JP2006083273A - Allophanate group-containing (meth)acrylate resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an allophanate group-containing (meth)acrylate resin with flexibility and scratch resistance compatible with each other, excellent in adhesion to plastic base materials and compatibility with other resins, and curable by ultraviolet light, electron beams, radiation or the like, and to provide a composition comprising the resin. <P>SOLUTION: The allophanate group-containing (meth)acrylate resin is such that the resin skeleton contains a structure composed of an allophanate group of formula(1)(wherein, R1 is a 1-40C aliphatic, alicyclic or aromatic hydrocarbon group, wherein the hydrocarbon group may be branched or have substituent(s)) and the structure of the resin terminal is represented by formula(2)(wherein, R2 is a 1-50C organic group and may be branched or have side chain(s); and R3 is H or methyl). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an allophanate group-containing (meth) acrylate resin composition that can be cured by ultraviolet rays, electron beams, radiation, or the like.

  Ultraviolet curable coatings are made of oligomers and monomers, and these are cured by ultraviolet rays. Therefore, they are attracting attention as coatings that have no volatile components and can cope with environmental problems. Among these ultraviolet curable paints, ultraviolet curable urethane resins are known as oligomer components that can provide a cured coating film having excellent scratch resistance. However, UV curable urethane resins are usually not only inferior in compatibility with acrylic resins and polyester resins, but if the cured coating is hardened to improve scratch resistance, cracking and adhesion of the coating due to curing shrinkage In addition, when a thin substrate such as a film is used, the film has a problem of curling.

  In order to solve such a problem, a method for producing an ultraviolet curable urethane resin from polyisocyanate has been disclosed (for example, Patent Document 1). According to this production method, an ultraviolet curable urethane resin can be obtained by reacting an isocyanate group-containing urethane resin with a hydroxyl group-containing acrylic monomer and / or methacrylic monomer. The coating film obtained by curing the ultraviolet curable urethane resin obtained by this production method is excellent in flexibility, heat resistance, and coating film physical properties in repeated heat tests, but the urethane resin is an allophanate group. Therefore, it cannot solve the problem of compatibility with other resins, and the cured coating film of the resin has the performance level of flexibility and scratch resistance required from the market. It was not compatible.

  Moreover, the composition which consists of a urethane polymer which reacted the polyol, tolylene diisocyanate, the hydroxyl group containing vinyl monomer, and styrene is disclosed (for example, patent document 2). In this composition, polymers are cross-linked with allophanate bonds to impart thixotropic properties. However, in the above composition, the proportion of allophanate bonds is very small in order to maintain a suitable viscosity. Therefore, there is a problem that the effect of improving the compatibility with other resins is extremely poor, and further, it is insufficient to impart flexibility to the cured coating film of the composition.

  Moreover, the ultraviolet curable urethane resin which introduce | transduced the unsaturated group through the allophanate group is disclosed (for example, patent document 3). Although allophanate groups are introduced into this UV curable urethane resin, it has a structure in which ethylenically unsaturated groups are introduced through allophanate groups, so the effect of improving compatibility with other resins is This is not always sufficient, and there is a problem that the coating film obtained by curing the resin has insufficient scratch resistance and flexibility.

Moreover, the ultraviolet curable urethane resin containing 20 to 50% of uretdione groups, 20% or less of isocyanurate groups, and 0.1 to 40% of urethane groups and allophanate groups is disclosed (for example, Patent Document 4). . The coating film obtained by curing this ultraviolet curable urethane resin is excellent in scratch resistance because it contains a large amount of uretdione groups, but the effect of improving compatibility with other resins is not sufficient, and the resin itself Since the flexibility of the obtained cured coating film is extremely low due to poor flexibility, there is a problem that the coating film is likely to be cracked when bent, for example.
JP-A-5-209038 JP-A-61-243815 JP-A-10-279656 JP 2003-48927 A

  An object of the present invention is to provide a resin and a resin composition excellent in adhesion to a plastic substrate and compatibility with other resins, and furthermore, these resins and resin compositions capable of achieving both flexibility and scratch resistance. It is providing the hardened | cured material which consists of.

  As a result of intensive studies to solve the above problems, the present inventors include at least a structure comprising an allophanate group represented by the following formula (1) in the resin skeleton, and further represented by the following formula (2). An allophanate group-containing (meth) acrylate resin and a resin composition containing the resin, characterized by including a structure composed of a group, have excellent compatibility with other resins, and excellent adhesion to a plastic substrate. Furthermore, the present inventors have found that the cured product of the resin composition can achieve both flexibility and scratch resistance, and have completed the present invention.

(In the formula, R1 represents an aliphatic, alicyclic, or aromatic hydrocarbon group having 1 to 40 carbon atoms in total. However, these hydrocarbon groups may have a branch or a substituent. (You may have it.)

