MXPA98008919A - Copolymers of vinylidene fluoride and hexafluoropropylene having reduced extractable content and improved solution clarity - Google Patents

Abstract

New and novel copolymers of vinylidene fluoride and hexafluoropropylene containing up to about 24%by weight hexafluoropropylene having improved solution clarity and fluidity, longer gel times and lower extractables than prior art vinylidine fluoride-hexafluoropropylene copolymers of comparable HFP content whose syntheses are disclosed in sufficient detail to duplicate, the novel compositions of matter and articles of manufacture containing such copolymers, of the compositions of matter containing such copolymers and of the articles of manufacture containing such copolymers are disclosed. Also disclosed are novel battery constructions based on the novel copolymers of vinylidene fluoride/hexafluoropropylene copolymers of the invention, on vinylidene fluoride homopolymers having a bimodal molecular weight distribution and on vinylidene fluoride/chlorotrifluoroethylene copolymers having a substantially homogeneous monomer distribution.

Description

COPOLYMERS OF V1NIHDENUM FLUORIDE AND HEXAFLUOROPROPYLENE THAT HAVE A CONTENT REMOVABLE REDUCED AND CLARITY OF IMPROVED SOLUTION RELATED REQUESTS This application claims the benefit of the provisional application serial number 60 / 038,346, filed on February 28, 1997.

BACKGROUND OF THE INVENTION This invention relates to compositions of matter classified in the field of chemistry as fluoropolymers, more specifically as copolymers of vinylidene fluoride (VDF), more specifically as copolymers of vinylidene fluoride and hexafluoropropylene (HFP), even more specifically as copolymers of VDF and H FP having a reduced extractable content, longer gel formation times and clarity of improved solution, novel compositions of matter and articles of manufacture containing said copolymers, as well as processes for the preparation and use of the copolymers , of manufacturing compositions containing said copolymers and of articles of manufacture containing said copolymers. VDF / H FP copolymers are well known and are used for their thermoplastic engineering design properties, chemical resistance of inertia towards degradation. They can be found in applications such as chemically resistant pipe, joint formation, full cable jacketing, filtration and extraction membranes and in the construction of lithium batteries. The present invention provides VDF / HFP copolymers containing up to about 24% by weight (12 mol%) of HFP having among other improved properties, a substantially improved clarity of solution, longer gel-forming times and reduced extractables, such as These terms are defined herein. The process used to make the copolymers herein requires a ratio of VDF and HFP for the initial filling of the reactor, and a different ratio of VDF and HFP during a subsequent continuous feed of the monomers. Any particularly desired average HFP content in the copolymer product has corresponding particular, initial filling and subsequent feed ratios. The uniformity of the compositions prepared in this manner provides unique and useful properties compared to the VDF / H FP copolymers described in the prior art. The present invention also provides lithium batteries made from copolymers of VDF / H FP of the present invention and lithium batteries of other homo and copolymers more specifically described below prepared through known procedures having analogous structure and which the inventors of the present have recognized as processing properties analogous to those of the VDF / H FP copolymers of the invention which make them uniquely suitable for the construction of lithium batteries.

DESCRIPTION OF THE PREVIOUS TECHNIQUE Rexford in the patent of E. U.A. No. 3,051,677 described copolymers of VDF / H FP with an H-FP content of 30 to 70% by weight (15 to 50 mol%), which showed utility as elastomers. To make these copolymers, an intermittent process with certain initial ratios of VDF and HFP, and a continuous process with fixed ratios of VDF and H FP through the process were described. The methods described were such that polymers lacking clarity of improved solution, longer gel-forming times and low production of extractable products of the present invention were made. The in the patent of E. U.A. No. 3, 178,399 described copolymers of VDF / H FP with an H-FP content of 2 to 26% by weight (from 1 to 13 mol%), which showed a numerical value for the product of the tensile strength (kg. / cm2 gauge) and a percentage of reversible elongation of at least 1, 000,000. To make the copolymers they used an intermittent procedure with certain initial ratios of VDF and H FP or, alternatively, a semicontinuous procedure with fixed ratios of VDF and HFP through the procedure. The methods discussed were such that copolymers lacking clarity of improved solution, longer gel-forming times and low production of extrudable products of the present invention were made. Moggi, et al. ~ 'E "ñ Polymer Bulletin 7, 115-122 (1982) analyzed the microstructure and crystal structure of VDF / HFP copolymers through nuclear magnetic resonance and X-ray diffraction experiments. The copolymers up to 31% by weight (up to 16 mol%) of H FP were made in an intermittent emulsification process, which was carried out only at low conversion, since the intermittent low conversion process is capable of producing copolymers that have clarity of solution and a low content of extractables, such properties are not described, it is not a practical procedure for industrial use due to the low conversions required to make the materials, and detailed polymerization examples are not offered Bonardelli et al. Polymer, vol.27, 905-909 (June 1986) studied the glass transition temperatures of the VDF / H FP copolymers having an H-FP content of up to 62% by weight (up to 4% by weight). 1 mole%.) Glass transition temperatures correlated to the total content of H FP in the copolymers. To make the copolymers for analysis, a semicontinuous emulsion process was used, which employed different ratios of VDF / H FP for the initial filling of the reactor and for the subsequent continuous feeding of monomers. Although reference was made to the use of reactivity ratio to fix the VDF / HFP ratio for the initial fill, no detailed polymerization examples were offered, and copolymers having solution clarity, gel formation times and low production are not mentioned. of extractable products comparable with those of the copolymers of the present invention. Pianca et al. in Polymer, vol. 28, 224-230 (Feb. 1987) examined the microstructure of the VDF / HFP copolymers through nuclear magnetic resonance, and the microstructure determinations were used to explain the trends in the glass transition temperatures of the copolymers. The synthesis of the copolymers involved a semicontinuous emulsion process, which used different ratios of VDF / H FP for the initial filling of the reactor and for subsequent continuous feeding of monomers. No detailed synthesis examples were provided, and there was no discussion of the copolymers having improved clarity of solution, longer gel-forming times, and a low production of extractables as provided by the copolymers of the present invention. Abusleme et al. in the European patent application number 650, 982 A 1, they showed an emulsion process for making fluorinated polymers and copolymers optionally with one or more non-fluorinated oiefins. The process was based on the photochemical initiation of the polymerization, so that lower temperatures and pressures than those used for the thermally initiated processes could be used. Although there is a general mention of the structural regularity of the resulting polymers, the only evidence of regularity had to do with the homopolymer of polyvinylidene fluoride, and there are no claims of composition regularity. Examples of copolymerization of VDF / H FP were given, but no discussion of the extraction properties of the solution of the copolymers was given, and there was no relationship between the physical properties and the structure of the copolymers of VDF / H FP . Morgan in the patent of E. U.A. No. 5,543,217 described uniform tetrafluoroethylene / hexafluoropropylene copolymers (copolymers of TFE / H FP) made through a semi-continuous emulsion process. The niformity was simply defined as being a low proportion of adjacent HFP units in the polymer chains; there is no description of the disposition of the units of TFE and H FP, and there is no discussion of the copolymers of VDF / H FP or the properties that are expected of them. None of these references teaches or suggests a way to obtain VD F / HFP copolymers having clarity and fluidity of solvent solution, longer gel formation times and a low content of extractables as compared to VD F / H copolymers. FP of the present invention or that said properties can be obtained from the VDF / HFP copolymers.

The patent of E.U.A. No. 4,076,929 describes the synthesis of a VDF homopolymer having a relatively high defect structure uniformly distributed in its molecular claims. The patent of E.U.A. 2,752,331 describes the synthesis of VDF / chlorotrifluoroethylene copolymer (CTFE) having a high uniformity of comonomer distribution in its molecular chains. Baggett and Smith in High Polymers, Vol. XVIII, Ham, John Wiley (1964), Chapter X, Copolymerization, p. 587 et seq., Particularly pages 593 and 610, describe the synthesis of uniform composition distribution copolymers of vinylidene chloride and vinyl chloride and of vinyl chloride and vinyl acetate. The patent of E.U.A. 5,296,318 teaches that only VDF / HFP copolymers having from 8 to 25% by weight of HFP and no other VDF homopolymers or copolymers are suitable for use in the manufacture of lithium battery electrodes and separators. The patent of E.U.A. 5,348,818 mentions that among other polymers, the VDF polymer can be used to form a solid electrolyte for use in the manufacture of secondary battery. No particular type of polyvinylidene fluoride is identified and no copolymer thereof of any kind is suggested. European patent application 95 120 660.6-1215, published on September 4, 1996 teaches the use of microporous VDF copolymers (open or closed cell) with a comonomer content of about 7% to about 25% in lithium batteries and the use of a VDF homopolymer as a coating material for said batteries. The use of copolymers used by the present invention in solid electrolytes and the improved properties provided by them are not taught or suggested. Similarly, the use of the VDF homopolymer type used in the present invention in solid electrolytes is not taught or suggested. None of the references teach or suggest lithium oscillating seat batteries of the type contemplated by the present invention and the patent of E. U.A. 5,296, 318 expressly teaches from the use of the VDF homopolymer of any type, VDF / H FP copolymers with an H FP content of less than 8% by weight or other VDF-containing copolymers. The patent of E. U.A. 5, 571, 634 teaches a lithium-ion battery construction employing a VDF-CTFE copolymer wherein the CTFE content in the copolymer is not less than 8% by weight.

