JP2007186573A - Coating material composition, method for forming cured coated film and formed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating material composition without transpiring monomers into atmosphere, excellent in initial close adhesion, and jointly satisfying the good weather resistance (appearance change) and a good close adhesion of the cured coated film with a polycarbonate resin for a long time. <P>SOLUTION: This coating material composition contains (A) 100 pts.mass active energy beam-curing type resin, (B) ≥0.1 pt.mass and ≤10 pts.mass photopolymerization initiator, (C) ≥2 and ≤30 pts.mass ultraviolet light-absorbing agent, (D) ≥0.1 pt.mass and ≤5 pts.mass hindered amine type photo-stabilizer, and (E) ≥3 and ≤20 pts.mass at least 1 kind selected from a group consisting of ethylene diglycol acetate, butyl diglycol acetate, phenoxyethanol and phenoxyethoxyethanol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a coating composition for forming a coating film cured by active energy rays on the surface of a synthetic resin molded article, and imparting weather resistance, abrasion resistance, chemical resistance to the synthetic resin molded article, and a cured coating film thereof. It relates to a synthetic resin molded product.

  When exposed outdoors for a long time, the adhesion between the cured coating film of the active energy ray-curable coating material composition and the substrate decreases with time, and peeling of the cured coating film occurs due to a peeling test or the like. Furthermore, there are cases where even natural peeling occurs depending on the use environment. The present invention relates to a coating material composition with improved adhesion, a method for forming a cured coating film, and a molded article on which the cured coating film is formed.

  In general, polycarbonate resin is widely used as an engineering plastic with excellent transparency, easy moldability, heat resistance, and impact resistance. Especially, taking advantage of the above performance, headlamp lens, tail lamp, side cover lamp and glazing. It is often used for automotive applications such as materials. Among them, the polycarbonate resin is particularly useful for the headlamp lens because of its light weight and improved design for improving the fuel efficiency of automobiles.

  However, since polycarbonate resin has insufficient wear resistance, it has a drawback in that it is susceptible to damage such as scratches on the surface, and weather resistance is insufficient compared to other engineering plastics. In particular, because it is used in outdoor applications, in headlamp lenses, etc., there is a decrease in transparency caused by active energy rays such as ultraviolet rays contained in sand dust or washing, ultraviolet rays contained in sunlight, cracks, crazing, and yellowish color increase. Such appearance deterioration is likely to occur. For this reason, it is indispensable to form a cured coating film that increases abrasion resistance and imparts weather resistance on the surface of the polycarbonate headlamp lens.

  As a method of forming a cured coating film that compensates for the disadvantages of such polycarbonate resin, a coating material composition in which an ultraviolet absorber is blended with an acrylic, melamine, urethane, or silicone resin is applied to the surface of the molded polycarbonate product. A method of forming a coating film by applying and curing using active energy rays such as heat, ultraviolet rays, or electron beams has been developed (Patent Document 1). Among them, the active energy ray curing system using active energy rays has advantages such as superior productivity compared to other methods, so far it has imparted excellent wear resistance and weather resistance to polycarbonate molded products. Many coating material compositions have been developed as possible materials (for example, Patent Documents 2 to 5).

  However, when a cured coating film formed using many active energy ray-curable coating material compositions is exposed to the outdoors for a long time, the adhesiveness with the polycarbonate resin may decrease over time. Improvement of adhesion was desired.

  In general, in order to prevent a decrease in adhesion, a method of adding an additive for improving adhesion to a coating material composition has been proposed. For example, a method of adding dimethylformamide (Patent Document 6), a method of adding dimethylformamide, N-methylpyrrolidone, cyclohexanone and methyl cellosolve to give adhesion (Patent Document 7), 1,6-hexanediol diene There has been proposed a method (Patent Document 8) in which adhesion is imparted by adding an acrylate. Although the initial adhesion is improved by using such an additive, the good weather resistance (change in appearance) of the cured coating film composed of the active energy ray-curable coating material composition and the good adhesion with the polycarbonate resin It was difficult to achieve both properties for a long time.

