JP2007246799A - Resin composition for ultraviolet shielding aqueous coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inexpensive resin composition for ultraviolet shielding aqueous coating, which forms a coating film having excellent weather resistance, transparency, adhesivity to a substrate, processability and various resistances in a short time. <P>SOLUTION: The resin composition for ultraviolet shielding aqueous coating comprises an aqueous dispersion (A) of a polymer which is an aqueous dispersion of a polymer obtained by multistage emulsion polymerization of a polymerizable composition containing a radically polymerizable unsaturated monomer, in which a polymerizable composition composed of a polymerizable ultraviolet stabilizer having a specific structure as an essential component is polymerized in the presence of a cycloalkyl group-containing silane coupling agent at the final stage and a metal oxide (B) having a specific surface area by a nitrogen adsorption method (BET method) of 30-160 m<SP>2</SP>/g and forms a dried film having a haze of ≤1% at 2-5 μm film thickness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous coating resin composition having an ultraviolet blocking ability and excellent long-term weather resistance.

It is well known that coatings used outdoors degrade with exposure to ultraviolet light. Deterioration due to ultraviolet rays is caused by light having a wavelength of 250 to 400 nm, and it is desirable to prevent light in this range. Many materials used for packaging and the like are required to be transparent to transmit visible light having a wavelength of 400 nm or more.
In order to prevent the coating film from being deteriorated by ultraviolet rays, the coating film generally contains an ultraviolet absorber. Organic materials such as benzophenone, benzotriazole, and phenyl salicylate are known as materials that are added to paints and absorb ultraviolet rays.
However, since the organic ultraviolet absorber is an organic substance, the organic ultraviolet absorber is likely to be deteriorated, and the efficacy tends to decrease with time due to elution and decomposition from the coating film. These often cause yellowing.

In response to the above problems, fine particle titanium oxide, fine particle zinc oxide, fine particle cerium oxide and the like having an average particle size of 0.1 μm or less similarly have the property of selectively absorbing ultraviolet rays and are chemically stable, so It has been proposed to blend in paints instead of absorbents.
However, in order to form a coating film having excellent visible light permeability, a large amount of powders such as fine particle titanium oxide and fine particle zinc oxide cannot be added, so that the absorption of ultraviolet rays is not complete.
In addition, these materials have a refractive index of about 1.9 to 2.8, and have a large deviation from the refractive index of general film-forming materials, so that when used at a high concentration in order to obtain a high function. There is a problem that the transparency when formed into a coating film cannot be obtained.
Furthermore, fine particle titanium oxide, fine particle zinc oxide and the like have a problem in that radicals are generated by ultraviolet rays to degrade the organic resin that is a binder of the coating film, and as a result, the weather resistance of the coating film is deteriorated. Therefore, the organic resin itself is required to have high weather resistance.

By the way, although the visible light scattering intensity of the fine particles depends on the refractive index of the particles and the medium, generally, the particle size is maximized in the vicinity of ½ of the wavelength, and if the particle size becomes smaller than that, the Rayleigh As shown by the scattering formula, the scattering intensity decreases in proportion to the sixth power of the particle diameter. Therefore, for visible light (wavelength: 400 to 800 nm), the scattering intensity is maximized when the particle diameter is 200 to 400 nm, and the scattering intensity is lowered (transparent) as the particle diameter becomes smaller. That is, it is indispensable to highly disperse particles having a small primary particle diameter in order to ensure transparency.
However, when inorganic particles such as metal oxides are dispersed in a solvent or polymer, the surface tension of the inorganic particles is larger than the surface tension of the medium. The interfacial energy at the interface between the liquid and the medium also increases and the particles aggregate.
In addition, the use of inorganic particles having a small primary particle size means that the specific surface area of the particles is increased at the same time. As a result, the opportunity for contact between particles increases, the tendency to agglomerate increases, and a stable dispersion is obtained. It becomes more difficult to obtain.