COMPENDIUM OF THE INVENTION The invention provides a first aspect of composition which is a copolymer of vinylidene fluoride and hexafluoropropylene containing a maximum of about 24% by weight of hexafluoropropylene, having improved clarity and fluidity solutions; copolymers with up to about 8% nominal H-FP content, having a weight percentage of extractable products within plus or minus 1.5% by weight of the extractable products calculated through an equation selected from the group consisting of: a )% / weight of extractables = 1.7 (HFP% molar) - 3.2, and b)% / weight of extractables = a -1.2 + 1.5 (HFP% molar) - 8 x 10"6 (Mn), and for copolymers having more than about 8% by weight of nominal H-FP content, having a DSC (differential scanning calorimetry) melting point of at least 2.5 ° C lower than the DSC melting point of copolymers having the same nominal weight percentage of H FP prepared by the methods for which the prior art provides details The tangent monomers of the first compositional aspect of the invention are semi-crystalline straw-to-colorless solid having fusion, according to completed by differential scanning calorimetry (DSC), lower than the VDF / H FP copolymers having the same nominal percentage HF% content prepared through procedures reported in detail in the prior art. The tangible modalities of this first aspect of the composition of the invention also possess longer gelation times from the solution than the VDF / HFP copolymers having the same nominal HFP content prepared through procedures reported in detail in the art. previous. The aforementioned physical characteristics taken together with the synthesis method positively tend to confirm the structure and novelty of the compositions that are sought to be patented. The tangible embodiments of the first compositional aspect of the invention have the inherent applied characteristics of being suitable for vehicles coated with paint and powder and as chemically resistant shaped objects and both supported and unsupported films. Particular mention is made of the copolymers of the first composition aspect of the present invention having from about 2% by weight of HFP content to about 8% by weight of H FP., more particularly copolymers having about 3 to 6% by weight of H FP, which possess the inherent applied characteristics of use being particularly suitable as polymeric separators and polymeric electrode matrices for batteries, particularly lithium batteries. The prior art, see for example patent of E. U.A. 5,296, 318 reported lithium batteries made of PVDF / H FP copolymers having from 8% to 25% by weight of HFP. It is understood that the copolymers of the present invention having an H-FP content on that scale are suitable for use in such batteries and could represent an improvement therein. Said improved batteries are also contemplated by the invention as equivalents. Particular mention is also made of the copolymers of the first composition aspect of the invention having from about 7% by weight of HFP content to about 15% by weight of H-FP content, more particularly, copolymers having about 10% by weight. weight of an HFP content, which possess the inherent applied characteristic of being suitable as flame resistant insulation for wires and cables. Further mention is made of the copolymers of the first composition aspect of the invention having more than about 15% by weight H-HP content, even more particularly of copolymers having about 16% by weight or a higher H content. FP, which have the characteristic of inherent applied use as transparent, flexible, chemically resistant films. The invention provides a second composition of the subject matter, an improved article of manufacture comprising an electrochemical cell having a positive electrode, an absorbing spacer and an electrode, wherein at least any of the electrodes comprises a polymer of vinyl idene fluoride having an electrolyte material combined therewith and / or said absorber separator comprises a vinylidene fluoride polymer having an electrolyte material combined therewith, wherein the improvement comprises the polyvinylidene fluoride polymer consisting of essentially of a vinylidene fluoride polymer selected from the group consisting of vinylidene fluoride homopolymer having a bimodal molecular weight distribution, fluoride / chlorotrifluoroethylene copolymer having a substantially homogeneous monomer distribution and a copolymer of vinylidene fluoride / hexafluoropropylene how do you define yourself in the first aspect of composition of the invention. Special mention is made of embodiments of the second composition of the invention, wherein the copolymer of VDF / H FP has a hexafluoropropylene content of about 2% by weight of hexafluoropropylene to about 8% by weight, particularly those having 3% by weight. by weight at 6% by weight of hexafluoropropylene, very particularly those having about 3% by weight of hexafluoropropylene. The vinylidene fluoride homopolymer having a bimodal molecular weight distribution represents a homopolymer of vinylidene fluoride prepared as described in the U.A. 4,076,729. The vinylidene fluoride / chlorotrifluoroethylene copolymer having a substantially homogeneous monomer distribution represents a copolymer of vinylidene fluoride / chlorotrifluoroethylene prepared as described in the U.S.A. 2,752,331. Special mention is made of VDF / CTFE copolymers having a CTFE content of about 2% by weight to about 8% by weight, more particularly said VDF / CTFE copolymers having a CTFE content of about 3 to about 6% in weigh. As used herein and in the appended claims, the vinylidene fluoride (or VDF copolymer) polymers herein represent the polyvinylidene fluoride homopolymer having a bimodal molecular weight distribution as defined above., the VDF / CTFE copolymers having a substantially uniform monomer distribution as defined above and / or the VDF / H FP copolymers, which are the first compositional aspect of the invention. The electrochemical cells, of which the second composition of the subject matter of this invention is an improvement, are described in PCT application WO 95/06332, European patent application 95 120 660.6-1215, published under number 730,316 A1 September 4, 1996 and the patent of E. U.A. 5,296,318. The descriptions of the PCT application, the European application and the patent of E. U.A. they are incorporated here by reference. In addition to using solution casting techniques for the preparation of films for use in battery constructions as described in the aforementioned references, the use of extrusion techniques to prepare such films and the batteries made therefrom are also contemplated . It has also been observed that batteries made from the VDF-HFP copolymers of the present invention have better adhesion of the polymers to metal portions of electrodes and higher usage temperatures than batteries made from VDF-copolymers. H FP of the prior art. It has also been observed that the VDF-HFP copolymers of the present invention provide batteries having improved electrical properties including the ability to discharge speeds higher than batteries made from VDF-HFP copolymers of the prior art. It is expected by the inventors herein that in general batteries made in accordance with the present invention will possess such use of higher temperature and higher discharge velocity capabilities. The present invention provides a third aspect of composition, a solution of a composition of the first composition aspect of the invention having improved clarity and solution fluidity. Copolymers of vinylidene fluoride and hexafluoropropylene of up to about 24 wt.% Hexafluoropropylene are useful semicrystalline thermoplastics. As the content of H FP increases in the materials, the crystallinity is reduced, and, correspondingly, the flexibility and the sensitivity of the solvent increase. Other properties also change, such as the final melting point, which is reduced with the increase in HFP content. In high purity applications such as membrane filtration or extraction, lithium battery construction, high transparency film from solution casting, and fluid storage and transport requiring low levels of contaminants, it is desirable to have materials with low levels of extractables, little gel formation in the presence of the solvent, and good clarity. The VDF / HFP copolymers provided here show a low production of extractables, improved solution properties, improved clarity and fluidity, and lower melting points compared to VDF / H FP copolymers not otherwise uniform in content. similar to H FP and known in the prior art.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a comparison of the final differential scanning calorimetry / (DSC) melting point of the copolymers of the invention with DSC melting points of prior art compounds whose synthesis is described in detail. Figure 2 shows the effect on the level of HFP on polymer extractables in dimethyl carbonate (DMC) at 40 ° C for copolymers of the invention and copolymers of the prior art whose synthesis is described in detail.

Figure 3 shows the relationship between the content of HFP and the record of the gelling time from the solution (20% by weight in propylene carbonate) of the copolymers of the present invention and of copolymers of the prior art having a detail of synthesis sufficient for reproduction. Figure 4 is a cross-sectional view of an electrochemical cell according to the present invention.

