JP5454186B2 - Active energy ray reactive curable adhesive composition, label and bottle with excellent cleaning properties - Google Patents

Description

  The present invention relates to an active energy ray reaction curable adhesive composition containing at least a copolymerized saturated polyester resin, a (meth) acrylate monomer, and a photoinitiator. More specifically, the present invention relates to an adhesive composition for bottle labels that is particularly excellent in adhesiveness to a bottle label mainly composed of a film made of an aromatic resin such as PET and that is excellent in cleanability during recycling. In the present invention, (meth) acrylate refers to both acrylate and methacrylate.

  An active energy ray reaction curable adhesive is generally a (meth) acrylate monomer dissolved in a (meth) acrylic resin and further blended with a photoinitiator. It is used after being reactively cured by irradiation with active energy rays such as ultraviolet rays (hereinafter sometimes abbreviated as UV) and electron beams (hereinafter sometimes abbreviated as EB).

  Solvent-soluble adhesives inevitably involve evaporation of the solvent upon bonding. On the other hand, in the active energy ray reaction curable adhesive, the (meth) acrylate monomer is blended as a solvent and reactive monomer, and since it reacts and solidifies upon irradiation with the active energy ray, there is no emission of volatile organic matter, Even in environments where organic solvents cannot be used, they are used in a wide range of fields as so-called solventless adhesives. In particular, it is recognized as an adhesive suitable for packaging foods and pharmaceuticals.

  However, for plastic bottles and other bottles used in large quantities for beverages, aromatic resin films such as polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and polystyrene are used. In many cases, an adhesive mainly composed of a (meth) acrylic resin and a (meth) acrylate monomer has a problem of insufficient adhesion. In recent years, after film is wound around a bottle, the film is often heat-shrinked so as to conform to the shape of the bottle.

  Patent Document 1 and Patent Document 2 propose a heat shrink film in which an adhesive portion made of an ultraviolet curable adhesive having a viscosity at 90 ° C. of 3000 mPa · s or more is proposed. Although the strength can be improved, it does not improve the final adhesive strength after curing.

  For example, Patent Document 3 proposes a combination of two types of copolymer polyesters having different glass transition temperatures and a monofunctional (meth) acrylate monomer having an aromatic ring. Although this proposal can certainly balance the temporary adhesive force at the time of winding and the final adhesive force after curing, the adhesiveness is still insufficient.

  Generally, it is said that the closer the solubility parameter (SP value) between the adherend and the adhesive is, the more advantageous it is for improving the adhesive force. Therefore, in order to obtain an adhesive suitable for an aromatic film, an aromatic is used. It can be presumed that it is advantageous to blend a resin. However, aromatic resins are generally poorly soluble in (meth) acrylate monomers, do not dissolve in most (meth) acrylate monomers, or have poor solution stability even when dissolved, phase separation or cloudiness. In many cases, a transparent adhesive cannot be obtained.

  Further, even when a transparent adhesive is obtained in an uncured state, the adhesive layer is often whitened by phase separation after the adhesive is applied and cured. When whitening occurs, the quality of the bottle label deteriorates.

  The (meth) acrylate monomer having an aromatic ring such as phenoxyethyl acrylate and triloxyethyl acrylate used in Patent Document 3 has relatively good solubility in an aromatic resin, but as described above, It is difficult to obtain an adhesive composition having good adhesiveness.

  On the other hand, a used PET bottle has a recycling process, and for this purpose, the adhesive needs to be easily peeled off from the PET bottle when the PET bottle is washed. There has not yet been proposed an adhesive that has good adhesive force and can easily peel the adhesive layer from the PET bottle by washing.

JP 2007-308164 A JP 2007-308165 A Japanese Patent No. 3758085

  The object of the present invention is to exhibit high adhesion to aromatic films, good solution stability, no whitening even after reaction curing, and activity to easily peel off the adhesive layer by washing It is an object to provide an energy ray reaction curable adhesive composition, a label adhered using the composition, and a bottle equipped with the label.

  As a result of intensive studies on the active energy ray reaction curable resin composition in order to achieve the object of the present invention, the present inventors have given a specific polyester resin with a certain range of concentrations of a specific polyester group. ) Active energy ray reactive curable adhesive that is excellent in adhesive strength, solution stability and transparent even after reaction curing by combining with acrylate monomer, and can easily peel off the adhesive layer by alkali cleaning The inventors have found that a composition can be obtained and have reached the present invention.

