Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1989-03-13
1990-07-31
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
521 82, 521 92, 521 97, 521181, 521149, C09K 2114
Patent
active
049450158
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to intumescent material comprising expandible graphite in a polymeric binder.
In accordance with the present invention there is provided an intumescent material comprising expandible graphite in a polymeric binder.
The intumescent material may further comprise at least one constituent selected from fillers and reinforcing agents.
The intumescent material may be made by preparing a mixture of the expandible graphite, the polymeric binder and a liquid and causing or allowing the mixture to harden.
Normally the intumescent material is non-foamed or non-cellular i.e. free of pores or cells.
Accordingly to a first aspect of the invention, the binder is a flexible or elastomeric binder.
In the first aspect of the invention, the graphite is preferably present in an amount of 15 to 60% by weight based on the combined weight of the binder and graphite. Preferably the graphite is present in an amount of at least 20% by weight based on the combined weight of the binder and graphite. Preferably also the graphite is present in an amount not exceeding 55% by weight based on the combined weight of the binder and graphite.
Preferably, also in the first aspect of the invention, the binder and the graphite are present in a total amount of at least 70% by weight based on the weight of the intumescent material.
The intumescent material according to the first aspect of the invention may comprise a plasticizer. The amount of the plasticizer preferably does not exceed 15% by weight based on the weight of the intumescent material. A suitable plasticizer is dibutyl phthalate.
The intumescent material according to the first aspect of the invention may be made by preparing a mixture of the expandible graphite, the polymeric binder and water and causing or allowing the mixture to harden. Hardening may occur at least in part due to evaporation of water.
The mixture may be liquid or formulated as a dough moulding compound.
The flexible binder may be or comprise a polymer selected from vinyl acetate polymers, styrene polymers, vinyl chloride polymers, acrylic polymers, vinyl butyral polymers, melamine/urea/phenol formaldehyde resins, polyesters and phenolic resins.
Where the binder is an elastomeric binder, the intumescent material preferably comprises 40 to 70% by weight of the binder and 25 to 60% by weight of the expandible graphite based on the combined weight of the binder and graphite.
The intumescent material may be made by preparing a mixture of the expandible graphite and a liquid emulsion or dispersion of the elastomeric binder and causing or allowing the mixture to cure by coagulation or cross-linking of the elastomeric binder.
Suitable emulsions or dispersions of the elastomeric binder may comprise Neoprene latex 115 and Neoprene latex 671. These latices are marketed by Du Pont. Neoprene latex 115 is described as a chloroprene copolymer with carboxyl functionality of pH 7. Neoprene latex 671 is described as polychloroprene in anionic colloidal system, pH 12.5.
It may be advantageous to add one or more organic accelarators such as thiocarbanilide, diphenylguanidine or hexamethylenediamine to the emulsion or dispersion of the elastomer.
The elastomeric binder may be a rubber.
The elastormeric binder is preferably fire- or flame-resistant and/or self-extinguishing.
According to a second aspect of the invention, the binder is a thermosetting formaldehyde resin. Such a resin is normally rigid (i.e. substantially non-flexible and non-elastomeric).
The thermosetting binder may be, for example, melamine formaldehyde resin, urea formaldehyde resin, phenol formaldehyde resin, resorcinol formaldehyde resin or a mixture of two or more of these resins. Melamine formaldehyde resin is particularly preferred as the thermosetting binder because it provides an intumescent material which can intumesce smoothly and free of sputtering of graphite particles.
The thermosetting binder may incorporate a minor proportion of one or more of the flexible polymers referred to above in order to improve the flexural properties
REFERENCES:
patent: 4698369 (1987-10-01), Bell
patent: 4722945 (1988-02-01), Wood et al.
Malcolm-Brown Tessa
Milner Bruce A.
Southern Eric
Dixon International Limited
Foelak Morton
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