DETAILED DESCRIPTION The invention provides copolymers of vinylidene fluoride and hexafluoropropylene having a hexafluoropropylene content of up to about 24% by weight and having improved clarity and solution fluidity and a reduced production of extractables. The copolymers are conveniently made through an emulsion polymerization process, but solution suspending processes can also be used. In an emulsion polymerization process, a reactor is charged with deionized water, water-soluble surfactants capable of emulsifying the reaction mass during polymerization, paraffin antiflocculant, vinylidene fluoride, hexafluoropropylene, chain transfer agent to control the molecular weight of the copolymer, and an initiator to start and maintain the polymerization. To obtain the VDF / HFP copolymers of the present invention, the initial charge of VDF and HFP monomers is such that the amount of HFP is up to 48% of the combined weight of the initially charged monomers, and then VDF is continuously fed. and HFP through the reaction, so that the amount of the HFP is up to 24% of the combined weight of the continuously fed monomers. The VDF / HFP ratios are different in the initial charge and during the continuous feed, and each final polymer composition has defined and related ratios for the initial charge and continuous feed. The process uses total amounts of VDF and HFP monomers, so that the amount of H FP used is up to about 24% of the total combined weight of the monomers. The reactor is in a pressurized polymerization reactor equipped with a stirrer and heat control means. The temperature of the polymerization may vary depending on the characteristics of the initiator used, but is typically between 65 ° and 105 ° C, and very conveniently between 75 and 95 ° C. The temperature is not limited to this scale, however, and may be higher or lower if a high temperature or low temperature initiator is used. The VDF / HFP ratios used in the polymerization will depend on the temperature selected for the reaction. The polymerization pressure is typically between 2750 and 6900 kPa, but may be higher if the equipment allows the operation at higher pressure. The pressure m uy conveniently is between 3790 and 5860 kPa.

The surfactants used in the polymerization are halogenated surface-active agents, soluble in water, especially fluorinated surfactants such as ammonium, substituted ammonium, quaternary ammonium or alkali metal salts of perfluorinated or partially fluorinated alkyl carboxylates, monoalkyl perfluorinated or partially fluorinated phosphate esters, perfluorinated or partially fluorinated alkyl ether or polyether carboxylates, perfluorinated or partially fluorinated alkyl sulfonates, and perfluorinated or partially fluorinated alkyl sulphates, Some specific examples, but not limiting, are the acid salts described in U.S. Patent No. 2,559,752 of formula X (CF2) nCOOM, wherein X is hydrogen or fluorine, M is an alkali metal, ammonium, substituted ammonium ion (e.g., alkylamine of 1 to 4 carbon atoms) , or quaternary ammonium, and n is an integer from 6 to 20; esters of sulfuric acid of polyfluoroalkanols of the formula X (CF2) nCH2OSO3M, wherein X and M are as defined above, and the salts of the acids of the formula CF3 (CF2) n (CX2) mSO3M, wherein X and M they are as defined above, n is an integer from 3 to 7 and m is an integer from 0 to 2, such as in potassium perfluoro-octyl sulfonate. The surfactant loading is from 0.05% to 2% by weight of the total weight of the monomer used, and most preferably the surfactant loading is from 0.1% to 0.2% by weight. The paraffin antiflocculant is conventional, any wax or saturated, long chain hydrocarbon oil can be used.

The paraffin reactor charges are from 0.01% to 0.03% by weight of the weight of the total monomer used. After the reactor has been charged with deionized water, surfactant, and paraffin antiflocculant, the reactor is either purged with nitrogen or evacuated to remove oxygen. The reactor is brought to a temperature, and optionally a chain transfer agent can be added. The reactor is then pressurized with a mixture of vinylidene fluoride and hexafluoropropylene. Chain transfer agents that can be used are well known in the polymerization of fluorinated monomers. Alcohols, carbonates, ketones, esters, and ethers are oxygenated compounds, which serve as chain transfer agents. Specific compounds, but not limiting, are isopropyl alcohol, as described in the patent of E. U.A. No. 4,360,652, acetone, as described in the patent of E. U.A. 3,857, 827, and ethyl acetate, as described in Published Unexamined Application (Kokai) JP 5806571 1. Other classes of compounds which serve as chain transfer agents in the polymerization of fluorinated monomers are halocarbons and hydrohalocarbons such as chlorocarbons, hydrochlorocarbons, chlorofluorocarbons and hydrochlorofluorocarbons; Specific examples, but not limiting, are trichlorofluoromethane, as described in the patent of E. U.A. number 4, 569,978, and 1,1-dichloro-2, 2,2-trifluoroethane. The chain transfer agents can be added all at once at the beginning of the reaction, in portions through the reaction, or continuously as the reaction progresses. The amount of chain transfer agent and the mode of addition, which is used, depends on the activity of the agent and the desired molecular weight characteristics of the product. The amount of chain transfer agent used is from 0.05% to 5% by weight of the weight of total monomer used, and is preferably from 0.1 to 2% by weight. The reactor is pressurized by adding monomers of vinylidene fluoride and hexafluoropropylene in a defined ratio (first effective ratio) so that the hexafluoropropylene varies up to 48% of the combined weight of the monomers initially charged. The first effective ratio used will depend on the relative reactivity of the two monomers at the selected polymerization temperature. The reactivity of vinylidene fluoride and hexafluoropropylene has been reported by Bonardelli et al. , Polymer, voi. 27, 905-909 (June 1986). The relative reactivity is such that a particular uniform copolymer composition is obtained, more hexafluoropropylene has to be charged to the reactor in the initial fill than will be incorporated in the copolymer. At the convenient polymerization temperature scale of this invention, approximately twice as much hexafluoropropylene has to be charged to the reactor in the initial packing as it appears in the polymer.

The reaction can be initiated and maintained through the addition of any suitable initiator known for the polymerization of fiuided monomers including inorganic peroxides, "redox" combinations of oxidizing and reducing agents, and organic peroxides. Examples of typical inorganic peroxides are the ammonium or alkali metal salts of persulfate, which have a useful activity on the temperature scale of 65 ° C to 105 ° C. "Redox" systems can operate at even lower temperatures, and examples include combinations of oxidants such as hydrogen peroxide, t-butyl hydroperoxide, eumenohydroperoxide, or persulfate, and reducing agents such as reduced metal salts, salts of iron (ll) which are a particular example, optionally combined with activators such as sodium formaldehyde sulfoxylate or ascorbic acid. Among the organic peroxides that can be used for polymerization are those of dialkyl peroxides, peroxyesters, and peroxydicarbonates. Examples of dialkyl peroxides are di-t-butyl peroxide, peroxy esters are t-butyl peroxypivalate and t-amyl peroxypivalate, and peroxydicarbonates are di (n-propyl) peroxydicarbonate, diisopropyl peroxydicarbonate, di (di) peroxydicarbonate. -butyl), and di (2-ethylhexyl) peroxydicarbonate. The use of diisopropyl peroxydicarbonate for the polymerization and copolymerization of vinylidene fluoride with other fluorinated monomers is taught in the patent of E.U.A. No. 3, 475,396, and its use for making copolymers of vinylidene fluoride / hexafluoropropylene is further illustrated in the U.S. number 4,360,652. The use of di (n-propyl) peroxydicarbonate in vinylidene fluoride polymerizations is described in Published Unexamined Application (Kokai) JP 58065711. The amount of an initiator required for polymerization is related to its activity and the temperature used for the polymerization. polymerization. The total amount of the initiator used is generally between 0.05% to 2.5% by weight based on the weight of the total monomer used. Typically enough initiator is added at the beginning to initiate the reaction and then additional initiator may be optionally added to maintain the polymerization at a convenient rate. The initiator can be added in pure form, in solution, in suspension, or emulsion, depending on the selected initiator. As a particular example, the peroxydicarbonates are conveniently added in the form of an aqueous emulsion.

As the reaction progresses, a mixture of monomers of vinylidene fluoride and hexafluoropropylene is fed in a defined ratio (second effective ratio) in order to maintain the reaction pressure. The second effective ratio used corresponds to the desired monomer unit ratio in the final composition of the copolymer, and this may vary up to 24% of the combined weight of the monomers that are continuously being fed through the reaction. The feed of vinylidene fluoride, hexafluoropropylene, and optionally the initiator and the chain transfer agent is continued until the desired filling of the reactor is obtained. After reaching the desired reactor fill, the monomer feeds are finalized. To get the copolymer to have an optimum clarity of solution and minimum extractables, all other feeds are stopped at the same time as the monomer is fed, and the reactor is ventilated as soon as practicable. Alternatively, to obtain a higher yield at the expense of clarity of solution and extractables, an out-of-reaction period is used to consume the residual monomer with optional continuation of the initiator feed. For the period out of reaction, the reaction temperature and stirring are maintained for a period of 20 to 30 minutes, but a longer period may be used if required, in order to consume the monomer to the point where the reactor pressure does not fall further to any significant degree. A period of sedimentation typically from 1 to 40 m inutes can be used after the period out of reaction. During the sedimentation period, the temperature is maintained but the initiator feed is not used. The reactor is then cooled and vented. The product is recovered as a latex. To obtain dry resin, the latex is coagulated, the clot is separated and the separated clot can be washed. To provide a powder, the clot dries. For the coagulation step, several well-known methods can be used including freezing, the addition of acids or salts, or mechanical shear with optional heating. The powder, if desired, can be further processed into pellets or other forms of suitable resins. The electrochemical cells of the present invention are based on a positive electrode, an absorber-separator sometimes referred to as a solid electrolyte and a negative electrode operatively associated with another, wherein at least one of the electrodes or the absorber-separator, and preferably both electrodes and the absorber-separator comprise a vinylidene fluoride polymer of the present invention and wherein the vinylidene fluoride polymer of the present invention comprises electrodes having an electrode material combined therewith and the fluoride polymer. of vinylidene of the present invention, the absorber-separator has an electrolyte material combined therewith. A plurality of electrodes and absorber-spacer elements can be used in the cell structure in order to increase the voltage, and / or amperage of the combined elements in a manner well known in the art. The vinylidene fluoride polymer of the present invention is not required to have an open or closed porous structure for operability. It provides improved electrolyte mobility in combination with the intrinsic ionic conductivity effects of the polymer without considering its initial porous or non-porous state. The vinylidene fluoride electrode or separator-absorber combined with electrode or electrolyte materials on the pore surface of the porous polymer was previously believed to make the use of the active material, either the electrode material or the electrolyte material, more efficient and provides a method to easily manufacture efficient electrodes and separator-absorber structures. Nevertheless, there are other advantages to using porous polymer structures even for the polyvinylidene fluoride polymers of the present invention. It is also believed that the segregation of the active materials on the surface of active pores will allow to vary the amount of binder in the separator-absorber electrode to improve the resistance with a minimum effect on the operation of the cell. The electrochemical cells formed in this way, therefore, will have improved mechanical properties and can be made independent, that is, the secondary reinforcing structures do not have to be employed, such as a metal or other conventional battery cover material. This also leads to ease of manufacture when the electrochemical cell is wrapped or encased in a vinylidene fluoride homopolymer, which will adhere to the porous electrodes and / or absorber-spacer structures. The adhesion can be obtained through a simple heat bonding or radio frequency welding (rf) or other similar procedures well known in the art. The adhesives are not required, but importantly, the outer part of the electrochemical cell (ie, the envelope) is of the same type or of a substantially similar type of material as the electrodes and the absorber-separator and is more compatible with the same and adherent to it, thus simplifying and reducing the cost of manufacturing since only one type of material is used for the structural components of the cell as compared to a construction either conventional dry cell or secondary ceda. Polyvinylidene fluoride, in general, absorbs the rf frequency and can also be heated through dielectric techniques. Heat guns can also be used to seal surfaces of polyvinylidene fluoride under pressure. Welding bars can also be used to heat seal two pieces easily, as is done in the manufacture of larger polyvinylidene fluoride structures. The joints obtained are usually as strong as the basic resins used. Since polyvinylidene fluoride polymers are resistant to abrasion and corrosion as well as chemical resistant, they are useful as an internal and external element of the battery and, as previously noted, can be easily assembled through non-adhesive means by bonding by heat. By selecting vinylidene fluoride polymers of the present invention for electrodes and said polymers or conventional VDF polymer for coating that are both extremely flexible or a little stiff, structures can be made that are either flexible or a little stiff. Further in this regard, improved stiffness can be obtained by interlacing the vinylidene fluoride homo- or copolymers in general either chemically but preferably using high energy radiation such as high energy electron beam radiation (from about 10 to about 20). Mrad), with some pending dehydrofluorination. A potential benefit is the additional stabilization of the amorphous regions in the vinylidene fluoride polymers, ie, crystallization inhibitions with time, which is important since it is believed that the electrolyte ionic conductivity occurs mainly in the amorphous or open As previously noted, the vinylidene fluoride polymers generally affect the ionic conductivity in a form that makes them suitable for the manufacture of electrochemical cells. Since the mobility of charged species is required in electrochemical cells, it is believed that migration of charged species into polyvinylidene fluoride polymers will be through the amorphous phase. The vinylidene fluoride polymers of the present invention have been recognized by the invention as having improved amorphous phases, which are more stable and particularly for the copolymers of H FP and CTFE provide this benefit to conductivity and the like at lower comonomer levels, thus providing solubility and temperature advantages that approach those of the homopolymers. In the triboelectric series, most polymers stabilize electrons. The vinylidene fluoride polymers, however, are unique for stabilizing positive holes and are one of the best means in this regard, probably due to the highly negative gem-difluorocarbon group. In the special case of lithium ion batteries, such as the oscillating seat batteries described herein, the high specific charge and the small ionic size of the lithium ion can lead to specific interactions in the fluoride polymer environment. of vinylidene host, considering the degree of gem-difluorocarbon groups non-polymerizable, negative available. Since the conductivity is inversely related to the crystallinity of the vinylidene fluoride polymer, it has been determined that conventional copolymers of vinylidene fluoride with from about 7 to about 25% hexafluoropropylene will sufficiently network the glass structure. of the polymer without sacrificing the mechanical properties so that the acceptable ionic effects of the polymer can be obtained. The inventors have discovered that the vinyl fluoride polymers of the present invention provide benefits equal to or better than the above conventional VDF / H FP copolymers at comonomer levels below 8% by weight, preferably by below 6% by weight. When polymers of vinylidene fl uoride of the present invention are employed in the manufacture of electrodes or absorber-spacers, plasticizers such as organic carbonates (eg, ethylene carbonate, propylene carbonate, dimethyl carbonate and the like) are used with In order to minimize the effect of the crystal structure and promote ionic conductivity. Other solvents or plasticizers may also be used, including diethoxyethane, diethyl carbonate, dimethoxyethane, dipropyl carbonate and mixtures thereof, especially mixtures of two or three components. Similarly, and in accordance with the present invention, the various porous and non-porous structures, depending on their tensile strength, can be mechanically oriented by stretching or applying tension forces in order to improve the amount of beta conformation. within the polymer structure and possibly thus promote the ionic conductivity depending on the electrolyte the composition of lead polyvinyl fluoride. Using combinations of solvent and non-solvent, the polyvinylidene fluoride polymers of the present invention are cast into thin membranes. This method is described by Benzinger et al. , in the patent of E. U.A. No. 4,384, 047, which is incorporated herein by reference. Electrode materials or electrolyte materials, as described herein, can be incorporated into the polyvinylidene fluoride solution before casting it to a film or sheet, after which the solution, if desired, can be converted. to a porous polyvinylidene fluoride membrane combined with the electrode of the electrolyte materials. These films or sheets, either with or without the electrode or electrolyte materials, can have a thickness from about 6.35 to about 2540, in particular from about 12.7 to about 254, and especially from about 25.4 to about 203.2 microns, and are especially suitable for further treatment by stretching or the application of tensile forces in order to promote the beta conformation necessary to obtain the ferroelectric properties in polyvinylidene fluoride. There are three kinds of organic liquids, which can be used to make solutions or dispersions of polymers of vinylidene fluoride. Active solvents are those organic liquids that dissolve or swell the polymers of vinylidene fluoride at room temperature and typically consist of lower alkyl ketones, esters and amides. Latent solvents are those organic liquids that do not dissolve the homo- or copolymers of vinylidene fluoride at room temperature; however, they will dissolve polyvinylidene fluoride at elevated temperatures and typically are alkyl ketones of medium chain length, esters, glycol ethers, and organic carbonates. Non-solvents are organic liquids that do not dissolve or swell the vinylidene fluoride polymers to the boiling point of the liquid or the crystalline melting point of the vinylidene fluoride polymer, whichever condition is satisfied first. These liquids are typically aromatic hydrocarbons, aliphatic hydrocarbons and chlorinated hydrocarbons or other chlorinated organic liquids. Solvents and latent solvents are used in the manufacture of the films or sheets of polyvinylidene fluoride of the present invention. Examples of these organic liquids are presented in Table A below.

