Process for the preparation of charged thermosetting compounds o

Details Process for the preparation of charged thermosetting compounds o Process for the preparation of charged thermosetting compounds o

1992-03-31

1993-08-24

Welsh, Maurice J.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

521107, 5211091, 521121, 521122, 521123, 521130, 524700, 524710, 524733, 524734, 524775, 524783, 524785, 524786, 524788, C08G 1814

Patent

active

052389693

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a process for preparation of filled heat-curable compounds of the polyurethane type by condensation reaction of their constituents in the presence of a pulverulent filler.
The invention also relates to the filled heat-curable compounds of the polyurethane type obtained according to the process.
The invention finally relates more particularly to the filled foamed heat-curable compounds of the polyurethane type obtained according to the process.


BACKGROUND OF THE INVENTION

For a long time specialist literature has described many heat-curable compounds filled with pulverulent inorganic materials of preferably pigment-like size and the processes for obtaining them, which concern both foamed and unfoamed filled heat-curable compounds, which in the first case are in the form of plastic masses containing fine gaseous inclusions.
The introduction of inorganic fillers (French patent 2,531,971) into the various heat-curable compounds of the polyurethane type is directed at various objectives in order to respond to demands of specialist or user industries, such as, for example, the motor vehicle, building, electronics, electrical domestic appliances or other, industries, for availability of nonmetallic products with specific characteristics such as lightness, rigidity, reduced shrinkage, decrease in the expansion coefficient, improvement in thermal shock resistance, improvement in sound insulation, sufficient flexural, tensile, compressive mechanical strength or other major physical characteristics.
Various fillers intended for heat-curable compounds of the polyurethane type are referred to in "European Plastics News" (1979, August, page 21) and "Modern Plastic International" (1982, April, page 42), such as calcium carbonate, talc, mica, aluminium trihydrate, silica, but also glass fibres, textile fibres or others. Thus, in the RIM (Reaction Injection Moulding) and RRIM (Reinforced Reaction Injection Moulding) processes fillers as diverse as glass fibres, ballotini, mica, wollastonite, talc and treated inorganic fibres are often used in order to increase the rigidity of the articles produced and to reduce their cost ("Plastic Technologic" 1978, November, page 13 and "Elastomerics", 1979, February, page 25).
Various processes are proposed for performing the introduction of fillers into heat-curable compounds, the essential preoccupation of which is to produce filled heat-curable compounds which have at least some of the specific characteristics referred to above.
In a first type of process the filler is introduced into one of the constituents of the polyurethane compound, generally the polyol. To stabilize the suspension thus prepared, that is to say to avoid sedimentation effects, the polyol is frequently subjected to grafting (DE OS 2,654,746, 2,714,291 and 2,739,620), with methacrylic acid or with another vinyl compound such as styrene, or else with isocyanate (DE OS 2,834,623). However, experimental results show that the suspension thus prepared does not escape either a considerable increase in its viscosity, which makes it difficult to handle, or a poor distribution of the filler within the heat-curable compound produced.
According to a second type of process, and to try and get rid of the disadvantages revealed in the first type, the filler is surface-treated before its introduction into one of the constituents of the desired heat-curable compound (the polyol), by means of a coating agent which is compatible with the constituents, a coating agent which is, for example, a C.sub.8 to C.sub.14 alcohol (FR 2,531,971). However, this type of process produces disadvantages which are substantially identical with those referred to earlier, since the user still finds an increase in the viscosity of the suspension of the filler in the polyol, attenuated to be sure, but still too high, which causes nonuniform dispersion of this filler in the heat-curable compound which is subsequently formed.
In another type of process, which is directed towards the production of unfoamed

REFERENCES:
Database Chemical Abstracts, vol. 108, No. 12, 1987, resume no. 187763q, (Columbus, Ohio, US), T. I. Chalykh et al.: "Sorption and diffusion of water vapor in filled polyurethanes and poly (vinyl chloride)", & Izv, Vyssh. Uchebn, Zaved., Khim., Khim. Trekhnol., 30 (12), 100-4.
Database Chemical Abstracts, (HOTE:STN), vol. 78, No. 12, 1972, resume no. 73184h; (Columbus, Ohio, US), &ES, A, 371150 (J. SHIH) 1 Apr. 1972.

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