JP6904047B2 - An active energy ray-curable adhesive composition and an adhesive composition for an acrylic resin member using the same. - Google Patents

Description

The present invention relates to an active energy ray-curable adhesive composition. More specifically, the present invention can obtain an adhesive layer having excellent adhesiveness to an acrylic resin and excellent hardness, and is also excellent in coatability. It relates to an adhesive composition.

A transparent base material is required for optical devices such as touch panels and optical members such as optical recording media, and glass base materials have been used conventionally. However, in recent years, electronic materials have been used from the viewpoint of impact resistance and weight reduction. The use of acrylic resin as a so-called glass substitute, such as replacing the glass protective cover or glass substrate used for the display of equipment with a cover or substrate made of acrylic resin, is expanding, and acrylic resin and others. There is a demand from the market for an active energy ray-curable adhesive having excellent adhesiveness to the base material (member) of the above. Adhesives used in such applications are required to have high adhesiveness, and sometimes adhesiveness to a level at which the bonded members cannot be peeled off is also required.

However, while an acrylic resin made of polymethylmethacrylate or the like has characteristics suitable for glass replacement such as high transparency and high hardness, it is generally known to be a poorly adhesive member.

Further, depending on the application, the hardness of the adhesive layer itself is also required. As an example, in the adhesion between a hard coat film to which functionality has been imparted and an acrylic resin base material, if the film thickness of the hard coat film is thin, it is greatly affected by the hardness of the underlying adhesive layer, so the hard coat film In order to bring out the original hardness, an active energy ray-curable adhesive having higher hardness is required.

So far, as an active energy ray-curable pressure-sensitive adhesive applicable to adhesion to acrylic resins, a resin composition for an ultraviolet-curable pressure-sensitive adhesive containing an isocyanate group-containing urethane acrylate and a compound having an ethylenically unsaturated bond ( For example, Patent Document 1) and a resin composition for an ultraviolet curable pressure-sensitive adhesive containing a polyester urethane acrylate compound made from an aliphatic diol compound having a branched structure and a compound having an ethylenically unsaturated bond (for example, Patent). Document 2) is disclosed.

Japanese Unexamined Patent Publication No. 2013-569666 Japanese Unexamined Patent Publication No. 2014-5368

However, in the technique disclosed in Cited Document 1, sufficient adhesiveness cannot be obtained only by irradiating the resin composition with ultraviolet rays, and it takes time to cure until the final adhesive strength is reached, and isocyanate. There is also a problem that the storage stability is inferior because the group remains in the system. Further, the technique disclosed in Cited Document 2 was insufficient in hardness and moisture heat resistance.

In the active energy ray-curable adhesive for adhesion to acrylic resin members, in addition to adhesiveness to acrylic resin, coating suitability, curability, hardness, transparency, moist heat resistance, storage stability, etc. are required. There are many items to be applied, and an active energy ray-curable adhesive that is well-balanced and excellent in all of these has not been obtained so far.

Therefore, the present invention provides an adhesive composition having excellent coatability and adhesiveness to an acrylic resin under such a background, and also having excellent hardness when cured. It is the purpose.

However, as a result of diligent studies, the present inventors have obtained an adhesive composition containing an unsaturated compound (A) having one ethylenically unsaturated group and a urethane (meth) acrylate-based compound (B), which is ethylene. The unsaturated compound (A) having one sex-unsaturated group has a cyclic structure, and the urethane (meth) acrylate-based compound (B) has an ether structure and / or a carbonate structure, and these are used. The present invention has been completed by finding that the adhesive composition contained in a specific ratio exhibits high adhesiveness to an acrylic resin, and is also excellent in coatability and hardness of the adhesive layer after curing.

That is, the gist of the present invention is an active energy ray-curable adhesive composition containing an unsaturated compound (A) having one ethylenically unsaturated group and a urethane (meth) acrylate-based compound (B). , The unsaturated compound (A) having one ethylenically unsaturated group has a cyclic structure, the urethane (meth) acrylate compound (B) has an ether structure and / or a carbonate structure, and an ethylenically unsaturated group. The content ratio (weight ratio) of the unsaturated compound (A) having one of the unsaturated compounds (A) and the urethane (meth) acrylate-based compound (B) is (A) :( B) = 99: 1 to 50:50. It relates to a curable adhesive composition.

The present invention also provides an adhesive composition for an acrylic resin member using the active energy ray-curable adhesive composition.

The active energy ray-curable pressure-sensitive adhesive composition obtained by the present invention is excellent in adhesiveness to various resin members, particularly adhesiveness to acrylic resins, and further, coatability and an adhesive after curing. It also has a well-balanced and excellent effect on the hardness of the layer, and is therefore particularly useful as an adhesive for an acrylic resin member that adheres a member made of an acrylic resin (acrylic film or the like) to another member.

Hereinafter, the present invention will be described in detail, and these are examples of desirable embodiments.
In the present invention, (meth) acrylic acid refers to acrylic acid or methacrylic acid, (meth) acrylic refers to acrylic or methacrylic acid, (meth) acryloyl refers to acryloyl or methacryloyl, and (meth) acrylate refers to acrylate or methacrylic acid. It means each methacrylate. The acrylic resin is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate-based monomer.

[Unsaturated compound (A) having one ethylenically unsaturated group]
The active energy ray-curable adhesive composition of the present invention contains an unsaturated compound (A) having one ethylenically unsaturated group as an essential component, and the unsaturated compound having one ethylenically unsaturated group ( A) needs to have an annular structure.

Examples of the unsaturated compound (A) having one ethylenically unsaturated group include an alicyclic structure such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate (meth). Acrylate compound; (meth) acrylate compound having a benzene ring such as benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxybenzyl (meth) acrylate;
Tetrahydrofurfuryl (meth) acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl (meth) acrylate, cyclic trimethylolpropaneformal (meth) acrylate, (3-ethyloxetane-3) -A (meth) acrylate compound having a cyclic ether structure such as methyl (meth) acrylate, (3-ethyloxetane-3-yl) methyl (meth) methacrylate, and acryloyl morpholine;
And so on.
The unsaturated compound (A) having one of these ethylenically unsaturated groups can be used alone or in combination of two or more.

