JP2782991B2 - Adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a (meth) acrylic solvent-based pressure-sensitive adhesive composition, and more particularly, to a compounding agent which is excellent in workability with a long pot life and is blended with a curing agent having excellent immediate curing properties. Pressure-sensitive adhesive composition.

[0002]

2. Description of the Related Art Conventionally, pressure-sensitive adhesives composed of (meth) acrylic copolymers have poor cohesiveness and temperature sensitivity.
There is known a method of performing a crosslinking treatment with a crosslinking agent such as an isocyanate compound, a melamine resin, an epoxy resin, an aziridinyl compound, and a metal chelate compound. A (meth) acrylic pressure-sensitive adhesive containing a crosslinking agent in this manner increases cohesion and improves temperature sensitivity. However, a coating material containing a metal chelate compound as a cross-linking agent has a high adhesion to a supporting substrate. Is known to be defective. In addition, crosslinking agents such as isocyanate compounds, melamine resins and epoxy resins require a long curing treatment time due to low reactivity, and unreacted crosslinking agents tend to remain in the obtained adhesive layer. This tends to cause the performance of the pressure-sensitive adhesive to deteriorate over time.

In addition, although isocyanate compounds are highly reactive, they also react with moisture in the air, so that the pot life of the pressure-sensitive adhesive composition is short and workability in applying the pressure-sensitive adhesive to a supporting substrate is good. Is not good. Further, the aziridinyl compound also has high reactivity and does not deteriorate with time of the pressure-sensitive adhesive, but has a short pot life and cannot be used practically. In order to improve this, it is known to mix volatile amine compounds.However, the odor at the time of dry coating leaves a problem in workability, and the volatile amine compounds remaining in the pressure-sensitive adhesive layer indicate the performance of the pressure-sensitive adhesive. It is the actual situation that causes the variation.

[0004]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks associated with the incorporation of these crosslinking agents, has a long pot life,
An object of the present invention is to provide a pressure-sensitive adhesive composition which is excellent in workability and does not deteriorate in performance over time.

[0005]

According to the present invention, there is provided a (meth) acrylic resin containing 0.1 to 50% by weight of a polymerizable unsaturated carboxylic acid (a) and 0.01 to 30% by weight of an amino group-containing monomer (b). A pressure-sensitive adhesive composition comprising a (meth) acrylic copolymer solution obtained by copolymerizing an acid alkyl ester in an organic solvent and an aziridinyl compound as a crosslinking agent.

In the present invention, the alkyl (meth) acrylate having an alkyl group having 1 to 14 carbon atoms preferably accounts for 50 to 99.89% by weight of the acrylic copolymer. As the alkyl (meth) acrylate, the following compounds can be exemplified. Methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
Acrylic esters of linear or branched aliphatic alcohols such as 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate and the like, and corresponding methacrylic esters. Preferably, the alkyl (meth) acrylate used is an alkyl ester having 4 to 12 carbon atoms in the alkyl group.

The copolymerizable unsaturated carboxylic acid (a) used as an essential component in the (meth) acrylic copolymer of the present invention includes the following compounds as specific examples. it can. Acrylic acid, methacrylic acid, maleic anhydride, maleic acid, maleic monoester, itaconic acid, crotonic acid, etc. The polymerizable unsaturated carboxylic acid,
0.1 to 50% by weight of the (meth) acrylic copolymer is contained, preferably used in the range of 1 to 35% by weight.
Or two or more species.

The copolymerizable polymerizable amino group-containing monomer (b) used as an essential component in the (meth) acrylic copolymer of the present invention includes N-methylaminoethyl acrylate and N-tributylamino as specific examples. Ethyl acrylate, N, N-dimethylaminoethyl acrylate,
N, N-dimethylaminoethyl methacrylate, N, N
-Diethylaminoethyl methacrylate, vinylpyrrolidone and the like. The polymerizable amino group-containing monomer,
The (meth) acrylic copolymer is contained in an amount of 0.01 to 30% by weight, preferably 1 to 20% by weight, and one or more types are contained. The lower limit of the introduction amount is limited by the function of the pressure-sensitive adhesive, and the upper limit of the introduction amount is limited by the adhesion to the support, the adhesion to the adherend, or the stability over time of the pressure-sensitive adhesive.

