JPH04372683A - adhesive composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to adhesive compositions used for labels and sheets, tapes, building materials, packaging materials, electronics, etc. It has excellent tackiness, processability and thermal stability, and especially has high adhesion to polyolefins.
The present invention relates to a pressure-sensitive adhesive composition that exhibits good adhesiveness to curved surfaces, maintains high cohesive strength over time under moist heat, and has excellent low-temperature adhesiveness.

0002

[Prior Art] Traditionally, natural rubber,
Elastic bodies such as synthetic rubber or acrylic resin are used,
Adhesive labels made by forming these adhesives on the support surface
BACKGROUND ART Sheets and tapes are widely used for various purposes because they can be easily adhered to an object surface at room temperature with pressure similar to finger pressure.

However, these general adhesives have poor cohesive force and temperature sensitivity, and in order to improve this, acrylic resins with functional groups are used, such as isocyanate compounds, melamine resins, epoxy resins, and aziridinyl compounds. Also known are methods of crosslinking using a crosslinking agent such as a metal chelate compound. The acrylic resin blended with a crosslinking agent in this manner has increased cohesive force and improved temperature sensitivity, but as the cohesive force increases, tackiness becomes poor and adhesive strength also decreases. In particular, for polyolefins, a significant decrease in adhesive strength and deterioration of curved surface adhesion was observed.
Furthermore, the cohesive force tends to decrease over time under moist heat and the adhesive force decreases at low temperatures, which causes a decrease in the performance of the pressure-sensitive adhesive, and the actual use of the pressure-sensitive adhesive is limited.

[0004]Alkylene oxide compounds such as polyethylene glycol and polypropylene glycol are added to the adhesive to improve low-temperature adhesion, but when the molecular weight is small, it causes a plasticizing effect and the molecular weight In the case where the pressure-sensitive adhesive is high, the stability of the adhesive is significantly impaired and the alkylene oxide compound is precipitated and separated at low temperatures, which is a disadvantage, and the grade and amount used are limited.

[0005]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of these conventional acrylic pressure-sensitive adhesives and provides good adhesion (
The present invention provides a pressure-sensitive adhesive composition that has high adhesive strength, high cohesive strength, and good curved surface adhesion, particularly retains high cohesive strength over time under moist heat, and has excellent low-temperature adhesive properties.

[0006]

[Means for Solving the Problems] The present invention provides a (meth)acrylic copolymer 1 containing a (meth)acrylic acid alkyl ester as a main component and a functional group-containing monomer as a copolymerization component.
0.00 parts by weight and 0.01 to 50 parts by weight of a reactive alkylene oxide compound represented by the following structural formula. R-(CH2-CXHO)n-R (However, n is an integer from 1 to 1000, R is an amino group or a carboxyl group, and X is a hydrogen atom or a methyl group.)

In the present invention, (meth)acrylic acid alkyl ester is the main component, that is, acrylic copolymer 5
The amount is 0 to 99.9 parts by weight, the functional group-containing monomer is the remaining copolymerization component, and other copolymerization components are included as necessary.

[0008] The (meth)acrylic acid alkyl ester is an alkyl ester in which the alkyl group has 1 to 14 carbon atoms, and more specifically, the following compounds can be exemplified. Methyl acrylate, ethyl acrylate,
Acrylic acid esters of linear or branched aliphatic alcohols such as butyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate, and corresponding methacrylic esters. Preferably, the (meth)acrylic acid alkyl ester used has an alkyl group having 4 to 1 carbon atoms.
Two alkyl esters. (meta) of the present invention
Copolymerizable polar functional group-containing monomers used as essential components in acrylic copolymers include carboxyl groups, hydroxyl groups, methylol groups, amino groups, amide groups, glycidyl groups, phosphoric acid groups, sulfonic acid groups, and ethyleneimine groups. ,
It has an isocyanate group, etc., and specific examples include the following compounds. Acrylic acid, methacrylic acid, maleic anhydride, maleic acid, maleic acid monoester, itaconic acid, crotonic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, polyethylene glycol acrylate, N- Methylol acrylamide, N-methylol methacrylamide,
N-methylaminoethyl acrylate, N-tributylaminoethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, acrylamide, methacrylamide, vinylpyrrolidone, glycidyl acrylate , glycidyl methacrylate, mono-(2-hydroxyethyl-α-chloroacrylate) acid phosphate, vinyl isocyanate, and the like. The above-mentioned functional group-containing monomer is contained in an amount of 0.01 to 25% by weight of the (meth)acrylic copolymer, and one or more types thereof are contained.

