JP2010084108A - Adhesion sheet and adhesion process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesion sheet that contains no formaldehyde, but is capable of adhering in a dry step and an adhesion process. <P>SOLUTION: The adhesion sheet is characterized in that it is obtained by heating a plastisol composition containing at least a thermoplastic resin powder, a plasticizer, and a curable resin for liquefaction and then forming the resultant into a sheet. As a curable resin, an epoxy resin, an urethane resin, or an acrylic resin is preferably contained in the sheet. As a thermoplastic resin powder, an acrylic resin powder is preferably contained in the sheet. The method also comprises performing adhesion by placing an adhesion sheet between adherents and then providing curing conditions for a curable resin. The method also comprises performing adhesion by coating an adherent with the plastisol composition, heating and solidifying the resultant, superimposing another adherent over the solidified product, and then providing curing conditions for a curable resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adhesive sheet and a bonding method that do not contain formaldehyde and can be bonded in a dry process.

  Adhesion is a kind of bonding method in which a liquid adhesive is applied to an adherend and the adhesive is cured to develop an adhesive force. Its features include the ability to bond various adherends with the required performance by selecting an appropriate adhesive, no special processing is required for the adherends, and the entire surface can be joined and stress is not concentrated. The work procedure is simple, and many adhesives do not require special equipment, and are used in various fields such as woodwork, architecture, and packaging.

  On the other hand, since it is necessary to handle a liquid adhesive, the product adheres to the part other than the adherend surface of the adherend and the product is contaminated. There are problems such as being contaminated, the surroundings being contaminated through the adhesive attached to the hands and clothes of the operator, and the cleaning operation of the adhesive application device being necessary. Therefore, in a field where a clean environment is required, an adhesive sheet that can be handled as a solid material is used.

Phenol resin has been mainly used as a conventional adhesive sheet, but it has a problem of releasing formaldehyde, and it becomes difficult to use it for applications such as building materials and vehicle interior materials that are expected to affect the human body. It's getting on. In addition, so-called anisotropic conductive sheets are used in circuit boards, and it can be said that the circuit boards are joined without releasing formaldehyde, but the main purpose is conduction in a specific direction, and large separation. It does not have sufficient adhesive strength against force. As described above, although there is a demand for an adhesive sheet that has a sufficient adhesive force and does not contain formaldehyde, there is no adhesive sheet that can cope with this.
JP 10-130500 A Japanese Patent Laid-Open No. 2003-231876 JP 2001-31915 A

  An object of the present invention is to provide an adhesive sheet and a bonding method that do not contain formaldehyde and can be bonded in a dry process.

  An adhesive sheet obtained by heating a plastisol composition containing at least a thermoplastic resin powder, a plasticizer, and a curable resin to liquefy it and mold it into a sheet. The curable resin preferably contains an epoxy resin, a urethane resin or an acrylic resin, and the thermoplastic resin powder preferably contains an acrylic resin powder. Moreover, it is the method of adhering by pinching | bonding an adhesive sheet between to-be-adhered materials, and giving the hardening conditions of curable resin. Furthermore, after applying the plastisol composition to an adherend, it is heated and solidified, and bonded with another adherend by providing curing conditions for a curable resin.

  The adhesive sheet of the present invention does not contain formaldehyde, has sufficient adhesive strength, and can be bonded in a dry process. In use, since the adhesion is completed by sandwiching an adhesive sheet between the adherends and applying curing conditions for the curable resin, there is no product or surrounding contamination that occurs when using a liquid adhesive. Therefore, it is particularly suitable for applications requiring a clean environment. Further, the bonding method of the present invention does not require handling of a liquid adhesive at the time of bonding, and thus is particularly suitable for applications requiring a clean environment.

