JPH07102229A - Adhesive composition - Google Patents

Abstract

(57) [Summary] [Purpose] An adhesive that has excellent adhesion (heat resistance) to base materials at high temperatures, good bonding at low temperatures, and excellent adhesion to adherends made of olefin resins. A composition is provided. [Structure] Adhesive containing 40 to 95% by weight of an acrylic copolymer mainly composed of an alkyl ester of (meth) acrylic acid having an alkyl group having 2 to 18 carbon atoms, and three kinds of resins having different softening points. A pressure-sensitive adhesive composition containing 5 to 60% by weight of the applied resin. 5-60% by weight of this tackifying resin
The composition is 1 to 20% by weight of a rosin ester resin or an alkylphenol-modified xylene formaldehyde resin having a softening point of 150 ° C. or higher, 2 to 20% by weight of a rosin ester resin having a softening point of 100 to less than 150 ° C., and a softening point of 100.
It is 2 to 20% by weight of a rosin ester resin at a temperature lower than 0 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive composition having excellent pressure-sensitive adhesive properties in a wide temperature range and pressure-sensitive adhesive force to an adherend made of an olefin resin which is difficult to adhere to. The present invention relates to a pressure-sensitive adhesive composition used for applications such as household electric appliances, cushioning materials for automobiles, and gap tapes, and for processing the surface of urethane foam tapes used with expanded applications.

[0002]

2. Description of the Related Art Solvent-based pressure-sensitive adhesives composed mainly of acrylic resin have been used conventionally because of their excellent weather resistance, durability, heat resistance, cold resistance and the like. In addition, recently, as the use of tapes has expanded, there has been an increasing demand for pressure-sensitive adhesives with a better balance between higher heat resistance and other physical properties (adhesive strength to adherends made of olefin resin, initial tack, etc.). There is. However, in order to increase the heat resistance of the pressure-sensitive adhesive, it is possible to use a polar group-containing monomer and / or a monomer that produces high cohesive force in large amounts, and increase the amount of the curing agent added. However, other physical properties are deteriorated, which is not preferable.

[0003] In recent years, due to improvements in heat resistance required properties and expansion of types of adherends in the market, heat resistance, bondability at low temperature, adhesion to adherends made of olefinic resin, initial tack It is becoming difficult to satisfy such requirements at the same time. In particular, due to the expansion of the types of polyolefin-based adherends that are difficult to adhere to, adhesive performance under high temperature environments has been required.

As a solution to these problems, Japanese Patent Laid-Open Nos. 4-114079, 4-110376, 4-161477, and 4-202 are known.
No. 391, etc.

For example, in JP-A-4-114079, a rosin-based tackifying resin having a high softening point (110 to 190 ° C.) is blended with a copolymer of acrylic acid ester and rosin acrylic acid ester. Discloses that an adhesive having excellent adhesiveness to a nonpolar adherend and adhesiveness in a wide temperature range can be obtained. Japanese Patent Laid-Open No. 4-11
Japanese Patent No. 0376 discloses that by admixing an unsaturated rosin ester with a specific copolymer, the adhesive force to an adherend made of a polyolefin resin, the holding power at high temperature,
It is disclosed that a pressure-sensitive adhesive having excellent curved surface repulsion resistance can be obtained. JP-A-4-161477 discloses that a similar pressure-sensitive adhesive can be obtained by combining an acrylic copolymer, a vinyl acetate polymer, a modified cyclopentadiene resin and an aziridine curing agent. Japanese Patent Application Laid-Open No. 4-202391 discloses a method of adding an alkylphenol-based tackifying resin to a specific acrylic copolymer.

[0006] These solutions are commonly characterized by adding one kind of tackifying resin.

[0007]

However, with the means disclosed in the above publication, it is difficult to widen the temperature range in which stable tackiness is exhibited. For example, when the tackiness at high temperature is emphasized, the ball tack is reduced, and when the adhesive is made at low temperature, zipper peeling occurs.

