JP2002037969A - Room temperature-curable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture-curable modified silicone composition excellent in transparency. SOLUTION: This room temperature-curable composition is characterized by comprising (A) a copolymer containing hydrolyzable functional group- containing silicon and whose molecular chain is composed substantially of (a) 1-8C alkyl group-bearing (meth)acrylic alkyl ester monomer unit and (b) >=10C alkyl group-bearing (meth)acrylic alkyl ester monomer unit, (B) a moisture-curing catalyst and (C) amorphous high-purity fused silica glass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a room temperature curable composition containing silicon bonded to a hydrolyzable functional group,
Room temperature curable composition with excellent deep curability and useful as automotive and architectural seals, industrial seals, adhesives, coatings, electrical or electronic sealants or pottings, or universal adhesives. About.

[0002]

2. Description of the Related Art Silicone compositions which are polymerized by causing a chemical reaction in the presence of moisture in the air are well known, and are used for sealing materials, adhesives, coating materials and potting materials. In the silicone composition, a silicon atom having a hydrolyzable functional group is siloxane-bonded by moisture in the air. For this reason, after the adhesive is applied, the adhesive is cured by exposing it to air, so that energy such as heating and light irradiation is not required, which is advantageous in terms of environment and cost.

A silicone composition is a polymer of silicon formed by a siloxane bond, and has excellent heat resistance and flexibility. However, the cured product is porous or is easily attacked by an ionic substance. Is often not suitable.

On the other hand, so-called modified oxyalkylene polymers having silicon-terminated hydrolyzable functional groups or (meth) acrylate copolymers having silicon-terminated hydrolyzable functional groups are known. Silicones have also been used as moisture-curable resins. In particular, the modified silicone having the above composition has advantages such as excellent adhesive strength.

[0005]

When the modified silicone is used as an adhesive / sealant, a material having excellent transparency is often required so that the protruding portion is not conspicuous. For example, Japanese Patent Application Laid-Open No. 2000-38560 discloses a moisture-curable adhesive composition having excellent transparency, using fumed silica treated with hexamethyldisilazane as a filler. However, since the particle size of the fumed silica is small and the viscosity of the composition increases remarkably even if a small amount is added, a large amount cannot be added. Therefore, not only the effect of reinforcing the filler is small, but also the effect of cost reduction is small.

In general, silicone and modified silicone require an inorganic filler or the like as a reinforcing material because the cured product is brittle. As the inorganic filler, for example, fumed silica,
Calcined silica, precipitated silica, crushed silica, fused silica, quartz powder, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, precipitated calcium carbonate,
Examples include heavy calcium carbonate, magnesium carbonate, zinc carbonate, limestone clay, kaolin clay, calcined clay, carbon black, and the like, which have been conventionally used. After the addition of these fillers, the composition becomes white, and when carbon black is added, it becomes black, so that excellent transparency cannot be obtained. When the modified silicone is cured without adding a filler, a cured product having excellent transparency can be obtained, but the adhesive strength is low and it is economically disadvantageous.

Accordingly, the present invention, despite having excellent transparency, has a reinforcing property of a cured product and good adhesiveness, and exhibits excellent storage stability in containers such as cartridges and tubes. It is an object of the present invention to provide a modified silicone composition which has a small increase in viscosity even when a large amount of filler is added, and gives excellent transparency, reinforcing property of a cured product and good adhesion after curing.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve such a problem, and as a result, have found that (A) has a hydrolyzable functional group-containing silicon and the molecular chain is substantially (a). )
(Meth) acrylic acid alkyl ester monomer units having an alkyl group having 1 to 8 carbon atoms and (b) 10 to 30 carbon atoms
Room temperature curable composition containing a copolymer comprising the above-mentioned alkyl group-containing (meth) acrylic acid alkyl ester monomer unit, (B) a moisture curing catalyst, and (C) amorphous high-purity fused silica glass. I came to. Further, as a preferred embodiment, when an oxyalkylene polymer having silicon having a hydrolyzable functional group is further added to the composition, a more excellent room temperature curable composition can be obtained.