Improvements in the method of forming a cured coating film have also been implemented. In that case, a heat treatment step is provided for about 5 to 10 minutes between the coating step and the active energy ray curing step, and the active energy ray curable coating material composition is sufficiently dissolved in the polycarbonate resin to improve the adhesion. However, when heated for a long time, monofunctional (meth) acryloyl monomer (hereinafter referred to as monomer) having a small molecular weight volatilizes, and not only the physical properties of the active energy ray-curable coating material composition are deteriorated, but also in the atmosphere. It is pointed out that this causes an environmentally undesirable phenomenon such as scattering of monomers.
JP 56-122840 A JP-A-5-179157 JP-A-3-275769 JP-A-9-286809 JP 2000-281935 A JP-A-9-302268 Japanese Patent Laid-Open No. 10-7939 USP 5990188

  An object of the present invention is a coating material that has excellent initial adhesion without scattering monomers in the atmosphere, and that achieves both good weather resistance (change in appearance) of a cured coating film and good adhesion with a polycarbonate resin for a long period of time. It is to provide a composition.

  Accordingly, as a result of intensive studies to solve this problem, the present inventors have selected an active energy ray-curable coating material composition from the group consisting of ethyl diglycol acetate, butyl diglycol acetate, phenoxyethanol, and phenoxyethoxyethanol. It was found that the cured coating film formed from the composition can achieve good weather resistance and adhesion over a long period outdoors by blending a specific amount of at least one of the above. Further, it has been found that by using the coating material composition of the present invention, sufficient adhesiveness of a cured coating film can be obtained even if the heat treatment step is dramatically shortened compared to the prior art.

  In the present invention, the active energy ray-curable coating material composition is blended with at least one selected from the group consisting of ethyl diglycol acetate, butyl diglycol acetate, phenoxyethanol and phenoxyethoxyethanol, so that it is good for a long time outdoors. Weather resistance and adhesion can be imparted to the cured coating film. More specifically, the coating material composition of the present invention comprises (A) 100 parts by mass of an active energy ray-curable resin, (B) 0.1 part by mass or more and 10 parts by mass or less of a photopolymerization initiator, and (C) an ultraviolet absorber. 2 to 30 parts by mass, (D) from 0.1 to 5 parts by mass of a hindered amine light stabilizer, (E) from the group consisting of ethyl diglycol acetate, butyl diglycol acetate, phenoxyethanol and phenoxyethoxyethanol It is characterized by containing at least one selected from 3 parts by mass to 20 parts by mass.

  According to the present invention, there is provided a coating material composition that is excellent in initial adhesion and provides a cured coating film that achieves both good weather resistance (change in appearance) and good adhesion with a good polycarbonate resin for a long period of time. In addition, the coating material composition of the present invention provides a cured coating film with good adhesion in the heat treatment step provided between the coating step and the active energy ray curing step, regardless of the treatment at a low temperature and in a short time. Therefore, monomer scattering into the atmosphere, which has been a problem in the past, is suppressed, and the material is excellent in physical properties and environmental aspects of the cured coating film.

  Next, each component of the coating material composition of the present invention will be described.

  The active energy ray-curable resin component (hereinafter referred to as “component (A)”) used in the present invention is a resin raw material component composed of a monomer or an oligomer that is cured by irradiation with active energy rays. There is no particular limitation as long as it can be cured by active energy rays, such as a (meth) acryloyl monomer or a (meth) acryloyl oligomer. However, monofunctional (meth) acryloyl monomers and C3-C6 alkanedi (meth) acryloyl monomers represented by 1,6-hexanediol diacrylate are generally low in reactivity, and thus are not exposed even when irradiated with active energy rays. In many cases, it remains in the cured coating film as it is reacted. The remaining monofunctional (meth) acryloyl monomer and the like, when exposed outdoors, may deteriorate over time and cause abnormal appearance and the like. Usable monomers and oligomers include urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, organic-inorganic hybrid (meth) acrylate obtained by condensing colloidal silica and (meth) acryloylalkoxysilane, etc. The monofunctional (meth) acrylate or polyfunctional (meth) acrylate having a polymerizable unsaturated bond may be used, and may be selected according to the required performance of the cured coating film.