TABLE A Liquids to Prepare Solutions or Dispersions of PVDF The suitability of any given liquid depends on the exact type and degree of the PVDF resin. Other methods have been developed for the manufacture, when desired, of porous polyvinylidene fluoride polymers of open cell foam, which are formulated to contain chemical or physical blowing agents such as absorbed carbon dioxide. It is preferred to use blowing agents in the manufacture of electrochemical cells, since the trace amounts of the chemical blowing agents in the foam structure can adversely affect the operation of the cell. When carbon dioxide or comparable physical blowing agents are employed, they are incorporated into the polyvinylidene fluoride at super critical pressures followed by heat treatment to expand the article thus produced. In this way, open-cell films of variable thickness with excellent mechanical integrity have been made and which have specific gravities of about one as compared to solid polyvinylidene fluoride, which has a specific gravity of about 1.76 to about 1.78. Similarly, polyvinyl idene fluoride powders can be concreted to form a porous structure by heating the powders in a non-solvent slurry, or under pressure between opposing plates, until the individual particles sufficiently flow under melting together to form the structure of the polyvinylidene fluoride. desired open cell. Other methods known in the art for making powder polymers such as PTFE to form open cell porous structures such as those described by Menassen et al. , "A Polymer Chemist's View on Fuel Cell Electrodes", Proceedinq of the 34th International Power Source Svmposium. June 25-28, 1990, pages 408-10, may also be employed. A porous polyvinylidene cast film provides polymers of the present invention from a mixture of solvents and non-solvents as described by Benzinger et al. , in the patent of E. U.A. No. 4,383,047, which has a thickness of about 254 microns after the formation of the casting solution, can be used for the manufacture of an electrochemical cell. The polymer comprises a copolymer of Example 1 presented hereinafter. This film is used in the manufacture of a solid electrolyte absorber-separator making a Li PF6 solution in a 1: 1 by weight mixture of ethylene carbonate: propylene carbonate, to which it is heated at approximately 125 ° C and the Porous copolymer film is immersed in the solution until it is combined with the film. Similarly, a positive electrode is made from the same porous copolymer. A dispersion of LiMn2O, smoke smoke SS and Li PF6 in a 1: 1 mixture of ethylene carbonate and propylene carbonate together with tetrahydrofuran (TH F) was combined with the porous film by soaking the film in the suspension, which was stirred in a beaker of vibration in order to keep the solid material in suspension until it was properly combined with the film. The film was then placed on an aluminum sheet. A negative electrode was prepared by making a dispersion ion or suspension of petroleum coke, carbon black SS and LiPF6 in a 1: 1 solution of ethylene carbonate / propylene carbonate in the same manner as was done for the preparation of the positive electrode and after combining the suspension with the porous film, a copper foil was placed on the film. The proportions of the various components of the electrode and the absorber-separator or solid electrolyte are substantially the same as those set forth in Examples 1 and 8 of Gozdz et al. , patent of E. U.A. No. 5,296,318. The electrodes and the electrolyte can also be made from polyvinylidene fluoride concreted by forming a dry mixture of electrode or electrolyte materials with powdered polyvinylidene fluoride. Dry mixing techniques can be used, known in the field, such as stirring type mixing. For example, the mixture of the polyvinylidene fluoride powder and the electrode and electrolyte materials can be adjusted by stirring or milling by ball mill for a sufficient time to ensure that a good mixture will be obtained. A container made of steel or other material, or ceramic container, is used, especially if it is lined with a layer of polyvinylidene fluoride or PTFE. In the case of grinding by ball mill, grinding balls made of steel or other material, or ceramic, are also coated with a layer of polyvinylidene fluoride or PTFE. The coating of polyvinylidene fluoride or PTFE is employed to substantially reduce to a minimum or substantially eliminate the introduction of impurities into the system. Ground mixtures are formed to electrode and electrolytes through the application of heat and pressure as noted above. One skilled in the art will recognize that the copolymer of Non-porous VDF / HFP of the first composition aspect of the invention or other vinylidene fluoride polymers of the invention, porous or non-porous, can be substituted for the VDF / HFP described in Example 1 to make analogous batteries. Solvents such as ethylene carbonate and propylene carbonate, and their equivalents, especially as noted herein, including mixtures thereof, which are employed in the electrode or electrolyte, can be added after soaking the electrode or electrolyte structures in said solvents. The soaking can be carried out at room temperature or more to maximize the solvation effect of these materials and to produce an optimum ionic conductivity in the electrodes or electrolyte. The positive electrodes and the negative electrode thus prepared are then placed on opposite sides of the absorber-separator prepared as described above with the copper and aluminum surfaces facing outward to form a cell as illustrated in Figure 4, where the copper film 14 is shown extended along a surface of the negative electrode 16, which is operatively associated with the absorber-separator 18 combined with the electrolyte. The aluminum film 22 is in contact with the positive electrode 20, which in turn is in contact with the other face of the absorber-separator 18, all the elements being operatively associated with one another. A casing 12 of the polyvinylidene fluoride homopolymer extends completely around the cell. The casing 12 can be a single film or a plurality of films, for example, two or three films and extends around all sides and completely envelops cell 10. Copper and aluminum cables (not shown) are passed through through the casing 12 to make electrical contact with the films 14 and 22, respectively, and are connected to a load (not shown) to form an electrical circuit. The other electrolytes described herein for the oscillating seat cells can also be used in place of the Li P F6 salt and the substituted Li N iO2 or LiCoO2 materials for the LiMn2O materials in the previous example. In addition, gyrite can be used instead of petroleum coke in the manufacture of the negative electrode, although petroleum coke is especially preferred. The vinylidene fluoride polymers of the present invention can also be used in cells having an organic lithium electrolyte, wherein the polymer is used either as a binder for particular electrode active materials, such as a solid electrolyte for cells polymeric, as a porous mesh supporting an electrolyte in the almost solid gel state or as a cell base material. The vinylidene fluoride polymers of the present invention, as described herein, can also be used in lithium / oxyhalide cells as a background insulator. They can also be used in zinc bromide cells as a binder for bipolar electrodes or in nickel metal hydride cells as a binder for the hydride electrode or for the nickel electrode. The vinylidene fluoride polymers of the present invention are also suitable for use in a silver-zinc cell, where vinylidene fluoride polymers are used as a binder for the zinc electrode or in a lead-acid cell as a separator between the electrodes and as a separator. The vinylidene fluoride polymers can also be used in thermal batteries for cathode active materials. In addition to the nickel metal hydride cells, the vinylidene fluoride polymers can also be used in other alkaline cells such as nickel-cadmium cells and zinc-air cells, especially when a Electrolyte regulates its pH in order to counteract the dehydrohalogenation effect of the alkaline medium of these cells. The following examples further illustrate the best mode contemplated by the inventors to carry out the invention and are constructed as illustrative and not as a limitation for the same. Melt viscosity measurements are through ASTM D3835 at 232 ° C and 100 s-1. The thermal properties are measured with a differential scanning calorimeter (DSC) according to ASTM D3418. The content of HFP was determined through 19 F NMR according to the signal assignments and method described by Pianca et al., Polymer, vol. 28, 224-230 (Feb. 1987). A spectrometer of Unity 400 at 376.3 MHz was used. The spectra were obtained either in deuterated dimethylformamide at 50 ° C with an excitation pulse width of 8.0 microseconds and a recirculation delay of 10 seconds, in deuterated dimethyl sulfoxide at 80 ° C with an excitation pulse width of 6.0 microseconds and a recirculation delay of 5 seconds, or in deuterated acetone at 50 ° C with an excitation pulse width of 8.0 microseconds and a recirculation delay of 20 seconds. Molecular weights were measured through size exclusion chromatography (SEC). A Waters 150 C chromatographic device was used with a group of mixed PL gel 2 columns B with a bead size of 10 microns at an operating temperature 105 ° C. HPLC grade dimethyl sulfoxide (DMSO) was used as the eluent at a flow rate of 1.0 mL / minute. The samples were prepared through dissolution in DMSO for 5 hours at 100 ° C, followed by filtration.