The object of the present invention is to solve the above-mentioned problems in conventional adhesives for processing urethane foam, and particularly to improve the adhesion (heat resistance) to a base material (for example, urethane) at a high temperature (about 100 ° C.). An object of the present invention is to provide a pressure-sensitive adhesive composition which is excellent in bonding at low temperature (5 ° C. or lower) and has excellent adhesive strength to an adherend made of an olefin resin.

[0009]

In order to achieve such an object, the pressure-sensitive adhesive composition of the present invention comprises an alkyl ester of (meth) acrylic acid having an alkyl group having 2 to 18 carbon atoms as a main component. Acrylic copolymer 40 to 95% by weight,
And 5 to 60% by weight of a tackifying resin containing three types of rosin ester resins having different softening points, and the composition of the three types of rosin ester resin of 5 to 60% by weight of the tackifying resin has a softening point of Is 1 to 20% by weight of a high softening point rosin ester resin having a softening point of 100 to 150 ° C. or higher.
2 to 20% by weight of medium softening point rosin ester resin below ℃,
And a low softening point rosin ester resin having a softening point of less than 100 ° C. of 2 to 20% by weight.

The pressure-sensitive adhesive composition of the present invention also comprises 40 to 95% by weight of an acrylic copolymer mainly composed of an alkyl ester of (meth) acrylic acid whose alkyl group has 2 to 18 carbon atoms, and a softening point. Three different types of tackifying resins 5
The composition of the tackifying resin is 5 to 60% by weight and the softening point is 1 to 20% by weight of the alkylphenol-modified xylene formaldehyde resin having a softening point of 150 ° C. or higher, and the softening point is 100 to less than 150 ° C. The softening point rosin ester resin is 2 to 20% by weight, and the low softening point rosin ester resin is 2 to 20% by weight.

A detailed description of these is as follows.

In the present specification, (meth) acrylic acid means acrylic acid and / or methacrylic acid.

The acrylic copolymer used in the pressure-sensitive adhesive composition of the present invention is obtained by polymerizing an alkyl ester of (meth) acrylic acid as a main component. Examples of the alkyl ester of (meth) acrylic acid include (meth)
Examples thereof include ethyl acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.
The alkyl group having 2 to 18 carbon atoms is used from the viewpoint of the tackiness of the obtained pressure-sensitive adhesive composition.

In order to increase the heat resistance of the obtained pressure-sensitive adhesive composition, it is preferable to copolymerize a polar group-containing monomer and a monomer which produces a high cohesive force with the (meth) acrylic acid ester. Examples of the polar group-containing monomer include carboxylic acids having an ethylenic double bond such as (meth) acrylic acid and acrylic acid esters having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, and high cohesive force. Examples of the monomer that generates (meth) acrylate include methyl (meth) acrylate, vinyl acetate, and styrene.

The rosin ester resin of the tackifying resin used in the pressure-sensitive adhesive composition of the present invention includes rosin esters such as diethylene glycol, glycerin and pentaerythritol, and their derivatives, partially disproportionated or disproportionated rosin. Examples thereof include esters, hydrogenated rosin esters, maleic acid-modified rosin esters, polymerized rosin esters, and formaldehyde-modified rosin esters.

In the present invention, as these tackifying resins, three kinds of resins having different softening points are used in combination. This makes it possible to extend the temperature range in which stable tackiness is exhibited.

In the invention of claim 1, as the high softening point resin having a softening point of 150 ° C. or higher, a polymerized rosin ester or a phenol-modified rosin resin is preferably used. As the medium softening point resin having a softening point of 100 ° C. to less than 150 ° C., rosin esters or hydrogenated rosin esters are preferably used. As the low softening point resin having a softening point of less than 100 ° C., rosin esters or hydrogenated rosin esters are preferably used.

In the invention of claim 2, as the high softening point resin having a softening point of 150 ° C. or higher, an alkylphenol-modified xylene formaldehyde resin is preferably used. As the medium softening point resin having a softening point of 100 ° C. to less than 150 ° C., rosin esters or hydrogenated rosin esters are preferably used. As the low softening point resin having a softening point of less than 100 ° C., rosin esters or hydrogenated rosin esters are preferably used.

