JP2023022393A - Photocurable coating agent composition and laminate having cured layer thereof - Google Patents

Abstract

To provide a photocurable coating agent composition that has sufficiently low moisture permeability even with a small thickness, and also has excellent wear resistance and a laminate having a cured layer thereof.SOLUTION: A photocurable coating agent composition contains a 2-8 functional methacrylate having an isocyanuric acid skeleton, surface-treated nano silica, and a photopolymerization initiator. The methacrylate includes a urethane methacrylate produced from a reaction between a hexamethylene diisocyanate trimer and an OH group-bearing methacrylate and/or an isocyanuric acid EO-modified methacrylate.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a photocurable coating composition having extremely excellent water vapor barrier properties and low moisture permeability, which is cured by irradiation with light such as ultraviolet rays, and a laminate having a cured layer thereof.

UV curable resin takes advantage of its ability to cure in a short time, and is used in a wide range of applications, from industrial materials such as coating agents for films and moldings, sealing agents for electronic parts and electrical contacts, to familiar products such as adhesives and gel nails. It's being used. Among these coating agents, hard coating agents for liquid crystal panel members are well known. Recently, the applications are diversifying, and demands for durability such as stability against environmental changes are becoming stricter.

A cellulose ester film that easily absorbs moisture is often used to protect the surface of a polarizing plate, which is one of the components of a liquid crystal panel. It is described that deterioration of the display screen caused by environmental changes of the liquid crystal display device can be suppressed. Therefore, as a method for reducing the moisture permeability, for example, a compound having three or more ethylenically unsaturated double bonds, two types of alicyclic epoxy compounds, a radical polymerization initiator, and a low moisture permeability containing a cationic polymerization initiator A film having a moisture-permeable hard coat layer has been proposed (Patent Document 2).

The use of such resins has made it possible to achieve low moisture permeability even when using cellulose ester films. In some cases, there were problems in terms of flexibility and warpage. Therefore, there has been a demand for a hard coat resin that has good resistance to steel wool even if the hard coat layer is thin, and that is capable of achieving low moisture permeability.

JP-A-2008-256747 JP 2016-194566 A

An object of the present invention is to provide a photocurable coating composition having sufficiently low moisture permeability and good wear resistance even when the film thickness is thin, and a laminate having a cured layer thereof.

In order to address the above problems, the invention according to claim 1 comprises a di- to octa-functional (meth)acrylate (A) having an isocyanuric acid skeleton, a surface-treated nanosilica (B), and a photopolymerization initiator (C). (A) contains urethane (meth)acrylate (a1) and/or isocyanuric acid EO-modified (meth)acrylate (a2) obtained by reacting hexamethylene diisocyanate trimer and (meth)acrylate having an OH group Provided is a photocurable coating composition characterized by:

The invention according to claim 2 is the photocurable coating composition according to claim 1, wherein the amount of (B) is 100 to 800 parts by weight with respect to 100 parts by weight of (A). I will provide a.

The invention according to claim 3 is characterized in that the (B) comprises surface-treated nanosilica (b1) having an average primary particle diameter of 1 to 30 nm and surface-treated nanosilica (b2) having an average primary particle diameter of 35 to 100 nm. The photocurable coating composition according to claim 1 or 2 is provided.

The invention according to claim 4 provides the photocurable coating composition according to any one of claims 1 to 3, wherein (A) is di- to penta-functional.

The invention according to claim 5 provides a laminate having a cured layer of the photocurable coating agent according to any one of claims 1 to 4 on at least one surface of a plastic substrate film.

The composition of the present invention has good curability with respect to light irradiation such as ultraviolet rays, has sufficiently low moisture permeability even when the film is thin, and has good wear resistance. It is useful as a photocurable coating agent composition to be used.

The present invention will be described in detail below.

The composition of the present invention comprises a di- to octa-functional (meth)acrylate (A) having an isocyanuric acid skeleton, nanosilica (B), and a photopolymerization initiator (C). In this specification, (meth)acrylate includes both acrylate and methacrylate.

Di- to octa-functional (meth)acrylate (A) having an isocyanuric acid skeleton used in the present invention is the main resin constituting the cured film and has at least hexamethylene diisocyanate (hereinafter referred to as HDI) trimer and OH group ( Urethane (meth)acrylate reacted with meth)acrylate (hereinafter referred to as ureac) (a1) and/or isocyanuric acid EO-modified (meth)acrylate (a2).

