JP3016926B2 - Pressure-sensitive adhesive tape and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic pressure-sensitive adhesive tape having excellent adhesive strength, holding power and water resistance.

[0002]

2. Description of the Related Art While desolvation is being promoted in various fields from the point of view of environmental hygiene and the like, an aqueous dispersion using an emulsifier has been proposed in the field of acrylic pressure-sensitive adhesives. However, the adhesive tape obtained by using such a water-dispersed acrylic pressure-sensitive adhesive has a problem in that it has poor holding power, and also has poor water resistance, such as absorption of water and reduced adhesive strength.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve the holding power and water resistance of an adhesive tape made of a water-dispersed acrylic pressure-sensitive adhesive.

[0004]

According to the present invention, an emulsifier in a water-dispersed acrylic pressure-sensitive adhesive is used for ionizing radiation treatment.
There is provided a pressure-sensitive adhesive tape, wherein more pressure-sensitive adhesive layer formed by the compound to the base polymer, having on the support tape.

The present invention also provides a water-dispersible acrylic pressure-sensitive adhesive formed using an emulsifier containing an unsaturated double bond, which is coated on a support tape and treated with ionizing radiation. And a method for producing the pressure-sensitive adhesive tape.

[0006]

The present inventors have conducted intensive studies to improve the water resistance of an adhesive tape composed of a water-dispersed acrylic pressure-sensitive adhesive, and have found that the emulsifier used for dispersing the adhesive in water has become more sensitive. It remains in the pressure-sensitive adhesive layer and investigates that this is the cause of water absorption, and based on this knowledge, further research has led to the preparation of an aqueous dispersion using an emulsifier containing an unsaturated double bond. In addition, it has been found that by integrating the emulsifier with the base polymer, absorption of moisture can be suppressed, and unexpectedly, the holding power is remarkably improved.

[0007]

The pressure-sensitive adhesive tape of the present invention comprises:
Ionizing an emulsifier in the aqueous dispersion type acrylic pressure-sensitive adhesive
It has a pressure-sensitive adhesive layer formed on a support tape by being combined with a base polymer by radiation treatment . The production can be performed, for example, using a water-dispersed acrylic pressure-sensitive adhesive formed using an emulsifier containing an unsaturated double bond.

The preparation of the above-mentioned water-dispersed acrylic pressure-sensitive adhesive is carried out, for example, by emulsion-polymerizing a monomer mixture containing an acrylic acid alkyl ester as a main component using an emulsifier containing an unsaturated double bond. It can be carried out by a method for obtaining an emulsion of the base polymer.

As the acrylic acid alkyl ester,
For example, an alkyl ester of acrylic acid or methacrylic acid having an alkyl group having 12 or less carbon atoms such as a butyl group, an amyl group, a 2-ethylhexyl group, an octyl group, an isononyl group, and the like can be given.

The modifying monomers that may be used in combination with the acrylic acid alkyl esters include vinyl esters such as vinyl acetate and vinyl propionate, styrene derivatives such as styrene and α-methylstyrene, and vinyl monomers. Pyrrolidone, acrylonitrile, methacrylonitrile, acrylamide, N-methylolacrylamide,
Methacrylamide and the like. The amount of the modifying monomer used is equal to or less than that of the acrylic acid alkyl ester.

Unsaturated monomers having a functional group such as acrylic acid, methacrylic acid, (anhydride) maleic acid, itaconic acid, fumaric acid and crotonic acid may be used in combination. The combined use of an unsaturated monomer having a functional group is particularly effective for improving adhesive properties such as cohesion. Its usage is
0.5 to 10% by weight of all monomers is preferred.

Examples of the emulsifier having an unsaturated double bond include sodium alkylallyl sulfosuccinate, nonylphenyl ether type having allyl group and (meth) acryloyl group, and polyethylene glycol / polypropylene glycol type emulsifier. The emulsifier can be used in an amount necessary for the stable progress of emulsion polymerization, and the amount used is not particularly limited. Generally, about 0.5 to 10 parts by weight is used per 100 parts by weight of the monomer mixture.

[0013] Emulsion polymerization of the base polymer can be carried out in a usual manner using a polymerization initiator such as ammonium persulfate or hydrogen peroxide. The method in which the monomer mixture is emulsified in advance with an unsaturated double bond-containing emulsifier and the emulsion is dropped into a water-based reaction system containing a polymerization initiator to allow the reaction to proceed from the viewpoint of polymerization stability. preferable. In the polymerization, a chain transfer agent such as lauryl mercaptan or mercaptoethanol may be used for the purpose of adjusting the molecular weight. The prepared base polymer preferably has a glass transition point of 250 ° K or less from the viewpoint of adhesive properties.

