Patent GB-962199-A (GB)
Title: Stabilisation of plastic compositions based on cellulose esters
IPC: C08L1/08
Filed: 1962-12-20
Abstract: Plastic compositions comprising a major proportion of cellulose organic acid esters are stabilized against the effects of heat, light, or weather, and rendered odourless by the addition of one or more carbodiimides.  In general, aliphatic, cycloaliphatic or aromatic monocarbodiimides may be used, those of the formula: <FORM:0962199/C3/1> being preferred, where R represents like or different alkyl, alkoxy, or aryl radicals, especially phenyl and aralkyl and particularly phenalkyl radicals, R1 represents R or alternatively halogen or nitro-radicals, X is any desired inert radical and n is an integer from 0 to 3. Alkyl-substituted derivatives of diphenylcarbodiimide are preferred. Monocarbodiimides specified include N, N1-diisopropylcarbodiimide, N,N1-dibutylcarbodiimide, N, N1-diallylcarbodiimide, N, N1-dioctylcarbodiimide, N, N1-dicyclopentylcarbodiimide, N, N1-dicyclohexylcarbodiimide, N, N1-dicycloheptylcarbodiimide, N, N1-dicyclooctylcarbodiimide, N, N1-dibornylcarbodiimide, diphenylcarbodiimide, N, N1-di-p-tolyl-carbodiimide, dip-bromo-phenylcarbodiimide, di-p-carbethoxyphenylcarbodiimide, di-p-diethylaminophenylcarbodiimide, di-a -naphthylcarbodiimide,di-b -naphthylcarbodiimide, di-a -pyridylcarbodiimide, N-methyl-N1-tert.-butylcarbodiimide, N-hexyl-N1-isopropylcarbodiimide, N-(n-hexadecyl)-N1-(tert. butyl)-carbodiimide, N - n - dodecyl -N1 - (tert. butyl)-carbodiimide, N-allyl-N1-oleylcarbodiimide, N-allyl-N1-cyclo-hexyl-carbodiimide, N-tert.-butyl-N1-cyclohexylcarbodiimide, N-tert.-butyl-N1-furfurylcarbodiimide, N-propyl-N1-phenyl-carbodiimide, N-isopropyl-N1-3-chlorophenylcarbodiimide, N-phenyl-N1-benzylcarbodiimide, N-isopropyl-N1-naphthylcarbodiimide, N-phenyl-N1-p-tolyl-carbodiimide and N-phenyl-N1-tritylcarbodiimide. Diphenyl carbodiimide derivatives which are substituted on the aromatic radicals are also useful, especially for odour-removal, and may be made according to Specification 930,036 from aromatic monoisocyanates, which carry one or two aryl, alkyl, aralkyl or alkoxy-substituents in the o-position to the NCO-group, at least one of the substituents comprising at least two carbon atoms, under the action of e.g. tertiary amines, or basically reacting metal compounds.  Examples cited are 2,21-diethyl-diphenyl carbodiimide, 2,21-diisopropyl-diphenyl carbodiimide, 2,21-diethoxydiphenyl carbodiimide, 2,21,6, 61-tetraethyl-diphenyl-carbodiimide, 2,21,6,61-tetraethyl-4, 41-dimethyl-diphenyl-carbodiimide, 2, 21, 6, 61-tetraisopropyl-diphenyl-carbodiimide, 2,21,6,61-tetra-sec. butyl-diphenyl-carbodiimide, and 2,21, 6, 61-tetraethyl-3, 31-dichlorodiphenyl-carbodiimide. Polycarbodiimides, e.g. tetra methylene-w, w1-bis-tert.-butyl-carbodiimide, hexamethylene-w, w1-bis-tert.-butyl-carbodiimide and hexamethylene-w, w1-bis-cyclohexyl-carbodiimide are also suitable, as well as those polycarbodiimides which can be made according to Specification 930,036 from aromatic diisocyanates and polyisocyanates, e.g. polycarbodiimides from 1,3,5-triethylbenzene-2, 4-diisocyanate or 1,3,5-triisopropylbenzene-2, 4-diisocyanate.  Mixtures of carbodiimides may also be used.  Desirably, the composition contains 0.1-5% by weight, especially 0.5-2% by weight, of the carbodiimide, which may be admixed in solid form with the cellulose esters, in combination with other added substances e.g. plasticisers, antioxidants, ultra-violet absorbers, dyestuffs, pigments and fillers, or dissolved in suitable solvents which can be solvents or non-solvents for the cellulose esters. Processing is effected in known manner. Cellulose esters specified include cellulose acetate, propionate, butyrate, acetopropionate and acetobutyrate. Plasticisers mentioned include phthalates, sebacates, adipates, phosphates and citrates, particularly diethyl phthalate, dibutyl adipate, dibutyl sebacate, and a mixture of dioctyl phthalate and dibutyl adipate. Solvents specified include methylene chloride, trichloroethylene and diethyl ether. Specified pigments include red iron oxide and green chromium oxide.  The polycarbodiimide of 1,3,5-triisopropylbenzene-2, 4-diisocyanate is made by heating 100 parts by weight of 1,3,5-triisopropyl-benzene-2,4-diisocyanate with 1 part by weight of 35% sodium methylate in methanol for 3 hours at 180-200 DEG C.ALSO:Aluminium foil is coated with a cellulose acetobutyrate composition containing 1% of N-(n-hexadecyl)-N1-(tert. butyl)-carbodiimide and coloured with 0,03% of red iron oxide. Ornamental strips produced therefrom are free from butyric acid odour.  