JPH02245060A - Ultraviolet-curing silicone gel composition - Google Patents

Abstract

PURPOSE:To prepare an ultraviolet-curing silicone gel compsn. with an excellent heat resistance without causing a cure inhibition by compounding a specific polyorganosiloxane and a specific mercaptoalkylated polyorganosiloxane. CONSTITUTION:The title composition comprises a polyorganosiloxane (A) in which unsatd. aliph. groups attached to silicon atoms exist in an amt. of 0.01-20mol% and the residual org. groups attached to silicon atoms are optionally substd. monovalent hydrocarbon groups contg. no unsatd. aliph. group, and of which the viscosity at 25 deg.C is 50-10000cP, and a mercaptoalkylated polyorganosiloxane (B) in which on an average at least three mercaptoalkyl groups attached to silicon atoms exist in the molecule and the residual org. groups attached to silicon atoms are optionally substd. monovalent hydrocarbon groups contg. no aliph. unsatd. group in such a way that the ratio of the number of mercaptoalkyl groups of B to that of unsatd. groups attached to the silicon atom of A is 0.1-1.5.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention is a polyorganosiloxane containing an aliphatic unsaturated group and a polyorganosiloxane containing a mercaptoalkyl group. The present invention relates to a composition that provides the following properties.

[Technical background of the invention and its problems]

Conventionally, silicone gels are produced using unsaturated double bond-containing polysiloxanes and hydrogen group-containing polysiloxanes with platinum catalysts.
A thermosetting type is known in which an addition reaction is carried out in the presence of a peroxide or the like.

However, this gel composition has the disadvantage that it requires high temperature and a long time to cure.

Here, if an attempt was made to shorten the curing time, there was a drawback that the pot life would be shortened.

In addition, products using platinum catalysts are poisoned by substances such as amines, organic phosphorus compounds, sulfur compounds, and organic tin compounds, and solder fluxes whose main component is abietic acid have a substantial crosslink density. This has the disadvantage that its applications are limited because it tends to cause deterioration and poor curing.

In order to solve these problems, a specific ultraviolet curable gel composition is proposed in JP-A-63-186719. However, this composition has the disadvantage that the monovalent organic group having 4 to 25 carbon atoms including a vinyl functional group is a reactive group, and the heat resistance of the crosslinking point is poor, and the thin film and coating surface do not harden. There was a problem.

[Purpose of the invention]

The present invention aims to solve the above-mentioned problems, and as a result of intensive research to achieve this purpose, the present inventors have found that the present invention has an aliphatic unsaturated group containing an average of 0.01 to 20 mol%. A composition consisting of a polyorganosiloxane and a mercaptoalkyl group-containing polyorganosiloxane containing an average of three or more mercaptoalkyl groups in one molecule can be easily cured into a gel-like state by light irradiation, and can be easily cured into a gel-like form by irradiation with light. We have discovered that it is possible to provide a silicone gel with good heat resistance and no curing inhibition caused by the material, and have thus arrived at the present invention.

[Structure of the invention]

That is, in the present invention, (a) the number of aliphatic unsaturated groups bonded to silicon atoms is on average 0.
The remaining organic group bonded to the silicon atom is a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated group, and the viscosity at 25°C is 50 to 20 mol%.
a polyorganosiloxane that is 100,000 cP;
and (b) the mercaptoalkyl group bonded to the silicon atom is 1
A mercaptoalkyl group-containing polyorganosiloxane, which is present in an average number of more than 3 in the molecule, and the remaining organic groups bonded to silicon atoms are substituted or unsubstituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated groups; An ultraviolet curable silicone gel composition characterized in that the number of mercaptoalkyl groups is 0.1 to 1.5 per one aliphatic unsaturated group bonded to a silicon atom in (a). It is related to.

The present invention will be explained in detail below.

(a) The polyorganosiloxane of the present invention contains an average of 0.01 to 20 mol% of aliphatic unsaturated groups bonded to silicon atoms.
It is necessary to contain, especially 0.01 to 10 mol%
It is preferable that When the amount is less than 0.01 mol %, the gel penetration becomes too high or the gel does not harden.

Moreover, if the amount is more than 20 mol%, the heat resistance of the gel will deteriorate.

Regarding this heat resistance, it is more preferably 10 mol% or less.

Examples of aliphatic unsaturated groups include alkenyl groups such as vinyl, allyl and butenyl, cycloalkenyl groups such as cyclohexenyl, alkenyl-substituted aryl groups such as vinylphenyl, and alkynyl groups such as ethynyl, propynyl and butynyl. However, a vinyl group is preferred from the viewpoint of ease of obtaining materials and synthesis, and it is particularly desirable that a vinyl group be present at the end of the molecular chain.

