FLUORINATED THERMOPLASTIC ELASTOMER

Abstract

The present invention pertains to a fluorinated thermoplastic elastomer, to a process for the manufacture of said fluorinated thermoplastic elastomer and to uses of said fluorinated thermoplastic elastomer in various applications, especially in low temperature applications.

Claims

1. A fluorinated thermoplastic elastomer comprising: at least one block (A) consisting of at least one elastomeric fluoropolymer substantially free from recurring units derived from tetrafluoroethylene (TFE), and at least one block (B) consisting of at least one thermoplastic fluoropolymer comprising: recurring units derived from vinylidene fluoride (VDF), and optionally, recurring units derived from at least one fluorinated monomer different from VDF.

2. The fluorinated thermoplastic elastomer according to claim 1, said fluorinated thermoplastic elastomer comprising one or more repeating structures of type B-A-B.

3. The fluorinated thermoplastic elastomer according to claim 1, wherein the elastomeric fluoropolymer of the block (A) has a heat of fusion of less than 5 J/g, measured according to ASTM D3418-08.

4. The fluorinated thermoplastic elastomer according to claim 1, wherein the elastomeric fluoropolymer of the block (A) consists of: recurring units derived from vinylidene fluoride (VDF), recurring units derived from at least one fluorinated monomer different from VDF and tetrafluoroethylene (TFE), and optionally, recurring units derived from at least one hydrogenated monomer.

5. The fluorinated thermoplastic elastomer according to claim 1, wherein the elastomeric fluoropolymer of the block (A) consists of: from 45% to 90% by moles of recurring units derived from vinylidene fluoride (VDF), from 5% to 50% by moles of recurring units derived from at least one fluorinated monomer different from VDF and tetrafluoroethylene (TFE), and optionally, up to 30% by moles of recurring units derived from at least one hydrogenated monomer.

6. The fluorinated thermoplastic elastomer according to claim 1, wherein the thermoplastic fluoropolymer of the block (B) has a heat of fusion of from 10 J/g to 90 J/g, as measured according to ASTM D3418-08.

7. The fluorinated thermoplastic elastomer according to claim 1, wherein the thermoplastic fluoropolymer of the block (B) comprises: recurring units derived from vinylidene fluoride (VDF), and optionally, from 0.1% to 10% by moles of recurring units derived from at least one fluorinated monomer different from VDF.

8. The fluorinated thermoplastic elastomer according to claim 1, wherein the thermoplastic fluoropolymer of the block (B) further comprises recurring units derived from at least one hydrogenated monomer.

9. The fluorinated thermoplastic elastomer according to claim 1, wherein the weight ratio between blocks (A) and blocks (B) is comprised between 5:95 and 95:5.

10. A process for the manufacture of the fluorinated thermoplastic elastomer according to claim 1, said process comprising the following sequential steps: (a) polymerizing at least one fluorinated monomer different from tetrafluoroethylene (TFE) and, optionally, at least one hydrogenated monomer, in the presence of a radical initiator and of an iodinated chain transfer agent, thereby providing a pre-polymer consisting of at least one block (A) containing one or more iodinated end groups; and (b) polymerizing vinylidene fluoride (VDF), optionally at least one fluorinated monomer different from VDF, and optionally at least one hydrogenated monomer, in the presence of a radical initiator and of the pre-polymer provided in step (a), thereby providing at least one block (B) grafted on said pre-polymer by means of the iodinated end groups.

11. A composition (C) comprising: at least one fluorinated thermoplastic elastomer according to claim 1, and optionally, one or more additives.

12. An article comprising the composition (C) according to claim 11.

13. (canceled)

14. A method for manufacturing an article, the method comprising using the composition (C) according to claim 11 as a processing aid.

15. A process for the manufacture of the article according to claim 12, said process comprising processing a composition comprising at least one polymer, in the presence of a composition (C), using a melt-processing technique selected from compression moulding, injection moulding and extrusion moulding, wherein composition (C) comprises: at least one fluorinated thermoplastic elastomer comprising: at least one block (A) consisting of at least one elastomeric fluoropolymer substantially free from recurring units derived from tetrafluoroethylene PTFE), and at least one block (B) consisting of at least one thermoplastic fluoropolymer comprising: recurring units derived from vinylidene fluoride (VDF), and optionally, recurring units derived from at least one fluorinated monomer different from VDF, and optionally, one or more additives.

