JP2651836B2 - Organopolysiloxane composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an organopolysiloxane composition having excellent storage stability, and more particularly to an organopolysiloxane composition suitably used for silicone rubber.

[Prior Art] A silicone rubber molded article is obtained by heating and curing a composition comprising an organopolysiloxane raw rubber, reinforcing silica, and an organic peroxide. However,
This method required complicated steps such as mastication and sorting before molding.

For this reason, recently, a silicone rubber composition comprising a silicon atom-bonded vinyl group-containing organopolysiloxane having a relatively low degree of polymerization, a silicon atom-bonded hydrogen atom-containing organopolysiloxane, a reinforcing silica, and a platinum alkenylsiloxane complex (hereinafter, referred to as a “silicon atom-bonded organopolysiloxane”) An addition reaction-curable silicone rubber composition) is heated to accelerate the addition reaction between the silicon atom-bonded vinyl group and the silicon atom-bonded hydrogen atom and to cure the silicone rubber to obtain a silicone rubber molded article. . This method has many advantages such as easy handling of the silicone rubber composition to be used and adoption of an injection molding method having good productivity. Therefore, the use range thereof is steadily expanding.

However, the addition reaction-curable silicone rubber composition is
Since the addition reaction proceeds even at room temperature, it was practically impossible to store it in the same container. Therefore, a two-part composition is usually used. That is, a mixture of a silicon atom-bonded vinyl-containing organopolysiloxane, a reinforcing silica, and a platinum alkenylsiloxane complex is stored in one container as an organopolysiloxane composition for silicone rubber. A mixture of the hydrogen atom-containing organopolysiloxane and the reinforcing silica is stored in a container different from the above as a crosslinking agent composition. Immediately before molding, these compositions are uniformly mixed to obtain a curable silicone rubber composition, which is cured by heating to obtain a molded article.

[Problems to be Solved by the Invention] However, such organopolysiloxane compositions for silicone rubbers have low storage stability, and their viscosity decreases when they are stored for a long period of time. However, there has been a problem that the properties of the silicone rubber may not be obtained due to a change in the catalytic activity of the platinum alkenylsiloxane complex.

The inventor of the present invention has made intensive studies to solve the above problems, and has accomplished the present invention.

An object of the present invention is to provide an organopolysiloxane composition having excellent storage stability, and in particular, to provide an organopolysiloxane composition that can be suitably used as an organopolysiloxane composition for silicone rubber.

Means for Solving the Problems and Action Thereof The present invention provides: (A) 100 parts by weight of an organopolysiloxane having at least two silicon-bonded alkenyl groups in one molecule; (B) fine-particle silica; 100 parts by weight, (C) 0.00001 to 1 part by weight of a platinum alkenylsiloxane complex, and (D) at least one compound represented by the formula (R ¹ is an aryl group and R ² is an alkenyl group.)
Wherein the number of silicon atoms in one molecule is 8 or less.
An organopolysiloxane composition comprising parts by weight. About.

To explain this, the organopolysiloxane of the component (A) used in the present invention is a main component of the composition of the present invention, and it is necessary that one molecule has at least two silicon-bonded alkenyl groups. is there. Examples of such an alkenyl group include a vinyl group, an allyl group, and a propenyl group. Organic groups bonded to silicon atoms other than alkenyl groups in the organopolysiloxane include alkyl groups such as methyl, ethyl, propyl, and butyl; 2-phenylmethyl, 2-phenylethyl, 3 , 3,3-
Examples include a substituted alkyl group such as a trifluoropropyl group; an aryl group such as a phenyl group and a tolyl group; and an alkoxy group. The molecular weight of such an organopolysiloxane is not particularly limited, but the viscosity at 25 ° C is 100 to 300,000.
It is preferably in the range of centipoise, 300 to 10
Those within the range of 0,000 centipoise are more preferred. This organopolysiloxane may be used as a mixture of two or more kinds.

The finely divided silica of the component (B) used in the present invention includes:
It is a silicone rubber reinforcing filler. As is well known, such particulate silica can be roughly classified into two types according to the production method. The first is silica produced by reacting tetrachlorosilane and the like in an oxyhydrogen flame, which is called fumed silica or fumed silica. And is called wet silica. The present invention can use both dry and wet silica,
Generally, wet silica is preferred because it can further stabilize the composition of the present invention. Further, as such fine particle silica, silica whose surface has been treated with a hydrophobizing agent such as dimethylchlorosilane, hexamethyldisilazane, or hexamethylcyclotrisiloxane can also be used.
The amount of the component (B) is 1 to 100 parts by weight of the component (A).
It is in the range of ~ 100 parts by weight. When the amount is less than 1 part by weight, the composition of the present invention does not become a suspension, a paste, or a plastic body, and does not become in an easy-to-use state. Because it is gone.

