JPS6044573A - Manufacture of pressure-sensitive adhesive tape - Google Patents

Abstract

PURPOSE:To obtain the titled tape having remarkably improved anchoring effect between a polyolefin sheet and an emulsion-type pressure-sensitive adhesive, by using an undercoating agent comprising an emulsion-type acrylic polymer containing zirconium hydroxyacetate. CONSTITUTION:Preferably 1-15pts.wt. of a 5-20% aqueous solution of zirconium hydroxyacetate is added to 100pts.wt. of an emulsion-type acrylic polymer prepared by the emulsion polymerization of an acrylic monomer (preferably 1-10C alkyl (meth)acrylate, etc.). The obtained acrylic emulsion is used as an undercoating agent, and is applied to the oxidized surface of a polyolefin sheet to a thickness of 0.01-2mu (as dried film). The objective tape can be manufactured by applying an emulsion-type pressure-sensitive adhesive to the coated surface to a thickness of 5-50mu (as dried film).

Description

DETAILED DESCRIPTION OF THE INVENTION In the production of pressure-sensitive adhesive tapes, sheets, labels, etc. using a polyolefin sheet as a support, the present invention uses a specific primer to bond the polyolefin sheet and emulsion-type pressure-sensitive adhesive. The present invention relates to a method for producing pressure-sensitive adhesive tapes that can significantly improve anchoring properties and provide stable adhesive strength and cohesive strength.

Conventionally, various self-supporting sheets such as paper, plastic sheets, and metal foils have been used as supports for pressure-sensitive adhesive tapes. In particular, polyolefin sheets such as polyethylene and polypropylene have moisture-proof, chemical-resistant, and electrically insulating properties. Because of its excellent properties, it can be said to be a useful support for a variety of uses such as packaging, surface protection, and electrical insulation. In addition, in recent years, acrylic pressure-sensitive adhesives have become widely used in place of conventional natural rubber-based and synthetic rubber-based pressure-sensitive adhesives due to their excellent adhesive properties and durability. Among pressure-sensitive adhesives, emulsion-type adhesives that do not use organic solvents are recently replacing them.

However, emulsion-type pressure-sensitive adhesives that are coated and dried on polyolefin sheets have an essential drawback of poor anchoring properties.As a means to improve this, we have developed a method that uses surface-oxidized polyolefin sheets and uses pressure-sensitive adhesives. Attempts have been made to improve anchoring properties by introducing a functional group such as a carboxyl group into the material, and efforts have been made to use catalysts from cross-linking agents used in pressure-sensitive adhesives as primers, but none of these methods have been effective. The reality is that fully satisfactory results have not been obtained.

As a result of intensive research on improving the anchoring properties of a polyolefin sheet and an emulsion-type pressure-sensitive adhesive layer, the present inventors used a surface-oxidized polyolefin sheet as a support, and used the sheet and an emulsion-type pressure-sensitive adhesive layer. The present invention was based on the discovery that the presence of a specific primer at the interface with the layer significantly improves anchoring properties.

That is, the present invention applies zirconium oxyacetate as an undercoat when producing pressure-sensitive adhesive tapes by coating and drying an emulsion type pressure-sensitive adhesive on the treated surface of a polyolefin sheet subjected to surface oxidation treatment. The present invention also relates to a method for producing pressure-sensitive adhesive tapes characterized by using an emulsion-type acrylic polymer added thereto.

Polyethylene, polypropylene, poly(1-butene), etc. are used as the polyolefin sheet used in the present invention, and the surface oxidation treatment of the sheet includes corona treatment, flame treatment, chemical oxidation treatment, etc. to oxidize one or both sides of the sheet. The processed one is used.

The emulsion-type acrylic polymer constituting the primer is obtained by polymerizing acrylic ffi polymers using a special emulsion polymerization method, and the monomers include alkyl esters of acrylic acid or methacrylic acid (alkyl groups). (having 1 to 10 carbon atoms) or the above alkyl esters and other vinyl monomers copolymerizable therewith are preferably used, and examples of the alkyl esters of acrylic acid or methacrylic acid include ethyl acrylate, propyl acrylate, One or two examples include butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc.
You may use more than one species in combination. Other vinyl monomers that can be copolymerized with these alkyl esters include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, 2-hydroxyethyl acrylate, and N-N-dimethylaminoethyl acrylate. , acrylamide, n-
Examples include butoxymethyl methacrylamide, glycidyl methacrylate, acrylonitrile, vinyl acetate, methacrylate, and styrene.