Patent Document 1 discloses an ultraviolet absorbing paint containing zinc oxide powder having a specific surface area of 10 m ² / g or more and 60 m ² / g or less in a paint solid content of 30 to 80 wt%. Patent Document 1 describes “transparent” ultraviolet absorbing paint. However, the coating film formed from the ultraviolet absorbing paint disclosed in Patent Document 1 itself has a high haze value and is never excellent in transparency. Patent Document 1 discloses that a transparent coating film can be obtained by overcoating a coating material of only a transparent resin on a coating film that is not very excellent in transparency.

Patent Document 2 forms a coating film with a very excellent transparency having a haze value of about 0.5% using a transparent ultraviolet absorbing zinc oxide coating material in which zinc oxide having a primary particle size of 0.1 μm or less is monodispersed. It is described that it is possible.
However, the coating material described in Patent Document 2 is a mixture of zinc oxide and polyester resin mixed in a sand mill for 8 hours and then subjected to ultrasonic treatment and dispersed over a total of 45 hours. Since an ultrasonic disperser has a relatively weak dispersion force, it is estimated that a long time is required for dispersion as described above. Such long-time dispersion is inefficient and unsuitable for industrial production.
JP-A-1-217084 JP-A-2-169673

  An object of the present invention is an inexpensive UV-blocking water-based coating resin composition capable of forming a coating film excellent in long-term weather resistance and transparency, adhesion to a substrate, processability, and various resistances in a short time. Is to provide.

That is, the present invention is an aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a polymerizable composition containing a radically polymerizable unsaturated monomer, in the presence of a silane coupling agent having a cycloalkyl group. An aqueous dispersion (A) of a polymer obtained by polymerizing a polymerizable composition having a polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component in the final stage, and an ultraviolet absorbing ability and nitrogen UV shielding capable of forming a dry film having a specific surface area of 30 to 160 m ² / g by adsorption method (BET method) and having a haze of 1% or less at a film thickness of 2 to 5 μm The present invention relates to a water-based resin composition for coating.

(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 (R 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 present invention also provides the ultraviolet blocking water-based coating according to the above invention, wherein the aqueous dispersion (A) of the polymer is obtained by using a reactive emulsifier having an unsaturated double bond capable of radical polymerization. The present invention relates to a resin composition.

  Furthermore, the present invention provides a polymerizable ultraviolet absorber represented by the following general formula (2) when the polymerizable composition having the polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component is polymerized in the final stage. It is related with the resin composition for ultraviolet blocking water-system coating of any one of the said invention characterized by using together.

(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 present invention also relates to the ultraviolet blocking water-based coating resin composition according to any one of the above inventions, wherein a silane coupling agent having a cycloalkyl group having a cyclohexyl group and having no cyclic ether structure is used.

Furthermore, the present invention provides 70 to 95% by weight of a metal oxide (B) having ultraviolet absorbing ability and a specific surface area of 30 to 160 m ² / g by a nitrogen adsorption method (BET method) and a dispersion resin or dispersion. 30 to 5% by weight of the agent is kneaded with two rolls or kneaded with a dry pulverizer to obtain a preliminary dispersion,
An aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a polymerizable composition containing a radically polymerizable unsaturated monomer, in the presence of a silane coupling agent having a cycloalkyl group, represented by the general formula (1) 100 parts by weight of an aqueous dispersion (A) of a polymer obtained by polymerizing a polymerizable composition containing a polymerizable ultraviolet stabilizer represented by formula (1) as an essential component in the final stage,
The pre-dispersion is blended so that the metal oxide (B) is 30 to 200 parts by weight, and relates to a method for producing a resin composition for ultraviolet blocking water-based coating.

  According to the present invention, an inexpensive UV-blocking water-based coating resin composition capable of forming a coating film excellent in long-term weather resistance and transparency, adhesion to a substrate, processability, and various resistances in a short time is provided. I was able to do that.

