Patent GB-401689-A (GB)
Title: Process for the production of covering layers from carbamide aldehyde condensation products
IPC: B05D3/02
Filed: 1932-05-12
Abstract: Covering layers of carbamide-aldehyde condensation products are produced on materials of various kinds by coating or coating and impregnating with a suspension of the condensation product, the coating produced being dried and hardened by pressure and heat. Included in the materials or supports to which the coating may be applied are paper, cardboard, fabrics formed of fibrous materials, wood, veneers, leather, ceramic masses, asbestos cement, natural or artificial stones, condensation products, viscose, cellulose derivatives, &c.  The liquid phase is constituted by a solution in water or an organic solvent of a carbamide-aldehyde condensation product.  As the solid phase, a powdered carbamide-aldehyde condensation product may be employed in such a condition that it is not dissolved but only slightly swollen by the liquid phase. Fillers, preferably fibrous, luminous and other colouring matters and plasticizers may be incorporated with the solid phase together with bronze powder or metal filings.  When the suspension is allowed to dry at ordinary temperatures, a compact hard layer is obtained on the support. The suspension may vary from a dough-like consistency to a thin liquid and it may be applied to the support by spraying, painting, rolling or immersion.  With a smooth support, e.g. a cellulose derivative, the suspending liquid should be one which will act as a swelling agent for the support.  Application of the suspension to paper of fabric may be effected by passing the support thereover so that one side only is in contact with the suspension, or by filtering the suspension through the support with the aid, if necessary, of reduced pressure.  Any of the sheets so formed may be attached together or to sheets of other condensation products by superposition and moulding.  Urea condensation products or thiourea or its derivatives may be employed for the preparation of the condensation products in addition to urea, and other aldehydes may be used in place of formaldehyde.  In an example, 300 parts by weight of urea and 76 of thiourea are dissolved in 1000 of formaldehyde, the whole neutralized by active carbon, filtered, and the filtrate heated under pressure at 98 DEG  C. With 20 parts of the solution so obtained are mixed 1 part of thiourea and 5 of cellulose, the mass dried, ground with lithopone, and kneaded with a mixture of the solution first obtained and thiourea to produce a paste which can be applied by spreading or rolling to an asbestos plate whereon it is secured by drying and is then heated under pressure.  Various colouring and filling matters may be added during formation.  In a second example, urea is dissolved in formaldehyde in the molecular ratio of 1 to 2, 15 parts of the solution being heated in an autoclave at 98 DEG  C., mixed with 1 part of thiourea and made into a suspension with a known carbamide condensation product.  One side of a web of absorbent paper is drawn in contact with the suspension and passed through a drying apparatus.  The hardened, dried material may be broken into sheets, assembled and united by heat and pressure. In a third example, a solution of dimethylol urea in methanol is obtained as described in Specification 261,029, [Class 95, Paints &c.], mixed with a known carbamide-aldehyde moulding powder and applied to a printed material, dried and combined by pressure with a plate of amine-formaldehyde condensation product.  In another example, 240 parts of urea and 152 parts of thiourea are dissolved in 1000 parts of formaldehyde and heated at 98 DEG  C. in an autoclave, 75 parts of thiourea are added and the whole evaporated to dryness and ground, the powder being suspended in a 5 per cent aqueous solution of a carbamide-aldehyde condensation product and painted on a veneer which is dried, and pressed at a raised temperature. Other examples are furnished describing the use of solutions and suspensions so formed.  Specification 342,326, [Group IV], also is referred to.ALSO:Urea-aldehyde and thiourea-aldehyde condensation products are produced as covering layers on materials of various kinds by coating or coating and impregnating with a suspension of the condensation product, the coating produced being dried and hardened by pressure and heat.  The liquid phase is constituted by a solution in water or an organic solvent of a carbamide-aldehyde condensation product.  As the solid phase, a powdered carbamide-aldehyde condensation product may be employed in such a condition that it is not dissolved but only slightly swollen by the liquid phase. Fillers, preferably fibrous, luminous and other colouring matters and plasticisers may be incorporated with the solid phase together with bronze powder or metal filings.  When the suspension is allowed to dry at ordinary temperatures, a compact hard layer is obtained on the support.  