Polymer composition comprising basic additive, process and articles comprising said polymer composition

Abstract

The present invention relates to polymer compositions comprising at least one basic additive, and processes comprising at least one process step to obtain the polymer composition or articles comprising the polymer composition. The polymer composition generally displays an enhanced biodegradability.

Claims

1. A polymer composition comprising at least one polymer and at least one basic additive, wherein the at least one basic additive has a pH of equal to or less than 13 and equal to or higher than 7 when measured in a 1 wt. % solution in water at 20° C., wherein the at least one polymer is a cellulose ester selected from the group consisting of cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate, wherein the cellulose ester has an average degree of substitution from 1.5 to 3.0; wherein the at least one basic additive is present in the polymer composition in the form of distributed particles; and wherein the polymer composition does not include ZnO as a basic additive; wherein the polymer composition comprises 0.01 to 40 wt.-% of basic additive, relative to the combined weight of polymer and additive; and wherein the polymer composition has an enhanced biodegradability in terms of: (i) an average weight loss that is 10% or greater, according to the soil burying test according to EN ISO 11721-1 after two months, compared to the polymer composition without the at least one basic additive, or (ii) an O.sub.2 consumption that is more than two times greater, as determined in an aquatic aerobic biodegradation after 28 days when measured according to ISO 14851, compared to the polymer composition without the at least one basic additive, wherein the at least one basic additive is selected from the group consisting of MgO, CaO, Ca(OH).sub.2, NaHCO.sub.3, Na.sub.2CO.sub.3, KHCO.sub.3, K.sub.2CO.sub.3 and basic Al.sub.2O.sub.3; wherein the polymer composition further comprises at least one inhibitor of autocondensation reactions occurring in solvents with at least one carbonyl function and a C—H bond in a-position to said carbonyl function; and wherein the at least one inhibitor present in the polymer composition is in an amount of from 0.001 to 10 wt. %.

2. The polymer composition according to claim 1, wherein the at least one basic additive has a solubility of from 10.sup.−6 to 70 g/100 ml water at 20° C.

3. The polymer composition according to claim 2, wherein the at least one basic additive has a solubility of from 10.sup.−5 g/100 ml to 1 g/100 ml water at 20° C.

4. The polymer composition according to claim 1, wherein the at least one basic additive is selected from the group consisting of MgO, CaO, NaHCO.sub.3, Na.sub.2CO.sub.3, and KHCO.sub.3.

5. The polymer composition according to claim 1, wherein the at least one basic additive is selected from the group K.sub.2CO.sub.3 and basic Al.sub.2O.sub.3.

6. The polymer composition according to claim 1, wherein the at least one basic additive is present in the polymer composition in the form of distributed particles having a D90 particle size that is equal to or less than 10 μm.

7. The polymer composition according to claim 6, wherein the distributed particles are present in an amount of from 0.01 to 40 wt. %.

8. The polymer composition according to claim 1, wherein the at least one inhibitor is selected from the group consisting of carboxylic acids and alcohols.

9. The polymer composition according to claim 1, wherein the at least one inhibitor is selected from the group consisting of citric acid, lactic acid, malic acid, and tartaric acid.

10. The polymer composition of claim 1, comprising equal to or less than 10 wt % of the basic additive.

11. The polymer composition according to claim 1, wherein the at least one basic additive is selected from the group consisting of MgO, CaO, and basic Al.sub.2O.sub.3.

12. The polymer composition according to claim 1, wherein the at least one inhibitor is selected from the group consisting of carboxylic acids.

13. The polymer composition according to claim 1, wherein the at least one inhibitor is selected from the group consisting of carboxylic acids.

