TWI414575B - Water-whitening resistant, removable emulsion pressure sensitive adhesives - Google Patents

Abstract

This invention relates to a water-whitening resistant, removable emulsion pressure sensitive adhesive, which comprising (a) 70 to 85 phr monomer of alkyl acrylate containing 4 to 12 carbon atoms in the alkyl group; (b) 1 to 8 phr monomer of &agr; , &bgr; unsaturated carboxyl group; (c) 5 to 20 phr copolymerizable monomer, which Tg is about 5 DEG C to 150 DEG C; (d) 0.1 to 3.0 phr reactive surfactant; (e)0.1-3.0 phr external crossliking agent and add deionized water, initiator and buffer, by emulsion polymerization.

Description

Water-resistant whitening and removable emulsified pressure-sensitive adhesive

The present invention is directed to providing a water-resistant whitening and removable emulsifying pressure sensitive adhesive which can be applied to label and tape products.

Recently, environmental awareness has become increasingly high. Any industrial product that is harmful to the ecological environment is facing the fate of updating or gradually being eliminated. Even the adhesives that are closely related to daily life are no exception. Commonly used solvent-based adhesive products will gradually withdraw from the stage, and environmentally-friendly emulsified adhesive products are also rapidly developing. Among the emulsified adhesives, acrylic pressure sensitive adhesives are the most widely used, and are particularly used in label and tape products, among which emulsified acrylic pressure sensitive adhesives (hereinafter referred to as Latex), after the transparent label or substrate is made, it should be attached to outdoor advertising signs, bus advertisements or glass windows of convenience stores. It needs to have a low adhesion, generally 50-450g/in, in order to tear off and replace.

As one of the characteristics of the removable emulsified pressure-sensitive adhesive, the adhesive force cannot rise with the increase of the adhesive time. Otherwise, when the label or the substrate is torn off, the latex is likely to remain on the object, which is called residual glue phenomenon. . The second characteristic is that it remains unchanged in the long-term high-humidity environment and remains transparent.

According to the current technology, it is not easy to achieve the aforementioned characteristics one and two, because the latex is added with a lot of water-sensitive substances such as a surfactant, a hydrophilic monomer and a water-soluble electrolytic substance during polymerization. Such materials still have an interface between the emulsion particles when the latex forms a transparent film upon drying. These interfaces provide a path for water molecules to diffuse into the film. As water diffuses into the film, the refractive index at the interface between the emulsion particles becomes larger, resulting in light scattering and whitening, resulting in reduced aesthetics and poor vision. In order to solve the above problems, the present invention provides a water-resistant whitening and removable emulsified pressure-sensitive adhesive.

It is an object of the present invention to provide a water-resistant whitening and removable emulsifying pressure sensitive adhesive.

The emulsified pressure-sensitive adhesive composition comprises: (a) 70 to 85 phr (part per hundred) of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group; (b) an α,β unsaturated carboxylic acid group ( Carboxyl group) 1~8 phr of copolymerizable monomer; (c) 5~20 phr of copolymerizable monomer with glass transition temperature (Tg) of 5 °C~105 °C; (a)+(b)+(c) The amount is 100 phr. Relative to (a) + (b) + (c) = 100 phr; use (d) a reactive surfactant in an amount of 0.1 to 3.0 phr; and add an appropriate amount of deionized water, an initiator and a buffer The agent is produced by a general emulsion polymerization method. Further, (e) an external crossliking agent is used in an amount of 0.1 to 3.0 phr. The water-resistant whitening and removable emulsified pressure-sensitive adhesive of the present invention has a solid content of 30 to 70% by weight and a glass transition temperature (Tg) of -20 ° C to -50 ° C.

A composition for water-resistant bleaching and removable emulsified pressure-sensitive adhesive of the present invention comprises:

(a) "Acrylate monomer having 4 to 12 carbon atoms in the alkyl group" means butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, isodecyl acrylate or lauryl acrylate They may be used alone or in combination of two or more. Among them, butyl acrylate or 2-ethylhexyl acrylate is preferred, and its amount ranges from 70 to 85 phr.

