JP2008001761A - Short-time bonding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonding method which permits a sufficiently long time elapsed after adhesive application and therefore excellent workability and permits bonding excellent in water resistance performance by a short-time compaction of 3-10 min at ordinary temperature throughout a year with a water-based adhesive. <P>SOLUTION: The bonding method comprises bonding adherends at least either of which is a porous material with an acetoacetyl group-containing synthetic resin emulsion controlled to a temperature of 15 to 80°C. In a desirable embodiment, the bonding method is one wherein the acetoacetyl group-containing synthetic resin emulsion contains acetoacetylated polyvinyl alcohol. In another desirable embodiment, any of the bonding methods is one wherein the acetoacetyl group-containing synthetic resin emulsion contains a resin obtained by copolymerizing an acetoacetyl group-containing monomer with another monomer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of adhering an adherend having at least one porous material using a water-based adhesive, and can be bonded with excellent water resistance by short-time pressing for 3 to 10 minutes at room temperature throughout the year. It is what.

  In recent years, in the industry that manufactures wood products and inorganic board products, the allowable release time or closed deposition time is as long as possible in the bonding process, and bonding can be completed in a short time. Is strongly demanded. In addition, composite wood flooring and stair treads, which are Japanese Agricultural Standards (JAS) products, are veneered MDF, veneered plywood and plywood, LVL, MDF, etc. are composite bonded. It is required to have a water resistance performance.

As a method for completing the adhesion by short-time pressing, an aqueous two-component adhesive has been proposed. For example, a mixture of a neutralized aqueous solution of a synthetic polymer compound having an imide structure in the molecule and an aqueous latex such as styrene-butadiene rubber latex or polyvinyl acetate emulsion is used as the first liquid, and an aqueous polyaldehyde solution such as glyoxal is used. A liquid containing an aldehyde compound or a hydrazine compound, the first liquid being an aqueous solution or emulsion of a two-component fractional coating type aqueous adhesive (Patent Document 1) used as the second liquid or a polymer compound having an acetoacetyl group in the molecule A two-component fractional coating type adhesive composition (Patent Document 2) is known in which a second liquid is used. However, since separate application of two liquids is required, at least two adhesive application lines are required. In addition, since both have poor water resistance, the former cannot pass the JAS2 immersion peel test unless the polyfunctional epoxy resin is used as the third liquid and the latter is not used in the liquid polymeric methylene diphenyl diisocyanate as the third liquid. In this case, it is necessary to perform operations such as measurement and mixing of the adhesive, and the bonding process becomes more complicated. Furthermore, it is known that the second and third liquids of the former adhesive composition have high skin irritation, and there is a drawback that a significant rash occurs although there are individual differences in contact.
JP-A-56-90867 JP-A-60-202176

  In addition, for the purpose of completing the adhesion by pressing for a short time, one or both of the adherends are preheated by installing a hot press or a drying furnace before applying the adhesive. Both the press and the drying furnace have been pointed out the disadvantages of having a large investment and a large installation space.

  Both ends are isocyanated by urethane bonding of at least one crystalline polyester polyol with a polyisocyanate such as methylenediphenyl diisocyanate at least one mole for the purpose of completing adhesion with excellent water resistance while being pressed for a short time. There has also been a proposal to use a so-called reactive hot melt, which is a prepolymer that is solid at room temperature. However, the molecular weight of this adhesive is about 1,000 to 10,000, and it is solid at room temperature due to the structure of the crystalline polyester. During the several hours until the isocyanate groups at both ends are cured with moisture after bonding. Cannot exert a strong cohesive force, and actually has a lower adhesive strength than a synthetic resin emulsion having a molecular weight of several tens to several millions for several minutes to several tens of minutes of short-time pressing.

  In addition, since the adhesive is applied by heating as a molten liquid and pasted and bonded, and becomes a solid when cooled, the allowable release or closing deposition time from application to the pressing step is extremely short and the workability is poor. In order to increase the allowable release or closing deposition time, an amorphous or liquid raw material is used in combination as the raw material polyester polyol. With this method, the solidification time becomes extremely long, and the adhesive strength immediately after pressing for a short time. Became more scarce.

