JP2002155264A - Delayed tack adhesive composition and adhesive label - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Without using dicyclohexyl phthalate,
When coating on a substrate to produce a heat-sensitive adhesive label, it can be heated and dried at a higher temperature, has low foaming properties, has good coating suitability, and has anti-blocking properties and adhesion during storage. Provided are a delayed tack type pressure-sensitive adhesive composition which has excellent adhesiveness and can maintain its adhesiveness for a long time, and a pressure-sensitive adhesive label using the same. SOLUTION: The first constitution is an aqueous dispersion type delayed tack adhesive composition comprising a thermoplastic resin, a tackifier resin and a solid plasticizer, wherein a carboxylic acid-containing dispersant is used as an aqueous dispersant for the solid plasticizer. A delayed tack-type pressure-sensitive adhesive composition comprising a polymer, and a second configuration is a delayed tack-type pressure-sensitive adhesive label having a pressure-sensitive adhesive composition layer provided on a substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a heat-sensitive material which is non-tacky at room temperature but develops tackiness by heating, and after tackiness is developed, the tackiness is maintained for a while even if a heating source is removed. The present invention relates to a delayed tack type pressure-sensitive adhesive composition and a heat-sensitive pressure-sensitive adhesive label.

[0002]

2. Description of the Related Art As described in "Adhesion Handbook" (Twelveth Edition, published in 1955, published by Kobunshi Kanko), conventional heat-sensitive delayed-tack type pressure-sensitive adhesives are used in combination with thermoplastic resins and tackifying resins. And a solid plasticizer as a basic skeleton. The thermoplastic resin is the basis of the pressure-sensitive adhesive, and without this, no cohesive force at the time of use can be obtained. In addition, solid plasticizers do not impart plasticity to the resin at room temperature, and melt first into the resin when heated to swell or soften the resin. Acts to express As the solid plasticizer, for example, dicyclohexyl phthalate is well known (JP-A-61-9479, JP-A-7-278).
521, JP-A-8-333565, etc.).

In recent years, the above-mentioned delayed tack-type pressure-sensitive adhesive label is often produced by applying an emulsion-type heat-sensitive pressure-sensitive adhesive to the back surface of a substrate and then heating it for drying. In that case, the heating temperature is required to be a low temperature of 40 ° C. or less so that the dicyclohexyl phthalate does not melt and develop adhesiveness at the stage of forming the adhesive layer. However, such low-temperature heating requires a long time for the heating and drying step, and thus has a problem that the productivity of the delayed tack adhesive label is reduced. In addition, since the release tack is not used in the delayed tack type adhesive label as described above, the plastic resin of the binder resin due to dicyclohexyl phthalate gradually occurs while being stacked, for example, when stored for a long time at a high temperature in summer, So-called blocking in which the labels adhere to each other occurs. Therefore, there is a problem that a cooling device for preventing such blocking is required. In addition, the delayed tack adhesive has the property of not sticking at room temperature before heating by using a crystalline solid plasticizer, but if it solidifies quickly after heating and crystallization occurs, it will cause sticking of coated labels etc. There is a contradiction that sex is lost. Since dicyclohexyl phthalate, which has been conventionally used, is rapidly recrystallized, a solid plasticizer capable of further extending the stickiness retention period has been desired. Furthermore, in recent years, there has been a concern about the use of a phthalate compound containing dicyclohexyl phthalate, which is an environmental hormone analog, and in particular, as a delayed tack type pressure-sensitive adhesive composition used for beverage bottle labels, dedicyclohexyl phthalate is desired. I have.

[0004] Further, it is required to make the pressure-sensitive adhesive composition aqueous, and in particular, anionic emulsifiers, nonionic emulsifiers, water-soluble resins, and the like have been used as dispersants for aqueous solid plasticizers.
Examples of the anionic emulsifier include a fatty acid salt, an alkyl sulfate salt, an alkylbenzene sulfonate, an alkyl sulfosuccinate, an alkyl phosphate, and the like. Examples of the nonionic emulsifier include polyoxyethylene alkyl ether and polyoxyethylene alkyl aryl ether. ,
Polyoxyethylene / oxypropylene block polymers, sorbitan fatty acids, polyoxy fatty acid esters, polyoxyethylene alkylamines, and the like are included. Examples of water-soluble resins include methyl cellulose, polyvinyl alcohol, sodium polycarboxylate, maleic acid resins, and gelatin. . JP-A-8-333565 describes an example of nonylphenylalkylene ether as a nonionic surfactant.

