Active energy ray-curable resin composition for adhesives

Abstract

To provide a urethane (meth)acrylate compound having excellent thermal stability and excellent handleability even though it is made from a polyol with an average number of functional groups of more than 2.0.SOLUTION: A urethane (meth)acrylate compound is a reaction product between a polyol (a1) with an average number of functional groups of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2), and satisfies the formula (1). Formula (1) X+0.2≥Z / Y≥X-0.2, where, X, Y, Z are as follows. X: an average number of functional groups of the polyol (a1), Y: a molar amount of charge of the polyol (a1), Z: a molar amount of charge of the isocyanate group-containing (meth)acrylate (a2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a urethane (meth)acrylate compound obtained by using, as a raw material, a polyol having an average functionality of more than 2.0. More specifically, the present invention relates to a urethane (meth)acrylate compound having good thermal stability and excellent handleability, and an active energy ray-curable resin composition containing the same. [Background technology]

[0002] Conventionally, urethane (meth)acrylate compounds obtained by reacting a diol compound such as a polyester diol or a polyether diol, a diisocyanate compound such as isophorone diisocyanate or diphenylmethane diisocyanate, and a hydroxyl group-containing (meth)acrylate compound such as hydroxyethyl (meth)acrylate have been known as active energy ray-curable resin compositions, and have been used in applications such as paints, coating agents, and adhesives.

[0003] In such urethane (meth)acrylate compounds, polyols having an average functionality of 2.0 or less are often used as the raw material for the polyol component in terms of gelation during the reaction and storage stability after the reaction. On the other hand, urethane (meth)acrylate compounds obtained using polyols with an average functionality of more than 2.0 are expected to have improved physical properties such as heat resistance and hardness, and for example, urethane (meth)acrylate compounds using castor oil have been proposed (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-26555 [Patent Document 2] Special Publication No. 58-5949 [Patent Document 3] Japanese Patent Application Publication No. 1-113478 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the urethane (meth)acrylate compounds in the above Patent Documents 1 to 3 use castor oil as a polyol component, and the average number of functional groups in castor oil is high at around 2.7, so the urethane (meth)acrylate compounds obtained from this have poor thermal stability.

[0006] Castor oil is an oil containing a triester compound of ricinoleic acid and glycerin. Of the fatty acids that make up the triester compound, ricinoleic acid accounts for approximately 90 mol%. The rest of the fatty acids include oleic acid, linoleic acid, linolenic acid, and other acids that lack hydroxyl groups. As a result, the average number of functional groups in castor oil is approximately 2.7.

[0007] Under these circumstances, the present invention aims to provide a urethane(meth)acrylate compound and an active energy ray-curable resin composition that are obtained by using a polyol having an average functionality of more than 2.0 as a raw material, and that have good thermal stability and excellent handleability, as well as a method for producing the urethane(meth)acrylate compound. [Means for solving the problem]

[0008] However, as a result of intensive research by the present inventors to solve the above-mentioned problems, it has been found that a urethane(meth)acrylate compound is prepared using a polyol (a1) having an average functionality of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2), and when the average functionality of the polyol component is more than 2.0, for example, when castor oil (including refined castor oil) is used as the polyol component, the average functionality of the hydroxyl group is usually around 2.7. Therefore, when this is reacted as it is with the isocyanate group-containing (meth)acrylate, gelation tends to occur during the reaction, and the desired urethane(meth)acrylate cannot be obtained. Acrylate compounds are difficult to obtain, and even if a desired urethane (meth)acrylate is obtained, it is not practical because it has high viscosity and poor handleability or poor thermal stability. However, it has been found that the above object can be achieved by optimizing the relationship between the average number of functional groups (X) of polyol (a1), the number of moles of polyol (a1) charged (Y moles), and the number of moles of isocyanate group-containing (meth)acrylate (a2) charged (Z moles), and that a urethane (meth)acrylate compound with good thermal stability and excellent handleability can be obtained, thereby completing the present invention.

[0009] That is, a first aspect of the present invention is a urethane (meth)acrylate compound which is a reaction product of a polyol (a1) having an average functionality of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2), and which satisfies the following formula (1): Formula (1)...X+0.2≧Z / Y≧X-0.2 Here, X, Y, and Z are as follows: X: Average number of functional groups of polyol (a1) Y: number of moles of polyol (a1) charged Z: number of moles of the isocyanate group-containing (meth)acrylate (a2) charged

[0010] Furthermore, a second gist of the present invention is an active energy ray-curable resin composition containing the urethane (meth)acrylate compound.