Since (a1) has an HDI trimer (isocyanurate) skeleton, it has excellent scratch resistance, and since it is aliphatic, it has excellent weather resistance and water vapor barrier properties. Examples of (meth)acrylates having an OH group to be reacted with HDI include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. Acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate and the like. Among these, 2-hydroxyethyl acrylate (hereinafter referred to as 2HEA) is preferred, but it may be combined with, for example, pentaerythritol triacrylate (hereinafter referred to as PETA) as long as the number of functional groups is 8 or less.

The above (a1) can be obtained by reacting the isocyanate group of HDI and the functional group molar ratio of the OH group by adjusting the molar ratio. Specifically, the isocyanate group:OH group ratio is preferably 1:1.5 to 1:8, more preferably 1:2 to 1:6. The reaction can be carried out according to a conventional method. For example, HDI and a (meth)acrylate having an OH group are placed under conditions of 50 to 90° C., and a tin-based compound such as dibutyltin dilaurate is used as a catalyst for the reaction. . The reaction may be carried out either in the absence of a solvent or in the presence of an organic solvent, and examples of solvents that can be used include methyl ethyl ketone and ethyl acetate.

・・・・・（１）
Ｒ＝“（ＣＨ_２）_２ＯＣＯＣＨ＝ＣＨ_２”又は”（ＣＨ_２）_２ＯＨ“ The (a2) is represented, for example, by the following formula (1). Similar to (a1), it has an isocyanuric acid skeleton, so it has excellent scratch resistance, and it has an alkyl group substituent, so it has weather resistance and water vapor barrier properties. has good properties. Commercially available products are Aronix M-313 (trade name: manufactured by Toagosei Co., Ltd., isocyanuric acid EO-modified di- and triacrylate mixture, ratio of diacrylate is 30 to 40% by weight), M-315 (trade name: manufactured by Toagosei Co., Ltd. , isocyanuric acid EO-modified di- and triacrylate mixtures, the ratio of diacrylate is 3 to 13% by weight), and the like.

(1)
R="( _CH2 ) _2OCOCH = _CH2 " or "( _CH2 ) _2OH "

The content of (A) is preferably 8 to 40% by weight, more preferably 10 to 35% by weight, based on the total solid content. Sufficient curability and water vapor barrier property can be ensured by making it 8% by weight or more, and sufficient steel wool resistance can be ensured by making it 40% by weight or less. The blending ratio of (a1) and/or (a2) in (A) is preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more. By making it 50% by weight or more, a film having sufficiently low moisture permeability and excellent scratch resistance can be formed.

The nanosilica (B) used in the present invention is blended for the purpose of improving abrasion resistance and water vapor barrier properties. The average particle size is preferably 0.5 to 300 nm, more preferably 1 to 150 nm, particularly preferably 3 to 100 nm. (B) may have a single average particle size, but by blending a plurality of types of nanosilica with different average particle sizes, it is possible to highly fill the film with silica. For example, by combining two types of nanosilica (b1) with a small average particle size of 1 to 30 nm and nanosilica (b2) with a large average particle size of 35 to 100 nm, the water vapor barrier property can be further improved. .

The above (B) is surface-treated for good dispersibility in (A), and examples thereof include acryloyl group coating, alkoxy group coating, and epoxy group coating. Among these, the acryloyl group coating is preferable in that it has good reactivity with the acryloyl group of the binder (A), firmly bonds with it, and is prevented from falling off from the coating film surface after curing.

The average particle size of (b1) is preferably 1 to 30 nm, more preferably 3 to 25 nm, particularly preferably 5 to 20 nm. The average particle size of (b2) is preferably 35 to 100 nm, more preferably 35 to 70 nm, particularly preferably 40 to 60 nm. The average particle size is the median size (d=50) measured by a laser diffraction/scattering method according to JISZ8825-1.

The amount of (B) is preferably 100 to 800 parts by weight, more preferably 150 to 700 parts by weight, particularly preferably 220 to 650 parts by weight, per 100 parts by weight of (A). When the amount is 100 parts by weight or more, sufficient wear resistance can be secured, and when the amount is 800 parts by weight or less, sufficient water vapor barrier properties of the film can be secured.

The mixing ratio of (b1) and (b2) in (B) is preferably (b1):(b2) = 1:1 to 1:2, more preferably 1:1.3 to 1:1.8, 1:1.5 to 1:1.7 are particularly preferred. By setting the compounding ratio within this range, it is possible to highly fill the inside of the cured film with silica, thereby effectively improving the water vapor barrier property.