However, a coating machine such as a gravure coater, a lip coater or a roll coater is used to apply the delayed tack type adhesive to the label paper. At the time of coating with these machines, in order to supply the delayed tack type adhesive to the coating roll, it is circulated and supplied by a circulation pump while constantly mixing and stirring in an adhesive storage tank. Therefore, it is easy to foam, and the foaming may cause a coating failure such as overflowing from the liquid storage tank, contaminating other than the coated surface, and furthermore, a predetermined amount of coating may not be obtained, and adhesiveness may be insufficient. is there. In particular, water dispersion liquids originally foam easily when stirred, unlike alcoholic solutions, etc., so foaming has been reduced by adding a silicon-based antifoaming agent, etc., but in this case the antifoaming agent reduces the adhesiveness Tend to. Therefore, an aqueous dispersion of a delayed tack-type pressure-sensitive adhesive with reduced foaming properties has been required.

In general, solid plasticizers, which are low-molecular ester compounds, have high polarity and are difficult to disperse in water with emulsifiers. In particular, the blocking tacking temperature of delayed tack adhesives is improved and the recrystallization property is delayed. Benzoic acid esters and hindered phenol ester compounds which are effective for water have high hydrophilicity and are difficult to disperse in water with conventional emulsifiers.

[0007]

An object of the present invention is to carry out heat drying at a higher temperature when producing a heat-sensitive adhesive label by coating on a substrate without using dicyclohexyl phthalate. And a delayed tack-type pressure-sensitive adhesive composition that has low foaming properties, good coating suitability, excellent blocking resistance during storage and adhesion, and can maintain the adhesion for a long period of time, and an adhesive label using the same. Is to provide.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have searched for a dispersant for a solid plasticizer in order to overcome the above-mentioned problems, and as a result, a specific carboxylic acid-containing copolymer has been used as a dispersant for a solid plasticizer. Has been found to have suitable performance, leading to the present invention. That is, the constitution of the present invention is (1) an aqueous dispersion-type delayed tack adhesive composition comprising a thermoplastic resin, a tackifier resin and a solid plasticizer, wherein the solid plasticizer contains carboxylic acid as an aqueous dispersant. A delayed tack-type pressure-sensitive adhesive composition comprising a copolymer.

The present invention also provides (2) a delayed tack-type pressure-sensitive adhesive composition according to (1), wherein the carboxylic acid-containing copolymer is a styrene-maleic acid resin and / or an acrylic ester-acrylic acid resin. (3) The delayed tack-type pressure-sensitive adhesive composition according to (1) or (2), wherein the solid plasticizer is a benzoate compound.
(4) The delayed tack-type pressure-sensitive adhesive composition according to the above (1) or (2), wherein the solid plasticizer is a hindered phenol ester compound, and (5) a butadiene in which the thermoplastic resin is not tacky at room temperature or lower. The delayed tack-type pressure-sensitive adhesive composition according to any one of (1) to (4), which is an aqueous dispersion of at least one resin selected from a copolymer, a vinyl acetate copolymer, and an acrylic copolymer, (6) a delayed tack-type pressure-sensitive adhesive composition layer containing a thermoplastic resin, a tackifier resin, a solid plasticizer and a carboxylic acid-containing copolymer,
It is a delayed tack type pressure-sensitive adhesive label provided on a label substrate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic resin, tackifying resin, solid plasticizer and dispersant of the solid plasticizer, which are constituent elements of the present invention, will be described in detail below.

The thermoplastic resin used in the delayed tack adhesive composition of the present invention has no tackiness at room temperature or lower, that is, the polymer has a glass transition temperature of at least -2.
A resin at 0 ° C. or higher is used. For example, acrylate, styrene-acrylate, styrene-butadiene, vinyl acetate, ethylene-vinyl acetate, vinyl acetate-acrylate, ethylene-acrylate, ethylene-acrylic acid, butadiene copolymer, urethane, styrene-isoprene block Thermoplastic resins such as polymers can be used.

