JP2023058202A - Heat-curable organopolysiloxane composition and cured product, and article - Google Patents

Abstract

To provide a heat-curable organopolysiloxane composition excellent in storage stability and deep part curability, without receiving cure inhibition by oxygen, nitrogen, sulfur, and the like, capable of storing as one liquid, exhibiting good adhesiveness to various base materials, and capable of giving a cured product such as colorless transparent silicone gel, a liquid optical transparent adhesive comprising the composition, a transparent cured product of the composition, and various articles and the like having the cured products.SOLUTION: A heat durable organopolysiloxane composition includes: (A) an organopolysiloxane having a specific structure having two or more unsabstituted or substituted amino groups in a molecule; and (B) an organo(poly)siloxane having a specific structure having two or more blocked isocyanate groups which generate isocyanate groups by eliminating blocking agents by heating in a molecule, and having an organo(poly)siloxane chain as a spacer, by a specific ratio.SELECTED DRAWING: None

Description

The present invention provides a thermosetting organopolysiloxane composition using an organo(poly)siloxane having two or more blocked isocyanate groups in the molecule, and a colorless and transparent composition obtained by curing the thermosetting organopolysiloxane composition. The present invention relates to a cured product such as a silicone gel of No. 1, and various articles having the cured product.

Compositions that cure to silicone rubbers have been known for a long time and have been widely used in industry. Curing reactions (reaction mechanisms) of conventional silicone rubbers include condensation curing, addition curing, and UV curing.

Of these, the condensation-curing type undergoes a hydrolysis/condensation reaction between the hydroxyl group or hydrolyzable silyl group in the base polymer and the hydrolyzable group in the cross-linking agent due to moisture (moisture) in the air. Since hardening progresses gradually toward the deep part, it has the disadvantage of being inferior in fast hardening properties in the deep part.

The addition-curable type cures by hydrosilylation addition reaction between the alkenyl groups in the base polymer and the SiH groups in the cross-linking agent in the presence of a platinum catalyst. In some cases, the catalytic action is inhibited and curing does not proceed sufficiently. In addition, since the storability as a single component is poor, refrigeration storage is required, and for storage at room temperature, it is necessary to use a two-liquid component type in which the catalyst and the cross-linking agent are stored separately.

In the UV-curing type, irradiation with ultraviolet rays induces radical polymerization of alkenyl groups in the base polymer and hydrosilylation addition reaction between the alkenyl groups in the base polymer and SiH groups in the cross-linking agent, thereby promoting cross-linking. Harden. Curing forms using radical polymerization are subject to curing inhibition by oxygen, and UV addition reaction types are subject to curing inhibition in the presence of compounds containing nitrogen atoms or sulfur atoms, similar to the aforementioned addition reaction types.

In addition, as a technique for improving the curing speed of the condensation curing type, in Japanese Patent Application Laid-Open No. 2002-226708 (Patent Document 1), both ends of the molecular chain are blocked with a hydrolyzable silyl group having an oxime structure as a leaving group. Organic compounds having at least one carbonyl group (C=O group) in one molecule and organic compounds having at least one primary amino group ( _NH2 group) in one molecule for diorganopolysiloxane A composition containing This uses the water produced as a by-product of the ketimine formation reaction between carbonyl groups and primary amino groups to improve deep-curing and fast-curing properties. It is difficult to say that the curing speed is sufficient in comparison.

In the technology of storing a one-component addition-curable type at room temperature, JP-A-2016-98337 (Patent Document 2) describes an aliphatic unsaturated hydrocarbon group-containing organopolysiloxane, a thermally conductive filler, an organohydro A one-part addition-curable silicone composition containing genpolysiloxane and a platinum group metal complex with a specific organophosphorus compound as a ligand has been proposed, but the oxygen permeability coefficient is 1×10 ⁻¹² cm ³ ( STP) The storability at room temperature cannot be ensured unless it is sealed and stored in a container made of a material with a viscosity of STP) cm/cm ² ·s·Pa or less.

As a technique for improving curing inhibition due to UV curing type oxygen, Japanese Patent Laid-Open No. 2020-12024 (Patent Document 3) does not require heating or UV irradiation at the time of use, and oxygen in the atmosphere is used as a reaction trigger, room temperature. provides an oxygen-curable silicone composition that cures at , but requires handling in the absence of oxygen.

As described above, each curing type has its own problems, and development of an elastomer material that solves these problems is required.

Japanese Patent Application Laid-Open No. 2002-226708 JP 2016-98337 A JP 2020-12024 A Japanese Patent Application No. 2021-087289

The present inventors have developed an elastomer material that solves the above problems in Japanese Patent Application No. 2021-087289 (Patent Document 4). A thermosetting organopolysiloxane composition that can be stored as a single component and can give a cured product such as a silicone elastomer that exhibits good adhesion to various substrates, a cured product thereof, and the cured product. We provide various items that we have. However, the cured product is white and cannot be used for applications such as optical bonding where colorless transparency is important.

