JP2007070578A - Active energy ray-curable coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a crosslinked hardened coating film having excellent weatherability, wear resistance and adhesiveness to a substrate material. <P>SOLUTION: The active energy ray-curable coating composition comprises (A) at least either one of an acrylic monomer and an acrylic oligomer, (B) a photopolymerization initiator, (C) a hindered amine light stabilizer, and (D) an ultraviolet absorber having a structure represented by general formula (1), wherein R represents a linear or a branched ≤17C alkyl group and Ar represents a substituted or unsubstituted monocyclic or polycyclic aryl group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a crosslinked cured film having excellent wear resistance and weather resistance, and excellent surface smoothness, heat resistance, chemical resistance, durability and adhesion to the substrate by irradiation with active energy rays. The present invention relates to a coating composition that can be formed on a surface.

  Synthetic resin molded products produced from polymethyl methacrylate resin, polymethacrylimide resin, polycarbonate resin, polystyrene resin, AS resin, etc. are not only lightweight and excellent in impact resistance, but also have good transparency. As a plastic material for automobiles, it is widely used in various lamp lenses, glazing, instrument covers and the like. In particular, the use of plastic materials for headlamp lenses is increasing due to weight reduction and design diversification to improve automobile fuel efficiency. On the other hand, these synthetic resin molded products have insufficient surface wear resistance, and are easily damaged by contact with other hard objects, friction, and scratches. In addition, when used as an automobile material, the weather resistance is also an important performance. Particularly in the case of polycarbonate resin or the like, the weather resistance is poor, and it is deteriorated by active energy rays such as ultraviolet rays contained in sunlight, and the molded product is markedly yellowed or cracked on the surface.

  Various methods have been studied for improving the drawbacks of such synthetic resin molded products. For example, a coating material made of a silicon-based or melamine-based resin composition is applied to the surface of a synthetic resin molded product and heated. Proposed methods include condensation to form a crosslinked coating to improve wear resistance, and a method of forming a crosslinked coating by irradiating active energy rays after applying a resin composition comprising a radical polymerizable monomer. (Patent Document 1: Japanese Patent Laid-Open No. 56-122840).

  Among these techniques, the present inventors have previously developed a resin composition excellent in wear resistance, weather resistance, durability and chemical resistance with respect to a resin composition comprising a radical polymerizable monomer, Poly (meth) acrylates of mono- or polypentaerythritol, urethane poly (meth) acrylate compounds having at least two radically polymerizable unsaturated double bonds in the molecule, and poly We have proposed a resin composition obtained by blending substances such as [(meth) acryloyloxyalkyl] (iso) cyanurate at a specific ratio. This resin composition has both excellent wear resistance and weather resistance. (Patent Document 2: Japanese Patent Application Laid-Open No. 05-23097, Patent Document 3: Japanese Patent Application Laid-Open No. 06-128502, Patent Document 4: Japanese Patent Application Laid-Open No. 05) 179,157 JP).

  In these inventions, high weather resistance is obtained by using an ultraviolet absorber such as a benzotriazole compound. However, in order to use it for a long time in a harsh environment such as a high humidity environment, further improvement in weather resistance is required.

JP 56-122840 A Japanese Patent Laid-Open No. 05-230397 Japanese Patent Laid-Open No. 06-128502 JP 05-179157 A

  The present invention has been made in the background described above, and the object of the present invention is to provide a coating composition having excellent weather resistance, and capable of forming a crosslinked cured film excellent in wear resistance and substrate adhesion. Is to provide.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have excellent weather resistance, wear resistance, and substrate adhesion by using an ultraviolet absorbent having a structure represented by the following general formula (1). It was found that a coating composition capable of forming a crosslinked cured film was obtained.

In a first aspect, the present invention provides:
(A) at least one of an acrylic monomer and an acrylic oligomer;
(B) a photopolymerization initiator,
(C) a hindered amine light stabilizer,
(D) An active energy ray-curable coating composition containing an ultraviolet absorber having a structure represented by the following general formula (1).