[0011] A third aspect of the present invention is a method for producing a urethane (meth)acrylate compound, which comprises reacting a polyol (a1) having an average functionality of more than 2.0 with an isocyanate group-containing (meth)acrylate (a2) under the conditions of the following formula (1): Formula (1)...X+0.2≧Z / Y≧X-0.2 Here, X, Y, and Z are as follows: X: Average number of functional groups of polyol (a1) Y: number of moles of polyol (a1) charged Z: number of moles of the isocyanate group-containing (meth)acrylate (a2) charged [Effects of the Invention]

[0012] The urethane (meth)acrylate compound of the present invention is a reaction product of a polyol (a1) having an average functionality of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2), and is obtained by optimizing the relationship between the average functionality (X) of the polyol (a1), the molar amount (Y moles) of the polyol (a1) charged, and the molar amount (Z moles) of the isocyanate group-containing (meth)acrylate (a2), and is a urethane (meth)acrylate compound with good thermal stability and excellent handleability. Furthermore, such a urethane (meth)acrylate compound is useful as a raw material for active energy ray-curable resin compositions that can be used in a variety of applications, such as coating agents, paints, inks, pressure-sensitive adhesives, and adhesives. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited to these.

[0014] In the present invention, (meth)acrylic means acrylic or methacrylic, and (meth)acrylate means acrylate or methacrylate, respectively.

[0015] The urethane (meth)acrylate compound of the present invention is a reaction product of a polyol (a1) having an average functionality of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2). Each component will be described below.

[0016] <Polyol (a1)> The polyol (a1) having an average functionality of more than 2.0 used in the present invention may be any polyol as long as its average functionality exceeds 2.0, and the lower limit of the average functionality is preferably 2.1, more preferably 2.3, and even more preferably 2.5. The upper limit is preferably 6.0, more preferably 5.0, even more preferably 4.0, and particularly preferably 3.0. If the average functionality is below the above range, physical properties such as heat resistance and hardness may be inferior. If the average functionality is above the above range, gelation during the reaction and storage stability after the reaction tend to be reduced.

[0017] The proportion of the polyol (a1) having an average functionality of more than 2.0 in all polyols is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 99 mol% or more.

[0018] A specific example of the polyol (a1) having an average functionality of more than 2.0 used in the present invention is castor oil. Castor oil is an oil and fat containing a triester compound of ricinoleic acid and glycerin. Of the fatty acids constituting the triester compound as a whole, ricinoleic acid accounts for approximately 90 mol %, and the remaining fatty acids include oleic acid, linoleic acid, linolenic acid, and the like, which lack hydroxyl groups. Therefore, the average functionality of castor oil is approximately 2.7. Furthermore, because castor oil is derived from plants and contains many impurities, it is preferable to use castor oil that has been purified by distillation or the like. Furthermore, because fatty acids such as ricinoleic acid contain unsaturated bonds, it is preferable to use hydrogenated castor oil.

[0019] Furthermore, examples of the polyol (a1) having an average functionality of more than 2.0 include partially dehydrated castor oil, polyols in which part of the ricinoleic acid has been substituted with a fatty acid that does not have a hydroxyl group, such as oleic acid, and polyols in which the hydroxyl groups of ricinoleic acid have been partially esterified with a monocarboxylic acid.

[0020] In addition to the above, examples of the polyol (a1) having an average functionality of more than 2.0 include cardanol-derived polyols, polyester polyols, and polycarbonate polyols.

[0021] The cardanol-derived polyol is synthesized from cardanol, an oily component contained in cashew nut shells, which is obtained as a by-product during the harvesting of cashew nuts. Cardanol is a compound in which a hydroxyl group and an aliphatic hydrocarbon group having 15 to 18 carbon atoms are bonded to an aromatic ring, and the chain contains one to three unsaturated bonds. This is condensed with formaldehyde, and then modified by the addition of ethylene oxide or the like to produce a polyol with an average functionality of more than 2.0. Examples of cardanol-derived polyols include Cardolite (registered trademark) NX-9001, NX-9007, and NX-9008 manufactured by Cardolite Corporation.

[0022] Examples of polyester polyols 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.

