JPH05163472A - Adhesive composition - Google Patents

Abstract

PURPOSE:To obtain an adhesive, not inferior to conventionally used adhesives even in aspect of the initial adhesion, capable of providing an adhesive film having high elastic modulus and excellent in water resistance. CONSTITUTION:An adhesive composition is obtained by blending 100 pts.wt. resin content of a vinyl acetate resin-based emulsion with an acrylic emulsion having 50-100 deg.C glass transition temperature in an amount of 10-70 pts.wt. expressed in terms of resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition having excellent adhesive strength and water resistance, and more particularly to an adhesive composition which is preferably used when producing a paper tube.

[0002]

2. Description of the Related Art Conventionally, as this type of adhesive, one based on starch, polyvinyl alcohol (hereinafter referred to as PVA), polyvinyl acetate, etc. has been used. Moreover, the thing which mixed these, the thing which added the filler, etc. are also used.

[0003]

Generally, an adhesive for a paper tube is required to have an initial adhesive property, a compression resistance of the paper tube, and the like.
In order to improve the compression strength, it is necessary to harden the film to increase the elastic modulus of the film and increase the water resistance.

However, it is the actual situation that none of the above-mentioned conventional adhesives have satisfactory initial adhesiveness, film elastic modulus and water resistance.

The present invention has been made in view of such circumstances, and the adhesive film has a high elastic modulus and is comparable to the conventionally used adhesives in terms of initial adhesiveness,
Further, it is intended to provide an adhesive having excellent water resistance.

[0006]

The adhesive composition of the present invention for solving the above-mentioned problems has a glass transition temperature of 5 with respect to 100 parts by weight of the resin content of the vinyl acetate resin emulsion.
The acrylic emulsion at 0 to 100 ° C. is blended in an amount of 10 to 70 parts by weight in terms of resin content.

As a vinyl acetate resin emulsion,
For example, a product obtained by polymerizing PVA as a protective colloid in water in the presence of a polymerization initiator can be used. As the polymerization initiator, potassium persulfate, ammonium persulfate, hydrogen peroxide, tartaric acid, etc. are appropriately used alone or in combination. The proportion of vinyl acetate is preferably in the range of 10 to 50% by weight, and completely saponified PVA is preferable from the viewpoint of the water resistance of the film. Also,
The proportion of PVA is preferably in the range of 2 to 20% by weight. The amount of the polymerization initiator used is preferably in the range of 0.05 to 5% by weight.

The acrylic emulsion to be blended with the vinyl acetate resin emulsion contains, as a main component, at least one of acrylic acid ester and / or methacrylic acid ester, and, if necessary, other ethylenic non-polymerizable copolymers. An emulsion obtained by emulsion-copolymerizing a saturated monomer, having a glass transition temperature of 50 to 100 ° C.
Use the one in the range.

Examples of the acrylic ester include ethyl acrylate, n-butyl, 2-ethylhexyl, and n-acrylate.
Examples thereof include esters such as octyl and isononyl.

Examples of the methacrylic acid ester include methacrylic acid esters such as methyl, ethyl, n-butyl, 2-ethylhexyl, decyl, lauryl and stearyl.

Examples of the ethylenically unsaturated monomer copolymerized with an acrylic acid ester and / or a methacrylic acid ester as required include vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate, styrene, acrylamide and methacrylamide. , Acrylonitrile and the like are exemplified, but the invention is not limited thereto.

The preferred range of the copolymerization ratio of acrylic acid ester and / or methacrylic acid ester monomer is 50 to 100% by weight.

Regarding the method for producing an acrylic emulsion, in order to improve the film strength, a film-forming property at a low temperature is secured without adding a film-forming auxiliary agent such as a plasticizer, while maintaining a high glass transition temperature. Therefore, for example, a so-called two-stage polymerization method, in which the inner layer of the resin particles is polymerized with a monomer composition that raises the glass transition temperature and the outer layer is polymerized with a small amount of the monomer composition that lowers the glass transition temperature, is suitable. ing.

The mixing ratio of the acrylic emulsion to the vinyl acetate resin emulsion is limited to the range of 10 to 70 parts by weight in terms of the resin content with respect to 100 parts by weight of the resin content of the vinyl acetate resin emulsion. The reason is 1
If it is less than 0 parts by weight, the elastic modulus of the obtained adhesive film is inferior, and if it exceeds 70 parts by weight, phenomena such as thickening and gelation may occur due to aging. A particularly preferred range is 30 to 50 parts by weight.

