JPH03250051A - Thermally curable organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in the storage stability around room temp. and the properties after being cured by compounding an organopolysiloxane, an organohydrogenpolysiloxane, a particulate material of a silicone resin, etc., and a carboxylic acid salt, 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 the 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 a carboxylic acid salt, silanolate, or beta-diketonate of a metal other than those of the groups IA and IIA.

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 has excellent heat resistance after curing. The present invention relates to a heat-curable silicone elastomer composition that can be made into an elastomer molded article. [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 as a release coating material for paper, film, etc. However, this type of organopolysiloxane composition has a problem in that it has poor storage stability near room temperature, and in particular, its pot life is extremely short when trying to obtain a composition that hardens rapidly. 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 agglomerates, giving an unfavorable appearance and, in particular, significantly reducing the mechanical strength of elastomer molded products. [Problems to be Solved by the Invention] As a result of intensive studies aimed at solving the above problems, the present inventors found that if a specific metal compound is added to the organopolysiloxane composition, the cured elastomer molded product will last longer. This research was accomplished by discovering that the resin used for granulation does not aggregate even after being heated for a long time. The purpose of the present invention is to provide an elastomer molded product with excellent storage stability near room temperature, and to prevent the formation of aggregates and reduce the degree of decrease in mechanical strength even when the elastomer molded product is heated for a long time after being heat-cured. An object of the present invention is to provide a heat-curable organopolysiloxane composition having the characteristic of having a small size. [Means for Solving the Problems and Their Effects 1] The present invention has the following: (^) average composition formula R, SiO+4-111 i□ (wherein R is a substituted or unsubstituted monovalent hydrocarbon group, 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, (D) carvone of a metal element other than Group IA or Group IIA A heat-curable organopolysiloxane composition comprising a compound selected from acid salts, silanolates, and β-diketonates. The organopolysiloxane (A) component used in the present invention is a main component of the composition of the present invention, and has an average unit formula of Ra5iO (4-111/z), and
It is necessary to have at least two silicon-bonded alkenyl groups in one molecule. 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, an allyl group, a hexenyl group, or a phenyl group. It is a monovalent hydrocarbon group exemplified by an aryl group such as a group, a substituted hydrocarbon group such as 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. There are 11 organic groups in one molecule! It may be used alone, or 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 homopolymer or copolymer thereof or a mixture of a polymer having a length of 2 m or more 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 amount is such that the molar ratio of silicon-bonded hydrogen atoms in this component to silicon-bonded alkenyl groups in component (A) is preferably in the range of 0.5/1 to 10/1. and usually 0 parts per 100 parts by weight of component (A).
．． It is within the range of 1 to 10 parts by weight. The particulate material made of the drosilylation reaction catalyst of component (C) and a silicone resin or polysilane resin crosslinks the silicon-bonded alkenyl group of component (A) and the silicon-bonded hydrogen atom of 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 hydrosilylation catalytic activity can be used. Specifically, examples include 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 (triphenylphosphine). ) A palladium-based catalyst such as palladium or a rhodium catalyst is exemplified. Among these, platinum is preferred due to its high activity and compatibility with components (A) and (B).
Vinyl siloxane catalysts are preferred. 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 surface tension, and can be easily determined by observing crushed particles under a microscope while increasing the temperature at a constant rate. The glass transition point can be determined by measurement using a DSC (differential scanning calorimeter). In the present invention, either the softening point or the glass transition point is 40
It can be used within the range of ~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, coacervage method, submerged drying method, and vapor phase drying method. physical, such as
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 within the range of 0.01 to 500 μl, preferably within the range of 0.1 to 10 μl. This is because if the average particle diameter becomes smaller than 0.01 μm, the yield during production will decrease significantly;
This is because if the amount exceeds 00 μl, the dispersion stability of component (A) in diorganopolysiloxane may be impaired or the mechanical properties of the cured product may be reduced. Also, this (C)
Preferably, the shape of the component is spherical. The ratio of the hydrosilylation reaction catalyst to the silicone resin or polysilane resin varies greatly depending on the method of manufacturing the granules, so it cannot be particularly limited.
