JPH09286966A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition containing a specific copolymer together with an organic solvent, excellent in adhesion to an adhered material consisting of a polyolefinic resin or to a pressure-sensitive adhesive tape substrate and useful for the production of a pressure-sensitive adhesive product such as an adhesive sheet and an adhesive tape. SOLUTION: This pressure-sensitive adhesive composition contains (A) a copolymer containing (A1 a copolymerizable surfactant having vinyl or allyl group as a reactive group e.g. a compound of the formula [R1 is H or methyl; R2 is a 2-4C alkylene, R3 is H or a 6-20C alkyl; X is OH or a group of the formula: OSO3 M (M is NH4 Na, K, etc.); (n) is an average number of moles for addition]} as monomer unit (e.g. containing 0.1-48wt.% A1 in the copolymer composition) with (B) an organic solvent. Further, preferably this composition contains further (C) a cross linking agent containing >=2 functional groups capable of reacting with an active hydrogen, and (D) a tackiness imparting agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is suitable for pressure-sensitive adhesive tapes or sheets which have excellent adhesion to adherends, and particularly to adherends made of polyolefin resins such as polyethylene and polypropylene. It relates to a pressure sensitive adhesive composition.

[0002]

2. Description of the Related Art Recently, there has been a remarkable expansion of pressure-sensitive adhesive tapes or sheets into industrial application fields, and in particular, double-sided tapes used for pasting surface to surface, which has been a conventional application field of adhesives. The use of is typical. The reason is that the pressure-sensitive adhesive tape originally has excellent labor-saving property and no pollution.

[0003]

However, when the adherend or the pressure-sensitive adhesive tape substrate is made of a polyolefin resin such as polyethylene or polypropylene, it is sufficient because the polyolefin resin is non-polar. No good adhesion was obtained.

Therefore, although the adhesive force is improved by blending the acrylic resin and the tackifier, it is not yet sufficiently satisfied.

The present invention provides a pressure-sensitive adhesive composition and a pressure-sensitive adhesive product which exhibit high adhesion to an adherend made of a polyolefin resin or a pressure-sensitive adhesive tape substrate. It is an issue.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a conventional solvent-type acrylic copolymer commonly used as a pressure-sensitive adhesive has
The present invention was found to obtain a composition having sufficient adhesiveness to an adherend composed of a polyolefin-based resin by copolymerizing a copolymerizable surfactant containing a vinyl group or an allyl group. It came to completion.

The invention according to claim 1 is a pressure-sensitive adhesive composition containing a copolymer containing a copolymerizable surfactant having a vinyl group or an allyl group as a reactive group as a monomer unit together with an organic solvent.

The invention according to claim 2 is characterized in that a copolymerizable surfactant having a vinyl group or an allyl group as a reactive group is contained in an amount of 0.1 to 48% by weight based on the copolymer composition. It is an agent composition.

The invention according to claim 3 is characterized in that a copolymerizable surfactant having a vinyl group or an allyl group as a reactive group is contained in an amount of 1.0 to 24% by weight of the copolymer composition. It is an agent composition.

The invention according to claim 4 is the copolymer composition,
Copolymerizable surfactant containing vinyl group or allyl group is 0.1 to 48% by weight, copolymerizable vinyl monomer containing no active hydrogen is 42 to 99.8% by weight, copolymerizable vinyl containing active hydrogen. The pressure-sensitive adhesive composition according to claim 1, 2 or 3, wherein the amount of the monomer is 0.1 to 10% by weight.

A fifth aspect of the present invention is the pressure-sensitive adhesive composition according to any one of the first to fourth aspects, which comprises a crosslinking agent containing two or more functional groups that react with active hydrogen.

The invention of claim 6 is a pressure-sensitive adhesive composition comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 5 and a tackifier mixed therein.

The invention of claim 7 is a pressure-sensitive adhesive product obtained by coating and drying the pressure-sensitive adhesive composition according to any one of claims 1 to 6 on a substrate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the present invention, a copolymerizable surfactant containing a vinyl group or an allyl group is used as the adhesion improving monomer. It is generally known that it is difficult to obtain a good adhesive force when copolymerizing with conventional adhesive monomers such as butyl acrylate and 2-ethylhexyl acrylate, since the surface tension becomes higher than the surface tension of the polyolefin resin. That is what is being done. On the other hand, it is generally known that the surface tension is lowered by using a copolymerizable surfactant, but conventionally, it is simply used as an emulsifier in a resin emulsion system, and it is used only in an organic solvent system. The use of is not known.

