JP2005112913A - Plastic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic sheet excellent in long-term durability, more specifically in gloss retention, crack resistance, yellowing resistance and water resistance. <P>SOLUTION: The plastic sheet is a plastic sheet the surface of the base material of which is coated with a coating containing an aqueous dispersion of a polymer obtained by multistage emulsion-polymerizing a radically polymerizable unsaturated monomer. The aqueous dispersion of the polymer is obtained by polymerizing a monomer the indispensable component of which is a hindered amine-based polymerizable ultraviolet stabilizer in the presence of a silane coupling agent having a cycloalkyl group at the final polymerization stage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plastic sheet that is excellent in weather resistance, chemical resistance, stain resistance, and decontamination property, and is used for various decorations, displays, and packaging.

  Currently colored products such as automobiles, motorcycles, motorboats, snowmobiles, home appliances, electronic devices, moldings and exterior boards, interior materials, building materials, various information boards, traffic signs, indoor / outdoor advertisements, signs, shutters, windows, etc. Various plastic sheets are used for decoration and display, and for imparting various surface functions such as weather resistance, antifouling properties, various resistances, and the like. In addition, various plastic sheets are used as packaging materials for preventing quality deterioration of various articles and protecting each function.

  For these plastic sheet materials, semi-rigid or soft vinyl chloride resin, polyethylene terephthalate resin, acrylic resin, urethane resin, polyethylene resin, polypropylene resin, polycarbonate resin, fluorine resin, and the like are used. However, these resin sheets alone are inferior in weather resistance, and when used outdoors, due to sunlight ultraviolet rays, rain, heat, etc., gloss degradation due to polymer degradation, sheet strength degradation, discoloration, and the like occur. In order to eliminate these drawbacks, a coating agent containing a known ultraviolet absorber, hindered amine radical scavenger and the like is applied to the surface of the plastic sheet. However, since UV absorbers and hindered amine radical scavengers have low molecular weight, they are volatilized, bleed out, and decomposed over long periods of time. A plastic sheet having good weather resistance over a period of time has not been obtained.

Therefore, an emulsion polymerization type resin obtained by copolymerizing a polymerizable hindered amine monomer has been proposed as a resin used for the coating agent for such a problem. In the emulsion polymerization type resin copolymerized with this hindered amine monomer, the hindered amine is bonded to the resin, so that it does not volatilize or bleed out from the formed coating film.
However, when a coating agent containing an emulsion polymerization resin copolymerized with a hindered amine monomer is used, a completely homogeneous coating is applied due to the poor compatibility between the hindered amine monomer and other monomers. Since a film is not obtained and microscopically phase-separated, fine cracks occur on the surface of the paint film after the weather resistance test, resulting in a reduction in the gloss of the paint film. The weather resistance cannot be satisfied.

In addition, when many monomers having a cycloalkyl group are copolymerized in order to improve the weather resistance, the volatility of the film forming aid is poor, causing blocking or forming cracks when forming the coating film. As a result, the gloss is lowered and a film having good weather resistance cannot be obtained.
Furthermore, today, the demand for weather resistance is becoming stricter, and the above emulsion polymerization type resin copolymerized with a hindered amine monomer cannot meet the demand.
Japanese Patent Laid-Open No. 3-128978 Japanese Patent Laid-Open No. 10-60023 Japanese Patent Laid-Open No. 10-60024 JP 2000-351886 A JP 2000-351908 A JP 2001-115080 A

  An object of the present invention is to provide a plastic sheet excellent in long-term weather resistance, specifically, gloss retention, crack resistance, yellowing resistance, water resistance and the like.

（式中、Ｒ₁は水素原子又はシアノ基を表し、Ｒ₂、Ｒ₃はそれぞれ独立して水素原子、メチル基又はエチル基を表し、Ｒ₄は水素原子、炭素数１〜１８のアルキル基、−ＣＯ−Ｃ（Ｒ₅）＝ＣＨ（ＣＲ₆）を表し、Ｘはイミノ基又は酸素原子を表す。Ｒ₅、Ｒ₆はそれぞれ独立して水素原子、メチル基又はエチル基を表す。） The plastic sheet of the present invention is a plastic sheet in which a coating agent containing an aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of radically polymerizable unsaturated monomers is applied to the surface of a plastic sheet substrate. In the final stage, the aqueous dispersion of the polymer polymerizes a monomer having the polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component in the presence of a silane coupling agent having a cycloalkyl group. It is characterized by the fact that it is a damaging thing.

