JPH07179836A - Hot-melt pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the subject compsn. which is excellent in low-temp. properties, high-temp. creep resistance, and peelability and can be used in a wide temp. range. CONSTITUTION:This adhesive compsn. has a loop tack value at -20 deg.C of 100 gf/25 mm or higher and a holding power at 40 deg. of 3.0mm or lower and comprises 100 pts.wt. block copolymer of an A-B type and/or an A-B-A type (wherein A is an arom. vinyl polymer block and B is a conjugated diene polymer block provided the content of A in the copolymer is 5-30wt.%) having a wt. average mol. wt. of 50,000-200,000 and a 300% modulus of 2-10kg/cm<2>, 30-130 pts.wt. tackifying resin, and 10-70 pts.wt. softener provided the sum of the tackifying resin and the softener is 50-150 pts.wt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt pressure-sensitive adhesive composition which has excellent low-temperature characteristics and creep resistance at high temperatures, has a wide operating temperature range, and is excellent in re-peeling.

[0002]

2. Description of the Related Art Conventionally, pressure-sensitive adhesive tapes have been used for many purposes such as sealing, packing, wrapping, masking, repair, etc. Generally, the pressure-sensitive adhesive tapes are natural rubber or isoprene, styrene-isoprene or Styrene-diene rubber, which is a polymer or copolymer such as butadiene, is used as a base elastomer, and an adhesive liquid obtained by dissolving and mixing this with a tackifier, a softening agent, a stabilizer and the like in an organic solvent, a film, paper, It is manufactured by coating a tape base material such as cloth and then removing the solvent by drying. However, the use of solvents has problems such as fire, working environment, and productivity. Therefore,
As a means for solving these problems, a hot-melt type pressure-sensitive adhesive, which is obtained by hot-melting and coating a pressure-sensitive adhesive without using an organic solvent, has attracted attention and has already been industrialized.

The base elastomer of the hot-melt type pressure sensitive adhesive is a styrene-isoprene-styrene copolymer (hereinafter referred to as "SIS"), a styrene-butadiene-styrene copolymer (hereinafter referred to as "SBS"), or these. Hydrogenated products, styrene-ethylene-propylene-styrene copolymer (hereinafter referred to as "SEPS"), styrene-
Ethylene-butylene-styrene copolymer (hereinafter referred to as "SEB
Various elastomers such as thermoplastic block copolymers such as S); ethylene-vinyl acetate copolymers, ethylene-α-olefin copolymers are used. Among these, thermoplastic block copolymer type pressure-sensitive adhesives such as SIS, SBS, SEPS and SEBS are disclosed in Japanese Patent Publication No.
As disclosed in Japanese Patent No. 41518, etc., it is preferably used because of its excellent adhesiveness and cohesive force.

Hot-melt pressure-sensitive adhesives are produced by blending the above elastomer with a tackifying resin and a softening agent such as liquid rubber, oil, plasticizer and liquid resin. The important purpose of blending the softening agent in the adhesive is to improve the low temperature characteristics and to lower the melt viscosity of the pressure sensitive adhesive to enhance the fluidity and improve the coatability.

[0005]

However, the hot-melt type pressure-sensitive adhesives produced by these methods usually have a drawback that the pressure-sensitive adhesive property changes greatly with temperature. That is, when the amount of the softening agent is increased in order to improve the low temperature characteristics, the cohesive force at high temperature is poor and the creep resistance property is deteriorated, and conversely, when the amount of the softening agent is decreased to increase the cohesive force at high temperature,
There is a problem that the low temperature characteristics deteriorate, the melt viscosity increases, and the coatability deteriorates. Further, even if the amount of the softening agent is decreased and the amount of the tackifying resin is increased, the melt viscosity is lowered and the decrease in the cohesive force at a high temperature can be suppressed to some extent, but the low temperature characteristics are deteriorated. Therefore, conventionally, in the hot-melt pressure-sensitive adhesive, the compounding ratio of the tackifying resin, the softening agent and the like other than the elastomer tends to be higher than that of the solution-type pressure-sensitive adhesive, and as a result, the temperature of the pressure-sensitive adhesive property is increased. Dependence becomes large and the practical temperature range is narrower than that of solution pressure sensitive adhesives.Adhesiveness is too high and the adherend is damaged when peeled off after sticking the adhesive tape or the adhesive tape is cut. However, there is a problem that it is not suitable for applications that require removability. An object of the present invention is to provide a hot-melt pressure-sensitive adhesive composition which has excellent low-temperature characteristics and creep resistance at high temperatures, has a wide practical temperature range, and has excellent removability.

