JPH09208830A - Curable composition and plastic film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve weather resistance and heat of a curable compsn. which imparts water repellency, lubricity, and releasability to the front and back sides of a substrate. SOLUTION: This compsn. comprises a polydimethylsiloxane block copolymer having polydimethylsiloxane blocks and vinyl polymer blocks having hydrolyzable silyl groups and may further contain a hydrolyzable silane comd. as a cross- linker and, if necessary, a cure catalyst. A plastic film which is useful as a substrate of a magnetic tape or of a thermal transfer ink ribbon and of which the front and/or back side has been coated with the compsn. is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint which is effective mainly in fields where weather resistance, lubricity and mold release properties are required.
For example, as a paint to prevent icing and snow accretion, as a paint for preventing sticking of paper, and on the surface or back surface of a substrate such as polyvinyl chloride or polyester film or electrophotographic carrier, or a substrate such as cloth or paper, water repellency and lubricity. The present invention relates to a curable composition useful as a coating agent that imparts functions such as releasability and heat resistance, and a plastic film having the front surface and / or the back surface coated with the curable composition. The plastic film, cloth or paper coated with the curable composition of the present invention on the front surface and / or the back surface is a magnetic tape, a base material of a thermal transfer ink ribbon, a release film, an adhesive tape base material, an adhesive label or a sealing base material, casting,
It is used as a medical tape base material, a process film or paper used for producing polyurethane foam, a food packaging sheet or a wrapping paper, and the like.

[0002]

BACKGROUND OF THE INVENTION For example, silicone-based paints are used as paints for preventing icing and snow accretion, or paints for preventing graffiti and paper sticking. Also, for the purpose of imparting environmental resistance, durability, wear resistance, etc. to iron powder, ferrite, etc. used in electrophotography,
Alternatively, a plastic film base material such as polyester-based polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) used as a base material for a magnetic tape or a thermal transfer ink ribbon may be provided with water repellency, lubricity, heat resistance, or the like on the front surface or the back surface. A treatment with a coating agent is performed for the purpose of imparting.

[0003]

2. Description of the Related Art Heretofore, as such paints and coating agents, compositions containing reactive silicone, polydimethylsiloxane oil, etc. have been mainly used.

[0004]

However, in the composition containing the above-mentioned reactive silicone, polydimethylsiloxane oil, etc., the adhesion and transparency of the coating film may be deteriorated, or the surface of the coating film may be tacky. , Or water repellency,
There is a problem that the effect of imparting lubricity, heat resistance and the like to the front surface or the back surface of the substrate is not sufficient, and the sustainability of the effect is insufficient.

[0005]

As a means for solving the above-mentioned conventional problems, the present invention provides a polydimethylsiloxane block copolymer having a polydimethylsiloxane moiety and a vinyl polymer moiety having a hydrolyzable silyl group. A curable composition comprising a polymer (A) is provided, and the polydimethylsiloxane block copolymer (A) is also provided.
And a cross-linking agent (B) and / or a curing catalyst (C), wherein the cross-linking agent (B) is an alkoxysilane, chlorosilane, silane coupling agent or polymer thereof, and a single amount of the silane coupling agent. Or one or more compounds selected from a hydrolyzate obtained by hydrolyzing a hydrolyzable silyl group of a polymer or a polymer, wherein the curing catalyst (C) is an aluminum chelating agent,
The present invention provides a curable composition which is one or more compounds selected from organic tin, organic titanate, organic acids, and inorganic acids, and a magnetic material obtained by applying the curable composition to the front surface and / or the back surface. Provided is a plastic film useful as a base material for a tape or a thermal transfer ink ribbon.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

[Polydimethylsiloxane block copolymer (A)]
The curable composition of the present invention comprises a polydimethylsiloxane block copolymer (A) having a polydimethylsiloxane moiety and a vinyl polymer moiety having a hydrolyzable silyl group.
The mixture is mainly. First, the polydimethylsiloxane block copolymer (A) having a polydimethylsiloxane portion and a vinyl polymer portion having a hydrolyzable silyl group will be described. The polydimethylsiloxane block copolymer (A) has the following structure. (A ¹ * a ² ) _l a ¹ * (a ¹ * a ² ) _m a ² * (a ¹ * a ² ) _n where l, m, and n are integers from ^{1 to} 10 a ¹ is the following structure Having a polydimethylsiloxane moiety