(In the formula, R ₁ represents a hydrogen atom or a cyano group, R ₂ and R ₃ each independently represents a hydrogen atom, a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. , —CO—C (R ₅ ) ═CH (CR ₆ ), X represents an imino group or an oxygen atom, and R ₅ and R ₆ each independently represents a hydrogen atom, a methyl group or an ethyl group.

  The plastic sheet of the present invention has a coating agent containing an aqueous dispersion of a polymer in which a silane coupling agent having a hindered amine and a cycloalkyl group is localized in the outermost layer of emulsion particles in a multistage emulsion polymerization method. Since it is applied to the surface of the material, the coating film is homogeneous and excellent in long-term weather resistance, specifically, gloss retention, crack resistance, yellowing resistance, water resistance and the like.

  The plastic sheet of the present invention is one in which a coating agent containing an aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a radically polymerizable unsaturated monomer is applied to the surface of a plastic sheet substrate, An aqueous dispersion of a polymer is prepared by using a monomer having a polymerizable UV stabilizer represented by the general formula (1) as an essential component in the presence of a silane coupling agent having a cycloalkyl group. Polymerization is performed in stages.

（式中、Ｒ₁は水素原子又はシアノ基を表し、Ｒ₂、Ｒ₃はそれぞれ独立して水素原子、メチル基又はエチル基を表し、Ｒ₄は水素原子、炭素数１〜１８のアルキル基、−ＣＯ−Ｃ（Ｒ₅）＝ＣＨ（ＣＲ₆）を表し、Ｘはイミノ基又は酸素原子を表す。Ｒ₅、Ｒ₆はそれぞれ独立して水素原子、メチル基又はエチル基を表す。）

(In the formula, R ₁ represents a hydrogen atom or a cyano group, R ₂ and R ₃ each independently represents a hydrogen atom, a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. , —CO—C (R ₅ ) ═CH (CR ₆ ), X represents an imino group or an oxygen atom, and R ₅ and R ₆ each independently represents a hydrogen atom, a methyl group or an ethyl group.

By allowing the polymerizable ultraviolet stabilizer and the silane coupling agent having a cycloalkyl group to coexist in the outermost layer of the polymer particles, a coating film excellent in compatibility can be obtained, and the weather resistance of the plastic sheet, particularly in the long term The gloss retention can be further improved.
The multistage emulsion polymerization referred to in the present invention is a kind of emulsion polymerization and comprises two or more different polymerization stages. That is, it is a polymerization method that passes through a plurality of different polymerization stages such as monomers, emulsifiers, polymerization initiators to be used.

  Specific examples of the polymerizable ultraviolet stabilizer include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine. 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4 -(Meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6 -Tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl 4-cyano-4- (meth) acryloyl amino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like. These may use only 1 type and may mix and use 2 or more types suitably.

Among the polymerizable ultraviolet stabilizers exemplified above, in the general formula (1), R ₁ is a hydrogen atom, R ₂ is a methyl group, R ₃ is a hydrogen atom, and R ₄ is a hydrogen atom or A compound that is a methyl group and X is an oxygen atom is particularly preferred. Specific examples of such compounds include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6, and the like. Examples include 6-pentamethylpiperidine.

  The content of the polymerizable ultraviolet stabilizer is 100% by weight in total of the polymerizable ultraviolet stabilizer, a silane coupling agent having a cycloalkyl group described later, and a radical polymerizable unsaturated monomer described later (polymerization described later. 0.1% to 60.0% by weight in the case of using a polymerizable ultraviolet light absorber or a polymerizable monomer having an alkoxysilyl group in a total of 100% by weight including these. When the polymerizable ultraviolet stabilizer is less than 0.1% by weight, it is difficult to sufficiently exert the effect of improving weather resistance. On the other hand, if it exceeds 60% by weight, the polymerization reaction is difficult to proceed, a large amount of unreacted polymerizable UV stabilizer remains, and the polymerization stability is lowered during emulsion polymerization, and aggregates are generated. Absent. The radical polymerizable unsaturated monomer referred to in the present invention does not include a polymerizable ultraviolet stabilizer, a polymerizable ultraviolet absorber described later, or a polymerizable monomer having an alkoxysilyl group.