  Specific examples of the polyfunctional (meth) acrylate include neopentyl glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (n = 2 to 15) di (meth) acrylate, polypropylene glycol (n = 2) -15) di (meth) acrylate, polybutylene glycol (n = 2-15) di (meth) acrylate, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis (4 -(Meth) acryloxydiethoxyphenyl) propane, trimethylolpropane diacrylate, bis (2- (meth) acryloxyethyl) -hydroxyethyl-isocyanurate, trimethylolpropane tri (meth) acrylate, tris (2- (Meth) acryloxyethyl) isocyanur , Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A diepoxy Polyurethane obtained by reacting 2-hydroxyethyl (meth) acrylate with a trimer of 1,6-hexamethylene diisocyanate, epoxy poly (meth) acrylate such as epoxy di (meth) acrylate obtained by reacting with (meth) acrylic acid Tri (meth) acrylate, urethane di (meth) acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth) acrylate, isophorone diisocyanate and penta Urethane hexa (meth) acrylate reacted with tris (tri) methacrylate, urethane di (meth) acrylate reacted with dicyclomethane diisocyanate and 2-hydroxyethyl (meth) acrylate, dicyclomethane diisocyanate and poly ( n = 6-15) urethane poly (meth) acrylate such as urethane di (meth) acrylate obtained by reacting urethanation reaction product with tetramethylene glycol with 2-hydroxyethyl (meth) acrylate, trimethylolethane and succinic acid, and Polyester polymers such as polyester (meth) acrylate reacted with (meth) acrylic acid, polyester (meth) acrylate reacted with trimethylolpropane and succinic acid, ethylene glycol, and (meth) acrylic acid. Examples include li (meth) acrylate.

  An organic-inorganic hybrid (meth) acrylate obtained by condensing colloidal silica and (meth) acryloylalkoxysilane is also used to increase the hardness of the cured coating film. Specifically, colloidal silica and vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 2 -Combinations of (meth) acryloxyethyltrimethoxysilane, 2- (meth) acryloxyethyltriethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane, 3- (meth) acryloxypropyltriethoxysilane And organic-inorganic hybrid vinyl compounds and organic-inorganic hybrid (meth) acrylate compounds. These (A) components are preferably used in combination as necessary.

  In particular, a combination of one or two kinds of polyfunctional acrylates and a urethane poly (meth) acrylate compound having at least two or more radically polymerizable unsaturated double bonds in one molecule is suitable for a headlamp. Among them, 10 parts by mass or more and 40 parts by mass or less of poly (meth) acrylate of mono- or polypentaerythritol 5 parts of urethane poly (meth) acrylate compound having at least two radically polymerizable unsaturated double bonds in one molecule. Preferably 40 parts by weight or more and 40 parts by weight or less, and a poly [(meth) acryloyloxyalkyl] (iso) cyanurate comprising 20 parts by weight or more and 70 parts by weight or less, preferably with heat resistance, chemical resistance, durability, and substrate. A cured coating film having excellent adhesion can be obtained. When the poly (meth) acrylate of mono- or polypentaerythritol is 10 parts by mass or more, a cured coating film having sufficient abrasion resistance can be obtained. When the amount is 40 parts by mass or less, the wear resistance is improved, cracks are hardly generated, and the heat resistance of the cured coating film is improved. When the urethane poly (meth) acrylate compound is 5 parts by mass or more, a cured coating film having sufficient toughness and weather resistance is obtained, and curability in an air atmosphere is good. In the case of 40 parts by mass or less, the wear resistance of the cured coating film is improved. When poly [(meth) acryloyloxyalkyl] (iso) cyanurate is 20 parts by mass or more, a cured coating film having sufficient wear resistance and heat resistance can be obtained. In the case of 70 parts by mass or less, curability is improved.

  The photopolymerization initiator component (B) used in the present invention (hereinafter referred to as “B component”) may be appropriately selected from the viewpoint of compatibility in the active energy ray-curable coating material composition, and is particularly limited. It is not something.

  Specific examples of the component (B) include, for example, benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzyldimethyl ketal, 2,2-diethoxyacetophenone, 1- Carbonyl compounds such as hydroxycyclohexyl phenyl ketone, methylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide; 2,4 , 6-Trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethyl) Phosphoric acid compounds such as benzoyl) -phenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide; 2-benzyl-2-dimethylamino-1- (4- Morpholinophenyl) butanone-1, camphorquinone and the like. These may be used singly or in combination of two or more, and can be arbitrarily combined depending on the required cured coating film performance.

  In the present invention, the content of component (B) is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of component (A). A more preferred lower limit is 2 parts by mass, and a more preferred upper limit is 6 parts by mass. In the case of 0.1 parts by mass or more, the effect of sufficiently accelerating the curing rate of the cured coating material tends to be exhibited, and the cured film obtained has excellent hardness (abrasion resistance). It tends to be able to impart adhesion and weather resistance. On the other hand, in the case of 10 parts by mass or less, it is possible to prevent coloring of the cured coating film and deterioration of weather resistance.

