JP2002128938A - Silicone rubber composition for sponge molding and manufacturing method of silicone sponge molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicone rubber composition for sponge molding having a fast curing speed and capable of giving a silicone rubber sponge molded article causing no blooming on the surface thereof, and a manufacturing method of a silicone sponge molded article. SOLUTION: The silicone rubber composition for sponge molding comprises (A) 100 pts.wt. of a silicone rubber base compound comprising (a-1) a diorganopolysiloxane raw rubber, (a-2) a reinforcing silica and (a-3) a diorganosiloxane oligomer with both ends blocked with a silanol group or a hexaorganodisilazane, (B) 0.1-10 pts.wt. of an organic peroxide represented by the general formula: R-COOOCOO-R1-OOCOOOC-R and (C) 0.1-20 pts.wt. of an organic foaming agent. The manufacturing method of the silicone rubber sponge molded article is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition for sponge molding and a method for producing a silicone rubber sponge molded product. More specifically, sponge rolls for building gaskets, various packings, copying machines, etc., and sponges for cosmetic puffs and the like. The present invention relates to a silicone rubber composition used as a molded article and a method for producing a silicone rubber sponge molded article.

[0002]

2. Description of the Related Art Silicone rubber is excellent in heat resistance, cold resistance, weather resistance, electrical properties, etc., and is used for sponge molding of construction gaskets, various packings, copying machines, sponge rolls for printers, and cosmetic puffs. It is frequently used as a product. Conventionally, as a method for producing such a silicone rubber sponge, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,2
Organic foaming agents such as 4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), dinitrosopentamethylenetetramine, and azodicarbonamide are added, and heat molding is performed using organic peroxide as a curing agent. The method was adopted. Particularly, when a sponge molded product is manufactured by extrusion molding, a chlorinated benzoyl peroxide such as 2,4-dichlorobenzoyl peroxide or chlorobenzoyl peroxide, which is hardly inhibited from curing due to atmospheric oxygen, has been used. However, silicone rubber compositions containing these chlorinated benzoyl peroxides have problems such as an unpleasant odor during curing and blooming on the surface of the molded silicone rubber product after curing. Blooming is a phenomenon in which a decomposition product of a curing agent gradually deposits on the surface of a molded product, so that the surface becomes white. In order to solve such problems, a silicone rubber composition containing bis (ortho-methylbenzoyl) peroxide as a curing agent (JP-A-59-18758).
Japanese Patent Application Laid-Open No. Sho 62-185750) and a silicone rubber composition containing bis (para-methylbenzoyl) peroxide. However, these silicone rubber compositions have a problem that productivity is inferior due to a low curing rate.

[0003]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, if the composition is cured with a specific organic peroxide, the curing speed is high and blooming does not occur on the surface. The present inventors have found that a silicone rubber sponge molded product can be obtained, and have completed the present invention. That is, an object of the present invention is to provide a silicone rubber composition for sponge molding and a method for producing a silicone rubber sponge molded product which can obtain a silicone rubber sponge molded product having a high curing rate and not causing blooming on the surface. It is in.

[0004]

