JPH0258295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to self-bonding silicone rubber compositions and, more particularly, to methods of adhering such compositions to substrates.

Platinum-catalyzed compositions for Si--H olefin addition are well known. Such compositions generally include a vinyl-containing polysiloxane polymer as the base polymer, and the base vinyl-containing polymer is supplemented with a reinforcing filler such as fumed or precipitated silica or a volume-enhancing filler such as fused silica. A filler is introduced as a filler. Vinyl-containing silicone resins may also be used in conjunction with or in place of reinforcing fillers. Such mixtures are generally stored separately. The crosslinking portion of the composition comprises a hydride siloxane, which may be either a hydride-containing polysiloxane or a hydride-containing silicone resin. A platinum catalyst is used to accelerate curing. Various other ingredients can be added to the composition to enhance the physical properties after curing, for example, a low viscosity vinyl-containing polymer can be added to the composition. The platinum catalyst may be combined with the basic vinyl-containing polymer and filler, or may be incorporated with a hydride siloxane crosslinker. When curing of the composition is desired, the two inclusions or components are mixed together and the mixed composition is applied in the desired manner and cured at room temperature or higher to form the silicone elastomer. to form.

Known inhibitors can also be incorporated into such compositions, such as, for example, acetylenic compounds and other types of compounds that inhibit and inhibit the room temperature curing of the compositions. When such inhibitor-inhibited compositions are heated to elevated temperatures, ie, temperatures above 100° C., the effectiveness of the inhibitor is destroyed and the compositions rapidly cure to form silicone elastomers within minutes. Such inhibitors are used in such SiH-olefin platinum catalyst compositions to improve pot life after mixing the two inclusion components and before curing.

Also, one-component SiH-olefin platinum-catalyzed silicone rubber compositions have been developed, which use hydroperoxy compounds as inhibitors, which are very effective, so the compositions are It can be kept in one package for a long period of time, and when exposed to high temperatures, it hardens within a few minutes to form a silicone elastomer. Such compositions are described, for example, in U.S. Pat. No. 675,377 to William J. Bobear, “Inhibitor for Platicum Catalyzed
Silicone Rubber Compositions (Inhibitors for Platinum Catalyzed Silicone Rubber Compositions).

Such SiH-olefin platinum catalyzed compositions have great utility, for example, in the preparation of silicone molds, paper release coatings or capsule encapsulations.
However, these compositions either have good release properties that make them very suitable for paper release applications and silicone molds, or they lack adhesion to the required bonding surfaces, making them highly suitable for encapsulation and potting applications. It is somewhat difficult to use it for purposes such as sealing, protective burial, etc. For potting applications, it is often desirable to pot or encapsulate the electrical circuit with a silicone composition to protect the electrical circuit from dust, moisture and mechanical shock. Transparent SiH-olefin platinum catalyzed compositions have been developed for such potting and encapsulation applications, and therefore, if there is a malfunction within an electrical circuit, engineers can I was able to see the circuit through the lens and determine the corrective action to take.

Other relevant properties of such SiH-olefin platinum catalyzed compositions for potting and encapsulating electrical circuits include being electrically nonconductive, ozone resistant, and weather resistant. It is water repellent. These properties make such compositions ideal encapsulating and potting materials. However, such SiH-olefin platinum catalyzed compositions still have difficulties with potting and encapsulation applications. These
SiH-olefin platinum catalyzed silicone rubber compositions do not adhere very well to electrical circuits or circuit boards due to their good release properties, and as a result, the bond formed between the silicone elastomer composition and the substrate is very weak. . Thus, from such a poor bond being formed between the silicone elastomer composition and the encapsulated substrate, the silicone elastomer encapsulant or potting compound loosens from the substrate and absorbs moisture.
They tend not to adequately protect electrical circuits from dust and mechanical shock.

To solve this problem, primers have been developed for these SiH-olefin platinum catalyzed compositions, which can be applied to metallic substrates, particularly electrical circuit boards and the circuits themselves, and thereby cured silicone elastomers. adheres to the encapsulated and potted substrate with good bonding strength. Such primer compositions are generally combinations of active ingredients dissolved in volatile solvents or solvent mixtures. The primer is applied to the encapsulating or potting substrate by wipe application or spray application. The solvent is allowed to evaporate, leaving a surface coating more suitable for bonding. A silicone rubber potting composition is applied thereon and cured to produce a silicone elastomer that provides a good bond between the silicone elastomer and the electrical circuit to be potted or encapsulated. Unfortunately, clear silicone potting compounds that use vinyl-containing silicone resins rather than fillers for reinforcement still do not adhere satisfactorily even with these primers. Examples of desirable materials for electrical circuit boards bonded by such SiH-olefin platinum catalyzed compositions include, for example, glass, aluminum, steel, copper, and stainless steel, including, of course, the metals of the electrical circuit itself. Also included. Thus, the use of such primers sometimes works effectively to bond such SiH-olefin platinum catalyzed compositions to the metal substrate with good bond strength. However, even when the primers worked well, there were problems associated with them.

