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
1999-06-01
2001-04-17
Yoon, Tae H. (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...
C524S048000, C428S522000
Reexamination Certificate
active
06218464
ABSTRACT:
The present invention relates to the preparation of fluorinated polymers. In particular, the present invention relates to an improved preparation of fluorinated emulsion polymers.
Fluorinated polymers have many desirable properties such as superior weather resistance, high temperature resistance, water and oil repellency, low surface tension, chemical inertness, and low flammability. These properties have resulted in the use of fluorinated polymers as coating materials for textiles and various substrates in many industrial areas.
It is well known that is is very difficult to prepare emulsion polymers from perfluorinated monomers, particularly those containing long perfluorinated alkyl chains, such as fluoroalkyl groups having 4 to 20 carbon atoms, because these monomers are inherently water insoluble and have poor solubility in most organic hydrocarbon solvents and monomers. The insolubility of perfluorinated monomers limits their ability to be transported from monomer droplets to polymerizing particles. As a result, particle size distribution is broad, composition of a copolymer may not be uniform and high levels of gel form during the polymerization. Such gel formation is undesirable.
Various methods of polymerizing fluorinated monomers are known, such as by using an organic solvent having high solubility in both water and in the perfluorinated monomers. Such solvents aid the transport of monomer from the monomer droplets to the polymerizing particles. Other methods use relatively high levels of fluorinated surfactants to avoid gels or a combination of fluorinated surfactant and a compatibilizer containing a perfluorinated segment and a hydrocarbon segment. All of these methods have the disadvantage of introducing “foreign” components to the polymer latex. Solvents contribute to volatile organic compound (“VOC”) content, and perfluorinated surfactants dilute the polymer content and end up in the polymer film where they can migrate and thereby alter the surface composition and properties of the film. Also, the use of large amounts of fluorinated surfactants adds to the cost of the polymer latex. However, reducing the amount of fluorinated surfactants leads to increased gel formation, which is undesirable.
U.S. Pat. No. 5,521,266 (Lau) discloses the emulsion polymerization of hydrophobic hydrocarbon monomers using cyclodextrin. The presence of cyclodextrin facilitates the transport of hydrophobic long alkyl chain monomers through the aqueous phase so that they can be homo- or copolymerized in a conventional emulsion polymerization process. There is no disclosure of the applicability of this method of emulsion polymerization to perfluorinated monomers.
The incompatability of fluorocarbons with hydrocarbons or water is well known, as evidenced by the use of fluorocarbon coatings for non-stick cooking surfaces. The cavity of cyclodextrin is a sugar ring having hydroxylated hydrocarbons. That cyclodextrins can be used to transport fluorinated monomers through the aqueous phase in emulsion polymerizations is unexpected and was not recognized in U.S. Pat. No. 5,521,266.
The present invention seeks to overcome the problems associated with known methods for preparing fluorinated emulsion polymers.
The present invention provides a method for preparing a fluorinated emulsion polymer comprising, as polymerized units, at least one fluorinated monomer and at least one non-fluorinated monomer having high water solubility, comprising the steps of:
a) providing a reaction mixture comprising
i) water,
ii) surfactant,
iii) monomer mixture comprising from 1 to 99 percent by weight of at least one fluorinated monomer, from 1 to 10 percent by weight of at least one non-fluorinated monomer having high water solubility, and from 0 to 98 percent by weight of at least one non-fluorinated monomer having low water solubility,
iv) macromolecular organic compound having a hydrophobic cavity; and
b) polymerizing said monomer mixture.
The present invention further provides a composition comprising a macromolecular organic compound and a fluorinated emulsion polymer comprising, as polymerized units, from 1 to 99 percent by weight of at least one fluorinated monomer, from 1 to 10 percent by weight of at least one non-fluorinated monomer having high water solubility, and from 0 to 98 percent by weight of at least one non-fluorinated monomer having low water solubility.
