JPH08157787A - Double-faced pressure-sensitive adhesive tape - Google Patents

Abstract

PURPOSE: To prepare a double-faced pressure-sensitive adhesive tape excellent in the tight adhesion to a urethane foam at low temps. CONSTITUTION: In this double-faced pressure-sensitive adhesive tape having pressure-sensitive adhesive layers contg. an acrylic polymer and a tackifier resin having hydroxyl groups, the hydroxyl no, of the tackifier resin is from 3.5 to less than 4.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an acrylic polymer,
The present invention relates to a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a tackifying resin having a hydroxyl group, and more particularly to a double-sided pressure-sensitive adhesive tape having excellent adhesion to urethane foam at low temperatures.

[0002]

2. Description of the Related Art A double-sided pressure-sensitive adhesive tape is formed by laminating pressure-sensitive adhesive layers on both sides of a base material, and the pressure-sensitive adhesive layer is generally composed of an acrylic polymer alone, an acrylic polymer and an acrylic polymer. It is roughly classified into two types, that is, a combination with a tackifying resin. In particular, the latter is useful because it has excellent heat resistance from recent market demands.

When an acrylic polymer and a tackifying resin are mixed to form a pressure-sensitive adhesive layer, the polarity of the acrylic polymer and the solvent used for preparing the acrylic polymer by solution polymerization (generally, In terms of compatibility with rosin, rosin-based resins and terpene-phenolic resins are mainly used as tackifier resins, and rosin-based resins are especially used in terms of price and stability over time. Ester resin is used.

That is, the rosin-based resin has abietic acid as a main component, but various measures are taken because it is severely deteriorated by heat and light. For example, JP-A-3-281 is used.
In Japanese Patent No. 587, an esterified tackifying resin is used in an acrylic pressure-sensitive adhesive composition.

However, since the esterified tackifying resin has a hydroxyl group that does not contribute to the reaction, this reacts with the isocyanate which is often used as a curing agent for the acrylic polymer. Since the hydroxyl value of the tackifying resin is not constant, various adhesive physical properties are changed.

Further, in the double-sided pressure-sensitive adhesive tape using a pressure-sensitive adhesive layer composed of a combination of the above-mentioned acrylic polymer and tackifying resin, the adhesive strength to various adherends is improved, but the adhesion is generally low temperature. Inferior in sex. For example, in the adhesion of urethane foam, which is often used for adhesion and fixation of automobile interior materials, adhesion and fixing work at low temperature with a so-called converter (bonding and fixing of urethane foam and polypropylene or other molded products or urethane foam and various metals) ), It is desired to improve the adhesive strength with urethane foam at low temperatures.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to use a pressure-sensitive adhesive layer composed of a combination of an acrylic polymer and a tackifying resin. Another object of the present invention is to provide a double-sided pressure-sensitive adhesive tape having improved adhesive strength with urethane foam at low temperatures.

[0008]

The double-sided pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing an acrylic polymer and a tackifying resin having a hydroxyl group. Hydroxyl number derived from resin is 3.5
It is characterized by being 4 or more and less than 4, whereby the above object is achieved.

The composition of the acrylic polymer (base) used in the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, and for example, a homopolymer or copolymer containing (meth) acrylic acid ester as a main component is used. can do.

Specific examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Further, as the crosslinkable monomer, (meth) acrylic acid, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide and the like can be used in combination.

Further, if necessary, other copolymerizable monomers such as vinyl acetate and styrene may be used in combination to the extent that the adhesive property of the (meth) acrylic acid ester (co) polymer is not impaired. it can.

Acrylic polymers are prepared by dissolving the above-mentioned (meth) acrylic acid ester alone or in combination with other copolymerizable monomers in a solvent such as ethyl acetate to prepare an azo-based polymer.
Heating by adding various known polymerization initiators of peroxide type,
It can be easily produced by a so-called solution polymerization method. It can also be produced by other polymerization methods.

