JPH1192728A - Adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition which contains a water-soluble filler, exhibits tight bonding force and good adhesion to various materials in an ordinary state, is used to bond members to give a structure which, if necessary, can be separated into the initial members by immersion in water or hot water and, if necessary, is separated into the starting materials. SOLUTION: The amount of the water-soluble filler used is 0.1-200 pts.wt. per 100 pts.wt. solid mater of the adhesive base resin. The water-soluble filler, which can be used is one which is solid at the service temperature of the adhesive, can be converted into a powder or particles and can be rapidly dissolved in water or hot water. It is exemplified by an inorganic acid salt, an organic acid (salt), a chelating agent (salt), a polysaccharide or a sugar alcohol. The adhesive which can be used is a hot melt adhesive, an organic-solvent-based adhesive, a one-package polymerization-curable adhesive, a two-package adhesive, a pressure-sensitive adhesive or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for bonding a plurality of constituent members to form a predetermined structure, and exhibits a predetermined bonding strength in a normal use state.
The present invention relates to an adhesive composition in which, when a structure is immersed in water or heated water, the adhesive force is rapidly reduced, and it is easy to separate the structure into its original components.

[0002]

2. Description of the Related Art Conventionally, there have been known a large number of adhesives for bonding a plurality of constituent members made of the same or different materials to form a structure having a predetermined function. As such adhesives, those classified into solvent-based adhesives, water-based adhesives, hot-melt adhesives, and polymerizable adhesives from the aspect of form are used.

[0003]

In recent years, environmental issues have become more important, and in order to greatly reduce waste,
BACKGROUND ART There is an international demand that machinery and equipment, automobiles and other articles and structures be collected and re-used. The recycling law has been enacted in Japan as well, and bonded structures are separated for each material.
It is required to be collected and reused. Especially,
Separation into materials and components is required when a consumer disposes of used articles. However, most of the conventionally known and used adhesives have been improved only for the purpose of strongly bonding,
Examining the possibility of separation into components, it can be pointed out that there are problems in the following points.

(1) Hot Melt Adhesive The hot melt adhesive utilizes the property that a thermoplastic resin is melted by heating, and therefore can be separated into its original constituent members by heating. .
However, heating at a minimum heating temperature of 80 ° C. requires high-temperature heating for ordinary consumers, and it is particularly difficult to separate thick members to which heat is hardly transmitted.

(2) Solvent-based adhesive A solvent-based adhesive is an adhesive obtained by dissolving a resin in an organic solvent such as a thinner, and a structure bonded by such a solvent-based adhesive dissolves the adhesive resin. It is possible to separate the member into a member that is immersed in an organic solvent. However, in consideration of the danger of fire, the effect on the human body, etc., there are too many problems for ordinary consumers to always keep organic solvents. In addition, as in the case of the hot melt adhesive, the bonding area is large, and when the substrate is thick, it takes a long time to dissolve the adhesive in the center. Furthermore, depending on the material forming the constituent members, the material may be dissolved in an organic solvent and may not meet the purpose of recovery and reuse.

(3) Aqueous adhesive An adhesive using water as a medium, such as starch paste, aqueous polyvinyl alcohol solution, or vinyl acetate emulsion. A structure bonded using such an adhesive is cured by an adhesive. It is possible to separate it into the original members by immersing it in water, excluding those of the nature. However, such adhesives are limited in the material that can be bonded as compared with hot-melt adhesives and solvent-based adhesives, and their use is also limited due to low adhesive strength.

[0007] In addition to the above-mentioned adhesives, there is also known a technique of using a pressure-sensitive adhesive or a double-sided pressure-sensitive adhesive tape so as to detachably attach the constituent members. However, general pressure-sensitive adhesives have low adhesive strength and cannot firmly fix members. On the other hand, a double-sided adhesive tape having a strong adhesive force is also known, but in the case of member separation, it requires a correspondingly large amount of force,
It is difficult for the general consumer to separate.

It is an object of the present invention to have a strong adhesive force in a normal state, a good adhesiveness to a wide range of materials, and, if necessary, to be immersed in water or hot water even for a general consumer. It is an object of the present invention to provide an adhesive composition that can be separated into the original constituent members and separated for each raw material.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an adhesive composition, comprising a water-soluble filler, and immersing an adherend adhered using the adhesive composition in water or heated water. In this case, the object to be bonded can be easily separated into the original member.

When the structure bonded using the adhesive of the present invention is immersed in water due to the presence of the water-soluble filler, the water-soluble filler is dissolved in water, and the adhesive layer becomes porous, and As a result, the adhesive force is rapidly reduced, and the original constituent members can be easily separated and collected.

Here, “easy” means a time factor,
Includes ease of use for both mechanical elements, meaning that when the structure to be discarded is immersed in water or heated water, it can be separated in as short a time as possible and at most within a few hours. It also means that the original component can be separated by a simple operation such as twisting or hitting with a relatively small force instead of a strong external force.

It is presumed that the use of the adhesive of the present invention facilitates the separation into the constituent members constituting the structure due to the following effects. In other words, when immersed in water or heated water, the water-soluble filler quickly absorbs and dissolves water, and the filler layer mainly dissolves in water. As the area decreases and the contact area with water increases, the adhesive strength decreases, and the resin itself, which is the base of the adhesive, absorbs water and the strength decreases, and the adhesive force decreases due to the fact that the material is easily broken by external force. It is considered that the action such as reduction is partially or comprehensively exerted.

In the present invention, it is preferable that the adhesive quickly changes its volume when immersed in water. Due to the change in the volume of the adhesive, voids are generated between the constituent members or shear stress is generated, and peeling of the adhesive occurs or the adhesive force is greatly reduced, so that the separation of the constituent members becomes extremely easy. In addition, here, "immediately"
Means as short as possible and as long as several hours as described above.

As the adhesive used in the present invention, an adhesive such as a hot-melt adhesive, an organic solvent-based adhesive, a one-component type polymerizable curable adhesive, or a two-component curable adhesive can be used. Not applicable to water-based adhesives. Further, the present invention can be applied to an adhesive contained in one kind of the adhesive and an adhesive tape using the same. As described above, the adhesive composition of the present invention can be composed based on various types of adhesives, and as a result, the composition can be applied to bonding of components formed from a wide variety of materials.

In the adhesive composition of the present invention, the amount of the water-soluble filler is preferably 0.1 to 200 parts by weight based on 100 parts by weight of the solid content of the adhesive base resin. If the added amount is less than 0.1 part by weight, it is difficult to separate easily even if the structure is immersed in water, and if it exceeds 200 parts by weight, the amount of the filler is too large and the adhesive strength in a normal state is sufficient. In some cases, it does not work.

The most preferred amount of the water-soluble filler is 0.1.
The amount is 1 to 100 parts by weight, and within this range, an adhesive having a suitable balance between adhesiveness and separability can be obtained.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the adhesive used in the present invention is a hot-melt adhesive, an organic solvent-based adhesive, a one-part type polymerization-curable adhesive, and a two-part curing type adhesive. An adhesive such as an adhesive or a pressure-sensitive adhesive (adhesive) can be used. Further, it can be applied to an adhesive tape using a pressure-sensitive adhesive. The following can be exemplified as a resin material constituting such an adhesive. (1) High molecular weight or relatively high molecular weight polymers (used as organic solvent-based adhesives, hot-melt adhesives, etc.) Acrylic polymers using acrylic acid or alkyl esters of methacrylic acid, poly Polyvinyl alcohol derivatives such as polyvinyl chloride and copolymers thereof, polyurethane, polyvinyl acetate, polyvinyl butyral, and polyvinyl acetal; silicone resins; rubber polymers such as natural rubber and polychloroprene; EVA resins; SBS resins; SIS resins; Derivatives and the like. (2) Multi-component mixed type adhesive using oligomer Two-part curable epoxy resin, two-part curable urethane resin, and the like. (3) One-component adhesives Cyanoacrylate adhesives, etc.

The water-soluble filler used in the present invention includes:
At least at the use temperature of the adhesive, it is solid and can be powdered or formed into particles, and those which rapidly dissolve in water or heated water can be used without any particular limitation. Particularly preferred are the following, which may be used alone or 2
A mixture of more than one species can be used. Inorganic salts Sodium chloride, potassium chloride, magnesium chloride, sodium nitrate, potassium nitrate, ammonium nitrate, sodium nitrite, potassium nitrite, sodium sulfate, potassium sulfate, magnesium sulfate, potassium alum and the like. Organic acids and salts thereof Organic acids such as malic acid, citric acid, sorbic acid, glutamic acid, ascorbic acid, pantothenic acid, adipic acid, oxalic acid, and succinic acid, and alkali metal salts or ammonium salts thereof. Chelating agents and salts thereof Ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid and alkali metal salts, alkaline earth metal salts and ammonium salts thereof. Polysaccharides Sucrose, granulated sugar, galactooligosaccharide, isomaltooligosaccharide, trehalose, maltose, palatinose,
Xylo-oligosaccharides and the like. Sugar alcohols xylitol, pentaerythritol, monoglycuronide glycyrrhizin, maltitol, raffinose and the like. Others Aspartame, stevia, urea, polydextrose, sodium bicarbonate, saccharin, etc.

Among the above-mentioned water-soluble fillers, when a structure formed by bonding is immersed in water, water easily penetrates into the adhesive layer and the filler dissolves quickly without forming a mushroom. It is preferable that the structure be separated into the original components very easily.

Examples of additives used in the organic solvent solution type adhesive include, in addition to organic solvents, viscosity modifiers such as thixotropic agents, plasticizers, coloring agents, weathering agents, discoloration inhibitors, curing agents, Catalysts and the like are exemplified, as examples of additives used in the hot melt type adhesive, tackifier,
Examples include discoloration inhibitors, antioxidants, viscosity modifiers, plasticizers, waxes, and the like. Other types of adhesives can use the required additives depending on their properties.

In order to adhere the components using the adhesive of the present invention, an adhesive applying means known to those skilled in the art, for example, a dispenser in the case of a solution adhesive or a one-component type instant adhesive, In the case of a hot melt adhesive, for example, an applicator or the like can be used.

[0022]

Embodiments of the present invention will be described below. In this embodiment, a glass decorative container formed by bonding a glass container and a decorative member formed of resin will be described as an example.

Table 1 shows Example 1 and Example 2
The adhesive compositions of Examples 11 to 11 and Comparative Examples 1 to 4 were adjusted according to the compositions shown in Table 2. The compounding amounts are indicated in parts by weight. For the adhesive, use a kneading device that can be sealed, first knead the resin uniformly with an organic solvent if necessary, and then add a water-soluble filler and knead the mixture until uniform. Adjusted by

[0024]

[Table 1] (Note) *): The compounding amount is shown in terms of solid content.

[0025]

[Table 2]

The materials listed in Table 2 are as follows. Acrylic resin: Alon S-1015 (Toa Gosei Chemical) Urethane resin: Olester M54-80A (Mitsui Toatsu Chemical) Epoxy resin: Epoki 877 (Mitsui Toatsu Chemical) Erythritol: (Nikken Chemical) Acrylamide, EDTA, NaCl: Reagents (Nacalai Tesque)

(Adjustment of Test Specimen) A test accessory 1 made of ABS resin having the shape shown in FIG. 1 was used as a model of the accessory. The test attachment 1 has a thick cylindrical shape,
The inner cylinder has a shape through which a cylindrical projection 11 of the test glass member 9 described below is inserted, and a groove 3 for passing a continuous wire is provided on the inner cylinder surface, the bottom surface, and the outer cylinder surface. The total weight of the test accessory 1 is 2 g.