The present invention further provides an article comprising a coated substrate wherein the coating comprises the composition above.
The present invention provides a method for preparing fluorinated emulsion polymers that reduces or eliminates the need for a fluorinated surfactant. The present invention also provides a method for preparing fluorinated emulsion polymers that has reduced gel formation.
As used herein, the term “having low water solubility” means having water solubility at a temperature in the range of from 25 to 50° C. of no greater than 200 millimoles/liter. The term “having high water solubility” means having water solubility at a temperature in the range of from 25 to 50° C. of greater than 200 millimoles/liter. As used herein, the term “(meth)acrylate” refers to methacrylate and acrylate, the term “(meth)acrylic” refers to methacrylic and acrylic, and the term “(meth)acrylamide” refers to methacrylamide and acrylamide. The term “fluoroalkyl” means a partially fluorinated or perfluorinated (C
1
-C
20
)alkyl. “Alkyl” means linear or branched alkyl. All amounts are percent by weight unless otherwise noted, and all weight percent ranges are inclusive. As used herein, the following abbreviations are applied: “g”=grams; “AATCC”=American Association of Textile Chemists and Colorists; “BA”=butyl acrylate; “MMA”=methyl methacrylate; “MAA”=methacrylic acid; “2-EHA”=2-ethylhexyl acrylate; and “STY”=styrene.
Suitable fluorinated monomers include, but are not limited to: fluoroalkyl (meth)acrylate; fluoroalkylsulfoamidoethyl (meth)acrylate; fluoroalkylamidoethyl (meth)acrylate; fluoroalkyl (meth)acrylamide; fluoroalkylpropyl (meth)acrylate; fluoroalkylethyl poly(alkyleneoxide) (meth)acrylate; fluoroalkylsulfoethyl (meth)acrylate; fluoroalkylethyl vinyl ether; fluoroalkylethyl poly(ethyleneoxide) vinyl ether; pentafluoro styrene; fluoroalkyl styrene; fluorinated &agr;-olefins; perfluorobutadiene; 1-fluoroalkylperfluorobutadiene; &agr;H,&agr;H,&ohgr;H,&ohgr;H-perfluoroalkanediol di(meth)acrylate; and &bgr;-substituted fluoroalkyl (meth)acrylate. Preferred fluorinated monomers have a fluoroalkyl group having form 4 to 20 carbon atoms. Particularly preferred is fluoro(C
6
-C
20
)alkyl (meth)acrylate. Especially preferred fluorinated monomers are perfluorooctylethyl methacrylate and perfluorooctylethyl acrylate.
Suitable non-fluorinated monomers having low water solubility include, but are not limited to: &agr;,&bgr;-ethylenically unsaturated monomers such as primary alkenes; styrene and alkylsubstituted styrene; &agr;-methyl styrene; vinyltoluene; vinyl esters of (C
4
-C
30
)carboxylic acids, such as vinyl 2-ethylhexanoate and vinyl neodecanoate; vinyl chloride; vinylidene chloride; N-alkyl substituted (meth)acrylamide, such as octyl acrylamide and maleic acid amide; vinyl alkyl or aryl ethers with (C
3
-C
30
)alkyl groups, such as stearyl vinyl ether; (C
1
-C
30
)alkyl esters of (meth)acrylic acid, such as methyl methacrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate; unsaturated vinyl esters of (meth)acrylic acid, such as those derived from fatty acids and fatty alcohols; multifunctional monomers, such as pentaerythritol triacrylate; and monomers derived from cholesterol. These monomers may also contain functionality, such as, but not limited to: hydroxy, amido, aldehyde, ureido, and polyether.
Suitable non-fluorinated monomers having high water solubility include, but are not limited to: &agr;,&bgr;-monoethylenically unsaturated monomers containi
Lau Willie
Parker Hsing-Yeh
Rosenlind Erik S.
Cairns S. Matthew
Rohm and Haas Company
Yoon Tae H.
LandOfFree
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