The present invention has been made in view of the above circumstances, is excellent in storage stability and deep-part curability, is not subject to curing inhibition by oxygen, nitrogen, sulfur, etc., can be stored as a single liquid, and can be used for various substrates. A thermosetting organopolysiloxane composition capable of giving a cured product such as a colorless and transparent silicone gel exhibiting good adhesion, a liquid optically transparent adhesive (LOCA) comprising the composition, and the transparency of the composition An object of the present invention is to provide a cured product and various articles having the cured product.

The inventors of the present invention have extensively studied to achieve the above object, and as a result, the main agent (base polymer), and has two or more blocked isocyanate groups in the molecule that generate an isocyanate group (-N=C=O) by eliminating the blocking agent by heating (80 to 150 ° C.) as a cross-linking agent, and a spacer The inventors have found that a thermosetting organopolysiloxane composition containing a predetermined amount of an organo(poly)siloxane represented by the general formula (2) having an organo(poly)siloxane chain as , solves the above problems. , which led to the present invention.

（式中、Ｒ¹は独立に水素原子又は炭素数１～１０の非置換若しくは置換の一価炭化水素基であり、Ｒ²、Ｒ³はそれぞれ独立に炭素数１～１０の非置換又は置換の一価炭化水素基であり、ａは独立に１～６の整数であり、ｍは０～２０の整数、ｎは１以上の整数であり、分子中のｎの合計は２０～２，０００である。但し、主鎖中のジオルガノシロキサン単位とオルガノシルセスキオキサン単位はランダムに配列されてよい。）
（Ｂ）下記一般式（２）で示されるブロック化イソシアネート基を分子中に２個以上有するオルガノ（ポリ）シロキサン：１～４０質量部

（式中、Ｒ⁴は独立に炭素数１～１０の非置換又は置換一価炭化水素基であり、Ｒ⁵は独立にラクタム類、ピラゾール類、オキシム類、フェノール類、アルコール類、β－ジケトン類およびβ－ケトエステル類から選ばれるブロック化剤の残基であり、Ｒ⁶は独立に炭素数１～１０の非置換又は置換の一価炭化水素基であり、ｐは０～１００の整数であり、ｑは独立に５～３０の整数である。）を含有する熱硬化性オルガノポリシロキサン組成物。
［２］
（Ｂ）成分のオルガノ（ポリ）シロキサンが８０～１５０℃においてブロック化剤を脱離するものである［１］に記載の熱硬化性オルガノポリシロキサン組成物。
［３］
（Ｂ）成分が、下記一般式（３）

（式中、Ｒ⁴、Ｒ⁵は前記の通りである。）
で示されるシランカップリング剤と、下記一般式（４）

（式中、Ｒ⁶、ｑは前記の通りである。）
で示される両末端にシラノール基を有するオルガノ（ポリ）シロキサンとの縮合反応物である［１］又は［２］に記載の熱硬化性オルガノポリシロキサン組成物。
［４］
一成分型である［１］～［３］のいずれかに記載の熱硬化性オルガノポリシロキサン組成物。
［５］
［１］～［４］のいずれかに記載の熱硬化性オルガノポリシロキサン組成物からなる液状光学透明性接着剤。
［６］
［１］～［４］のいずれかに記載の熱硬化性オルガノポリシロキサン組成物を硬化してなる透明硬化物。
［７］
［６］に記載の硬化物を有する自動車用部品。
［８］
［６］に記載の硬化物を有する自動車用オイルシール。
［９］
［６］に記載の硬化物を有する電気・電子用部品。
［１０］
［６］に記載の硬化物を有する建築用構造物。
［１１］
［６］に記載の硬化物を有する土木工事用構造物。
［１２］
［６］に記載の硬化物を封止剤とするパワーモジュール。 That is, the present invention provides the following thermosetting organopolysiloxane composition, a liquid optically transparent adhesive (LOCA) comprising the thermosetting organopolysiloxane composition, and the thermosetting organopolysiloxane composition. Provides transparent cured products obtained by curing, various articles containing such cured products (automobile parts, automotive oil seals, electrical and electronic parts, architectural structures, civil engineering structures, power modules, etc.) It is something to do.
[1]
(A) 100 parts by mass of a linear or branched organopolysiloxane having a viscosity of 20 to 1,000,000 mPa·s at 23° C. represented by the following general formula (1), and

(In the formula, R ¹ is independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are each independently an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms. is a monovalent hydrocarbon group, a is independently an integer of 1 to 6, m is an integer of 0 to 20, n is an integer of 1 or more, and the sum of n in the molecule is 20 to 2,000 However, the diorganosiloxane units and organosilsesquioxane units in the main chain may be arranged randomly.)
(B) Organo(poly)siloxane having two or more blocked isocyanate groups represented by the following general formula (2) in the molecule: 1 to 40 parts by mass