The aqueous dispersion of the base polymer prepared by emulsion polymerization can be used as it is as a water-dispersed acrylic pressure-sensitive adhesive by adjusting the concentration as necessary. Further, a tackifier resin may be blended for the purpose of improving the adhesive strength, tackiness, and the like. In that case, the tackifier resin is preferably emulsified using an unsaturated double bond-containing emulsifier, and mixed with an aqueous dispersion type acrylic pressure-sensitive adhesive as an emulsion from the viewpoint of stabilizing quality. The compounding amount of the tackifier resin is
It is generally 10 to 80 parts by weight per 100 parts by weight of the base polymer.

As the tackifier resin, for example, customary resins such as rosin resin, rosyl ester resin, terpene resin, terpene / phenol resin, and petroleum resin can be used. Examples of the unsaturated double bond-containing emulsifier for emulsifying the tackifier resin include those described above,
The same ones used for the emulsion polymerization of the base polymer are preferably used in view of the stability of the mixed system. The emulsification treatment of the tackifier resin can be performed by, for example, a method of adding a solution of the tackifier resin with an organic solvent or a heated melt of the tackifier resin to water containing an emulsifier under high-speed stirring.

The pressure-sensitive adhesive tape is produced, for example, by applying a water-dispersed acrylic pressure-sensitive adhesive on a support tape, drying it if necessary, and then treating it with ionizing radiation. Can be. Paper,
Conventional materials such as synthetic paper, cloth, laminated cloth, plastic film, metal foil, foam sheet, release liner and the like may be used.

The treatment with ionizing radiation can be performed by, for example, irradiating an electron beam, γ-ray, or the like. This causes the emulsifier to combine with the base polymer via its unsaturated double bond. The irradiation amount of the ionizing radiation is appropriately determined depending on the molecular weight of the base polymer, the content of the emulsifier, and the like. Generally, it is 0.5 to 20 Mrad. If the irradiation amount is less than 0.5 Mrad, the water resistance may not be sufficiently improved, and if it exceeds 20 Mrad, the crosslinking of the base polymer itself may proceed excessively, and the adhesive properties such as tackiness may decrease.

In the present invention, a compound having two or more unsaturated double bonds may be added to the water-dispersed acrylic pressure-sensitive adhesive for the purpose of accelerating the compounding of the emulsifier. Examples of such compounds include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, diethylene glycol diacrylate, dipentaerythritol hexaacrylate, and the like.
The compounding amount is per mole of the emulsifier containing an unsaturated double bond,
0.05 to 2 mol is common. The compound having two or more unsaturated double bonds may be directly added to the water-dispersed acrylic pressure-sensitive adhesive or may be added as an emulsion such as a tackifier resin.

As described above, a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer in which an emulsifier is combined with a base polymer is formed on a support tape. It is also possible to use a separator treated with a release agent for the support tape and transfer the pressure-sensitive adhesive layer formed thereon onto another support tape to form a pressure-sensitive adhesive tape. The thickness of the pressure-sensitive adhesive layer is appropriately determined according to the purpose of use, but is generally 1 to 500 μm.

[0020]

According to the present invention, since were combined based polymer <br/> emulsifier in ionizing radiation treatment, and the compound
By the crosslinking of the base polymer itself, it is possible to obtain a pressure-sensitive adhesive tape having excellent holding power and water resistance made of a water-dispersed acrylic pressure-sensitive adhesive and having satisfactory adhesive strength.

[0021]

【Example】

Example 1 5 equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser tube
20 parts of distilled water in which 0.5 part of potassium persulfate was dissolved was placed in a 00 ml reactor, heated to 80 ° C. under a nitrogen stream, and maintained at 80 ° C. with 80 parts of n-butyl acrylate (weight Parts, the same shall apply hereinafter), 15 parts of ethyl acrylate, and 100 parts of a monomer mixture composed of 5 parts of acrylic acid, and sodium alkyl allyl sulfosuccinate (Eleminol JS-
2. An emulsion prepared by mixing 2 parts of Sanyo Kasei Co., Ltd.) and 46 parts of distilled water was added dropwise over 5 hours, and ammonia water was added to the obtained emulsion polymerization liquid (glass transition point of base polymer: 226 ° K). Was added to adjust the pH to 8, to obtain a water-dispersed acrylic pressure-sensitive adhesive.