The present invention relates to (A) (a-1) 100 parts by weight of a diorganopolysiloxane raw rubber, (a-2) 15 to 150 parts by weight of reinforcing silica, and (a-3) a silanol group at both ends. 100 parts by weight of a silicone rubber base compound comprising 0 to 50 parts by weight of a blocked diorganosiloxane oligomer or hexaorganodisilazane and (a-2) a general formula: R-COOOCOO-R ¹ -OOCOOOC-R
{In the formula, R is an alkyl group, an alkoxy group, -SiR ² ₃ group, (wherein, R ² is an alkyl group or an alkoxy _{^{group.) - CH 2 SiR 2 3}} ( wherein, R ² are as defined above in a group represented by.), in -Ph-R ³ _c [wherein, Ph is phenyl group, R ³ is an alkyl group, an alkoxy group, or Si
R ² ₃ group (wherein, R ² is as defined above.), - CH ₂ S
iR ² ₃ (wherein, R ² is as defined above.), c is 0 to 3
It is. R ¹ is an alkylene group having 1 to 10 carbon atoms. Organic peroxide represented by｝ 0.1
The present invention relates to a silicone rubber composition for forming a sponge, comprising 10 to 10 parts by weight and (C) 0.1 to 20 parts by weight of an organic foaming agent.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS To explain this, the component (A)
The component (A) is a main component of the composition of the present invention.
(A-1) component of diorganopolysiloxane
Rubber has a viscosity of 1,000,000 mPa · s or more at 25 ° C.
Is preferably 5 million mPa · s or more.
Is more preferable. Also, its Williams plasticity
50 or more, preferably 100 or more, and 120 or more
More preferred. The polymerization degree is usually 3,000.
0 to 20,000, and the weight average molecular weight is 20 × 10
^Four That is all. As such a component (a-1),
Diorganopolysiloxane raw material represented by the average unit formula shown
Rubber is exemplified. Average unit formula: R_aSiO_{4-a / 2}(Where R is a monovalent hydrocarbon
A is 1.8 or more.
2.3. ). As the monovalent hydrocarbon group, methyl
An alkyl group such as a group, an ethyl group or a propyl group; a vinyl group,
Alkenyl such as allyl, propenyl, and hexenyl
A cycloalkyl group such as a cyclohexyl group;
Aralkyl groups such as nilethyl group; phenyl group, tolyl group
And the like, and an aryl group is exemplified.
3,3,3-trifluoropropyl group, 3-chloropropyl
A ropyl group is exemplified, but at least 50 mol% is methyl.
It is preferably a benzyl group. In addition, one molecule
It is preferable to have a silicon-bonded alkenyl group in the
And a vinyl group is preferred. Vinyl groups are all organic groups in the molecule
Is preferably 0.01 to 0.4 mol% of the total. Honari
The molecular structure can be either linear or branched and linear.
You may. This component can be a homopolymer or a copolymer.
Or a mixture of these polymers. This ingredient
As a specific example of the siloxane unit constituting
Siloxane unit, methylvinylsiloxane unit, methyl
Phenyl siloxane unit, (3,3,3-trifluoroprop
Ropyl) methylsiloxane units. Molecular chain end
Groups present at the ends include trimethylsiloxy groups,
Tylvinylsiloxy group, methylvinylhydroxysiloxy
And a dimethylhydroxysiloxy group. This
As a diorganopolysiloxane raw rubber such as
Methyl vinyl polysiloxane with terminal trimethylsiloxy group blocking
Raw rubber, dimethyl endblocked with trimethylsiloxy groups at both ends
Siloxane / methylvinylsiloxane copolymer raw rubber,
Dimethylvinylsiloxy-blocked dimethylpolysilo at both ends
Xan raw rubber, both ends dimethylvinylsiloxy group blocked di
Methylsiloxane / methylvinylsiloxane copolymer raw
Rubber, dimethylhydroxysiloxy group-blocked dimethyl
Siloxane and methylvinylsiloxane copolymer
And methyl vinylhydroxysiloxy groups at both ends
Cylsiloxane, methylvinylsiloxane, methylphen
Nylsiloxane copolymer raw rubber,
Doxysiloxy group-blocked dimethylsiloxane / methylbi
Nylsiloxane ・ (3,3,3-trifluoropropyl)
Methylsiloxane copolymer raw rubber is exemplified.

[0006] (a-2) Reinforcing silica is a component required to impart extruded shape retention to the composition of the present invention and to impart mechanical strength to the silicone rubber obtained by curing. Examples of such reinforcing silica include dry silica such as fumed silica and wet silica such as precipitated silica. Further, reinforcing silica whose surface is hydrophobized with an organosilicon compound such as an organochlorosilane, hexaorganodidisilazane, or diorganocyclosiloxane oligomer can also be used. This component is the BE
The T method specific surface area is preferably 50 m ² / g or more.
The amount of this component is 15 per 100 parts by weight of component (A).
It is in the range of 150 parts by weight. This is because the mechanical strength is reduced, and if it exceeds 150 parts by weight, it becomes difficult to mix it with the component (a-1).