In an example, 300 parts by weight of urea and 76 of thiourea are dissolved in 1000 of formaldehyde, the whole neutralised by active carbon, filtered and the filtrate heated under pressure at 98 DEG  C.  20 parts of the solution so obtained are mixed 1 part of thiourea and 5 of cellulose, the mass dried, ground with lithopone, and kneaded with a mixture of the solution first obtained and thiourea to produce a paste which can be applied by spreading or rolling to an asbestos plate whereon it is secured by drying and is then heated under pressure.  Various colouring and filling matters may be added during formation.  In a second example, urea is dissolved in formaldehyde in the molecular ratio of 1 to 2, 15 parts of the solution being heated in an autoclave at 98 DEG  C. mixed with 1 part of thiourea and made into a suspension with a known carbamide condensation product.  One side of a web of absorbent paper is drawn in contact with the suspension and passed through a drying apparatus. The hardened, dried material may be broken into sheets, assembled and united by heat and pressure.  In a third example, a solution of dimethylol urea in methanol is obtained as described in Specification 261,029, [Class 2 (iii), Dyes, &c.] mixed with a known carbamide-aldehyde moulding powder and applied to a printed material, dried and combined by pressure with a plate of amineformaldehyde condensation product.  In another example, 240 parts of urea and 152 parts of thiourea are dissolved in 1000 parts of formaldehyde and heated at 98 DEG  C. in an autoclave, 75 parts of thiourea are added and the whole evaporated to dryness and ground, the powder being suspended in a 5 per cent. aqueous solution of a carbamide-aldehyde condensation product and painted on a veneer which is dried and pressed at a raised temperature. Other examples are furnished describing the use of solutions and suspension so formed. Specification 342,326 also is referred to.ALSO:Covering layers of carbamide-aldehyde condensation products are produced on materials of various kinds by coating, or coating and impregnating, with a suspension of the condensation product, the coating produced being dried and hardened by pressure and heat.  Included in the materials or supports to which the coating may be applied are paper, cardboard, fabrics formed of fibrous materials, wood, veneers, leather, ceramic masses, asbestos cement, natural or artificial stones, condensation products, viscose, cellulose derivatives &c.  The liquid phase is constituted by a solution in water or an organic solvent of a carbamide-aldehyde condensation product.  As the solid phase, a powdered carbamide-aldehyde condensation product may be employed in such a condition that it is not dissolved but only slightly swollen by the liquid phase.  Fillers, preferably fibrous, luminous and other colouring matters and plasticisers may be incorporated with the solid phase together with bronze powder or metal filings.  When the suspension is allowed to dry at ordinary temperatures, a compact hard layer is obtained on the support. The suspension may vary from a dough-like consistency to a thin liquid and it may be applied to the support by spraying, painting, rolling or immersion.  With a smooth support, e.g. a cellulose derivative, the suspending liquid should be one which will act as a swelling agent for the support.  Application of the suspension to paper or fabric may be effected by passing the support thereover so that one side only is in contact with the suspension, or by filtering the suspension through the support with the aid, if necessary, of reduced pressure.  Any of the sheets so formed may be attached together or to sheets of other condensation products by superposition and moulding.  Urea condensation products or thiourea or its derivatives may be employed for the preparation of the condensation products in addition to urea, and other aldehydes may be used in place of formaldehyde.  In an example, 300 parts by weight of urea and 76 of thiourea are dissolved in 1000 of formaldehyde the whole neutralised by active carbon filtered and the filtrate heated under pressure at 98 DEG  C. 20 parts of the solution so obtained are mixed 1 part of thiourea and 5 of cellulose the mass dried ground with lithopone and kneaded with a mixture of the solution first obtained and thiourea to produce a paste which can be applied by spreading or rolling to an asbestos plate whereon it is secured by drying and is then heated under pressure.  Various colouring and filling matters may be added during formation.  In a second example urea is dissolved in formaldehyde in the molecular ratio of 1 to 2 15 parts of the solution being heated in an autoclave at 98 DEG  C., mixed with 1 part of thiourea and made into a suspension with a known carbamide condensation product.  One side of a web of absorbent paper is drawn in contact with the suspension and passed through a drying apparatus.  The hardened, dried material may be broken into sheets, assembled and united by heat and pressure.  In a third examp