First, the preparation of encapsulated or potted electrical circuit devices requires an additional step, namely the application of a primer to the substrate. Additionally, the effort required to apply the primer composition to the electrical circuit board;
The cost of the entire process increases, both in terms of the cost of manufacturing and distributing the primer composition itself. Moreover, the use of such primer compositions requires more detailed instructions than are normally required for the preparation of capsule encapsulation devices. Therefore, for such encapsulation and potting applications, SiH
- It is highly desirable to have a self-bonding additive in the olefin platinum catalyst additive composition so that no primer is required for use of the composition for encapsulation or potting of electrical circuits. It would be particularly desirable to obtain satisfactory adhesion without the use of a primer with transparent SiH-olefin platinum catalyzed compositions containing self-bonding additives. Various attempts have been made to accomplish this, but they have failed for various reasons. One of the reasons why many additives added to SiH-olefin platinum catalyst additive compositions do not work properly is that the additives poison or deactivate the platinum catalyst, so that even after application, the composition does not work properly. is the point where it does not harden. Other conceivable self-bonding additives are simply ineffective in forming a good bond between the cured elastomer and the substrate of interest. For example, silyl triallyl isocyanurate has been attempted as a self-bonding additive in room temperature vulcanizable compositions, but this has not worked as well as desired. This use of silyl triallyl isocyanurate in traditional room temperature vulcanizable compositions has been described, for example, by Hardmun and Bevger.
No. 3,882,083. Another example of such a SiH-olefin platinum catalyzed composition is found in Ballard, US Pat. No. 3,527,655.
The adhesive component of this composition was the reaction product of vinyltrichlorosilane and vinyltrialkoxysilane. Therefore, SiH-olefin platinum catalyzed compositions can be bonded to a variety of substrates such as glass, aluminum, steel, copper, and stainless steel with good bond strength without a primer, and the compositions can be used as encapsulations in electrical circuits. It would be highly desirable to find self-bonding additives that would make the composition desirable for packaging and potting applications.

The self-bonding silicone rubber composition provided by the present invention has the formula (A) (In the formula, R is selected from the group consisting of a monovalent hydrocarbon group and a monovalent halogenated hydrocarbon group, and x is a number such that the viscosity of the basic polymer at 25°C is 100 to 20,000,000 centipoise. (B) 0.5 to 50 parts by weight of a hydride siloxane crosslinking agent, (C) 1 to 500 ppm of a platinum catalyst, and (D)
It consists of 0.1 to 5 parts by weight of a self-binding additive which is a partial hydrolysis product of an aliphatic unsaturated hydrolyzable alkoxysilane. Most preferably, the partial hydrolysis product is a partial hydrolysis product of vinyltriethoxysilane. In addition to or instead of reinforcing fillers
Vinyl-containing silicone reinforcing resin consisting of R ⁶ ₃ SiO _0.5 units and SiO ₂ units and containing silicon-bonded vinyl groups in approximately 2.5 to 10 mol % of the silicon atoms (herein, R ⁶ is a monovalent hydrocarbon group). ) 10 to 100 parts may be introduced.

It should be noted that pure vinyltriethoxysilane does not function as a self-bonding additive in the SiH-olefin platinum catalyst additive composition. On the other hand, fully hydrolyzed vinyltriethoxysilane cannot be used as a self-bonding additive in SiH-olefin platinum catalyzed additive compositions. This is because it is in the form of a resinous gel and is immiscible with the composition and therefore does not perform a self-binding function. Furthermore, the introduction of such gels into SiH-olefin platinum catalyzed compositions is not beneficial as their presence impairs the final cured physical properties of the composition. An advantage of the self-bonding additives of the present invention is that when properly used at appropriate concentrations, they do not appreciably impair the final physical properties of the silicone elastomer formed.

In order to produce a suitable partial hydrolysis product of an aliphatic unsaturated silane, it is desirable to hydrolyze 16 to 49% of the hydrocarbon oxy groups present in the alkoxysilane during the process of producing the partial hydrolyzate. If less than 16% is hydrolyzed, too much vinyltriethoxysilane remains in the hydrolyzate mixture to act as a self-binding additive and dilute the effectiveness of the partial hydrolysis product. If more than 49% of the hydrocarbon oxy groups in this silane are hydrolyzed, the previously mentioned problem of undesirable gel formation in the final product is encountered.

The hydride crosslinker is a hydride-containing linear polysiloxane polymer, a hydride-containing silicone resin consisting of monofunctional and tetrafunctional siloxy units, or a hydride-containing silicone resin consisting of monofunctional, tetrafunctional, and/or difunctional units. Any compound-containing silicone resin may be used.

It should also be noted that the self-bonding additive of the present invention does not cure the composition because it acts as an inhibitor and does not cure the composition at room temperature for an extended period of time, e.g., two weeks after mixing the two components. Hardening of materials must be done at high temperatures. Furthermore, according to the proposal to use the self-bonding additive of the present invention, the self-bonding additive deactivates the platinum catalyst, so that the two-component SiH-olefin platinum catalyst additive composition of the present invention containing the platinum catalyst It is desirable not to include self-bonding additives in the components of. However, if the self-bonding additive of the present invention is incorporated into a component that does not contain a platinum catalyst, the composition can be stored as two separate components for as long as desired without any deleterious effects.

When curing of the composition is desired, the two components are simply mixed together, applied, and heated at elevated temperatures, i.e., in excess of 100° C., within two weeks after mixing to form the desired self-bonding silicone elastomer of the present invention. harden.

Self-bonding additives should not be present in the entire composition for more than two weeks prior to curing of the composition, i.e., the self-bonding additive acts as an inhibitor and inhibits the two components of the composition. After mixing, it should be cured at high temperature within two weeks. If more than two weeks elapse between application of the composition and curing at elevated temperatures, the composition will not cure in a completely satisfactory manner.

It should also be noted that within the scope of this invention is a preferred method for producing aliphatic unsaturated hydrolyzable alkoxysilane hydrolysis products, in which:
Hydrolysis of silane monomer is partial hydrolysis of silane monomer. Partial hydrolysis occurs easily and conveniently in the presence of dipolar neutral solvents, and there is sufficient solvent to provide a homogeneous reaction medium. With such a homogeneous hydrolysis medium, the reaction occurs rapidly and efficiently to produce the desired partial hydrolysis products in the most efficient manner.

Acids, especially strong acids, act as catalysts for such hydrolysis of aliphatic unsaturated hydrolyzable alkoxysilanes and their use is therefore advantageous according to the invention.