16. The fluorinated thermoplastic elastomer according to claim 4, wherein the elastomeric fluoropolymer of the block (A) has a heat of fusion of less than 3 J/g, as measured according to ASTM D3418-08.

17. The fluorinated thermoplastic elastomer according to claim 6, wherein the thermoplastic fluoropolymer of the block (B) has a heat of fusion of from 30 J/g to 60 J/g, as measured according to ASTM D3418-08.

18. The fluorinated thermoplastic elastomer according to claim 9, wherein the weight ratio between blocks (A) and blocks (B) is typically comprised between 20:80 and 80:20.

19. The fluorinated thermoplastic elastomer according to claim 1, wherein: the elastomeric fluoropolymer of the block (A) consists of: recurring units derived from vinylidene fluoride (VDF), recurring units derived from at least one fluorinated monomer different from VDF and tetrafluoroethylene (TFE), and optionally, recurring units derived from at least one hydrogenated monomer; and the thermoplastic fluoropolymer of the block (B) comprises: recurring units derived from vinylidene fluoride (VDF), and optionally, from 0.1% to 10% by moles of recurring units derived from at least one fluorinated monomer different from VDF.

20. The fluorinated thermoplastic elastomer according to claim 19, wherein the elastomeric fluoropolymer of the block (A) consists of: from 45% to 90% by moles of recurring units derived from vinylidene fluoride (VDF), from 5% to 50% by moles of recurring units derived from at least one fluorinated monomer different from VDF and tetrafluoroethylene (TFE), and optionally, up to 30% by moles of recurring units derived from at least one hydrogenated monomer.

Description

EXAMPLE 1: BLOCK COPOLYMER HAVING STRUCTURE PVDF-P(VDF-HFP)-PVDF (P(VDF-HFP) VDF: 78.5% BY MOLES, HFP: 21.5% BY MOLES)

[0136] In a 7.5 liters reactor equipped with a mechanical stirrer operating at 72 rpm, 4.5 l of demineralized water and 22 ml of a microemulsion, previously obtained by mixing 4.8 ml of a perfluoropolyoxyalkylene having acidic end groups of formula CF.sub.2ClO(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.2COOH, wherein n/m=10, having an average molecular weight of 600, 3.1 ml of a 30% v/v NH.sub.4OH aqueous solution, 11.0 ml of demineralized water and 3.0 ml of GALDEN D02 perfluoropolyether of formula CF.sub.3O(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.3, wherein n/m=20, having an average molecular weight of 450, were introduced.

[0137] The reactor was heated and maintained at a set-point temperature of 85 C.; a mixture of vinylidene fluoride (VDF) (78.5% moles) and hexafluoropropylene (HFP) (21.5% moles) was then added to reach a final pressure of 20 bar. Then, 8 g of 1,4-diiodoperfluorobutane (C.sub.4F.sub.8I.sub.2) as chain transfer agent were introduced, and 1.25 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 20 bar by continuous feeding of a gaseous mixture of vinylidene fluoride (VDF) (78.5% by moles) and hexafluoropropylene (HFP) (21.5% by moles) up to a total of 2000 g. Moreover, 0.86 g of CH.sub.2CH(CF.sub.2).sub.6CHCH.sub.2, fed in 20 equivalent portions each 5% increase in conversion, were introduced.

[0138] Once 2000 g of monomer mixture were fed to the reactor, the reaction was discontinued by cooling the reactor to room temperature. The residual pressure was then discharged and the temperature brought to 80 C. VDF was then fed into the autoclave up to a pressure of 20 bar, and 0.14 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 20 bar by continuous feeding of VDF up to a total of 500 g. Then, the reactor was cooled, vented and the latex recovered. The latex was treated with aluminum sulphate, separated from the aqueous phase, washed with demineralized water and dried in a convection oven at 90 C. for 16 hours.

[0139] Characterization data of the polymer so obtained are reported in Table 1.

