Adhesive for paper-covered box, paper-covered box, and method for producing paper-covered box

Abstract

To achieve an adhesive for paper-covered boxes that exhibits enhanced durability under high temperature and high humidity environments, against warping or peeling of decorative paper, as compared with traditional adhesives, and which enables the manufacture of a paper-covered box.SOLUTION: An adhesive for paper-covered boxes comprises a main agent and a curing agent, wherein the main agent is a glue-gelatin solution containing at least one of glue and gelatin, and the curing agent is a water-soluble epoxy compound that dissolves in water at a room temperature of 25°C, and the addition amount of the water-soluble epoxy compound is 0.15 wt.% or more and 8 wt.% or less relative to the solid content of the glue or gelatin in the glue-gelatin solution.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive for pasted boxes, which is used for pasting decorative paper in the manufacturing process of pasted boxes.

Background Art

[0002] A pasted box is a decorative box manufactured by pasting decorative paper (such as surface paper with various colors, patterns or designs) on a fabric box (core material) made of cardboard or the like with an adhesive. Pasted boxes are widely used as packaging boxes for relatively expensive products such as food, watches, and jewelry.

[0003] In the manufacture of pasted boxes, hide glue - gelatin - based adhesives are often used as adhesives for pasted boxes. Hide glue - gelatin - based adhesives are one type of protein - based adhesives. Hide glue - gelatin - based adhesives are liquid adhesives and are used after being heated. In the manufacturing process of pasted boxes, when the hide glue - gelatin - based adhesive applied to the back surface of the decorative paper is cooled to 30 - 40°C, it gels due to the sol - gel change, so tack force can be obtained in a short time. In this specification, the term "hide glue" includes not only the case where it contains both hide glue and gelatin, but also the case where it contains only hide glue among hide glue and gelatin, and the case where it contains only gelatin among hide glue and gelatin.

[0004] Patent Document 1 describes a hardening type adhesive for bookbinding in which the main agent is a fish glue - gelatin solution and the hardening agent is a solution containing a compound that cross - links fish glue - gelatin. This fish glue - gelatin - based adhesive forms a three - dimensional cross - linked structure by subjecting the main agent to a cross - linking reaction using the hardening agent. By this reaction, the rise of adhesive strength is accelerated, and the formed adhesive film becomes tough, making it difficult for the main agent to soften, melt, elute, or deteriorate due to heat, moisture, etc., and it becomes excellent in all of heat resistance, moisture resistance, and durability. Patent Document 1 lists, as compounds that cross - link fish glue - gelatin, aldehyde compounds, tannins, epoxy compounds, isocyanate compounds, alum having trivalent chromium and / or trivalent aluminum, zirconium salts, etc. In the examples described in Patent Document 1, dialdehyde starch, tannin, bisphenol A type epoxy, etc. are used as the hardening agent.

[0005] Patent Document 2 describes a tissue adhesive that is prepared by mixing an adhesive component containing an aqueous solution of fish gelatin and a hardening component containing an aqueous solution of a water - soluble cross - linking molecule and applying it to tissues. Patent Document 2 lists, as water - soluble cross - linking molecules, Polyethyleneglycol di - succinimidyl succinate, succinimidylated poly - L - glutamic acid, starch with aldehyde groups introduced, dextran with aldehyde groups introduced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, when the pasted box is exposed to a high-temperature and high-humidity environment, it returns to a sol state due to the sol-gel change, resulting in a decrease in adhesive strength. In recent years, due to the rising temperature in summer, the environment to which the pasted box is exposed has become more severe. Therefore, with conventional glue-gelatin-based adhesives, when the pasted box is exposed to a high-temperature and high-humidity environment, there is a risk that the decorative paper may float from the cardboard box or the edge of the cosmetic box may peel off (see Comparative Example 6).

[0008] Here, in addition to the requirement for durability against floating and peeling of the decorative paper, the adhesive for the pasted box needs to satisfy at least two conditions as manufacturing conditions: the workability of coating and the adhesive strength at the timing of pasting the decorative paper. This will be explained below.