(In the formula, R is a linear or branched alkyl group having 17 or less carbon atoms, and Ar is a substituted or unsubstituted monocyclic or polycyclic aryl group.)

In the second aspect of the present invention,
It is an active energy ray-curable coating composition in which the ultraviolet absorbent (D) represented by the general formula (1) of the coating composition is 1 to 10% by mass in the solid content of the coating.

In the third aspect of the present invention,
10 to 70% by mass of at least one monomer selected from (A)-(a) poly (meth) acrylates of mono- or polypentaerythritol represented by the following general formula (2):

(In the formula, at least three of X ^1,1 , X ^1,2 , X ^1,3 , X ^{n + 1,2} , X ^{n + 1,3} and X ^1,4 are CH ₂ ═CR—COO— A group (R represents hydrogen or a methyl group), and the remainder is an —OH group, and n is an integer of 0 to 4).
(A)-(b) 5-50% by mass of at least one urethane poly (meth) acrylate compound having at least two radically polymerizable unsaturated double bonds in one molecule;
(A)-(c) Poly [(meth) acryloyloxyalkyl] (iso) cyanurate represented by the formula (3), (4) or (5), 5 to 70% by mass,

(In the formula, X ¹ , X ² and X ³ represent an acryloyl group, a methacryloyl group, a hydrogen atom or an alkyl group, and at least two of these are an acryloyl group and / or a methacryloyl group, and R ¹ , R ² And R ³ represents an oxyalkylene group or a polyoxyalkylene group.
(B) 0.1-10% by mass of a photopolymerization initiator,
(C) An active energy ray-curable coating composition that is 0.1 to 5% by mass of a hindered amine light stabilizer.

In the fourth aspect of the present invention,
The A component is
(A)-(d) (meth) acryloyloxy group-containing colloidal silica 5 to 70% by mass,
20 to 80% by mass of a polyfunctional monomer other than (A)-(d),
(B) An active energy ray-curable coating composition having a photopolymerization initiator of 0.1 to 10% by mass and (C) a hindered amine light stabilizer of 0.1 to 5% by mass.

  By applying this coating composition to the surface of a synthetic resin molded article and irradiating active energy rays, it has excellent abrasion resistance and weather resistance having a crosslinked cured film, and has heat resistance, chemical resistance, durability, A synthetic resin molded product having excellent material adhesion can be obtained.

  The present invention will be described in detail. First, each component of the coating composition of the present invention will be described.

<About (A) component>
The component (A) is composed of at least one of an acrylic monomer and an acrylic oligomer, and is selected from a monofunctional or polyfunctional monomer or oligomer having a (meth) acryloyloxy group. These are produced by a well-known method, and are described in, for example, “UV / EB Curing Handbook—Raw Materials” published by Polymer Publishing Co., Ltd.

  Specifically, for example, ethyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 1,4-butanediol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, bis (2-acryloyloxyethyl) isocyanurate, tris (2-acryloyloxyethyl) isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (me ) Acrylic monomers such as acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, oligomers in which these acrylic monomers are multimerized, or polyhydric alcohols and polyfunctional isocyanates and hydroxyl groups Urethane (meth) acrylates synthesized by addition reaction with containing (meth) acrylate compounds, Polyester (meth) acrylates synthesized by condensation reaction of polyhydric alcohol with (meth) acrylic acid and polyfunctional carboxylic acid And epoxy (meth) acrylates synthesized by addition reaction of bisphenol type epoxy resin or novolac type epoxy resin and (meth) acrylic acid. Moreover, you may use the radically polymerizable group containing inorganic fine particle synthesize | combined by processing inorganic fine particles, such as corosidal silica, with the silane coupling agent containing a (meth) acryloyl group. These are used in one or a mixture of two or more.

  As a specific mixed system, the above-described third and fourth aspects of the present invention are preferable.

<About (A)-(a) component>
The poly (meth) acrylate of mono- or polypentaerythritol represented by the general formula (2) which is the component (A)-(a) exhibits a good polymerization activity upon irradiation with active energy rays, and has a high crosslinking density. A polymer having excellent wear resistance is formed. Therefore, a cured film having excellent wear resistance can be formed on the substrate surface.