The tackifier used in the delayed tack adhesive composition of the present invention includes, for example, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, cumarone-indene resin, styrene resin, phenol resin, Aqueous dispersions of terpene-phenol resins, rosin derivatives (rosin, polymerized rosin, hydrogenated rosin and their esters with glycerin, pentaerythritol, etc., resin acid dimer, etc.) are mentioned.

The solid plasticizer used in the delayed tack adhesive composition of the present invention includes a benzoate compound,
Hindered phenol ester compounds and the like are preferably used. Solid plasticizers are required to have a long time until recrystallization. Particularly, in the case of benzoic acid ester, a triester with a trifunctional alcohol is required to balance the time until recrystallization and the activation temperature. Preferred from above. The activation temperature of the delayed tack adhesive depends on the heating device, but is usually 60 to 100 ° C. Therefore, the benzoic acid ester having a melting point in the range of 75 to 90 ° C as a solid plasticizer is considered to be a delayed tack adhesive. It is preferable from the viewpoint of storage management and activation energy of the agent. Examples of the benzoate compound as a solid plasticizer include sucrose benzoate, diethylene glycol benzoate, glyceride benzoate, pentaerythritol benzoate, trimethylolethane benzoate, and trimethylolpropane benzoate. Trimethylol benzoate propane ester is most preferably used.

Examples of the hindered phenol ester compound as a solid plasticizer include triethylene glycol bis [3- (3-t-butyl-4-hydroxyphenyl) propionate] and triethylene glycol bis [3-
(3-t-butyl-4-hydroxy-5-methylphenyl) propionate], triethylene glycol bis [3- (3,5-di-t-butyl-4-hydroxy-phenyl) propionate], 1,6- Hexanediol bis [3- (3-t-butyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], thiobis [ethylene 3
-(3-t-butyl-4-hydroxyphenyl) propionate], thiobis [ethylene 3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], thiobis [ethylene 3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate]. Particularly preferred solid plasticizers include triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], 1,6
Hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and thiobis [ethylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] No.

The above thermoplastic resins, tackifiers and solid plasticizers can be used alone or as a mixture of two or more as an aqueous dispersant or an aqueous solution. In particular, the solid plasticizer can maintain a good dispersion state by using the dispersant of the present invention. Dispersant or defoamer, if necessary
Thickeners and the like can also be used.

As an essential component of the present invention, an aqueous dispersant of a solid plasticizer containing a carboxylic acid-containing copolymer is used. Examples of the carboxylic acid-containing copolymer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, a copolymer containing maleic acid, and a styrene-maleic acid resin and / or an acrylic ester-acrylic acid resin are preferable. Used.

As the styrene-maleic acid resin, a resin having a weight average molecular weight in the range of 1,000 to 10,000 is preferable. Examples of the acrylic ester-acrylic acid resin include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethylhexyl acrylate, and the like, and a copolymer of acrylic acid or methacrylic acid, and have a weight average molecular weight of 3,000 to 300.
A range of 00 is preferred.

It is preferable that the solid plasticizer dispersant of the present invention is blended in an amount of 3 to 10 parts by weight with respect to the solid plasticizer. The aqueous dispersion of the solid plasticizer has a solid content of 50 to 70% by weight.
Is preferred. The dispersing agent may be in the form of a powder or granule, or may be incorporated as an aqueous solution. In any case, after compounding, a pulverizing and dispersing step such as a ball mill or a handy mill is required.

In order to obtain the delayed tack adhesive composition of the present invention, an aqueous dispersion of the above-mentioned solid plasticizer such as a benzoic acid triester or hindered phenol ester compound and an acrylic resin having a glass transition temperature of 10 ° C. to 40 ° C. And a rosin ester aqueous dispersion, and the weight ratio of the solid content is preferably 55 to 70:20 to 30:10 to 20.

Another configuration of the present invention is characterized in that the pressure-sensitive adhesive composition is a label provided on a label substrate. As the label substrate, there are a plastic film and paper, but paper is preferably used.