  The object of the present invention is to eliminate the drawbacks of the prior art as described above, exhibit a sufficiently long application time and exhibit excellent workability, and at room temperature 3 to 10 minutes throughout the year using an aqueous adhesive. An object of the present invention is to provide a bonding method that enables bonding with excellent water resistance by short-time pressing.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention provide a water-based adhesive that has a sufficiently long application time, exhibits excellent workability because of a one-pack type, and is excellent in safety. It was possible to develop a bonding method that enables bonding with excellent water resistance by short-time pressing for 3 to 10 minutes at room temperature throughout the year, and the present invention has been completed. That is, the present invention is an adhesion method characterized by using an acetoacetyl group-containing synthetic resin emulsion composition adjusted to 15 ° C. to 80 ° C. and adhering an adherend at least one of which is a porous material.

  According to the bonding method of the present invention, it is possible to perform bonding with excellent water resistance by short-time pressing while having a sufficiently long application time without requiring a complicated bonding step. In addition, since equipment such as a hot press and a drying furnace is not required, it can efficiently cope with variable-variety multi-product production.

Hereafter, each structure of this invention is demonstrated in detail.
Synthetic resin emulsions constituting the acetoacetyl group-containing synthetic resin emulsion composition (hereinafter abbreviated as AA group-containing Em) of the present invention include vinyl acetate resin emulsions, ethylene-vinyl acetate copolymer resin emulsions, and acrylic resin systems. Examples include emulsions, polyurethane resin emulsions, SBR latex, MBR latex, NBR latex, chloroprene rubber latex, and the like. Moreover, the composite resin emulsion obtained by superposing | polymerizing a monomer in presence of another resin emulsion may be sufficient. These synthetic resin emulsions can be used alone or in combination of two or more. As a method of containing an acetoacetyl group, a monomer having an acetoacetyl group such as acetoacetoxyethyl acrylate, acetoacetoxyethyl methacrylate, acetoacetoxyallyl, or the like is copolymerized with other monomers at the time of polymerization of the synthetic resin emulsion. And a method of using acetoacetylated polyvinyl alcohol as a protective colloid. Moreover, the method of adding acetoacetylated polyvinyl alcohol aqueous solution to a synthetic resin emulsion may be sufficient, and these methods may be used together 2 or more types. The detailed reason is not clear, but by adding an acetoacetyl group to the synthetic resin emulsion, when the temperature is adjusted to 15 ° C. to 80 ° C. and an adherend having at least one porous material is adhered, Bonding can be completed even with a short press. As another effect, water resistance can be exhibited by a self-crosslinking reaction between acetoacetyl groups.

  The amount of acetoacetyl group introduced is not particularly limited, but a monomer having an acetoacetyl group and an unsaturated double bond, such as acetoacetylated polyvinyl alcohol, acetoacetoxyethyl acrylate, acetoacetoxyethyl methacrylate, and acetoacetoxyallyl Is relatively expensive compared to other water-based adhesive raw materials, and it is only uneconomical if it is too much.

  In addition, the AA group-containing Em may contain a water-soluble polymer, an inorganic or organic filler. In particular, calcium carbonate is preferably used because it improves water resistance when blended. The reason why the water resistance is improved is presumed to be due to the effect of coordination between the acetoacetyl group and calcium.

  The non-volatile content of the AA group-containing Em is preferably 40 to 80%. Even if it is less than 40%, although there is an effect of shortening the pressing time, it is difficult to complete the bonding with a pressing time of about 3 to 10 minutes in winter when the temperature of the adherend is lowered. On the other hand, if it exceeds 80%, the fluidity and applicability are remarkably lowered.

  Depending on the blending conditions of the AA group-containing Em and the like, the crosslinking reaction may proceed during storage, and sufficient storage stability may not be obtained. In such a case, the storage stability can be improved by adding oxycarboxylic acid, sulfite, bisulfite, metabisulfite, thiosulfate or the like. Particularly preferred is anhydrous sodium bisulfite.

