JPH086079B2 - Pressure sensitive adhesive composition - Google Patents

Description

The present invention relates to a water-based pressure-sensitive adhesive composition, and more particularly, to the up-and-down sealing of cardboard cases and the production of corrugated board, particularly in the distribution industry. The present invention relates to a pressure-sensitive adhesive composition that is useful as a temporary fixing for a manufacturer's cardboard base paper.

(Prior Art) In recent years, acrylic pressure-sensitive adhesives have been widely used in place of conventional natural rubber-based and synthetic rubber-based pressure-sensitive adhesives because of their excellent adhesive properties and durability. In addition, water-based pressure-sensitive adhesives are being researched in consideration of resource saving, environmental hygiene, and product cost. A rubber-based or synthetic rubber-based pressure-sensitive adhesive is inferior to an acrylic pressure-sensitive adhesive in terms of a decrease in tackiness in a low temperature environment, a decrease in cohesive force at a high temperature, and various durability.

It is known that an acrylic polymer prepared by emulsion polymerization has a relatively large molecular weight as compared with a polymer obtained by solution polymerization, so that a relatively high cohesive force can be obtained as a pressure-sensitive adhesive. However, the rubber-based and synthetic rubber-based pressure-sensitive adhesives are several times superior in shearing force, especially in the normal state. Therefore, for example, curved surfaces and bent corrugated cardboard cases exert a restoring force, which is useful for applications that require repulsion resistance that can withstand this restoring force. Most of the adhesive composition is made of rubber or synthetic rubber.

Conventional water-based acrylic pressure-sensitive adhesives are not satisfactory when they are applied to applications where high shear forces are desired. Therefore, in order to further improve the shearing force of this type of pressure-sensitive adhesive, it has been attempted to add a cross-linking agent such as an aziridine compound, a melamine compound, an epoxy compound and a metal salt to the emulsion after emulsion polymerization. However, in such a means, only the cohesive force becomes large, and the adhesive force and the tackiness are reduced accordingly, and eventually the water-based pressure-sensitive adhesive composition having high adhesive force and high shearing force is obtained. Was hard to get.

In addition, as the corrugated cardboard cases on the market have a restoring force,
At the same time, the repulsion resistance that can withstand this restoring force is significantly reduced, and there is a problem in that it is difficult to obtain an excellent repulsion resistance.

(Problems to be Solved by the Invention) The present invention provides a pressure-sensitive adhesive capable of suppressing repulsion when attached to a curved or curved surface, such as vertical sealing of a corrugated cardboard case and temporary fixing of corrugated cardboard.

[Structure of Invention]

(Means for Solving the Problems) In the present invention, (meth) acrylic acid ester (a) having an alkyl group having 4 to 12 carbon atoms (a) 60 to 99.8 parts by weight, polymerizable unsaturated carboxylic acid (b) 0.2 to 10 100 parts by weight of acrylic acid ester-based copolymer (solid content) obtained by emulsion polymerization of 0 to 39.8 parts by weight of copolymerizable vinyl-based monomer (c) other than the above and acrylic acid ester-modified SBR
A pressure-sensitive adhesive composition comprising 5 to 45 parts by weight of emulsion (solid content).

(Meth) acrylic acid alkyl ester (a) of the present invention
Is an acrylic acid ester or a methacrylic acid ester having an alkyl group having 4 to 12 carbon atoms, and particularly preferable one is 2-ethylhexyl acrylate, and butyl acrylate, hexyl acrylate, octyl acrylate and the like are used. To be

Examples of the polymerizable unsaturated carboxylic acid (b) include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid and fumaric acid. When these polymerizable unsaturated carboxylic acids (b) are copolymerized in a small amount, they are effective in improving adhesiveness and cohesive force. Above (a), (b)
Examples of vinyl-based monomers (c) other than (a) include acrylic monomers other than (a) or styrene, vinyltoluene, vinyl acetate, acrylonitrile, and the like. In particular, acrylonitrile and methacrylnitrile having a nitrile group are suitable as a vinyl-based monomer having a relatively large polarity and have a structure close to that of a reticulated polymer peculiar to a rubber system, and are suitable for adhesion of an adherend having a strong resilience. Other acrylic acid 2-
A polymerizable monomer having a hydroxyl group such as hydroxyethyl may be used.

