JPH05247349A - Silicone rubber composition and cured material - Google Patents

Abstract

PURPOSE:To obtain the subject composition useful as a rubber material for packing and sealing, having excellent tensile strength and tear strength, by blending a specific organopolysilalkylenesiloxane with a filler and a curing agent. CONSTITUTION:(A) 100 pts.wt. organopolysilalkylenesiloxane of formula I {R<1> to R<5> are (substituted) monofunctional hydrocarbon having no aliphatic unsaturated bond; R<6> is monofunctional aliphatic unsaturated hydrocarbon; X is H or group of formula II [R<7> to R<9> are (substituted) monofunctional hydrocarbon]; (n) is >=1; (m) is >=0; (a) is 4-16} is blended with (B) preferably 20-200 pts.wt. filler such as fumed silica and (C) preferably 0.2-5 pts.wt. curing agent such as organic peroxide to give the objective composition. The composition is cured to give a cured material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silicone rubber composition which gives a cured product having high tensile strength and high tear strength.

[0002]

BACKGROUND OF THE INVENTION Silicone rubber is excellent in properties such as electric insulation, heat resistance, cold resistance and weather resistance and is used in various fields.
It had the drawback of being inferior to other rubber materials in tensile strength and tear strength.

Therefore, improvement measures such as adding a treated filler to a silicone rubber composition or adding a polymer having a localized functional group have been proposed, but a cured product having higher tensile strength and tear strength is proposed. There is a need for a silicone rubber composition that provides

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a silicone rubber composition that gives a cured product having high tensile strength and high tear strength, and a cured product thereof.

[0005]

Means and Actions for Solving the Problems As a result of extensive studies conducted by the present inventor in order to achieve the above object, a silicone rubber composition containing a base siloxane component, a filler and a curing agent was used as a siloxane component. It was found that a silicone rubber composition giving a cured product having extremely high tensile strength and tear strength can be obtained by blending an organopolysilalkylene siloxane represented by the following general formula (I), and the present invention provides I arrived.

[0006]

[Chemical 2]

Accordingly, the present invention provides a silicone rubber composition comprising (A) an organopolysilalkylene siloxane of the above formula (I), (B) a filler, and (C) a curing agent, and this composition. A cured product obtained by curing is provided.

The present invention will be described in more detail below. In the silicone rubber composition of the present invention, an organopolysilalkylene siloxane represented by the following general formula (I) is added as a base siloxane component [component (A)]. To do.

[0009]

[Chemical 3]

In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated group, preferably carbon atoms. The number is 1
~ 8, which may be the same or different.

Specifically, an alkyl group such as a methyl group, an ethyl group and a propyl group, a cycloalkyl group such as a cyclohexyl group, an aryl group such as a phenyl group and a tolyl group,
3,3,3-trifluoropropyl group, 6,6,6
A group in which hydrogen atoms of these groups such as 5,5,4,4,3,3-nonafluorohexyl group, chloromethyl group and 3-chloropropyl group are partially substituted with a halogen atom, 2-cyanoethyl Examples thereof include cyanohydrocarbon groups such as groups, and particularly preferred are methyl group, ethyl group, phenyl group and 3,3,3-trifluoropropyl group. R ⁶ is a monovalent aliphatic unsaturated hydrocarbon group, and examples thereof include a vinyl group, an allyl group and an ethynyl group, with a vinyl group being preferred.

Further, X is a hydrogen atom or the following general formula (I
It is a group represented by I).

[0013]

[Chemical 4] (In the formula, R ⁷ , R ⁸ and R ⁹ are each an unsubstituted or substituted monovalent hydrocarbon group, for example, a hydrocarbon group having no aliphatic unsaturated bond as exemplified above as R ^{1 to} R ⁵ , a vinyl group, And an alkenyl group such as an allyl group and a hexenyl group, which may be the same or different from each other.)

Examples of such X include a hydrogen atom,
_{(CH 3) 3 Si -,} (CH 2 = CH) (CH 3) 2 Si-
Are preferably used.

Further, n is an integer of 1 or more, preferably 10
Is an integer of 0 to 10,000, m is an integer of 0 or more, a
Is an integer of 4 to 16. As will be understood from these values of n and m, the organopolysylalkylene of the above formula (I) does not require the constitutional unit represented by the following formula as an essential constitutional unit.

[0016]

[Chemical 5]

The organopolysilalkylene siloxane of the above formula (I) can be produced by a known method.
In this case, in the above formula (I), X is a hydrogen atom, that is, one having a silanol group at the molecular chain end is, for example, an organosyl alkylene siloxane represented by the following general formula (III) and the following general formula (IV) It can be synthesized by copolymerizing with a diorganosiloxane represented by the following in the presence of an alkali or acid catalyst.

