JPS6047024A - Silicone conformal coating - 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 BACKGROUND OF THE INVENTION This invention relates to protective silicone sawing compositions and articles coated with the compositions. More particularly, the present invention provides (1) R3S i O(,,5 units and 5i0
The present invention relates to a silicone composition comprising the reaction product of a two-unit hydroxy-containing resin copolymer and (2) a monoorganopolysiloxane containing a terminal silicon-bonded hydroxy group. In addition, the present invention relates to articles coated with compositions as described above, as well as methods of protecting articles such as electrical and electronic devices by coating such articles with the compositions of the present invention.

In recent years, advances in the field of electrical and electronic engineering have provided highly complex semiconductor circuits that can be integrated into smaller and smaller areas than was previously possible1. Minimize physical damage and reduce heat
Great demands are placed on electrical insulators to maximize the resistance of the system to harsh environmental conditions such as low temperatures and humidity.

Some of the more useful insulating materials currently in use include greases, resins, and silicone compositions such as room temperature curable polysiloxanes. Although such silicone compositions provide the desired protection for sensitive electrical and electronic components, once installed, the entire coating may be removed for repair or maintenance of the component. has the disadvantage that it is almost impossible to remove some parts.

Silicone compositions made from hydroxy chain-terminated linear diorganopolysiloxanes and MQ resins have been described in the literature in the area of pressure sensitive adhesive All and room temperature curable (RTV'') H compositions. To the best of my knowledge, no material has yet been found that is durable and can be removed with a solvent.

Accordingly - C2 It is an object of the present invention to provide a solvent removable composition for protecting electrical and electronic equipment from harsh environmental conditions and further to enable repair and maintenance of electronic components and circuits such as these. It is to provide.

Other objects and advantages of the invention will become apparent from the detailed description below.

SUMMARY OF THE INVENTION The present invention provides novel silicone conformal coating compositions, methods of protecting electronic and electrical components using such compositions, and articles having such compositions cured onto their surfaces. do.

In summary, in its broadest sense, the Noricone Conformal Coach Inc. of the present invention includes:
(1) about 55 to 70 parts by weight of an organoborisiloxane which is a cohydrolysis product of a hydrolyzable trialkylsilane and an alkyl silicate or sodium silicate; and (2) a silicon-terminated organoborisiloxane. 30 to 45 parts by weight of a linear diorganopolysiloxane fluid having bound hydroxy groups, comprising the cocondensation reaction product of said hydrolyzable silane and said silicate ester or salt. Hydrolysis pJ capacity q Shira 75gJ per mole
0.33 to about 0.55 moles are reacted, and the alkyl group has a maximum of 4 carbon atoms. Further, the organic group in the diorganopolysiloxane is an alkyl group or an aryl group.

alkaryl group, aral, kyl group, 71071J −
selected from the group consisting of # groups, alkenyl groups, and mixtures thereof, wherein the diorganopolysiloxane is
from about 200,000 centipoise to about 2, o o o,
It has a viscosity of o o centipoise.

DESCRIPTION OF THE INVENTION The present invention provides novel silicone compositions that are solvent removable and exhibit primerless adhesion to a wide variety of substrates.

Typically, such a composition is a co-condensation reaction product of a mixture containing all of the following (1) and (2).

m R3S: LOo, 5 units (M units) and 5i02
About 55-70 parts by weight of a hydroxy-containing resin copolymer consisting of units (Q units) and 60-65 parts by weight of the hydroxyl-containing resin copolymer. Here, R3S i O (the ratio of 1,5 units to 5102 units is about 036 to 0.55:1, preferably 0.35 to 0,
45:1, and R is an alkyl group, preferably an alkyl group having up to 4 carbon atoms and 2.

(2) about 30 to 45 parts by weight, preferably 35 to 40 parts by weight of a hydroxy-terminated diorganopolysiloxane having an average of about 2 populated groups per silicon atom; , the organic group is selected from the group consisting of alkyl groups, aryl groups, alkaryl groups, aralkyl groups, haloaryl groups, alkenyl groups, and mixtures thereof, and the diorganopolysiloxane has a temperature of about 200.
000 centipoise to about 2,000,000 centipoise. However, the total of (1) and (2) above is equal to 100 copies.

R35iOo, 5 units and 5i0 used in the practice of the present invention
Two-unit resin copolymers are well known in the art and are described in US Pat. No. 2.857.356, Dauclt et al., U.S. Pat. Are listed. All of these patents are incorporated by reference into this disclosure. Although a variety of methods can be used to produce M'Q resins such as those described above, the patentability of this invention is not dependent upon the particular method of producing the resin copolymer.

