KR101348516B1 - Aqueous emulsion pressure sensitive adhesive composition using reactive nonionic surfactant - Google Patents

Abstract

(상기 화학식 1에서, n은 5 내지 45의 정수이고, R은 알킬기이며, x는 수소(H)이다.)There is little adhesive deterioration due to aging, and discloses an environmentally friendly and harmless aqueous adhesive composition having good coating properties during processing.
The aqueous adhesive composition according to the present invention comprises (a) an alkyl (meth) acrylate monomer, (b) at least one monomer among unsaturated carbonic acid and hydroxyl group-containing unsaturated monomers, (c) crosslinkable monomer and (d1) Including the reactive nonionic surfactant represented by 1, there is almost no adhesive deterioration due to aging and has an advantage of having good coating properties.
[Chemical Formula 1]

(In Formula 1, n is an integer of 5 to 45, R is an alkyl group, x is hydrogen (H).)

Description

Aqueous adhesive composition using reactive nonionic surfactant {AQUEOUS EMULSION PRESSURE SENSITIVE ADHESIVE COMPOSITION USING REACTIVE NONIONIC SURFACTANT}

FIELD OF THE INVENTION The present invention relates to reactive nonionic surfactants and, more particularly, to aqueous adhesive compositions using reactive nonionic surfactants of nonyl phenol nonaddition type.

Currently, most of the pressure sensitive adhesives commonly used in adhesive tapes and labels are solvent-based and emit volatile organic compounds (VOCs). Therefore, the technical improvement from the solvent type to the water-based adhesive has been progressed by strengthening the environmental regulations recently. Although some aqueous acrylic emulsion adhesives are produced in Korea, it is pointed out as a problem that the adhesive properties due to aging are greatly reduced in addition to water resistance and heat resistance in comparison with physical properties of solvent-type adhesives.

Techniques relating to an aqueous pressure-sensitive adhesive composition are disclosed in Korean Patent Registration No. 10-0177541. Here, the surfactant used in the emulsion polymerization process in the production of the water-based pressure-sensitive adhesive plays an important role in the emulsion stability, it can be said to be a factor that can significantly affect the physical properties of the pressure-sensitive adhesive and coating properties during processing. Nonionic, anionic and cationic surfactants are used as the type of surfactant used in the emulsion polymerization.

Nonionic surfactants known to date include polyoxyethylene nonylphenyl acer or oxyphenyl acer reactive surfactants. These surfactants have a problem in that they include benzene rings as hormonal disturbances.

The above-mentioned surfactant is a hormonal disruptor, and it is a substance that inhibits normal processes by synthesizing, accumulating, secreting, in vivo transport, receptor binding, and hormonal action in vivo, which affects homeostasis, reproduction and behavior of a living body. Regulation is increasingly being tightened.

Therefore, there is little adhesive deterioration due to aging and the development of an environmentally friendly and harmless aqueous adhesive with good coating properties during processing is required.

The present invention is to solve the conventional problems as described above, and to provide an environmentally friendly and harmless aqueous adhesive composition having excellent adhesive properties due to aging, good coating properties during processing.

An aqueous adhesive composition according to an embodiment of the present invention for achieving the above object is (a) an alkyl (meth) acrylate monomer, (b) at least one monomer among unsaturated carboxylic acid and hydroxyl-containing unsaturated monomer, and (c) It is characterized by including a crosslinkable monomer and (d1) a reactive nonionic surfactant represented by the following formula (1).

[Formula 1]

(In Formula 1, n is an integer of 5 to 45 ° ~, R is an alkyl group, x is hydrogen (H).)

The aqueous adhesive composition according to the present invention has an environmental friendliness compared to the conventional method using a nonyl phenol non-additive type surfactant, has a very low rate of tack loss due to aging, and has an advantage of having good coating properties during processing. .

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Hereinafter, the aqueous adhesive composition according to the present invention will be described in detail.

The aqueous adhesive composition according to the present invention comprises (a) an alkyl (meth) acrylate monomer, (b) at least one monomer among unsaturated carbonic acid and hydroxyl group-containing unsaturated monomers, (c) crosslinkable monomer and (d1) The reactive nonionic surfactant shown by 1 is included.

[Formula 1]

(In Formula 1, n is an integer of 5 to 45, R is an alkyl group, x is hydrogen (H).)