[0018]

[Chemical 6]

Further, the organopolysilalkylene siloxane in which the molecular terminal of the above formula (I) is blocked by the group represented by the above general formula (II) is a compound represented by the following general formula (V) or formula during the above synthesis. It can be produced by copolymerization in the presence of the silicon compound represented by (VI).

[0020]

[Chemical 7]

Examples of the alkali or acid catalyst used in the above copolymerization include alkali hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, alkali siliconates such as lithium siliconate and potassium siliconate, and tetrabutyl. Derived from quaternary salt hydroxides such as phosphine hydroxide and tetrabutylammonium hydroxide, sulfonic acids such as sulfuric acid and trifluoromethanesulfonic acid, trifluoroacetic acid, and hexafluoropropene oxide oligomers represented by the following general formula Examples thereof include fluorinated carboxylic acid.

[0022]

[Chemical 8]

In this case, the amount of the alkali or acid catalyst added is 0.01 to 5 parts by weight, preferably 0.05 to 1.0 parts by weight, based on 100 parts by weight of siloxane. The mixing ratio of the starting materials is not particularly limited, but may be as follows, and the reaction temperature is 90 to 150 ° C., especially 12
The temperature is preferably 0 to 150 ° C.

[0024]

[Chemical 9]

In the present invention, a filler is used as the component (B) in addition to the organopolysilalkylenesiloxane as the component (A). Here, as the filler, various fillers used in general silicone rubber compositions can be used, for example, fumed silica, precipitated silica, carbon powder, titanium dioxide, aluminum oxide, quartz powder, Reinforcing fillers such as talc, sericite and bentonite, and fibrous fillers such as asbestos, glass fibers and organic fibers.

In the present invention, these fillers are usually
It is preferable to add 10 to 300 parts by weight, particularly 20 to 200 parts by weight, per 100 parts by weight of the component (A). When the amount of this filler is less than 10 parts by weight,
In some cases, it may not be possible to obtain a sufficient reinforcing effect, and if it is compounded in a proportion exceeding 300 parts by weight, the mechanical strength of the cured product may decrease, which may be a disadvantage.

In the silicone rubber composition of the present invention, the curing agent used as the component (C) may be, for example, an organic peroxide or an organopolysiloxane having at least one hydrogen atom bonded to a silicon atom in the molecule. Hydrogen polysiloxane and the like are preferably used.

As the organic peroxide, various ones used for organic peroxide crosslinking can be used, and examples thereof include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 4-monochlorobenzoyl peroxide, and the like. Dicumyl peroxide, tert-butyl benzoate, tert-butyl peroxide, 2,5
-Dimethyl-2,5-bis (tert-butylperoxy) hexane, cumyl-tert-butylperoxide and the like can be used alone or in combination of two or more.

On the other hand, examples of the organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in the molecule include the following. In the formula below, Me is a methyl group, Ph is a phenyl group, and Pr is a propyl group.

[0030]

[Chemical 10]

The compounding amount of such a curing agent is generally 0.2 to 10 parts by weight with respect to 100 parts by weight of the component (A), but in the case of an organic peroxide, it is usually used. The amount is preferably 0.2 to 5 parts by weight per 100 parts by weight of the component (A), and is 0.5 to 10 parts by weight per 100 parts by weight of the component (A) in the case of the above organohydrogenpolysiloxane. Is. When an organohydrogenpolysiloxane is used, a known platinum-based catalyst can be added.

In the silicone rubber composition of the present invention, various compounding agents can be added in addition to the above-mentioned essential components within the range not impairing the object of the present invention. For example, dispersants such as diphenylsilanediol, low-polymerization degree molecular chain terminal hydroxyl group-blocked dimethylpolysiloxane, and hexamethyldisilazane; heat resistance improvers such as ferrous oxide, ferric oxide, cerium oxide, and iron octylate; A colorant such as a pigment can be blended if necessary. .

The silicone rubber composition of the present invention can be easily prepared by uniformly kneading the above-mentioned components using a mixer such as a roll, a kneader, or a Banbury mixer.

This silicone rubber composition is heat-treated at a temperature of 100 to 200 ° C. for 30 seconds to 1 hour under normal pressure or a pressure, and if necessary, subjected to secondary vulcanization at a temperature of 150 to 200 ° C. for 2 to 24 hours. By doing so, it is completely cured to give a silicone rubber cured product rich in elasticity.

[0035]

The silicone rubber composition of the present invention provides a cured product having high tensile strength and high tear strength.
The rubber material can be effectively used in applications requiring these properties, for example, rubber materials for packing and sealing.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1] A silalkylene siloxane 600 represented by the following formula (1) was placed in a 1-liter four-necked flask equipped with a stir bar, a nitrogen introduction tube, a thermometer and an exhaust tube.
g, a diorganosiloxane represented by the following formula (2): 1.
Charge 6 g and 0.3 g of potassium siliconate to 100
When heated and stirred at 0 ° C. for 3 hours, a raw rubber-like polymer (organopolysilalkylenesiloxane represented by the following formula (3)) was obtained.

