US2071523A - Preparation of artificial resin compression mixtures - Google Patents

Description

Patented Feb. 23, 1937 UNITED STATES PATENT PREPARATION OF ARTIFICIAL RESm OFFICE COM- 2 Claims.

It is known to prepare artificial resin compression mixtures, i. e. intimate mixtures of artificial resins, particularly soluble and fusible condensation products of phenols and formaldehyde, capable of being hardened, and filling substances, particularly wood powder, by intimately mixing or kneading resols, either in liquid or finely powdered condition, or in the form of an alcoholic solution, with filling substances.

In the solvent-process the solvents are removed by heating and the solid mass compressed in a granulated or powdered form in known manner. Working with solvents has the disadvantage that these solvents adhereextremely fast to the mix-' ture and can only be expelled by long heating. This long heating, however, reduces the flowing properties of the finished compression mixtures to an extraordinary degree. On the other hand if this long heating is omitted the material, owing to'tho retention of the solvent in the compression mixture, can only be compressed with great difliculty, since vapours are given off and consequently blisters form and it is therefore impossible to obtain high value compressed articles. The mixing process on rollers, on the other hand, has the disadvantage that, on mixing the material together, a further condensation of the resin also takes place at the same time, whereby it becomes extremely difiicult to hit the exact point when the product is homogeneously mixed and suflicient condensation has taken place. In this case also it is extremely diflicult to obtain uniform compression mixtures having 'the' desired flowing properties and permanence of compression.

According to this invention it has been found that compression mixtures, which are precondensed to any desired degree and are also completely homogeneously mixed, can be prepared without difficulty by bringing together finely powdered, suitably precondensed resin and suit,- able quantities of finely powdered filling material, if desired with the addition of pigments and agents for preventing'adhesionto the matrices, intimately mixing the ingredients together in a suitable apparatusfor example a mill, and thereafter subjecting the mixture for a short time at a high temperature to a high compression pressure, after which the pressure is rapidly released and the temperature lowered. This treatment has the purpose and effect of bringing the resin, owing to the high temperature, into a liquidform and at the same time forcing the resin into the finest pores of the filling material owing to the high pressure produced. This treatment can, for

In Germany March 27, 1930 example, becarried out by spreading out the mixture in a thin layer on a plate, thereafter subjecting the mixture to a high pressure with the aid of a second plate, heating for a short time and then rapidly cooling down the mixture, whilst releasing the pressure. The process may also be advantageously carried out by forcing the above described mixture through nozzles heated to high temperatures. Uniform mixing and impregnation of the resin and the filling substance thereby takes place in the nozzle.

The conditions, according to which this treatment takes place, must be so chosen that fusion of the resin takes place in the entire layer whilst the outer layers, by employing suitable temperatures, are prevented from passing over into the final condition, so that the material after impregnation can still be compressed in any desired manner.

As filling materials there may be employed wood powder, fibrous substances of every kind, mineral filling substances, such as asbestos, talc, lithopone, magnesia, etc. I

are intimately mixed ina mill and the mixture rapidly forced through narrow nozzles of any desired shape and of suitable length heated to about 200 C. After cooling the mixture may, if

desired, be powdered. y

What I claim is:

1. A process for preparing a consolidated com-' pression mixture which is capable of pressmouldinginto shapes and hardening, and is of v uniform quality and comprises an artificial resin in resol form homogeneously mixed with and impregnating a porous solid filling material, which comprises bringing together finely powdered precondensed resin in resol form with finely powdered porous filling materialin the absence of resin solvent and thereby forming an intimate dry powdery mixture, subjecting the mixture for a short'time to a high compression pressure at a high temperature andthereby uniformly liquefying the rennin the presence of the filling material so that the liquefied resin under said pressure permeates and impregnates the pores of the filler, and rapidly cooling and releasing the presdry powdery mixture, forcing the mixture uniformly and rapidly under high pressure through a restricted orifice while subjecting it to an elevated temperature for uniformly liquefying the resin in the presence of the filling material so that the liquefied resin under said pressure permeates and impregnates the pores of the filler, and rapidly cooling and effecting the escape of the mixture from the pressure and temperature existing at the orifice before a substantial conver- 19 sion and hardening of the resol has occurred.

' RICHARD HESSEN.