Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Nonwoven fabric
Reexamination Certificate
1999-09-24
2002-05-21
Cole, Elizabeth M. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Nonwoven fabric
C442S414000, C525S276000, C525S199000, C525S200000, C264S147000, C264S176100, C264S210800, C264S235000, C428S421000, C524S462000, C524S463000, C526S227000, C526S243000
Reexamination Certificate
active
06391807
ABSTRACT:
This invention relates to fluorochemical compounds having oligomeric portions that contain pendent fluoroaliphatic and fluorine-free aliphatic groups. This invention also relates to polymer compositions comprising the fluorochemical composition and shaped articles made from the thermoplastic composition.
The utility of organofluorine compounds as surface-active agents (i.e., surfactants) and surface-treating agents is due in large part to the extremely low free-surface energy of a C
6
-C
12
fluorocarbon group, according to H. C. Fielding, “Organofluorine Compounds and Their Applications,” R. E. Banks, Ed., Society of Chemical Industry at p. 214 (1979). Generally, the organofluorine substances described above are those which have carbon-bonded fluorine in the form of a monovalent fluoroaliphatic radical such as a perfluoroalkyl group, typically —C
n
F
2n+1
, where n is at least 3, the terminal part of which group is trifluoromethyl, —CF
3
.
International Published Application WO 98/51723 (Allewaert et al.) discloses fluorochemical oligomer having the formula M
f
m
M
n
—Q
1
—T
1
, wherein M
f
m
M
n
represents fluorochemical oligomer comprising m units derived from fluorinated monomer and n units derived from fluorine-free monomer, m is from about 2 to 40, n is from 0 to 20, T
1
is —OH or —NH
2
, and Q
1
—T
1
together represent the organic residue obtained by removing a hydrogen atom from a chain transfer agent that is functionalized with T
1
.
European Publication EP 0670358 describes polymeric surfactants having a fluorocarbon segment and a hydrocarbon segment in the molecule, which can be made by co-polymerizing a polyfluoroalkyl group-containing (meth)acrylate with a long chain (meth)acrylic alkyl ester having at least 8 carbon atoms. The polymeric surfactants are useful for making fluorine-containing-oil-in-hydrocarbon-oil type emulsions.
J. Polymer Science, Part A 1988, 26, 2991 (Chujo et al.) describes a di-carboxyl terminated macromonomer prepared by the free radical co-polymerization of a perfluoroalkylethyl acrylate and methyl methacrylate in the presence of thiomalic acid. Also described is the reaction of such macromonomers with organic dicarboxylic acids and organic diamines in the presence of an appropriate catalyst to afford a copolymer wherein the macromonomer is grafted onto a polyamide chain.
Several patents have taught that the addition of certain fluorochemicals to thermoplastic imparts oil and stain repellency to thermoplastic articles such as fibers. For example, U.S. Pat. No. 5,025,052 (Crater et al.) describes the use of fluoroaliphatic radical-containing 2-oxazolidinone compounds having a monovalent fluoroaliphatic radical bonded to the 5-position thereof with an organic linking group. The compounds are said to be useful in the surface treatment of fibrous materials, such as textiles and are also useful in preparing fibers, films and molded articles by melt-extrusion or injection molding. U.S. Pat. No. 5,380,778 (Buckanin) describes the use of fluorochemical aminoalcohols in thermoplastic compositions which can be melted and shaped, for example by extrusion or molding, to provide fibers and films having desirable oil- and water-repellency properties. U.S. Pat. No. 5,451,622 (Boardman et al.) describes shaped articles, such as fibers and films, made by melt extruding mixtures of fluorochemical piperazine compounds and a thermoplastic polymer. U.S. Pat. No. 5,898,046 describes repellent compositions formed by the mixture of a thermoplastic polymer and a fluorocarbon/aliphatic hydrocarbon monoester, wherein the aliphatic hydrocarbon portion can have from about 12 to about 76 carbon atoms. International Published Application WO 97/22576 (Raiford et al.) describes fluorochemical diesters added to thermoplastic polymer melts which impart repellency of low surface tension fluids to the resultant fiber, fabric, nonwoven, film or molded article. International Published Application WO 99/05345 (Gasper et al.) discloses a hydrophobic and oleophobic fiber comprising synthetic organic polymer and a compound which is a fluorochemical ester or amide derived from a dimer or trimer acid. U.S. Pat. No. 5,411,576 (Jones et al.) describes an oily mist resistant electret filter media comprising melt-blown electret microfibers and a melt-processible fluorochemical having a melting point of at least about 25° C. and a molecular weight of about 500 to 2500, the fluorochemical being a fluorochemical piperazine, oxazolidinone or perfluorinated alkane having from 15 to 50 carbon atoms. U.S. Pat. No. 5,300,587 (Macia et al.) describes oil-repellent polymeric compositions made by blending a perfluoropolyether and a thermoplastic polymer. U.S. Pat. No. 5,336,717 (Rolando et al.) discloses fluorochemical graft copolymers derived from reacting monomers having terminal olefinic bonds with fluorochemical olefins having fluoroaliphatic groups and polymerizable double bonds.