Among these, from the viewpoint of adhesion to an acrylic resin, it is preferable to use a (meth) acrylate compound having a benzene ring or a cyclic ether structure as the cyclic structure, and particularly preferably, benzyl (meth) acrylate and cyclic trimethylol. Propaneformal (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and more preferably, benzyl (meth) acrylate is excellent in a good balance between adhesiveness to an acrylic resin and hardness when cured.

The unsaturated compound (A) having one ethylenically unsaturated group may be separately blended with the urethane (meth) acrylate compound (B) described later, or may be a urethane (meth) acrylate. It may be blended as a diluent during the production of the system compound (B), but it is preferably blended separately with the urethane (meth) acrylate compound (B).

[Urethane (meth) acrylate compound (B)]
The urethane (meth) acrylate-based compound (B) used in the present invention is a urethane (meth) acrylate-based compound having an ether structure and / or a carbonate structure.
The urethane (meth) acrylate-based compound (B) may have an ether structure and / or a carbonate structure in the compound, but the urethane (meth) acrylate-based compound (B) preferably has an ether structure and / or a carbonate structure. / Or a compound derived from a polyol having a carbonate structure, for example, the urethane (meth) acrylate compound (B) is a polyvalent isocyanate compound (b1), a hydroxyl group-containing (meth) acrylate compound (b2) and , The polyol compound (b3) is obtained as a reaction product of the polyol compound (b3), and the polyol compound (b3) is a polyol compound (b3-1) having an ether structure (however, a compound having a carbonate structure is excluded. ), A polyol compound having a carbonate structure (b3-2) (excluding a compound having an ether structure), and at least one selected from a polyol compound having both an ether structure and a carbonate structure (b3-3). It is particularly preferable that it is a polyol compound containing.

Examples of the polyvalent isocyanate-based compound (b1) include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylenedi isocyanate, and naphthalene. Aromatic polyisocyanates such as diisocyanates; aliphatic polyisocyanates such as pentamethylene diisocyanates, hexamethylene diisocyanates, trimethylhexamethylene diisocyanates, lysine diisocyanates and lysine triisocyanates; isophorone diisocyanates, 1,3-bis (isocyanato) cyclohexane, 1 , 4-Bis (isocyanato) cyclohexane, norbornene diisocyanate, alicyclic polyisocyanate such as 4,4'-dicyclohexylmethane diisocyanate, or trimeric compound or multimer compound of these polyisocyanates; allophanate type polyisocyanate, bullet type Examples include polyisocyanate.
These can be used alone or in combination of two or more.

Among these, aliphatic diisocyanates and alicyclic diisocyanates are preferably used because they cause less yellowing, and isophorone diisocyanates and 1,3-bis (isophorone diisocyanates) are particularly preferable because they are excellent in reactivity and versatility. Isocyanato) Cyclohexane and 4,4'-dicyclohexylmethane diisocyanate are used.

Examples of the hydroxyl group-containing (meth) acrylate compound (b2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth). ) Acrylate, hydroxyalkyl (meth) acrylate such as 6-hydroxyhexyl (meth) acrylate, 2-hydroxyethylacryloyl phosphate, 2- (meth) acryloyloxyethyl-2-hydroxypropylphthalate, caprolactone-modified 2-hydroxyethyl ( Meta) acrylate, dipropylene glycol (meth) acrylate, fatty acid-modified-glycidyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropyl A hydroxyl group-containing (meth) acrylate-based compound containing one ethylenically unsaturated group such as (meth) acrylate; an ethylenically unsaturated group such as glycerindi (meth) acrylate and 2-hydroxy-3-acryloyl-oxypropyl methacrylate. Pentaerythritol tri (meth) acrylate, caprolactone-modified pentaerythritol tri (meth) acrylate, ethylene oxide-modified pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) Examples thereof include hydroxyl group-containing (meth) acrylate compounds containing three or more ethylenically unsaturated groups such as acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate, and ethylene oxide-modified dipentaerythritol penta (meth) acrylate.
These hydroxyl group-containing (meth) acrylate compounds (b2) can be used alone or in combination of two or more.

Among these, a hydroxyl group-containing (meth) acrylate-based compound having one ethylenically unsaturated group is preferable in that it has a good balance between adhesion to an adherend and hardness when formed into an adhesive layer, and is particularly preferable. Preferably, hydroxy such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and the like. Alkyl (meth) acrylate, more preferably 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4 in terms of excellent reactivity and versatility. -Hydroxybutyl (meth) acrylate.

The above-mentioned polyol compound having an ether structure (b3-1) (however, the compound having a carbonate structure is excluded) (hereinafter, it may be referred to as "polyol compound having an ether structure (b3-1)"). Examples thereof include polyether polyols, and specific examples thereof include polyalkylene glycols having an oxyalkylene structure such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, and polyhexamethylene glycol, and polyalkylene glycols thereof. A branched structure using linear-structured polyether polyols such as random or block copolymers of alkylene glycol, trivalent or higher alcohols such as glycerin and trimethylolpropane, and trivalent or higher amines such as ethylenediamine as raw materials. Examples thereof include a polyether polyol containing a branched polyether chain (a structure containing a branched polyether chain).

Among these, a polyether polyol having a linear structure is preferable from the viewpoint of a balance between adhesiveness to an acrylic resin and hardness when cured, and further, polytetramethylene ether glycol and polypropylene glycol are preferable.

The polyol compound (b3-1) having an ether structure can be used alone or in combination of two or more.

The above-mentioned polyol compound having a carbonate structure (b3-2) (however, the compound having an ether structure is excluded) (hereinafter, it may be referred to as "polyol compound having a carbonate structure (b3-2)"). Examples thereof include polycarbonate-based polyols, and specifically, for example, a reaction product of a polyhydric alcohol and a carbonic acid ester, a reaction product of a polyhydric alcohol and a phosgen, and a polyhydric alcohol and a cyclic carbonate (alkylene carbonate, etc.). Ring-opening polymers and the like can be mentioned.

