JPH03250052A - Thermally curable organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in the storage stability around room temp. and properties after being cured by compounding an organopolysiloxane, an organohydrogenpolysiloxane, a particulate material of a silicone resin, etc., and an oxide, etc. CONSTITUTION:The title compsn. is prepd. by compounding: an organopolysiloxane having a mean compsn. shown by the formula (wherein R is an optionally substd. monovalent hydrocarbon group; and (a) is 1.8-2.3) and at least two alkenyl groups directly attached to silicon atoms in the molecule; an organohydrogenpolysiloxane having at least two hydrogen atoms directly attached to the silicon atoms in the molecule; a particulate material comprising a hydrosilylation catalyst and a silicone or polysilane resin having a softening or glass transition point of 40-200 deg.C; and a compd. comprising an oxide or hydroxide of a metal other than that of the group IA and IIA or a carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a heat-curable organopolysiloxane composition, and more specifically, it has excellent storage stability and rapid heat-curing properties near room temperature, and The following is related to K (a heat-curable silicone elastomer composition that can be made into an elastomer molded article with excellent thermal properties).

[Prior art and its problems] An organopolysiloxane composition that is cured by a hydrosilylation reaction is characterized in that it does not produce reaction by-products and is rapidly cured to the depths.
Molded rubber, adhesives, botting agents for electrical and electronic parts,
It is used in a wide range of fields, including as a coating material and a release coating material for paper, film, etc.

However, this type of organopolysiloxane composition has the drawback of poor storage stability near room temperature, and particularly when attempting to obtain a rapidly curing formulation, the pot life is extremely short.

The present inventors have previously proposed an organopolysiloxane composition that solves these problems, using a silicone resin or polysilane particles containing a hydrosilylation reaction catalyst as a curing catalyst. However, although this composition has excellent storage stability near room temperature, if the elastomer molded product after heat curing is heated for a long time, the silicone resin or polysilane resin will deteriorate.
There was a problem in that they agglomerated to form aggregates, and in particular, the mechanical strength of elastomer molded products was significantly reduced.

[Problems to be Solved by the Invention] As a result of intensive studies to solve the above problems, the present inventors found that if a specific metal compound is added to the organopolysiloxane composition, a cured elastomer molded article can be formed. The present invention was achieved by discovering that the resin used for the granules does not aggregate even when heated for a long time.

The object of the present invention is to have excellent storage stability near room temperature, to cure quickly when heated, and to prevent the formation of aggregates even when the heat-cured elastomer molded product is heated for a long time. The first object of the present invention is to provide a heat-curable organopolysiloxane composition which is characterized by a small degree of decrease in mechanical strength.

[Means for Solving the Problems and Their Effects 1 The present invention has the following features: (A) average composition formula RmSiO+4-al/2 (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group, and a is 1.8
~2.3) and having at least two silicon-bonded alkenyl groups in one molecule; (B) having at least two silicon-bonded hydrogen atoms in one molecule; Organohydrodiene polysiloxane, (C) Granules made of a hydrosilylation reaction catalyst and a silicone resin or polysilane resin with a softening point or glass transition point of 40 to 200°C, CD) Oxides of metal elements other than Group IA and Group IIA Alternatively, the present invention relates to a heat-curable organopolysiloxane composition comprising hydroxide or carbon black.

The organopolysiloxane (A) component used in the present invention is a main component of the composition of the present invention, and is represented by the average unit formula or Ra5i014-Ill y□, and has at least It is necessary to have two silicon-bonded alkenyl groups. In the above formula, R is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, an alkenyl group such as a vinyl group, a furyl group, a hexenyl group, a phenyl group, etc. is a monovalent hydrocarbon group exemplified by a substituted hydrocarbon group such as an aryl group or a 3,3°3-trifluoropropyl group, and a is a number from 1.8 to 2.3. The molecular structure of this organopolysiloxane is linear,
It may also have a branched siloxane skeleton. Although the degree of polymerization is not particularly limited, those having a viscosity at 25° C. of 10 to 1,000,000,000 centivoice are usually used.