[0023] Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, and 1,9-nonanediol. diols such as bisphenol A, 2-methyl-1,8-octanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2,2-dimethylolheptane, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 2,4-diethyl-1,5-pentamethylenediol, hydrogenated bisphenol A, hydroxyalkylated bisphenol A, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, isosorbide, and 2,2,4-trimethyl-1,3-pentanediol; Examples of the polyhydric alcohol include tri- or higher functional alcohols such as glycerol, trimethylolmethane, trimethylolethane, trimethylolpropane, trimethylolbutane, 1,2,4-butanetriol, 1,2,3-hexanetriol, 1,2,4-hexanetriol, tris(hydroxymethyl)amine, tris(hydroxyethyl)amine, tris(hydroxypropyl)amine, pentaerythritol, diglycerol, triglycerol, polyglycerol, bis(trimethylolpropane), tris(hydroxymethyl)isocyanurate, tris(hydroxyethyl)isocyanurate, sugars such as glucose, and sugar derivatives such as sorbitol.

[0024] Examples of the polycarboxylic acid 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, and paraphenylenedicarboxylic acid. Examples of the polyvalent carboxylic acids include tri- or higher functional carboxylic acids such as trimellitic acids, pyromellitic acids, and trimesic acids.

[0025] The polyol (a1) used in the present invention has an average functionality of more than 2.0, and therefore, as a polyester polyol, is synthesized using at least one of a trifunctional or higher polyhydric alcohol and a trifunctional or higher polycarboxylic acid.

[0026] Examples of polycarbonate polyols include reaction products of polyhydric alcohols with phosgene; and transesterification products of carbonate esters with polyhydric alcohols.

[0027] Examples of the polyhydric alcohols include the diols and tri- or higher functional polyhydric alcohols, and examples of the carbonate esters include ethylene carbonate, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, and diphenyl carbonate.

[0028] The polyol (a1) used in the present invention has an average functionality of more than 2.0, and therefore, as a polycarbonate-based polyol, it is synthesized using at least one tri- or higher functional polyhydric alcohol.

[0029] <Isocyanate group-containing (meth)acrylate (a2)> The isocyanate group-containing (meth)acrylate (a2) used in the present invention can be obtained by reacting a polyisocyanate (a2-1) with a hydroxyl group-containing (meth)acrylate (a2-2) in a 1:1 (molar ratio).

[0030] Examples of the polyisocyanate (a2-1) include aliphatic polyisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate; and aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; as well as trimer compounds of the above polyisocyanates and polymeric compounds of the above polyisocyanates. Other examples include allophanate-type polyisocyanates, biuret-type polyisocyanates, etc. These may be used alone or in combination of two or more.

[0031] Among these, the polyisocyanate (a2-1) is preferably an aliphatic diisocyanate or an alicyclic diisocyanate, particularly preferably an aliphatic diisocyanate, from the viewpoint of the thermal stability of the urethane (meth)acrylate compound. Specifically, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, or hexamethylene diisocyanate is preferred, particularly isophorone diisocyanate.

[0032] The hydroxyl group-containing (meth)acrylate (a2-2) preferably has one hydroxyl group, and examples thereof include hydroxyalkyl (meth)acrylates 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 acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol mono(meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 2-hydroxy Hydroxyl group-containing (meth)acrylates containing one ethylenically unsaturated group, such as 3-(meth)acryloyloxypropyl (meth)acrylate; hydroxyl group-containing (meth)acrylates containing two ethylenically unsaturated groups, such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyloxypropyl methacrylate; and hydroxyl group-containing (meth)acrylates containing 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, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate. These can be used alone or in combination of two or more.

[0033] Among these, as the hydroxyl group-containing (meth)acrylate (a2-2), a hydroxyl group-containing (meth)acrylate containing one ethylenically unsaturated group is preferred in terms of adhesive properties, particularly when used for adhesive applications, and a hydroxyalkyl (meth)acrylate is more preferably used, and a hydroxyalkyl (meth)acrylate in which the alkyl group has 1 to 4 carbon atoms, particularly 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate, is particularly preferred. The isocyanate group-containing (meth)acrylate (a2) may be any of a biuret, a nurate, an adduct, and an allophanate, with the adduct being preferred.

[0034] In the present invention, the method for obtaining the isocyanate group-containing (meth)acrylate (a2) is not particularly limited, and a product synthesized by a conventionally known method or a commercially available product may be used. Examples of conventionally known production methods that can be suitably used include those described in JP 2002-138112 A and JP 2012-523385 A. An example of a commercially available product is "VESTANAT EP-DC 1241" manufactured by Evonik Corporation. This product is a monoadduct of isophorone diisocyanate, which is the polyisocyanate (a2-1), and 2-hydroxyethyl acrylate, which is the hydroxyl group-containing (meth)acrylate (a2-2), in a 1:1 (molar ratio).

