JPH0144266B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an adhesive tape or an adhesive sheet, and in particular, the surface base paper of the adhesive tape or adhesive sheet is an neutral paper containing 2 to 70% by weight of calcium carbonate as a filler in the paper. The present invention provides a pressure-sensitive adhesive tape or a pressure-sensitive adhesive sheet that exhibits good adhesion to polyolefin without deterioration in adhesive strength by providing a specific pressure-sensitive adhesive layer. [Prior art and problems to be solved by the invention] Conventionally, acidic paper has been used as the surface base paper for adhesive tapes or adhesive sheets, but the sulfuric acid band, which is a sizing agent, is susceptible to sulfuric acid during long-term storage. This has become a problem as it acts on the paper and causes it to deteriorate. In recent years, advances in papermaking technology have led to the development of neutral paper using sizing agents such as alkyl ketene dimers, which can withstand long-term storage. Neutral paper usually contains 2 to 70% by weight of calcium carbonate as a filler in the paper. Conventional acrylic adhesives copolymerize carboxylic acid monomers such as acrylic acid to improve polymerization stability, mechanical stability, and adhesive strength, so neutral paper was used as the surface base paper. For adhesive tapes or adhesive sheets, storage under moist heat conditions (e.g., 80°C, 95% RH) results in denaturation of the adhesive, which is thought to be due to the reaction between calcium carbonate and carboxyl groups, although the details are unknown.
Adhesive strength decreased over time. [Means for Solving the Problems] The present inventors have conducted intensive research on the decrease in adhesive strength of adhesive tapes or adhesive sheets made of neutral paper as the surface paper, an acrylic adhesive layer and release paper, and have found that We have completed an adhesive tape or adhesive sheet that has good adhesion to polyolefin without any decrease in adhesive strength that is seen in other products. That is, in the present invention, in the adhesive tape or adhesive sheet 4 formed by laminating the surface base paper 1, the adhesive layer 2, and the release paper 3, the surface base paper 1 accounts for 2 to 70% by weight.
calcium carbonate as a filler in the paper, and the adhesive layer 2 is made of an acrylic ester monomer having an alkyl group having 4 to 10 carbon atoms, or the above acrylic ester monomer and an alkyl group having 3 or less carbon atoms. A mixture of an acrylic acid (or methacrylic acid) ester monomer and a vinyl acetate monomer having the general formula (However, in the above formula, R is hydrogen or a methyl group, M
represents hydrogen, ammonium, or a monovalent metal. The configuration of the present invention will be explained with reference to the drawings. The figure is an enlarged sectional view for explaining the structure of the adhesive tape or adhesive sheet according to the present invention, in which 1 is the surface base paper, 2 is the adhesive layer, 3 is the release paper, and 4 is the adhesive tape or adhesive sheet. shows. The adhesive tape or adhesive sheet with the above structure is
By removing the acrylic acid that reacts with the calcium carbonate in neutral paper from the adhesive and instead copolymerizing sulfonic acid monomers, we prevent the adhesive from deteriorating under moist heat conditions and eliminate any decrease in adhesive strength, while at the same time polymerizing. This makes it possible to maintain stability and mechanical stability. As the sulfonic acid monomers used, allylsulfonic acid, methallylsulfonic acid, and their metal salts are effective because they have excellent adhesiveness to polyolefins and do not show any decrease in adhesive strength under moist heat conditions. , acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, and metal salts thereof are not suitable because of their low adhesive strength to polyolefin. As the surface-based paper in the present invention, neutral papers such as fine, coated, and cast coated papers containing 2 to 70% by weight of calcium carbonate can be used. The ratio of each monomer in the adhesive will be explained. As the acrylic acid ester monomer having an alkyl group having 4 to 10 carbon atoms, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, etc. are used, and the amount is 60 to 95% by weight, preferably 80 to 95% by weight.
Weight % is suitable. As an acrylic acid (or methacrylic acid) ester monomer having an alkyl group having 3 or less carbon atoms,
Examples include methyl acrylate, ethyl acrylate, and methyl methacrylate. These are not necessarily essential, but when added, it is preferably 10% by weight or less. Vinyl acetate monomer is an essential component and is preferably 20% by weight or less; if vinyl acetate exceeds 20%, adhesive strength decreases. The following formula (i) (However, in the above formula, R is hydrogen or a methyl group, M
represents hydrogen, ammonium, or a monovalent metal) The allylsulfonic acid or methallylsulfonic acid derivative represented by is also an essential component, and the amount thereof is from 0.05 to
10% by weight, preferably 0.1-5% by weight is used;
If it exceeds 10% by weight, it will adversely affect the adhesive properties. It is characterized by using a copolymer composed of the above monomers as an adhesive. The adhesive of the present invention may be polymerized by emulsion polymerization, suspension polymerization, or the like, but emulsion polymerization is generally preferred. The emulsion polymerization method uses emulsifiers such as alkylphenols, adducts of higher alcohols and ethylene oxide, and other sulfuric ester derivatives, or block polymers of polyethylene oxide and polypropylene oxide, persulfates, bisulfites, and peroxides. There is a method in which the monomer or monomers are emulsified with the above emulsifier and added to an aqueous solution containing a water-soluble polymerization initiator such as hydrogen-iron chloride. It is also possible to use a seed polymerization method in which an initiator and an emulsified monomer are further added to the emulsion obtained by the above polymerization method and polymerized. The pressure-sensitive adhesive thus obtained may contain additives such as fillers, thickeners, antifoaming agents, etc., if necessary. [Example] Example 1 In a reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet pipe and a reflux condenser, 40% butyl acrylate was added.
parts by weight, 40 parts by weight of 2-ethylhexyl acrylate, 9.95 parts by weight of vinyl acetate, 10 parts by weight of methyl methacrylate, 0.05 parts by weight of sodium allylsulfonate, and 3 parts by weight of sodium dodecylbenzenesulfonate as an emulsifier. , 0.1 part by weight of dodecyl mercaptan and 100 parts by weight of ion-exchanged water.
parts by weight were added and heated while stirring under a nitrogen stream. When the reaction system reached about 40°C, 0.2 parts by weight of ammonium persulfate and 0.1 parts by weight of sodium disulfite were added as polymerization initiators to initiate polymerization. Then, the reaction temperature was raised to 70°C and the polymerization reaction was carried out for about 30 minutes, and then the remaining 80 parts by weight of the monomer mixture was added to 3
The mixture was added dropwise over a period of time, and after the completion of the addition, the mixture was allowed to react for about 3 hours to obtain an adhesive. After neutralizing the above adhesive by dropping approximately 25% ammonia aqueous solution while stirring, the dry weight is 25g/m ² on neutral paper (base paper for cast coating) containing 10% by weight of calcium carbonate as a filler in the paper. I applied it and let it dry. A release paper laminated with polyethylene was layered on the adhesive-coated surface and bonded to produce an adhesive sheet. The initial adhesion strength of the adhesive sheet thus obtained to polyethylene and the adhesive strength after storage for 3 days under moist heat conditions (80°C, 95% RH) are shown in Table 1.
It was as shown in. Example 2 An adhesive sheet was prepared in the same manner as in Example 1 using the adhesive obtained in Example 1 and neutral paper (high quality paper for PPC) containing 2% by weight of calcium carbonate as a filler in the paper. It was created. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1. Example 3 An adhesive sheet was made in the same manner as in Example 1 using the adhesive obtained in Example 1 and neutral paper (base paper for wallpaper) containing 70% by weight of calcium carbonate as a filler in the paper. Created. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1. Example 4 The monomer mixture of Example 1 was butyl acrylate: 2-ethylhexyl acrylate: vinyl acetate: sodium allylsulfonate = 45:45:9.95:
A pressure-sensitive adhesive was obtained by polymerizing an emulsion mixture using a monomer composition of 0.05, and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 using the same neutral paper as in Example 1. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1. Example 5 Butyl acrylate: 2-ethylhexyl acrylate: vinyl acetate: sodium allylsulfonate =
An emulsion mixture having a monomer composition of 40:40:10:10 was polymerized to obtain a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1. Example 6 Using the same neutral paper as in Example 1 and using the same method,
An emulsion mixture with a monomer composition of butyl acrylate: 2-ethylhexyl acrylate: vinyl acetate: methyl methacrylate: sodium methallylsulfonate = 40:40:9.95:10:0.05 was polymerized to obtain an adhesive and carried out. A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1. Comparative Example In the same manner as in Example 1, butyl acrylate:
An emulsion mixture having a monomer composition of 2-ethylhexyl acrylate: vinyl acetate: acrylic acid = 45:45:9:1 was polymerized to obtain a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1. The initial adhesive strength of this sheet and the adhesive strength after storage under humid heat conditions were as shown in Table 1.