  The adhesive sheet of the present invention is obtained by heating and solidifying a plastisol composition containing at least a thermoplastic resin powder, a plasticizer, and a curable resin, and molding the sheet into a sheet shape. A thermoplastic resin and a plasticizer that are in a dispersed liquid state before heating are compatibilized by heating, and are molded into a sheet when melted and solidified, whereby an adhesive sheet containing a curable resin is obtained. When used as an adhesive sheet, it is sandwiched between the adherends, and the bonding is completed by giving curing conditions for the curable resin. As another method, an adhesive sheet is formed on the adherend by applying the plastisol composition to the adherend and then solidifying by heating, and the adhesive sheet and the adherend are handled in an integrated manner. Also good. In this case, the bonding is completed by giving curing conditions for a resin that can be cured after being combined with another adherend.

  Acrylic polymer powder is preferably used as the thermoplastic resin powder. When vinyl chloride resin powder is used, it is not preferable because harmful chlorine compounds may be generated during incineration, but the effect of the present invention can be obtained. Acrylic polymer powders are monomers such as acrylic acid esters and methacrylic acid esters in emulsion media, seed emulsion polymerization, soap-free polymerization, suspension polymerization, fine suspension polymerization, in organic media. Acrylic resin dispersion synthesized by dispersion polymerization, dispersion polymerization in water / organic mixed medium, precipitation polymerization in organic medium, spray drying method (spray drying method), coagulation method with salt or acid, Powdered using a technique such as freeze-drying, centrifugation, or filtration.

  Specific examples of monomers include ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, ethyl hexyl methacrylate, ethyl acrylate, n-butyl acrylate, sec-butyl acrylate, Examples include tert-butyl acrylate, methyl methacrylate, benzyl methacrylate, methacrylic acid, acrylic acid, itaconic acid, and crotonic acid.

  As the acrylic polymer powder, those having a core-shell type having different monomer compositions, and those in which the monomer composition changes from the central part toward the outermost part in a multistage or continuous manner can be used. Further, two or more kinds of acrylic polymer powders having different monomer compositions, particle structures, primary particle diameters, secondary particle diameters, and the like can be used.

  The plasticizer is used to dissolve the thermoplastic resin powder. Specifically, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, diisononyl phthalate, dialkyl phthalate such as diisodecyl phthalate, alkyl benzyl phthalate such as butyl benzyl phthalate, alkyl aryl phthalate, dibenzyl phthalate , Aliphatic dibasic acid esters such as diaryl phthalate and dibutyl adipate, phosphate plasticizers such as triphenyl phosphate, tricresyl phosphate, tri- (2-ethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, dibutyl Ether-containing compounds such as glycol adipate, ester plasticizers such as 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, alkylsulfonic acid phenyl esters, polyalkylene glycols And soybean oil-based plasticizers such as epoxidized soybean oil. A plasticizer may be used independently and may use 2 or more types together. It is preferable to use 50 to 400 parts by weight of a plasticizer with respect to 100 parts by weight of the thermoplastic resin powder.

  The curable resin is a component related to the adhesiveness of the adhesive sheet, which can be cured by giving the curing conditions. In the present invention, when a thermoplastic resin and a plasticizer are made compatible by heating, even if a curable resin is cured, the performance as an adhesive sheet cannot be exhibited. Further, if curing proceeds during storage as an adhesive sheet, the period of use is restricted. Accordingly, a thermosetting resin that is cured at a temperature higher than that during heating for the compatibilization, a UV curable resin, or the like is suitable.

  Specific examples of the curable resin suitable for the present invention include an epoxy resin using a high temperature active type curing agent such as dicyandiamide, a urethane resin having a latent curing group such as a blocked isocyanate group, and a high temperature decomposition type polymerization initiator. And acrylic resin.

  A filler may be added to the plastisol composition. Specific examples include calcium carbonate, palaita, clay, colloidal silica, mica powder, diatomaceous earth, kaolin, talc, pennite, glass powder, sand, aluminum oxide, aluminum hydroxide, antimony trioxide, and titanium dioxide. 0 to 400 parts by weight can be added to 100 parts by weight of the thermoplastic resin powder.

