JP2022077715A - Urethane(meth)acrylate-containing composition, photocurable resin composition, cured product thereof, hard coat agent, and substrate with hard coat layer - Google Patents

Abstract

To provide a (meth)acrylate composition from which a photocurable resin composition that has a low shrinkage during curing and can form a cured product having high hardness and less occurrence of curl and crack can be obtained.SOLUTION: Provided is an urethane(meth)acrylate-containing composition, which is a composition containing an urethane(meth)acrylate obtained by reacting a dipentaerythritol (meth)acrylate mixture (A) and a polyisocyanate compound (B) having three or more isocyanate groups, or the dipentaerythritol (meth)acrylate mixture (A) and the polyisocyanate compound (B) and a diisocyanate compound (C), and in which the urethane (meth)acrylate has four or more (meth)acryloyl groups in one molecule and has a weight average molecular weight of 5,000 or more, and the hydroxyl value of the dipentaerythritol (meth)acrylate mixture (A) is 121 to 150 mgKOH/g.SELECTED DRAWING: None

Description

The present invention relates to a urethane (meth) acrylate-containing composition, a photocurable resin composition, a cured product thereof, a hardcoat agent, and a substrate with a hardcoat layer.

The photocurable resin composition containing (meth) acrylate is used for a hard coat or the like.
Patent Document 1 describes at least two kinds selected from the group consisting of dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. A resin composition containing a reaction product of a dipentaerythritol poly (meth) acrylate mixture or the like having a hydroxyl value of 80 to 120 mgKOH / g and a polyisocyanate compound containing a diisocyanate compound has been proposed. According to this resin composition, it is said that it is excellent in hardness and scratch resistance, is less likely to cause curl and cracks, and gives a cured film even better than that known.

International Publication No. 2010/146801

However, the cured film of the resin composition of Patent Document 1 may not have sufficient hardness and may not sufficiently suppress the occurrence of curls and cracks.

INDUSTRIAL APPLICABILITY The present invention provides a urethane (meth) acrylate-containing composition capable of forming a photocurable resin composition capable of forming a cured product having a low shrinkage rate during curing and having high hardness and less likely to cause curling or cracking, and a shrinkage rate during curing. A photocurable resin composition and its cured product that can form a cured product with low hardness and low curl and cracks, and a hard coat layer with low shrinkage and high hardness and low curl and cracks. It is an object of the present invention to provide a hard coating agent capable of forming a coating agent and a substrate with a hard coating layer using the same.

The present invention has the following aspects.
[1] A dipentaerythritol (meth) acrylate mixture (A) and a polyisocyanate compound (B) having three or more isocyanate groups, or the dipentaerythritol (meth) acrylate mixture (A) and the polyisocyanate. A composition containing a urethane (meth) acrylate obtained by reacting a compound (B) with a diisocyanate compound (C).
The urethane (meth) acrylate has four or more (meth) acryloyl groups in one molecule, and has a weight average molecular weight of 5,000 or more.
A urethane (meth) acrylate-containing composition having a hydroxyl value of 121 to 150 mgKOH / g of the dipentaerythritol (meth) acrylate mixture (A).
[2] The dipentaerythritol (meth) acrylate mixture (A) is a dipentaerythritol di (meth) acrylate, a dipentaerythritol tri (meth) acrylate, a dipentaerythritol tetra (meth) acrylate, or a dipentaerythritol penta (meth) acrylate. The urethane (meth) acrylate-containing composition according to the above [1], which comprises at least two kinds selected from the group consisting of acrylate and dipentaerythritol hexa (meth) acrylate.
[3] The polyisocyanate compound (B) is a trimeric of isophorone diisocyanate, a trimeric of 1,3-bis (isocyanatomethyl) cyclohexane, a trimeric of hexamethylene diisocyanate, and a trimethylhexamethylene diisocyanate. The urethane (meth) acrylate-containing composition according to the above [1] or [2], which is at least one selected from the group consisting of the trimer of the above.
[4] The diisocyanate compound (C) is at least one selected from the group consisting of isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. The urethane (meth) acrylate-containing composition according to any one of [1] to [3].
[5] A photocurable resin composition containing the urethane (meth) acrylate-containing composition according to any one of the above [1] to [4] and a photopolymerization initiator.
[6] A cured product of the photocurable resin composition of the above [5].
[7] A hard coat agent comprising the photocurable resin composition of the above [5].
[8] A base material with a hard coat layer having a hard coat layer made of a cured product of the hard coat agent of the above [7] on the surface of the base material.