[0035] <Urethane (meth)acrylate compounds> The urethane (meth)acrylate compound of the present invention is obtained by reacting the above components (a1) and (a2). In this case, it is important that the following formula (1) is satisfied. Even when a polyol (a1) having an average functionality of more than 2.0 is used as the polyol, gelation does not occur during the reaction due to the small number of branched structures, and the storage stability of the urethane (meth)acrylate compound after the reaction is good. In addition, a urethane (meth)acrylate compound with low viscosity and excellent handleability due to the narrow polydispersity can be obtained.

[0036] Formula (1)...X+0.2≧Z / Y≧X-0.2 Here, X, Y, and Z are as follows: X: Average number of functional groups of polyol (a1) Y: number of moles of polyol (a1) charged Z: number of moles of the isocyanate group-containing (meth)acrylate (a2) charged

[0037] The above formula (1) represents a technical idea of ​​completing the reaction while leaving as few reactive groups other than (meth)acrylate groups as possible, thereby improving storage stability. It is important that the number of moles (Z moles) of the isocyanate group-containing (meth)acrylate (a2) charged satisfies formula (1). If Z is too small or too large, reactive groups will remain, causing deterioration of storage stability.

[0038] In the reaction of the polyol (a1) having an average functionality of more than 2.0 with the isocyanate group-containing (meth)acrylate (a2), the urethane (meth)acrylate compound of the present invention can be obtained by terminating the reaction when the content of residual isocyanate groups in the reaction system is usually 0.1% by weight or less.

[0039] In the present invention, in the reaction between the polyol (a1) having an average functionality of more than 2.0 and the isocyanate group-containing (meth)acrylate (a2), it is preferable to use a catalyst to promote the reaction.

[0040] Examples of such catalysts include organometallic compounds such as dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octoate, tin octoate, cobalt naphthenate, stannous chloride, and stannic chloride; amine catalysts such as triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, and N-ethylmorpholine; bismuth nitrate, bismuth bromide, and bismuth iodide; Examples of suitable bismuth catalysts include bismuth, bismuth sulfide, and organic bismuth compounds such as dibutyl bismuth dilaurate and dioctyl bismuth dilaurate, and organic acid bismuth salts such as bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth bisneodecanoate, bismuth disalicylate, and bismuth digallate. Among these, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferred.

[0041] In addition, in the reaction between the polyol (a1) and the isocyanate group-containing (meth)acrylate (a2), an organic solvent that does not have a functional group that reacts with an isocyanate group, for example, an ester such as ethyl acetate or butyl acetate, a ketone such as methyl ethyl ketone or methyl isobutyl ketone, or an aromatic such as toluene or xylene, can be used.

[0042] The reaction temperature is usually 30 to 90°C, preferably 40 to 80°C, and the reaction time is usually 2 to 12 hours, preferably 3 to 10 hours.

[0043] Thus, the urethane (meth)acrylate compound of the present invention is obtained which has good thermal stability and excellent handleability.

[0044] In the present invention, the number average molecular weight of the urethane (meth)acrylate compound obtained above is preferably 500 to 15,000, more preferably 800 to 13,000, even more preferably 1,000 to 10,000, particularly preferably 1,200 to 8,000, and especially preferably 1,500 to 5,000. If the number average molecular weight is too small, the properties of the resin composition prepared using the urethane (meth)acrylate compound, such as adhesive properties when used as a pressure-sensitive adhesive, tend to be reduced, while if the number average molecular weight is too large, the viscosity of the resin composition tends to increase, resulting in problems such as reduced handleability and gelation.

[0045] The weight-average molecular weight of the urethane (meth)acrylate compound is preferably 1,000 to 100,000, more preferably 1,200 to 80,000, even more preferably 1,500 to 60,000, and particularly preferably 2,000 to 50,000. If the weight-average molecular weight is too small, the properties of a resin composition prepared using the urethane (meth)acrylate compound, such as adhesive properties when used as a pressure-sensitive adhesive, tend to be reduced, whereas if the weight-average molecular weight is too large, the viscosity of the resin composition tends to increase, resulting in problems such as reduced handleability and gelation.

[0046] In the present invention, the dispersity (weight average molecular weight / number average molecular weight) of the urethane (meth)acrylate compound is preferably 2.0 or less, more preferably 1.8 or less, particularly preferably 1.6 or less, even more preferably 1.4 or less, and especially preferably 1.3 or less, from the viewpoint of ease of handling. If the dispersity is too high, the viscosity of the urethane (meth)acrylate compound increases, resulting in problems such as poor handling. The lower limit of the dispersity is usually 1.0.

