Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1995-06-06
2001-04-24
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S340000
Reexamination Certificate
active
06221973
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a formaldehyde-free curable aqueous composition and the use thereof as a binder for heat-resistant nonwovens. The composition contains (a) a polyacid containing at least two carboxylic acid groups, anhydride groups, or the salts thereof; (b) a polyol containing at least two hydroxyl groups; and (c) a phosphorous-containing accelerator, wherein the ratio of the number of equivalents of said carboxylic acid groups., anhydride groups, or salts thereof to the number of equivalents of said hydroxyl groups is from about 1/0.01 to about 1/3, and wherein the carboxyl groups, anhydride groups, or salts thereof are neutralized to an extent of less than about 35% with a fixed base. The composition may be used as a binder for nonwovens composed of fiberglass or other heat-resistant fibers.
BACKGROUND OF THE INVENTION
Nonwoven fabrics are composed of fibers which may be consolidated by purely mechanical means such as, for example, by entanglement caused by needle-punching, by an air-laid process, and by a wet-laid process; by chemical means such as, for example, treatment with a polymeric binder; or by a combination of mechanical and chemical means before, during, or after nonwoven fabric formation. Some nonwoven fabrics are used at temperatures substantially higher than ambient temperature such as, for example, glass fiber-containing nonwoven fabrics which are impregnated with a hot asphaltic composition pursuant to making roofing shingles or roll roofing material. When a nonwoven fabric is contacted with a hot asphaltic composition at temperatures of 150-250° C., the nonwoven fabric may sag, shrink, or otherwise become distorted. Therefore, nonwoven fabrics which incorporate a curable aqueous composition should substantially retain the properties contributed by the cured aqueous composition such as, for example, tensile strength. In addition, the cured composition should not substantially detract from essential nonwoven fabric characteristics, as would be the case, for example, if the cured composition were too rigid or brittle or became sticky under processing conditions.
There is a need for a method for making a heat-resistant nonwoven fabric by using heat-resistant fibers and a heat-resistant curable aqueous composition which is free of formaldehyde, because of existing and proposed legislation directed to the lowering or elimination of formaldehyde
DESCRIPTION OF THE PRIOR ART
U.S. Pat. No. 4,693,847 discloses the esterification of a rosin, which is mainly a mixture of C
20,
fused-ring, monocarboxylic acids, with a polyol in the presence of a catalytic proportion of an organic ester of hypophosphorous acid, such as 2-ethylhexyl phosphinic acid.
U.S. Pat. No. 4,658,003 discloses (hydroxy)-phosphinylalkyl (meth)acrylates which can be prepared by the reaction of hypophosphorous acid with a suitable aldehyde or ketone to prepare an &agr;-hydroxyalkyl phosphorous acid, which is thereafter reacted with acrylic or methacrylic acid to prepare the (meth)acrylates, which may be further homo- or co-polymerized.
U.S. Pat. No. 5,042,986 discloses an aqueous treating solution for cellulosic textiles, the treating solution containing a cyclic aliphatic hydrocarbon of 4 to 6 carbon atoms having 4 or more carboxyl groups wherein at least two adjacent carboxyl groups are in the trans configuration relative to each other. The treating solution includes a suitable curing agent which is the alkali metal dihydrogen phosphate or the alkali metal salt of phosphorous, hypophosphorous, and polyphosphoric acid. The treating process is disclosed to be advantageously used with textiles containing 30-100% cellulosic materials.
U.S. Pat. Nos. 4,820,307; 4,936,865; and 4,975,209 disclose catalysts for the rapid formaldehyde-free esterification and crosslinking of fibrous cellulose in textile form by polycarboxylic acids including saturated, unsaturated, and aromatic acids as well as alpha-hydroxyacids. The catalysts disclosed are acidic or weakly basic salts selected from the alkali metal dihydrogen phosphates and alkali metal salts of phosphorous, hypophosphorous, and polyphosphoric acids.
U.S. Pat. No. 4,795,533 discloses a solid electrolyte membrane which contains a three component blend prepared by admixing an organic polymer, such as polyvinyl alcohol, with an inorganic compound and a polyorganic acid, such as polyacrylic acid. The inorganic compound is disclosed to be selected from a group consisting of phosphoric acid, sulphuric acid, heteropoly acids, or salts of heteropoly acids. Examples of phosphoric acids which may be employed include hypophosphoric acid, metaphosphoric acid, orthophosphoric acid, pyrophosphoric acid, and polyphosphoric acid.
U.S. Pat. No. 4.076,917 discloses &bgr;-hydroxyalkylamides and certain polymers thereof as curing agents for polymers containing one or more carboxy or anhydride functions. The &bgr;-hydroxyamides are disclosed to be effective in solution, aqueous emulsion, and powder coating form.
None of the references disclose a formaldehyde-free curable aqueous composition and the use thereof as a binder for heat-resistant nonwovens. The composition contains (a) a polyacid containing at least two carboxylic acid groups, anhydride groups, or the salts thereof; (b) a polyol containing at least two hydroxyl groups; and (c) a phosphorous-containing accelerator, wherein the ratio of the number of equivalents of said carboxylic acid groups, anhydride groups, or salts thereof to the number of equivalents of said hydroxyl groups is from about 1/0.01 to about 1/3, and wherein the carboxyl groups, anhydride groups, or salts thereof are neutralized to an extent of less than about 35% with a fixed base.
SUMMARY OF THE INVENTION
A formaldehyde-free curable aqueous composition and the use thereof as a binder for heat-resistant nonwovens such as, for example, nonwovens composed of fiberglass or other heat-resistant fibers are provided. The composition contains (a) a polyacid containing at least two carboxylic acid groups, anhydride groups, or salts thereof; (b) a polyol containing at least two hydroxyl groups; and (c) a phosphorous-containing accelerator,
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed to a formaldehyde-free curable aqueous composition and the use thereof as a binder for heat-resistant nonwovens. The composition contains (a) a polyacid containing at least two carboxylic acid groups, anhydride groups, or salts thereof; (b) a polyol containing at least two hydroxyl groups; and (c) a phosphorous-containing accelerator, wherein the ratio of the number of equivalents of said carboxylic acid groups, anhydride groups, or salts thereof to the number of equivalents of said hydroxyl groups is from about 1/0.01 to about 1/3, and wherein the carboxyl groups are neutralized to an extent of less than about 35% with a fixed base. The composition may be used as a binder for heat-resistant nonwovens such as, for example, nonwovens composed of fiberglass.
The formaldehyde-free curable aqueous composition of this invention is a substantially thermoplastic, or substantially uncrosslinked, composition when it is applied to the substrate, although low levels of deliberate or adventitious crosslinking may be present. On heating the binder, the binder is dried and curing is effected, either sequentially or concurrently. By curing is meant herein a structural or morphological change which is sufficient to alter the properties of a flexible, porous substrate to which an effective amount of polymeric binder has been applied such as, for example, covalent chemical reaction, ionic interaction or clustering, improved adhesion to the substrate, phase transformation or inversion, hydrogen bonding, and the like.
This invention is directed to a formaldehyde-free curable aqueous composition. By “formaldehyde-free composition” herein is meant that the composition is substantially free from formaldehyde, nor does it liberate substantial formaldehyde as a result of drying and/or curing. In order to minimize the formaldehyde content of the waterbo
Arkens Charles Thomas
Gleim Robert David
Bakule Ronald D.
Rohm and Haas Company
Wu David W.
LandOfFree
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