Water-dispersible films and fibers based on sulfopolyesters

Details Water-dispersible films and fibers based on sulfopolyesters Water-dispersible films and fibers based on sulfopolyesters

1999-11-26

2001-01-09

Acquah, Samuel A. (Department: 1711)

Stock material or miscellaneous articles

Web or sheet containing structurally defined element or...

C528S288000, C528S289000, C528S291000, C528S294000, C528S295000, C528S302000, C528S308000, C528S308600, C525S437000, C525S444000, C524S401000, C524S413000, C524S424000, C524S425000, C524S432000, C524S433000, C524S436000, C524S445000, C524S450000, C524S451000, C428S364000

Reexamination Certificate

active

06171685

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to water-dispersible film and fiber compositions that are based on formulations containing sulfopolyesters. The formulations may be manufactured in-situ directly after the polymer is synthesized and fabricated into films by melt extrusion. Excellent quality films are obtained that maintain water-dispersibility and non-blocking characteristics.
BACKGROUND OF THE INVENTION
Water soluble or water-dispersible films are known, but there are few commercially viable examples. Polyvinyl alcohol (PVOH) film constitutes nearly all of the volume and is used for disposable bags and packaging. A solution process is typically employed for PVOH since it lacks thermal stability. This is cumbersome and adds to the cost of the manufactured film.
Sulfopolyesters are another class of materials where cast films may subsequently be re-dispersed into water. Typical sulfopolyesters, such as those disclosed in U.S. Pat. No. 3,734,874, result in brittle films or films having low strength.
More recently, a family of branched sulfopolyesters has been developed for water-dispersible adhesive formulations as disclosed in U.S. Pat. Nos. 5,543,488; 5,552,495; 5,552,511; 5,571,876; and 5,605,764. These polymers are easily dispersible into water, but have glass transition (Tg) values not greater than 20° C. and result in films that undergo blocking during storage.
SUMMARY OF THE INVENTION
The present invention provides a water-dispersible sulfopolyester composition having relatively large proportions of pigments and/or fillers. Such compositions are substantially non-blocking when processed using packaging rolls and are comprised of at least one sulfopolyester as described herein; about 10 to about 75 weight percent of a filler; and one or more waxes.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a water-dispersible polymer composition comprising
(a) at least one sulfopolyester as described herein;
(b) about 10 to 75 weight percent of a pigment or filler; and
(c) a wax; with the sum of (a), (b), and (c) equaling 100 weight percent.
The sulfopolyester material may be linear or branched. In a preferred embodiment, the sulfopolyester is comprised of
(i) monomer residues of at least one dicarboxylic acid; and
(ii) about 4 to 25 mole percent, based on the total of all acid and hydroxy equivalents, of monomer residues of at least one difunctional sulfomonomer containing at least one sulfonate group bonded to an aromatic ring, wherein the functional groups are hydroxy or carboxyl; and optionally
(iii) monomer residues of at least one poly(alkylene glycol) having the formula —(OCH
2
CH
2
)
n
— wherein n is 2 to about 500, provided that the mole percent of such residues is inversely proportional to the value of n; and
(iv) up to about 75 mole percent of monomer residues of at least one diol, wherein said diol is other than a poly(alkylene glycol).
In a further preferred embodiment, the sulfopolyester component (i) is a blend of two or more sulfopolyesters. Particularly preferred polyesters are the substantially linear polyesters described in U.S. Pat. No. 3,779,993, and the branched polyesters described in U.S. Pat. No. 5,543,488, incorporated herein by reference.
Thus, the present invention further provides a water-dispersible polymer composition comprising
(I) a sulfopolyester component comprising
(a) a water-dispersible sulfopolyester having a Tg of ≦20° C. comprised of residues of
(i) at least one difunctional dicarboxylic acid;
(ii) at least one difunctional glycol containing two —CH
2
OH groups of which at least 15 mole percent is a poly(ethylene glycol) having the formula
H—(—OCH
2
—CH
2
—)—
n
—OH
 wherein n is an integer in the range of 2 to about 20;