However, it has been found that the copolymer obtained by polymerizing the surfactant in the organic solvent-only system exhibits better adhesion to the polyolefin resin than the conventional copolymer.

That is, it can be inferred that even when the solvent was used alone, the surface tension of the obtained copolymer system could be lowered. From this, it is considered that the copolymer obtained by using the copolymerizable surfactant exhibits better adhesive force to the olefin resin than the conventional copolymer.

Further, according to the present invention, a pressure-sensitive adhesive product obtained by coating and drying the pressure-sensitive adhesive on a substrate has been provided.

Examples of the copolymerizable surfactant containing a vinyl group or an allyl group include the following general formulas (1) to (4). However, the copolymerizable surfactant is not limited to the following compounds.

[0019]

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[0020]

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[0021]

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[0022]

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(In the formula, R1, R2, R3, R4, X and n, m and w are as follows: R1: hydrogen or methyl group R2: alkylene group having 2 to 4 carbon atoms R3: 6 carbon atoms 20 alkyl group or hydrogen R4: hydrogen, an optionally substituted hydrocarbon group, a phenyl group, an amino group or a carboxyl group _{X: OH, OSO 3 M,} M: NH 4, Na, K etc n, m, W: average number of moles added)

As the vinyl monomer containing no active hydrogen, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 18 carbon atoms, such as methyl acrylate or ethyl acrylate, is used from the viewpoint of adhesive properties after polymerization. , Butyl acrylate, propyl acrylate, acrylic acid 2-
In addition to ethylhexyl, iso-octyl acrylate, n-octyl acrylate, isononyl acrylate, etc., alkyl methacrylate such as methyl methacrylate, ethyl methacrylate, octyl methacrylate, lauryl methacrylate, stearyl methacrylate; vinyl methyl Ether, vinyl ethyl ether, vinyl isopropyl ether, vinyl n-propyl ether, vinyl isobutyl ether, vinyl n-amyl ether, vinyl 2-
Alkyl vinyl ethers such as ethylhexyl ether and vinyl n-octadecyl ether; alkyl vinyl esters such as vinyl acetate and vinyl propionate; and styrene, vinyltoluene, acrylonitrile, acrylamide, methyl vinyl ketone and allyl chloride. The number of carbon atoms of the alkyl group in the alkyl group such as the alkyl acrylate ester, the methacrylic acid alkyl ester and the alkyl vinyl ether is not particularly limited, but generally, the carbon number is 1 to 18, preferably 4 to 12 is there.

The copolymerizable vinyl monomer containing active hydrogen includes hydrogen in a hydroxyl group, a carboxyl group, an amino group or the like as the active hydrogen, and preferably hydrogen in the hydroxyl group or the carboxyl group. Examples of such a monomer include unsaturated acids such as acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid Rubonic acid: 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, etc. Unsaturated alcohols and the like.

The above-mentioned copolymer can be obtained by polymerizing each monomer component in the presence of a radical polymerization initiator by a conventionally known method. The polymerization in this case is
It can be carried out by any polymerization method such as suspension polymerization, graft polymerization, block polymerization and solution polymerization. For example, when performing solution polymerization, the monomer mixture is dissolved in an organic solvent, for example, ethyl acetate or toluene alone or in a mixture, and azobisisoptyronitrile or benzoyl peroxide is added as a polymerization initiator, and an inert gas is added. 50 to 8 in the atmosphere
If heated to 0 ° C, the copolymer can be obtained in 3 to 15 hours. However, the manufacturing method is not limited to these.

The pressure-sensitive adhesive composition of the present invention comprises an organic solvent solution of the above-mentioned copolymer. In this case, any organic solvent can be used as long as it can dissolve the above-mentioned copolymer. The thing can be used. Examples of such an organic solvent include fatty acid esters such as ethyl acetate, ethyl formate, butyl formate, methyl acetate, propyl acetate and butyl acetate; aromatic hydrocarbons such as benzene, toluene and xylene; halogenation of chlorobenzene and chlorotoluene. Examples thereof include aromatic hydrocarbons; linear hydrocarbons such as n-hexane and n-heptane; cyclic hydrocarbons such as cyclohexane and methylcyclohexane. Copolymer concentration in solvent is 1
It is 0 to 80% by weight, preferably 20 to 70% by weight.