The pressure-sensitive adhesive of the present invention is obtained by blending an acrylic acid ester-modified SBR emulsion with an emulsion obtained by copolymerizing the above monomers by a usual emulsion polymerization method. The amount of the acrylic acid ester-modified SBR emulsion is 5 to 45 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight (solid content) of the acrylic acid ester copolymer. If the amount of the acrylic acid ester-modified SBR is less than 5 parts by weight, the effect of the addition is not observed, and if it exceeds 45 parts by weight, the tackiness required as a pressure-sensitive adhesive decreases, which is not preferable.

The acrylic ester modified SBR emulsion can be obtained by modifying the SBR emulsion with the (meth) acrylic ester (a). The modification ratio is 5 to 30% by weight of the (meth) acrylic acid ester (a) with respect to the solid content of SBR.

(Effects of the Invention) Acrylic ester-modified SBR has better compatibility with acrylic ester-based pressure-sensitive adhesives than general SBR, and does not aggregate or separate after compounding. Moreover, the characteristics of the conventional acrylic emulsion are not lost by the blending.

The shearing force of rubber-based and synthetic rubber-based pressure-sensitive adhesives at room temperature has little dependence on the pulling speed, and when bonded to a curved or curved surface such as corrugated cardboard, it is excellent in repulsive property at a slow speed. Has performance. The pressure-sensitive adhesive of the present invention expresses the high shear property, which is a characteristic of rubber-based and synthetic rubber-based pressure-sensitive adhesives, without impairing the advantages of the pressure-sensitive adhesive that the acrylic emulsion originally has. Is.

(Example) Hereinafter, the present invention will be described with reference to an example. In the examples, “part” means “part by weight”.

Example 1 Pure water 65 parts Sodium citrate 0.6 parts Dodecylbenzene sulfonate 1 part Polyoxyethylene nonylphenol ether 1 part Weigh and heat to 70 ° C. under stirring at 200 rpm.

Then, a mixture of 2-ethylhexyl acrylate 70 parts Butyl acrylate 22 parts Vinyl acetate 4.5 parts Acrylic acid 3.5 parts and 10 parts of 10% ammonium persulfate aqueous solution 6 parts are uniformly added dropwise to the reaction system kept at 70 ° C for 3 hours. And polymerize. After all the monomers have been added dropwise, the reaction is continued at 70 ° C. for 2 hours to complete the polymerization.

Acrylic ester-modified SBR emulsion (manufactured by Nippon Zeon Co., Ltd. under the trade name QTI-10
05; the same in the following examples) was added in an amount of 10 parts (based on solid content) to obtain a pressure-sensitive adhesive composition.

Apply this pressure-sensitive adhesive composition to high-quality paper (45 kg),
A sample was obtained. After that, the above-mentioned sample pieces were attached to a corrugated cardboard base paper (liner) in an atmosphere of 23 ° C-65% RH, roll-bonded according to JIS method, and shearing force was measured by a Shopper type peeling tester.

 The measurement results are shown in the table below.

Example 2 13 parts of pure water is weighed and heated to 90 ° C. under stirring at 200 rpm.

Next, a pre-emulsion was prepared with 2-ethylhexyl acrylate 90 parts vinyl acetate 5 parts acrylic acid 5 parts polyoxyethylene sorbitan monolaurate 1 part polyoxyethylene nonylphenol ether 1 part sodium citrate 0.6 parts pure water 52 parts Then, 6 parts of 10% aqueous sodium persulfate solution was added, and the mixture was uniformly added dropwise to the reaction system kept at 70 ° C. for 3 hours for polymerization. After all the pre-emulsion has been dropped, the reaction is continued at 80 ° C. for 2 hours to complete the polymerization.

A pressure sensitive adhesive composition was obtained by adding 20 parts (solid content basis) of acrylic acid ester-modified SBR to 100 parts of the solid content of this composition. This composition was operated in the same manner as in Example 1 to prepare a sample, and the shearing force was similarly measured. The measurement results are shown in the table.