Next, the above-mentioned water-dispersed acrylic pressure-sensitive adhesive is applied on a polyester film having a thickness of 25 μm and dried at 120 ° C. for 3 minutes to form a layer having a thickness of 50 μm. An electron beam was irradiated at 3 Mrad (acceleration voltage: 165 kV) to obtain a pressure-sensitive adhesive tape of the present invention.

Example 2 100 parts of a 70% by weight toluene solution of hydrogenated rosin ester (Foralin 90, manufactured by Rika Hercules) was added to 66 parts of distilled water and sodium alkyl allyl sulfosuccinate 2
Of the water-dispersed acrylic pressure-sensitive adhesive obtained in Example 1 and mixed with 30 parts of the emulsified liquid. A pressure-sensitive adhesive tape of the present invention was obtained according to Example 1 using a pressure-sensitive adhesive.

Example 3 A water-dispersed acrylic pressure-sensitive adhesive and a pressure-sensitive adhesive tape of the present invention were obtained in the same manner as in Example 2 except that 2 parts of trimethylolpropane triacrylate was additionally added.

Example 4 According to Example 1, 2-ethylhexyl acrylate 53
Emulsion-polymerization (glass transition point of base polymer: 225 ° K) using a monomer mixture consisting of 1 part, 45 parts of ethyl acrylate and 2 parts of acrylic acid to obtain a water-dispersible acrylic pressure-sensitive adhesive. Was used to obtain a pressure-sensitive adhesive tape of the present invention. However, the electron beam irradiation amount was 4 Mrad.

Example 5 An emulsion of a rosin ester (Superester A-100, manufactured by Arakawa Chemical Industry Co., Ltd.) was prepared according to Example 2, and 30 parts thereof were dispersed in the water-dispersed acrylic sensitizer obtained in Example 4. A pressure-sensitive adhesive tape of the present invention was obtained according to Example 4 using the water-dispersed acrylic pressure-sensitive adhesive and mixing with 100 parts of the pressure-sensitive adhesive.

Comparative Example 1 A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that irradiation treatment with an electron beam was not performed.

Comparative Example 2 A pressure-sensitive adhesive tape was obtained in the same manner as in Example 2 except that irradiation with an electron beam was not performed.

Comparative Example 3 A pressure-sensitive adhesive tape was obtained in the same manner as in Example 4 except that sodium dodecylbenzenesulfonate was used instead of sodium alkyl allyl sulfosuccinate.

Comparative Example 4 A pressure-sensitive adhesive tape was obtained in the same manner as in Example 5, except that sodium dodecylbenzenesulfonate was used instead of sodium alkyl allyl sulfosuccinate as an emulsifier for rosin ester.

Evaluation Test The following characteristics were examined for the pressure-sensitive adhesive tapes obtained in Examples and Comparative Examples. Adhesive force Adhesive force (180 degree peel) was measured according to JIS Z1528.

Holding force: bonded to a bakelite plate with a bonding area of 20 mm × 20 mm,
At 40 ° C. or 80 ° C., the time required to fall by applying a load of 1 kg was examined.

Water Resistance After the pressure-sensitive adhesive tape was immersed in water (room temperature) for 72 hours, it was taken out, the surface water was wiped off, and the water absorption was calculated from the weight difference before and after immersion. The adhesive force of the immersed pressure-sensitive adhesive tape was measured in the same manner as described above.

The results are shown in Table 1.

[Table 1] Table 1 shows that the pressure-sensitive adhesive tapes of the examples are remarkably excellent in holding power and water resistance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-207781 (JP, A) JP-A-61-108677 (JP, A) JP-A-57-70162 (JP, A) JP-A-5-1982 43852 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09J 7/02

Claims (3)

(57) [Claims] 1. A pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer obtained by compounding an emulsifier in a water-dispersed acrylic pressure-sensitive adhesive with a base polymer by ionizing radiation treatment on a support tape. 2. The pressure-sensitive adhesive tape according to claim 1, wherein the water-dispersed acrylic pressure-sensitive adhesive contains an emulsion of a tackifier resin with an unsaturated double bond-containing emulsifier. 3. A water-dispersed acrylic pressure-sensitive adhesive formed using an emulsifier containing an unsaturated double bond is applied on a support tape and treated with ionizing radiation to combine the emulsifier with a base polymer. The method for producing a pressure-sensitive adhesive tape according to claim 1 or 2, wherein: