JPH01213363A - Polyorganosiloxane composition - Google Patents

Abstract

PURPOSE:To obtain the above composition free from change in physical properties even by potting to form multiple layers, curable to a stable gel and suitable for insulation coating of electrical and electronic parts, etc., by compounding a specific polyorganosiloxane with a catalyst for addition reaction. CONSTITUTION:The objective composition is produced by compounding (A) a polyorganosiloxane in which the ratio of vinyl group and hydrogen atom. in whole side chain bonded to silicon atom. is 0.1-4mol.%, preferably 0.2-2mol.% each on an average and the ratio of vinyl group bonded to silicon atom. to hydrogen atom. bonded to silicon atom. is 0.8-3 with (B) 0.1-100ppm, preferably 3-20ppm of a catalyst for addition reaction (e.g., chloroplatinic acid).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyorganosiloxane composition, and more particularly to a polyorganosiloxane composition that hardens into a gel having stable physical properties even when potted in multiple layers.

[Conventional technology]

Gel-like cured products of silicone rubber (hereinafter referred to as silicone gel) are particularly useful for potting and sealing electrical and electronic parts, taking advantage of their excellent electrical insulation properties, stability of electrical properties, and flexibility. It is used to cover control circuit elements such as power transistors, ICs, and capacitors to protect them from thermal and mechanical damage.

Various methods are conventionally known for forming this silicone gel. For example, a composition consisting of a polyorganosiloxane having a vinyl group bonded to a silicon atom and a polyorganohydrodiene siloxane having a hydrogen atom bonded to a silicon atom is subjected to a crosslinking reaction in the presence of a platinum compound and cured into a gel form. There are ways to obtain polyorganosiloxane.

[Problem that the invention seeks to solve]

By the way, when soldering a semiconductor element to a terminal, etc., in order to protect it from heat and solder splash, the semiconductor element is first coated with silicone gel to form a protective film (first layer gel), and then the terminal, etc. solder, and then apply a protective layer (second layer gel) on the surface layer, which is the original purpose.
is carried out. In order to form this second layer gel, according to the above conventional method, the polyorganohydrodiene siloxane in the composition potted for forming the second layer penetrates into the first layer gel, and the second layer gel is formed. The balance of functional groups in the gel composition may be upset. Therefore, the expected gel properties cannot be obtained when the second layer is cured, and vinyl groups remain in the gel-like material of the second layer, which causes a decrease in heat resistance. Furthermore, there is a problem in that the uncrosslinked polysiloxane oozes out onto the surface of the second layer and contaminates other parts.

Therefore, an object of the present invention is to provide a polyorganosiloxane composition that can be cured into a stable gel-like material without changing its physical properties even when it is bobbed into multiple layers.

Means for Solving Problem C] The present invention solves the above problems by providing (A) an average proportion of vinyl groups and hydrogen atoms in the total side groups bonded to silicon atoms of 0.1, respectively; The present invention provides a polyorganosiloxane composition containing a polyorganosiloxane having an amount of 4.0 mol % and (B) an addition reaction catalyst.

The polyorganosiloxane which is the component (A) used in the present invention is a linear or branched polyorganosiloxane, and contains a vinyl group bonded to a silicon atom and a hydrogen atom bonded to a silicon atom in one molecule. For example, the average unit formula:
represents a valent hydrocarbon group, and a is a number from 1.8 to 3.0. ] It is expressed as. The vinyl group bonded to the silicon atom and the hydrogen atom bonded to the silicon atom may be bonded to any silicon atom at the end or in the middle of the molecular chain.

In the polyorganosiloxane of component (A) of the present invention, the ratio of vinyl groups bonded to the silicon atom in all side groups (including terminal groups) bonded to the silicon atom in one molecule is on average 0. 1 to 4.0 mol%, preferably 0
．． The proportion of hydrogen atoms bonded to silicon atoms is on average 0.1 to 4.0 mol%, preferably 0.2 to 2.0 mol%. If the proportion of either the vinyl group bonded to the silicon atom or the hydrogen atom bonded to the silicon atom is less than 0.1 mol% on average in all the side groups bonded to the silicon atom in one molecule, gel formation may occur. If it exceeds 4.0 mol %, the resulting gel becomes too hard and cannot function as a gel.