(wherein R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ⁵ is independently lactams, pyrazoles, oximes, phenols, alcohols, β-diketones and β-ketoesters, R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and p is an integer of 0 to 100. and q is independently an integer of 5 to 30.).
[2]
The thermosetting organopolysiloxane composition according to [1], wherein the organo(poly)siloxane of component (B) eliminates the blocking agent at 80 to 150°C.
[3]
(B) component is the following general formula (3)

(In the formula, R ⁴ and R ⁵ are as defined above.)
and a silane coupling agent represented by the following general formula (4)

(In the formula, R ⁶ and q are as defined above.)
The thermosetting organopolysiloxane composition according to [1] or [2], which is a condensation reaction product with an organo(poly)siloxane having silanol groups at both ends represented by
[4]
The thermosetting organopolysiloxane composition according to any one of [1] to [3], which is a one-component type.
[5]
A liquid optically transparent adhesive comprising the thermosetting organopolysiloxane composition according to any one of [1] to [4].
[6]
A transparent cured product obtained by curing the thermosetting organopolysiloxane composition according to any one of [1] to [4].
[7]
An automobile part having the cured product according to [6].
[8]
An automotive oil seal comprising the cured product according to [6].
[9]
An electrical/electronic part comprising the cured product according to [6].
[10]
An architectural structure comprising the cured product according to [6].
[11]
A structure for civil engineering work comprising the cured product according to [6].
[12]
A power module using the cured product according to [6] as a sealant.

The thermosetting organopolysiloxane composition of the present invention can be stored for a long period of time as a one-part composition at room temperature (23° C.±15° C.), and is not subject to curing inhibition by oxygen, nitrogen, sulfur, etc. It cures rapidly when heated, has excellent deep-curing properties, and exhibits excellent adhesiveness to various substrates. - It can be suitably used for electronic parts, architectural structures, civil engineering structures, power modules, liquid optically transparent adhesives (LOCA), and the like.

The present invention provides a thermosetting organopolysiloxane composition using an organo(poly)siloxane having two or more blocked isocyanate groups in the molecule, particularly an unsubstituted or substituted amino group (broadly defined amino group) in the molecule. The main component (base polymer) is an organopolysiloxane having two or more in it, and a blocked isocyanate group (that is, an isocyanate group (-N=C=O) that eliminates the blocking agent by heating (80 to 150 ° C.) amide structure, urethane structure, or unsubstituted or substituted urea structure obtained by reacting with a specific blocking agent having active hydrogen) in the molecule, and an organo (poly)siloxane chain as a spacer (Poly)siloxane is contained as a cross-linking agent (curing agent), and the isocyanate group generated in the cross-linking agent by heating reacts (aminolysis) with the amino group (broadly defined) in the base polymer to cross-link (harden). 3. A thermosetting organopolysiloxane composition that has a urea structure (urea bond) at a cross-linking point and gives a transparent cured product such as a silicone gel; A thermosetting organopolysiloxane composition that is 5-dimethylpyrazole, a liquid optically transparent adhesive (LOCA) comprising the thermosetting organopolysiloxane composition, and a cured thermosetting organopolysiloxane composition. and transparent cured products such as silicone gels, and various articles having such cured products.

The present invention will be described in detail below. In the present invention, viscosity is a value measured by a rotational viscometer according to the method specified in JIS Z8803.

（式中、Ｒ¹は独立に水素原子又は炭素数１～１０の非置換若しくは置換の一価炭化水素基であり、Ｒ²、Ｒ³はそれぞれ独立に炭素数１～１０の非置換又は置換の一価炭化水素基であり、ａは独立に１～６の整数であり、ｍは０～２０の整数、ｎは１以上の整数であり、分子中のｎの合計は２０～２，０００である。但し、主鎖中のジオルガノシロキサン単位とオルガノシルセスキオキサン単位（即ち、主鎖中でｎ、ｍそれぞれで括られるカッコ内の単位）はランダムに配列されてよい。） [(A) component organopolysiloxane]
Component (A) acts as the main component (base polymer) of the thermosetting organopolysiloxane composition of the present invention, and has a viscosity of 20 to 1,000 at 23° C. represented by the following general formula (1). 000 mPa·s linear or branched organopolysiloxane.

(In the formula, R ¹ is independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are each independently an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms. is a monovalent hydrocarbon group, a is independently an integer of 1 to 6, m is an integer of 0 to 20, n is an integer of 1 or more, and the sum of n in the molecule is 20 to 2,000 However, the diorganosiloxane units and organosilsesquioxane units in the main chain (that is, the units in parentheses enclosed by n and m in the main chain) may be arranged randomly.)