Comparable results are obtained using N,N1-dicyclohexylcarbodiimide or N,N1-di-p-tolyl-carbodiimide.  In an alternative method, 1% of 2,21,6,61-tetraisopropyl-diphenylcarbodiimide is added to a fluidized sinter powder based on cellulose acetobutyrate and a plasticizer, the carbodiimide being dissolved in diethyl ether and sprayed on to the fluidized sinter powder. After evaporating the ether, coatings 3mm. thick were produced on aluminium sheets, which on heating to 320-420 DEG C. were still free from butyric acid odour.  Hence higher processing temperatures may be used, leading to more homogeneous coating and better adhesion. In general, aliphatic, cycloaliphatic or aromatic monocarbodiimides may be used, those of the formula: <FORM:0962199/B1-B2/1> being preferred, where R represents like or different alkyl, aloxy or aryl radicals, especially phenyl and aralkyl and particularly phenalkyl radicals, R1 represents R or alternatively halogen or nitro-radicals, X is any desired inert radical and n is an integer from 0 to 3.  Alkyl-substituted derivatives of diphenylcarbodiimide are preferred.  Monocarbodiimides specified include N,N1-diisopropylcarbodiimide, N,N1-dibutycarbodiimide, N,N1-diallylcarbodiimide, N,N1-dioctylcarbodiimide, N,N1-dicyclopentylcarbodiimide, N,N1-dicyclohexylcarbodiimide, N,N1-dicyclohexycarbodiimide, N,N1-dicycloheptylcarbodiimide, N,N1-dicyclooctylcarbodiimide, N,N1-dibornylcarbodiimide, diphenylcarbodiimide, N,N1-di-p-tolyl-carbodiimide, di-p-bromo-phenylcarbodiimide, di-p-carbethoxyphenylcarbodiimide, di-p-diethylaminophenylcarbodiimide, di-a -naphthylcarbodiimide, di-b -naphthylcarbodiimide, di-a -pyridylcarbodiimide, N-methyl-N1-tert.-butylcarbodiimide, N-hexyl-N1-isopropylcarbodiimide, N-(n-hexadecyl)-N1-(tert. butyl)-carbodiimide, N-n-dodecyl-N1-(tert. butyl)-carbodiimide, N-allyl-N1-oleylcarbodiimide, N-alkyl-N1-cyclohexylcarbodiimide, N-tert. butyl-N1-cyclohexylcarbodiimide, N-tert. butyl-N1-cyclohexylcarbodiimide, N-tert. butyl-N1-furfurylcarbodiimide, N-propyl-N1-phenylcarbodiimide, N-isopropyl-N1-3-chlorophenylcarbodiimide, N-phenyl-N1-benzylcarbodiimide, N-isopropyl-N1-naphthylcarbodiimide, N-phenyl-N1-p-tolylcarbodiimide, and N-phenyl-N1-tritylcarbodiimide. Diphenylcarbodiimide derivatives which are substituted on the aromatic radicals are also useful, especially for odour-removal, and may be made according to Specification 930,036 from aromatic monoisocyanates, which carry one or two aryl, alkyl, aralkyl or alkoxy-substituents in the o-position to the NCO group, at least one of the substituents comprising at least two carbon atoms under the action of e.g. tertiary amines, or basically reacting metal compounds.  Examples cited are 2,21-diethyl-diphenylcarbodiimide, 2,21-diisopropyl-diphenylcarbodiimide, 2,21-diethoxydiphenylcarbodiimide, 2,21-6,61-tetraethyl-diphenyl-carbodiimide, 2,21,6, 61-tetraethyl-4-41-dimethyl-diphenyl-carbodiimide, 2,21,6,61-tetraisopropyl-diphenyl-carbodiimide, 2,21,6,61-tetra-sec. butyl-diphenyl-carbodiimide, and 2,21,6,61-tetraethyl-3, 31-dichloro-diphenyl-carbodiimide.  Polycarbodiimides, e.g. tetramethylene-w,w1-bis-tert. butyl-carbodiimide, hexamethylene-w,w1-bis-tert.butyl-carbodiimide, and hexamethylene-w,w1-bis-cyclohexyl-carbodiimide are also suitable, as well as those polycarbodiimides which can be made according to Specification 930,036 from aromatic diisocyanates and polyisocyanates e.g. polycarbodiimides from 1,3,5-triethylbenzene-2,4-diisocyanate or 1,3,5-triisopropylbenzene-2,4-diisocyanate.  Mixtures of carbodiimides may also be used.  Desirably, the composition p contains 0,1-5% by weight, especially 0,5-2% by weight, of the carbodiimide, which may be admixed in solid form with the cellulose esters, in combination with other added substances, e.g. plasticizers, antioxidants, ultraviolet absorbers, dyestuffs, pigments and fillers, or dissolved in suitable solvents which can be solvents or non-solvents for the cellulose esters. Processing is effected in known manner.  Cellulose esters specified include cellulose acetate, propionate, butyrate, acetopropionate and acetobutyrate.  Plasticizers mentioned include phthalates, sebacates, adipates, phosphates and citrate, particularly diethyl phthalate, dibutyl adipate, dibutyl sebacate, and a mixture of dioctyl phthalate and dibutyl adipate.  Solvents specified include methylene chloride, trichloroethylene, and diethyl ether.  Specified pigments include red iron oxide and green chromium oxide.