(A-3) The diorganosiloxane oligomer or hexaorganodisilazane having silanol groups at both ends thereof functions as a surface treating agent for (a-2) reinforcing silica, and the component (a-2) is a-1) It works to facilitate uniform dispersion in the components. Further, it functions to prevent crepe hardening of the component (A). Here, as the diorganosiloxane oligomer having silanol groups at both ends, dimethylsiloxane oligomers having silanol groups at both ends, methylvinylsiloxane oligomers having silanol groups at both ends, dimethylsiloxane / methylvinylsiloxane oligomer having silanol groups at both ends, and silanol groups at both ends. Examples include group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane oligomer and dimethylsiloxane / methylphenylsiloxane oligomer with both terminal silanol groups blocked. Examples of hexaorganodisilazane include hexamethyldisilazane and tetramethyldivinyldisilazane. The amount of the component (a-3) is from 0 to 50 parts by weight, preferably from 1.0 to 100 parts by weight, per 100 parts by weight of the component (a-1).
40 parts by weight. It is preferable that water is used in combination with hexaorganodisilazane. The component (A) has the above-mentioned (a)
-1) Component, (a-2) component and (a-3) component at 150 ° C
Manufactured easily by mixing at ~ 220 ° C.

[0008] The organic peroxide of the component (B) is a curing agent for the composition of the present invention, and has the general formula: R-COOOCOO-R ¹
During -OOCOOOC-R {wherein, R is a methyl group, an ethyl group, an alkyl group such as propyl group, a methoxy group, an ethoxy group, an alkoxy group propoxy, -SiR ² ₃ group (wherein, R ² is a methyl group, ethyl group, an alkyl group such as propyl group, a methoxy group, an ethoxy group, an alkoxy group ^{_{propoxy), -. CH 2 SiR 2}} 3 ( wherein the groups of R ² are represented by the same as defined above). during -Ph-R ³ _c [wherein, Ph is a phenylene group, R ³ is an alkyl group, an alkoxy group, or a SiR ² ₃ group (wherein, R ² is as defined ^{_{above.), - CH 2 SiR 2}} 3 (In the formula, R ² is the same as described above.) And c is 0 to 3. R ¹ is an alkylene group having 1 to 10 carbon atoms. Is represented by｝, but is also represented by the following general formula.

General formula:

Embedded image (In the formula, R and R ¹ are the same as described above.) Examples of such an organic peroxide include the following compounds.

[0010]

Embedded image Or

Embedded image

[0011]

Embedded image

[0012]

Embedded image

[0013]

Embedded image

[0014]

Embedded image

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

Component (B) has a maximum particle size of 50 μm.
The following is preferred. When the component (B) is mixed with the silicone rubber-based compound, it is preferable to mix the component (B) in a paste-like substance dispersed in dimethylpolysiloxane oil. It is to be noted that the use of a curing agent for the silicone rubber composition and a known organic peroxide together with the component (B) may be used as long as the object of the present invention is not impaired. Examples of such organic peroxides include methyl-substituted benzoyl peroxides such as benzoyl peroxide, orthomethylbenzoyl peroxide, metamethylbenzoyl peroxide, and paramethylbenzoyl peroxide; dicumyl peroxide;
Examples thereof include alkyl-based organic peroxides such as 5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide, and t-butylcumyl peroxide. Of these, alkyl-based organic peroxides are preferred. When the component (B) is mixed with the silicone rubber-based compound, it is preferable to mix the component (B) in a paste form in which the component (B) is dispersed in dimethylpolysiloxane oil. The amount of this component is 0.1 to 10 parts by weight per 100 parts by weight of component A).

(C) Organic foaming agents include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (2-methylbutyral Ronitrile), dinitrosopentamethylenetetramine, azodicarbonamide and the like. The addition amount of this component is in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the silicone rubber base compound as the component (A).

The composition of the present invention comprises the component (A)
(C) In addition to these components, in addition to these components, various additives conventionally known to be incorporated into silicone rubber compositions, such as diatomaceous earth, quartz powder, calcium carbonate, carbon black Fillers such as rare earth oxides, cerium hydroxide, cerium silanolate, and cerium fatty acid salts; higher fatty acids such as stearic acid, zinc stearate, and calcium stearate; and metal salts thereof. The use of a mold releasing agent such as a pigment; a pigment, a platinum compound, a flamed titanium dioxide, a flame retardant such as zinc carbonate, or the like may be added as long as the object of the present invention is not impaired. In curing, alkyl-based organic compounds such as dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, di-t-butyl peroxide and t-butylperoxybenzoate are used. An oxidized oxide or an addition reaction curing agent may be used in combination.