The pressure-sensitive adhesive composition of the present invention also comprises
A cross-linking agent is added if necessary. This cross-linking agent cross-links the copolymer to enhance its cohesiveness and improve the heat resistance of the composition. As the cross-linking agent, any one may be used as long as it can react with active hydrogen in the copolymer to cross-link the copolymer, and conventionally known ones are used. As such a thing, the following can be mentioned, for example.

(A) Polyisocyanate compound Addition product of tolylene diisocyanate (3 mol) and trimethylolpropane (1 mol), addition product of hexamethylene diisocyanate (3 mol) and trimethylolpropalpropane (1 mol), isophorone Examples thereof include an adduct of diisocyanate (3 mol) and trimethylolpropane (1 mol). This polyisocyanate compound reacts with active hydrogen in the copolymer through the isocyanate group to crosslink the copolymer.

(B) Polyepoxy compound Ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerol polyglycidyl ether, sorbitol polyglycidyl ether, phthalic acid diglycidyl ester and the like can be exemplified. The polyepoxy compound reacts with active hydrogen in the copolymer through the epoxy group to crosslink the copolymer.

(C) Polymethylol melamine Trimethylol melamine, hexamethylol melamine,
Examples thereof include ethylated methylolmelamine and butylated methylolmelamine. This polymethylol melamine is
It reacts with the active hydrogen of the copolymer through the methylol group to crosslink the copolymer.

(D) Metal compounds Di-iso-propoxy bis (acetylacetone) titanate, ethylene acetoacetate aluminum diisopropylate, aluminum isopropylate and the like can be exemplified. This metal compound reacts with active hydrogen in the copolymer through the metal ion to crosslink the copolymer.

The pressure-sensitive adhesive composition of the present invention also comprises
A tackifier is added if necessary. This tackifier controls the three properties of pressure-sensitive adhesives, namely tackiness, adhesive strength and holding power. Examples of the tackifier include natural resin tackifiers such as rosin, rosin derivatives, and terpene resin-based tackifiers, and synthetic resin tackifiers such as petroleum resin-based and phenol resin-based tackifiers. May be.

The pressure-sensitive adhesive composition of the present invention can be coated on a substrate and dried to give a pressure-sensitive adhesive product such as an adhesive sheet or an adhesive tape. In this case, the composition can be applied to one or both sides of the substrate. As the base material, conventionally known base materials generally used in the field of pressure-sensitive adhesives can be used. Examples of such a base material include films and sheets of synthetic resins such as polyolefin resins, polyester resins, and vinyl chloride resins, Japanese paper, and non-woven fabric. The thickness of the pressure sensitive adhesive layer on the substrate is 0.5 to 100 μm, preferably 1
It is 0 to 80 μm.

[0035]

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

Example 1 (Method for polymerizing solvent-type acrylic polymer) In a flask equipped with a stirrer, 132.40 parts by weight of ethyl acetate, 0.24 part by weight of copolymerizable surfactant a, and 95% of butyl acrylate were added. .6
8 parts by weight, acrylic acid 2.88 parts by weight, methacrylic acid 2
-Hydroxyethyl (1.20 parts by weight) was added, and the temperature was raised to 80 ° C with stirring. After 10 minutes, ethyl acetate 4.8
Azobisisobutyronitrile (AIBN) 0.
A solution in which 12 parts by weight is dissolved is charged to start the reaction. Further, a solution prepared by dissolving 0.05 parts by weight of AIBN in 1.2 parts by weight of ethyl acetate was charged 4 hours and 6 hours after the start of the reaction, and reacted at 80 ° C. for 8 hours to obtain a copolymer A. The properties of the obtained copolymer are as follows: resin part (solid content) 4
The content was 1.7% by weight and the viscosity was 5000 cps. The copolymerizable surfactant a is hereinafter referred to as “activator a”, and its structural formula is as follows.