A test glass member 9 having the shape shown in FIG. 1 was used as a glass container model. The test glass member 9 includes a columnar portion 13 and a columnar protrusion 11 provided on one end surface of the columnar portion 13, and has a total weight of 70 g.
It is.

The adhesion between the test accessory and the test glass member is as follows:
An adhesive is applied to two portions of the bottom of the test attachment member at the middle portions 5 and 5 of the groove on the bottom surface where the wire insertion groove is provided so that the weight becomes 0.05 g per one portion, and the test glass member 9 is coated with the adhesive. The columnar projection 11 was inserted into the inner cylinder of the test accessory 1 and adhered, left in an oven at 50 ° C. for 24 hours to complete the adhesion, and a test sample was prepared and used for the following evaluation.

(Evaluation of Adhesive Performance) As shown in FIG. 2, the cylindrical portion 13 of the test glass member of the test sample was fixed by a fixing means such as a vise, and the wire inserted into the groove 3 of the test accessory was lifted. The adhesive strength under normal conditions was measured.

(Evaluation of Peeling Performance) As shown in FIG. 3, the test sample was hung by a wire inserted into the groove 3 of the test accessory 1 of the test sample, and the entire test sample was immersed in a water tank adjusted to a predetermined temperature. Peelability was evaluated. For Example 1, the temperature of the water to be immersed was 15 ° C., 4
Four levels of 0 ° C., 60 ° C., and 80 ° C. were adopted, and the time required for the test glass member to fall off naturally after immersion was measured. Example 2
After immersion in water at 15 ° C. for 12 hours, adhesive strength (peeling strength) of each of Comparative Examples 1 to 4 was measured by the method used in the evaluation of the adhesive performance.

(Evaluation Results) The evaluation results of Example 1 are shown in Table 3.
The results of Examples 2 to 11 and Comparative Examples 1 to 4 are shown together with the composition in the lower part of Table 2. The evaluation in Table 2 is based on the following criteria. [Evaluation of adhesion performance] ：: 3.0 kg or more: 2.0 or more and less than 3.0 kg △: 1.0 or more and less than 2.0 kg ×: less than 1.0 kg [Release performance evaluation] ：: less than 0.5 kg ○: 0.5 kg or more and less than 2.0 kg △: 2.0 kg or more and less than 2.5 kg ×: 2.5 kg or more The evaluation is preferably such that the adhesion performance under normal conditions is stronger, that is, the peel strength is higher, and the peeling when immersed in water is preferable. The performance is based on the fact that it is preferable that the material peels off in a short time and that the peel strength is small.

[0033]

[Table 3]

From the above evaluation results, the composite container using the adhesive to which the water-soluble filler is added as in the present invention has a strong adhesive force in a normal state which is not different from the conventional one, but when immersed in water or hot water, It can be seen that the glass and the accessory can be easily separated.

[Brief description of the drawings]

FIG. 1 is a diagram showing shapes of a test glass member and a test accessory member used for evaluation of adhesion performance and evaluation of peeling performance, and an adhesion state of these members.

FIG. 2 is a diagram showing a method for measuring adhesive performance in a normal state.

FIG. 3 is a view showing a state in which an adhesive sample is immersed in water for evaluation of peeling performance.

Claims (2)

[Claims] 1. An adhesive composition, comprising a water-soluble filler, wherein a structure to which a component member is adhered using the adhesive composition is immersed in water or heated water. An adhesive composition which can be easily separated into the constituent members. 2. The adhesive composition according to claim 1, wherein the amount of the water-soluble filler is 0.1 to 200 parts by weight based on 100 parts by weight of the solid content of the adhesive base resin.