Actinic energy ray-curable composition and resin moulded body

Abstract

A solvent-free, actinic energy ray-curable composition containing a polyfunctional acrylate and an intramolecular cleavage initiator, said actinic energy ray-curable composition having a viscosity of 10 to 60 mPa·s, and a viscosity change percentage of ±20% or less before and after being stored for 30 min in the presence of a fluorescent lamp and in an air atmosphere at a temperature of 23°C.

Description

Active energy ray-curable composition and resin molded product

[0001] The present invention relates to an active energy ray-curable composition and a resin molded article.

[0002] Transparent synthetic resins such as polycarbonate resin (PC) and polymethyl methacrylate resin (PMMA) have excellent transparency, moldability, and mechanical properties, and are therefore used in many fields, such as lamp covers (outer covers) for automobiles and motorcycles, eyeglass lenses, optical sensor covers, and various liquid crystal panels. However, when the surface temperature of a molded product such as a synthetic resin drops below the dew point, moisture in the air condenses into fine droplets, causing fogging. This reduces light transmittance, resulting in poor visibility and malfunction of sensors and the like. Furthermore, the adhesion of scratches or dirt to the surface of a molded product such as a synthetic resin can reduce light transmittance, resulting in poor visibility and malfunction of sensors and the like. To prevent these problems, a composition is applied to the surface of a molded product (coated object) such as a synthetic resin, and the composition hardens on the surface of the molded product as a cured film, thereby ensuring transparency.

[0003] However, when the composition is sprayed onto the surface of a molded article, the composition that does not adhere to the surface of the molded article, i.e., the uncoated portion, is discarded, which results in poor utilization of the composition, and causes problems such as increased costs and an increased environmental load.

[0004] For example, Patent Document 1 discloses a method and device for recovering UV-curable paint that has not adhered to an object to be coated.

[0005] Japanese Patent Application Laid-Open No. 2005-342550

[0006] However, even if the composition that has become the object to be coated is recovered in this manner, if the viscosity of the object to be coated increases, the composition that has become the object to be coated cannot be used again for spray coating.

[0007] The present invention has been made in view of the above points, and an object of the present invention is to provide a reusable active energy ray-curable composition and a resin molded article having a cured film obtained by curing the active energy ray-curable composition.

[0008] A solventless active energy ray-curable composition containing a multifunctional acrylate and an intramolecular cleavage initiator, wherein the active energy ray-curable composition has a viscosity of 10 to 60 mPa·s and exhibits a viscosity change rate of ±20% or less before and after storage for 30 minutes in the presence of a fluorescent lamp in an air atmosphere at a temperature of 23°C.

[0009] It is a conceptual diagram showing a resin molded body of the present invention. It is a diagram showing a manufacturing process of a resin molded body of the present invention. It is a table summarizing the results of comparison between Examples and Comparative Examples of the active energy ray-curable composition of the present invention.

[0010] An embodiment of the present invention will be described. The active energy ray-curable composition 10 of the present invention is solventless. Here, "solventless" means that the active energy ray-curable composition 10 does not contain a non-reactive volatile organic solvent, or that it does not substantially contain a non-reactive volatile organic solvent. "Substantially does not contain a non-reactive volatile organic solvent" means that when the active energy ray-curable composition is subjected to gas chromatography analysis at 200°C, the total amount of components detected as having a structure not containing a vinyl group or an acryloyl group is less than 1 mass%.

[0011] Because the active energy ray-curable composition 10 is solvent-free, when the active energy ray-curable composition is cured, most of it becomes a cured film as an active ingredient, which makes it possible to reduce the total amount of the active energy ray-curable composition required for application to the surface of the substrate 20 (molded product).

[0012] The active energy ray-curable composition 10 exhibits a viscosity change rate (%) of ±20% or less before and after storage for a predetermined period of time under predetermined conditions. Specifically, the viscosity change rate is ±20% or less before and after storage for 30 minutes in the presence of a fluorescent lamp in an air atmosphere at a temperature of 23°C.