The photopolymerization initiator (C) used in the present invention generates radicals upon irradiation with ultraviolet rays, electron beams, etc., and the radicals trigger a polymerization reaction. general-purpose photopolymerization initiators such as Curability can be imparted over a wide wavelength range from the ultraviolet region to the visible light region by arbitrarily selecting the light absorption wavelength of the polymerization initiator. Specifically, 2,2-dimethoxy-1,2-diphenylethan-1-one is a benzyl ketal system, and 1-hydroxy-cyclohexyl-phenyl-ketone and 1-[4-(2- hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one is 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1 as α-aminoacetophenone -on includes acylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, either singly or in combination of two or more can be used in combination.

Among these, it is preferable to contain an α-hydroxyacetophenone-based resin that is resistant to yellowing. The content of (C) is preferably 2 to 12 parts by weight, more preferably 3 to 10 parts by weight, per 100 parts by weight of the radically polymerizable resin component.

In addition to the above, a (meth)acrylate monomer may be included as a reaction diluent in order to adjust the viscosity of the composition and improve the adhesion to the substrate. butyl (meth)acrylate, isobornyl (meth)acrylate, hydroxyethyl (meth)acrylate, (poly)ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylol propane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, diglycerin tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and the like, either alone or in combination with More than one species can be used in combination.

In addition, the encapsulating resin composition of the present invention contains antioxidants, polymerization inhibitors, ultraviolet absorbers, flame retardants, antifoaming agents, silane coupling agents, and coloring agents, if necessary, within a range that does not impair performance. It may contain additives such as agents and organic particles.

The coating agent composition of the present invention is diluted with a solvent to a solid content of 10 to 70% in order to improve coatability on substrates. Examples of solvents include alcohol solvents such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol and diacetone alcohol; ketone solvents such as acetone, methyl ethyl ketone (hereinafter referred to as MEK), methyl isobutyl ketone and cyclohexanone; Solvents, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as propylene glycol monomethyl ether (hereinafter referred to as PGM), diethyl ether and diisopropyl ether, and hydrocarbon solvents such as cyclohexane and methylcyclohexane (hereinafter MCH). and can be used singly or in combination of two or more. Among these, PGM and MEK are preferred from the viewpoint of solubility.

Substrates to which the coating agent composition of the present invention is applied include organic plastic films, such as polyester films, polyethylene films, polypropylene films, diacetylcellulose films, triacetylcellulose films (hereinafter referred to as TAC films), and acetylcellulose butyrate. Film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide Films, polyimide films, fluororesin films, nylon films, acrylic films, cycloolefin (co)polymer films, and the like can be exemplified, but by using TAC films in particular, their characteristics can be sufficiently brought out.

The method of applying the coating agent composition of the present invention is not particularly limited, and known coating methods such as spray coating, roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, wire bar, etc. Gravure printing, screen printing, offset printing, inkjet printing, etc. can be used. The film thickness of the coating is not limited, but the film thickness after curing can be exemplified from 0.5 μm to 30 μm.

After applying the coating agent composition of the present invention, it is dried at 60 to 120° C. and cured using an ultraviolet irradiation machine. 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, LED lamps, and electrodeless ultraviolet lamps. An irradiation intensity of 50 mW/cm ² to 3000 mW/cm ² and an integrated light amount of 50 to 2,000 mJ/cm ² are exemplified. The atmosphere for irradiation may be air or an inert gas such as nitrogen or argon.

Hereinafter, the present invention will be described in detail based on Examples and Comparative Examples, but these are specific examples and are not particularly limited to these. Unless otherwise specified, measurements were made under the conditions of room temperature of 25° C. and relative humidity of 65%. In addition, a compounding quantity shows a weight part.

Example 1
(A) is Ureac 1 (a reaction product of a trimer of HDI and 2HEA, trifunctional), and (b1) is PGM-AC-2140Y (trade name: manufactured by Nissan Chemical Industries, Ltd., acrylic having an average particle size of 10 to 15 nm). Modified nanosilica, PGM dispersion, solid content 47% by weight) as (b2) PGM-AC-4130Y (trade name: manufactured by Nissan Chemical Industries, acrylic-modified nanosilica having an average particle size of 40 to 50 nm, PGM dispersion, solid content 32 weight %), and Omnirad 2959 (trade name: manufactured by iGM Resins) as (C) is placed in a stirring vessel with the formulation shown in Table 1, and diluted with PGM so that the solid content becomes 40% by weight. It was stirred and degassed until it dissolved in , and the photocurable coating agent composition of Example 1 was prepared.