Jr. U.S. Patent No. 2.857. MQ resins prepared according to the method of , i5''6 have been found to be particularly preferred since hydroxy-containing resins can be obtained directly from them. The co-hydrolysis of an alkyl acid or sodium silicate involves adding the hydrolyzable trialkylsilane and the alkyl or sodium silicate to all suitable solvents, followed by adding a sufficient amount of water. In addition, the desired co-hydrolysis and co-condensation can take place. Most preferably, trinotylylrollosilane and ethyl orthosilicate are used to obtain the hydroxy-containing MQ resin. Of course, hydrolyzable The ratio of silane to silicate ester (or salt) is approximately 0.33 to 0.000% per unit of 5i02.
A resin copolymer containing 55 R3S i Oo, 5' units should be obtained.

Briefly, MQ resin is obtained as follows.

That is, the two components are dissolved in a suitable solvent such as toluene, xylene or an aliphatic hydrocarbon, and the mixture is then added to water maintained at a temperature of the order of 60-85°C with stirring. The resulting two-phase system is then treated to remove the water-alcohol layer and the resin material is neutralized with an appropriate amount of sodium bicarbonate or other alkaline material. The resin solution is then filtered and If necessary, add the appropriate solvent (2) to adjust the resin solids content to the desired concentration. For further details or additional information, please refer to the above-mentioned patents.

Regardless of the method of producing the resin copolymer, the alkyl groups are preferably lower alkyl groups such as methyl, ethyl, propyl and butyl. Does higher alkyl group hydrolyze silane? This is undesirable because it causes co-condensation with silicic acid esters (or salts) which slows down and gives rise to undesirable products. However, such alkyl groups may be the same or different alkyl groups. In order to obtain optimum properties such as toughness, tensile strength and non-stick properties, the M units in the final product should be between about 0.53 and 9 per Q unit.
It is also important that the value be 0.55.

The diverticulate, high viscosity organopolysiloxane used for co-reaction with the hydroxy-containing MQ resin must necessarily have terminal silicon-bonded hydroxy groups to facilitate copolymerization with the resin. Must be. Such organopolysiloxanes may also be prepared by any known method, e.g. by acid- or alkali-catalyzed polymerization of the corresponding cyclic nitrogenoxanes. ″′
Leaf US hour 1? 'F 2.857.356, is well known in the art. Gutdwin, Jr.'s method involves the use of a small amount of rearrangement catalyst, such as potassium hydroxide.
Cyclic organopolysiloxa/ in the presence of X from 125°C
I would like to heat the JFI to a temperature of 150℃.

Typically, the polymerization produces a high molecular weight product, preferably about 75%
000-125. ．． Run for a sufficient time to obtain a product with a viscosity in the range of 0'OO centipoise. Once such polymerized product is obtained, the molecules of the organopolysiloxane are treated to bear terminal silicon-bonded hydroxy groups for co-reaction with the hydroxyl groups of the resin. For this purpose, steam can be blown through the polymer surface. However, this reduces the viscosity of the polymer and at the same time increases the silanol content of the organopolysiloxane. Although it is possible to use siloxane, it is possible to
Reheated to a temperature of 150°C: 2'00.000~2.
Preferably, a material having a viscosity of 0.000.000 centipoise is obtained. The preferred range of viscosity is 40D, 00
0 to so o, o o centipoise. Once the desired viscosity is achieved, the organopolysiloxane should be treated to completely deactivate the siloxane rearrangement catalyst.

t bonded to the silicon atom of diorganopolysiloxane
′! ! The groups include alkyl groups such as methyl, ethyl, propyl, butyl and isobutyl, aryl groups such as phenyl and naphthyl, alkaryl groups such as phenyl and naphthyl,
Selected from the group consisting of xylyl and ethylphenyl, aralkyl groups such as benzyl and phenylethyl, halo7'J-yl groups such as talolophenyl, tetratalolophenyl and difluorophenyl, and alkenyl groups such as vinyl and allyl. Mixtures of the foregoing groups are also intended to be within the scope of this invention. Preferred organic groups are alkyl groups selected from methyl, ethyl, propyl and butyl, with methyl being most preferred.

MQ resin and diorganopolysiloxane are used to make silicone conformal coach-in f Mi Paraboloid'f: Made from HA! +'i is relatively simple. That is, it is sufficient to simply mix the two components and heat the mixture to cause cocondensation. In practicing the present invention, care must be taken to maintain a resin to organopolysiloxane ratio within the range of 122 to 2.33:1. If more organopolysiloxane is used, the final product will not be too sticky; if more MQ resin is used, the final product will be too brittle.