The (meth)acrylic copolymer of the present invention may contain the following monomers in addition to the above monomer components. Vinyl ester, vinylpyridine, vinyl acetate, vinyl propionate, styrene, acrylonitrile,
Methacrylonitrile, butadiene, chloroprene, etc.

The (meth)acrylic copolymer of the present invention can be produced by solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. Examples of the polymerization initiator include peroxides such as benzoyl peroxide, lauryl peroxide, and cumene peroxide, azo compounds such as azobisisobutyronitrile, and persulfate compounds such as ammonium persulfate and potassium persulfate.

The organic solvent used when producing the (meth)acrylic copolymer of the present invention by solution polymerization includes n
- Pentane, toluene, benzene, n-hexane, dioxane, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, etc., mixed with alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, etc. Good too.

In the present invention, the reactive alkylene oxide compound has an alkylene oxide skeleton such as ethylene oxide or propylene oxide, and has an amino group or a carboxyl group as a polar functional group at both ends. These compounds include H2N-(CH2-CH
2O)n-NH2H2N
-[CH2-C(CH3)HO]n-NH2
HOOC-(CH2-CH2O
)n-COOH HOOC
-[CH2-C(CH3)HO]n-COOH, etc. In the formula, n is an integer from 1 to 1000, preferably from 10 to 100.

The reactive alkylene oxide compound is selected to have a functional group capable of reacting with the polar functional group contained in the (meth)acrylic copolymer. The amount of the reactive alkylene oxide compound used is 0.01 to 50 parts by weight, preferably 0.1 to 25 parts by weight, based on 100 parts by weight of the (meth)acrylic copolymer. The upper limit of the blending amount is limited by the function as an adhesive.

The adhesive composition of the present invention may contain crosslinking agents such as isocyanate compounds, melamine resins, epoxy resins, aziridinyl compounds, and metal chelate compounds.

The adhesive composition of the present invention may also contain other additives used in general adhesives. The adhesive composition of the present invention can be applied to a film-like substrate such as polyester, polypropylene, vinyl chloride or high-quality paper,
It is applied to a paper substrate such as art paper or coated paper to a thickness of 5 to 30 μm. The obtained adhesive sheet can be used as an adhesive for labels and stickers, tapes, building materials, packaging materials, and electronics, and should exhibit sufficient adhesive performance especially when the adherend is polyolefin. Can be done.

[0016]

[Examples] The present invention will be explained below with reference to Examples. In the examples, parts represent parts by weight, and % represents weight %.

[0017]

[Example 1] Solution polymerization was carried out using the following monomer formulation in a 3L 4-necked flask equipped with a stirrer, thermometer, condenser, and dropping funnel to obtain a (meth)acrylic copolymer. butyl acrylate
76 copies
Methyl methacrylate
20 parts acrylic acid
Part 3 Benzoyl peroxide
1 part ethyl acetate
18
0 parts A solution containing 100 parts of the obtained (meth)acrylic copolymer was added with amino group-containing reactive polyethylene glycol (manufactured by Kawaken Chemical Co., Ltd., trade name: PEO Amine 400).
12 parts and 1 part of a diisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L) to obtain an adhesive composition.

