Solventless photocurable resin composition

Abstract

To provide a photocurable resin composition which has good coatability despite being solventless and a cured film of which has good water repellency and oil repellency.SOLUTION: Provided is a solventless photocurable resin composition comprising: a tri- or more functional urethane (meth)acrylate oligomer having a Si atom in the skeleton; a reactive diluent; a surface control agent; and a photoinitiator, where the oligomer has a weight average molecular weight of 800-10,000 and a blending amount of the reactive diluent is 65 wt% or less relative to a total solid content.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solvent-free photocurable resin composition having water and oil repellency. [Background technology]

[0002] Acrylic photocurable resins are used in many fields to impart special properties to the surfaces of plastic films and plastic moldings. For example, hard-coated films, which are applied to PET (polyethylene terephthalate) films to impart high hardness, are used in large quantities as films for touch panels and moldings.

[0003] Among these, touch panel films are widely used as surface components for input devices of information terminals such as smartphones, and in recent years, they are increasingly required to have high transparency, hardness, and stain resistance. For this reason, a resin composition containing, for example, a compound component having an alkoxysilyl group and an acrylate having two or more (meth)acryloyl groups has been proposed as a cured film with enhanced water and oil repellency (Patent Document 1).

[0004] These hard coat resins generally contain solvents to achieve good coatability, but this requires equipment and processes for volatilizing the solvent, and the solvent released from these processes places a significant burden on the environment. On the other hand, when hard coat resins are made solvent-free, the surface conditioner floats to the coating surface when the solvent volatilizes, and by concentrating, it can change the appearance and physical properties of the coating film, which is called the "lifting effect." This makes it difficult to consistently form an appearance and consistently impart properties such as water repellency and oil repellency. Therefore, there is room for improvement in order to create a hard coat resin that is solvent-free yet has good coatability and appearance, and produces a cured film with stable water and oil repellency. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-187205 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a photocurable resin composition which is solvent-free, has good coatability, and produces a cured film having good water and oil repellency. [Means for solving the problem]

[0007] In order to solve the above problem, the invention of claim 1 comprises a tri- or higher functional urethane (meth)acrylate oligomer (A) having a Si atom in the skeleton, a reactive diluent (B); The composition contains a surface conditioner (C) and a photopolymerization initiator (D), wherein the weight average molecular weight of (A) is 800 to 10,000, and the blending amount of (A) is 30 to 95% by weight based on the total solid content. (B) contains a tri- to tetra-functional reactive diluent, and the amount of the diluent blended is 60% by weight or less based on the total amount of solids, and (C) is a fluorine-based compound. The present invention provides a solventless photocurable resin composition characterized by:

[0008] The invention of claim 2 is as follows: The viscosity of the solvent-free photocurable resin composition is 300 to 25,000 mPa·s. The present invention provides the solventless photocurable resin composition according to claim 1, wherein

[0009] The invention of claim 3 is as follows: A hard coat film having a cured layer of the solventless photocurable resin composition according to claim 1 or 2. to provide. [Effects of the Invention]

[0011] The photocurable resin composition of the present invention is solvent-free and has good coatability, and the cured film has sufficient water and oil repellency, making it useful as a hard coat (hereinafter referred to as HC) resin for hard coat films that require antifouling properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will now be described in detail.

[0013] The HC resin composition of the present invention contains a tri- or higher functional urethane (meth)acrylate (A) having a Si atom in the skeleton, a reactive diluent (B), a surface conditioner (C), and a photopolymerization initiator (D). In this specification, the term "(meth)acrylate" includes both acrylate and methacrylate.

[0014] The tri- or higher functional urethane (meth)acrylate (hereinafter referred to as urea) (A) used in this invention has a silicon atom in its skeleton and is the main component of the hard coat film, possessing water- and oil-repellent properties by itself. It is a resin containing three or more (meth)acryloyl groups per molecule and possessing excellent scratch resistance due to the cohesive strength of hydrogen bonds derived from the urethane bonds. When combined with (C), it can impart stable water- and oil-repellent properties to the cured film.

[0015] The (A) can be prepared by a conventionally known method, such as the methods described in JP-A 2004-160932 and Japanese Patent No. 6035325. That is, it can be prepared by a general urethane reaction in which an isocyanate component such as hexamethylene diisocyanate (hereinafter referred to as HDI) is reacted with a polyhydric alcohol having a polysiloxane skeleton and a compound having a hydroxyl group and a (meth)acryloyl group in an appropriate molar ratio using a catalyst such as dibutyltin laurate or dibutyltin acetate.

