JPH08209093A - Tacky agent composition - Google Patents

Abstract

PURPOSE: To obtain a tacky agent composition useful as a tacky tape for bonding a vinyl chloride-based resin plate, having sufficient bond strength with time as well as initial bond strength, comprising a specific graft copolymer, a tackifier resin, a plasticizer and a cross-linking agent in a specific ratio. CONSTITUTION: This tacky agent composition comprises (A) 100 pts.wt. graft copolymer obtained by grafting (i) a 1-12C alkyl (meth)acrylate and (ii) vinyl acetate to a chloroprene-based rubber, (B) 25-80 pts.wt. tackifier resin such as (hydrogenated) rosin resin, (C) 25-80 pts.wt. plasticizer such as dimethyl phthalate and (D) 0.5-8 pts.wt. cross-linking agent such as tolylene diisocyanate.

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, and more particularly to a pressure-sensitive adhesive composition suitable for adhering a vinyl chloride resin plate containing a plasticizer when used as a pressure-sensitive adhesive tape.

[0002]

2. Description of the Related Art Conventionally, acrylic adhesives made of acrylic copolymers are widely used because of their excellent initial adhesive strength, shear adhesive strength, and weather resistance, and the ability to design performance by various formulations. It has been used for various purposes.

However, when a pressure-sensitive adhesive tape using such an acrylic pressure-sensitive adhesive is applied to a soft vinyl chloride resin containing a large amount of a plasticizer, etc., the migration of the plasticizer to the pressure-sensitive adhesive layer causes remarkable aggregation. There is a problem that the strength is lowered and the adhesive strength is lowered.

As one of the methods for solving the above problems,
An adhesive using a polymer obtained by graft-copolymerizing chloroprene rubber with (meth) acrylic acid ester and acrylonitrile has been disclosed (JP-A-5-86347).

[0005]

However, although the polymer described in JP-A-5-86347 is useful as an adhesive, for example, when it is used as an adhesive tape laminated on at least one surface of a substrate. Had no initial adhesive strength at room temperature and could not be used as an adhesive tape.

The object of the present invention is, when used as a pressure-sensitive adhesive tape, to obtain an adherend having a vinyl chloride resin containing a plasticizer on the surface thereof, as well as an initial adhesive force and a sufficient adhesive force even after lapse of time. It is to provide such an adhesive composition.

[0007]

The pressure-sensitive adhesive composition of the present invention contains a graft copolymer as a main component, and the above-mentioned graft copolymer comprises a chloroprene rubber and an alkyl (meth) acrylate (A). And vinyl acetate (B) are graft-copolymerized.

Examples of the chloroprene rubber include homopolymers of chloroprene and copolymers of chloroprene and other monomers.

The above alkyl (meth) acrylate (A)
Is an alkyl group having 1 to 12 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth). Acrylate, sec-butyl (meth) acrylate, t-
Butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n
-Octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate,
Examples thereof include isononyl (meth) acrylate and lauryl (meth) acrylate, and these may be used alone or in combination of two or more kinds.

The above alkyl (meth) acrylate (A)
If the copolymerization ratio of is small, it becomes difficult to obtain sufficient adhesion to the soft vinyl chloride resin adherend, and if it is large, the crystallinity of the chloroprene rubber is impaired, and sufficient adhesion stability over time is obtained. Therefore, it is preferably 20 to 100 parts by weight of chloroprene rubber.
The amount is 150 parts by weight, more preferably 20 to 130 parts by weight, and particularly preferably 30 to 120 parts by weight.

When the copolymerization ratio of the vinyl acetate (B) is small, it becomes difficult to obtain sufficient adhesive force to the soft vinyl chloride resin adherend, and when the copolymerization ratio is large, the same result is obtained. Therefore, the chloroprene rubber is obtained. For 100 parts by weight,
It is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight, and particularly preferably 5 to 30 parts by weight.