[0047] The number-average molecular weight and weight-average molecular weight are measured in terms of standard polystyrene molecular weight using a high-performance liquid chromatograph (Waters, "ACQUITY Advanced Polymer Chromatography (APC) System") equipped with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45. If the sample contains an ethylenically unsaturated monomer (B), the number-average molecular weight and weight-average molecular weight are determined excluding the ethylenically unsaturated monomer (B). In the present invention, "APC measurement" refers to measurement using the APC system.

[0048] Furthermore, the viscosity of the urethane (meth)acrylate compound obtained by the present invention at 60°C is preferably 1,000,000 mPa·s or less, more preferably 80,000 mPa·s or less, even more preferably 50,000 mPa·s or less, particularly preferably 30,000 mPa·s or less, and especially preferably 20,000 mPa·s or less. If the viscosity is too high, handling properties tend to be reduced. Here, the viscosity is measured using an E-type viscometer.

[0049] In the present invention, the active energy ray-curable resin composition containing the urethane (meth)acrylate compound of the present invention obtained above (hereinafter, the urethane (meth)acrylate compound of the present invention may be referred to as the urethane (meth)acrylate compound (A)) can be used for various applications, but it is particularly preferable to add an ethylenically unsaturated monomer (B) to form an active energy ray-curable resin composition.

[0050] <Ethylenically unsaturated monomer (B)> The ethylenically unsaturated monomer (B) used in the present invention may be any ethylenically unsaturated monomer having one or more ethylenically unsaturated groups in one molecule, and examples thereof include monofunctional monomers, difunctional monomers, and trifunctional or higher functional monomers.

[0051] The monofunctional monomer may be any monomer containing one ethylenically unsaturated group, and examples thereof include styrene, vinyltoluene, chlorostyrene, α-methylstyrene, methyl(meth)acrylate, ethyl(meth)acrylate, acrylonitrile, vinyl acetate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, phenoxyethyl(meth)acrylate, and 2-phenoxy-2-hydroxypropyl. Chloropropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, nonylphenol propylene oxide modified (meth)acrylate, half ester (meth)acrylate of phthalic acid derivatives such as 2-(meth)acryloyloxy-2-hydroxypropyl phthalate acrylate, tetrahydrofurfuryl (meth)acrylate, carbitol (meth)acrylate, benzyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, allyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl acrylamide, N-methylol (meth)acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, 2-(meth)acryloyloxyethyl acid phosphate monoester, and the like.

[0052] In addition to the monofunctional monomers, Michael adducts of acrylic acid and 2-acryloyloxyethyl dicarboxylic acid monoesters can also be used. Examples of Michael adducts of acrylic acid include acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, and methacrylic acid tetramer. Examples of 2-acryloyloxyethyl dicarboxylic acid monoesters, which are carboxylic acids having specific substituents, include 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester, and 2-methacryloyloxyethyl hexahydrophthalic acid monoester. Oligoester acrylates can also be used.

[0053] The bifunctional monomer may be any monomer containing two ethylenically unsaturated groups, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, propylene oxide-modified bisphenol A di(meth)acrylate, Examples of suitable diglycidyl esters include 1,6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide-modified di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid-modified neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide-modified diacrylate, and 2-(meth)acryloyloxyethyl acid phosphate diester.

[0054] The tri- or higher functional monomer may be any monomer containing three or more ethylenically unsaturated groups, and examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanuric acid ethylene oxide modified triacrylate, ethylene oxide modified dipentaerythritol penta(meth)acrylate, Examples of the dipentaerythritol tetra(meth)acrylate include ethylene oxide-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified pentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, and succinic acid-modified pentaerythritol tri(meth)acrylate.

[0055] Furthermore, as the ethylenically unsaturated monomer (B), a urethane (meth)acrylate compound obtained by reacting a polyisocyanate compound with a (meth)acrylate compound containing one hydroxyl group, or a urethane (meth)acrylate compound obtained by reacting a polyisocyanate compound, a (meth)acrylate compound containing one hydroxyl group, and a polyol compound (however, excluding the urethane (meth)acrylate compound (A)) may be used.

[0056] In the present invention, among the ethylenically unsaturated monomers (B), when the active energy ray-curable resin composition is used as an adhesive, it is preferable to use a monofunctional monomer, and an alicyclic monofunctional monomer is more preferable, for example, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, etc., and among them, isobornyl (meth)acrylate is the most preferable.

