Patent GB-774805-A (GB)
Title: Improvements in or relating to a process for producing a thermosetting resinous molding composition
IPC: B29B9/06
Filed: 1954-06-24
Abstract: A thermosetting resinous moulding composition is made by pulverizing thermosetting resinous material to a particle size within the range of 44-1410 microns, continuously introducing the pulverized material into a zone divided into a plurality of sub-zones maintained at different temperatures and wherein continuous densification of the material occurs, all of said temperatures being above 20 DEG  C. but below 150 DEG  C., continuously removing the densified material from the zone in an extruded form and continuously cutting into pellets and cooling said material to room temperature.  When starting with a dry resin, the resin (if desired, with a fibrous or non-fibrous filler, a dye, a pigment, a metallic powder, a mould lubricant or a curing catalyst is introduced into a continuous pulverizer.  When starting with a resinous syrup, the syrup (together if desired with any of the additions mentioned above) is, prior to pulverization, introduced into a mixer maintained at 100-160 DEG  F., and if desired under pressure and is then passed to a continuous dryer maintained at a temperature of 100-215 DEG  F. dry bulk and 80-140 DEG  F. wetbulk where the volatile content of the syrup is reduced to less than 15 per cent by weight.  In either case, the pulverized material is passed to an extruder wherein a plurality of heating zones are maintained, the temperatures in which may increase or decrease in the direction of motion or may first increase, then decrease and again increase.  Vacuum may be applied to a section of the extruder to remove volatiles.  The densified material may be extruded with or without a die and cut into pellets having a diameter and length ranging from 0.025-0.10 inches.  Cooling (e.g. in a water-cooled rotating cooler) may be effected before or after cutting the material into pellets.  The resin may be derived from an aldehyde and a phenol, an aminotriazine, an aminotriazole, a urea, a urea and an aminotriazine, an aminodiazine, a protein or a polyamide.  Also it may be shellac, a polymerizable unsaturated polyester or a mixture of such a polyester and a polymerizable compound containing a CH2=C< group.  The Specification lists many examples of specific resins, fillers, mould lubricants, dyes, pigments and curing catalysts.  In examples: (1) a mixture of melamine-formaldehyde resin, an aniline-formaldehyde resin modified by mono-m-p-cresyl glyceryl ether, alpha cellulose, magnesium oxide and cadmium red were ground and introduced into an extruder having zones heated to 20 DEG  C., 100 DEG  C. and 70 DEG  C., or 150 DEG  C., 100 DEG  C. and 20 DEG C.; (2) a mixture of melamine-formaldehyde resin, aniline - cresol - formaldehyde resin, anilineshellac-formaldehyde resin cotton flock, calcined asbestos and zinc stearate was ground and densified in an extruder having zones maintained at 20 DEG  C., 120 DEG  C., 45 DEG C. and 62 DEG  C.; (3) and (4) a mixture of melamine-formaldehyde resin, aniline-cresol-formaldehyde resin, wood flour, calcium stearate, cadmium red and magnesium oxide was ground and densified in an extruder having two zones maintained at 100 DEG  and 65 DEG  C., or three zones maintained at 20 DEG  C., 100 DEG  C. and 60 DEG  C.; (5) a mixture of a urea-formaldehyde resinous syrup, wood flour, barium sulphate and zinc palmitate was blended in a vessel maintained at 120-130 DEG  F., dried in a continuous dryer having a dry-bulk temperature of 160 DEG  C. and a wet-bulk temperature of 115 DEG  C., pulverized and passed to an extruder having zones at 20 DEG  C., 85 DEG  C. and 80 DEG  C.; (6) a mixture of urea-formaldehyde resinous syrup, alpha cellulose, tetrachlorophthalic anhydride, hexamethylene tetramine, zinc palmitate and barium sulphate was blended in a vessel maintained at 125 DEG  F., dried in a continuous dryer having a drybulk temperature of 160 DEG  F. and a wet-bulk temperature of 115 DEG  F., pulverized and passed to an extruder having zones at 20 DEG C., 120 DEG  C., 65 DEG  C. and 105 DEG  C.; (8) a mixture of an ethylene glycol - maleic anhydride polyester, diallyl phthalate, a urea-dicyandiamide-formaldehyde resin, cotton flock and clay was ground, benzoyl peroxide, ditertiary butyl paracresol and zinc stearate added and the mixture introduced into an extruder having zones at 20 DEG  C., 70 DEG  C., 65 DEG  C., 80 DEG  C. and 60 DEG C.; (9) a mixture of a phenol-formaldehyde novolak resin, hexamethylene tetramine, wood flour and zinc stearate was ground and then densified in an extruder with zones maintained at 20 DEG  C., 70 DEG  C., 95 DEG  C., 110 DEG  C., and 90 DEG  C.  In Examples (1)-(7) the extruder screws rotate at 40 or 60 r.p.m. and the material is extruded through a 2 inch die area having 119 or 300 holes each having a diameter of 0.072 inch, the material then being cut by rotating knife blades into pellets having length and diameter of 0.072 inch.  In Examples (8) and (9), the material was extruded through a 2 inch die area containing 104 holes, each having 0.122-0.144 inch tapered diameter, the material then being cut by rotating knife blades into pellets having a diameter and length of about 0.130 inch.ALSO:A thermosetting resinous moulding composition is made by pulverizing thermosetting resinous material to a particle size within the range of 44-1410 microns, continuously introducing the pulverized material into a zone divided into a plurality of sub-heating zones maintained at different temperatures and wherein continuous densification of the material occurs, all of said temperatures being above 20 DEG C. but below 150 DEG C., continuously removing the densified material from the zone in an extruded form and continuously cutting into pellets and cooling said material to room temperature.  When starting with a dry resin, the resin (together if desired with a fibrous or non-fibrous filler, a dye, a pigment, a metallic powder, a mould lubricant or a curing catalyst 1 is introduced into a continuous pulverizer.  When starting with a resinous syrup, the syrup (together if desired, with any of the additions mentioned above) is, prior to pulverization, introduced into a mixer maintained at 100 DEG -160 DEG F. and if desired under pressure and is then passed to a continuous dryer maintained at a temperature of 100 DEG -215 DEG F. dry-bulb and 80 DEG -140 DEG F. wet-bulb where the volatile content of the syrup is reduced to less than 15 per cent by weight.  In either case, the pulverized material is passed to an extruder wherein a plurality of heating zones are maintained, the temperature in which may increase or decrease in the direction of motion or may first increase, then decrease and again increase.  Vacuum may be applied to a section of the extruder to remove volatiles.  The densified material may be extruded with or without a die and cut into pellets having a diameter and length ranging from 0,025-0,10 inches.  Cooling (e.g. in a water-cooled rotating cooler) may be effected before or after cutting the material into pellets.  In examples (1)-(7) the extruder screws rotate at 40 or 60 r.p.m. and the densified material is extruded through a 2 inch die having 119 or 300 holes each having a diameter of 0,072 inches, the material then being cut by rotating knife blades into pellets having lengths and diameter of 0,072 inches.  In examples (8) and (9), the material was extruded through a 2 inch die area containing 104 holes each having 0,122-0,144 inch tapered diameter; the material then being cut by rotating knife blades into pellets having a diameter and length of about 0,130 inches.