[0009]

Hereinafter, the present invention will be described in detail. The component (A) used in the present invention has silicon having a hydrolyzable functional group, and is a (meth) acrylic copolymer (hereinafter referred to as a copolymer (A)) of the monomer units (a) and (b).
It is). (M) having an alkyl group having 1 to 8 carbon atoms, which is a monomer unit of (a) constituting the component (A)
The acrylic acid alkyl ester monomer unit has the general formula

[0010]

Embedded image (Wherein, R ¹ represents an alkyl group having 1 to 8 carbon atoms, and R ² represents a hydrogen atom or a methyl group). (B)
The (meth) acrylic acid alkyl ester monomer unit having an alkyl group having 10 or more carbon atoms, which is a monomer unit of
General formula

[0011]

Embedded image (Wherein, R ² is the same as above, and R ³ is an alkyl group having 10 or more carbon atoms). As R ¹ in the general formula (I), for example, a methyl group, an ethyl group, a propyl group, an n-butyl group, a t-butyl group, a 2-ethylhexyl group and the like have 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. And more preferably 1 to 2 alkyl groups. The alkyl group of R ¹ may be used alone or as a mixture of two or more.

R ³ in the above general formula (II) is, for example, lauryl group, tridecyl group, cetyl group, stearyl group, alkyl group having 22 carbon atoms, behenyl group and the like, and usually 10 to 30 carbon atoms. , Preferably 10-2
0 long-chain alkyl groups. The alkyl group of R ³ may be used alone as in the case of R ¹ , or may be a mixture of two or more kinds such as a mixture of 12 and 13 carbon atoms.

The molecular chain of the copolymer (A) is substantially (a)
And the monomer unit of (b). The term “substantially” as used herein means that the total of the monomer units of (a) and (b) present in the copolymer (A) is 50% by weight. Means to exceed. The total of the monomer units of (a) and (b) is preferably at least 70% by weight. Further, the abundance ratio of the monomer unit of (a) to the monomer unit of (b) is 95: 5 by weight ratio.
40:60 is preferred, and 90:10 to 60:40 is more preferred.

The monomer units other than (a) and (b) which may be contained in the copolymer (A) include, for example, acrylic acid such as acrylic acid and methacrylic acid; acrylamide, methacrylamide, N- Monomers containing an amide group such as methylol acrylamide and N-methylol methacrylamide, an epoxy group such as cricidyl acrylate and glycidyl methacrylate, and an amino group such as diethylaminoethyl acrylate, diethylaminoethyl methacrylate and aminoethyl vinyl ether; other acrylonitrile, iminol Examples include monomer units derived from methacrylate, styrene, α-methylstyrene, alkyl vinyl ether, vinyl chloride, vinyl acetate, vinyl propionate, ethylene, and the like. The copolymer (A) preferably has a number average molecular weight of 500 to 100,000 from the viewpoint of easy handling.

The component (A) is a copolymer (A) having hydrolyzable functional group-containing silicon bonded thereto. Hydrolyzable functional group-containing silicon can form a siloxane bond and be crosslinked, and is a silicon functional group bonded to a hydrolyzable group. This is a well-known functional group and has a feature that it can be crosslinked at room temperature. Specific examples of the hydrolyzable functional group include a halogen atom, a hydrogen atom,
Examples thereof include an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an aminooxy group, a mercapto group, and an alkenyloxy group. Among these, an alkoxy group such as a methoxy group and an ethoxy group is preferred from the viewpoint of mild hydrolyticity.

The hydrolyzable functional group-containing silicon preferably has two hydrolyzable functional groups per silicon. The number of hydrolyzable functional group-containing silicon in the copolymer (A) may be one or more on average from the viewpoint of obtaining sufficient curability.
The number is preferably at least 1, more preferably at least 1.5, and the number average molecular weight per apparently reactive silicone functional group is 3
It is preferable that it exists so that it may be 00-4000.

The copolymer (A) used in the present invention is obtained by vinyl polymerization, for example, vinyl polymerization by radical reaction.
It can be obtained by polymerizing a monomer giving units represented by the general formulas (I) and (II) by an ordinary solution polymerization method, a bulk polymerization method, or the like. The reaction is carried out using the monomer and, if necessary, a radical initiator, preferably a number average molecular weight of 5
If necessary, a chain transfer agent such as n-dodecyl mercaptan or t-dodecyl mercaptan is added to obtain a copolymer (A) of 100 to 100,000.
To react. The solvent may or may not be used, but when used, it is preferable to use a non-reactive solvent such as ethers, hydrocarbons and acetates.

