JPH0248180B2 - GERUJOSOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention has excellent adhesion to base materials such as plastics, rubber, glass, and metals at room temperature or with slight heating, and does not discolor or change physical properties at high temperatures. The present invention relates to a polyorganosiloxane composition capable of forming a stable gel-like material. [Prior Art] Conventionally, various technologies have been known for compositions that can be cured to form gel-like polyorganosiloxanes through an addition reaction between a hydrosilyl group and a silicon-bonded vinyl group.・Widely used as potting materials for electronic devices, encapsulations, and implants in surgical procedures. Regarding such a polyorganosiloxane composition, JP-A-48-17847 discloses that the amount of hydrogen atoms bonded to the silicon atom is one or less per vinyl group bonded to the silicon atom, and The average amount per molecule of organohydrodiene siloxane
A composition in which an amount corresponding to 1.4 to 1.8 is present,
Also, JP-A-54-15957 and JP-A-54-48720
In the publication, the amount of hydrogen atoms per vinyl group is
A composition in which a relatively small amount of around 0.3 to 0.8 is present is disclosed, and as a vinyl group-containing polyorganosiloxane, JP-A-54-15957 discloses polydimethylsiloxane end-capped with methylvinylphenylsiloxy groups. , Japanese Patent Publication No. 54-48720
The publication proposes the use of a polysiloxane containing in one molecule at least two vinyl groups and one hydroxyl group bonded to silicon atoms. However, such compositions that can be cured into a gel-like state or gel-like products obtained therefrom have the following drawbacks in common. Due to its low adhesiveness, it does not adhere to the base material, and when used for potting electronic equipment parts, gaps may be created between the parts and the gel-like material, through which moisture may enter, causing corrosion or poor insulation. Become. Since the vinyl groups remaining in the gel-like material are oxidized at high temperatures, it has poor heat resistance in an oxidizing atmosphere. Since the amount of polyorganohydrodiene siloxane in the composition is small, errors in blending the siloxane or the mixture containing it during blending immediately before curing can cause a significant difference in the softness of the gel-like product. The methylvinylphenylsiloxy terminal group as shown in JP-A-54-15957 is difficult to synthesize. [Problems to be solved by the invention] In order to solve these problems,
Publication No. 143241 basically discloses a composition in which the hydrogen atoms are present in an amount of 0.5 to 5 per vinyl group, thereby almost solving the above problems. However, this composition often undergoes discoloration at high temperatures, resulting in a decrease in light transmittance, which has caused a problem in that its range of use in optical applications is somewhat limited. [Means for Solving the Problems] The present invention eliminates these drawbacks and provides a polyorganosiloxane composition that has excellent adhesion to substrates and can be cured into a stable gel-like material without discoloration at high temperatures. It is something to do. As a result of studying compositions that solve these problems, the present inventors determined that the amount of effective hydrogen in the polyorganohydrodiene siloxane was set to 0.5% by weight or less, and the amount of the catalyst was adjusted to 0.5% by weight or less. 0.01~ as the amount of element
It was discovered that the objective could be achieved by setting the content to 30 ppm, and the present invention was completed. That is, the present invention provides (A) an average of 0.1 to 2.0 vinyl groups bonded to the silicon atom in one molecule, and the remaining organic groups bonded to the silicon atom are substituted or unsubstituted vinyl groups that do not contain aliphatic unsaturation. Polyorganosiloxane (B), which is a monovalent hydrocarbon group and has a viscosity of 50 to 100,000 cP at 25°C.There are more than 2 hydrogen atoms bonded to silicon atoms in one molecule on average, and the effective hydrogen amount is 0.5 Polyorganohydrodiene siloxane with a weight percent or less of hydrogen atoms bonded to silicon atoms (A)
and (C) a catalyst selected from the group consisting of a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst; (B)
0.01~ as the amount of catalytic metal element relative to the total amount of
The present invention relates to a gel composition characterized in that the amount is 30 ppm. The polyorganosiloxane as component (A) used in the present invention has an average of 0.1 to 2.0, preferably 0.1 to 1.4 vinyl groups bonded to silicon atoms in one molecule. When the amount of vinyl groups is less than 0.1, the amount of polyorganosiloxane that does not take part in crosslinking increases, and the physical properties of the gel-like product obtained by curing and the adhesion to the substrate are significantly reduced. Furthermore, if the amount of vinyl groups is more than 2.0, the feature of the present invention, which is to obtain a soft gel-like material that does not discolor at high temperatures, cannot be exhibited. Among the organic groups bonded to the silicon atom of the polyorganosiloxane (A), those other than the vinyl group mentioned above include methyl group, ethyl group, propyl group, butyl group, amino group, hexyl group, octyl group, decyl group. group, alkyl group such as dodecyl group, aryl group such as phenyl group, aralkyl group such as β-phenylethyl group, β-phenylpropyl group, and chloromethyl group, cyanoethyl group, 3,
