Stock material or miscellaneous articles – Structurally defined web or sheet – Physical dimension specified
Patent
1998-08-19
2000-11-14
Beck, Shrive
Stock material or miscellaneous articles
Structurally defined web or sheet
Physical dimension specified
252 62, 181284, 181294, 428522, 442120, 4273855, B05D 302, E04B 182, E04B 184
Patent
active
061467464
DESCRIPTION:
BRIEF SUMMARY
The invention relates to the use of coating compositions for coating shaped articles and sheets.
Shaped articles, for example soundproofing panels, often consist of fibers or fillers which are bound, i.e. consolidated, by means of a binder, for example starch or aqueous polymer dispersions.
Shaped articles or sheets can be coated or impregnated on the surface with a coating composition in order to improve further the properties of the shaped articles or sheets.
In EP 123 234 it is noted that such sheets must frequently be coated or impregnated with formaldehyde condensation resins in order to improve the moisture resistance. A disadvantage of sheets treated in this way, especially in the context of use in enclosed spaces, is the gradual release of formaldehyde from the condensation resin.
EP 386 579 describes shaped articles obtainable by impregnating preforms composed in the main of mineral fibers, nonfibrous mineral fillers and starch with a composition containing a binder comprising copolymers composed of
______________________________________ 60-95% by weight
of methyl methacrylate (I)
5-40% by weight
of acrylic and/or methacrylate acid (II)
0-35% by weight
of one or more acrylic esters of a
C.sub.1 -C.sub.8 -alkanol (III)
0-5% by weight
of copolymerizable polyunsaturated monomers
(VI)
and
0-5% by weight
of other copolymerizable monomers (VI)
______________________________________
having been selected within the stated limits in such a way that a polymer
composed of these monomers only would have a glass transition temperature
of from 60 to 125.degree. C.
The starch-containing sheets impregnated with such compositions, when stored for 48 hours under hot, damp conditions, show unsatisfactory bowing.
EP 445 578 describes binders and coating compositions for sheets, containing at least one high molecular mass polycarboxylic acid and at least one polyfunctional amine or alkanolamine or a polyhydric alcohol. High molecular mass polycarboxylic acids described are polyacrylic acid, poly(methyl methacrylate-co-n-butyl acrylate-co-methacrylic acid) and poly(methyl methacrylate-co-methacrylic acid). Polyfunctional alcohols and alkanolamines used are 2-hydroxymethyl-1,4-butanediol, trimethylolpropane, glycerol, poly(methyl methacrylate-co-hydroxypropyl acrylate), diethanolamine and triethanolamine. Although maleic acid is named as a possible comonomer for preparing the high molecular mass polycarboxylic acids, no more detailed description is given of the use of copolymers containing maleic acid. Preferably, .alpha.,.beta.-unsaturated carboxylic acids are used. Although one example cites the use of triethanolamine as crosslinking agent, it is used only in combination with an aqueous dispersion, prepared by emulsion polymerization, of a copolymer of methyl methacrylate and methacrylic acid. A disadvantage is the inadequate flexural modulus of the coated, starch-containing sheets. It is desirable to give the coated sheet a maximum flexural modulus so that no unwanted deformation occurs even in the course of a period of use extending over several years.
EP 583 086 discloses formaldehyde-free aqueous binders for producing mechanically stable, thermally resistant glass fiber nonwovens. The binders contain polycarboxylic acids and polyols. No mention is made of the coating or impregnation of sheets composed of organic and/or inorganic fibers, nonfibrous mineral fillers and starch and/or aqueous polymer dispersions.
EP 651 088 describes a method of consolidating cellulose substrates using aqueous compositions of polycarboxylic acids, polyols and phosphorus-containing accelerators. No mention is made of the coating or impregnation of sheets composed of organic and/or inorganic fibers, nonfibrous mineral fillers and starch and/or aqueous polymer dispersions.
A disadvantage of known sheets and shaped articles comprising organic and/or inorganic fibers and nonfibrous mineral fillers is their excessive bowing under damp and/or hot conditions, especially if starch has been used as
REFERENCES:
patent: 4367259 (1983-01-01), Fulmer et al.
patent: 5427587 (1995-06-01), Arkens et al.
Beckerle Wilhelm Friedrich
Hummerich Rainer
Kistenmacher Axel
Reck Bernd
Rupaner Robert
BASF - Aktiengesellschaft
Beck Shrive
Calcagni Jennifer
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