The platinum alkenylsiloxane complex of the component (C) is a curing catalyst for the composition of the present invention, that is, a hydrosilylation reaction catalyst, and is a platinum complex in which alkenylsiloxa is coordinated with platinum. Such a platinum alkenylsiloxane complex is described in, for example, Japanese Patent Publication No. 42-22924, but is a platinum complex obtained by reacting a halogenated platinic acid or a halogenated platinum salt with an alkenylsiloxane. Any catalyst capable of accelerating the addition reaction, that is, a catalyst having a hydrosilylation reaction catalytic activity, can be used in the present invention. There is no particular limitation on the structure of the alkenyl siloxane used as the raw material of the component (C), but in order to enhance the storage stability of the obtained platinum siloxane complex itself, it is preferable that two or more alkenyl groups are contained in one molecule. More preferably, an alkenyl group is bonded to two adjacent silicon atoms through an oxygen atom. The amount of component (C) is (A)
Platinum metal is preferably in the range of 0.00001 to 1 part by weight based on 100 parts by weight. This is because if the amount is less than 0.00001 part by weight, the effect as a catalyst for the human rosilation reaction cannot be substantially exerted, and if it exceeds 1 part by weight, the cost becomes high and uneconomical.

The organopolysiloxane of the component (D) is a component that characterizes the composition of the present invention, and has at least one compound represented by the formula per molecule. [In the formula, R ¹ is an aryl group such as a phenyl group and a tolyl group, and is preferably a phenyl group. R ² is a vinyl group,
An alkenyl group such as an allyl group or a hexenyl group;
Preferably it is a vinyl group. It is necessary to increase the storage stability of the composition of the present invention without lowering the activity of the platinum alkenylsiloxane complex of the component (C). In addition, this organopolysiloxane needs to have eight or less silicon atoms in one molecule. This is because if the number of silicon atoms exceeds 8, the affinity with the component (A) decreases, and the effect of not lowering the activity of the platinum alkenylsiloxane complex of the component (C) cannot be exerted.

Aryl groups in such organopolysiloxanes,
Examples of the organic group other than the alkenyl group and the oxygen atom include an alkyl group such as a methyl group and a propyl group; a substituted alkyl group such as a 2-phenylmethyl group, a 3,3,3-trifluoropropyl group; and an alkoxy group. . Such organopolysiloxanes include, for example, 1,3-divinyl-1,3-diphenyldimethyldimethylsiloxane, 1,3-divinyl-tetraphenyldisiloxane, 1,3,5-trivinyl-1,3,5
-Triphenyl dimethyltrisiloxane.

The compounding amount of the component (D) is in the range of 0.00001 to 5 parts by weight based on 100 parts by weight of the component (A). This is 0.00001
If the amount is less than 5 parts by weight, the effect of enhancing the storage stability is not exhibited. This is because it occurs.

The composition of the present invention comprises, in addition to the components (A) to (D), an organosilicon compound containing a sufficient amount of silicon-bonded hydrogen atoms to react with and cure the alkenyl group of the component (A); and By adding a hydrosilylation reaction inhibitor, the composition can be used as a one-part silicone rubber composition.

In the composition of the present invention, if necessary, a crepe-hardening inhibitor, a polymer other than the organopolysiloxane,
The compounding of organic solvents, iron oxides, heat-resistant agents such as rare earth compounds, flame retardants such as manganese carbonate, fumed titanium, quartz powder, diatomaceous earth, calcium carbonate, glass fiber, carbon black, etc. This is arbitrary as long as the purpose of is not impaired.

The composition of the present invention can be easily obtained by uniformly mixing the above components (A) to (D). The mixing order is not particularly limited, but it is preferable that the platinum alkenylsiloxane complex of the component (C) is added after the components (A) and (B) are mixed. The polysiloxane of the component (D) may be added at any stage, but it is preferable to add it beforehand to the component (A) or to add it after mixing the components (A) to (C).

The composition of the present invention has remarkably improved storage stability as compared with the conventional composition, and does not increase the viscosity or the addition catalytic activity of the platinum alkenylsiloxane complex even after long-term storage, It can be usefully used as a composition for silicone rubber.

[Examples] Next, the present invention will be described with reference to examples.
The term "part" means "part by weight", and the viscosity indicates a value at 25 ° C.