[0009] In the manufacture of the pasted box, although a certain viscosity of the adhesive for the pasted box is required (for example, a viscosity of about 10,000 mPa·s), if the viscosity of the adhesive for the pasted box is too high, it becomes difficult to perform the process of applying the adhesive to the decorative paper. The viscosity of the adhesive for the pasted box is required to be a viscosity that allows the coating work to be possible. For example, when an automatic coater is used in the manufacture of the pasted box, the adhesive is applied to the roller of the coater, and the adhesive is applied to the decorative paper from the roller. However, if the viscosity is high, it becomes difficult to apply the adhesive to the decorative paper with the roller of the coater.

[0010] In addition, as methods for reducing the viscosity of the adhesive, there are a method of adding water and a method of heating the adhesive solution. In the former case, since it is accompanied by a decrease in the solid content in the glue-gelatin-based adhesive, it leads to poor adhesion. In the latter case, since glue-gelatin is a protein and is basically vulnerable to heat and accompanied by a decrease in molecular weight, this also leads to poor adhesion.

[0011] In addition, a certain length of open time is required for pasting the decorative paper onto the fabric box. The open time is the time during which the adhesive is applied and then left open until pasting. In the case of conventional hide-glue / gelatin-based adhesives (adhesives for pasting boxes), the open time is 10 seconds or more. For adhesives with a short open time, the adhesive strength required for initial adhesion cannot be obtained at the pasting timing of the decorative paper. After pasting the decorative paper, even if the decorative paper can be pasted somehow, there is a risk that the decorative paper will easily lift or peel off even in a room-temperature environment.

[0012] When a crosslinking agent is used in a hide-glue / gelatin-based adhesive, the durability in a high-temperature and high-humidity environment is improved. However, the viscosity increases and the open time may become short. The present invention has been made in view of such circumstances, and an object thereof is to realize an adhesive for pasting boxes that has improved durability in a high-temperature and high-humidity environment against the lifting and peeling of the decorative paper and enables the manufacture of pasting boxes.

Means for Solving the Problems

[0013] As a result of intensive research on an adhesive for pasting boxes using hide-glue / gelatin as the main ingredient, the inventor of the present application has found that when a water-soluble epoxy compound is used as a crosslinking agent in a predetermined content, the durability of the decorative paper against lifting and peeling in a high-temperature and high-humidity environment and the above-mentioned two manufacturing conditions (coating workability and adhesive strength at the pasting timing of the decorative paper) can be achieved simultaneously. When an isocyanate compound, an epoxy compound other than water-soluble, or a water-soluble resin compound other than epoxy (water-soluble oxazoline compound, water-soluble carbodiimide compound) is used as the crosslinking agent, the above-mentioned compatibility cannot be achieved. The first invention based on these findings includes a main agent and a curing agent. The main agent is a hide-glue / gelatin solution containing at least one of hide-glue and gelatin as the main component, and the curing agent is a water-soluble epoxy compound that dissolves in water at room temperature of 25°C. The addition amount of the water-soluble epoxy compound is 0.15% by weight or more and 8% by weight or less based on the solid content of hide-glue / gelatin in the hide-glue / gelatin solution, and it is an adhesive for pasting boxes.

[0014] In the second invention, based on the first invention, when 10 parts by mass of a water-soluble epoxy compound is added to 90 parts by mass of water at room temperature of 25°C, the dissolution rate of the water-soluble epoxy compound in water is defined as the water solubility rate, and the water solubility rate of the water-soluble epoxy compound is 20% or more.

[0015] In the third invention, based on the second invention, the water solubility rate of the water-soluble epoxy compound is 60% or more.

[0016] In the fourth invention, based on the first invention, the water-soluble epoxy compound has two or more epoxy groups in the molecule.