Embedded image a ² is a vinyl polymer moiety having a hydrolyzable silyl group having the following structure

Embedded image And R ₁ , R ₂ and R ₃ represent an alkoxyl group having 1 to 4 carbon atoms or an aliphatic hydrocarbon having 1 to 8 carbon atoms. However, the case where all of R ₁ , R ₂ and R ₃ are aliphatic hydrocarbons having 1 to 8 carbon atoms is excluded. First, in order to synthesize the polydimethylsiloxane block copolymer (A), a living polymerization method, a polymer initiator method, a polymer chain transfer method and the like can be mentioned. Industrially, or method is used. preferable. In the polymer initiator method, for example,

Embedded image And a vinyl monomer having a hydrolyzable silyl group by using the polymer azo catalyst having a polydimethylsiloxane moiety introduced therein and other copolymerizable vinyl monomer if desired. If you add and polymerize,
The block copolymer A can be efficiently produced. If a polymeric initiator such as a peroxide type polymer initiator and an azo type polymer initiator is used, polymerization can be performed in two steps. For example, when using an azo type polymer initiator,

[Chemical 6]

Embedded image Here, m, n, n ', and l are integers of 1 or more M ₁ is a macromonomer having the following structure

Embedded image

Embedded image M ₂ is another vinyl monomer copolymerizable with M ₁ (including a vinyl monomer having a hydrolyzable silyl group). R is an example

Embedded image

Embedded image Etc. In the polymer chain transfer method,

Embedded image

Embedded image HS to polydimethylsiloxane having functional groups such as
-CH ₂ COOH or HS-CH ₂ CH ₂ COOH is added to use a polydimethylsiloxane having an SH group, and a vinyl monomer having a hydrolyzable silyl group is used by utilizing chain transfer of the SH group of the polydimethylsiloxane. The block copolymer A is obtained by adding a monomer and, if desired, other copolymerizable vinyl monomer and polymerizing.

[Vinyl Monomer Having Hydrolyzable Silyl Group] Examples of the vinyl monomer having a hydrolyzable silyl group used in the present invention include γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropyl. A silane coupling agent such as triethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethoxyethoxysilane, vinyltrimethoxysilane, or vinyltriethoxysilane can be used. .

[Other Copolymerizable Vinyl Monomers] Examples of the other copolymerizable vinyl monomers used in the above-mentioned polymer initiator method and polymer chain transfer method include, for example, methyl acrylate and ethyl acrylate. , N-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, stearyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate , N-
Aliphatic or cyclic acrylates and / or methacrylates such as propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl Vinyl ethers such as vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, iso-butyl vinyl ether, styrenes such as styrene and α-methylstyrene,
Nitrile-based monomers such as acrylonitrile and methacrylonitrile, fatty acid vinyls such as vinyl acetate and vinyl propionate, halogen-containing monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene, propylene, isoprene Such as olefins, chloroprene, dienes such as butadiene, acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, crotonic acid,
Α, β-unsaturated carboxylic acids such as atropic acid and citraconic acid, acrylamide, methacrylamide, N, N-methylol acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, methyl acrylamide glycolate methyl ether and other amides, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminopropyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminopropyl Amino group-containing monomers such as acrylates, glycidyl acrylate, glycidyl methacrylate, epoxy group-containing monomers such as glycidyl allyl ether, 2-hydroxyethyl methacrylate, 2-hydroxy Ethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, allyl alcohol, Cardura E and acrylic acid, methacrylic acid,
Reaction products with itaconic acid, maleic acid, crotonic acid, etc., as well as vinylpyrrolidone, vinylpyridine, vinylcarbazole, etc. The above monomers are used alone or in combination of two or more. The above examples do not limit the invention.