That is, this invention is the active energy ray reaction hardening type adhesive composition excellent in the following detergency, and the adhesive for bottle labels using the same.
(1) In a resin composition containing at least a copolymerized saturated polyester resin, a (meth) acrylate monomer, and a photoinitiator, when the total of the copolymerized saturated polyester resin and the (meth) acrylate monomer is 100 parts by weight 20 to 50 parts by weight of the copolymerized saturated polyester resin and 50 to 80 parts by weight of the (meth) acrylate monomer are blended, and the total amount of the polyhydric alcohol components constituting the copolymerized saturated polyester resin is 100 mol%. The diethylene glycol is 5 mol% or more and 80 mol% or less, the specific gravity at 30 ° C. of the copolymerized saturated polyester resin is 1.30 or more and 1.40 or less, and the acid value is 100 equivalents / t or more and 500 equivalents. / T, and the (meth) acrylate monomer has an aromatic ring and a hydroxyl group. An active energy ray reaction curable adhesive composition characterized by the above.
(2) The active energy ray reaction curable adhesive according to (1), wherein the (meth) acrylate monomer is 2-hydroxy-3-phenoxypropyl acrylate or / and 2-hydroxy-3-phenoxypropyl methacrylate. Agent composition.
(3) The active energy ray reaction curable adhesive composition according to (1) or (2), wherein the copolymerized saturated polyester resin has a number average molecular weight of 8000 to 40,000.
(4) The active energy ray reaction curable adhesive composition according to any one of (1) to (3), wherein the dynamic viscosity at a temperature of 70 ° C. and an angular velocity of 5 rad / s is 5 dPa · s to 150 dPa · s.
(5) An adhesive composition for bottle labels using the active energy ray reaction curable adhesive composition according to any one of (1) to (4).
(6) A label adhered with the active energy ray reaction curable adhesive composition according to any one of (1) to (4).
(7) A heat-shrinkable label bonded with the active energy ray reaction curable adhesive composition according to any one of (1) to (4).
(8) A bottle equipped with the label according to (6) or (7).

  The active energy ray reaction curable adhesive composition of the present invention has good solution stability and excellent temporary fixing adhesive force, and is transparent and has high adhesive strength even after the curing reaction. When used for adhesion of a shrinkable label, it is excellent in maintaining adhesiveness after shrinkage, and the adhesive layer can be easily peeled off by alkali cleaning. For this reason, the label adhered using the adhesive composition of the present invention and the bottle equipped with the label can be easily recycled. .

  The copolymerized saturated polyester resin used in the present invention needs to be blended in an amount of 20 to 50 parts by weight per 100 parts by weight of the total weight of the copolymerized saturated polyester resin and the (meth) acrylate monomer of the present invention. 45 parts by weight is preferably blended, and more preferably 30 to 40 parts by weight. If the blending ratio of the copolymerized saturated polyester resin is too low, the adhesive strength to an aromatic film or the like tends to be low, and if it is too high, the viscosity of the adhesive composition tends to be too high and the handling tends to be difficult. .

  When the total amount of the polyhydric alcohol component constituting the copolymerized saturated polyester resin is 100 mol%, diethylene glycol is required to be 5 mol% or more and 80 mol% or less, preferably 10 mol% or more. It is 70 mol% or less, More preferably, it is 15 mol% or more and 65 mol% or less, More preferably, it is 20 mol% or more and 60 mol% or less. If the ratio of diethylene glycol is too low, the adhesiveness to an aromatic film such as a PET film may be lowered, and if too high, the water resistance may be lowered.

  The components other than diethylene glycol constituting the copolymerized saturated polyester resin are not particularly limited, and general-purpose acid components and glycol components can be used.

  Examples of the acid component include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid and other aromatic dibasic acids, p-oxybenzoic acid, Aromatic oxycarboxylic acids such as p- (hydroxyethoxy) benzoic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, dimer acid, cyclohexanedicarboxylic acid and other aliphatic dicarboxylic acids. Two or more selected may be used in combination. The acid component is preferably composed mainly of an aromatic dibasic acid, and has an effect of increasing the adhesive force to an aromatic film such as a PET film. The total of terephthalic acid and isophthalic acid is preferably 75% by weight or more of the acid component constituting the copolymerized saturated polyester resin, more preferably 90% by weight or more, and still more preferably 95% by weight or more.