The aliphatic unsaturated hydrolyzable silane preferably has the formula R ¹ _a Si(OR ³ ) _4-a (2) where R ¹ is selected from the group consisting of alkenyl and alkynyl having 2 to 8 carbon atoms. is an aliphatic unsaturated group, R ³ is selected from the group consisting of an alkyl group and a cycloalkyl group having 1 to 8 carbon atoms,
a is an integer of 1-2. R ¹ may be an alkynyl group, but is preferably an alkenyl group since acetylenic groups, ie, alkynyl groups, are more efficient inhibitors than alkenyl groups and are therefore less desirable in the compositions of the present invention. Therefore, the R ¹ group is desirably and preferably selected from alkenyl groups having 2 to 8 carbon atoms, such as vinyl, allyl, etc., with vinyl being the most preferred group.

For hydrolyzable groups, the number of carbon atoms is 1 to 8.
an alkyl group or a cycloalkyl group such as methyl,
Preferably, it is selected from ethyl, cyclohexyl, cycloheptyl, etc. It should be noted that many other hydrolyzable groups do not function in the self-bonding additives of the present invention, i.e. additives with groups such as hydroxy, ketoximino, aminoxy, acetoxy, etc. In any case, a compound having such a hydrolyzable group deactivates the platinum catalyst in the SiH-olefin platinum catalyst addition composition, so
It is undesirable for use as a self-binding additive in the compositions of this invention. Most preferably ^R3 is selected from alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl and propyl.

Furthermore, although a may be between 1 and 2, values of a of 1 are preferred because too much unsaturation in the self-bonding additive will unduly inhibit curing of the composition and/or alter the physical properties of the cured elastomer. is more preferable. The most preferred ^R2 groups are ethyl or methyl. Therefore, the most preferred compounds of formula (2) above for use as self-bonding additives in the present invention are compounds of formula (2) in which R ¹ is vinyl, such as vinyltrimethoxysilane or vinyltriethoxysilane. It is a partial hydrolysis product of silane. Vinyltriethoxysilane is more preferred because the alcohol released during hydrolysis is non-toxic and tolerates high concentrations.

The compound of formula (2) above cannot itself be used as a self-binding additive and has little or no ability as a self-binding additive. What needs to be used as self-binding additive in the compositions of the invention is a partial hydrolysis product of a compound of formula (2), which contains between 16 and 49 moles of ^OR3 groups. % is hydrolyzed. Given that in a particular molecule of silane one or more of the ^OR3 groups are hydrolyzed, this number is of course an average value of the hydrolyzed ^OR3 groups in a particular composition. If on average more than 49% of the OR ³ groups are hydrolyzed, the partial hydrolyzate of the compound of formula (2) tends to approach the gel stage, and therefore, in the SiH-olefin platinum catalyzed composition for two reasons. undesirable for Firstly, the composition does not have good self-bonding properties, and secondly,
Gel forms of compounds of formula (2) tend to add significant damage to the physical properties of SiH-olefin platinum catalyzed compositions. If less than 16% of the OR ³ groups are hydrolyzed, the partial hydrolyzate will contain too much monomer of formula (2) and will not impart any self-binding properties to the composition, diluting the effectiveness of the partial hydrolyzate.

The average number of hydrolyzed ^OR3 groups in the monomer of formula (2) is
More preferably 25 to 40 mol%, most preferably 33 mol%. Hydrolysis in the monomeric silane of formula (2)
The reason why the optimal value for the amount of OR ³ groups is 33 mol% is that in the silane of formula (2), on average, only one
This is because the optimum self-binding and curing properties of the SiH-olefin platinum catalyzed composition are obtained when the ^OR3 group is hydrolyzed.

Also, the concentration of the self-binding additive of the present invention used is determined by the formula
The amount is preferably 0.1 to 5 parts by weight, and more preferably 1 to 1.5 parts by weight, based on the base vinyl-containing polymer (1). If the amount of partial hydrolyzate is too small, the desired degree of self-association will not be obtained. If too much self-binding additive is used, ie, more than 5 parts, these high concentrations of self-binding additive will alter the stoichiometric equilibrium of the SiH and olefins and the composition will not cure properly. This balance of the SiH-olefin platinum catalyzed addition reaction is perturbed by the high concentrations of excess vinyl units that may be present as a result of adding self-binding additives above the stated concentrations.

Using an excess amount of partial hydrolyzate greater than the stated amount will result in a shorter than desired pot life. The reaction to produce a partial hydrolyzate is a simple but demanding reaction. Generally, the hydrolysis reaction is preferably carried out in a homogeneous hydrolysis medium, and for this purpose, the hydrolysis medium contains a dipolar neutral solvent capable of dissolving the compound of formula (2) in order to carry out the hydrolysis reaction. as well as the amount of water necessary to partially hydrolyse the compound. Examples of dipolar neutral solvents include, for example, acetone, diethyl ketone,
These include methyl ethyl ketone, dioxane and tetrahydrofuran. The most preferred solvent is acetone, which has desirable solvent properties for the silane of formula (2) as well as the water required to partially hydrolyze it, making it easy to remove from the crude hydrolysis product. It has sufficient volatility.

In a preferred hydrolysis method, water and the compound of formula (2) are mixed simultaneously with a solvent. This gives the best partially hydrolyzed composition.

In another hydrolysis method, water is dissolved in a solvent and silane is added to the solvent, where the hydrolysis reaction takes place. Yet another method involves adding water to the silane and solvent.

Generally, in such hydrolysis reactions, 0.5 to 1.5 moles of water are added per mole of silane of formula (2), depending on the desired amount of partial hydrolyzate. The addition can be carried out under stirring, but stirring is not strictly necessary since the reaction takes place in a homogeneous hydrolysis medium. Sufficient solvent should be used to ensure that there is always a homogeneous hydrolysis medium during partial hydrolysis. The reaction can be carried out in the absence of a solvent or with other types of solvents. but,
If two phases are present in the hydrolysis medium, the hydrolysis reaction will occur, but at a slower rate, which is not the most preferred embodiment as described above.

