JP3408549B2 - Graft-modified ladder silicone and composition thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable silicone composition capable of exhibiting a wide range of physical properties ranging from hard to soft and excellent in moldability and a graft-modified ladder silicone constituting this composition.

[0002]

2. Description of the Related Art A chain polysiloxane represented by dimethylpolysiloxane is generally known as a silicone, but a siloxane bond constitutes a molecular skeleton, and this bond has a very high internal rotational energy. It is low and flexible enough to rotate freely. For this reason, chain polysiloxane can provide materials with excellent properties such as flexibility, cold resistance, and impact resistance shown in silicone rubber, but are not suitable for applications requiring rigidity and strength. It is said that.

On the other hand, when a raw material silane at the time of synthesizing silicone is combined with a D unit which is a bifunctional siloxane and a T unit which is a trifunctional siloxane and condensed, an oligomer having a three-dimensional network structure is obtained, which is further heated. When condensed, it becomes a so-called silicone resin. However, since this is a condensation reaction that produces water, alcohol, etc.,
It is impossible to form a thick film having a certain thickness or more, and it is merely used as a silicone varnish for the purpose of electrical insulation, adhesion, protective coating and the like.

Further, a silicone resin composed only of T units of trifunctional siloxane is polyorganosilsesquioxane so-called ladder silicone, and the molecular skeleton has a ladder structure, and free rotation of siloxane bond is restricted. As a result, although it has excellent heat resistance, hardness, and scratch resistance, it is fragile and cannot form a thick film above a certain level, like the silicone varnish.

Further, conventionally, it has not been performed to combine a ladder silicone with a chain polysiloxane. This is because the two are completely incompatible. Therefore, as an alternative to this, a resin having a carbon skeleton such as polysulfone, polycarbonate, or polyimide as a hard segment for imparting rigidity to a chain polysiloxane is compounded, and various types are used. It is used for purposes.

However, in these methods, the amount of components other than silicone mixed in becomes large, and the original characteristics of silicone, such as heat resistance, flame resistance, electrical characteristics, radiation resistance, gas permeability, and oxidation resistance are listed. It is unavoidable that such a decrease will occur.

[0007]

Therefore, an object of the present invention is to obtain a novel silicone composition capable of realizing a wide range of physical properties from soft to superhard by combining a chain silicone and a ladder silicone. Especially. In addition, compared with conventional silicone resins, it is possible to mold thick materials, and not only thermosetting but also curable silicone that is excellent in molding processability such as rapid curing at room temperature by photocuring such as UV curing. To obtain the composition. Well
In addition, with one component that constitutes such a curable silicone composition
To obtain a graft-modified ladder silicone.

[0008]

[Means for Solving the Problems] Such a problem is not found in the side chain.
The ladder silicone to have a saturated group, and formulated thiol group or chain graft-modified resulting polysiloxane is reacted ladder silicone and ladder silicone graft modified ladder silicone having an unsaturated group, a chain polysiloxane cured Is solved by a hydrophilic silicone composition.

The present invention will be described in detail below. The ladder silicone used in the present invention has a repeating structure of m (m is an integer of 1 or more) repeating units of a silsesquioxane unit as represented by the following general formula (I).

[0010]

[Chemical 5]

The side chains R1 and R2 in the repeating structural unit represented by the general formula (I) have the following general formula (II):
It is those containing at least one ladder silicone per molecule an unsaturated group shown.

[0012]

[Chemical 6]

In the general formula (II), R3 is a hydrogen atom or a methyl group, R4 is an unsubstituted or substituted divalent hydrocarbon group, X is an oxygen atom, a carboxyl group, a sulfur atom or a thio compound. The side chains R1 and R2 other than the above general formula (II) are selected from an alkyl group having 1 to 3 carbon atoms and a substituted or unsubstituted phenyl group. The one having an alkyl group having 4 or more carbon atoms as a side chain is not preferable because the performance such as hardness and heat resistance is deteriorated.

