JPS61127718A - Curable silicone composition, manufacture and use - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to curable polyorganosiloxane (silicone) compositions, particularly for use in botting electronic circuits.

BACKGROUND OF THE INVENTION Silicones are used to pot and encapsulate electronic devices, such as integrated circuits, to provide thermal stability, low temperature flexibility, and dielectric strength. They are primarily used as elastomeric or gel-like materials to provide impact, vibration and thermal stress resistance for fragile electronic components. Regarding silicone gel encapsulating agents, see U.S. Pat.
, No. 271,425, No. 4,374,967 and Dee Dixon, Jr. (D, Dic
Kson, Jr.) by Proceep Inc. Electric Electronic Intel.

Con7. (Proceedings Electric
c/ElectronicInte1. Conf.)
12.92 (1975), respectively. Regarding prior art, U.S. Patent No. 4,374,
Please refer to the description in the specification of No. 967.

The commercially available potting silicone of the present invention cures with moisture and takes several hours to several days to fully cure, as described in U.S. Pat. No. 4,271,425. This is a one-component composition. Rapid curing is achieved at elevated temperatures by a two-part system such as that described in U.S. Pat. No. 4,087.585. but.

In binary systems requiring platinum catalysts, plasticizers such as organotin compounds, sulfur, amines, urethanes, and unsaturated hydrocarbons on the substrate surface interfere.

It is known that some silicones containing methacrylate or acrylate functionality can be cured by ultraviolet light.

U.S. Patent Nos. 4,201,808 and 4,348,4
No. 51 specifications and British patent application No. GB20392
Specification No. 87A discloses that ultraviolet rays (
UV) curable compositions. This composition does not produce a jelly-like material, ie, an elastomeric material.

(Problems to be Solved by the Invention) In other words, it is desirable to have a UV-curable silicone composition that produces an elastomer-like consistency, that is, a soft gel-like consistency when cured. Compositions that can be cured by alternative cure mechanisms would be desirable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide silicone compositions having the desired properties mentioned above. This composition
Approximately a few seconds or minutes after irradiation, the material hardens and takes on a soft gel-like consistency, that is, an elastomer.

In addition, this composition undergoes moisture curing in the shadow areas. However, moisture curing does not impair the gel-like or elastomeric properties.

The composition according to the invention is a mixture consisting of:

(a) an acrylic/dialkoxysilyl functional group or an acrylic/dialyloxysilyl functional group as a terminal group;
and 30 to 100 parts by weight of a reactive polyorganosiloxane containing 0.1 to 5 parts by weight of a silicone moisture curing catalyst.

(b) A trimethylsilyl group is used as a terminal group. O to 70
Parts by weight of silicone oil.

(c) an effective amount of a photosensitizer.

Also novel reactive polyorganosiloxanes for use in the compositions of the present invention and methods of making them.

It constitutes a part of the present invention.

(Example) The main ingredients contained in the formulation according to the present invention are acrylic
It is a polyorganosiloxane terminated with a dialkoxysilyl functional group or an acrylic diallyloxysilyl functional group. These silicones have the following formula (1
).

In the formula, R1 and R2 are an alkyl group such as a methyl group or an ethyl group, a haloalkyl group such as a 3,3,3-trifluoropropyl group, a substituted or unsubstituted allyl group such as a benzyl group or a phenyl group. further represents other groups such as vinyl, methacryloxypropyl, methoxy, mercaptopropyl, hydrogen, or benzoin, and B2 is the same group as 11 and R2 or another alkyl group. R4 represents hydrogen or an alkyl group having 1 to 5 carbon atoms, R5 represents an alkylene group, and n represents an integer of 80 to more.

R1 and R2 are preferably alkyl groups, most preferably methyl groups. Although phenyl groups are also suitable, silicones containing large amounts of phenyl groups are
Because it absorbs too much radiation, it reduces the curing rate based on the initial amount of Uψ curing.

If R1 and R2 are functional groups such as vinyl, methacryloxypropyl, or methoxy groups that can be crosslinked under UV curing or moisture curing conditions, these groups can be It is never present in an amount exceeding 2%.