[0016] When (A) is cured alone, the water contact angle is preferably 85° or more, and more preferably 90° or more. By adjusting the contact angle within this range, stable water and oil repellency can be ensured when combined with (C) to form a composition. When (A) is cured alone, 5 parts by weight of (D) are blended with 100 parts by weight of (A), and the mixture is applied to a PET film in a thickness of 15 μm. The mixture is then cured using an electrodeless UV irradiation device F300S / LC-6B manufactured by Fusion UV Systems Japan under conditions of an H bulb output of 1200 mW / cm² and an integrated light dose of 200 mJ / cm².

[0017] The weight-average molecular weight (hereinafter, Mw) of (A) is 800 to 10,000, preferably 1,000 to 8,000, and more preferably 1,200 to 6,500. If it is less than 800, curing shrinkage will be large, making the composition prone to warping. If it is 10,000 or more, the viscosity of the composition will be too high, making stable coating difficult. The number of functional groups in (A) is preferably 3 to 15, more preferably 4 to 12. A functionality of 3 or more ensures sufficient curing reactivity and film cohesive strength, while a functionality of 15 or less ensures sufficient scratch resistance without increasing curing shrinkage. The Mw was calculated by measuring the molecular weight in terms of standard polystyrene using gel permeation chromatography in a column containing a styrene-divinylbenzene-based packing material and a tetrahydrofuran eluent.

[0018] The blending ratio of (A) to the total solid content is preferably 30 to 95% by weight, more preferably 40 to 90% by weight, and particularly preferably 50 to 80% by weight. By making it 30% by weight or more, sufficient water and oil repellency can be ensured, and by making it 95% by weight or less, sufficiently stable coating properties can be ensured.

[0019] The reactive diluent (B) used in the present invention is blended to dilute the viscosity of the composition to a level that makes it easy to apply, and to improve the abrasion resistance of the cured coating. The number of functional groups is preferably 2 to 6, and more preferably 3 to 4. By making it 2 or more functional, the molecular weight of the cured product can be increased to a level that provides sufficient cohesive strength, while by making it 6 or less functional, sufficient scratch resistance can be ensured without increasing cure shrinkage.

[0020] Examples of (B) include bifunctional compounds such as 1,4-butanediol di(meth)acrylate, 4,6-hexanediol (meth)acrylate, dimethyloltricyclodecane diacrylate, and pentaerythritol di(meth)acrylate; trifunctional compounds such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and glycerin tri(meth)acrylate; and tetrafunctional compounds such as ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and diglycerin tetra(meth)acrylate. These compounds may be used alone or in combination of two or more. Among these, glycerin triacrylate, pentaerythritol triacrylate (hereinafter referred to as PE3A), and pentaerythritol tetraacrylate (hereinafter referred to as PE4A) are preferred because they have high compatibility with (A) and high curing reactivity.

[0021] The blending ratio of (B) to the total solid content is 65% by weight or less, preferably 10 to 60% by weight, more preferably 20 to 50% by weight, and particularly preferably 30 to 40% by weight. If it is 65% by weight or more, it becomes difficult to impart sufficiently stable water and oil repellency to the cured coating.

[0022] The surface conditioner (C) used in the present invention is blended to increase the water and oil repellency of the cured coating film and improve its antifouling properties. Examples include silicone-based, fluorine-based, and acrylic-based compounds. However, it is preferable that the surface conditioner has a reactive functional group capable of polymerizing with the binder resin to form a cured coating film, as this prevents bleeding from the cured coating film over time and maintains its effectiveness for a long period of time. Fluorine-based compounds are particularly preferred because their low surface free energy allows them to easily segregate on the coating film surface after application, thereby stabilizing abrasion resistance and antifouling properties over a long period of time.

[0023] The blending ratio of (C) to the total solid content is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight. By making it 0.5% by weight or more, sufficient water and oil repellency can be ensured, and by making it 10% by weight or less, sufficient pencil hardness can be ensured.

[0024] The photopolymerization initiator (D) used in the present invention generates radicals upon irradiation with ultraviolet light or an electron beam, and these radicals trigger the polymerization reaction, and general-purpose photopolymerization initiators such as benzyl ketals, acetophenones, and phosphine oxides can be used. By arbitrarily selecting the light absorption wavelength of the polymerization initiator, it is possible to impart curability over a wide wavelength range from the ultraviolet region to the visible light region. Specifically, benzyl ketals include 2,2-dimethoxy-1,2-diphenylethan-1-one; α-hydroxyacetophenones include 1-hydroxycyclohexylphenyl ketone and 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one; α-aminoacetophenones include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one; and acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, which can be used alone or in combination. Among these, α-hydroxyacetophenones that are less likely to yellow are preferred, and commercially available products include Omnirad 184 and 2959 (trade names: iGM, α-hydroxyacetophenones).

