Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation specified as water repellent
Reexamination Certificate
1999-12-14
2002-09-17
Dawson, Robert (Department: 1712)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation specified as water repellent
C524S805000, C524S198000, C524S195000, C524S201000, C428S392000, C428S394000, C428S393000, C428S395000, C428S421000, C427S389900, C427S392000, C106S002000, C442S152000, C442S154000, C442S164000, C442S168000, C442S169000, C442S170000, C525S326200
Reexamination Certificate
active
06451717
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a composition and process for preparing an aqueous emulsion composition of a fluorochemical copolymer for imparting oil and water repellency to textiles, particularly to cotton or cotton blends, wherein the resulting textile has effective and highly durable initial and post-washing oil and water repellency.
BACKGROUND OF THE INVENTION
For many years the public has been accustomed to purchasing fabrics or garments prepared from natural cellulosic fibers such as cotton or its blends to which various sizing, repellency-enhancing and/or softening additives have been added to provide improved characteristics. However, these additives may also add undesirable characteristics to the fibers. As a result, it has become the practice to add one or more complementary materials which compensate for the imperfections of the various additives.
For example, crease-resistant resins added to fabrics consisting wholly or partially of cellulosic fibers provide enhanced appearance and minimize ironing, but at the same time the fabric is found to be more receptive to stains, particularly to oily stains. Release of these stains during cleaning, especially laundering, is found to be extremely difficult. This tendency can be alleviated by supplementing the fabric finish with a polymer containing fluoroaliphatic radicals. This confers a high degree of oil and water repellency to the fabric, and reduces the tendency to accept stains. A further improvement can be made by adding to the fluoropolymer an ingredient containing a hydroxyl group or other hydrophilic group to aid in releasing soil during laundering.
A fabric treated with resins also may have a harsher feel. Fabric softness can be improved by adding to the fluoropolymer an ingredient containing fatty alkyl groups.
The prior art discloses numerous specific polymers intended for application to textiles to bestow oil and water repellency properties. Such polymers are generally made from monomers which contain pendant perfluoroalkyl groups of three or more carbon atoms which provide the desired repellencies. These monomers are then generally copolymerized with other monomers to confer additional favorable properties to the textile fabrics. These polymers are generally marketed as aqueous emulsions for easy application to the fabric. The fabric-treating composition may also include other additives in addition to those copolymerized with the fluoropolymer. In particular, various compounds such as blocked isocyanates are frequently added after polymerization to promote durability of a desired property such as repellency. In such applications, the blocking agent is removed from the isocyanate under the thermal conditions used when curing the treated fabric, allowing the isocyanate group to interact with the fabric and improve the desired durability.
In one class of such compounds found to be useful for treating cotton or cotton blends, the perfluoroalkyl groups are connected to polyurethane groups as monomers. However, such urethanes and their isocyanate intermediates are costly and potentially hazardous to manufacture.
In a second class of fluoropolymers useful for treating cotton and cotton blends, the perfluoroalkyl groups are connected to (meth)acrylate groups. By “(meth)acrylate” is meant methacrylate, acrylate, or a combination of these groups. These fluoropolymers can be copolymerized with other monomers, such as non-fluorine-containing (meth)acrylate compounds containing a long-chain fatty alkyl group and/or a hydrophilic group. These products have the advantage that they do not involve costly and potentially hazardous isocyanate/urethane chemical manufacturing steps (except indirectly, for any blocked isocyanates added).
A fluorochemical copolymer composition for imparting oil and water repellency to fabrics which is more effective than existing urethane or (meth)acrylate fluoropolymers would have widespread applications, in particular wherein the resulting textile has effective and highly durable initial and post-washing oil and water repellency. The present invention provides such fluorochemical copolymer compositions.