[0017] The fifth invention is a pasted box in which a decorative paper and a fabric box are adhered by an adhesive layer formed by curing the adhesive for pasted boxes according to the first to fourth inventions.

[0018] The sixth invention is a method for manufacturing a pasted box, which includes a coating step of applying an adhesive for pasted boxes obtained by mixing a main agent and a curing agent to the back surface of a decorative paper, and a pasting step of pasting the decorative paper to a fabric box after the coating step. The main agent is a glue-gelatin solution containing at least one of glue and gelatin as a main component, the curing agent is a water-soluble epoxy compound that dissolves in water at room temperature of 25°C, and the addition amount of the water-soluble epoxy compound is 0.15% by weight or more and 8% by weight or less based on the solid content of the glue-gelatin in the glue-gelatin solution.

Advantages of the Invention

[0019] According to the present invention, by using a glue-gelatin-based adhesive as the main agent and a water-soluble epoxy compound as the cross-linking agent in a predetermined content, as described above, an adhesive for pasted boxes can be obtained that achieves both durability against floating and peeling of the decorative paper in a high-temperature and high-humidity environment and the above-described two manufacturing conditions. According to the present invention, it is possible to realize an adhesive for pasted boxes with improved durability against floating and peeling of the decorative paper in a high-temperature and high-humidity environment compared to the conventional ones and enable the manufacture of pasted boxes.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the following embodiments are examples of the present invention and are not intended to limit the scope of the present invention, its applications, or its uses.

[0021] [Regarding the Adhesive] This embodiment is an adhesive for a pasted box (hereinafter referred to as "this adhesive") used for pasting decorative paper (surface paper) in the process of creating a pasted box. This adhesive is a glue - gelatin - based adhesive containing a main agent and a curing agent. This adhesive is a liquid adhesive. Note that the "glue - gelatin - based adhesive" is an adhesive containing one or both of glue and gelatin as the main component of the main agent.

[0022] The main agent is a solution (hereinafter sometimes referred to as "glue - gelatin solution") containing at least one of glue and gelatin as the main component. The raw materials of glue and gelatin, which are the solid components of the glue - gelatin solution, are not particularly limited, and the same ones as those of ordinary adhesives for pasted boxes (for example, cowhide, cow bone, pigskin, pig bone, fish skin, etc.) can be used. The solvent of the main agent is not particularly limited, and water can be used. Other water - soluble solvents may be contained in the solvent of the main agent.

[0023] To obtain the main agent, a glue solution may be used alone, a gelatin solution may be used alone, or a mixture of these may be used. Also, to obtain the main agent, a commercially available glue - gelatin - based adhesive containing other components may be used.

[0024] The hardener is a water-soluble epoxy compound that dissolves in water at room temperature of 25°C. The water-soluble epoxy compound is a compound that has an epoxy group and is soluble in water by itself. The water-soluble epoxy compound serves as a crosslinking agent and crosslinks the animal glue - gelatin. By using the water-soluble epoxy compound as the hardener, through the crosslinking reaction, the adhesive strength, heat resistance, moisture resistance, and durability of the animal glue - gelatin (hereinafter referred to as "adhesive strength and durability, etc.") are increased. Therefore, under high temperature and high humidity, the occurrence of lifting and peeling of the decorative paper on the pasted box is suppressed.

[0025] In this adhesive, the content (addition amount) of the water-soluble epoxy compound is 0.15 wt% or more and 8 wt% or less based on the solid content of the main agent (animal glue - gelatin). Incidentally, this content is preferably 0.3 wt% or more and 7 wt% or less. When the content is less than 0.15 wt%, a sufficient crosslinking reaction does not occur, and the degree of improvement in adhesive strength and durability, etc. is small. Also, when the content exceeds 8 wt%, the viscosity increases, making it difficult to apply the adhesive. In addition, the open time becomes short, and the adhesive strength at the level required for initial adhesion cannot be obtained.