[0057] These ethylenically unsaturated monomers (B) may be used alone or in combination of two or more. The ethylenically unsaturated monomer (B) may be added separately to the urethane (meth)acrylate compound (A), or may be present in part or in whole in the system during production as a raw material for the urethane (meth)acrylate compound (A). Furthermore, the ethylenically unsaturated monomer (B) may be contained as a reaction solvent in the reaction of (a1) and (a2).

[0058] In the present invention, the content of the ethylenically unsaturated monomer (B) is preferably 20 to 400 parts by weight, more preferably 30 to 300 parts by weight, even more preferably 40 to 200 parts by weight, particularly preferably 50 to 150 parts by weight, and especially preferably 60 to 100 parts by weight, per 100 parts by weight of the urethane (meth)acrylate compound (A), in terms of adhesive strength when used as an adhesive. If the content of the ethylenically unsaturated monomer (B) is too low or too high, it tends to be difficult to obtain sufficient adhesive strength when used as an adhesive.

[0059] <Photopolymerization initiator (C)> In the present invention, the active energy ray-curable resin composition preferably further contains a photopolymerization initiator (C) in order to more efficiently carry out curing with active energy rays.

[0060] Examples of the photopolymerization initiator (C) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)-phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy- Acetophenones such as 2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, and phenylglyoxylic acid methyl ester; Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo benzophenones such as (4-benzoylbenzyl)trimethylammonium chloride and (2-propenyloxy)ethyl]benzenemethanaminium bromide; thioxanthones such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride;Examples include acylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. These photopolymerization initiators (C) may be used alone or in combination of two or more.

[0061] In addition, these auxiliary agents can also be used in combination with triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and the like.

[0062] Among these, it is preferable to use benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin isopropyl ether, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl) ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one.

[0063] The content of the photopolymerization initiator (C) is preferably 0.1 to 40 parts by weight, more preferably 0.5 to 20 parts by weight, and even more preferably 1 to 10 parts by weight, per 100 parts by weight of the total of the urethane (meth)acrylate compound (A) and the ethylenically unsaturated monomer (B). If the content of the photopolymerization initiator (C) is too low, curing tends to be insufficient, while if it is too high, solution stability tends to decrease, such as precipitation when applied, and problems such as embrittlement and coloration tend to occur.

[0064] In producing the active energy ray-curable composition of the present invention, the method for mixing the urethane (meth)acrylate compound (A), the ethylenically unsaturated monomer (B), and the photopolymerization initiator (C) is not particularly limited, and they can be mixed by various methods. For example, the methods can be appropriately selected, such as mixing all the components at once, or mixing any of the components first and then mixing the remaining components.

[0065] Thus, the active energy ray-curable resin composition of the present invention is obtained. If necessary, a surface conditioner, a leveling agent, a polymerization inhibitor, etc. may be further added.

[0066] The surface conditioner is not particularly limited, and examples thereof include alkyd resins. Such alkyd resins have the effect of imparting film-forming properties during coating and the effect of increasing adhesion to the surface of a thin metal film.

[0067] As the leveling agent, any known leveling agent can be used as long as it has the effect of imparting wettability to the substrate and reducing the surface tension of the coating liquid, such as silicone-modified resins, fluorine-modified resins, alkyl-modified resins, etc. These can be used alone or in combination of two or more kinds.

[0068] Examples of polymerization inhibitors include p-benzoquinone, naphthoquinone, toluquinone, 2,5-diphenyl-p-benzoquinone, hydroquinone, 2,5-di-t-butylhydroquinone, methylhydroquinone, methoxyphenol, 2,6-di-t-butyl-p-cresol, mono-t-butylhydroquinone, and pt-butylcatechol. Among these, methoxyphenol and 2,6-di-t-butyl-p-cresol are preferred. These can be used alone or in combination of two or more.

[0069] In the present invention, when the active energy ray-curable resin composition is used for various applications, it is applied to various substrates or members, dried in the case where an organic solvent is contained, and then cured by irradiating with active energy rays.

[0070] The method for applying the active energy ray-curable resin composition is not particularly limited, and examples thereof include wet coating methods such as spraying, showering, dipping, rolling, spinning, curtain, flow, slit, die, gravure, comma, dispenser, screen printing, and inkjet printing.