  Examples of the glycol component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, and 3-methylpentanediol. 1,6-hexanediol, nonanediol, methyloctanediol, neopentyl glycol, dipropylene glycol, 2-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3- Pentanediol, cyclohexanedimethanol, dimerdiol, neopentylglycol hydroxypivalate, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, ethylene oxide adduct of hydrogenated bisphenol A, hydrogenation Propylene oxide adduct of scan phenol A and the like. Further, high molecular weight glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone, and polycarbonate diol may be copolymerized. Moreover, you may use together 2 or more types chosen from these.

  Examples of the copolymerized saturated polyester resin used in the present invention include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, sodium sulfoterephthalic acid, 2-sodium sulfo-1,4-butanediol, and 2,5-dimethyl. You may copolymerize the acid component and / or glycol component which have sulfonic-acid metal bases, such as -3-sodium sulfo-2,5-hexanediol. Adhesion may be improved by copolymerizing an acid component and / or glycol component having a sulfonic acid metal base.

  Further, as a part of the raw material of the copolymerized saturated polyester resin used in the present invention, a tri- or higher functional compound such as trimellitic anhydride, glycerin, trimethylolpropane, pentaerythritol may be copolymerized, and the adhesiveness is increased. May improve. Moreover, after polyester is polymerized, a terminal-modified component such as a lactone or an acid anhydride may be introduced, and the adhesion may be improved.

  The copolymerized saturated polyester resin used in the present invention has a specific gravity at 30 ° C. of 1.30 or more and 1.40 or less, and preferably 1.33 or more and 1.38 or less. If the specific gravity at 30 ° C. is too low, the adhesiveness to aromatic films such as PET film may be reduced. Conversely, if the specific gravity is too high, the solubility in (meth) acrylate monomer tends to be low, and it is dissolved. Even so, the solution stability may deteriorate. In order to set the specific gravity at 30 ° C. of the copolymerized saturated polyester resin to 1.30 or more and 1.40 or less, for example, only an aromatic dicarboxylic acid is used as the acid component, and ethylene glycol and diethylene glycol are used as the glycol component, and the ratio of diethylene glycol is changed. What is necessary is just to make it 20 mol%.

  The copolymerized saturated polyester resin used in the present invention has an acid value per ton of resin of 100 equivalent / t or more and less than 500 equivalent / t, preferably 150 equivalent / t or more and less than 300 equivalent / t. It is. If the acid value is too low, peeling by alkali cleaning tends to be difficult. Conversely, if the acid value is too high, the polarity of the polyester will increase, and the adhesiveness may deteriorate due to the influence of steam etc. in the label shrinking process. is there. In order to obtain a polyester resin having an acid value per ton of resin of 100 equivalents / t or more and less than 500 equivalents / t, for example, a polyester resin mainly composed of hydroxyl terminal is produced by a conventional method, and then an acid anhydride is added to perform terminal modification. Just do it. Preferred examples of the acid anhydride used here include trimesic anhydride, trimellitic anhydride, ethylene glycol bistrimellitic dianhydride, phthalic anhydride, pyromellitic anhydride, succinic anhydride, 1,8-naphthalic anhydride 1,2-cyclohexanedicarboxylic anhydride, cyclohexane-1,2,3,4-tetradicarboxylic acid 3,4-anhydride, ethylene glycol bisambitro trimellitate, 5- (2,5-dioxotetrahydro- 3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, naphthalene 1,8: 4,5-tetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, and the like. .

  The copolymerized saturated polyester resin used in the present invention may be composed of only one type of copolymerized saturated polyester resin, or may be composed of two or more types in combination.

  The (meth) acrylate monomer constituting the active energy ray reaction curable adhesive composition of the present invention has an aromatic ring and a hydroxyl group. By using such a (meth) acrylate monomer, a high adhesive force is obtained, the solubility of the copolymerized saturated polyester resin is good, the solution stability of the adhesive composition is good and the reaction cured The adhesive layer is also transparent.

