Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-05-11
2001-09-11
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S463000, C526S242000, C526S250000, C526S253000, C526S254000, C526S255000
Reexamination Certificate
active
06288157
ABSTRACT:
This invention relates to fluorochemical compositions for use in providing repellent properties to a substrate material. In another aspect, this invention relates to fluorochemical compounds that contain pendent fluoroaliphatic groups proximal to one another. In yet another aspect, it relates to fluorochemical compounds that are at least in part oligomeric in nature. This invention also relates to thermoplastic 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
.
U.S. Pat. No. 3,758,447 (Falk et al.) describes polymers that result from free radical polymerization of a monomer in the presence of perfluoroalkyl mercaptans, which act as chain-transfer agents. Mercaptans that contain pairs or triplets of closely-packed perfluoroalkyl groups are said to produce polymers with higher oil repellency levels compared with analogous polymers derived from a mercaptan with just one perfluoroalkyl group or perfluoroalkyl groups that are not closely packed.
U.S. Pat. No. 5,453,540 (Dams et al.) describes fluorochemical compositions for the treatment of textiles comprising: (i) a fluorochemical oligomeric portion comprising an aliphatic backbone with a plurality of fluoroaliphatic groups attached thereto, each fluoroaliphatic group having a fully fluorinated terminal group and each independently linked to a carbon atom of the aliphatic backbone through an organic linking group;(ii) an organic moiety (which can be functional or non-functional, and which is different from the fluorochemical oligomeric portion); (iii) a non-polymeric isocyanate-derived linking group which links the fluorochemical oligomeric portion to the organic moiety; and
(iv) a group bonded thereto, which can impart soft hand, stain release, water repellency, or a durable property when the compound is applied to a fibrous substrate.
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 impart 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. 5,411,576 (Jones et al.) describes an oily mist resistant electret filter medium 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 termianl olefinic bonds with fluorochemical olefins having fluoroaliphatic groups and polymerizable double bonds.
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.
Fibrous polypropylene electret filters that are currently available, some made from melt-blown polypropylene microfibers and others from fibrillated polypropylene film, can show thermally stable electret filtration enhancement. Unfortunately, fibrous electret filters made of polypropylene, whether melt-blown microfibers or fibrillated film, tend to lose their electret enhanced filtration efficiency faster than desired for some purposes when exposed to oily aerosols. There is a growing awareness of the need to improve the long-term efficiency of air filters in the presence of aerosol oils, especially in respirators. It is known to blend about 1 to 20 weight percent poly(4-methyl-1-pentene) with polypropylene to provide resistance to loss of electret enhanced filtration efficiency on exposure to oily aerosols.
SUMMARY OF THE INVENTION
This invention provides fluorochemical compounds comprising:
(i) a fluorochemical oligomeric portion comprising an aliphatic backbone with a plurality of pendant fluoroaliphatic groups, each fluoroaliphatic group having a fully fluorinated terminal group and each independently linked to a carbon atom of the aliphatic backbone through an organic linking group;
(ii) an aliphatic moiety; and
(iii) a linking group which links the fluorochemical oligomeric portion to the aliphatic moiety.
In another aspect, the present invention provides a fluorochemical composition comprising at least one fluorochemical compound described above.
In another aspect, the present invention provides a synthetic organic polymer composition comprising the alkylated fluorochemical oligomer described above and a thermoplastic or thermoset synthetic organic polymer, such a
Dams Rudolf J.
Jariwala Chetan P.
Jones Marvin E.
Klun Thomas P.
3M Innovative Properties Company
Cain Edward J.
Kokko Kent S.
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