Component (A) is a diorganosiloxane whose main chain consists of repeating difunctional diorganosiloxane units ((R ² ) ₂ SiO _2/2 ) and which constitutes the main chain, as shown in formula (1). A linear or branched molecule which may contain a branched structure consisting of a trifunctional organosilsesquioxane unit ((R ³ )SiO _3/2 ) at any position in the repeating structure of the unit A structure in which all ends of the molecular chain (both ends of the molecular chain in the case of a straight chain, both ends of the main chain and all ends of the branched chain in the case of a branched chain) are unsubstituted or substituted amino groups ( (i.e., -NR ¹ H, preferably -NH ₂ ), specifically unsubstituted or substituted aminoalkyl groups (i.e., -(CH ₂ ) _a -NR ¹ H, preferably -(CH ₂ ) _a - NH ₂ )-blocked, linear or branched organopolysiloxanes with viscosities of 20 to 1,000,000 mPa·s at 23°C.

In the above formula (1), R ¹ is independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, and R ² and R ³ are each independently is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms. Examples of unsubstituted or substituted monovalent hydrocarbon groups for R ¹ , R ² and R ³ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group and tert-butyl group. a pentyl group, a hexyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, an alkyl group such as a decyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, alkenyl groups such as hexenyl groups; aryl groups such as phenyl groups and tolyl groups; aralkyl groups such as benzyl groups and phenylethyl groups; and groups substituted with halogen atoms, such as 3,3,3-trifluoropropyl group. R ¹ is preferably a hydrogen atom, a methyl group or an ethyl group, and R ² and R ³ are preferably a methyl group, an ethyl group, a phenyl group or a 3,3,3-trifluoropropyl group. These R ¹ , R ² and R ³ may be the same group or different groups.

In the above formula (1), m representing the number of trifunctional organosilsesquioxane units ((R ³ )SiO _3/2 ) having a branched structure is an integer of 0 to 20, and component (A) is When it is a linear organopolysiloxane, m is 0, and when component (A) is a branched organopolysiloxane, m is an integer of 1 to 20, preferably an integer of 1 to 10, and more It is preferably an integer of 1-5.

In the above formula (1), the number of repeating bifunctional diorganosiloxane units ((R ² ) ₂ SiO _2/2 ) constituting the main chain or constituting the main chain and branched chains (side chains) (or degree of polymerization) is an integer of 1 or more, and when m is 0 (that is, the component (A) has a branched structure in the molecule, the trifunctional organosilsesquioxane unit ((R ³ ) In the case of a linear organopolysiloxane containing no SiO _3/2 ), n in the molecule is preferably an integer of 20 to 2,000, more preferably an integer of 40 to 1,200. and more preferably an integer of 50-800. Further, when m is an integer of 1 to 20 (that is, the component (A) contains a trifunctional organosilsesquioxane unit ((R ³ )SiO _3/2 ) having a branched structure in the molecule. branched organopolysiloxane), each n in the molecule is independently preferably an integer of 1 to 1,999, more preferably an integer of 10 to 1,800, still more preferably 10 to 1,200. , particularly preferably an integer from 15 to 800, most preferably from 20 to 400, the sum of n in the molecule (i.e., one n in the main chain and the sum of m n in the branched chains ) is an integer from 20 to 2,000, preferably an integer from 40 to 1,200, more preferably an integer from 50 to 800.

In the above formula (1), a representing the repeating number of methylene groups in the linear alkylene group —(CH ₂ ) _a — which is the linking group between the terminal silicon atom of the polysiloxane structure and the unsubstituted or substituted amino group is It is independently an integer of 1-6, preferably an integer of 2-4, more preferably 2 or 3.

In the present invention, the degree of polymerization (or molecular weight) is, for example, the number average degree of polymerization (or number average molecular weight) in terms of polystyrene in gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF) or the like as a developing solvent, or It can be obtained as a result of ²⁹ Si-NMR analysis or the like.

The organopolysiloxane of component (A) has a viscosity at 23° C. of 20 to 1,000,000 mPa·s, preferably 50 to 100,000 mPa·s, more preferably about 100 to 50,000 mPa·s. I wish I had. In the present invention, viscosity can be measured by a rotational viscometer (eg, BL type, BH type, BS type, cone plate type, rheometer) or the like.
The (A) component organopolysiloxane may be used alone or in combination of two or more.

（式中、Ｒ⁴は独立に炭素数１～１０の非置換又は置換一価炭化水素基であり、Ｒ⁵は独立にラクタム類、ピラゾール類、オキシム類、フェノール類、アルコール類、β－ジケトン類およびβ－ケトエステル類から選ばれるブロック化剤の残基であり、Ｒ⁶は独立に炭素数１～１０の非置換又は置換の一価炭化水素基であり、ｐは０～１００の整数であり、ｑは独立に５～３０の整数である。） [(B) component organo (poly) siloxane]
Component (B) acts as a cross-linking agent (curing agent) for the thermosetting organopolysiloxane composition of the present invention, and has two blocked isocyanate groups represented by the following general formula (2) in the molecule. It is an organo(poly)siloxane having the above and having an organo(poly)siloxane chain as a spacer.