Examples of the polyhydric alcohol used as a raw material for the polycarbonate-based polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, and 2-methyl-. 1,3-Trimethylenediol, 1,4-Butanediol, 1,5-Pentamethylenediol, Neopentyl glycol, 1,6-Hexamethylenediol, 3-Methyl-1,5-Pentamethylenediol, 2,4 -Diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), bisphenols (bisphenol A, etc.), polyolics (xylitol, sorbitol, etc.) ) And so on.

Examples of the alkylene carbonate used as a raw material for the polycarbonate-based polyol include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

As the polyol compound (b3-3) having both the ether structure and the carbonate structure, for example, as the polyhydric alcohol as a raw material of the polycarbonate-based polyol, a polyhydric alcohol having an ether structure such as diethylene glycol and dipropylene glycol can be used. Examples thereof include polyol-based compounds having both an ether structure and a carbonate structure obtained by producing a polycarbonate-based polyol.

Among the polyol compounds (b3-2) having a carbonate structure and the polyol compounds (b3-3) having both an ether structure and a carbonate structure, the linear structure (b3-3) has an excellent adhesiveness to an acrylic resin. A polycarbonate-based polyol having a structure that does not contain branched polycarbonate chains) is preferable.

The polyol compound (b3-1) having an ether structure, the polyol compound (b3-2) having a carbonate structure, and the polyol compound (b3-3) having both an ether structure and a carbonate structure are each independently. It may be used, or two or more kinds may be used in combination.

In the present invention, it is preferable to use a polyol compound (b3-1) having an ether structure from the viewpoint of adhesiveness to a member (particularly an acrylic resin member), and the hardness when cured. Therefore, it is preferable to use a polyol compound (b3-2) having a polycarbonate structure.

Further, in the present invention, when the urethane (meth) acrylate compound (B) having both an ether structure and a carbonate structure is used, the polyol compound (b3) is a polyol compound having both an ether structure and a carbonate structure. It may be produced by using the compound (b3-3), and may be a polyol compound (b3-1) having an ether structure, a polyol compound (b3-2) having a polycarbonate structure, and / or ether. It may be produced in combination with a polyol compound (b3-3) having both a structure and a carbonate structure.

In the present invention, other polyol compounds having no ether structure and carbonate structure can be used in combination as the polyol compound (b3) as long as the effects of the present invention are not impaired. For example, polyester-based polyols, polyolefin-based polyols, (meth) acrylic-based polyols, polysiloxane-based polyols, and the like can be mentioned.

In the present invention, the number average molecular weight of the polyol compound (b3) is preferably 300 to 10,000, particularly preferably 400 to 5,000, and even more preferably 500 to 2,000. If the number average molecular weight is too small, the adhesive force with the adherend tends to decrease, and if it is too large, the unsaturated group concentration of the obtained urethane (meth) acrylate compound (B) decreases, and the adhesive composition When it is used, the curability and the hardness when cured tend to be insufficient.
The above number average molecular weight is calculated from the hydroxyl value of each polyol.

Further, in the present invention, the number of hydroxyl groups contained in the polyol compound (b3) is preferably 2 to 5, particularly preferably 2 to 3, and even more preferably 2. If the number of hydroxyl groups is too large, gelation tends to occur during the reaction.

The hydroxyl value of the polyol compound (b3) is preferably 10 to 400 mgKOH / g, particularly preferably 20 to 300 mgKOH / g, and even more preferably 50 to 200 mgKOH / g. If the hydroxyl value is too high, the urethane (meth) acrylate compound tends to have a low molecular weight and the adhesive force with the adherend tends to decrease, and if it is too low, the obtained urethane (meth) acrylate compound and the urethane (meth) acrylate compound contained therein are contained. Since the adhesive composition becomes highly viscous and the coatability is lowered, the workability tends to be lowered.

The urethane (meth) acrylate compound (B) used in the present invention is, for example,
(1) A method in which the above-mentioned polyisocyanate compound (b1), hydroxyl group-containing (meth) acrylate compound (b2), and polyol compound (b3) are collectively or separately charged into a reactor and reacted.
(2) A method of reacting a hydroxyl group-containing (meth) acrylate compound (b2) with a reaction product obtained by reacting a polyhydric isocyanate compound (b1) with a polyol compound (b3) in advance.
(3) A method of reacting a polyol compound (b3) with a reaction product obtained by reacting a polyhydric isocyanate compound (b2) with a hydroxyl group-containing (meth) acrylate compound (b1) in advance.
However, the method (2) is preferable from the viewpoint of reaction stability and reduction of by-products.

A known reaction means can be used for the reaction between the polyisocyanate compound (b1) and the polyol compound (b3). At that time, for example, the molar ratio of the isocyanate group in the polyhydric isocyanate compound (b1) to the hydroxyl group in the polyol compound (b3) is usually about 2n: (2n-2) (n is an integer of 2 or more). By doing so, a terminal isocyanate group-containing urethane (meth) acrylate-based compound in which an isocyanate group remains can be obtained, and after the compound is obtained, an addition reaction with the hydroxyl group-containing (meth) acrylate-based compound (b2) is carried out. to enable.

The reaction ratio (molar ratio) of the isocyanate group in the polyhydric isocyanate compound (b1) to the hydroxyl group of the polyol compound (b3) is the isocyanate group of (b1): the hydroxyl group of (b3) = 1.2 :. It is preferably 1 to 2: 1 and more preferably 1.5: 1 to 2: 1.

A known reaction is also carried out in an addition reaction between a reaction product obtained by reacting the polyisocyanate compound (b1) and a polyol compound (b3) in advance with a hydroxyl group-containing (meth) acrylate compound (b2). Means can be used.

The reaction molar ratio of the reaction product to the hydroxyl group-containing (meth) acrylate compound (b2) is, for example, that the polyvalent isocyanate compound (b1) has two isocyanate groups and the hydroxyl group-containing (meth) acrylate compound (b2). ) Has one hydroxyl group, the reaction product: hydroxyl group-containing (meth) acrylate compound (b2) is about 1: 2, and the polyvalent isocyanate compound (b1) has three isocyanate groups. When the hydroxyl group-containing (meth) acrylate compound (b2) has one hydroxyl group, the reaction product: the hydroxyl group-containing (meth) acrylate compound (b2) is about 1: 3.