Further, a small amount of a solid emulsifier may be added.
Usually, among fatty acid soaps and alkylphenylalkylene oxides as emulsifiers, those solid at room temperature are preferred in order to prevent blocking of the pressure-sensitive adhesive. Further, an antifoaming agent, a lubricant, a coloring agent, and a filler may be blended as long as the object is not impaired. If the coating amount of the delayed tack type adhesive on the paper base material is small, the initial adhesion to the adherend is insufficient, and if it is too large, it is difficult to peel off after immersion in water. To 25 g / m2, preferably 8 to 18 g / m2.
Is preferred. For the coating, a general-purpose coating machine such as a gravure coater, a roll coater, a lip coater, and a bar coater can be used.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the scope of the present invention is not limited at all by the following examples. In the examples, parts are parts by weight,%
Means weight%.

Example 1 55 parts of particulate trimethylolpropane benzoate (melting point: 85 ° C.), 40 parts of ion-exchanged water, particulate acrylic ester-acrylic acid copolymer resin (methyl methacrylate / butyl acrylate acrylic acid = 70) / 20/10, molecular weight 15000) and 28 parts of 28% aqueous ammonia were put into a ball mill and kneaded for a predetermined time until the dispersed particles became 2 μm or less. 60 parts of the obtained water dispersion, an acrylic emulsion (styrene /
Acrylic ester / acrylic acid = 12/85/3) 30
Part, rosin emulsion (Superester E-73
0: Arakawa Chemical Co., Ltd.) (10 parts) was prepared to prepare an aqueous pressure-sensitive adhesive dispersion (solid content: 55%). A predetermined amount of the obtained water-based pressure-sensitive adhesive dispersion was weighed to evaluate the foaming property, and then the water-based pressure-sensitive adhesive dispersion was directly applied onto one-sided art paper so that the coating amount was 20 g / m2. And dried at 40 ° C. for 2 minutes. In this state, no tackiness could be confirmed. Table 1 shows the results of evaluation of adhesion and blocking properties of the coated product. Further, the coated product was heated at 120 ° C. for 1 minute to develop adhesiveness, and then bonded to a glass plate to measure the initial adhesive strength. Table 1 shows the results of measuring the adhesive strength after storage at 40 ° C. for one month.

[Example 2] In Example 1, a powdery and granular acrylic resin-acrylic acid copolymer resin (methyl methacrylate / butyl acrylate acrylic acid = 70 /
20/10, molecular weight 15000) was prepared in the same manner as in Example 1 except that 8 parts were blended instead of 4 parts, and the foaming property was evaluated.
After drying, the results of evaluation of the coated product are shown in Table 1.

Example 3 In Example 1, a powdery acrylic ester-acrylic acid copolymer resin (methyl methacrylate / butyl acrylate acrylic acid = 70/20 /
10, molecular weight 15000) Instead of 4 parts, a granular styrene-maleic acid resin (styrene / maleic acid = 3/1,
A molecular weight of 3000) was prepared in the same manner as in Example 1, except that the same amount was blended. After evaluating the foaming property, the composition was directly coated on one-sided art paper, dried, and the coated product was evaluated. Is shown in Table 1.

Example 4 The same procedure as in Example 1 was carried out except that the powdery trimethylolpropane benzoate (melting point 85 ° C.) 5
Instead of 5 parts, powdery triethylene glycol bis [3
Example 1 except that-(3-t-butyl-4-hydroxy-5-methylphenyl) propionate] was mixed in the same amount.
After preparing an adhesive in the same manner as in Example 1 and evaluating the foaming property, the composition was directly applied on one-sided art paper, dried, and the coated product was evaluated. The results are shown in Table 1.

Comparative Example 1 In Example 1, a powdery acrylic ester-acrylic acid copolymer resin (methyl methacrylate / butyl acrylate acrylic acid = 70/20 /
In order to disperse a solid plasticizer in a ball mill in the same manner as in Example 1 except that 2 parts of nonylphenylalkylene ether (Neugen EA-120: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of 4 parts of (10, molecular weight 15,000). However, the following evaluation was unavoidably stopped because the solid plasticizer aqueous dispersion was not obtained due to the aggregation state.

[Comparative Example 2] In Example 1, a particulate acrylic ester-acrylic acid copolymer resin (methyl methacrylate / butyl acrylate acrylic acid = 70/20 /
10, molecular weight 15000) An adhesive was prepared in the same manner as in Example 1 except that 4 parts of dioctylsulfosuccinate sodium (Carabone DA-72: manufactured by Sanyo Chemical Co., Ltd.) was added instead of 4 parts, and the foaming property was evaluated. After the evaluation, the coated product was directly applied on one-sided art paper, dried, and the coated product was evaluated. The results are shown in Table 1.