(In the formula, R2 represents an organic group having 1 to 50 carbon atoms in total, and R3 represents a hydrogen atom or a methyl group. However, the organic group R2 may have a branch or have a side chain. May be.)
Among the allophanate group-containing (meth) acrylate resins, an allophanate group-containing (meth) acrylate resin characterized by having at least two (meth) acrylate groups in one molecule of the resin and a composition containing the resin are preferable. .

The allophanate group-containing (meth) acrylate resin preferably contains 0.2 to 5.0 mmol / g of allophanate groups.
The resin can be suitably used for paint applications, and in particular, a paint containing the resin and a photopolymerization initiator can be suitably used as a photocurable paint.

Moreover, the composition containing the said resin can harden | cure and can be used as hardened | cured material.
Moreover, the said resin composition is suitable for the resin composition for hard-coats.
In addition, description like methyl (meth) acrylate means that it is methyl acrylate and / or methyl methacrylate, and description with (meth) acrylate is the same meaning hereafter.

  According to the present invention, a resin and a resin composition excellent in compatibility with other resins and excellent in adhesion to a plastic substrate can be obtained, and further, the resin composition capable of achieving both flexibility and scratch resistance. A cured coating film comprising a product can be obtained.

The present invention will be described in detail below.
[Allophanate group-containing (meth) acrylate resin]
The allophanate group-containing (meth) acrylate resin according to the present invention includes a structure composed of an allophanate group represented by the above formula (1) in the resin skeleton, and further includes a structure represented by the above formula (2). It is characterized by. The allophanate group-containing (meth) acrylate resin having the above structure can be obtained by reacting an allophanate group-containing polyisocyanate resin with an active hydrogen compound having at least one (meth) acrylate group in the molecule.

<Allophanate group-containing polyisocyanate resin>
The allophanate group-containing polyisocyanate resin used in the present invention can be obtained by reacting a monoalcohol with an organic polyisocyanate prepolymer under specific conditions.

≪Method for producing organic polyisocyanate prepolymer≫
The organic polyisocyanate prepolymer used in the present invention refers to a prepolymer having an isocyanate group, and can usually be produced by reacting an isocyanate compound and a hydroxyl group-containing compound.

  The isocyanate compound used in the production reaction can be generally divided into a diisocyanate compound and a polyisocyanate compound. Here, in the present invention, the polyisocyanate compound means an isocyanate compound having three or more isocyanate groups.

As the diisocyanate compound, for example,
Trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4 , 4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methylcaproate and other aliphatic diisocyanate compounds;
1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2 , 4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanate methyl) cyclohexane, 1,3-diisocyanatomethyl cyclohexane (H ₆ XDI ), Alicyclic diisocyanate compounds such as isophorone diisocyanate (IPDI);
1,3- or 1,4-xylylene diisocyanate, a mixture of the two compounds, ω, ω′-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis (1-
Isocyanate-1-methylethyl) benzene, an araliphatic diisocyanate compound such as a mixture of the above two compounds; and m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, Aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, toluene diisocyanate (TDI) Compound;
Etc.

As a polyisocyanate compound, for example,
Lysine ester triisocyanate, 1,4,8-triisocyanate octane, 1,6,11-triisocyanate undecane, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-triisocyanate hexane, 2,5 Aliphatic polyisocyanate compounds such as 1,7-trimethyl-1,8-diisocyanate-5-isocyanate methyloctane;
1,3,5-triisocyanatecyclohexane, 1,3,5-trimethylisocyanatecyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatemethyl) -bicyclo (2.2.1) heptane, 2 -(3-Isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2 2.1) Heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2 -Isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, -(2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3 An alicyclic polyisocyanate compound such as -isocyanatopropyl) -bicyclo (2.2.1) heptane;
Araliphatic polyisocyanate compounds such as 1,3,5-triisocyanate methylbenzene; and triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatebenzene, 2,4, And aromatic polyisocyanate compounds such as 6-triisocyanate toluene and 4,4′-diphenylmethane-2,2 ′, 5,5′-tetraisocyanate.

These isocyanate compounds may be used alone or in combination of two or more. Among these isocyanate compounds, hexamethylene diisocyanate (HDI), 1,3-diisocyanatomethylcyclohexane (H ₆ XDI), and isophorone diisocyanate (IPDI) are preferable.

