Vinylidene fluoride polymer

Abstract

The present invention pertains to a vinylidene fluoride polymer, to a process for manufacturing said vinylidene fluoride polymer and to an article comprising said vinylidene fluoride polymer.

Claims

1. A process for manufacturing a vinylidene fluoride polymer (VDF), said process comprising polymerizing vinylidene fluoride and from 0.01% to 10% by moles, with respect to the total amount of moles of said vinylidene fluoride, of at least one (meth)acrylic monomer (MA) and, optionally, at least one fluorinated monomer different from vinylidene fluoride in an aqueous suspension medium comprising: at least one polyalkylene oxide of formula (I):
R.sub.AO—[(CH.sub.2).sub.mO].sub.n—R.sub.B  (I) wherein R.sub.A and R.sub.B, equal to or different from each other, are H or a C.sub.1-C.sub.5 linear or branched alkyl group, m, equal to or different from each other at each occurrence, is an integer from 2 to 5, and n is an integer from 1000 to 200000, and at least one polysaccharide derivative in an amount of from 0.4 to 0.8 g, per Kg of vinylidene fluoride.

2. The process according to claim 1, wherein the monomer (MA) is of formula (II): ##STR00006## wherein R.sub.1, R.sub.2 and R.sub.3, equal to or different from each other, are independently a hydrogen atom or a C.sub.1-C.sub.3 hydrocarbon group, and R.sub.x is a hydrogen or a C.sub.1-C.sub.5 hydrocarbon group optionally comprising at least one hydroxyl group.

3. The process according to claim 1, wherein the polyalkylene oxide of formula (I) is a polyethylene oxide of formula (I-A):
R′.sub.AO—(CH.sub.2CH.sub.2O).sub.n′—R′.sub.B  (I-A) wherein R′.sub.A and R′.sub.B, equal to or different from each other, are H or a C.sub.1-C.sub.5 linear or branched alkyl group, and n′ is an integer from 1000 to 200000.

4. The process according to claim 1, wherein the polyalkylene oxide of formula (I) is a polyethylene glycol of formula (1-B):
HO—(CH.sub.2CH.sub.2O).sub.n″—H  (1-B) wherein n″ is an integer from 1000 to 200000.

5. The process according to claim 1, said process being carried in the presence of at least one polyalkylene oxide of formula (I), in an amount of from 0.01 to 5 g per Kg of vinylidene fluoride.

6. The process according to claim 1, wherein the polysaccharide derivative comprises recurring units derived from glycosidic units selected from the group consisting of D-glucopyranosides, D-glucofuranosides and mixtures thereof, said glycosidic units being linked to each other by glycosidic bonds.

7. The process according to claim 1, wherein the polysaccharide derivative comprises recurring units derived from β-D-glucopyranosides of formula (III) linked to each other by β-glycosidic bonds: ##STR00007## wherein each R′, equal to or different from any other at each occurrence, represents a hydrogen atom, a C.sub.1-C.sub.8 hydrocarbon group or a C.sub.2-C.sub.8 hydroxyalkyl group.

8. The process according to claim 7, wherein each R′, equal to or different from any other, is a hydrogen atom, a methyl group, a hydroxyethyl group or a 2-hydroxypropyl group.

9. The process according to claim 1, wherein the polysaccharide derivative is selected from the group consisting of methylcellulose, hydroxyethyl methylcellulose, hydroxyethyl ethylcellulose and hydroxypropyl methylcellulose.

10. The process according to claim 1, wherein the weight ratio of at least one polyalkylene oxide of formula (I) to at least one polysaccharide derivative is comprised between 1:10 and 10:1.

11. A vinylidene fluoride polymer (VDF) obtainable by the process according to claim 1.

12. A composition (C) comprising at least one polymer (VDF) according to claim 11.

13. An article comprising the composition (C) according to claim 12.

14. The article according to claim 13, which is a binder in electrodes for secondary batteries or a separator for secondary batteries.

15. The process according to claim 1, wherein the vinylidene fluoride is polymerized with 0.1% to 3% by moles, with respect to the total amount of moles of said vinylidene fluoride, of at least one (meth)acrylic monomer (MA).

16. The process according to claim 1, wherein n is an integer from 5000 to 70000.

17. The process according to claim 3, wherein n′ is an integer from 5000 to 70000.

18. The process according to claim 4, wherein n″ is an integer from 5000 to 70000.

19. The process according to claim 1, said process being carried in the presence of at least one polyalkylene oxide of formula (I-A) or at least one polyethylene glycol of formula (1-B), in an amount of from 0.05 to 1.5 g of per Kg of vinylidene fluoride.

Description

EXAMPLES 1-7

(1) The process conditions are set forth in Table 2.

(2) Examples 1, 2, 6 and 7 were carried out in the 85 litres reactor according to the general procedure as detailed above.

(3) Examples 3, 4 and 5 were carried out in the 4 litres reactor according to the general procedure as detailed above.

(4) Example 3 was carried out according to the general procedure as detailed above using diethyl carbonate (DEC) in an amount of 26 g/Kg of vinylidene fluoride.

Comparative Examples 1-2

(5) The process conditions are set forth in Table 2.

(6) Comparative Examples 1 and 2 were carried out in the 85 litres reactor according to the general procedure as detailed above but without adding the ALKOX® PEO grades.

(7) TABLE-US-00002 TABLE 2 TAPPI AA Suspending agent Water [g/Kg VDF [g] [g/Kg VDF] Run [Kg] VDF] [Kg] Initial Differed a1 b1 b2 T = 55° C., P = 110 bar, AA = 14-15 g/Kg of water Ex. 1 46.2 2.85 25.27 10.8 253  0.125 0.8 — (E-60) Ex. 2 46.2 2.75 25.27 10.8 268 0.2 0.5 — (E-45) Ex. 3 2.16 5.0 1.17 0.5 12 0.2 0.5 — (E-45) C. Ex. 1 48.1 2.85 25.27 10.8 253 — 0.8 — T = 50° C., P = 120 bar, AA = 12.5 g/Kg of water Ex. 4 2.23 2.9 1.15 0.4 9 0.8 0.4 — (E-45) Ex. 5 2.24 2.9 1.16 0.4 9 1.5 0.4 — (E-45) Ex. 6 48.85 2.9 25.33 8.4 204 0.2 0.5 — (E-45) Ex. 7 48.85 2.9 25.33 8.4 204 0.8 — 1.5 (E-45) C. Ex. 2 48.85 2.9 25.33 8.4 204 — — 1.5

(8) As shown in Table 3, it has been found that the process of the invention advantageously enables obtaining VDF polymers as notably embodied by the polymers obtained according to the process of any one of Examples 1 to 7 exhibiting both good colour retention and good thermal stability to be suitably used in various applications.

(9) On the other side, the process for manufacturing the polymers of any of Comparative Examples 1 and 2, in the absence of a polyalkylene oxide, even using high amounts of a polysaccharide derivative, is not enough stable to be scaled up at industrial level.

(10) TABLE-US-00003 TABLE 3 Colour retention Viscosity Run Control of reaction [190° C.] [l/g] Ex. 1 E NW 0.30 Ex. 2 E NW 0.33 Ex. 3 — NW 0.10 C. Ex. 1 NG — 0.30 Ex. 4 — W 0.39 Ex. 5 — W 0.40 Ex. 6 E NW 0.37 Ex. 7 E NW 0.36 C. Ex. 2 NG — 0.37