JPH07133473A - Tackifier resin emulsion and water-based adhesive composition - Google Patents

Abstract

PURPOSE:To provide a tackifier resin useful for the production of water-based adhesive compositions excellent in adhesion and heat resistance and stable against high mechanical shear forces caused by gear pumps, roll coaters, etc., by emulsifying a tackifier resin in the presence of an emulsifier, etc. CONSTITUTION:(A) 100 pts.wt. of one kind or more of tackifier resins selected from a rosin (derivative), a petroleum resin, and a terpene resin, (B) an emulsifier such as a sulfonated alpha-olefin preferably in an amount of 1-5 pts.wt., and (C) one kind or more of protective colloids selected from a water-soluble casein salt, gelatin, polyacrylic acid, PVA (derivative), cellulose (derivative) preferably in an amount of 1-5 pts.wt., are compounded with each other and emulsified to provide the objective tackifier resin emulsion. The emulsion is compounded with an acrylic polymer emulsion and/or a latex for adhesives to provide a water-based adhesive composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to tackifier resin emulsions and aqueous pressure-sensitive adhesive compositions. More specifically, it relates to a tackifier resin emulsion capable of providing an aqueous pressure-sensitive adhesive composition having excellent mechanical stability.

[0002]

BACKGROUND OF THE INVENTION Adhesives are applied to papers, plastic films, etc., and are applied to tapes, sheets, labels, etc. Generally, they are applied to a base resin such as an acrylic polymer or the like, such as tacks. Tackifier resins have been added and used to impart properties. In addition, as the pressure-sensitive adhesive, a solvent type has been generally used in the past, but in recent years, an aqueous emulsion has various advantages such as no air pollution, excellent safety and health, and suitability for resource saving. It tends to be converted to mold adhesive.

As the applications of such water-based emulsion type adhesives expand, the required performance becomes higher, and one of the required performances is the stability of the emulsion, especially the stability against mechanical shear. Came to be. Here, the stability against mechanical shear refers to the stability against mechanical shear added in conventionally known gear pumps, roll coating machines, etc., and the spray coating that has been increasing in coating systems in recent years. It refers to the stability against mechanical shear that is added at the time of work.If the stability against such mechanical shear is inferior, aggregates occur in the emulsion, reducing the commercial value of tapes, sheets, labels, etc. There was a problem of causing it.

In order to improve the stability against such mechanical shear, a method of adjusting the type or amount of an emulsifier used in a base resin such as an acrylic polymer emulsion or a tackifier resin emulsion is studied. However, it has not been sufficiently improved. Further, a method of adding a water-soluble polymer such as polyacrylic acid to a base resin and a tackifier resin emulsion has been proposed, but an aqueous emulsion pressure-sensitive adhesive with good stability against mechanical shear is still obtained. Not not.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an emulsion type water-based pressure-sensitive adhesive composition having good stability against mechanical shear.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors blended a base resin with a tackifier resin emulsion obtained by a specific production method. As a result, they have found that an aqueous pressure-sensitive adhesive composition having extremely good stability against mechanical shear can be obtained, and completed the present invention.

That is, the present invention relates to a tackifier resin emulsion obtained by emulsifying a tackifier resin in the presence of an emulsifier and a protective colloid. Further, the present invention is
The present invention relates to an aqueous pressure-sensitive adhesive composition containing an acrylic polymer emulsion and / or a latex for pressure-sensitive adhesive and the tackifier resin emulsion.

As the tackifier resin used in the present invention, various known resins can be used. Examples include rosins, rosin derivatives, petroleum-based resins, and terpene-based resins, and one of these can be used alone or two or more can be used as a mixture.

The rosin refers to a raw rosin of gum rosin, wood rosin or tall oil rosin, a stabilized rosin obtained by disproportionating or hydrogenating the raw rosin, a polymerized rosin and the like.

Examples of rosin derivatives include rosin esters and rosin phenols. As the rosin ester, a rosin ester obtained by subjecting the rosin and a polyhydric alcohol to an esterification reaction, partially fumarized or maleated from a raw material rosin, and then partially maleated or partially fumarized by esterification Polyhydric alcohol ester of rosin, polymaleic alcohol ester of partially maleated or partially fumarized disproportionated rosin obtained by partially fumarizing or maleating raw material rosin, and then disproportionating Say. Further, the rosin phenols are those obtained by adding phenols to rosins and thermally polymerizing them, or subsequently esterifying them.

The polyhydric alcohol used for the esterification is not particularly limited, and diethylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,
Various known compounds such as 2,4-butanetriol and pentaerythritol can be exemplified.

[0012] The petroleum resins are C5 petroleum resins,
Examples thereof include C9 petroleum resin, C5-C9 copolymer petroleum resin, pure monomer resin, dicyclopentadiene petroleum resin, and hydrides thereof.

