JP7534880B2 - Curable composition for forming hard coat and laminate - Google Patents

Description

The present invention relates to a novel curable composition for forming a hard coat and a laminate.

Acrylic resins, including polymethyl methacrylate (PMMA), are excellent in transparency, impact resistance, and processability, and are therefore used in various molded products. In this case, a hard coat (surface protective layer) is formed on the surface of the molded acrylic resin product to increase its hardness (scratch resistance) and chemical resistance. One method for forming a hard coat is to apply a coating liquid for forming a hard coat to a pre-made molded product (post-coating method), but in recent years, insert molding or in-mold molding, in which molding and hard coat formation are performed simultaneously, are also widely used to manufacture molded products with hard coats.

For example, insert molding is a method in which a sheet-like material for forming a hard coat is loaded into the cavity of a mold, the mold is then closed, and heated and molten resin is injected to create a molded product in which the sheet-like material and the molten resin are integrated. This method has the advantage that the manufacturing process can be simplified compared to the post-coating method described above, and that a hard coat can be formed even on molded products with complex shapes, and that the hard coat can be firmly integrated into the molded product.

In this case, when the sheet material is to be used for molding, such as in insert molding, the sheet material is required to have hardness, chemical resistance, and also moldability of the sheet material itself. In order to achieve high moldability, the material itself must also have high elongation (stretchability).

As a technique for forming such a hard coat, for example, an active energy ray curable resin composition is known that contains at least (a-1) polyisocyanate, (a-2) polycarbonate polyol, and (a-3) urethane (meth)acrylate oligomer (A) which is a reaction product of hydroxyalkyl (meth)acrylate, wherein the diol constituent unit of the polycarbonate polyol (a-2) contains 1,4-butanediol, and the tensile modulus of elasticity of the cured film at 23°C when cured by irradiation with active energy is 100 to 1000 MPa (Patent Document 1).

For example, a curable composition has been proposed that includes a polyurethane compound (A) having a weight average molecular weight of 3,000 to 50,000 and a side chain radical polymerizable group equivalent of 1,000 g/mol or less, an acrylic polymer compound (B) having a weight average molecular weight of 5,000 to 50,000 and a radical polymerizable group equivalent of 600 to 3,500 g/mol, and a polymerization initiator (C), in which the polyurethane compound (A) is a reaction product of the following compounds: (a1) a compound having two hydroxyl groups and one radical polymerizable group in the molecule; (a2) a compound having one hydroxyl group and one or more radical polymerizable groups in the molecule; and (a3) a diisocyanate compound (Patent Document 2).

JP 2014-196430 A JP 2018-172638 A

When sheet-shaped materials are used for molding processes such as insert molding, they must be moldable (easy to process) so that they can be molded into the desired shape without any problems. However, when sheet-shaped materials are used to make hard coats, they must have hardness, chemical resistance, etc.

However, in general, moldability, hardness, and chemical resistance are mutually contradictory properties, and increasing moldability reduces hardness or chemical resistance, while increasing hardness or chemical resistance reduces moldability. In this respect, although a certain degree of moldability is obtained with the curable compositions of the prior art, the hardness, chemical resistance, etc. are still not sufficient, and further improvement is required.

Therefore, the main object of the present invention is to provide a curable composition capable of forming a hard coat having high hardness, chemical resistance, and high elongation.

As a result of extensive research into the problems of the prior art, the inventors discovered that the above-mentioned objectives could be achieved by adopting a composition having a specific composition, and thus completed the present invention.

That is, the present invention relates to the following curable composition for forming a hard coat and laminate.
1. A curable composition for forming a hard coat on an organic resin substrate, comprising:
(1) at least one of a) a urethane (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more, and b) a (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more (excluding urethane (meth)acrylate compounds);
(2) a (meth)acrylate compound having a radical polymerizable group equivalent of 160 g/mol or less; (3) a photopolymerization initiator; and (4) an organic solvent,
The organic solvent has the following formula (a) in Hansen three-dimensional space:
6.5≧{4(δ _1d - δ _2d ) ² + (δ _1p - δ _2p ) ² + (δ _1h - δ _2h ) ² } ^1/2 ...(a)
(wherein, δ _1d is the dispersion component of the organic resin substrate, δ _2d is the dispersion component of the organic solvent, δ _1p is the polar component of the organic resin substrate, δ _2p is the polar component of the organic solvent, δ _1h is the hydrogen bond component of the organic resin substrate, and δ _2h is the hydrogen bond component of the organic solvent.)
Fulfilling
A curable composition for forming a hard coat comprising:
2. The curable composition for forming a hard coat according to item 1, wherein the organic resin substrate has a dispersive component δ _1d of 10 to 30, a polar component δ _1p of 0 to 20, and a hydrogen bond component δ _1h of 0 to 20.
3. The curable composition for forming a hard coat according to item 1 or 2, wherein the content of the compound (2) is 5 to 20% by weight based on the solid content.
4. A laminate comprising a hard coat formed on the surface of an organic resin substrate by curing the hard coat-forming curable composition according to any one of items 1 to 3, and a diffusion layer having a thickness of 0.3 to 20 μm derived from both the organic resin substrate and the hard coat is formed between the organic resin substrate and the hard coat.
5. The laminate according to claim 4, which is used for insert molding or in-mold molding.
6. A molded product obtained by molding the laminate according to item 5. 7. A method for producing a laminate having a hard coat on a surface of an organic resin substrate, comprising the steps of:
(1) A step of forming a liquid film of the curable composition for forming a hard coat according to any one of items 1 to 3 on a surface of an organic resin substrate;
(2) A step of forming a hard coat on the organic resin substrate by subjecting the liquid film or the dried film thereof to a heat treatment and then a curing treatment.
A method for producing a laminate comprising the steps of:
8. The method according to item 7, wherein the heat treatment temperature is 70 to 120° C.