The composition of the present invention comprises the above components (A) to (C)
It is easily manufactured by mixing the components uniformly.
As the mixing device, a conventionally known device used in the production of silicone rubber, such as a continuous kneading extruder or a two-roll mill, can be used.

The composition of the present invention comprises the component (A)
It is composed of the component (C), but the component (A) and the component (B)
The compound at the stage of mixing the components was prepared by using a JSR Curastometer III type Curastometer, 130
Torque value measured at 10 ° C / 10 min is 10% of maximum torque value
Become the time required (T ₁₀₎ is equal to or less than 0.25 minutes and, 130 ° C. / torque values at 10 minutes time required for the 90% of the maximum torque value (T ₉₀₎ is 1. It is preferably 0 minutes or less. Here, the JIS III type curast meter is a vulcanization tester for specifying a standard rubber vulcanization rate, and is a standard rubber vulcanization rate specified by SRIS (Rubber Association Standards). Is a vulcanization tester that measures
See page 61 (1973).

In order to produce a silicone rubber sponge molded product using the composition of the present invention, in the case of extrusion molding, the composition of the present invention is continuously charged into an extruder to obtain an uncured silicone rubber molded product. Then, the molded article under normal pressure,
By curing and foaming in hot air at 150 to 600 ° C, preferably 160 to 300 ° C, a silicone rubber sponge molded product is obtained. Here, as the extruder, a conventionally well-known extruder used for extrusion of a silicone rubber composition, for example, a single screw extruder can be used. In the case of die molding, the composition of the present invention is charged into a predetermined molding die, for example, a die, and cured at normal pressure or pressure by a press molding machine heated to 100 to 200 ° C, preferably 130 to 170 ° C. Then, a silicone rubber sponge molded product is obtained by foaming.

Since the composition of the present invention as described above has a high curing rate under heating and does not cause blooming on the surface, it can be used for applications requiring such properties, for example, building gaskets, various packings, It is extremely useful as a sponge molding material such as a sponge roll for a copying machine and a printer, and a cosmetic puff.

[0025]

Next, the present invention will be described in detail with reference to examples. In the examples, “parts” means “parts by weight”, and the viscosity is a value at 25 ° C.

[0026]

Example 1 Methylvinylpolysiloxane raw rubber (degree of polymerization 5000) consisting of 99.86 mol% of dimethylsiloxane units and 0.14 mol% of methylvinylsiloxane units, both ends of the molecular chain of which are blocked with dimethylvinylsiloxy groups.
Part, dry method silica 3 having a BET specific surface area of 200 m ² / g
0 parts, 10 parts of wet silica having a BET specific surface area of 130 m ² / g, and 7.0 parts of a dimethylsiloxane oligomer having a capped silanol group at both ends and having a viscosity of 60 cSt are charged into a kneader mixer, and the mixture is made uniform at 175 ° C. To obtain a silicone rubber-based compound. After cooling the silicone rubber-based compound, 100 parts of the compound was added to a 50% by weight silicone oil paste of an organic peroxide represented by the following formula (100 parts of the organic peroxide and dimethylpolysiloxane oil having a viscosity of 1000 mPa · s). 1.3 parts of azobisisobutyronitrile and 1.5 parts of azobisisobutyronitrile were added and mixed on a two-roll mill to produce a silicone rubber composition for sponge molding. The particle size of the organic peroxide represented by Chemical Formula 11 is as follows:
The maximum particle size was 30 μm, and the average particle size was 2 μm.

[0027]

Embedded image The silicone rubber composition for sponge molding obtained above is put into a single-screw extruder of 65 mmφ equipped with a die having a diameter of 8φ, extruded into a round bar shape, and then heated in a hot air oven at 250 ° C. to be cured and cured. Foamed. The time required to obtain a completely cured sponge molded article was about 140 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was charged into a mold of 40 mm × 60 mm × 6 mmt, and the temperature was adjusted to 1 ° C. using a single-stage press molding machine.
When heated and cured and foamed at 70 ° C. and a pressure of 5 MPa, the time required to obtain a cured sponge molded product was 300 seconds. Table 1 shows the measurement results.
It was shown to.