Examples of the hydroxyl group-containing compound used when producing the organic polyisocyanate prepolymer include:
Methanol, ethanol, propanol, butanol, alkanol having 5 to 38 carbon atoms, alkenyl alcohol having 3 to 36 carbon atoms (for example, 2-propen-1-ol, etc.), alkadienol having 6 to 8 carbon atoms ( Monoalcohols (monohydric alcohols) such as aliphatic unsaturated alcohols having 9 to 24 carbon atoms other than the above, such as 3,7-dimethyl-1,6-octadiene-3-ol)
Ethylene glycol, propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,6-hexanediol, methylpentanediol, neopentylglycol, 3,3-dimethylolheptane, Alkanediol having 7 to 22 carbon atoms, diethylene glycol, triethylene glycol, dipropylene glycol, cyclohexanedimethanol, alkane-1,2-diol having 17 to 20 carbon atoms, hydrogenated bisphenol A, 1,4-dihydroxy- Dialcohols (dihydric alcohols) such as 2-butene, 2,6-dimethyl-1-octene-3,8-diol, bisphenol A;
Glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, 1,1,1-tris (hydroxymethyl) Trialcohols (trihydric alcohols) such as propane, 2,2-bis (hydroxymethyl) -3-butanol and other aliphatic triols having 8 to 24 carbon atoms;
Tetramethylol methane, D-sorbitol, xylitol, D-mannitol, tetravalent or higher alcohols such as D-mannitol;
Polyester polyols such as pivalic acid neopentyl glycol ester;
Polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol; and polycarbonate polyols such as polyhexamethylene carbonate glycol;
Etc.

  Among these compounds having a hydroxyl group, monoalcohol or dialcohol is preferable. Moreover, these compounds having a hydroxyl group may be used alone or in combination of two or more.

  When the hydroxyl group compound is a monoalcohol, the organic polyisocyanate prepolymer used in the present invention is an isocyanate compound in an amount that is an excess of the isocyanate group equivalent to the monoalcohol and twice the equivalent of the hydroxyl equivalent of the monoalcohol. When the hydroxyl group compound is other than a monoalcohol, the hydroxyl group-containing compound is reacted with an amount of the isocyanate compound in an amount that is an excess of the isocyanate group equivalent to the hydroxyl group equivalent of the hydroxyl group-containing compound, and further required. Depending on the case, it can be obtained by removing the unreacted isocyanate compound.

≪Method for producing allophanate group-containing polyisocyanate resin≫
The allophanate group-containing polyisocyanate resin used in the present invention can be obtained by reacting the above organic polyisocyanate prepolymer with a monoalcohol under specific reaction conditions. This is disclosed in detail in Japanese Laid-Open Patent Application No. 5-209090 and Japanese Laid-Open Patent Application No. 8-188556.

  That is, the allophanate group-containing polyisocyanate resin is an allophanate-forming reaction of monoalcohol and the above-mentioned organic polyisocyanate prepolymer in an amount that gives an excess of isocyanate group equivalent to the hydroxyl group equivalent in the monoalcohol in the presence of a catalyst. Further, it can be obtained by removing the unreacted organic polyisocyanate prepolymer.

  By these reactions, monoalcohol can be bonded to the organic polyisocyanate prepolymer via the allophanate group, and the solubility in acrylic resin and polyester resin can be greatly improved. Moreover, the skeleton derived from the monoalcohol can impart flexibility to the cured product obtained using the resin, so that both flexibility and scratch resistance can be achieved.

The monoalcohol used in the above production process may have a polar group such as an unsaturated bond, an ether group or an ester group. The monoalcohol can be appropriately selected and used according to the other resin to be compatible.

  Among these monoalcohols, monoalcohols having 1 to 40 carbon atoms are preferable. By using a monoalcohol having a carbon number within the above range, both the flexibility and scratch resistance of the cured coating film can be achieved.

As these monoalcohols,
Methanol, ethanol, n-propanol, isopropanol, butanol isomers, allyl alcohol, pentanol, hexanol, heptanol, 2-ethylhexanol, n-octanol, nonanol, n-decanol, cyclopentanol, cyclohexanol, furfuryl alcohol Aliphatic, alicyclic and araliphatic alcohols such as benzyl alcohol;
An ether group-containing monoalcohol which is an addition polymer (a random and / or block copolymer of two or more alkylene oxides) of the monoalcohol and an alkylene oxide such as ethylene oxide or propylene oxide;
An ester group-containing monoalcohol which is an addition polymer of a low molecular weight monoalcohol and a lactone such as ε-caprolactone or δ-valerolactone;
An ester group-containing monoalcohol which is an adduct of a monocarboxylic acid such as acetic acid, propionic acid, benzoic acid and an alkylene oxide;
Etc. can be illustrated.

  In addition to the monoalcohol having 1 to 40 carbon atoms described above, a small amount of polyfunctional alcohol such as dialcohol or trialcohol can be used in combination. In addition to these, active hydrogen compounds such as thiols, oximes, lactams, phenols, and β-diketones can be used in combination as necessary.