EXAMPLE 1 In a 7.5 liter stainless steel reactor, 4,799 kg of deionized water, 0.230 kg of a solution of 1% by weight of a mixture of perfluoroalkanoate salts, and 0.004 kg of paraffin wax were charged. The mixture was purged with nitrogen and stirred for 30 minutes. The reactor was sealed and heated to 80 ° C. The reactor was charged with 0.355 kg of vinylidene fluoride, 0.049 of hexafluoropropylene (a ratio of 88 vinylidene fluoride / 12 hexafluoropropylene), and 0.120 kg of a 5% by weight solution of ethyl acetate in deionized water. The reaction conditions were stabilized at 80 ° C and 4480 kPa, and after the polymerization was initiated by introducing 0.026 kg of an initiator emulsion consisting of 2% by weight of di-n-propyl peroxydicarbonate and 0.15% by weight of mixed perfluoroalkanoate salts dispersed in deionized water. The pressure was increased to 4550 kPa with the addition of the initiator emulsion. The polymerization was maintained through the addition of the initiator emulsion at the rate of 0.1 12 kg per hour, and through the addition of a mixture of vinylidene fluoride / hexafluoropropylene in order to maintain the pressure. After 4.2 hours, total of 1890 kg of vinylidene fluoride and 0.140 kg of hexafluoropropylene were charged to the reactor. All feeds were stopped, and the reactor cooled. After 5 minutes of cooling, the speed of the stirring was reduced to 78% and the remaining gases were vented. The stirring was stopped, the reactor was further cooled, and then the latex was emptied. Polymer resin was isolated through latex coagulation by washing the resulting solids with boiling water, and drying the solids at 1 10 ° C to produce a fine powder. The resin thus made had a melt viscosity of 2770 Pa.s, had a DSC melting point of 152 ° C, and had a hexafluoropropylene content as measured through NMR of 5.4% by weight.

EXAMPLE 2 To a 7.5 liter stainless steel reactor, 4,913 kg of deionized water, 0.230 kg of a 1% by weight solution of a mixture of perfluoroalkanoate salts, and 0.004 kg of paraffin wax were charged. The mixture was purged with nitrogen and stirred for 30 minutes. The reactor was sealed and heated to 80 ° C. The reactor was charged with 0.415 kg of vinylidene fluoride, 0.215 kg of hexafluoropropylene (a ratio of 66 vinylidene fluoride / 34 hexafluoropropylene), and 0.010 kg of ethyl acetate. The pressure was 4895 kPa. The reaction conditions were stabilized at 80 ° C, and after the polymerization was initiated polymerization was initiated by introducing 0.040 kg of an initiator emulsion consisting of 2% by weight of di-n-propyl peroxydicarbonate and 0.15% by weight of salts of perfluoroalkanoate mixed dispersed in deionized water. The pressure dropped after initiation and was maintained at 4825 kPa. Polymerization was maintained through the addition of the initiator emulsion at the rate of 0.1 76 kg per hour, and the addition of a mixture of vinylidene fluoride / hexafluoropropylene in the ratio of 84 vinylidene fluoride / 16 hexafluoropropylene to the to maintain the pressure. After 2.2 hours, the totals of 1585 kg of vinylidene fluoride and 0.445 kg of hexafluoropropylene were charged to the reactor. The monomer feeds were stopped, and the residual monomer was consumed while maintaining the initiator emulsion feed and 80 ° C for 20 minutes. The initiator feed and stirring were stopped and the reactor allowed to settle for 10 minutes. The reactor was cooled to 45 ° C, vented and then emptied of the latex. The polymer resin was isolated through latex coagulation, washing the resulting solids with boiling water, and drying the solids at 80 ° C to produce a fine powder. The resin thus made had a melt viscosity of 1220 Pa. s, had a DSC melt point of 1 1 4 ° C, and had a hexafluoropropylene content as measured by N M R of 1 7.2% by weight.

EXAMPLE 3 (Example Comparative to Example 1) In a stainless steel reactor, of 7.5 liters, it will be charged 4. 799 kg of deionized water, 0.230 kg of a 1% solution in weight, a mixture of perfluoroalkanoate salts, and 0.004 kg of paraffin wax. The mixture was purged with nitrogen and stirred for 30 minutes. The reactor was sealed and heated to 80 ° C. The reactor was charged with 0.400 kg of vinylidene fluoride, 0.030 kg of hexafluoropropylene (a ratio of 93 vinylenide fluoride / 7 hexafluoropropylene), and 0.120 kg of a 5% by weight solution of ethyl acetate in deionized water. The reaction conditions were stabilized at 80 ° C and 4480 kPa, and then the polymerization was initiated by introducing 0.026 kg of an initiator emulsion consisting of 2% by weight of di-n-propyl peroxydicarbonate and 0.15% by weight of salts of mixed perfluoroalkanoate dispersed in deionized water. The polymerization was maintained through the addition of the initiator emulsion at the rate of 0.1 12 kg per hour, and through the addition of a mixture of vinylidene fluoride / hexafluoropropylene in the ratio of vinylidene fluoride / 7 hexafluoropropylene with In order to maintain the pressure. After 3.1 hours, total of 1890 kg of vinylidene fluoride and 0.140 kg of hexafluoropropylene were charged to the reactor. The monomer feedings were stopped, and the residual monomer was consumed while maintaining the initiator emulsion feed and at 80 ° C for 20 minutes. The initiator feed and stirring were stopped, the reactor allowed to settle for 10 minutes. The reactor was cooled to 45 ° C, vented and then emptied of the latex. The polymer resin was isolated by coagulating the latex, washing the resulting solids with boiling water, and drying the solids at 1 10 ° C to produce a fine powder. The resin thus made had a melt viscosity of 2550 Pa.s, had a DSC melting point of 154 ° C and had a hexafluoropropylene content as measured by NMR of 6.0% by weight.

EXAMPLE 4 In a 293 liter stainless steel reactor, 200.0 kg of deionized water, 1.00 kg 10% by weight of a solution of a mixture of perfluoroalkanoate salts, and 0.015 kg of paraffin oil were charged. The reactor was evacuated and heated to a temperature of 91 ° C during loading, and agitation was used. To the reactor were added 12.6 kg of vinylidene fluoride, 0.8 kg of hexafluoropropylene (a ratio of 94 vinylidene fluoride / 6 hexafluoropropylene), and 0.5 kg of ethyl acetate, which brought the reactor pressure to 4480 kPa. During pressurization, when the pressure reached 3445 kPa, an initiator emulsion feed consisting of 2% by weight of di-n-propyl peroxydicarbonate and 0.15% by weight of mixed perfluoroalkanoate salts dispersed in deionized water, was initiated and maintained at 9.0 kg / h until 4.6 kg of the initiator emulsion was added. The additional initiator emulsion addition rate was adjusted in order to maintain a total monomer feed rate of 27.0 kg / h. A monomer mixture in the ratio of vinylidene fluoride / 6 hexafluoropropylene was fed to the reactor in order to maintain the pressure at 4480 kPa until the totals of 85.3 kg of vinylidene fluoride and 5.4 kg of hexafluoropropylene were charged to the reactor. All feeds were stopped, and the residual monomer was consumed keeping at 91 ° C and stirring for 30 minutes and then keeping at 91 ° C for 35 minutes. The reactor was cooled, vented and drained of latex. The polymer resin was isolated by coagulating the latex, washing the resulting solids with water, and drying the solids to produce a fine powder. The resin thus made had a melt viscosity of 1740 Pa.s, had a DSC melting point of 155 ° C, and had a hexafluoropropylene content as measured through NMR of 4.7% by weight.

EXAMPLES 5 TO 12 The copolymers of Examples 5 to 8 were made similarly to the copolymers of Examples 1 or 2, and the copolymers of Examples 9 to 12 were made in a similar manner to the copolymers of Examples 3 or 4, and are shown in Table I .

NJ I heard O 01 O C? (: UADR < 3 1 AXLES EXPERIMENT AJLES Example 1 2 5 6 7 8 3 4 9 10 11 12 (Detailed example, which is 1 1 1 2 3 3 4 3 very similar) Temperature, ° C 80 80 80 80 80 80 80 91 80 80 91 80 Pressure, kPa 4550 4825 4550 4480 4480 4480 4480 4480 4480 4515 4480 4480 Initial filling [a] Water, kg 4,799 4,913 4,837 4,768 4,797 4,723 4,799 200.0 4,837 4,768 200.0 4,723 VDF, kg 0.355 0.415 0.365 0.365 0.460 0.400 0.400 12.6 0.390 0.365 11.0 0.455 HFP, kg 0.049 0.215 0.030 0.129 0.163 0.207 0.030 0.8 0.017 0.060 1.9 0.128 EtoAc solution, kg 0.120 - 0.080 0.160 0.130 0.200 0.120 - 0.080 0.160 - 0.200 EtoAc, kg - 0.010 - - - - - 0.5 - - 0.7 - 4k Ol NPP emulsion, kg. 0.026 0.040 0.026 0.033 0.036 0.040 0.026 4.6 0.026 0.033 3.7 0.040 VDF totals. kg. 1,890 1,585 1,915 1,745 1,700 1,590 1,890 85.3 1,945 1,745 77.1 1,585 HFP, kg. 0.140 0.445 0.083 0.285 0.331 0.441 0.140 5.4 0.085 0.285 13.6 0.445 NPP emulsion, kg. 0.506 0.460 0.413 0.422 0.352 0.463 0.405 8.5 0.540 0.491 8.3 0.563 Viscosity under melting, Pa.s 2770 1220 3120 1660 1760 480 2550 1740 2240 1010 660 850 Melting point, ° C 152 114 156 132 125 116 154 155 159 141 139 126 Polymer of HFP,% / p 5.4 17.2 3.4 12.5 14.8 17.0 5.8 4.6 4.9 11.8 11.7 18.1 [a] perfluoroalkanoate salt solution. salts of perfluoroalkanoate, paraffin wax and paraffin oil in Examples 5 to 2 were the same as in the similar detailed examples.

