JPH03287664A - Room temperature curable organopolysiloxane composition and curing product prepared therefrom - Google Patents

Abstract

PURPOSE:To prepare the title compsn. which hardly causes contact trouble and gives a curing product showing no change in rubber properties with time by compounding a specific diorganopolysiloxane, a specific organosilicon compd. or a partially hydrolyzed condensate thereof, and a curing catalyst. CONSTITUTION:100 pts.wt. diorganopolysiloxane having silanol or alkoxy groups at both molecular ends, 1-20 pts.wt. organosilicon compd. of the formula [wherein R<1> is a 1-6C (substd.) monovalent hydrocarbon group; and R<2> is a 1-4C (substd.) monovalent hydrocarbon group] and/or a partially hydrolyzed condensate thereof, and an effective amt., usually 0.01-10 pts.wt., of a curing catalyst are compounded as the essential components to give the title compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel dealcoholization type room temperature curable organopolysiloxane composition and its cured product, and is particularly useful for adhesive fixing and coating of electrical parts and electronic parts, etc. This invention relates to a novel dealcoholization type room temperature curable organopolysiloxane composition that does not cause contact failure when used in applications such as botting, and a cured product thereof.

(Prior Art) Dealcoholization-type, room-temperature-curing organopolysiloxane compositions are generally one-component, and when extruded from a tube or cartridge, cure with moisture in the air, making them versatile and useful in electrical and electronic applications. It is widely used in the electrical and electronic industries because it has the advantage of not corroding parts, etc.

Incidentally, in recent years, there has been a remarkable trend toward miniaturization of electronic components due to the trend toward miniaturization of electrical products, and the chances of trouble occurring in micromotors and relay circuits are increasing with the miniaturization of such electronic components. It is believed that volatile silicone is one of the causes of these troubles.

In order to prevent such contact failure caused by volatile silicone, it is important to take measures to remove volatile low-molecular-weight siloxane (up to 20-mer cyclic dimethylsiloxane) present in silicone polymers in advance. It can be done relatively cheaply, except for the fact that it increases the cost a little.

However, conventional dealcoholization-type room-temperature-curable organopolysiloxane compositions contain low-molecular organosilicon compounds such as methyltrimethoxysilane as crosslinking agents; No matter how completely siloxane is removed, the low-molecular crosslinking agent evaporates into the air during the process of being extruded into the air and hardening due to moisture, and this adheres to electronic components such as micro motors and relay circuits, causing contact failure. It had the disadvantage of causing

Therefore, the above-mentioned measure of previously removing volatile low-molecular-weight siloxane present in the silicone polymer could not be a drastic measure.

(Problem to be solved by the invention) Therefore, it is possible to consider a method of preventing contact failure by using, for example, a crosslinking agent such as phenyltrimethoxysilane, which is relatively difficult to evaporate, but if phenyltrimethoxysilane is used as a crosslinking agent, it will harden at room temperature. Problems arise such as slow cure, impractical, and inability to obtain a transparent cured product. Also, if a larger amount of curing catalyst is used than normally used to accelerate curing,
This has the disadvantage that not only the storage stability becomes poor, but also the heat resistance, weather resistance, water resistance, etc. of the cured rubber deteriorate.

As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors selected a diorganopolysiloxane having silanol groups or alkoxy groups at both ends of the molecular chain as the base polymer. As a crosslinking agent that can quickly react with the polymer, R'3S iO
The present invention was completed by discovering that the above-mentioned problems can be solved by combining the organosilicon compounds represented by 31(OR'')3.

Therefore, the first object of the present invention is to provide a room-temperature-curable organopolysiloxane composition that does not cause contact failure even when used for adhesive fixing, coating, and botting of electrical and electronic components, and its curing. It's about providing things.

A second object of the present invention is to provide a room-temperature-curable organopolysiloxane composition in which the curing reaction proceeds rapidly and the physical properties of the rubber do not change over time after curing, and which is suitable for use in electrical and electronic components. and to provide a cured product thereof.

(Means for Solving the Problems) The above aspects of the present invention are as follows: (100 parts by weight of diorganopolysiloxane having a silanol group or alkoxy group at both ends of the molecular chain; (2) general formula R'sS i O3i (OR) ) Achieved by a room-temperature-curable organopolysiloxane composition containing 1 to 20 parts by weight of an organosilicon compound represented by () and/or its partially hydrolyzed %f condensate, and (1) an effective amount of a curing catalyst, and a cured product thereof. It was done.

The organopolysiloxane in which both ends of the molecular chain are blocked with silanol groups that can be used in the component (1) above is represented by the general formula HO (R'R' S io), H in which R3 and R4 are: Alkyl groups such as methyl, ethyl, propyl and butyl groups, alkenyl groups such as vinyl and allyl groups, aryl groups such as phenyl and tolyl groups, cyclohexyl groups, or hydrogen bonded to carbon atoms of these groups. Chloromethyl group, cyanoethyl group, with some or all atoms substituted with halogen atoms, cyano groups, etc., 3.3゜3-
Represents the same or different unsubstituted or substituted monovalent hydrocarbon groups selected from substituted alkyl groups such as trifluoropropyl groups, and those having 1 to 8 carbon atoms are particularly preferred.
m is an integer of 5 or more.