(b) "A copolymerizable monomer containing an α,β unsaturated carboxyl group" means acrylic acid, methacrylic acid, maleic acid, fumaric acid, itacon Acidic acid, crotonic acid, monoalkyl maleic acid, or monoalkyl fumaric acid may be used alone or in combination of two or more. Among them, acrylic acid and methacrylic acid are preferred, and the amount thereof ranges from 1 to 8 phr.

(c) "Copolymerizable monomer having a glass transition temperature of 5 ° C to 105 ° C" means vinyl acetate, alkyl methacrylate having a carbon number of 1 to 4, acrylonitrile ( Acrylonitrile) or styrene may be used singly or in combination of two or more kinds, preferably vinyl acetate, methyl methacrylate, ethyl methacrylate or butyl methacrylate alone or in combination of two or more. Used in combination, in an amount ranging from 5 to 20 phr.

(d) "Reactive surfactant" means RS-30, JS2 (Sanyo Chemical, Japan), S-180 (Kao, Japan), SE-10N, NE-10, NE20, NE30 ( Asahi Chemical Industry Co., Ltd., Japan), MS-60 (Japanese emulsifier, Japan) The reactive surfactant is used in an amount ranging from 0.1 to 3.0 phr, relative to 100 phr of total (a) + (b) + (c).

(e) "External bridging agent" means API-EC10 (epoxy functional crosslinking resin, Advanced Polymer, INC.), APR-500 (oxazoline functional polymer solution, Advanced Polymer, INC.), API-BI792 (Waterborne blocked- Polyisocyanate crossinking agent, Advanced Polymer, INC.). The amount of the external bridging agent ranges from 0.1 to 3.0 phr relative to the total amount of 100 phr of (a) + (b) + (c).

The emulsified pressure-sensitive adhesive composition of the present invention can participate in the reaction by at least one initiator, buffer, and deionized water. The use of the initiator is in the range of 0.2 to 0.6 phr relative to the total amount of 100 phr of (a) + (b) + (c), such as potassium persulfate, sodium persulfate, ammonium persulfate, and benzoic acid peroxide. Benzyl peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, and the like. The buffer is used in an amount ranging from 0.2 to 0.6 phr, based on the total amount of 100 phr of (a) + (b) + (c), such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogencarbonate, phosphoric acid. Sodium and so on.

The emulsified pressure sensitive adhesive of the present invention is subjected to an emulsion polymerization reaction in a reaction tank, and the above-mentioned (a), (b) and (c) monomers and the above (d) reactive surfactant are mixed and added in an appropriate amount. Deionized water, an initiator and a buffer are co-presented, and the reaction is initiated by heating and heating to form latex particles. The reaction temperature is 70 ° C to 85 ° C, the reaction time is 5 to 10 hours, and the mixture is cooled to room temperature, and then the above (e) an external bridging agent is added. The solid content of the product is 30-70% by weight, and the glass transition temperature (Tg) is -20 ° C ~ -50 ° C.

Next, the following is an illustration of the preparation of a water-resistant bleaching and removable emulsified pressure-sensitive adhesive of the present invention:

[Example 1]

First, 205.2 g of butyl acrylate monomer [composition (a)], 4.5 g of acrylic monomer [composition (b)], 4.5 g of methacrylic acid monomer [composition (b)], and 10.0 g of methyl methacrylate alone The body [composition (c)] and 8.2 g of butyl methacrylate monomer [composition (c)] were uniformly stirred to prepare an A solution.

Another 86.2 g of deionized water and 9.0 g of MS-60 reactive surfactant [composition (d)] were uniformly stirred to prepare a B solution.

The pre-emulsified C solution was prepared by continuously stirring the solution A into the solution B.

Further, 97.4 g of deionized water, 1.1 g of sodium hydrogencarbonate and 1.1 g of potassium persulfate were uniformly stirred to prepare a D solution.

Another 5.5 g of deionized water and 0.2 g of potassium persulfate were uniformly stirred to prepare an E solution.