[0028]

Example 2 Methylvinylpolysiloxane raw rubber (degree of polymerization: 5,000) consisting of 99.86 mol% of dimethylsiloxane units and 0.14 mol% of methylvinylsiloxane units, both ends of the molecular chain of which are blocked with dimethylvinylsiloxy groups.
Part, dry method silica 3 having a BET specific surface area of 200 m ² / g
0 parts, 10 parts of wet silica having a BET specific surface area of 130 m ² / g, and 7.0 parts of a dimethylsiloxane oligomer having a capped silanol group at both ends and having a viscosity of 60 cSt are charged into a kneader mixer, and the mixture is made uniform at 175 ° C. To obtain a silicone rubber-based compound. After cooling the silicone rubber-based compound, 100 parts of the compound was added to a 50% by weight silicone oil paste of an organic peroxide represented by the following formula (100 parts of the organic peroxide and dimethyl polyether having a viscosity of 1,000 mPa · s). 1.3 parts of a mixture of siloxane oil (100 parts) and 1.5 parts of azobisisobutyronitrile were added and mixed on a two-roll mill to prepare a silicone rubber composition for sponge molding. The particle diameter of the organic peroxide represented by Chemical Formula 12 is such that the maximum particle diameter is 50 μm and the average particle diameter is 20 μm.
Met.

[0029]

Embedded image The silicone rubber composition for sponge molding obtained above is put into a single-screw extruder of 65 mmφ equipped with a die having a diameter of 8φ, extruded into a round bar shape, and then heated in a hot air oven at 250 ° C. to be cured and cured. Upon foaming, the time required to obtain a completely cured sponge molded article was about 140 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was added to 40 mm × 60 mm × 6 m
mt and heated and cured / foamed at a temperature of 170 ° C. and a pressure of 5 MPa using a one-stage press molding machine, and it was necessary to obtain a cured sponge molded product. The time was 320 seconds. Table 1 shows the results of these measurements.

[0030]

Example 3 Methylvinylpolysiloxane raw rubber (degree of polymerization: 5,000) consisting of 99.86 mol% of dimethylsiloxane units and 0.14 mol% of methylvinylsiloxane units, both ends of the molecular chain of which are blocked with dimethylvinylsiloxy groups.
Part, dry method silica 3 having a BET specific surface area of 200 m ² / g
0 parts, 10 parts of wet silica having a BET specific surface area of 130 m ² / g, and 7.0 parts of a dimethylsiloxane oligomer having a silanol group at both ends and having a viscosity of 60 cStokes and having a viscosity of 60 cSt are charged into a kneader mixer until the mixture becomes uniform at 175 ° C. The silicone rubber base compound was obtained by mixing. After cooling the silicone rubber-based compound, 100 parts of the compound was added to a 50% by weight silicone oil paste of an organic peroxide represented by the following formula (100 parts of the organic peroxide and dimethyl polyether having a viscosity of 1,000 mPa · s). 0.8 parts of a mixture of 100 parts of siloxane oil) and a 40% by weight silicone oil paste of dicumyl peroxide (40 parts of dicumyl peroxide and a viscosity of 1,000)
1.0 part of a mixture of 100 parts of dimethylpolysiloxane oil of mPa · s) and 1.5 parts of azobisisobutyronitrile were added and mixed on a two-roll mill to prepare a silicone rubber composition for sponge molding. Incidentally, the particle diameter of the organic peroxide represented by Chemical Formula 11, the maximum particle diameter is 30μm,
The average particle size was 2 μm.

[0031]

Embedded image The obtained silicone rubber composition for forming a sponge was put into a single-screw extruder having a diameter of 65 mm and having a diameter of 8 mm, and extruded into a round bar. Upon foaming, the time required to obtain a completely cured sponge molded article was about 140 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was added to 40 mm × 60 mm × 6 m
mt and heated and cured / foamed at a temperature of 170 ° C. and a pressure of 5 MPa using a one-stage press molding machine, and it was necessary to obtain a cured sponge molded product. The time was 300 seconds. Table 1 shows the results of these measurements.