[0026] Here, when a water-insoluble epoxy compound or a water-dispersed epoxy compound is used as the hardener, by crosslinking the animal glue - gelatin with the hardener, the adhesive strength and durability, etc. of the animal glue - gelatin are increased. However, as the animal glue - gelatin becomes insoluble in water and the viscosity increases so much that the adhesive cannot be applied. Also, a strong film is formed on the roller of the coating machine, and it takes a long time to clean the coating machine. In addition, the open time becomes short, and the adhesive strength at the level required for initial adhesion cannot be obtained either.

[0027] On the other hand, in this adhesive using a water-soluble epoxy compound as a curing agent at a predetermined content, the glue gelatin crosslinked by the curing agent dissolves in water, unlike a water-insoluble epoxy compound or a water-dispersible epoxy compound, so an increase in the viscosity of the adhesive is suppressed. Therefore, this adhesive can be applied. Further, this adhesive is also suppressed from forming a strong film on the roller of the coater, and after the coating is completed, the roller can be cleaned without requiring a long time. Also, shortening of the open time is suppressed, and an adhesive strength at a level necessary for initial adhesion can be obtained.

[0028] As the water-soluble epoxy compound, it is preferable to use one having two or more epoxy groups in the molecule (a bifunctional epoxy compound or a polyfunctional epoxy compound). Examples of the water-soluble epoxy compound having one epoxy group in the molecule include phenol (EO) 5 glycidyl ether and lauryl alcohol (EO) 15 glycidyl ether and the like can be used. Examples of the water-soluble epoxy compound having two or more epoxy groups in the molecule include ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether and the like can be used. Note that, as the crosslinking agent, a plurality of types of water-soluble epoxy compounds may be used in combination. In that case, the plurality of types of water-soluble epoxy compounds may be composed only of a water-soluble epoxy compound having one epoxy group in the molecule (a monofunctional epoxy compound), or may be composed only of a water-soluble epoxy compound having two or more epoxy groups in the molecule (a polyfunctional epoxy compound), or may be configured to include both a monofunctional epoxy compound and a polyfunctional epoxy compound.

[0029] When a water-soluble epoxy compound having two or more epoxy groups in the molecule is used, compared with the case of using a water-soluble epoxy compound having one epoxy group in the molecule, the cross-linking of the nikawa gelatin as the main agent is promoted, and the adhesive strength and durability of this adhesive are further increased. Therefore, the occurrence of floating and peeling of the decorative paper is further suppressed.

[0030] The water solubility rate of the water-soluble epoxy compound is preferably 20% or more, more preferably 40% or more, and still more preferably 60% or more. In the examples described later, it has been confirmed that the higher the water solubility rate, the better the durability of the decorative paper against floating and peeling, the workability of coating, and the cleanability after coating, and an adhesive for pasting boxes can be obtained. The "water solubility rate" is the dissolution rate (mass%) of the water-soluble epoxy compound with respect to water when 10 parts by mass of the water-soluble epoxy compound is added to 90 parts by mass of water at room temperature of 25°C.

[0031] [Regarding the pasting box and the manufacturing method of the pasting box] The pasting box is one in which decorative paper is pasted on a fabric box. For example, the fabric box has a substantially rectangular parallelepiped container part with an open upper side and a substantially rectangular parallelepiped lid part with an open lower side.

[0032] The manufacturing method of the pasting box is basically the same for both the container part and the lid part. The manufacturing method of the pasting box includes a coating step of applying an adhesive for pasting boxes (this adhesive) obtained by mixing a main agent and a curing agent to the back surface of the decorative paper, and a pasting step of pasting the decorative paper to the fabric box after the coating step, thereby manufacturing the container part or the lid part. The main agent is a nikawa gelatin solution, and the curing agent is a water-soluble epoxy compound. The addition amount of the water-soluble epoxy compound is 0.15% by weight or more and 8% by weight or less with respect to the solid content of nikawa gelatin in the nikawa gelatin solution. After the pasting step, the adhesive solidifies by drying. This adhesive is classified as a dry-curing type.

