymer, dimethylpolysiloxane blocked at both ends by dimethylhydrogensiloxy groups, dimethylsiloxane/methylhydrogensiloxane copolymer blocked at both ends by dimethylhydrogensiloxy groups, copolymer of methylhydrogensiloxane/diphenylsiloxane blocked at both ends by trimethylsiloxy groups Coalescence, both terminal trimethylsiloxy group-blocked methylhydrogensiloxane/diphenylsiloxane/dimethylsiloxane copolymer, both terminal trimethylsiloxy group-blocked methylhydrogensiloxane/methylphenylsiloxane/dimethylsiloxane copolymer, both terminal dimethylhydrogensiloxy groups A blocked methylhydrogensiloxane/dimethylsiloxane/diphenylsiloxane copolymer, a methylhydrogensiloxane/dimethylsiloxane/methylphenylsiloxane copolymer blocked with dimethylhydrogensiloxy groups at both ends, (CH ₃ ) ₂ HSiO _1/2 units and ( Copolymers consisting of _CH3 ) _3SiO1 /2 units and _SiO4 /2 units, copolymers consisting of ( _CH3 ) _2HSiO1 _/2 _units and SiO4 _/2 units, ( _CH3 ) ₂ A copolymer consisting of HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units, and the above exemplary compounds, in which a part or all of the methyl group is replaced by another alkyl group and those substituted with a phenyl group or the like.

The amount of the organohydrogenpolysiloxane compounded is preferably 0.1 to 40 parts by mass per 100 parts by mass of component (A). In addition, the number ratio of silicon-bonded hydrogen atoms (hydrosilyl groups) is preferably in the range of 0.5 to 10, more preferably 0, per alkenyl group of component (A). A range of 7 to 5 is appropriate. If it is at least the above lower limit, cross-linking will be sufficient, and sufficient mechanical strength will be obtained. Further, when the amount is less than the above upper limit, the physical properties after curing do not deteriorate, and in particular, deterioration of the heat resistance of the silicone rubber and an increase in compression set can be prevented.

The hydrosilylation catalyst is a catalyst for the hydrosilylation addition reaction between the alkenyl groups of component (A) and the silicon-bonded hydrogen atoms (hydrosilyl groups) of the organohydrogenpolysiloxane. Hydrosilylation catalysts include platinum group metal-based catalysts. There are elemental platinum group metals and compounds thereof, and conventionally known catalysts for addition reaction-curable silicone rubber compositions may be used. For example, particulate platinum metal adsorbed on a carrier such as silica, alumina or silica gel, platinum catalyst such as platinic chloride, chloroplatinic acid, alcoholic solution of chloroplatinic acid hexahydrate, palladium catalyst, rhodium catalyst, etc. platinum or platinum compounds (platinum catalysts) are preferred.

The amount of catalyst to be added should be sufficient to promote the above addition reaction. Generally, it is used in the range of 1 mass ppm to 1 mass %, preferably 10 to 500 mass ppm, based on the organopolysiloxane of the component (A) in terms of platinum group metal content. If the amount of the catalyst is at least the above lower limit, the addition reaction will be sufficiently accelerated and curing will be sufficient. If the content is equal to or less than the above upper limit, it is economical because the effect of accelerating the reaction can be obtained according to the amount added.

[Other optional ingredients]
In addition to the components described above, the fluorosilicone rubber composition of the present invention may optionally contain quartz powder, crystalline silica, non-reinforcing silica such as diatomaceous earth, calcium carbonate, acetylene black, furnace black, channel black, and the like. Heat resistance improvers such as carbon black, colorants, iron oxide and cerium oxide, flame retardant improvers such as platinum, titanium oxide and triazole compounds, acid acceptors, thermal conductivity improvers such as alumina and boron nitride, mold release agents, etc. may be added.

The fluorosilicone rubber composition of the present invention can be obtained by uniformly mixing the above components using a mixing device such as a two-roll mill, Banbury mixer, Dow mixer (kneader), etc. (A) , (B), (C), and (D) to prepare a base compound, and then blend the (E) component.

The base compound is preferably prepared by heat treatment at 20 to 250°C, particularly 50 to 200°C, for 0.1 to 10 hours, particularly 0.1 to 5 hours.

[Curing molding]
The fluorosilicone rubber composition of the present invention can be heat-cured and molded at the same time to obtain a cured molding consisting of a rubber-like elastic body (cured silicone rubber).

The method for curing the fluorosilicone rubber composition is not particularly limited, but any method may be used as long as it applies sufficient heat to decompose the curing agent and vulcanize the fluorosilicone rubber composition. The temperature conditions for curing are usually 80 to 400° C., particularly 100 to 200° C., for 3 seconds to 160 minutes, particularly 3 seconds to 20 minutes, although they depend on the curing method. The molding method is not particularly limited, and for example, molding methods such as continuous vulcanization by extrusion molding, press molding (pressure molding), and injection molding can be employed. Further, if necessary, secondary vulcanization may be performed at 150 to 250° C. for about 1 to 10 hours.

Examples and comparative examples are shown below to specifically describe the present invention, but the present invention is not limited to the following examples.

The (A) component organopolysiloxane (organopolysiloxane crude rubber) used in the examples and comparative examples is as follows. In addition, the mol % of siloxane units in the following is the ratio of each siloxane unit to the total number of siloxane units.