According to the present invention, a urethane (meth) acrylate-containing composition capable of forming a photocurable resin composition capable of forming a cured product having a low shrinkage rate during curing and having high hardness and less likely to cause curling or cracking can be obtained. A photocurable resin composition and its cured product that can form a cured product with a low shrinkage rate and high hardness that does not easily cause curls and cracks. It is possible to provide a hard coating agent capable of forming a coating layer and a substrate with a hard coating layer using the same.

As used herein, the "urethane (meth) acrylate" is a (meth) acrylate having one or more urethane bonds.
A "(meth) acrylate" is a compound having one or more (meth) acryloyl groups.
A "poly (meth) acrylate" is a compound having two or more (meth) acryloyl groups.
"(Meta) acryloyl group" is a general term for acryloyl group and methacryloyl group.
The "weight average molecular weight" (hereinafter, also referred to as "Mw") is a standard polystyrene-equivalent value measured by gel permeation chromatography (hereinafter, also referred to as "GPC").
The "hydroxyl value" is the amount of potassium hydroxide required to acetylate the hydroxyl group in the sample and neutralize the acetic acid used for acetylation, expressed in mg with respect to 1.0 g of the sample. , A measure of the content of hydroxyl groups in the sample. The hydroxyl value is measured using the neutralization titration method specified in JIS K 0070: 1992.
Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[Urethane (meth) acrylate-containing composition]
The urethane (meth) acrylate-containing composition of the present invention (hereinafter, also referred to as “composition (a)”) is also referred to as a dipentaerythritol (meth) acrylate mixture (A) (hereinafter, also referred to as “component (A)”). ) And the polyisocyanate compound (B) having three or more isocyanate groups (-N = C = O) (hereinafter, also referred to as "component (B)"), or the component (A) and (B). It is obtained by reacting a component with a diisocyanate compound (C) (hereinafter, also referred to as “component (C)”), and contains urethane (meth) acrylate.

The component (A) includes dipentaerythritol (meth) acrylate having one or more hydroxyl groups (hereinafter, also referred to as “hydroxyl-containing dipentaerythritol (meth) acrylate”), which will be described in detail later. When the component (A) and the component (B) are reacted, and if necessary, the component (C) is reacted, the hydroxyl group of the hydroxyl group-containing dipentaerythritol (meth) acrylate and the isocyanate group of the component (B) and the component (C) are formed. Urethane bonds are formed to form urethane (meth) acrylates.

In the composition (a), a part of the component (A) may remain without reacting with the component (B) or the component (C). For example, when the component (A) contains a dipentaerythritol (meth) acrylate having no hydroxyl group, that is, a dipentaerythritol hexa (meth) acrylate (hereinafter, also referred to as “DPH (M) A”), DPH (. Since M) A does not react with the component (B) or the component (C), the composition (a) contains DPH (M) A.

In the composition (a), the component (B) or a part of the component (C) may remain without reacting with the component (A), but the substance of the component (B) and the component (C) It is preferable that all of them react with the component (A). In this case, the (meth) acrylate composition is composed of only urethane (meth) acrylate, or a mixture of urethane (meth) acrylate and the component (B) or the component (A) that has not reacted with the component (C). Will be.

<Ingredient (A)>
The component (A) consists of at least two dipentaerythritol (meth) acrylates.
Dipentaerythritol (meth) acrylate is a compound in which one or more of the six hydroxyl groups of dipentaerythritol is substituted with a (meth) acryloyloxy group. Specifically, dipentaerythritol mono (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, DPH (M) A can be mentioned.
Among the above, the dipentaerythritol (meth) acrylate other than DPH (M) A is a hydroxyl group-containing dipentaerythritol (meth) acrylate. Therefore, the component (A) contains at least one hydroxyl group-containing dipentaerythritol (meth) acrylate.