  Specific examples of the silane coupling agent having a cycloalkyl group include cyclohexyldimethylchlorosilane, cyclohexylethyldimethoxysilane, cyclohexylmethyldichlorosilane, cyclohexylmethyldimethoxysilane, (cyclohexylmethyl) trichlorosilane, cyclohexyltrichlorosilane, cyclohexyltrimethoxysilane, Examples include cyclooctyltrichlorosilane, cyclopentyltrichlorosilane, cyclopentyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. These may use only 1 type and may mix and use 2 or more types suitably.

Among the silane coupling agents having a cycloalkyl group exemplified above, a silane coupling agent having a cyclohexyl group and not having a cyclic ether structure, such as cyclohexylethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyltrimethoxysilane, It is preferable to use cyclopentyltrimethoxysilane or the like.
When a silane coupling agent having a cyclic ether structure such as 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane or 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane is used, The cyclic ether structure may simply open without reacting with -COOH in the coating film, and the hydroxyl group generated by the ring opening may deteriorate the water resistance of the coating film.

  The content of the silane coupling agent having a cycloalkyl group includes a silane coupling agent having a cycloalkyl group, a polymerizable UV stabilizer, a radically polymerizable unsaturated monomer described later, and a polymerizable that can be used as necessary. 0.1 to 10.0% by weight, preferably 0.2 to 5.0% by weight, in a total of 100% by weight of the ultraviolet absorbent and the polymerizable monomer having an alkoxysilyl group that can be used as required. It is good to be. When the content of the silane coupling agent having a cycloalkyl group is less than 0.1% by weight, the effect of improving weather resistance and compatibility is hardly exhibited, whereas when it exceeds 10.0% by weight, the water resistance of the coating film is increased. This is not preferable because the property tends to decrease.

Various types of emulsifiers can be used for multistage emulsion polymerization of radically polymerizable unsaturated monomers. From the viewpoint of improving the water resistance of the coating film, radicals having both radical polymerizability and functions as an emulsifier. It is preferable to use a reactive emulsifier having a polymerizable unsaturated double bond.
As the reactive emulsifier, an anionic or nonionic emulsifier having an unsaturated double bond capable of radical polymerization and having a non-nonylphenol structure is preferably used. Examples of such reactive emulsifiers include sulfosuccinic acid esters (for example, commercially available products such as LATEMUL S-120, S-180P, S-180A, Sanyo Chemical Co., Ltd., Eleminol JS-2, etc.) And alkyl ether-based products (for example, Aqualon KH-05, KH-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Adekaria Soap SR-10N, SR-20N, ER-10, 20, manufactured by Asahi Denka Kogyo Co., Ltd. 30 and 40).

  In emulsion polymerization, one or more of these can be mixed and used. The amount of the emulsifier used is a polymerizable UV stabilizer, a silane coupling agent having a cycloalkyl group, a radical polymerizable unsaturated monomer described later, a polymerizable UV absorber that can be used as required, and As described later, the amount is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total polymerizable monomers having an alkoxysilyl group that can be used as necessary. When the amount exceeds 10 parts by weight, the particle size of the polymer becomes small, but since a large amount of emulsifier is used, the water resistance of the coating film tends to deteriorate as an adverse effect. In the radical polymerizable unsaturated monomer referred to in the present invention, a reactive emulsifier is not included.

  In the final stage of the multistage emulsion polymerization, it is preferable to further copolymerize a polymerizable ultraviolet absorber represented by the general formula (2).

（式中、Ｒ₇は水素原子又はメチル基を表し、Ｙは炭素数１〜６のアルキレン基を表す）。

(Wherein R ₇ represents a hydrogen atom or a methyl group, and Y represents an alkylene group having 1 to 6 carbon atoms).