In the addition reaction between this reaction product and the hydroxyl group-containing (meth) acrylate compound (b2), urethane is terminated when the residual isocyanate group content of the reaction system becomes 0.1% by weight or less. The (meth) acrylate compound (B) is obtained.

At the time of the above reaction, the reaction temperature is usually 30 to 90 ° C., preferably 40 to 80 ° C., and the reaction time is usually 2 to 30 hours, preferably 3 to 20 hours.

In the reaction between the polyvalent isocyanate compound (b1) and the polyol compound (b3), and further in the reaction between the reaction product and the hydroxyl group-containing (meth) acrylate compound (b2), a catalyst is used for the purpose of promoting the reaction. As such a catalyst, for example, an organic metal compound such as tin octylate, dibutyltin dilaurate, trimethyltin hydroxide, tetra-n-butyltin, zinc octate, tin octate, cobalt naphthenate, etc. Metal salts such as stannic chloride and stannic chloride, triethylamine, benzyldiethylamine, 1,4-diazabicyclo [2,2,2] octane, 1,8-diazabicyclo [5,4,0] undecene, N, N , N', N'-tetramethyl-1,3-butanediamine, N-ethylmorpholin and other amine-based catalysts, bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, etc., as well as dibutyl bismuth dilaurate, dioctyl bismuth Organic bismuth compounds such as dilaurate, 2-ethylhexanoic acid bismuth salt, naphthenic acid bismuth salt, isodecanoic acid bismuth salt, neodecanoic acid bismuth salt, lauric acid bismuth salt, maleic acid bismuth salt, stearate bismuth salt, oleate bismuth salt. , Linol acid bismuth salt, bismuth acetate salt, bismuth libis neodecanoate, bisalicylic acid bismuth salt, dicalcified bismuth salt and other organic acid bismuth salt and other bismuth catalysts, inorganic zirconium, organic zirconium, zirconium alone and other zirconium Examples include those using two or more kinds of catalysts such as a system catalyst and zinc 2-ethylhexanoate / zirconium tetraacetylacetonate in combination. Among them, dibutyltin dilaurate and 1,8-diazabicyclo [5,4,0] undecene. Is preferable. In addition, these catalysts can be used alone or in combination of two or more.

Further, in the reaction between the polyol compound (b3) and the polyhydric isocyanate compound (b1), and further in the reaction between the reaction product and the hydroxyl group-containing (meth) acrylate compound (b2), an isocyanate group is required. Using an organic solvent that does not have a functional group that reacts with, for example, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and organic solvents such as aromatics such as toluene and xylene. May be good.

Thus, the urethane (meth) acrylate-based compound (B) used in the present invention is produced.
The weight average molecular weight of the urethane (meth) acrylate compound (B) is 1,000 to 10,000. If the weight average molecular weight is too small, the adhesive strength tends to decrease, and if it is too large, the unsaturated group concentration of the obtained urethane (meth) acrylate compound decreases, and sufficient curability and hardness tend not to be obtained. is there.

The above weight average molecular weight is a weight average molecular weight converted to standard polystyrene molecular weight, and is used for high performance liquid chromatography ("Shodex GPC system-11 type" manufactured by Showa Denko Co., Ltd.), column: Shodex GPC KF-806L (excluded). limit molecular weight: 2 × 10 ^7, separation range: 100 to 2 × 10 ^7, theoretical plate number: 10,000 plates / the filler material: styrene - divinylbenzene copolymer, filler particle size: 10 [mu] m) 3 present in Measured by using series.

The viscosity of the urethane (meth) acrylate compound (B) is preferably 1,000 to 1,000,000 mPa · s, particularly preferably 2,000 to 500,000 mPa · s, at a viscosity at 60 ° C. s, more preferably 3,000 to 100,000 mPa · s. If the viscosity is too high, it tends to be difficult to handle, and if it is too low, it tends to be difficult to control the film thickness during coating.
The viscosity is measured by an E-type viscometer.

[Active energy ray-curable adhesive composition]
The active energy ray-curable adhesive composition of the present invention can be obtained by mixing the unsaturated compound (A) having one ethylenically unsaturated group and the urethane (meth) acrylate compound (B).

The content ratio (weight ratio) of the unsaturated compound (A) having one ethylenically unsaturated group and the urethane (meth) acrylate compound (B) in the active energy ray-curable adhesive composition of the present invention is , (A): (B) = 90 : 10 to 70:30.

If the content of the urethane (meth) acrylate compound (B) is too large with respect to the unsaturated compound (A) having one ethylenically unsaturated group, the adhesiveness to the acrylic resin member is lowered, and the object of the present invention is It cannot be achieved, and if it is too small, sufficient coatability, curability, and hardness cannot be obtained, and in some cases, curing may be poor, and the object of the present invention cannot be achieved. Further, in the case of poor curing, the unreacted residual monomer tends to reduce the physical characteristics (adhesive strength and hardness) of the coating film under high humidity and heat conditions, and the appearance of the coating film tends to be deteriorated due to the occurrence of cracks and the like.

The active energy ray-curable adhesive composition of the present invention preferably further contains a photopolymerization initiator (C) in order to efficiently cure with the active energy rays.

The photopolymerization initiator (C) is not particularly limited as long as it generates radicals by the action of light, and is, for example, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one. , Benzoyldimethylketal, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1 -On, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer, 1-[ 4- (2-Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) ) -Phenyl] -Phenyl} -2-Methyl-Propane-1-one and other acetophenones; Benzoyl, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and other benzoins; benzophenone, o-benzoyl benzoyl Methyl acid, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 3,3', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4-Benzoyl-N, N-Dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethanamineium bromide, (4-benzoylbenzyl) benzophenones such as trimethylammonium chloride; 2-isopropyl Thioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4-dimethyl-9H Thioxanthones such as −thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, Examples thereof include acylphosphon oxides such as bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; and the like. These photopolymerization initiators may be used alone or in combination of two or more.