[0032]

Example 4 Methyl vinyl polysiloxane raw rubber (degree of polymerization 5000) consisting of 99.86 mol% of dimethyl siloxane units and 0.14 mol% of methyl vinyl siloxane units in which both ends of the molecular chain are blocked with dimethyl vinyl siloxy groups
Part, dry method silica 3 having a BET specific surface area of 200 m ² / g
0 parts, 10 parts of wet silica having a BET specific surface area of 130 m ² / g, and 7.0 parts of a dimethylsiloxane oligomer having a silanol group at both ends and having a viscosity of 60 centistokes at 25 ° C. were charged into a kneader mixer at 175 ° C. Mixing until uniform resulted in a silicone rubber-based compound. After cooling the silicone rubber-based compound, 100 parts of the compound was added to a 50% by weight silicone oil paste of an organic peroxide represented by the following formula (100 parts of the organic peroxide and a viscosity of 1000 mPa · s).
Mixture of 100 parts of dimethylpolysiloxane oil
0.8 parts of a 40% by weight silicone oil paste of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (100 parts of this organic peroxide and a viscosity of 1,000 mP
1.0 part of a mixture of 100 parts of a · s dimethylpolysiloxane oil) and 1.5 parts of azobisisobutyronitrile
The mixture was added and mixed on two rolls to produce a silicone rubber composition for sponge molding. The maximum particle diameter of the organic peroxide represented by Chemical Formula 12 was 50 μm, and the average particle diameter was 20 μm.

[0033]

Embedded image The obtained silicone rubber composition for forming a sponge was put into a single-screw extruder having a diameter of 65 mm and having a diameter of 8 mm, and extruded into a round bar. Upon foaming, the time required to obtain a completely cured sponge molded article was about 140 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was added to 40 mm × 60 mm × 6 m
mt and heated and cured / foamed at a temperature of 170 ° C. and a pressure of 5 MPa using a one-stage press molding machine. The time required to obtain a cured sponge molded article was 320 seconds. Table 1 shows the results of these measurements.

[0034]

COMPARATIVE EXAMPLE 1 In Example 1, 50% by weight of organic peroxide represented by Chemical Formula 11 was replaced with 50% by weight of paramethylbenzoyl peroxide instead of silicone oil paste.
A silicone rubber composition for sponge molding was produced in the same manner as in Example 1 except that a silicone oil paste (a mixture of 100 parts of para-methylbenzoyl peroxide and dimethylpolysiloxane oil having a viscosity of 1000 mPa · s) was blended. The silicone rubber composition for sponge molding obtained above was applied to a 65 m
After being put into a single-screw extruder with mΦ and extruded into a round bar,
It was heated in a heating furnace at 0 ° C. to cure and foam. The time required to obtain a fully cured sponge molded article is about 1
80 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was added to a 40 mm × 60 mm
X6mmt, and heated using a one-stage press molding machine at a temperature of 170 ° C and a pressure of 5MPa.
After curing and foaming, the time required to obtain a cured sponge molded product was 480 seconds. Table 1 shows the results of these measurements.

[0035]

Comparative Example 2 In Example 1, a 50% by weight silicone oil paste of an organic peroxide represented by Chemical Formula 11 was replaced with a 50% by weight silicone oil paste of ortho-methylbenzoyl peroxide (100 parts of ortho-methylbenzoyl peroxide and a viscosity of 1%). (A mixture of dimethyl polysiloxane oil of 2,000 mPa · s) was prepared in the same manner as in Example 1 except that a silicone rubber composition for sponge molding was produced. The silicone rubber composition for sponge molding obtained above was applied to a 65 m
After being put into a single-screw extruder with mΦ and extruded into a round bar,
It was heated in a hot air oven at 0 ° C. to cure and foam. The time required to obtain a fully cured sponge molded article is about 1
60 seconds. 14.4 cc of the silicone rubber composition for sponge molding obtained above was added to 40 mm × 60 mm ×
It was charged into a 6 mmt mold and heated and cured / foamed using a one-stage press molding machine at a temperature of 170 ° C. and a pressure of 5 MPa. The time required to obtain a cured sponge molded product was 420 seconds. Table 1 shows the results of these measurements.