  Specific examples of the component (A)-(a) include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipenta Erythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra (meth) acrylate, tripentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) An acrylate, tripentaerythritol octa (meth) acrylate, etc. are mentioned.

  The use ratio of the component (A)-(a) is preferably in the range of 10 to 70% by mass in 100% by mass of the total amount of the components (A) to (D). The lower limit is more preferably 20% by mass or more, and the upper limit is more preferably 50% by mass or less. When the amount of the component (A)-(a) is 10% by mass or more, the wear resistance of the cured coating is improved. Moreover, in the case of 70 mass% or less, the weather resistance and heat resistance of a cured film become good.

<About (A)-(b) component>
The urethane poly (meth) acrylate compound having at least two radically polymerizable unsaturated double bonds in one molecule, which is the component (A)-(b), is toughness, flexibility and heat resistance of the cured film. And a component for improving weather resistance, a urethanization reaction product of a hydroxyl group-containing (meth) acrylate and an isocyanate compound having two or more isocyanate groups in the molecule, and two or more in the molecule Examples include urethanation reaction products in which an isocyanate having an isocyanate group is reacted with a polyol, polyester or polyamide-based diol to synthesize an adduct, and then a hydroxyl group-containing (meth) acrylate is added to the remaining isocyanate group. It is done. The latter urethane poly (meth) acrylate is preferred because it can further improve the toughness and flexibility of the cured film. Moreover, those having a molecular weight of 1000 to 5000 are more preferable in terms of improving the adhesion of the cured film to the substrate.

  Specific examples of the isocyanate compound having two or more isocyanate groups in the molecule include tolylene diisocyanate, ethylene diisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, 4,4′-diphenylmethane. Diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, hexamethylene diisocyanate, lysine isocyanate, 4,4′-methylenebis (cyclohexyl) isocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, And polyisocyanate monomers such as imacic acid diisocyanate and 2-isocyanatoethyl-2,6-diisocyanatohexanoate, burettes and trimers thereof, and adducts of these with various polyols. it can.

  The polyol used for the synthesis of the adduct is not particularly limited, and specific examples thereof include alkyl polyols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, sorbitol, mannitol, and glycerin. , Polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol and the like.

  Specific examples of (meth) acrylates containing hydroxyl groups include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. In addition to addition reaction products of monoepoxy compounds such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl methacrylate and (meth) acrylic acid, polyethylene glycol, mono (meth) acrylic acid ester of polypropylene glycol, polycaprolactone Examples thereof include mono (meth) acrylic acid esters of diol.

  The reaction between an isocyanate compound having two or more isocyanate groups in the molecule, various polyols, and a (meth) acrylate containing a hydroxyl group is carried out in the presence of a tin-based catalyst such as n-butyltin dilaurate and the like. Are heated at 60 to 70 ° C. for several hours. Since the reaction product generally has a high viscosity in general, it is preferably diluted with an organic solvent or other dilution monomer during the reaction or after the completion of the reaction.

  The use ratio of the components (A) to (b) is preferably in the range of 5 to 50% by mass in 100% by mass of the total amount of the components (A) to (D). The lower limit is more preferably 10% by mass or more, and the upper limit is more preferably 30% by mass or less. When the amount of the component (A)-(b) is 5% by mass or more, the weather resistance of the cured film and the curability in an air atmosphere are improved. Moreover, when it is 50 mass% or less, the abrasion resistance of a cured film becomes good.

<About (A)-(c) component>
The poly ((meth) acryloyloxyalkyl] (iso) cyanurate represented by the general formula (3), (4) or (5), which is the component (A)-(c), is good when irradiated with active energy rays. It is a component that exhibits polymerization activity and can improve the toughness and heat resistance of the cured coating without impairing high wear resistance.