[0013] Because the viscosity change rate of the active energy ray-curable composition 10 is ±20% or less, when spray coating is performed, the uncoated material that does not adhere to the substrate 20 can be collected and the collected uncoated material can be reused in spray coating as is. In other words, the recyclability of the active energy ray-curable composition that has become the uncoated material is improved, and waste can be reduced.

[0014] The polyfunctional acrylate is a highly reactive hydrophobic material. Because of its high reactivity, the active energy ray-curable composition 10 can be cured at a high rate by using the polyfunctional acrylate as the main component.

[0015] Because the polyfunctional acrylate is hydrophobic, it can improve the adhesion between the active energy ray-curable composition 10 and the substrate 20 when applied to a hydrophobic substrate. This can prevent the cured film from peeling off from the substrate. Furthermore, the high adhesion between the cured film and the substrate can also prevent cracks from occurring in low-temperature environments. Therefore, a cured film with excellent durability can be formed on the substrate.

[0016] The content of the polyfunctional acrylate is 90% by mass or more relative to the total amount of the active energy ray-curable composition 10. In other words, the main component of the active energy ray-curable composition 10 is the polyfunctional acrylate.

[0017] Examples of polyfunctional acrylates that can be used include trimethylolpropane trimethacrylate, PEG 200 diacrylate, PEG 600 diacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, 2-hydroxy-3-acryloyloxypropyl acrylate, polytetramethylene glycol diacrylate, dipentaerythritol hexaacrylate, and pentaerythritol triacrylate. These polyfunctional acrylates may be used alone or in combination of two or more.

[0018] By using these polyfunctional acrylates as the main component of the active energy ray-curable composition 10, the viscosity of the active energy ray-curable composition can be adjusted to 10 to 60 mPa·s, which is a viscosity suitable for spray coating. It is more preferable to use PEG200 diacrylate, triethylene glycol diacrylate, polytetramethylene glycol diacrylate, or the like as the polyfunctional acrylate, thereby adjusting the viscosity of the active energy ray-curable composition to 10 to 30 mPa·s.

[0019] The initiator is a radical generator that generates highly active radicals when irradiated with ultraviolet light. These radical species undergo decomposition and react with resin components such as monomers and / or oligomers. This reaction product then reacts with other resin components, causing a chain reaction to proceed. The crosslinking reaction then progresses, increasing the molecular weight and curing the polyfunctional acrylate, forming a cured film.

[0020] The content of the initiator is preferably 1% by mass or more and less than 10% by mass with respect to the total amount of the active energy ray-curable composition 10. If the content of the initiator is less than 1% by mass, the active energy ray-curable composition will not be cured sufficiently, resulting in poor curing. On the other hand, if the content of the initiator is 10% by mass or more, the molecular weight will not increase, resulting in insufficient strength of the cured film.

[0021] As the initiator, an intramolecular cleavage type initiator such as 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 4'-(2-hydroxyethoxy)-2-hydroxy-2-methylpropiophenone, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, etc. can be used. These initiators can be used alone or in combination of two or more.

[0022] In addition to the initiator, the active energy ray-curable composition 10 may contain various additives such as an antibacterial agent, an antifungal agent, an antifoaming agent, an antioxidant, an antistatic agent, a dye, and a polymerization inhibitor.

[0023] Examples of antibacterial agents include captan, carbendazim, quinomethionate, chlorothalonil, clozolinate, cyprodinil, epoxiconazole, famoxadone, fenarimol, fenbuconazole, fenfuram, fenpiclonil, azoxystrobin, benalaxyl, benomyl, bitertanol, fluazinam, fludioxonil, fluorimide, fluquinconazole, flusulfamide, flutolanil, folpet, Hexachlorobenzene, hexaconazole, ipoconazole, iprodione, kresoxim methyl, manzeb, maneb, mepanipyrim, mepronil, metconazole, metiram, phthalide, procymidone, propineb, quintozene, tecnazene, thifluzamide, thiophenate methyl, thiram, tolclofos methyl, tolylfluanid, triadimefon, triadimenol, triazoxide, triforine, etc. can be used. Inorganic antibacterial agents can also be used, for example, silver, copper, zinc, tin, lead, gold, etc. Furthermore, synthetic antibacterial agents can also be used, for example, polyhexamethylene hyguanide, hydrochloride, benzethonium chloride, alkylpolyaminoethylglycine, benzisothiazoline, etc.