It is desirable that the content of the hydrosilylation reaction catalyst in component C) be 0.011 or more. This is because if it is less than 0.01%, the proportion of silicone resin or polysilane resin in the composition of the present invention becomes too high, and the physical properties after curing may be impaired. The amount of such component (C) is usually within the range of 0.000001 to 0.1 part by weight in terms of platinum per 100 parts by weight of the organopolysiloxane of component (A),
Preferably it is within the range of o, ooooot to 0.01 parts by weight. The amount of component (C) itself is 0,0
Although it is used within the range of 0.05 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 silicone resin or polysilane resin constituting component (C) from agglomerating when the molded article after heating and curing is left in a heated state for a long time. Component (D) is a compound selected from carboxylates of metal elements other than Group IA and Group IIA, silanolates, and β-diketonates. Examples of metal elements include rare earth metals such as cobalt, manganese, lead, copper, iron, zirconium, chromium, tin, nickel, aluminum, vanadium, cerium, and lanthanum. These metals include carboxylates such as octylic acid and naphthylic acid,
It is necessary to add it to the composition as a β-diketonate or silanolate. The blending amount of component (D) is usually (
A) The metal element is in the range of 0.0001 to 0.1 part by weight per 100 parts by weight of the organopolysiloxane component,
Preferably it is in the range of 0.0005 to 0.1 iti parts. In the present invention, if the weight is less than 0.0001, the effect of preventing agglomeration of the resin constituting the granules can be achieved when the cured elastomer molded product is left in a heated state for a long time. This is because if the amount exceeds 1 part by weight, the heat resistance of the organopolysiloxane (A) component will be impaired, and the molded product will have poor appearance such as significant coloring. 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 (C) component used, but at least (C)
) It is desirable that the temperature be below the softening point of the thermoplastic resin used in the component. The 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, and can be used as an elastomer molded article after heat-curing. Even if the particles are 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 vinylsiloxane complex 160 g of 1,3-divinyltetramethyldisiloxane and 32.0 g of chloroplatinic acid ()12Ptcls.6H
zO) 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 vinylsiloxane complex in which 1°3-divinyltetramethyldisiloxane was coordinated with chloroplatinic acid. . The platinum-gold IE concentration in this reaction product was 4.25% by weight. Reference Example 2 Preparation of silicone resin fine particles containing platinum catalyst 112 mol
A silicone resin composed of diphenylsiloxane units of , 21 moles of dimethylsiloxane units, and 67 moles of monophenylsiloxane units (softening point: 110°C)
16.0 g and 2.0 g of the platinum vinyl siloxane complex 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 [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 suspension by centrifugation. Next, this solid material was washed with water and then with a large amount of methyl alcohol to obtain platinum catalyst-containing silicone resin fine particles having a platinum metal content of 0.21 weight. The average particle diameter of the fine particles was 7 μl, 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 silicone resin fine particles having a diameter of 10 μl and a platinum content of 0.27% by weight 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 add 3-divinyltetramethyldisiloxane to 70-80 g while stirring in suspension.
The reaction was carried out at 0°C for 60 minutes. Isopropyl alcohol and water were removed by volatilization under conditions of a pressure of 50 mmHg, 2W and 45°C, and the solid content was filtered to prepare a platinum catalyst solution y4 having a platinum content of 8.5 weight units. Meanwhile, 1000 g phenyltrichlorosilane, 160 g
After hydrolysis of a solution of 330 g of dimethyldichlorosilane and 330 g of diphenyldichlorosilane diluted with 500 g of toluene, the organic phase was separated after removing the hydrogen chloride and then 0.6 g of potassium hydroxide was added. After adding and heating, the generated water was distilled off, 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 were placed in a glass stirring container.
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. This solution was then transferred to a spray dryer tank (Ashizawa Nitro,
The mixture was continuously sprayed into an atomizer (manufactured by Co., Ltd.). 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 by a van filter. The average particle diameter of this fine particle is 1.1 μl,
Its shape was spherical. In addition, the platinum metal content is 0,
It was 40% by weight. Example 1 After thoroughly mixing 20 g of fumed silica hydrophobized with hexamethyldisilazane into 100 g of α,ω-divinylpolydimethylsiloxane with a viscosity of 1500 cp,
The average molecular formula is )le3s iO(MezSiO) 3 (MeHS
iO) 6S 1ce3 2.8 g of the siloxane shown and 0.01 g of phenylbutynol were added and mixed uniformly. To 100 parts by weight of this composition (referred to as Composition-1), a predetermined amount of the metal compound shown in Table 1 was added, and to each was further added 0.25 MIk part of the platinum catalyst-containing silicone resin fine particles obtained in Reference Example 2. A heat-curable organopolysiloxane composition was obtained by adding and mixing. These compositions were cured under pressure at 130° C. for 5 minutes to obtain sheets with 2II additional thickness. After this sheet was heated in a hot air circulation oven at 250° C. for 3 days, it was visually observed to determine whether silicone resin aggregates were formed in the rubber. The results are shown in Table 1. For comparison, a heat-curable organopolysiloxane composition was obtained in the same manner as above except that no metal compound was added. Regarding this composition, the presence or absence of formation of aggregates was observed in the same manner as above. The results are also listed in Table 1.