Furthermore, as already mentioned, partial hydrolysis using 0.5 to 1.5 moles of water per mole of silane of formula (2) and having the above-mentioned average number of hydrolyzed ^OR3 substituents in the compound of formula (2) obtained by hydrolysis. Most preferably, of course, one mole of water per mole of silane of formula (2) is used so that the average number of hydrolysed ^OR3 substituents is
A partial hydrolyzate containing 33 mol% of the compound (2) is obtained. It should further be noted that although temperatures in the range of 10-50°C are acceptable, it is preferred to carry out the reaction near normal ambient temperatures.

The critical point in the above method of producing a partial hydrolyzate is the use of a dipolar neutral solvent in producing a homogeneous hydrolysis medium during the reaction. A second aspect of the method of producing a partial hydrolyzate according to the present invention is the presence of an acid catalyst during the hydrolysis. It has been found that in the absence of an acid catalyst in a homogeneous hydrolysis medium, hydrolysis takes place very slowly or over a long period of time. Therefore, to increase the rate of this reaction, a catalytic amount of acid, i.e., acetic acid, hydrochloric acid, sulfuric acid, i.e., any type of mild or strong acid, i.e., the acidity of the hydrolysis medium is generally increased by 10 ~
It should be present in an amount sufficient to raise it to 500 ppm, preferably 10 to 50 ppm.

Using these acids in the hydrolysis medium and increasing the temperature from 10 to
In the range of 50 DEG C., the reaction proceeds within a time period of 0.5 to 12 hours to yield the desired composition, whereas in the absence of an acid catalyst, the reaction goes to completion only after a much longer period of time. When the acid catalyst is present at the above concentrations, the reaction is nearly complete in about 0.5 hours. Therefore,
When the acid is present in the homogeneous hydrolyzate at the above concentrations, partial hydrolysis is completed within a short time, such as 0.5 hours. Although some well-known acid catalysts have been mentioned above, the catalyst can be any acid catalyst. Furthermore, it is preferred not to add too much acid catalyst so as not to encounter any difficulties in removing excess acid after the hydrolysis reaction is complete. In order to use the partial hydrolyzate of the compound of formula (2) as a self-binding additive, i.e., a self-binding additive in a SiH-olefin platinum catalyst additive composition, its acidity must be below 10 ppm; Otherwise, excessive acidity will affect the curing as well as the final physical properties of the elastomer formed. Therefore, it is desirable to use less acid during the homogeneous hydrolysis reaction to facilitate purification and preparation of the final partial hydrolysis product.

In either case, it is necessary to add a neutralizing agent, such as sodium bicarbonate, to the homogeneous hydrolysis medium after the hydrolysis reaction is complete to substantially neutralize the acid, and then filter the solution to neutralize it. Remove the salts formed by. If the acidity is not too high, for example
10 ppm or less, the mixture may be heated at a temperature in the range of 100 to 125° C. under atmospheric pressure, preferably subatmospheric pressure, to remove any solvent still remaining in the composition, any unreacted water and any formula ( The unreacted silane of 2) can be simply stripped off to obtain the partially hydrolyzed product in its final form. If the acidity of the composition is excessive as described above, sodium bicarbonate may be added to the homogeneous hydrolysis medium after the hydrolysis reaction is completed to neutralize the excess acid, and the solution may then be filtered before finishing. 100-125, preferably at subatmospheric pressure.
The solvent, water and some unreacted silane of formula (2) are stripped off by heating to a temperature in the range of .degree. In any event, this process results in a partially hydrolyzed product which is a self-binding additive of the present invention.

To ensure optimal use in SiH-olefin platinum catalyzed compositions, it is necessary to further dry the partially hydrolyzed product to remove substantially all of the remaining water. Anhydrous sodium or magnesium sulfate, among other drying agents, can be used to sufficiently dry the partially hydrolyzed product for this purpose. Even small amounts of water in the partial hydrolyzate product can inhibit the SiH-olefin platinum catalyzed composition to generate hydrogen, thereby foaming the composition or forming the vinylpolysiloxane of formula (1). There is not enough hydride crosslinking agent for crosslinking with the polymer, and as a result, a soft elastomer is obtained and the physical properties of the elastomer are not good.

After the above process, therefore, a partial hydrolysis product of the compound of formula (2), which is the self-binding additive of the invention, is obtained. These partial hydrolyzate products are generally dimers, trimers,
Siloxanes such as tetramers, i.e., hydrolysates mainly composed of low molecular weight linear or branched siloxanes having olefinic substituents in the heavy chain and containing unhydrolyzed ^OR3 groups, have the formula (2 ) is mixed with some silane. The above partial hydrolysis products are
A self-binding additive of the present invention for SiH-olefin platinum catalyst additive compositions.