The ladder silicone represented by the general formula (I) is obtained by synthesizing a corresponding trialkoxysilane or trichlorosilane by hydrolysis and condensation in the presence of an acid or basic catalyst, and its terminal group is Depending on the raw material, it is composed of silanol, alkoxysilane, or both. The terminal group can be used by capping by reacting it with trimethylalkoxysilane, trimethylchlorosilane or the like, if necessary.

The chain polysiloxane used in the present invention is represented by the following general formula (IV), and the side chains R6, R7 and / or the terminal groups are represented by the above general formula (II). Unsaturated group or the following general formula (III)
Thiols groups represented a are those containing at least one chain polysiloxanes per molecule. In the general formula (IV), n
Is an integer of 1 or more.

[0016]

[Chemical 7]

[0017]

[Chemical 8]

In the general formula (III), R ₅ is unsubstituted or
Represents a substituted divalent hydrocarbon group. In addition, side chains R6 and R
Examples of the group of 7 other than the above general formulas (II) and (III) include
It is a group selected from an alkyl group having 1 to 3 carbon atoms and a substituted or unsubstituted phenyl group. The one having an alkyl group having 4 or more carbon atoms as a side chain is not preferable because the performance such as hardness and heat resistance is deteriorated.

The graft-modified ladder silicone of the present invention is obtained by grafting the above-mentioned chain polysiloxane on the side chain of the above-mentioned ladder silicone. To obtain this graft product, the ladder silicone as a raw material and the chain polysiloxane are dissolved in a common solvent and grafted. As the solvent, benzene, toluene, carbon tetrachloride, acetone, butanol, isopropanol, dioxane,
Ethyl acetate, ethylene glycol monoethyl ether, etc. are exemplified, and these are used alone or in combination of two or more.

The graft reaction proceeds by heating a solution in which a ladder silicone and a chain polysiloxane are dissolved, but a catalyst such as an organic peroxide or an amine such as trimethylamine is added to accelerate the reaction rate. You can also do it. After completion of the grafting reaction, the solvent is removed by vacuum distillation or the like to obtain a uniformly compatible liquid grafted product. Of course, when the curable silicone composition of the present invention is used in the form of a solution such as a coating agent, the solvent may coexist. Further, in the graft-modified ladder silicone of the present invention, the required graft ratio is also influenced by the chain length of the chain polysiloxane, but it is desirable that at least one grafted per one molecule of the ladder silicone.

The curable silicone composition of the present invention
The above-mentioned graft-modified ladder silicone has the general formula
With the ladder silicone represented by (I) and the general formula (IV)
The chain polysiloxane represented is an essential component.
is there. The composition of each component in this curable silicone composition
The total amount (100 parts by weight in total) is 95 weight of ladder silicone
Parts by weight or less, chain polysiloxane 80 parts by weight or less, graph
To modified ladder silicone 3 parts by weight or more, 100 parts by weight
I'm full. If the ladder silicone exceeds 95 parts by weight, the material becomes poor in flexibility and becomes brittle, and if the chain polysiloxane exceeds 80 parts by weight, the object of the present invention cannot be achieved in terms of strength and hardness. If the graft-modified ladder silicone is less than 3 parts by weight, it is impossible to make the ladder silicone and the chain polysiloxane compatible with each other.

When the curable silicone composition of the present invention is produced, other components such as ladder silicone and chain polysiloxane are added in advance during the grafting reaction for obtaining the graft-modified ladder silicone, and after the reaction. ,
It can be used as it is as a curable silicone composition, and physical entanglement of molecular chains can be expected, which is advantageous in terms of physical properties.

The curable silicone composition of the present invention can be made thermosetting by adding a radical generator to it, and can be made photocurable by adding a radical generator and a photosensitizer. be able to. Examples of the radical generator include organic peroxides and diazo compounds such as azobisisobutyronitrile, benzoyl peroxide, dicumyl peroxide, dilauryl peroxide, cumene hydroperoxide and tertiary butyl perbenzoate. Also,
As the photosensitizer, various ones conventionally known as photopolymerization initiators can be used, and specifically, acetophenone, propiophenone, benzophenone,
Examples thereof include fluorenone, benzaldehyde, fluorene, anthraquinone, 3-methylacetophenone and 4,4'-dimethoxybenzophenone. These photopolymerization initiators may be used alone or in combination of two or more. In the present invention, it is also possible to further enhance the ultraviolet curability by using a so-called sensitization aid such as a tertiary amine together with the above photopolymerization initiator. Three
As the tertiary amine, various aliphatic or aromatic tertiary amines can be used, and N-dimethanolamine, triethanolamine, N-methyldiethanolamine, triethylamine, ethyl P-dimethylaminobenzoate, etc. are exemplified.