[0018]

[Example 2] Solution polymerization was carried out in the same manner as in Example 1 except that the monomer formulation was changed to the following. 2-ethylhexyl acrylate
47 parts n-butyl acrylate
15 parts 2-hydroxyethyl acrylate 3 parts
glycidyl acrylate
15 parts vinyl acetate
20 parts Azobisisobutyronitrile 0.2
part ethyl acetate
180 copies
To a solution containing 100 parts of the obtained (meth)acrylic copolymer, 7 parts of carboxyl group-containing reactive polyethylene glycol (manufactured by Kawaken Chemical Co., Ltd., trade name: PEO acid 1000) and a diisocyanate-based compound (manufactured by Nippon Polyurethane Co., Ltd.,
A pressure-sensitive adhesive composition was obtained by blending 0.2 part of Coronate L (trade name: Coronate L).

[0019]

[Example 3] Solution polymerization was carried out in the same manner as in Example 1 except that the following monomer formulation was changed. 2-ethylhexyl acrylate
49 parts acrylic acid
8 parts methacrylic acid
Part 2 Glycidyl methacrylate
1 part methyl acrylate
40 copies
Azobisisobutyronitrile
0.2 parts ethyl acetate

180 parts A solution containing 100 parts of the obtained (meth)acrylic copolymer was added with amino group-containing reactive polyethylene glycol (manufactured by Kawaken Chemical Co., Ltd., trade name: PE
A pressure-sensitive adhesive composition was obtained by blending 18 parts of Oamine 6000).

[0020]

[Example 4] Ion-exchanged water was added to a 3L 4-necked flask equipped with a stirrer, thermometer, condenser, and dropping funnel.
250 copies
Polyoxyethylene alkylphenol ether
Part 2 Ammonium sulfate salt of polyoxyethylene alkylphenol ether

2 parts were charged, the temperature was raised while stirring, and when the temperature reached 80°C, 1 part of ammonium persulfate was added, and the following pre-emulsion that had already been emulsified was added dropwise. 2-ethylhexyl acrylate
790 parts methyl methacrylate
80 parts 2-hydroxyethyl acrylate 30
Part methacrylic acid
30 parts vinyl acetate
70 parts Polyoxyethylene alkylphenol ether 13 parts Ammonium sulfate salt of polyoxyethylene alkylphenol ether


13 parts ion exchange water
4
41 parts ammonium persulfate
4
The temperature inside the flask was kept at 80°C and the mixture was added dropwise over 3 hours. Thereafter, 1 part of ammonium persulfate is added twice every hour to complete the polymerization. The resulting milky white emulsion had a solid content of 60%, a pH of 3.0, and a viscosity of 210.
0cps (BL type rotational viscometer, #3 rotor/30rp
m). A preservative, an antifoaming agent, aqueous ammonia, and a thickener were added to this milky white emulsion, and 15 parts of an amino group-containing reactive polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., trade name: IONET YB-400) was added. , viscosity 15,000 to 20,000 cps (BL type rotational viscometer,
#4 rotor/12 rpm) was obtained.

[0021]

[Example 5] In a flask similar to Example 4,
ion exchange water
250 parts Polyoxyethylene alkylphenol ether 2 parts
Ammonium sulfate salt of polyoxyethylene alkylphenol ether

2 parts were charged, the temperature was raised while stirring, and when the temperature reached 80°C, 1 part of ammonium persulfate was added, and the following pre-emulsion that had already been emulsified was added dropwise. 2-ethylhexyl acrylate
790 parts methyl methacrylate
80 parts 2-hydroxyethyl acrylate 30
Part Glycidyl methacrylate
20 copies
acrylic acid
10 copies
vinyl acetate
70 copies
Polyoxyethylene alkylphenol ether
13 parts Ammonium sulfate salt of polyoxyethylene alkylphenol ether

Part 13
ion exchange water
441 copies
ammonium persulfate
The temperature inside the 4-part flask was maintained at 80° C. and the mixture was added dropwise over 3 hours. Thereafter, 1 part of ammonium persulfate is added twice every hour to complete the polymerization. The obtained milky white emulsion had a solid content of 60%, a pH of 4.0, and a viscosity of 2800 cps (BL type rotational viscometer, #4 rotor/30 rpm). A preservative, an antifoaming agent, aqueous ammonia and a thickener were added to this milky white emulsion, and a reactive polyethylene glycol containing amino groups (manufactured by Kawaken Chemical Co., Ltd., trade name: PEO acid 4) was added.
00) 7 parts to give a viscosity of 15,000 to 20,000c.
ps (BL type rotational viscometer, #3 rotor/12 rpm)
An aqueous emulsion type adhesive composition was obtained.