In addition, zirconium oxyacetate used as an additive for the primer is heated and dissolved in water to form a 5-20% aqueous solution, and added in an amount of 1-15 parts by weight per 100 parts by weight of the emulsion-type acrylic polymer. used. The primer coat prepared in this manner is applied to the treated surface of the polyolefin sheet which has undergone surface oxidation treatment and is allowed to dry, but the coating thickness after drying must be 0.01 to 2 μm. If the coating thickness is less than 0.01 μm, a good anchoring effect cannot be obtained,
If the thickness is 2 μm or more, the undercoat is acidic, and when an emulsion-type pressure-sensitive adhesive is applied on the undercoat layer, it may affect the stability of the emulsion and make the adhesive surface defective. It is best to use within a range.

Further, the emulsion type pressure sensitive adhesive used in the present invention may be a natural rubber type or a synthetic rubber type adhesive, but is preferably an acrylic type emulsion type pressure sensitive adhesive of the same type as the above-mentioned primer. Generally, the main monomer is an acrylic acid (or methacrylic acid) alkyl ester (alkyl group having 4 to 10 carbon atoms), and a modifying monomer is used to impart functions such as adhesive force and cohesive force to the main monomer. An emulsion obtained by adding a substance and emulsion polymerizing in an aqueous medium is used.

The above-mentioned modifying monomers include acrylic acid, methacrylic acid, itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, N-N-dimethylaminoethyl acrylate, acrylamide, methacrylamide, N- Methylol acrylamide, glycidyl acrylate, acrylonitrile, methacrylonitrile, vinyl acetate, styrene, etc. are used. Examples of these acrylic emulsion type pressure sensitive adhesives include Japanese Patent Application No. 55-189175, Japanese Patent Application No. 56-29133, Japanese Patent Application No. 57-35437, and Japanese Patent Application No. 57-2082.
Those described in No. 56 and the like may also be used.

The reason why the pressure-sensitive adhesive tapes obtained by the present invention exhibits an anchoring effect is not clear, but an inorganic-organic composite is formed by combining an emulsion-type acrylic polymer and zirconium oxyacetate as an undercoat, and the composite It is presumed that this effect not only strengthens the anchoring ability for the polyolefin sheet, but also improves the affinity with the emulsion-type pressure-sensitive adhesive, resulting in good anchoring ability.

To show a specific method for implementing the present invention, first, a polyolefin sheet whose surface has been oxidized is prepared, and 1 to 15 parts by weight of zirconium oxyacetate is applied to the treated surface based on 100 parts by weight of the emulsion type acrylic polymer. A base coat containing an aqueous solution of about 5 to 20% solids is applied to a dry thickness of 0.01 to 2 μm, and an emulsion-type pressure-sensitive adhesive is applied on top of this to a dry thickness of 0.01 to 2 μm. 5
By coating and drying to a thickness of ~50 μm, a pressure-sensitive adhesive sheet with very good anchoring properties between the polyolefin sheet and the pressure-sensitive adhesive and stable adhesive strength and cohesive strength can be obtained.

Hereinafter, the present invention will be explained in detail with reference to Examples and Production Examples, but the present invention is not limited to these Examples. Note that in the following, parts mean parts by weight, and the adhesive strength and anchoring strength tests were measured by the following methods.

[Adhesive strength]

The produced pressure-sensitive adhesive tape sample was cut into a width of 20 mm,
Attach to a degreased SUS 304 stainless steel plate 3
After standing for 0 minutes, 180 degree peeling adhesive strength (peeling speed 300Il1m/min, 20°C x 65%R,) 1. ) to measure.

[Anchoring power]

The operations of rapidly adhering and separating the adhesives of the produced pressure-sensitive adhesive tape samples were repeatedly performed, and the anchoring force was evaluated by the number of adhesion and separation operations until the adhesive layer peeled off from the support sheet.