The polymer aqueous dispersion (A) used in the present invention has a polymerizable composition comprising, as an essential component, a polymerizable UV stabilizer represented by the general formula (1) in the presence of a silane coupling agent having a cycloalkyl group. The product is polymerized at the final stage of the multistage emulsion polymerization. By making the polymerizable UV stabilizer and the silane coupling agent having a cycloalkyl group coexist in the outermost layer of the polymer particles, a homogeneous coating film having excellent compatibility can be obtained, and weather resistance, in particular, long-term 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.

(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 (R 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.

  Specific examples of the polymerizable ultraviolet stabilizer in the present invention 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- (meta Examples include acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like. It is done. These may use only 1 type and may mix and use 2 or more types suitably.

In the present invention, 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, R A compound in which ₄ is a hydrogen atom or a methyl group and X is an oxygen atom is particularly preferable. 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. In the case of using a polymerizable ultraviolet light absorber or a polymerizable monomer having an alkoxysilyl group, it is preferable that the amount is 0.1 to 60% by weight 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 the weather resistance. On the other hand, if it exceeds 60% by weight, the polymerization reaction is difficult to proceed and a large amount of unreacted monomer remains. Further, the polymerization stability is lowered during the emulsion polymerization, and aggregates are generated. The “radically polymerizable unsaturated monomer” in the present invention does not include a polymerizable UV stabilizer, a polymerizable UV absorber described later, or a polymerizable monomer having an alkoxysilyl group. To do.

  In the present invention, it is preferable to polymerize a polymerizable unsaturated carboxylic acid such as acrylic acid before the final stage polymerization, as will be described later. In such a case, before emulsion polymerization of the polymerizable ultraviolet stabilizer is carried out at the final stage, -COOH derived from the polymerizable unsaturated carboxylic acid is neutralized with a neutralizing agent such as aqueous ammonia, and the pH of the reaction solution is previously determined. Is preferably adjusted to 4.0 or more. If the pH is not adjusted, the polymerization stability tends to deteriorate.

Further, the aqueous dispersion (A) of the present invention can be used in various ways depending on the content of the polymerizable ultraviolet stabilizer used.
That is, when the content of the polymerizable ultraviolet stabilizer is 0.1 to 10% by weight in 100% by weight of the solid content of the aqueous dispersion (A), the aqueous dispersion of the polymer itself is used as a coating agent. A coating film having excellent long-term weather resistance can be obtained.
Further, when the content of the polymerizable ultraviolet stabilizer is 10 to 60% by weight, the solid content of the aqueous dispersion of various polymers such as acrylic, urethane, polyester, epoxy, and alkyd is 100 parts by weight, The aqueous dispersion of the present invention can be used as an additive for improving long-term weather resistance by post-adding 0.5 to 5 parts by weight of a solid content.

In obtaining the aqueous dispersion (A) of the present invention, it is important to use a silane coupling agent having a cycloalkyl group in the polymerization step.
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.

In the present invention, among the silane coupling agents having a cycloalkyl group exemplified above, particularly preferred compounds include cyclohexylethyldimethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexyl having a cyclohexyl group and having no cyclic ether structure. Examples include trimethoxysilane and cyclopentyltrimethoxysilane.
When a compound having a cyclic ether structure such as 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane or 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane is used, this cyclic ether structure is coated. When reacted with -COOH in the membrane, a hydroxyl group is formed. Alternatively, when this cyclic ether structure undergoes ring-opening polymerization alone without reacting with -COOH, a polyether structure is formed. The presence of these hydroxyl groups and polyether structures may deteriorate the water resistance of the coating film. Therefore, it is preferable to use a silane coupling agent having a cyclohexyl group and not having a cyclic ether structure.

  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. It is 0.1 to 10% by weight, preferably 0.2 to 5% by weight, in a total of 100% by weight of the polymerizable monomer having an alkoxysilyl group that can be used as necessary. Good. 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. On the other hand, when the content exceeds 10% by weight, the water resistance of the coating film is reduced. Since it tends to decrease, it is not preferable.

