JP2000212534A - Pressure-sensitive acrylic adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive acrylic adhesive composition having an adhesive performance excellent in both adhesivity and peeling resistance at an ordinary temperature and at a high temperature. SOLUTION: This pressure-sensitive acrylic adhesive composition comprises an acrylic polymer and a tackifier. Therein, the tackifier is a high mol.wt. terpene phenolic resin which is obtained by reacting a terpene phenol resin with a cross-linking agent and has a softening point of 150-200 deg.C.

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 composition having excellent adhesive strength at room temperature to high temperature and excellent peeling resistance.

[0002]

2. Description of the Related Art Acrylic pressure-sensitive adhesive compositions containing an acrylic polymer as a main component are used for labels, adhesive tapes, double-sided adhesive tapes and the like. However, in general, the acrylic pressure-sensitive adhesive composition does not have sufficient adhesive strength and peel resistance as compared with other pressure-sensitive adhesive compositions.
Further, acrylic pressure-sensitive adhesive compositions generally have a
In a high-temperature region of 100 ° C. or higher than 50 ° C., there is a disadvantage that sufficient adhesive strength and peel resistance cannot be obtained. Therefore, in order to improve the adhesive strength of the acrylic pressure-sensitive adhesive composition, a tackifier resin such as a rosin ester, a terpene resin (particularly, a terpene phenol resin), or a C9 petroleum resin has been blended.

[0003] However, even when these tackifying resins are blended, the adhesive strength and peeling resistance at room temperature are improved. However, in a high temperature range of about 50 to 100 ° C, the adhesive strength and peeling resistance are rather increased with increasing temperature. However, these tackifying resins have a problem that the adhesive strength and the peeling resistance in a high temperature range are reduced.

Further, attempts have been made to increase the amount of a cross-linking agent used, increase the cross-linking density of the acrylic polymer, modify the acrylic polymer, and increase the adhesive strength at high temperatures. Although the adhesive force at high temperature is improved, there is a disadvantage that the adhesive force at normal temperature is reduced, and the acrylic pressure-sensitive adhesive composition excellent in both normal temperature and high temperature adhesive force is:
Not yet developed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic pressure-sensitive adhesive composition having excellent adhesive properties at room and high temperatures and excellent peeling resistance.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a specific tackifying resin is used as the tackifying resin to be blended with the acrylic copolymer. It has been found that this problem can be solved.

That is, the present invention provides an acrylic pressure-sensitive adhesive composition containing an acrylic polymer and a tackifying resin, wherein the tackifying resin is obtained by reacting a terpene phenol resin with a crosslinking agent; The present invention also relates to an acrylic pressure-sensitive adhesive composition characterized by being a high molecular weight terpene phenol resin having a softening point of more than 150 ° C. and 200 ° C. or less.

[0008] As the acrylic polymer as the base polymer of the present invention, a known acrylic polymer can be used. As the monomer used for the acrylic polymer,
Ethyl acrylate, butyl acrylate, octyl acrylate (or more adhesive component), methyl, C1-C2 alkyl ester of ethyl acrylate, C2-C8 alkyl methacrylate, vinyl acetate, propionic acid, acrylonitrile, styrene, vinylidene chloride (or more aggregate component) Acrylic acid, maleic anhydride, acrylamide, hydroxyl group-containing monomer, acrylonitrile (the above-mentioned modifying component) and the like.

The glass transition temperature of these acrylic polymers is not particularly limited, but is preferably -80 to -10 ° C. When the glass transition temperature is higher than −10 ° C., the tack tends to decrease, and when the glass transition temperature is lower than −80 ° C., the adhesive strength tends to decrease.

The method for producing the acrylic polymer is as follows.
It is based on a known polymerization method such as a bulk polymerization method, a solution polymerization method, and a suspension polymerization method. As the radical initiator for these radical polymerizations, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 85 ° C, and the reaction time is about 1 to 8 hours. In addition, a polar solvent such as ethyl acetate is generally used as a solvent for the acrylic polymer. The solution concentration is usually about 40 to 60%.

Commercially available products include "Nissetsu" manufactured by Nippon Carbide Industry Co., Ltd., "Olivine" manufactured by Toyo Ink Mfg. Co., Ltd., "Sibinol" manufactured by Saiden Chemical Co., Ltd., and "SK Dyne" manufactured by Soken Chemical Co., Ltd. "Ace Reset" manufactured by Nippon Shokubai Co., Ltd., "Vinesol" manufactured by Sharp Fat & Oil Co., Ltd., "Arontack" manufactured by Toagosei Co., Ltd., and the like.