[0024] Examples of the antifungal agent that can be used include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof.

[0025] Examples of the defoaming agent that can be used include fatty acid salts, liquid fatty oil sulfates, higher alcohol sulfates, fatty alcohol phosphates, fatty acid amide sulfonates, sulfonates of dibasic fatty acid esters, alkylarylsulfonates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, acrylic polymers, vinyl polymers, and organopolysiloxanes.

[0026] Examples of the antioxidant that can be used include phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Examples of the phenol-based antioxidant include 2,6-di-tert-butyl-p-cresol, stearyl β-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate, and 1,3,5-trimethyl-2,4,6-tris(3',5'-di-tert-butyl-4-hydroxybenzyl)benzene. Examples of the phosphorus-based antioxidant include tris(2,4-di-tert-butylphenyl)phosphite, diphenylmono(2-ethylhexyl)phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)-2-ethylhexyl phosphite, distearyl pentaerythritol diphosphite, and tri(mononylphenyl)phosphite. Examples of sulfur-based antioxidants that can be used include dilauryl-3,3'-thiodipropionate and pentaerythritol tetrakis(3-laurylthiopropionate).

[0027] Examples of the antistatic agent that can be used include various cationic antistatic agents having a cationic group such as a primary to tertiary amino group, a quaternary ammonium salt, or a pyridinium salt; anionic antistatic agents having an anionic group such as a sulfonate group, a sulfate group, a phosphate group, or a phosphonate group; amphoteric antistatic agents such as amino acid-based or amino sulfate-based; nonionic antistatic agents such as amino alcohol-based, glycerin-based, or polyethylene glycol-based; and polymeric antistatic agents obtained by increasing the molecular weight of the above-mentioned antistatic agents.

[0028] Examples of dyes that can be used include pyrazole azo compounds, anilino azo compounds, triarylmethane compounds, anthraquinone compounds, anthrapyridone compounds, benzylidene compounds, oxonol compounds, pyrazolotriazole azo compounds, pyridone azo compounds, cyanine compounds, phenothiazine compounds, pyrrolopyrazole azomethine compounds, xanthene compounds, phthalocyanine compounds, benzopyran compounds, indigo compounds, and pyrromethene compounds.

[0029] A polymerization inhibitor may be added to prevent the double bond from reacting. Examples of the polymerization inhibitor include hydroquinone (HQ), hydroquinone monomethyl ether (MEHQ), 2,6-di-t-butyl-4-methylphenol (BHT), t-butylcatechol (TBC), and phenol or naphthol derivatives such as 4-methoxy-1-naphthol, phenothiazine derivatives, and nitrosamine salts.

[0030] 2, a method for producing a resin molded body 30 in which an active energy ray-curable composition 10 is cured on the surface of a substrate 20 will be described. First, the active energy ray-curable composition 10 was loaded into a paint gun (S1). Then, the substrate 20 to be coated was fixed to a painting jig (S2). The active energy ray-curable composition 10 was applied to the surface of the substrate 20 with the paint gun to a uniform film thickness of less than 10 μm (S3). The active energy ray-curable composition 10 was irradiated with ultraviolet light (S4). The active energy ray-curable composition 10 was cured on the surface of the substrate 20 to form a cured film (S5). As described above, a resin molded body 30 in which the active energy ray-curable composition 10 is cured on the surface of the substrate 20 can be produced.

