JP2599589B2 - Aqueous adhesive composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel aqueous pressure-sensitive adhesive composition excellent in adhesion to polyolefin and transparency.

2. Related Art and Problems Thereof Usually, an adhesive is applied to paper, plastic film, and the like, and is applied to tapes, sheets, labels, and the like. Aqueous emulsion-type pressure-sensitive adhesives have various advantages compared to organic solvent-type pressure-sensitive adhesives, such as no air pollution, excellent safety and health, and suitability for resource saving. From water to an aqueous emulsion type. Thus, as the application of the aqueous emulsion type adhesive expands, the required performance also becomes higher, and one of such required performance is polypropylene,
Adhesion of a polyolefin base material such as polyethylene to a curved surface, that is, anti-flagging property, is regarded as important.
Here, the anti-flagging property means that a tape or a label does not peel off over time. Applications requiring such performance include, for example, high-quality beautiful labels for food and cosmetics, quality indication labels for electric appliances, etc., supermarket price labels, office computer labels, adhesive sheets, adhesive tapes, and the like. . further,
When used for a transparent film, transparency of the pressure-sensitive adhesive sheet is required in addition to the problem of anti-flagging.

Conventionally, it has been carried out to improve the adhesion to a polyolefin substrate by blending an emulsion of a tackifier resin such as a glycerin ester of disproportionated rosin into an acrylic polymer emulsion, but in this case, the adhesion is improved. Some improvements can be made, but the flagging problem has not yet been improved. Further, even if the problem of the flagging property can be improved to some extent, the adhesive sheet may become turbid and cannot be used for applications requiring transparency such as a transparent film. That is, a water-based emulsion adhesive satisfying the required performance has not yet been obtained.

Means for Solving the Problems In view of the above problems of the aqueous pressure-sensitive adhesive composition obtained by blending the tackifier resin emulsion with the existing acrylic emulsion, the present inventors have proposed an aqueous pressure-sensitive adhesive composition polyolefin. In the case of using a specific high softening point tackifier resin emulsion as a tackifier resin, as a result of intensive studies to improve the adhesiveness of the substrate, particularly its curved surface, that is, the problem of flagging resistance, and to improve the transparency of the pressure-sensitive adhesive sheet. It has been found that not only adhesiveness to a polyolefin plane but also adhesiveness to a polyolefin curved surface and transparency of a pressure-sensitive adhesive sheet can be imparted at the same time, and the present invention has been completed.

That is, the present invention provides at least one selected from (1) an acrylic polymer emulsion containing acrylic acid ester and / or methacrylic acid ester as a main component and (2) a rosin-modified phenol resin and a polyhydric alcohol ester of polymerized rosin. A resin emulsion having a softening point of 110 to 150 ° C., which is a kind of tackifier resin.

As the acrylic polymer emulsion used in the present invention, emulsions generally used for various acrylic pressure-sensitive adhesives can be used. The acrylic polymer emulsion is generally used in an active charge polymerization method, a monomer sequential addition polymerization method, a monomer sequential addition polymerization method, an emulsion monomer sequential addition polymerization method, and a seed polymerization method in which an acrylic acid ester and / or a methacrylic acid ester are usually used as an emulsion polymerization method. It can be easily manufactured by attaching.

Here, acrylates and methacrylates used (hereinafter referred to as (meth) acrylates)
As monomers, (meth) acrylic acid methyl ester,
Ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Further, in order to impart stability to the obtained resin emulsion, a small amount of (meth) acrylic acid may be used instead of part of the (meth) acrylate. If desired, a copolymerizable monomer such as vinyl acetate and styrene can be used in combination to the extent that the adhesive properties of the (meth) acrylate styrene polymer are not impaired. The glass transition temperature of the polymer mainly composed of these acrylates and methacrylates is -70 to 0.
° C, preferably -60 to -10 ° C. If the temperature exceeds 0 ° C., the tack is remarkably reduced, which is not preferable. Emulsifiers used for acrylic emulsions include anionic emulsifiers,
Partially saponified polyvinyl alcohol or the like can be used, and its use amount is about 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the polymer.

On the other hand, as the high softening point tackifier resin used in the high softening point tackifier resin emulsion as one component in the composition of the present invention, at least one kind of a rosin-modified phenol resin and a polyhydric alcohol ester of a polymerized rosin is used. There must be. That is, the object of the present invention is achieved by using the above tackifier resin.