The (meth) acrylic copolymer of the present invention can contain the following copolymerizable polar functional group-containing monomers in addition to the above monomer components. The copolymerizable polar functional group-containing monomer has a hydroxyl group, a methylol group, a glycidyl group, a phosphoric acid group, a sulfonic acid group, an ethyleneimine group, an isocyanate group, and the like, and specific examples include the following compounds. (Meth) acrylic acid 2-
Hydroxypropyl, 2-hydroxyethyl (meth) acrylate, polyethylene glycol acrylate, glycidyl acrylate, glycidyl methacrylate, mono- (2-hydroxyethyl-α-chloroacrylate)
Acid phosphate, vinyl isocyanate and the like.

The (meth) acrylic copolymer of the present invention may contain the following monomers in addition to the above monomer components. Vinyl ester, vinyl pyridine, vinyl acetate, vinyl propionate, styrene, acrylonitrile, methacrylonitrile, butadiene, chloroprene and the like. The aziridinyl compound as a crosslinking agent in the present invention is a compound having at least two aziridinyl groups in one molecule, for example, tri-1-aziridinylphosphine oxide, N, N′-hexamethylene-1,
6-bis (1-aziridinecarboxamide),
N, N′-diphenylethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate,
N'-toluene-2,4-bis (1-aziridinecarboxyamide, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine)
Phosphine, trimethylolpropane-tri-β- (2
-Methylaziridinyl) propionate. One or more of these may be used in combination.

The aziridinyl compound is used in an amount of 0.01 to 10% based on 100 parts by weight of the (meth) acrylic copolymer.
0 parts by weight, preferably in the range of 0.05 to 3.0 parts by weight. The (meth) acrylic copolymer of the present invention can be produced by solution polymerization, bulk polymerization, or the like. Examples of the polymerization initiator include peroxides such as benzoyl peroxide, lauryl peroxide and cumene peroxide, and azo compounds such as azobisisobutyronitrile. Examples of the organic solvent used when producing the (meth) acrylic copolymer of the present invention by solution polymerization include n-pentane, toluene, benzene, n-hexane, dioxane, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, and acetic acid. Ethyl, butyl acetate and the like, and alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and butyl alcohol may be mixed.

In the pressure-sensitive adhesive composition of the present invention, other crosslinking agents such as an isocyanate compound, a melamine resin, an epoxy resin, and a metal chelate compound may be used in combination. In the pressure-sensitive adhesive composition of the present invention, other additives used for general pressure-sensitive adhesives can be used in combination. The pressure-sensitive adhesive composition of the present invention, polyester, polypropylene,
It is applied to a film-like substrate such as vinyl chloride or a paper substrate such as high quality paper, art paper, coated paper or the like in an amount of 5 to 30 μm. The obtained pressure-sensitive adhesive sheet can be used as a pressure-sensitive adhesive for labels and seals, tapes, building materials, packaging materials, and electronics.

[0013]

The present invention will be described below with reference to examples. In the examples, “parts” means “parts by weight” and “%” means “% by weight”.

[0014]

Example 1 The following monomers were charged into a 3 L 4-neck flask equipped with a stirrer, thermometer, cooler and dropping funnel, 29 parts of 2-ethylhexyl acrylate 47 parts of butyl acrylate 18 parts of vinyl acetate N, N'-dimethyl Aminoethyl methacrylate 1 part Acrylic acid 5 parts Benzoyl peroxide 0.1 part The mixture was heated with stirring and polymerized at the reflux temperature of ethyl acetate to obtain a (meth) acrylic polymer. 40% ethyl acetate solution 1 containing the obtained (meth) acrylic copolymer
In 00 parts, trimethylolpropane-tri-β- (2-
0.3 part of methylaziridinyl) propionate was blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of the pressure-sensitive adhesive was 1300 cps (BL rotational viscometer, # 3 rotor / 12 rpm), and the viscosity after storage at 40 ° C. for 8 hours was 1500 cps. Was. This adhesive composition was applied on a 25 µm-thick polyester film by a dry weight of 25 g / m2 to prepare an adhesive sheet. This adhesive sheet is JIS-Z-0237
According to the measurement of the adhesive force 24 hours after application,
70g / 25mm (to stainless steel plate), holding force,
The adhesiveness (tack) was also excellent.