[0033] The cosmetic paper is obtained by cutting paper into a shape having a bottom surface and four side surfaces. The fabric box is obtained by performing a cutting process of manufacturing the fabric by cutting paper such as cardboard into a shape having a bottom surface and four side surfaces, and an assembling process of fixing the side surfaces of the fabric after the cutting process with tape or the like.

[0034] Also, the coating process can be performed using an automatic coating machine. Regarding the production timing of the present adhesive, the present adhesive may be produced by mixing the glue - gelatin solution and the water - soluble epoxy compound in a tank such as an automatic coating machine, or the present adhesive produced by previously mixing the glue - gelatin solution and the water - soluble epoxy compound may be supplied to the above - mentioned tank.

Example

[0035] Examples of the present invention will be described. Note that the present invention is not limited to the examples as long as the gist thereof is not exceeded.

[0036] Examples 1 - 17 are adhesives obtained by mixing a main agent and a curing agent with the compositions of the components and weight percentages shown in Table 1. In each example, a glue - gelatin solution with a glue - gelatin content of 60% by weight is used as the main agent. In each example, a water - soluble epoxy compound is used as the curing agent, and the content (addition amount) of the water - soluble epoxy compound relative to the solid content of the glue - gelatin is in the range of 0.15% by weight or more and 8% by weight or less.

[0037] Comparative Examples 1 - 5, 7 - 8 are adhesives obtained by mixing a main agent and a curing agent with the compositions of the components and weight percentages shown in Table 2. Comparative Example 6 is an adhesive using only the main agent with the components and weight percentages shown in Table 2. In Comparative Examples 1 - 3, a water - insoluble epoxy compound is used as the curing agent. In Comparative Example 4, a water - dispersed epoxy compound is used as the curing agent. In Comparative Example 5, a water - soluble epoxy compound with a water solubility rate of 99% is used as the curing agent, but the addition amount of the water - soluble epoxy compound relative to the solid content of the glue - gelatin is 8% by weight or more. In Comparative Example 6, no curing agent is used. In Comparative Examples 7 - 8, a water - soluble resin compound other than the epoxy compound is used as the curing agent.

[0038]

Table 1

[0039]

Table 2

[0040] In the examples and comparative examples, for the fish glue - gelatin solution, a commercially available industrial - grade powdered gelatin dissolved in warm water to a concentration of 60% was used. For the water - soluble epoxy compound, in Example 1 and 10, for sorbitol polyglycidyl ether, Denacol (registered trademark) EX - 614 manufactured by Nagase ChemteX Corporation was used; in Example 2 and 11, for glycerol polyglycidyl ether, Denacol EX - 313 manufactured by the same company was used; in Example 3, for glycerol polyglycidyl ether, Denacol E314 manufactured by the same company was used; in Example 4, for diglycerol polyglycidyl ether, Denacol EX - 421 manufactured by the same company was used; in Example 5 and 12, for polyglycerol polyglycidyl ether, Denacol EX - 512 manufactured by the same company was used; in Example 6, for ethylene glycol diglycidyl ether, Denacol EX - 810 manufactured by the same company was used; in Example 7, for polyethylene glycol diglycidyl ether, Denacol EX - 850 manufactured by the same company was used; in Example 8, for polypropylene glycol diglycidyl ether, Denacol EX - 941 manufactured by the same company was used; in Example 9, 13, and 14, for polypropylene glycol diglycidyl ether, Denacol EX - 920 manufactured by the same company was used; in Example 15, for phenol (EO) 5For the glycidyl ether, Denacol EX-145 manufactured by the company was used; for the sorbitol polyglycidyl ether of Example 16, EX-612 manufactured by the company was used; for the trimethylolpropane polyglycidyl ether of Example 17, EX-321 manufactured by the company was used; for the glycerol polyglycidyl ether of Comparative Example 5, EX-313 manufactured by the company was used. For the water-insoluble epoxy compound, for the sorbitol polyglycidyl ether of Comparative Example 1, EX-622 manufactured by the company was used; for the trimethylolpropane polyglycidyl ether of Comparative Example 2, EX-321L manufactured by the company was used; for the pentaerythritol polyglycidyl ether of Comparative Example 3, EX-411 manufactured by the company was used. For the water-dispersible epoxy compound, for the cresol novolak type epoxy dispersion of Comparative Example 4, EM-160 manufactured by the company was used. For the water-soluble oxazoline compound of Comparative Example 7, Epocros WS-500 manufactured by Nippon Shokubai Co., Ltd. was used. For the water-soluble carbodiimide compound of Comparative Example 8, Carbodilite V-02 manufactured by Nisshinbo Chemical Inc. was used.