Specific examples of the polymerizable ultraviolet absorber include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl). ) Phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyhexyl) phenyl ] -2H-benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-t -Butyl-3 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy 5 ′-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-t-butyl -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, and the like. These may use only 1 type and may mix and use 2 or more types suitably.
Among the polymerizable ultraviolet absorbers, 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole is particularly preferable.

  The content of the polymerizable UV absorber is necessary as described below, the polymerizable UV absorber, the polymerizable UV stabilizer, the silane coupling agent having a cycloalkyl group, the radical polymerizable polymerizable unsaturated monomer described below, and Depending on the total amount of polymerizable monomers having alkoxysilyl groups that can be used, it is 0.1 to 10% by weight, preferably 0.2 to 5% by weight. If the content of the polymerizable ultraviolet absorber is less than 0.1% by weight, a synergistic effect of improving weather resistance is hardly exhibited. On the other hand, if it exceeds 10% by weight, the polymerization stability is poor, and generally, the polymerizable ultraviolet absorber is expensive and disadvantageous in terms of cost.

  In the multistage emulsion polymerization, a polymerizable monomer having an alkoxysilyl group can be used in order to improve the various physical properties by introducing a crosslinked structure into the coating film. In addition, when a polymerizable monomer having an alkoxysilyl group is used in the final stage of multi-stage emulsion polymerization, a silane coupling agent having a cycloalkyl group, a polymerizable UV stabilizer or a radical polymerizable unsaturated monomer. Increases compatibility with the body and the like, and a synergistic effect of improving weather resistance appears. Specific examples of the polymerizable monomer having an alkoxysilyl group include vinyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, allyltriethoxysilane, trimethoxysilylpropylallylamine, vinyltriethoxysilane, vinyltris. (Β-methoxyethoxy) silane, γ- (meth) acryloxypropyltriethoxysilane and the like can be mentioned. These may use only 1 type and may mix and use 2 or more types suitably.

  The content of the polymerizable monomer having an alkoxysilyl group includes a polymerizable monomer having an alkoxysilyl group, a polymerizable UV stabilizer, a silane coupling agent having a cycloalkyl group, and a radical polymerizable polymerizable monomer described later. It is 0.1 to 5% by weight, preferably 0.3 to 3% by weight, in a total of 100% by weight of the saturated monomer and the polymerizable ultraviolet absorber that can be used as necessary. When the content of the polymerizable monomer having an alkoxysilyl group is less than 0.1% by weight, a synergistic effect of improving weather resistance is hardly exhibited, whereas when it exceeds 5% by weight, the coating film tends to be brittle. This is not preferable because the physical properties easily change during storage. The radical polymerizable unsaturated monomer referred to in the present invention does not include a polymerizable monomer having an alkoxysilyl group.

  As radically polymerizable unsaturated monomers, it is possible to introduce a crosslinked structure into a coating film such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, diallyl phthalate, divinylbenzene, allyl methacrylate, glycidyl methacrylate, etc. Any polyfunctional polymerizable unsaturated monomer can be used.

  Specific examples of other radical polymerizable unsaturated monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, Acrylate esters such as isoamyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate, methyl methacrylate, propyl methacrylate, methacrylic acid n-butyl, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate, methacrylate Methacrylic acid esters such as dodecyl acid, styrene monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, chlorostyrene, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, methacryl Hydroxy group-containing monomers such as hydroxypropyl acid, N-substituted acryl such as N-methylol acrylamide, N-butoxymethyl acrylamide, N-methylol methacrylamide, N-butoxymethyl methacrylamide, methacrylic monomers, and acrylonitrile 1 type or 2 types or more can be selected and used.