As the terpene resin, an α-pinene resin, a β-pinene resin, or an aromatic-modified terpene resin obtained by copolymerizing a terpene such as α-pinene and β-pinene with an aromatic monomer such as styrene. Resin can be illustrated.

The softening point of these tackifier resins is not particularly limited, and those having a high softening point of 200 ° C. or lower and liquid can be appropriately selected and used according to various uses.

In the present invention, the tackifier resin is emulsified in the presence of an emulsifier and a protective colloid to produce a tackifier resin emulsion.

Various known emulsifiers can be used. For example, α-olefin sulfonates, alkyl sulphates, alkyl phenyl sulphates, polyoxyethylene alkyl phenyl ether sulphates, sulfosuccinic acid half ester salts of polyoxyethylene aralkyl phenyl ethers, anionic emulsifiers such as rosin soaps, polyoxyethylene alkyls. Nonionic emulsifiers such as phenyl ether can be used, and one of these can be used alone or two or more can be used as a mixture. The amount of the emulsifier used is not particularly limited, but is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight in terms of solid content, relative to 100 parts by weight of the tackifier resin. If it exceeds 10 parts by weight, the water resistance of the resulting aqueous pressure-sensitive adhesive is lowered, and if it is less than 1 part by weight, the stability of the resin emulsion during emulsification becomes poor.

As the protective colloid, various water-soluble polymers can be used. Examples thereof include a water-soluble salt of casein, gelatin, polyacrylic acid, polyvinyl alcohol, a polyvinyl alcohol derivative, a water-soluble salt of cellulose, a cellulose derivative and the like, and one of these may be used alone or two or more of them may be used as a mixture. . The water-soluble salt of casein is obtained by solubilizing casein, which is a natural phosphoprotein such as milk and soybean, in an aqueous solution of a basic substance such as sodium hydroxide, potassium hydroxide, ammonia, and organic amines. Say something. Polyvinyl alcohol refers to one having a saponification degree of 70% or more and a viscosity of 70 cps (20 ° C.) or less when made into a 4% aqueous solution, and a polyvinyl alcohol derivative is various modified polyvinyl such as acetylation-modified or silicon-modified. Refers to alcohol. The water-soluble salt of cellulose is obtained by solubilizing cellulose in an aqueous solution of the basic substance, and the cellulose derivative is cellulose ether or the like. Among these protective colloids, the water-soluble salt of casein is preferable, and the ammonium salt of casein is particularly preferable.

The amount of the protective colloid used is not particularly limited, but is usually about 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the tackifier resin. It is a department. If it exceeds 10 parts by weight, the viscosity of the tackifier resin emulsion obtained by emulsification increases and handling becomes difficult. If it is less than 0.1 part by weight, the tackifier resin emulsion obtained by emulsification. It is not possible to sufficiently improve the stability of the water-based pressure-sensitive adhesive composition prepared by blending with the mechanical shear.

In the production of the tackifier resin emulsion of the present invention, a method similar to the conventionally known emulsification method can be employed except that a protective colloid is used together with an emulsifier. Even if a protective colloid is added after the production of the emulsion, the stability against mechanical shear cannot be sufficiently improved.

Examples of the emulsification method include a general high-pressure emulsification method and a reverse emulsification method. Specifically, the tackifier resin is dissolved in a solvent such as benzene and toluene, and then the emulsifier, a protective colloid and soft water are added, and the solvent is removed under reduced pressure after emulsification using a high pressure emulsifier. A small amount of solvent such as benzene and toluene is mixed with the tackifier resin, and then an emulsifier and a protective colloid are kneaded, and then hot water is gradually added to gradually invert the emulsion to obtain an emulsion and then the solvent is depressurized. The method of removing or using as it is, the method of raising the temperature above the softening point of the resin in the autoclave, kneading the emulsifier and the protective colloid, gradually adding hot water, and then phase inversion emulsifying to emulsify. I can give you.

The tackifier resin emulsion of the present invention thus obtained is blended with an acrylic polymer emulsion as a base resin and / or a latex for pressure-sensitive adhesive to give various water-based pressure-sensitive adhesive compositions adhesive properties such as tack. It imparts and improves the mechanical shear of the aqueous pressure-sensitive adhesive composition.

As the acrylic polymer emulsion, those generally used for various acrylic pressure-sensitive adhesives can be used. Acrylic acid ester and / or methacrylic acid ester are batch-charged polymerization method, successive addition polymerization method of monomers, and emulsification. It can be easily produced by a known emulsion polymerization method such as a sequential monomer addition polymerization method and a seed polymerization method.

