JP2001316651A - Process for dispersing hot-melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for dispersing a hot-melt adhesive used for attaching labels or protective films to substrates which allows easy dispersion of the hot-melt adhesive and therefore allows easy release of the labels or protective films from the substrates. SOLUTION: In the process for dispersing (A) a hot-melt adhesive containing (a) an ethylene/(meth)acrylate copolymer, (b) a rosin or a rosin derivative having a high acid value and (c) a wax having a high acid value in an aqueous alkaline solution, (B) a nonionic or anionic surfactant is added to the aqueous alkaline solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dispersing a hot-melt adhesive, and more particularly, to attaching a label or a protective film to a base material using a hot-melt adhesive, and thereafter, The present invention relates to a method for dispersing a hot-melt adhesive in which a hot-melt adhesive is easily dispersed when a protective film or a protective film is peeled off from a base material, thereby facilitating the peeling operation.

[0002]

2. Description of the Related Art Hot-melt adhesives have been widely used as protective materials for metal plates, bookbinding, bag-making, and cardboard. Recently, hot-melt adhesives have also been actively used as adhesives for bottle labels. We are starting. Hot-melt adhesives are characterized by excellent workability because they do not contain any water or solvent. That is, in the first stage, hot-melt adhesives are used in a coating machine called an applicator. The adhesive is melted and, in the molten state, applied directly to the adherend in advance and cooled and solidified. In the second stage of the joining, the surface is coated with the hot melt adhesive in a solidified state. The feature is that the work is completed in a short time only by pressing the body against the base material and heating / cooling.

[0003] By the way, there is an operation in which a bottle label must be removed after use and the inside and outside of the bottle must be cleaned for reuse. For this reason, casein, which is easy to peel off the label after use, has been generally used as the glue for bottle labels. However, since casein can only be used in the form of an aqueous solution, its workability is poor, such as limited pot life, and it is not only difficult to simplify the label attaching process, but it must be a natural product. Therefore, there is a problem that the quality stability is poor, the water resistance is inferior, and the decay is cheap.

[0004] In order to avoid such a problem, attempts have been made to use a hot melt adhesive which is excellent in workability, quality stability, rot resistance, etc., for bonding bottle labels. However, when a hot-melt adhesive is used as an adhesive for a bottle label, it is very difficult to remove the label after using the bottle.To use a hot-melt adhesive as an adhesive for a bottle label, the label must be peeled. Must be able to be easily implemented.

[0005]

As a method for dispersing a hot melt adhesive, for example, as disclosed in Japanese Patent Publication No. Sho 56-469, ethylene and vinyl acid and / or
Also known is a method comprising dissolving or dispersing a hot melt adhesive composed of a copolymer with acrylate or methacrylate, rosin and wax in an aqueous alkaline solution, characterized by using a surfactant in combination. I have.

In this prior art, when a used book is boiled with an aqueous alkaline solution to recycle waste paper after the hot melt adhesive is used for bookbinding, the hot melt used as the adhesive is made of alkali. Because it is difficult to dissolve or disperse in aqueous solutions, it may remain as a lump in recycled paper, making it extremely difficult to recycle waste paper.To solve this problem, use a surfactant in an alkaline aqueous solution It proposes the technology to do.

[0007] The rosin in the prior art includes natural rosin, glycerin ester rosin, pentaerythritol rosin, alicyclic hydrocarbon resin, aromatic petroleum resin, rosin maleate, and the like. Wax, petroleum wax, chlorinated paraffin,
Chlorinated diphenyl or triphenyl and the like are mentioned.

[0008] As the surfactant, permeation, wetting,
It is said that any kind of commercially available surfactants for the purpose of emulsification, dispersion and solubilization can be used, and nonionic surfactants, anionic surfactants and cationic surfactants are specifically exemplified.

On the other hand, the applicant of the present application has proposed (A) a hot-melt adhesive having high strength and excellent alkali dispersibility.
(Meth) acrylic acid polymerized unit is 15 to 40% by weight, 19
0 ° C, melt flow rate at 2160g load is 5
30 to 60% by weight of an ethylene / (meth) acrylic acid copolymer of 0 to 300 g / 10 min, (B) an acid value of 150 to 30
A rosin or rosin derivative of 0 to 15% by weight and (C) an acid value of 20 to 80;
A hot melt composition comprising 10 to 50% by weight of an acid-containing wax at a temperature of 10 ° C. has been proposed (JP-A-6-256595).