  Specific examples of the component (A)-(c) include bis (2-acryloyloxyethyl) hydroxylethyl isocyanurate, tris (2-acryloyloxyethyl) isocyanurate, bis (2-acryloyloxypropyl) hydroxylethyl isocyanurate. , Tris (2-acryloyloxypropyl) isocyanurate, bis (2-acryloyloxyethyl) hydroxylethyl cyanurate, tris (2-acryloyloxyethyl) cyanurate, bis (2-acryloyloxypropyl) hydroxylethyl cyanurate, tris ( 2-acryloyloxypropyl) cyanurate, tris [(2-acryloyloxyethyl) carbonylamidohexyl] isocyanurate, and the like.

  The proportion of the component (A)-(c) used is preferably in the range of 5 to 70% by mass in 100% by mass of the total amount of the components (A) to (D). The lower limit is more preferably 20% by mass or more, and more preferably 60% by mass or less. When the amount of the component (A)-(c) is 5% by mass or more, the wear resistance and heat resistance of the cured coating are improved. Moreover, in the case of 70 mass% or less, sclerosis | hardenability becomes good.

<About (A)-(d) component>
The (meth) acryloyloxy group-containing colloidal silica which is the component (A)-(d) is a colloidal silica particle composed of silica particles having a primary particle size of 1 to 200 nm, a silane compound represented by the following formula (6), or It can be synthesized by chemically modifying with the hydrolyzate.

Wherein R ⁴ is a single bond or a substituted or unsubstituted divalent hydrocarbon group, R ⁵ is a monovalent hydrocarbon group or hydrogen atom, R ⁶ is a substituted or unsubstituted monovalent hydrocarbon group, R ⁷ represents a hydrogen atom or a methyl group, a is an integer of 1 to 3, b is an integer of 0 to 2, a + b is an integer of 1 to 3)

In the formula (6), the substituted or unsubstituted divalent hydrocarbon group represented by R ⁴ is a linear, branched or cyclic alkylene group having 1 to 17 carbon atoms, an arylene group having 6 to 12 carbon atoms, or these. The combination is mentioned. Examples of the monovalent hydrocarbon group for R ⁵ and R ⁶ include a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms and an aryl group having 6 carbon atoms. Moreover, as a substituent, a hydroxyl group and a C1-C6 linear or branched alkoxy group are mentioned.

  Specific examples of the silane compound represented by the formula (6) include 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane, and commercially available products are available.

  The components (A) to (d) remarkably improve the wear resistance and surface hardness of the cured film, and exhibit an excellent effect particularly in a wear resistance test using abrasive grains as an abrasive.

  (A)-(d) The usage rate of a component has the preferable range of 5-70 mass% in 100 mass% of (A)-(D) component total amount. The lower limit is more preferably 15% by mass or more, and the upper limit is more preferably 50% by mass or less. When the amount of the component (A)-(d) is 5% by mass or more, the wear resistance of the cured film is improved. Moreover, when it is 70 mass% or less, the weather resistance of a cured film becomes good.

<About polyfunctional monomers other than (A)-(d)>
Examples of the polyfunctional monomer other than (A)-(d) include the above-mentioned (A)-(a) component, (A)-(b) component, (A)-(c) component, 4-butanediol diacrylate, glycerol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol hydroxypivalate Di (meth) acrylates such as polyester (meth) acrylate synthesized from diacrylate, dibasic acid, dihydric alcohol and acrylic acid; trimethylolpropane tri (meth) acrylate, tris ((meth) acryloxyethyl) Isocyanurate, pentaerythritol tri (meth) acrylate and other tri ( ) Acrylates; tetra (meth) acrylates such as polyester (meth) acrylate synthesized from ditrimethylolpropane tetra (meth) acrylate, dibasic acid, trivalent or tetravalent alcohol and (meth) acrylic acid, etc. Is mentioned. These monomers may be used individually by 1 type, and may be used in combination of 2 or more types.