[Method for Producing Polydimethylsiloxane Block Copolymer (A)] The polydimethylsiloxane block copolymer (A) according to the present invention has the above polydimethyl It is prepared by polymerizing the vinyl monomer having a hydrolyzable silyl group with a siloxane-introduced polymer initiator, if desired, by adding the other copolymerizable vinyl monomer to polymerize the polymer chain. In the transfer method, the above SH
A vinyl monomer having a hydrolyzable silyl group is polymerized by adding another copolymerizable vinyl monomer, if desired, by utilizing chain transfer of SH group of polydimethylsiloxane having a group. Manufactured. The above polymerization reaction is usually performed in a solution. In the solution polymerization, aromatic hydrocarbon solvents such as toluene and xylene, acetone, methyl ethyl ketone, ketone solvents such as methyl isobutyl ketone, ethyl acetate, propyl acetate, isobutyl acetate, ester solvents such as butyl acetate, methanol, It can be used alone or as a mixed solvent of alcoholic solvents such as ethanol, isopropanol, butanol and isobutanol. In the solution polymerization, for example, benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, dicumyl peroxide, t-butyl peroxyisopropyl carbonate, t-butyl perbenzoate, di-t-butyl peroxide, azobis Polymerization initiators such as isobutyronitrile and azobisvaleronitrile can be used in combination, but they need not always be used in the polymer initiator method. In the polydimethylsiloxane block copolymer (A) thus obtained, the siloxane content is 1 to 60% by weight, preferably 5 to 40% by weight, and the vinyl monomer having a hydrolyzable silyl group is contained. The ratio is 1 to 30% by weight, and the content ratio of the other copolymerizable vinyl monomer is 5 to 85% by weight, and it is preferable that the vinyl monomer having an OH group or an epoxy group is contained therein. Polydimethylsiloxane block copolymer (A) thus obtained
Has a high compatibility with other synthetic resins and is extremely effective as a compatibilizing agent, therefore, it is possible to mix and use a synthetic resin such as a silicone resin, polyvinyl acetoacetal or polyvinyl butyral.

[Crosslinking Agent (B)] The silane compound having a hydrolyzable group used as the crosslinking agent (B) of the polydimethylsiloxane block copolymer A will be described. The silane compound having a hydrolyzable group,
For example, alkoxysilane, chlorosilane, a silane coupling agent, or if the silane coupling agent is polymerizable, it is obtained by hydrolyzing the polymer thereof, and further hydrolyzing the hydrolyzable group of the silane coupling agent or the polymer. There are hydrolysates and the like. Examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetramethoxysilane such as trimethoxyneopentoxysilane, alkyltrialkoxy such as methyltrimethoxysilane, methyltriethoxysilane, and phenyltrimethoxysilane. Examples thereof include silane, dimethyldimethoxysilane, methylphenyldimethoxysilane, dialkyldialkoxysilane such as diphenyldimethoxysilane, and colloidal silica. Examples of the chlorosilane include trimethylchlorosilane, dimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, methyldichlorosilane, triphenylchlorosilane and phenylchlorosilane. As the silane coupling agent, aminomethyltriethoxysilane, N-β-aminoethylaminomethyltrimethoxysilane, N-β-aminoethylaminoethyltrimethoxysilane, N-β- (aminoethyl)
-Γ-aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane and other aminoalkylalkoxysilanes,
γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-
Epoxyalkylalkoxysilanes such as (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, etc. Mercaptoalkylalkoxysilane, γ-chloropropyltrimethoxysilane, halogenated alkylalkoxysilane such as 3,3,3-trichloropropyltrimethoxysilane, alkyltriacyloxysilane, alkenyltriacyloxysilane, aryltrialkoxysilane, trimethoxy Examples thereof include hydroxysilane compounds such as silane. Further, as a polymerizable silane coupling agent, used in the polydimethylsiloxane block copolymer (A). Vinyl monomers and the like having a hydrolyzable silyl group, polymer and the like of the silane coupling agents as further silane compounds used as the crosslinking agent (B). These silane compounds (B)
These may be used alone or in combination of two or more. Further, these silane compounds (B) may be in the state as they are, in the state of being hydrolyzed, or in the state of being partially condensed. For example, as the above-mentioned hydrolyzate,
What is obtained by adding water to a silane compound having a hydrolyzable group in an alcohol combination system in the presence of an acid or an alkali catalyst, wherein water equivalent to or more than the silane compound having a hydrolyzable group is added. When added, a completely hydrolyzed alcoholic silica gel or silica sol, or a siloxane-based composite is obtained, and when less than the equivalent amount of water is added, a partial hydrolyzate corresponding to the ratio is prepared.