Examples of the acrylic acid ester and methacrylic acid ester (hereinafter referred to as (meth) acrylic acid ester) used include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth)
Acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester, (meth) acrylic acid glycidyl ester, (meth) acrylic acid 2-hydroxyethyl ester and the like can be mentioned, and these can be used alone or in admixture of two or more. To use. Further, in order to impart stability to the obtained emulsion, a small amount of (meth) acrylic acid may be used instead of the (meth) acrylic acid ester. Furthermore, if desired, a copolymerizable monomer such as vinyl acetate or styrene may be used in combination as long as the adhesive property of the (meth) acrylic acid ester polymer is not impaired. The glass transition temperature of the polymer containing these (meth) acrylic acid esters as a main component is usually about -70 to 0 ° C, preferably -60 to -10 ° C. If it exceeds 0 ° C, the tack is remarkably lowered, which is not preferable. The emulsifier used for the acrylic polymer emulsion may be an anionic emulsifier, partially saponified polyvinyl alcohol, or the like, and the amount thereof is 0.1 to 100 parts by weight of the polymer.
It is about 5 parts by weight, preferably 0.5 to 3 parts by weight.

The ratio of the acrylic polymer emulsion to the tackifier resin emulsion used is usually about 5 to 30 parts by weight of the tackifier resin emulsion with respect to 100 parts by weight of the acrylic polymer emulsion (solid content conversion). It is preferable to use solid content conversion). If the tackifier resin emulsion is less than 5 parts by weight, the adhesive force tends to decrease, and if it exceeds 50 parts by weight, the cohesive force tends to decrease, which is not suitable in any case.

Examples of the adhesive latex include natural rubber latex, styrene-butadiene copolymer latex and chloroprene latex. As the natural rubber latex, a known one used in an aqueous pressure-sensitive adhesive composition can be used, and it may be either depolymerized or non-depolymerized. As the styrene-butadiene copolymer latex and chloroprene latex, those commercially available for pressure-sensitive adhesives can be usually used. The styrene-butadiene copolymer latex and chloroprene latex may be carboxy-modified.

The ratio of the latex for tackifier to the tackifier resin emulsion is usually about 5 to 150 parts by weight (solid content) with respect to 100 parts by weight of the latex for tackiness (calculated as solid content). (Converted) is recommended. If the tackifier resin emulsion is less than 5 parts by weight, the adhesive strength tends to decrease, and also 150
If the amount is more than parts by weight, the cohesive force tends to decrease, which is not suitable in any case.

In the aqueous pressure-sensitive adhesive composition of the present invention, an acrylic polymer emulsion as a base resin and a latex for pressure-sensitive adhesive may be used in combination, and if necessary, a defoaming agent, a thickener, a filler and an oxidizer. It is also possible to use an inhibitor, a water-proofing agent, a film-forming aid and the like.

[0028]

According to the tackifier resin emulsion obtained by the present invention, it is possible to provide an aqueous pressure-sensitive adhesive composition having good stability against mechanical high shear during gear pump, roll coating, spray coating, etc. Workability during coating can be greatly improved. Further, the obtained water-based pressure-sensitive adhesive composition has excellent adhesiveness and the like similar to the conventional water-based pressure-sensitive adhesive composition which does not use a protective colloid, and is also excellent in heat resistance.

[0029]

EXAMPLES The present invention will be described in detail below with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. In each example, parts and% are based on weight.

Production Example A four-necked flask equipped with a stirrer, a cooling tube, a dropping funnel and a nitrogen introducing tube was placed under a nitrogen gas stream at 70 ° C. and water 4 times.
3.40 parts and anionic emulsifier (“Hitenol S”, solid content 50%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.92
Parts were dissolved. Further, (1) butyl acrylate 45.
10 parts and acrylic acid 1.40 parts, (2) catalyst (potassium persulfate) 0.24 parts, pH adjuster (baking soda) 0.1
1 part and 8.83 parts of water were added dropwise from separate dropping funnels in an amount of 1/10 and preliminarily reacted for 30 minutes under a nitrogen gas stream at 70 ° C., and then (1) and (2) The amount of 9/10 was added dropwise over 2 hours for polymerization. After the total amount of (1) and (2) was dropped, 70
After completion of the reaction at 1 ° C. for 1 hour and cooling to room temperature, the mixture was taken out while performing 100-mesh wire mesh filtration and solid content was 45.
A 7% acrylic polymer emulsion was obtained.

Example 1 100 parts of pentaerythritol ester of polymerized rosin having a softening point of 160 ° C. was added to 60 parts of toluene at 100 ° C. to about 1 part.
After melting for a period of time, it was cooled to 80 ° C. Next, 3 parts of anionic emulsifier (sodium dodecylbenzene sulfonate) in terms of solid content, 0.3 part of 28% ammonia water in advance,
An aqueous ammonia solution of casein prepared by heating and dissolving 2 parts of casein and 10 parts of water, and 160 parts of water were added, and preliminarily emulsified by strongly stirring at 75 ° C. for 1 hour. Further, the obtained preliminary emulsion was subjected to high pressure emulsification at a pressure of 300 kg / cm ² by a high pressure emulsifier (manton gaurin company) to obtain an emulsion. Next, 200 parts of the emulsion was charged into a vacuum distillation apparatus and vacuum distillation was carried out at 50 ° C. and 100 mmHg for 8 hours to obtain an emulsion of pentaerythritol ester of polymerized rosin having a solid content of 50%.