SUMMARY OF THE INVENTION
The present invention comprises an oil- and water-repellent aqueous emulsion prepared by:
1) forming a monomer mixture comprising by weight:
(a) 70-90% polymer chain units derived from a mixture of monomers of the formula:
R
f
—Q—A—C(O)—C(R)═CH
2
wherein
R
f
is a straight or branched-chain perfluoroalkyl group containing from 2 to about 20 carbon atoms,
R is H or CH
3
,
A is O, S, or N(R′),
Q is alkylene of 1 to 15 carbon atoms, hydroxyalkylene of 3 to 15 carbon atoms, —(C
n
H
2n
)(OC
q
H
2q
)
m
—, —SO
2
—NR′(C
n
H
2n
)—, or —CONR′(C
n
H
2n
)—, wherein R′ is H or alkyl of 1 to about 4 carbon atoms, n is 1 to about 15, q is 2 to about 4, and m is 1 to about 15;
(b) 5-25% monomer chain units derived from a long-chain alkyl (meth)acrylate of the formula:
R″—O—C(O)—C(R)═CH
2
wherein R″ is an alkyl group of about 12 to about 24 carbons and R is H or CH
3
;
(c) 0.1-2.5% monomer chain units derived from compounds of the formulas:
HO—CH
2
—CH
2
—O—C(O)—C(R)═CH
2
or
HO—CH
2
—N(H)—C(O)—C(R)═CH
2
,
wherein R is H or CH
3
;
2) polymerizing the mixture of monomers (a), (b) and (c) in an organic solvent using a free radical initiator as catalyst;
3) adding, in an organic solvent or alone, 10-90% of a blocked aromatic isocyanate (d) relative to the weight of fluoropolymer, with both weights on a solvent-free basis;
4) adding the mixed fluoropolymer-isocyanate solvent solution to water under conditions so as to create an aqueous dispersion of the fluoropolymer-isocyanate mixture; and,
5) removing most or all of the organic solvent from the aqueous dispersion of the fluoropolymer-isocyanate mixture.
The present invention further comprises a process for preparing an oil- and water-repellent aqueous emulsion comprising steps (1) through (5) as recited above.
The present invention further comprises a method of treating fabrics or fabric blends to impart oil- and water-repellency comprising application to the surface of the fabric or fabric blend of an effective amount of the inventive aqueous emulsion as described above.
The present invention still further comprises a fabric or fabric blendwhich has been treated according to the method of the present invention as described above.
DETAILED DESCRIPTION OF THE INVENTION
In the present description trademarks are indicated by capitalization.
The present invention comprises a process for preparing an aqueous emulsion, and the resulting emulsion, useful for imparting oil- and water-repellency with high washing durability to fabrics or fabric blends, particularly to cotton fabrics or blends. By “fabrics” is meant natural or synthetic fabrics composed of fibers of cotton, rayon, silk, wool, hemp, polyester, spandex (including LYCRA), polypropylene, polyolefins, nylon, aramids, and poly(trimethylene terephthalate). By “fabric blends” is meant fabrics made of two or more types of fibers. Typically these blends are a combination of a natural fiber and a synthetic fiber, but can also include a blend of two natural fibers or two synthetic fibers. Superior oil- and water-repellency properties can be imparted to fabrics or fabric blends by the addition of certain fluorochemical copolymers. These can be applied to the fabric in the form of an emulsion or dispersion in water or other solvent either before, after or during the application of other fabric treatment chemicals.
The inventive, highly efficient copolymers useful for this purpose are characterized in that they are made by forming a monomer mixture of (a) a perfluoroalkyl compound, (b) a long-chain alkyl (meth)acrylate and (c) hydroxyethyl methacrylate or hydroxyethyl (meth)acrylamide, polymerizing the monomer mixture in an organic solvent, adding a blocked aromatic isocyanate (d) to the fluoropolymer solution, adding a water/surfactant mixture in such a way as to form an aqueous dispersion of the fluor
Fitzgerald John J.
Sherman Melissa Ann
Dawson Robert
E. I. du Pont de Nemours and Company
Peng Kuo-Liang
LandOfFree
Highly durable oil/water repellents for textiles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Highly durable oil/water repellents for textiles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Highly durable oil/water repellents for textiles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2838175