14. A process for making the polymer composition, or articles comprising the polymer composition, according to claim 1, the process comprising at least one step wherein the at least one step is selected from the group of steps comprising: a) contacting the at least one basic additive and optionally the at least one inhibitor with the at least one polymer in a liquid phase comprising at least one solvent, and subsequently separating the at least one solvent to obtain the polymer composition, b) contacting the at least one basic additive and optionally the at least one inhibitor with the at least one polymer in a liquid phase comprising at least one solvent, and subsequently spinning the resulting mixture to obtain fibres comprising the polymer composition, c) contacting the at least one basic additive and optionally the at least one inhibitor with the at least one polymer in a liquid phase comprising at least one solvent, and wherein the resulting mixture subsequently is processed in a film producing process to obtain films comprising the polymer composition, d) contacting the at least one basic additive and the at least one polymer, wherein at least part of the at least one polymer is in molten state, and optionally cooling the mixture to obtain the polymer composition, and e) contacting the at least one basic additive with the at least one polymer, wherein at least part of the at least one polymer is in molten state, and subsequently extruding and/or film-blowing the mixture to obtain a moulded part, a fibre, a film, a deep-drawn film, an injection-moulded article, a thick-walled moulded part, a granulate, a microbead, a bead, a vessel, or a flower pot comprising the polymer composition.

15. A filter tow comprising fibers of the composition made by the process according to claim 14.

16. A filter tow comprising the polymer composition according to claim 1.

Description

EXAMPLE 1

Degradability of Cast Films

(1) Films were made by dissolving cellulose acetate DS 2.45 in acetone and adding the basic additive and optionally the inhibitor. The resulting mixture was submitted to a film casting procedure using an automated film applicator. The films were dried, cut to pieces (6.5 cm×6.5 cm), the pieces were mounted in frames, and buried in soil according to EN ISO 11721-1. After 1 and after 2 months the specimens were retrieved from soil, carefully cleaned from coarse deposits and checked for weight and visually for missing area. Each reported weight loss and missing are, respectively, is an average of 6 films and related to the parts of the film which was in contact with the soil

(2) Film A: from 15 parts cellulose acetate and 85 parts acetone (comparative example)

(3) Film B: from 15 parts cellulose acetate, 85 parts acetone, 0.79 parts MgO (resulting in 5 wt % MgO in final product)

(4) Film C: from 15 parts cellulose acetate, 85 parts acetone, 0.38 parts MgO (resulting in 2.5 wt % MgO in final product)

(5) Film D: from 15 parts cellulose acetate, 85 parts acetone, 0.79 parts MgO (resulting in 5 wt % MgO in final product) and 0.08 parts citric acid (resulting in 0.5 wt % citric acid in final product)

(6) TABLE-US-00001 TABLE 1 Degradability as determined by EN ISO 11721-1. Average weight Average missing MgO Citric Acid loss (%) area (%) Film (wt %) (wt %) 1 month 2 months 1 month 2 months A 0 0 0 0 0 0 B 5 0 13 29 29 49 C 2.5 0 3 16 12 28 D 5 0.5 16 26 32 45

EXAMPLE 2

Degradability of Spun Fibres

(7) Spinning solutions were manufactured by mixing cellulose acetate (DS 2.45) and acetone, and spun to 1.9 denier filaments with a Y-cross-section using the dry spinning method. The filaments were milled and subjected to an aquatic aerobic biodegradation test according to ISO 14851. The biodegradation was determined by measurement of the O.sub.2 consumption.

(8) Filament A (comparative): Spinning solution from 26.9 parts of cellulose acetate and 0.1 parts TiO.sub.2 in 73 parts acetone.

(9) Filament B: Spinning solution from 25.6 parts of cellulose acetate, 1.35 parts MgO (resulting in 5 wt % in the final product), 0.07 parts citric acid (resulting in 0.25 wt % in the final product) and 0.1 parts TiO.sub.2 in 73 parts acetone.

(10) TABLE-US-00002 TABLE 2 Degradability as determined by ISO 14851 Biodegradation MgO Citric Acid Biodegradation (%) (%) Filament (wt %) (wt %) after 28 days after 56 days A 0 0 8 12 B 5 0.25 60 87