[0025] The ratio of (D) to 100 parts by weight of the photocurable resin component is preferably 1 to 10 parts by weight, more preferably 3 to 8 parts by weight. By adding 1 part by weight or more, sufficient curability is achieved, and by adding 10 parts by weight or less, excessive addition is avoided, preventing yellowing of the coating film and deterioration of storage stability.

[0026] Furthermore, if necessary, the photocurable resin composition of the present invention may contain an ultraviolet absorber, an antioxidant, a colorant, a leveling agent, an antifoaming agent, a thickener, an anti-precipitation agent, an antistatic agent, an anti-fogging agent, a slip agent, an antiviral agent, an antibacterial agent, organic fine particles, an inorganic filler, or the like.

[0027] The viscosity of this composition is preferably 300 to 25,000 mPa·s, and more preferably 500 to 10,000 mPa·s. This range ensures stable coating properties, good appearance, and uniform film thickness. Viscosity was measured using a Toki Sangyo RE-215R E-type viscometer with a cone angle of 3°R17.65°C at 25±1°C. The rotation speed was 50 rpm for viscosities of 500 mPa·s or less, 20 rpm for 500 to 2000 mPa·s, 10 rpm for 2000 to 5000 mPa·s, 5 rpm for 5000 to 10,000 mPa·s, and 1 rpm for viscosities of 10,000 mPa·s or more.

[0028] Examples of substrates onto which the photocurable resin composition of the present invention is applied include polyester films, polyethylene films, polypropylene films, diacetyl cellulose films, triacetyl cellulose films, acetyl cellulose butyrate films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene vinyl alcohol films, polystyrene films, polycarbonate films, polymethylpentene films, polysulfone films, polyether ether ketone films, polyethersulfone films, polyetherimide films, polyimide films, fluorine resin films, nylon films, acrylic films, and cycloolefin (co)polymer films.

[0029] The method for applying the photocurable resin composition of the present invention is not particularly limited, and can be any known coating method such as spray coating, roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, wire bar coating, or gravure printing, screen printing, offset printing, inkjet printing, etc. The coating thickness can be, for example, 1 μm to 30 μm.

[0030] After coating, the photocurable resin composition of the present invention is cured using an ultraviolet irradiator. Examples of light sources for ultraviolet irradiation include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, electrodeless ultraviolet lamps, and LED lamps. The curing conditions are 500 mW / cm. 2 ~3000mW / cm 2 The irradiation intensity is 50 to 2,000 mJ / cm as the cumulative light amount. 2 The irradiation atmosphere may be air or an inert gas such as nitrogen or argon, but curing in an inert gas is preferred to prevent curing inhibition by oxygen. If it is difficult to set up an inert gas atmosphere, a release film may be attached immediately after coating, and curing may be carried out in a state where the coating surface is prevented from contacting air.

[0031] The present invention will be described in detail below based on examples and comparative examples, but these are intended to be specific examples and are not intended to limit the scope of the invention. Unless otherwise specified, measurements were carried out at a room temperature of 25°C and a relative humidity of 65%. The blend amounts are in parts by weight.

[0032] Example 1 Example 1, a photocurable resin composition, was prepared using UreaC A (hexafunctional with Si atoms in the skeleton, Mw 1550, solids content 100%, and a water contact angle of 93°) as (A), MT-933 (trade name: glycerin triacrylate, manufactured by Toagosei Co., Ltd.) as (B), RS-75NS (trade name: DIC Corporation, with reactive functional groups, solids content 100%, fluorine-based) as (C), and Omnirad184 (trade name: IGM Corporation, α-hydroxyacetophenone-based) as (D) in the formulation shown in Table 1, and the mixture was stirred until uniformly dissolved and dispersed to prepare Example 1, a photocurable resin composition.

[0033] Examples 2 to 8 In addition to the materials used in Example 1, Ureac B (10 functional groups with Si atoms in the skeleton, Mw 5100, solid content 100%, and a water contact angle of 92° alone) and Ureac C (10 functional groups with Si atoms in the skeleton, Mw 2100, solid content 100%, and a water contact angle of 94° alone) were used as (A), and PET-30 (trade name: manufactured by Nippon Kayaku Co., Ltd., a mixture of PE3A and PE4A) was used as (B). These were stirred until uniformly dissolved and dispersed in the formulations shown in Table 1 to prepare photocurable resin compositions of Examples 2 to 8.