On the other hand, the remaining organic groups bonded to the silicon atom are substituted or unsubstituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated groups, such as alkyl groups such as methyl, ethyl, and propyl, and cyclohexyl and cyclooctyl groups. Examples include cycloaryl groups, aryl groups such as phenyl, tolyl, and xylyl, and groups in which some of the hydrogen atoms of these groups are substituted, such as trifluoropropyl groups and cyanoethyl groups. From the viewpoint of ease of synthesis, heat resistance, etc., phenyl group and methyl group are preferred.

The polyorganosiloxane of component (a) is heated at 25°C.
It has a viscosity of 50 to 100,000 cP, and may be linear, branched, or cyclic, but is preferably substantially linear or branched.

The polyorganosiloxane (C) must contain an average of three or more mercaptoalkyl groups in one molecule; if it is less than that, the curability deteriorates. Examples of the mercaptoalkyl group include mercaptoethyl, mercaptopropyl, and mercaptohexyl groups.

The remaining organic groups are substituted or unsubstituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated groups, such as alkyl groups such as methyl, ethyl, and propyl, cycloaryl groups such as cyclohexyl and cyclooctyl, phenyl, and tolyl. , aryl groups such as xylyl, and groups in which some of these hydrogen atoms are substituted, such as trifluoropropyl group and cyanoethyl group. From the viewpoint of ease of synthesis, heat resistance, etc., phenyl group and methyl group are preferred.

The blending amount of (B) is based on one aliphatic unsaturated group in the aliphatic unsaturated group-containing polyorganosiloxane (A).
It is necessary that the number of mercaptoalkyl groups in b) is 0.1 to 1.5. If it is less than 0.1, it will be difficult to harden, and if it is more than 1.5, it will have a hardness that can no longer be called a gel.

The ultraviolet curable silicone gel composition of the present invention may contain a photoreaction initiator (photosensitizer), antigelation agent, heat resistance improver, filler, colored dye and pigment, and adhesion aid.

Examples of photoinitiators include aromatic hydrocarbons, acetophenone and its derivatives, benzophenone and its derivatives, 0-benzoylbenzoic acid ester, benzoin and benzoin ether and its derivatives, xanthone and its derivatives, thioxanthone and its derivatives, Examples include disulfide compounds, quinone compounds, halogenated hydrocarbons and amines, organic peroxides, etc., and an appropriate selection is made from among them.

Among these photoinitiators, compatibility with silicone,
From the viewpoint of stability, photoreaction initiators or organic peroxides containing substituted or unsubstituted benzoyl groups are preferred. The preferred amount of the photoreaction initiator is 0.002 to 30% by weight.

Any anti-gelling agent may be used as long as it prevents dark reactions, and examples thereof include p-hydroquinone, p-methoxyphenol, t-butylcatechol, and phenothiazine.

Preferred examples of the heat resistance improver include phenolic anti-aging agents.

Fillers such as fumed silicon oxide, wet silica, and fine quartz powder may be added to the composition of the present invention, if necessary, for the purpose of improving mechanical strength or adjusting fluidity.

Coloring dyes and pigments can also be used in small amounts.

〔Example〕

The present invention will be explained below with reference to Examples.

Parts in this example represent parts by weight.

Example 1 Blocked with a terminal cahinyl group, consisting of 5 mol% diphenylsiloxy units and the remainder dimethylsiloxy units at 25°C
To 100 parts by weight of methylphenylpolysiloxane having a viscosity of 2000 cP, an average structural formula of [(CH2)
5sjo+zz] [HS(CHz) asios/
d s[(CHs) tsfO□/116°, and 2
4 parts by weight of mercabutoalkylmethylborisiloxane having a viscosity of 300 cP at 5° C. was uniformly mixed. Next, 0.01 part of p-methoxyphenol, p-t-
A solution of 0.01 part of butylcatechol in 0.5 parts of toluene was mixed uniformly. Then 2-hydroxy-2-methyl-1-phenylpropan-1-one2.
5 parts were added and mixed uniformly. Pour this composition into a 50cc beaker to a depth of 13mm and use 80w/c
When it was irradiated with light for 10 seconds from a distance of 10 cm using a high-pressure mercury lamp, it hardened into a gel-like state.