COMPARATIVE EXAMPLE 1: P(VDF-HFP) FLUOROELASTOMER (VDF: 78.5% BY MOLES, HFP: 21.5% BY MOLES)

[0140] In a 7.5 liters reactor equipped with a mechanical stirrer operating at 72 rpm, 4.5 l of demineralized water and 22 ml of a microemulsion, previously obtained by mixing 4.8 ml of a perfluoropolyoxyalkylene having acidic end groups of formula CF.sub.2ClO(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.2COOH, wherein n/m=10, having an average molecular weight of 600, 3.1 ml of a 30% v/v NH.sub.4OH aqueous solution, 11.0 ml of demineralized water and 3.0 ml of GALDEN D02 perfluoropolyether of formula CF.sub.3O(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.3, wherein n/m=20, having an average molecular weight of 450, were introduced.

[0141] The reactor was heated and maintained at a set-point temperature of 85 C.; a mixture of vinylidene fluoride (VDF) (78.5% moles) and hexafluoropropylene (HFP) (21.5% moles) was then added to reach a final pressure of 20 bar. Then, 8 g of 1,4-diiodoperfluorobutane (C.sub.4F.sub.8I.sub.2) as chain transfer agent were introduced, and 1.25 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 20 bar by continuous feeding of a gaseous mixture of vinylidene fluoride (VDF) (78.5% moles) and hexafluoropropylene (HFP) (21.5% moles) up to a total of 2000 g. Moreover, 0.86 g of CH.sub.2CH(CF.sub.2).sub.6CHCH.sub.2, fed in 20 equivalent portions each 5% increase in conversion, were introduced. Then, the reactor was cooled, vented and the latex recovered. The latex was treated with aluminum sulphate, separated from the aqueous phase, washed with demineralized water and dried in a convection oven at 90 C. for 16 hours. Characterization data of the polymer so obtained are reported in Table 1.

COMPARATIVE EXAMPLE 2: BLOCK COPOLYMER HAVING STRUCTURE PVDF-P(VDF-HFP-TFE)-PVDF (P(VDF-HFP-TFE) VDF: 50% BY MOLES, HFP: 25% BY MOLES, TFE: 25% BY MOLES)

[0142] In a 5 liters reactor equipped with a mechanical stirrer operating at 630 rpm, 3.5 l of demineralized water and 36 ml of a microemulsion, previously obtained by mixing 7.9 ml of a perfluoropolyoxyalkylene having acidic end groups of formula CF.sub.2ClO(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.2COOH, wherein n/m=10, having an average molecular weight of 600, 5.1 ml of a 30% v/v NH.sub.4OH aqueous solution, 18.0 ml of demineralized water and 5.0 ml of GALDEN D02 perfluoropolyether of formula CF.sub.3O(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.3, wherein n/m=20, having an average molecular weight of 450, were introduced.

[0143] The reactor was heated and maintained at a set-point temperature of 80 C.; a mixture of vinylidene fluoride (VDF) (25.5% by moles), hexafluoropropylene (HFP) (58.5% by moles) and tetrafluoroethilene (16.0% by moles) was then added to reach a final pressure of 25 bar. Then, 6 g of 1,4-diiodoperfluorobutane (C.sub.4F.sub.8I.sub.2) as chain transfer agent were introduced, and 0.112 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 25 bar by continuous feeding of a gaseous mixture of vinylidene fluoride (VDF) (50.0% by moles), hexafluoropropyene (HFP) (26.0% by moles) and tetrafluoroethylene (24.0% by moles) up to a total of 1500 g. Moreover, 3 g of CH.sub.2CH(CF.sub.2).sub.6CHCH.sub.2, fed in 20 equivalent portions each 5% increase in conversion, were introduced.

[0144] Once 1500 g of monomer mixture were fed to the reactor, the reaction was discontinued by cooling the reactor to room temperature. The residual pressure was then discharged and the temperature brought to 80 C. VDF was then fed into the autoclave up to a pressure of 20 bar, and 0.05 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 20 bar by continuous feeding of VDF up to a total of 375 g. Then, the reactor was cooled, vented and the latex recovered. The latex was treated with aluminum sulphate, separated from the aqueous phase, washed with demineralized water and dried in a convection oven at 90 C. for 16 hours. Characterization data of the polymer so obtained are reported in Table 1.