To obtain suitable moisture curability, R3 is preferably an alkyl group having from 3 to less than 3 carbon atoms.To stabilize the bond in R5 against heat and hydrolysis, R5 is preferably an alkyl group having from 3 to about 3 carbon atoms. Preferably it has 10 carbon atoms.

The number of repeating units of the silicone of formula (1) should be about 80 or more units to provide the desired gel-like or elastomeric properties in the cured material. n has no theoretical limit, but preferably does not exceed 1500 repeating units.
Polymers exceeding 0.00 are difficult to process, difficult to coat, and difficult to cure.

The moisture curing catalyst used in the present invention can be any methoxysilicone moisture curing catalyst that does not have an adverse effect on the acrylic groups, such as inducing or inhibiting curing of the acrylic groups. Suitable moisture curing catalysts are organotitanate-based catalysts such as tetraisopropyl orthotitanate. The higher the amount of organotitanate catalyst, the faster the curing rate.

Therefore, the moisture cure rate is adjusted as necessary. The moisture curing catalyst is used in a proportion of 0.1 to 5% based on the amount of reactive silicone represented by formula (1).

The silicone oil used in the present invention is:

It is a trimethylsilyl terminated polydimethylsiloxane having a viscosity of about 100 to 5,000 centipoise (cp). These oils are used as plasticizers to adjust the texture and softness of the cured material, and as diluents to adjust the final viscosity of the composition. For potting compositions required for gel-like materials, the plasticizing silicone oil should be present in the range of about 30 to 70% by weight of the composition, with lower amounts of silicone oil being present. A composition is created that yields a soft rubbery material. If the amount of silicone oil is present in excess of about 70%, the material will flow even after curing.

The composition according to the invention comprises a photosensitizer. Photosensitizers that initiate curing through the action of acrylic functional groups are known in the art. Examples of these include benzoin and its substituted products, benzophenone, Michler's ketone (
Michlar's ketone), dialkoxybenzophenone, and jetoxyacetophenone.

Any known photosensitizers can be used, as well as mixtures thereof, without departing from the concept of the invention.

Further, examples of the use of such photosensitizers can be found in the above-mentioned patent specifications.

In addition, Technology Marketing Co.
UV Curing: Science and Technology J (S, P, Pappas) published in 1978 by UV Curing: 5 science a
It is described in a paper called nd Technology).

The amount of photosensitizer used in the composition according to the invention is from 0.1 to 5% relative to the composition. However, depending on the properties of the photosensitizer, even if the amount is outside this range,
They can be used without departing from the concept of the present invention, as long as they exhibit the ability to quickly and effectively initiate the polymerization of acrylic groups.

The photosensitizing component can also be a polymer bonded as part of the R1 or R2 group of the reactive silicone, for example of formula (1). For polymer-bonded photoinitiators and techniques for producing them, see U.S. Pat.
No. 71,425. Those skilled in the art of this synthesis will appreciate that polymer-bonded silicones having dialkoxyacrylic functional groups as terminal groups can be prepared and used with appropriate modifications to the scale technique.

The compositions according to the invention can contain other additives as long as they do not interfere with the UV curing and moisture curing action. Examples of such additives include 2゜3-epoxypropyltrimethoxysilane, triallyl-8-triazine-
2,4,6(LH,3H,5H)-trione, and others known to those skilled in the art, such as adhesion promoters,
silica.

There are fillers such as micro balloon glass.

Examples of fillers useful for improving the texture of compositions according to the invention are described in U.S. Pat. No. 4,072,635 from column 4, line 40 to column 5Ii, line 7. ing. If applied to electronic devices, the additive should not include ionic species.

Ion trapping compounds such as crown ethers and Cryptata are useful in reducing ionic conductivity when used in electronic circuits.

Examples of these are 18-crown-6, 12-crown-4, and 15-crown-5. Reference is made to US Pat. No. 4,271,425, which describes the use of crown ethers in naturally vulcanized (RTV) silicone encapsulants.