There are various methods for introducing a hydrolyzable functional group-containing silicon into the copolymer (A). For example, a compound having a polymerizable unsaturated bond and a reactive silicone functional group (eg, CH ₂ = CHSi (OC
H ₃ ) ₃ ) and a monomer having units represented by the general formulas (I) and (II) and copolymerizing the compound, a compound having a polymerizable unsaturated bond and a reactive functional group (for example, (Acrylic acid) is added to a monomer giving units represented by the general formulas (I) and (II) and copolymerized, and then the resulting copolymer is reacted with a hydrolyzable functional group and a reactive functional group. compound having a functional group such as a method of reacting with (e.g. isocyanate groups and -Si (OCH ₃₎ compounds having ₃ group) and the like that can be. Details of the production method are described in JP-A-63-112462.

The component (A) is, for example, Kanegafuchi Chemical Industry Co., Ltd.
MS polymer or MA polymer.

As the moisture curing catalyst as the component (B),
Moisture curing catalysts used for moisture curable silicones, such as metal carboxylate and alkoxytitanium. For example, dibutyltin bistriethoxysilicate, dibutyltin dimethoxide, dibutyltin diacetate,
Dibutyltin dilaurate, butyltin tri-2-ethylhexoate, lead-2-ethyloctoate, iron-2
-Ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, zinc-2-
Metal salts of organic acid carboxylic acids such as ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, tin butylate, tin naphthenate, zinc naphthenate, cobalt naphthenate, zinc stearate; tetrabutyl Titanate, tetra-2-ethylhexyl titanate,
Organic titanates such as triethanolamine titanate and tetra (isopropenyloxy) titanate;
Organotitanium compounds such as organosiloxytitanium and β-carbonyltitanium; alkoxyaluminum compounds; quaternary ammonium salts such as benzyltriethylammonium acetate; lower fatty acid salts of alkali metals such as potassium acetate, sodium acetate and lithium oxalate; dimethylhydroxyl Amines, dialkylhydroxylamine such as diethylhydroxyamine and the like. Among these, chelating compounds such as dibutyltin dimethoxide and dibutyltin bisacetylacetonate are more preferable because they have high activity as a room temperature curing catalyst and increase the curing rate of the curable composition. These curing catalysts
They may be used alone or in combination of two or more.

The amount of the moisture curing catalyst used is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, based on the total weight of the room temperature curable composition. If the amount of the moisture-curing catalyst is too small, the curing rate of the obtained resin composition becomes slow. On the other hand, if the amount is too large, not only physical properties such as tensile properties of the obtained cured product are lowered, but also economically disadvantageous. Profit, both of which are undesirable.

The component (C) of the present invention is an amorphous high-purity fused silica glass filler. Since the high-purity crystalline quartz filler has a high refractive index, a transparent compound cannot be obtained in combination with the component (A) of the present composition. The high-purity fused quartz glass used in the present invention preferably has a SiO2 content of 99.8% or more and has extremely few impurities including alkali ions. By using this, not only transparency is improved, but also acid resistance is improved, and excellent electric properties such as high dielectric strength, low conductivity, and low dielectric loss are provided.

As the component (C), those having various particle sizes can be used. If a 50% weight average particle size is measured when the particle size distribution is measured by a laser method, a particle size of 1 to 100 μm is desirable. Furthermore, particles of 2 to 50 μm are more desirable. When the average particle size is smaller than 2 μm, the obtained composition tends to be cloudy, and the transparency of the cured product is deteriorated. When the average particle size is larger than 50 μm, the transparency of the composition is excellent, but when used as an adhesive, the large particles work as an anti-blocking agent, so that the adhesive strength is greatly reduced.

The amorphous high-purity fused silica glass filler may be used without surface treatment, or may be surface-treated with a coupling agent. Examples of usable coupling agents include, for example, organic titanate compounds, organic aluminum compounds,
Organic zirconium compounds, alkoxysilanes and the like can be mentioned. Specific organic titanate compounds, for example, tetrapropoxy titanium, tetrabutoxy titanium,
Tetrakis (2-ethylhexyloxy) titanium, tetrastearyloxytitanium, diproxybis (acetylacetonato) titanium, titanium propoxyoctylene glycolate, titanium stearate, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (Dioctyl pyrophosphate) titanate,
Tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate)
Oxyacetate titanate, tris (dioctyl pyrophosphate) ethylene titanate and the like can be mentioned. Organic aluminum compounds such as acetoalkoxyaluminum diisopropylate and organic zirconium compounds such as zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium lactate and zirconium butyrate stearate can be used. Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, bistris (2-methoxyethoxy) silane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, and N- (2-amino Ethyl) 3-aminopropylmethyltrimethoxysilane, 3
-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, Examples thereof include 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and hexamethyldisilazane. These fillers can contribute to marked improvement in the tensile strength, impact strength and moisture resistance of the cured product by the treatment of the coupling agent.