Incidentally, it has been found that the hot-melt adhesive having a large adhesive strength disclosed in Japanese Patent Application Laid-Open No. 6-256595 cannot exhibit the dispersing performance unless an appropriate aqueous alkaline solution is used. Specifically, 0.5 wt%
/ NaOH aqueous solution has the best dispersion, and if the concentration is too high or too low, the dispersion becomes worse. Further, the absolute amount of the hot melt adhesive dispersed in the alkaline aqueous solution is not always sufficient, and further improvement of the dispersing performance may be required depending on the application. In particular, the ethylene-methacrylic acid copolymer has a higher melting point and higher strength than the ethylene-acrylic acid copolymer, but the acid dissociation constant of methacrylic acid is smaller than that of acrylic acid. Was low, so improvement was sometimes required.

After recognizing the above prior art, the present inventor focused on adopting a hot-melt adhesive having a high adhesive strength disclosed in Japanese Patent Application Laid-Open No. 6-256595 as an adhesive for labels. When peeling off the label after bonding the label using this hot melt adhesive,
An attempt was made to apply the dispersion method described in JP-B-56-469.

However, when the specific hot melt adhesive of the present invention was used, the fact that only a specific surfactant exerted a dispersing effect on the aqueous alkali solution was discovered, and the present invention was achieved. Was. An object of the present invention is to provide a method for dispersing a hot-melt adhesive in which a specific hot-melt adhesive excellent as a hot-melt for a bottle label can be suitably dispersed.

[0013]

That is, the present invention is characterized by a combination of a specific hot melt adhesive and a dispersing method thereof. According to the present invention, there is provided a hot melt adhesive comprising (A) (a) an ethylene / (meth) acrylic acid copolymer, (b) a rosin or a rosin derivative having a high acid value, and (c) a wax having a high acid value. A method for dispersing a hot-melt adhesive, characterized in that (B) a nonionic or anionic surfactant is present in the aqueous alkaline solution when dispersing the same in the aqueous alkaline solution.

According to the present invention, (A) the hot melt adhesive comprises (a) 30 to 60% by weight of an ethylene / (meth) acrylic acid copolymer, and (b) rosin or a rosin derivative having a high acid value. The present invention provides a method for dispersing the hot melt adhesive comprising 15 to 60% by weight and (c) 10 to 50% by weight of a high acid wax.

Further, according to the present invention, there is provided (b) a method for dispersing the above hot melt adhesive, wherein the rosin or rosin derivative has an acid value of 150 to 300.

According to the present invention, there is further provided (c) a method for dispersing the hot melt adhesive, wherein the wax has an acid value of 20 to 150.

Further, according to the present invention, there is provided a method for dispersing the hot melt adhesive, wherein (B) a nonionic or anionic surfactant is contained in an aqueous alkaline solution in an amount of 0.01 to 3% by weight. You.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hot melt adhesive,
The present invention relates to a method for dispersing a specific hot-melt adhesive particularly suitable for labels, and is characterized by the presence of a specific surfactant in an alkaline aqueous solution.

<Structure of Hot Melt Adhesive> A first feature of the present invention resides in the use of a specific hot melt adhesive comprising the following components. The hot melt adhesive (A) of the present invention contains (a) an ethylene / (meth) acrylic acid copolymer, (b) a rosin or rosin derivative having a high acid value, and (c) a wax having a high acid value.

(A) The ethylene / (meth) acrylic acid copolymer contains 15 to 40% by weight, preferably 15 to 30% by weight of acrylic acid polymerized units at 190 ° C. and 21% by weight.
Melt flow rate at 50g load is 50 to 5
00 g / 10 min, preferably 60 to 300 ethylene / (meth) acrylic acid copolymer, and the proportion of the ethylene / (meth) acrylic acid copolymer in the hot melt adhesive is 30 to 60% by weight, preferably Is 40 to 60% by weight. (A) in hot melt adhesives
When the proportion of the component is less than the above range, an adhesive having excellent cohesion and high strength cannot be obtained, and when the amount of the component is more than the above range, the coating property tends to decrease.

The rosin or rosin derivative of the component (b) is
It acts as a compatibilizer between the component (a) and the component (c), and it is important that the component has high oxidation. The high acid value of the component (b) in the present invention is 150 to 30.
0, preferably 150 to 250,
The proportion of this component in the hot melt adhesive is 30 to 60% by weight.

When the proportion of the component (b) in the hot melt adhesive is higher than the above range, the adhesive itself tends to become brittle, and when it is smaller than the above range, the components (a) and (c) Does not sufficiently act as a compatibilizer. If the acid value is lower than the above range, the dispersibility in alkali decreases, especially the dispersibility in a high-concentration aqueous alkali solution tends to decrease, and the compatibility with the component (a) tends to decrease. Examples of such a rosin or rosin derivative include rosin, hydrogenated rosin, polymerized rosin, and acid-modified rosin.