An emulsion polymerization apparatus comprising: a stirrer, a thermometer, a heater, a reflux condenser, a five-neck and a one-liter round bottom bottle. When the emulsion polymerization apparatus is heated to 75 ° C - 78 ° C, the D solution is poured and maintained for 10-15 minutes. The pre-emulsified C solution was then fed in 240 minutes. Then, the temperature is raised to 80 ° C -82 ° C, and then the E solution is fed for 20 minutes and maintained for 90 minutes, then cooled to room temperature, and then added 2.5 g of APR-500 external bridging agent [composition (e)], which can be formed The emulsified pressure sensitive adhesive of the present invention has a solid content of 55.0% and a glass transition temperature (Tg) of -45 °C.

The emulsified pressure sensitive adhesive of the present invention is applied to a 40 μm transparent PVC film at room temperature, placed in an oven (80 ° C × 5 minutes), coated to a thickness of 22 μm, and then bonded to a release liner to form a label. (label) product, the physical property test results refer to the following Table 2.

[Example 2]

First, 135 g of 2-ethylhexyl acrylate monomer [composition (a)], 70.2 g of butyl acrylate monomer [composition (a)], 4.5 g of acrylic monomer [composition (b)], 4.5 g The acrylic monomer [composition (b)], 12 g of methyl methacrylate monomer [composition (c)], and 15 g of butyl methacrylate monomer [composition (c)] were uniformly stirred to prepare an A solution.

Another 86.2 g of deionized water and 9.0 g of MS-60 reactive surfactant [composition (d)] were uniformly stirred to prepare a B solution.

The pre-emulsified C solution was prepared by continuously stirring the solution A into the solution B.

Further, 97.4 g of deionized water, 1.1 g of sodium hydrogencarbonate and 1.1 g of potassium persulfate were uniformly stirred to prepare a D solution.

Another 5.5 g of deionized water and 0.2 g of potassium persulfate were uniformly stirred to prepare an E solution.

An emulsion polymerization apparatus comprising: a stirrer, a thermometer, a heater, a reflux condenser, a five-neck and a one-liter round bottom bottle. When the emulsion polymerization apparatus is heated to 75 ° C - 78 ° C, the D solution is poured and maintained for 10-15 minutes. The pre-emulsified C solution was then fed in 240 minutes. Then, the temperature is raised to 80 ° C -82 ° C, and then the E solution is fed for 20 minutes and maintained for 90 minutes, then cooled to room temperature, and then added 2.5 g of APR-500 external bridging agent [composition (e)], which can be formed The emulsified pressure sensitive adhesive of the present invention has a solid content of 55.0% and a glass transition temperature (Tg) of -49 °C.

The emulsified pressure sensitive adhesive of the present invention is applied to a 40 μm transparent PVC film at room temperature, placed in an oven (80 ° C × 5 minutes), coated to a thickness of 22 μm, and then bonded to a release liner to form a label. (label) product, the physical property test results refer to the following Table 2.

[Comparative Example 1]

First, 205.2 g of butyl acrylate monomer [composition (a)], 4.5 g of acrylic monomer [composition (b)], 4.5 g of methacrylic acid monomer [composition (b)], and 10.0 g of methyl methacrylate alone The body [composition (c)] and 8.2 g of butyl methacrylate monomer [composition (c)] were uniformly stirred to prepare an A solution.

Another 100 g of deionized water and 1.8 g of polyoxyethylene nonylphenyl ether and 6.0 g of polyoxyethylene nonylphenyl ether sulfate ammonium surfactant were uniformly stirred to prepare a B solution.

The pre-emulsified C solution was prepared by continuously stirring the solution A into the solution B.

Further, 97.4 g of deionized water, 1.1 g of sodium hydrogencarbonate and 1.1 g of potassium persulfate were uniformly stirred to prepare a D solution.

Another 5.5 g of deionized water and 0.2 g of potassium persulfate were uniformly stirred to prepare an E solution.