The amount of the amorphous high-purity fused silica glass filler as the component (C) is preferably about 1 to 300 parts, more preferably 5 to 200 parts, per 100 parts of the component (A). If the amount of the amorphous high-purity fused silica glass filler is below this range, the cured product is soft and the reinforcing effect is small. On the other hand, when the amount of the amorphous high-purity fused silica glass filler exceeds this range, the viscosity of the compound increases, and handling becomes difficult.

The amount of the component (C) is as follows:
About 0.1 to 200 parts is preferable for 00 parts,
100 parts is more preferred.

It is preferable to further add a curing accelerator or an adhesion promoter to the composition of the present invention. These examples are γ-
Aminosilanes such as (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ
And silane coupling agents such as mercaptosilanes such as mercaptopropyltrimethoxysilane and epoxysilanes such as γ-glycidoxypropyltrimethoxysilane. One or more of these are suitably used.

The amount of these curing accelerators and adhesion promoters used is 0.01 to 1 with respect to the total weight of the room temperature curable composition.
0 parts by weight, especially 0.1 to 5 parts by weight is preferred. If the amounts of the curing accelerator and the adhesion promoter are too small, the curing speed is not accelerated. On the other hand, if it is too large, not only physical properties such as elongation of the obtained cured product are deteriorated, but also it is economically disadvantageous, and both are not preferable.

In addition to the above essential components (A) to (C), if necessary, reinforcing materials, fibrous fillers, oil resistance improvers, heat resistance improvers, cold resistance improvers, pigments, dyes, etc. Coloring agents, thixotropic agents, dehydrating agents, rust inhibitors, adhesion improvers, oil-resistant adhesion improvers, solvents, plasticizers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, surfactants Etc. may be added. These are added in appropriate amounts according to the required physical properties. As the reinforcing material, for example, fumed silica, calcined silica, precipitated silica, ground silica, fused silica, quartz powder; diatomaceous earth; iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide; precipitated calcium carbonate, heavy Calcium carbonate; magnesium carbonate; zinc carbonate; limestone clay, kaolin clay, calcined clay; carbon black.

[0030]

Next, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited by these Examples. In the description of the following examples, all parts are by weight.

Synthesis Example a Production of Component (A) Butyl Acrylate 63 5 g, methyl methacrylate 3
89 g, 117 g of stearyl methacrylate, TSMA
30.5 g of (γ-methacryloxypropyldimethoxymethylsilane), 12.0 g of AIBN (azobisisobutyronitrile), and 255 g of xylene were mixed and stirred to uniformly dissolve. 30 g of the mixture was placed in a 200 ml four-necked flask equipped with a stirrer and a condenser, and heated to 80 ° C. in an oil bath while passing nitrogen gas. After a few minutes, the polymerization started and generated heat. After the heat generation became mild, the remaining mixed solution was gradually dropped using a dropping funnel over 3 hours to perform polymerization. The polymerization was terminated when no heat generation was observed. The number average molecular weight was 9,700, the polymerization conversion was 99%, and the resin solid content was 70%. This was designated as compound a.

Example 1 To 100 parts of the component (A) prepared in Synthesis Example 1, 3 parts of γ-aminopropyltrimethoxysilane (A-
1110), 3 parts of dibutyltin dimethoxide (SCAT-27 manufactured by Sankyo Co., Ltd.), and Fuselex E- manufactured by Tatsumori Corporation as an amorphous high-purity fused silica glass filler.
70 parts of No. 1 (particle size: 11 μm, purity: 99.9%) were mixed in an anhydrous state and vacuum defoamed to prepare a one-part moisture-curable modified silicone composition.