As the radically polymerizable unsaturated monomer, polymerization properties such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid are used during polymerization or in order to maintain the storage stability of the aqueous dispersion of the polymer. It is preferred to use unsaturated carboxylic acids and their anhydrides.
For this purpose, the polymerizable unsaturated carboxylic acid is composed of a polymerizable UV stabilizer, a silane coupling agent having a cycloalkyl group, a radical polymerizable polymerizable unsaturated monomer, and a polymerizable that can be used as necessary. 0.05 to 5% by weight can be used in a total of 100% by weight of the polymerizable monomer having an alkoxysilyl group which can be used as required.
In the multistage emulsion polymerization, the polymerizable unsaturated carboxylic acid is preferably polymerized before the final stage polymerization. In such a case, before the polymerizable ultraviolet stabilizer is emulsion-polymerized in the final stage, -COOH derived from the polymerizable unsaturated carboxylic acid is neutralized with a neutralizing agent such as ammonia water, and the pH is adjusted to 4. It is preferable to adjust to 0 or more. If the pH is not adjusted, the polymerization stability tends to deteriorate.

  In the emulsion polymerization, inorganic peroxide initiators such as ammonium persulfate and sodium persulfate and water-soluble azo initiators can be used. In some cases, an oil-soluble initiator such as benzoyl peroxide or azobisisobutyronitrile may be used in combination. These initiators can be used alone, but may be used in a redox type in combination with a reducing agent such as Rongalite.

Further, during emulsion polymerization, transition metal ions such as copper ions such as cupric sulfate and cupric chloride, and iron ions such as ferric sulfate and ferric chloride are ^added to the polymerization system from 10 ⁻⁷ to 10 ^−. It can be added in the range of ⁵ mol / liter. These transition metal ions have a kind of catalytic function for smoothly starting the polymerization reaction.

  Further, mercaptans such as sodium acetate, sodium citrate, sodium bicarbonate as a buffering agent, polyvinyl alcohol as a protective colloid, water-soluble cellulose derivatives, etc., stearyl mercaptan, t-dodecyl mercaptan as chain transfer agents can be used. .

The aqueous dispersion of the polymer of the present invention obtained by multi-stage emulsion polymerization of a radically polymerizable unsaturated monomer by the above method can be used in various ways depending on the content of the polymerizable ultraviolet stabilizer.
That is, when the content of the polymerizable ultraviolet stabilizer is 0.1 to 10.0% by weight, the aqueous dispersion of the polymer of the present invention itself is used as a coating agent, and the coating film has excellent long-term weather resistance. Can be formed on the surface of the plastic sheet substrate.
Further, when the content of the polymerizable ultraviolet stabilizer is 10.0 to 60.0% by weight, the solid content of various aqueous resin dispersions such as acrylic resin, urethane resin, polyester resin, epoxy resin, alkyd resin, etc. By adding 0.5 to 5.0 parts by weight of the aqueous dispersion of the polymer of the present invention in 100 parts by weight, it can be used as a coating agent for improving long-term weather resistance.

  Coating agents containing an aqueous dispersion of the polymer of the present invention include pigments, dyes and other colorants and fillers, thixotropic modifiers such as fine powder silica, colloidal silica, alumina sol, polyvinyl pyrrolidone, polyvinyl alcohol, water-soluble Polyester resins, water-soluble or water-dispersible polyurethane resins, emulsifiers, antifoaming agents, leveling agents, slipping agents, tackifiers, preservatives, antifungal agents, organic solvents as film-forming aids, etc. as required You may mix | blend.

As the plastic sheet substrate, a known plastic sheet such as semi-rigid or soft vinyl chloride resin, polyethylene terephthalate resin, acrylic resin, urethane resin, polyethylene resin, polypropylene resin, polycarbonate resin, or fluororesin is used. In particular, in order to obtain a plastic sheet having excellent long-term weather resistance, a sheet of semi-rigid or soft vinyl chloride resin, urethane resin, or fluororesin is effective.
In addition, molded products and exterior panels for automobiles, motorcycles, motorboats, snowmobiles, home appliances, electronic devices, interior materials, building materials, various information boards, traffic signs, indoor / outdoor advertisements, signboards, shutters, windows, etc. In view of the above, a soft vinyl chloride resin sheet having excellent followability to a curved surface is most effective.
The surface of the plastic sheet substrate can be subjected to corona treatment and primer treatment for the purpose of improving the wettability and adhesion of the coating agent to the plastic sheet substrate. As the primer treatment agent, materials known as easy adhesion treatment agents, for example, urethane resins, polyester resins, acrylic resins, chlorinated olefin resins, vinyl chloride vinyl acetate copolymers and the like are used.