[0034] Comparative Examples 1 to 3 In addition to the materials used in the examples, Ureac 1 (a reaction product of HDI nurate (trimer) and PE3A, 100% solids, 9 functional groups, and a water contact angle of 71° alone) and Ureac 2 (a reaction product of HDI and dipentaerythritol pentaacrylate, 100% solids, 10 functional groups, and a water contact angle of 72° alone) were used as oligomers, and the resulting mixture was stirred until uniformly dissolved and dispersed in the formulation shown in Table 1 to prepare Comparative Examples 1 to 3, which are photocurable resin compositions.

[0035] HC film adjustment The photocurable resin composition was applied to a 15 μm thick A4-sized PET film Lumirror U34 (product name: manufactured by Toray Industries, Inc., with double-sided easy-adhesion layers) and then a 75 μm thick release film E7006 (product name: manufactured by Toyobo Co., Ltd., with a silicone release layer on one side) was laminated on top of it. The composition was then photocured using an electrodeless UV irradiation device F300S / LC-6B manufactured by Fusion UV Systems Japan, with an H bulb output of 1200 mW / cm2 and an accumulated light dose of 200 mJ / cm2.

[0036] Table 1 JPEG0007734516000001.jpg63135

[0037] The evaluation method was as follows.

[0038] Coatability: When a good appearance was obtained by leveling immediately after coating, it was marked with an ⊚; when a good appearance was obtained by leveling a few seconds after coating, it was marked with an ◯; when it took more than 10 seconds to level, it was marked with an ×.

[0039] Coating haze: Measured in accordance with JIS K7361-1 using Haze-GARD2 manufactured by Toyo Seiki Seisakusho, with 1.0% or less being rated as ◯ and over 1.0% being rated as x.

[0040] Water contact angle: In accordance with the sessile drop method of JIS R 3257:1999, water was dropped at room temperature using a DMs-400 manufactured by Kyowa Interface Science Co., Ltd., and the contact angle was measured after leaving it to stand for 30 seconds. In the normal state, 95° to 100° was marked as ○, 100 to 105° as ◎, and values ​​outside these ranges were marked as ×.

[0041] Oil-based marker repellency: A continuous arc was drawn using an oil-based marker (trade name: manufactured by Teranishi Chemical Industry Co., Ltd.), and the case where the ink was repelled was marked with a circle, and the case where the ink was not repelled was marked with an X.

[0042] Pencil hardness: In accordance with JIS K5600-5-4 (1999 edition), measurements were taken using a pencil scratch coating hardness tester (Model P) manufactured by Toyo Seiki Seisakusho Co., Ltd., with a load of 750 g. 2H or more was rated as ◯, and less than 2H was rated as ×.

[0043] Abrasion resistance: A load of 500 g / cm 2 was placed on steel wool #0000 and reciprocated 10 times. When visually observed, if no scratches were found, it was marked as ◯, and if scratches were found, it was marked as ×.

[0044] Viscosity: Measurements were taken using a Toki Sangyo RE-215R E-type viscometer with a cone angle of 3°R17.65, with values ​​between 200 and 1000 mPa·s marked as ◯ and values ​​outside this range marked as ×. The rotation speed was 50 rpm for viscosity ranges of 500 mPa·s or less, 20 rpm for 500 to 2000 mPa·s, 10 rpm for 2000 to 5000 mPa·s, 5 rpm for 5000 to 10000 mPa·s, and 1 rpm for 10000 mPa·s or more.

[0045] Evaluation results JPEG0007734516000002.jpg62135

[0046] The examples were satisfactory with no problems in all respects of coatability, coating haze, water contact angle, oil-based marker repelling, pencil hardness, abrasion resistance and viscosity.

[0047] On the other hand, Comparative Example 1, in which the blending amount of (B) was more than 35% by weight, had poor water contact angle and oil-based marker repellency, and Comparative Examples 2 and 3, in which oligomers without Si atoms in the skeleton were used, had low water contact angles and poor oil-based marker repellency, and neither was suitable for the present invention.

Claims

1. 1. A solventless photocurable resin composition comprising: (A) a tri- or higher functional urethane (meth)acrylate oligomer having a Si atom in its skeleton; (B) a reactive diluent; (C) a surface conditioner; and (D) a photopolymerization initiator, wherein the weight-average molecular weight of (A) is 800 to 10,000, the amount of (A) blended is 30 to 95 wt % based on the total amount of solids; (B) comprises a tri- or tetrafunctional reactive diluent, the amount of which is 60 wt % or less based on the total amount of solids; and (C) is a fluorine-based compound.

2. 2. The solvent-free photocurable resin composition according to claim 1, wherein the viscosity of the solvent-free photocurable resin composition is 300 to 25,000 mPa·s.

3. A hard coat film having a cured layer of the solventless photocurable resin composition according to claim 1 or 2.

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