Other vinyl monomers may be copolymerized with the above graft copolymer, for example, (meth) acrylic acid, itaconic acid, crotonic acid, (anhydrous) maleic acid, (anhydrous) fumaric acid, carboxy. Carboxyl group-containing vinyl monomer such as ethyl acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone modified (meth) acrylate, polyethylene glycol (meth) acrylate Hydroxyl group-containing vinyl monomers such as polypropylene glycol (meth) acrylate, (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyllaurylolactam, (meth) acryloylmorpholine, (meth) Acrylamide, dimethyl (meth) acrylamide, N- methylol (meth) acrylamide, N- butoxymethyl (meth) acrylamide,
Nitrogen-containing vinyl monomers such as dimethylaminopropyl (meth) acrylamide, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and the like can be given. May be used alone or in combination of two or more.

The copolymerization ratio of the other vinyl monomer is
If the amount is large, it becomes difficult to obtain a sufficient initial adhesive force to the soft vinyl chloride resin adherend. Therefore, the amount is preferably 15 parts by weight or less relative to 100 parts by weight of the chloroprene rubber.
It is more preferably 10 parts by weight or less.

Solution polymerization is generally preferred as the method for obtaining the above graft copolymer. For example, chloroprene rubber, alkyl (meth) acrylate, vinyl acetate and the like are dissolved in an organic solvent, and then a thermal polymerization initiator is added. A method of adding and polymerizing while heating is included.

Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene, alicyclic compounds such as cyclohexane, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, acetone, cyclohexanone and other ketones, and methyl acetate. , Esters such as ethyl acetate and butyl acetate, etc., and these may be used alone or in combination of two or more kinds.

Examples of the thermal polymerization initiator include ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, isobutyryl peroxide, benzoyl peroxide, and 2,4-dichlorobenzoyl peroxide. , Diacyl peroxides such as P-chlorobenzoyl peroxide, hydroperoxides such as diisopropylbenzene hydroperoxide and t-butyl hydroperoxide, 2,5
-Dialkyl peroxides such as dimethyl-2,5-di- (t-butylperoxy) hexane, 1,3-bis- (t-butylperoxyisopropyl) benzene and di-t-butylperoxide, 1, Peroxyketals such as 1-di-t- (butylperoxy) -3,3,5-trimethylcyclohexane and 1,1-di- (t-butylperoxy) cyclohexane, t-butylperoxypivalate, Alkyl peresters such as t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, di-2-ethylhexylperoxydicarbonate, bis- (4-t-butylcyclohexyl) peroxy In addition to organic peroxides such as percarbonates such as dicarbonates, 2,2′-azobis-isobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azo Examples include azobis compounds such as bisisobutyrate, 4,4′-azobis-4-cyanovaleric acid, and 2,2′-azobis- (2-aminopropane) dihydrochloride, which are used alone. Or two or more kinds may be used in combination.

A chain transfer agent may be added for the purpose of suppressing variations in the polymerization reaction when polymerizing the above graft copolymer and appropriately controlling the molecular weight of the resulting copolymer.
For example, n-dodecyl mercaptan, 2-mercaptoethanol, β-mercaptopropionic acid, octyl β-mercaptopropionate, methoxybutyl β-mercaptopropionate, trimethylolpropane tris (β-
Thiopropionate), butyl thioglycolate, propanethiols, butanethiols, thiophosphites and other thiol compounds, and carbon tetrachloride and other halogen compounds.

The solution polymerization temperature is determined depending on the decomposition temperature of the thermal polymerization initiator used, the boiling point of the organic solvent and the like, but is usually 60 to 120 ° C.

The solution of the graft copolymer obtained by the solution polymerization may be used in any solid content, but the solid content is preferably 10 to 30% by weight because it is easy to use.

The pressure-sensitive adhesive composition of the present invention comprises the above graft copolymer, a tackifying resin, a plasticizer and a crosslinking agent.

The tackifying resin is added for the purpose of obtaining an initial tackiness at room temperature, and for example, C5 and C9 (hydrogenated) petroleum resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester. Resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, (hydrogenated) coumarone indene resin, disproportionated rosin resin, disproportionated rosin ester resin, polymerized rosin resin, polymerized rosin ester resin, xylene resin , Styrene resin, and heat-reactive phenol resin, and these may be used alone or in combination of two or more kinds.