[0031] When applying the active energy ray-curable composition 10 to the surface of the substrate 20, the composition may be applied to a part of the surface of the substrate 20, or may be applied to the entire surface of the substrate 20. The method for applying the active energy ray-curable composition 10 is not limited to a coating gun, and an application method using an inkjet or a dispenser may also be used.

[0032] As the substrate 20, in addition to polycarbonate resin (PC), hydrophobic synthetic resin such as polymethyl methacrylate resin (PMMA), hydrophobic materials such as glass, and the like can be used.

[0033] The active energy ray-curable composition 10 can be used as a hard coat or an anti-fog coat. Furthermore, the resin molded product 30 obtained by curing the active energy ray-curable composition 10 on the surface of a substrate 20 can be used as an outer lens (translucent cover) for a vehicle lamp, a window glass, a lens for eyeglasses, a cover for the surface of an optical sensor, and the like.

[0034] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0035] Example 1 95 parts by mass of trimethylolpropane trimethacrylate (product name: product code: T0912, manufactured by Tokyo Chemical Industry Co., Ltd.) as a polyfunctional acrylate was added to a 300 mL separable flask equipped with a stirring blade. Next, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 1.

[0036] Example 2 99 parts by mass of PEG200 diacrylate (product name: PEG200DA, manufactured by Daicel Allnex Corporation) as a multifunctional acrylate was added to a 300 mL separable flask equipped with a stirring blade. Next, 1 part by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 2.

[0037] Example 3 90 parts by mass of PEG600 diacrylate (product name: EBECRYL 11, manufactured by Daicel-Allnex Corporation) as a multifunctional acrylate was added to a 300 mL separable flask equipped with a stirring blade. Next, 10 parts by mass of 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropane (product name: Omnirad2959, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 3.

[0038] Example 4 95 parts by mass of triethylene glycol diacrylate (product name: Light Acrylate 3EG-A, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate was added to a 300 mL separable flask equipped with a stirring blade. Next, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 4.

[0039] Example 5 95 parts by mass of triethylene glycol diacrylate (product name: Light Acrylate 3EG-A, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate was added to a 300 mL separable flask equipped with a stirring blade. Next, 5 parts by mass of 4'-(2-hydroxyethoxy)-2-hydroxy-2-methylpropiophenone (product name: Omnirad2959, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 5.

[0040] Example 6 A 300 mL separable flask equipped with a stirring blade was charged with 13 parts by mass of pentaerythritol triacrylate (product name: Light Acrylate PE-3A, manufactured by Kyoeisha Chemical Co., Ltd.) as a multifunctional acrylate and 85 parts by mass of PEG200 diacrylate (product name: PEG200DA, manufactured by Daicel-Allnex Corporation). Next, 2 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator were added. The mixture was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 6.

[0041] Example 7 A 300 mL separable flask equipped with a stirring blade was charged with 50 parts by mass of 2-hydroxy-3-acryloyloxypropyl acrylate (product name: Light Ester G-201P, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate and 45 parts by mass of triethylene glycol diacrylate (product name: Light Acrylate 3EG-A, manufactured by Kyoeisha Chemical Co., Ltd.). Next, 5 parts by mass of 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (product name: Omnirad907, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. The mixture was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 7.

[0042] Example 8 A 300 mL separable flask equipped with a stirring blade was charged with 60 parts by mass of 2-hydroxy-3-acryloyloxypropyl acrylate (product name: Light Ester G-201P, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate and 35 parts by mass of polytetramethylene glycol diacrylate (product name: Light Acrylate PTMGA-250, manufactured by Kyoeisha Chemical Co., Ltd.). Next, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. The mixture was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 8.

[0043] Example 9 To a 300 mL separable flask equipped with a stirring blade, 97 parts by mass of polytetramethylene glycol diacrylate (product name: Light Acrylate PTMGA-250, manufactured by Kyoeisha Chemical Co., Ltd.) was added as a multifunctional acrylate. Next, 3 parts by mass of 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropane (product name: Omnirad2959, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 9.

