JP3436410B2 - Active energy ray-curable adhesive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has good curability to active energy rays, adhesive strength to metals and plastics, flexibility, weather resistance, heat resistance and water resistance. And an active energy ray-curable adhesive excellent in chemical resistance. [0002] Active energy ray-curable adhesives are different from general solvent-based adhesives in that the solvent-free and active energy ray-curing process has high productivity, resource saving and energy saving.
Due to such features, development as an adhesive for various substrates has been progressing. However, conventional active energy ray-curable adhesives have poor wettability to the substrate,
Since the internal stress due to shrinkage during curing remains, the adhesive strength with the base material is weak, and the flexibility of the cured adhesive layer is insufficient, so that the limit of the base material that can be bonded and the durability of the bonded part are There was a problem in point. In addition, curing with a lower active energy dose has been required to speed up production lines and diversify the substrates to be bonded, but adhesives with excellent curability have poor adhesion to the substrate. There was a problem. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide excellent curability to low energy active energy rays. Another object of the present invention is to provide an active energy ray-curable adhesive having excellent adhesive strength to metals and plastics, flexibility, weather resistance, heat resistance, water resistance and chemical resistance. Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, a polyester polyol having a molecular weight of 1,000 to 20,000 obtained by copolymerizing a specific amount of an aromatic dicarboxylic acid with ( 2) having a specific range of molecular weight and urethane or urea group concentration obtained by introducing a compound having at least one (meth) acryloyloxy group and at least one hydroxyl group through a polyisocyanate compound; Use of an adhesive obtained by blending urethane acrylate (A) and polymerizable monomer (B) makes it possible to cure and bond to active energy rays in a low energy range, adhesive strength, flexibility, weather resistance, heat resistance, and water resistance. It has been found that an active energy ray-curable adhesive having excellent heat resistance and chemical resistance can be obtained. That is, the active energy ray-curable adhesive of the present invention comprises a component (1) obtained by reacting the following components (1) to (3):
A urethane acrylate (A) having a molecular weight of 1,000 to 20,000 having 2.7 to 11 urethane bonding groups and / or urea bonding groups per constituent unit of component (1), wherein the number of repeating units is 2 or more, and tetrahydrofurfree (Meth) acrylate, phenoxyethyl (meth) acrylate, toluyloxyethyl (meth) acrylate, N
-An active energy ray-curable adhesive characterized by containing vinylpyrrolidone or (meth) acryloylmonophorin (B). (1) Copolymerized polyester polyol containing 40 mol% or more of aromatic dicarboxylic acid and having a molecular weight of 1,000 to 10,000 (2) Polyisocyanate compound (3) One or more (meth) acryloyloxy groups and one or more The compound (1) used in the present invention comprises a dicarboxylic acid component and a glycol component. The aromatic dicarboxylic acid, which is an essential component in the present invention, is a dicarboxylic acid having a group having aromaticity in the molecule, such as phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, and 1,5-naphthalic acid. Are typical examples. If necessary, a small amount of tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid and pyromellitic acid may be contained. Examples of dicarboxylic acids that can be copolymerized other than aromatic dicarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 1,2-hexahydrophthalic acid, 1,3- Hexahydrophthalic acid,
Alicyclic dicarboxylic acids such as 1,4-hexahydrophthalic acid and perhydronaphthalenedicarboxylic acid, unsaturated dicarboxylic acids such as fumaric acid, maleic acid and itaconic acid, and unsaturated fats such as tetrahydrophthalic acid and cyclobutene dicarboxylic acid Oxyacids such as cyclic dicarboxylic acid, p-hydroxyethyloxybenzoic acid, and ε-caprolactone are exemplified. Examples of the glycol component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol. , Neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, spiro glycol, 1,4-phenylene glycol, 1,4-phenylene glycol Of ethylene oxide adduct, bisphenol A ethylene oxide adduct and propylene oxide adduct, hydrogenated bisphenol A ethylene oxide adduct and propylene oxide adduct, polyethylene glycol,