According to the present invention, it is possible to provide a curable composition capable of forming a hard coat having excellent hardness and chemical resistance as well as high elongation. Therefore, it can be suitably used as a material for forming a hard coat (surface protection layer) of a sheet-like material used in insert molding. A laminate having a hard coat formed on its surface by the curable composition of the present invention can obtain high moldability even when subjected to insert molding, etc., and can provide a molded article molded integrally with the molten resin introduced during molding. At the same time, the hard coat covering the surface of such a molded article can also achieve high hardness, chemical resistance, etc.

The curable composition of the present invention and the hard coat made from it, which have such characteristics, can be suitably used for products that require high hardness, chemical resistance, etc. on the surface, such as car navigation systems, automotive interior materials such as instrument panels, automotive exterior materials such as side mirror covers, mobile phones, touch panels, compact discs, audio equipment, and other electrical appliances.

FIG. 2 is a diagram showing an example of a layer structure of a laminate of the present invention. FIG. 1 is an image showing HSP distances in Hansen's three-dimensional space.

1. Curable composition for forming a hard coat The curable composition for forming a hard coat of the present invention (the composition of the present invention) is a curable composition for forming a hard coat on an organic resin substrate,
(1) a) a urethane (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more (hereinafter also simply referred to as a "urethane (meth)acrylate compound"), and b) at least one of a (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more (excluding a urethane (meth)acrylate compound) (hereinafter also simply referred to as a "(meth)acrylate compound");
(2) A (meth)acrylate compound having a radical polymerizable group equivalent of 160 g/mol or less (hereinafter also referred to simply as a “diffusing component”)
(3) a photopolymerization initiator; and (4) an organic solvent,
The organic solvent has the following formula (a) in Hansen three-dimensional space:
6.5≧{4(δ _1d - δ _2d ) ² + (δ _1p - δ _2p ) ² + (δ _1h - δ _2h ) ² } ^1/2 ...(a)
(wherein, δ _1d is the dispersion component of the organic resin substrate, δ _2d is the dispersion component of the organic solvent, δ _1p is the polar component of the organic resin substrate, δ _2p is the polar component of the organic solvent, δ _1h is the hydrogen bond component of the organic resin substrate, and δ _2h is the hydrogen bond component of the organic solvent.)
Fulfilling
It is characterized by:

In the present invention, unless otherwise specified, an acryloyl group or a methacryloyl group is collectively referred to as a "(meth)acryloyl group". An acryloyloxy group or a methacryloyloxy group is collectively referred to as a "(meth)acryloyloxy group". In addition, an acrylate or a methacrylate is collectively referred to as a "(meth)acrylate", and an acrylic acid or a methacrylic acid is collectively referred to as a "(meth)acrylic acid".

The term "radical polymerizable group equivalent" in the present invention refers to the molecular weight per mole of the radical polymerizable group. The radical polymerizable group is not limited as long as it is a functional group capable of radical polymerization, and examples thereof include vinyl groups, allyl groups, acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups. In particular, from the viewpoint of being able to exhibit high UV curing properties, etc., at least one of acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups is desirable.

The radical polymerizable group equivalent can be measured by a known measurement method, for example, it can be calculated by the peak ratio of double bond protons to the total protons by ¹ H-NMR, or by iodine value titration.

(1) Urethane (meth)acrylate compound or (meth)acrylate compound In the composition of the present invention, as the component (1) above, at least one of a) a urethane (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more and b) a (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more (excluding urethane (meth)acrylate compounds) is used.

These compounds are used with a radical polymerizable group equivalent of 300 g/mol or more (preferably 350 g/mol or more). This allows the formation of a hard coat that has high elongation, high hardness, high chemical resistance, etc. The upper limit of the radical polymerizable group equivalent is not particularly limited, but can be, for example, about 10,000 g/mol.

In the present invention, the urethane (meth)acrylate compound or (meth)acrylate compound may preferably have a radical polymerizable group equivalent of 300 g/mol or more and be UV-curable, and may be, for example, the compounds shown in (1-1) and (1-2) below.

(1-1) Urethane (meth)acrylate compound The urethane (meth)acrylate compound is a compound having a (meth)acryloyl group and a urethane bond, and known or commercially available compounds can be used. Compounds synthesized by known manufacturing methods can also be used. For example, a compound obtained by reacting a (meth)acrylate compound containing a hydroxyl group with a polyvalent isocyanate compound and, in some cases, a polyol compound can be suitably used. Each compound serving as a raw material will be described below.

Hydroxyl group-containing (meth)acrylate compounds Examples of hydroxyl group-containing (meth)acrylate compounds include hydroxyalkyl (meth)acrylates having an alkyl group with 1 to 16 (preferably 1 to 12) carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate; 2-hydroxyethyl (meth)acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol (meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol. Examples of the ethylenically unsaturated group include compounds having one ethylenically unsaturated group, such as mono(meth)acrylate; compounds having two ethylenically unsaturated groups, such as glycerin di(meth)acrylate and 2-hydroxy-3-(meth)acryloyl-oxypropyl(meth)acrylate; and compounds having three or more ethylenically unsaturated groups, such as pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and succinic acid-modified pentaerythritol tri(meth)acrylate.

Polyisocyanate Compounds Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane; and trimers or polymers of isocyanates (adducts, biurets, isocyanurates, and allophanates). These may be used alone or in combination of two or more.