  In addition, prior to the allophanatization reaction with the organic polyisocyanate prepolymer and the monoalcohol, some or all of the hydroxyl groups present in the monoalcohol and some of the isocyanate groups present in the organic polyisocyanate compound are pre-reacted. Then, a urethane group may be generated.

  In the present invention, the use ratio of the organic polyisocyanate prepolymer and the monoalcohol is the molar ratio of the isocyanate group present in the organic polyisocyanate prepolymer to the hydroxyl group present in the monoalcohol ([isocyanate group in the prepolymer). ] / [Hydroxyl group in monoalcohol]) is usually in the range of 5 to 100, preferably 10 to 50. When the molar ratio of the isocyanate group to the hydroxyl group is within the above range, the allophanate group content becomes an appropriate amount, and a resin having high solubility with other resins can be obtained.

  A solvent may or may not be used for the reaction between the monoalcohol and the organic polyisocyanate compound. When using a solvent, it is necessary to use a solvent having no reaction activity with respect to an isocyanate group.

As the catalyst used for the reaction between the monoalcohol and the organic polyisocyanate prepolymer, a catalyst that is easy to control the reaction, has little coloring of the final product, and generates a dimer having poor thermal stability is used. As these catalysts, for example,
Tetraalkylammonium hydroxides such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, trimethylbenzylammonium and their weak organic acid salts;
Trialkylhydroxyalkylammonium hydroxides and their organic weak acid salts such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, triethylhydroxyethylammonium;
Alkyl carboxylates of alkyl carboxylic acids such as acetic acid, caproic acid, octylic acid, myristic acid and alkali metals;
An alkylcarboxylic acid metal salt of the above alkylcarboxylic acid and a metal such as tin, zinc or lead;
A chelate compound of β-diketone and metal such as aluminum acetylacetone and lithium acetylacetone;
Friedel-Crafts catalysts such as aluminum chloride and boron trifluoride;
Various organometallic compounds such as titanium tetrabutyrate and tributylantimony oxide; and aminosilyl group-containing compounds such as hexamethylsilazane;
And so on.

  Among these catalysts, quaternary ammonium compounds such as tetraalkylammonium hydroxide and its organic weak acid salt, trialkylhydroxyalkylammonium hydroxide and its organic weak acid salt are preferably used.

Although the said catalyst changes with the kind, reaction temperature, etc., it is normally used in 0.0001-1 weight% with respect to organic polyisocyanate. In the present invention, the allophanatization reaction is usually performed in a temperature range of 20 to 160 ° C, preferably 40 to 100 ° C.

  When the desired polyisocyanate resin reaches the desired amount of residual NCO, for example, an acidic substance such as phosphoric acid, benzoyl chloride, monochloroacetic acid, dodecylbenzenesulfonic acid is added to the reaction mixture as a catalyst deactivator, After deactivation of the catalyst, it can be obtained, for example, by removing the unreacted organic polyisocyanate prepolymer by means such as thin film distillation.

  The polyisocyanate resin having an allophanate group thus obtained can be made into a resin that can be mixed with other resins at an arbitrary ratio by appropriately selecting the raw material monoalcohol, and does not become cloudy even at room temperature or lower. Resin can be provided.

The allophanate group-containing polyisocyanate resin can also be obtained by reacting the isocyanate compound used in the production of the organic polyisocyanate prepolymer described above with a monoalcohol, which is a compound having a hydroxyl group, under conditions where the isocyanate compound is in a large excess. It is done.
<Method for producing allophanate group-containing (meth) acrylate resin>
The allophanate group-containing (meth) acrylate resin according to the present invention is obtained by reacting the allophanate group-containing polyisocyanate resin with an active hydrogen compound having at least one (meth) acrylate group in the molecule. As the active hydrogen compound having a (meth) acrylate group used in this reaction, a compound containing a (meth) acrylate group and a hydroxyl group can be suitably used.

In order to make the cured product of the allophanate group-containing (meth) acrylate resin excellent in scratch resistance, it is necessary to form a urethane bond by this reaction. Therefore, it is preferable to control the reaction temperature to 40 ° C. or higher and 80 ° C. or lower. By carrying out the reaction within the above temperature range, a desired urethane bond can be formed efficiently, and when it is made into a cured product, excellent scratch resistance can be exhibited without impairing flexibility. The reaction is preferably performed without using a catalyst. Furthermore, from the viewpoint of reliably forming a urethane bond while suppressing side reactions, an allophanate group-containing polyisocyanate resin, and an isocyanate group contained in the allophanate group-containing polyisocyanate resin have an equimolar amount of a hydroxyl group-containing (meth) acrylate. Is preferably mixed at a low temperature in the temperature range of 10 ° C. or more and 50 ° C. or less, and then the reaction is started by raising the temperature.