20 parts of the emulsion of the polymerized rosin pentaerythritol ester thus obtained (in terms of solid content) and 80 parts of the acrylic polymer emulsion obtained in the above production example (in terms of solid content) were mixed to prepare an aqueous solution. An adhesive composition was obtained.

Example 2 The same as Example 1 except that pentaerythritol ester of partially fumarized disproportionated rosin (softening point 125 ° C.) was used in place of pentaerythritol ester of polymerized rosin. An operation was performed to obtain an emulsion of pentaerythritol ester of partially fumarized disproportionated rosin. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Example 3 The same operation as in Example 1 was carried out except that glycerin ester of disproportionated rosin (softening point 100 ° C.) was used in place of pentaerythritol ester of polymerized rosin in Example 1. An emulsion of the glycerol ester of leveled rosin was obtained. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Example 4 Polymerized rosin was prepared in the same manner as in Example 1 except that 2 parts of polyvinyl alcohol was dissolved in 10 parts of water instead of the ammonia solution of casein. To obtain an emulsion of pentaerythritol ester. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the ammonia aqueous solution of casein was not added to obtain an emulsion of a polymerized rosin pentaerythritol ester. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Comparative Example 2 An emulsion of pentaerythritol ester of partially fumarized disproportionated rosin was obtained in the same manner as in Example 2 except that the aqueous ammonia solution of casein was not added. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Comparative Example 3 The same operation as in Example 3 was carried out except that the ammonia aqueous solution of casein was not added to obtain an emulsion of glycerin ester of disproportionated rosin. Further, an aqueous pressure-sensitive adhesive composition was obtained with the same composition as in Example 1.

Comparative Example 4 An emulsion of a pentaerythritol ester of polymerized rosin was obtained in the same manner as in Example 1, except that the aqueous ammonia solution of casein was not added. Also, in the case of preparing the aqueous pressure-sensitive adhesive composition in Example 1, the same as in Example 1 except that the aqueous ammonia solution of casein used in the preparation of the emulsion of the polymerized rosin pentaerythritol ester in Example 1 was added. An aqueous pressure-sensitive adhesive composition was obtained by blending.

(Stability to mechanical shear) The aqueous pressure-sensitive adhesive compositions prepared in Examples and Comparative Examples were further adjusted to pH 8 and non-volatile content 30% with 28% ammonia water, and then subjected to a Marlon test. , Aggregate generation rate (%)
= (Aggregate / initial solid content) × 100 was calculated. Conditions of the Marlon test are load: 10 kg, rotation speed: 1000 r
pm, share time: 10 minutes. The results are shown in Table 1.

(Heat Resistance) The water-based pressure-sensitive adhesive compositions prepared in Examples and Comparative Examples were coated on a PET film and dried to prepare a pressure-sensitive adhesive tape having a film thickness of 30 μm.
A creep test was conducted by the method according to C-7 to evaluate heat resistance (holding power). Evaluation is temperature 70 ℃, load 1
It was represented by the time when the weight fell under the condition of kg. The results are shown in Table 1.

[0042]

[Table 1]

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Claims (6)

[Claims] 1. A tackifier resin emulsion obtained by emulsifying a tackifier resin in the presence of an emulsifier and a protective colloid. 2. The tackifier resin emulsion according to claim 1, wherein the tackifier resin is at least one selected from rosins, rosin derivatives, petroleum resins and terpene resins. 3. The protective colloid is a water-soluble salt of casein,
The tackifier resin emulsion according to claim 1, which is at least one selected from gelatin, polyacrylic acid, polyvinyl alcohol, polyvinyl alcohol derivatives, cellulose, and cellulose derivatives. 4. An acrylic polymer emulsion and / or
Alternatively, an aqueous pressure-sensitive adhesive composition comprising a latex for pressure-sensitive adhesive, and the tackifier resin emulsion according to claim 1, 2 or 3. 5. The tackifier resin emulsion according to claim 1, 5 or 30 parts by weight (solid content conversion) is used for 100 parts by weight of acrylic emulsion (solid content conversion). 4. The aqueous pressure-sensitive adhesive composition according to 4. 6. The tackifier resin emulsion according to claim 1, 5 to 150 parts by weight (solid content conversion) is used with respect to 100 parts by weight of adhesive latex (solid content conversion). Item 4. The aqueous pressure-sensitive adhesive composition according to item 4.