Polyol Compound Examples of the polyol compound include aliphatic polyols (A), alicyclic polyols (B), polyether-based polyols (C), polyester-based polyols (D), polycarbonate-based polyols (E), polyolefin-based polyols (F), polybutadiene-based polyols (G), (meth)acrylic-based polyols (H), and polysiloxane-based polyols (I).

Examples of aliphatic polyols (A) include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 2-methyl-1,3-trimethylene diol, 1,5-pentamethylene diol, 1,6 -hexamethylene diol, 3-methyl-1,5-pentamethylene diol, 2,4-diethyl-1,5-pentamethylene diol, pentaerythritol di(meth)acrylate, 1,9-nonanediol, 2-methyl-1,8-octanediol, and other aliphatic alcohols containing two hydroxyl groups; sugar alcohols such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups such as glycerin, trimethylolpropane, and trimethylolethane. These can be used alone or in combination of two or more.

Examples of alicyclic polyols (B) include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecane dimethanol, and these can be used alone or in combination of two or more.

Examples of polyether polyols (C) include polyether polyols containing an alkylene structure, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, as well as random or block copolymers of these polyalkylene glycols.

Examples of polyester polyols (D) include condensation polymers of polyhydric alcohols and polycarboxylic acids; ring-opening polymers of cyclic esters (lactones); and reaction products of three components: polyhydric alcohols, polycarboxylic acids, and cyclic esters.

Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 2-methyl-1,3-trimethylene diol, 1,5-pentamethylene diol, neopentyl glycol, 1,6-hexamethylene diol, 3-methyl-1,5-pentamethylene diol, 2,4-diethyl-1,5-pentamethylene diol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), and sugar alcohols (such as xylitol and sorbitol).

Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid.

Examples of cyclic esters include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

Examples of the polycarbonate-based polyol (E) include a reaction product of a polyhydric alcohol with phosgene; a ring-opening polymer of a cyclic carbonate (such as an alkylene carbonate); and the like.
The polycarbonate polyol may be any compound having a carbonate bond in the molecule and a hydroxyl group at the end, and may have an ester bond in addition to the carbonate bond.

Examples of polyolefin polyols (F) include those having homopolymers or copolymers of ethylene, propylene, butene, etc. as a saturated hydrocarbon skeleton and having hydroxyl groups at the molecular terminals.

Examples of polybutadiene-based polyols (G) include those that have a butadiene copolymer as the hydrocarbon backbone and have hydroxyl groups at the molecular ends.

The polybutadiene polyol may be a hydrogenated polybutadiene polyol in which all or part of the ethylenically unsaturated groups contained in the structure are hydrogenated.

(Meth)acrylic polyols (H) include those having at least two hydroxyl groups in the molecule of a polymer or copolymer of (meth)acrylic acid ester. Examples of such (meth)acrylic acid ester include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

Examples of polysiloxane-based polyols (I) include dimethylpolysiloxanepolyol, methylphenylpolysiloxanepolyol, etc.

Among these polyol compounds, aliphatic polyols or alicyclic polyols are preferably used to suppress stickiness when the resin composition is cured to form a coating film. On the other hand, polyester-based polyols, polyether-based polyols, or polycarbonate-based polyols are preferably used to impart flexibility to the coating film. In addition, it is preferable to use a bifunctional (having two hydroxyl groups) polyol as the polyol compound, and a trifunctional polyol may also be used in combination.

As described above, the urethane (meth)acrylate compound used in the particularly preferred embodiment can be obtained by reacting a (meth)acrylate compound containing a hydroxyl group, a polyvalent isocyanate compound, and optionally a polyol compound at an appropriate temperature in the presence of an appropriate catalyst. The urethane (meth)acrylate compound used in the embodiment can also be obtained by reacting a polyol compound with a (meth)acrylate compound containing an isocyanate group at an appropriate temperature in the presence of an appropriate catalyst.

As such a urethane (meth)acrylate compound, a commercially available product can be used. For example, the Shiko series (UV-7000B, UV-6640B, etc.) manufactured by Nippon Synthetic Chemical Industry Co., Ltd., the Ebecryl series (EBECRYL9260, etc.) manufactured by Daicel-Allnex Corporation, and the Unidic series manufactured by DIC Corporation can be exemplified. These may be used alone or in combination of two or more kinds. By appropriately selecting or combining these urethane (meth)acrylate compounds as necessary, it is also possible to obtain a laminate having the desired hardness and elongation.

(1-2) (Meth)acrylate Compound The (meth)acrylate compound is not particularly limited as long as it is a compound other than the urethane (meth)acrylate compound and has at least an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group. These can be used alone or in combination of two or more.

In particular, in the present invention, a compound (polymer) having a (meth)acryloyl group at least on the side chain or end of the acrylic main chain can be preferably used.

The acrylic main chain may have a structure made of a polymer or copolymer containing (meth)acrylic acid or an ester thereof as a monomer. Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate, as well as epoxy (meth)acrylates.

As such a (meth)acrylate compound, commercially available products can be used. Examples include UV-curable acrylic polymers ("SMP-360A", "SMP-550A") manufactured by Kyoeisha Chemical Co., Ltd., ART CURE series ("OAP-2531", "OAP-5000", "MAP-2801", "MAP-4050", "MAP-7000") manufactured by Negami Chemical Industries Co., Ltd., and epoxy acrylates ("EBECRYL3701", "EBECRYL3708") manufactured by Daicel-Allnex Corporation. In addition to these, commercially available (meth)acrylate compounds as UV-curable compounds can also be used.