The wax as the component (c) has the function of improving the coating properties of the adhesive and keeping the adhesive non-tacky, and this component must also have a high acid value. The high acid value of the component (c) in the present invention means 20 to 150, preferably 30 to 130, and the proportion of this component in the hot melt adhesive is 10 to 50% by weight.
It is. When the proportion of the component (c) in the hot melt adhesive is higher than the above range, the adhesive tends to be brittle, and when the ratio is less than the above range, the effect of improving the coatability of the adhesive decreases. .

If the acid value of the component (c) is lower than the above range, the alkali dispersibility, particularly in a high-concentration aqueous alkali solution, decreases. Examples of such a wax include an acid value paraffin wax, a fatty acid wax, a low melting point oxidized polyethylene wax, and a modified polyethylene wax graft-modified with an unsaturated carboxylic acid or a derivative thereof.

The hot melt adhesive of the present invention has a melt viscosity, alkali dispersibility, strength,
In addition to the above three components, small amounts of other polymers, waxes, tackifiers, antioxidants, various stabilizers, pigments, dyes, and other additives known per se for the purpose of fine adjustment of cohesiveness and the like Can be blended. Preparation of the hot melt adhesive of the present invention is a melt stirring tank known per se, a kneader,
It can be performed by a hot melt preparation device such as an extruder.

<Structure of Alkaline Aqueous Solution> The second feature of the present invention is that (B) a nonionic or anionic surfactant is present in an alkaline aqueous solution for dispersing a hot melt adhesive. To make it happen. The use of a surfactant in combination with an aqueous alkali solution for dispersing a hot melt adhesive is disclosed in Japanese Patent Publication No. 56-469 as described above.

However, according to the findings of the present inventors, it is not necessary to simply use a surfactant in an aqueous alkali solution in order to disperse the above-mentioned specific hot melt adhesive in the present invention. Alternatively, it has been found that only anionic surfactants can disperse the hot melt adhesive of the present invention.

That is, in the prior art, any surfactant was effective as long as it was a surfactant. However, the hot melt adhesive of the present invention is nonionic to an aqueous alkaline solution. Alternatively, it was found that the purpose of dispersion could not be achieved unless an anionic surfactant was present, and that the amphoteric surfactant or cationic surfactant significantly reduced the dispersion ability.

The nonionic surfactant which can be added to the aqueous alkali solution in the present invention includes polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyalkylene alkyl ether, sorbitan monolau Rate, sorbitan monostearate, sorbitan monooleate, sorbitan tristearate,
Polyoxyethylene sorbitan monolaurate, polyoxysorbitan monostearate, polyoxysorbitan monooleate, polyoxyethylene sorbite tetraoleate, glycerol monostearate, glycerol monooleate, polyoxyethylene glycol monolaurate, polyoxy Examples thereof include ethylene glycol monostearate, polyoxyethylene alkylamine, and alkyl alkanolamide. Among them, polyoxyethylene lauryl ether is easily available and has an excellent dispersing effect.

Examples of the anionic surfactant include sodium lauryl sulfate, myristic acid, triethanolamine lauryl sulfate, ammonium lauryl sulfate, sodium alkylnaphthalenesulfonate, potassium alkylphosphate, and the like. For this reason, sodium lauryl sulfate is preferably used. In addition,
The aqueous alkali solution is generally an aqueous alkali solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, and the like, and usually has an alkali concentration of about 0.1 to 5% by weight.

The concentration of the nonionic or anionic surfactant added to the aqueous alkali solution is 0.01 to 3
%, And practically about 0.02 to 2% by weight can sufficiently achieve the purpose.

[0032]

According to the present invention, a label or a protective film is attached to a substrate using a hot-melt adhesive, and then, when the label or the protective film is peeled off from the substrate, the hot-melt adhesive is used. Is easily dispersed, and a method for dispersing a hot melt adhesive which facilitates the peeling operation is provided.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. 1. Sample (1) Ethylene / (meth) acrylic acid copolymer (a) Methacrylic acid 20% by weight, MFR 300, acid value 13
0 (manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.) (b) Acrylic acid 20% by weight, MFR 300, acid value 155
(Mitsui-Dupont Polychemical Co., Ltd.) (2) Rosin Arakawa Chemical Co., Ltd. “KE-604” (acid value 240) (3) Wax Allied Signal Co., Ltd. “AC5120” (acid value 12)
0)

2. Preparation of hot melt adhesive In a 180 ° C oil bath, while dissolving and stirring rosin and wax, add ethylene / (meth) acrylic acid copolymer, and stir for about 1 hour to prepare hot melt adhesive did. Table 1 shows the blending amounts (parts by weight) of each component and the acid value of the obtained hot melt adhesive.