(iii) in an amount to provide said water dispersible characteristic of said polymer of at least one difunctional sulfomonomer containing at least one metal sulfonate group to an aromatic nucleus wherein the functional groups are hydroxy or carboxy; and
(iv) up to about 50 mole percent of a difunctional hydroxy-carboxylic acid having one —C(R)
2
—OH group, wherein R is H or a C
1
-C
4
alkyl group; and
(b) a water-dispersible branched polyester composition comprised of residues of:
(I) at least one difunctional dicarboxylic acid which is not a sulfomonomer;
(II) about 2 to 30 mol percent, based on the total of all acid, hydroxyl and amino equivalence, of residues of at least one difunctional sulfomonomer containing at least one sulfonate group bonded to an aromatic ring wherein the functional groups are hydroxyl, carboxyl, or amino;
(III) at least one diol or a mixture of a diol and a diamine comprising:
(A) about 0.1 to 85 mole percent, based on the total mol percent of diol moieties or diol and diamine moieties, of a diol or diamine having the formula H(—OCH
2
CH
2
—)
n
OH and HRN(—(CH
2
CH
2
O))
n
NHR wherein n is 2 to about 20 and R is hydrogen or C
1
-C
6
alkyl provided that the mole percent of such moieties is inversely proportional to the value of n;
(B) about 0.1 to 15 mol percent, based on the total mol percent of diol moieties or diol and diamine moieties, of moieties of a poly(ethylene glycol) having the formula H(—OCH
2
CH
2
—)
n
OH wherein n is 2 to about 500, provided that the mol percent of such moieties is inversely proportional to the value of n; and
(C) 0 to greater than about 99 mol percent of the diol component or diol and diamine mixture being selected from the group consisting of a glycol and a mixture of glycol and diamine having two —NRH groups, the glycol containing two —C(R
1
)
2
—OH groups wherein R
1
is a hydrogen atom, an alkyl of 1 to 5 carbon atoms, or an aryl group of 6 to 10 carbon atoms;
(IV) 0 to about 40 mol % of a difunctional monomer reactant selected from the group consisting of hydroxycarboxylic acids having one —C(R—)
2
—OH group, aminocarboxylic acids having one —NRH group, aminoalkanols having one —C(R—)
2
OH group and one —NRH group and mixtures of said difunctional reactants wherein R is hydrogen or an alkyl group of 1 to 6 carbon atoms; and
(V) about 0.1 to 40 mol % of a multifunctional or branch-inducing reactant containing at least three functional groups selected from hydroxyl, carboxyl, amino, and mixtures thereof;
said branched polyester comprised of substantially equal mole proportions of acid equivalents (100 mol %) and diol or diol and diamine equivalents (100 mol %) wherein at least 20 weight percent of the groups linking the moieties of the monomeric units are ester linkages and wherein the inherent viscosity is at least 0.1 dL/g measured in a 60/40 parts by weight solution of phenol/tetrachloroethane at 25° C. and at a concentration of about 0.25 g of polymer in 100 ml of the solvent, the glass transition temperature T
g
is no greater than 20° C., and the ring and ball softening point is at least 70° C.;
(II) about 10 to 75 weight percent of a pigment or filler; and
(III) a wax.
As noted above, the sulfopolyester may be a linear or branched material. It is particularly preferred to blend two or more sulfopolyesters insofar as this approach provides a balance of properties. Particular utility is obtained from blends of a low Tg branched sulfopolyester, such as Eastman AQ® 14000 resin, with a higher Tg linear sulfopolyester, such as Eastman AQ® 55 resin.
In this regard, a particularly preferred branched sulfopolyester is comprised of
(i) a dicarboxylic acid;
(ii) 2 to 15 mole percent of sodioisophthalic acid residues;
(iii) poly(ethylene glycol);
(iv) up to 50 mole percent of a diol which is other than poly(ethylene glycol);
(v) 0.1 to 20 mole percent of at least one trifunctional hydroxy compound; wherein said sulfopolyester has a T
g
of ≦20° C.
A particularly preferred linear sulfopolyester is comprised of
(i) an aromatic diacid component comprised of up to 50 mole percent of an aliphatic or cycloaliphatic diacid;
(ii) 5 to 25 mole percent of sodioisophthalic acid;
(iii) a diol;
(iv) up to 75 mole percent of poly(ethylene glycol); wherein said sulfopolyester has a T
g
of about 25 to 125° C.
The term “water-dispersible” is of

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