In addition, the composition may further include (d2) anionic surfactant together with the (d1) reactive nonionic surfactant, and may include (e) a water-soluble initiator and (f) a molecular weight modifier.

The (a) alkyl (meth) acrylate monomer used in the aqueous adhesive composition according to the present invention may be methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate. , Butyl (meth) acrylate, isobutyl acrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate , At least one selected from the group consisting of isodecyl acrylate, decyl methacrylate, dodecyl methacrylate and isobornyl methacrylate, and more preferably butyl acrylate monomer and ethyl acrylate. It may be a mixture consisting of monomers.

At least one monomer of the (b) unsaturated carbonic acid and hydroxyl group-containing unsaturated monomer used in the aqueous adhesive composition according to the present invention is a composition for reinforcing adhesive strength, acrylic acid, itaconic acid, maleic acid, fumaric acid, methacrylic Acid, ethyl methacrylate, hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate It is preferable to include 1 or more types selected, More preferably, acrylic acid can be used.

In addition, the (c) crosslinkable monomer used in the aqueous adhesive composition according to the present invention is ethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol ethoxy Late diacrylate, hexanediol propoxylate diacrylate, neopentyl glycol ethoxylate diacrylate, neopentyl glycol propoxylate diacrylate, trimethyl propane ethoxylate triacrylate, trimethyl propane propoxylate triacrylic It is preferable that it contains 1 or more types chosen from the group which consists of a latex, pentaerythritol ethoxylate triacrylate, and pentaerythritol propoxylate triacrylate.

Surfactants used in the present invention include a reactive nonionic surfactant represented by the following formula (1).

[Formula 1]

(In Formula 1, n is an integer of 5 to 45, R is an alkyl group, x is hydrogen (H).)

The surfactant is a nonionic reactive nonionic surfactant of nonyl phenol (including nonyl phenol ethoxylate) non-addition type, and has excellent environmental friendliness compared to conventional surfactants. In addition, the pressure-sensitive adhesive composition using the surfactant according to the present invention has excellent adhesiveness compared to the existing pressure-sensitive adhesive composition, and has the advantage of having good coating properties during processing.

In addition, the pressure-sensitive adhesive composition according to the present invention may further include an anionic surfactant together with the reactive nonionic surfactant. By using two types of surfactants in combination than when using each surfactant alone, there is an advantage that can greatly increase the stability of the polymer emulsion.

Examples of the anionic surfactant include, but are not limited to, sulfonate carboxylate and phosphate, and known anionic surfactants may be used.

The type of the (e) water-soluble initiator used in the aqueous adhesive composition according to the present invention is not particularly limited, and a material containing at least one selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate may be used. Can be.

In addition, the (f) molecular weight modifier used in the aqueous adhesive composition according to the present invention is not particularly limited, lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, A substance comprising at least one selected from the group consisting of glycidyl mercaptan, mercapto acetic acid, 2-mercapto ethanol, 2-ethylhexyl thioglycolic acid, and 2,3-dimercapto-1-propanol can be used. Can be.

In particular, it is preferable that the aqueous adhesive composition which concerns on this invention has a particle size of 100-400 nm after emulsion polymerization. If the particle diameter is less than 100 nm, particle stability may deteriorate. If the particle diameter exceeds 400 nm, the stress of the particles may be reduced after drying, resulting in deterioration of coating properties and adhesive properties after processing.

On the other hand, the aqueous adhesive composition according to the present invention is (a) 70 to 90% by weight of the monomer, (b) 1 to 5% by weight of the monomer, 0.1 to 0.5% by weight of the (c) crosslinkable monomer, (d1) surfactant 0.1 to 1% by weight, (e) 0.01 to 0.5% by weight of water-based initiator, (f) 0.1 to 0.3% by weight of molecular weight regulator, 0.1 to 1.5% by weight of ammonia and 5 to 25% by weight of deionized water.

The aqueous adhesive composition according to the present invention (a) may comprise 70 to 90% by weight of the monomer, in particular, a mixture consisting of 60 to 75% by weight of butyl acrylate monomer, 10 to 15% by weight of ethyl acrylate monomer can do. When the butyl acrylate monomer is less than 60% by weight or when the ethyl acrylate monomer is used at less than 10% by weight, there is a problem in that the aqueous adhesive cannot secure sufficient adhesiveness. In addition, when the butyl acrylate monomer is more than 75% by weight, or when the ethyl acrylate monomer is used in more than 15% by weight there is a problem that the aqueous adhesive is excessively firm and the adhesive strength is lowered.

