JP2002180020A - Emulsion adhesive mass composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that dispersion cannot be avoided even by changing the kind and amount of a thickener in order to avoid the dispersion because dispersion of thickness is caused when an adhesive mass layer is simply thinly coated when the adhesive mass layer is coated to 10 μm thickness, new problems in which an adhesive mass is not locally applied when the solid content of the adhesive mass is reduced to uniformize the thickness and further new problems about leakage of the adhesive mass to the outside of a coating machine because the cohesive strength of the adhesive mass is reduced by lowering of solids. SOLUTION: This emulsion adhesive mass composition is obtained by compounding 0.1-10 pts.wt. of a wetting agent in the emulsion adhesive mass composition comprising 100 pts.wt. of a rubber component of a rubber latex, 30-200 pts.wt. of a tackifier emulsion and 0.1-20 pts.wt. of a thickener expressed in terms of solid weight ratio. The composition is a type capable of thickening its own system when the thickener is dissolved in water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an emulsion-based pressure-sensitive adhesive composition, and more particularly to an emulsion-based pressure-sensitive adhesive composition that can be applied to a small thickness.

[0002]

2. Description of the Related Art Heretofore, an emulsion-based pressure-sensitive adhesive composition diluted with water has a solid content of 50%, and the viscosity and coatability have been adjusted with a thickener. When the adhesive tape is applied to the substrate, it is usually applied to a thickness of 20 μm.

In recent years, there has been a demand for reducing the thickness of the entire pressure-sensitive adhesive tape, and accordingly, the pressure-sensitive adhesive layer has to be reduced. Therefore, it has to be applied to a thickness of 10 μm.

[0004] However, if the coating is simply performed to a thickness of 10 µm, the thickness varies. In particular, the variation in the width direction was large due to the formation of streaks along the longitudinal direction. Even if the type and amount of the thickener were changed to avoid this variation, the variation could not be avoided. In addition, a means for reducing the solid content of the pressure-sensitive adhesive to make the thickness uniform can be considered. However, the viscosity of the pressure-sensitive adhesive is reduced, and a new problem that the pressure-sensitive adhesive is not locally applied occurs.
Further, since the cohesive force of the pressure-sensitive adhesive decreases due to the decrease in the solid content, the conventional comma-direct coating method has a new problem that the pressure-sensitive adhesive leaks out of the coating machine.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an emulsion pressure-sensitive adhesive composition which can be applied with a thickness of about 10 μm.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, 100 parts by weight of a rubber component of a rubber latex, 30 parts by weight of a tackifier emulsion, 200 parts by weight and a thickener 0.1
An emulsion-based pressure-sensitive adhesive composition having a weight-average weight of 0.1 to 20 parts by weight, wherein a wetting agent of 0.1 to 10 parts by weight is blended to increase the viscosity of its own system when the thickener is dissolved in water. As a result, the inventors have found that coating can be performed with a thickness of about 10 μm, and completed the present invention.

In another invention, the solid content of the emulsion-based pressure-sensitive adhesive composition is 20 to 40% and the viscosity is 100%.
By limiting the thickness to 0 to 30,000 cps, it was found that coating can be performed with a thickness of about 10 μm as in the above invention, and the present invention was completed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a wetting agent is blended in order to lower the polarity of the emulsion-based pressure-sensitive adhesive composition. By lowering the polarity, wettability to a film substrate can be improved. As the wetting agent, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant and the like can be used. Incidentally, a cationic surfactant is not preferable because ordinary rubber latex is anionic, and if both are bonded, the pressure-sensitive adhesive composition becomes unstable and aggregates are easily generated, which is not preferable. In the present invention, if the compounding ratio of the wetting agent is too small, the effect of lowering the polarity is not exhibited, and if the compounding ratio is too large, the effect stops at a maximum. Therefore, the solid content ratio is preferably 0.1 to 10 parts by weight.