Rosin modified phenolic resin, after the addition reaction of 75 to 150 parts by weight of phenol to at least 100 parts by weight of at least one of tall oil rosin, utsdrozine and gum rosin in the presence of an acidic catalyst such as protonic acid and Lewis acid , Calcium hydroxide or the like, neutralized, filtered, and thermally polymerized at 250 to 300 ° C. The polyhydric alcohol ester of the polymerized rosin is subjected to an esterification reaction of 8 to 12 parts by weight of a polyhydric alcohol such as glycerin or pentaerythritol with respect to 100 parts by weight of the polymerized rosin in the presence or absence of an acid catalyst such as methanesulfonic acid. It is obtained by doing. The softening point of the tackifier resin thus obtained is preferably 110 to 150 ° C.,
Particularly, 110 to 130 ° C is preferable. When the softening point is less than 110 ° C, the anti-flagging property is poor. If the temperature exceeds 150 ° C., the tack is remarkably reduced, and the compatibility is poor and turbidity occurs.

Examples of the emulsifier used for emulsifying the above resin include α-olefin sulfonate, alkyl sulfate, alkyl phenyl sulfate, polyoxyethylene alkyl phenyl ether sulfate, and polyoxyethylene aralkyl phenyl ether sulfosuccinic acid. Examples include anionic emulsifiers such as half ester salts and rosin soaps, and nonionics such as nonions such as polyoxyethylene alkyl phenyl ether. The amount of the emulsifier is not particularly limited, but is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight, as solids, relative to 100 parts by weight of the resin. When the amount exceeds 10 parts by weight, the water resistance of the obtained pressure-sensitive adhesive decreases. If the amount is less than 1 part by weight, the stability of the resin emulsion at the time of emulsification becomes poor.

The high softening point tackifier resin emulsion is obtained by dissolving the high softening point tackifier resin in a solvent such as benzene and toluene, adding the emulsifier and soft water, emulsifying the mixture using a high-pressure emulsifier, and then removing the solvent under reduced pressure. Or a small amount of a solvent such as benzene or toluene is mixed so that the softening point of the resin is about 90 ° C or less, then the emulsifier is kneaded, and hot water is gradually added. Emulsions are obtained by phase emulsification, then the solvent is removed under reduced pressure or used as is, or the temperature is raised to above the softening point of the resin in an autoclave, the emulsifier is kneaded, and hot water is gradually added. It can be obtained by a method of emulsifying by phase emulsification, etc., and any method may be used.

The aqueous pressure-sensitive adhesive composition of the present invention is used by blending a high softening point tackifier resin emulsion in the range of about 5 to 30 parts by weight based on 100 parts by weight of the solid content of the acrylic emulsion. Is preferred. Particularly preferred is 7
~ 15 parts by weight. If the addition amount of the high softening point tackifier resin emulsion is less than 5 parts by weight, it is difficult to impart sufficient adhesion. Is not preferred because the hardness becomes high and the tack decreases.

The aqueous pressure-sensitive adhesive composition of the present invention may optionally contain a small amount of an antifoaming agent, a thickener, a filler, an antioxidant, a water-proofing agent, a film-forming aid, and the like.

Effect of the Invention The water-based pressure-sensitive adhesive composition of the present invention can be used very suitably for various uses in which conventional acrylic pressure-sensitive adhesives have been used. Particularly, a polyolefin base material, particularly in the field where its adhesiveness to a curved surface is required, has an excellent effect, does not cause the phenomenon of flagging, which has been conventionally regarded as a problem, and is excellent in transparency, so that its commercial value is high.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples. In each example, all parts and percentages are by weight unless otherwise specified.

Production example (1) 44.46 parts of water (2) Anionic emulsifier (“HITENOL S”, solid content
0.90 parts (3) Butyl acrylate 43.90 parts Acrylic acid 1.36 parts (4) Catalyst (potassium persulfate) 0.23 parts pH adjuster (heavy sulfuric acid) 0.11 parts Water 9.04 parts Stirrer In a four-necked flask equipped with a cooling tube, a dropping funnel and a nitrogen inlet tube, the above (1) and (2) are dissolved under a nitrogen gas stream at 70 ° C., and then stirred (3) and (4).
And a preliminary reaction was carried out at 70 ° C. for 30 minutes in a nitrogen gas stream, and then 9/10 of (3) and (4) were added dropwise over 2 hours to carry out drop polymerization. Was. After dropping all of (3) and (4), the reaction was completed at 70 ° C. for 1 hour, cooled to room temperature, and then taken out while performing 100 mesh wire mesh filtration to obtain an acrylic emulsion having a solid content of 45.7%.

