http://rdf.ncbi.nlm.nih.gov/pubchem/patent/GB-662404-A
Outgoing Links
| Predicate | Object |
|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_19aaaa9f91b7bf94ef9bdd9425970c0c |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/B29C41-24 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/B29C41-24 |
| filingDate | 1949-10-25-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationDate | 1951-12-05-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | GB-662404-A |
| titleOfInvention | Improvements in or relating to a process and apparatus for casting films and sheets,and to products manufactured according to this process |
| abstract | <PICT:0662404/IV (a)/1> Films and sheets are made by casting solutions of film-forming compounds on a support, preferably of a drum or band casting machine, coated with a casting layer wholly or partly consisting of a partially esterified cellulose aceto formate, the point representing the chemical composition of which falls within the area ABCD on the graph shown in the drawing. This area is defined by the lines AD, corresponding with 80 per cent partial esterification of the aceto formates, AB, corresponding with a formyl content of more than 3 per cent, BC, corresponding with more than 14.4 per cent acetyl content, and CD, corresponding with less than 15 per cent formyl content. Cellulose aceto formates, 80 per cent esterified with an acetyl content of 14.4-32 per cent and a formyl content of 3-15 per cent, are said to dissolve well in aqueous mixtures of several organic solvents such as acetone, dioxane, ethyl lactate and ethylene chlorhydrin to form clear dopes from which casting layers may be obtained which have a high gloss and are very stable and indifferent to many individual organic solvents, such as acetone, chlorinated hydrocarbons, and chloroform, and to many non-aqueous mixtures of solvents in which the film-forming substances are dissolved. The cast film can therefore readily be detached from the casting layer. In an example a cellulose aceto formate having an acetyl content based on the total cellulose mixed ester of 22.6 per cent and a formyl content of 9 per cent and whose chemical composition is represented by the point I in the drawing is dissolved in four times its weight of a mixture of acetone, water and dioxane in the volume proportion of 2 : 1 : 2. This solution is coated on an endless band to form a casting layer which is allowed to dry. On this casting layer is cast a film-forming solution consisting of cellulose diacetate dissolved in acetone. After evaporation of the greater part of the solvent, the film is detached from the casting layer. Other examples are given of the production of films in a similar manner from solutions of other cellulose esters and from ethyl cellulose, using casting layers of various compositions according to the invention. The film-forming compounds used may be cellulose esters, cellulose ethers, polyvinyl compounds or synthetic rubber compounds, and the solvent may be removed from the film-forming layer by evaporation under reduced pressure or in a current of air or in processes in which the cast film-forming layer is passed through a precipitating bath. |
| priorityDate | 1948-10-30-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
Incoming Links
Total number of triples: 30.