In addition, as an auxiliary agent for these photopolymerization initiators, for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethyl benzoic acid, etc. Ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2, It is also possible to use 4-diisopropylthioxanson or the like in combination. These auxiliaries can also be used alone or in combination of two or more.

The content of the photopolymerization initiator is the sum of the unsaturated compound (A) having one ethylenically unsaturated group and the urethane (meth) acrylate compound (B) (the ethylenically unsaturated compound (D) described later). ) Is further preferably 0.1 to 20 parts by weight, particularly preferably 1 to 10 parts by weight, still more preferably 2 to 5 parts by weight with respect to 100 parts by weight (total with (D)). It is a part by weight. If the content is too small, the curing rate tends to decrease or the adhesive strength tends to decrease, and if it is too large, the curability does not improve, and yellowing may occur under high temperature and high humidity conditions.

Further, the active energy ray-curable adhesive composition of the present invention is an ethylenically unsaturated compound (D) other than the unsaturated compound (A) having one ethylenically unsaturated group (hereinafter, an ethylenically unsaturated compound (hereinafter, ethylenically unsaturated compound). D)) may be described. ) May be used, and the ethylenically unsaturated compound may be any of a monofunctional monomer, a bifunctional monomer, and a trifunctional or higher functional monomer.
These may be used alone or in combination of two or more.

The content of the ethylenically unsaturated compound (D) is the unsaturated compound (A) having one ethylenically unsaturated group, the urethane (meth) acrylate compound (B), and the ethylenically unsaturated compound (D). It is preferably 0 to 70% by weight, particularly preferably 0 to 50% by weight, and even more preferably 0 to 30% by weight, based on 100 parts by weight of the total. If the content is too large, the adhesiveness to the adherend, particularly the adhesiveness to the acrylic resin tends to decrease.

The monofunctional monomer may be a monomer containing one ethylenically unsaturated group, and may be, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, or isobutyl (meth) acrylate. , T-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, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, ethylcarbitol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (Meta) acrylate, butoxyethyl (meth) acrylate, glycidyl (meth) acrylate, trimethylpropane (formal) (meth) acrylate, acrylonitrile, vinyl acetate, allyl (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate Examples include monoesters.

In addition to the above monofunctional monomer, a Michael adduct of acrylic acid or a 2-acryloyloxyethyl dicarboxylic acid monoester can also be mentioned. Examples of the Michael adduct of acrylic acid include acrylic acid dimer, methacrylic acid dimer, and acrylic acid trimmer. , Methacrylic acid trimmer, acrylate tetramer, methacrylic acid tetramer and the like. Examples of the 2-acryloyloxyethyl dicarboxylic acid monoester, which is a carboxylic acid having a specific substituent, include 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, and 2-acryloyloxyethyl. Examples thereof include phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester, and 2-methacryloyloxyethyl hexahydrophthalic acid monoester. Further, oligoester acrylate can also be mentioned.

The bifunctional monomer may be a monomer containing two ethylenically unsaturated groups, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and polyethylene. Glycoldi (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-type di (meth) acrylate, propylene oxide-modified bisphenol A-type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,6-hexanediol ethylene oxide-type di (meth) acrylate, Examples include 1,9-nonanediol di (meth) acrylate, phthalic acid diglycidyl ester di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate, and 2- (meth) acryloyloxyethyl acid phosphate diester. Be done.

The trifunctional or higher functional monomer may be a monomer containing three or more ethylenically unsaturated groups. For example, trimethylpropantri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa (). Meta) acrylate, tri (meth) acryloyloxyethoxytrimethylol propane, isocyanurate ethylene oxide modified triacrylate, ethylene oxide modified dipentaerythritol hexa (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, caprolactone modified dipenta Examples thereof include erythritol hexa (meth) acrylate and caprolactone-modified pentaerythritol tetra (meth) acrylate.

Among these ethylenically unsaturated compounds (D), it is preferable to use a monofunctional monomer because it is excellent in the flexibility of the coating film, and it is excellent in flexibility with less yellowing, for example, methyl (meth). Acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl ( Meta) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, dodecyl (meth) acrylate, n-stearyl (meth) acrylate, isostearyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, ethyl carbitol (meth) Particularly preferred are meta) acrylates, methoxypolyethylene glycol (meth) acrylates, methoxypolypropylene glycol (meth) acrylates and butoxyethyl (meth) acrylates.

The active energy ray-curable adhesive composition of the present invention includes an unsaturated compound (A) having one ethylenically unsaturated group, a urethane (meth) acrylate compound (B), a photopolymerization initiator (C), and the like. In addition to the ethylenically unsaturated compound (D), a resin such as an acrylic resin or a polyurethane compound or an inorganic particle such as silica gel can be added as needed. Further, it is also possible to contain an antioxidant, a flame retardant, an antistatic agent, a filler, a leveling agent, a stabilizer, a reinforcing agent and a matting agent as long as the effects of the present invention are not impaired. Further, as the cross-linking agent, a compound having an action of causing cross-linking by heat, specifically, an epoxy compound, an aziricin compound, a melamine compound, an isocyanate compound, a chelate compound and the like can also be used.

Further, the active energy ray-curable adhesive composition of the present invention can contain a polythiol compound from the viewpoint of suppressing unreacted components and improving the adhesive force.
The polythiol compound is not particularly limited, but a compound having 2 to 6 mercapto groups in the molecule is preferable, for example, aliphatic polythiols such as alkanedithiol having about 2 to 20 carbon atoms and aromatics such as xylylene dithiol. Polythiols, polythiols formed by substituting the halogen atom of the halohydrin adduct of alcohols with a mercapto group, polythiols composed of hydrogen sulfide reaction products of polyepoxide compounds, polyhydric alcohols having 2 to 6 hydroxyl groups in the molecule. And polythiols composed of thioglycolic acid, β-mercaptopropionic acid, or an esterified compound with β-mercaptobutanoic acid, and these can be used alone or in combination of two or more. ..