  While the polyfunctional monomer component other than (A)-(d) interacts with other components, it mainly imparts toughness and flexibility to the cured coating, and prevents the cured coating from cracking. Improve adhesion. When a coating composition is prepared from the component (A)-(d) without using any multifunctional monomer component other than the components (A)-(d), cracks caused by internal stress generation in the coating film It is easy to generate | occur | produce and a practical abrasion-resistant synthetic resin molded product cannot be obtained.

  Among the polyfunctional monomer components other than (A)-(d), at least one of bis- (acryloyloxyethyl) hydroxyethyl isocyanurate and tris (acryloyloxyethyl) isocyanurate, and 1,9-nonanediol The combined use system with at least one of diacrylate and 1,6-hexanediol diacrylate or urethane acrylate has a large effect of improving adhesion, and weather resistance by accelerated exposure, particularly its transparency and gloss retention or resistance. Since it is excellent in yellowing, it is particularly preferable as a polyfunctional monomer component other than (A)-(d) used in the present invention.

  The proportion of the polyfunctional monomer component other than (A)-(d) is preferably in the range of 20 to 80% by mass in a total of 100% by mass of the components (A) to (D). The lower limit is more preferably 40% by mass or more, and the upper limit is more preferably 70% by mass or less. When the amount of the polyfunctional monomer component other than (A)-(d) is 20% by mass or more, the transparency of the cured film is improved. Moreover, when it is 80 mass% or less, the abrasion resistance of a cured film becomes good.

<About (B) component>
As the photopolymerization initiator as the component (B), any photopolymerization initiator can be used as long as it can initiate polymerization of an acrylic monomer or oligomer by irradiation with active energy rays. Specifically, benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzyldimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methyl Carbonyl compounds such as phenylglyoxylate, ethylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, sulfur compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, 2,4 And acylphosphine oxide such as 1,6-trimethylbenzoyldiphenylphosphine oxide. These are used in one or a mixture of two or more. Among these, benzophenone, benzoin isopropyl ether, methylphenylglyoxylate, and benzyldimethyl ketal are more preferable.

  (B) The usage-amount of a component has the preferable range of 0.1-10 mass% in 100 mass% of total amounts of (A)-(D) component. The lower limit is more preferably 1% by mass or more, and the upper limit is more preferably 5% by mass or less. It is. When the amount of the component (B) is 0.1% by mass or more, curability is improved. Moreover, in the case of 80 mass% or less, the transparency and weather resistance of a cured film are improved.

<About (C) component>
As the hindered amine light stabilizer which is component (C), known hindered amine light stabilizers can be used. Specifically, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1-methoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-ethoxy-2, 2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-propoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-butoxy-2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (1-pentyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-hexyloxy-2,2 6,6-tetramethyl-4-piperidyl) sebacate, bis (1-heptyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-octoxy-2,2,6,6- Tetramethyl-4-piperidyl) sebacate, bis (1-nonyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1-decanyloxy-2,2,6,6-tetramethyl-4) -Piperidyl) sebacate, bis (1-dodecyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, and the like, of which bis (2,2,6,6-tetramethyl-4 -Piperidyl) is particularly preferred.

  (C) The usage-amount of a component has the preferable range of 0.1-5 mass% in 100 mass% of total amounts of (A)-(D) component. The lower limit is more preferably 0.5% by mass or more, and the upper limit is more preferably 2% by mass or less. When the amount of the component (C) is 0.1% by mass or more, the weather resistance of the cured film is improved. On the other hand, when the content is 5% by mass or less, the curability and the toughness, heat resistance, and wear resistance of the cured film are improved.

<About (D) component>
The ultraviolet absorber having the structure represented by the general formula (1) as the component (D) has a characteristic that it is difficult to bleed out even in a high humidity environment, and can provide weather resistance over a long period of time. I can do it. Moreover, since the ultraviolet absorption efficiency is extremely high, sufficient weather resistance can be imparted even when added in a smaller amount than conventional triazine-based ultraviolet absorbers. Since it is added in a small amount, there is little decrease in scratch resistance and adhesion due to the addition of the ultraviolet absorber, and it is possible to achieve both weather resistance, scratch resistance and adhesion.