When the addition amount of the above tackifying resin is small, it is difficult to obtain a sufficient initial adhesive force to the soft vinyl chloride resin adherend, and when it is too large, the cohesive force is lowered and a sufficient shear adhesive force is obtained. 25 to 80 parts by weight, preferably 30 to 80 parts by weight, and more preferably 40 to 100 parts by weight of the above graft copolymer.
˜70 parts by weight.

The above-mentioned plasticizer is added mainly for the purpose of softening the chloroprene rubber having a high crystallinity at room temperature and obtaining a sufficient initial adhesive force. For example, dimethyl phthalate,
Examples thereof include phthalate ester systems such as dibutyl phthalate and dioctyl phthalate, and dibasic fatty acid esters such as dimethyl adipate, dioctyl adipate and diisodecyl adipate, which may be used alone or in combination of two or more kinds. Good.

When the amount of the plasticizer added is small, it becomes difficult to obtain sufficient initial adhesive force to the soft vinyl chloride resin adherend, and when it is large, the cohesive force is lowered and sufficient shear adhesive force is obtained. Therefore, the amount is 25 to 80 parts by weight, preferably 25 to 70 parts by weight, and more preferably 30 to 60 parts by weight with respect to 100 parts by weight of the graft copolymer.

The above-mentioned cross-linking agent is added for the purpose of increasing the cohesive force by cross-linking the main chain chloroprene rubber and obtaining sufficient shear strength. For example, tolylene diisocyanate (TDI) and naphthylene-1,5. -Diisocyanate, diphenylmethane diisocyanate (MDI),
Hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), xylene diisocyanate (XDI), trimethylolpropane modified TD
In addition to isocyanate-based crosslinking agents such as I, oxides of divalent metals such as zinc oxide, lead oxide, calcium oxide and magnesium oxide may be used, and these may be used alone or in combination of two or more kinds. May be.

When the amount of the above-mentioned cross-linking agent added is small, the cohesive force is lowered, and it becomes difficult to obtain a sufficient shear adhesive strength, and when it is increased, the unreacted cross-linking agent is deactivated and the pressure-sensitive adhesive composition is adversely affected. Therefore, it is 0.5 to 8 parts by weight, preferably 1 to 8 parts by weight, and more preferably 3 to 8 parts by weight with respect to 100 parts by weight of the graft copolymer.

A crosslinking accelerator may be added to the pressure-sensitive adhesive composition of the present invention together with the above-mentioned crosslinking agent, and examples thereof include crosslinking accelerators such as aldehyde amines, polyethylene polyamines and ammonium dithiocarbamate.

The pressure-sensitive adhesive composition of the present invention is used as a single-sided or double-sided pressure-sensitive adhesive tape by laminating it on one side or both sides of a substrate such as a film or sheet. Examples of the base material include olefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate, paper, non-woven fabric, and acrylic adhesive sheets.

The thickness of the pressure-sensitive adhesive composition to be laminated on the pressure-sensitive adhesive tape is usually 10 to 500 μm, but it is not limited to this and is appropriately selected.

[0030]

The graft copolymer, which is the main component of the pressure-sensitive adhesive composition of the present invention, is obtained by graft-copolymerizing an alkyl (meth) acrylate and vinyl acetate on a chloroprene rubber having a high cohesive force by itself. As a result, the cohesive force and the adhesive force are easily balanced. Further, by adding a specific amount of a tackifying resin or a plasticizer, a better initial adhesive strength and flexibility can be obtained, and by being crosslinked by a crosslinking agent, an adhesive composition having a better cohesive strength can be obtained. ing. Therefore, when the pressure-sensitive adhesive tape obtained by laminating the pressure-sensitive adhesive composition of the present invention is attached to an adherend made of a vinyl chloride resin containing a plasticizer, it can withstand the migration of the plasticizer from the vinyl chloride resin. It is considered that the resin has a cross-linking density of a certain degree and the initial adhesive force is sufficient.