Examples include diols such as polypropylene glycol and polytetramethylene glycol. If necessary, a small amount of triol and tetraol such as trimethylolethane, trimethylolpropane, glycerin and pentaerythritol may be contained. In order to obtain a copolymerized polyester polyol from such a dicarboxylic acid component and a glycol component, synthesis may be performed using an excess of a glycol raw material with respect to a dicarboxylic acid raw material. At this time, it is desirable that the synthesis is performed so that the carboxyl group terminal is less than 50 eq / 10 ⁶ g in the copolymerized polyester. If it exceeds 50 eq / 10 ⁶ g, the number of inactive terminals in the reaction with a diisocyanate compound in synthesizing the urethane acrylate resin described below becomes too large, and the desired urethane resin cannot be obtained, and the curability to active energy rays decreases. I do. The polyester polyol used in the present invention contains at least 40 mol% of an aromatic dicarboxylic acid as a dicarboxylic acid component, and has a molecular weight in the range of 1,000 to 10,000. If the content of the aromatic dicarboxylic acid component as the dicarboxylic acid component is less than 40 mol%, the adhesion strength is lowered and the heat resistance of the cured product is also lowered, which is not preferable. On the other hand, if the molecular weight is less than 1,000, the adhesion strength decreases, and the flexibility of the cured product is insufficient. If the molecular weight exceeds 10,000, urethanization reactivity decreases, and the viscosity increases, which causes a problem of handling. As the (2) polyisocyanate compound used in the present invention, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, p-phenylene diisocyanate, biphenylmethane diisocyanate,
m-phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 3,
3′-dimethoxy-4,4′-biphenylene diisocyanate, 2,4-naphthalenediisocyanate, 3,
3′-dimethyl-4,4′-biphenylene diisocyanate, 4,4′-diphenylene diisocyanate, 4,
4'-diisocyanate diphenyl ether, 1,5 '
-Naphthalene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 1,3
Diisocyanate compounds such as diisocyanate methylcyclohexane, 1,4-diisocyanate dicyclohexane, 4,4′-diisocyanate dicyclohexane, 4,4′-diisocyanate dicyclohexylmethane, isophorone diisocyanate, or 7 mol% or less of all isocyanate groups. Trimer of 1,4-tolylene diisocyanate, 3 of hexamethylene diisocyanate
Triisocyanate compounds such as monomers. Among these isocyanate compounds, isophorone diisocyanate and hexamethylene diisocyanate are particularly preferable in terms of weather resistance. The compound (3) having one or more (meth) acryloyloxy groups and one or more hydroxyl groups used in the present invention includes mono- (meth) glycols such as ethylene glycol, diethylene glycol and hexamethylene glycol. ) Acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, trimethylolpropane, glycerin, trimethylolethane, etc. Mono (meth) acrylate, di (meth) acrylate, tri (meth) acrylate, tri (meth) acrylate, glycerin monoa of tetravalent or higher polyol such as meth) acrylate and di (meth) acrylate, pentaerythritol, dipentaerythritol Ether, hydroxyl group-containing acrylic compounds such as glycerol diacrylate ether. Urethane acrylate used in the present invention
(A) may contain a polyol other than the above (1) and / or
Alternatively, a polyamine may be used as a chain extender. Examples of the polyol other than the above (1) include glycol components of the above (1) copolymerized polyester polyol such as ethylene glycol and propylene glycol. Examples of the polyamine include hexamethylenediamine, diaminodiphenylmethane, N-methyldiethanolamine, and high molecular weight polyamines having two or more primary or secondary amino groups in the molecule, such as terminally aminated polybutadiene and the like. In addition, water may be used similarly to these compounds. The urethane acrylate (A) of the present invention is obtained by reacting (1) the copolymerized polyester polyol with (2) a polyisocyanate compound at [NCO] / [OH] <2 to obtain an isocyanate-terminated urethane prepolymer. After (3) one or more (meth) acryloyloxy groups and 1
It can be obtained by reacting a compound having two or more hydrogen groups. As another manufacturing method, (1) the copolymerized polyester polyol and (2) the polyisocyanate compound
CO] / [OH] ≧ 2 to obtain an isocyanate-terminated prepolymer, and (3) a compound having at least one (meth) acryloyloxy group and at least one hydrogen group.
