Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-12-05
2003-02-11
Zitomer, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S263000, C526S287000, C526S310000, C526S312000
Reexamination Certificate
active
06518380
ABSTRACT:
FIELD OF THE INVENTION
The subject of the present invention is novel fluorocopolymers and their use for the coating and the impregnation of various substrates, such as textiles, leather, wood, non-wovens, metal, concrete, stone and, more particularly, paper and similar articles, for the purpose of making them oleophobic and hydrophobic. The invention also relates to the substrates thus treated.
BACKGROUND OF THE INVENTION
To achieve this objective, many fluoroderivatives have already been proposed.
International Application WO 98/23657 thus teaches cationic fluorocopolymers capable of being obtained by the copolymerization of:
52 to 92% by weight of one or more polyfluoromonomers of general formula:
in which Rf represents a perfluorinated radical, having a straight or branched chain, containing 2 to 20 carbon atoms, preferably 4 to 16 carbon atoms, B represents a divalent linking which is linked to O by a carbon atom and which may comprise one or more oxygen, sulphur and/or nitrogen atoms, one of the symbols R represents a hydrogen atom and the other a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms;
1 to 25% of one or more monomers of general formula:
in which B′ represents a linear or branched alkylene radical containing 1 to 4 carbon atoms, R′ represents a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, the symbols R
1
and R
2
, which are identical or different, each represent a hydrogen atom, a linear or branched alkyl radical containing 1 to 18 carbon atoms or a hydroxyethyl or benzyl radical, or R
1
and R
2
together with the nitrogen atom to which they are linked form a morpholino, piperidino or pyrrolidin-1-yl radical;
1 to 25% of a vinyl derivative of general formula:
R″—CH═CH
2
in which R″ may be an alkyl carboxylate or alkyl ether group containing from 1 to 18 carbon atoms.
The copolymerization reaction leading to the fluorocopolymers described by that international application is carried out in solution in a water-miscible organic solvent or solvent mixture and is followed by a step of dilution with an aqueous solution of a mineral or organic acid. This dilution step is carried out in the presence of hydrogen peroxide or is followed by a treatment by means of an aqueous hydrogen peroxide solution.
After the said dilution step, it is necessary to carry out a vacuum distillation or to flush with an inert gas, for example nitrogen, in order to remove the volatile compounds and to obtain a composition that can be sold and applied to the substrate to be treated.
The solvents exemplified in that application are, mostly, mixtures based on N-methylpyrrolidone. Because of their boiling point, these solvents are not completely removed by the distillation operation so that significant quantities of them remain in the commercial composition.
This commercial composition is thus in the form of a solution, thereby giving it stability properties which are highly advantageous for its transportation and its storage.
However, for some applications, and especially for the treatment of papers or similar articles intended for the field of packaging food products, it is desirable to reduce the amount of any solvents in commercial compositions, or even to completely eliminate them therefrom.
International Application WO 98/23657 mentions (cf. page 5 lines 14-15) that the use of light solvents makes it possible to obtain, after distillation, a commercial composition containing no organic solvent.
However, during the operation of distilling these light solvents, a gradual precipitation of the cationic fluorocopolymers occurs, which then results in an unstable aqueous dispersion, i.e. one which results in a settling in a few hours. Such a dispersion is unsuitable as a commercializable composition.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that the introduction of an anionic monomer, or a monomer which is potentially anionic by varying the pH, into the copolymers described by the international application, and a modification to their synthesis process, makes it possible to obtain novel fluorocopolymers which confer on various substrates, and especially on paper, the same hydrophobic and oleophobic properties and which, in addition, may be in the form of aqueous compositions which contain no organic solvents and are stable over time.
Fluorocopolymers according to the present invention are obtained by polymerization of a monomer mixture comprising by weight:
(a) from 50 to 92%, preferably from 70 to 90%, of one or more polyfluoromonomers of general formula:
in which:
Rf represents a perfluorinated radical having a straight or branched chain, containing 2 to 20 carbon atoms, preferably 4 to 16 carbon atoms,
B represents a divalent linking which is linked to O by a carbon atom and which may comprise one or more oxygen, sulphur and/or nitrogen atoms,
one of the symbols R represents a hydrogen atom and the other a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms;
(b) from 1 to 25%, preferably from 8 to 18%, of one or more monomers of general formula:
in which:
B′ represents a linear or branched alkylene radical containing 1 to 4 carbon atoms,
R′ represents a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms,
the symbols R
1
and R
2
, which are identical or different, each represent a hydrogen atom, a linear or branched alkyl radical containing 1 to 18 carbon atoms or a hydroxyethyl or benzyl radical, or R
1
and R
2
together with the nitrogen atom to which they are linked form a morpholino, piperidino or pyrrolidin-1-yl radical;
(c) from 0.5 to 20%, preferably from 1 to 10%, of an anionic monomer or a monomer which is potentially anionic by varying the pH (III), such as alkene carboxylic acids, monoolefinic derivatives of sulphonic acid, and their salts of alkali or alkaline-earth metals;
(d) from 2 to 10% of a vinyl derivative of general formula:
R″—CH═CH
2
(IV)
in which R″ may be an alkyl carboxylate or alkyl ether group containing from 1 to 18 carbon atoms;
(e) from 0 to 10%, preferably from 0 to 8%, of any monomer other than the monomers of formulae I, II, III and IV;
With regard to monomer (c), mention may be made especially of (meth)acrylic acid as an example of an alkene carboxylic acid and acrylamidomethyl-propanesulphonic acid as an example of a monoolefinic derivative of sulphonic acid.
The fluorocopolymers according to the present invention are prepared by copolymerization of the monomers in solution in a distillable organic solvent. The term “distillable” solvent is understood to mean any organic solvent or solvent mixture whose boiling point at atmospheric pressure is less than 150° C. Next, the reaction mixture is diluted with water in the presence of a mineral or organic acid in order to salify the macromolecules.
According to a preferred variant of the invention, this dilution step is carried out in the presence of hydrogen peroxide or is followed by a treatment by means of an aqueous hydrogen peroxide solution.
These fluorocopolymers can be applied to various substrates, such as leather, non-wovens, building materials, paper and board. In particular, they can be applied to paper using various techniques (applied in a size press or applied in the bulk), thus giving the paper, without the need for additives (sequestrants, retention agents, fixing resins, etc.), excellent hydrophobic and oleophobic properties.
According to the present invention, it is preferred to use:
(a) as polyfluoromonomers of formula I, the compounds of formula:
in which R
F
is a perfluoroalkyl radical containing 4 to 16 carbon atoms;
(b) dimethylaminoethyl methacrylate or N-tert-butylaminoethyl methacrylate as monomer of formula II;
(c) methacrylic acid as monomer of formula III; and
(d) vinyl acetate as monomer of formula IV.
As distillable organic solvent in which the copolymerization is carried out, mention may be made by way of non-limiting example of ketones (for example acetone or methyl ethyl ketone), of alcohols (for example isopropanol) an
Corpart Jean-Marc
Juhue Didier
Lina Marie-Jose
N'Zudie Denis Tembou
Pabon Martial
E. I. du Pont de Nemours and Company
Zitomer Fred
LandOfFree
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