  The component (D) can be used as long as it dissolves uniformly in the composition and has good weather resistance. If necessary, it may be used in combination with an ultraviolet absorber derived from a triazine, benzophenone, benzotriazole, phenyl salicylate, or phenyl benzoate having another structure.

  In the general formula (1), examples of the linear or branched alkyl group having 17 or less carbon atoms represented by R include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i- Examples include a butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, and an n-stearyl group. In the general formula (1), examples of the monocyclic or polycyclic aryl group represented by Ar include a phenyl group and a naphthyl group, which may have a substituent. Examples of the substituent include an alkyl group having 1 to 17 carbon atoms, a hydroxyl group, and a structure represented by the following general formula (7). R in the general formula (7) represents a linear or branched alkyl group having 17 or less carbon atoms, and specifically includes a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. I-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-stearyl group and the like.

  Specific examples of the component (D) include 2- [4- (octyl-2-methylethanoate) oxy-2-hydroxyphenyl] -4,6- [bis (2,4-dimethylphenyl)]-1, 3,5-triazine {trade name: “Tinuvin 479” (Ciba Specialty Chemicals)}, tris [2,4,6- [2- {4- (octyl-2-methylethanoate) oxy-2-hydroxy Phenyl}]-1,3,5-triazine {trade name: “Tinubin 777” (Ciba Specialty Chemicals)} and the like.

  (D) The usage-amount of a component has the preferable range of 1-20 mass% in 100 mass% of total amounts of (A)-(D) component. The lower limit is more preferably 2% by mass or more, and the upper limit is more preferably 10% by mass or less. When the amount of the component (D) is 1% by mass or more, the weather resistance of the cured film is improved. When the content is 20% by mass or less, the curability and the toughness of the cured film, the heat resistance, the wear resistance, and the substrate adhesion are improved.

  The coating composition of the present invention comprises the above components (A), (B), (C) and (D). If necessary, an organic solvent, an antioxidant, a yellowing inhibitor, Various additives such as inking agents, pigments, leveling agents, antifoaming agents, thickeners, anti-settling agents, antistatic agents, antifogging agents and the like may be contained. The organic solvent is preferably selected according to the type of substrate. For example, when polycarbonate is used as the base material, it is preferable to use one or more of alcohol solvents such as isobutanol and ester solvents such as n-butyl acetate.

  In order to apply the coating composition of the present invention to the substrate, methods such as brush coating, spray coating, dip coating, spin coating, curtain coating, etc. are used, but the coating composition coating workability, coating smoothness, From the standpoint of improving the uniformity and adhesion of the cured film to the substrate, it is preferable to add an appropriate organic solvent for application. Moreover, you may apply | coat, after heating a coating composition in order to adjust a viscosity.

The coating composition of the present invention is crosslinked by irradiation with active energy rays after being applied to a substrate to form a cured film. When curing by irradiation with active energy rays, the coating composition is applied on the substrate so as to have a film thickness of 1 to 50 μm, preferably 3 to 20 μm, and a high-pressure mercury lamp, a metal halide lamp or the like is used. Irradiation with ultraviolet rays of ˜400 nm is carried out so as to be 1000 to 5000 mJ / cm ² . The atmosphere to be irradiated may be air or an inert gas such as nitrogen or argon.

  The coating composition of the present invention can be used to modify the surface of various synthetic resin molded articles that are base materials, but as this synthetic resin molded article, various types that have conventionally been requested to improve wear resistance, weather resistance, etc. These thermoplastic resins and thermosetting resins. Specifically, polymethyl methacrylic resin, polycarbonate resin, polyester resin, poly (polyester) carbonate resin, polystyrene resin, ABS resin, AS resin, polyamide resin, polyarylate resin, polymethacrylimide resin, polyallyl diglycol carbonate resin Etc. In particular, polymethyl methacrylic resin, polycarbonate resin, polystyrene resin, and polymethacrylimide resin are particularly effective to apply the coating composition of the present invention because they are excellent in transparency and have a strong demand for improving wear resistance. Synthetic resin molded products include sheet-shaped molded products, film-shaped molded products, and various injection molded products made of these resins.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The measurement evaluation in the examples was performed by the following method.