(4) It can be obtained by reacting a polyol and / or polyamine other than the above (1). These resins can also be obtained by a method in which the compounds to be reacted are charged at a fixed ratio and then reacted. The urethane acrylate (A) of the present invention thus obtained has a molecular weight in the range of 1,000 to 20,000, and has 2 or more repeating units in the molecule and 2.7 to 11 per structural unit. Urethane bonding group and / or
Alternatively, it is necessary to have a urea bonding group. If the molecular weight is smaller than 1,000, the strain during curing increases, and the adhesion to the base material becomes poor, which is not preferable. If the molecular weight exceeds 20,000, the compatibility with the polymerizable monomer (B) described below deteriorates, and as a result, the viscosity becomes too high and the use becomes difficult. When the number of repeating units is one, the toughness and adhesion of the cured product are insufficient. Even when the number of repeating units is two or more, if the number of urethane bonding groups and / or urea bonding groups in the molecule is less than 2.7 per unit of the constituent polyester polyol (1), the adhesion to the base material is poor. Not enough, and the toughness of the cured product is also insufficient. If the number exceeds 11, the adhesiveness decreases, and the viscosity increases due to urethane bonds or the like, which is not preferable. Another essential component (B) of the present invention is tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, toluyloxyethyl (meth) acrylate, N-vinylpyrrolidone, or (B). (Meth) acryloylmonophorin. These polymerizable monomers have excellent adhesion to polyethylene terephthalate. Active energy ray-curable adhesives using these compounds have curability to active energy rays,
Metals and plastics, especially polyethylene terephthalate, are preferred because they have excellent adhesion strength, flexibility, weather resistance, water resistance, heat resistance and chemical resistance. The active energy ray-curable adhesive of the present invention can optionally contain a photopolymerization initiator (C).
Examples of the photopolymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, and 1- (4-
Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy)
Phenyl- (2-hydroxy-2-propyl) ketone,
1-hydroxycyclohexyl-phenyl ketone, 2-
Acetophenones such as methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, benzoin,
Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin ethers such as benzoin isobutyl ether, benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, Alkylated benzophenone, 3,3 ′, 4,4′-tetra (t
-Butylperoxycarbonyl) benzophenone, 4-
Benzophenones such as benzoyl-N, N-dimethyl-N- [2-((1-oxo-2-propenyloxy) ethyl] benzenemethanaminium bromide and (4-benzoylbenzyl) trimethylammonium chloride;
Isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-
Thioxanthones such as dichlorothioxanthone are exemplified. These may be used alone or in combination. The photopolymerization initiators include triethanolamine, methyldiethanolamine, triethanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, benzoic acid (2 -Dimethylamino) ethyl,
4,4'-dimethylaminobenzophenone, 4,4'-
A sensitizer such as diethylaminobenzophenone may be used in combination. The active energy ray-curable adhesive of the present invention comprises the above urethane acrylate (A), polymerizable monomer (B)
The photopolymerization initiator (C) is added as required. The mixing ratio can be set arbitrarily, but (A) / (B) / (C) = 10-70 / 1 by weight ratio.
The range of 0 to 70/0 to 10 is preferred. Ingredient (A) is 10
If the content is less than 10% by weight, the properties as a urethane acrylate resin are lost, and the adhesion strength to metals and plastics is reduced, and the flexibility and weather resistance are undesirably reduced. On the other hand, if the content of the component (A) exceeds 70% by weight, the viscosity is too high to use, and the curability to active energy rays deteriorates, which is not preferable. As a method of producing the active energy ray-curable adhesive of the present invention, there is a method of synthesizing the urethane acrylate (A) by the above-mentioned method and then blending a polymerizable monomer (B). As another method, the polymerizable monomer (B)
Is used as a reaction solvent to synthesize urethane acrylate (A). Components other than the above components (A) to (C) can be added to the active energy curable adhesive of the present invention as needed. For example, it is effective to add epoxy and polyisocyanate to improve the adhesive strength. Other resins, plasticizers, defoamers, leveling agents, solvents, stabilizers, and the like may be added according to the properties of the adhesive depending on the site of use. Active energy rays used for curing in the present invention are ultraviolet rays, electron rays, γ rays, neutron rays and the like. When using ultraviolet rays, it is desirable to add the above-mentioned photopolymerization initiator to the active energy ray-curable adhesive. As the electron beam irradiator, a scanning method,
Alternatively, the curtain beam method can be adopted, and the absorbed dose is 1
-20 Mrad, preferably 2-15 Mrad. The organic solvent that can be used in the present invention is limited to a volatile solvent, and most or all of the organic solvent must be volatilized by heating and drying before curing with active energy rays.
Examples of usable solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, esters such as methyl acetate and ethyl acetate, ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether, benzene, and toluene.
Examples include aromatic hydrocarbons such as xylene, aliphatic hydrocarbons such as hexane and heptane, alcohols such as methanol, ethanol, and isopropyl alcohol, and mixtures thereof. The solvent used in synthesizing the urethane acrylate (A) of the present invention can be used as it is. The active energy ray-curable adhesive of the present invention is said to have excellent curability to active energy rays, excellent adhesion strength to metals and plastics, flexibility, weather resistance, water resistance, heat resistance and chemical resistance. Taking advantage of its features, in addition to general plastic, metal and glass bonding, bonding and fixing of electric and electronic parts, automobile panels, bonding of optical fibers, assembly of optical parts, fixing of bolts and nuts, dental care, etc. Can be used for various applications. EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”. (Production Example of Copolymerized Polyester Polyol) In a reaction vessel equipped with a thermometer, a stirrer, a distillation column, a condenser, and a decompression device, dimethyl terephthalate 44 was added.
0 part, dimethyl isophthalate 440 parts, ethylene glycol 412 parts, hexane diol 393 parts, and tetrabutoxy titanate 0.5 part, and 150 to 23
The mixture was heated at 0 ° C. for 120 minutes to cause a transesterification reaction.
Then, the reaction system was depressurized to 10 mmHg, and the temperature was raised to 250 ° C. for 30 minutes to carry out a reaction, thereby obtaining a copolymerized polyester polyol A. Polyester polyol A has a molecular weight of 160
It was 0. The polyester polyols BF obtained by the same method are shown in Table 1 together with the polyester polyol A. The resin composition was analyzed by ¹ H NMR. [Table 1] (Production Example 1 of Active Energy Beam Curable Adhesive) 100 parts of copolymerized polyester polyol A and 132 parts of phenoxyethyl acrylate were charged into a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser. After charging 17 parts of methylene diisocyanate and 0.05 part of dibutyltin dilaurate and reacting at 70 to 80 ° C. for 2 hours, further adding 15 parts of 2-hydroxyethyl acrylate and performing the reaction at 70 to 80 ° C. An active energy ray-curable adhesive A, which is a phenoxyethyl acrylate solution of an acrylate resin, was obtained. The molecular weight of urethane acrylate was 2000. Urethane acrylate resins were synthesized in the same manner to obtain active energy ray-curable adhesives B to E. The composition obtained is shown in Table 2. [Table 2] (Production Example 2 of Active Energy Ray-Curing Adhesive) 100 parts of copolymerized polyester polyol A and 135 parts of acryloylmorpholine were charged into a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser. After 21 parts of diisocyanate and 0.05 part of dibutyltin dilaurate were charged and reacted at 70 to 80 ° C. for 2 hours, 7 parts of 2-hydroxyethyl acrylate was added, and the mixture was further reacted at 70 to 80 ° C. for 2 hours. The reaction was performed by adding 7 parts of 3-methyl-1,5-pentanediol as an agent to obtain an active energy ray-curable adhesive F which is a solution of urethane acrylate resin in acryloylmorpholine. The molecular weight of urethane acrylate was 4100. A urethane acrylate resin is synthesized in the same manner, and the active energy ray-curable adhesive G
~ K was obtained. The composition obtained is shown in Table 3. [Table 3] Example 1 A photopolymerization initiator 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Darocur 1116 MERK) was used for 100 parts of the active energy ray-curable adhesive B. 3 parts were mixed and applied on a polyethylene terephthalate sheet using an applicator such that the thickness after curing became 10 μm. Then, a polyethylene terephthalate film was overlaid on the coated surface. 6.4kw x 4 lamps Water-cooled low-pressure mercury lamp with 10 UV rays
Irradiation was performed from one of the stacked films so as to have a thickness of 0 mJ / cm ² , thereby effecting curing adhesion. In the same manner, a cured adhesive was prepared using a galvanized steel sheet instead of a film coated with an adhesive. Cured adhesives were similarly prepared for adhesives C, E, F, and H. COMPARATIVE EXAMPLE 1 Photopolymerization initiator 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Darocur 1116, manufactured by MERK) based on 100 parts of active energy ray-curable adhesive A Three parts were mixed and applied on a polyethylene terephthalate sheet using an applicator such that the thickness after curing became 10 μm. Then, a polyethylene terephthalate film was overlaid on the coated surface. 6.4kw x 4 lamps Water-cooled low-pressure mercury lamp with 10 UV rays
Irradiation was performed from one of the stacked films so as to have a pressure of 0 mJ / cm ² , thereby effecting curing adhesion. In the same manner, a cured adhesive was prepared using a galvanized steel sheet instead of a film coated with an adhesive. Cured adhesives were similarly prepared for adhesives D, G, I, J and K. The cured adhesive was evaluated by the following method. For evaluations other than the adhesion strength, a cured adhesive between polyethylene terephthalate films was used. Adhesion Strength The cured adhesive was cut into a strip of 10 mm × 40 mm with a cutter or the like, and the adhesive was peeled at an angle of 90 °, and the strength at that time was tested. Curable The cured adhesive was placed in a thimble filter paper and extracted with methyl ethyl ketone for 24 hours using a Soxhlet extractor. The residue in the thimble was dried, weighed, and the weight fraction of the insoluble content was calculated from the weight before extraction. Adhesion strength was measured after exposure for 300 hours in the accelerated weathering test (QUV). -The adhesion strength was measured after standing in water resistant water for 300 hours. -Heat resistance The adhesion strength was measured after leaving in a high-temperature bath at 80 ° C for 300 hours. -Adhesion strength was measured after standing for 24 hours in a 3% hydrochloric acid aqueous solution with chemical resistance. Tables 4 and 5 show the evaluation results of the cured adhesives obtained by the active energy ray-curable adhesives of Example 1 and Comparative Example 1. [Table 4] [Table 5] The active energy ray-curable adhesive of the present invention has excellent curability to active energy rays, adhesion strength to metals and plastics, flexibility, weather resistance, water resistance, heat resistance, and chemical resistance. A product with excellent properties is obtained.

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Claims (1)

(57) [Claims] [Claim 1] The number of repeating units of the component (1) obtained by reacting the following (1) to (3) is 2 or more, and per unit of the component (1) Urethane acrylate (A) having a molecular weight of 1,000 to 20,000 having 2.7 to 11 urethane bonding groups and / or urea bonding groups, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, toluyloxyethyl ( An active energy ray-curable adhesive characterized by containing (meth) acrylate, N-vinylpyrrolidone or (meth) acryloylmonophorin (B) (1) containing at least 40 mol% of an aromatic dicarboxylic acid, A copolymerized polyester polyol having a molecular weight of 1,000 to 10,000 (2) a polyisocyanate compound (3) at least one (meth) acryloyloxy group and at least one Compounds having a hydroxyl group