The basic components of SiH-olefin platinum catalyst addition compositions are well known in the art. These basic components consist of 100 parts by weight of the vinyl siloxane of formula (1) above.
In the above description, R is selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbons, and is generally an alkyl group having 1 to 8 carbon atoms, such as methyl. , ethyl, cycloalkyl groups having 4 to 8 carbon atoms, such as cyclohexyl, mononuclear aryl groups, such as phenyl, ethyl phenyl, fluoroalkyl groups, such as 3,3,
selected from 3-trifluoropropyl and alkenyl groups such as vinyl, allyl and the like. In the most preferred embodiment of the invention, it is preferred that the compound of formula (1) has no olefinically unsaturated groups other than at the terminal positions of the polymer chain. Therefore, most preferably R
Alkyl group having 1 to 8 carbon atoms, 6 carbon atoms
~8 mononuclear aryl groups such as phenyl and C3 to C8 fluoroalkyl groups such as 3,
Selected from 3,3-trifluoropropyl. Generally, x in a polymer is the viscosity of the polymer at 25℃.
In a more preferred embodiment, the viscosity of the vinyl-terminated polymer, i.e., the base polymer, at 25°C ranges from 300 to 200000000 centipoise.
500000 centipoise, more preferably 300~
It is 200000 centipoise. Although the self-bonding additives of the present invention can be used in high viscosity compositions, it is still preferable to use them in low viscosity compositions. The self-binding additive of the present invention can be used in any two-component high viscosity SiH-olefin platinum catalyst additive composition, but is more effective as a self-binding additive in low viscosity SiH-olefin platinum catalyst additive compositions. It is true.
It is particularly effective for transparent, low-viscosity compositions that use vinyl-containing silicone resins instead of reinforcing fillers. Therefore, the self-bonding additive of the present invention has a low viscosity.
It has wide application as a self-bonding additive to SiH-olefin platinum catalyst additive compositions. Therefore, Eq.
The vinyl polysiloxane polymer (1) is generally heated at 25℃.
It is desirable to have a viscosity of 100 to 200,000 centipoise.

Methods for producing such vinyl-containing polymers are well known in the art and generally consist of equilibration of a suitably substituted cyclotetrasiloxane in the presence of a basic catalyst, most preferably potassium hydroxide. Appropriate amounts of various chain terminators are used in the equilibrium reaction medium to obtain vinyl end groups on the polymer chain and to obtain a suitable viscosity in the final polymer. Thus, a vinyl terminated polymer of formula (1) of the desired viscosity is produced using divinyltetramethyldisiloxane as a chain terminator. The chain terminator, i.e., cyclotetrapolysiloxane, and the required amount of catalyst, present in a concentration of 10 to 100 ppm, are heated at a temperature above 150° C. for an average time of 1 to 8 hours to form a linear chain of formula (1). Produces polysiloxane polymers. At the equilibrium point, approximately 80-85% of the cyclotetrasiloxane is converted to polymer, and at the equilibrium point, the polymer that is being prepared from the cyclotetrasiloxane and the polymer that is decomposing to form the cyclotetrasiloxane. and become equal amounts.

At that point, the catalyst is simply neutralized and the cyclics stripped off to provide the desired linear polysiloxane polymer of formula (1). Basic polymer 100 of the above formula (1)
1 to 50 parts by weight of the hydride siloxane crosslinking agent are used. Such hydride siloxane crosslinkers have the formula , where R ⁷ is selected from the group consisting of hydrogen, a monovalent hydrocarbon group, and a monovalent halogenated hydrocarbon group, and R ⁴ is a monovalent hydrocarbon group, more preferably a carbon atom. It is selected from the group consisting of alkyl groups having numbers 1 to 8, cycloalkyl groups having up to 8 carbon atoms, mononuclear aryl groups such as phenyl and 3,3,3-trifluoropropyl groups. Therefore, R ⁴ is hydrogen, and any saturated monovalent hydrocarbon group and halogenation can be carried out using a solvent such as a water-immiscible organic solvent selected from benzene, toluene, xylene, etc. during hydrolysis. good. In any event, such hydrolysis reactions for producing such hydride silicone resins are well known, as are methods for producing hydrogen-containing polysiloxane polymers of formula (3) above. Polysiloxane polymers of formula (3) can also be obtained by equilibrating cyclotetrasiloxane at elevated temperatures in the presence of an acid catalyst such as toluenesulfonic acid using a suitable hydride chain terminator. In such an equilibration process, the same heating step is used during equilibration to produce the desired hydrogen polysiloxane polymer of formula (3) above, followed by neutralization and exhaust of volatiles. These steps are well known in the art and therefore will not be described in detail.

In addition to hydride silicone resins consisting of monofunctional and tetrafunctional units, HR ⁵ ₂ SiO _0.5 units,
Consisting of SiO ₂ units and R ⁵ ₂ SiO units (however, H+
Hydride silicone resins can be used as crosslinkers (R ⁵ to Si ratio is from 1.1 to 1 to 2.7 to 1 and R ⁶ is as defined above). More preferably, silicone resins comprising hydrogen-containing siloxy monofunctional units and tetrafunctional siloxy units are preferred as the crosslinking agent in the hydrogen siloxane of formula (3) above, ie, the composition of the present invention. Additionally, silicone resins containing difunctional siloxy units are difficult and expensive to manufacture. However, such bifunctional unit-containing resins can be treated with SiH according to the present invention.
- Can be used as a crosslinking agent in olefin platinum catalyst additive compositions.

As a catalyst, 1 to 500 ppm, preferably 1 to 500 ppm
A 200 ppm platinum catalyst is used.

Many different platinum compounds are known for this SiH-olefin addition reaction, and such platinum catalysts can also be used in the reaction of the present invention. Preferred platinum catalysts are platinum compound catalysts that are soluble in the reaction mixtures of the invention, especially when optical clarity is required. The platinum catalyst is covered by Ashby's U.S. Patent No.
It is selected from those having the formula (PtCl ₂ olefin) ₂ and H (PiCl ₃ olefin) as described in No. 3159601. The olefin shown in the above two formulas may be almost any type of olefin, but is preferably alkenylene having 2 to 8 carbon atoms, cycloalkenylene having 5 to 7 carbon atoms, or styrene. Specific olefins used in the above formula are ethylene, propylene, various isomers of butylene, octylene, cyclopentene, cyclohexane, cycloheptene, and the like.

Additionally, platinum-containing materials that can be used in the compositions of the present invention include the platinum chloride cyclopropane complex (PtCl ₂ .C ₃ H ₆ ) ₂ described in U.S. Pat. No. 3,159,662 to Ashby.
It is.