Reference Example 1 Preparation of platinum vinylsiloxane complex 160 g of 1,3-divinyltetramethyldisiloxane and 3 g
2.0g of chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O) were mixed and heated and mixed for 1 hour in a nitrogen stream 120 ° C.. After removing the by-produced platinum black by filtration, the acid was removed by washing with water to obtain a reaction product containing a platinum vinyl siloxane complex. The platinum concentration in the reaction product was 4.25% by weight.

Example 1 100 parts of dimethylpolysiloxane blocked with dimethylvinylsiloxy groups at both ends having a viscosity of 2,000 centipoise was put into a planetary mixer, and heated until the internal temperature reached 150 ° C. with stirring. To this, 30 parts of [Nip Seal LP, manufactured by Nippon Silica Kogyo Co., Ltd.] was divided into four parts, added over about one hour, and mixed. After charging the silica, the mixture was further heated and mixed under vacuum for 2 hours and then cooled. Next, 8.4 mg of the reaction product of the platinum-vinylsiloxane complex obtained in Reference Example 1 was added and mixed, and 6.0 mg of 1,3-divinyl-1,3-diphenyldimethyldisiloxane was further added and mixed, and the organopolysiloxane was added. A composition was obtained. One part of the obtained composition was put in a plastic container, sealed and aged at 50 ° C. for one month.

Next, 1.4 parts of a methylsiloxane / methylhydrogensiloxane copolymer (content of silicon-bonded hydrogen atoms of 1 part) was added to 100 parts of the composition immediately after mixing and 100 parts of the composition after aging at 50 ° C. for one month. %) And 0.003 part of 3-methylbutynol 1 as a reaction inhibitor were obtained to obtain a curable silicone rubber composition. The viscosity, cured physical properties, and cured silicone rubber physical properties of this composition were measured. These measurement results were as shown in Table 1.

The methods for measuring the curing properties and the physical properties of the silicone rubber after curing are as follows.

Curing property: Curing meter [Curast meter type 3 manufactured by Toyo Boardwin Co., Ltd.]
And heated at 130 ° C., and the time from when the heating was started to when the silicone rubber started to harden (began to exhibit the behavior as an elastic body) was measured, and this was defined as the hardening start time.

Silicone rubber physical properties after curing: The silicone rubber composition is put into a mold and press-vulcanized at 150 ° C. for 5 minutes to obtain a 2 mm thick silicone rubber sheet. About this sheet, JISK
Physical properties were measured according to 6301.

Also, for comparison, 1,3-divinyl-1,3
Table 1 also shows the measurement results of the silicone rubber composition obtained in the same manner as described above except that -diphenyldimethyldisiloxane was not added.

Example 2 In Example 1, a specific surface area of 200 m was used instead of wet silica.
A silicone rubber composition obtained using ² / g of dry silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.) and the other conditions were the same as in Example 1 was measured for various properties by the same method as in Example 1. . These measurement results were as shown in Table 2.

For comparison, the measurement results of the silicone rubber composition obtained in the same manner as above except that 1,3-diphenyldimethyldisiloxane was not added are shown in Table 2.
It is described together.

Example 3 In Example 1, a specific surface area of 120 m was used instead of wet silica.
A silicone rubber composition obtained by using 30 parts of ² / g of hydrophobic wet silica [Nip Seal SS-10 manufactured by Nippon Silica Kogyo Co., Ltd.] and using the same procedures as in Example 1 except for that described in Example 1 was used.
Curing characteristics were measured in the same manner as in the above. The measurement results are as shown in Table 3.

Example 4 In Example 3, 30 parts of hydrophobic dry silica having a specific surface area of 87 m ² / g [Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.] was used in place of the hydrophobic wet silica, and the other parts were the same as in Example 1. With respect to the composition for silicone rubber thus obtained, the curing characteristics were measured by the same method as in Example 1. The measurement results are as shown in Table 4.

[Effects of the Invention] As described above, the organopolysiloxane composition of the present invention is composed of the components (A) to (D), and particularly contains the specific organopolysiloxane of the component (D), so that it is stable in storage. It has the characteristic that the catalytic activity of the platinum alkenylsiloxane complex does not change even after long-term storage.

Claims (1)

(57) [Claims] 1. An organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule.
100 parts by weight, (B) 1 to 100 parts by weight of particulate silica, (C) 0.00001 to 1 part by weight of a platinum alkenylsiloxane complex, and (D) at least one compound represented by one molecule per molecule. (R ¹ is an aryl group and R ² is an alkenyl group.)
Wherein the number of silicon atoms in one molecule is 8 or less.
An organopolysiloxane composition comprising parts by weight.