For co-condensation of the resin and organopolysiloxane, the resin is heated to a temperature of, for example, about 100-150°C for 05-6 hours.
That is, heating is performed until a product with the desired properties is obtained. After obtaining the appropriate material, the product is dissolved in a solvent such as toluene,
Dissolved in xylene, aliphatic hydrocarbons or halogenated aliphatic hydrocarbons to a convenient solids content, for example 10-50%.

The amount of solvent in the mixture can vary within a wide range. This is because the function of the solvent is to facilitate the handling of the conformal coating composition; That's why.

The present invention further provides a method for protecting electrical and electronic components from harsh environmental conditions, which method comprises applying the composition of the present invention as a coating having a thickness of 0.00254 to 0.254 mm as described above. It consists of applying to electronic devices. Through the disclosure herein, electrical and electronic devices, parts,
The terms apparatus and the like are used interchangeably and are meant to include, but are not limited to, devices such as circuits, transistors, diodes, resistors, capacitors, and the like. After applying the formulation to the apparatus or device by conventional means such as spraying, brushing, and dipping, the formulation is air-dried (
air dry) and then continue to dry at a temperature ranging from 75 to 150°C for 10 to 10 minutes.
Dry in the oven for 60 minutes.

Optionally, a catalyst or curing agent is included in the composition. Preferred such curing agents are peroxide catalysts, such as benzoyl peroxide or dichlorobenzoyl peroxide, at concentrations of 1 to 2 parts based on the silicone content of the coating composition. Any organic peroxide present in an amount ranging from 30 parts by weight is of course effective.
Any suitable catalyst may be used. The catalyst is mixed into a solution of a 10-50% solids conformal coating composition during application. The solution is then applied to the desired electronic components, after which the coated components are air dried and then heated to a temperature of about 75-15o C. If for 10-60 minutes. to completely evaporate the solvent and cure the conformal coating composition.

Prior to increasing the air temperature to activate the peroxide,
The solvent must be removed.

Articles thus formed are useful for protecting electronic and electrical components from harsh environmental conditions, such as heat, heat and humidity, and at the same time against mechanical damage caused by agitation or compression of the equipment. It is valid. Composition of the invention? An important advantage of its use in electronic components, such as stepboards, is that the composition can be easily removed on exposure to solvents such as toluene, xylene or aliphatic hydrocarbons. That is, if the coated article is not working properly, the silicone conformal coating composition can be removed in whole or in part to facilitate repair of the electronic device or circuit. It has become possible to access such coated electronic devices not only for general purpose purposes, but also for routine maintenance as needed.

The compositions of the present invention are primarily intended for use in protecting and insulating electronic and electrical equipment.
Other parts, devices, substrates, etc. that may be protected with the silicone conformal coating compositions of the present invention are also within the scope of the present invention.

Claims (1)