The component (A) may contain at least two kinds of dipentaerythritol poly (meth) acrylates from the viewpoint of excellent hardness and scratch resistance of the cured product of the photocurable resin composition containing the present composition (a). preferable. Specifically, from dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate. It is preferable to include at least two kinds selected from the group.

The hydroxyl value of the component (A) is 121 to 150 mgKOH / g, preferably 121 to 140 mgKOH / g. When the hydroxyl value is at least the above lower limit value, the curable resin composition containing the present composition (a) is excellent in flexibility and processability, and when it is at least the above upper limit value, the hardness of the cured product is excellent. , Excellent scratch resistance.
The hydroxyl value of the component (A) can be adjusted by the type and ratio of the dipentaerythritol (meth) acrylate constituting the component (A).

<Ingredient (B)>
The component (B) may be a compound having three or more isocyanate groups in the molecule, and examples thereof include an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, and an aromatic polyisocyanate compound.

Examples of the aliphatic polyisocyanate compound include multimers, biurets and adducts of the aliphatic diisocyanate compounds.
Examples of the aliphatic diisocyanate compound include hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, methylene diisocyanate, ethylene diisocyanate, butylene diisocyanate, propylene diisocyanate, octadecylene diisocyanate, 1,4-tetramethylene diisocyanate, and 1,6-. Hexamethylene diisocyanate and 1,10-decamethylene diisocyanate can be mentioned.
Examples of the multimer include a trimer. The trimer is also referred to as a nurate form or an isocyanate.

Examples of the alicyclic polyisocyanate compound include multimers, biurets and adducts of alicyclic diisocyanate compounds.
Examples of the alicyclic diisocyanate compound include 4,4'-methylenebis (cyclohexylisocyanate), methylcyclohexane-2,4 (or 2,6) -diisocyanate, isophorone diisocyanate, and 1,3-bis (isocyanatomethyl) cyclohexane. , Dimerate diisocyanate, 1,3-cyclohexylene diisocyanate, 4,4'-methylene-bis (cyclohexyl isocyanate).
Examples of the multimer include a trimer.

Examples of the aromatic polyisocyanate compound include multimers of aromatic diisocyanate compounds, biuret and adduct compounds, and triphenylmethane triisocyanate.
Examples of the aromatic diisocyanate include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, xylene diisocyanate, dianisidine diisocyanate, phenyl diisocyanate, halogenated phenyl diisocyanate, 1,5-naphthalenedi isocyanate, and polymethylene polyphenylenedi isocyanate. , Naphthalene diisocyanate, 3-phenyl-2-ethylene diisocyanate, cumene-2,4-diisocyanate, 4-methoxy-1,3-phenylenediisocyanate, 4-ethoxy-1,3-phenylenediocyanate, 2,4'-diisocyanate diphenyl ether , 5,6-dimethyl-1,3-phenylenediocyanate, 4,4'-diisocyanate diphenyl ether, benzidine diisocyanate, 9,10-anthrusene diisocyanate, 4,4'-diisocyanate benzyl, 3,3'-dimethyl-4, Examples thereof include 4'-diisocyanate diphenylmethane, 2,6-dimethyl-4,4'-diisocyanate diphenyl, 3,3'-dimethoxy-4,4'-diisocyanate diphenyl, 1,4-anthlasene diisocyanate and phenylenediisocyanate.
Examples of the multimer include a trimer.

As the component (B), one type may be used alone, or two or more types may be used in combination.
As the component (B), a trimer of isophorone diisocyanate, a trimer of 1,3-bis (isocyanatomethyl) cyclohexane, a trimer of hexamethylene diisocyanate, and a trimethylhexamethylene are used because of their excellent weather resistance. At least one selected from the group consisting of diisocyanate trimers is preferred.