As the tackifier resin of the present invention, a high molecular weight terpene phenol resin obtained by reacting a terpene phenol resin with a crosslinking agent and having a softening point of 150 to 200 ° C. is used. For the softening point,
The temperature is more preferably 160 to 180 ° C. Softening point is 15
If the temperature is lower than 0 ° C., the high-temperature adhesive strength of the acrylic pressure-sensitive adhesive decreases. When the softening point exceeds 200 ° C., the room temperature tack of the acrylic pressure-sensitive adhesive decreases.

Here, the terpene phenol resin is a terpene compound and a phenol that are cationically polymerized under a Friedel-Crafts catalyst.

The terpene compound which is one of the raw materials of the terpene phenol resin will be described. Terpene compounds are generally polymers of isoprene (C5H8), such as monoterpenes (C10H16) and sesquiterpenes (C15H2).
4) and diterpenes (C20H32). Terpene compounds are compounds having these as the basic skeleton. Among them, in the present invention, a monoterpene is preferably used. As specific examples of these terpene compounds,
For example, the following may be mentioned, but the present invention is not limited to these.

Examples of terpene compounds include myrcene, allocymene, ocimene, α-pinene, β-pinene, dipentene, limonene, α-pherandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4 -Cineol, α-terpineol, β-terpineol, γ-terpineol, camphene, tricyclene, sabinene, paramentadienes, currens and the like. Among these compounds, α-pinene, β
-Pinene, limonene, myrcene, allocymene, α-terpinene are particularly preferably used in the present invention.

Examples of phenols include phenol, cresol, xylenol, catechol, resorcin, hydroquinone, bisphenol A and the like.

Examples of commercially available terpene phenol resins include Polystar series and Mighty Ace series manufactured by Yasuhara Chemical Co., Ltd.

As the cross-linking agent, hexamethylenetetramine, trioxane, etc., which are used for increasing the molecular weight of ordinary phenol resins and the like, can be used in consideration of the OH value of the terpene phenol resin and the softening point of the obtained resin.

The high molecular weight terpene phenolic resin of the present invention is prepared in the same manner as in the ordinary crosslinking reaction of a phenolic resin, and the terpene phenolic resin and the crosslinking agent are reacted at 200 to 240 ° C. for about 30 to 120 minutes. It can be obtained by melting and stirring.

The compounding ratio of the acrylic pressure-sensitive adhesive composition of the present invention is preferably such that 2 to 80 parts by weight of the tackifier resin of the present invention is mixed with 100 parts by weight of the acrylic polymer. It is particularly preferably 10 to 60 parts by weight of the tackifier resin of the present invention based on 100 parts by weight of the acrylic polymer. If the amount of the tackifier resin is less than 2 parts by weight, it is not possible to provide a sufficient high-temperature adhesive force. If it exceeds 80 parts by weight, the adhesive strength is reduced and the tack is also reduced.

The acrylic pressure-sensitive adhesive composition of the present invention can improve cohesive strength and heat resistance by further adding a crosslinking agent to the acrylic polymer and the tackifier resin. Examples of the crosslinking agent include a polyisocyanate compound, a polyamine compound, an epoxy resin, and a urea resin. Preferably, it is a polyisocyanate compound. Specific examples include 1,6-hexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate, and tetramethylene diisocyanate.

Further, as the acrylic pressure-sensitive adhesive composition of the present invention, an antioxidant, a filler, an ultraviolet absorber and the like may be used as needed. Further, a known tackifier resin different from the tackifier resin of the present invention may be used in combination.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to production examples, examples and comparative examples. In each example, all parts and percentages are by weight unless otherwise specified.

Production Example A (Production of High Molecular Weight Compound of Terpene Phenol Resin) A terpene phenol resin (Yasuhara Chemical Co., Ltd.) was placed in a reactor equipped with a stirrer, a cooling pipe, and a nitrogen inlet pipe.
Polystar T-145), 100 parts, and hexamethylenetetramine 0.5 part, and 240 ° C. under a nitrogen gas stream.
And reacted at the same temperature for 1 hour. The obtained resin had a softening point of 161 ° C., an OH value of 60, and a color tone (Gardner) of 8.