An emulsion polymerization apparatus comprising: a stirrer, a thermometer, a heater, a reflux condenser, a five-neck and a one-liter round bottom bottle. When the emulsion polymerization apparatus is heated to 75 ° C - 78 ° C, the D solution is poured and maintained for 10-15 minutes. The pre-emulsified C solution was then fed in 240 minutes. Then, the temperature is raised to 80 ° C -82 ° C, and then the E solution is fed for 20 minutes and maintained for 90 minutes, then cooled to room temperature, and then added 2.5 g of APR-500 external bridging agent [composition (e)], which can be formed The emulsified pressure sensitive adhesive of the present invention has a solid content of 55.0% and a glass transition temperature (Tg) of -45 °C.

The emulsified pressure sensitive adhesive of the present invention is applied to a 40 μm transparent PVC film at room temperature, placed in an oven (80 ° C × 5 minutes), coated to a thickness of 22 μm, and then bonded to a release liner to form a label. (label) product, the physical property test results refer to the following Table 2.

[Comparative Example 2]

First, 135 g of 2-ethylhexyl acrylate monomer [composition (a)], 70.2 g of butyl acrylate monomer [composition (a)], 4.5 g of acrylic monomer [composition (b)], 4.5 g The acrylic monomer [composition (b)), 12 g of methyl methacrylate monomer [composition (c)], and 15 g of butyl methacrylate monomer [composition (c)] were uniformly stirred to prepare an A solution.

Another 100 g of deionized water and 1.8 g of polyoxyethylene nonylphenyl ether and 6.0 g of polyoxyethylene nonylphenyl ether sulfate ammonium surfactant were uniformly stirred to prepare a B solution.

The pre-emulsified C solution was prepared by continuously stirring the solution A into the solution B.

Further, 97.4 g of deionized water, 1.1 g of sodium hydrogencarbonate and 1.1 g of potassium persulfate were uniformly stirred to prepare a D solution.

Another 5.5 g of deionized water and 0.2 g of potassium persulfate were uniformly stirred to prepare an E solution.

An emulsion polymerization apparatus comprising: a stirrer, a thermometer, a heater, a reflux condenser, a five-neck and a one-liter round bottom bottle. When the emulsion polymerization apparatus is heated to 75 ° C - 78 ° C, the D solution is poured and maintained for 10-15 minutes. The pre-emulsified C solution was then fed in 240 minutes. Then, the temperature is raised to 80 ° C -82 ° C, and the E solution is fed for 20 minutes and maintained for 90 minutes, and then cooled to room temperature to form the emulsified pressure sensitive adhesive of the present invention, which has a solid content of 55.0%. The glass transition temperature (Tg) was -49 °C.

The emulsified pressure sensitive adhesive of the present invention is applied to a 40 μm transparent PVC film at room temperature, placed in an oven (80 ° C × 5 minutes), coated to a thickness of 22 μm, and then bonded to a release liner to form a label. (label) product, the physical property test results refer to the following Table 2.

[Production of test samples]

The emulsion pressure sensitive adhesive obtained in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention was applied using a 40 μm transparent PVC film, and the coating thickness was 22 μm, and the adhesion of the steel sheet was performed by the following test method (performance No. 1). , glass plate adhesion (performance number 2), water resistance whitening test (performance number 3), the physical property test results refer to the following Table 2.

【testing method】

1. Steel plate adhesion: (performance number 1): According to ASTM D-1000 standard, the sample placement conditions are divided into 23 ° C / 65% RH (relative humidity) / 1 day and 70 ° C / 90% RH / 7 days .

2. Glass plate adhesion: (Performance No. 1): According to ASTM D-1000 standard, the sample placement conditions are divided into 23 ° C / 65% RH (relative humidity) / 1 day, and 70 ° C / 90% RH / 7 days.

3. Water whitening test (performance No. 3): The sample size is 25mm×200mm, immersed in a water bath of 23°C/24 hours, observe the change of transparency, which is divided into 1~5 grades, 1 is completely transparent, 2 is slight Whitening, 3 is partial whitening, 4 is a lot of whitening, and 5 is completely whitened (milky). Acceptable levels are 1, 2, and 3.