Furthermore, chloroplatinic acid and up to 2 moles per gram of platinum of alcohols, ethers,
The platinum-containing material may be a complex formed with an aldehyde or a mixture thereof.

A preferred platinum compound that can be used not only as a platinum catalyst but also as a flame retardant additive is disclosed in Karstedt, US Pat. No. 3,775,452. Generally speaking, platinum complexes of this type are formed by reacting chloroplatinic acid containing 4 moles of water of hydration with tetravinyltetramethylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanolic solution. .

When the filler is selected from reinforcing fillers and bulking fillers, 10 to 200 parts by weight of the filler per 100 parts of the basic vinyl-containing polymer of formula (1) may be added to the base vinyl to enhance the physical properties of the composition. It can be incorporated into containing polymers. Generally, the reinforcing filler is a filler such as fumed silica or precipitated silica, and the bulking filler is, for example, fused silica. Although reinforcing fillers are preferred for strength properties, bulking fillers also tend to be cheaper and do not appreciably increase the viscosity of the uncured composition.

In order to obtain the desired high tensile strength in the compositions of the present invention, and especially when forming such compositions into thin coatings or films, it is desirable to incorporate fillers into the compositions. Examples of the many fillers that can be used are titanium oxide, lithopone, zinc oxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate, fumed silica, silazane-treated silica, precipitated silica, glass fiber, magnesium oxide, oxidized Chromium, zirconium oxide, aluminum oxide, alpha quartz, kamiyaki clay, asbestos, carbon, graphite, cork,
Cotton, synthetic fibers, etc.

Preferred fillers for use in the compositions of this invention, particularly component (A) of this invention, are either treated fumed silicas or precipitated silicas. Thus, silica fillers may be treated with cyclic polysiloxanes as disclosed, for example, in Lucas, US Pat. No. 2,938,009.

Another method of treating fillers or treated fillers that can be used in the present invention is disclosed in Brown, US Pat. No. 3,024,126.

In particular, Smith U.S. Pat. No. 3,635,743 and Beers
Silazane-treated fillers according to the disclosure of U.S. Patent Application No. 311,486, filed December 4, 1972, are preferred as treated fillers for use in the compositions of the present invention.

Further information on basic vinyl-containing polymers and hydride polysiloxanes and such
For general details regarding SiH-olefin platinum catalyzed compositions, see Jeram et al.
Please refer to No. 3957713. As described in this patent, other components well known in SiH-olefin platinum catalyzed compositions can be incorporated into the base composition to obtain certain properties in the cured elastomer resulting from the composition. .

In this way, the basic vinyl-containing polymer of formula (1)
Based on 100 copies, formula vinyl-containing polymer or formula of vinyl-containing silicone resin (where m, p, q
takes a value such that the resin contains 2.5 to 10 mol% of vinyl groups, R ⁶ is an alkyl group having 1 to 8 carbon atoms,
selected from the group consisting of cycloalkyl groups, aryl groups and fluoroalkyl groups, and z is preferably such that the viscosity of the polymer is from 100 to 5000 centipoise at 25°C.
(The value is 100 to 1000 centipoise)
1 to 30 parts by weight may be added to the composition.

Preferably R ⁶ is methyl, phenyl and 3,
It is selected from groups such as 3,3-trifluoropropyl, most preferably methyl or phenyl. When the vinyl-containing polymer of formula (4) above is added to the base vinyl-containing polymer, the SiH-olefin platinum catalyzed composition produces a cured elastomer with higher strength properties, such as higher tear properties, than when it does not contain such components. is obtained.

Reference may be made to Jeram, US Pat. No. 4,041,010 for the preparation of fluorosilicon substituted SiH-olefin platinum catalyzed compositions. This patent describes suitable basic vinyl-containing polymers, types of platinum catalysts that can be used, and information on the formation of cured elastomers.
The types of hydride siloxane crosslinkers and fillers and other components conventionally added to SiH-olefin platinum catalyzed compositions are disclosed.

It should be understood that the self-bonding additive of the present invention can be used not only in the compositions of these patents, but also in most SiH-olefin platinum catalyst additive compositions; -Olefin platinum catalyzed compositions and fluorosilicone SiH-olefin platinum catalyzed compositions. As is well known, in addition to the basic components described above for SiH-olefin platinum catalyst additive compositions, the self-bonding additives of the present invention may be added, as long as they do not interfere with the self-bonding properties of the components of the present invention. Other ingredients may be added, such as pigments conventionally added to SiH-olefin platinum catalyzed compositions as well as fluorosilicone SiH-olefin platinum catalyzed compositions. However, for clear potting compounds, pigments are not desirable additives for SiH-olefin platinum catalyzed potting compounds. However, SiH−
Various vinyl-containing fluids and/or resins known to be added to the olefin platinum catalyzed compositions may be added to the basic components disclosed in the above disclosure and the Jeram patent, in addition to some of the cured elastomers formed from the compositions. Characteristics can be improved.

As mentioned above, the self-bonding additive of the present invention is applied to a two-component SiH-olefin platinum catalyst additive composition, and is applied to a component of the two-component SiH-olefin platinum catalyst additive composition that does not contain a platinum catalyst. It will be applied.

Preferably, therefore, the filler or vinyl-containing silicone reinforcing resin is incorporated into the basic vinyl-containing polymer of formula (1), the platinum catalyst is added thereto, and the composition is stored separately from the other ingredients. . To form the second component of the second package, the hydrogen siloxane crosslinker alone or with some filler may be included, and if the platinum catalyst is combined with the hydrogen polysiloxane, it may contain any vinyl-containing polymer. does not enter. However, if the platinum catalyst is incorporated with the basic vinyl-containing polymer of formula (1) and filler, then the vinyl-containing fluid may also be introduced with the hydrogen siloxane crosslinker component. Unless the platinum catalyst is present with the hydrogen siloxane and the low viscosity vinyl-containing polymer, there will be no crosslinking or curing of the components. However, if the platinum catalyst is introduced along with the hydrogen siloxane crosslinker, the vinyl-containing fluid needs to be incorporated into the other components combined with the base vinyl-containing polymer.