In addition, the aqueous adhesive composition according to the present invention may be used (b) an acrylic monomer as a monomer, the acrylic acid monomer may be used in 1 to 5% by weight. When the acrylic acid monomer is used in less than 1% by weight, there is a problem that the water-based adhesive may not secure sufficient adhesiveness, and when the acrylic acid monomer is used in excess of 5% by weight, the aqueous adhesive is excessively firm and the adhesive force is lowered. There is a problem.

In addition, the aqueous adhesive composition according to the present invention (c) 0.1 to 0.5% by weight of the crosslinkable monomer may be used. When the crosslinkable monomer is used in less than 0.1% by weight, there is a fear that the cohesive force of the pressure-sensitive adhesive composition is reduced or the heat resistance is lowered. When the crosslinkable monomer is used in an amount of more than 0.5% by weight, the adhesive strength or water resistance may be lowered or the aging of the pressure-sensitive adhesive may be caused by temperature. There is a concern. The kind of the crosslinkable monomer is not particularly limited, and a known crosslinkable monomer may be used.

In addition, the aqueous adhesive composition according to the present invention may be used in 0.1 to 1% by weight of the surfactant (d1). When the surfactant is used at less than 0.1% by weight, the water dispersibility may deteriorate. When the surfactant is used in an amount exceeding 1% by weight, the physical properties of the pressure-sensitive adhesive may be deteriorated. In particular, the adhesive strength may be reduced due to aging. . In the present invention, the surfactant may be used together with (d1) a reactive nonionic surfactant and (d2) anionic surfactant, and a mixture of the two materials may be used in an amount of 0.1 to 1% by weight.

In addition, the aqueous adhesive composition according to the present invention may comprise 0.01 to 0.5% by weight of the (e) water-soluble initiator. When the water-soluble initiator is used at less than 0.01% by weight, the degree of polymerization may decrease, and when it exceeds 0.05% by weight, the molecular weight may decrease.

In addition, the aqueous adhesive composition according to the present invention may comprise 0.1 to 0.3% by weight of (f) molecular weight regulator. When the molecular weight modifier is used in less than 0.1% by weight there is a problem that the molecular weight is difficult to control, if the content exceeds 0.3% by weight there is a fear that the heat resistance deteriorates.

On the other hand, the aqueous adhesive composition of the present invention may be used containing 0.1 to 1.5% by weight of ammonia used in the emulsion polymerization, deionized water may be used containing 5 to 25% by weight. If the amount of the ammonia water used as a post additive is less than 0.1% by weight, the pH is low and acidic. If the amount of the ammonia water used is less than 1.5% by weight, problems such as formation of aggregated particles may occur. And when the usage-amount of deionized water is less than 5 weight%, there exists a possibility that the deterioration of the reaction process by a viscosity and a problem of deposit formation may arise, and when it exceeds 25 weight%, it may become difficult to dry on post-processing.

In addition, the water-based adhesive composition according to the present invention can be used as the antifoaming agent, wetting agent, thickener, dispersant, UV stabilizer, antioxidant, filler and the like as necessary.

The aqueous adhesive composition may be formed on one or both sides of the film or sheet to produce an adhesive sheet. Specifically, the acrylic pressure-sensitive adhesive is applied to the surface of the film or sheet using a bar coder or the like, followed by drying, or the acrylic pressure-sensitive adhesive is applied to the surface of the release base material and dried, and then formed on the surface of the release base material. The layer can be transferred to a film or sheet to produce an adhesive sheet having a constant adhesive thickness.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by the following Examples.

< Examples and Comparative Examples>

[Example 1]

An adhesive sheet using the aqueous adhesive composition according to the present invention was prepared. In the emulsion polymerization method of Example 1, a pre-emulsion method was used, and in a 1 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser, about 18% of the total mass of the reactant was used. Ultrapure water and ammonium persulfate, which is 15% water-soluble initiator relative to the total amount of initiator split, are charged in advance into the reactor, nitrogen gas is injected to completely remove dissolved oxygen, etc. contained in the reactor, and the temperature is raised to about 80 ° C. Hold for 30 minutes.