Example 1 100 parts of a rosin-modified phenol resin having a softening point of 147 ° C. was dissolved in 60 parts of toluene at 100 ° C. for about 1 hour, and then cooled to 80 ° C. to convert an anionic emulsifier (sodium dodecylbenzenesulfonate) into a solid content. Add 3 parts and water 160 parts with 7
Preliminary emulsification was carried out by vigorous stirring at 5 ° C. for 1 hour, and the preliminarily emulsified product was emulsified at a pressure of 300 kg / cm ² with a high pressure emulsifier (manufactured by Manton Gaulin) to obtain an emulsified product. Next, 200 parts of the emulsion was charged into a vacuum distillation apparatus at 50 ° C and 100 ° C.
Vacuum distillation was performed for 6 hours under the condition of mmHg to obtain a rosin-modified phenol resin emulsion having a solid content of 50%. 10 parts (in terms of solid content) of the rosin-modified phenolic resin emulsion thus obtained and 90 parts (in terms of solid content) of the acrylic emulsion obtained in the above Production Example were mixed, and further, as an acrylic thickener, Primal ASE-60 "(manufactured by Nippon Acrylic Co., Ltd.) was thickened with aqueous ammonia to which 0.5 part (in terms of solid content) was added to obtain an aqueous pressure-sensitive adhesive composition.

Example 2 In Example 1, a pentaerythritol ester of a polymerized rosin (softening point) was used in place of the rosin-modified phenol resin.
Except that 121 ° C. was used, the same operation as in Example 1 was carried out to obtain an emulsion, and an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

Comparative Example 1 In Example 1, an aliphatic petroleum resin (softening point 100 ° C., “Quinton A-1”) was used in place of the rosin-modified phenol resin.
"00", manufactured by Nippon Zeon Co., Ltd.), and an emulsion was obtained in exactly the same manner as in Example 1. Further, an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

Comparative Example 2 In Example 1, an aromatic petroleum resin (softening point: 120 ° C., “Petrogin 12” was used instead of the rosin-modified phenol resin.
0 ", manufactured by Mitsui Petrochemical Co., Ltd.), and an emulsion was obtained in exactly the same manner as in Example 1. Further, an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

Comparative Example 3 In Example 1, glycerol ester of disproportionated rosin (softening point 100 ° C., replaced with rosin-modified phenol resin)
"Super Ester A-100", Arakawa Chemical Industry Co., Ltd.
The procedure of Example 1 was repeated except that the above-mentioned procedure was used to obtain an emulsion. Further, an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

Comparative Example 4 A glycerin ester of maleated rosin (softening point 150) was used in Example 1 in place of the rosin-modified phenol resin.
C., "Marquid No. 5" (Arakawa Chemical Industry Co., Ltd.) except that the same operation as in Example 1 was performed to obtain an emulsion. Further, an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

Comparative Example 5 In Example 1, the rosin-modified phenol resin was replaced with a polyterpene resin (softening point 115 ° C., “YX-Resin Px # 1”).
Except for using "150" Yasuhara Yushi Kagaku Kogyo Co., Ltd.), the same operation as in Example 1 was performed to obtain an emulsion. Further, an aqueous pressure-sensitive adhesive composition was obtained by the same blending.

The aqueous pressure-sensitive adhesive composition prepared in each of Examples and Comparative Examples was applied to a polyester film having a thickness of 40 μm so that the adhesive thickness after drying was 30 μm, and then dried at 105 ° C. in a circulating drier.
Table 1 shows the results of various tests conducted by preparing an adhesive sheet after drying for minutes.

 Various tests are performed according to the following methods.

1. Adhesive force: Adhesive force (g / cm) was measured by 180 ° peeling at a measuring temperature of 20 ° C. and a tensile speed of 300 mm / min. The adherend is a stainless plate (SS), a polyethylene plate (PE) and a polypropylene plate (PP).

2.Tack: According to the J.Dow method described in JIS Z 0237
The measurement was performed at an inclination of 30 ° and a measurement temperature of 20 ° C. The numerical values in Table 1 indicate Ball No.

3.Cohesion force: According to JIS C 2107, affixed area 25 × 25mm ² ,
The displacement (mm) after 1 hour at 40 ° C. with respect to the stainless steel plate under a load of 1 kg was measured.

4. Furatsugingu properties: PP retention resistance Furatsugingu resistance after the adhesive sheet adhered to with 30 days of curved 20 × 20mm ² ((number / total number does not cause Furatsugingu of 16 mm) × 10
0%).

5. Turbidity of the sheet: The dried adhesive sheet was visually judged. Those with turbidity were indicated by x, and those without turbidity were indicated by ○.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-84371 (JP, A) JP-A-58-225173 (JP, A)

Claims (2)

(57) [Claims] At least one selected from (1) an acrylic polymer emulsion containing an acrylic ester and / or a methacrylic ester as a main component and (2) a rosin-modified phenol resin and a polyhydric alcohol ester of a polymerized rosin. An aqueous pressure-sensitive adhesive composition comprising: a kind of tackifier resin; and a resin emulsion having a softening point of 110 to 150 ° C. 2. A method according to claim 1, wherein the resin emulsion of the tackifier resin is blended in an amount of 5 to 30 parts by weight (in terms of a fixed amount) with respect to 100 parts by weight of the acrylic polymer emulsion (in terms of solid content). The aqueous pressure-sensitive adhesive composition as described in the above.