[0015]

Comparative Example 1 A solution containing 100 parts of a (meth) acrylic copolymer obtained by copolymerizing in Example 1 without introducing a polymerizable amino group-containing monomer was added to trimethylolpropane-tri-β- 0.3 parts of (2-methylaziridinyl) propionate was blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of this adhesive is 130.
The viscosity after storage at 40 ° C. for 2 hours was 3 cps.
After storage at 200 cps for 4 hours, the gel was formed and coating was impossible.

[0016]

Example 2 Solution polymerization was carried out in the same manner as in Example 1 except that the following monomer formulation was used. 2-ethylhexyl acrylate 56 parts n-butyl acrylate 15 parts methyl methacrylate 20 parts itaconic acid 7 parts vinylpyrrolidone 2 parts azobisisobutyronitrile 0.1 part At elevated temperature with stirring, at the reflux temperature of ethyl acetate Polymerization was performed to obtain a (meth) acrylic polymer. 40% ethyl acetate solution 1 containing the obtained (meth) acrylic copolymer
In 00 parts, a volatile amine compound: propylamine 0.5
Part and tri-N, N'-hexamethylene-1,6-bis (1
-Aziridinecarboxamide) to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of the adhesive was 2500 cps (BL-type rotational viscometer, # 3 rotor / 12 rpm), and the viscosity after storage at 40 ° C. for 8 hours could be applied at 2800 cps. Was. This adhesive composition was applied on a 25 µm-thick polyester film by a dry weight of 25 g / m2 to prepare an adhesive sheet. This adhesive sheet is JIS-Z-0237
According to the measurement of the adhesive strength 24 hours after application,
30g / 25mm (to stainless steel plate), holding force,
The adhesiveness (tack) was also excellent.

[0017]

Comparative Example 2 In Example 2, a solution containing 100 parts of a (meth) acrylic copolymer obtained by copolymerization without introducing a polymerizable amino group-containing monomer was added with a volatile amine compound: propylamine 0 0.5 part and 0.2 part of tri-N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) were blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of this adhesive is 220
0cps (BL type viscometer, # 3 rotor / 12rp)
m) and the viscosity after storage at 40 ° C. for 8 hours is 2400
Coating was possible at cps. This pressure-sensitive adhesive composition has a thickness of 2
25 g by dry weight on a 5 μm polyester film
/ M2 to prepare an adhesive sheet. At this time, a slight amine odor was felt. This adhesive sheet is JIS-Z-0
When the adhesive force after 24 hours of application was measured based on 237, it was 450 g / 25 mm (for the stainless steel plate), but after 7 days, the adhesive force after 24 hours of application was 240 g / 25 mm. It was 25 mm (with respect to the stainless steel plate), and it was found that the crosslinking rate was significantly delayed due to the amine compound remaining in the pressure-sensitive adhesive layer, and that the adhesive force balance was lost.

[0018]

Example 3 Solution polymerization was carried out with the following monomer formulation. 2-ethylhexyl acrylate 34 parts Maleic anhydride 10 parts Methacrylic acid 5 parts N-methylaminoethyl acrylate 0.5 parts 2-hydroxyethyl acrylate 0.5 parts Methyl acrylate 40 parts Benzoyl peroxide 0.2 parts Stirring The polymerization was carried out at a reflux temperature of ethyl acetate while obtaining a (meth) acrylic polymer. 40% ethyl acetate solution 1 containing the obtained (meth) acrylic copolymer
To 100 parts, 1.0 part of tris-1- (2-methylaziridine) phosphine was blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of the pressure-sensitive adhesive was 1850.
The viscosity after storage at 40 ° C. for 8 hours is 210 cps.
Coating was possible at 0 cps. This adhesive composition was coated on a polyester film having a thickness of 25 μm by a dry weight of 25%.
g / m2 was applied to form an adhesive sheet. When the adhesive strength of this pressure-sensitive adhesive sheet after 24 hours was measured based on JIS-Z-0237, it was 560 g / 25 mm (for a stainless steel plate), and both the holding power and the tackiness (tack) were excellent.