  The (meth) acrylate monomer used in the present invention needs to be blended in an amount of 50 to 80 parts by weight per 100 parts by weight of the total weight of the copolymerized saturated polyester resin of the present invention and the (meth) acrylate monomer. 75 parts by weight is preferably blended, more preferably 60 to 70 parts by weight. If the blending ratio of the (meth) acrylate monomer is too low, the viscosity of the composition tends to be too high and the handling tends to be difficult, and the final adhesive force after curing tends to be low due to insufficient curing. On the other hand, when the blending ratio of the (meth) acrylate monomer is too high, the viscosity becomes too low and the temporary fixing adhesive force tends to be lowered.

  As the (meth) acrylate monomer used in the present invention, 2-hydroxy-3-phenoxypropyl (meth) acrylate, p-methoxyphenoxyethyl (meth) acrylate, o-methoxyphenoxyethyl (meth) acrylate, 2- (meth) Acryloyloxyethyl-2-hydroxypropyl phthalate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate, (meth) acrylic acid adduct of bisphenol A diglycidyl ether, (meth) acrylic acid of bisphenol F diglycidyl ether Additives and the like.

  Among these, 2-hydroxy-3-phenoxypropyl acrylate and 2-hydroxy-3-phenoxypropyl methacrylate are preferable, and 2-hydroxy-3-hydroxy is most preferable because of the solubility and ease of handling of the copolymerized saturated polyester resin used in the present invention. -3-phenoxypropyl acrylate.

  The number average molecular weight of the copolymerized saturated polyester resin used in the present invention is preferably 8000 or more and 40,000 or less. If the molecular weight is too low, the adhesiveness to an aromatic film such as a PET film may be reduced. On the other hand, if the molecular weight is too high, the viscosity of the composition becomes too high and handling becomes difficult. There is a tendency for the solubility of to decrease. More preferably, it is 10,000 or more and 30000 or less.

  The glass transition temperature of the copolymerized saturated polyester resin used in the present invention (hereinafter sometimes abbreviated as Tg) is not particularly limited, but if it is a resin having a very low Tg, it can be cured as an adhesive. Since there exists a possibility that it may protrude from an adhesive layer with a heat | fever, the one higher than normal temperature is preferable and 40 degreeC or more is more preferable.

  The photoinitiator used in the present invention is not particularly limited. For example, chloroacetophenone, 4-phenoxydichloroacetophenone, 4-t-butyltrichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1 -Phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenyl (4-dodecyl) propane-1- ON, 4- (2-hydroxyethoxyphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl-phenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2- Morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4 Morpholinophenyl) -butanone-1, phenyl 2-hydroxy-2-propyl ketone, acetophenones such as hydroxyacetophenone, α-aminoacetophenone, benzyldimethyl ketal (2,2-dimethoxy-1,2-diphenylethane-1- ON) and other ketals, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin alkyl ether, benzoins such as α-methylbenzoin, benzophenone, methyl o-benzoylbenzoate, 4-phenyl Benzophenone, p-chlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3'- Methyl-4-methoxybenzophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 4,4 ′-(dimethylamino) benzophenone, p-dimethylaminobenzophenone, [4- (methyl Benzophenones such as phenylthio) phenyl] phenylmethanone, anthraquinones such as 9,10-anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 1 Propiofenones such as-(4-isopropylphenyl) -2-hydroxy-2-methylpropiophenone, Suberons such as dibenzosuberone, Michler ketones such as Michler ketone (4,4-bis (dimethylamino) benzophenone) , Benji Benzyls such as, diphenyl disulfide, tetramethylthiuram disulfide, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4 -Sulfur-containing compounds such as thioxanthones such as diisopropylthioxanthone and 1-chloro-4-propoxythioxanthone, and pigments such as methylene blue, eosin and fluorescein. In addition, 1,1-dichloroacetophenone, 1-hydroxy-cyclohexyl-phenyl-ketone, azobisisobutylnitrile, benzoyl peroxide, di-tert-butyl peroxide, 2,4,6-trimethylolbenzophenone, 4-methylbenzophenone 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl) propanone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,2 -Dichloro-p-phenoxyacetophenone, 1-phenyl-1,2-propanedione-2 (o-ethoxycarbonyl) oxime, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, methylphenylglyoxyester, 9,10- Phenanthrene Non, camphorquinone, dibenzosuberone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-benzyl-2-dimethylamino-1 -(4-morpholinophenyl) -butanone-1, phenanthrenequinone, 1,4-dibenzoylbenzene, 10-butyl-2-chloroacridone, 2,2'-bis (o-chlorophenyl) -4, 5,4 ′, 5′-tetrakis (3,4,5-trimethoxyphenyl) -1,2′-biimidazole, 2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5 ′ -Tetraphenyl-1,2'-biimidazole, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyldiphenyl ether, acrylated benzophenone, etc. .