Examples 2-7
In addition to the materials used in Example 1, Ureac 2 (reaction product of trimer of HDI, PETA and 2HEA, pentafunctional) and M-315 (trade name: manufactured by Toagosei Co., Ltd., isocyanuric acid EO-modified A mixture of di- and triacrylates) was placed in a stirring vessel with the formulation shown in Table 1, diluted with PGM so that the solid content was 40% by weight, and stirred and degassed until uniformly dissolved. No. 7 photocurable coating composition was prepared.

Comparative Examples 1-4
In addition to the materials used in the examples, oligomers such as ureac 3 (reaction product of HDI trimer and PETA, 9 functional), ureac 4 (reaction product of HDI and PETA, hexafunctional) and ureac 5 (isophorone diisocyanate trifunctional PGM-ST (trade name: manufactured by Nissan Chemical Industries, average particle size 10 to 15 nm, PGM dispersion, solid content 30%) and IPA-ST- L (trade name: manufactured by Nissan Chemical Industries, average particle size 40 to 50 nm, IPA dispersion, solid content 30%) is put in a stirring container with the formulation shown in Table 1, and PGM is added so that the solid content becomes 40% by weight. and stirred and defoamed until uniformly dissolved to prepare photocurable coating agent compositions of Comparative Examples 1 to 4.

Evaluation items and evaluation methods

Preparation of evaluation sheet The coating agent composition obtained above was applied to TG40UL (trade name: manufactured by Fuji Film Co., Ltd., thickness 40 µm) with a bar coater so that the film thickness after curing was 2 µm. After drying at 80°C for 60 seconds, using a 4kW high-pressure mercury UV irradiation device (ECS-4011GX) inverter type manufactured by Eyegraphics, it is cured under the conditions of an output of 60mW/cm ² and an integrated amount of light of 150mJ/cm ² . let me

Moisture permeability: On top of a moisture permeable cup (manufactured by Yasuda Seiki Co., Ltd.) containing 30 g of calcium chloride, put the evaluation sheet prepared above with the coated surface facing up and attach a rubber packing and a lid. The moisture permeability was calculated by measuring the mass before and after the test for 24 hours under the condition of 90% humidity, and dividing the mass difference by the surface area of the coating film (a circle with a radius of 30 mm). A moisture permeability of 360 g/m ² ·24 hr or less was evaluated as ⊚, a moisture permeability of over 360 to 500 g/m ² ·24 hr was evaluated as ○, and a moisture permeability of over 500 g/m ² ·24 hr was evaluated as ×.

Coatability: When the above evaluation sheet was prepared, even if there were fine defects or coating unevenness, the case where there was no obvious cissing was evaluated as ◯, and the case where there were obvious cissing and defects was evaluated as X.

Abrasion resistance: A load of 500 g (contact area: 25 mmφ) was placed on #0000 steel wool and reciprocated 10 times.

Evaluation results Evaluation results are shown in Table 2.

Each coating composition of Examples gave good results in all evaluations of moisture permeability, coatability, and abrasion resistance.

On the other hand, Comparative Example 1 using surface-untreated silica was inferior in moisture permeability and abrasion resistance. The moisture permeability was poor, and none of them were suitable for the present invention.

Claims (5)

Di- to octa-functional (meth)acrylate (A) having an isocyanuric acid skeleton, surface-treated nanosilica (B), and a photopolymerization initiator (C), wherein (A) is hexamethylene diisocyanate trimer and A photocurable coating composition comprising a urethane (meth)acrylate (a1) reacted with a (meth)acrylate having an OH group and/or an isocyanuric acid EO-modified (meth)acrylate (a2). 2. The photocurable coating composition according to claim 1, wherein the amount of (B) is 100 to 800 parts by weight per 100 parts by weight of (A). 3. The method according to claim 1, wherein the (B) comprises surface-treated nanosilica (b1) having an average primary particle diameter of 1 to 30 nm and surface-treated nanosilica (b2) having an average primary particle diameter of 35 to 100 nm. Photocurable coating agent composition. 4. The photocurable coating composition according to any one of claims 1 to 3, wherein (A) is di- to penta-functional. A laminate having a cured layer of the photocurable coating agent according to any one of claims 1 to 4 on at least one side of a plastic substrate film.