The reactive silicone represented by formula (1) is represented by the following formula (2)
It is indicated by. Easily made from silanol-terminated silicones.

p! In the formula, R1 and R2 are the same as the groups defined in formula (1).

Silanol-terminated dimethylsiloxanes having viscosities of about 500 to so, ooo centipoise yield reactive silicones in the desired molecular weight ranges previously discussed. Approximately 600 pieces of soft gel-like hardware for potting
Silanol-terminated dimethylsiloxanes having a viscosity of from 20,000 centistokes (cst) to 600 to 4,000 centistokes are preferred, and more preferably from 600 to 4,000 centistokes (cst).
It is in the range of 0 centistokes.

The silanol represented by the formula (2) reacts with the silane compound represented by the following formula (3).

In the presence of a condensation catalyst such as an organotitanate, where R3, R4 and R5 represent the same groups as defined in formula (1), a reactive silicone of formula (1) is produced. Methacryloxytrimethoxysilane is a suitable compound represented by Formula 1 (3) because it is commercially available and both the alkoxy group and the acrylic group are highly reactive.

The molar ratio of silane to silanol-terminated siloxane is from 2 to 6 (1 to 3 moles of trialkoxysilane per equivalent silanol hydroxyl) relative to the number of moles of silanol of formula (2). (3)
As the molecular weight of the silanol increases, as the molecular weight of the silanol increases, a gel-like or toffee-like material is produced, which cannot be used in the present invention. A slight increase in the minimum concentration of silane was observed. Therefore, when using a silanol-terminated dimethylsiloxane with a molecular weight of 28 L 000, a ratio of at least 2.2:1 is preferred, whereas for a silanol-terminated dimethylsiloxane with a molecular weight of 12,000, A ratio of 2:1 is sufficient.

Titanate catalyst is added in the range of 0.1 to 5% by weight. A preferred catalyst is tetraisopropanol titanate. The catalyst and the reactant react at a temperature in the range of 10°C to 200°C, preferably in the range of 60°C to 120°C. R”O liberated from reaction with silane
Vacuum is applied during or after the reaction to remove substantially all of the stoichiometric amount of H.

Before or after the reaction of the silicone represented by formula (2) and the silane represented by formula (3), silicone oil and a photopolymerization initiator, which are components of the composition of the present invention, are added to 1
Add to the composition. After reaction, the concentration of titanate catalyst is adjusted to alter the moisture curing properties of the composition.

Compositions according to the invention primarily produce slightly softer samples when comparing moisture curable samples and UV curable specimens of the same composition. Moisture curing is usually complete within 24 to 72 hours. After curing with UV or after completion of moisture curing, the samples show no appreciable advanced curing with respect to long-term aging.

The physical properties of the cured product obtained from a given composition are:
It depends on the molecular weight of the reactive silicone represented by formula (1), as well as the curing method and amount of oil used. In general, the higher the molecular weight of the reactive silicone, the softer the cured product and the slower the curing rate.
The proportion of oil that gives a free-flowing cured product is 70
% is slightly lower than %.

Hereinafter, preferred embodiments of the present invention will be described in detail based on experiments.

50.0 g of hydroxyl-terminated polydimethylsiloxane (0.3% by weight hydroxyl), 2.62 g of methacryloxypropyltrimethoxysilane, and 0.0 g of hydroxyl-terminated polydimethylsiloxane having a viscosity of 680 centistokes, 2.62 g of methacryloxypropyltrimethoxysilane, and .21 g of tetraisopropylorthotitanate was placed in a round bottom flask.
The reaction was carried out for 2 hours using a single rotary evaporator while maintaining the pressure at 10-10 g and the temperature at 80°C. During the first hour, the viscosity of the mixture increases; during the second hour.

It decreased. Approximately 0.5m at 80℃ for another 4 hours
A near full vacuum of mHH was maintained. The flask was removed from the evaporator and flushed with nitrogen. The silicone produced by the reaction was a yellow liquid.

This product is then used to have a viscosity of 100 centistokes or 1,000 centistokes.