The content (solid content) of the compound (1) in the composition of the present invention is not limited, and is usually about 50 to 95% by weight, but is preferably 70 to 90% by weight. By setting it within this range, it is possible to ensure higher elongation as well as better hardness, chemical resistance, etc.

(2) (Meth)acrylate Compound as Diffusion Component The (meth)acrylate compound as the diffusion component is one having a radical polymerizable group equivalent of 160 g/mol or less (preferably 100 g/mol or less). This makes it possible to form a desired diffusion layer. In this case, the lower limit of the radical polymerizable group equivalent is not particularly limited, but can be, for example, about 80 g/mol.

In addition, in the present invention, the weight average molecular weight (hereinafter simply referred to as "molecular weight") of the (meth)acrylate compound as the diffusion component is not limited, but is usually preferably 600 or less, and more preferably 550 or less. This allows the diffusion layer to be formed more reliably. The lower limit of the molecular weight is not particularly limited, and can be, for example, about 100.

As the (meth)acrylate compound serving as the diffusion component, for example, a compound having an ethylenically unsaturated group in the molecule, such as a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloyloxy group, can be used. However, the above-mentioned urethane (meth)acrylate compounds are excluded. Here, the (meth)acrylate compound may be either monofunctional or polyfunctional. These may also be used in combination.

There are no limitations on the (meth)acrylate compound used as the diffusing component, so long as it has at least the above-mentioned radical polymerizable group equivalent. For example, one or more of pentaerythritol triacrylate (radical polymerizable group equivalent 99 g/mol, molecular weight 298), pentaerythritol tetraacrylate (radical polymerizable group equivalent 88 g/mol, molecular weight 352), 1,6-hexanediol diacrylate (radical polymerizable group equivalent 113 g/mol, molecular weight 226), ethoxylated isocyanuric acid triacrylate (radical polymerizable group equivalent 141 g/mol, molecular weight 423), trimethylolpropane triacrylate (radical polymerizable group equivalent 98 g/mol, molecular weight 296), dipentaerythritol hexaacrylate (radical polymerizable group equivalent 96 g/mol, molecular weight 578), 2-hydroxyethyl methacrylate (radical polymerizable group equivalent 130 g/mol, molecular weight 130), and acryloyl morpholine (radical polymerizable group equivalent 141 g/mol, molecular weight 141) can be used.

The content (solids content) of the diffusion component in the composition of the present invention is usually about 5 to 20% by weight, but it is particularly preferable to set it to 10 to 20% by weight. By setting it within this range, superior hardness, chemical resistance, etc. can be ensured, and high elongation can be more reliably obtained by promoting the formation of a diffusion layer.

(3) Photopolymerization initiator Examples of photopolymerization initiators include a) photoradical polymerization initiators which generate radical active species upon irradiation with light (e.g., acetylbenzene, dimethoxybenzyl, dibenzoyl, benzoin, benzophenone, benzoylbenzoic acid, bis(dimethylamino)benzophenone, bis(diethylamino)benzophenone, chlorothioxatone, ethylanthraquinone, etc.), and b) photocationic polymerization initiators which generate cationic active species (e.g., bis(4-tert-butylphenyl)iodonium hexafluorophosphate, bis(4-furan), etc.). (fluorophenyl)iodonium triflate, diphenyliodonium hexafluorophosphate, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-triazine, 4-nitrobenzenediazonium tetrafluoroborate, etc.), c) photoanionic polymerization initiators that generate anionic active species (acetophenone-O-benzoyloxime, 1,2-bis(4-methoxyphenyl)-2-oxoethyl cyclohexylcarbamate, nifedipine, etc.). These may be used alone or in combination of two or more.

As such a photopolymerization initiator, commercially available products can be used. For example, commercially available products such as the Irgacure series (BASF Japan) can be used. More specifically, "Irgacure 907" (2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one), "Irgacure TPO" (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide), etc. can be used.

The content (solids content) of the photopolymerization initiator in the composition of the present invention can be set appropriately depending on the type of polymerization initiator used, but it is usually about 2 to 8% by weight, and preferably 3 to 5% by weight. By setting it within this range, a coating film excellent in hardness, chemical resistance, and elongation can be obtained.

(4) Organic Solvent The organic solvent is represented by the following formula (a) in Hansen's three-dimensional space:
6.5≧{4(δ _1d - δ _2d ) ² + (δ _1p - δ _2p ) ² + (δ _1h - δ _2h ) ² } ^1/2 ...(a)
(wherein, δ _1d is the dispersion component of the organic resin substrate, δ _2d is the dispersion component of the organic solvent, δ _1p is the polar component of the organic resin substrate, δ _2p is the polar component of the organic solvent, δ _1h is the hydrogen bond component of the organic resin substrate, and δ _2h is the hydrogen bond component of the organic solvent.)
By using such an organic solvent, in addition to the action of the diffusing component, a desired diffusion layer can be more reliably formed.

In the three-dimensional Hansen space as shown in FIG. 2, the vector A of the organic resin substrate and the vector B of the organic solvent can be shown by plotting the dispersion component (δ _d ), polar component (δ _p ) and hydrogen bond component (δ _h ) of the organic resin substrate and the organic solvent, respectively. The lengths L _A and L _B of these vectors are the Hildebrand solubility parameters in the organic resin substrate and the organic solvent. The above formula (a) is the distance D (hereinafter also referred to as the "HSP distance") between the tips (arrows) of both vectors A and B, and the shorter the distance D, the higher the solubility. In the present invention, by controlling such an HSP distance to 6.5 or less (preferably 6 or less), a predetermined diffusion layer can be effectively formed in the laminate.