The rubber latex according to the present invention includes:
Conventionally known natural rubber latex and synthetic rubber latex which can be used for the emulsion-based pressure-sensitive adhesive composition can be employed.
Examples of the natural rubber latex include concentrated raw material natural rubber latex, methyl methacrylate grafted natural rubber latex, synthetic natural rubber latex, styrene grafted natural rubber latex, and organic peroxide prevulcanized natural rubber latex. As the synthetic rubber latex, butadiene-based synthetic latex, modified styrene-butadiene-based synthetic latex, modified acrylonitrile-butadiene-based synthetic latex, modified methacrylbutadiene-based synthetic latex, chloroprene-based synthetic latex and synthetic latex subjected to graft reaction, acrylic ester-based emulsion, Examples include vinyl acetate emulsions.

As the above-mentioned tackifier emulsion, a conventionally known tackifier emulsion which can be used for an emulsion-based pressure-sensitive adhesive composition can be used. Examples of the tackifier emulsion include modified rosin ester-based, polyterpene-based, cumarone-indene-based, petroleum resin-based and phenol-based emulsions. In the present invention, if the compounding ratio of the tackifier emulsion is too small, the pressure-sensitive adhesive composition itself does not exhibit tackiness, and if it is too large, the cohesive force of the pressure-sensitive adhesive composition itself decreases, so 30 to 200 parts by weight in terms of the weight ratio is good.

As the above-mentioned thickener, a type which thickens its own system when the thickener is dissolved in water is preferable, and a type which forms a bridge structure with emulsion particles such as urethane type is preferable. Absent. Examples of the thickening agent of the type that thickens its own system include fiber derivatives, acrylic acid systems, protein systems, mineral substances, vinyl polymer systems, polyacrylamides and polyethylene oxides. Examples of the fiber derivative include sodium salts of carboxylated methylcellulose, methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, and hydroxyethylcellulose. Potassium salt, polyacrylic acid, sodium polyacrylate, ammonium polyacrylate, partially saponified polyacrylate, sodium polyacrylate and the like. Proteins include sodium caseinate, glue, gelatin and soy lecithin, and mineral substances include montmorillonite benite. Examples of the vinyl polymer include a high molecular weight carboxyvinyl polymer and an ammonium salt of the high molecular weight carboxyvinyl polymer, and examples of the polyacrylamide include a polyacrylamide emulsion. Alginate systems include sodium alginate, potassium alginate, ammonium alginate and triethanolamine alginate. In the present invention, the mixing ratio of the thickener is too low, the viscosity of the pressure-sensitive adhesive composition itself remains low, and if it is too high, the thickness becomes too thick and the thickness uniformity after coating is not uniform. The content is preferably 0.1 to 20 parts by weight in terms of solid content weight ratio.

In another invention, the emulsion-based pressure-sensitive adhesive composition has a solid content of 20 to 40% and a viscosity of 1000
The reason why the thickness is limited to ３０30000 cps is that it is possible to apply even a thin film having a thickness of about 10 μm as long as such a condition is satisfied. If the solid content is too low, there will be areas where the adhesive will not be applied on the coated surface when applied to the base material, and if it is too high, the coating surface when coated on the base material will have streaks and uniform thickness If the viscosity is too low, the pressure-sensitive adhesive will leak from the coating machine during application to the substrate, and if the viscosity is too high, the thickness will not be uniform.

When the emulsion pressure-sensitive adhesive composition according to the present invention is used for a pressure-sensitive adhesive tape, it is laminated on one or both sides of a film substrate.

The manufacturing process of the pressure-sensitive adhesive tape will be described.
The adhesive tape is completed by diluting and dispersing the emulsion-based pressure-sensitive adhesive composition having the above-mentioned composition with water on one surface of a film-shaped base material, coating the film, and winding it up. When winding up the completed pressure-sensitive adhesive tape, a release agent may be laminated on the back surface of the base material or a release sheet may be laminated on the pressure-sensitive adhesive as necessary. When applying the pressure-sensitive adhesive tape on both surfaces of the substrate, the pressure-sensitive adhesive may be coated on the back surface. In addition, it is a matter of course that a primer may be laminated between the pressure-sensitive adhesive and the base material, if necessary.