Substituted hydrocarbon groups such as 3,3-trifluoropropyl groups are examples, but methyl groups are preferred because of their ease of synthesis, ease of handling in an uncured state, and the heat resistance and physical properties of gel-like products. It is preferable that In addition, phenyl may contain up to 8 mol% of all organic groups when cold resistance is required, and up to 50 mol% of all organic groups when particularly high heat resistance, radiation resistance, or high refractive index is required. It is recommended to introduce groups. Viscosity is 50~100000cP at 25℃,
Preferably, it is selected from the range of 300 to 5000 cP. When used for potting, a range of 500 to 1500 cP is most preferred. If it is lower than 50cP, it will flow easily and the physical properties after reaction will be poor. Also
If it exceeds 100000cP, workability will deteriorate. The siloxane skeleton of the polyorganosiloxane (A) may be linear or branched, or may be a mixture of both, but from the viewpoint of ease of synthesis and imparting appropriate softness to the gel-like material, Preferably, it is linear. It is acceptable for a small amount of cyclic polyorganosiloxane to coexist, but even if it has a vinyl group bonded to a silicon atom, its reactivity is low and it does not contribute to the formation of a sticky gel. The vinyl group in polyorganosiloxane may be bonded to either a silicon atom in the middle of the molecule or a silicon atom at the end of the molecule, but due to the reaction rate and the effect of forming a gel-like substance by the reaction, it is preferable to bond to the silicon atom at the end of the molecule. It is preferable to do so. Such polyorganosiloxane (A) is made of, for example, a vinyl group-containing polyorganosiloxane that has vinyl groups bonded to silicon atoms at both ends, and a linear or branched polyorganosiloxane that does not contain vinyl groups. If available, it is blended with a polyorganosiloxane that does not contain vinyl groups to satisfy the average molecular weight and the amount of vinyl groups that achieve the above-mentioned viscosity range, and an acid catalyst such as sulfuric acid, hydrochloric acid, activated clay, or potassium hydroxide. It is synthesized by cutting and equilibrating siloxane using conventional methods in the presence of an alkali catalyst such as tetramethylammonium hydroxide. In this case, a cyclic polysiloxane, particularly a cyclic polysiloxane containing no vinyl group, may be used in combination as part of the raw material. After equilibration,
The catalyst is removed by a conventional method, and by-product or unreacted low-molecular-weight polyorganosiloxane is removed and purified by heating under reduced pressure. The polyorganohydrodiene loxane used in the present invention, component (B), reacts with the vinyl group of the polyorganosiloxane (A) to form a gel-like substance, and the silicon atoms in (A) In order to form a loose network structure by reacting with a polyorganosiloxane containing two or more vinyl groups to be bonded, the number of hydrogen atoms bonded to silicon atoms is present in an average of more than two in one molecule. Must.
Furthermore, in order to improve heat resistance, which is the objective of the present invention, and in particular to prevent discoloration of the gel-like material at high temperatures, the effective weight must be 0.5% by weight or less. Here, the effective hydrogen amount is a value expressed as a percentage obtained by dividing the number of hydrogen per molecule by the number of molecular weights. When the amount of effective hydrogen is more than 0.5% by weight, the discoloration of the gel material at high temperatures increases. Such a hydrogen atom may be bonded to any silicon atom at the end of the molecule or in the middle of the molecule. The organic group bonded to the silicon atom in (B) is exemplified by the same organic groups listed as organic groups other than vinyl groups among the organic groups bonded to the silicon atom in (A), but it is easy to synthesize. A methyl group is preferable from the viewpoint of the heat resistance of the gel-like material obtained. The siloxane skeleton may be linear or branched, but linear is preferred because it is easy to synthesize and provides good physical properties to the resulting gel. The viscosity of component (B) is not particularly limited, but from the viewpoint of workability and ease of synthesis,
A range of 10000 cP is preferred. The blending amount of component (B) is preferably 1 to 5 hydrogen atoms to be bonded to the silicon atom in component (B) for each vinyl group bonded to the silicon atom in component (A).