As can be seen from Table 2, Examples 1 and 2 have excellent adhesion to the steel sheet and adhesion of the glass sheet, and the adhesion is 0.17 to 0.27 kg/in, and has excellent water whitening resistance. In Comparative Example 1, although the adhesion of the steel sheet and the adhesion of the glass sheet were all in the range of 0.23-0.30 kg/in, the water whitening resistance was poor. In Comparative Example 2, the adhesion of the steel sheet and the adhesion of the glass sheet were poor in the high temperature and high humidity (70 ° C / 90% RH) for 7 days, and the water whitening resistance was poor.

Thus, it can be seen that the water-resistant whitening and removable emulsified pressure-sensitive adhesive of the present invention has the following advantages: excellent steel sheet adhesion (performance number 1) and glass sheet adhesion (performance number 2) and water-resistant whitening test ( Performance number 3). The transparent label or substrate made of the emulsified pressure-sensitive adhesive of the invention can be applied to products such as outdoor advertising signs, bus advertisements or glass windows of convenience stores, and has the invention patent requirements such as industrial utilization, novelty and progress. .

The above embodiments are only intended to illustrate the objects, technical contents, features and effects of the present invention, and are not intended to limit the scope of the present invention.

Claims (7)

A water-resistant whitening and removable emulsified pressure-sensitive adhesive comprising: (a) 70-85 phr of an acrylate monomer having 4 to 12 carbon atoms in an alkyl group; (b) containing α, β-unsaturated a carboxyl group may copolymerize 1-8 phr of the monomer; (c) 5-20 phr of a copolymerizable monomer having a glass transition temperature (Tg) of 5 ° C to 105 ° C; (d) a reactive interface Reactive surfactant 0.1-3.0 phr; (e) external crossliking agent 0.1-3.0 phr; wherein the total amount of (a), (b) and (c) is 100 phr, (d) and (e) is based on the calculation of a total amount of 100 phr of (a), (b) and (c), and an appropriate amount of deionized water, an initiator and a buffer are obtained by emulsion polymerization; wherein (d) Reactive surfactants are ELEMINOL RS-30, ELEMINOL JS2, LATEMUL S-180 (Japan Kao Corporation), ADEKAREASOAP SE-10N, ADEKAREASOAP NE-10, ADEKAREASOAP NE20, ADEKAREASOAP NE30 (Japan Asahi Chemical Industry Co., Ltd.) or SINONATE MS- 60 (Zhongri Synthetic Chemical Co., Ltd.); and (e) external bridging agent API-EC10 (epoxy functional cross-linking resin, ADVANCED POLYMER, USA), APR-500 (oxazoline functional polymerization) Solution, ADVANCED POLYMER, USA) or API-BI792 (aqueous block-polyisocyanate cross-linking agent, ADVANCED POLYMER, USA). The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 1, wherein (a) the acrylate monomer having 4 to 12 carbon atoms in the alkyl group comprises butyl acrylate and acrylic acid-2. Ethylhexyl ester, octyl acrylate, decyl acrylate, isodecyl acrylate and acrylic lauric acid. The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 2, wherein (a) an acrylate single system butyl acrylate or acrylic acid-2 having 4 to 12 carbon atoms in the alkyl group; Ethylhexyl ester. The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 1, wherein (b) the α,β unsaturated carboxyl group-polymerizable monomer includes acrylic acid and methyl group. Acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, monoalkyl maleic acid, and monoalkyl One of mono alkyl fumaric acid. The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 4, wherein (b) the α,β unsaturated carboxylic acid group can copolymerize a single system of acrylic acid or methyl group. acrylic acid. The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 1, wherein (c) the copolymerizable monomer having a glass transition temperature (Tg) of 5 ° C to 105 ° C comprises vinyl acetate. An alkyl methacrylate, an acrylonitrile, or a styrene having a carbon number of 1 to 4 alone or a mixture of two or more kinds thereof. The water-resistant whitening and removable emulsified pressure-sensitive adhesive according to claim 6 wherein (c) a copolymerizable single-system vinyl acetate having a glass transition temperature (Tg) of 5 to 105 ° C, Methyl methacrylate, ethyl methacrylate, and butyl methacrylate are used singly or in combination of two or more kinds.