JPH068334B2 - UV curable organopolysiloxane composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultraviolet-curable organopolysiloxane composition,
In particular, the present invention relates to a UV-curable organopolysiloxane composition which is non-corrosive and odorless and is useful for electronics and the like.

(Conventional technology) Liquid silicone rubber This curable liquid silicone is widely used as a potting material, sealing material, and coating material for electrical and electronic products because its coating film has excellent heat resistance, weather resistance, and electrical characteristics. It is known that the rubber is a condensation type one-pack type and an addition reaction type one-pack type or two-pack type.

However, the condensation type has a disadvantage that it takes several hours to several days for curing and is not suitable for a continuous production line, and the addition reaction type is used as a catalyst although it is cured by heating for several minutes to several hours. When platinum compounds come into contact with sweat, solder flux, sulfur, vulcanized rubber, condensation type one-component silicone rubber, etc., they have the drawback of not being cured by poisoning, which is a disadvantage that curing strain occurs during heat curing. There is.

On the other hand, a photocurable silicone rubber has been proposed as a curable silicone rubber that does not have such disadvantages. For example, a vinyl radical-containing polysiloxane and a mercapto group-containing polysiloxane are cured by a photoradical addition reaction. Some of them are known (see Japanese Examined Patent Publication (Kokoku) No. 52-40334 and Japanese Patent Laid-Open No. 60-104158), but their use is limited due to problems of odor of mercapto group and corrosion of metal. There is a disadvantage that. Further, as a composition which is cured by irradiation with light, a composition comprising an acrylic group-containing polysiloxane and a sensitizer has been proposed (Japanese Patent Publication No. Sho.
No. 215509), it is necessary to use a high molecular weight linear polymer in order to obtain a rubber-like elastic body, and therefore the amount of acrylic groups at the ends is relatively very small and the curability is poor. However, since the surface part in contact with air hardly cures due to the inhibition of curing by oxygen, only resin-like products with a relatively large amount of acrylic groups have been put to practical use, and satisfactory rubber-like products are available. No elastic body is obtained.

(Structure of the Invention) The present invention relates to an ultraviolet-curable organopolysiloxane composition which has solved such disadvantages, and it is 1)
General formula (Here, R ¹ is a hydrogen atom or a methyl group, R ² , R ³ , R ⁴
Is the same or different unsubstituted or substituted monovalent hydrocarbon group,
a and b are characterized by comprising 100 parts by weight of an organopolysiloxane having at least one group represented by 1, 2 or 3) in the molecule, and 2) 0.01 to 10 parts by weight of a photoinitiator. .

That is, according to the present invention, as a result of various studies on obtaining an ultraviolet-curable organopolysiloxane composition which does not have the above-mentioned disadvantages and drawbacks, the acryloxyorganosilyl group represented by the above general formula (1) is contained in the molecule. The organopolysiloxane having at least one of them serves as a cross-linking point when this acryloxyorganosilyl group is irradiated with ultraviolet rays, and therefore, when irradiated with ultraviolet rays in the presence of a photoinitiator, the curability far exceeds that expected and it is rubber-like. The present invention has been completed by finding out that it becomes an elastic body, and confirming that it has almost no inhibition of oxygen curing which has been a fatal defect in the conventional composition of this kind.

The organopolysiloxane as the first component constituting the composition of the present invention has a general formula in the molecule. R ¹ is a hydrogen atom or a methyl group, R ² , R
³ , R ⁴ are alkyl groups such as methyl group, ethyl group, propyl group and butyl group, cycloalkyl groups such as cyclohexyl group, alkenyl groups such as vinyl group and allyl group, aryl groups such as phenyl group and tolyl group Or a hydrogen atom bonded to a carbon atom of these groups, some or all of which are the same or different, selected from a chloromethyl group, a trifluoropropyl group, a cyanoethyl group, etc. An unsubstituted or substituted monovalent hydrocarbon group, a and b are each 1, 2 or 3 and are supposed to have at least one acryloxyorganosilyl group, which was found by the present inventors. It is a novel compound that has not been published in the literature, and is exemplified by the following.

The organopolysiloxane can be obtained, for example, by the following method. That is, this synthesis starts with the general formula Wherein R ⁵ is a divalent hydrocarbon group, R ⁶ and R ⁷ are methyl groups or phenyl groups, and C is 0 or 1, and an organosiloxane having at least one group in the molecule, for example, With an organopolysiloxane such as And an addition reaction of a chlorosilane having d of 0, 1 or 2 such as CH ₃ HSiC ₂ or HSiC _{3 in} the presence of a platinum catalyst such as a chloroplatinic acid solution in isopropyl alcohol at 50 to 80 ° C. Let the general formula An organopolysiloxane having a group represented by the following at the molecular chain end, for example, the following is synthesized.

Next, the general formula for this organopolysiloxane Wherein R ¹ , R ² , R ³ and b are as defined above for an acryloxyorganosilanol, eg Is mixed in the above-mentioned organopolysiloxane so that the chloro group and the silanol group in this silanol are equimolar, and then reacted at room temperature in the presence of a dehydrochlorinating agent such as triethylamine, and then desalted. By doing so, the desired organopolysiloxane as described above can be easily obtained.

