GB998528A - Film-forming dispersions - Google Patents

Abstract

An aqueous dispersion cable of forming insoluble and infusible continuous films comprises (1) a water-insoluble emulsion copolymer of (A) 50 to 98% weight of a "rigid" monoethylenic monomer containing no group reactive with N-hydroxy- or -alkoxy methyl groups, (B) 2 to 20% of a mono-ethylenic monomer which does contain such a group and optionally (C) 0 to 45% of a "non-rigid" monomer free from such groups and (2) at least 10% by weight of (1) of a C2- 4 alkoxy-methylated melamine having an average of 5 to 6 alkoxy-methyl groups (2) functions as both a plasticizer and cross-linking agent for (1) A literature reference is given to define "rigid" and "non-rigid" Specified monomers are: (A) C1- 5 alkyl and benzyl methacrylates, t-butyl and t-amyl acrylates, acrylonitrile, methacrylonitrile, styrene, p-methyl styrene, chlorostyrene and vinyl chloride; (B) acrylic, alkacrylic and haloacrylic acids, their amides, and their hydroxyalkyl esters; and (C) C1- 12 non-tertiary alkyl acrylates The dispersion may also contain acid curing catalyst, pigments, dyes, fillers, powdered or flaked metals and U V light absorbers; in Example (38), titanium dioxide (as pigment), a sodium salt of a polymeric carboxylic acid (as dispersing agent), an alkyl aryl polyether alcohol (as wetting agent), lanolin (anti-foament) and hydroxyethyl cellulose (thickener) are included Applications - The dispersions may be used to coat various substrates, e g metals, wood, glass and asbestos cement building sheets They can provide a clear top film on decorative laminates, e g of phenolic resin-bonded paper sheets overlaid with a melamine-formaldehyde resin impregnated cellulosic print In examples, the dispersion is cast on glass or steel panels and baked, with previous air-drying when the substrate is glass In example (49), the dispersion is brush-coated on one side of alpha-cellulose overlay paper, the impregnated paper being dried and used, coated side out, as the top sheet in the laminate mentioned above.ALSO:An aqueous dispersion capable of forming insoluble and infusible continuous films comprises (1) a water insoluble emulsion copolymer of (A) 50-98% weight of a "rigid" monoethylenic monomer containing no group reactive with N-hydroxy- or -alkoxymethyl groups, (B) 2-20% of a mono-ethylenic monomer which does contain such a group and optionally (C) 0-45% of a "non-rigid" monomer free from such groups and (2) at least 10% by weight of (1) of a C2-4 alkoxymethylated melamine having an average of 5-6 alkoxymethyl groups. (2) functions as both a plasticizer and cross-linking agent for (1). A literature reference is given to define "rigid" and "non-rigid". Specified monomers are: (A) C1-5 alkyl and benzyl methacrylates, t-butyl and t-amyl acrylates, acrylonitrile, methacrylonitrile, styrene, p-methyl styrene, chlorostyrene and vinyl chloride; (B) acrylic, alkacrylic and haloacrylic acids, their amides, and their hydroxyalkyl esters; and (C) C1-12 non-tertiary alkyl acrylates. The dispersion may also contain acid curing catalyst, pigments, dyes, fillers, powdered or flaked metals and U-V light absorbers; in Example 38 titanium dioxide (as pigment), a sodium salt of a polymeric carboxylic acid (as dispersing agent), an alkyl aryl polyether alcohol (as wetting agent), lanolin (anti foamant), and hydroxyethyl cellulose (thickener) are included. Applications. The dispersions may be used to coat various substrates, e.g. metals, wood, glass and asbestos cement building sheets. They can provide a clear top film on decorative laminates, e.g. of phenolic resin bonded paper sheets overlaid with a melamine-formaldehyde resin impregnated cellulosic print. In examples, the dispersion is cast on glass or steel panels and baked, with previous air-drying when the substrate is glass. In Example 49 the dispersion is brush-coated on one side of alpha-cellulose overlay paper, the imregnated paper being dried and used, coated side out, as the top sheet in the laminate mentioned above.