In the present invention, various emulsifiers can be used in the multistage emulsion polymerization, but from the viewpoint of improving the water resistance of the coating film, so-called reactive emulsifiers having both a radical polymerization property and a function as an emulsifier are used. Is preferred.
Examples of the reactive emulsifier preferably used in the present invention include an anionic or nonionic emulsifier having one or more unsaturated double bonds capable of radical polymerization in the molecule of the non-nonylphenol structure. For example, sulfosuccinic acid ester type (for example, Latemul S-120, S-180P, S-180A, Sanyo Kasei Co., Ltd. Eleminol JS-2, etc., manufactured by Kao Corporation) or alkyl ether type (for commercial products, for example) For example, there are Aqualon KH-05 and KH-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Adeka Soap SR-10N, SR-20N, ER-10, 20, 30, 40, etc. manufactured by Asahi Denka Kogyo Co., Ltd.).

  In emulsion polymerization, one or more of these can be mixed and used. These emulsifiers include 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 necessary as described later, and a later described. Thus, it is preferable that it is 0.1-10 weight part with respect to a total of 100 weight part of the polymerizable monomer which has the alkoxy silyl group which can be used as needed. When the amount exceeds 10 parts by weight, the particle size becomes small, but since a large amount of an emulsifier is used, the water resistance of the coating tends to deteriorate as an adverse effect. In the “radically polymerizable unsaturated monomer” referred to in the present invention, a reactive emulsifier is not included.

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

(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.)

Specific examples of the polymerizable ultraviolet absorber in the present invention 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 ′-(methacryloyloxy) Hexyl) 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- [ '-Hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-methoxy-2H-benzo Triazole, 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 these, 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole is particularly preferable.

  The content of the polymerizable UV absorber is required as described below, the polymerizable UV absorber, the polymerizable UV stabilizer, the silane coupling agent having a cycloalkyl group, the radical polymerizable unsaturated monomer described later, and the later described. The total amount of polymerizable monomers having an alkoxysilyl group that can be used is 100 to 10% by weight, preferably 0.2 to 5% by weight, based on 100% by weight. When the content of the polymerizable ultraviolet absorber is less than 0.1% by weight, the synergistic improvement effect of 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 present invention, a phase change between a silane coupling agent having a cycloalkyl group and a polymerizable ultraviolet stabilizer, a radically polymerizable unsaturated monomer, etc., by introducing a crosslinked structure into the coating film to improve various physical properties. A polymerizable monomer having an alkoxysilyl group can be used in the polymerization in order to increase the solubility and exhibit the synergistic effect of improving the weather resistance.
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 unsaturated 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 monomer and the polymerizable ultraviolet absorber that can be used as required. When the content of the polymerizable monomer having an alkoxysilyl group is less than 0.1% by weight, the synergistic improvement effect of weather resistance is hardly exhibited. On the other hand, when the content exceeds 5% by weight, the coating film tends to be brittle. , Because the physical properties easily change during storage. In the “radical polymerizable unsaturated monomer” in the present invention, a polymerizable monomer having an alkoxysilyl group is not included.

  As radically polymerizable unsaturated monomers used in the present invention, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, diallyl phthalate, divinylbenzene, allyl methacrylate, glycidyl methacrylate and the like are crosslinked to the coating film. Polyfunctional polymerizable unsaturated monomers capable of introducing a structure 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, Alkyl acrylates such as isoamyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate,
Methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-methacrylate Alkyl methacrylates such as octyl, decyl methacrylate and dodecyl methacrylate,
Styrene monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, chlorostyrene,
Hydroxy group-containing monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate,
Select from N-substituted acrylic or methacrylic monomers such as N-methylol acrylamide, N-butoxymethyl acrylamide, N-methylol methacrylamide, N-butoxymethyl methacrylamide and one or more of acrylonitrile. be able to.