[0035]

[Table 1]

3. Surfactant (1) Polyoxyethylene lauryl ether; "Emulgen 120" manufactured by Kao Corporation (2) Sodium lauryl sulfate; "Emal 1" manufactured by Kao Corporation
0 ”(3) Myristic acid; manufactured by Hiroshima Wako Pure Chemical Co., Ltd. (4) Lauryl dimethylamine oxide;“ Amphitol 20N ”manufactured by Kao Corporation (5) Lauryl trimethylammonium chloride;“ Coatamine 24P ”manufactured by Kao Corporation (1) Non-ion (2) and (3) are anionic surfactants, (4) is an amphoteric surfactant, and (5) is a cationic surfactant.

4. Hot melt adhesive sample Ethylene / methacrylic acid copolymer / rosin / wax Ethylene / acrylic acid copolymer / rosin / wax

5. Dissolution conditions A predetermined amount of sample adjusted to a thickness of about 0.5 mm
The solution was added to 100 ml of an aqueous alkaline solution kept at a temperature of 100 ° C., and shaken at 1.2 times / second for 10 minutes. The surfactant was added at 0.05% by weight based on the aqueous alkali solution.
The state of dispersion was evaluated for each concentration of the alkaline solution, and the results are shown in Table 2.

<Comparative Example 1> 0.1 g of a sample of a hot melt adhesive was added to 100 ml of an aqueous alkali solution of various concentrations kept at 80 ° C., and no surfactant was added at 1.2 times / second for 10 minutes. Shake. Table 2 shows the evaluation results of the dispersion state.

Example 1 The same procedure as in Comparative Example 1 was carried out except that the surfactant (1) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Example 2> The procedure of Comparative Example 1 was repeated except that a surfactant (2) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

Example 3 The same procedure as in Comparative Example 1 was carried out except that a surfactant (3) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 2> The same procedure as in Comparative Example 1 was carried out except that a surfactant (4) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 3> The same procedure as in Comparative Example 1 was carried out except that a surfactant (5) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

Comparative Example 4 0.1 g of a hot-melt adhesive sample was added to 100 ml of an aqueous alkali solution of various concentrations kept at 80 ° C., and no surfactant was added at 1.2 times / second for 10 minutes. Shake. Table 2 shows the evaluation results of the dispersion state.

Example 4 The same procedure as in Comparative Example 4 was carried out except that surfactant (1) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Example 5> The procedure of Comparative Example 4 was repeated except that the surfactant (2) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 5> The same procedure as in Comparative Example 4 was carried out except that a surfactant (4) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 6> The procedure of Comparative Example 4 was repeated except that a surfactant (5) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 7> 0.2 g of a sample of a hot melt adhesive was added to 100 ml of an aqueous alkali solution of various concentrations kept at 80 ° C., and no surfactant was added at 1.2 times / second for 10 minutes. Shake. Table 2 shows the evaluation results of the dispersion state.

<Example 6> The procedure of Comparative Example 7 was repeated except that the surfactant (1) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Example 7> The procedure of Comparative Example 7 was repeated except that a surfactant (2) was added together with a sample of the hot melt adhesive. Table 2 shows the evaluation results of the dispersion state.

Example 8 The same procedure as in Comparative Example 7 was carried out except that a surfactant (3) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 8> The same operation as in Comparative Example 7 was carried out except that a surfactant (4) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

<Comparative Example 9> The same procedure as in Comparative Example 7 was carried out except that a surfactant (5) was added together with the hot melt adhesive sample. Table 2 shows the evaluation results of the dispersion state.

[0056]

[Table 2] In the table, 〇 means complete dissolution, and × means that there is undissolved material.

Claims (5)

[Claims] (A) (a) an ethylene / (meth) acrylic acid copolymer, (b) a rosin or rosin derivative having a high acid value,
(c) dispersing a hot melt adhesive containing a wax having a high acid value in an aqueous alkali solution, wherein (B) a nonionic or anionic surfactant is present in the aqueous alkali solution; Melt adhesive dispersion method. 2. A hot melt adhesive comprising: (a) 30 to 60% by weight of an ethylene / (meth) acrylic acid copolymer; (b) 15 to 60% by weight of a high acid value rosin or rosin derivative; (c) The method for dispersing a hot melt adhesive according to claim 1, comprising 10 to 50% by weight of a high acid value wax. 3. The method for dispersing a hot melt adhesive according to claim 1, wherein (b) the rosin or the rosin derivative has an acid value of 150 to 300. (C) The wax has an acid value of 20 to 150.
The method for dispersing a hot melt adhesive according to any one of claims 1 to 3, wherein 5. The method according to claim 1, wherein (B) the nonionic or anionic surfactant is contained in an aqueous alkali solution in an amount of 0.01 to 3% by weight.
The method for dispersing a hot melt adhesive according to any one of claims 1 to 4, which is included.