The term "solutions having improved clarity and fluidity" as used in the specifications and claims of this application, represents that the solutions of any particular polymer of this invention having a particular nominal HFP content will provide solutions having analogous descriptive properties to those shown by Example 2 in Table II when dissolved in any of the listed solvents at the same concentration levels at which a polymer having approximately the same particular nominal HFP content made through a typical procedure described in detail in the prior art, provide descriptive solution properties analogous to those shown in Table II for Example 12.

EVALUATION OF THE SOLUTION PROPERTIES OF THE EXAMPLES The solution properties of Examples 2 and 12 are shown in Table I I. Mixtures of the indicated weight percentage were prepared, using heat when necessary to dissolve the polymer completely and form a clear solution. Then, the solutions were allowed to cool and were observed daily for a period of two weeks. Copolymer 2 showed a reduced tendency to gel formation and was clearer than copolymer 12. Retention of flowability and clarity by copolymer 2 is advantageous in applications which are based on polymer solutions, such as in the production of films and casting membranes. The reduction in the tendency towards gelation through the copolymers of the present invention is further shown in Table II A. The gelation times of the propylene carbonate solutions of some of the examples are shown in the Table. A Rheometrics® dynamic tension rheometer from DSR-200 was used to measure the gelation times of 20% by weight solutions of the polymers in the propylene carbonate (the propylene carbonate was of a nominal purity of 99.7%). The rheometer was equipped with a Peltier fitting and a solvent trap. A 40 mm parallel plate geometry with a 1 mm gap was used. The solid copolymer was mixed with propylene carbonate at room temperature on the day of measurement, the container was sealed and the solution formed by heating and stirring the mixture in the sealed container for 1.0 hours in a heating module equipment. Pierce Reacti-Therm® agitation set at 120CC. The solutions were loaded quickly at the end of the dissolution period in the test accessory, which was preset at 100 ° C. A temperature-cooling ramp in a dynamic oscillatory mode at 1 Hz started as fast as the accessory temperature was re-balanced at 100 ° C; re-balancing typically required 1 minute or less. The cooling ramp was 100 ° C at 15 ° C at a speed of 30 ° C / m. When it reached 15 ° C, an equilibrium time of 1 minute was used, and then a time-sweep measurement was started. The sample was maintained at 1 5 ° C during the time sweep measurement performed at 1 radian / s. The time sweep was continued until the gel point was reached. The gelation point was taken as the point at which the solution storage module, G ', and the loss modulus, G ", were equal.The gelation time was taken as the duration in the time sweep to reach the gelation point The ratio between the HFP content and the gel time logarithm of 20% by weight of propylene carbonate solutions is shown in Figure 3. It can be seen that the copolymers of the present invention have gelling times longer than the copolymers prepared according to the prior art with respect to the total scale of the H-FP content The reduced tendency towards gelation through the copolymers of the present invention is advantageous for processing such solutions for the casting of films and other solution applications.

TABLE II SOLUTION PROPERTIES Polymer and solvent Appearance Concentration Example 2 Example 12 10% in MEK Fluid, clear Fluid, clear 20% in MEK Fluid, clear At day 2, gel loss, clear 30% at MEK On day 14, some gel, Af day 1 gel loss, of course; to clear day 4, gel, hazy 10% in MPK Fluid, clear Fluid, clear 20 in MPK Fluid, clear At 2 o'clock, some gel, clear; to day 1, gel, slightly hazy % in MiBK Fluid, clear At day 4, gel, clear 10% in CPO Fluid, clear Fluid, clear 10% in CHO Fluid, clear Fluid, clear 20% in CHO On day 2, some gel, clear On day 1 , some gel, clear On day 2, some gel, hazy % in EtoAc Fluid, clear At day 7, some gel, clear 20% in EtoAc Fluid, clear At day 1, Fluid, hazy; On day 3, some gel, hazy % in n-PrOAc Fluid, clear Fluid, clear 10% in i-PrOAc Fluid, clear AI day 6, Some gel, clear % in EGMEA Fluid, clear At day 6, gel, clear 10% in DMC Fluid, clear At day 7, some gel, clear % in DMC Fluid, clear At day 1, some gel, very cloudy; On day 2, gel, hazy % in Mix 2 Fluid, clear At day 14, fluid, hazy NOTES FOR BOX II [a] Polymer concentrations are in percent / weight unless otherwise stated. MEK is methyl ethyl ketone, MPK is methyl propyl ketone, MiBK is methyl isobutyl ketone, CPO is cyclopentanone, CHO is cyclohexanone, EtOAc is ethyl acetate, N-PrOAc is n-propyl acetate, i-PrOAc is isopropyl acetate, EGMEA is ethylene glycol monomethyl ether acetate, DMC is dimethyl carbonate, Mixture 2 is composed of 35.4 parts of MiBK, 29.8 parts of CHO, and 30 parts of DMC by weight.

TABLE II A SOLUTION GELIFICATION TIME Tal Example number Gelation time _ __ 1 512 3 342 3 394 6 4, 913 6 8, 322 6 12, 924 10 934 10 1, 553 10 3, 191 2 77, 000 2 62, 400 12 14, 100 12 47, 500 [a] solutions of 20 % by weight at 15 ° C in propylene carbonate. The gelling time is in seconds.

EVALUATION OF BRIGHTNESS AND CLARITY OF THE FILM Some of the ungelled solutions from the solution property tests were used to make films, which were tested for brightness and clarity. The films were cast on a Leneta Form 2A opacity graph using a 0.127 meter ejection applicator having a 250 micrometer gap. The cast films were dried for three days at room temperature. The brightness of the film was determined using a HunterLab Progloss PG-2 brightness meter, and the results are shown in Table III. Turbidity was measured by determining the whiteness index (L * CIELAB value) of the film on the black portion of the opacity plot using a HunterLab Labscan 2 color meter, and the results are shown in Table IV. The copolymer 2 films showed a higher brightness from a broader scale of solvents than the films of the copolymer 12. The turbidity in the films 2 and 12 was generally similar, but remarkably less turbidity was observed in the films of 2 in several cases. The results, taken together, show that the VDF / HFP copolymer of the present invention demonstrates increased utility for high gloss, high transparency film applications.

TABLE III BRIGHTNESS OF COLADAS FILMS Polymer Concentration and Brightness, 20 degrees / 60 degrees solvent [a] Example 2 Example 12 20% in MEK 33.6 / 69.0 31.3 /68.7 10% in MPK 31.4 / 68.9 1.3 / 18.7 10% in CPO 0.7 / 16.9 2.0 / 27.7 10 % in EtOAc 29.4 / 66.6 29.4 / 68.0 10% in n-PrOAc 31.9 / 70.1 16.0 / 57.0 10% in i-PrOAc 31.6 / 69.4 15.4 / 56.2 10% in DMC 35.4 / 70.6 30.1 /68.6 20% in Mixture 2 34.6 / 71.2 0.1 /2.4 [a] Concentration of polymer and solvent indicates the percentage by weight and solvent of the films that were cast. MEK is methyl ethyl ketone, MPK is methyl propyl ketone, CPO is cyclopentanone, EtOAc is ethyl acetate, N-PrOAc is n-propyl acetate, i-PrOAc is isopropyl acetate, DMC is dimethyl carbonate, Mixture 2 is composed of 35.4 parts of methyl isobutyl ketone, 29.8 parts of cyclohexanone, and 30 parts of DMC by weight.