[0022]

[Comparative Example 1] (Meth)acrylic copolymer 10 of Example 1
A pressure-sensitive adhesive composition was obtained by blending 12 parts of polyethylene glycol (PEG400) which does not have a reactive functional group and 1 part of a diisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L) into a solution containing 0 parts. Ta.

[0023]

[Comparative Example 2] (Meth)acrylic copolymer 10 of Example 2
A pressure-sensitive adhesive composition is prepared by blending 7 parts of polyethylene glycol (PEG1000), which does not have a reactive functional group, and 0.2 parts of a diisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate L) into a solution containing 0 parts. I got it.

[0024]

[Comparative Example 3] (Meth)acrylic copolymer 10 of Example 3
A pressure-sensitive adhesive composition was obtained by blending 1.5 parts of a diisocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) into a solution containing 0 parts.

[0025]

Comparative Example 4 An aqueous emulsion composition was obtained in the same manner as in Example 4. This aqueous emulsion composition contains polyethylene glycol (PEG400) having no reactive functional groups.
) to obtain an aqueous emulsion type adhesive composition.

[0026]

Comparative Example 5 An aqueous emulsion composition was obtained in the same manner as in Example 5. An aqueous emulsion type adhesive composition was obtained without adding a reactive alkylene oxide to this aqueous emulsion composition. The adhesive composition obtained in each example was
A commercially available polyethylene laminate high-quality paper separator was coated with a dry weight of 20 to 30 g/m 2 , dried at 100° C. for 2 minutes, and then reversed onto a commercially available cast coated paper to prepare a coated product. The adhesive strength, holding power, etc. of this coated product were measured based on JIS-Z-0237. The coated product left at 23°C-65%RH is a normal coated product, and the coated product is left in a high temperature and high humidity atmosphere of 50°C-95%RH for 2 days, and then the coated product is left at 23°C-65%RH.
The coated product left for one day was treated as a humidified aged coated product, and the humidity deterioration resistance was evaluated using the value of the adhesive strength of the humidified aged coated product relative to the adhesive strength of the normal coated product as the humidified aged retention rate. That is, the closer this value is to 100%, the lower the resistance to humidity deterioration is, and the closer this value is to 0%, the greater the resistance to humidity deterioration. Next, this normally coated product was left in an atmosphere at -5°C for one day, and then -5°C
It was pasted under the following conditions and rolled crimped according to JIS.
After 24 hours, the adhesive strength was measured to evaluate its low temperature properties. Furthermore, curved surface adhesion was evaluated by pasting this normally coated product onto a polyethylene round rod with a diameter of 10 mm at a π/2 angle and measuring the degree of peeling using a ruler. That is,
If the degree of peeling is large, the curved surface adhesion is poor.
If there is no peeling at all, the curved surface adhesion is good. The results are shown in Table 1.

[0027]

[Table 1]

[0028]

[Effects of the Invention] The present invention provides an adhesive that has excellent adhesion to various adherends, especially polyolefins, curved surface adhesion, and moisture deterioration resistance when coated paper is used as the surface substrate. .

Claims (1)

[Claims] Claim 1: A reactive alkylene oxide represented by the following structural formula is added to 100 parts by weight of a (meth)acrylic copolymer containing a (meth)acrylic acid alkyl ester as a main component and a functional group-containing monomer as a copolymerization component. Compound 0.0
An adhesive composition containing 1 to 50 parts by weight. R-(CH2-CXHO)n-R (However, n is an integer from 1 to 1000, R is an amino group or a carboxyl group, and X is a hydrogen atom or a methyl group.)