The tackifying resin used in the double-sided pressure-sensitive adhesive tape of the present invention is preferably a resin acid ester having a hydroxyl value of 10 to 25. The resin acid ester can be obtained by reacting a resin acid and a polyhydric alcohol.

Examples of the resin acid include resin acid monomers such as rosins, and examples of the rosin include gum rosin, wood rosin and tall oil rosin. Further, the resin acid preferably contains 5% by weight or more of a resin acid dimer. More preferably, it is 10% by weight or more. When the content of the resin acid dimer is 5% by weight or more, the tackiness at low temperature is particularly excellent.

The resin acid dimer is usually called a polymerized rosin, and is a dimer of resin acid monomers such as rosins.

Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, diethylene glycol and triethylene glycol, trihydric alcohols such as glycerin, pentaerythritol, dipentaerythritol,
Examples include tetrahydric or higher alcohols such as polyglycerin.

Specific examples of the tackifying resin include rosin ester-based resin (Super Ester A series, manufactured by Arakawa Chemical Co., Ltd.), polymerized rosin ester-based resin (Pencel D series, manufactured by Arakawa Chemical Co., Ltd.), and high-grade hydrocarbon resin (FTR). Series, manufactured by Mitsui Petrochemical Co., Ltd., and the like.

The blending ratio of the acrylic polymer and the tackifying resin is set so that the resulting adhesive layer has a hydroxyl value of 3.5 or more and less than 4.0. For example, the acrylic polymer 60 to 95-40 wt% tackifying resin 5-40
Weight percent is preferred.

If the amount of the acrylic polymer is less than 60% by weight, the tackiness of the pressure-sensitive adhesive layer is almost lost and it is difficult to use it as a pressure-sensitive adhesive, and if it is more than 95% by weight, the effect of adding the tackifying resin becomes small. The tackiness decreases.

The adhesive layer contains a polyisocyanate compound, a polyamine compound, a melamine compound, a urea compound,
A crosslinking agent such as an epoxy compound can be used to further improve cohesive force and heat resistance. Particularly, polyisocyanate compounds are preferably used, for example, 1,6-
Hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,
4'-diphenylmethane diisocyanate and the like can be mentioned.

The pressure-sensitive adhesive layer used in the present invention further comprises
If necessary, a filler, an antioxidant, an ultraviolet absorber and the like can be added. Further, various publicly known tackifying resins other than the above may be used in combination within a range not impairing the performance of the tackifying resin. Examples thereof include terpene resin, phenol resin, coumarone resin, xylene resin, petroleum resin and the like. Further, it may be combined with one having no hydroxyl group.

The double-sided pressure-sensitive adhesive tape of the present invention can be manufactured, for example, as follows.

A tackifying resin and a cross-linking agent are added to the acrylic polymer obtained above to obtain a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition is coated on both sides of the substrate, and then dried to give a pressure-sensitive adhesive. A double-sided pressure-sensitive adhesive tape can be obtained by forming an agent layer and sticking release paper on both sides thereof. As the above-mentioned substrate, a conventionally known one is used, and for example, a non-woven fabric is preferable.

[0024]

The double-sided pressure-sensitive adhesive tape of the present invention is one in which a pressure-sensitive adhesive layer containing an acrylic polymer and a tackifying resin is formed on both sides of a substrate, and the hydroxyl value derived from the tackifying resin of the above-mentioned pressure-sensitive adhesive layer is used. By setting the ratio to 3.5 or more and less than 4.0, it is possible to prevent the adhesiveness at a low temperature from being significantly reduced. The hydroxyl value of the pressure-sensitive adhesive layer can be within the above range by changing the hydroxyl value of the tackifying resin used and the number of parts of the tackifying resin mixed with the acrylic polymer. When the amount is out of the above range, the adhesion with the urethane foam is deteriorated.

In the acrylic pressure-sensitive adhesive composition disclosed in JP-A-3-281587 mentioned above, the hydroxyl value is 50 or more, and when such an acrylic pressure-sensitive adhesive composition is used. Have poor adhesion to urethane foam at low temperatures.