(1) Appearance of cured coating The appearance after application and curing of the composition was visually evaluated. A sample having a smooth surface and a transparent surface was marked with ◯, and a sample with whitening or spider observed was marked with ×.

(2) Abrasion resistance Abrasion wheel CS-10F was used for 300 revolutions with a load of 500 g using a Taber abrasion tester, and then the diffusion transmittance (haze value) was measured to determine the abrasion resistance. The criteria for judging wear resistance are as follows.
○: Increase haze value = 0-15
Δ: Increase haze value = 16-20
X: Increase haze value = 21 or more

(3) Adhesion Insert a cross-cut reaching the base material at 1 mm intervals in the cured coating, make 100 1 mm ² grids, apply a serotape on top of them, peel them off, and count the peeled grids. It was. The case where there was no peeling was rated as ◯, the case where the number of peelings was 1-50, and the case where the number of peelings was 51-100, and x.

(4) Heat resistance The coated plate sample was placed in a 120 ° C. hot air dryer for 24 hours, and the appearance change of the cured film was visually observed. The case where there was no change was rated as ◯, the case where a small crack occurred was evaluated as △, and the case where a crack occurred on the entire surface of the coated plate was evaluated as x.

(5) Weather resistance Using a sunshine carbon weatherometer (Suga Test Instruments, WEL-SUN-HC-B type) weather resistance tester, a black panel temperature of 63 ± 3 ° C., rainfall for 12 minutes, and irradiation for 48 minutes. did. The change of the cured film after exposure for 2000 hours and 3000 hours was observed to test the adhesion.
(A) Regarding the discoloration of the appearance, the case where there was no discoloration was rated as ◯, the case where there was a slight yellowing was marked as Δ, and the case where the yellowing was large was marked as x.
(B) Regarding the occurrence of cracks and peeling of the film, those that did not exist were marked with ◯, and those that did exist were marked with ×.

Synthesis Example 1 Synthesis of methacryloyloxy group-containing colloidal silica To a 2-liter 4-necked flask equipped with a stirrer, thermometer, and condenser, isopropanol silica sol (dispersion medium: isopropanol, SiO ₂ concentration: 30% by mass, by BET method) Average particle diameter: 15 nm, trade name: OSCAL1432; manufactured by Catalytic Chemical Industry Co., Ltd.) (hereinafter referred to as OSCAL1432), 1200 parts by mass, γ-methacryloyloxypropyltrimethoxysilane (trade name: “SX-6030”, Toray Industries, Inc.) After adding 240 parts by mass of Dow Corning Silicone Co., Ltd. (hereinafter referred to as SX-6030) and 80 parts by mass of pure water, the mixture was refluxed for 1 hour (reaction temperature 80 ° C.) to carry out a hydrolysis reaction.

  After completion of the hydrolysis, 720 parts by mass of toluene was added, and alcohol, water, and the like were azeotropically discharged together with toluene under normal pressure, and the solvent was completely replaced to obtain a toluene dispersion. The solid content concentration at this time was about 50% by mass.

  Further, a dehydration condensation reaction was carried out at 110 ° C. for 4 hours while distilling off toluene to obtain chemically modified colloidal silica.

  The obtained chemically modified colloidal silica was a pale yellow transparent liquid. The final solid content was 60% by mass. In addition, solid content concentration here is computed with the heating residue method, The calculation method is shown by (mass after heating (g) / mass before heating (g)) x100 (mass%), and heating conditions are 3 hours at 105 ° C.

Example 1
A coating composition was prepared at a blending ratio shown in Table 1, and sprayed onto a polycarbonate resin plate having a thickness of 3 mm (manufactured by GE, trade name: “Lexan LS-II”) so that the coating film after curing was 8 μm. Painted. After volatilizing the organic solvent by heating at 80 ° C. for 3 minutes in an oven, using a high-pressure mercury lamp in the air, irradiating energy of 3000 mJ / cm ² with an integrated light amount of 340 nm to 380 nm, and curing A coating film was obtained. The evaluation results of the obtained coating film are shown in Table 1.