[0041] <Test 1: Workability Test> To evaluate the workability of coating, it was confirmed whether the adhesive could be coated on the facing paper by a coater. In Tables 1 and 2, those that could be coated were evaluated as "〇", those that had a relatively high viscosity of the adhesive but could be coated with difficulty were evaluated as "△", and those that could not be coated due to significant thickening or generation of gelified products were evaluated as "×".

[0042] <Test 2: Coater Cleanability Test> To evaluate the coater cleanability, it was confirmed whether the adhesive filling tank and roller of the coater could be easily washed with water. In Tables 1 and 2, those that could be easily washed were evaluated as "〇", those that could be washed but not easily were evaluated as "△", and those that required a significantly long time for washing due to being insoluble in water were evaluated as "×".

[0043] <Test 3: Initial Adhesion Test> To evaluate the initial adhesion, after pasting the decorative paper coated with the adhesive onto the fabric box, it was immediately checked whether the decorative paper peeled off. In Tables 1 and 2, those for which the decorative paper could be smoothly pasted were evaluated as "〇", those that had difficulty pasting the decorative paper but obtained the adhesive strength at the level required for initial adhesion were evaluated as "△", and those for which the decorative paper peeled off immediately were evaluated as "×". Also, those for which evaluation was impossible were designated as "-".

[0044] <Test 4: Anti-lifting and peeling test (Part 1)> To evaluate the anti-lifting and peeling of the decorative paper, after leaving the pasted box in an environment of 50°C and 80% RH for one day, it was checked whether the edge of the decorative paper peeled off from the sticker. In Tables 1 and 2, those for which the edge of the decorative paper did not peel off were evaluated as "〇", those for which a part of the edge of the decorative paper peeled off were evaluated as "△", and those for which the edge of the decorative paper peeled off entirely were evaluated as "×". Also, those for which evaluation was impossible were designated as "-".

[0045] <Test 5: Anti-lifting and peeling test (Part 2)> Similar to Test 4, an anti-lifting and peeling test was conducted under the condition of a lower temperature than that in Test 4 while in a high-temperature and high-humidity environment. Specifically, after leaving the pasted box in an environment of 40°C and 80% RH for one day, it was checked whether the edge of the decorative paper peeled off from the sticker, and evaluation of "〇", "△", or "×" was performed according to the same criteria as in Test 4. This evaluation result is also shown in Tables 1 and 2.

[0046] For Examples 1 - 14, a glue gelatin solution was used as the main agent, a water-soluble epoxy compound having two or more epoxy groups in the molecule was used as the curing agent, and the addition amount of the water-soluble epoxy compound was 0.15 wt% or more and 8 wt% or less based on the solid content of the glue gelatin in the glue gelatin solution. Furthermore, when the water solubility rate of the water-soluble epoxy compound was 60% or more, the evaluation was "〇" in any of Tests 1 - 5. For Example 15, when a water-soluble epoxy compound having one epoxy group in the molecule was used as the curing agent, the evaluation of Test 1 - 3 was "〇", Test 4 was "△", and Test 5 was "〇". For Examples 16 - 17, when the water solubility rate of the water-soluble epoxy compound was 20% or more and less than 60%, the evaluation was "△" in any of Tests 1 - 5. As a result, it was confirmed that any of Examples 1 - 17 had improved durability in a high-temperature and high-humidity environment compared to conventional adhesives for pasted boxes with respect to the lifting and peeling of the decorative paper, and that the pasted boxes could be manufactured. This confirmation was made for the water-soluble epoxy compound with the lowest water solubility rate among those manufactured by Nagase ChemteX Corporation. By using a water-soluble epoxy compound as a cross-linking agent at a predetermined content, regardless of the water solubility rate, an adhesive for pasted boxes with improved durability in a high-temperature and high-humidity environment with respect to the lifting and peeling of the decorative paper and capable of manufacturing pasted boxes was confirmed to be achievable.