[0026]

EXAMPLES Specific examples will be described below. In addition, a part means a weight part.

(Example 1) A. Preparation of acrylic polymer 70 parts of n-butyl acrylate, 27 parts of 2-hexylhexyl acrylate, 3 parts of acrylic acid and 0.10 part of 2-hydroxyethyl acrylate were subjected to boiling point polymerization with 50% by weight of ethyl acetate to obtain a weight. A polymer having an average molecular weight of 500,000 was obtained.

B. Preparation of Double-sided Adhesive Tape The acrylic polymer obtained in the above section A was added to a rosin ester resin (super ester A-100 (hydroxyl value 14.
0), manufactured by Arakawa Chemical Co., Ltd.) and mixed with 1.5 parts of a polyisocyanate compound (manufactured by Nippon Polyurethane Company, trade name “Coronate L55E”) as a cross-linking agent and cross-linked acrylic pressure-sensitive adhesive. A composition was obtained. The hydroxyl value of this pressure-sensitive adhesive composition was 3.6.

The obtained pressure-sensitive adhesive composition is coated on both sides with a thickness of 60 μm on a non-woven fabric (manufactured by Nippon Paper Industry Co., Ltd., trade name “SPC base paper”) and then dried to form a pressure-sensitive adhesive layer. Then, release paper was attached to both sides of the adhesive to obtain a double-sided adhesive tape. The following evaluation was performed about the obtained double-sided adhesive tape.

The amount of the above-mentioned cross-linking agent was set to be 100 parts by weight of the total amount of the acrylic polymer and the tackifying resin (liquid / liquid ratio).

The hydroxyl value of the tackifying resin can be measured by
JIS-K-0070 (1992) 7. Hydroxyl value
7.1 Performed based on the neutralization titration method.

The hydroxyl value in the adhesive layer was calculated from the following formula.

[0033]

[Equation 1]

C. Foam Adhesion Test An adhesive test piece obtained by slitting the double-sided pressure-sensitive adhesive tape obtained in the above item C into a width of 25 mm in a room at 23 ° C. and 65% RH is an aluminum plate (thickness 2 mm, size 50 mm × 120 mm) was attached to one side.

The subsequent application, pressure bonding and measurement of the foam were all carried out in a room at 5 ° C.

After peeling off the release paper attached to one surface of the pressure-sensitive adhesive test piece, a urethane foam slit to a width of 20 mm was attached on the pressure-sensitive adhesive layer, and then a spacer having a thickness of 1.5 mm was formed by urethane. Placed on both sides of the foam to regulate the extent to which the urethane foam is deformed,
Thereafter, both the spacer and the urethane foam were reciprocated once while pressing a rubber roller having a weight of 2 kg at a speed of 300 mm / min to obtain a test piece.

After 20 minutes, the peel strength of the test piece was measured when the test piece was peeled 90 degrees at a pulling speed of 300 mm / min.

The urethane foam used was ECS (3 mm thick) manufactured by Inoac Corporation.

The results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 3 Example 1 except that the tackifying resin shown in Table 1 was used in place of 35 parts of the rosin ester resin (super ester A-100). A double-sided adhesive tape was obtained in the same manner. A foam adhesion test was conducted on the obtained double-sided pressure-sensitive adhesive tape in the same manner as in Example 1. The results are shown in Table 1 together with the hydroxyl value of the tackifying resin and the hydroxyl value in the adhesive layer.

[0041]

[Table 1]

[0042]

INDUSTRIAL APPLICABILITY According to the present invention, a double-sided pressure-sensitive adhesive tape having an excellent effect on urethane foam adhesion at a low temperature can be obtained, which is useful, for example, for adhesion fixing work of automobile interior materials at a low temperature.

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Claims (1)

[Claims] 1. A double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing an acrylic polymer and a tackifying resin having a hydroxyl group, wherein the pressure-sensitive adhesive layer-derived hydroxyl value of the pressure-sensitive adhesive layer is 3.5 or more and less than 4 A double-sided adhesive tape characterized in that