[Table] Adhesive strength is for polyethylene.
According to JIS-Z-1538, the adhesive sheet was pasted in a room at 20℃ and 65% RH with a 3kg roller 2.5 times back and forth, and after 10 minutes it was tested at 300mm/min using a tensile tester.
The adhesive strength was measured when the adhesive was peeled off from an angle of 180° at a pulling speed of .

[Brief explanation of drawings]

The figure is an enlarged sectional view for explaining the structure of the adhesive sheet according to the present invention. In the figure, 1...surface base paper, 2...adhesive layer, 3...
...Release paper, 4...Adhesive sheet or adhesive sheet.

Claims (1)

[Scope of Claims] 1. A surface-based paper containing 2 to 70% by weight of calcium carbonate as a filler in the adhesive tape or adhesive sheet formed by laminating a surface-based paper, an adhesive layer, and a release paper. An adhesive tape or adhesive sheet that has good adhesion to polyolefin and is laminated with an adhesive layer having the composition shown below and an ordinary release paper. Adhesive composition: 60 to 95% by weight of an acrylic ester monomer having an alkyl group having 4 to 10 carbon atoms, 0 to 95% by weight of an acrylic acid or methacrylic acid ester monomer having an alkyl group having 3 or less carbon atoms.
10% by weight, vinyl acetate monomer 20% by weight or less, general formula [However, R: hydrogen or methyl group, M: hydrogen, ammonium group, or monovalent metal] Consisting of 10% by weight or less of monomers of derivatives of allylsulfonic acid or methallylsulfonic acid, each of the above monomers copolymer.