[0031]

EXAMPLES Examples of the present invention will be described below. still,
Hereinafter, "part" means "part by weight". "Preparation of Graft Copolymer" (Graft Copolymer A) Chloroprene rubber (trade name "277-CGT" manufactured by Kowa Chemical Co., Ltd.) in an autoclave
100 parts, 80 parts of methyl methacrylate, vinyl acetate 2
0 parts and 800 parts of toluene were added, and the temperature was raised to 80 ° C. to dissolve. Then benzoyl peroxide 1.5
Part was added and graft copolymerization was carried out for 3 hours to obtain a solution of graft copolymer A having a resin solid content of 20% by weight.

(Graft copolymer B) A graft copolymer having a resin solid content of 20% by weight was prepared in the same manner as in the graft copolymer A except that 100 parts of methyl methacrylate was used and vinyl acetate was not added. A solution of B was obtained.

(Graft copolymer C) A resin solid content of 2 was obtained in the same manner as in the graft copolymer A except that 10 parts of methyl methacrylate and 90 parts of vinyl acetate were used.
A solution of 0% by weight of graft copolymer C was obtained.

(Examples 1 to 4 and Comparative Examples 1 to 5) According to the blending composition of Table 1, the above graft copolymer (converted to solid content in Table 1), rosin ester (manufactured by Arakawa Chemical Co., Ltd., trade name " Super ester A-115 "), terpene resin (Yasuhara Chemical Co., Ltd., trade name" YS Polystar T-13 "
0 "), dibutyl phthalate, tolylene diisocyanate, zinc oxide and magnesium oxide, respectively, and mixed sufficiently to obtain a pressure-sensitive adhesive composition, and then a bar coater on a 38 μm polyethylene terephthalate film whose surface is release-treated. After coating with 11
It was dried in an oven at 0 ° C. for 5 minutes to obtain a laminate having a 30 μm pressure-sensitive adhesive composition layer formed.

"Evaluation of performance of laminate" Evaluation items and evaluation methods are shown below. (Measurement of initial peel strength) Width 20 mm
× Cut to a length of 100 mm and JIS at 23 ° C
Lined by sticking to an H4000 standard 0.05 mm thick aluminum alloy sheet (product number "1100P"), peel off the polyethylene terephthalate film on the other side, and soft chloride with a width of 25 mm, a length of 100 mm and a thickness of 1.0 mm. Vinyl-based resin plate (Engineering Test Service Co., Ltd., product name “Vinite” 2 kg under 23 ° C. condition
The sample was made by reciprocating two times at a speed of 300 mm / min using the pressure bonding roller. The initial peel strength was obtained by pulling the aluminum alloy sheet lined from the soft vinyl chloride resin plate at an angle of 90 ° at a speed of 300 mm / min using a tensile tester for the sample after curing at 23 ° C for 72 hours. Was measured and the results are shown in Table 1 together with the fracture morphology. The unit is kgf / 20mm
Is.

(Measurement of Peel Strength Over Time) A sample obtained by the same operation as above was further aged at 23 ° C. for 1 month, and then the peel strength over time was measured in the same manner. Indicated. The unit is kgf / 20 mm.

[0037]

[Table 1]

[0038]

EFFECTS OF THE INVENTION The pressure-sensitive adhesive composition of the present invention has high initial adhesiveness to a soft vinyl chloride resin and is unlikely to cause a decrease in cohesive force due to migration of a plasticizer from the vinyl chloride resin. Has become. Therefore, when the pressure-sensitive adhesive composition is used as a pressure-sensitive adhesive tape, it has sufficient adhesive strength to an adherend made of a soft vinyl chloride resin for a long period of time.

Claims (1)

[Claims] 1. A graft copolymer obtained by graft-copolymerizing a chloroprene rubber with (A) an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms and (B) vinyl acetate, 100 parts by weight of a tackifying resin. 25-80 parts by weight,
An adhesive composition comprising 25 to 80 parts by weight of a plasticizer and 0.5 to 8 parts by weight of a crosslinking agent.