As the hydroxyl group-containing (meth) acrylate compound,
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy- Compounds having one (meth) acrylate group in the molecule, such as 3-phenoxypropyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate;
Two or more (meth) per molecule such as pentaerythritol acrylate, pentaerythritol methacrylate, isocyanuric acid ethylene oxide modified diacrylate, isocyanuric acid ethylene oxide modified dimethacrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate A compound having an acrylate group;
Etc.

  In order to improve the scratch resistance of the coating film, it is important to increase the crosslink density, but it is obtained by using a compound having one (meth) acrylate group in the molecule as the hydroxyl group-containing (meth) acrylate compound. In the case of a cured product using the (meth) acrylate resin obtained, since the crosslinking density is low, the flexibility is improved, but the scratch resistance tends to be lowered. In the case of a cured product using a (meth) acrylate resin obtained by using a compound having two or more (meth) acrylate groups in the molecule, the crosslink density increases, so that the scratch resistance tends to be improved. When the allophanate group is contained in the (meth) acrylate resin, in particular, when the allophanate group and the isocyanurate group are contained, flexibility is imparted to the cured product, and flexibility and scratch resistance are obtained. Can be achieved.

  Therefore, in order to achieve both flexibility and scratch resistance, it is preferable to use a compound having at least two (meth) acrylate groups in the molecule, and at least three (meth) acrylate groups in the molecule. It is more preferable to use a compound having

  Further, the amount of the hydroxyl group-containing (meth) acrylate compound is preferably 5 parts by weight or more based on 100 parts by weight of the allophanate group-containing polyisocyanate resin.

  In addition, even if it is a case where it aims at coexistence with flexibility and scratch resistance, in the range which does not impair the effect, as a hydroxyl-containing (meth) acrylate compound, one (meth) acrylate group is included in a molecule | numerator. Even if it has the compound which has it, there is no problem.

In the allophanate group-containing (meth) acrylate resin according to the present invention, the allophanate group content is excellent in compatibility with other resins, and further, both the flexibility and scratch resistance of the cured product made of the above resin are achieved. Is preferably in the range of 0.2 to 5.0 mmol / g, more preferably 0.3 to 4 mmol / g, and still more preferably 0.4 to 3 mmol / g. The content of such allophanate groups is determined by H ¹ -NMR measurement using d6-DMSO or d6-acetone as a solvent as described in, for example, JP-A-2002-53635 and JP-A-8-52939. It can be obtained by doing.

  The cured product comprising the allophanate group-containing (meth) acrylate resin according to the present invention is given flexibility and compatibility with other resins by the carbon chain of the monoalcohol bonded with the allophanate group. Furthermore, since the (meth) acrylate group is bonded via a urethane group, scratch resistance can be exhibited without impairing flexibility.

[Light curable paint]
A photocurable resin composition can be obtained by adding a photopolymerization initiator and, if necessary, other additives to the allophanate group-containing (meth) acrylate resin according to the present invention. This photocurable resin composition is It can be suitably used for a photo-curing paint or the like.

<Photopolymerization initiator>
A photopolymerization initiator is used in the photocurable coating according to the present invention. The photopolymerization initiator in the present invention means a compound capable of generating radicals by ultraviolet rays, electron beams, radiation or the like. As a specific example of the photopolymerization initiator used in the present invention,
Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylphenyl Glyoxylate, ethylphenylglyoxylate, 4,4-bis (dimethylaminobenzophenone),
Carbonyl compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one;
Sulfur compounds such as tetramethylthiuram disulfide;
Azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile;
Anthraquinones such as 2-ethylanthraquinone;
Peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide; acylphosphines such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide An oxide compound;
And so on.

  Among these initiators, preferred initiators include benzophenone, methylphenylglyoxylate, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,4, Mention may be made of 6-trimethylbenzoyldiphenylphosphine oxide.

These photopolymerization initiators may be used alone or in combination of two or more.
The amount of these photopolymerizable initiators used is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the allophanate group-containing (meth) acrylate resin according to the present invention. . If the use amount of the photopolymerizable initiator is within the above range, the curing reaction can be sufficiently performed, and further, a photocurable coating material that does not cause discoloration of the cured film and discoloration over time can be obtained. preferable.

<Other additives>
Furthermore, the photocurable coating according to the present invention may be used by further adding a compound having a (meth) acrylic group, an acrylic resin, a polyester resin, an epoxy resin, a melamine resin, an olefin resin, etc. for the purpose of adjusting the viscosity. it can. Among these, since the compound having a (meth) acryl group has photocurability, it may be preferable to use it from the viewpoint of improving wear resistance and chemical resistance.