[0038]

[Chemical 11]

Next, the following ingredients were kneaded with a kneader,
Heat treatment was performed at a temperature of 105 ° C. for 4 hours.

100 parts by weight of the above-mentioned polymer (organopolysilalkylenesiloxane) fumed silica (specific surface area 200 m ² / g) 40 〃 diphenylsilanediol 3.9 〃 viscosity 20cs, both ends of the molecular chain are blocked with hydroxyl groups Dimethylpolysiloxane 3.9 〃 Furthermore, 100 parts by weight of the above kneaded material, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
Part by weight was uniformly mixed using a two-roll mill to obtain a composition I.

This composition I was treated at a temperature of 140 ° C. and a pressure of 120.
After pressing under a condition of kg / cm ² for 20 minutes to form a sheet having a thickness of 2 mm, it was further heat-treated at a temperature of 140 ° C. for 4 hours.

Comparative Example 1 For comparison, a composition II was prepared by using dimethyl silicone raw rubber in place of the organopolysilalkylene siloxane and by the same formulation as above. The composition II was treated at a temperature of 170 ° C. and a pressure of 120 k.
After pressing under a condition of g / cm ² for 20 minutes to form a sheet having a thickness of 2 mm, it was further heat-treated at a temperature of 200 ° C. for 4 hours.

When the physical properties of the sheets obtained in Example 1 and Comparative Example 1 were examined, the results shown in Table 1 were obtained.

[0044]

[Table 1]

From the results shown in Table 1, the silicone rubber composition of the present invention (Example 1) has a tensile strength of 1.8 times and a tear strength of 2.1 times that of the silicone rubber composition of Comparative Example 1. It was confirmed to give a cured product having high strength and high tear strength.

Example 2 A silalkylene siloxane 200 represented by the above formula (1) was placed in a 1-liter four-necked flask equipped with a stir bar, a nitrogen introducing tube, a thermometer and an exhaust tube.
g, the diorganosiloxane of the above formula (2) 0.
When 32 g, 0.05 g of 1,3-divinyl-1,1,3,3-tetradimethylsiloxane and 0.05 g of potassium siliconate were charged and heated and stirred at 150 ° C. for 3 hours, a raw rubber-like polymer (the following formula: An organopolysilalkylene siloxane represented by (4) was obtained.

[0047]

[Chemical 12]

Next, the following components were kneaded with a kneader,
Heat treatment was performed at a temperature of 120 ° C. for 4 hours.

100 parts by weight of the above polymer 100% by weight of fumed silica (specific surface area 200 m ² / g) 42 〃 diphenylsilanediol 4 〃 Further, 100 parts by weight of the above kneaded product, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
Parts by weight are mixed evenly using a two-roll mill to obtain a composition II
Got I.

A sheet having a thickness of 2 mm was prepared from this composition III in the same manner as the composition I of Example 1.

Example 3 A 1-liter four-necked flask equipped with a stirring bar, a nitrogen introducing tube, a thermometer and an exhaust tube was used, and the silalkylene siloxane 300 represented by the above formula (3) was used.
g, the diorganosiloxane of the above formula (2) 0.
When 44 g, 1,3-divinyl-1,1,3,3-tetradimethylsiloxane 0.06 g and potassium siliconate 0.06 g were charged and heated and stirred at 150 ° C. for 3 hours, a raw rubber-like polymer (the following formula: An organopolysilalkylene siloxane represented by (5) was obtained.

[0052]

[Chemical 13]

Next, the following ingredients were kneaded with a kneader,
Heat treatment was performed at a temperature of 120 ° C. for 4 hours.

100 parts by weight of the above polymer 100 parts by weight of fumed silica (specific surface area 200 m ² / g) 40 〃 diphenylsilanediol 4 〃 Further, 100 parts by weight of the above kneaded product, 2,5-dimethyl-
2,5-bis (t-butylperoxy) hexane 0.4
Parts by weight are evenly mixed using a two-roll mill to obtain a composition IV
Got

A sheet of Composition IV having a thickness of 2 mm was prepared from this Composition IV by the same method as that of Composition I of Example 1.

When the physical properties of the sheets obtained in Examples 3 and 4 were examined, the results shown in Table 2 were obtained.

[0057]

[Table 2]

From the results shown in Table 2, it was confirmed that the silicone rubber compositions of the present invention (Examples 3 and 4) gave cured products having high strength and high tear strength.

Front Page Continuation (72) Inventor Takashi Matsuda 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (2)

[Claims] 1. (A) an organopolysilalkylene siloxane represented by the following general formula (I): A silicone rubber composition comprising (B) a filler and (C) a curing agent. 2. A cured product obtained by curing the silicone rubber composition according to claim 1.