A mixture containing trimethylsilyl-terminated silicone was prepared. This mixture was made to have a silicone oil content ranging from O to 90%. For each of these mixtures, 2
% by weight of jetoxyacetophenone was added. Approximately 6.4 mm (1/4 inch) thick samples of these compositions were cured with approximately 70,000 μIt/aJ of UV light for 1 to 2 minutes or at ambient temperature and humidity. Curing was performed for 24 hours. When the oil content is above about 70%, curing is very difficult and it has not been possible to obtain a non-flowing product by moisture curing. Samples containing oil in the range of 0 to 70% showed some degree of creep but did not flow, ranging from soft rubber-like (hardness 10 to tS by Shore A hardness tester) to extremely The hardness ranged from soft adhesive gel-like properties (unmeasurable with a Shore A hardness meter).

50.0 g of hydroxyl-terminated polydimethylsiloxane (molecular weight 28,000) with a viscosity of 3.500 centistokes, i, os g of methacryloxypropyltrimethoxysilane, and 0 The same synthesis procedure as in Example 1 was carried out using .20 g of tetraisopropyl orthotitanate. The product was a thick liquid. When this product sample was mixed with 2% jetoxyacetophenone and cured by UV irradiation at 70,000 μV/cm, a soft rubber-like product with high elasticity was obtained. Another sample was cured for 2.5 days at ambient temperature and humidity, resulting in a slightly softer rubber.

Using 101.7 g of silanol-terminated dimethylsiloxane having a viscosity of 20.000 centistokes, 2.6 g of methacryloxypropyltrimethoxysilane, and 0.3 g of tetraisopropylorthotitanate, Methacryloxypropyl was added to the resulting mixture in the same manner as in Examples 1 and 2, except that a trimethylsilyl-terminated silicone oil having a viscosity of io centistokes was added before heating. Dimethylsiloxane terminated with dimethoxysilyl groups was prepared. The resulting product had a viscosity of 21,200 centipoise.

Next, 21. 3, with a viscosity of Zoo centipoise
0.05 g of product was mixed with 0.6 g of silicone oil having a viscosity of 100 centistokes and 0.07 g of dimethoxyacetophenone. Cono composition containing 58% oil has approximately 70,000 μ#/cva2 (
7) When UV was irradiated for 60 seconds, the diameter was 1.6 mm (
It hardened into a soft gel to a depth of 1/16 inch).

193.8 g with a viscosity of 21.200 centipoise
4 having a viscosity of 100 centistokes
5g of silicone oil and 5g of dimethoxyacetophenone were mixed. 3. :'II+++
Pour into + (1/8 inch) thick open mold for 6 times at 20 second intervals, cooling after each interval.

It was cured by irradiating UV with the same intensity as before.

The sample was then moisture cured overnight and then io
A 2 cm square (4 inch x 4 inch) test piece was removed from the mold, turned over once, and the bottom surface was irradiated with UV three times at 20 second intervals to weaken the adhesiveness. When an electrical test was conducted on a 10.2 cm square (4 inch x 4 inch) test piece, the results shown in the following table (2) were obtained.

Claims (10)