  These photoinitiators may be used alone or in combination of two or more. The compounding amount of these photoinitiators is 0.05 parts by weight or more and 20 parts by weight or less, more preferably 0.5 parts by weight or more and 10 parts by weight or less based on the entire resin composition.

  The viscosity of the adhesive composition of the present invention is 5 to 150 dPa · s, preferably 15 to 80 dPa · s, more preferably 25 to 75 dPa · s at a temperature of 70 ° C. and an angular velocity of 5 rad / s. . If the viscosity is too low, the temporary fixing adhesive force when applying the adhesive composition to the adherend tends to be inferior, and dripping tends to occur during application. On the other hand, if it is too high, coating tends to be difficult and handling tends to be difficult.

  As a typical usage method of the adhesive composition of the present invention, it can be used for adhesion of labels of PET bottles and other bottles used in large quantities for beverages and the like. Aromatic resin films such as PET and polystyrene are often used for these labels, and the adhesive composition of the present invention exhibits high adhesion to labels made of these materials. The material is not limited to these materials. In recent years, after a label is wound on a bottle, a method of heat shrinking and conforming to the shape of the bottle is often taken, and an increasingly higher adhesive force is required. In a preferred embodiment of the present invention, this method is used. It is also suitable for bonding such heat shrink labels.

  On the other hand, used PET bottles are required to be recycled from the environmental aspect. Cleaning is performed at the time of recycling, and an alkaline warm aqueous solution is generally used as the cleaning liquid. Since the adhesive composition of the present invention can easily peel off the adhesive layer by washing with alkaline hot water, a bottle attached with a label adhered using the adhesive composition of the present invention has been conventionally used. Can be easily recycled by a recycling process including an alkaline cleaning process or by slightly changing cleaning conditions such as cleaning time, alkali concentration, and temperature.

  Hereinafter, the present invention will be described specifically by way of examples. In the examples, “parts” means “parts by weight”.

<Characteristic evaluation method of polyester resin>
1. Composition The sample resin was dissolved in chloroform-d, and the resin composition and composition ratio were determined by ¹ H-NMR spectrum using a 400 MHz-NMR apparatus manufactured by VARIAN.

2. Number average molecular weight The sample resin was dissolved or diluted in tetrahydrofuran so that the resin concentration was about 0.5% by weight, and filtered through a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm to obtain a GPC measurement sample. GPC measurement of a resin sample using tetrahydrofuran as a mobile phase, a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation, and a differential refractometer (RI meter) as a detector at a column temperature of 30 ° C. and a flow rate of 1 ml / min. Was done. Using the GPC measurement result of monodisperse polystyrene having a known number average molecular weight, the number average molecular weight in terms of polystyrene of the sample resin was determined, and this was used as the number average molecular weight of the sample resin in the present invention. However, shodex KF-802, 804L, and 806L manufactured by Showa Denko KK were used as the column.

3. Glass transition temperature 5 mg of sample resin is put in an aluminum sample pan, sealed, and heated to 200 ° C. using a differential scanning calorimeter (DSC) DSC-220 manufactured by Seiko Instruments Inc. It was measured at the temperature of the intersection of the extended line of the base line below the glass transition temperature and the tangent showing the maximum inclination at the transition part.

4). Specific resin The resin piece of the sample resin was put into a 30 ° C calcium chloride aqueous solution, and the specific gravity of the calcium chloride aqueous solution was adjusted by adding calcium chloride or water so that the resin piece stayed in the aqueous solution without floating or settling. . Next, the specific gravity of the aqueous solution at 30 ° C. was measured using a float / sink type standard specific gravity meter, and the specific gravity at 30 ° C. of the sample resin was determined.

5. Acid value 0.2 g of a sample was dissolved in chloroform, titrated with 0.1 mol / l potassium hydroxide-ethanol solution using phenolphthalein as an indicator, and indicated by the number of equivalents per ton (equivalent / t).