COMPARATIVE EXAMPLE 3: P(VDF-HFP-TFE) FLUOROELASTOMER (VDF: 50% BY MOLES, HFP: 25% BY MOLES, TFE: 25% BY MOLES)

[0145] In a 5 liters reactor equipped with a mechanical stirrer operating at 630 rpm, 3.5 l of demineralized water and 36 ml of a microemulsion, previously obtained by mixing 7.9 ml of a perfluoropolyoxyalkylene having acidic end groups of formula CF.sub.2ClO(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.2COOH, wherein n/m=10, having an average molecular weight of 600, 5.1 ml of a 30% v/v NH.sub.4OH aqueous solution, 18.0 ml of demineralized water and 5.0 ml of GALDEN D02 perfluoropolyether of formula CF.sub.3O(CF.sub.2CF(CF.sub.3)O).sub.n(CF.sub.2O).sub.mCF.sub.3, wherein n/m=20, having an average molecular weight of 450, were introduced.

[0146] The reactor was heated and maintained at a set-point temperature of 80 C.; a mixture of vinylidene fluoride (VDF) (25.5% by moles), hexafluoropropylene (HFP) (58.5% by moles) and tetrafluoroethylene (16.0% by moles) was then added to reach a final pressure of 25 bar. Then, 6 g of 1,4-diiodoperfluorobutane (C.sub.4F.sub.8I.sub.2) as chain transfer agent were introduced, and 0.112 g of ammonium persulfate (APS) as initiator were introduced. Pressure was maintained at a set-point of 25 bar by continuous feeding of a gaseous mixture of vinylidene fluoride (VDF) (50.0% by moles), hexafluoropropylene (HFP) (26.0% moles) and tetrafluoroethylene (24.0% by moles) up to a total of 1500 g. Moreover, 3 g of CH.sub.2CH(CF.sub.2).sub.6CHCH.sub.2, fed in 20 equivalent portions each 5% increase in conversion, were introduced.

[0147] Then, the reactor was cooled, vented and the latex recovered. The latex was treated with aluminum sulphate, separated from the aqueous phase, washed with demineralized water and dried in a convection oven at 90 C. for 16 hours. Characterization data of the polymer so obtained are reported in Table 1.

[0148] As shown in Table 1 here below, the fluorinated thermoplastic elastomer of the present invention as notably embodied by the block copolymer of Example 1 according to the invention, wherein the elastomeric block is substantially free from recurring units derived from tetrafluoroethylene, unexpectedly has a glass transition temperature lower than the glass transition temperature of the corresponding fluoroelastomer as notably embodied by the fluoroelastomer of Comparative Example 1.

[0149] Also, as shown in Table 1 here below, the fluorinated thermoplastic elastomer of the present invention as notably embodied by the block copolymer of Example 1 according to the invention, wherein the elastomeric block is substantially free from recurring units derived from tetrafluoroethylene, unexpectedly has a glass transition temperature lower than the glass transition temperature of the block copolymer of Comparative Example 2, wherein the elastomeric block further comprises recurring units derived from tetrafluoroethylene.

[0150] On the other side, the block copolymer of Comparative Example 2, wherein the elastomeric block further comprises recurring units derived from tetrafluoroethylene, has a glass transition temperature higher than the glass transition temperature of the corresponding fluoroelastomer of Comparative Example 3.

TABLE-US-00001 TABLE 1 DSC Ex. 1 C. Ex. 1 C. Ex. 2 C. Ex. 3 T.sub.g [ C.] 21.5 18.0 9.0 10.6 T.sub.m [ C.] 162.5 162.4 H.sub.m [J/g] 11.6 15.9 soft hard soft hard Composition - NMR (A) (B) (A) (B) VDF [% mol] 78.5 100 78.5 50 100 50 HFP [% mol] 21.5 21.5 25 25 TFE [% mol] 25 25

[0151] In view of the above, it has been surprisingly found that the fluorinated thermoplastic elastomer of the present invention, wherein the elastomeric block is substantially free from recurring units derived from tetrafluoroethylene, exhibits outstanding performances such as outstanding mechanical performances over a wide range of temperatures up to low temperatures to be suitably used in various applications such as, for instance, low temperature applications.