Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-12-18
2002-03-26
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S588000, C525S431000, C525S436000, C525S474000, C525S479000
Reexamination Certificate
active
06362279
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
FIELD OF THE INVENTION
This invention relates to fire retardants for plastics particularly preceramic additives as fire retardants for plastics and fire retardant blends of such additives and plastics.
BACKGROUND OF THE INVENTION
Current fire retardants have a number of problems depending on the system. Halogen based fire retardants (which may produce toxic and corrosive combustion products) and phosphorus based fire retardants increase the amount of carbon monoxide and smoke during combustion (by five to ten times), hydrates (e.g. ATH, aluminum trihydrate) which decompose by an endothermic process to produce water, must be used at such high loadings that (40-70% wt) the physical properties of the base polymer are excessively compromised. New fire retardants are needed that do not have these shortcomings. This is especially important for US companies trying to sell products in Europe, where a negative public opinion exists towards halogen base fire retardants, and a new European environmental law, the “eco-labeling” law, has passed which requires a label on all products that describes the materials used in the product. These issues are forcing companies to look for new, environmentally acceptable fire retardants for their fire retardant (FR) polymer products.
Accordingly there is need and market for fire retardants for plastics including polymers, which overcome the above prior art shortcomings.
There have now been discovered FR additives for polymers and FR blends of additives and polymers which are effective as such FRs and are environmentally suitable or safe.
SUMMARY OF THE INVENTION
Broadly the present invention provides an environmentally friendly (eco) FR for plastics comprising preceramic polymers.
The invention also includes combining such preceramic polymers with plastics as additives and in blends therewith to form eco FR materials.
Such preceramic polymers can be present in the blend in the amount of 1-80 wt% as discussed below.
The invention also provides a method for enhancing the fire resistivity of plastics by adding at least one preceramic polymer to at least one organic plastic to reduce the flammability thereof and form a polymer-plastic blend, wherein the preceramic polymer is selected from the group of polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins and polyhedral oligomeric silsesquioxane (POSS) monomers, polymers and copolymers.
Definitions:
By “preceramic polymer” as used herein, is meant an oligomeric or polymeric material that converts into a ceramic (inorganic char,) when heated above its decomposition point. Listed below are several examples of different types of preceramic oligomers and polymers.
By “oligomer” as used herein, is meant low molecular weight polymer chains that are often unentangled and which do not show the same level of desirable mechanical properties as higher molecular weight chains of the same polymer.
By “engineering polymer” as used herein, is meant a thermoset plastic or thermoplastic that maintains its dimensional stability and most of its mechanical properties between −20° C. to 200° C. Generically these resins include: acetals, polyamides (nylons), polyimides, polyetherimides, polyesters, polycarbonates, polyethers, polysulfides, polysulfones and blends or alloys of them.
By “commodity polymer” as used herein, is meant a thermoplastic or thermoset plastic that maintains most of its mechanical properties between 0 to 100° C. Typically such polymers are called commodity plastics because they are also produced on a large scale industrially and hence often cost less per pound than the above mentioned engineering polymers. Examples include: styrenics, acrylics, polyolefins, polyurethanes, polyvinylchlorides and related chlorinated olefins, acrylonitrile-butadiene-styrene (ABS) and poly(ethylene terephthalate).
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Gilman Jeffrey W.
Lichtenhan Joseph D.
Hoke Veronica P.
Stover Thomas C.
The United States of America as represented by the Secretary of
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