The foaming property for evaluating the coating property of the aqueous dispersion of the delayed tack type pressure-sensitive adhesive in the examples and comparative examples, the adhesive strength for evaluating the adhesive property, and the storage stability of the coated article were measured. The blocking property for evaluation was evaluated by the following method.

(Foaming test of aqueous dispersion) 100 g of a delayed tack-type aqueous adhesive dispersion was weighed into a 250 ml glass mayonnaise bottle, the liquid level was measured, and then a turbo mixer (manufactured by Tokushu Kikai Co., Ltd.) 3) at 8000 rpm
After stirring for one minute, the liquid level was measured to compare the degree of foaming. ：: The liquid surface height after stirring of the aqueous dispersion was less than 20% increase Δ: The liquid surface height after stirring of the aqueous dispersion increased by 20% or more and 5
Less than 0% increase ×: The liquid level after stirring of the aqueous dispersion increased by 50% or more

(Adhesive strength test) After the adhesive property was developed by heating, the adhesive-coated material was immediately attached to a float glass plate, and the adhesive strength was measured by 180-degree peeling according to JIS K-6848. The judgment was made based on the standard. However, the glued portion was 100 mm. ：: Adhesive strength is 4 N / 15 mm or more and is sufficiently adhered to the bottle △: Adhesive strength is 1 N / 15 mm or more and less than 4 N / 15 mm and does not peel off spontaneously but can be peeled off by hand ×: Adhesion Easy to peel naturally with strength less than 1N / 15mm

(Blocking property) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive coated product was superimposed on the printed layer on the back surface, applied under a load of 0.1 mPa, stored at 50 ° C. for 5 hours, and peeled off. . ：: No peeling resistance. Δ: There is a slight noise when peeling. X: The paper fiber is pulled at the time of peeling.

[0033]

[Table 1]

However, P in Table 1 indicates paper breakage.

[0035]

According to the present invention, an aqueous dispersant of a delayed tack type adhesive can be obtained without using an emulsifier which has been used as an aqueous dispersant of a conventional solid plasticizer for a heat sensitive delayed tack type adhesive. By doing so, it is possible to coat well on the base material with less foaming by a coating machine, and to have excellent blocking resistance during storage of the coated product, excellent adhesiveness, and long adhesiveness. A delayed tack adhesive composition that can be maintained for a long period of time can be obtained. The industrial significance of the fact that the heat-sensitive delayed-tack type pressure-sensitive adhesive and label of the present invention can provide an environmentally-friendly label that does not require a release paper, and can pursue safety and economic benefits have been realized. , Is a great deal.

Claims (6)

[Claims] 1. An aqueous dispersion-type delayed tack adhesive composition comprising a thermoplastic resin, a tackifier resin and a solid plasticizer, comprising a carboxylic acid-containing copolymer as an aqueous dispersant for the solid plasticizer. A delayed tack-type pressure-sensitive adhesive composition, characterized in that: 2. The method according to claim 1, wherein the carboxylic acid-containing copolymer is styrene-
The delayed tack type pressure-sensitive adhesive composition according to claim 1, which is a maleic acid resin and / or an acrylic ester-acrylic acid resin. 3. The delayed tack-type pressure-sensitive adhesive composition according to claim 1, wherein the solid plasticizer is a benzoate compound. 4. The delayed tack-type pressure-sensitive adhesive composition according to claim 1, wherein the solid plasticizer is a hindered phenol ester compound. 5. The thermoplastic resin according to claim 1, which is an aqueous dispersion of one or more resins selected from butadiene copolymers, vinyl acetate copolymers and acrylic copolymers that are not tacky at room temperature or lower. 5. The delayed tack-type pressure-sensitive adhesive composition according to any one of 4. 6. A delay, wherein a delayed tack-type pressure-sensitive adhesive composition layer containing a thermoplastic resin, a tackifier resin, a solid plasticizer and a carboxylic acid-containing copolymer is provided on a label substrate. Tack type adhesive label.