International Published Application No. WO 98/15598 (Yamaguchi et al.) describes water- and oil-repellent resin compositions useful, e.g., for kitchenware and bathroom utensils, comprising thermoplastic or thermosetting resin and perfluoroalkylated polymer, such compositions exhibiting superior anti-fouling and mouldability. The perfluoroalkyl polymer can be a copolymer of a 5 to 18 carbon perfluoroalkyl group-containing (meth)acrylic ester and a hydrophilic group-bearing (meth)acrylic ester, with an optional copolymerizable comonomer which can be a C
1
-C
25
(meth)acrylic acid alkyl ester, preferably a C
8
-C
22
alkyl ester.
While these fluorochemical melt additives can in some circumstances impart satisfactory hydrophobicity and/or oleophobicity to thermoplastic resins they typically suffer from poor thermal stability above 300° C., a melt processing temperature often encountered in the industry, and they can also be prohibitively expensive, lending limitations to their commercial utility.
For many years nonwoven fibrous filter webs have been made from polypropylene using melt-blowing apparatus of the type described in Report No. 4364 of the Naval Research Laboratories, published May 25, 1954, entitled “Manufacture of Super Fine Organic Fibers” by Van Wente et al. Such melt-blown microfiber webs continue to be in widespread use for filtering particulate contaminants, e.g., as face masks and as water filters, and for other purposes, e.g., to remove oil from water.
Fibrous filters for removing particulate contaminants from the air are also made from fibrillated polypropylene films. Electret filtration enhancement can be provided by electrostatically charging the film before it is fibrillated. Common polymers such as polyesters, polycarbonates, etc. can be treated to produce highly charged electrets but these charges are usually short-lived especially under humid conditions. The electret structures may be films or sheets which find applications as the electrostatic element in electro-acoustic devices such as microphones, headphones and speakers and in dust particle control, high voltage electrostatic generators, electrostatic recorders and other applications.
SUMMARY OF THE INVENTION
This invention provides a polymer composition comprising a polymer and at least one fluorochemical oligomer comprising:
(i) an oligomeric portion having both fluoroaliphatic and fluorine-free aliphatic pendent groups;
(ii) an aliphatic moiety; and
(iii) a linking group which links the oligomeric portion to the aliphatic moiety; wherein the ratio of fluoroaliphatic pendent groups to fluorine-free aliphatic pendent groups is greater than or equal to 4.
A polymer composition of this invention can be melted or shaped, for example by extrusion or molding, to produce shaped articles, such as fibers, films and molded articles whose surfaces exhibit excellent oil- and water repellency. The repellent polymer composition is especially useful in the preparation of nonwoven fabrics used in medical gowns and drapes, where repellency to bodily fluids is mandated. Films made from repellent polymer compositions of this invention are useful, for ex
Jariwala Chetan P.
Klun Thomas P.
Cole Elizabeth M.
Kokko Kent S.
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