The organohydrodiene polysiloxane used in the present invention as the component (B) is a crosslinking agent for the organopolysiloxane as the component (A). It is necessary to have at least two silicon-bonded hydrogen atoms. Examples of the organic group bonded to the silicon atom other than the hydrogen atom include the same organopolysiloxane as component (A) described above. Only one type of organic group may be present in one molecule, and
Two or more types may be mixed.

The molecular structure of this organohydrodiene polysiloxane may include a linear structure, a network structure, or a three-dimensional structure, and a single polymer or copolymer thereof or a mixture of two or more types of polymers can also be used. . The degree of polymerization of this organohydrodiene polysiloxane is usually 25°C.
The viscosity is in the range of 0.5 to 50,000 centiVoice, preferably in the range of 1 to 10,000 centiVoice.

In addition, the blended jujube is used in an amount such that the molar ratio of the silicon-bonded hydrogen atoms in this component to the silicon-bonded alkenyl groups in component (A) is preferably in the range of 0.5/1 to 10/1. It is usually in the range of 0.1 to 10 parts by weight per 100 parts by weight of component (A).

The particulate material made of the hydrosilylation reaction catalyst and silicone resin or polysilane resin as the component (C) crosslinks the silicon-bonded alkenyl group of the component (A) and the silicon-bonded hydrogen atom of the component (B) by a hydrosilylation reaction. It is a catalyst for The purpose of such granules is to isolate the contained catalyst for the hydrosilylation reaction from components external to the granules. Therefore, even if the hydrosilylation reaction catalyst is dissolved or dispersed in the particulate silicone resin or polysilane resin, the hydrosilylation reaction catalyst is contained as a core in the shell of the particulate silicone resin or polysilane resin. Particles with a similar structure, so-called microcapsules, can also be used for the purpose of the present invention.

As the catalyst for the hydrosilylation reaction, all conventionally known transition metal catalysts exhibiting vitrosilylation catalytic activity can be used. Specifically, chloroplatinic acid, alcohol-modified chloroplatinic acid, complexes of platinum and olefins, platinum supported on alumina, silica, carbon black, etc., platinum-based catalysts such as platinum black, and tetrakis ( Examples include palladium-based catalysts such as (phenylphosphine) palladium, or rhodium catalysts. Among these, platinum-vinylsiloxane complex catalysts are preferred from the viewpoint of high activity and compatibility with components (A) and (B). Component (C) is such a hydrosilylation reaction catalyst granulated with a silicone resin or polysilane resin whose softening point or glass transition point is within the range of 40 to 200°C. The softening point is the temperature at which the resin starts to flow due to its own weight or its own surface tension.
This can be easily determined by observing the crushed particles with a mirror. The glass transition point is determined by DSC (Differential
This can be determined by measurement using a scanning calorimeter. In the present invention, it can be used as long as either the softening point or the glass transition point is in the range of 40 to 200°C. If the softening point or glass transition point is lower than 40°C, the storage stability of the composition will be significantly reduced, and if it is higher than 200°C, a sufficient heat curing rate will not be obtained.

Methods for granulating the hydrosilylation reaction catalyst with silicone resin or polysilane resin include conventionally known chemical methods such as interfacial polymerization method and 1n-situ polymerization method, core cell basis method, submerged drying method, and vapor phase drying method. physical, such as law;
There are mechanical methods, and any method may be used in the present invention. Among these, the submerged drying method and the vapor phase drying method are preferable because granules with a narrow particle size distribution can be obtained relatively easily. The granules obtained by these methods can be used as they are as component (C), but it is also possible to wash them with an appropriate cleaning solvent to remove the hydrosilylation reaction catalyst attached to the surface. It is desirable to obtain heat-effect organopolysiloxane compositions that are storage stable. A suitable cleaning solvent here is one that does not dissolve the silicone resin or polysilane resin, but has the property of dissolving the hydrosilylation reaction catalyst. Examples of such cleaning solvents include alcohols such as methyl alcohol and ethyl alcohol, and low molecular weight organopolysiloxanes such as hexamethyldisiloxane.

The average particle diameter of component (C) is usually 0.01 to 500ti
i, preferably within the range of 0.1 to 10 μm. This is because if the average particle diameter becomes smaller than 0.01μI, the yield of the hydrosilylation reaction catalyst will decrease significantly during production. This is because the stability may be impaired or the mechanical properties of the cured product may be reduced. Moreover, it is preferable that the shape of this (C) component is spherical.

