Patent GB-890149-A (GB)
Title: Soft, non-woven fibrous product and process for preparing the same
IPC: D04H1/64
Filed: 1960-05-05
Abstract: A polymeric binder comprises (i) a heat cured product of a water-insoluble copolymer having units consisting essentially of about 4 to 6% by weight of units from methacrylamide, about 5 to 15% by weight of units of vinyl alcohol, about 1 to 45% by weight of a vinyl ester such as vinyl acetate and about 46 to 90% by weight of an ester of acrylic or methacrylic acid with an alkanol containing 4 to 18 carbon atoms.  Said copolymer may be used as the sole binder agent or in conjunction with (ii) a water-dispersible thermosetting resin condensate such as (a) an aminoplast or (b) a polyepoxide.  Suitable acrylic and methacrylic esters are butyl acrylate, butyl methacrylate, 2 ethyl hexyl acrylate and methacrylate, dodecyl acrylate, hexadecyl acrylate and octadecyl acrylate.  The monomers from which the polymers are prepared are so selected as to yield a copolymer having an apparent second order transition temperature not above 20 DEG C.  The polymers may be linear addition copolymers produced by conventional emulsion polymerization procedures; or they may be graft or block copolymers wherein one or more but not all of the monomers are first polymerized and then one or more other monomers are copolymerized with the first polymer obtained.  The linear addition copolymers may be obtained by first preparing a copolymer of methacrylamide, vinyl acetate and the ester of acrylic or methacrylic acid with an alkanol containing 4 to 18 carbon atoms followed by hydrolysis with vinyl alcohol.  Suitable emulsifiers are sodium lauryl sulphate and t-octyl-phenoxy-polyethoxyethanols containing from 10 to 50 oxyethylene units per molecule.  These may be used in conjunction with a free-radical initiator such as azodiisobutyronitrile, t-butyl hydroperoxide and ammonium or potassium persulphates. The copolymers may comprise small amounts of other monomers such as styrene, vinyl toluene, vinyl chloride, acrylonitrile, or methacrylonitrile.  Aminoplast condensates (ii) (a) which may be employed in conjunction with the foregoing binders are low molecular weight or monomeric reaction products of formaldehyde with urea, thiourea, biuret or other homologues or derivatives thereof such as N,N-ethylene-urea, N,N1 ethylene urea, N,N1-dimethylurea, N,N1 diethyl urea, N,N1-dimethoxymethyl urea, N,N-dimethoxymethyl urea, N,N1-diethoxyethylurea, tetra-methoxymethyl urea, and tetra-ethoxyethylurea.  Similar reaction products of formaldehyde with triazines, such as melamine and N,N1-dimethylmelamine may also be employed as well as alcohol-modified melamine-formaldehyde thermosetting resin condensates, e.g. of methyl and ethyl alcohols, e.g. dimethoxymethylmonomethylolmelamine.  The epoxy thermosetting resin-forming condensates (ii)(b) may be either water-soluble or self-dispersible in water.  The water-soluble types may be any of those formulas II, III and IV:-  <FORM:0890149/IV (a)/1> where x is a number having an average value of 1 to 3. p  <FORM:0890149/IV (a)/2> where y is a number having an average value of 2 to 4. <FORM:0890149/IV (a)/3> where m is a number having a value of 2 to 4 and z is a number having an average value of 1 to 5.  The water-insoluble but self-dispersible types include compounds of formula III above wherein u has an average value of 5 to 10, and also compounds of formula V:-  <FORM:0890149/IV (a)/4> where   is the p-phenylene group and p is a number having an average value of 1 to 3.  In the examples oxalic acid was added as an acidic catalyst. Use. Impregnating random fibres to form a non-woven fibrous product (see Group VIII).