(wherein R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ⁵ is independently lactams, pyrazoles, oximes, phenols, alcohols, β-diketones and β-ketoesters, R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and p is an integer of 0 to 100. and q is independently an integer from 5 to 30.)

In general formula (2), the blocked isocyanate group represented by -NH(C=O)R is blocked with a specific blocking agent having an active hydrogen in the isocyanate group (-N=C=O) ^, A group having an amide structure, a urethane structure, or an unsubstituted or substituted urea structure (that is, a temporarily inactivated group obtained by reacting an isocyanate group with a blocking agent) and heated (80 to 150°C) by releasing (eliminating) a blocking agent (R ^H ) such as 3,5-dimethylpyrazole or ε-caprolactam as a leaving group (leaving substance) to form an isocyanate group (-N=C=O ). By this heating, the isocyanate groups generated in the component (B), which is a cross-linking agent, and the amino groups (amino groups in a broad sense) in the above component (A), which is the base polymer, react (aminolysis) to cross-link (harden). ), an organopolysiloxane cured product such as a silicone gel having a urea structure (urea bond) at a cross-linking point can be obtained.

In the general formula (2), R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, such as Alkyl such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, nonyl group and decyl group cycloalkyl groups such as cyclohexyl groups; alkenyl groups such as vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups and hexenyl groups; aryl groups such as phenyl groups and tolyl groups; and alkoxy-substituted alkyl groups such as methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group in which the hydrogen atoms of these unsubstituted monovalent hydrocarbon groups are partially substituted with alkoxy groups, etc. is mentioned. ^R4 is preferably a methyl group, an ethyl group, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group or an isopropenyl group.

In the general formula (2), R ⁵ is a blocking agent (R ⁵ H ) from which the active hydrogen has been eliminated.

The blocking agent (R ⁵ H), which is a leaving group (leaving compound) generated by heating the organo(poly)siloxane of the general formula (2), includes, for example, ε-caprolactam, δ-valerolactam and γ-butyrolactam. lactams such as carbazole, dimethylpyrazole, triazole and other pyrazoles, formaldoxime, acetaldoxime, acetone oxime, methylethylketoxime, methylisobutylketoxime, cyclohexanone oxime and other oximes, phenol, cresol, ethylphenol, butylphenol alcohols such as 2-hydroxypyridine, dimethyl malonate and diethyl malonate; β-ketoesters such as methyl acetoacetate and ethyl acetoacetate; and β-diketones such as acetylacetone.

In general formula (2) above, R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms. Examples of unsubstituted or substituted monovalent hydrocarbon groups for R ⁶ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl and hexyl. Alkyl groups such as octyl group, 2-ethylhexyl group, nonyl group and decyl group, cycloalkyl groups such as cyclohexyl group, alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group and hexenyl group , aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and phenylethyl group, and hydrogen atoms of these unsubstituted monovalent hydrocarbon groups are partially substituted with halogen atoms such as chlorine, fluorine and bromine. groups such as 3,3,3-trifluoropropyl group. R ⁶ is preferably a methyl group, an ethyl group, a phenyl group or a 3,3,3-trifluoropropyl group. This R ⁶ may be the same group or different groups.

The component (B) organo(poly)siloxane is usually composed of a hydrolyzable organosilane compound (silane coupling agent alone) having a blocked isocyanate group (—NH(C=O)R ⁵ ) as a starting material, and a terminal It can be obtained as a condensation reaction product with an organo(poly)siloxane having a silanol group.
In the general formula (2), p represents the degree of condensation of the organo(poly)siloxane, p is an integer of 0 to 100, preferably an integer of 0 to 50, more preferably an integer of 1 to 10. is. q indicates the degree of polymerization of the organo(poly)siloxane chain as a spacer, and q is independently an integer of 5 to 30, preferably an integer of 10 to 20, more preferably an integer of 15 to 20. .

（式中、Ｒ⁴、Ｒ⁵は前記の通りである。）
で示されるシランカップリング剤と、下記一般式（４）

（式中、Ｒ⁶、ｑは前記の通りである。）
で示される両末端にシラノール基を有するオルガノ（ポリ）シロキサンとを、触媒の存在下で縮合反応させることで製造できる。この反応は、下記反応式［Ｉ］で表される。 Component (B), organo(poly)siloxane, is represented by the following formula (3), for example:

(In the formula, R ⁴ and R ⁵ are as defined above.)
and a silane coupling agent represented by the following general formula (4)

(In the formula, R ⁶ and q are as defined above.)
can be produced by condensing an organo(poly)siloxane having silanol groups at both ends represented by in the presence of a catalyst. This reaction is represented by the following reaction formula [I].