Production Example 1 80 parts of butyl acrylate, 20 parts of acrylonitrile, 5 parts of acrylic acid, 5 parts of polyoxyethylene alkylphenol ether, and 160 parts of ion-exchanged water were placed in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser. was charged and heated under a nitrogen stream while stirring until the reaction system reached about 6
When the temperature reaches 0° C., 0.3 parts of ammonium persulfate is added as a polymerization initiator to initiate polymerization, and the polymerization reaction is carried out for about 3 hours.

After the polymerization was completed, the reaction system was heated to about 75° C. and aged for about 1 hour to obtain an emulsion composition containing a copolymer. An acrylic emulsion-type pressure-sensitive adhesive having a viscosity of about 5 poise (at 20° C.) was prepared by dropping an approximately 3% ammonia aqueous solution into the emulsion composition while stirring.

Production Example 2 The monomer composition shown in Table 1 was charged into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and polyoxyethylene alkylphenol ether 5 was added to the monomer composition shown in Table 1.
and 160 parts of ion-exchanged water, heated while stirring under a nitrogen stream, and when the temperature inside the reactor reached approximately 60°C, 0.2 parts of ammonium persulfate was added as a polymerization initiator to start polymerization. The polymerization reaction is carried out for about 3 hours. After the polymerization is completed, the reaction system is heated to about 75° C. and aged for about 1 hour to obtain an emulsion type acrylic polymer.

Examples 1 to 4 An emulsion-type acrylic polymer prepared according to Production Example 2 using the monomer composition shown in Table 1 was mixed with ion-exchanged water so that the solid content was 10%, and a 10% aqueous zirconium oxyacetate solution was added. A primer was prepared by adding 3 parts of the above acrylic polymer to 100 parts of the above acrylic polymer.

This primer was applied to the treated surface of a corona-treated 60 μm polyethylene sheet so that the thickness after drying would be 0.5 μm, heated and dried at 90° C. for 1 minute, and then prepared in Production Example 1. The resulting emulsion-type pressure-sensitive adhesive was applied to a dry thickness of 20 μm, and dried by heating at 90° C. for 3 minutes to obtain an original pressure-sensitive adhesive tape.

Table 1 Comparative Example 1 An emulsion type acrylic polymer obtained from the monomer composition shown in Table 1 used in Example 1 was used as a primer without adding zirconium oxyacetate,
A pressure-sensitive adhesive tape original was obtained according to Example 1.

Comparative Example 2 Emulsion type acrylic polymer 100 produced from the monomer composition of Example 1 shown in Table 1 according to Production Example 2
0.5 parts (solid content) of zirconium oxyacetate
The undercoating agent was prepared by adding 50% of the undercoating agent, and applied so that the thickness of the undercoating agent after drying was 0.01 μm. Thereafter, the same procedure as in Example 1 was carried out to obtain a pressure-sensitive adhesive tape material.

Comparative Example 3 The pressure-sensitive adhesive obtained in Production Example 1 was applied to the corona-treated surface of a polyethylene sheet without applying a primer to obtain a pressure-sensitive adhesive tape original according to Example 1.

The adhesive strength and anchoring strength of each of the pressure-sensitive adhesive tape samples of Examples 1 to 4 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 2.

Table 2

Claims (3)

[Claims] (1) When manufacturing pressure-sensitive adhesive tapes by coating and drying an emulsion-type pressure-sensitive adhesive on the treated surface of a polyolefin sheet that has undergone surface oxidation treatment, zirconium oxyacetate is added as an undercoat. A method for producing pressure-sensitive adhesive tapes characterized by using an emulsion-type acrylic polymer. (2) The emulsion type acrylic polymer is
or) obtained by emulsion polymerization of an acrylic acid alkyl ester monomer (alkyl group having 1 to 10 carbon atoms) or the above alkyl ester monomer and a vinyl monomer copolymerizable with it. A method for producing pressure-sensitive adhesive tapes according to claim 1. (3) Zirconium oxyacetate as a primer is 1 to 1 part by weight per 100 parts by weight of the emulsion type acrylic polymer.
5 parts by weight of the pressure-sensitive adhesive tape according to claim 1.