<Synthesis of copolymerized saturated polyester resin>
<Synthesis example of polyester (a)>
In a reaction vessel equipped with a stirrer, thermometer, and distillation condenser, 433 parts by weight of dimethyl terephthalate, 415 parts by weight of dimethyl isophthalate, 26 parts by weight of dimethyl ester of 5-sodium sulfoisophthalic acid, 332 parts by weight of ethylene glycol, diethylene glycol 378 parts by weight and 0.3 parts by weight of tetrabutyl titanate were added, and a transesterification reaction was carried out at 170 to 220 ° C. under normal pressure for 3 hours. Next, the temperature of the reaction system was raised from 220 ° C. to 260 ° C., and the pressure inside the system was slowly reduced to 500 Pa over 60 minutes, and a polycondensation reaction was performed at 130 Pa or less for 60 minutes. After completion of the polycondensation, the inside of the can was returned to normal pressure with nitrogen, cooled to 220 ° C., 17 parts by weight of trimellitic anhydride (hereinafter sometimes abbreviated as TMA) was added, an addition reaction was performed, and polyester ( a) was obtained.

  Polyester (a) is 50 mol% terephthalic acid as an acid component, 48 mol% isophthalic acid, 2 mol% 5-sodiumsulfoisophthalic acid, 40 mol% ethylene glycol as a diol component, 60 mol% diethylene glycol, as a post-addition TMA It had a composition of 2 mol%. The glass transition temperature was 41 ° C., the number average molecular weight was 26000, the specific gravity was 1.35 at 30 ° C., and the acid value was 165 equivalent / t.

<Synthesis example of polyester (b)>
In the same reaction vessel as in the synthesis example of polyester (a), 363 parts by weight of terephthalic acid, 355 parts of isophthalic acid, 8.4 parts of trimellitic anhydride, 246 parts of ethylene glycol, 389 parts of diethylene glycol, 0.4% of tetrabutyl titanate. 3 parts by weight was added, and pressure esterification reaction was performed at 190 to 240 ° C. at 250 kPa for 3 hours. After completion of the esterification reaction, the reaction system was heated from 240 ° C. to 260 ° C., and the pressure inside the system was slowly reduced to 500 Pa over 60 minutes, and a polycondensation reaction was performed at 130 Pa or less for 60 minutes. After completion of the polycondensation, the inside of the can was returned to atmospheric pressure with nitrogen and then cooled to 220 ° C., 17 parts of trimellitic anhydride, ethylene glycol bistrimellitic dianhydride (Rikacide TMEG-200 manufactured by Shin Nippon Rika Co., Ltd. 18 parts (sometimes abbreviated as TMEG) were added to carry out an addition reaction to obtain polyester (b).

  Polyester (b) is 50 mol% terephthalic acid as an acid component, 49 mol% isophthalic acid, 1 mol% trimellitic acid, 35 mol% ethylene glycol, 65 mol% diethylene glycol as a diol component, and 2 mol% as a post-addition TMA. TMEG had a composition of 1 mol%. The glass transition temperature was 34 ° C., the number average molecular weight was 18000, the specific gravity was 1.34 at 30 ° C., and the acid value was 280 equivalent / t.

<Synthesis examples of polyesters (c) to (e) and (g) to (j)>
Polyesters (c) to (e) and (g) to (j) were synthesized in the same manner as polyester (b) except that only the charged composition was changed. Table 1 shows the measurement results of the composition and properties of the obtained polyester.

<Synthesis example of polyester (f)>
440 parts by weight of dimethyl terephthalate, 422 parts by weight of dimethyl isophthalate, 27 parts by weight of dimethyl ester of 5-sodium sulfoisophthalic acid, 332 parts by weight of ethylene glycol, diethylene glycol in a reaction vessel equipped with a stirrer, a thermometer and a condenser for distillation 378 parts by weight and 0.3 parts by weight of tetrabutyl titanate were added, and a transesterification reaction was carried out at 170 to 220 ° C. under normal pressure for 3 hours. Next, the temperature of the reaction system was raised from 220 ° C. to 260 ° C., and the pressure inside the system was slowly reduced to 500 Pa over 60 minutes. Further, a polycondensation reaction was performed at 130 Pa or less for 60 minutes to obtain polyester (f).

  Polyester (f) has a composition of 50 mol% terephthalic acid, 48 mol% isophthalic acid, 2 mol% 5-sodium sulfoisophthalic acid as an acid component, 40 mol% ethylene glycol as a diol component, and 60 mol% diethylene glycol. It was. The glass transition temperature was 40 ° C., the number average molecular weight was 25000, the specific gravity was 1.36 at 30 ° C., and the acid value was 10 equivalent / t.

In addition, the symbol regarding the composition in Table 1 and Table 2 has the following meaning.
TPA: terephthalic acid IPA: isophthalic acid GCM: 5-sodium sulfoisophthalic acid SA: sebacic acid TMA: trimellitic acid DEG: diethylene glycol EG: ethylene glycol NPG: neopentyl glycol TMEG: ethylene glycol bis trimellitate dianhydride RIKACID TMEG-200 manufactured by Rika Co., Ltd.)

<Example 1>
After mixing 30 parts of polyester (a) and 64 parts of 2-hydroxy-3-phenoxypropyl acrylate to completely dissolve polyester (a), 3 parts of 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy as a photoinitiator -2-Methylpropiophenone 3 parts was blended to obtain an active energy ray reaction curable adhesive composition. Subsequently, the characteristics of the adhesive composition were evaluated by a method described separately. Table 3 shows the composition of the adhesive composition and the evaluation results of the adhesive composition characteristics.

<Examples 2-5, Comparative Examples 1-10>
Active energy ray reaction curable adhesive compositions of Examples 2 to 5 and Comparative Examples 1 to 10 were obtained in the same manner as in Example 1. Tables 3 and 4 show the composition of the adhesive composition and the evaluation results of the adhesive composition characteristics.

In addition, the symbol regarding the composition in Table 3 and Table 4 has the following meaning.
(Meth) acrylate monomer Ma: 2-hydroxy-3-phenoxypropyl acrylate Mb: 2-hydroxy-3-phenoxypropyl methacrylate Mc: 2-acryloyloxyethyl-2-hydroxyethyl phthalate Md: phenoxyethyl acrylate Me: 2-hydroxy -1,3-dimethacryloxypropane Mf: 4-hydroxybutyl acrylate photoinitiator Ra: 1-hydroxycyclohexyl phenyl ketone Rb: 2-hydroxy-2-methylpropiophenone Rc: 2,2-dimethoxy-2-phenyl Acetophenone

<Method for evaluating properties of adhesive composition>
<Viscosity>
Using an rheometer AR550 manufactured by TA Instruments, the adhesive composition was sandwiched and heated in an aluminum pan with a diameter of 25 mm, and the temperature was fixed at 70 ° C., and the angular velocity was changed from 250 rad / s to 1 rad / s. The value of the dynamic viscosity at the time of angular velocity = 5 rad / s was taken as the viscosity in this patent.

<Solution stability evaluation method>
After the active energy ray reaction curable adhesive compositions obtained in Examples and Comparative Examples were cooled to 5 ° C. and allowed to stand for 24 hours, the state of the solution was visually confirmed, and then heated to 25 ° C. and after 4 hours had passed. The state of the solution was visually observed.
A: Uniform solution transparent at 5 ° C., Uniform solution transparent at 25 ° C .: White turbidity at 5 ° C., Transparent uniform solution when returned to 25 ° C. Δ: White turbidity at 5 ° C. Precipitates remain at ℃ and remain even after returning to 25 ℃

<Method for evaluating transparency after curing>
The active energy ray reaction curable adhesives obtained in Examples and Comparative Examples were applied on a transparent shrinkage PET film having a thickness of 25 μm so as to have a thickness of 5 μm, laminated with the same film, and then manufactured by Toshiba Corporation. Using a UV lamp H8000L / 2, UV irradiation was performed so that the irradiation amount was 150 mJ / cm ² , and a laminated laminated film was prepared. The transmittance of the laminated laminate film was measured at a wavelength of 600 nm using a spectrophotometer U-3210 manufactured by Hitachi, Ltd., and the transparency was evaluated in the following three stages.
○: Transmittance of 95% or more Δ: Transmittance of 90% or more and less than 95% ×: Transmittance of less than 90%

<Adhesion evaluation method>
In the same manner as in the above <Transparency evaluation method after curing>, the active energy ray reaction curable adhesives obtained in the examples and comparative examples were prepared, and then the laminated laminated film was cut into a width of 15 mm, A tensile test was performed in a T-shaped (180 °) peeling mode at a temperature of 23 ° C. and a humidity of 50% at a tensile speed of 100 mm / min, and the adhesive strength after curing was measured.