The pressure-sensitive adhesive composition of the present invention may contain a tackifying resin other than those mentioned above to the extent that performance is not impaired. A xylene resin is preferably used as the tackifying resin other than the above-mentioned resins. Examples of the xylene resin include a xylene formaldehyde resin modified with a bifunctional phenol.

The pressure-sensitive adhesive composition of the present invention can be obtained by mixing the above acrylic copolymer and the above tackifying resin by a conventional method.

The pressure-sensitive adhesive composition of the present invention comprises 40 to 95% by weight of the acrylic copolymer, and the tackifying resin 5 described above.
It is contained in a proportion of ˜60% by weight. When the content of the tackifying resin is less than 5% by weight, the adhesive strength becomes poor and
When the content is more than weight%, the bondability at low temperature becomes poor.

The composition of the tackifying resin of 5 to 60% by weight has a high softening point resin of 1 to 20% by weight and an intermediate softening point resin of 2 to 2%.
0 wt% and low softening point resin 2 to 20 wt%,
Preferably, 1 to 10% by weight of high softening point resin, 10 to 20% by weight of medium softening point resin, and 10 to 20% by weight of low softening point resin are used. When the content of the high softening point resin is less than 1% by weight, the heat resistance is lowered, and when it exceeds 20% by weight, the bonding property at low temperature is deteriorated. When the content of the medium softening point resin is less than 2% by weight, the adhesive strength is lowered, and when it exceeds 20% by weight, the laminating property is deteriorated. When the content of the low softening point resin is less than 2% by weight, the bondability at low temperature becomes poor, and when it exceeds 20% by weight, the heat resistance decreases.

A curing agent is preferably added to the pressure-sensitive adhesive composition according to the present invention in order to improve heat resistance. As such a curing agent, for example, an isocyanate compound, an epoxy compound, an organic metal complex, an aziridine compound or the like is used. Usually, an isocyanate compound is preferably used as a curing agent. In this case, the curing agent is added in an amount of 0.2 to 100 parts by weight of the pressure-sensitive adhesive composition so that the obtained pressure-sensitive adhesive composition has excellent balance of pressure-sensitive adhesive properties and the like.
It is preferably used in the range of 5 parts by weight.

The pressure-sensitive adhesive composition obtained in the present invention is used, for example, for producing a urethane foam tape. Such urethane foam tape is suitably used for applications such as building materials, household electric appliances, automobile cushioning materials, gap tapes, etc., and can be used for expanding tape applications.

[0025]

EXAMPLES The present invention will be described below based on examples.

(Example 1) In a four-necked flask equipped with a cooling tube, the monomers were charged in the proportions shown in Table 1 below, and then 81.8 parts by weight of ethyl acetate were charged and the temperature was raised for 30 minutes. After refluxing, 0.1 part by weight of benzol peroxide was added dropwise and the reaction was carried out for 7 hours. Then, 0.1 part by weight of benzol peroxide was further added dropwise and the reaction was carried out for 3 hours. Next, 40.4 parts by weight of toluene was added thereto and cooled to obtain a viscous transparent acrylic copolymer solution.

The acrylic copolymer and the tackifying resin were mixed in the proportions shown in Table 2 below, and then an isocyanate compound was added as a curing agent and mixed to obtain a pressure sensitive adhesive composition.

The pressure-sensitive adhesive composition thus obtained was coated on a release paper with a doctor blade to a thickness of 145 μm (wet resin). Then, it was dried in a dryer at 80 ° C. for 2 minutes.
Next, an ether-based urethane foam sheet having a thickness of 10 mm and a specific gravity of 0.02 was pressure-bonded with a roll to produce a urethane foam tape. This urethane foam tape was aged in a thermostatic chamber at a temperature of 20 ° C. and a humidity of 65% for 10 days.

Using the urethane foam tape thus obtained, the following four physical properties were measured.