Application of the coating agent is a conventionally known method, for example, gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade coating method, roll coating method, knife coating method, curtain coating method, slot orifice method. , Spray coating, bar coating, and the like. The coating agent may be applied in several times or may be applied once. A plurality of different methods may be combined.
The coating film thickness of the coating agent is usually about 0.1 to 50 μm, but is not limited to this range, and may be applied so as to have a film thickness suitable for the application and required performance.

An adhesive can be applied to the back surface of the plastic sheet of the present invention, that is, the surface to which the coating agent is not applied, if necessary. At that time, a release liner may be deposited on the pressure-sensitive adhesive layer.
Examples of the adhesive include rubber adhesives mainly composed of general natural rubber, synthetic isoprene rubber, recycled rubber, styrene-butadiene rubber, polyisoprene rubber, styrene-isoprene-styrene rubber, and (meth) Acrylic pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive mainly composed of a polymer obtained by copolymerizing monomers such as acrylic acid, methacrylic acid, acrylamide, vinyl acetate, and styrene mainly composed of acrylic ester (C2 to C12) An adhesive having a suitable adhesive strength can be selected according to the use and the material of the adherend.

  Depending on the type of adhesive and the application suitability, the adhesive uses a conventionally known method such as a kiss coating method, a die coating method, a lip coating method, a comma coating method, a blade coating method, or a bar coating method. Then, it may be applied directly to the back surface of the plastic sheet substrate, or the adhesive once applied on the release liner may be laminated on the back surface of the plastic sheet substrate.

  The plastic sheet of the present invention includes molded articles and exterior boards, interior materials, building materials, various information boards, traffic signs, indoor / outdoor advertisements, signboards, shutters, windows for automobiles, motorcycles, motorboats, snowmobiles, home appliances, and electronic devices. For various decorations, coloring, display materials, etc., as well as as a sheet that provides various surface functions such as weather resistance, stain resistance, decontamination, various resistances, etc., and prevents deterioration of the quality of various articles Used as a packaging material to protect the function.

Hereinafter, the present invention will be described by way of examples. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.
[Example 1]
A reaction vessel equipped with a thermometer, a dropping funnel, a reflux condenser and replaced with nitrogen gas was charged with 240 parts of ion-exchanged water and 5% of the pre-emulsion for the first stage previously mixed as shown in Table 1. . After raising the internal temperature to 80 ° C., the remaining pre-emulsion for the first stage was added dropwise over 1 hour while maintaining the internal temperature at 80 ° C., and after reacting at that temperature for 0.5 hour, 25% aqueous ammonia was added. Was added to neutralize the resulting emulsion.
Next, the pre-emulsion for the second stage previously mixed as shown in Table 1 was added dropwise to the neutralized emulsion over 0.5 hours, and further reacted at 80 ° C. for 2 hours. After cooling, an aqueous dispersion having a solid content of 40.5%, a viscosity of 100 mPa · s, a pH of 5.3, and a particle size of 150 nm was obtained.
To 100 parts of the resulting aqueous dispersion, 7 parts of 2-butoxyethanol was added to prepare a coating agent.
The obtained coating agent is applied to a transparent soft vinyl chloride resin sheet and a white soft vinyl chloride resin sheet with a bar coater to a dry film thickness of 10 μm, and dried for 5 minutes in a hot air dryer at 100 ° C. to give a plastic sheet It was created.

アクアロンKH-10：第一工業製薬株式会社製反応性界面活性剤（有効成分９７％以上）

Aqualon KH-10: Reactive surfactant manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (active ingredient 97% or more)

[Examples 2 to 13]
A raw material having the composition shown in Table 2 was polymerized in the same manner as in Example 1, and using the resulting aqueous dispersion, a coating agent was prepared, applied and dried in the same manner as in Example 1 to produce a plastic sheet. did.

[Comparative Examples 1-8]
A raw material having the composition shown in Table 3 was polymerized in the same manner as in Example 1, and using the resulting aqueous dispersion, a coating agent was prepared, applied and dried in the same manner as in Example 1 to produce a plastic sheet. .
[Comparative Example 9]
A sample for comparison test was prepared by applying nothing to the soft vinyl chloride resin sheet used in Example 1.