70 wt% butyl acrylate monomer, 12 wt% ethyl acrylate monomer, 3 wt% acrylic acid monomer, 0.3 wt% crosslinkable monomer, 0.5 wt% surfactant, 0.2 wt% water-soluble initiator, 0.2 wt% molecular weight modifier and ultrapure water After about 10 minutes to prepare a pre-emulsion. After the temperature of the reactor reached the set temperature, a predetermined amount of preemulsion prepared in advance using a dropping funnel was added to the reactor, and the mixture was dropped at the same rate over about 3 hours while maintaining a constant stirring speed. After the dropping was completed, the mixture was aged for 2 hours, and an additional amount of redox catalyst t-butylhydroperoxide and Longalite (Rongalite; sodium formaldehyde sulfoxylate) were added to completely remove the unreacted monomer and reacted for 1 hour. I was.

After the reaction was completed, the temperature was lowered and the reactant was discharged when the temperature dropped to room temperature. Thereafter, the resin was neutralized with an aqueous 28% concentration of ammonia at room temperature and adjusted to pH 7-8.

The total amount of the surfactant during the polymerization was 0.5% by weight, and the ratio of the ionic surfactant and the nonionic surfactant was 2: 8. As the nonionic surfactant, ER-10 reactive nonionic surfactants of ADEKA Co., Ltd. (ADEKA) of non-nonyl phenol (including nonyl phenol ethoxylate) non-addition type were used.

The prepared aqueous adhesive resin was coated by a method of coating on a release paper, followed by drying, and then laminated on one side of a vinyl chloride resin (PVC) sheet to prepare an adhesive sheet having a thickness of 55 μm of the acrylic adhesive layer.

Comparative Example 1

An aqueous adhesive composition and an adhesive sheet were prepared in the same manner as in Example 1, except that TWEEN (R) 20, a non-ionic surfactant of polysorbates of Sigma-Aldrich, was used as a surfactant. It was. In Comparative Example 1, the total amount of the surfactant was 0.5% by weight, and the ratio of the ionic surfactant and the nonionic surfactant was used at 2: 8.

[Comparative Example 2]

Example 1 except that SR-10S, a non-sulfur phenol-based reactive anionic surfactant of non-addition type phenol (including nonyl phenol ethoxylate) of Adeka, Japan, was used as a surfactant at 0.5% by weight. An aqueous adhesive composition and an adhesive sheet were prepared in the same manner.

The types and chemical structures of the surfactants used in the above Examples and Comparative Examples are shown in Table 1 below.

[Table 1]

Solid content, gel content, viscosity, particle diameter and physical properties after coating of the prepared examples and comparative examples are shown in Table 2 below.

[Table 2]

< Evaluation>

1. Evaluation of Coating Properties

When evaluating the coating properties was evaluated on a three-point scale based on the following criteria.

○: good

△: slightly bad

Ⅹ: bad

In the examples and comparative examples, the viscosity was measured using a Brookfield viscometer, and the particle diameter was measured using a Zetasizer Nano ZS90 manufactured by Malvern.

Reactive surfactants have similar properties in surface tension, emulsification, and dispersing power compared to general surfactants, but they have double bonds such as vinyl, allyl, and acryl groups in their molecular structure. When the general surfactant is used, the polymerization stability and the mechanical stability are superior.

As shown in Table 1, in the case of Example 1 using a reactive non-ionic surfactant and the particle diameter is between 100nm to 400nm, it can be seen that the polymerization stability is excellent and has the best coating properties during processing.

Comparative Example 2 used a reactive anionic surfactant, but it can be seen that the coating properties slightly poor compared to Example 1 using a reactive nonionic surfactant.

2. Peel force evaluation

1) 180 ° initial peel strength measurement

A pressure-sensitive adhesive film (2.5 cm wide and 25 cm wide) was removed from the substrate at 25 ° C. and 55% relative humidity, and after 1 day, the initial peel strength was measured according to JTS Z 0237. The base material was SUS # 304, PMMA, Glass to measure the adhesive properties according to each case.