[Curing catalyst (C)] Next, the curing catalyst (C) will be described. The polydimethylsiloxane block copolymer (A) is cured by one or more curing catalysts (C) selected from aluminum chelating agents, organotins, organic titanates, organic acids, and inorganic acids. The coating film performance is further improved. The following reaction forms are conceivable as the curing type. (1) -Si (OR) _n- >-Si (OH) _n (2) -Si (OH) _n + -Si (OR) _n- >-SiOSi- + nROH (3) -Si (OH) _n + -Si ( OH) _n → -SiOSi- + nH ₂ O In addition, the polydimethylsiloxane block copolymer A is O
In the case of having an H group, (4) -OH + -Si (OR) _n- >-Si (OR) _n-1-

The compounding ratio of the polydimethylsiloxane block copolymer A having a polydimethylsiloxane and a hydrolyzable silyl group and the cross-linking agent B is such that A: B is a solid content ratio of 100: 0 to 1:99. However, the range of 70:30 to 50:50 is preferable. Within this range, various performances are most effectively exhibited. The curing catalyst C has a solid content ratio of A + B: C of 100: 0.1-1.
The range is 00:10. When added in the above range, the curing catalyst C adversely affects the physical properties.

[Plastic Film] As the plastic film to which the above-mentioned curable composition is applied, for example, polyethylene terephthalate, polyethylene naphthalate, etc. are particularly useful as a base material for magnetic tapes and thermal transfer ink ribbons, and usually 1 to 0.05 μm. , Preferably 0.5-
About 0.1μ is applied. In addition, it is also useful for engineering plastic films such as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polyamide, polyimide, polycarbonate, polyacetal, and polyphenylene oxide. When used, it is usually 10 to 1 µ, preferably 5 to 2
About μ is applied.

[0014]

According to the present invention, since the polydimethylsiloxane component is incorporated in the skeleton of the block copolymer A, the surface condensing function sufficiently exerts the functions of water repellency, lubricity, and heat resistance on the surface. The tackiness of the surface peculiar to the composition to which polydimethylsiloxane oil is added, the decrease in transparency and the durability of the effect can be improved, and the copolymerization component improves the adhesion to the substrate. Further, by crosslinking, the weather resistance, heat resistance, solvent resistance, water repellency, and durability of lubricity are remarkably improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[Example 1] (Production of silane compound B-1) 80 parts by weight of ethanol (hereinafter simply referred to as "part") was placed in a 500 ml flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas introduction tube, and tetraethoxy was added while stirring. Dissolve 200 parts of silane, then 35% in 40 parts of deionized water
A solution in which 5 parts of hydrochloric acid was dissolved was slowly added dropwise, and the reaction temperature was kept constant at 80 ° C. for 5 hours with stirring to carry out hydrolysis reaction of tetraethoxysilane to obtain a hydrolyzed silane compound s.

Example 2 (Production of Silane Compound B-2) Using the same equipment as in Example 1, ethanol 80 parts, methyltrimethoxysilane 180 parts, and γ-glycidoxypropyltrimethoxysilane 20 parts were used. A silane compound t was obtained by the same operation except for the above.