（式中、Ｒ⁴、Ｒ⁵、Ｒ⁶、ｐ、ｑは前記の通りである。）

(In the formula, R ⁴ , R ⁵ , R ⁶ , p and q are as defined above.)

（式中、Ｍｅはメチル基、Ｅｔはエチル基である。） Examples of the silane coupling agent represented by formula (3) are given below.

(In the formula, Me is a methyl group and Et is an ethyl group.)

Examples of the organo(poly)siloxane having silanol groups at both ends represented by the above formula (4) are shown below.

In the above condensation reaction, the amount of organo(poly)siloxane having silanol groups at both ends represented by formula (4) used is 0.5 to 1 mol per 1 mol of the silane coupling agent represented by formula (3). is preferred, and an amount of 0.6 to 0.99 mol is more preferred. If the amount of the organo(poly)siloxane having silanol groups at both ends represented by the formula (4) is too small, the condensation reaction may not proceed sufficiently. There is

As the catalyst, those generally used for hydrolysis of alkoxysilanes can be used, such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin dioctate, and dimethyltin dimethoxide. , dimethyltin diacetate and other organic tin compounds (tin catalysts), tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, dimethoxytitanium diacetylacetonate, titanium diisopropoxybis(ethylacetoacetate) and other organic titanium compounds compounds (titanium catalyst), hydrochloric acid, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid (acidic catalyst), triethylamine, tetramethylguanidine, diazabicycloundecene (basic catalyst), and the like. Among these, it is particularly desirable to use an acidic catalyst, particularly hydrochloric acid, sulfuric acid, and methanesulfonic acid. In addition, when using an acidic catalyst, it is preferable to neutralize it after completion of the reaction.

The amount of the catalyst added is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the mass of the silane coupling agent. If the amount of catalyst added is too small, the reaction may not be completed, and if the amount of catalyst added is too large, it is economically disadvantageous.

In the production of component (B) organo(poly)siloxane, commonly used solvents may be used, for example, aromatic hydrocarbons such as toluene, xylene and benzene, pentane, hexane, heptane, nonane, Aliphatic hydrocarbons such as octane and decane, ethers such as dimethyl ether and methyl ethyl ether, halogenated hydrocarbons such as perchloroethane, perchlorethylene, trichloroethane, chloroform and carbon tetrachloride, alcohols such as methanol and ethanol, etc. is mentioned.
The amount of the solvent used is not particularly limited, but it is usually used in the range of 0.1 to 500 parts by mass, preferably 0.5 to 300 parts by mass, per 100 parts by mass of the silane coupling agent used.

The reaction conditions for the above condensation reaction are usually 0° C. or higher and lower than 80° C., preferably 0 to 40° C., and a mixed solution of a silane coupling agent and an organo(poly)siloxane having a terminal silanol group serving as a catalyst and a spacer. is added dropwise, and the reaction is allowed to proceed at a temperature of 0° C. to 80° C., preferably 0 to 60° C., for 1 to 48 hours, preferably 3 to 30 hours. If the temperature during the reaction is too low, the reaction may not be completed, and if the temperature is too high, the blocking agent of the silane coupling agent may be eliminated. On the other hand, if the reaction time is too short, the reaction may not be completed, and if the reaction time is too long, the productivity is adversely affected.

Further, after the reaction is completed, it is possible to distill off the unreacted substances and the solvent by heating under a reduced pressure environment. At this time, the degree of pressure reduction is preferably from 10 ^-8 to 3,000 Pa, more preferably from 10 ^-8 to 2,000 Pa, and the temperature is preferably from 0°C to less than 80°C, more preferably from 0 to 40°C. If the degree of pressure reduction is too high, it may become difficult to distill off unreacted substances and solvents. On the other hand, if the temperature is too low, it may become difficult to distill off the unreacted substances and solvent, and if it is too high, the blocking agent for the silane coupling agent may be eliminated.

（式中、Ｍｅはメチル基、Ｅｔはエチル基である。） Specific examples of the (B) component organo(poly)siloxane include those represented by the following formulas.

(In the formula, Me is a methyl group and Et is an ethyl group.)

Component (B) is added in an amount of 1 to 40 parts by mass, preferably 2 to 25 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is less than 1 part by mass, a crosslinked structure may not be formed and the composition may not be cured. If the amount of component (B) exceeds the above upper limit of 40 parts by mass, the curability of the composition may be significantly reduced.
(B) component may be used individually by 1 type, and may use 2 or more types together.

[Other ingredients]
As other optional components, various generally known additives such as adhesion imparting agents, plasticizers, and fungicides that do not impair the transparency of the cured product obtained from the thermosetting organopolysiloxane composition of the present invention are added. may be added.

