http://rdf.ncbi.nlm.nih.gov/pubchem/patent/GB-611495-A
Outgoing Links
| Predicate | Object |
|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_d647e846645953f86e9ba89e7f5ead3d |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C08G77-16 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/C08G77-16 |
| filingDate | 1946-05-02-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationDate | 1948-10-29-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | GB-611495-A |
| titleOfInvention | Improvements in and relating to the treatment of chloromethyl-substituted polysiloxanes |
| abstract | Polymers containing silicon-bonded chlorinated methyl groups are heated with an alkaline material in presence of moisture to remove the chlorinated methyl groups. Suitable alkalies are caustic potash, ammonia, sodium carbonate, basic metal oxides and organic salts of basic metal oxides. The polymers may be prepared from methylchlorosilanes chlorinated according to the processes described in Specifications 575,667, 575,668 and 575,669, [Group III]. Polysiloxanes containing silicon-bonded chloromethyl radicals may be converted by this method to silicols and thence to higher molecular weight polysiloxanes. In the examples: (1) Dimethyl (dichloromethyl) chlorosilane was hydrolysed by pouring into water. The separated sym-tetramethyl-bis-(dichloromethyl) disiloxane was treated with aqueous potassium hydroxide. A viscous oil was the product. (2) Methyl di - (chloromethyl) chlorosilane was hydrolysed and condensed to dimethyltetra-bis-(chloromethyl) disiloxane which was heated with caustic potash. (3) Methyl (trichloromethyl) dichlorosilane was hydrolysed and the resulting oil treated with caustic potash. (4) Sym - tetramethyl - bis - (dichloromethyl) disiloxane was warmed with moist sodium carbonate. Methylene chloride was evolved and the molecular weight of the product increased. Examples (5), (6) and (7) also employ sym - tetramethyl - bis - (dichloromethyl) dichloromethyl) disiloxane, which is heated with: example (5) aqueous sodium carbonate and n-butanol; (6) lead oxide; (7) an oil-soluble form of basic metal oxide "Nuodex" (R.T.M.). The chloromethyl groups are not split off under acidic conditions, so that siloxanes structures containing chloromethyl groups can be formed under acidic conditions and subsequently treated to increase the molecular weight. In example (8), heptamethyl-chloromethyl-cyclotetrasiloxane was polymerized to a toluene-soluble gum with ferric chloride as in Specification 585,628. The gum was compounded on milling rolls with 1 per cent of lead oxide and titanium dioxide as a filler and formed into sheets which were then cured at 150-200 DEG C. The products were similar to those of Specification 594,481. |
| priorityDate | 1945-05-05-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
Incoming Links
Total number of triples: 43.