Patent GB-578484-A (GB)
Title: Manufacture of improved alkyd resin coating compositions
IPC: C09D167/08
Filed: 1944-03-03
Abstract: Organic solvent-soluble polysilicic acid esters are incorporated into alkyd resin coating compositions.  Preferably the alkyd resin contains 35-65 per cent fatty oils (e.g. chinawood, cottonseed, castor, linseed or soyabean) and 65-35 per cent polyhydric alcohol-polycarboxylic acid ester, e.g. glyceryl phthalate.  The resin may contain excess polyhydric alcohol, e.g. glycerol.  The ratio of C atoms to Si atoms in the polysilicic acid ester is preferably greater than 1 : 1, and the ratio of silicic acid ester groups to silicon atoms is greater than 1 : 10. Preferably the esters are hydrocarbon soluble.  A suitable acid for the alkyd resins is oxalic, succinic, glutaric, adipic, pimelic, sebacic, hexamethylene dicarboxylic, 2-phenyl glutaric, maleic, phthalic, isophthalic, terephthalic, acetylene dicarboxylic, itaconic, malic, citric, camphoric or diphenic or an anhydride thereof, and a suitable alcohol is ethylene glycol, propylene glycol, hexamethylene glycol, decamethylene glycol, diethylene glycol, pinacol, glycerol, 1 : 1 : 1-trimethylpropane, erythritol, pentaerythritol or mannitol.  The alkyd resins may be modified in known manner with fatty oils, monobasic acids, including resin acids or drying oil acids and/or with monohydric alcohols or with amines, including amino acids or amino alcohols. Preparation of the resin should not be carried beyond the point of solubility in organic solvents.  The polysilicic acid ester is derived from an alcohol which preferably boils below 200 DEG C. Preferably the polysilicic acid esters contain some unesterified silicic acid hydroxyl groups.  The molecular weight of the ester may vary from that of an ester containing only two silicon atoms to that of an ester whose molecules are of colloidal dimensions and whose sols approach the gel state.  Preferably the compositions contain 5-35 per cent by weight of SiO2 based on the alkyd resin.  Suitable solvents for the compositions are xylene, benzene, toluene, high-boiling aliphatic, aromatic or naphthenic hydrocarbons, dioxane, and alcohols such as the butanols.  Films of the coating compositions may be air-dried or baked preferably at 100-150 DEG  C.  Pigments, metallic driers, dyes, fillers, waxes, inhibitors, plasticisers, thinners, drying oils, natural resins, cellulose esters, chlorinated rubber, phenol-formaldehyde or urea-formaldehyde resins may be added in the usual manner.  Examples describe: (1) partial esterification by dissolving in methanol of a polysilicic acid complex prepared by addition to aqueous sodium silicate of sulphuric acid, diethyl ether of ethylene glycol and sodium chloride.  This solution is mixed with a xylene-butanol solution of a castor oil (55 per cent) modified glyceryl phthalate to give 25 per cent SiO2 based on the alkyd resin. (2) Tributyl phosphate and sodium chloride added to an acidified sodium silicate solution and the upper tributyl phosphate layer containing the partial n-butyl ester of polysilicic acid is separated, dried and rinsed with xylene-butanol solution of castor oil modified alkyd resin to give compositions having 10, 20 30 and 50 per cent SiO2 based on alkyd resin.  (3) The tributyl phosphate solution of Ex. (2) is diluted with methanol and benzene and the methanol solution of partially esterified polysilicic acids separated and dissolved in butanol to lower the SiO2 concentration to 10.9 per cent. The butanol solution is mixed with a xylene solution of an alkyd resin in varying proportions as in Ex. (2).  (4) Similar to Ex. (3) using a castor oil (45 per cent) modified alkyd resin.  (5) Similar to Ex. (2) using a linseed oil modified alkyd resin.  (6) Similar to Ex. 3 using a linseed oil modified alkyd.  (7) Similar to Ex. (3) using a linseedchinawood oil modified alkyd resin. (8) Similar to Ex. (4) with addition of titanium dioxide to the composition, and a high SiO2 concentration in the butanol solution of polysilicic acid esters.  (9) A solution in xylene and butanol of a hydrogenated coconut oil (35 per cent) modified glyceryl phthalate prepared with excess glycerol is ground with titanium dioxide and high flash naphtha and the product mixed with more alkyd resin and solvents and with a butyl polysilicic acid ester solution prepared by adding toluene and a little sulphuric acid to a butanol solution, distilling off water, toluene and some butanol and adding high solvency petroleum hydrocarbons to adjust the SiO2 concentration to 20 per cent.  (10) The polysilicic acid ester solution of Ex. 9 is mixed with a xylene solution or a soyabean oil (40 per cent), modified alkyd prepared with excess glycerol.  (11) A solution of a soyabean oil modified alkyd in a mixture of petroleum and turpentine is ground with titanim dioxide, zinc oxide and petroleum and the product mixed with a butanol solution of butyl acid polysilicate, alkyd resin, xylene and butanol to give an enamel.  (12) A solution of polysilicate prepared as in Ex. (9) is mixed with a xylene high flash naphtha solution of a dehydrated castor oil (43 per cent) modified alkyd prepared with excess glycerol.  (13) Similar to (12) the xylene being omitted and Prussian blue added as a pigment.  (14) A solution of polysilicate prepared as in Ex. (9) using phosphoric acid instead of sulphuric acid is mixed with cobalt naphthenate drier and a xylene solution of linseed oil (52 per cent) glyceryl phthalate and prepared with excess glycerol. Four other similar examples are given employing an ethanol solution of ethyl acid polysilicate prepared from tetraethyl silicate by adding acid, water and absolute ethanol.  Films are prepared from the composition of the examples. They may be baked and are hard, glossy and tackfree.