[0071] The coating may be carried out by blending an organic solvent, if necessary, to adjust the viscosity, and examples of such organic solvents include alcohols such as methanol, ethanol, propanol, n-butanol, and i-butanol, ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, cellosolves such as ethyl cellosolve, aromatic compounds such as toluene and xylene, glycol ethers such as propylene glycol monomethyl ether, acetates such as methyl acetate, ethyl acetate, and butyl acetate, diacetone alcohol, etc. These organic solvents may be used alone or in combination of two or more.

[0072] In addition, when the active energy ray-curable resin composition is a solid or a highly viscous liquid, a hot melt method may be used in which the active energy ray-curable resin composition is heated to reduce the viscosity and then coated by the above method.

[0073] Examples of such active energy rays that can be used include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays, electromagnetic waves such as X-rays and gamma rays, as well as electron beams, proton beams, and neutron beams, but curing by ultraviolet irradiation is advantageous in terms of curing speed, ease of availability of irradiation equipment, cost, etc. When electron beam irradiation is performed, curing can occur even without using a photopolymerization initiator (C).

[0074] For curing by ultraviolet irradiation, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, electrodeless discharge lamps, LEDs, etc. that emit light in the 150 to 450 nm wavelength range are used, with an intensity of 30 to 3,000 mJ / cm. 2 It is enough to irradiate it to some extent. After the ultraviolet irradiation, heating may be carried out as necessary to ensure complete curing.

[0075] The thickness of the cured coating film is usually 1 to 300 μm, preferably 2 to 250 μm, and more preferably 5 to 200 μm, in consideration of light transmission so that the photopolymerization initiator (C) can react uniformly.

[0076] Examples of substrates to which the active energy ray-curable resin composition obtained by the present invention can be applied include polyolefin resins, polyester resins, polycarbonate resins, acrylonitrile butadiene styrene copolymers (ABS), polystyrene resins, polyamide resins, etc., and molded products thereof (films, sheets, cups, etc.), metal substrates (metal vapor deposition layers, metal plates (copper, stainless steel (SUS304, SUSBA, etc.), aluminum, zinc, magnesium, etc.)), glass, etc., and composite substrates thereof.

[0077] In the present invention, a urethane (meth)acrylate compound which is a reaction product of a polyol (a1) having an average functionality of more than 2.0 and an isocyanate group-containing (meth)acrylate (a2) and satisfies the above formula (1) is very useful as a urethane (meth)acrylate compound having good thermal stability and excellent handleability. [Example]

[0078] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight. The number average molecular weight, weight average molecular weight and viscosity of the urethane (meth)acrylate compound were measured according to the methods described above.

[0079] As the polyol (a1) having an average functionality of more than 2.0, the following "ELA-DR" was used. "ELA-DR": Toyokuni Oil Mill, castor oil (hydroxyl value 161.0 mg KOH / g, average functionality 2.7)

[0080] As the isocyanate group-containing (meth)acrylate (a2), the following "VESTANAT EP-DC 1241" was used. VESTANAT EP-DC 1241: Evonik, 1:1 monoadduct of isophorone diisocyanate and 2-hydroxyethyl acrylate (molecular weight 338.4)

[0081] Example 1 [Preparation of urethane acrylate (A-1)] A flask equipped with an internal thermometer, stirrer, and condenser was charged with 482.0 parts of "ELA-DR" as a polyol (a1) with an average functionality greater than 2.0, 468.0 parts of "VESTANAT EP-DC 1241" as an isocyanate group-containing (meth)acrylate (a2), 0.06 parts of dibutyltin dilaurate as a reaction catalyst, and 0.05 parts of 2,6-di-t-butyl-p-cresol and 0.38 parts of 4-methoxyphenol as polymerization inhibitors. The reaction was terminated when the residual isocyanate group content reached 0.1% or less, yielding a composition containing urethane acrylate (A-1). The number average molecular weight, weight average molecular weight, dispersity, and viscosity of the resulting urethane acrylate (A-1)-containing composition are shown in Table 1. The thermal stability of the composition containing the urethane acrylate (A-1) obtained above was evaluated by the following method.

[0082] [Confirmation of thermal stability] The composition containing the urethane acrylate (A-1) obtained above was heated for 1 day at 60° C., and then checked for the presence or absence of gelation. The results are shown in Table 1.