Examples 2-9, Comparative Examples 1-7
A coating composition was prepared at a blending ratio shown in Tables 1 and 2, and a cured coating film was obtained under the same conditions as in Example 1. The evaluation results of the obtained coating film are shown in Tables 1 and 2.

Example 10
It spray-coated so that the coating film after hardening might be set to 8 micrometers on the polymethylmethacrylate resin board (Mitsubishi Rayon Co., Ltd. make, brand name: "Acrypet VH") of thickness 3mm. After volatilizing the organic solvent by heating, using a high-pressure mercury lamp in the air, the accumulated light amount of the wavelength of 340 nm to 380 nm was irradiated with energy of 3000 mJ / cm ² to obtain a cured coating film. The evaluation results of the obtained coating film are shown in Table 1.

Example 11, Comparative Example 8
A coating composition was prepared at a blending ratio shown in Tables 1 and 2, and a cured coating film was obtained under the same conditions as in Example 10. The evaluation results of the obtained coating film are shown in Tables 1 and 2.

  In addition, the symbol of the compound in Table 1 and Table 2 is as follows.

By coating the coating composition of the present invention on a plastic substrate such as an automotive headlamp lens, the lens is protected from ultraviolet rays and scratches over a long period of time even in a harsh environment such as a high humidity environment, and a good appearance Can be maintained. As a result, a good field of view can be secured, leading to improved safety during night driving.

Claims (4)

(A) at least one of an acrylic monomer and an acrylic oligomer;
(B) a photopolymerization initiator,
(C) a hindered amine light stabilizer,
(D) An active energy ray-curable coating composition containing an ultraviolet absorber having a structure represented by the following general formula (1).

(In the formula, R is a linear or branched alkyl group having 17 or less carbon atoms, and Ar is a substituted or unsubstituted monocyclic or polycyclic aryl group.)   The ultraviolet absorber (D) represented by the general formula (1) is 1 to 20% by mass in the composition (however, the total amount of the components (A) to (D) is 100% by mass). Item 2. The active energy ray-curable coating composition according to Item 1. (A) component is
(A)-(a) 10 to 70% by mass of at least one monomer selected from poly (meth) acrylates of mono- or polypentaerythritol represented by the following general formula (2);

(In the formula, at least three of X ^1,1 , X ^1,2 , X ^1,3 , X ^{n + 1,2} , X ^{n + 1,3} and X ^1,4 are CH ₂ ═CR—COO— A group (R represents hydrogen or a methyl group), and the remainder is an —OH group, and n is an integer of 0 to 4).
(A)-(b) 5-50% by mass of at least one urethane poly (meth) acrylate compound having at least two radically polymerizable unsaturated double bonds in one molecule;
(A)-(c) Poly [(meth) acryloyloxyalkyl] (iso) cyanurate represented by the formula (3), (4) or (5), 5 to 70% by mass,

(In the formula, X ¹ , X ² and X ³ represent an acryloyl group, a methacryloyl group, a hydrogen atom or an alkyl group, and at least two of them are an acryloyl group and / or a methacryloyl group, and R ¹ , R ² And R ³ represents an oxyalkylene group or a polyoxyalkylene group.
The active energy ray-curable coating composition according to claim 2, wherein (B) the photopolymerization initiator is 0.1 to 10% by mass, and (C) the hindered amine light stabilizer is 0.1 to 5% by mass. (A) component is
(A)-(d) (meth) acryloyloxy group-containing colloidal silica 5 to 70% by mass, polyfunctional monomer other than (A)-(d) 20 to 80% by mass,
The active energy ray-curable coating composition according to claim 2, wherein (B) the photopolymerization initiator is 0.1 to 10% by mass, and (C) the hindered amine light stabilizer is 0.1 to 5% by mass.