The amount is 1.0 to 1.5. If the amount of hydrogen atoms bonded to a silicon atom is less than one, crosslinking will not proceed sufficiently and the gel-like material will not only become too soft, but also become noticeably discolored at high temperatures. Further, even if the amount of hydrogen atoms exceeds 5, the gel-like material becomes hard over time. The catalyst of component (C) used in the present invention is for promoting the addition reaction between the vinyl group of component (A) and the hydrosilyl group of component (B), and is a catalyst of chloroplatinic acid, alcohol-modified platinum chloride, etc. Acids, platinum-based catalysts such as complexes of platinum and olefins, complexes of platinum and ketones, complexes of platinum and vinylsiloxane, tetrakis(triphenylphosphine)palladium, and combinations of palladium black and triphenylphosphine. Palladium-based catalysts or rhodium-based catalysts, such as mixtures, can be used. Platinum-based catalysts are preferred because of their catalytic effect and ease of handling. (C)
The blending amount of the components is such that the amount of the catalytic metal element is in the range of 0.01 to 30 ppm based on the total amount of (A) and (B). If it is less than 0.01 ppm, the addition reaction will not proceed sufficiently and the gel will become too soft.
If it exceeds 30 ppm, discoloration at high temperatures will become significant and the features of the present invention will not be exhibited. The compositions of the present invention may be stored in a single container by the presence of a reaction inhibitor such as an acetylenic compound or by using a platinum-based catalyst with low activity at room temperature. Store (B) in the same container and (C) in a separate container, or store a part of (A) in combination with (B), or most of (A) with (C) in separate containers, and store them immediately before hardening. It may be used after uniformly mixing and defoaming under reduced pressure. Further, by adding an inorganic filler to the composition of the present invention as needed, workability, hardness after curing, mechanical strength, etc. can be adjusted depending on the application. Examples of such inorganic fillers include fumed silica, silica aerogel, and precipitated silica. Also,
Solvents such as toluene and hexane, viscosity modifiers such as polydimethylsiloxane, additional base polymers such as alkenyl-containing polysiloxanes, cure inhibitors such as acetylene alcohol and its reaction products with polysiloxanes, etc. , may be used in combination to the extent that the effects of the present invention are not lost. [Effects of the Invention] The present invention provides a polyorganosiloxane composition that has excellent adhesion to a substrate at room temperature or by slight heating, and forms a stable gel-like material with little discoloration or change in physical properties at high temperatures. was gotten. The composition of the present invention is suitable for use in electrical and electronic parts, particularly optical coupling pads that require optical transparency, potting of parts where design value is important, encapsulation, and the human body. Used for making models, etc. [Example] Examples of the present invention will be shown below. In the examples, all parts are by weight, and viscosity is the viscosity at 25°C. In addition, the symbol Me,
Vi and Ph represent a methyl group, a vinyl group and a phenyl group, respectively. Example 1 Compositions 1 to 5 were prepared by uniformly mixing the materials shown below at the compounding ratios shown in Table 1. However, compositions 1 and 2 are products of the present invention, and compositions 3 to 5 are comparative products. <As component (A)> Polysiloxane: Average formula A polydimethylsiloxane containing a vinyl group represented by: Viscosity: 650cP Polysiloxane: Average formula A polyorganosiloxane containing a vinyl group and a phenyl group represented by: Viscosity: 2000cP <As component (B)> Polysiloxane: Average formula Polymethylhydrodienesiloxane represented by Viscosity: 45cP, effective hydrogen amount: 0.11% by weight Polysiloxane: average formula Polymethylhydrodiene siloxane represented by Viscosity: 50 cP, effective hydrogen amount: 0.80% by weight <As component (C)> Platinum: Obtained by heating chloroplatinic acid and tetramethyltetravinylcyclotetrasiloxane. Platinum content: 2.0% by weight as platinum

[Table] Number of atoms Curing When each of these compositions was heated at 50° C. for 2 hours, all of them were cured to obtain corresponding transparent gel-like materials 1 to 5. ASTM D-1403
When the penetration of the gel-like material was measured according to
Values as shown in the initial values in Table 2 were obtained. Heat Resistance Test The gel-like materials 1 to 5 obtained by curing were placed in an air circulation oven at 150° C., and the change in penetration over time was measured, and the degree of discoloration was measured using the APHA value. The results are shown in Table 2.