Example 3 (Production of Silicone Block Copolymer A-1) With the same equipment as in Example 1, isopropyl alcohol 20 was used.
0 parts, 35 parts of methyl methacrylate, 15 parts of n-butyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate, 10 parts of γ-methacryloxypropyltrimethoxysilane, VPS-0501 (trade name: polydimethyl manufactured by Wako Pure Chemical Industries, Ltd. Siloxane polymer azo initiator
After charging 20 parts of a silicone chain length of 5000) and stirring until uniform, the temperature was raised to 80 ° C. and the polymerization was completed in 5 hours. Thus, a resin liquid having a solid content of 33.3% by weight (hereinafter simply referred to as%) was obtained. Then, the resin liquid 100
20 parts of the silane compound s of Example 1 was mixed with 10 parts to prepare a resin liquid a.

[Example 4] (Production of Silicone Block Copolymer A-2) VPS-0501 of Example 3 was prepared with the same equipment as in Example 1.
Is VPS-1001 (trade name, manufactured by Wako Pure Chemical Industries, Ltd.)
A resin liquid having a solid content of 33.3% was obtained by the same composition and operation as in Example 3, except that the polydimethylsiloxane polymer azo initiator silicone chain length was changed to 10000).
Subsequently, 20 parts of the silane compound of Example 1 was mixed with 100 parts of this resin solution to prepare a resin solution b, and Example 2 was used.
The resin solution c was prepared by mixing 20 parts of the silane compound t.

Example 5 (Production of Silicone Block Copolymer A-3) With the same equipment as in Example 1, 35 parts of methyl methacrylate of Example 3 and 15 parts of n-butyl methacrylate were replaced with 20 parts of methyl methacrylate, n-butyl methacrylate 10
Part and 3-methacryloxypropyltris (trimethylsiloxy) silane were changed to 20 parts to obtain a resin liquid having a solid content of 33.3% by the same composition and operation as in Example 3.
Subsequently, a resin d was prepared by mixing 20 parts of the silane compound of Example 2 with 100 parts of this resin liquid.

Example 6 (Production of Silicone Block Copolymer A-4) Using the same equipment as in Example 1, isopropyl alcohol 20 was used.
0 parts, 35 parts of methyl methacrylate, 15 parts of n-butyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate, 10 parts of γ-methacryloxypropyltrimethoxysilane, X22-167B (trade name of Shin-Etsu Chemical Co., Ltd .: thiols at both ends) 20 parts of polydimethylsiloxane having a group) and 1 part of azobisisobutyronitrile were charged, the temperature was raised to 80 ° C., and the polymerization was completed in 5 hours. Thus, a resin liquid having a solid content of 33.3% was obtained. Then, the silane compound s2 of Example 1 was added to 100 parts of this resin liquid.
0 parts were mixed to obtain a resin liquid e.

Comparative Example 1 Using the same equipment as in Example 1, 200 parts of isopropyl alcohol, 35 parts of methyl methacrylate, 15 parts of n-butyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate, γ-methacryloxypropyltrimethoxysilane. After charging 10 parts and 1 part of azobisisobutyronitrile, the temperature was raised to 80 ° C. and the polymerization was completed in 5 hours. Then, FM-4421 (trade name, manufactured by Chisso Corporation: polydimethylsiloxane having hydroxyl groups at both ends: 20 parts of a molecular weight of 5000) are mixed to obtain a solid content of 33.
A 3% resin solution was obtained. This was designated as resin liquid f.

Comparative Example 2 All the same composition and operation as Comparative Example 1 except that the FM-4421 of Comparative Example 1 was changed to SF8411 (trade name: Toray Silicone Co., Ltd .: side chain ether type epoxy modified polydimethylsiloxane). Thus, a resin liquid having a solid content of 33.3% was obtained. This was designated as resin liquid g.

The resin liquid a prepared in Examples 3 to 6 above,
b, c, d, e, and the resin liquids f produced in Comparative Examples 1 and 2,
g, solid content of 20 with isopropyl alcohol, respectively
%, And 2% of acetylacetone aluminum as a catalyst C was added to the solid content to prepare a coating solution. This coating solution was applied onto a PET film with Meyer bar # 3, dried at 60 ° C. for 8 hours, and then evaluated for physical properties. The results are shown in Table 1.