"Activator a"

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(Method for preparing sample) Tolylene diisocyanate (3 mol) as a cross-linking agent was added to 100 parts by weight of the above copolymer.
45 of the adduct of trimethylolpropane (1 mol) with
1.7 parts by weight of a wt% ethyl acetate solution is added and coated on a polyester film (thickness: 25 μm) and dried at 100 ° C. for 2 minutes to prepare an adhesive tape having a coating thickness of 25 μm (dry).

[Examples 2 to 12 and Comparative Examples 1 to 2] By the same polymerization method as in Example 1, a copolymerizable surfactant containing a vinyl group or an allyl group and an acrylic ester were prepared. By changing the compounding ratio variously, various copolymers B to
Created N. Next, various adhesive tapes were prepared by the same method as the adhesive tape preparation of Example 1. In addition, four kinds of copolymerizable surfactants are used, and hereinafter, “activator a” and “activator b” are used.
"Activator c" and "Activator d" are shown, and "Activator a" and "Activator b"
The structural formulas of “activator c” and “activator d” are as follows. Further, only the copolymer L is charged with a solution prepared by dissolving 0.29 parts by weight of dibenzoyl peroxide (BPO) in place of AIBN in 4.8 parts by weight of ethyl acetate to start the reaction. BPO 0.07 is added to 1.2 parts by weight of ethyl acetate.
A solution in which parts by weight are dissolved is charged 4 hours and 6 hours after the start of the reaction.

"Activator b"

[Chemical 6]

"Activator c"

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"Activator d"

Embedded image Here, the compounding ratio of the composition to be mixed with each of the various copolymers A to N is shown in Table 1 below.

[0043]

[Table 1]

BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate n-OA: n-octyl acrylate AA: acrylic acid 2HEMA: 2-hydroxyethyl methacrylate

[Example 13] To 94 parts by weight of the copolymer C prepared in Example 4, 6 parts by weight of a tackifier (pentaline H: manufactured by Rika Hercules Co., Ltd.) and tolylene diisocyanate (3 mol) as a cross-linking agent and tri 45 wt% ethyl acetate solution of adduct with methylolpropane (1 mol) 1.
Add 7 parts by weight, polyester film (25μ thick
m) and dried at 100 ° C. for 2 minutes to prepare an adhesive tape having a coating thickness of 25 μm (dry).

[Example 14 and Comparative Examples 3 to 4] Example 1
Various copolymers (Stevelite Ester 7: manufactured by Rika Hercules Co., Ltd.) were prepared by changing the copolymer and the tackifier in the same manner as in 3. Next, various adhesive tapes were prepared by the same method as the adhesive tape preparation of Example 1.

The performances of various adhesive tapes in Examples and Comparative Examples are shown in Tables 2, 3 and 4 below.
It should be noted that Tables 2 and 3 show the performance of various adhesive tapes with acrylic raw materials, and Table 4 shows the performance of various adhesive tapes with a tackifier compounding.

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

Crosslinking agent B-45: 45% by weight ethyl acetate solution of an adduct of tolylene diisocyanate (3 mol) and trimethylolpropane (1 mol).

As shown in Tables 2 and 3, in the case of Examples 1 to 12 in which a copolymerizable surfactant having a vinyl group or an allyl group as a reactive group was introduced as a monomer unit into the copolymer, the copolymerizability was Compared to Comparative Example 1 in which no surfactant is introduced, the adhesive performance is almost equal to or slightly inferior to the stainless steel plate, but the adhesive performance to the polyethylene plate (PE plate) and the polypropylene plate (PP plate). There is a tendency to improve. In particular, comparing Examples 1-6, Examples 2-5
As shown in, the maximum value of the adhesive performance is recognized in the range of 1.0 to 24% by weight of the copolymerizable surfactant in the copolymer composition. On the other hand, in the case of Comparative Example 2 in which the copolymerizable surfactant was contained too much, compared with Comparative Example 1 in which the copolymerizable surfactant was not introduced, the polyethylene plate (PE plate) and the polypropylene plate (PP plate) were compared. However, the adhesive performance is not so good, and tends to be inferior to the stainless steel plate.

Considering this result, when the copolymerizable surfactant is introduced as a monomer unit, it is preferable to contain 0.1 to 48% by weight of the copolymer composition.
It is optimal to contain 1.0 to 24% by weight.