[0015]

The adhesive according to the present invention is a mixture of a vinyl acetate resin emulsion and a specific acrylic emulsion, so that the adhesive is applied to the adherend by the action of the acrylic emulsion. A high elastic modulus can be imparted to the film, excellent initial adhesiveness can be obtained, and excellent water resistance can be obtained.

[0016]

EXAMPLES Next, examples of the present invention and comparative examples to be compared are given to clarify the advantages of the present invention.

[0017]

Examples 1 to 5, Comparative Examples (a) Adjustment of Adhesive A reactor equipped with a stirrer, a thermometer and a dropping funnel was charged with water and PVA, respectively, and the charged substances were stirred to obtain PVA.
Was dispersed in water. Then, the dispersion was heated to a temperature of 95 ° C. and kept at the same temperature for 1 hour. Next, the dispersion is heated to a temperature of 70.
After cooling to 0 ° C., vinyl acetate and a polymerization initiator (hydrogen peroxide and tartaric acid) were added to this dispersion to carry out initial polymerization. Then, vinyl acetate and a polymerization initiator were added dropwise, and after completion of the addition, the reaction solution was aged for 1 hour. Thus, an aqueous emulsion adhesive (comparative example) was obtained.

Next, the resin content 10 of this aqueous emulsion was used.
Acrylic emulsion (trade name: S
UMIKA FLEX CA-376 (manufactured by Sumitomo Chemical Co., Ltd., glass transition temperature: 70 ° C.) was blended in the proportions shown in Table 1 in terms of resin content to obtain adhesives (Examples 1 to 5) made of an aqueous emulsion. (B) Performance evaluation The performance of the obtained adhesive was evaluated by the following method.

Measurement of Elastic Modulus of Adhesive Film Adhesive is applied to a polyethylene plate to be adhered, and a coating layer is applied.
Cured for 3 days at 0 ° C and relative humidity 65% RH, 300 ~ 5
A 00 μm film was formed, and the dry film was punched out with a No. 1 dumbbell to prepare a test piece. This test piece was set in a tensile tester and pulled at a pulling speed of 10 mm / min.
The elastic modulus was calculated from the tensile strength of 70% of the maximum strength and the elongation at this time. The results are shown in Table 1.

Measurement of Initial Adhesion Strength A base paper for a class B paper tube manufactured by Sakura Paper Tube Co., Ltd. was cut into a size of 25 mm × 50 mm to prepare two test pieces, and one of the test papers had an application amount of 0.05 g / (25 mm) ² was coated with an adhesive, which was immediately laminated on the other test paper in a staggered manner, and both were pressed with a 1 kg weight for 40 seconds.

Then, the pressure was released, and these test pieces were immediately set in a tensile tester and pulled in the shearing direction at a pulling speed of 10 mm / min to measure the tensile strength.
The results are shown in Table 1.

Measurement of Water Resistance The above-mentioned test pieces were prepared, adhered in the same manner as described above, and both were pressed with a 1 kg weight for 1 minute.

Thereafter, the pressure is released, and these test pieces are placed in
It was aged at 0 ° C. and 65% RH for 1 day. Next, this test piece was set by hanging a 50 g weight in warm water at a temperature of 50 ° C., and the drop time until the bonded surface was peeled off and dropped. The results are shown in Table 1.

[0024]

[Table 1]

As is clear from Table 1, the adhesive prepared by mixing the vinyl acetate resin emulsion with the specified amount of the acrylic emulsion of the present invention has a film having a higher elastic modulus than the vinyl acetate homopolymer emulsion. Forming,
From the viewpoint of initial adhesive strength, it is recognized that the adhesive is comparable to conventionally used adhesives and has excellent water resistance.

[0026]

As described above, according to the present invention, by the action of the acrylic emulsion, a high elastic modulus can be imparted to the film formed by applying the adhesive to the adherend, and excellent initial adhesion can be achieved. Since the property is obtained and excellent water resistance is obtained, it is possible to obtain an adhesive having satisfactory initial adhesiveness, film elastic modulus and water resistance.

Claims (1)

[Claims] 1. A glass transition temperature of 50 to 100 ° C. with respect to 100 parts by weight of a resin content of a vinyl acetate resin emulsion.
Acrylic emulsion of 10 to 70 in terms of resin
An adhesive composition, characterized in that it comprises one part by weight.