<Ingredient (C)>
The component (C) may be a compound having two isocyanate groups in the molecule, and examples thereof include an aliphatic diisocyanate compound, an alicyclic diisocyanate compound, and an aromatic diisocyanate compound.
Specific examples of the aliphatic diisocyanate compound, the alicyclic diisocyanate compound, and the aromatic diisocyanate compound include the same as described above. Each of the above diisocyanate compounds may be an allophanate.

As the component (C), one type may be used alone, or two or more types may be used in combination.
As the component (C), at least one selected from the group consisting of isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate from the viewpoint of better weather resistance. Is preferable.

The ratio of the component (B) to the total of the component (B) and the component (C) is preferably 80% by mass or more, more preferably 85% by mass or more, further preferably 90% by mass or more, and 100% by mass. May be good. When the ratio of the component (B) is equal to or greater than the lower limit, shrinkage of the photocurable resin composition containing the composition (a) during curing can be suppressed, and curling of the film made of the cured product can be suppressed. In addition, the cured product is excellent in flexibility and processability, and when a base material having a film made of a cured product on the surface is bent, problems such as cracks and peeling are less likely to occur in the film.

The total content of the component (B) and the component (C) can be appropriately set in consideration of the molar ratio (NCO / OH) of the isocyanate group to the hydroxyl group of the component (A).
NCO / OH is, for example, 0.5 to 2.

The ratio of the component (A) to the total mass of the component (A), the component (B) and the component (C) is preferably 60 to 85% by mass, more preferably 65 to 85% by mass, and 70 to 80% by mass. More preferred.
The ratio of the component (B) to the total mass of the component (A), the component (B) and the component (C) is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, and 20 to 30% by mass. More preferred.
The ratio of the component (C) to the total mass of the component (A), the component (B) and the component (C) is preferably 0 to 10% by mass, more preferably 0 to 5% by mass.

<Urethane (meth) acrylate>
The urethane (meth) acrylate is a reaction product of the hydroxyl group-containing dipentaerythritol (meth) acrylate contained in the component (A) and the component (B), or the hydroxyl group-containing dipentaerythritol (meth) acrylate and the component (B). (C) A reaction product with the component.

Urethane (meth) acrylate is derived from the component (A) and has a (meth) acryloyl group.
The number of (meth) acryloyl groups contained in one molecule of urethane (meth) acrylate is 4 or more, preferably 6 to 20 and more preferably 10 to 15. When the number of (meth) acryloyl groups is at least the above lower limit value, the cured product of the photocurable resin composition containing the present composition (a) has high hardness, excellent scratch resistance and hard coat property, and the upper limit. If it is less than or equal to the value, the substrate of the photocurable resin composition containing the present composition (a) is excellent in flexibility and processability, and has a film (cured film) made of the cured product on the surface. When bent, the cured film is less likely to have problems such as cracks and peeling.
The number of (meth) acryloyl groups in one molecule is a theoretical value based on the reaction between the hydroxyl group of the component (A) and the isocyanate group of the total of the components (B) and (C) at a molar ratio of 1: 1. Is required from.

The Mw of urethane (meth) acrylate is 5000 or more, preferably 20000 or more. When Mw is at least the above lower limit value, the cured product is excellent in flexibility and processability.
The Mw of urethane (meth) acrylate is preferably 200,000 or less, more preferably 150,000 or less. When Mw is not more than the upper limit value, the hardness of the cured product is high, and scratch resistance and workability are excellent.

In the composition (a), the ratio of urethane (meth) acrylate to DPH (M) A (urethane (meth) acrylate: DPH (M) A) is preferably 60:40 to 95: 5, preferably 75:25 to. 90:10 is more preferable. When the ratio of urethane (meth) acrylate and DPH (M) A is within the above range, the balance between hardness and flexibility of the cured product is more excellent.
The ratio of urethane (meth) acrylate to DPH (M) A is the area ratio of GPC.

<Manufacturing method of composition (a)>
The composition (a) can be produced by reacting the component (A) with the component (B) or reacting the component (A) with the component (B) and the component (C) (urethaneization step). .. When each of these components is reacted, the hydroxyl group of the hydroxyl group-containing dipentaerythritol (meth) acrylate of the component (A) and the isocyanate group of the component (B) or the component (C) form a urethane bond to form a urethane (meth). Acrylate is produced. When the component (A) contains DPH (M) A, DPH (M) A does not react and remains as it is.