The lower limit of the HSP distance is not particularly limited and can usually be set to 0, but if high transparency is required for the laminate, for example, it is preferable to set it to about 0.5, and more preferably to set it to about 1.

Organic resin substrates generally available on the market have a dispersion component of about 10 to 30, a polar component of about 0 to 20, and a hydrogen bond component of about 0 to 27, so an organic solvent that gives an HSP distance of 6.5 or less can be appropriately selected according to the organic resin substrate used (at least the resin that constitutes the surface that forms the diffusion layer). Therefore, in the present invention, for example, an organic resin substrate with a dispersion component of 10 to 30 (preferably 15 to 30), a polar component of 0 to 20 (preferably 3 to 17), and a hydrogen bond component of 0 to 20 (preferably 1 to 18) can also be suitably used.

The dispersion component (δ _d ), polar component (δ _p ) and hydrogen bond component (δ _h ) of the organic solvent and organic resin substrate in the present invention may be either a literature value or an actual measurement value, but if the two are significantly different, it is desirable to adopt the actual measurement value. The actual measurement value can be performed according to a known method. For example, any of a method of extracting data from a database of a commercially available HSP calculation software, or a method of obtaining a dissolved sphere from a solubility test of an organic resin substrate and obtaining the center coordinates can be adopted. In addition, if an error occurs in each numerical value, the smallest value may be adopted.

The organic solvents that can be used are not limited as long as they satisfy the above conditions, and can be selected from one or more of the following organic solvents as appropriate: ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran, propylene glycol monomethyl ether acetate, and diethylene glycol dimethyl ether; aromatic solvents such as toluene and xylene; and alcohol solvents such as methanol, ethanol, 1-propanol, isopropyl alcohol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

When two or more organic solvents are mixed, the dispersive components, polar components, and hydrogen bond components are calculated by multiplying the dispersive components, polar components, and hydrogen bond components of each organic solvent by their volume fractions, and the total values obtained are the dispersive components, polar components, and hydrogen bond components of the mixed solvent.

When an organic solvent is used, the amount used is not limited, and may be set appropriately depending on the types of components used, the desired viscosity, etc., so that the solid content of the composition of the present invention is within the range of about 5 to 90% by weight. For example, when the composition of the present invention is used in the form of a paste, the solid content may be set to a relatively large amount.

(5) Form of the composition of the present invention The composition of the present invention is usually in a liquid form. In this case, the viscosity (20°C) can be appropriately set according to the desired thickness of the hard coat, for example, about 1 to 500 mPa·s, but is not limited thereto.

(6) Preparation of the composition of the present invention The composition of the present invention can be prepared by uniformly mixing the above-mentioned components. The order of mixing is not particularly limited, and any order can be adopted. Mixing can be carried out using a known or commercially available device such as a mixer or kneader. The atmosphere in which the components are mixed is also not particularly limited, and usually the components can be mixed at room temperature and pressure.

In the composition of the present invention, some or all of the components constituting the composition of the present invention may be dissolved in the organic solvent, or may be dispersed without being dissolved. In particular, in the present invention, it is desirable to have a solution in which at least the organic components are dissolved in the organic solvent.

(7) Use of the composition of the present invention By curing a coating film of the composition of the present invention, a hard coat consisting of a desired cured film can be formed. In particular, a laminate including a diffusion layer can be produced by using an organic resin substrate as a base, applying the composition of the present invention thereto, and curing the applied composition. Details of this will be described in "2. Laminate and its manufacturing method" below.

2. Laminate and its manufacturing method (A) Laminate The present invention encompasses a laminate in which a hard coat formed by curing the hard coat-forming curable composition according to any one of claims 1 to 3 is formed on the surface of an organic resin substrate, and a diffusion layer having a thickness of 0.3 to 20 μm derived from both layers is formed between the organic resin substrate and the hard coat (laminate of the present invention).

An example of the layer structure of the laminate of the present invention is shown in FIG. 1. In the laminate of the present invention 10, a hard coat 12 is formed on (above) the surface of an organic resin substrate 11. That is, the hard coat 12 is formed so as to be exposed on the outermost surface of the laminate. A diffusion layer 13 derived from both layers is formed as an intermediate layer between the two. Here, "derived from both layers" means that the components contained in the organic resin substrate 11 and the components contained in the hard coat 12 are mixed by diffusion. For example, a layer formed by diffusion occurring at the interface between the organic resin substrate 11 and the composition of the present invention applied directly onto the substrate can be exemplified.

The organic resin substrate is not particularly limited, and examples thereof include substrates such as acrylic resins (polymethylmethacrylate, etc.), olefin resins (polyethylene, polypropylene, etc.), polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polyamide resins (nylon, etc.), polycarbonate resins, polyurethane resins, vinyl resins (vinyl chloride resins, vinyl acetate resins, etc.), fluorine resins, silicone resins, and mixtures thereof. In particular, when transparency is required for the laminate of the present invention, it is preferable to use a transparent organic resin substrate. The degree of transparency can be appropriately set depending on the application of the laminate.

In the present invention, for example, an acrylic resin substrate can be suitably used. The acrylic resin is not limited as long as it is a polymer containing at least one of (meth)acrylic acid and its derivatives as a monomer unit. Examples of the derivative include esters, alkali salts, nitriles, amides, and the like. Examples of the esters include esters in which R in the COOR of (meth)acrylic acid is a methyl group, an ethyl group, a butyl group, a glycidyl group, a hydroxyethyl group, a hydroxypropyl group, an ethylhexyl group, and the like. Examples of the alkali salts include potassium salts and sodium salts of (meth)acrylic acid. Examples of the nitriles include acrylonitrile and methacrylonitrile. Examples of the amides include (meth)acrylic acid amide. Specific examples of acrylic resins composed of these monomers include polymethyl methacrylate (PMMA), and the like.