The organopolysiloxane has a viscosity at 25°C ranging from 25 to 500,000 cst, preferably 1.
000 to 100,0OOcst.

Further, examples of organopolysiloxanes whose molecular chain terminals are capped with alkoxy groups include those represented by -a formula % formula %. Here, R1 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms similar to the above-mentioned R3 and R4, and R3 and R4 are the above-mentioned organopolymer in which both ends of the molecular chain are blocked with silanol groups. Same as siloxane. X represents an unsubstituted or substituted lower alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a methoxyethoxy group, an ethoxyethoxy group, and a represents 0 or 1; The viscosity of the polysiloxane is 25% as in the case of the silanol-terminated organopolysiloxane.
The range is 25 to 500,000 cst, preferably 1,000 to 100,000 cst at °C.

The organosilicon compound represented by the general formula R', S i O3i (OR'')', which is the component (1) of the present invention (where R1 is the same as in the case of the component (1) above, and is a substituted compound having 1 to 6 carbon atoms). or represents an unsubstituted monovalent hydrocarbon group.R2 represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 4 carbon atoms such as a methyl group, ethyl group, propyl group, isopropyl group, butyl group, methoxyethyl group, or ethoxyethyl group. ) representing a monovalent hydrocarbon group such as an alkyl group is a feature of the present invention, and specifically, (CHs)s S i O3i (OCHs:h, (
CH2)! (CHt=CH)S i O3i
(OCHs)s, (CHa)z Chis S i O
3i (OCH3)+, CHs (CaHs)g
S i O3i (OCHs)s, (CHs)z(C
Fs Cz Ha ) S i O3i (QC) (
Examples include s) s and those obtained by changing the methoxy group of these compounds to other alkoxy groups such as ethoxy group, propoxy group, isopropoxy group, butoxy group, methoxyethoxy group, and ethoxyethoxy group.

The catalysts that are component (1) of the present invention include tin carboxylates such as silver naphthenate, silver caprylate, and silver oleate; Acetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis(triethoxysiloxy)
8. Tin compounds such as diptyltin benzyl maleate, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetrakis(2-ethylhexoxy)titanium, dipropoxybis(acetylacetonato)titanium, titanium isoproboxyoctylene glycol titanate esters or titanium chelate compounds, etc., guanidyl group-containing silanes such as tetramethylguanidylpropyltrimethoxysilane, tetramethylguanidylpropyldimethoxysilane, tetramethylguanidylpropyltris(trimethylsiloxy)silane, etc. Partial hydrolysates thereof and guanidyl group-containing siloxanes are used.

This catalyst is for accelerating the curing of the room temperature curable silicone composition of the present invention, and by using an effective amount to exhibit catalytic action, the composition of the present invention can be cured into a rubber. However, in order to accelerate curing, it is usually used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 2 parts by weight, per 100 parts by weight of component (1).

Further, fillers may be added to the composition of the present invention for the purpose of reinforcing or increasing the amount, if necessary.

Fillers include, for example, finely powdered silica, fumed silica,
Precipitated silica, diatomaceous earth; Metal oxides such as iron oxide, zinc oxide, titanium oxide, etc., or those whose surfaces have been hydrophobized with silane, etc.; Metal carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, etc. ; It can be appropriately selected from known materials such as asbestos, glass fiber, carbon blank, finely divided mica, and fused silica powder.

Furthermore, if necessary, thixotropic property imparting agents such as polyethylene glycol and its derivatives, pigments, dyes, anti-aging agents, antioxidants, antistatic agents, flame retardants such as antimony oxide and chlorinated paraffin, boron nitride and aluminum oxide, etc. It is also optional to add a thermal conductivity improver, etc.
Furthermore, organic silicon compounds having reactive Il groups such as amino groups, epoxy groups, and mercapto groups (
Various conventionally known additives such as a so-called silane coupling agent may be mixed.

When applying the silicone composition of the present invention to a substrate, it may be diluted with a hydrocarbon solvent such as toluene, xylene, or petroleum ether, or a solvent such as ketones or esters from the viewpoint of insulating properties. Furthermore, there is no problem in adding plasticizers, anti-sagging agents, known antifouling agents, preservatives, bactericidal agents, antifungal agents, and the like.