The reaction temperature in the urethanization step is, for example, 50 to 150 ° C., more preferably 60 to 100 ° C.
The reaction time of the urethanization step varies depending on the reaction temperature, the presence or absence of a catalyst, and the type, but is, for example, 6 to 48 hours, and further 12 to 36 hours.

The urethanization step is preferably performed in the presence of a catalyst from the viewpoint of shortening the reaction time. As the catalyst, a known urethanization catalyst can be used, and examples thereof include organometallic compounds such as dibutyltin acetate, dibutyltin dilaurate and dioctyltin dilaurate, and basic compounds such as triethylenediamine and triethylamine.
The amount of the catalyst used can be appropriately adjusted depending on the activity of the catalyst used, but is preferably 0.01 to 0.50% by mass, preferably 0.03 to 0.30% by mass, based on the component (A). More preferably, 0.05 to 0.25% by mass is further preferable.

The urethanization step is preferably carried out in the presence of a thermal polymerization inhibitor from the viewpoint of suppressing the reaction of the (meth) acryloyl group. As the thermal polymerization inhibitor, known thermal polymerization inhibitors can be used, and examples thereof include 2,6-di-tert-butyl-p-cresol and 4-methoxyphenol.
The amount of the thermal polymerization inhibitor used can be appropriately adjusted depending on the activity of the thermal polymerization inhibitor used, but is 0.01 with respect to the total of the components (A), (B) and (C). It is preferably ~ 1.5% by mass, more preferably 0.03 to 1.0% by mass, still more preferably 0.03 to 0.8% by mass.

In the urethanization step, it is preferable to react substantially all of the component (B) and the component (C) with the component (A).
The infrared absorption spectrum of the reactants was measured, and the absorption of the wavelength 2200 to 2300 cm ^-1 derived from the isocyanate residue was no longer observed, so that substantially all of the components (B) and (C) were (A). It can be determined that it has reacted with the component.

[Photocurable resin composition]
The photocurable resin composition of the present invention (hereinafter, also referred to as “the present resin composition”) contains the composition (a) and a photopolymerization initiator. Since the composition (a) contains a urethane (meth) acrylate, the present resin composition contains a urethane (meth) acrylate and a photopolymerization initiator. When the composition (a) contains DPH (M) A, it contains urethane (meth) acrylate, DPH (M) A, and a photopolymerization initiator.
This resin composition is also referred to as a compound having a polymerizable unsaturated bond (polymerizable carbon-carbon double bond, etc.) other than urethane (meth) acrylate and DPH (M) A (hereinafter, also referred to as “other polymerizable compound”). It may be further included.).
The present resin composition may further contain a non-reactive diluent, if necessary.
The present resin composition may further contain components other than the above, if necessary.

<Photopolymerization initiator>
As the photopolymerization initiator, a known photopolymerization initiator can be used, and for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, α-hydroxyacetophenone, diethoxyacetophenone, 2-hydroxy-2- Methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethyl Amino-1- (4-morpholinophenyl) butanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, benzophenone, methyl o-benzoylbenzoate, hydroxybenzophenone , 2-Isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6 Examples thereof include -bis (trichloro) -S-triazine, 2- (4-methoxyphenyl) -4, 6-bis (trichloromethyl) -S-triazine, an iron-allene complex, and a titanosen compound. These photopolymerization initiators may be used alone or in combination of two or more.

<Other polymerizable compounds>
Examples of other polymerizable compounds include a monofunctional monomer having one polymerizable unsaturated bond, a polyfunctional monomer having two or more polymerizable unsaturated bonds, and the like.
Examples of the monofunctional monomer include hydroxyl group-containing monofunctional (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate, acryloylmorpholine, dimethylacrylamide, and isobornyl acrylate. Can be mentioned.
Examples of the polyfunctional monomer include hydroxyl group-containing polyfunctional (meth) acrylates such as dipentaerythritol di, tri, tetra or penta (meth) acrylate, pentaerythritol di or tri (meth) acrylate, DPH (M) A, and penta. Examples thereof include erythritol tetra (meth) acrylate, tripropylene glycol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate.
These monomers may be used alone or in combination of two or more. A monofunctional monomer and a polyfunctional monomer may be used in combination.

