Coating composition

摘要

A transparent coating composition comprises 40-85% by weight of a glyceride selected from the group consisting of:- (a) glycerides of the formula where R1 and R2 are selected from the group consisting of hydrogen and the acyl radicals of aliphatic monobasic and polybasic acids of from one to six carbon atoms, not more than one of R1 and R2 being hydrogen, and R3 is the acyl radical of an aliphatic, long-chain fatty acid having one unsaturated double bond and a chain length of from 10-30 carbon atoms, and (b) mixtures of such glycerides in which the average unsaturated double bond content of the long chain fatty acids is from 0,5 to 1,5; and from 60-15% by weight of a cellulose ester component having a hydroxyl content of from 0,5-2,5%, an acetyl content of from 6 to 32%, and from 15-50% of an aliphatic acyl radical of from 3-18 carbon atoms. R1 may be an acyl radical of 1-6 carbon atoms, of a monobasic acid (e.g. formic, acetic, propionic and butyric) or of a polybasic acid (e.g. lactic or tartaric) or in some disubstituted glycerides may be hydrogen. Mono- or diacetylated glycerides are preferred. Specified mono-acetylated glycerides, and the acids from which they are derived, are as follows:-Aceto myristolein (9-tetradecenoic); aceto palmitolein (9-hexadecenoic); aceto-olein (9-octadecenoic); acetogadolein (from a mixture of 11- and 12-octadecenoic, and 9- and 11- eicosenoic acids); acetocetolenin (11- decosenoic); acetoerucicin (13-docosenoic); acetoselacholein (15-tetracosenoic); acetoximenin (17-hexacosenoic); acetolumequein (21-triacontenoic). A specified diacetylated glyceride is 2,3 diacetylmonooleate. Specified cellulose esters include acetobutyrate, which is preferred, especially acetobutyrate having an acetyl content of 10-25% and a butyryl content of 25-45%, acetopropionate, acetoisobutyrate, acetoamylate, and acetostearate. Desirably the cellulose ester content of the composition is from 15-50%, especially 20-40% of the total weight. Conventional additives, e.g. antioxidants, dyes, compatible oils, and other strengthening agents, may also be present. The composition may be made by dissolving the cellulose ester in the liquified glyceride. Articles may be transparently coated by covering them with the liquified composition, e.g. by spraying or projection especially by passing the article through a falling film of the liquified composition and then cooling the coated article to a temperature at which the coating solidifies. The coatings are especially useful for preserving foodstuffs, but may also be used for the protection of wood, rubber or metal from air, moisture and dirt.ALSO:A transparent coating composition comprises 40-85% by weight of a glyceride selected from the group consisting of:-(a) glycerides of the formula where R1 and R2 are selected from the group consisting of hydrogen and the acyl radicals of aliphatic monobasic and polybasic acids of from one to six carbon atoms, not more than one of R1 and R2 being hydrogen, and R3 is the acyl radical of an aliphatic, long-chain fatty acid having one unsaturated double bond and a chain length of from 10-30 carbon atoms, and (b) mixtures of such glycerides in which the average unsaturated double bond content of the long chain fatty acids is from 0,5 to 1,5; and from 60-15% by weight of a cellulose ester component having a hydroxyl content of from 0,5-2,5%, an acetyl content of from 6 to 32%, and from 15-50% of an aliphatic acyl radical of from 3-18 carbon atoms. R1 may be an acyl radical of 1-6 carbon atoms, of a monobasic acid (e.g. formic, acetic, propionic and butyric) or of a polybasic acid (e.g. lactic or tartaric) or in some disubstituted glycerides may be hydrogen. Mono-or di-acetylated glycerides are preferred. Specified mono-acetylated glycerides, and the acids from which they are derived, are as follows:-Aceto myristolein (9-tetradecenoic); aceto palmitolein (9-hexadecenoic); aceto-olein (9-octadecenoic); acetogadolein (from a mixture of 11- and 12-octadecenoic, and 9- and 11-eicosenoic acids); acetocetolenin (11-decosenoic); acetoerucicin (13-docosenoic); acetoselacholein (15tetracosenoic); acetoximenin (17-hexacosenoic); acetolumequein (21-triacontenoic). A specified diacetylated glyceride is 2,3 