[Example 14]
The raw materials having the composition shown in Table 2 were polymerized in the same manner as in Example 1, and 100 parts of the aqueous dispersion obtained in Comparative Example 1 and 7 parts of 2-butoxyethanol were added to 2 parts of the obtained aqueous dispersion. Add and mix to create a coating. The obtained coating agent was applied and dried in the same manner as in Example 1 to prepare a plastic sheet.

[Evaluation of plastic sheet]
The plastic sheet was evaluated for water whitening resistance and weather resistance by the following methods. The results are shown in Table 4.
<Water-whitening resistance>: The degree of whitening of the coating film was visually evaluated when a plastic sheet of a transparent soft vinyl chloride resin was left in warm water at 60 ° C. for 24 hours. In addition, evaluation was performed by 5-point evaluation.
5 points: not whitened at all.
1 point: Significant whitening is observed on the entire surface.

<Wrinkle resistance>: Adhesive is applied to the back of a plastic sheet of white soft vinyl chloride resin, bonded to a white painted plate, and subjected to a weather resistance test under the following conditions to evaluate gloss deterioration, cracks, choking, and yellowing. Went.
Testing machine: QUV / Spray weathering tester (Q-Panel Lab Products)
Lamp: UVB-313
Test cycle: Irradiation 65 ° C. 8 hours, Shower: 5 minutes, Condensation: 50 ° C. 3 hours 55 minutes Test time: 5000 hours

<Gloss>: The gloss of the coating film before and after the weather resistance test for 5000 hours was measured at an irradiation angle of 60 ° and a light receiving angle of 60 ° using a variable angle gloss meter made by Nippon Denshoku Co., Ltd. Asked.
<Crack>: The coating film after a 5000 hour weather resistance test was visually evaluated for the presence or absence of cracks.
○: No crack, Δ: Micro crack present, ×: Crack present <choking>: The state of choking was visually evaluated for the coating after the 5000 hour weather resistance test.
○: No abnormality, Δ: Slightly choking, X: Slightly choking <yellowing>: For the coating film before and after the 5000 hour weather resistance test, the hue was measured with a color difference meter CR-200 manufactured by Minolta Co., Ltd. (ΔE) was determined.

Claims (6)

A plastic sheet in which a coating agent containing an aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a radically polymerizable unsaturated monomer is applied to the surface of a plastic sheet substrate, the aqueous dispersion of the polymer In the presence of a silane coupling agent having a cycloalkyl group, the polymer is obtained by polymerizing a monomer having the polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component in the final stage. Features a plastic sheet.

(In the formula, R ₁ represents a hydrogen atom or a cyano group, R ₂ and R ₃ each independently represents a hydrogen atom, a methyl group or an ethyl group, and R ₄ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. , —CO—C (R ₅ ) ═CH (CR ₆ ), X represents an imino group or an oxygen atom, and R ₅ and R ₆ each independently represents a hydrogen atom, a methyl group or an ethyl group. The aqueous dispersion of the polymer is characterized by using a reactive emulsifier having an unsaturated double bond capable of radical polymerization in multistage emulsion polymerization of a radical polymerizable unsaturated monomer. The plastic sheet according to claim 1. When the aqueous dispersion of the polymer is polymerized in the final stage with a monomer having the polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component, the polymerizable ultraviolet absorption represented by the general formula (2) The plastic sheet according to claim 1 or 2, which is obtained by copolymerizing an agent.

(In the formula, R ₇ represents a hydrogen atom or a methyl group, and Y represents an alkylene group having 1 to 6 carbon atoms.) The plastic sheet according to any one of claims 1 to 3, wherein the silane coupling agent having a cycloalkyl group is a silane coupling agent having a cyclohexyl group and having no cyclic ether structure. The plastic sheet according to any one of claims 1 to 4, wherein an adhesive is applied to the back surface of the plastic sheet substrate. 6. The plastic sheet according to claim 1, wherein the plastic sheet substrate is a soft vinyl chloride resin sheet.