  Various compounding materials can be added to the AA group-containing Em used in the present invention depending on each use mode. Such compounding materials include tackifier resins, fillers, thickeners, dispersants, leveling agents, water resistance agents, preservatives, antifoaming agents, surfactants, isocyanate compounds, epoxy compounds, silane cups as crosslinking agents. Examples thereof include a ring agent, an oxazoline compound, and a metal oxide.

  The present invention is characterized in that the temperature of the AA group-containing Em is adjusted to 15 to 80 ° C. during bonding. AA-group-containing Em can produce practical adhesive strength within a very short time by adjusting the temperature to 15 ° C. or higher. Therefore, not only in summer when the temperature and the substrate temperature are high and advantageous for short-time bonding, Even in winter when the temperature of the adherend is low and disadvantageous for short-time bonding, the bonding can be completed in about 3 to 10 minutes, and the next process should be performed immediately after the short-time pressing. Can do. As a temperature adjustment method, any method can be used as long as the AA group-containing Em can be adjusted to 15 to 80 ° C., the temperature may be preliminarily stored in a service tank with a heating facility, or a roller with a heating device. A glue spreader may be used. In addition, when AA group containing Em is maintained at 15-80 degreeC even if it does not adjust temperature especially like summer, it is not necessary to adjust temperature again. When the AA group-containing Em temperature is less than 15 ° C. as in winter, the effect of the present invention can be obtained by adjusting the temperature to 15 to 80 ° C. by using the above apparatus. When the temperature of the AA group-containing Em is less than 15 ° C., the adhesion in the winter when the adherend temperature is low tends to vary in the pressing time of about 3 to 10 minutes. Moreover, when it exceeds 80 degreeC, since water volatilizes before apply | coating to a to-be-adhered material, or before adhering to another to-be-adhered body after application | coating, water will volatilize and it will become dry adhesion, and it is preferable. Absent.

The coating amount of the bonding method using the water-based adhesive of the present invention and capable of bonding with excellent water resistance by short-time pressing for 3 to 10 minutes at room temperature is suitably 25 to 200 g / m ^{2 in} solid content, particularly 50. ˜150 g / m ² is preferred.

  At least one of the adherends of the present invention is a porous material such as paper, wood, plywood, LVL, laminated wood, particle board, MDF, OSB or other woody material, fiber reinforced cement board, inorganic material such as calcium silicate board It is necessary to be. If at least one of the adherends is not a porous material, the water content of the water-based adhesive is not absorbed. Therefore, it is impossible to achieve adhesion with excellent water resistance by pressing for 3 to 10 minutes at room temperature. If at least one of the adherends is a porous material, the other adherend is a non-porous material such as a plastic material such as a melamine resin-impregnated decorative board, or a metal material such as an aluminum plate or a steel plate. Can also be glued. Therefore, work such as composite wood flooring, stair treads, wood flash panels, decorative plywood, prefabricated panels, glued timbers, edge bonding, hozo, dowels, tows, hooks, square wood, and other assembly operations are accelerated. It is labor-saving and can contribute to energy saving.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Production method of adhesive 1 10 parts of acetoacetylated polyvinyl alcohol (Gosephemer Z-200, manufactured by Nippon Synthetic Chemical Co., Ltd., trade name), H-17 (manufactured by Denki Kagaku Kogyo Co., Ltd., product) Name) 14 parts, B-05 (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name) 6 parts were dispersed in 220 parts of water, and stirred and dissolved at 80 ° C. for 1 hour to obtain a protective colloid. Then, after adding 5 parts of 10% aqueous solution of arsenic acid (polymerization co-catalyst) and 10 parts of 1% aqueous solution of hydrogen peroxide (polymerization catalyst), 180 parts of vinyl acetate monomer, 20 parts of acetoacetoxyethyl methacrylate, 40 parts of a 1% aqueous solution of hydrogen oxide was added dropwise over 3 hours to conduct emulsion polymerization, and after aging at 80 ° C. for 1 hour, 9 parts of phenyl glycol-H (trade name, manufactured by Nippon Emulsifier Co., Ltd.), sodium bisulfite ( 1 part of a 10% aqueous solution of a polymerization inhibitor) was added and cooled. A total of 140 parts of paste in which 70 parts of heavy calcium carbonate having an average particle diameter of 2 microns was mixed and dispersed in 70 parts of water was added to obtain adhesive 1 (AA group-containing Em) having a nonvolatile content of 45%.