[Claims] (1) (a) R35iOo, s units and 5i02
About 55 to 70 parts by weight of a hydroxy-containing resin copolymer consisting of R35iO0,5 units to 5
The ratio of i02 units ranges from about 0.35 to 0.55:1, where R is an argyl group or a mixture of alkyl groups), and (+)) hydroxy-terminated diorganoporin 1 coxane. 30 to 45 parts by weight (provided that the organic group of the diorganopolysiloxane is selected from the group consisting of an alkyl group, an aryl group, an alkaryl group, an aralkyl group, a haloaryl group, an alkenyl group, and a mixture thereof; The polysiloxane has a viscosity in the range of about 200, OD D centipoise to about 2, (10,000 centipoise) at 25°C (provided that the maxims of (a) and (b)) is 1
00 parts). (2) The amount of hydroxy-containing resin copolymer is about 60
The composition of claim 1, wherein the amount of 1-, hydroxy-terminated diorganopolysiloxane varies from about 35 to 40 parts by weight. (3) The ratio of R3S10o, 5 units to 5i02 units is in the range of about 0.35 to about 0.45:1 k%
A composition according to claim 1, characterized in that: 4. A composition according to claim 1, wherein the hydroxy-containing resin copolymer is a reaction product of a hydrolyzable trialkylsilane and an alkyl silicate or a sodium silicate. (5) The composition according to claim 4, characterized in that the hydrolyzable trialkylsilane is destroyed by trimethylchlorosilane. (6) The composition according to claim 4, wherein the alkyl silicate is tetraethyl orthosilicate. C7) R3S 100 , the alkyl group of 5 units is methyl. A composition according to claim 1, characterized in that it is selected from the group consisting of ethyl, propyl, butyl and mixtures thereof. (81R3S i 00.5 The composition according to claim 1, wherein the alkyl group of the unit is a methyl group. (9) The organic group of the diorganopolysiloxane is methyl,
Composition according to claim 1, characterized in that it is selected from the group consisting of ethyl, propyl, butyl and mixtures thereof. (IL) The composition according to claim 1, wherein the organic group of the diorganopolysiloxane is a methyl group. The viscosity of α diorganopolysiloxane is approximately 4 at 25℃.
00. A composition according to claim 1, characterized in that it is in the range of OOO centipoise - about 800,000 centipoise. 0'1. (of (OHa) + EIiOo, about 60 to 65 parts by weight of a hydroxy-containing resin copolymer which is the reaction product of citrimethylchlorosilane and tetraethyl orthosilicate or sodium silicate, consisting of 5 units and 8102 units)
(CH3)3SiO0,5 units to SiO2 units ratio is in the range of about 035-045:1), and (b) linear hydroxy-terminated dimethyl polysiloxane about 35-40 times The viscosity of borynroxane is in the range of about 400,000 to about so,ooo centipoise at 25°C (however, the mixture of (a) and (b) has a viscosity of about 10
0 parts) of cocondensation reaction products. A method for soaking an article having a conformal coating in α4 Table 1ω, comprising: (a) (1) R3S i 00.5 units and 81
about 55 to 70 parts by weight of a hydroxy-containing resin copolymer consisting of 02 units, where the ratio of R3S i Oo,s units to 5i02 units ranges from about 0.33 to 0.55:1, where R is (2) 30 to 45 parts by weight of hydroxy-terminated diorganopolysiloxane (where the organic group of the heel diorganopolysiloxane (i.e., an alkyl group, an aryl group, an alkaryl group, The diorganopolysiloxane has a viscosity at 25°C ranging from about 200 to 2,000 centipoise to 2,000 centipoise to 2,000 centipoise. (However, the total of (1) and (2) is 10
(b) curing said composition to said substrate. α→ The amount of hydroxy-containing resin copolymer is about 60~
14. The method of claim 8g13, wherein the amount of hydroxy/-terminated diorganoboria xane varies from about 65 to 40 parts by weight. 14. The method of claim 13, wherein the ratio of α5 R3s lOo, 5 units to 5i02 units is in the range of about 0.35 to about 0.45:1. (IQ) Process according to claim 13, characterized in that the hydroxy-containing resin copolymer is a reaction product of a hydrolysable trialkylsilane and an alkyl silicate or a sodium silicate. The method according to claim 16, characterized in that the decomposable trialkylsilane is trimethylchlorosilane. Claim 16, characterized in that the alkyl silicate is tetraethyl orthosilicate. (19J) wherein the alkyl group of the R35iO0,5 unit is selected from the group consisting of methyl, ethyl, propyl, butyl and mixtures thereof. Method. (a): Claim 13, characterized in that the alkyl group of the R3S i Oo, 5 unit is a methyl group.
The method described in section. Q]) The organic group of diorganopolysiloxane is methyl,
14. A method according to claim 13, characterized in that it is selected from the group consisting of ethyl, propyl, butyl and mixtures thereof. (c) The method according to claim 13, wherein the organic group of the diorganopolysiloxane is a methyl group. (c) The viscosity of the diorganopolysiloxane at 25° C. is about 400,000 to about 800. O[11
14. A method according to claim 13, characterized in that it is in the range of 3 centipoise. (c) The method according to claim 13, wherein the substrate having the co/formal coating ζ on its surface is an electrical or electronic component. (c) about 0.00254 to about 0 coatings,