[•] The numbers in the table indicate the weight parts added as metal atoms based on 10,000 weight parts of Composition-1. Example 2 In Example 1, the compounds shown in Table 2 were used instead of the metal compounds shown in Table 1, and the platinum catalyst obtained in Reference Example 3 was used instead of the platinum catalyst-containing silicone resin fine particles. A thermosetting organopolysiloxane composition was prepared in the same manner as in Example 1, except that 0.50 g of polysilane resin fine particles were used. These compositions were evaluated in the same manner as in Example 1, and the results are shown in Table 2. Table 2: Addition of metal compounds and formation of aggregates 1.
The numbers in Table 1 indicate the parts by weight of metal atoms added to 10,000 parts by weight of Composition-1. Example 3 100 parts by weight of organopolysiloxane raw rubber (degree of polymerization 5000) consisting of 99.8 mol% dimethylsiloxane units and 0.2 mol% methylvinylsiloxane units, dimethylsiloxane endblocked with silanol groups at both ends (viscosity 60c)
p) 8.0 parts and 40 parts by weight of fumed silica having a specific surface M2O0tr2/g were put into a kneader mixer and kneaded under heating until uniform. For 100 parts of this rubber base, the average molecular formula is Mo
f, sio 04eaSiO) S (MeHS i
O) After adding and mixing the compounds shown in Tables 3 and 4 to 0.40 parts of the siaxane represented by as 1dea, 0.04 parts of the platinum catalyst-containing silicone resin fine particles obtained in Reference Example 2 were added to each of the compounds shown in Tables 3 and 4. and 0.001 part of 1-ethynyl-1-cyclohexanol were mixed to prepare a heat-curable organo-boxy Oxa2 composition. These compositions were evaluated in the same manner as in Example 1. Furthermore, regarding the compositions in Table 3, JIS 630
The mechanical properties of the rubber immediately after curing and after heating were measured using a method based on 1. In the measurement, a heat-curable organopolysiloxane composition was cured under heating at 170° C. for 5 minutes to prepare a sheet with a thickness of 2 mm, and the measurement was performed on this sheet. These results are shown in Tables 3 and 4. Table 3: Amount of metal compound added (a), formation of aggregates, and physical properties The numbers for metal compounds in the table are gold for rubber base 10,000 heavy parts! 1 indicates the amount added in parts by weight as atoms. Table 4: Amount of metal compound added (a) and formation of aggregates
The numbers in Table 1 indicate the number of parts by weight of gold IA added to 10,000 parts by weight of Composition-1. Example 4 For 100 parts of the rubber base prepared in Example 3, the average molecular formula was: )1e+siO(MezSiO)3()IeHSiO)
0.2 to 0.40 parts of siloxane indicated by asiMes
After adding and mixing 0 parts of cerium silanolate (dimethylsiloxane solution containing 20 parts by weight of cerium), platinum catalyst-containing silicone resin fine particles obtained in Reference Example 4 were added.
．． A heat-curable organopolysiloxane composition was prepared by mixing 0.04 parts of 1-ethynyl-1-cyclohexanol and 0.001 parts of 1-ethynyl-1-cyclohexanol. In addition, for comparison, a heat-curable organopolysiloxane composition was prepared in exactly the same manner except that cerium silanolate was not added. For these compositions, the mechanical properties of the rubber immediately after curing and after heating were measured in the same manner as in Example 3 using a method based on JIS 6301. These results are shown in Table 5. Table 5 [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 (D)
It has excellent storage stability near room temperature, and does not cause aggregates to form when the elastomer molded product is heated for a long time after being heat-cured, resulting in a decrease in mechanical strength. It is characterized by a small degree of

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. (D) A heat-curable organopolysiloxane composition comprising: (D) a carboxylate, silalate or β-diketonate of a metal element other than Group IA or Group IIA. 2. The heat-curable ornopolysiloxane composition according to claim 1, wherein the metal element other than Group IA and Group IIA is cerium, cobalt, manganese, zinc, iron, or zirconium. 3. The heat-curable organopolysiloxane composition according to claim 1, wherein the silanolate of a metal element other than Group IA and Group IIA is cerium silanolate.