[Table] As shown above, polymethylhydrodienesiloxane in which the number of hydrogen atoms bonded to a silicon atom is 1 or more per vinyl group bonded to a silicon atom, and the effective hydrogen amount is 0.5% by weight or less, and Products 1 and 2 of the present invention, which contain platinum in an amount of 30 ppm or less based on the sum of (A) and (B), harden into a soft gel-like material, resulting in a composition with little discoloration and change in penetration at high temperatures. It was done. Example 2 Polysiloxane of Example 1 - 100 parts average formula 6.1 parts of polymethylhydrodiene siloxane with a viscosity of 60 cP and an effective hydrogen content of 0.11% by weight,
and 0.03 part of the platinum used in Example 1 were mixed uniformly and left at 50°C for 2 hours to harden into a gel-like mixture. The penetration of the obtained gel-like material was determined by ASTM D-1403.
When measured according to the standard, it was 95. Also,
A heat resistance test was performed on the gel-like material obtained by hardening in the same manner as in Example 1, and as shown in Table 3, good results similar to those of Compositions 1 and 2 of Example 1 were obtained.

[Table] Table 4 also shows the transmittance at the initial stage and after 1000 hours at 150°C.

[Table] * Transmittance; Percentage of air Shows good transmittance even after heating. Example 3 100 parts of the polysiloxane of Example 1
Me ₂ SiO units 50 mol%, SiO ₂ units 42 mol%,
5.5 parts of polymethylhydrodiene siloxane with a viscosity of 15 cP and an effective hydrogen content of 0.12% by weight, consisting of 8 mol% of HMe ₂ SiO _1/2 units, and the platinum used in Example 1.
When 0.03 parts were mixed uniformly and left at 50℃ for 2 hours, the penetration was as per ASTM D-1403.
99 gel-like material was obtained. This gel-like material is heated to 150℃.
Even after heating for 1000 hours, the penetration was 85 and the APHA value was 10. Example 4 In the same manner as Composition 1 of Example 1 except that 0.012 parts of the following platinum compound was used instead of platinum, the mixture was mixed uniformly and left at 50°C for 2 hours. 93 gels were obtained. This gel-like material was heated at 150℃ for 1000 hours, and the penetration was 85.
The APHA value was still 10. Platinum: Obtained by heating chloroplatinic acid and tetramethyldivinyldisiloxane. Platinum content: 0.5% by weight as platinum

Claims (1)

[Claims] 1 (A) An average of 0.1 to 2.0 vinyl groups bonded to the silicon atom exist in one molecule, and the remaining organic groups bonded to the silicon atom are substituted or non-substituted without aliphatic unsaturation. Polyorganosiloxane (B), which is a substituted monovalent hydrocarbon group and has a viscosity of 50 to 100,000 cP at 25°C.There are more than 2 hydrogen atoms bonded to silicon atoms in one molecule on average, and the effective hydrogen amount is Polyorganohydrodiene siloxane with 0.5% by weight or less, the number of hydrogen atoms bonded to silicon atoms is (A)
and (C) a catalyst selected from the group consisting of a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst; (B)
0.01~ as the amount of catalytic metal element relative to the total amount of
A gel composition comprising an amount of 30 ppm. 2. The composition according to claim 1, wherein the vinyl group bonded to the silicon atom of (A) is present at the end of the molecule. 3. The composition of claim 1, wherein (A) is a substantially linear polyorganosiloxane. 4. The organic group other than the vinyl group bonded to the silicon atom in (A) is a monovalent hydrocarbon group selected from the group consisting of a methyl group and a phenyl group, and the amount of the phenyl group is The composition according to claim 1, wherein the content is 50 mol% or less. 5. The composition according to claim 4, wherein the organic group other than the vinyl group bonded to the silicon atom in (A) is a methyl group. 6. The composition according to claim 1, wherein (A) has a viscosity of 300 to 5000 cP at 25°C. 7. The composition according to claim 1, wherein the organic group bonded to the silicon atom in (B) is a methyl group. 8 The amount of (B) is such that the number of hydrogen atoms bonded to the silicon atom of (B) is 1.0 to 1.5 per vinyl group bonded to the silicon atom of (A). A composition according to scope 1. 9. The composition according to claim 1, wherein the catalyst in (C) is a platinum-based catalyst.