  The (C) ultraviolet absorber component (hereinafter referred to as “component (C)”) used in the present invention is not particularly limited. Any material that can be uniformly dissolved in the composition and can provide the necessary weather resistance can be used. Particularly preferred are ultraviolet absorbers having a maximum absorption wavelength in the range of 240 to 380 nm, which are compounds derived from benzophenone, benzotriazole, phenyl salicylate, phenyl benzoate and hydroxyphenyltriazine. Type, benzotriazole type, and hydroxyphenyltriazine type ultraviolet absorbers are preferred, and it is most preferred to use a combination of two or more of these. Specific examples of the ultraviolet absorber include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 4 -Dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, phenyl salicylate, p -Tert-butylphenyl salicylate, p- (1,1,3,3, -tetramethylbutyl) phenyl salicylate, 3-hydroxyphenylbenzoate, phenylene-1,3-dibenzoate, 2- (2-hydroxy- '-Methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy3,5-tert-butylphenyl) benzotriazole, 2- ( 2-hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-4-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole 2- (2,4-dihydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -2H-benzotriazole, 2- (2,4-dihydroxyphenyl) -4,6-bis (2, 4-Dimethylphenyl) -1,3,5-triazine and glycidyl alkyl (C12-C1 ) Reaction product with ether, 2- [4- (octyl-2-methylethanoate) oxy-2-hydroxyphenyl] -4,6- [bis (2,4-dimethylphenyl)]-1,3 5-triazine, tris [2,4,6- [2- {4- (octyl-2-methylethanoate) oxy-2-hydroxyphenyl}]-1,3,5-triazine, and the like. Among them, benzophenone-based 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone, benzotriazole-based 2- (2-hydroxy-tert-butylphenyl) benzotriazole, hydroxyphenyltriazine-based 2- [ 4- (Octyl-2-methylethanoate) oxy-2-hydroxyphenyl] -4,6- [bis (2,4-dimethyl) Tilphenyl)]-1,3,5-triazine is particularly preferred, and these are more preferably used in combination of two or more. (C) The usage-amount of a component is 2 to 30 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 5 to 15 mass parts. When the amount of the component (C) is less than 2 parts by mass, the weather resistance of the cured coating film is not sufficient, and when it exceeds 30 parts by mass, the coating film itself is insufficiently cured, and the toughness, heat resistance, Wear resistance is reduced.

  (D) Hindered amine light stabilizer component (hereinafter referred to as “component (D)”) includes bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and 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-piperyl) ) 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, etc., among which bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate Is particularly preferred.

  Moreover, the usage-amount of (D) component is 0.1 to 5 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 0.5 to 2 mass parts. When the amount of the component (D) is less than 0.1 parts by mass, the weather resistance and durability of the cured coating are not sufficient, and when it exceeds 5 parts by mass, the coating itself is insufficiently cured, and the toughness of the cured coating , Heat resistance and wear resistance are reduced.

  As the component (E), at least one selected from the group consisting of ethyl diglycol acetate, butyl diglycol acetate, phenoxyethanol, and phenoxyethoxyethanol is used. Among these, since ethyl diglycol acetate can provide long-term adhesion in outdoor exposure without impairing various physical properties of a cured coating film made of an active energy ray-curable coating material composition, compared to other components (E). More desirable.

  (E) The usage-amount of a component is 3 to 20 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 5 to 10 mass parts. When the amount of the component (E) is less than 3 parts by mass, the adhesion tends to be insufficient, and when it exceeds 20 parts by mass, the water resistance and weather resistance are lowered.

  The coating material composition of the present invention comprises the above components (A) to (E), but if necessary, other organic solvents, antioxidants, yellowing inhibitors, brewing agents, pigments, Components such as various additives such as a leveling agent, an antifoaming agent, a thickening agent, an anti-settling agent, an antistatic agent and a surfactant may be contained. The organic solvent is preferably selected according to the coating method in addition to the component (E). That is, when spray coating is used, alcohol solvents such as isobutanol, ester solvents represented by n-butyl acetate, ketone solvents represented by methyl isobutyl ketone, aromatics represented by toluene Desirably, the viscosity of the coating material composition is 20 mPa · s or less by arbitrarily combining solvents. Moreover, when implementing by the coating method by shower flow coat or a dip, it is desirable to make the viscosity of a coating material composition into 100 mPa * s or less. On the other hand, in a high solid type coating material composition having a solid content exceeding 80% by mass, it is important to select an appropriate solvent in consideration of the solubility of additives such as ultraviolet absorbers.