<Non-reactive diluent>
The non-reactive diluent is a compound that does not have a polymerizable unsaturated bond and is liquid at room temperature.
Examples of the non-reactive diluent include organic solvents such as methanol, ethanol, isopropyl alcohol, propylene glycol monomethyl ether, methyl ethyl ketone, ethyl acetate, butyl acetate and toluene, and water. These non-reactive diluents may be used alone or in combination of two or more.
As the non-reactive diluent, a ketone solvent such as methyl ethyl ketone and an ester solvent such as ethyl acetate are preferable because they are excellent in dilutability and workability in the drying step.

<Other ingredients>
Other ingredients include thermal polymerization inhibitors, UV absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, antiaging agents, antibacterial agents, fungicides, antifoaming agents, leveling agents, fillers, etc. Examples thereof include additives such as thickeners, adhesion-imparting agents, thixo-imparting agents, and brightening materials.

<Contents of each component>
The content of the composition (a) is preferably 30 to 95% by mass, more preferably 50 to 95% by mass, based on the total mass of the present resin composition. When the content of the composition (a) is at least the above lower limit value, the balance between the hardness and the flexibility of the cured product is more excellent.

The content of the other polymerizable compound is preferably 0 to 50% by mass, more preferably 0 to 30% by mass, based on the total mass of the present resin composition. When the content of the other polymerizable compound is not more than the upper limit, the balance between the hardness and the flexibility of the cured product is more excellent.

The ratio of the composition (a) to the total content of the composition (a) and the other polymerizable compound is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. .. When the ratio of the composition (a) is at least the above lower limit value, the balance between the hardness and the flexibility of the cured product is more excellent.

The content of the photopolymerization initiator is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, based on the total mass of the present resin composition. When the content of the photopolymerization initiator is not less than the lower limit value, the photocurability of the present resin composition is more excellent, and when it is not more than the upper limit value, the storage stability of the present resin composition is more excellent.

The content of the non-reactive diluent is preferably 0 to 80% by mass, more preferably 20 to 60% by mass, based on the total mass of the present resin composition. When the content of the non-reactive diluent is at least the above lower limit value, the workability is more excellent.

The present resin composition can be produced by mixing the composition (a), a photopolymerization initiator, and, if necessary, at least one selected from the group consisting of other polymerizable compounds and other components. The mixing order of each component is not particularly limited.

The present resin composition can be cured by irradiating with light to obtain a cured product.
When the present resin composition is irradiated with light, active species (radicals and cations) are generated by intramolecular cleavage and hydrogen transfer of the photopolymerization initiator, and the active species are urethane (meth) acrylate or DPH (M) A. , A polymerization or cross-linking reaction occurs by acting on other polymerizable compounds, and the present resin composition is cured.

Examples of the light include visible light, ultraviolet rays, plasma, infrared rays, ionizing radiation and the like. Among these, ultraviolet rays are preferable from the viewpoint that the irradiation device is widely used.
The light irradiation conditions can be appropriately selected according to the light source used. The integrated light amount when irradiating with ultraviolet rays is, for example, 50 to 1000 mJ / cm ² .

The present resin composition can be used, for example, in applications such as hard coat agents, paints, inks, resists, and cross-linking agents.
This resin composition is suitable as a hard coat agent because it can form a cured product having high hardness and less likely to cause curling or cracking.

The hard coat agent composed of the present resin composition can be used to form a hard coat layer on the surface of the base material.
For example, a hard coat agent is applied to the surface of a base material and dried as necessary to form a coating film made of the hard coat agent. Next, the coating film is irradiated with light and cured to form a hardcoat layer (cured film) made of a cured product of the hardcoat agent. This gives a substrate with a hardcourt layer.