(Effect of the invention) The room temperature curable organopolysiloxane composition of the present invention has the following properties:
As the crosslinking agent, we use an organosilicon compound that is relatively difficult to volatilize, has good compatibility with the base diorganopolysiloxane, and has a rapid curing reaction, so it is unlikely to cause contact failure, which has been a problem in the past. Moreover, the storage stability and the heat resistance, weather resistance, and water resistance of the rubber after curing are also sufficient.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Synthesis Example 1 214 parts of methyldiphenylsilanol and 152.1 parts of tetramethoxysilane (1:1 molar ratio) were charged into a reaction vessel equipped with a thermometer, a condenser, and a stirring device, and 0.5 part of calcium hydroxide was added. In addition, the mixture was reacted at reflux temperature for 8 hours.

By distilling after the reaction, the boiling point is 161-164°C/
1-methyl-1,1-diphenyl- with 3 mmHg
3,3°3-trimethoxydisiloxane (hereinafter abbreviated as ΦTM) was obtained in an isolated yield of 92%.

Synthesis Example 2゜720 parts of trimethylsilanol and 121 parts of tetramethoxysilane were placed in a reactor similar to that used in Synthesis Example 1.
6.8 parts (molar ratio: 1:1) were charged, 5 parts of calcium chloride was added, and the mixture was reacted under reflux for 8 hours. By distilling the obtained reaction product, 1°1.1-trimethyl-3,3,3-) having a boiling point of 150-152°C (normal pressure)
Rimethoxydisiloxane (hereinafter abbreviated as MTM) was obtained with an isolated yield of 94%.

Synthesis Example 3 306 parts of vinyldimethylsilanol and 4 parts of tetramethoxysilane were placed in a reaction apparatus similar to that used in Synthesis Example 1.
56.6 (molar ratio: 1:1), 5 parts of calcium chloride was added, and the mixture was reacted under reflux for 8 hours. By distilling the obtained reaction product, the boiling point was 80.5°C/38mmH.
1-vinyl-1,1-dimethyl-3,3,3 with g
-) Rimethoxydisiloxane (hereinafter abbreviated as VTM) was obtained with an isolated yield of 87%.

Example 1 The molecular terminals are blocked with silanol groups, the content of low molecular weight siloxane (cyclic dimethylpolysiloxane with less than 20 polymers) is 0.2%, and the viscosity at 25°C is 5.0.
A base was prepared by adding and mixing 10 parts of silica filler to 100 parts of 00cst polydimethylsiloxane polymer. For 100 parts of this base, 1-methyl-1,1-
Diphenyl-3,3,3-trimethoxydisiloxane (
0.07M) and 3 parts of dimethyldimethoxytin. 1 part was added and stirred and mixed uniformly.

The thus obtained room temperature curable organopolysiloxane composition (RTV) was molded into a sheet with a thickness of 2 mm.
After curing for 7 days at 0''C and 55% RH, the physical properties of the cured product were measured.

The results are shown in Table 1.

Table 1 Also, put 100 parts of this RTV into a container with a volume of 51 and
A mounting test was conducted on the micromotor (M) using the variable constant voltage power supply (2.0V-150mA) shown in the figure, and the occurrence of contact failure was evaluated. The evaluation was performed by observing the motor waveform using a synchroscope, and assuming that a contact failure occurred when the motor waveform became abnormal. The results are shown in Table 2.

Example 2 Using the same base as in Example 1, 3 parts of 1.1.1-)dimethyl-3,3,3-trimethoxydisiloxane (MTM) and 0 of dimethyldimethoxytin per 100 parts of base.
．． The physical properties and the occurrence of contact failure were evaluated in the same manner as in Example 1 for the RTV obtained by adding 1 part and stirring and mixing uniformly. The results are shown in Tables 1 and 2.

Example 3 Using the same base as in Example 1, 3 parts of 1-vinyl-1,1-dimethyl-33,3-trimethoxydisiloxane (VTM) and 0.1 tin of dimethyldimethoxy were added to 100 parts of the base. The physical properties and the occurrence of contact failure were evaluated in the same manner as in Example 1 for the RTV obtained by adding 50% of the total amount and stirring and mixing uniformly. The results are shown in Tables 1 and 2.

Comparative Example 1゜About RTV obtained by using the same base as in Example 1, adding 3 parts of vinyltrimethoxysilane (VMS) and 0.1 part of dimethyldimethoxytin to 100 parts of the base and stirring and mixing them uniformly. The physical properties and occurrence of contact failure were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

The results in Tables 1 and 2 demonstrate the effectiveness of the room temperature curable compositions of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the implementation of a micromotor using a variable constant voltage power supply. The symbol M in the figure represents a micromotor. Patent applicant Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1) [1] 100 parts by weight of diorganopolysiloxane having silanol groups or alkoxy groups at both ends of the molecular chain, [2] Organosilicon represented by the general formula R^1_3SiOSi(OR^2)_3 1 to 20 parts by weight of the compound and/or its partially hydrolyzed condensate (here, R^1 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and R^2 represents a carbon number 1 to 4 unsubstituted or substituted monovalent hydrocarbon groups) and [3] A room-temperature-curable organopolysiloxane composition characterized by containing as a main component an effective amount of a curing catalyst. 2) A cured product obtained by curing the composition according to claim 1.