  Furthermore, polymerizable unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid and their anhydrides are used in combination during polymerization or in order to maintain the storage stability of the aqueous resin dispersion. It is preferable. For this purpose, the polymerizable unsaturated carboxylic acid comprises a polymerizable UV stabilizer, a silane coupling agent having a cycloalkyl group, a radical polymerizable unsaturated monomer, and a polymerizable UV absorber that can be used as necessary. And 0.05 to 5 weight% can be used in 100 weight% of the total of the polymerizable monomer which has the alkoxy silyl group which can be used as needed.

  As an initiator used at the time of emulsion polymerization, an inorganic peroxide polymerization initiator such as ammonium persulfate or sodium persulfate or a water-soluble azo initiator is used. In some cases, oil-soluble initiators such as benzoyl peroxide and azobisisobutyronitrile can 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 at 10 ⁻⁷ to 10 ^−5. It can be added in the range of mol / liter. These transition metal ions have a kind of catalytic function for smoothly starting the polymerization reaction.

  Furthermore, sodium acetate, sodium citrate, sodium bicarbonate, etc. are used as buffering agents, polyvinyl alcohol, water-soluble cellulose derivatives, etc. are used as protective colloids, and mercaptans, such as stearyl mercaptan and t-dodecyl mercaptan, are used as chain transfer agents. it can.

The metal oxide (B) used in the present invention is not particularly limited as long as it is a metal oxide having ultraviolet absorbing ability, and examples thereof include titanium dioxide, zinc oxide, cerium oxide, and iron oxide. As the metal oxide (B), a metal oxide powder having a specific surface area of 30 to 160 m ² / g determined by a nitrogen adsorption method (BET method) is used. When the specific surface area is less than 30 m ² / g, light scattering by the metal oxide particles becomes remarkable, and it becomes difficult to obtain a transparent coating film.
These metal oxides (B) may be used singly or in combination of two or more. From the viewpoint of the obtained coating film becoming colorless and the high ultraviolet shielding ability, The use of titanium or zinc oxide is preferred. In addition, titanium dioxide and zinc oxide exhibit catalytic activity and cause deterioration (choking) of the organic coating film, so the surface of the particles is surface-treated with a metal oxide such as silica, alumina, zirconia or its hydrate, It is preferable to use one with reduced catalytic activity.

The metal oxide (B) used in the present invention may be previously hydrophobized with a coupling agent, organosilicone, higher fatty acid, phosphate ester, higher alcohol, or the like.
For example, the coupling agent may be any of silane, titanate, and aluminum chelate. Specifically, as the silane, methyltriethoxysilane, methyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxylane, tetraethoxy Silane, tetramethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, N (2-amino Ethyl) -3-aminopropylmethyldimethoxysilane, N (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrime Toxisilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxy Silane;
Titanium-based isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, bis (dioctyl) Pyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyldimethacrylisostearoyl titanate, isopropylisostearoyldiacryl titanate, isopropyltri (dioctylphosphate) titanate, isopropyltricumylphenyl titanate, Isopropyl (N- amidoethyl-aminoethyl) titanate, dicumyl phenyloxy acetate titanate, diisostearoyl ethylene titanate;
Examples of the aluminum chelate system include acetoalkoxyaluminum diisopropylate.

As a method for hydrophobizing the metal oxide (B) in the present invention, a conventionally known method can be used.
However, in the present invention, since it is an aqueous coating agent, it is not necessary to perform the hydrophobization treatment of the metal oxide (B).

In the coating resin composition of the present invention, it is preferable that a preliminary dispersion containing the metal oxide (B) is obtained in advance and the preliminary dispersion is mixed with the aqueous dispersion (A).
The preliminary dispersion containing the metal oxide powder (B) will be described. The preliminary dispersion is obtained by kneading 70 to 95% by weight of the metal oxide powder (B) and 30 to 5% by weight of the dispersion resin or dispersant with two rolls or kneading with a dry pulverizer. It is.
The aggregated metal oxide (B) particles are crushed by the strong shearing action of the two rolls or the powerful impact force of the grinding media, and at the same time, the dispersion resin or dispersant on the particle surface is strong. Since adsorption occurs, a fine dispersion having good dispersion stability can be obtained.
Further, a kneading process using a two-roll or dry pulverizer and a dispersing process using a wet media type disperser can be used in combination. When used together, the dispersion time is greatly shortened as compared with the case where the dispersion is performed for a long time alone, and contamination caused by wear of the vessel or the medium can be greatly reduced.

