Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1988-07-06
1990-07-17
Gallagher, John J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156184, 156192, 156276, 1563075, 1563086, 156 39, 1563313, 252194, 427333, 427340, 427341, 428420, B32B 3100
Patent
active
049419382
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of binding water upon the joining of materials using water-based adhesives or adhesives which liberate water during curing. More particularly, the invention relates to such a method wherein water is bound to a compound in the form of water of crystallization. The method of the invention can be utilized in many fields, such as for example in the production of composite wood and wood-based materials, in the production of cellulose-based board materials, in the bonding of carpets to different kinds of substrates, and in other types or bonding operations, such as mounting and renovation. The method of the invention is particularly suitable for gluing of dense materials and at thick glue joints, and another field in which the present method is very advantageous is in the production of paper cores for the paper industry.
Different kinds of binders and adhesives which solidify and give the desired glue joint through release of water are per se well known and used in a number of fields. "Drying" adhesives in which the binder is dispersed or dissolved in water give a joint by release of water and the formation of a continuous phase without any actual chemical reaction. For curable adhesives the transformation to a solid phase, or the development of the binding capability, includes a chemical reaction. Several types of water-based curable adhesives and adhesives which liberate water during the curing exist, and they are usually used in the form of two-component systems, i.e. in the form of a resin which during the joining is mixed with or applied in combination with a hardener. While drying adhesives are mainly used for the gluing of paper, wallpaper, floors and similar products, curable adhesives such as formaldehyde-based amino- and phenolic resins are mainly used for bonding wood, wood-based and cellulose-based materials.
A common problem when using adhesives which are water-based and/or liberate water during curing is that the water as rule must be made to be released as uniformly as possible to give a final strong joint and a joint over the entire intended area in such a manner that the dimensional stability and the strength properties are not negatively influenced. In certain applications, such as for example the production of particle board and plywood, high temperatures and pressures are used in the presses to release the majority of the water, while the release of water in other applications must occur at ambient temperature, or only somewhat elevated temperatures. The simplest way of reducing the drying time is of course to use aqueous adhesive compositions having as high a dry content as possible, but here factors such as distribution at spreading, wetting and penetration impose certain limits, and even when adhesives in more or less entirely dry form are used, these can liberate water during curing which it is desirable to remove. Thus, there remains a desire to remove water in processes for joining wherein water-based adhesives or adhesives which give off water at curing are used, and to do this in such a manner that strength properties and dimensional stability are at least retained.
The present invention offers a method of binding water so that it is not present in free form and need not be removed by heating, prolonged storage, waiting-times, etc., while joining materials using adhesives of the above mentioned types. The method of the present invention can considerably speed up the gluing process. The method of the present invention can be utilized in most types of joining of different kinds of materials and gives great advantages. The method is particularly advantageous for thick glue joints, when bonding wood having poorly treated surfaces or when low pressures are used, for example in bonding processes within buildings, and in the bonding of dense materials, such as the bonding of metal to wood where the problems with water release are particularly pronounced. The method of the present invention is particularly advantageous in the joining of materials whic
REFERENCES:
patent: 2410586 (1946-11-01), McGarvey
patent: 3574662 (1971-04-01), Gage
patent: 3941632 (1976-03-01), Swedenberg et al.
Casco Nobel AB
Gallagher John J.
Philpitt Fred
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