[0006]

The inventors of the present invention have made extensive studies for this reason, and as a result, as will be described later, the molecular weight, the modulus and the molecular weight of the AB type and / or ABA type block copolymers and The object is achieved by using an elastomer having a specified composition ratio of the A block in the block copolymer and limiting the addition amount of the tackifying resin, the addition amount of the softening agent and the addition amount thereof. The present invention has been completed and the present invention has been completed.

That is, the present invention provides the following component (a),
(B) and (c) and composition, hot-melt pressure-sensitive material characterized by having a loop tack value at −20 ° C. of 100 gf / 25 mm or more and a holding power at 40 ° C. of 3.0 mm or less. It is an adhesive composition. (A) General formula A-B and / or A-B-A (In the formula, A represents an aromatic vinyl-based polymer block, B represents a conjugated diene-based polymer block, and the content of A is a block. It is 5 to 30% by weight in the copolymer) 100 parts by weight of a block copolymer having a weight average molecular weight of 50,000 to 200,000 and a 300% modulus of ^{2 to} 10 kg / cm ² (b) ) Tackifying resin 30 to 130 parts by weight (c) Softener 10 to 70 parts by weight However, the total amount of the component (b) and the component (c) is 50 to 1
It is 50 parts by weight.

Here, the loop tack value means an FTM-adhesive tape obtained by applying a pressure-sensitive adhesive to a thickness of 40 ± 5 μm on one side with a paper, cloth, plastic film or a laminate of these as a support. 9 (FINAT test method, Quick-s
In the test method of tick measurement), it is a value measured using a stainless steel plate as an adherend. The holding force is a value measured in accordance with JIS Z 0237 under the conditions that the adherend is a glass plate, the adhesive tape has an attachment area of 12 × 20 mm ² , the suspension load is 1 kg, and the time is 60 minutes. Is. The composition of the present invention is excellent not only in low-temperature characteristics and creep resistance at high temperatures but also in removability, and can be suitably used for various applications.

The present invention will be described in detail below. Examples of the aromatic vinyl monomer of the block copolymer (a) composed of the aromatic vinyl monomer and the conjugated diene-based monomer used in the present invention include styrene, α-methylstyrene, vinyltoluene and the like. However, styrene is particularly preferable. Examples of the conjugated diene-based monomer include butadiene, isoprene, piperylene and the like, but isoprene is preferable among them. The main component of the elastomer used in the present invention is represented by the general formula AB and / or ABA (wherein A represents an aromatic vinyl polymer block and B represents a conjugated diene polymer block. The content of the block A in the copolymer is 5 to 30% by weight), and the weight average molecular weight is 5
20,000 to 200,000, 300% Modulus is 2
It is about 10 kg / cm ² .

The block copolymer (a) has a molecular weight of 50,
If it is less than 000, the cohesive force of the pressure-sensitive adhesive composition is poor and the creep resistance at high temperatures is poor. When the molecular weight exceeds 200,000, the melt viscosity becomes too high and the coatability deteriorates. If the 300% modulus is less than ² kg / cm ² , the cohesive force is poor, and if it exceeds 10 kg / cm ² , the initial tackiness is poor and the low temperature properties are poor. When the content of the aromatic vinyl hydrocarbon is less than 5% by weight, the cohesive force is insufficient, and when it exceeds 30% by weight, the flexibility as an elastomer is lowered and the compatibility with the tackifying resin (b) is poor. Adhesive properties are less likely to develop.

The block copolymer (a) used in the present invention
Include ethylene-vinyl acetate copolymer, ethylene-α-
Olefin-based elastomers such as olefin copolymers, polyethylene and polypropylene may be added in an amount not exceeding 20% by weight based on the total polymer. Examples of the tackifying resin (b) used in the present invention include an aliphatic petroleum resin, an aromatic petroleum resin, a rosin resin, a terpene resin, a coumarone-indene resin, and one or more of them. Is used. The compounding amount of the tackifying resin (b) is 30 to 130 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the elastomer. When the amount is less than 30 parts by weight, the tackiness is poor, and when the amount is more than 130 parts by weight, low temperature characteristics are deteriorated and removability becomes difficult to be imparted.

The softening agent (c) used in the present invention includes
Examples thereof include polyester-based plasticizers, naphthene-based oils, aromatic oils, paraffin-based oils, and the like, and at least one of these is used. Softeners such as plasticizers and oils (c)
The compounding amount of 10 to 7 parts with respect to 100 parts by weight of the component (a).
It is 0 part by weight, preferably 20 to 60 parts by weight. When the blending amount of the softening agent (c) is less than 10 parts by weight, the melt viscosity becomes high and the coatability is poor, and when it exceeds 70 parts by weight, the creep resistance property at high temperature becomes poor. The total blending ratio of the tackifying resin (b) and the softening agent (c) is 50 to 150 parts by weight, preferably 70 to 130 parts by weight, relative to 100 parts by weight of the component (a). If it is less than 50 parts by weight, the melt viscosity becomes too high and the coating workability becomes poor, and if it exceeds 150 parts by weight, the low temperature properties become poor, the creep resistance at high temperatures becomes poor, and removability is imparted. You may not be able to do it.