In addition, the acrylic resin may be one that contains an acrylic resin as the main component (usually 50% by weight or more, particularly 80% by weight or more in the acrylic resin substrate) as long as it does not interfere with the effects of the present invention, and may be a mixed resin with other resin components, a polymer alloy, etc., to that extent. The other resin components are not particularly limited, and examples include various resin components such as polyolefins (polyethylene, polypropylene, etc.), polyurethanes, polyesters, polyamides, polystyrenes, silicone resins, polyvinyl alcohols, fluororesins, and polyvinyl chloride. Examples of such resins include acrylonitrile butadiene styrene resins (ABS resins), acrylonitrile styrene resins (AS resins), etc.

Furthermore, the organic resin substrate may contain other additives as long as they do not impair the effects of the present invention. Examples of additives include plasticizers, fillers, colorants (dyes, pigments), preservatives, matting agents, antistatic agents, flame retardants, UV absorbers, light stabilizers, antifouling agents, antiblocking agents, antibacterial agents, antioxidants, etc.

The organic resin substrate may be transparent, translucent, or opaque. For example, if it is transparent or translucent, the printed layer is laminated on the base, making the printed layer visible.

The shape of the organic resin substrate is not limited, but it is generally desirable that the organic resin substrate is in the form of a sheet (plate) in terms of a shape suitable for molding. In this case, the sheet-shaped organic resin substrate may contain another layer on the surface opposite to the surface to which the composition of the present invention is applied. The other layer may be, for example, a resin layer, a metal layer, etc., but from the viewpoint of moldability (for example, moldability in insert molding or in-mold molding), one or more thermoplastic resin layers can be preferably used. Examples of thermoplastic resins include polyolefins (polyethylene, polypropylene, etc.), polyurethane, polycarbonate, polyester, polyamide, polystyrene, silicone resins, fluororesins, polyvinyl alcohol, polyvinyl chloride, etc. In this way, a laminate formed by laminating a specific organic resin layer and another resin layer can also be used as the organic resin substrate.

The thickness of the organic resin substrate may be, for example, about 0.05 to 1 mm, as long as the desired formability and other properties are ensured, but is not limited to this. In particular, when the laminate as described above is used as the organic resin substrate, the thickness of the acrylic resin layer to which the composition of the present invention is applied is not limited, but is desirably about 0.1 to 0.5 mm from the viewpoint of more reliably forming the desired diffusion layer.

The diffusion layer is formed between the organic resin substrate and the hard coat. The diffusion layer originates from the organic resin substrate and the hard coat, and exists as an intermediate buffer layer between the two layers. The diffusion layer is formed at the interface between the organic resin substrate and the composition of the present invention when the composition of the present invention is applied to the organic resin substrate, and is formed as a region containing both the components of the organic resin substrate and the components of the composition of the present invention. By forming such a diffusion layer, the organic resin substrate and the hard coat are integrally configured, and excellent elongation can be imparted to the laminate, resulting in excellent moldability. This makes it possible to suppress or prevent cracks that may occur during molding.

The thickness of the diffusion layer is usually about 0.3 to 20 μm, and preferably 1 to 10 μm. If the thickness is less than 0.3 μm, the cushioning effect will be low and the elongation will also be low. On the other hand, if the thickness exceeds 20 μm, there is a risk that the coating performance such as hardness and chemical resistance will decrease.

The thickness of the diffusion layer can be measured from the reflectance spectrum of light of a certain wavelength using a commercially available film thickness meter, but it can also be measured using other analytical methods such as a scanning electron microscope.

The hard coat layer is formed by curing the composition of the present invention. As shown in Figure 1, it is exposed on the outermost surface of the laminate and functions as a protective layer for the laminate.

The hard coat layer may be transparent, translucent, or opaque. For example, if the hard coat layer is transparent or translucent, the printed layer can be visible by laminating the printed layer on the base.

The thickness of the hard coat layer can be set appropriately depending on the desired hardness, moldability, etc., but is usually set to 2 to 20 μm, and preferably to 2.5 to 10 μm. If it is less than 2 μm, poor curing will occur due to oxygen inhibition, and if it exceeds 20 μm, poor curing may occur deep in the coating film.

(B) Manufacturing Method of Laminate The laminate of the present invention can be suitably manufactured, for example, by the following manufacturing method. That is, a method for manufacturing a laminate having a hard coat on a surface of an organic resin substrate, comprising the steps of:
(1) a step of forming a liquid film of the composition of the present invention on the surface of an organic resin substrate (coating step);
(2) A step of forming a hard coat on the resin substrate by subjecting the liquid film or the dried film thereof to a heat treatment and then a curing treatment (hard coat forming step).
Including,
The laminate of the present invention can be produced by the method characterized by the above.

In the coating step, a liquid film is formed on the surface of the organic resin substrate using the composition of the present invention. Since the organic solvent contained in the composition of the present invention has a property of easily dissolving the organic resin substrate, the formation of the liquid film can swell the surface of the organic resin substrate, thereby accelerating the formation of a diffusion layer.

The method for forming the liquid film is not particularly limited, and can be appropriately performed using known coating methods such as the doctor blade method, bar coating method, dipping method, air spray method, roller brush method, roller coater method, etc.