[0019]

Comparative Example 3 In Example 3, a solution containing 100 parts of a (meth) acrylic copolymer obtained by copolymerization without introducing a polymerizable amino group-containing monomer was added with a volatile amine compound: propylamine 0 0.5 part and 1.0 part of tris-1- (2-methylaziridine) phosphine were blended to obtain a pressure-sensitive adhesive composition. Liquid temperature 40 ° C immediately after compounding of this adhesive
Was 1950 cps, and the viscosity after storage at 40 ° C. for 8 hours was 2300 cps, and coating was possible. This adhesive composition was applied on a 25 µm-thick polyester film by a dry weight of 25 g / m2 to prepare an adhesive sheet. At this time, a slight amine odor was felt. When the adhesive force of this pressure-sensitive adhesive sheet after 24 hours of application based on JIS-Z-0237 was measured, it was 750 g / 25 mm (for a stainless steel plate). The adhesive strength was measured to be 370 g / 25 mm (for a stainless steel plate), and it was found that the crosslinking rate was significantly delayed due to the amine compound remaining in the pressure-sensitive adhesive layer, and the adhesive force balance was lost.

[0020]

Example 4 Solution polymerization was carried out with the following monomer formulation. 2-ethylhexyl acrylate 73 parts Ethyl acrylate 10 parts N-tributylaminoethyl acrylate 1 part 2-hydroxyethyl acrylate 1 part Itaconic acid 15 parts Benzoyl peroxide 1.0 part Polymerization was performed at a temperature to obtain a (meth) acrylic polymer. 40% ethyl acetate solution 1 containing the obtained (meth) acrylic copolymer
In 00 parts, trimethylolpropane-tri-β- (2-
0.5 part of methylaziridinyl) propionate was blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the mixing of the pressure-sensitive adhesive was 2,300 cps, and the viscosity after storage at 40 ° C. for 8 hours was 2,450 cps. This adhesive composition was applied on a 25 µm-thick polyester film by a dry weight of 25 g / m2 to prepare an adhesive sheet. This pressure-sensitive adhesive sheet is JIS-Z-023
Based on 7 and measuring the adhesive strength 24 hours after application,
It was 520 g / 25 mm (with respect to stainless steel plate), and was excellent in both holding power and tackiness (tack).

[0021]

Comparative Example 4 A solution containing 100 parts of a (meth) acrylic copolymer obtained by copolymerization in Example 4 without introducing a polymerizable amino group-containing monomer was added to trimethylolpropane-tri-β- 0.5 part of (2-methylaziridinyl) propionate was blended to obtain a pressure-sensitive adhesive composition. The viscosity at a liquid temperature of 40 ° C. immediately after the compounding of this adhesive is 245
The viscosity after storage at 40 ° C. for 2 hours was 9 cps.
After storage at 300 cps for 4 hours, it was gelled and could not be applied.

[0022]

The pressure-sensitive adhesive composition of the present invention can be prepared by adding a highly reactive cross-linking agent to a (meth) acrylic acid alkyl ester-based copolymer having a carboxyl group introduced as a cross-linking point, whereby the pressure-sensitive adhesive is aggregated. The strength is increased, and deterioration of the pressure-sensitive adhesive over time due to an unreacted crosslinking agent is prevented. Furthermore, due to the copolymerization of the polymerizable amino group-containing monomer, the pot life of the pressure-sensitive adhesive composition solution after blending the cross-linking agent is extended, and special consideration should be given to work in the manufacturing process of pressure-sensitive adhesive tapes and pressure-sensitive labels. The practical value is high because it can be used without it.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-70780 (JP, A) JP-A-63-130685 (JP, A) JP-A-61-152779 (JP, A) JP-A-60-1985 65081 (JP, A) JP-A-61-261382 (JP, A) JP-A-61-19677 (JP, A) JP-B-51-47458 (JP, B1) (58) Fields investigated (Int. ⁶ , DB name) C09J 133/00-133/14 C08L 33/00-33/14

Claims (1)

(57) [Claims] 1. The polymerizable unsaturated carboxylic acid (a)
50% by weight and an amino group-containing monomer (b) 0.01 to
An adhesive composition comprising a (meth) acrylic copolymer solution obtained by copolymerizing an alkyl (meth) acrylate containing 30% by weight in an organic solvent and an aziridinyl compound as a crosslinking agent.