From the viewpoint of coating workability, the hot melt pressure-sensitive adhesive preferably has a melt viscosity at 190 ° C. of 2,000 poises or less, preferably 1,000 poises or less. Generally, the elastic modulus of a pressure-sensitive adhesive decreases as the temperature rises, but a pressure-sensitive adhesive having a smaller change in elastic modulus with a temperature change is preferable. The hot melt pressure-sensitive adhesive composition of the present invention has a shear storage elastic modulus at 50 ° C. and 0 ° C. at 1 Hz of 7 × 10 ⁵ dyne / cm ² or more and 7 × 10 ⁶ dyne / cm ² or less, respectively. The temperature dependency is smaller than that of the conventional hot melt type pressure sensitive adhesive.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Examples 1 and 2 and Comparative Examples 1, 2 and 3 Hot-melt pressure-sensitive adhesives having the compositions shown in Table 1 were prepared by melting and stirring at 190 ° C. The melt viscosity of the obtained sample at 190 ° C. was measured by a BH type viscometer, and the shear storage elastic modulus at 1 Hz was measured by Rheometrics R.
Measured with DAII. Next, each pressure-sensitive adhesive was melted and coated on a hot plate on a kraft paper side having a total thickness of 115 μm laminated on one side with polyethylene so that the adhesive thickness was 40 μm. . The loop tack value, holding power, and removability of the obtained adhesive tape were measured by the test methods shown below. The above results are shown in Table 1.

(Removability test) An adhesive tape was attached to a glass plate in an atmosphere of 23 ° C., left for 24 hours, and then peeled at an angle of 1
The adhesive tape was peeled off at 80 degrees and a peeling speed of 100 mm / min. Good removability was obtained when the adhesive tape was peeled off cleanly from the glass plate (○), and the adhesive adhered to the glass plate, causing delamination (delamination between polyethylene and kraft paper) on the tape support. In this case, the removability was evaluated as poor (x).

[0017]

[Table 1]

[0018]

As is apparent from Examples 1 and 2, the hot-melt pressure-sensitive adhesive of the present invention has a low melt viscosity which causes no problem in coating workability and is a conventional hot-melt pressure-sensitive adhesive. Stable and good adhesive properties over a wide temperature range from -20 ° C to 40 ° C, which was not obtained by Furthermore,
Even if the adhesive tape is attached and then peeled off, the adherend is not damaged or the tape is not cut, and the removability is excellent. The composition of Comparative Example 1 has a low melt viscosity and has no problem of coatability,
It also has good low-temperature characteristics, but has poor creep resistance at high temperatures and a narrow operating temperature range. Further, the composition of Comparative Example 2 has poor low temperature characteristics and high temperature characteristics, has no removability, and cannot be used practically. In addition, the composition of Comparative Example 3 had a very low cohesive force and thus had poor high-temperature properties, and also in the removability test, delamination and cohesive failure of the adhesive occurred. The hot-melt pressure-sensitive adhesive of the present invention can be preferably used as a pressure-sensitive adhesive for pressure-sensitive adhesive tapes having a wider range of applications than conventional hot-melt pressure-sensitive adhesives.

Claims (3)

[Claims] 1. A composition comprising the following components (a), (b) and (c) and a composition having a loop tack value at −20 ° C. of 10:
A hot-melt type pressure-sensitive adhesive composition having a holding power of 0 gf / 25 mm or more and a holding power at 40 ° C. of 3.0 mm or less. (A) General formula A-B and / or A-B-A (In the formula, A represents an aromatic vinyl-based polymer block, B represents a conjugated diene-based polymer block, and the content of A is a block. 100% by weight of a block copolymer having a weight average molecular weight of 50,000 to 200,000 and a 300% modulus of ^{2 to} 10 kg / cm ² and having a structure represented by the formula: ) Tackifying resin 30 to 130 parts by weight (c) Softener 10 to 70 parts by weight However, the total amount of the component (b) and the component (c) is 50 to 1
It is 50 parts by weight. 2. The hot melt type pressure-sensitive adhesive composition according to claim 1, which has a melt viscosity at 190 ° C. of 1,000 poise or less. 3. Shear storage modulus at 50 ° C. and 0 ° C. at 1 Hz is 7 × 10 ⁵ dyne / cm ² or more and 7 respectively.
The hot-melt pressure-sensitive adhesive composition according to claim 1, having a density of × 10 ⁶ dyne / cm ² or less.