Self-binding additives must be incorporated into components that do not contain platinum catalysts, otherwise they tend to deactivate and eventually poison the platinum catalysts during storage. Therefore, if the two ingredients are packaged as is,
During transportation and storage, and when curing of the composition is desired,
These ingredients are simply mixed together in specified amounts and then formed into the desired area. The composition must then be heated to a temperature above 100 DEG C. for a few minutes to 1 to 2 hours, depending on the degree of heating, to cure the composition into a self-bonding silicone elastomer. It should be noted here that once the two components are mixed, the composition must be cured within two weeks, because if the mixed composition is not cured within this period, the platinum catalyst will be deactivated. Therefore, even if there is a small amount, it becomes very difficult to cure the composition. Therefore,
Once the two components are mixed, it is desirable for the composition to cure within two weeks. As will be appreciated with respect to the compositions of the present invention, after mixing the two components, the mixed composition will have a pot life of two weeks, during which time the composition will not cure at room temperature, but only at elevated temperatures, i.e., above 100°C. Cures into silicone elastomer at temperature.

EXAMPLES Hereinafter, embodiments of the present invention will be illustrated with reference to Examples. However, the examples are not presented to set limits on the scope of the invention. All parts in the examples are by weight.

Example 1 An adhesion promoting additive composition was prepared as follows. A 1 quart bottle was charged with 250 parts acetone, 191 parts vinyltriethoxysilane, and 18 parts water. The bottle was capped and shaken gently.
A mild fever occurred. The bottle was evacuated several times during the exotherm. After the exotherm subsided, the mixture was allowed to stand overnight. Upon titration, the product mixture contained 10 ppm of acid, no doubt due to traces of silyl chloride remaining in the vinyltriethoxysilane. The mixture was subjected to stripping at 100° C. in a rotary evaporator at maximum vacuum (25 inches). The weight of the final product was 103 parts. This was a clear, water-white liquid. It was dried using anhydrous sodium sulfate prior to its analysis and use. Gas chromatographic analysis of the stripped product showed that some (up to 5%) reactant silane remained, but vinyl silicone was present in more substantial amounts, dimer (approximately 40%) and higher. It existed as a multimer (approximately 40%). Ethyl alcohol was also present in trace amounts in the stripped product.

Example 2 An adhesion promoting additive composition was prepared as follows.

135 parts acetone, 255 parts vinyltriethoxysilane in an all-glass reactor equipped for reagent addition.
and several drops of 12 molar hydrochloric acid. With gentle stirring, 24 parts of water was added at a rate sufficient to generate a mild exotherm, and the reaction temperature was maintained below 50°C. The reaction mixture was gently stirred for 2 hours after this water addition and then cooled to room temperature. Approximately 5 parts of sodium bicarbonate was added to neutralize the acid. The mixture was stirred for an additional hour and then pumped through Celite. Heat the liquid at 100℃ and vacuum (28
After stripping with an inch-inch), it was dried over anhydrous magnesium sulfate. Approximately 100 parts of product were obtained.

The product was a clear water-white liquid. The acid content was less than 10 ppm and the water content was less than 0.05% by weight. The infrared spectrum matched the expected composition, showing a vinyl absorption band at 6.25 microns and a siloxy absorption band at 9-10 microns. Gas chromatographic analysis showed that about 5-10% by weight of the mixture was unconverted vinyltriethoxysilane, with the remainder being dimers and higher multimers. A small amount (less than 1%) of ethyl alcohol was also detected.

Example 3 Following the teachings of Modic U.S. Pat. No. 3,425,967,
A transparent resin reinforced potting/encapsulation composition was prepared. This composition consisted of two packages A and B. Package A is average type (x is the value such that the viscosity of the polymer is 4000 cps at 25°C) 75 parts of the base polymer, average formula 25 parts of resin and Lamoreaux U.S. Patent No. 3,220,972
It consisted of 10ppm of Pt in the form described in No. On the other hand, package B contains 50 parts of the basic polymer present in package A and the average formula It consisted of 50 parts of a crosslinking resin represented by: To 100 parts of Package A was added 1 part by weight of the adhesion promoting additive composition of Example 1. This mixture was immediately combined with 10 parts of Package B and mixed thoroughly. This mixture did not cure at ambient laboratory temperatures, but did cure at elevated temperatures. For example, after 1 hour at 100°C, the mixture cured to form a clear silicone elastomer. Up to 14 days after preparation, the mixture cured satisfactorily when exposed to 100° C. for 1 hour. After 14 days, the cure was unsatisfactory at this high temperature (100°C) and the final elastomer was too soft.

The physical properties of the compositions with and without self-bonding additives were as follows. Physical properties Without additives With additives Tensile psi 920 820 Elongation % 150 160 Durometer shore 35 28 A hardness tear 1bs/in 40 20 Therefore, even if additives are present at the concentrations of the examples,
No noticeable deterioration of the physical properties of the cured elastomer occurred.

Example 4 To the SiH-olefin platinum catalyst addition composition of Example 3 above, 1 part by weight of the partially hydrolyzed vinylsiloxysilane of Example 1 was added. During the 14-day period of satisfactory high temperature cure detailed in Example 3, the RTV (room temperature vulcanizable) composition of Example 3 was applied to each test substrate at a thickness of 60 mils and cured at 300 mm. It was cured in place by baking for an hour. Again, no substantial deterioration in the physical properties of the cured rubber was observed.