[0044] Example 10 To a 300 mL separable flask equipped with a stirring blade, 15 parts by mass of dipentaerythritol hexaacrylate (product name: Light Acrylate DPE-6A, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate and 80 parts by mass of polytetramethylene glycol diacrylate (product name: Light Acrylate PTMGA-250, manufactured by Kyoeisha Chemical Co., Ltd.) were added. Next, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 10.

[0045] Example 11 A 300 mL separable flask equipped with a stirring blade was charged with 15 parts by mass of pentaerythritol triacrylate (product name: Light Acrylate PE-3A, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate and 80 parts by mass of triethylene glycol diacrylate (product name: Light Acrylate 3EG-A, manufactured by Kyoeisha Chemical Co., Ltd.). Next, 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name: Omnirad184, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. The mixture was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Example 11.

[0046] Comparative Example 1 To a 300 mL separable flask equipped with a stirring blade, 95 parts by mass of pentaerythritol tetraacrylate (product name: Light Acrylate PE-4A, manufactured by Kyoeisha Chemical Co., Ltd.) as a polyfunctional acrylate was added. Next, 5 parts by mass of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (product name: Omnirad TPO, manufactured by Sanyo Trading Co., Ltd.) as an initiator was added. This was stirred at room temperature for 30 minutes, yielding 100 parts by mass of the active energy ray-curable composition of Comparative Example 1.

[0047] (Viscosity Measurement) The first viscosity was measured for each of the active energy ray-curable compositions of Examples 1 to 11 and the active energy ray-curable composition of Comparative Example 1. The viscosity was measured using an E-type viscometer (product name: TVE-22L, manufactured by Toki Sangyo Co., Ltd.) in accordance with JIS K2283. The viscosity measurement results for Examples 1 to 11 and Comparative Example 1 are shown together in Figure 3.

[0048] (Measurement of Viscosity Change) The active energy ray-curable compositions of Examples 1 to 11 or the active energy ray-curable composition of Comparative Example 1 were spray-coated onto a substrate to a film thickness of 10 μm (gravity spray coating, W-50-124BPG, manufactured by Anest Iwata Co., Ltd.). Uncoated material that did not adhere to the surface of the substrate was collected on a stainless steel tray at a 45-degree incline on a PTFE sheet, and then transferred to a Good Boy (sealed container) and capped. This was left to stand for 30 minutes at a temperature of 23°C under fluorescent light, and then the second viscosity was measured for each. The viscosity was measured using an E-type viscometer (product name: TVE-22L, manufactured by Toki Sangyo Co., Ltd.) in accordance with JIS K2283. Figure 3 shows a summary of the viscosity change measurement results for Examples 1 to 11 and Comparative Example 1.

[0049] (Evaluation of Viscosity Change Rate) The viscosity change rate was calculated by substituting the first viscosity and the second viscosity into the following formula 1, and the viscosity change rate of the active energy ray-curable compositions of Examples 1 to 11 or the active energy ray-curable composition of Comparative Example 1 was evaluated.

[0050] Viscosity change rate (%) = (second viscosity - first viscosity) ÷ first viscosity × 100 (1)

[0051] The evaluation was made as follows: A: the viscosity change rate was 0% or more and less than 5%, B: the viscosity change rate was 5% or more and less than 10%, C: the viscosity change rate was 10% or more and less than 15%, D: the viscosity change rate was 15% or more and less than 20%, and E: the viscosity change rate was 20% or more. Figure 3 shows the evaluation results of the viscosity change rates of Examples 1 to 11 and Comparative Example 1.