The ratio of the hydrosilylation reaction catalyst to the silicone 444 resin or polysilane resin varies greatly depending on the manufacturing method of the granules, so it may not be possible to limit it to Samurai, or the content of the hydrosilylation reaction catalyst in component (C). It is desirable that the ratio is 0.01% or more. This is because if it is less than 0.01%, the proportion of silicone 414 resin or polysilane resin in the composition of the present invention becomes too high, and the physical properties after curing may be impaired. The blending amount of such component (C) is usually
It is within the range of 0.000001 to 0.1 part by weight in terms of platinum, and preferably within the range of o, oo oos to 0.01 part by weight, based on 100 parts by weight of the organopolysiloxane of component (A). (C) The blending amount of the component itself is o,
Although it is used within the range of oos to 100 parts by weight, it may be used in an amount exceeding this range as long as it is within the above range of parts by weight in terms of platinum. In addition, in the case of a transition metal other than platinum, the platinum equivalent weight means the weight calculated assuming that the same number of atoms of platinum as the transition metal to be blended is blended.

Component (D) plays a role in preventing the cyanocone resin or polysilane resin constituting component (C) from agglomerating when the molded article after heat curing is left in a heated state for a long time. Component (D) is an oxide or hydroxide of a metal element other than Group IA or Group IIA, or carbon black.

Examples of metal elements other than Group IA and Group IIA include rare earth metals such as cobalt, manganese, zinc, copper, iron, zirconium, chromium, tin, nickel, aluminum, vanadium, cerium, and lanthanum. These metals must be added to the composition as oxides or hydroxides. The blending amount of component (D) is usually (
The amount ranges from 0.01 to 10 parts by weight per 100 parts by weight of the organopolysiloxane component A). In the present invention, if it is less than 0.01 part by weight, the 10-layer plate part can achieve the effect of preventing agglomeration of the resin constituting the granules when the cured elastomer molded product is left in a heated state for a long time. This is because, if it exceeds this amount, the tetrathermal properties of the component (A), surganobolisiloxane, will be impaired, and the mechanical strength of the molded product will be reduced.

The composition of the present invention is an organopolysiloxane composition consisting of the above-mentioned components (A) to (D). finely powdered silica, crepe hardening inhibitors, storage stabilizers such as phenylbutynol, polymers other than organopolysiloxane, heat resistant agents, flame retardants, quartz powder, diatomaceous earth, calcium carbonate, glass fiber, etc. may be used as long as it does not impair the purpose of the present invention.

The composition of the present invention can be easily obtained by uniformly mixing the components (A) to (D) above. There is no particular restriction on the mixing order, but after mixing component (C) into a small amount of component (A) and dispersing it uniformly, this is added to the mixture of (A), (B) and (D). The preferred method is to In this case, any means may be used as long as it does not destroy the granulated hydrosilylation reaction catalyst of component (C).

In addition, the temperature conditions cannot be unconditionally defined because they vary depending on the component (C) used, but at least (
The temperature is desirably below the softening point of the thermoplastic resin used in component C).

The 81 composition of the present invention as described above has excellent storage stability at room temperature, so it can be stored for a long period of time as a one-component heat-curable organopolysiloxane composition, and
Even if the molded article after heating and curing is kept in a heated state for a long time, the resin constituting the particles does not aggregate, and the degree of decrease in mechanical strength is small.

Therefore, it is extremely useful as silicone rubber compositions, silicone gel compositions, and silicone resin compositions that require these properties.

[Example] Next, the present invention will be explained by referring to an example. In the examples, viscosity is the value at 25°C, and Cp represents centivoise.

Reference Example 1 Preparation of platinum vinyl siloxane complex 160 g of 1,3-divinyltetramethyldisiloxane and 32.0 g of chloroplatinic acid (H2PtC1s.6H
20) and heated and mixed at 120° C. for 1 hour in a nitrogen stream.

Next, platinum black produced as a by-product was removed by filtration, and then the acid was removed by washing with water to obtain a reaction product containing a platinum complex in which 1,3-divinyltetramethyldisiloxane was coordinated with chloroplatinic acid. The platinum metal concentration in this reaction product is 4.
It was 25 hours 2.

