Fluorinated surfactant-free aqueous dispersion of a vinylidene fluoride copolymer comprising hydroxyl groups

Patent metadata

Field	Value
Publication number	US-2019284428-A1
Application number	US-201716318128-A
Country	US
Kind code	A1
Filing date	Jul 12, 2017
Priority date	Jul 15, 2016
Publication date	Sep 19, 2019
Grant date	—

Abstract

The present invention pertains to a fluorosurfactant free aqueous dispersion of an acrylic-modified vinylidene fluoride polymer, possessing a melt viscosity of at least 30 kPoise, and possessing an amount of end groups of formula —CH2—OH of at least 5 mmol/kg, to a method for its preparation and to its use for the manufacture of electrochemical cell components, such as electrodes and/or composite separators.

First claim

1 . An aqueous dispersion (D) comprising particles of polymer (A), wherein polymer (A) is a vinylidene fluoride (VDF) copolymer comprising recurring units derived from vinylidene fluoride (VDF) monomer and recurring units derived from at least one hydrophilic (meth)acrylic monomer (MA) of formula:

wherein each of R1, R2, R3, equal or different from each other, is independently a hydrogen atom or a C 1 -C 3 hydrocarbon group, and R OH is a hydroxyl group or a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group, said polymer (A):
(i) comprising more than 85.0% moles of recurring units derived from VDF and from 0.05 to 10% by moles of recurring units derived from said hydrophilic (meth)acrylic monomer (MA), with respect to the total number of recurring units of polymer (A);
(ii) possessing a melt viscosity of at least 30 kPoise, when determined at a shear rate of 100 sec −1 , and at a temperature of 230° C., according to ASTM D3835, and
(iii) possessing an amount of end groups of formula —CH 2 —OH of at least 5 mmol/kg and at most 20 mmol/kg;

wherein said dispersion is substantially free from fluorinated surfactants.

2 . The dispersion (D) of claim 1 , wherein polymer (A) consists essentially of recurring units derived from VDF, and from monomer (MA).

3 . The dispersion (D) of claim 1 , wherein polymer (A) consists essentially of recurring units derived from VDF, from HFP and from monomer (MA).

4 . The dispersion (D) of claim 1 , wherein the hydrophilic (meth)acrylic monomer (MA) complies with formula:

wherein each of R1, R2, equal or different from each other, is independently an hydrogen atom or a C 1 -C 3 hydrocarbon group, and R3 is hydrogen and R OH is a hydroxyl group or a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group.

5 . The dispersion (D) of claim 4 , wherein the monomer (MA) is selected from the group consisting of:
hydroxyethylacrylate (HEA) of formula:

2-hydroxypropyl acrylate (HPA) of either of formulae:

acrylic acid (AA) of formula:

and mixtures thereof.

6 . The dispersion (D) of claim 1 , wherein polymer (A) comprises at least 0.1% moles of recurring units derived from said hydrophilic (meth)acrylic monomer (MA) and/or polymer (A) comprises at most 7.5% moles of recurring units derived from said hydrophilic (meth)acrylic monomer (MA).

7 . The dispersion (D) according to claim 1 , wherein polymer (A) possesses a melt viscosity (MV) of no more than 100 kPoise when determined at a shear rate of 100 sec −1 , and at a temperature of 230° C., according to ASTM D3835.

8 . The dispersion (D) according to claim 1 , wherein polymer (A) comprises an amount of polar end groups of formula —CH 2 OH of at least 5 mmol/kg and at most 18 mmol/kg.

9 . A method of making the dispersion (D) of claim 1 , said method comprising emulsion polymerizing VDF and said hydrophilic (meth)acrylic monomer (MA) in the presence of a persulfate inorganic initiator, at a temperature of at most 80° C., under a pressure of at least 20 bar, without adding any fluorinated surfactant.

10 . An aqueous electrode-forming composition comprising the dispersion (D) according to claim 1 , a powdery electrode material, and, optionally an electroconductivity-imparting additive and/or a viscosity modifying agent.

11 . An aqueous coating composition (AC) comprising dispersion (D) according to claim 1 , at least one non-electroactive inorganic filler material and, optionally, one or more than one additional additive.

12 . The composition (AC) of claim 11 , wherein the non-electroactive inorganic filler material is selected from the group consisting of natural and synthetic silicas, zeolites, aluminas, titanias, metal carbonates, zorconias, silicon phosphates and silicates.

13 . The composition (AC) of claim 11 , wherein the composition includes at least one additional additive selected from the group consisting of viscosity modifiers, anti-foams, and non-fluorinated surfactants, and anionic surfactants.

14 . The composition (AC) according to claim 11 , said composition (AC) being obtained by:
mixing:
(i) dispersion (D), in an amount of from 5 to 25% wt;
(ii) at least one non-electroactive inorganic filler material, in an amount of from 70 to 95% wt; and
(iii) one or more than one additional additive, in an amount of 0 to 5% wt; and optionally, adding water for adjusting solid contents in the range of 30 to 80% wt %.

15 . A method for the manufacture of a composite separator suitable for use in an electrochemical cell, said method comprising:
applying the composition (AC) as defined in claim 11 onto at least one surface of a porous substrate to provide a coating composition layer; and drying said coating composition layer at a temperature of at least 60° C., to provide said composite separator.

16 . The dispersion (D) of claim 4 , wherein each of R1, R2, R3 are hydrogen, and R OH is a hydroxyl group or a C 1 -C 5 hydrocarbon moiety comprising at least one hydroxyl group.

17 . The dispersion (D) of claim 6 , wherein polymer (A) comprises at least 0.2% moles and at most 3% moles of recurring units derived from said hydrophilic (meth)acrylic monomer (MA).

18 . The dispersion (D) according to claim 7 , wherein polymer (A) possesses a melt viscosity (MV) of less than 80 kPoise, when determined at a shear rate of 100 sec −1 , and at a temperature of 230° C., according to ASTM D3835.

19 . The dispersion (D) according to claim 8 , wherein polymer (A) comprises an amount of polar end groups of formula —CH 2 OH of at least 5 mmol/kg and at most 12 mmol/kg.

20 . The composition (AC) of claim 13 , wherein the at least one additional additive is selected from the group consisting of non-ionic emulsifiers, alkoxylated alcohols, ethoxylated alcohols, propoxylated alcohols, mixed ethoxylated/propoxylated alcohols, fatty acid salts, alkyl sulfonate salts, sodium dodecyl sulfate, alkylaryl sulfonate salts and arylalkyl sulfonate salts.

Assignees

• Solvay Specialty Polymers It

Inventors

• Carella Serena
• Molena Elena
• Biso Maurizio
• Brinati Giulio

Classifications

• C09D127/16 Primary

  Homopolymers or copolymers of vinylidene fluoride · CPC title

• C09D5/24

  Electrically-conducting paints {(conductive materials H01B1/00)} · CPC title

• C08F214/225 Primary

  with non-fluorinated comonomers · CPC title

• H01M2/166

  Electricity · mapped topic

• H01M2/145

  Electricity · mapped topic