Ion-conductive thermoplastic composition, electrochromic composite system and process for producing ion-conductive foil

1. An ion-conductive thermoplastic composition containing a partially acetalated polyvinyl alcohol, at least one support electrolyte and at least one plasticizer, wherein the partially acetalated polyvinyl alcohol is a co-polymer containing the following:

0.01 to 5% by weight of polyvinyl acetate;

10 to 40% by weight of vinyl alcohol; and

40 to 80% by weight of acetals I and II,

acetal I being obtained from vinyl alcohol and at least one aldehyde having formula I:

R 1 —CHO  (I)

where R 1 is a branched or unbranched alkyl radical having 1 to 10 carbon atoms, and

acetal II being obtained from vinyl alcohol and a carbonyl compound having formula II:

where R 2 =H or a branched or unbranched alkyl radical having 1 to 10 carbon atoms, R 3 =a direct bond, a branched or unbranched alkyl radical having 1 to 10 carbon atoms, or an aryl radical having 6 to 18 carbon atoms, and Y=—CO 2 H, —SO 3 H, or —PO 3 H 2 .

2. The ion-conductive thermoplastic composition according to claim 1 , wherein a ratio of monomer units in the partially acetalated polyvinyl alcohol of acetal I to acetal II is 1:1 to 10,000:1.

3. The ion-conductive thermoplastic composition according to claim 1 wherein acid-functionalized aldehydes are used as the carbonyl compound of formula II.

4. An electrochromic composite system built up of two bodies coated with electrodes, at least one of which is transparent and at least one exhibits an electrochromic film, which bodies are separated by a foil having a composition according to claim 1 .

5. The electrochromic composite system according to claim 4 , wherein at least one of the electrochromic films contains a metal polycyanometalate, transition metal oxide, or conductive polymer modifying a color on cathodic reduction.

6. The electrochromic composite system according to claim 4 , wherein at least one of the electrochromic films contains a metal polycyanometalate, transition metal oxide or conductive polymer modifying a color on anodic oxidation.

7. The electrochromic composite system according to claim 4 , wherein at least one of the electrochromic films contains tungsten trioxide.

8. The electrochromic composite system according to claim 4 , wherein at least one of the electrochromic films contains Prussian blue.

9. The electrochromic composite system according to claim 4 , wherein one of the electrochromic films contains tungsten trioxide and one of the electrochromic films contains Prussian blue.

10. A process for the production of an ion-conductive foil by extrusion of a mixture of:

a) 50-90% by weight of a partially acetalated polyvinyl alcohol containing the following:

0.01 to 5% by weight of polyvinyl acetate;

10 to 40% by weight of vinyl alcohol;

40 to 80% by weight of acetals I and II;

acetal I being obtained from vinyl alcohol and at least one aldehyde having formula I:

R 1 —CHO  (I)

where R 1 is a branched or unbranched alkyl radical having 1 to 10 carbon atoms;

acetal II being obtained from vinyl alcohol and a carbonyl compound having formula II:

where R 2 =H or a branched or unbranched alkyl radical having 1 to 10 carbon atoms, R 3 is a direct bond, a branched or unbranched alkyl radical having 1 to 10 carbon atoms, or an aryl radical having 6 to 18 carbon atoms, and Y=—CO 2 H, —SO 3 H, —PO 3 H 2 ;

b) 10 to 50% by weight of at least one plasticizer; and

c) 0.1 to 25% by weight of at least one support electrolyte.

11. The process according to claim 10 , wherein the extrusion is carried out under melt fracture conditions.

12. The process according to claim 10 , wherein the foil is embossed on one side or both sides having a roughness R z of 40-120 μm.