First, a method for obtaining a preliminary dispersion by kneading with two rolls will be described.
The kneading treatment with two rolls in the present invention is to adsorb the dispersion resin on the particle surfaces while crushing the aggregates of metal oxide particles using the shearing force of the two rolls.
70 to 95% by weight of the metal oxide (B) and 30 to 5% by weight of the dispersion resin or dispersant are mixed at room temperature or under heating to make a homogeneous mixture. In particular, in the case of an aqueous system, it is preferable to use a metal oxide whose surface is not hydrophobized.
When the metal oxide (B) is less than 70% by weight, the workability of the next kneading treatment step using two rolls is deteriorated. On the other hand, when it exceeds 90% by weight, the dispersion stability of the obtained preliminary dispersion is lowered.

  The mixture thus obtained is kneaded a plurality of times with two rolls at a heating temperature of 40 to 200 ° C. and a rotation speed of 10 to 50 rpm to obtain a fragment-like or sheet-like kneaded product. The number of kneading can be arbitrarily set according to the desired degree of kneading. When the obtained kneaded material is in the form of a sheet, it is preferably used in the subsequent dissolution and dispersion steps after being pulverized into powder or fragments. A method for pulverizing the sheet-like kneaded material is not particularly limited, and an ordinary pulverizer may be used.

Next, the kneading process of the metal oxide powder (B) and the dispersion resin or dispersant using a dry pulverizer will be described.
The kneading treatment by the dry pulverizer in the present invention has an ultraviolet absorbing ability and a metal oxide (B) having a specific surface area of 30 to 160 m ² / g by nitrogen adsorption method (BET method) and 70 to 95% by weight. The dispersion resin or the dispersant is added in an amount of 30 to 5% by weight, and the reaction is carried out at room temperature or under heating by using a pulverizer incorporating a pulverization medium such as beads. That is, the dispersion resin is adsorbed on the particle surface while pulverizing the aggregate of the metal oxide particles using the impact force of the pulverizing media. As the dry pulverizer, known methods such as a dry attritor, a ball mill, and a vibration mill can be used. If necessary, the inside of the dry pulverization apparatus may be subjected to a deoxidizing atmosphere by flowing nitrogen gas or the like to perform the kneading process.

By dispersing such a preliminary dispersion in the aqueous dispersion (A), the resin composition for ultraviolet blocking coating of the present invention can be obtained.
In order to disperse the preliminary dispersion in the aqueous dispersion (A), these can be dispersed using a high-speed stirrer such as a dissolver and then further dispersed with various dispersers to obtain a uniform and fine dispersion. Is preferable.

As the disperser used here, a disperser usually used for pigment dispersion can be used.
Although a specific example is given below, it is not limited to them.
For example, paint conditioner (manufactured by Red Devil), ball mill, sand mill (such as “Dynomill” manufactured by Shinmaru Enterprises), attritor, pearl mill (such as “DCP mill” manufactured by Eirich), coball mill, homomixer, homogenizer (M -"Clairemix" manufactured by Technic Co., Ltd.), wet jet mill (such as "Genus PY" manufactured by Genus, "Nanomizer" manufactured by Nanomizer, etc.) can be used. In view of cost, processing capability, etc., it is preferable to use a media type dispersing machine. As the media, glass beads, zirconia beads, alumina beads, magnetic beads, stainless beads, etc. can be used.

  When considering the transparency of the coating film to visible light (wavelength: 400 to 800 nm), the resin composition for ultraviolet blocking coating of the present invention generally has a dispersed particle diameter of the filler of 1/2 of the wavelength (200 to 400 nm). Hereinafter, it is more preferable that the thickness is 100 nm or less. That is, it is suitable for ensuring transparency that the filler with a fine primary particle size is highly dispersed.