The content of the polythiol compound is the total of the unsaturated compound (A) having one ethylenically unsaturated group and the urethane (meth) acrylate compound (B) (the above-mentioned ethylenically unsaturated compound (D) is contained. In this case, it is preferably 0.01 to 10 parts by weight or less, and particularly preferably 0.1 to 5 parts by weight or less, relative to 100 parts by weight (total with (D)).

Further, in the active energy ray-curable adhesive composition of the present invention, a solvent may be used to adjust the viscosity at the time of coating, if necessary, but the solvent may remain in the adhesive layer or the solvent may remain. Since the curing component may volatilize when the solvent dries, it is preferable to use it as a solvent-free adhesive composition that does not substantially contain a solvent.
The term "substantially free of solvent" means that the composition is usually 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.1% by weight or less based on the entire active energy ray-curable adhesive composition. Refers to something.

The viscosity of the active energy ray-curable adhesive composition of the present invention at 20 ° C. is preferably 1 to 10,000 mPa · s, particularly 3 to 1,000 mPa · s, from the viewpoint of coatability and the like. Further, it is preferably 5 to 500 mPa · s. If the viscosity is too low, liquid twisting and repelling tend to occur during coating on the base material, and the coatability tends to decrease. If the viscosity is too high, the base material has one monomer component (one ethylenically unsaturated group). The penetrating power of the unsaturated compound (A) and the ethylenically unsaturated compound (D) is impaired, and there is a tendency that sufficient adhesiveness cannot be obtained, and the coatability also tends to decrease.
The viscosity is measured by an E-type viscometer.
Thus, the active energy ray-curable adhesive composition of the present invention is obtained.

The active energy ray-curable adhesive composition obtained in the present invention is applied on various substrates, the adherend is adhered to the coated surface, and then cured by irradiating with active energy rays.

The base material to which the active energy ray-curable adhesive composition obtained in the present invention is applied includes (meth) acrylic resin, polyolefin resin, polyester resin, polycarbonate resin, and acrylonitrile butadiene styrene co-weight. Synthetic resins such as coalesced (ABS), polystyrene resins, and polyamide resins and their molded products (films, sheets, cups, etc.), metal substrates (metal vapor deposition layers, metal plates (copper, stainless steel (SUS304, SUSBA, etc.), etc.) ), Aluminum, zinc, magnesium, etc.)), glass, etc., or a composite base material thereof.

Examples of the adherend include articles having various metal surfaces; polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefins such as polyethylene, polypropylene, and polymethylpentene. Systems Resins: Polyfluorinated Ethylene Resins such as Polyvinyl Fluoride, Vinylidene Polyfluoride, Polyethylene Polyfluoride; Polyamides such as Nylon 6, Nylon 6, 6; Polyvinyl Chloride, Polyvinyl Chloride / Vinyl Acetate Copolymer, Ethylene-vinyl Acetate Copolymers, ethylene-vinyl alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; methyl polymethacrylate, ethyl polymethacrylate, ethyl polyacrylate, polyacrylics Acrylic resins such as butyl acid acid; synthetic resins such as polystyrene, polycarbonate, polyarylate, and polyimide, and molded products thereof (plates, films, sheets, cups, etc.) can be mentioned.

The active energy ray-curable adhesive composition of the present invention is particularly useful as an adhesive composition for an acrylic resin member because it has excellent adhesiveness to (meth) acrylic resins. At this time, an adhesive layer may be provided on the acrylic resin member, or an adhesive layer may be provided on the member side to be bonded to the acrylic resin member.

The method for applying the active energy ray-curable adhesive composition is not particularly limited, and for example, spray, shower, dipping, roll, spin, curtain, flow, slit, die, gravure, comma, dispenser, etc. , Screen printing, inkjet printing and the like.

As such active energy rays, in addition to ultraviolet rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays and infrared rays, and electromagnetic waves such as X-rays and γ-rays, electron beams, proton rays, neutron rays and the like can be used. Curing by ultraviolet irradiation is advantageous because of its availability and price. When electron beam irradiation is performed, it can be cured without using the photopolymerization initiator (C).

As a method of curing by ultraviolet irradiation, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, an LED, etc. that emit light in the wavelength range of 150 to 450 nm are used. It suffices to irradiate about 30 to 3,000 mJ / cm ^2.
After the irradiation with ultraviolet rays, heating can be performed as necessary to complete the curing.

The thickness of the adhesive layer after curing is usually preferably 1 to 50 μm, particularly preferably 2 to 20 μm, and further preferably 3 to 10 μm.

The active energy ray-curable adhesive composition obtained in the present invention is useful as a component of various active energy ray-curable adhesives, and in particular, an adhesive used for adhesion to an acrylic resin member, specifically Is useful as an adhesive between an acrylic plate as an optical member such as a liquid crystal panel member and a protective sheet.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the example, "part" and "%" mean a weight standard.

<Manufacturing of urethane (meth) acrylate compound (B)>
[Manufacturing Example 1]
In a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 301 g (1.35 mol) of isophorone diisocyanate and 540 g of polycarbonate diol (linear structure; hydroxyl value 140.5 mgKOH / g; number average molecular weight calculated from hydroxyl value). 799; 0.68 mol), 0.1 g of dibutyltin dilaurate was charged as a reaction catalyst, and the reaction was carried out at 80 ° C. When the residual isocyanate group becomes 6.8% or less, the mixture is cooled to 60 ° C., 159 g (1.37 mol) of 2-hydroxyethyl acrylate and 0.4 g of methoxyphenol as a polymerization inhibitor are further charged, and the reaction is carried out at 60 ° C. The reaction is terminated when the residual isocyanate group becomes 0.3% or less, and the urethane (meth) acrylate compound (B-1) having a carbonate structure (weight average molecular weight; 5,000, viscosity; 50, 000 mPa · s / 60 ° C.) was obtained.