Further, the photoinitiator as the second component in this composition is for promoting the photopolymerization of the acrylic group in the organopolysiloxane as the above-mentioned first component,
This may be one that is well known in the art, including acetophenone, propiophenone, benzophenone,
Xanthone, fluorene, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-methylacetophenone, 3-pentylacetophenone, 4-methoxyacetophenone,
3-bromoacetophenone, 4-allylacetophenone, p-diacetylbenzene, 3-methoxybenzophenone, 4-methylbenzophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4-chloro-4'-benzylbenzophenone, 3- Chloroxanthone, 3,9-dichloroxanthone, 3-chloro-8
-Nonylxanthone, benzoin, benzoin methyl ether, benzoin butyl ether, bis (4-dimethylaminophenyl) ketone, benzyl methoxy ketal, 2-chlorothioxanthone, diethyl acetophenone, 1-hydroxycyclohexyl phenyl ketone, 2
Examples include -methyl [4-methylthio) phenyl] 2-morpholino-1-propanone and 2,2-dimethoxy-2-phenylacetophenone. In addition, this compounding amount is the above-mentioned organopolysiloxane 1 as the first component.
If it is 0.01 part by weight or less with respect to 00 parts by weight, the addition effect will not be obtained, and if it is 10 parts by weight or more, the silicone rubber obtained from this will have low strength and the physical properties of the cured product will be deteriorated. It must be within the scope of the department.

In the present invention, the composition can be obtained by uniformly mixing the above-mentioned predetermined amounts of the first component and the second component, and if necessary, a fumed silica-based filler that does not inhibit photocuring is added. You may add.

Since the organopolysiloxane as the first component contains a photopolymerizable acryloxyorganosilyl group, the composition of the present invention thus obtained can be irradiated with ultraviolet rays in a short time of 1 to 20 seconds. It easily cures to give silicone rubber, but since it is non-corrosive and odorless, it is particularly useful as a potting material, sealing material, coating material for various electric and electronic parts manufactured in a line.

Next, examples of the synthesis of the organopolysiloxane as the first component and examples of the present invention will be described. In the examples, parts are parts by weight, and viscosities are measured values at 25 ° C.

Synthesis Example 1 500 g of α, ω-divinyldimethylpolysiloxane having a viscosity of 400 cS (vinyl value of 0.018 mol / 100 g) was placed in a reaction flask 1 equipped with a thermometer and a stirrer, and heated at 120 ° C. for 2 hours under a nitrogen gas stream. After dehydration, and after cooling, 0.1 g of isopropyl alcohol solution of chloroplatinic acid (platinum content 2% by weight) and 10 g of methyldichlorosilane are added, and the mixture is reacted at 50 ° C. for 1 hour and further at 80 ° C. for 3 hours. At the same temperature, nitrogen gas was passed through this liquid to remove unreacted methyldichlorosilane out of the system.

Then, add 36.4 g of triethylamine and 3,5-di-t.
After adding 0.1 g of -butyl-4-hydroxytoluene, 36.1 g of α-acryloxymethyldimethylsilanol was added dropwise over 30 minutes, and after reacting at 60 ° C for 2 hours, the generated salt was separated and 100 ° C / 2 mmHg Stripped under conditions to remove excess triethylamine under reduced pressure, the following formula with physical properties of viscosity 588 cS, refractive index 1.4080, specific gravity 0.978 As a result, 485 g of organopolysiloxane (hereinafter abbreviated as polymer A) represented by

Synthesis Example 2 500 g of α, ω-divinyldimethylpolysiloxane (vinyl value 0.012 mol / 100 g) having a viscosity of 1,000 cS was placed in a reaction flask 1 equipped with a thermometer and a stirrer.
After dehydration by heating at 120 ° C for 2 hours in a nitrogen gas stream, after cooling, 0.1 g of an isopropyl alcohol solution of chloroplatinic acid (2% by weight of platinum) and 10.8 g of trichlorosilane are added, and the mixture is heated at 50 ° C for 1 hour. After reacting for 3 hours at 80 ° C., nitrogen gas was allowed to flow into this solution at the same temperature to remove unreacted trichlorosilane out of the system.

Then, add 36.4 g of triethylamine and 3,5-di-t.
After adding 0.1 g of -butyl-4-hydroxytoluene, 28.9 g of α-acryloxymethyldimethylsilanol was added dropwise over 30 minutes, and after reacting at 60 ° C for 2 hours, the formed salt was separated and 100 ° C / 2 mmHg Stripped under conditions to remove excess triethylamine under reduced pressure, the following formula with physical properties of viscosity 1,230 cS, refractive index 1.4069, specific gravity 0.978 As a result, 460 g of an organopolysiloxane (hereinafter abbreviated as polymer B) represented by

Synthesis Example 3 200 g of α, ω-divinyldimethyldiphenylpolysiloxane having a viscosity of 4,000 cS (vinyl value of 0.018 mol / 100 g, phenyl group amount of 30 mol%) was placed in a 0.5 reaction flask equipped with a thermometer and a stirrer. After heating at 120 ° C for 2 hours under a stream of nitrogen gas to dehydrate and after cooling,
Add 0.1 g of chloroplatinic acid isopropyl alcohol solution (2% by weight of platinum) and 4.6 g of methyldichlorosilane,
After reacting at 50 ° C. for 1 hour and further at 80 ° C. for 3 hours, nitrogen gas was passed through this solution at the same temperature to remove unreacted methyldichlorosilane out of the system.