Reference Example 2 Preparation of Silicone Resin Fine Particles Containing a Platinum Catalyst Silicone resin (softening point: 110°C) consisting of 12 moles of diphenylsiloxane units, 21 mole% of dimethylsiloxane units, and 67 mole% of monophenylsiloxane units
．． 0 g and 2.0 g of the platinum vinyl siloxane complex catalyst obtained in Reference Example 1 were dissolved in 330 g of methylene chloride. This methylene chloride solution was mixed with 15 g of polyvinyl alcohol [Nippon Gosei Kagaku Kogyo special product, Gohsenol GL-
05] into water with stirring. Methylene chloride was then removed by evaporation at 25-40°C over 48 hours. Solid matter was separated from this @fiJ solution by centrifugation. Next, this solid material was washed with water and then with a large amount of methyl alcohol to obtain a platinum content of 0.21% by weight.
Platinum catalyst-containing silicone resin fine particles were obtained. The average particle diameter of the fine particles was 7 μm, and the shape was spherical.

Reference Example 3 Preparation of platinum catalyst-containing polysilane resin fine particles In Reference Example 2, 8.0 g of polysilane resin (softening point 135°C) was used instead of the silicone resin, and the other conditions were the same as in Reference Example 2, so that the average particles were Platinum catalyst-containing polysiloxane resin fine particles having a diameter of 10 μm and a platinum content of 0.27% were obtained.

Reference Example 4 Preparation of silicone resin fine particles containing platinum catalyst 260 g of chloroplatinic acid aqueous solution (platinum content 33%) and 160 g of 1.
Dissolve 3-divinyltetramethyldisiloxane in 350 g of isopropyl alcohol, add 100 g of bicarbonate of soda, and heat the suspension to 70-80°C while stirring.
The reaction was carried out for 60 minutes. A platinum catalyst solution having a platinum content of 8.5 weight X was prepared by removing isopropyl alcohol and water by volatilization under conditions of a pressure of 50 + n + nHg and a degree of A of 45°C, and filtering the solid content.

On the other hand, looog phenyltrichlorosilane, 160
After hydrolysis of a solution of g of dimethyldichlorosilane and 330 g of diphenyldichlorosilane diluted with 500 g of toluene, hydrogen chloride was removed and the organic phase was separated, then 0.6 g of potassium hydroxide was added and heated. After distilling off the generated water, it was neutralized and washing with water was repeated.

Thereafter, the solvent was dried to obtain a thermoplastic silicone resin having a glass transition point of 65°C and a softening point of 85°C.

900 g of this thermoplastic silicone resin, 500 g of toluene, and 4600 g of dichloromethane in a glass container with a stirrer.
g was added and mixed uniformly. Next, 44.4 g of the platinum catalyst solution obtained above was added and mixed to obtain a homogeneous solution of the platinum catalyst and thermoplastic silicone resin.

Next, this solution was continuously sprayed into a swab-dryer tank (manufactured by Ashizawa Nitro Atomy Sea Co., Ltd.) using a two-fluid nozzle and a hot nitrogen gas stream.

Here, the hot air flow temperature of nitrogen gas is 95°C at the inlet of the spray dryer, and 45°C at the outlet of the spray dryer.
It was ℃. After one hour of operation, 450 g of platinum catalyst-containing silicone resin fine particles were collected using a bag filter. The average particle diameter of these fine particles is 1. ILljll, and its shape was spherical. Further, the platinum metal content was 0.40% by weight.

Example 1 100 parts by weight of organopolysiloxane raw rubber (degree of polymerization 5000) consisting of 99.8 mol χ of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units, dimethylsiloxane endblocked with silanol groups at both ends (viscosity 60)
8.0 parts of c p ) and 40 parts by weight of fumed silica having a specific surface area of 200 nz/g were placed in a kneader mixer and kneaded under heating until uniform. This rubber base 1
For the 00 jujutsu part, the average molecular formula is Me3SiO(Me2SiO)3(HeHSiO) a
0.30 parts by weight of siloxane represented by siHe3
After adding and mixing the metal compound and carbon blank in the weight parts shown in the table, 0.04 weight part of the platinum catalyst-containing silicone resin fine particles obtained in Reference Example 2 and 1-ethynyl-1-cyclo A heat-curable organopolysiloxane composition was prepared by mixing 0.001 part by weight of hexanol.

