Acrylic resin-impregnated bodies formed of expanded graphite, process for producing such bodies and sealing elements, fuel cell components and heat-conducting elements formed of the bodies

Abstract

Bodies made of expanded graphite are impregnated with low-viscosity, solvent-free, storage-stable, polymerizing acrylic resins up to resin contents of 50% by weight. A primary product made of expanded graphite has an open pore system, with a particularly preferred range of bulk densities of from 0.5 to 1.3 g / cm.sup.3 and with an ash value of not more than 4% by weight. Such bodies can also contain a proportion of additives. The impregnated, shaped and rapidly curable graphite bodies are employed as sealing elements, as components in fuel cells or as heat-conducting elements. A process for producing the bodies is also provided.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a synthetic resin-impregnated body made of expanded or at least partially recompressed expanded graphite, a process for producing such a body and sealing elements, fuel cell components and heat-conducting elements formed of the bodies. In this contest, the phrase "synthetic resin-impregnated body" is understood to mean a body made of expanded graphite which is impregnated by synthetic resin.

[0003] Material composites of graphite and plastics are widely used in many technical applications. For example, particles of electrographite are processed with fluoroplastics into highly corrosion-resistant components for the construction of chemical apparatus, but they are comparatively expensive due to the costs of the fluoroplastics and the processing technique required. A subject which in terms of content is even closer to the present application is set out in U.S. Pat. No. 4,265,952: expanded graphite...

Examples

example 2

[0058] The resin system that was used was the same as the resin system in Example 1. The primary product had a thickness of 2.7 mm and a density of 0.65 g / cm.sup.3 and the ash value of the graphite was less than 0.15% by weight. After an impregnating period of one hour at room temperature, the now impregnated plate was taken out of the resin bath and weighed after the resin adhering to the surface had been wiped off. The proportion of resin which was determined was 20% by weight. The impregnated plate was placed in a pressing die preheated to 1500.degree. C. The die, which was furnished with an anti-stick coating, was closed and the impregnated graphite was pressed into the mold, in the course of which a further compression of the composite material took place. After five minutes under the effect of pressing force and temperature, the die was opened and the cured shaped body was removed. The shaped body was free from cracks and blisters and the surface showed no resin film visible t...

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a synthetic resin-impregnated body made of expanded or at least partially recompressed expanded graphite, a process for producing such a body and sealing elements, fuel cell components and heat-conducting elements formed of the bodies. In this contest, the phrase "synthetic resin-impregnated body" is understood to mean a body made of expanded graphite which is impregnated by synthetic resin.

[0003] Material composites of graphite and plastics are widely used in many technical applications. For example, particles of electrographite are processed with fluoroplastics into highly corrosion-resistant components for the construction of chemical apparatus, but they are comparatively expensive due to the costs of the fluoroplastics and the processing technique required. A subject which in terms of content is even closer to the present application is set out in U.S. Pat. No. 4,265,952: expanded graphite...

Examples

example 2

[0058] The resin system that was used was the same as the resin system in Example 1. The primary product had a thickness of 2.7 mm and a density of 0.65 g / cm.sup.3 and the ash value of the graphite was less than 0.15% by weight. After an impregnating period of one hour at room temperature, the now impregnated plate was taken out of the resin bath and weighed after the resin adhering to the surface had been wiped off. The proportion of resin which was determined was 20% by weight. The impregnated plate was placed in a pressing die preheated to 1500.degree. C. The die, which was furnished with an anti-stick coating, was closed and the impregnated graphite was pressed into the mold, in the course of which a further compression of the composite material took place. After five minutes under the effect of pressing force and temperature, the die was opened and the cured shaped body was removed. The shaped body was free from cracks and blisters and the surface showed no resin film visible t...