[0036]

[Table 1]

[0037]

The silicone rubber composition of the present invention is
It is composed of the components (A) to (C), and has a feature that the curing speed is high because the special organic peroxide of the component (B) is used as a curing agent. Further, the production method of the present invention has a feature that such a silicone rubber sponge molded product can be efficiently produced.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08K 3/36 C08K 3/36 5/14 5/14 5/541 C08L 83/04 C08L 83/04 83/07 83 / 07 (C08L 83/04 // (C08L 83/04 83:06) 83:06) B29K 83:00 B29K 83:00 C08K 5/54 (72) Inventor Hiroshi Honma 2-2 Chigusa Coast, Ichihara-shi, Chiba Toray・ F-term in Dow Corning Silicone Co., Ltd. Research & Development Division 4F074 AA90 AA93 AA95 AC32 AD08 AD17 BA13 BA14 BA16 BA20 BB03 CA24 CC03X CC04Y CC22X CC32Y CC34Y DA39 DA47 DA53 DA59 4F203 AA45 AG20 AK01 AR06 DA03 DA08 DB01 DC01 DD01 4F204 AA45 AG20 AK01 AR06 FA01 FB01 FF01 FN15 FN17 FQ01 FW06 4F207 AA45 AG20 AK01 AR06 KA01 KA11 KA17 KF01 KK51 4J002 CP031 CP061 CP062 CP121 CP131 CP141 CP142 CP151 DJ016 EX007 EX0800 FD010 FD016 FD016 FD016

Claims (9)

[Claims] (A) (a-1) 100 parts by weight of a diorganopolysiloxane raw rubber, (a-2) reinforcing silica 15 to 15
0 parts by weight and (a-3) 100 parts by weight of a silicone rubber base compound comprising 0 to 50 parts by weight of an organosiloxane oligomer having silanol groups at both ends or hexaorganodisilazane, (B) a general formula: R-COOOC
During OO-R ¹ -OOCOOOC-R {wherein, R is an alkyl group, an alkoxy group, -SiR ² ₃ group, (wherein, R ² is an alkyl group or an alkoxy group.) - CH ^₂ SiR _{2 3}
(Wherein R ² is the same as defined above),-
During Ph-R ³ _c [wherein, Ph is a phenylene group, R ³ is an alkyl group, an alkoxy group, or a SiR ² ₃ group (wherein, R ² is as defined ^{_{above.), - CH 2 SiR 2}} 3 ( wherein Wherein R ² is the same as described above), and c is 0 to 3. R ¹ is an alkylene group having 1 to 10 carbon atoms. A silicone rubber composition for forming a sponge, comprising 0.1 to 10 parts by weight of an organic peroxide represented by｝ and (C) 0.1 to 20 parts by weight of an organic foaming agent. 2. The sponge-forming silicone rubber composition according to claim 1, wherein the component (A) is an alkenyl group-containing diorganopolysiloxane raw rubber. 3. The silicone rubber composition for sponge molding according to claim 2, wherein the alkenyl group of the component (A) is a vinyl group, and the content of the vinyl group is 0.01 to 0.4 mol%. 4. The sponge-forming silicone rubber composition according to claim 1, wherein the component (B) is a powdery or granular material and has a maximum particle size of 50 μm or less. 5. The silicone rubber composition for sponge molding according to claim 1, wherein the component (B) is a paste dispersed in dimethylpolysiloxane oil. 6. A time (T ₁₀ ) required for a torque value measured at 130 ° C./10 minutes to become 10% of a maximum torque value using a JSR Curastometer III type is 0.25 minutes or less. And the time (T ₉₀ ) required to reach 90% of the maximum torque value at 130 ° C./10 minutes is 1.
The silicone rubber composition for sponge molding according to claim 1, wherein the time is 0 minute or less. 7. The silicone rubber composition for sponge molding according to claim 1, which is for extrusion molding. 8. The silicone rubber composition for sponge molding according to claim 1 is charged into an extruder to form an uncured silicone rubber molded product.
A method for producing a silicone rubber sponge molded product, which is cured in hot air at 50 to 600 ° C to obtain a silicone rubber molded product. 9. The silicone rubber composition for sponge molding according to claim 1 is put into a mold, and heated or foamed at a temperature of 100 to 200 ° C. under no pressure or under pressure using a press molding machine. A method for producing a silicone rubber sponge molded product, comprising curing to form a silicone rubber sponge molded product.