[0052] (Evaluation of Non-reactive Volatile Organic Solvent Content) The active energy ray-curable compositions of Examples 1 to 11 and the active energy ray-curable composition of Comparative Example 1 were each subjected to gas chromatography analysis at 200°C, and the total value of components detected with a structure not containing a vinyl group or an acryloyl group was determined. The evaluation was rated A when the total value was less than 1 mass%, B when the total value was 1 mass% or more but less than 10 mass%, C when the total value was 10 mass% or more but less than 30 mass%, D when the total value was 30 mass% or more but less than 50 mass%, and E when the total value was 50 mass% or more. FIG. 3 shows a summary of the evaluation results for the non-reactive volatile organic solvent content of Examples 1 to 11 and Comparative Example 1.

[0053] (Evaluation of Dischargeability) The viscosity of the active energy ray-curable compositions of Examples 1 to 11 and the active energy ray-curable composition of Comparative Example 1 was evaluated based on the first viscosity. The evaluation was as follows: A when the viscosity was 3 mPa·s or more and less than 30 mPa·s, B when the viscosity was 30 mPa·s or more and less than 40 mPa·s, C when the viscosity was 40 mPa·s or more and less than 50 mPa·s, D when the viscosity was 50 mPa·s or more and less than 80 mPa·s, and E when the viscosity was 80 mPa·s or more. Figure 3 shows a summary of the evaluation results of dischargeability for Examples 1 to 11 and Comparative Example 1.

[0054] 3, it is clear that the active energy ray-curable compositions of Examples 1 to 11 have lower viscosities and viscosity change rates than the comparative examples. Therefore, the active energy ray-curable compositions of Examples 1 to 11 are suitable for spray coating, and the active energy ray-curable compositions of Examples 1 to 11 that have become uncoated can be reused as paints.

[0055] It is also clear that the active energy ray-curable compositions of Examples 1 to 11 can reduce the content of non-reactive volatile organic solvents and ensure excellent dischargeability. Therefore, the proportion of the active ingredient that forms the cured film is large, allowing for a reduction in the total amount of materials, and also eliminating the need for dilution with an organic solvent when spray coating, thereby reducing power consumption during production.

[0056] From the results of Examples 1, 2, and 4 to 11, it is clear that when the content of the initiator is set to 5% or less, the second viscosity is 55 mPa s or less, and therefore the uncoated active energy ray-curable composition is suitable for reuse as a paint.

[0057] From the results of Examples 2, 4, 5, 6, 9, and 11, it is clear that when PEG200 diacrylate, triethylene glycol diacrylate, or polytetramethylene glycol diacrylate is contained as the main component as a multifunctional acrylate, the viscosity is less than 40 mPa s in the ejection property evaluation, and therefore better ejection properties can be imparted.

[0058] In contrast, the active energy ray-curable composition of Comparative Example 1 had a high viscosity change rate, making it impossible to reuse the uncoated active energy ray-curable composition as a paint. Furthermore, in the evaluation of dischargeability, the viscosity was 80 mPa s or more, which clearly shows that spray coating is not possible unless the composition is diluted with an organic solvent.

[0059] As described above, according to the present invention, it is possible to provide a reusable active energy ray-curable composition 10 and a resin molded body 30 having a cured film obtained by curing the active energy ray-curable composition 10.

[0060] 10 Active energy ray curable composition 20 Substrate 30 Resin molded body

Claims

1. A solventless active energy ray-curable composition comprising a multifunctional acrylate and an intramolecular cleavage initiator, the active energy ray-curable composition having a viscosity of 10 to 60 mPa·s and a viscosity change rate of ±20% or less before and after storage for 30 minutes in the presence of a fluorescent lamp and in an air atmosphere at a temperature of 23°C.

2. The active energy ray-curable composition according to claim 1, which has a viscosity of 10 to 30 mPa·s.

3. A resin molded article comprising a cured film obtained by curing the active energy ray-curable composition according to claim 1 or 2, and a substrate having the cured film on at least a portion of its surface.

4. The resin molded article according to claim 3, wherein the substrate is hydrophobic.

5. The resin molded article according to claim 4, wherein the substrate is made of a polymethyl methacrylate resin or a polycarbonate resin.

6. The resin molding according to claim 3, which is an outer lens of a vehicle lamp.

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