In addition, in the curable silicone composition of the present invention, it is possible to adjust the properties of the composition and the physical properties after curing by using a reactive monomer and a reactive diluent.
Examples of these monomers and the like include (meth) acrylate compounds, vinyl compounds and thiol compounds. Further, at this time, it is possible to further improve the physical properties by using a polyfunctional compound of these compounds. The curable silicone composition of the present invention can be used after diluting it with a solvent, if necessary. Further, the curable silicone composition of the present invention may be mixed with various substances and compounds for the purpose of modifying the physical properties of the cured product, or depending on the application of the cured product, and cured. These additives include polymerization inhibitors such as hydroquinone and P-methoxyphenol, coloring pigments such as phthalocyanine blue, phthalocyanine green, and titanium white. Thickeners and fillers such as silica, calcium carbonate, kaolin, and various ultraviolet rays such as clay. Absorbents, antioxidants and the like may be added. In order to three-dimensionally cure the curable silicone composition of the present invention after coating or shaping, heating, light irradiation or a combination of both can be performed.

[0025]

[Function] Ladder silicone and chain polysiloxane are so different from each other that their molecular morphology is completely different from each other. However, by coexisting with the graft-modified ladder silicone of the present invention, a uniform compatible system can be obtained. You can It is considered that this is because the ladder silicone and the chain polysiloxane are compatibilized by interposing a compatible graft polymer between them. As a result, both the hard segment and the soft segment can be made of silicone, and a wide range of physical properties from soft to superhard can be realized by changing the ratio of both. Also,
Since the curable silicone composition of the present invention undergoes a radical reaction or an ionic reaction without by-products like conventional silicone varnishes and ladder silicones upon curing, rapid curing at room temperature and molding of thick materials are possible. Become.

[0026]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Unless otherwise specified, "parts" in Examples and Comparative Examples means "parts by weight".

(Example 1) Methyltriethoxysilane and γ-mercaptopropyltrimethoxysilane were mixed at a molar ratio of 7: 1,
Hydrolysis and condensation were performed to remove the solvent and by-products to obtain a viscous liquid substance (ladder silicone) having a number average molecular weight of 4,100 and a weight average molecular weight of 8,500. 85 parts of the above ladder silicone using 100 parts of isopropyl alcohol as a solvent,
Add α, ω-dimethacryloxypropyl-modified dimethylpolysiloxane (15 parts) and trimethylamine (0.4 parts) to give 8
The reaction was allowed to proceed at 0 ° C for 5 hours. Polymerization inhibitor metquinone 0.
When 4 parts were added and the solvent was distilled off under reduced pressure, it was transparent.
A viscous liquid (graft modified ladder silicone) was obtained.

(Example 2) Methyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane were mixed at a molar ratio of 5: 1, hydrochloric acid was added for hydrolysis and condensation, and then n-butylamine was used. After proceeding with the condensation, the number average molecular weight is 3,800 and the weight average molecular weight is 8,0 excluding the solvent and the reaction by-products.
A viscous liquid substance (ladder silicone) of 00 was obtained. The above ladder silicone 20 parts Graft modified ladder silicone synthesized in Example 1 60 parts Trimethylolpropane trimethacrylate 18 parts α, ω-dimethacryloxypropyl modified dimethylpolysiloxane 2 parts t-butyl perbenzoate 0.2 parts 4,4 When 0.2 part of'-dimethoxybenzophenone was mixed, a uniform transparent liquid was obtained. This product was sandwiched between quartz glass plates with a thickness of 1 mm, and was irradiated with 1 J / cm 2 using a high-pressure mercury lamp on the front side and once on the back side each time, and then the glass plate mold was removed.
When cured by heating at 0 ° C. for 1 hour, a hard resin plate having excellent transparency was obtained. The pencil hardness of this hard resin plate was as high as 4H, and no change was observed even after heating at 300 ° C. for 1 hour.