  Specific examples of such a compound having a (meth) acrylic group include 2 ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dipropylene glycol (meth) acrylate, Ethoxydiethylene glycol (meth) acrylate, hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentenyl (meth) acrylate, neopentyl glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, hydroxypivalic acid Opentyl glycol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, bis (( (Meth) acryloxyethyl) bisphenol A, trimethylolpropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane di (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, ethylene Oxide-modified glycerin tri (meth) acrylate, propylene oxide-modified glycerin tri (meth) acrylate, ditrimethylo Rupropanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, one of these (meth) acrylate compounds Examples thereof include polyfunctional (meth) acrylates in which a part is substituted with an alkyl group and ε-caprolactone.

  Furthermore, polyester poly (meth) acrylate obtained by reaction of polybasic acid such as phthalic acid and adipic acid, polyhydric alcohol such as ethylene glycol and butanediol, and (meth) acrylic acid compound; epoxy resin ( Epoxy poly (meth) acrylate obtained by reaction with meth) acrylic acid compound; polysiloxane poly (meth) acrylate obtained by reaction of polysiloxane with (meth) acrylic acid compound; polyamide and (meth) acrylic acid compound And polyamide poly (meth) acrylate obtained by the above reaction.

  Since the amount of these (meth) acrylic group-containing compounds does not decrease the chemical resistance and abrasion resistance of the cured coating film, the alphanate group-containing (meth) acrylate resin and (meth) acrylic according to the present invention are used. The weight ratio of the group-containing compound ([alphanate group-containing (meth) acrylate resin] / [(meth) acrylic group-containing compound]) is preferably in the range of 90/10 to 20/80. When the amount used is within the above range, the cured coating film after photocuring is excellent in chemical resistance and abrasion resistance.

  Further, the photocurable coating according to the present invention includes an organic solvent, a polymerization inhibitor, an ultraviolet absorber, a light stabilizer, an antioxidant, an anti-yellowing agent, a dye, a pigment, a leveling agent, an antifoaming agent, and a thickening agent. Further, it may contain various additives such as an anti-settling agent, an antistatic agent, an antifogging agent, an anti-fogging agent, a wetting agent, a dispersing agent, an anti-sagging agent and a coupling agent.

<Usage of photocurable paint>
There is no limitation on the method of applying such a photocurable coating to a substrate, and it can be performed by a conventional method such as brush coating, spray coating, dip coating, spin coating, curtain coating or the like. In order to develop sufficient abrasion resistance and good adhesion between the film and the substrate without generating cracks in the film, use it in a coating amount such that the film thickness of the cured film is 3 to 30 μm. It is preferable to do.

  As a means for curing the coating applied to the substrate, a known method of irradiating active energy rays such as ultraviolet rays, electron beams, and radiation can be used, and the ultraviolet ray generation source is from the viewpoint of practicality and economy. An ultraviolet lamp is generally used. Specific examples include ultraviolet lamps such as low-pressure mercury lamps, high-pressure mercury lamps, ultrahigh-pressure mercury lamps, xenon lamps, gallium lamps, and metal halide lamps. Sunlight can also be used directly. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon.

  In addition, after applying the photocurable paint according to the present invention to the surface of the substrate, before curing with active energy rays, an infrared or hot air drying furnace is used for the purpose of improving the adhesion of the cured film to the substrate. The heat treatment may be performed for 1 to 60 minutes in a temperature range of 20 to 120 ° C.

  Although there is no restriction | limiting in particular as a base material which apply | coats a photocurable coating material, For example, various synthetic resin molded products can be used. Specific examples include polymethyl methacrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyester resin, polystyrene resin, polyolefin resin, acrylonitrile-styrene copolymer resin, acrylonitrile-butadiene-styrene copolymer resin, polyamide resin, polyarylate resin, poly Examples include molded products such as methacrylimide resins and polyallyl diglycol carbonate resins. In particular, molded products using polymethylmethacrylic resin, polycarbonate resin, polystyrene resin, polyethylene terephthalate resin, polyolefin resin, and acrylonitrile-butadiene-styrene copolymer resin are highly demanded to improve wear resistance. A mold coating composition can be suitably used. Synthetic resin molded products include sheet-shaped molded products, film-shaped molded products, and various injection molded products made of these resins.

  The coating film obtained by the photo-curable paint according to the present invention has good transparency and excellent surface hardness, wear resistance, and adhesion, and therefore, particularly, a plastic substrate such as PET, ABS, PC is used. As a coating film for surface protection of automobile parts, cosmetic containers, etc., it can be suitably used as a hard coat coating film for optical members such as plastic lenses and resin films for display substrates.