Examples of the base material include films, sheets, and various other molded products. A film is preferable in that it is highly useful because it can suppress curling. The thickness of the film is, for example, 10 to 500 μm.
Examples of the material of the base material include resin, metal, glass, and wood. Examples of the resin include polyesters such as polyethylene terephthalate (PET), polycarbonate resins, and ABS resins.

As the coating method, a known coating method can be appropriately adopted, and examples thereof include spray coating, spin coating, and gravure coating.
As the drying conditions, it suffices if the non-reactive diluent can be removed, and examples thereof include conditions at 60 to 110 ° C. for 0.5 to 10 minutes.
The light irradiation conditions are the same as described above.
The thickness of the coating film is set according to the thickness of the hard coat layer to be formed.
The thickness of the hard coat layer can be, for example, 1 to 20 μm.

Hereinafter, the present invention will be specifically described with reference to examples.
In the following, "part" means "part by mass".
The component (A) is a mixture of a plurality of dipentaerythritol acrylates having different numbers of acryloyl groups, contains a hydroxyl group-containing dipentaerythritol polyacrylate and dipentaerythritol hexaacrylate (DPHA), and has a hydroxyl value of 129 mgKOH / g or A dipentaerythritol acrylate mixture at 95 mgKOH / g was used.
The Mw of urethane acrylate in the urethane acrylate / DPHA-containing mixture and the ratio of urethane acrylate to DPHA were determined by GPC (gel permeation chromatography).

[Manufacturing Example 1]
In a four-necked flask equipped with a thermometer, a cooling tube, and a stirrer, 462 parts of a dipentaerythritol acrylate mixture having a hydroxyl value of 129 mgKOH / g, 400 parts of methylethylketone, 0.3 parts of dibutyltin dilaurate, and 2,6-di- 0.3 part of tert-butyl-p-cresol, 121 parts of hexamethylene diisocyanate and 18 parts of hexamethylene diisocyanate were added and stirred sufficiently, then heated to 70 ° C. and stirred and heated for about 24 hours. And reacted. After the reaction, it was confirmed that the isocyanate residue was no longer observed by infrared absorption spectroscopy. In this way, a mixture containing urethane acrylate and DPHA (hereinafter, also referred to as “urethane acrylate / DPHA-containing mixture”) was obtained.
Table 1 shows Mw of urethane acrylate, the number of acryloyl groups in one molecule, and the ratio of urethane acrylate to DPHA.

[Production Example 2, Comparative Production Examples 1 to 3]
A urethane acrylate / DPHA-containing mixture was obtained in the same manner as in Production Example 1 except that the types and amounts of the materials to be charged into the four-necked flask were as shown in Table 1.
Table 1 shows Mw of urethane acrylate, the number of acryloyl groups in one molecule, and the ratio of urethane acrylate to DPHA.

[Example 1]
(Preparation of resin composition)
In a flask equipped with a stirrer, 100 parts of the urethane acrylate / DPHA-containing mixture obtained in Production Example 1 and a photopolymerization initiator (1-hydroxycyclohexylphenyl ketone, IGM Resins B.V.), product name "Omnirad 184" ) (Hereinafter simply referred to as "Omnirad 184"), 1.8 parts and 20 parts of methyl ethyl ketone were added and stirred for about 1 hour to obtain a liquid resin composition.

(Formation of evaluation sample)
The obtained resin composition was applied to a glass plate so that the film thickness after drying was 5 μm, and dried at 100 ° C. to form a coating film. Then, the coating film was irradiated with ultraviolet rays so that the integrated light amount was 500 mJ / cm ² , and a cured film (cured product) was formed to obtain a glass plate with a cured film.
A film with a cured film was obtained in the same manner as above except that a film having a thickness of 100 μm (easy-adhesive PET) was used instead of the glass plate.

(evaluation)
The following items were evaluated for the prepared evaluation sample (glass plate with cured film or film with cured film), and the results are shown in Table 3.

<Pencil hardness>
The pencil hardness of the surface of the cured film of the glass plate with the cured film was measured according to JIS K 5600-5-4.