Method for producing adhesive 2 In the method for producing adhesive 1, the amount of water for dispersing polyvinyl alcohol was changed from 170 parts to 155 parts, and a paste obtained by mixing and dispersing heavy calcium carbonate in water was added. Agent 2 (AA group-containing Em) was used. The nonvolatile content was 53%.

Production method of adhesive 3 In the production method of adhesive 1, 6 parts of B-33 (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.) was used instead of 6 parts of B-05, and the amount of water for dispersing polyvinyl alcohol was adjusted. The adhesive from 3 to 170 parts was designated as Adhesive 3 (AA group-containing Em). The nonvolatile content was 37%.

Method for Producing Adhesive 4 A-340L (trade name, non-volatile content: 36%, manufactured by Aika Kogyo Co., Ltd.), which is a vinyl acetate resin emulsion adhesive not containing an acetoacetyl group, was used as the adhesive 4.

Example 1
Using the adhesive 1 adjusted to 23 ° C. and the adherend adjusted to 0 ° C., the shortest pressing time was determined by the test method described later, and it was 7 minutes. Moreover, the water resistance performance was also good under all conditions.

Examples 2-8, Comparative Examples 1-8
It implemented similarly to Example 1 on the adhesive agent of Table 1, adhesive agent temperature, and a to-be-adhered material condition. The results are shown in Table 1.

Minimum pressing time 12 mm thick plywood (75 mm × 40 mm) is applied to both sides of a 12 mm thick plywood (50 mm × 40 mm) so that the solid content is 75 g / m ^2, and the 12 mm thick plywood (75 mm × 40 mm) has the shape shown in FIG. Bonding and pressing immediately. The pressure was released after pressing for a predetermined time, and a split load in the direction of the arrow was applied using a steel jig as shown in FIG. 1, and the maximum load at break was measured. The shortest pressing time when the split adhesive strength was 300 N / (40 mm × 50 mm) or more was determined.

Water resistance performance Each adhesive was applied to a 12 mm thick plywood at 150 g / m ² , and bonded to a 3 mm thick MDF with a glued veneer veneer. After depressurization, curing at room temperature for 3 days, cutting a test piece of 75 mm x 75 mm, and carrying out a Japan Agricultural Standard JAS2 type peeling test (same as the JAS composite flooring peeling test) and JAS1 type peeling test Judged the suitability.

  As shown in Table 1, when the adhesive 1 and adhesive 2 which are AA group-containing Em are used after being adjusted to a temperature of 15 ° C. or higher, even if the temperature of the adherend is 0 ° C., a short time Good adhesion performance was obtained by pressing. When the adhesive 3 was used, when the temperature of the adherend was 23 ° C., good adhesive performance was obtained with a short pressing. When the adhesive 4 was used, water resistance was insufficient under any conditions.

Illustration of the test method for the minimum pressing time

Claims (5)

  An adhesion method, comprising using an acetoacetyl group-containing synthetic resin emulsion composition adjusted to a temperature of 15 ° C to 80 ° C and adhering an adherend at least one of which is a porous material.   The adhesion method according to claim 1, wherein the acetoacetyl group-containing synthetic resin emulsion composition contains acetoacetylated polyvinyl alcohol.   The adhesive according to claim 1 or 2, wherein the acetoacetyl group-containing synthetic resin emulsion composition contains a resin obtained by copolymerizing an acetoacetyl group-containing monomer and another monomer. Method.   The bonding method according to claim 1, wherein the non-volatile content of the acetoacetyl group-containing synthetic resin emulsion composition is 40 to 80%.   The bonding method according to claim 1, wherein the pressing time is 3 to 10 minutes.

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