[Manufacturing Example 2]
408 g (1.56 mol) of 4,4'-dicyclohexylmethane diisocyanate and 349 g of polyether diol (linear structure; hydroxyl value 167 mgKOH / g; calculated from hydroxyl value) in a flask equipped with an internal thermometer, a stirrer, and a cooling tube. With a number average molecular weight of 672; 0.52 mol), 0.1 g of dibutyltin dilaurate was charged as a reaction catalyst and reacted at 70 ° C. When the residual isocyanate group becomes 11.5% or less, the mixture is cooled to 60 ° C., 243 g (2.10 mol) of 2-hydroxyethyl acrylate and 0.4 g of methoxyphenol as a polymerization inhibitor are further charged, and the reaction is carried out at 60 ° C. The reaction is terminated when the residual isocyanate group becomes 0.3% or less, and the urethane (meth) acrylate-based compound (B-2) having an ether structure (weight average molecular weight; 3,000, viscosity; 12, 000 mPa · s / 60 ° C.) was obtained.

[Comparative Manufacturing Example 1]
In a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 169 g (0.76 mol) of isophorone diisocyanate and 741 g of polyester diol having no ether structure and / or carbonate structure (hydroxyl value 57.6 mgKOH / g; from hydroxyl value). Calculated number average molecular weight 1948; 0.38 mol), 0.1 g of dibutyltin dilaurate was charged as a reaction catalyst, and the reaction was carried out at 60 ° C. When the residual isocyanate group became 3.5% or less, 90.5 g (0.78 mol) of 2-hydroxyethyl acrylate and 0.4 g of methoxyphenol as a polymerization inhibitor were further charged and reacted at 60 ° C. to remain. The reaction is terminated when the isocyanate group becomes 0.3% or less, and the urethane (meth) acrylate-based compound (B'-1) containing neither an ether structure nor a carbonate structure (weight average molecular weight; 10,000, viscosity; 15,000 mPa · s / 60 ° C.) was obtained.

[Comparative Manufacturing Example 2]
In a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 483 g (2.17 mol) of isophorone diisocyanate, 517 g (4.45 mol) of 2-hydroxyethyl acrylate, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were charged and polymerized. 0.4 g of methoxyphenol was added as a banning agent and reacted at 60 ° C., and the reaction was terminated when the residual isocyanate group became 0.3% or less, and the urethane (meth) acrylate compound (B'-2) ( Weight average molecular weight; 780, viscosity; 3,500 mPa · s / 60 ° C.) was obtained.

[Example 1]
90 parts of benzyl acrylate (A-1) as the unsaturated compound (A) having one ethylenically unsaturated group, and the urethane having the carbonate structure obtained in Production Example 1 as the urethane (meth) acrylate compound (B). 10 parts of (meth) acrylate compound (B-1) and 4 parts of 1-hydroxycyclohexyl-phenyl-ketone (manufactured by BASF Japan, trade name: Irgacure 184) as a photocuring initiator (C) are mixed and dissolved at room temperature. To obtain an active energy ray-curable adhesive composition (viscosity; 6.0 mPa · s / 20 ° C.).

[Example 2]
The active energy is the same as in Example 1 except that the blending amount of the benzyl acrylate (A-1) is changed to 80 parts and the blending amount of the urethane (meth) acrylate compound (B-1) having a carbonate structure is changed to 20 parts. A linear curable adhesive composition (viscosity; 15.0 mPa · s / 20 ° C.) was obtained.

[Example 3]
This was carried out except that the urethane (meth) acrylate compound (B-2) having an ether structure obtained in Production Example 2 was used instead of the urethane (meth) acrylate compound (B-1) having a carbonate structure. An active energy ray-curable adhesive composition (viscosity; 5.0 mPa · s / 20 ° C.) was obtained in the same manner as in Example 1.

[Example 4]
This was carried out except that the urethane (meth) acrylate compound (B-2) having a carbonate structure obtained in Production Example 2 was used instead of the urethane (meth) acrylate compound (B-1) having a carbonate structure. An active energy ray-curable adhesive composition (viscosity; 15.0 mPa · s / 20 ° C.) was obtained in the same manner as in Example 2.

[Example 5]
The active energy ray-curable adhesive composition (viscosity; 19.5 mPa · s) was the same as in Example 4 except that tetrahydrofurfuryl acrylate (A-2) was used instead of the benzyl acrylate (A-1). / 20 ° C.) was obtained.

[Example 6]
The active energy ray-curable adhesive composition (viscosity; mPa · s / 20 ° C.) was the same as in Example 4 except that phenoxybenzyl acrylate (A-3) was used instead of benzyl acrylate (A-1). ) Was obtained.

[Comparative Example 1]
Instead of the urethane (meth) acrylate compound (B-1) having a carbonate structure, the urethane (meth) acrylate compound (B'-1) containing neither the ether structure nor the carbonate structure obtained in Comparative Production Example 1 above. An active energy ray-curable adhesive composition (viscosity; 20.1 mPa · s / 20 ° C.) was obtained in the same manner as in Example 2 except that

[Comparative Example 2]
Instead of the urethane (meth) acrylate compound (B-1) having a carbonate structure, the urethane (meth) acrylate compound (B'-2) containing neither the ether structure nor the carbonate structure obtained in Comparative Production Example 2 above. An active energy ray-curable adhesive composition (viscosity; 4.9 mPa · s / 20 ° C.) was obtained in the same manner as in Example 2 except that

[Comparative Example 3]
The active energy ray-curable adhesive composition (viscosity) was the same as in Example 1 except that the blending amount of the benzyl acrylate (A-1) was 100 parts and the urethane (meth) acrylate compound (B) was not used. 2.3 mPa · s / 20 ° C.) was obtained.

[Comparative Example 4]
Instead of the urethane (meth) acrylate-based compound (B-1) having a carbonate structure, the urethane (meth) acrylate-based compound (B-2) having an ether structure obtained in Production Example 2 above is used, and benzyl acrylate is used. Active energy ray curing is the same as in Example 1 except that the blending amount of (A-1) is 40 parts and the blending amount of the urethane (meth) acrylate compound (B-2) having an ether structure is 60 parts. A sex adhesive composition (viscosity; 667 mPa · s / 20 ° C.) was obtained.