[0083] <Comparative Example 1> A flask equipped with an internal thermometer, stirrer, and condenser was charged with 290.3 parts of isophorone diisocyanate (IPDI) as the polyisocyanate (a2-1), 455.2 parts of "ELA-DR" as the polyol (a1) with an average functionality of more than 2.0, and 0.06 parts of dibutyltin dilaurate as a reaction catalyst, and the mixture was allowed to react at 70 ° C. After the residual isocyanate group content reached 7.4% or less, 154.5 parts of 2-hydroxyethyl acrylate (HEA) as the hydroxyl group-containing acrylate (a2-2), 0.05 parts of 2,6-di-t-butyl-p-cresol and 0.36 parts of 4-methoxyphenol as polymerization inhibitors, were added, and the mixture was allowed to react at 70 ° C. However, gelation occurred during the reaction, and the desired urethane acrylate was not obtained.

[0084] <Comparative Example 2> In a flask equipped with an internal thermometer, a stirrer, and a condenser, 480.5 parts of "ELA-DR" as a polyol (a1) having an average functionality of more than 2.0, 121.0 parts of "VESTANAT EP-DC 1241" as an isocyanate group-containing (meth)acrylate (a2), 0.06 parts of dibutyltin dilaurate as a reaction catalyst, 0.05 parts of 2,6-di-t-butyl-p-cresol as a polymerization inhibitor, and 0.38 parts of 4-methoxyphenol were added and reacted at 70 ° C. After the residual isocyanate group reached 0.3% or less, 227.0 parts of isophorone diisocyanate (IPDI) as a polyvalent isocyanate (a2-1) was added and reacted at 70 ° C. After that, when the residual isocyanate group reached 5.2% or less, 121.5 parts of 2-hydroxyethyl acrylate (HEA) was added and the reaction was continued at 70°C. The reaction was terminated when the residual isocyanate group reached 0.1% or less, yielding a composition containing urethane acrylate (A'-1). The number average molecular weight, weight average molecular weight, and dispersity of the obtained urethane acrylate (A'-1) are shown in Table 1. The thermal stability of the composition containing the urethane acrylate (A'-1) obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0085] [Table 1]

[0086] From the results in Table 1 above, it can be seen that the urethane acrylate of Example 1 is a urethane acrylate-based compound that uses a polyol having an average functionality of more than 2.0 as a raw material, but by adjusting the amount (Z moles) of the isocyanate group-containing (meth)acrylate (a2) charged so as to satisfy formula (1), it was possible to obtain a urethane acrylate-based compound that was free from gelation during the reaction, had good storage stability after the reaction, and had low viscosity and excellent handleability due to its narrow polydispersity. In contrast, in Comparative Example 1, the amounts of diisocyanate and hydroxyl group-containing acrylate did not satisfy the requirements of the present application, resulting in gelation during the reaction and failure to obtain the desired urethane acrylate. Also, in Comparative Example 2, an isocyanate group-containing (meth)acrylate (a2) was used, but the amount charged did not satisfy formula (1), resulting in poor thermal stability of the resulting urethane acrylate compound and making it substantially unusable. [Industrial Applicability]

[0087] The urethane (meth)acrylate compound of the present invention is a urethane (meth)acrylate compound having good thermal stability, and such a urethane (meth)acrylate compound is useful as a raw material for active energy ray-curable resin compositions that can be used in various applications, such as coating agents, paints, inks, pressure-sensitive adhesives, and adhesives.

Claims

1. An active energy ray-curable resin composition for adhesives, comprising a urethane (meth)acrylate compound (A) and an ethylenically unsaturated monomer (B), The urethane (meth)acrylate compound (A) is a reaction product of a polyol (a1) having an average functionality of more than 2.0 and not more than 6.0 and an isocyanate group-containing (meth)acrylate (a2), satisfies the following formula (1), and has a polydispersity (Mw / Mn) measured by APC of 2.0 or less: The active energy ray-curable resin composition for pressure-sensitive adhesives, wherein the polyol (a1) is a polyol derived from castor oil. Formula (1)...X+0.2≧Z / Y≧X-0.2 Here, X, Y, and Z are as follows: X: average number of functional groups of polyol (a1) Y: number of moles of polyol (a1) charged Z: number of moles of the isocyanate group-containing (meth)acrylate (a2) charged

2. 2. The active energy ray-curable resin composition for pressure-sensitive adhesives according to claim 1, wherein the isocyanate group-containing (meth)acrylate (a2) is a monoadduct of an alicyclic polyisocyanate and an aliphatic hydroxyl group-containing (meth)acrylate.

3. An active energy ray-curable resin composition for adhesives as described in claim 1 or 2, wherein the content of the ethylenically unsaturated monomer (B) is 40 to 400 parts by weight per 100 parts by weight of the urethane (meth)acrylate compound (A).

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