The amount of liquid film applied may be, for example, an amount that will result in the desired thickness of the cured film, and can usually be appropriately set so that the thickness of the resulting cured film is within the range of about 1 to 50 μm (preferably within the range of 3 to 15 μm).

The liquid film should be held for a time sufficient for the surface of the organic resin substrate to swell, and can be set within a range of, for example, 5 to 30 minutes, but is not limited to this. In this case, the holding temperature should be room temperature (especially about 10 to 35°C).

Hard Coat Forming Step In the hard coat forming step, the liquid film or the dried film thereof is heat-treated and then cured to form a hard coat on the resin substrate.

The subject of the heat treatment is usually a liquid film of the composition of the present invention, but it may also be a dried film that has been naturally dried or dried at a temperature of 50°C or less. From the standpoint of production efficiency, etc., it is desirable to subject the liquid film to the heat treatment.

In the heat treatment, the liquid film can be dried and the formation of a diffusion layer can be promoted. The heat treatment temperature (oven temperature) can be appropriately set within the range of about 70 to 120°C depending on the boiling point of the organic solvent contained in the composition of the present invention. If the temperature is below 70°C, the coating components are likely to be insufficiently diffused or the organic solvent is likely to be insufficiently dried, and if the temperature exceeds 120°C, the organic resin substrate may soften, resulting in a deterioration in the film appearance. In particular, in the present invention, it is preferable to set the heat treatment temperature to a temperature lower than the boiling point of the organic solvent contained in the composition of the present invention used. Based on the above heat treatment temperature, it is preferable to use an organic solvent whose boiling point is in the range of 75 to 200°C (preferably 100 to 160°C).

After heat treatment, the coating is cured. This fixes the diffusion layer formed between the organic resin substrate and the hard coat.

The method for curing the coating is not particularly limited, but a curing method using radiation (active energy rays) is particularly suitable. Any radiation may be used as long as it has an energy level sufficient to cleave the photopolymerization initiator. Examples of radiation include electromagnetic radiation and particle radiation, and it is particularly preferable to use ultraviolet light, infrared light, visible light, far-infrared light, etc.

In the present invention, ultraviolet light can be preferably used, in particular because it allows for relatively easy curing. In addition, when irradiating ultraviolet light, the light source is not limited, and examples include high-pressure mercury lamps, iron-doped metal halide lamps, gallium lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet lasers, LEDs, etc. Therefore, curing can be performed using publicly known or commercially available devices equipped with these.

When ultraviolet light is irradiated, for example, ultraviolet light having a wavelength range of about 100 to 400 nm, an illuminance of 80 to 1000 mW/cm ² , and an energy of an integrated light quantity of 100 to 5000 mJ/cm ² can be irradiated, but is not limited thereto. The ultraviolet light irradiation can be carried out using a known or commercially available UV irradiation device.

The temperature conditions for UV irradiation are not particularly limited, but should usually be within the range of 100°C or less. Therefore, for example, it can be suitably carried out at around room temperature (approximately 10 to 40°C).

(C) Use of the Laminate The laminate of the present invention can be suitably used as a molding material for molding a molded article having a hard coat (surface protective layer) for protecting the surface of the molded article.

The molding method is not particularly limited, but since the laminate of the present invention is usually a sheet-like product, a method suitable for molding and processing a sheet-like product can be suitably adopted. In other words, it is preferable to adopt a molding method in which the sheet-like laminate is closely attached to a mold. In particular, it can be suitably used as a sheet-like material to be loaded into a mold in insert molding or in-mold molding. This makes it possible to manufacture a molded product in which the hard coat of the laminate of the present invention is disposed as the outermost surface layer.

Since such molded products have a hard coat made of the laminate of the present invention on the surface as a surface protective layer, they can exhibit high hardness (scratch resistance), chemical resistance, etc. Furthermore, since the laminate of the present invention has excellent moldability (high elongation), the occurrence of defects such as cracks on the hard coat surface can be effectively suppressed even after molding, resulting in a good appearance.

The following examples and comparative examples are presented to more specifically explain the features of the present invention. However, the scope of the present invention is not limited to the examples.

Example 1
A curable composition (coating liquid) was prepared by uniformly mixing each component shown in Table 1. Next, the coating liquid was applied to the PMMA surface of a multilayer film (thickness about 0.3 mm) made of polycarbonate (PC)/polymethyl methacrylate (PMMA) as an organic resin substrate using a bar coater (bar coater No. 8). This was placed in an oven and heat-treated at 80°C for 3 minutes to remove the organic solvent, resulting in a dried coating film. Then, the coating film was irradiated with ultraviolet light (illuminance: 500 mW/cm ² , accumulated light amount: 500 mJ/cm ² ) to perform UV curing. In this way, a laminate in which a hard coat was formed on an acrylic resin substrate was obtained. The unit of the content of each component in Table 1 is "wt%". The content of the resin in Table 1 represents the content of the active ingredient.

Examples 2 to 3, Example 6, Comparative Examples 1 to 2, and Comparative Example 4
A coating solution having the composition shown in Table 1 was prepared in the same manner as in Example 1, except that the coating solution was prepared using the composition shown in Table 1, and a laminate was then produced.

Example 4
A coating liquid was prepared in the same manner as in Example 1, except that the heat treatment conditions were 90° C. and 30 minutes, and a laminate was then produced.

Example 5
A coating liquid was prepared in the same manner as in Example 1, except that the heat treatment conditions were 100° C. and 30 minutes, and a laminate was then produced.

Comparative Example 3
A coating liquid was prepared in the same manner as in Example 1, except that the bar coater No. 8 was replaced with the bar coater No. 3, and a laminate was then produced.