[Comparative Example 5]
Example 1 except that tetrahydrofurfuryl acrylate (A-2) was used instead of benzyl acrylate (A-1), the blending amount was 100 parts, and the urethane (meth) acrylate compound (B) was not used. In the same manner as above, an active energy ray-curable adhesive composition (viscosity; 3.1 mPa · s / 20 ° C.) was obtained.

[Comparative Example 6]
Example 1 and Example 1 except that phenoxybenzyl acrylate (A-3) was used instead of benzyl acrylate (A-1), the blending amount was 100 parts, and the urethane (meth) acrylate compound (B) was not used. In the same manner, an active energy ray-curable adhesive composition (viscosity; 21.3 mPa · s / 20 ° C.) was obtained.

The active energy ray-curable adhesive compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated as follows. The results are shown in Table 1.

[Preparation of evaluation sample]
The active energy ray-curable adhesive composition obtained above is applied onto an easily adhesive polyethylene terephthalate (PET) film (manufactured by Toyobo; Cosmo Shine A4300, thickness 125 μm) with a bar coater so as to have a thickness of 5 μm, and the coated surface is coated. Was affixed to a polymethyl methacrylate plate (acrylic resin member) with a roller. At this time, a surface not coated with the adhesive composition was provided on the edge of the PET film so that it could be peeled off in the adhesiveness test. Then, the PET film side was irradiated with ultraviolet rays with a high-pressure mercury lamp so that the integrated light intensity was 1000 mJ / cm ^2, and the active energy ray-curable adhesive composition was cured to prepare an easy-adhesion PET film / acrylic resin member adhesive sample. ..

〔Adhesiveness〕
The end of the PET film that was not adhered to the acrylic resin plate of the evaluation sample prepared above was fixed with a chuck, and the adhesiveness was evaluated by a 90 ° peel test by Shimadzu Autograph AG-X (Shimadzu Corporation). .. The width of the PET substrate in the test was 25 mm, and the measurement was performed at a peel speed of 300 mm / min.

(Evaluation criteria)
⊚: The PET base material was torn due to the strong adhesive force (material breakage), or the average adhesive force was 30.0 N / 25 mm or more.
◯: The average adhesive strength was 10.0 N / 25 mm or more and less than 30.0 N / 25 mm.
Δ: The average adhesive strength was 5.0 N / 25 mm or more and less than 10.0 N / 25 mm.
X ... The average adhesive strength was less than 5.0 N / 25 mm.

〔Pencil hardness〕
The active energy ray-curable adhesive composition obtained above was applied onto an easily adhesive PET film (Toyobo; Cosmo Shine A4300, thickness 125 μm) with a bar coater to a thickness of 5 μm, and then a high-pressure mercury lamp lamp 80W, 1 Using a lamp, 2-pass ultraviolet irradiation (cumulative irradiation amount 800 mJ / cm ² ) was performed from a height of 18 cm at a conveyor speed of 3.4 m / min to form a cured coating film. The hardness of the obtained cured coating film was measured according to JIS K 5600-5-4.

(Criteria)
○ ・ ・ ・ B or more △ ・ ・ ・ 3B or 2B
× ・ ・ ・ 4B or less

〔Heat-resistant〕
With respect to the active energy ray-curable adhesive composition of Example 4, the Hazen color number (APHA) was measured using a spectroscopic color difference meter "SE6000: manufactured by Nippon Denshoku Industries Co., Ltd.". Further, the active energy ray-curable adhesive composition was placed in a closed glass test container, stored under heat resistance conditions: 60 ° C. for 4 weeks, and the APHA value after the heat resistance test was measured.
As a result, the APHA before the heat resistance test was 9 and the APHA after the heat resistance test was 14, and the yellowing of the adhesive composition was small even after the heat resistance test.

From the above evaluation results, the active energy ray-curable adhesive compositions of Examples 1 to 6 were excellent in adhesiveness to the acrylic resin member, and the pencil hardness of the obtained cured coating film was also high. On the other hand, Comparative Examples 1 and 2 using urethane (meth) acrylate compounds having neither an ether structure nor a carbonate structure were inferior in hardness or adhesiveness, respectively. Further, the active energy ray-curable adhesive composition of Comparative Examples 3 to 6 in which the content ratio of the unsaturated compound having one ethylenically unsaturated group and the urethane (meth) acrylate-based compound does not satisfy the specified range of the present invention. Was lacking in the balance between the adhesiveness to the acrylic resin member and the hardness of the cured coating film.

The active energy ray-curable adhesive composition of the present invention is useful as an adhesive component for various adhesive components, particularly for optical members and optical films. In particular, it has excellent adhesion to acrylic resins, and has excellent coatability, curability, hardness when cured, transparency, moisture resistance, and storage stability in a well-balanced manner, making it useful as an adhesive for acrylic resin members. Therefore, it can be very suitably used for adhesion between a liquid crystal display and an acrylic protective film.

Claims (4)

An active energy ray-curable adhesive composition containing an unsaturated compound (A) having one ethylenically unsaturated group and a urethane (meth) acrylate compound (B).
The unsaturated compound (A) having one ethylenically unsaturated group has a cyclic structure and contains benzyl (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate or tetrahydrofurfuryl (meth) acrylate.
The urethane (meth) acrylate compound (B) has an ether structure and / or a carbonate structure, and has a weight average molecular weight of 1000 to 10000.
The content ratio (weight ratio) of the unsaturated compound (A) having one ethylenically unsaturated group and the urethane (meth) acrylate compound (B) is (A) :( B) = 90: 10 to 70:30. An active energy ray-curable adhesive composition comprising. The active energy ray-curable adhesive composition according to claim 1, further comprising a photopolymerization initiator (C). The active energy ray-curable adhesive composition according to claim 1 or 2 , wherein the active energy ray-curable adhesive composition has a viscosity at 20 ° C. of 1 to 10,000 mPa · s. An adhesive composition for an acrylic resin member, which comprises using the active energy ray-curable adhesive composition according to any one of claims 1 to 3.