(1) Curved surface adhesiveness: Two urethane foam tapes having a width of 25 mm and a length of 80 mm are placed on a 50φ iron rod.
The roll of kg is reciprocated once to bond and the temperature is 20 ° C.
After left for 1 hour at a humidity of 65%, left for 4 hours in a gear oven at 100 ° C. After cooling, the distance at which the ends of the urethane foam tape peel off is measured.

(2) Heat-resistant holding power; stainless steel plate (SU
A urethane foam tape having a width of 50 mm and a length of 120 mm is attached to (S-304), and a 2 kg roll is reciprocated once to adhere. After curing for 17 hours at a temperature of 20 ° C and a humidity of 65%, leave it in a 100 ° C gear oven for 20 minutes,
A static load of 100 g is applied with the tape surface facing down (angle is 90 ° with respect to the stainless steel plate). After being left for 1 hour, the time until the tape falls from the steel plate or the distance peeled from the steel plate is measured.

(3) PP adhesive strength; polypropylene (P
P) A urethane foam tape having a width of 25 mm and a length of 200 mm is attached to the plate, and a 2 kg roll is reciprocated once on the urethane foam tape to adhere the tape. After standing at a temperature of 5 ° C. for 20 minutes, the 90 ° peel strength is measured with a tensile tester. The pulling speed is 300 mm / min.

(4) Initial tack (probe tack): A urethane foam tape having a width of 25 mm and a length of 100 mm is pasted on a stainless steel plate with rubber glue. After adhering the bottom surface of the probe (stainless steel net having a bottom area of 1 cm ² and a weight of 10 g) to the glue surface for 3 seconds, a pulling speed of 200
The strength when pulled up at mm / min is measured.

(Examples 2 to 6) Acrylic copolymer solutions were obtained in the same manner as in Example 1 except that the kinds and blending ratios of the monomers were changed as shown in Table 1.

Next, the acrylic copolymer and the tackifying resin were mixed in the proportions shown in Table 2 to obtain a pressure sensitive adhesive composition. Using the obtained pressure-sensitive adhesive composition, a urethane foam tape was produced in the same manner as in Example 1, and each physical property was measured in the same manner as in Example 1.

(Comparative Examples 1 to 5) Acrylic copolymer solutions were obtained in the same manner as in Example 1 except that the kinds and blending ratios of the monomers were changed as shown in Table 1.

Next, the acrylic copolymer and the tackifying resin were mixed in the proportions shown in Table 2 to obtain a pressure sensitive adhesive composition. Using the obtained pressure-sensitive adhesive composition, a urethane foam tape was produced in the same manner as in Example 1, and each physical property was measured in the same manner as in Example 1.

(Examples 7 to 12) Acrylic copolymer solutions were obtained in the same manner as in Example 1 except that the kinds and blending ratios of the monomers were changed as shown in Table 1.

Next, the acrylic copolymer and the tackifying resin were mixed in the proportions shown in Table 3 to obtain a pressure sensitive adhesive composition. Using the obtained pressure-sensitive adhesive composition, a urethane foam tape was produced in the same manner as in Example 1, and each physical property was measured in the same manner as in Example 1.

(Comparative Examples 6 to 10) An acrylic copolymer solution was obtained in the same manner as in Example 1 except that the kinds and blending ratios of the monomers were changed as shown in Table 1.

Next, the acrylic copolymer and the tackifying resin were mixed in the proportions shown in Table 3 to obtain a pressure sensitive adhesive composition. Using the obtained pressure-sensitive adhesive composition, a urethane foam tape was produced in the same manner as in Example 1, and each physical property was measured in the same manner as in Example 1.

The types and blending ratios of the monomers used in the synthesis of the acrylic copolymers used in the above Examples and Comparative Examples are shown in Table 1 below.

[0043]

[Table 1]

The types of tackifying resins used in the pressure-sensitive adhesive compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 5 of the present invention, and the mixing ratio of the acrylic copolymer and each component of the tackifying resin. , And the evaluation of the urethane foam tape produced here are shown in Table 2 below.