(A) Organopolysiloxane raw rubber: 3,3,3-trifluoropropylmethylsiloxane unit 99.825 mol%, methylvinylsiloxane unit 0.125 mol%, dimethylvinylsiloxy unit 0.05 mol%, average polymerization Organopolysiloxane raw rubber with a degree of 4,000

[Example 1]
(A) 100 parts by mass of organopolysiloxane raw rubber, (B) 40 parts by mass of fumed silica having a BET specific surface area of 200 m ² /g (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.), (C1) trifluoropropylmethyl at both ends 6.0 parts by mass of linear 3,3,3-trifluoropropylmethylpolysiloxane having a hydroxysilyl group, an average degree of polymerization of 4, and a viscosity of 15 mPa s at 25° C. (D1) 0.3 part by mass of a chain-shaped fluorooxyalkylene group-containing polymer (trade name “FOMBLIN D2” manufactured by Solvay Solexis, number average molecular weight: 1,500) was kneaded in a kneader and heated to 150° C. under mixing with a kneader. A base compound (1) was prepared by heat-treating for 2 hours.

In the base compound (1), 0.6 of 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane as a curing agent (E) is added to 100 parts by mass of (A) organopolysiloxane raw rubber. Parts by mass were added with a double roll and uniformly mixed to obtain a crude rubber-like silicone rubber composition.

The roll workability test described below was performed on the silicone rubber composition.

[Example 2]
A silicone rubber composition was prepared in the same manner as in Example 1, except that (D1) the linear fluorooxyalkylene group-containing polymer (trade name "FOMBLIN D2") was added in an amount of 0.5 parts by mass. got The obtained composition was subjected to a roll workability test, which will be described later.

[Example 3]
In Example 1, (D2) a linear fluorooxyalkylene group-containing polymer (trade name “FOMBLIN M07” Solvay A silicone rubber composition was obtained in the same manner as in Example 1, except that 0.3 parts by mass of Solexis, number average molecular weight: 5,400) was used. The obtained composition was subjected to a roll workability test, which will be described later.

[Comparative Example 1]
In Example 1, a silicone rubber composition was prepared in the same manner as in Example 1 except that no linear fluorooxyalkylene group-containing polymer was added, and the resulting composition was subjected to the roll processability test described later. rice field.

[Comparative Example 2]
A silicone rubber composition was prepared in the same manner as in Example 1, except that the linear trifluoropropylmethylpolysiloxane of component (C1) was replaced with 6.0 parts by mass of diphenylsilanediol as component (C2). prepared. The obtained composition was subjected to a roll workability test, which will be described later.

The roll workability test method is shown below.

Test method for roll workability After kneading 200 g of the silicone rubber composition 20 times on a 6-inch double roll whose surface was plated with hard chrome, the adhesion to the roll surface was confirmed. It was evaluated as ◯ when it was easily peeled off by hand, Δ when it was slightly stuck and adhered, and x when it strongly adhered.

Table 1 below shows the composition of each example and comparative example and the results of the roll workability test.

From the results shown in Table 1, it can be seen that Examples 1 to 3 containing all of the components (A) to (E) used in the present invention exhibited good roll workability. On the other hand, Comparative Example 1, which did not contain the component (D), exhibited strong adhesion and poor roll workability. Further, Comparative Example 2 using (C2) diphenylsilanediol, which is similar to component (C) but not used in the present invention, instead of component (C) used in the present invention contains component (D). Therefore, although the roll workability was slightly improved, the roll workability was inferior compared to Examples 1 to 3 containing all of the components (A) to (E) used in the present invention.

The present invention is not limited to the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

Claims

A fluorosilicone rubber composition,
(A) Those having two or more silicon-bonded alkenyl groups in one molecule, and the number of siloxane units having a fluoroalkyl group is 60 mol% or more of the total number of all siloxane units. and an organopolysiloxane having an average degree of polymerization of 2,000 or more calculated from the weight average molecular weight: 100 parts by mass,
(B) reinforcing silica having a specific surface area of 50 m 2 /g or more by the BET method: 5 to 100 parts by mass;
(C) linear trifluoropropylmethylpolysiloxane having both ends blocked with trifluoropropylmethylhydroxysilyl groups: 0.1 to 20 parts by mass,
(D) a linear fluorooxyalkylene group-containing polymer: 0.01 to 5 parts by mass; and (E) a curing agent: a curing effective amount.
The organopolysiloxane of component (A) is linear, and both molecular chain ends of the organopolysiloxane are trimethylsiloxy group, dimethylvinylsiloxy group, dimethylhydroxysiloxy group, methyldivinylsiloxy group, and trivinylsiloxy group. 2. The fluorosilicone rubber composition according to claim 1, wherein the group is selected from the group consisting of:
The linear fluorooxyalkylene group-containing polymer of component (D) has the following formula (3), (4) or (5);
HOCH2O ( CF2O ) m1 ( CF2CF2O ) n1CH2OH ( 3 )
(In the formula, m1 and n1 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)
CF3O ( CF2O)m2 ( CF2CF2O )n2CF3 ( 4 )
(In the formula, m2 and n2 are numbers satisfying the number average molecular weight range of 1,000 to 10,000.)
HOCH2CF2O ( CF2CF2O ) n3 ( CF2O ) m3CF2CH2OH ( 5 )
(In the formula, m3 and n3 are numbers satisfying the number average molecular weight range of 1,000 to 5,000.)
3. The fluorosilicone rubber composition according to claim 1 or 2, characterized by being represented by:
4. The fluorosilicone rubber composition according to any one of claims 1 to 3, wherein the curing agent (E) is a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst. thing.
The fluorosilicone rubber composition according to any one of claims 1 to 3, wherein the curing agent of component (E) is an organic peroxide.
A cured molding characterized by comprising a cured product of the fluorosilicone rubber composition according to any one of claims 1 to 5.