The resin composition for ultraviolet blocking coating of the present invention can form a coating film excellent in long-term weather resistance, and can be used as various coating agents.
Specific applications of the coating agent include paints and inks that can be used on various substrates such as paper, film, metal, glass, wood, and leather.
Coating agents include pigments, dyes and other colorants and fillers, thixotropic modifiers such as finely divided silica, colloidal silica, alumina sol, polyvinyl pyrrolidone, polyvinyl alcohol, water-soluble polyester resins, water-soluble or water-dispersible polyurethane resins. An emulsifier, an antifoaming agent, a leveling agent, a slipping agent, a tackifier, an antiseptic, an antifungal agent, an organic solvent as a film-forming aid, and the like may be blended as necessary.

  The following examples illustrate the invention. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.

[Production Example 1]
A reaction vessel equipped with a thermometer, a dropping funnel, and a reflux condenser and replaced with nitrogen gas was charged with 240 parts of ion exchange water and 5% of the pre-emulsion for the first stage prepared in advance shown in Table 1. It is. After the internal temperature was raised to 80 ° C., dropping was started. While maintaining the internal temperature at 80 ° C., the remainder of the pre-emulsion for the first stage is added dropwise over 1 hour, and after reacting at that temperature for 0.5 hour, 2 parts of 25% ammonia water is added to neutralize the resulting emulsion. did.
Next, the pre-emulsion for the second stage prepared in advance shown in Table 1 was dropped into the emulsion after neutralization over 0.5 hour, 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 diameter of 150 nm was obtained.

[Production Examples 2 to 4]
Based on the composition shown in Table 1, polymerization was carried out in the same manner as in Production Example 1 to obtain respective aqueous dispersions.

[Production Examples 5 to 12]
Based on the composition shown in Table 2, polymerization was carried out in the same manner as in Production Example 1 to obtain respective aqueous dispersions.

[Examples 1 to 4 and Comparative Examples 1 to 8]
Using the aqueous dispersions of Production Examples 1 to 12, coating agents were produced by the following method.
120 parts of NANOFINE 50A (silica-alumina treated zinc oxide, BET specific surface area 50 m ² / g, manufactured by Sakai Chemical Co., Ltd.), 10 parts of Demol EP (dispersant manufactured by Kao Corporation), 10 parts of ethylene glycol and 15 parts of water at room temperature To obtain a homogeneous wet mixture. This wet mixture was repeatedly kneaded with two rolls heated to 80 ° C., and a solid preliminary dispersion A was obtained after 6 hours.
Subsequently, 100 parts of each aqueous dispersion shown in Table 3, 1 part of Primal ASE-60 (thickener made by Nippon Acrylic Co., Ltd.), CS-12 (film forming aid made by Chisso Corporation) 8 Part, SN deformer-364 (San Nopco Co., Ltd. antifoaming agent) 0.5 part, ammonia water 0.2 part, water 7 part was added to the above-mentioned pre-dispersion A and dispersed using a high-speed disper. Later, it was charged into a glass bottle and dispersed with a paint shaker for 2 hours using zirconia beads as a medium to obtain a coating agent.
The obtained coating agent was applied to an aluminum sheet having a thickness of 0.5 mm using a bar coater so that the thickness after drying was 3 μm, and was cured by heating in an electric oven at 150 ° C. for 10 minutes. Got.

[Comparative Example 9]
After wet dispersion treatment of NANOFINE 50A with a sand mill instead of two rolls to obtain a preliminary dispersion A ′, the aqueous dispersion and the preliminary dispersion A ′ were then dispersed using a high-speed disper in the same manner as in Example 1, A coated material was obtained in the same manner as in Example 1 except that the treatment was performed using an ultrasonic treatment machine instead of a paint shaker.