These compositions were cured under pressure at 130°C for 5 minutes to produce a sheet with a thickness of 2IIIN. 20 sheets of this
After vulcanization at 0°C for 2 hours, it was heat-treated in a hot air circulation oven at 250°C for 3 days. The obtained sheet immediately after heating and the sheet after heat treatment were observed using a microscope to determine whether aggregates of silicone resin fine particles were formed in the rubber. In addition, the mechanical properties of these sheets were determined by JI
The measurement was performed starting from SK6301. For comparison, a heat-curable organopolysiloxane composition was prepared in the same manner as above except that the platinum catalyst-containing silicone resin fine particles were not added and mixed, and the properties of this composition were measured in the same manner as above. These measurement results are also listed in Table 1.

Table 1 Example 2 In Example 1, the additives shown in Table 2 were used instead of the additives shown in Table 1, and the platinum catalyst-containing silicone resin fine particles were replaced with those obtained in Reference Example 3. A heat-curable organopolysiloxane composition was prepared in the same manner as in Example 1, except that 0.05 g of the platinum catalyst-containing polysilane resin fine particles prepared above were used. These compositions were cured under pressure at 130° C. for 5 minutes to produce a sheet with a thickness of 2 ml and 1 m. The properties of these sheets were evaluated in the same manner as in Example 1 below. These results are shown in Table 2.

Table 2 Example 3 After thoroughly mixing 20 g of fumed silica hydrophobized with hexamedyldisilazane into α,ω-divinylpolydimethylsiloxane loog with a viscosity of 1500 cp,
The average molecular formula is EasiO(MezSiO)3()IelSiO)6
2.8 g of siloxane shown as siMe3 and 0.01 g of phenylbutinol were added and mixed uniformly. To 100 parts by weight of this composition (referred to as composition-1), a prescribed amount of metal compounds and carbon platinum as shown in Table 3 was added,
0.25 parts by weight of the platinum catalyst-containing silicone resin fine particles obtained in Reference Example 2 were further added and mixed to each of them to obtain a heat-curable organopolysiloxane composition. These compositions were cured under pressure at 130'C for 5 minutes.
A sheet having a thickness of I111 was obtained. This sheet was heated in a hot air circulation oven at 250° C. for 3 days. These sheets were evaluated in the same manner as in Example 1. The result is the third
Shown in the table.

Table 3 Example 4 In Example 1, instead of the additives shown in Table 1,
The platinum layer v! obtained in Reference Example 1 using the additives shown in the table! A thermosetting organopolysiloxane composition was prepared in the same manner as in Example 1, except that 0.02 parts by weight of the platinum catalyst-containing silicone resin fine particles obtained in Reference Example 4 was used instead of the silicone resin mold particles containing mold. Prepared. These compositions were cured in the same manner as in Example 1, and sheet mechanical properties were measured. The results are shown in Table 4.

Table 4 [Effects of the invention] The heat-curable organopolysiloxane composition of the present invention is as follows:
Consists of components (A) to (D), especially component (C) and (DJ
Because it contains an acid component, it has excellent storage stability near room temperature, and cures quickly when heated, and after heat-curing, the elastomer molded product is not exposed to heat for a long time. It is characterized in that it does not form, and the degree of decrease in mechanical strength is small.

Claims (1)

[Claims] 1 (A) Average compositional formula R_aSiO_(_4_-_a_
)_/_2 (wherein R is a substituted or unsubstituted monovalent hydrocarbon group, a is a number from 1.8 to 2.3), and at least two silicon atom bonds in one molecule An organopolysiloxane having an alkenyl group, (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule, (C) a hydrosilylation reaction catalyst and a softening point or glass transition point of 40 to 200. A heat-curable organopolysiloxane composition comprising a particulate material made of a silicone resin or a polysilane resin at a temperature of 0.degree. 2. The heat-curable organopolysiloxane composition according to claim 1, wherein the metal element other than Group IA and Group IIA is cerium, cobalt, manganese, zinc, iron, zirconium, or titanium.