<Adhesion>
The surface of the film with the cured film on the cured film side was scratched in a grid pattern of 100 squares, cellophane tape was attached from above, and the film was peeled off at an angle of 90 degrees. The presence or absence of peeling of the cured film at this time was observed, and the adhesion was evaluated according to the following criteria.
◯: No peeling.
×: There is peeling.

<Curl>
Cut the film with the cured film into 10 cm x 10 cm, place it on a horizontal table, measure the height (mm) of each of the four sides of the film from the surface of the table, and measure the average value of the four sides. And said.
When the same evaluation was performed on the base material itself (the film before the cured film was provided), the curl was 0 mm.

<Scratch resistance>
A load of 200 g / cm ² was applied to steel wool # 0000 to reciprocate 10 times on the surface of the cured film of the glass plate with the cured film. After that, the state of scratches on the surface of the cured film was visually confirmed, and the scratch resistance was evaluated according to the following criteria.
◎: No scratches.
◯: There are some scratches.
×: There are scratches.

<Flexibility>
A mandrel test was carried out on the film with a cured film using a cylindrical mandrel bending tester. The mandrel test was performed with the cured film side of the film with the cured film facing outward. Flexibility was evaluated based on the following criteria from the diameter of the mandrel with the smallest diameter (minimum mandrel diameter) among the mandrel in which defects such as cracks and peeling did not occur in the cured film.
〇: The minimum mandrel diameter is 3 mm or less.
X: The minimum mandrel diameter is 5 mm or more.

[Example 2, Comparative Examples 1 to 3]
A resin composition was prepared in the same manner as in Example 1 except that the type and amount of the material to be put into the flask were as shown in Table 2, and an evaluation sample was prepared and evaluated. The evaluation results are shown in Table 3.

As shown in the above results, according to the resin compositions of Examples 1 and 2, the curl is small and the bending is small while sufficiently maintaining the required characteristics as a hard coat such as hardness, adhesion to a substrate, and scratch resistance. It was possible to form a cured film with excellent properties, flexibility and toughness.

According to the photocurable resin composition of the present invention, it is possible to form a cured product having high hardness, good scratch resistance, and less likely to cause curling or cracking. The cured product is also excellent in adhesion to the substrate and flexibility. Therefore, the photocurable resin composition of the present invention is suitable as a hard coat agent. The film with a hard coat layer using the hard coat agent made of the photocurable resin composition of the present invention can be applied to foldable devices and the like.

Claims (8)

A dipentaerythritol (meth) acrylate mixture (A) and a polyisocyanate compound (B) having three or more isocyanate groups, or the dipentaerythritol (meth) acrylate mixture (A) and the polyisocyanate compound (B). ) And the diisocyanate compound (C), which is a composition containing a urethane (meth) acrylate.
The urethane (meth) acrylate has four or more (meth) acryloyl groups in one molecule, and has a weight average molecular weight of 5,000 or more.
A urethane (meth) acrylate-containing composition having a hydroxyl value of 121 to 150 mgKOH / g of the dipentaerythritol (meth) acrylate mixture (A). The dipentaerythritol (meth) acrylate mixture (A) contains dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and The urethane (meth) acrylate-containing composition according to claim 1, which comprises at least two selected from the group consisting of dipentaerythritol hexa (meth) acrylate. The polyisocyanate compound (B) is a trimeric of isophorone diisocyanate, a trimeric of 1,3-bis (isocyanatomethyl) cyclohexane, a trimeric of hexamethylene diisocyanate, and a trimeric of trimethylhexamethylene diisocyanate. The urethane (meth) acrylate-containing composition according to claim 1 or 2, which is at least one selected from the group consisting of bodies. Claim 1 to claim 1, wherein the diisocyanate compound (C) is at least one selected from the group consisting of isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. 3. The urethane (meth) acrylate-containing composition according to any one of 3. A photocurable resin composition comprising the urethane (meth) acrylate-containing composition according to any one of claims 1 to 4 and a photopolymerization initiator. A cured product of the photocurable resin composition according to claim 5. A hard coat agent comprising the photocurable resin composition according to claim 5. A base material with a hard coat layer having a hard coat layer made of a cured product of the hard coat agent according to claim 7 on the surface of the base material.