14. A method according to claim 13, characterized in that it is applied to the substrate as a layer having a thickness in the range of 254 wn. (c) Curing of the composition is carried out by (bl) air drying for approximately 10 to 60 minutes, and (b2) subsequent oven drying at a temperature in the range of 75°C to 150°C for approximately 10 to 60 minutes. 14. The method according to claim 13. (a) The method according to claim 8g13, characterized in that curing is carried out in the presence of a catalyst. (c) The method according to claim 27, wherein the catalyst is an organic peroxide. (c) The organic peroxide catalyst is present in an amount ranging from 0.01 to 5.0% by weight.
The method described in section. Country: The catalyst is selected from the group consisting of benzoyl peroxide and dichlorobenzoyl peroxide. 30. The method of claim 29, characterized in: (3) The method of claim 60, wherein said catalyst is present in an amount ranging from about 10 to 2.0% by weight. (3) Curing is carried out by air drying for about 10 to 60 minutes, and then heating the coated article for 10 to 60 minutes at a temperature of about 5°C to about 150°C. 03. A method of manufacturing an article having a solvent-removable coating on a surface, the method comprising: (a) (1) (CH3)3SiOO, 5 units and E1
about 60 to 65 parts by weight of a hydroxy-containing resin copolymer consisting of 102 units and being the reaction product of trimethylchlorosilane and tetraethyl orthosilicate or sodium guinate, provided that the ratio of (C1H3)319 i 00.5 units to 5i02 units (2) a linear hydroxy-terminated dimethylpolysiloxane having a viscosity of about 35 to 40% (with the viscosity of the dimethylpolysiloxane ranging from about 4 to 40% at 25°C); 00.000 centipoise ~ approx. 80
in the range of 0.000 centipoise) (where the sum of (1) h and (2) is equal to 100 parts). Approximately 0.00254++l after applying
+11 to about 0.254 mm (7) in the presence of 10 to 2.0% by weight of a catalyst selected from the group consisting of benzoyl peroxide and dichlorobenzoyl peroxide; A method comprising curing the composition onto the substrate by air drying for 10 to 60 minutes followed by heating to a temperature in the range of about 75°C to about 150°C for about 10 minutes to about 60 minutes. (3→ (a) An article comprising: (a) a substrate; and (1)) a coating composition cured on at least one side of the substrate, the composition comprising: (1) R3Si Oo, 5 units and 8102 units. about 55 to 70 parts by weight of a hydroxy-containing resin copolymer consisting of (is a mixed proboscis of alkyl groups),
and (2) about 30 to 45 parts by weight of a hydroxy-terminated diorganopolysiloxane (provided that the organic groups of the diorganopolysiloxane include alkyl groups, aryl groups, alkaryl groups, aralkyl groups, haloaryl groups, alkenyl groups, The diorganopolysiloxane selected from the group consisting of mixtures of these materials has a viscosity at 25°C ranging from about . (However, the total of (1) and (2) is 10
An article consisting of 0 parts (tζ equal) of a cocondensation reaction product. 0→ The amount of hydroxy-containing resin copolymer is about 60~
35. The article of claim 34, wherein the amount of hydroxy-terminated diorganopolysiloxane varies from about 35 to about 40 parts by weight. QQ R35iO0,6 unit to 5i02 unit ratio is approximately 0
35. Article according to claim 34, characterized in that it is in the range of 35 to about 0.45:1. 071 Article according to claim 3A, characterized in that the hydroxy-containing resin copolymer is a reaction product of a hydrolysable trialkylsilane and an alkyl or (sodium silicate) silicate.09 Hydroxylation Claim 37, characterized in that the decomposable trialkylsilane is a trialkylsilane.
Articles listed in section. 09) The article according to claim 37, wherein the silicon alkyl is tetraethyl orthosilicate. Article according to claim 34, characterized in that the alkyl group of the ('10) R3S i 06.5 unit is selected from the group consisting of methyl, ethyl, propyl, butyl and mixtures thereof. . (4]) 71. that the alkyl group of R35iO0,5 unit is a methyl group. Claim 34 with J feature
L as described in section: Goods. (4) The organic group of diorganopolysiloxane is methyl,
35. Article according to claim 34, characterized in that it is selected from the group consisting of ethyl, propyl, butyl and mixtures thereof. 03. The article according to claim 34, wherein the organic group of the diorganopolysiloxane is a methyl group. 0 → The viscosity of diorganopolysiloxane is about 4 at 25℃
35. The article of claim 34, wherein the article is in the range of 0.000,000 centipoise to about 800,000 centipoise. (c) Conformal coating on the surface f! : The article according to claim 34, wherein the substrate is an electric or electronic component. 35. The article of claim 34, wherein the coating is applied to a substrate as a layer having a thickness in the range from about 0.00254 mm to about 0.254 mm. 134. The article of claim 134, wherein the composition is removed with a solvent. 47. An article according to claim 47, characterized in that the article comprises: (a) an electrical or electronic component; and (b) a coating composition cured on at least one side of the component, the coating comprising: The composition includes fl) l'cH3')3sioo, s units and 5i02
about 60 to 65 parts by weight of a hydroxy-containing resin copolymer which is the reaction product of trimethylchlorosilane and tetraethyl orthosilicate or sodium silicate, consisting of units, provided that the ratio of (CH3)3El i Oo,s units to 5i02 units (2) about 35 to 4 parts by weight of a linear hydroxy-terminated dimethylpolysiloxane (with the viscosity of the dimethylpolysiloxane: 25°C); from about 400.000 centipoise to about 1300.000 centipoise) (provided that the sum of (1) and (2) is 10
0 parts) of a cocondensation reaction product.