[0015]

EXAMPLES Examples of the present invention will be described below with reference to Table 1.
Will be described in more detail with reference to and comparison with a comparative example. The numerical values of the compositions in Table 1 are parts by weight (weight ratio of solid content), the viscosity of the characteristic value is measured based on JIS K 6838 (adhesive viscosity measurement method), and the coating property is as adhesive tape. The pressure-sensitive adhesive composition thus obtained was visually observed, and those having a variation in thickness such as streaks or local voids of the pressure-sensitive adhesive were evaluated as x, and those without the evaluation were evaluated as ○.

[0016]

[Table 1]

The emulsion-based pressure-sensitive adhesive composition in Example 1 was a natural rubber latex (SOC
TEX-CB) 50 parts by weight, SBR latex (JSR
50 parts by weight of JSR0545, 100 parts by weight of a tackifier emulsion (“E-100” manufactured by Arakawa Chemical Co., Ltd.), and a modified polyacrylic emulsion as a thickener (SN thickener A-850 manufactured by San Nopco) 7.5 A mixture of 2.1 parts by weight of sodium dodecylbenzenesulfonate (Neoperex No. 25 manufactured by Kao Corporation) as a wetting agent is diluted with water to obtain an emulsion-based pressure-sensitive adhesive composition having a solid content of 30%. The other examples and comparative examples described below are the same as the present example unless otherwise specified.

In Examples 2 and 3, 10.0 and 12.5 parts by weight of the tackifier emulsion of Example 1 were used. Comparative Example 1 is an example in which a wetting agent was not blended, and Comparative Example 2 was a compound of a urethane type in which a wetting agent was not blended and a thickener was formed into a bridge structure with latex to thicken the system. San Nopco SN Thickener A
This is an example of -804.

As shown in Example 2 and Comparative Example 1, when the wetting agent was not added (high viscosity), streaks were formed on the coated surface. As shown in Example 2 and Comparative Example 2, when a thickener of a type that forms a bridge structure with latex and thickens the system is added (has a low viscosity), a portion where the adhesive is not placed on the coated surface Has been completed.

Although not shown in the table, when 20 parts by weight of a wetting agent is added, the viscosity becomes 1000 cps or less, and the solid content of the emulsion tackifying resin itself is reduced to 15%.
When this was set, the adhesive leaked from the coating machine, and when set to 45%, streaks appeared on the coated surface.

[0021]

The emulsion-based pressure-sensitive adhesive composition of the present invention has a rubber component of rubber latex of 100 based on the solid content weight ratio.
0.1 to 10 parts by weight of a wetting agent in an emulsion pressure-sensitive adhesive composition having 30 parts by weight, 30 to 200 parts by weight of a tackifier emulsion, and 0.1 to 20 parts by weight of a thickener. As a result, even an emulsion-based pressure-sensitive adhesive composition diluted with water could be uniformly applied to a thickness of 10 μm.

In another invention, the emulsion-based pressure-sensitive adhesive composition has a solid content of 20 to 40% and a viscosity of 100%.
By specifying 0 to 30000 cps, it was possible to apply evenly an emulsion-based pressure-sensitive adhesive composition having a thickness of 10 μm even with water.

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Claims (2)

[Claims] 1. A rubber composition comprising 100 parts by weight of a rubber component of a rubber latex and a tackifier emulsion 30 to 20 parts by weight based on a solid content.
0.1 to 10 parts by weight of a wetting agent in an emulsion-based pressure-sensitive adhesive composition having 0 parts by weight and 0.1 to 20 parts by weight of a thickening agent. An emulsion-type pressure-sensitive adhesive composition characterized in that it is of a type that thickens the emulsion. 2. A solid content of 20 to 40% and a viscosity of 1000
An emulsion-based pressure-sensitive adhesive composition characterized by having a viscosity of up to 30,000 cps.