Example 2 As the component (A), compound a, Kaneka Chemical Industry MA44
0 was used. MA440 is composed of a (meth) acrylic acid alkyl ester monomer unit having an alkyl group having 1 to 8 carbon atoms and a (meth) acrylic acid alkyl ester monomer unit having an alkyl group having 10 to 30 or more carbon atoms. It is a mixture of a copolymer having an alkoxysilyl group at a molecular terminal and an oxyalkylene polymer having a silicon having a hydrolyzable functional group. (A) 3 parts of γ-aminopropyltrimethoxysilane (A-1110 of Nippon Unicar), 3 parts of dibutyltin dimethoxide (SCAT-27 of Sankyoki), amorphous high purity fused silica glass in 100 parts of component Hughes Rex E-2 manufactured by Tatsumori Corporation (average particle diameter 7 μm, purity 99.9) as a filler
%) And ZA-30 (average particle size: 5 μm, purity: 99.9%) were mixed in an anhydrous state and vacuum degassed to prepare a one-part moisture-curable modified silicone composition.

Comparative Example 1 100 parts of MA440 modified silicone, 3 parts of γ-aminopropyltrimethoxysilane, 2 parts of dibutyltin bistriethoxysilicate, and 70 parts of a water-repellent crystalline quartz glass filler (CAW-1000 manufactured by Tatsumori Co., Ltd.) Were mixed in an anhydrous state and degassed under vacuum to prepare a one-part moisture-curable composition.

Comparative Example 2 A fused silica glass having a purity of 99.5% (Imsil A108 manufactured by Tatsumori Co., Ltd .;
m) was performed in the same manner as in Comparative Example 1 except that m) was used.

Evaluation of transparency of cured product:
After coating in the form of a sheet having a thickness of 25 mm and curing at 23 ° C. for 7 days,
The dial was placed below and judged according to the following criteria. A: Characters are clearly visible. ：: Characters are difficult to see but can be recognized.
X: Characters are not visible at all.

Evaluation of Rubber Physical Properties: The compositions of the examples and comparative examples were formed into 2 mm sheets, left at 23 ° C. for 7 days, cured to obtain a rubber elastic body, and the rubber physical properties were examined. In the rubber physical property evaluation test, the tensile strength, elongation, and hardness of the cured rubber were measured based on JIS K6301.

Evaluation of storage stability: Judgment is made according to the following criteria. ◎: 23 ° C. of the adhesive filled in the laminate tube
After 12 months of storage, the increase in viscosity is within 1.4 times.
×: The adhesive filled in the laminate tube was 1 at 23 ° C.
After two months storage, the increase in viscosity is more than 2.0 times.

Table 1 shows the composition examples of Examples 1 to 4 and the results of the rubber properties.

The composition of the present invention is a one-part composition,
It is a moisture-curable modified silicone composition having excellent transparency, fast curing property, deep curing property and storage stability. Shows excellent adhesion to a wide range of materials such as metals, plastics, rubber, glass, wood, inorganic materials, and seals for automobiles and buildings, industrial seals, adhesives, coatings, and seals for electrical and electronic equipment. It is useful as a stop material or a potting material, or a universal adhesive.

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[Procedure amendment]

[Submission date] October 27, 2000 (2000.10.
27)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve such a problem, and as a result, have found that (A) has a hydrolyzable functional group-containing silicon and the molecular chain is substantially (a). )
(Meth) acrylic acid alkyl ester monomer units having an alkyl group having 1 to 8 carbon atoms and (b) 10 to 30 carbon atoms
A room temperature curable composition containing a copolymer comprising a (meth) acrylic acid alkyl ester monomer unit having an alkyl group of (B), (B) a moisture curing catalyst, and (C) amorphous high-purity fused silica glass. I got it. Further, as a preferred embodiment, when an oxyalkylene polymer having silicon having a hydrolyzable functional group is further added to the composition, a more excellent room temperature curable composition can be obtained.

Claims (2)

[Claims] (A) a (meth) acrylic acid alkyl ester monomer unit having (A) a hydrolyzable functional group-containing silicon and a molecular chain substantially having (a) an alkyl group having 1 to 8 carbon atoms; (B) a copolymer comprising a (meth) acrylic acid alkyl ester monomer unit having an alkyl group having 10 to 30 or more carbon atoms, (B) a moisture curing catalyst, (C) an amorphous high-purity fused quartz glass, A room temperature curable composition comprising: 2. The room temperature curable composition according to claim 1, wherein an oxyalkylene polymer having a hydrolyzable functional group-containing silicon is further added to the component (A).