TABLE IV CLARITY OF COLD FILMS Polymer concentration and Clarity, CIELAB L * [b] solvent [a] Example 2 Example 12 20% in MEK 6.59 6.22 10% in MPK 6.19 14.48 10% in CPO 15.18 15.56 10% in EtOAc 7.38 5.84 10% in n-PrOAc 5.64 7.34 10% in i-PrOAc 5.61 7.79 10% in DMC 6.21 5.73 20% in Mix 2 5.36 17.85 [a] Concentration of polymer and solvent indicates the percentage by weight and solvent of the films that were cast. MEK is methyl ethyl ketone, MPK is methyl propyl ketone, CPO is cyclopentanone, EtOAc is ethyl acetate, N-PrOAc is n-propyl acetate, i-PrOAc is isopropyl acetate, DMC is dimethyl carbonate, Mixture 2 is composed of 35.4 parts of methyl isobutyl ketone, 29.8 parts of cyclohexanone, and 30 parts of DMC by weight. [b] Turbidity guide: L * < 7 without turbidity 7 < L * < 9 very light turbidity 9 < L * < 1 1 light turbidity 1 1 < L * < 15 moderate turbidity 15 < L * severe turbidity.

EVALUATION OF THE THERMAL PROPERTIES OF THE EXAMPLES The final melting point is an important parameter in the use and processing of semicrystalline polymers. It is known that the final melting point of the VDF / HFP copolymers is related to the HFP content in the copolymers. The ratio between the HFP content and the final melting point of the VDF / HFP copolymer examples is shown in Figure 1. The copolymers of the present invention and the copolymers prepared according to the synthesis of the prior art, the details of which are available, it can be seen that it falls in different melting point curves, indicating that they are different materials, the prior art copolymers having a higher melting point at a given HFP content. The lower melting property of the polymers of the present invention may allow lower processing temperatures than for the prior art synthesis copolymers.

EVALUATION OF REMOVABLE PRODUCTS IN DIMETILO CARBONATE General Procedure 1 g of the polymer and 9 g of dimethyl carbonate were placed in a closed 25 ml container. The contents of the container were continuously stirred through appropriate means, while maintaining the desired temperature through appropriate means for 24 hours. All the contents of the container were then transferred to a centrifuge tube and centrifuged to separate the undissolved polymer. The liquid phase was transferred to a suitable container and the solvent evaporated. The residue in the container was weighed and reported as percentage by weight of extractables. The amount of polymer extracted in the dimethyl carbonate at 40 ° C was measured. The data is shown in Table V. Copolymers prepared according to the synthetic methods of the prior art for which details are available, were marked as "N". The copolymers prepared according to the methods described in the present invention were marked with "U".

TABLE V EFFECT OF HFP CONTENT. MOLECULAR NUMBER AND UNIFORMITY OF THE COMPOSITIONAL DISTRIBUTION OF THE POLYMER DISSOLUTION IN DMC A surface examination showed that all N samples had higher levels of polymer extracted in dimethyl carbonate. Figure 2 shows a graph of the extractables as a function of the HFP content (molar%). Two different curves are presented for the two kinds of materials. The upper curve (N samples) show significantly higher levels of extractables for a given level of HFP compared to the U curve. The inclinations measured for these curves are 3% of extractables / mol% of HFP for polymers N and 1.7% of extractables / mol% of HFP for polymers U. The percentage of extractables observed and calculated under the functional model individual as double is shown for polymers N in Table VI and for polymers U in Table VIL TABLE VI COMPARISON OF% IN WEIGHT OF REMOVABLE PRODUCTS POLYMER N AS A FUNCTION OF THE HFP OR EL CONTENT HFP AND Mn CONTENT (Model 1)% by weight of extrab product and 2.9 (HFP% molar) 0. 4. (Model 2)% by weight of extractable product 46.4 + 1.7 (HFP% molar) - 0.00028 (Mn).

TABLE VII COMPARISON OF% BY WEIGHT OF REMOVABLE PRODUCTS OF THE POLYMER U AS A FUNCTION OF THE HFP CONTENT OF THE HFP CONTENT OF Mn (Model 1)% by weight of extractable product = 1 .7 (H FP% molar) - 3.2 (Model 2)% by weight of extractable product = -1 .2 + 1 .5 (HFP% molar) - 8 x 10 6 (Mn).

In the specification and the appended claims the expression "which has a percentage by weight of extractable products within 1.5% of the percentage by weight of extractable product calculated by an equation selected from the group consisting of: a)% / weight of extractables = 1 .7 (H FP% molar) - 3.2, and b)% / weight of extractable products = - 1 .2 + 1 .5 (H FP% molar) - 8 x 10"6 (Mn), means that the percentage by weight of extractable products in carbonate of dimethyl at 40 ° C must be within 1.5 of absolute percentage of the extractable product value calculated for the particular polymer by any equation. That is, if the calculated value of percentage of extractables by any of equations 1 and 2 is 3.0 and the observed value of between 1.5 and 4.5%, they fall within the intended coverage value. Similarly, if the observed value is 8.0% this will be within the intended coverage if the calculated value of any of the equations varies from 6.5% to 9.5%.

EXAMPLE 13 Polyvinylidene Fluoride / Chlorotrifluoroethylene copolymer having a Substantially Homogeneous Monomer Distribution Following a procedure analogous to that of Example 1, an initial charge containing 0.40 kg of vinylidene fluoride and 0.124 kg of chlorotrifluoroethylene (97 VDF / 3 CTFE) is provided and the reaction mixture is maintained through a continuous feed of 96 VDF to 4 CTFE together with an initiator emulsion for a suitable total feed for the reactor size of approximately 1.9525 kg of VDF and 0.0775 kg of CTFE to obtain the title copolymer having a content of about 4.0% CTFE. In the procedure described above to determine the extractables in dimethyl carbonate, centrifugation was used for 30 minutes at 1500 rpm. at room temperature to separate the solution from insoluble matter and drying at 50 ° C for 70 hours under a mechanical pump vacuum was used to determine the weight of the solids in the separated solution. The subject matter that the applicant considers as the invention is particularly pointed out and claimed in the following claims.

Claims (10)

1. - An improved electrochemical cell having a positive electrode, an absorber-separator and a negative electrode, wherein at least any of one of the electrodes comprises a polymer of vinylidene fluoride having an electrolyte material combined therewith and / or an absorber-separator comprises a vinylidene fluoride polymer having an electrolyte material combined therewith, wherein the improvement comprises the vinylidene fluoride polymer consisting essentially of a vinylidene fluoride polymer selected from the group consisting of vinylidene fluoride homopolymer having a bimodal molecular weight distribution, vinylidene fluoride / chlorotri-fluoroethylene copolymer having a substantially homogeneous monomer distribution and a copolymer of vinylidene fluoride and hexafluoropropylene containing a maximum of about 24% by weight of hexafluoropropylene, having solutions of clarity and improved fluency; for the copolymers having a nominal H-FP content of up to about 8% by weight, having a percentage by weight of extractable products within plus or minus 1.5% of the percentage by weight of the extractables calculated by a selected equation from the group consisting of: a)% / weight of extractables = 1.7 (HFP% molar) - 3.2, and b)% / weight of extractables = a -1.2 + 1.5 (HFP% molar) - 8 x 10"6 ( Mn), and for copolymers having more than about 8% by weight of nominal HFP content, having a DSC melting point of at least 2.5 ° C lower than copolymers having the same nominal weight percentage of HFP prepared by the methods for which the prior art provides details

2. A battery according to claim 1, wherein the vinylidene fluoride polymer is a vinylidene fluoride homopolymer having a molecular weight distribution bimodal

3. A battery according to claim 1, wherein the vinylidene fluoride polymer is a vinylidene fluoride / chlorotrifluoroethylene copoiimer having up to about 20% by weight of chlorotrifluoroethylene and having a substantially homogeneous monomer distribution.

4. A battery according to claim 3, wherein the VDF / CTFE copolymer has up to 8% by weight of CTFE content.

5. A battery according to claim 4, wherein the VDF / CTFE copolymer has from about 2% to about 6% CTFE content.

6. A battery according to claim 1, wherein the polyvinylidene fluoride polymer is a copolymer of VDF / H FP.

7. A battery according to claim 6, wherein the VDF / HFP copolymer has up to about 8% by weight of HFP content.

8. A battery according to claim 7, wherein the VDF / HFP copolymer has from about 2% to about 6% by weight of the HFP content.

9. An improved electrochemical cell having a positive electrode, an absorber-separator and a negative electrode, wherein at least any of one of the electrodes comprises a polymer of vinylidene fluoride having an electrolyte material combined therewith and or said absorber-separator comprises a vinylidene fluoride polymer having an electrolyte combined therewith, wherein the improvement comprises the vinylidene fluoride polymer consisting essentially of a VDF / H FP copolymer having up to about 8% by weight of hexafluoropropylene and having a percentage by weight of extractables with more or less 1.5% of the percentage by weight of extractables calculated either through equation a) or b) defined in claim 1.

10. A battery according to claim 9, wherein the hexafluoropropylene content of the VDF / HFP copolymer is from about 2% to about 6% by weight.