〔Example〕
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

[Example 1]
An allophanate group-containing polyisocyanate resin was produced by the method disclosed in Example 1 of JP-A-6-41270. Specifically, it is a polyisocyanate resin obtained from 1,3-diisocyanatomethylcyclohexane (H6XDI) and isobutanol (IBA). The obtained polyisocyanate resin had an NCO content of 18.2 wt%, and almost no urethane groups were observed by NMR analysis. They were allophanate groups 35 mol% and isocyanurate groups 75 mol%. Subsequently, 600 g of this polyisocyanate resin, 206 g of pentaerythritol triacrylate (PETA), 241 g of 2-hydroxyethyl acrylate (HEA), and 2 g of methylhydroquinone were charged into a reaction vessel and reacted at 80 ° C. for 4 hours in an air stream. To this, 0.6 g of dibutyltin laurate was added, and further reacted at 80 ° C. for 4 hours to obtain a photocurable allophanate group-containing acrylate resin (A-1). The content of allophanate groups determined from H ¹ -NMR measurement of d6-DMSO as a solvent was 1.0 mmol / g.

[Example 2]
A polyisocyanate resin was produced by the method disclosed in Example 4 of JP-A-6-41270. Specifically, it is a polyisocyanate resin obtained from isophorone diisocyanate (IPDI) and isobutanol (IBA). The obtained polyisocyanate resin had an NCO content of 11.6 wt%, and almost no urethane groups were observed by NMR analysis. They were 60 mol% of allophanate groups and 40 mol% of isocyanurate groups. Subsequently, 600 g of this polyisocyanate, 127 g of pentaerythritol triacrylate (PETA), 149 g of 2-hydroxyethyl acrylate (HEA), and 2 g of methylhydroquinone were charged into a reaction vessel and reacted at 80 ° C. for 4 hours in an air stream. Dibutyltin laurate 0.6g was added to this, and also it was made to react at 80 degreeC for 4 hours, and the photocurable allophanate group containing acrylate resin (A-2) was obtained. The content of allophanate groups determined from H ¹ -NMR measurement of d6-DMSO as a solvent was 0.5 mmol / g.

[Example 3]
A polyisocyanate resin was produced by the method disclosed in Example 1 of JP-A-8-188565. Specifically, it is a polyisocyanate resin obtained from 1,6-hexamethylene diisocyanate (HDI) and isobutanol (IBA). The obtained polyisocyanate resin had an NCO content of 19.3 wt%, almost no urethane groups and isocyanurate groups were observed from NMR analysis and IR analysis, and allophanate groups were 100 mol%. Subsequently, 600 g of this polyisocyanate, 127 g of pentaerythritol triacrylate (PETA), 149 g of 2-hydroxyethyl acrylate (HEA), and 2 g of methylhydroquinone were charged into a reaction vessel and reacted at 80 ° C. for 4 hours in an air stream. To this, 0.6 g of dibutyltin laurate was added, and further reacted at 80 ° C. for 4 hours to obtain a photocurable allophanate group-containing acrylate resin (A-3). The content of allophanate groups determined from H ¹ -NMR measurement of d6-DMSO as a solvent was 1.3 mmol / g.

[Example 4]
A polyisocyanate resin was produced by the method disclosed in Comparative Example 1 of JP-A-6-41270. Specifically, it is a polyisocyanate resin obtained from 1,6-hexamethylene diisocyanate (HDI) and 1,3-butanediol (1,3BD). The obtained polyisocyanate resin had an NCO content of 20.8 wt%, and almost no urethane groups were observed by NMR analysis. They were 5 mol% allophanate groups and 95 mol% isocyanurate groups. Subsequently, 600 g of this polyisocyanate, 127 g of pentaerythritol triacrylate (PETA), 149 g of 2-hydroxyethyl acrylate (HEA), and 2 g of methylhydroquinone were charged into a reaction vessel and reacted at 80 ° C. for 4 hours in an air stream. To this, 0.6 g of dibutyltin laurate was added, and further reacted at 80 ° C. for 4 hours to obtain a photocurable allophanate group-containing acrylate resin (A-4). Further, the content of allophanate groups determined by H ¹ -NMR measurement using d6-DMSO as a solvent was 0.2 m.
mol / g.

[Comparative Example 1]
A photocurable acrylate resin was obtained by the method disclosed in Example 1 of JP-A-5-209038. Specifically, 4-hydroxybutyl acrylate (4HBA) is reacted with a polyisocyanate resin obtained from isophorone diisocyanate (IPDI) and polytetramethylene ether glycol (PTMEG). Although IR analysis and NMR analysis were conducted, the presence of allophanate groups and isocyanurate groups was not confirmed in this resin, and only the presence of urethane groups was confirmed.

[Comparative Example 2]
A photocurable acrylate resin was obtained by the method disclosed in Example 2 of JP-A-5-209038. Specifically, 4-hydroxybutyl acrylate (4HBA) is reacted with a polyisocyanate resin obtained from hexamethylene diisocyanate (HDI) and 1,3-butanediol (1,3-BD). By IR analysis and NMR analysis
The presence of urethane groups and isocyanurate groups in this resin was confirmed, but the presence of allophanate groups was not confirmed.