<Shrinkage resistance evaluation method>
A laminated laminate film obtained in the same manner as in the above <Adhesive evaluation method> was cut to a width of 15 mm to obtain a strip-shaped test piece having a length of 100 mm. This was poured into 90 ° C. warm water and allowed to stand for 30 seconds to shrink the PET film, and then allowed to cool at room temperature. The edge of the test piece cut to a width of 15 mm was observed and evaluated according to the following four levels.
(Double-circle): A blur cannot be detected visually from the end surface in the width direction.
○: Swelling of less than 1 mm in the width direction from the end face.
Δ: Swelling of 1 mm or more and less than 2 mm in the width direction from the end face.
X: 2 mm or more of rolling in the width direction from the end face, or peeling of the entire surface.

<Alkali detergency evaluation method>
The active energy ray reaction curable adhesives obtained in Examples and Comparative Examples were applied on a transparent shrinkage PET film having a thickness of 50 μm so as to have a thickness of 5 μm, and then a UV lamp H8000L / 2 manufactured by Toshiba Corporation was applied. UV irradiation was performed so that the irradiation amount was 150 mJ / cm ² . The adhesive-coated film was cut into a width of 30 × 15 mm, immersed in a 1.5% aqueous sodium hydroxide solution, heated to 80 ° C. and stirred for 10 minutes, and the detergency was evaluated in the following four stages.
A: No adhesive remains on the PET film.
○: Less than 5% by weight of the adhesive remains in the PET film.
Δ: 5% by weight or more and less than 50% by weight of the adhesive remains in the PET film.
X: 50% by weight or more of the adhesive remains in the PET film.

  As shown in Table 3 and Table 4, Examples 1 to 5 have superior performance in terms of solution stability, adhesiveness, post-curing transparency, shrink-resistant adhesiveness, and alkali washability compared to Comparative Examples 1-10. I understand.

  The active energy ray reaction curable adhesive composition of the present invention is transparent and high in adhesive strength even after reaction curing, and is excellent in maintaining adhesiveness after shrinkage when used for adhesion of shrinkable labels. Furthermore, the adhesive layer can be easily peeled off by washing with alkaline hot water. Therefore, it is particularly suitable for bonding a heat-shrinkable label made of an aromatic resin such as a PET film, and when used as an adhesive for a shrinkable bottle label, a bolt that can be easily recycled can be obtained.

Claims (8)

  In a resin composition containing at least a copolymerized saturated polyester resin, a (meth) acrylate monomer, and a photoinitiator, the copolymerization when the total of the copolymerized saturated polyester resin and the (meth) acrylate monomer is 100 parts by weight. When 20 to 50 parts by weight of the saturated polyester resin and 50 to 80 parts by weight of the (meth) acrylate monomer are blended, and the total amount of the polyhydric alcohol components constituting the copolymerized saturated polyester resin is 100 mol%, Diethylene glycol is 5 mol% or more and 80 mol% or less, the specific gravity at 30 ° C. of the copolymerized saturated polyester resin is 1.30 or more and 1.40 or less, and the acid value is 100 equivalents / t or more and less than 500 equivalents / t. And the (meth) acrylate monomer has an aromatic ring and a hydroxyl group. Active energy ray curable adhesive composition, characterized in that.   2. The active energy ray reaction curable adhesive composition according to claim 1, wherein the (meth) acrylate monomer is 2-hydroxy-3-phenoxypropyl acrylate or / and 2-hydroxy-3-phenoxypropyl methacrylate. .   3. The active energy ray reaction curable adhesive composition according to claim 1, wherein the copolymerized saturated polyester resin has a number average molecular weight of 8000 or more and 40000 or less.   4. The active energy ray reaction curable adhesive composition according to claim 1, wherein the dynamic viscosity at a temperature of 70 ° C. and an angular velocity of 5 rad / s is 5 dPa · s or more and 150 dPa · s or less.   The adhesive composition for bottle labels using the active energy ray reaction hardening type adhesive composition in any one of Claims 1-4.   A label adhered by the active energy ray reaction curable adhesive composition according to claim 1.   A heat-shrinkable label adhered by the active energy ray reaction curable adhesive composition according to claim 1.   A bottle equipped with the label according to claim 6 or 7.