[Haze]
The coating agent obtained in each Example and Comparative Example was applied to a PET film having a thickness of 32 μm using a bar coater so that the thickness after drying was 3 μm, and was cured by heating in an electric oven at 150 ° C. for 10 minutes. A coated product was obtained.
The haze of the obtained coating was measured with “HAZEMETER HM-150” (Murakami Color Research Laboratory).

[Bleed-out property]
Polymerizable UV stabilizer or polymerizable UV absorption before the test of the coating material obtained from the above and using the aluminum sheet as a base material and after the test that was allowed to stand at 65 ° C.-90% RH for 5000 hours. The agent was observed to bleed out.
〇 ・ ・ ・ ・ ・ Without bleed out × ・ ・ ・ ・ ・ With bleed out

[Accelerated weather resistance test]
The test conditions are as follows.
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 An exposure test was performed using the aluminum sheet-based coating material obtained above. The color difference from the unexposed test piece (blank) was measured.

The results are shown in Table 3.

The resin composition for ultraviolet blocking water-based coating of the present invention includes: automotive windshield, rear glass, door glass, fender mirror, door mirror and glass for transportation equipment such as railways, airplanes, high-rise building window glass, general window Glass, glass bottles for enzyme storage, ampoule bottles, reagent storage bottles, other commonly used glass bottles, glass products such as mirrors, and other medical fields, food, industry, agriculture and other industrial fields and general households Plastic products, various film products, metal products, concrete, ceramic products, cloth, leather products, etc. that require water repellency, oil repellency, antifouling properties, weather resistance, etc., for example, water repellant glass Non-adhesive glass bottles, anti-fogging mirrors, enzymes, reagents, etc., antibacterial, anti-fouling plastic, inkjet printer head, snow accretion, anti-icing Coated plates can be used in the kitchen for antifouling aluminum sheet, printing plate material, such as waterless offset plate, discard plate for paint used in offset printing, and other printing-related products and the like.

Claims (5)

An aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a polymerizable composition containing a radically polymerizable unsaturated monomer, in the presence of a silane coupling agent having a cycloalkyl group, represented by the general formula (1) An aqueous dispersion (A) of a polymer obtained by polymerizing a polymerizable composition having the polymerizable ultraviolet stabilizer shown in the above as an essential component at the final stage, and a nitrogen absorption method (BET method) having ultraviolet absorbing ability Containing a metal oxide (B) having a specific surface area of 30 to 160 m ² / g, and capable of forming a dry film having a haze of 1% or less at a film thickness of 2 to 5 μm. object.

(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 (R 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 resin composition for ultraviolet blocking water-based coating according to claim 1, wherein the aqueous dispersion (A) of the polymer is obtained by using a reactive emulsifier having an unsaturated double bond capable of radical polymerization. When the polymerizable composition having the polymerizable ultraviolet stabilizer represented by the general formula (1) as an essential component is polymerized in the final stage, the polymerizable ultraviolet absorber represented by the following general formula (2) is used in combination. The resin composition for ultraviolet blocking water-based coating according to claim 1 or 2.

(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.) 4. The ultraviolet blocking water-based coating resin composition according to claim 1, wherein the cycloalkyl group is a cyclohexyl group and a silane coupling agent having no cyclic ether structure is used. 70 to 95% by weight of a metal oxide (B) having ultraviolet absorbing ability and a specific surface area of 30 to 160 m ² / g by nitrogen adsorption method (BET method), and 30 to 5% by weight of a dispersion resin or dispersant Kneaded with two rolls or kneaded with a dry pulverizer to obtain a preliminary dispersion,
An aqueous dispersion of a polymer obtained by multi-stage emulsion polymerization of a polymerizable composition containing a radically polymerizable unsaturated monomer, in the presence of a silane coupling agent having a cycloalkyl group, represented by the general formula (1) 100 parts by weight of an aqueous dispersion (A) of a polymer obtained by polymerizing a polymerizable composition containing a polymerizable ultraviolet stabilizer represented by formula (1) as an essential component in the final stage,
The pre-dispersion is blended such that the metal oxide (B) is 30 to 200 parts by weight.