In the polyorganosiloxane component (A), the ratio of vinyl groups bonded to silicon atoms/hydrogen atoms bonded to silicon atoms is usually preferably 0.8 to 3, more preferably 0.9 to 2. range. If this ratio is too large, the heat resistance of the silicone gel obtained will be reduced due to the residual vinyl groups, and if this ratio is too small, foaming will occur easily during gel formation.

In the polyorganosiloxane of the component (^) of the present invention, the remaining side groups bonded to the silicon atom excluding the vinyl group bonded to the silicon atom and the hydrogen atom bonded to the silicon atom are substituted excluding aliphatic unsaturated groups. or an unsubstituted monovalent hydrocarbon group, such as an alkyl group such as a methyl group, ethyl group, or propyl group, an aryl group such as a phenyl group, or an aralkyl group such as a β-phenylethyl group or a β-phenylpropyl group. an unsubstituted hydrocarbon group; and a chloromethyl group,
Examples include substituted hydrocarbon groups such as a cyanoethyl group and a 3,3.3-)lifluoropropyl group. Of these,
A methyl group is more preferred from the viewpoints of ease of synthesis of the polyorganosiloxane (A) component, heat resistance and physical properties of the gel-like product obtained.

Specific examples of such polyorganosiloxanes as component (A) include (in the above formula, a''-'m is a positive integer).

The polyorganosiloxane which is component (A) of the present invention is
The viscosity at 25°C is usually preferably 100 to 1
00000cP, more preferably 300-5000c
It belongs to P. If the viscosity is too high, workability and foam removal will be poor; if the viscosity is too low, it will flow easily and the physical properties after the reaction will be poor.

As mentioned above, the polyorganosiloxane of component (A) of the composition of the present invention is linear or branched, but when the gel-like cured product of the composition of the present invention is required to have cold resistance. Preferably, component (A) is branched.

The method for producing polyorganosiloxane, component (A), is well known and obvious to those skilled in the art.

The addition reaction catalyst which is component (B) of the composition of the present invention is:
It is for causing an addition reaction between the vinyl group bonded to the silicon atom and the hydrogen atom bonded to the silicon atom in the polyorganosiloxane of the component (A), and is not particularly limited, and any known one can be used.

For example, platinum compounds such as chloroplatinic acid, alcohol-denatured solutions of chloroplatinic acid, coordination compounds of chloroplatinic acid and olefins or vinylsiloxane, tetrakis(triphenylphosphine)palladium, chlorotris(triphenylphosphine)rhodium, etc. Among them, platinum-based compounds are preferred.

In the composition of the present invention, the blending ratio of the addition reaction catalyst (B) is usually preferably 0.1 to 1100 pp, more preferably 3 to 20 pp, based on the polyorganosiloxane (A) component. It is ppn+. If the amount of component (B) is too large, discoloration due to thermal deterioration will be large and the cost will increase, while if the amount is too small, curing will be inhibited.

In addition to the above-mentioned components (A) and (B), various optional components can be added to the composition of the present invention as required. For example, fumed silica, silica aerosil, precipitated silica, ground silica, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, calcium carbonate, magnesium carbonate, zinc carbonate,
By adding an inorganic filler such as carbon black, the hardness, mechanical strength, etc. of the composition of the present invention after curing can be adjusted. The amount of these inorganic fillers to be used is not particularly limited, and can be arbitrarily selected as long as it does not impair the properties of the cured product of the present invention. Further, other silicone oil such as dimethylpolysiloxane or raw rubber can be added to the extent that the effects of the present invention are not impaired to adjust the flowability of the composition of the present invention, the hardness of the cured product, etc.