Each test substrate of 60 mil thick RTV was coated and cured in situ as described. From a normal perspective, the entire surface was transparent. The cured silicone elastomer, which is a clear SiH-olefin platinum catalyzed composition, had good clarity at this thickness.
The bonding conditions were as follows.

In order to compare the self-bonding additive according to the present invention with that according to Ballard (see Japanese Patent Publication No. 47-36255), the following experiment was carried out.

Comparative Example 1 A self-bonding additive according to Ballard was prepared as follows.

In the reaction glassware, add 200 g (1.05 mol) of vinyltriethoxysilane and 40 g of vinyltrichlorosilane.
(0.25 mol) and 175 g of toluene solvent. The mixture was stirred vigorously and 50 g (3.2 moles) of water was carefully added to keep the rate of hydrolysis moderate. The mixture was continued to stir for approximately 15 minutes after the addition was complete and then allowed to stand to separate the layers. isolating the layer containing the vinyl siloxane hydrolyzate;
After a while, it was transferred to a stripping device. The solution obtained by adding 4 g (0.2 mol) of water to this hydrolyzate was heated to 115° C., and the solvent and water were removed under atmospheric pressure. Then, remove the remaining solvent at 87℃ and 21mm
It was removed under vacuum using Hg. The weight of the hydrolyzed product after stripping was 73 g. The final product was a hydrolysis product according to Ballard's invention, which was cloudy in character and extremely viscous in nature. This is in contrast to the fact that the self-binding additive according to the invention was a clear, free-flowing liquid and therefore had little difficulty in incorporating into the Package A composition described in Example 3. .

According to Example 3, the physical properties of an ASTM sheet obtained by curing a silicone rubber composition containing Ballard's self-bonding additive at 100° C. for 1 hour were measured, and the following values were obtained.

Physical properties Tensile psi 480 Elongation % 200 Durometer shore A hardness 29 Tear Lbs/in. 11 Package A (containing 1 part by weight of Ballard's self-bonding additive) and package B were prepared in the same manner as in Example 4. was applied to each test substrate and cured in situ. When the bonding state of the cured product to each test substrate was investigated, the following results were obtained. Substrate bonding state Glass Defective Aluminum (bare) Defective Steel (carbon steel) Defective Copper Barely bonded Stainless steel (Steel) Defective From the above results, the cured product of the self-bonding silicone rubber composition containing Ballard's self-bonding additive is , the physical properties are considerably lower than in the case without additives,
It can be seen that Ballard's self-bonding additive does not function satisfactorily due to its lack of transparency and poor bonding with various substrates.

Claims (1)

[Claims] 1 (1) (A) formula (In the formula, Vi is a vinyl group, R is selected from the group consisting of a monovalent hydrocarbon group and a monovalent halogenated hydrocarbon group, and x is a viscosity of the base polymer at 25°C of 100 to 200000000 (B) 0.5 to 50 parts by weight of a hydride siloxane crosslinking agent, (C) 1 to 500 ppm of a platinum catalyst, and (D) an aliphatic unsaturated 0.1 to 5 parts by weight of a self-binding additive, which is a partial hydrolysis product of a hydrolyzable alkoxysilane, is mixed, (2) this mixture is applied to a substrate, and then (3) the substrate and mixture are heated to a high temperature. A method of adhering a self-bonding silicone rubber composition to a substrate, comprising: 2 The self-bonding additive has the formula R ¹ _a Si(OR ³ ) _4-a (where R ¹ is an aliphatic unsaturated group selected from the group consisting of alkenyl groups and alkynyl groups having 2 to 8 carbon atoms; , R ³ is selected from the group consisting of an alkyl group having 1 to 8 carbon atoms and a cycloalkyl group, and a is 1 to 2). Method described. 3. The method of claim 2, wherein the partial hydrolysis product is such that an average of 16 to 49% of the hydrocarbon oxy groups of the silane having the above formula are hydrolyzed. 4. The method of claim 1, wherein 1 to 1.5 parts by weight of the self-binding additive are used. 5. The method according to claim 1, wherein 5R is selected from the group consisting of an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, an aryl group, and a fluoroalkyl group. 6 The hydride siloxane crosslinking agent has the formula (However, R ⁷ is hydrogen, a monovalent hydrocarbon group, and a monovalent hydrocarbon group.
selected from the group consisting of valent halogenated hydrocarbon groups, R ⁴ is a monovalent hydrocarbon group, and y is
2. The method of claim 1, wherein the viscosity of the polymer at 25 DEG C. is in the range 10 to 500 centipoise. 7 The hydride siloxane crosslinking agent is a resin consisting of HR ⁵ ₂ SiO _0.5 units and SiO ₂ units, and H+R ⁵
The ratio of base to Si is 1.1 to 1.0 to 2.7 to 1.0, and R ⁵ is 1.
2. The method according to claim 1, wherein the monovalent hydrocarbon group is selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups. 8. The method of claim 1, further comprising 10 to 200 parts by weight of a filler selected from reinforcing fillers and bulking fillers. 9. The method of claim 1, wherein the reinforcing filler is selected from the group consisting of fumed silica and precipitated silica. 10. The method of claim 9, wherein the filler is treated with a treatment agent selected from the group consisting of cyclosiloxanes, silazane and mixtures thereof. 11 formula (In the formula, Vi is a vinyl group, R ⁶ is a carbon atom number of 1 to
selected from the group consisting of 8 alkyl groups, cycloalkyl groups, aryl groups and fluoroalkyl groups,
2. A method according to claim 1, wherein from 1 to 30 parts by weight of a vinyl-containing polymer is present, where z is such that the viscosity of the polymer at 25 DEG C. is from 100 to 5000 centipoise.