[0047] In addition, the water-soluble epoxy compound having two or more epoxy groups in the molecule was superior in the degree of improvement in resistance to lifting and peeling under high temperature and high humidity compared to the water-soluble epoxy compound having one epoxy group in the molecule. The water-soluble epoxy compound with a water solubility rate of 60% or more was superior in the performance of resistance to lifting and peeling and the performance in manufacturing under high temperature and high humidity compared to the water-soluble epoxy compound with a water solubility rate of 20% or more and less than 60%.

[0048] On the other hand, for Comparative Examples 1-4, when the curing agent was a water-insoluble epoxy compound or a water-dispersible epoxy compound, coating could not be performed due to significant thickening or generation of gelified products. For Comparative Example 5, when the addition amount of the water-soluble epoxy compound exceeded 8% by weight based on the solid content of the hide glue - gelatin solution, the decorative paper coated with the adhesive peeled off immediately after being bonded to the fabric box. For Comparative Example 6, when no curing agent was used, the edges of the decorative paper peeled off overall even under the high temperature and high humidity conditions of Test 5 with a room temperature of 40°C. For Comparative Examples 7-8, when using a water-soluble resin compound other than the epoxy compound, coating could not be performed due to significant thickening or generation of gelified products.

Industrial Applicability

[0049] The present invention is applicable to an adhesive for box pasting using a hide glue - gelatin solution as the main agent and the like.

Claims

1. Contains a base agent and a hardener, The base material is a glue-gelatin solution containing at least one of glue and gelatin as a main component, The curing agent is a water-soluble epoxy compound that dissolves in water at room temperature (25° C.), An adhesive for pasting boxes, wherein the amount of the water-soluble epoxy compound added is 0.15% by weight or more and 8% by weight or less based on the solid content of the glue / gelatin in the glue / gelatin solution.

2. 2. The box adhesive according to claim 1, wherein the water-soluble epoxy compound has a water-solubility of 20% or more, the water-solubility being defined as the solubility of the water-soluble epoxy compound in water when 10 parts by mass of the water-soluble epoxy compound is added to 90 parts by mass of water at room temperature 25° C.

3. The box adhesive according to claim 2 , wherein the water-soluble epoxy compound has a water solubility of 60% or more.

4. 2. The box adhesive according to claim 1, wherein the water-soluble epoxy compound has two or more epoxy groups in the molecule.

5. A pasted box, comprising a decorative paper and a fabric box adhered to each other by an adhesive layer formed by solidifying the adhesive for pasting boxes according to any one of claims 1 to 4.

6. A method for manufacturing a pasted box, comprising the steps of: A coating process in which the box adhesive obtained by mixing the base agent and the curing agent is applied to the back surface of the decorative paper; After the application process, a pasting process is performed in which the decorative paper is pasted on the fabric box, The base material is a glue-gelatin solution containing at least one of glue and gelatin as a main component, The curing agent is a water-soluble epoxy compound that dissolves in water at room temperature (25° C.), A method for manufacturing a pasted box, wherein the amount of the water-soluble epoxy compound added is 0.15% by weight or more and 8% by weight or less based on the solid content of the glue / gelatin in the glue / gelatin solution.

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