Then, add 8 g of triethylamine and 3,5-di-t-
Add butyl-4-hydroxytoluene 0.1 g and then α
-Acrylic oxymethyl dimethyl silanol 11.5g 3
After dropping for 0 minutes and reacting at 60 ° C for 2 hours, the formed salt was separated and stripped under the condition of 100 ° C / 2mmHg to remove excess triethylamine under reduced pressure. The viscosity was 4,400cS, The following formula with the physical properties of rate 1.508 and specific gravity 1.081 As a result, 196 g of an organopolysiloxane (hereinafter abbreviated as polymer C) represented by

Synthesis Example 4 In a reaction flask 1 equipped with a thermometer and a stirrer, a methylphenylsiloxane block polymer having a vinyl group equivalent of 0.036 mol / 100 g (phenyl group amount 55 mol%, 2
500 g of 50% toluene solution having a functional group / trifunctional group molar ratio of 1.0) was charged, heated and dehydrated under reflux of toluene for 2 hours, cooled and then isopropyl alcohol solution of chloroplatinic acid (platinum amount 2% by weight) 0.05 g and 15 g of methyldichlorosilane were added, and the mixture was reacted at 80 ° C. for 1 hour, further at 80 ° C. for 1 hour and further under toluene reflux for 3 hours, and then toluene and excess methyldichlorosilane were removed at 100 ° C./2 mmHg under reduced pressure. Then, add toluene 20 to this again.
0 g, triethylamine 40 g, and 3,5-di-t-butyl-4-hydroxytoluene 0.1 g were added, and α-acryloxymethyldimethylsilanol 31.8 g was added dropwise thereto over 30 minutes, followed by reaction at 60 ° C. for 2 hours. Also, when the generated salt was separated, the viscosity was 55 cS, the refractive index was 1.4785, and the specific gravity was 1.
005, non-volatile content (105 ℃ / 3 hours) 58.3% with the following formula As a result, 446 g of a toluene solution of organopolysiloxane (hereinafter abbreviated as polymer D) represented by

Synthesis Example 5 The methyldichlorosilane in Synthesis Example 1 was 8.3 g of dimethylchlorosilane, the addition amount of toluethylamine was 18.2 g, and α-acryloxymethyldimethylsilanol was γ.
-Methacryloxypropyl dimethylsilanol 23.0g
When treated in the same manner as in Synthesis Example 1 except that
80cS, refractive index 1.4063, specific gravity 0.974 488 g of an organopolysiloxane (hereinafter abbreviated as polymer E) represented by

Examples 1 to 9 Polymers A to C and E1 obtained in the above Synthesis Examples 1 to 5
A composition was prepared by adding 0.3 to 5.0 parts of the photoinitiator shown in Table 1 to 00 parts, and the composition was poured into a sheet-shaped mold having a thickness of 2 mm and air-dried to form a sheet. When the UV irradiation device of UD-20-2 [trade name of Nippon Battery Co., Ltd.] of 2 cm was used to irradiate the UV light of the amount shown in Table 1, these were completely cured in 1 to 8 seconds. However, this cured product exhibited the physical properties as also shown in Table 1.

Example 10 Toluene Solution 10 of Polymer D Obtained in Synthesis Example 4 Above
Formula as a photoinitiator in 0 part 1.2 parts of the compound of formula (1) was added to prepare a composition, which was poured into a sheet-shaped mold having a thickness of 2 mm and air-dried to form a sheet. Then, 1.0 J / When irradiated with cm ² of ultraviolet rays, this cured in 2 seconds, and this elastic body had a hardness (JIS-A) of 5
7, the physical properties of elongation 60% and tensile strength 37 kg / cm ² were exhibited.

In addition, this composition was coated on a commercially available glass epoxy printed circuit board to a thickness of about 0.1 mm, air-dried, and then cured by irradiating with 1.0 J / cm ² of light energy. The product adheres well to the printed circuit board. This product is kept at high temperature and humidity of 50 ° C x 98% for 20 minutes.
No change was observed in the film characteristics and the adhesion even if left for 0 hours.

Claims (1)

[Claims] 1. A general formula (Here, R ¹ is a hydrogen atom or a methyl group, R ² , R ³ , R ⁴
Is the same or different unsubstituted or substituted monovalent hydrocarbon group,
a, b are organopolysiloxanes having at least one group represented by 1, 2 or 3) in the molecule 1
00 parts by weight, 2) 0.01 to 10 parts by weight of a photoinitiator, and a UV-curable organopolysiloxane composition.