  In the present invention, the heat treatment process between the coating process and the ultraviolet curing process is very important for realizing long-term adhesion of the cured coating film outdoors and good weather resistance. Generally, the heat treatment process is achieved by heating with an infrared heater, circulation of hot air, or the like. When the coating material composition of the present invention is heat-treated so that the substrate surface temperature during the heat treatment step is 40 ° C. or higher and 90 ° C. or lower after coating, the cured coating film to be formed is outdoors over a long period of time. Adhesion is improved. More preferably, surface substrate temperature is 50 degreeC or more and 70 degrees C or less. When the surface substrate temperature is 40 ° C. or higher, the component (E), the organic solvent, and the like hardly remain inside the coating film, and the performance of the cured coating film can be sufficiently exhibited. Further, when the surface substrate temperature is 90 ° C. or lower, the whitening of the polycarbonate which is a preferable substrate and the deterioration of weather resistance do not occur. The holding time at which the substrate surface temperature is 40 ° C. or more and 90 ° C. or less is 60 seconds or more and 180 seconds or less when heated with infrared heaters, and 120 seconds or more and 300 seconds or less when heated with a hot air dryer. It is preferable that When holding time is lengthened, (E) component, an organic solvent, etc. hardly remain in a coating film inside, and the performance of a cured coating film can fully be exhibited. Shortening the holding time improves productivity.

  The coating material composition of the present invention is cross-linked by irradiation with active energy rays after being applied to a polycarbonate molded article as a preferred substrate to form a cured coating film. When curing by irradiation with active energy rays, the coating material composition is applied on the substrate so that a predetermined film thickness is formed, and then the solvent is volatilized, and then a high-pressure mercury lamp, metal halide lamp, etc. are used. Irradiate ultraviolet rays or electron beams. The atmosphere for irradiation may be air or an inert gas such as nitrogen or argon.

  The coating material composition of the present invention is preferably applied to the outside of an automobile headlamp lens. Polycarbonate has long been used for automobile headlamps because it has high impact resistance, heat resistance, transparency and lightness. However, since the polycarbonate has insufficient performance such as chemical resistance, weather resistance, and scratch resistance, the coating material composition of the present invention is used. In recent years, headlamps have become increasingly large and three-dimensional, and the ability to be easily molded is required. Further, from the viewpoint of reducing fuel consumption, there is a demand for lighter headlamps. From these two points, the transition from glass to polycarbonate for headlamp lenses is rapidly progressing.

  In addition, the polycarbonate coated with the cured coating film of the coating material composition of the present invention has the same performance as glass, is lightweight, and has easy moldability. It can be used suitably. For example, it can be used for outdoor signboards, glass windows in greenhouses and outdoor buildings, roofs of terraces and garages, balconies, and instrument covers.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, the measurement evaluation in an Example was performed with the following method.

(1) Appearance of cured coating film The appearance of a test piece obtained by applying and curing a coating material composition on a polycarbonate substrate was visually evaluated. A sample having a smooth surface and a transparent surface was rated as ◯, and a sample having whitening, yellowing, and spider was observed as ×.

(2) Abrasion resistance Using a Taber abrasion tester, the cured coating side of the test piece was worn 100 revolutions with a wear wheel CS-10F under a load of 500 g, and then the diffusion transmittance (haze value) was measured. Sex determination was performed. The criteria for judging wear resistance are as follows.
◎… Increase haze value = 0 or more and less than 10
○: Increase haze value = 10 or more and less than 15
X: Increase haze value = 15 or more

(3) Adhesion Put a cross-cut reaching the substrate at 1 mm intervals in the cured coating on the test piece, make 100 1 mm ² grids, and sell cellophane tape (manufactured by Nichiban Co., Ltd., trade name) "Cello tape") was applied and peeled off rapidly, and the peeled grids were counted. The case where there is no exfoliation is marked ◎, the case where the number of exfoliation is 1 or more and 10 or less, ○, the case where the number of exfoliation is 11 or more to 49 or less, Δ, the number of exfoliation is 50 or more X.

(4) Water resistance The test piece was immersed in warm water at 60 ° C. for 240 hours, and thereafter the appearance was evaluated by the same method as (1) and the adhesion was evaluated by the same method as (3).