[Evaluation methods]
The photocurable acrylate resin obtained by the above method was tested by the following method. The results are shown in Table 1.

<Compatibility>
After mixing 100 g of acrylic resin (Olester Q164: made by Mitsui Chemicals) or 100 g of polyester resin (Olester Q2148E: made by Mitsui Chemicals) with 100 g of the synthesized photocurable acrylate resin, the mixture was stored at 40 ° C. for 1 week. The appearance was confirmed visually. Colorless and transparent were marked with ◯, slightly cloudy and without separation, Δ, and white with turbidity and separation with x.

Hereinafter, although it shows about the evaluation method of hardened | cured material property, ultraviolet curing was performed as follows.
<UV curing>
3 parts of Irgacure 184 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) was dissolved in 100 parts of the synthesized photocurable acrylate resin to obtain a photocurable coating composition. A predetermined base material was coated with 25 μm by an applicator, and irradiated with an irradiation distance of 10 cm with an ultraviolet irradiation apparatus having three 100 w / cm high-pressure mercury lamps, and irradiated with 500 mJ / cm 2.

<Flexibility>
A photocurable acrylate resin was applied onto a polyethylene terephthalate (PET) film substrate having a film thickness of 50 μm, and UV-cured under the above curing conditions to obtain a PET film having a cured coating film. Bending this PET film, visually confirming the cracks in the formed coating film,
○, when there is no crack when bent 180 °
△, which breaks at 180 ° but does not crack at 90 °
What breaks even at 90 degrees ×
It was.

<Transparency>
In accordance with ASTM D-1003, the haze value of a cured film cured with ultraviolet rays on a polycarbonate (PC) plate was measured using a haze meter.

○… Transparent and no turbidity in the cured coating (cloudiness 0 ~ 0.2%)
Δ: Slight turbidity in the cured film (cloudiness: 0.3 to 0.6%)
X: The turbidity of the cured coating can be clearly identified (cloudiness value of 0.7% or more)
<Adhesion>
A photocurable coating composition was applied to a polycarbonate (PC) plate and a polyethylene terephthalate (PET) film having a thickness of 50 μm, respectively, and photocured, and the adhesion was evaluated by a cross cut test (JIS K5600-5-6).

<Scratch resistance>
For a cured coating film obtained by photocuring on a polycarbonate (PC) plate, the haze value at a load of 500 g and 100 revolutions with a CS-10F wear wheel was measured by the Taber abrasion test method (JIS K5600-5-9). It was measured and evaluated with. Practically less than 2 is necessary.
[Evaluation results]

  The resin of the present invention can be suitably used as a raw material resin for a photo-curable coating that is cured by ultraviolet rays, radiation, electron beams, or the like. A photo-curable coating using this resin can be suitably used for building materials, molding materials, and the like, and exhibits excellent properties particularly in coatings applied to plastic films and moldings.

Claims (8)

The allophanate group containing (meth) acrylate resin characterized by including in the resin frame | skeleton the structure consisting of the allophanate group represented by following formula (1), and the structure consisting of the group represented by following formula (2).

(In the formula, R1 represents an aliphatic, alicyclic, or aromatic hydrocarbon group having 1 to 40 carbon atoms in total. However, these hydrocarbon groups may have a branch or a substituent. (You may have it.)

(In the formula, R2 represents an organic group having 1 to 50 carbon atoms in total, and R3 represents a hydrogen atom or a methyl group. However, the organic group R2 may have a branch or have a side chain. May be.)   2. The allophanate group-containing (meth) acrylate resin according to claim 1, which has at least two (meth) acrylate groups in one molecule of the resin.   The allophanate group-containing (meth) acrylate resin according to claim 1 or 2, wherein the allophanate group content is 0.2 to 5.0 mmol / g.   A paint comprising the allophanate group-containing (meth) acrylate resin according to claim 1.   A photocurable coating material comprising the allophanate group-containing (meth) acrylate resin according to claim 1 and a photopolymerization initiator. Hardened | cured material obtained by hardening | curing the composition containing the allophanate group containing (meth) acrylate resin in any one of Claims 1-3. Producing an allophanate group-containing polyisocyanate resin by reacting some of the isocyanate groups contained in the organic polyisocyanate prepolymer with a hydroxyl group contained in a monoalcohol having no unsaturated bond,
4. The isocyanate group remaining in the polyisocyanate resin is reacted with an active hydrogen group of an active hydrogen compound having at least one (meth) acrylate group in the molecule. Of producing an allophanate group-containing (meth) acrylate resin.   A resin composition for hard coat, comprising the allophanate group-containing (meth) acrylate resin according to claim 1.