[Claims] (1) A composition curable by both moisture curing and UV curing mechanisms, the composition comprising: (a) an acrylic/dialkoxysilyl functional group or an acrylic/dialyloxysilyl functional group as a terminal group; and (b) 0 to 70 parts by weight of a silicone oil terminated with trimethylsilyl groups; , (c) an effective amount of a photosensitizer, and the polyorganosiloxane has the formula ▲ mathematical formula, chemical formula, table, etc.
and these groups do not crosslink by more than 2% under UV or moisture curing conditions, and n represents an integer. ) silanol-terminated silicone with a viscosity of 500 to 50,000 centipoise, and the formula ▲ mathematical formula, chemical formula, table, etc. ▼ (where R^3 is the same or different alkyl group) ,
or represents an allyl group, R^4 represents hydrogen or an alkyl group having 1 to 5 carbon atoms, and R^4 represents an alkyl group having 1 to 5 carbon atoms;
5 represents an alkylene group. ) acrylic
It is a product produced by reacting trialkoxysilane or acrylic triallyloxysilane in the presence of a condensation catalyst with a molar ratio of the silane to the silanol ranging from 2:1 to 6:1. A curable silicone composition characterized by: (2) (a) All R^3OH produced by the reaction of silanol and silane is substantially removed. (b) The photosensitizer is selected from the group consisting of substituted or unsubstituted benzoin, benzophenone, dialkoxybenzophenone, Michler's ketone, and diethoxyacetophenone. (c) The organo group R^1 or R^2 in the silicone having a silanol group as a terminal group contains a photosensitizing group, preferably a benzoin group or a benzoin ether group, and the organo group contains a photosensitizer. It consists of ingredients. (d) The silicone having a silanol group as a terminal group is about 6
00 to 20,000 centistokes, preferably 6
It has a viscosity ranging from 0.00 to 4,000 centistokes. (e) The molar ratio of silane to silanol is in the range of 2:1 to 2.5:1. The curable silicone composition according to claim (1), which has one or more of the above characteristics. (3) Any one of claims (1) and (2) characterized in that it contains a silicone oil having a viscosity of 100 to 5,000 centipoise and having a trimethylsilyl terminal group. The curable silicone composition described. (4) The curable silicone composition according to any one of claims (1) to (3), characterized in that silicone oil is contained in a range of 30 to 70%. (5) Claims (1) to (4) characterized in that the moisture curing catalyst comprises an ortho titanate catalyst.
) The curable silicone composition according to any one of the above items. (6) The molecular weight of the reactive polyorganosiloxane is 12
,000 to 50,000, the curable silicone composition according to any one of claims (1) to (5). (7) The curable silicone composition according to any one of claims (1) to (6), further comprising an adhesion promoter or an ion trapping compound. (8) A method for producing a reactive silicone that can be cured by moisture and free radicals, the method comprising: (a) Formula ▲ Numerical formula, chemical formula, table, etc. represents,
and these groups do not crosslink by more than 2% under UV or moisture curing conditions, and n represents an integer. ), 500 to 50,00
There are silanol-terminated silicones with a viscosity of 0 centipoise and formulas ▲mathematical formulas, chemical formulas, tables, etc.▼ (wherein R^3 is the same or different alkyl group,
or represents an allyl group, R^4 represents hydrogen or an alkyl group having 1 to 5 carbon atoms, and R^4 represents an alkyl group having 1 to 5 carbon atoms;
5 represents an alkylene group. ) or acrylic triallyloxysilane, and the molar ratio of the silane to the silanol is 2:
(b) the theoretical amount of R produced by the reaction;
A method for producing a curable silicone, comprising the step of substantially removing all of ^3OH. (9) The ratio of silane to silanol is 2:1 to 2
．． The method for producing curable silicone according to claim 8, characterized in that the ratio is in the range of 5:1. (10) (a) acrylic/dialkoxysilyl functional group,
or 30 to 100 parts by weight of a reactive polyorganosiloxane terminated with an acrylic diallyloxysilyl functional group and containing 0.1 to 5% silicone moisture curing catalyst; 0 to 70 parts by weight of silicone oil, and (c) an effective amount of photosensitizer, and the polyorganosiloxane has the formula, 1 and R^2 represent an organo group,
and these groups do not crosslink by more than 2% under UV or moisture curing conditions, and n represents an integer. ), 500 to 50,00
There are silanol-terminated silicones with a viscosity of 0 centipoise and formulas, ▲mathematical formulas, chemical formulas, tables, etc.▼ (wherein R^3 is the same or different alkyl group,
or represents an allyl group, R^4 represents hydrogen or an alkyl group having 1 to 5 carbon atoms, and R^4 represents an alkyl group having 1 to 5 carbon atoms;
5 represents an alkylene group. ) acrylic
consisting of a product formed by reacting a trialkoxysilane or an acrylic triallyloxysilane with a molar ratio of said silane to said silanol ranging from 2:1 to 6:1 in the presence of a condensation catalyst. A method of using a curable silicone composition comprising: using the curable silicone composition for potting an electronic circuit.