(5) Weather resistance Sunshine carbon weatherometer (manufactured by Suga Test Instruments, WEL-SUN-HC-B) weather resistance tester (black panel temperature 63 ± 3 ° C., rainfall 12 minutes, irradiation 48 minutes cycle)) Were used to test. Changes in the cured coating after 3000 hours exposure were confirmed as follows.
(A) Regarding the discoloration of the appearance, the case where there was almost no discoloration compared with the initial stage was marked with ◯, and the color where yellowing was large was marked with ×.
(B) The adhesion was evaluated by the same method as in (3).
(C) About the generation | occurrence | production of a crack and peeling of a film | membrane, it observed visually, the thing which did not exist was set to (circle), and what existed was set to x.

(Examples and comparative examples)
Examples 1-8, Comparative Examples 1-6
A coating material composition was prepared with the compounding ratio shown in Table 1, and the film thickness of the cured coating film was 10 μm on a polycarbonate resin plate having a thickness of 3 mm (manufactured by GEP, trade name: “Lexan LS2-111”). It was painted by spray method. Subsequently, heating is performed using a far-infrared heater under the condition that the maximum temperature of the substrate surface is as shown in Table 1, and using a high-pressure mercury lamp in the air, an integrated energy amount of light having a wavelength of 340 to 380 nm is 3000 mJ / cm ^2. Was irradiated to obtain a cured coating film. “Temperature” in Table 1 is the maximum temperature of the substrate surface measured while bringing a thermocouple into contact with the substrate surface. The total heating time is described as “hour”, and during the total heating time, the substrate The time during which the surface temperature was maintained at a temperature between 40 and 90 ° C. was recorded as “holding time”. The evaluation results of the obtained cured coating film are shown in Table 1.

In addition, the symbols of the compounds in Table 1 are as follows.
DPHA: Dipentaerythritol hexaacrylate TAIC: Tris (2-acryloyloxyethyl) isocyanurate THFA: Tetrafurfuryl acrylate UA1: Dicyclohexylmethanediol 2 mol, Nonabutylene glycol 1 mol and 2-hydroxyethyl acrylate 2 mol urethane Acrylate MAPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide BAPO: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide Irg. 369: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1
BNP: benzophenone MPG: methylphenylglyoxylate Irg. 184: 1-hydroxycyclohexyl phenyl ketone HBPB: 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole BOTS: bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate PGM: 1-methoxy-propanol ECA: ethyl diglycol acetate BCA: butyl diglycol acetate POEOH: phenoxyethanol POEOEOH: phenoxyethoxyethanol

  Since the constituents of Examples 1 to 8 consisted of composition ratios in the range specified in the present invention, the appearance and adhesion after the weather resistance test were good. Among these, since Examples 5 to 8 were processed in the heat treatment step specified by the method for forming a cured coating film of the present invention, the adhesion after the weather resistance test was particularly good.

  In Comparative Examples 1, 3, and 5, since the amount of the component (E) exceeded 20 parts by mass, the appearance of the initial cured coating film and the appearance of the cured coating film after the weather resistance test occurred, and the cured coating film surface layer A crack occurred.

  In Comparative Examples 2, 4, and 6, since the amount of the component (E) was less than 3 parts by mass, the adhesion after the weather resistance test was lowered.

Claims (6)

  (A) Active energy ray-curable resin 100 parts by mass, (B) 0.1 to 10 parts by mass of photopolymerization initiator, (C) 2 to 30 parts by mass of ultraviolet absorber, (D) hindered amine Type light stabilizer 0.1 to 5 parts by mass, (E) 3 to 20 parts by mass of at least one selected from the group consisting of ethyl diglycol acetate, butyl diglycol acetate, phenoxyethanol and phenoxyethoxyethanol Coating material composition containing below.   A coating material composition according to claim 1 is applied to a substrate and cured with active energy rays to form a cured coating film on the surface of the substrate, between the coating and the active energy ray curing step. A method of forming a cured coating film, comprising a heat treatment step, wherein the substrate surface temperature is 40 to 90 ° C. and then cured with active energy rays.   A molded article obtained by coating the substrate surface with a cured coating film of the coating material composition according to claim 1.   The molded article according to claim 3, wherein the molded article is an automobile headlamp lens.   The molded article according to claim 3 or 4, wherein the base material is a polycarbonate resin. The molded article according to any one of claims 3 to 5, wherein a cured coating film is formed by the method of claim 2.