2) Peel strength measurement after 180 ° aging

Peel strength after aging was measured in the same manner as the measurement of the initial peel strength, except that the adhesive film (2.5 cm wide and 25 cm long) was stored at 50 ° C. for 72 hours and then aged. Using SUS # 304, PMMA, and Glass as the substrate, the adhesive properties according to the case of each substrate were measured.

3) Aging rate measurement

The initial peel strength and the post-aging peel strength measured in the above were substituted into the following general formula 1, and the aging rate was measured.

[Formula 1]

% Aging = (bc) / b ⅹ100

[Table 3]

Looking at the results of Table 3, it was confirmed that Example 1 using the reactive non-ionic surfactant was superior in both room temperature and aging adhesive strength compared to the comparative examples using the conventional surfactant.

In the case of Comparative Example 1, although the initial adhesive strength itself is not high, it can be seen that the aging rate is relatively good, and Comparative Example 2 is excellent in the initial adhesive strength, but it can be confirmed that the aging rate is high. In Comparative Example 2, SR-10S, which is a reactive anionic surfactant, was used. Since it has a double bond in chemical structure, the initial peel strength was higher than that of Comparative Example 1 using TWEEN (R) 20. The aging adhesive is believed to have fallen due to the influence of ionic substances.

Claims (11)

(a) alkyl (meth) acrylate monomers;
(b) at least one monomer among unsaturated carboxylic acids and hydroxyl-containing unsaturated monomers;
(c) crosslinkable monomers; And
(d1) a reactive nonionic surfactant represented by the following Chemical Formula 1;
An aqueous adhesive composition further comprising (e) a water-soluble initiator and (f) a molecular weight regulator.

[Chemical Formula 1]

(In Formula 1, n is an integer of 5 to 45, R is an alkyl group, x is hydrogen (H).)
The method of claim 1,
The composition
(d2) An aqueous adhesive composition further comprising an anionic surfactant.
The method of claim 1,
Aqueous adhesive composition, characterized in that the diameter of the particles formed when the composition is emulsion polymerization is in the range of 100 ~ 400 nm.
The method of claim 1,
The monomer of (a) is
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, t-butyl methacrylate, pentyl meta Acrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, isodecyl acrylate, decyl methacrylate, dodecyl methacrylate and isobornyl methacrylate An aqueous adhesive composition, characterized in that it comprises one or more selected from the group consisting of.
The method of claim 1,
The monomer of (b) is
Acrylic acid, itaconic acid, maleic acid, fumaric acid, methacrylic acid, ethyl methacrylic acid, hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacryl Aqueous, adhesive composition comprising at least one member selected from the group consisting of 2-hydroxypropyl methacrylate.
The method of claim 1,
The monomer of (c) is
Ethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol ethoxylate diacrylate, hexanediol propoxylate diacrylate, neopentyl glycol ethoxylate Diacrylate, neopentyl glycol propoxylate diacrylate, trimethyl propane ethoxylate triacrylate, trimethyl propane propoxylate triacrylate, pentaerythritol ethoxylate triacrylate and pentaerythritol propoxylate triacrylic Aqueous aqueous adhesive composition, characterized in that it comprises one or more selected from the group consisting of a rate.
delete The method of claim 1,
(E) the water-soluble initiator
An aqueous adhesive composition comprising one or more selected from the group consisting of potassium persulfate, sodium persulfate and ammonium persulfate.
The method of claim 1,
The molecular weight regulator (f)
Lauryl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, glycidyl mercaptan, mercapto acetic acid, 2-mercapto ethanol, thioglycolic acid 2-ethylhexyl, 2 An aqueous adhesive composition comprising at least one member selected from the group consisting of 3-dimercapto-1-propanol.
The method of claim 1,
The composition
70 to 90% by weight of the monomer (a), 1 to 5% by weight of the monomer (b), 0.1 to 0.5% by weight of the (c) crosslinkable monomer, 0.1 to 1% by weight of the surfactant (d1), (e) An aqueous adhesive composition comprising 0.01 to 0.5% by weight of a water-soluble initiator, (f) 0.1 to 0.3% by weight of a molecular weight regulator, 0.1 to 1.5% by weight of ammonia water and 5 to 25% by weight of deionized water.
An adhesive sheet comprising a pressure-sensitive adhesive layer formed using the aqueous adhesive composition according to any one of claims 1 to 6 and 8 to 10.