The penetration of this gel was 56 as measured with an ASTM D-1403 1/4 cone. Moreover, the silicone composition in the beaker was completely cured to the bottom. This hardened gel was dried for 72 hours in a hot air circulation dryer at 150"C.
Although it was left to stand for a while, the penetration remained at 65, showing good heat resistance. Also, apply this silicone gel to a thickness of 0.2 mm on the printed circuit board on which the solder flux remains, and
When irradiated with ultraviolet rays from a distance of 10 cm for 1 second using a high-pressure mercury lamp at 0 m/cm, it hardened into a uniform gel-like state.

On the other hand, when TSE3051 (manufactured by Toshiba Silicone, platinum-catalyzed addition reaction gel) was similarly applied to a thickness of 0.2 mm and heated and cured at 125°C for 4 hours, the parts to which the flux was attached remained uncured. there were.

Example 2 The composition of Example 1 and TSE3051 were applied to various substrates shown in Table 1 to a thickness of 0.2 mm, and cured under the same curing conditions as in Example 1 to confirm the cured state. The results shown in Table 1 were obtained.

Table 1* Oxime-free condensation-curable liquid silicone rubber Example 3 To the composition of Example 1, 0.10 parts each of titanium oxide and ultramarine blue were added as pigments and uniformly dispersed using a triple roll. 50% of this composition! When poured into a #1 beaker to a depth of 10 mm and irradiated with ultraviolet rays for 10 seconds from a distance of 10 cm using an 80 W/C111 high-pressure mercury lamp, it was found to be hardened deep inside.

Further, the penetration degree at this time was 68 for the product containing titanium oxide and 67 for the product containing ultramarine blue. After 172 hours at 150°C, it was 65.68, indicating good heat resistance.

Example 4 At 25°C, the end is blocked with a vinyl group and consists of 3 mol% diphenylsiloxy units and the remainder dimethylsiloxy units.
To 100 parts by weight of methylphenylpolysiloxane having a viscosity of 1000 cP, 1 part of siloxane-treated fumed silica was added.
0 part was uniformly dispersed using a universal mixer, and further heated to 150″C.
A compound was obtained by heating and kneading under reduced pressure with 11C11O for 4 hours. The viscosity of this compound is 4000c at 25℃
It was P. The average structural formula is then [(CH3)ss
iO+7g] [H5(CH2)3Si03z□] 4
[(CH3) tsiotz□],. Mercaptoresin 3.5 with a viscosity of 450 cP at 25°C
1 part, 2 parts of a 50% solution of benzophenone in toluene, and 2-
Hydroxy-2-methyl-1 (p-4so-propyl)
2 parts phenylpropan-1-one and 0.01 part p-methoxyphenol, 0.0 part p-t-butylcatechol
A solution of 1 part in 0.7 parts of toluene was uniformly mixed into the above compound. Pour this composition into a 50cc beaker to a depth of 15mm, and
When irradiated with light for 10 seconds from a distance of 10c+n using a high-pressure mercury lamp of Cm, it was completely cured to the depths.

The penetration of this gel is 72, 150″C after 178 hours 7
0, good heat resistance was shown.

Example 5 The end is blocked with a vinyl group, the diphenylsiloxy unit is 5 mol%, the remainder is dimethylsiloxy unit, and the temperature is 25°C.
2-hydroxy-2-methyl-1-phenyl-propan-1-one 2-hydroxy-2-methyl-1-phenyl-propan-1-one 2-hydroxy-2-methyl-1-phenyl-propan-1-one 2-hydroxy-2-methyl-1-phenyl-propan-1-one
．． 5 parts and 0.01 part p-methoxyphenol, p-t
-butylcatechol 0.01 part, tetrakis[methylene-3-(3', 5'-di-t-butyl-4'-hydroxyphenyl)propionate cometaph 0.03 part, 2
Hydroxy-4-n-octoxybenzophenone 0.0
A solution of 1 part dissolved in 1 part of toluene was added and stirred uniformly. This composition has an average structural formula of [(CH3) 1
sio+zz] [H3(CHz) asjO3/zl
s [(CHs) zSi(hzz] b.
Mercaptoalkylsiloxane having a viscosity of 250 cP at 25°C was added at the blending ratio shown in Table 2 to form compositions 5-1 to 5.
-5 was prepared.

This composition was poured into a 50 cc beaker to a depth of 15 m + w, and heated with a high pressure mercury lamp of 80 w/cm for 10 min.
Ultraviolet rays were irradiated for 10 seconds from a distance of cm to obtain a cured gel product. The penetration degree of the obtained gel is shown in Table 2.