Example 3 Methyltriethoxysilane, vinyltrimethoxysilane and phenyltrimethoxysilane in a molar ratio of 7: 2: 1.
After mixing and hydrolyzing and condensing to remove by-products, the number average molecular weight is 4,800 and the weight average molecular weight is 10,30.
A viscous liquid of 0 (ladder silicone) was obtained. Using 100 parts of isopropyl alcohol as a solvent, 70 parts of the above-mentioned ladder silicone, 30 parts of α, ω-divinyl-modified dimethylpolysiloxane and 0.3 part of azobisisobutyronitrile were added and reacted at 80 ° C. for 3 hours. When 0.4 part of the polymerization inhibitor metquinone was added and the solvent was distilled off under reduced pressure, a transparent viscous liquid (graft-modified ladder silicone) was obtained. The above graft-modified ladder silicone 80 parts α, ω-divinyl-modified dimethylpolysiloxane 18 parts divinylbenzene 2 parts t-butylperbenzoate 0.5 parts were mixed to obtain a uniform transparent liquid. Pour this product between glass plates with a thickness of 1 mm 80
When cured by heating at 1 ° C, 1 hour, 120 ° C, 1 hour, 180 ° C, 1 hour, a transparent and elastic resin sheet was obtained. This one has a tensile strength of 120 kg.
/ Cm 2, elongation 35%, showing improvement in strength compared to silicone rubber.

[0030]

As described above, the curable silicone composition of the present invention has the inherent heat resistance, flame resistance, and
It is a material that retains performance such as electrical characteristics, water resistance, and weather resistance, and is excellent in hardness and strength. Further, compared with the conventional silicone varnish, a thick material can be molded, and it can be quickly cured at room temperature and the molding time can be shortened. Therefore, the curable silicone composition of the present invention can be used in a wide range of fields such as construction, electricity, electronics, automobiles and machines.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 77/44 C08L 83/10

Claims (2)

(57) [Claims] 1. A compound represented by the general formula (I): [However, in the formula (I), R ₁ and R ₂ are each represented by the general formula (II): (In the formula (II), R ₃ represents a hydrogen atom or a methyl group, R ₄ represents an unsubstituted or substituted divalent hydrocarbon group, X represents an oxygen atom, a carboxyl group, a sulfur atom or a thio compound). The unsaturated group represented by R ₁ and R ₂ other than the group represented by the general formula (II) is a group selected from an alkyl group having 1 to 3 carbon atoms and a substituted or unsubstituted phenyl group. is there. m represents an integer of 1 or more. ] In the ladder silicone having at least one unsaturated group in the side chain represented by the following general formula (IV), (However, in the formula (IV), the side chain R ₆ , R ₇ or the terminal group is
The above general formula (II) and the following general formula (III): It is an unsaturated group or a thiol group represented by . Also, R
The groups other than those represented by the general formulas (II) and (III) of R ₆ and R ₇ are groups selected from an alkyl group having 1 to 3 carbon atoms and a substituted or unsubstituted phenyl group. n represents an integer of 1 or more. In formula (III), R ₅ is an unsubstituted or substituted divalent hydrocarbon. ) At least 1 per molecule of unsaturated group or thiol group in the side chain or terminal represented by
Graft-modified ladder silicone obtained by grafting chain polysiloxanes each having. 2. The graft-modified ladder silicone according to claim 1, which is not less than 3 parts by weight and less than 100 parts by weight, and the side chain is unsaturated.
The above general formula containing at least one group per molecule
95 parts by weight or less of the ladder silicone represented by (I) ,
The above general formula (I ) containing at least one unsaturated group or thiol group per molecule in the side chain and / or terminal
A curable silicone composition containing 80 parts by weight or less of a chain polysiloxane represented by V) as an essential component.