The curing reaction of component (A) can also be controlled by adding conventionally known reaction inhibitors such as polymethylvinylsiloxane cyclic compounds, acetylene compounds, organic phosphorus compounds, etc. to the composition of the present invention.

The composition of the present invention does not change its physical properties even when potted in multiple layers and hardens into a stable gel-like material.
It can be used as an insulating coating or a protective coating for electronic components, and in particular, it can be used as a coating film to protect control elements such as power transistors, ICs, and capacitors from thermal and mechanical disturbances.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Examples 1 to 2 On each side, a polymerization vessel was charged with a monomer mixture having the composition shown in Table 1, and then 0.25 g of trifluoromethanesulfonic acid was added as a catalyst, and an equilibration reaction was carried out at room temperature for 8 hours. . After the reaction was completed, 6 g of sodium bicarbonate was added to neutralize, the product was filtered to remove the acid salts and excess sodium bicarbonate, and the product was stripped with 180″ CSIOC51O to obtain the polyorganosiloxane. Ta.

The viscosity of the obtained polyorganosiloxane, the average content of vinyl groups bonded to silicon atoms and the average content of hydrogen atoms bonded to silicon atoms in one molecule of the polymer were measured.

The measurement results are shown in Table 1.

Next, 0.01 part by weight of ethynylcyclohexanol was added to 100 parts by weight of the obtained polyorganosiloxane and mixed uniformly, and then a vinyl siloxane complex of chloroplatinic acid was added in an amount such that platinum was 5 ppm based on the total amount of the mixture. The mixture was added and mixed uniformly to obtain a polyorganosiloxane composition.

When the resulting composition was heated at 150°C for 30 minutes, a transparent gel-like substance was formed. The penetration of this gel-like material was measured using a 174 scale penetrometer. In addition, composition t
og was poured into an aluminum Petri dish with a diameter of 60 mm and a depth of 10 mm, and heated at 150°C for 30 minutes to create a first layer gel. Composition 5 is further applied to the surface layer of the first layer gel formed.
g was injected and heated at 150°C for 30 minutes to create a second layer gel. The stacked gel was cut vertically, and the interface between the first layer gel and the second layer gel was visually observed and evaluated.

The results are shown in Table 1.

Comparative Example 1 Viscosity 800 cp (25°C), Me2SiO unit 99
．． 100 parts by weight of a vinyl-containing polyorganosiloxane consisting of 1 mol% of ViMezSiOo, 0.27 mol% of 5 units and 0.63 mol% of Me:1SiOo, s units, and 62 mol% of MezSiO units, 3 MeH3iO units.
7 mol% and MesSiQ. Example 1 was carried out in the same manner as in Example 1, except that a blend of 0.7 parts by weight of methylhydrodiene polysiloxane containing 1 mol % of units was used instead of the polyorganosiloxane having both 5iVi groups and SiH groups. A composition was obtained, and this composition was also tested for penetration and the prepared first layer gel and second layer gel using the same test method as in the example.
The interfacial state of the gel was evaluated.

The results are shown in Table 1.

Table 1 Umbrella 2: Content of hydrogen atoms bonded to silicon atoms [Effects of the invention] The polyorganosiloxane composition of the present invention can be cured to obtain a stable gel-like material, and can be used in electrical and electronic applications. It can be used for a wide variety of purposes, including related protective coatings.

In particular, it is useful as a composition for forming a multilayer gel when soldering semiconductor elements to terminals, etc., because its physical properties do not change even when potted into multiple layers, and it can be cured into a stable gel-like material. .

Agent Patent Attorney Comrade Iwamiya

Claims (1)

[Scope of Claims] (A) The average proportion of vinyl groups and hydrogen atoms in all side groups bonded to silicon atoms is 0.1 to 4.0, respectively.
% by mole of a polyorganosiloxane, and (B) a catalyst for an addition reaction.