Table 2 Example 6 End-capped with vinyl group, viscosity at 25°C 10
Mercaptoalkylmethylpolysiloxane having a viscosity of 80 cP at 25 DEG C. and containing 10 methyl(3-mercaptopropyl)siloxy units and 68 dimethylsiloxy units, the end of which is closed with a trimethylsilyl group in 100 parts by weight of dimethylpolysiloxane having a viscosity of 80 cP.5. 5 parts of jetoxyacetophenone, 0.01 part of p-methoxyphenol, and 0.01 part of p-t-butylcatechol dissolved in 0.5 part of toluene were added and stirred uniformly. Pour this composition into a 50 cc beaker to a depth of 15 mm, ■ Toshiba (manufactured) fluorescent lamp PL-20.
When the BLB was turned on for 10 minutes from a distance of 5 cm,
The composition was completely cured into a gel-like state, and the penetration was 78. This composition was left at 150° C. for 72 hours and the penetration was measured to be 80.

Example 7 The average structural formula is CH.

[CH2=C)I-3iO+ /zl t [(CHs
) zsioz/zl qs [CH35iO+zzl
suff, 100 parts of a vinyl group-containing organopolysiloxane with a viscosity of 5000 cP at 25°C, 4.6 parts of an organopolysiloxane with an average viscosity of 130 cP at 25°C, 2 parts of benzoin butyl ether, and P-methoxyphenol. A solution of 0.01 part of pt-butylcatechol and 0.01 part of pt-butylcatechol dissolved in 0.5 part of toluene was added and stirred uniformly. When this composition was poured into a 50 cc beaker to a depth of 101 and irradiated with ultraviolet rays for 10 seconds using an 8011/Cl11 metal halide lamp, the penetration was 72. The heat resistance was evaluated at 150'C for 72 hours, but the penetration remained at 72.

Example 8 A composition was prepared under the same conditions except that 100 parts by weight of a vinyl group-containing organopolysiloxane having an average structural formula and a viscosity of 2000 cP at 25° C. was used instead of the vinyl group-containing organopolysiloxane of Example 6. When obtained and cured using the same method, the penetration was 100, and after 172 hours at 150'C, the penetration was 98.
Met.

〔Effect of the invention〕

The composition of the present invention can be easily cured on the surface and deep by short-time irradiation with ultraviolet rays, and a thick cured silicone gel can be obtained. In addition, unlike addition reaction type silicone gels using platinum catalysts, it does not suffer from curing inhibition from the contact base material, and has better heat resistance than acrylic UV-curable silicone gel compositions. It also has low temperature resistance and water resistance that are unique to silicone resins, so it can be used under a variety of conditions, such as moisture proofing for electrical and electronic components, botting as a buffer material for external stress, and mounting of electronic components. It can be suitably used as a temporary fixing material in the process. It can also be used as cushioning material for sports shoes, baseball gloves, etc., and for various dampers.

Claims (1)

[Scope of Claims] 1 (a) An average of 0.01 to 20 mol% of aliphatic unsaturated groups bonded to silicon atoms is present, and the remaining organic groups bonded to silicon atoms do not contain aliphatic unsaturated groups. A substituted or unsubstituted monovalent hydrocarbon group with a viscosity of 50 to 100.0 at 25°C.
00 cP, and (b) the mercaptoalkyl group bonded to the silicon atom is 1
A mercaptoalkyl group-containing polyorganosiloxane, which is present in an average number of more than 3 in the molecule, and the remaining organic groups bonded to silicon atoms are substituted or unsubstituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated groups; An ultraviolet curable silicone gel composition characterized in that the number of mercaptoalkyl groups is 0.1 to 1.5 per one aliphatic unsaturated group bonded to a silicon atom in (a). . 2. The composition according to claim 1, wherein the aliphatic unsaturated group bonded to the silicon atom in (a) is a vinyl group present at the end of the molecular chain. 3. The composition according to claim 1, wherein the aliphatic unsaturated group-containing polyorganosiloxane (a) is substantially linear. 4. The composition according to claim 1, wherein the aliphatic unsaturated group bonded to the silicon atom of (a) is present in an average amount of 0.01 to 10 mol%. 5. The composition according to claim 1, wherein the remaining organic group bonded to the silicon atom in (a) is a methyl group and/or a phenyl group. 6. The mercaptoalkyl group-containing polyorganosiloxane of (b) has a viscosity of 50 to 10,000 at 25°C.
2. The composition of claim 1, which is cP. 7. The composition according to claim 1, wherein the remaining organic group bonded to the silicon atom in (b) is a methyl group and/or a phenyl group. 8. The composition according to claim 1, further comprising 0.002 to 30% by weight of a photoinitiator.