The thermosetting organopolysiloxane composition of the present invention can be obtained by uniformly mixing predetermined amounts of the above components in a dry atmosphere. The thermosetting organopolysiloxane composition of the present invention is cured by heating to 80 to 150° C., and the molding method and curing conditions are determined according to known methods and conditions depending on the type of composition. can be adopted.

The thermosetting organopolysiloxane composition of the present invention can be stored stably for a long period of time as a one-component composition in the form of a one-component solution at room temperature. It hardens easily by
This is because the blocking agent contained in the organo(poly)siloxane having two or more blocked isocyanate groups is released by heating at 80 to 150°C (that is, it is not easily released below 80°C). It can be stored stably in one liquid.

The thermosetting organopolysiloxane composition of the present invention is heated (80 to 150° C.) so that the organo(poly)siloxane having two or more blocked isocyanate groups eliminates the blocking agent to form two isocyanate groups. The isocyanate group in the organo(poly)siloxane reacts with the amino group in the organopolysiloxane having two or more unsubstituted or substituted amino groups in the molecule to form urea. Since it forms bonds and crosslinks (hardens), it has excellent deep-part curability and is not affected by oxygen, nitrogen, sulfur, etc.

Since the thermosetting organopolysiloxane composition of the present invention forms urea bonds as described above, it exhibits good adhesion to a wide range of substrates such as various engineering plastics and metals, and is colorless and transparent. Since it can give cured products such as silicone gel, it is useful as a liquid optically transparent adhesive (LOCA). Further, transparent cured silicone products (organopolysiloxane cured products) such as silicone gels obtained by curing the thermosetting organopolysiloxane composition of the present invention are used for automotive parts, automotive oil seals, electrical and electronic parts. , building structures, civil engineering structures, power modules and the like. The method for using the silicone cured product obtained by curing the thermosetting organopolysiloxane composition of the present invention in the above-mentioned article may follow a conventionally known method.

Transparent silicone cured products such as silicone gels obtained by curing the thermosetting organopolysiloxane composition of the present invention are particularly suitable for engineering plastics (nylon 66 (PA66), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS)). etc.) and has excellent adhesion to metals (aluminum, brass, etc.).

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples. Viscosity is a value measured by a rotational viscometer at 23° C. according to the method specified in JIS Z 8803.

（式中、Ｅｔはエチル基である。） [Synthesis Example 1] Synthesis of organosiloxane 1 In a 300 mL three-necked flask equipped with a stirrer and a thermometer, silane coupling having a 3,5-dimethylpyrazole residue as a blocked isocyanate group represented by the following formula 20 g (58 mmol) of the agent and 14 g of ethanol were charged and stirred at room temperature (23° C., the same applies hereinafter in Examples) under a nitrogen atmosphere. A mixed solution of 59.52 g (44 mmol) of dimethylpolysiloxane having one silanol group at each end represented by the following formula, 0.2 g of sulfuric acid, and 6 g of ethanol was added dropwise thereto over about 1 hour. After stirring for 8 hours at room temperature, 10 g of sodium acetate was added for neutralization and filtered off. Ethanol was distilled off from the filtrate under conditions of 40° C. and 400 Pa to obtain an average trimer organosiloxane 1 represented by the following formula [II]. This step is represented by the following reaction formula.

(In the formula, Et is an ethyl group.)

[Example 1]
A linear dimethylpolysiloxane having a viscosity of 5,000 mPa·s at 23° C. and having both ends of the molecular chain blocked with γ-aminopropyl groups (in general formula (1), R ¹ = hydrogen atom, a = 3, m 24 parts by mass of the organosiloxane 1 obtained in Synthesis Example 1 was added to 100 parts by mass of dimethylpolysiloxane corresponding to = 0 and n in the molecule is about 250, and the mixture was sufficiently mixed to obtain composition 1.

（式中、Ｅｔはエチル基である。） [Comparative Example 1]
A linear dimethylpolysiloxane having a viscosity of 5,000 mPa·s at 23° C. and having both ends of the molecular chain blocked with γ-aminopropyl groups (in general formula (1), R ¹ = hydrogen atom, a = 3, m = 0, and n in the molecule corresponds to about 250), 4 parts by mass of an organosiloxane oligomer represented by the following molecular formula was added to 100 parts by mass, and thoroughly mixed to obtain composition 2.

(In the formula, Et is an ethyl group.)

[Test method]
The compositions prepared in Example 1 and Comparative Example 1 were evaluated as follows. Table 1 shows the evaluation results of hardness, curing inhibition, storage stability and transparency (appearance), and Table 2 shows the evaluation results of adhesiveness.

