Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1994-02-22
2001-08-28
Gallagher, John J. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S307500, C156S308800, C156S329000, C156S330000, C156S331400, C156S331700, C427S208400, C427S341000, C428S350000
Reexamination Certificate
active
06280562
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a contact adhering method, in which adherends are fastened by means of an adhesive which does not contain any solvent and can be cured without any heating process.
2. Description of the Related Art
Conventional solvent-based elastomeric adhesives (rubber cement) are easy to use to fasten adherends, since these adhesives do not require that adherends be temporarily kept pressed until they are firmly fastened, and since it is possible to let a certain period of time (open time) pass before the adherends must be fastened. However, such elastomeric adhesives include solvents as indispensable components, which are toxic to man and are flammable.
Various efforts and research have been carried out to solve the above inconveniences of the conventional solvent elastomeric adhesives through such alternatives as (1) high solidification, (2) non-use of solvents, and (3) use of aqueous contact (aqueous emulsion type) adhesives. However, these alternatives are not satisfactory for the following reasons.
(1) When it is highly solidified to remove the solvent, the adhesive cannot maintain its effective adhesiveness. (2) Use of hot melt adhesives is conceivable in place of the solvent adhesives. The hot melt adhesives are easy to use, but should be heated and are difficult to apply to large adherends. (3) Aqueous adhesives are safe from the viewpoint of hygiene and non-flammability, but have low contact adhesiveness. The aqueous adhesives are applicable only to water-absorbing adherends such as wood, and take time to dry.
With a conventional adhering method using a moisture curable type adhesive, the adhesive is applied on a single one (single spread) or both (double spread) of the adherends, and the adherends are fastened to cure the adhesive. In such a case the adhesive is slow to cure. Even when the adhesive is applied to adherends having a good moisture permeability, it will take one or two days for adhesive to cure at room temperature. In addition, the adherends have to be temporarily fastened by some means. This means the adhering task is very troublesome. When fastening adherends having no moisture permeability such as steel sheets, the adhesive takes time to cure, which makes the task even more troublesome.
SUMMARY OF THE INVENTION
The present inventors have focused on the fact that a moisture curable adhesive reacts with moisture at room temperature, cures to produce a thin film, and develops tack as the thin film is produced. They have tried to use the tack of the adhesive, thereby solving the problems experienced with conventional adhering methods.
It is therefore an object of this invention to provide a novel contact adhering method and an adhesive to be used for the proposed method. According to this invention, the adhesive is not a health hazard or a fire hazard since it does not include any solvent. The adhesive is of a contact type, which enables adherends to be fastened soon after the adhesive is applied. No temporary fastening means is necessary after the adherends are fastened with the adhesive, which facilitates the adhering task. In addition, the adhesive is applicable to any adherend since it is not of an aqueous contact type (aqueous emulsion type). The adhesive is cured at room temperature and does not need any heating. In contrast to the conventional moisture curable adhesives, the adhesive of this invention is applicable to adherends which do not have any moisture permeability, and may be fastened by themselves in a short period of time.
The above object of this invention is accomplished by the contact adhering method comprising the steps of applying a moisture curable adhesive to adherends, leaving the adhesive and the adherends for a certain period of time (open time) until tack is formed, and fastening the adherends in a tack range.
DETAILED DESCRIPTION
According to the method of this invention, the adhesive layer reacts with moisture in air or moisture supplied forcibly, and develops tack while forming a thin film on the surface. When the adhesive layer is too thick, the resulting thin film cannot be formed uniformly, which will cause insufficient tack and lower the contact adhesiveness of the adhesive.
The word “tack” is defined in this specification as a tacky state wherein there is maintained the contact adhesiveness which enables adherends to be fastened soon after bringing the adherends into contact with each other and produces excellent adhesiveness in a period of time after the contact of the adherends.
The term “tack range” is defined in this specification as a time required for developed tack to vanish.
The moisture curable adhesive may be one or more adhesives selected from the group consisting of (a) a silicon adhesive and/or an organic polymer adhesive comprising a high polymer (A) having one or more reactive silicon groups in a molecule, (b) a urethane adhesive comprising a high polymer (B) having one or more isocyanate groups in a molecule, and (c) an epoxy adhesive having the said high polymer (A) and/or (B) and a compound including an epoxy group.
An example of the high polymer, especially polyoxyalkylene (A) having one or more reactive silicon groups in a molecule is disclosed in Japanese Patent Publications No.156599/1975 (U.S. Pat. No. 3,971,751) and No.73998/1977, and Japanese Patent Publication No.10418/1983. Japanese Patent Laid-Open Publication No.230822/1987 discloses another high polymer. Japanese Patent Laid-Open Publication No.12677/1988 discloses an organic silicon compound having in a molecule two or more silicon atoms in which a hydrolyzable group is combined. An adhesive compound of oxyalkylene polymer including silicon groups, and acrylate and/or methacrylate (co)polymer including silicon groups are disclosed in Japanese Patent Laid-Open Publication Nos. 228516/1985 (U.S. Pat. No. 4,618,656), 112642/1988 (EP 0265929) and 131271/1989 (U.S. Pat. No. 4,910,255).
The adhesive comprising the compound disclosed in Japanese Patent Laid-Open Publication No.112642/1988 (EP 0265929) has a good adhesive property (such as tack range). The cited Japanese Publication No.112642/1988 (EP 0265929) discloses a curing compound, which is composed of (1) a copolymer including a reactive silicon group whose molecular chain substantially consists of (i) alkylacrylate and/or alkylmethacrylate monomeric unit having an alkyl group with 1 to 8 carbons, and (ii) alkylacrylate and/or alkylmethacrylate monomeric unit having an alkyl group with 10 more carbons, and (2) a polymer substantially consisting of oxyalkylene including a reactive silicon group. Here the reactive silicon group represents a functional group including silicon which can form cross linking through siloxane linkage. A typical example of the reactive silicon group is expressed by the general formula (I):
where R
1
represents a substituted or unsubstituted monovalent organic group having 1 to 20 carbons, or a triorganosiloxy group; X is a hydroxyl group, or a heterogeneous or homogeneous hydrolyzable group; a is an integer which is 0, 1, or 2; b is an integer which is 0, 1, 2, or 3 (a and b cannot have simultaneously the values a=2 and b=3) and m is an integer from 0 to 18. A preferable reactive and functional silicon group is expressed by;
where R
1
is the same as in formula (I), and n is integer of 0, 1 or 2.
In order to make the adhering method of this invention more effective, the following compounds may be added to the foregoing adhesives (a) to (c). They are vinyl compounds such as a vinyl chloride (co)polymer, phenol resin compound, petroleum resin, terpene phenol resin, a tackifiers such as a rosin ester resin, preliminary reacted epoxy resin as exemplified in Japanese Patent Laid-Open Publication No.291918/1988, or acrylate and/or methacrylate compounds such as butylacrylate copolymers.
The adhesive for the proposed method is obtained by mixing 100 parts of any one of the above-mentioned compounds with 0.1 to 10 parts of an accelerator.
The accelerator may be any one of organic tin compoun
Aoki Hiroshi
Horie Toshiharu
Makino Zyunzo
Nishikawa Nobuyoshi
Okuno Eiichi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Cemedine Company, LTD
Gallagher John J.
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