[0024]

[Table 1] Evaluation method Adhesion: Cross-cut cellophane tape peeling test Dynamic friction coefficient: HEIDON type friction tester Contact angle: Kyowa Interface Chemical contact meter Surface tackiness: ○ None × Yes Film transparency: visual judgment ○ Clear × cloudy Gel fraction : Films of various samples were subjected to ultrasonic waves in toluene for 30 minutes for extraction, and calculated from the weight difference before and after the extraction. Peeling force: Shimazu Seisakusho Autograph 25 cloth tape
It was measured at a speed of 300 mm / min with a width of 90 mm and a peel of 90 degrees. Weather resistance test: After 1000 hours of weatherometer, the contact angle and peeling force were measured in the same manner.

According to Table 1, in the samples 1 to 4 obtained by curing the block copolymer of the present invention, the orientation of silicone was as shown in the evaluations of adhesion, lubricity (dynamic friction coefficient) and contact angle. It is effectively expressed, and there is no problem in the film appearance. However, in Comparative Samples 1 and 2, the effect of silicone is seen to be constant, but the tackiness of the surface and the decrease in transparency of the film, which are observed when a large amount of silicone is added, are observed in the film appearance, and the effect is sustained. It is not enough in terms of sex.

[0026]

Therefore, in the present invention, the polydimethylsiloxane block copolymer A alone or the polydimethylsiloxane block copolymer A having the polydimethylsiloxane portion and the polymer portion having a hydrolyzable silyl group is present. A composition obtained by adding a silane compound B having a hydrolyzable group to a silicon atom as a cross-linking agent and further adding a specific curing catalyst C is a composition obtained by adding a conventional reactive silicone or a modified silicone oil. Compared with, the silicone's water repellency, lubricity, and heat resistance functions are fully exerted, and weather resistance, solvent resistance, surface tackiness, film transparency, water repellency and lubricity persistence, etc. Excellent curability composition and a plastic film useful as a base material for a magnetic tape or a thermal transfer ink ribbon coated with the curable composition Obtained.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hironori Hata 8-3 Ninomachi, Mizuho-ku, Nagoya, Aichi Natco Paint Co., Ltd.

Claims (7)

[Claims] 1. A curable composition comprising a polydimethylsiloxane block copolymer (A) having a polydimethylsiloxane portion and a vinyl polymer portion having a hydrolyzable silyl group. 2. The polydimethylsiloxane block copolymer (A) is produced by polymerizing a vinyl monomer having a hydrolyzable silyl group using a polymer azo catalyst having the following structure. The curable composition according to claim 1. 3. The polydimethylsiloxane block copolymer (A) comprises a vinyl monomer having a hydrolyzable silyl group and the hydrolyzable silyl group using a polymer azo catalyst having the following structure. The curable composition according to claim 1, wherein the curable composition is produced by copolymerizing the vinyl monomer contained therein with another copolymerizable vinyl monomer. 4. A mixture of the polydimethylsiloxane block copolymer (A) according to claim 1 and a crosslinking agent (B) and / or a curing catalyst (C), wherein the crosslinking agent (B) is an alkoxysilane, Chlorosilane, a silane coupling agent or its polymer, and one or more selected from hydrolysates obtained by hydrolyzing the hydrolyzable silyl group of the monomer or polymer of the silane coupling agent. The curing catalyst (C) is an aluminum chelating agent, organic tin, organic titanate, organic acid,
Curable composition characterized by being one or more compounds selected from inorganic acids 5. A plastic film comprising the curable composition according to claim 1, 2 or 3 applied to the front surface and / or the back surface. 6. The curable composition comprises a mixture of the polydimethylsiloxane block copolymer (A) according to claim 1 and a crosslinking agent (B) and / or a curing catalyst (C). B) is selected from alkoxysilane, chlorosilane, a silane coupling agent or a polymer thereof, and a hydrolyzate obtained by hydrolyzing a hydrolyzable silyl group of a monomer or polymer of the silane coupling agent. 6. The curing catalyst (C) is one or more compounds selected from aluminum chelating agents, organic tins, organic titanates, organic acids, and inorganic acids. Described plastic film 7. The plastic film is used as a base material for a magnetic tape or a thermal transfer ink ribbon.
Or the plastic film according to item 6.