diacetylmono-oleate. Specified cellulose esters include acetobutyrate, which is preferred, especially acetobutyrate having an acetyl content of 10-25% and a butyryl content of 25-45%, acetopropionate, acetoisobutyrate, aceto-amylate, and acetostearate. Desirably the cellulose ester content of the composition is from 15-50%, especially 20-40% of the total weight. Conventional additives, e.g. antioxidants, dyes, compatible oils, and other strengthening agents, may also be present. The composition may be made by dissolving the cellulose ester in the liquefied glyceride. Films made from the composition have a bursting strength of at least 300 gm./sq. cm., at a film thickness of 0,32/sB0,07 mm., are flexible, pliable and substantially 100% transparent at temperatures as low as -20 DEG C., and have a specific permeability, for film of 1 mm. thickness, of less than 2,0 mgm. water/sq. cm./24 hours at 4 DEG C. Articles may be transparently coated by covering them with the liquefied composition, e.g. by spraying or projection, especially by passing the article through a falling film of the liquefied composition and then cooling the coated article to a temperature at which the coating solidifies. The coatings are especially useful for preserving foodstuffs, but may also be used for the protection of wood, rubber or metal from air, moisture and dirt.ALSO:Foodstuffs may be preserved, and wood and rubber protected from air, moisture and dirt, by coating with a transparent coating composition comprising 40-85% by weight of a glyceride selected from the group consisting of: (a) glycerides of the formula where R1 and R2 are selected from the group consisting of hydrogen and the acyl radicals of aliphatic monobasic and polybasic acids of from one to six carbon atoms, not more than one of R1 and R2 being hydrogen, and R3 is the acyl radical of an aliphatic, long-chain fatty acid having one unsaturated double bond and a chain length of from 10-30 carbon atoms, and (b) mixtures of such glycerides in which the average unsaturated double bond content of the long chain fatty acids is from 0.5 to 1.5 and from 60-15% by weight of a cellulose ester component having a hydroxyl content of from 0.5-2.5%, an acetyl content of from 6 to 32%, and from 15-50% of an aliphatic acyl radical of from 3-18 carbon atoms. R1 may be an acyl radical of 1-6 carbon atoms, of a monobasic acid (e.g. formic, acetic, propionic and butyric) or of a polybasic acid (e.g. lactic or tartaric), or in some disubstituted glycerides may be hydrogen. Mono- or di-acetylated glycerides are preferred. Specified mono-acetylated glycerides, and the acids from which they are derived, are as follows: Aceto myristolein (9-tetradecenoic); aceto palmitolein (9-hexadecenoic); aceto - olein (9 - octadecenoic); acetogadolein (from a mixture of 11- and 12-octadecenoic, and 9- and 11-eicosenoic acids); acetocetolenin (11-deconenoic); acetoerucicin (13-docosenoic); acetoselacholein (15-tetracosenoic); acetoximenin (17-hexacosenoic); acetolumequein (21-triacontenoic). A specified diacetylated glyceride is 2,3-diacetylmono-oleate. Specified cellulose esters include acetobutyrate, which is preferred, especially acetobutyrate having an acetyl content of 10-25% and a butyryl content of 25-45%, acetopropionate, acetoisobutyrate, aceto amylate, and aceto-stearate. Desirably the cellulose ester content of the composition is from 15-50%, especially 20-40% of the total weight. Conventional additives, e.g. antioxidants, dyes, compatible oils, and other strengthening agents, may also be present. The composition may be made by dissolving the cellulose ester in the liquefied glyceride. Films made from the composition have a bursting strength of at least 300 gm./sq. cm., at a film thickness of 0.32/sB0.07 mm., are flexible, pliable and substantially 100% transparent at temperatures as low as -20 DEG C., and have a specific permeability, for a film of 1 mm. thickness, of less than 2.0 mgm. water/sq. cm./24 hours at 4 DEG C. Articles may be transparently coated by covering them with the liquefied composition, e.g. by spraying or projection, especially by passing the article through a falling film of the liquefied composition and then cooling the coated article to a temperature at which the coating solidifies.