Test Example 1
The laminates obtained in each of the Examples and Comparative Examples were examined for the following items. The results are also shown in Table 1. Table 2 shows the HSP distances of the organic resin substrate and the organic solvent, together with the values of the dispersion component (D component), polar component (P component), and hydrogen bond component (H component) of the organic resin substrate and the organic solvent.

(1) Coating thickness and diffusion layer thickness Using a film thickness measurement system "F20" (FILMETRICS Co., Ltd.), the thickness was measured from the reflectance spectrum of light having a certain wavelength. Here, "coating thickness" refers to the thickness of the hard coat 12 in FIG. 1.

(2) Appearance The coating film was visually inspected for abnormalities. If the surface was uneven like the skin of an orange or if there was any cissing, it was judged as "abnormal." If no such abnormalities were found, it was judged as "normal."

(3) Elongation A tensile test was carried out at a temperature of 130° C., and the elongation rate was measured until cracks were visually observed on the hard coat surface. A test piece of 5 mm×100 mm was cut out from each laminate, and the test was carried out at a chuck distance of 50 mm and a tensile speed of 600 mm/min.

(4) Pencil Hardness The hardness of the hard coat surface (coating film made from the coating liquid) was measured in accordance with Japanese Industrial Standard JIS-6500-5-4.

(5) Chemical resistance A commercially available sunscreen cream (product name "Neutrogena" manufactured by Johnson & Johnson, SPF 100) was applied to the hard coat surface, and after leaving it to stand for 30 minutes at a temperature of 80°C, the sunscreen cream was wiped off with a dry cloth and the hard coat surface was visually observed to see how much it had changed from transparent to white. Those that showed no change (hard coat remained transparent) were marked with "○", those that showed partial whitening were marked with "△", and those that showed whitening over the entire surface were marked with "×".

The meanings of the abbreviations in Tables 1 and 2 are as follows:
a) UV-7000B: Product name "Shikoh UV-7000B" Mitsubishi Chemical Corporation, urethane acrylate (number of acrylate functional groups: 2 to 3), radical polymerizable group equivalent: 1400 g/mol
b) SMP-360AP: Product name "SMP-360AP" Kyoeisha Chemical Co., Ltd., acrylic polymer, radical polymerizable group equivalent: 360 g/mol, solid content 50% (dilution solvent: propylene glycol monomethyl ether)
c) M-306: Product name "Aronix M-306" Toagosei Co., Ltd., mixture of pentaerythritol triacrylate (number of acrylate functional groups: 3, radical polymerizable group equivalent: 99) and pentaerythritol tetraacrylate (number of acrylate functional groups: 4, radical polymerizable group equivalent: 88) d) Irgacure 907: Product name "Irgacure 907" BASF Japan Ltd., photopolymerization initiator e) DMF: N,N dimethylformamide (boiling point 153.0°C), DuPont Co., Ltd. f) AcOBu: butyl acetate (boiling point 126.3°C), Godo Co., Ltd. g) MEK: methyl ethyl ketone (boiling point 79.53°C), Kanto Chemical Co., Ltd. h) PGM: propylene glycol monomethyl ether (boiling point 120°C)

As is clear from the results in Table 1, in each Example, since the diffusion layer has a constant thickness, it is possible to obtain high hardness as well as high elongation.
In contrast, in Comparative Example 1, the thickness of the diffusion layer was insufficient, so the elongation was insufficient. In Comparative Example 2, the coating film components did not contain a resin component having flexibility, so the elongation was significantly insufficient. In Comparative Example 3, the coating film layer was less than 2 μm, so curing failure occurred, and the pencil hardness and chemical resistance were insufficient. In Comparative Example 4, since no diffusion component was blended, mutual diffusion did not occur at the coating film/substrate interface, and the desired diffusion layer was not formed, so the elongation was insufficient.

Claims (5)

1. A curable composition for forming a hard coat on an organic resin substrate, comprising:
(1) at least one of a) a urethane (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more, and b) a (meth)acrylate compound having a radical polymerizable group equivalent of 300 g/mol or more (excluding urethane (meth)acrylate compounds);
(2) a (meth)acrylate compound having a radical polymerizable group equivalent of 160 g/mol or less; (3) a photopolymerization initiator; and (4) an organic solvent,
The organic solvent has the following formula (a) in Hansen three-dimensional space:
6.5≧{4(δ _1d - δ _2d ) ² + (δ _1p - δ _2p ) ² + (δ _1h - δ _2h ) ² } ^1/2 ...(a)
(wherein, δ _1d is the dispersion component of the organic resin substrate, δ _2d is the dispersion component of the organic solvent, δ _1p is the polar component of the organic resin substrate, δ _2p is the polar component of the organic solvent, δ _1h is the hydrogen bond component of the organic resin substrate, and δ _2h is the hydrogen bond component of the organic solvent.)
Fulfilling
The laminate is characterized in that a hard coat formed by curing the curable composition is formed on the surface of an organic resin substrate, and a diffusion layer having a thickness of 0.3 to 20 μm derived from both the organic resin substrate and the hard coat is formed between the organic resin substrate and the hard coat. 2. The laminate according to claim 1, wherein the organic resin substrate has a dispersive component δ _1d of 10-30, a polar component δ _1p of 0-20, and a hydrogen bonding component δ _1h of 0-20. 3. The laminate according to claim 1, wherein the content of the compound (2) in the curable composition is 5 to 20% by weight based on the solid content. The laminate according to claim 1, which is used for insert molding or in-mold molding. A molded article obtained by molding the laminate according to claim 4.