  By heating the plastisol composition, the thermoplastic resin powder and the plasticizer become compatible, and an adhesive sheet is obtained by molding into a sheet shape. The plastisol heating conditions are not particularly limited as long as the curable resin is other than a thermosetting resin, but when the curable resin is a thermosetting resin, heating is performed so that the curable resin is not cured. It is necessary to provide a necessary amount of heat by lowering the temperature and increasing the heating time. Further, when forming into a sheet shape, it may be formed by impregnating or coating paper or glass fiber as a base material.

  Since the adhesive sheet is a solid material, there is no risk of contaminating the product and surroundings unlike a liquid adhesive, and the adhesive sheet is easy to handle. When used as an adhesive sheet, the adhesion is completed by sandwiching between the adherends or combining the adherend coated with the plastisol composition with other adherents to give curing conditions for the curable resin. .

  Hereinafter, based on an Example, this invention is demonstrated more concretely. Of course, the present invention is not limited to the embodiments.

Example 1
Acrylic resin powder LP3106 (product name, manufactured by Mitsubishi Rayon Co., Ltd.) 100 parts by weight, diisononyl phthalate 100 parts by weight, calcium carbonate M white (manufactured by Maruo Calcium Co., product name) 100 parts by weight, epoxy resin A plastisol composition was obtained by mixing 40 parts by weight of jER828 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.) and 10 parts by weight of dicyandiamide. The adhesive sheet of Example 1 was obtained by applying the plastisol composition on the release paper at a film thickness of 100 μm and heating at 80 ° C. for 3 minutes. The adhesive sheet had no tack and was easy to handle.

Examples 2-4, Comparative Examples 1-3
In the same manner as in Example 1, the materials shown in Table 1 were mixed to form an adhesive sheet, thereby obtaining adhesive sheets of Examples and Comparative Examples. In Example 4, TMPT (trimethylolpropane trimethacrylate) was used as the curable acrylic resin, and BPO (benzoyl peroxide) was used as the curing agent. Further, as Comparative Example 3, a phenol resin adhesive sheet was used. Except for Comparative Example 2, each adhesive sheet had no tack and was easy to handle.

Test evaluation method Peeling strength Each adhesive sheet is sandwiched between aluminum foil (thickness: 0.2 mm) and felt (thickness: 0.5 mm) and heated under conditions of 0.3 MPa and 180 ° C for 15 minutes. An adhesive was obtained by tightening. The bonded body was cooled to room temperature and then cut to a width of 25 mm, a T-type peel test was performed at a crosshead speed of 100 mm / min, and the peel strength was measured.
Formaldehyde emission A product that did not use formaldehyde-containing material was evaluated as ○, and a material that contained formaldehyde was evaluated as ×.

When each adhesive sheet of the example was used, good peel strength was obtained. In addition, since it does not contain formaldehyde, it can be used for applications that are expected to affect the human body, such as building materials and vehicle interior materials. Furthermore, since there is no possibility of contaminating the product and surroundings unlike a liquid adhesive, it is easy to handle and can be used in fields where a clean environment is required.
On the other hand, the peel strength of the adhesive sheet of Comparative Example 1 was insufficient. In Comparative Example 2, the sheet could not be formed. Moreover, since the adhesive sheet of Comparative Example 3 contains formaldehyde, it is difficult to use the adhesive sheet for applications such as building materials and vehicle interior materials that are expected to affect the human body.

Claims (5)

  An adhesive sheet obtained by heating and solidifying a plastisol composition containing at least a thermoplastic resin powder, a plasticizer, and a curable resin, and molding the sheet into a sheet.   The adhesive sheet according to claim 1, wherein the plastisol composition contains an epoxy resin, a urethane resin, or an acrylic resin as a curable resin.   The adhesive sheet according to claim 1 or 2, wherein the plastisol composition contains an acrylic resin powder as a thermoplastic resin powder.   A method of adhering the adhesive sheet according to claim 1 by sandwiching the adhesive sheet between adherends and applying curing conditions for a curable resin.   A method of applying the plastisol composition according to any one of claims 1 to 3 to an adherend, followed by heating and solidification, and bonding with another adherend by providing curing conditions for a curable resin .