Production B to Production D (Production of High Molecular Weight Compound of Terpene Phenol Resin) The same reaction was carried out from Production B to Production D while changing the charged amounts of the terpene phenol resin and hexamethylenetetramine as shown in Table 1. Was. The obtained physical property values were as shown in Table 1.

[0026]

[Table 1]

Example 1 100 parts of an acrylic polymer (manufactured by Yushi Yushi Kogyo KK, trade name “Vinsol AS2050”, solid content conversion) and 40 parts of a high molecular weight terpene phenol resin obtained in Production Example A were used. After sufficient kneading, a polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane Co., Ltd.)
3 parts were added to obtain an acrylic pressure-sensitive adhesive composition. The obtained acrylic pressure-sensitive adhesive composition was applied to a 38 μm-thick polyester film using an applicator so that the dry film thickness became about 50 μm, and then the solvent in the adhesive composition was removed. And a tape having a paste thickness of 50 μm was prepared, and various tests were conducted. The test method is as follows.
The performance evaluation results are as shown in Table 2. Here, the performance evaluation method will be described. Performance test of tape The tape obtained in Example 1 was allowed to stand at 50 ° C for 5 days, aged, and then evaluated for performance by the following test method. Tack: J. T. described in JIS-Z-0237. The measurement was performed by the DOW method under the conditions of an inclination angle of 30 ° and a measurement temperature of 23 ° C. Room temperature adhesive strength: obtained tape (25 mm x 200 mm)
Is adhered to a polypropylene plate, and 180 at a temperature of 23 ° C. and 300 mm / min is measured using a tensile tester.
The peel strength (g / 25 mm) was measured. High temperature adhesive strength: obtained tape (25 mm x 200 mm)
Is adhered to a polypropylene plate, and 180 at a temperature of 60 ° C. and 300 mm / min is measured using a tensile tester.
The peel strength (g / 25 mm) was measured. Cohesive force: The obtained tape (25 mm × 25 mm) was affixed to a stainless steel plate, loaded with 1 kg at 40 ° C., and the time required for falling was measured. Peeling resistance: The obtained tape (10 mm × 50 mm) was affixed to a polypropylene plate, and a load of 100 g was applied in a direction perpendicular to the polypropylene plate at 60 ° C., and the time until the tape dropped was measured.

Examples 2 to 4 In the same manner as in Example 1, the amounts of the acrylic polymer (manufactured by YAS Co., Ltd., trade name “Vinesol AS2050”, in terms of solid content) and the amount of tackifying resin are shown in Table. The same procedure as in Example 1 was carried out except that Example 2 was repeated, and various bridge-type acrylic pressure-sensitive adhesive compositions were obtained. Evaluation was performed in the same manner as in Example 1 using the obtained crosslinked acrylic pressure-sensitive adhesive group. The evaluation results are as shown in Table 2.

Comparative Examples 1 and 2 In the same manner as in Example 1, the amounts of the acrylic polymer (manufactured by Yushi Kogyo Co., Ltd., trade name "Vinesol AS2050", in terms of solid content) and the amount of tackifier resin are shown in Table 1. In the same manner as in Example 1 except that the composition was changed as in Example 2, various crosslinked acrylic pressure-sensitive adhesive compositions were obtained. Evaluation was performed in the same manner as in Example 1 using the obtained crosslinked acrylic pressure-sensitive adhesive group. The evaluation results are as shown in Table 2.

[0030]

[Table 2]

[0031]

Industrial Applicability The acrylic pressure-sensitive adhesive composition of the present invention has excellent adhesion and peeling resistance in the range from room temperature to high temperature, especially to polyolefins such as polypropylene and polyethylene. It is also suitable for use in applications such as labels, sheets, adhesive tapes, etc., which are exposed to high temperatures, such as car bodies. Recently, demand for polypropylene and polyethylene has been growing in connection with environmental problems such as polyvinyl chloride, and the use of the acrylic pressure-sensitive adhesive composition of the present invention is expected to expand.

Claims (2)

[Claims] 1. A high molecular weight terpene phenol resin obtained by reacting (A) an acrylic polymer and (B) a terpene phenol resin with a crosslinking agent and having a softening point of 150 to 200 ° C. (A), (B) of tackifying resin
An acrylic pressure-sensitive adhesive composition comprising, as an essential component, 2. The amount of the acrylic polymer (A) is 100 parts by weight, and the amount of the tackifier resin (B) is 2 parts by weight.
The acrylic pressure-sensitive adhesive composition according to claim 1, wherein the amount is from 80 to 80 parts by weight.