Hardness The composition prepared in Example 1 above was filled in a glass petri dish with an inner diameter of 10 mm and heated at 120 ° C. for 180 minutes. Penetration defined in JIS K 6249) was measured.
Each composition prepared in Comparative Example 1 above was filled in an aluminum petri dish with an inner diameter of 60 mm and heated at 120 ° C. for 90 minutes. Asker C hardness according to test type C test method was measured.

On a butyl rubber sheet obtained by curing-inhibiting sulfur vulcanization, a sheet of 30 mm long, 30 mm wide, and 1 mm thick of each composition prepared in Example 1 and Comparative Example 1 was prepared. C. for 180 minutes, and 120.degree. C. for 90 minutes in Comparative Example 1 to confirm whether the interface was cured.

Preservability Each composition prepared in Example 1 and Comparative Example 1 was placed in a 50 mL glass bottle and stored at 40°C.

Transparency (appearance)
Each composition prepared in Example 1 and Comparative Example 1 was cured in a glass petri dish with an inner diameter of 10 mm to a thickness of 1.5 cm, and the appearance was visually observed. The curing temperature and time were 120° C.×180 minutes for Example 1 and 120° C.×90 minutes for Comparative Example 1.

Adhesion A simple adhesion test was performed by curing each composition prepared in Example 1 and Comparative Example 1 above to a thickness of 1 mm on an adherend having a width of 25 mm and a length of 100 mm, and pulling it off by hand. gone. A case where the cohesive failure rate of the adhesive surface was 50% or more was rated as ◯, and a case where the cohesive failure rate was less than 50% was rated as x. Polyphenylene ether (PPE), polyphenylene sulfide (PPS), 6,6-nylon, polybutylene terephthalate (PBT), epoxy resin, brass, and aluminum were used as adherends. The curing temperature and time were 120° C.×180 minutes for Example 1 and 120° C.×90 minutes for Comparative Example 1.

From the above results, Example 1, which is the thermosetting organopolysiloxane composition of the present invention, is not inhibited by sulfur, can be stored as a single component, and exhibits good adhesion to various substrates. It was shown to be a colorless and transparent silicone gel. Comparative Example 1 is free from curing inhibition due to sulfur, can be stored as a single component, and exhibits good adhesion to various substrates, but is white and does not have gel-like softness. Therefore, it can be said that the thermosetting organopolysiloxane composition of the present invention can be suitably used for applications such as optical bonding where colorless transparency is required.

From the above results, the thermosetting organopolysiloxane composition of the present invention has excellent curing inhibition resistance, can be stored as a single component, exhibits good adhesion to various substrates, and the cured product is colorless. It has been confirmed to be transparent and is suitable for various articles (automotive parts, automotive oil seals, electrical and electronic parts, construction structures, civil engineering structures, power modules, liquid optically transparent adhesives, etc.) found that it can be used for

Claims (12)

(A) 100 parts by mass of a linear or branched organopolysiloxane having a viscosity of 20 to 1,000,000 mPa·s at 23° C. represented by the following general formula (1), and

(In the formula, R ¹ is independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are each independently an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms. is a monovalent hydrocarbon group, a is independently an integer of 1 to 6, m is an integer of 0 to 20, n is an integer of 1 or more, and the sum of n in the molecule is 20 to 2,000 However, the diorganosiloxane units and organosilsesquioxane units in the main chain may be arranged randomly.)
(B) Organo(poly)siloxane having two or more blocked isocyanate groups represented by the following general formula (2) in the molecule: 1 to 40 parts by mass

(wherein R ⁴ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ⁵ is independently lactams, pyrazoles, oximes, phenols, alcohols, β-diketones and β-ketoesters, R ⁶ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and p is an integer of 0 to 100. and q is independently an integer from 5 to 30.)
A thermosetting organopolysiloxane composition containing 2. The thermosetting organopolysiloxane composition according to claim 1, wherein the organo(poly)siloxane of component (B) eliminates the blocking agent at 80 to 150.degree. (B) component is the following general formula (3)

(In the formula, R ⁴ and R ⁵ are as defined above.)
and a silane coupling agent represented by the following general formula (4)

(In the formula, R ⁶ and q are as defined above.)
3. The thermosetting organopolysiloxane composition according to claim 1 or 2, which is a condensation reaction product with an organo(poly)siloxane having silanol groups at both ends represented by ##STR1##. The thermosetting organopolysiloxane composition according to any one of claims 1 to 3, which is a one-component type. A liquid optically transparent adhesive comprising the thermosetting organopolysiloxane composition according to any one of claims 1 to 4. A transparent cured product obtained by curing the thermosetting organopolysiloxane composition according to any one of claims 1 to 4. An automotive part comprising the cured product according to claim 6. An automotive oil seal comprising the cured product according to claim 6. An electric/electronic part comprising the cured product according to claim 6. An architectural structure comprising the cured product according to claim 6 . A structure for civil engineering work comprising the cured product according to claim 6 . A power module comprising the cured product according to claim 6 as a sealant.