Anistropic compositions of cellulose esters; processes for obtaining such compositions; fibers of cellulose esters or cellulose
AssigneeMichelin Recherche et Technique S.A.
InventorsPhilippe Villaine, Claude Janin
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Abstract
Composition (M) having a base of a cellulose ester having formate groups, this composition being an anisotropic solution containing: (a) the cellulose ester; (b) formic acid; (c) at least one phosphoric acid. A process for obtaining this composition by dissolving the cellulose and a process for obtaining articles by transformation of this composition, and, for example, regenerating the cellulose of these articles. A cellulose fiber is provided in which a degree of substitution of the cellulose by formate groups is either at least equal to 2% or is zero or less than 2%.
Claims24
A composition having a base of at least one cellulose derivative containing cellulose ester groups, at least a part of these ester groups being formate groups, such that it is an anisotropic solution which can give fibers or films and comprises:
- (a) a cellulose derivative or derivatives, the concentration of the cellulose derivative or of all of the cellulose derivatives in the solution being at least equal to 10.2% by weight, the degree of polymerization DP of the cellulose in the cellulose derivative or derivatives being greater than 150 and less than 1500 and the degree of substitution DS of the cellulose in ester groups other than formate of the cellulose derivative or derivatives being zero or less than 15%;
- (b) an organic acid phase of formic acid or at least two compounds selected from the group consisting of monocarboxylic organic acids and the anhydrides and halides of these acids, one of these compounds being formic acid;
- and
- (c) a phosphoric acid phase of at least one phosphoric acid, or at least one phosphoric acid and phosphoric anhydride.
A fiber formed at least in part of a filament having a base of at least one cellulose derivative containing cellulose ester groups, at least a part of these ester groups formate groups, comprising the following properties:
- (a) the degree of substitution DS of the cellulose by formate groups is at least equal to 2%, the degree of substitution DS of the cellulose in other ester groups is zero or less than 10% and the degree of polymerization DP of the cellulose is greater than 150 and less than 1500;
- (b) the tenacity T and the initial modulus M.sub.i of the fiber verify the following relationships, T and M.sub.i being expressed in cN/tex:
- T>20;
- M.sub.i >1000;
- (c) this filament has a morphology such that it is formed at least in part by layers embedded in each other, these layers surrounding the axis of the filament, and such that in each layer the optical direction and the direction of crystallization vary pseudoperiodically along the axis of the filament.
A fiber formed at least in part of a filament having a base of cellulose or of at least one cellulose derivative containing cellulose ester groups, at least a part of these ester groups being formate groups, comprising the following properties:
- (a) the degree of substitution DS of the cellulose by formate groups is zero or less than 2%, the degree of substitution DS of the cellulose in ester groups other than formate is zero or less than 1.5% and the degree of polymerization DP of the cellulose is greater than 150 and less than 1500;
- (b) the degree of polymerization DP of the cellulose, the tenacity T and the initial modulus M.sub.i of the fiber verify the following relationships, T and M.sub.i being expressed in cN/tex:
- for DP<200, one has T>20 and M.sub.i >1800;
- for 200.ltoreq.DP<300, one has T>30 and M.sub.i >2000;
- for 300.ltoreq.DP<400, one has T>'and M.sub.i >2400;
- for 400.ltoreq.DP<1500, one has T>60 and M.sub.i >2600;
- (c) this filament has a morphology such that it is formed at least in part by layers which are embedded in each other, these layers surrounding the axis of the filament, and such that in each layer the optical direction and the direction of crystallization vary pseudoperiodically along the axis of the filament.
Dependencies are inferred from the claim text.