Example 3 13 parts of pure water was calculated and heated to 70 ° C. under stirring at 200 parts rpm.

Next, 2-ethylhexyl acrylate 87 parts Methyl methacrylate 10 parts Methacrylic acid 3 parts Dodecylbenzene sulfonate 1 part Polyoxyethylene nonylphenol ether 1 part Sodium acetate 0.6 parts Pure water 55 parts to prepare a pre-emulsion, 6 parts of an aqueous solution of ammonium sulfate is added, and the mixture is uniformly added dropwise to the reaction system kept at 70 ° C. for 3 hours for polymerization. After all the pre-emulsion was dropped, the reaction was continued at 70 ° C. for 2 hours to complete the polymerization.

To 100 parts of the solid content of this composition, 25 parts of acrylic ester-modified SBR (based on the solid content) was added to obtain a pressure-sensitive adhesive composition. A sample was prepared by operating this composition in the same manner as in Example 1, and the shearing force was measured in the same manner. The measurement results are shown in the table.

Example 4 13 parts of pure water is weighed and heated to 70 ° C. under stirring at 200 rpm.

Next, 2-ethylhexyl acrylate 87 parts Acrylonitrile 10 parts Acrylic acid 3 parts Dodecyl benzene sulfonate 10 parts Polyoxyethylene nonylphenol ether 1.0 part Sodium acetate 0.6 parts Pure water 55 parts Prepare a pre-emulsion and prepare a 10% ammonium persulfate aqueous solution. 6 parts was added, and the mixture was dropped uniformly into the reaction system kept at 70 ° C. for 3 hours to polymerize. After all the pre-emulsion was dropped, the reaction was continued at 70 ° C. for 2 hours to complete the polymerization.

To 100 parts of the solid content of this composition, 10 parts of acrylic acid ester-modified SBR was added to obtain a pressure-sensitive adhesive composition. This composition was operated in the same manner as in Example 1 to prepare a sample, and the shearing force was measured in the same manner.

 The measurement results are shown in the table.

Example 5 13 parts of pure water is weighed and heated to 70 ° C. under stirring of 200 RPM ”.

Then, 2-ethylhexyl acrylate 87 parts Methacrylonitrile 10 parts Acrylic acid 3 parts Dodecylbenzene sulfonate 1.0 part Polyoxyethylene nonylphenol ether 1.0 part Sodium citrate 0.6 parts Pre-emulsion prepared with pure water 55 parts and 10% ammonium persulfate 6 parts of an aqueous solution is added, and the mixture is uniformly added dropwise to the reaction system kept at 70 ° C. for 3 hours for polymerization. After all the pre-emulsion was dropped, the reaction was continued at 70 ° C. for 2 hours to complete the polymerization.

15 parts of acrylic ester-modified SBR was added to 100 parts of the solid content of this composition to obtain a pressure-sensitive adhesive composition. A sample was prepared by operating this composition in the same manner as in Example 1, and the shearing force was measured in the same manner.

 The measurement results are shown in the table.

Comparative Examples 1 to 5 The compositions obtained in Examples 1 to 5 were modified with an acrylic ester.
A sample piece was prepared in the same manner as in Example 1 except that SBR was not blended, and the pressure-sensitive adhesive compositions were compared.

 The measurement results are shown in the table.

As is apparent from the table, the pressure-sensitive adhesive composition of the present invention has a high shearing force, is extremely excellent in actual sticking property, and is a practically useful pressure-sensitive adhesive composition.

Claims (1)

[Claims] 1. A (meth) acrylic acid ester (a) having an alkyl group having 4 to 12 carbon atoms (a) (60 to 99.8 parts by weight), a polymerizable unsaturated carboxylic acid (b) (0.2 to 10 parts by weight), and a copolymer other than the above. 100 parts by weight (solid content) of acrylic acid ester-based copolymer obtained by emulsion polymerization of 0 to 39.8 parts by weight of possible vinyl-based monomer (c) and acrylic acid ester-modified SBR
A pressure-sensitive adhesive composition comprising 5 to 45 parts by weight of emulsion (solid content).