In addition, the copolymerizable surfactant was changed to contain the above optimum range of 12% by weight in Examples 7 and 8.
9 also shows an improvement in adhesion performance to a polyethylene plate (PE plate) and a polypropylene plate (PP plate).

Further, in Example 10 or Example 11 in which 2-ethylhexyl acrylate or n-octyl acrylate was copolymerized in Example 4, the improved tackiness is observed. Further, in Example 12 in which BPO was used as the initiator instead of AIBN, the adhesion performance to the polyethylene plate (PE plate) and the polypropylene plate (PP plate) was slightly inferior to that in Example 4, but it is preferable. Values are accepted.

On the other hand, as shown in Table 4, when the composition further contains a tackifier, the adhesion performance is improved not only on the polyethylene plate (PE plate) and polypropylene plate (PP plate) but also on the stainless plate. Is recognized.

Here, the criteria for each performance in Tables 2, 3 and 4 will be described. Adhesiveness The ball tack of the adhesive tape at 23 ° C. × 65% RH is measured according to JIS Z 0237. That is, place an adhesive tape (width 50 mm, length 150 mm or more) on an inclined surface of 30 degrees with the adhesive coated surface facing up, and 100 mm
The range of 100 mm from the lower end of the runway is used as the measurement unit.
A washed steel ball of 2/32 to 32/32 inches rolls on the approach lane and is represented by a numerical value 32 times the maximum diameter of the steel ball which has stopped sticking for 5 seconds within the range of the measuring section.

Adhesive strength The adhesive tape is 25 m wide under the condition of 23 ° C. × 65% RH.
m, stainless steel plate (SUS-304), polyethylene plate (PE
Plate), polypropylene plate (PP plate), 25 mm x 10
The 0 mm part is 300 m using a 2 kg rubber roller.
After 3 reciprocations at a speed of m / min, pressure bonding, 1 hour later, J
A 180 ° peel force is measured at a tensile speed of 300 mm / min using a tensile tester specified in IS B 7721.

Holding power The adhesive tape is 25 m wide under the condition of 23 ° C. × 65% RH.
m, a stainless steel plate (SUS-304) in which a test piece cut to a length of 120 mm was washed, a 25 mm × 25 mm portion was crimped back and forth 3 times at a speed of 300 mm / min using a 2 kg rubber roller, and then pressed for 1 hour. After that, a load of 1 kg is applied in the 0 ° direction at 70 ° C., and the drop time or the deviation width after 24 hours is measured.

[0060]

As described above, the pressure-sensitive adhesive composition of the present invention contains a vinyl group or an allyl group in an ordinary solvent-based acrylic copolymer which is widely used as a pressure-sensitive adhesive. By copolymerizing a copolymerizable surfactant, an excellent effect of adhesion to an adherend made of a polyolefin resin or a pressure-sensitive adhesive tape substrate is exhibited.

Claims (7)

[Claims] 1. A pressure-sensitive adhesive composition containing, together with an organic solvent, a copolymer containing a copolymerizable surfactant having a vinyl group or an allyl group as a reactive group as a monomer unit. 2. A copolymerizable surfactant having a vinyl group or an allyl group as a reactive group is contained in an amount of 0.1 to 48 in the copolymer composition.
The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is contained in a weight percentage. 3. A copolymerizable surfactant having a vinyl group or an allyl group as a reactive group is used in an amount of 1.0 to 24 in the copolymer composition.
The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition is contained in a weight percentage. 4. Of the copolymer composition, 0.1 to 48% by weight of the copolymerizable surfactant containing a vinyl group or an allyl group, and 4% of the copolymerizable vinyl monomer containing no active hydrogen.
The pressure-sensitive adhesive composition according to claim 1, 2 or 3, wherein the content of the copolymerizable vinyl monomer containing 2 to 99.8% by weight and the active hydrogen is 0.1 to 10% by weight. 5. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, which contains a crosslinking agent containing two or more functional groups that react with active hydrogen. 6. A pressure-sensitive adhesive composition comprising the pressure-sensitive adhesive composition according to claim 1 and a tackifier. 7. A pressure-sensitive adhesive product obtained by applying the pressure-sensitive adhesive composition according to claim 1 on a substrate and drying it.