[0045]

[Table 2]

Examples 7 to 12 of the present invention and Comparative Examples 6 to 10
The type of tackifying resin used in the pressure-sensitive adhesive composition obtained in 1., the mixing ratio of each component of the acrylic copolymer and the tackifying resin, and the evaluation of the urethane foam tape prepared here are shown in Table 3 below. Shown in.

[0047]

[Table 3]

The tackifying resins and curing agents in Tables 2 and 3 will be described below.

As the high softening point resin, in Examples 1 to 6 and Comparative Examples 1 to 5, phenol-modified rosin ester resin Tamanoru 810 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 185 ° C.) or polymerized rosin was used. Pencel D-160 which is an ester resin (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 16
0 ° C.), in Examples 7 to 12 and Comparative Examples 6 to 10, Nikanol GHP-160 (manufactured by Mitsubishi Gas Chemical Co., Inc., softening point 160 ° C.) or Nikanol HP-1 which is an alkylphenol-modified xylene formaldehyde resin.
50 (manufactured by Mitsubishi Gas Chemical Co., Inc., softening point 150 ° C.) was used.

As the medium softening point resin, super ester A115 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 115 ° C.) which is a disproportionated rosin ester resin, super ester A1
25 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 125 ° C.) or Harrier Star DS110S (manufactured by Harima Kasei Co., Ltd., softening point 110 ° C.) was used.

As the low softening point resin, super ester A-75 (manufactured by Arakawa Chemical Industry Co., Ltd., softening point 75 ° C.) which is a disproportionated rosin ester resin or Harrier Star DS is used.
90SL (manufactured by Harima Kasei Co., Ltd., softening point 90 ° C), or ester gum H (hydrogenated rosin ester resin, manufactured by Arakawa Chemical Industry Co., Ltd., softening point 70 ° C) or ester gum HP (Arakawa Chemical Industry Co., Ltd.) ), A softening point of 80 ° C.) was used.

An isocyanate compound, Coronate L (75% active ingredient, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used as a curing agent.

From Tables 2 and 3, the pressure-sensitive adhesive composition of the present invention is superior to the pressure-sensitive adhesive compositions of Comparative Examples in pressure-sensitive adhesive properties over a wide temperature range and pressure-sensitive adhesive force to an adherend composed of an olefin resin. You can see that

[0054]

EFFECTS OF THE INVENTION Since the pressure-sensitive adhesive composition of the present invention contains a tackifying resin containing three kinds of resins having different softening points as an essential component, the adhesion (heat resistance) to a substrate such as urethane foam at high temperature is improved. The adhesiveness is improved, the initial tack is good, the bonding at low temperature is excellent, and the adhesive strength to an adherend made of an olefin resin is excellent.

Claims (2)

[Claims] 1. A 40 to 95% by weight acrylic copolymer mainly composed of an alkyl ester of (meth) acrylic acid having an alkyl group having 2 to 18 carbon atoms, and three kinds of rosin ester resins having different softening points. A tackifying resin composition containing 5 to 60% by weight of a tackifying resin, wherein the composition of 5 to 60% by weight of the tackifying resin has a softening point of 15
High softening point rosin ester resin having a softening point of 0 ° C. or more, 1 to 20% by weight, medium softening point rosin ester resin having a softening point of 100 to less than 150 ° C., 2 to 20% by weight, and low softening point rosin ester having a softening point of less than 100 ° C. A pressure-sensitive adhesive composition comprising 2 to 20% by weight of a resin. 2. An acrylic copolymer mainly composed of an alkyl ester of (meth) acrylic acid having an alkyl group having 2 to 18 carbon atoms, and 40 to 95% by weight of the acrylic copolymer and 5 to 60% by weight of three kinds of tackifying resins. % Of the tackifying resin having a softening point of 15%.
High softening point above 0 ° C. Alkylphenol-modified xylene formaldehyde resin 1 to 20% by weight, softening point 100 to
A medium-softening point rosin ester resin having a softening point of 2 to 20% by weight and a low softening point rosin ester resin having a softening point of less than 100 ° C are 2 to 20% by weight, respectively, and a pressure-sensitive adhesive composition.