Two-component intumescent flame retardant
AssigneeHoechst Celanese Corporation
InventorsRaymond W. Nalepa, Daniel J. Scharf
Life of this patent
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Abstract
An improved flame reardant polyolefin is disclosed which comprises a combination of ammoniumm polyphosphate; tris(2-hydroxyethyl) isocyanurate; and a selected silica in an amount from 0.5 percent to an amount equal to one-half the amount by weight of THEIC, wherein the silica meets defined surface arera, particle size and absorption criteria.
Claims13
A flame retardant polyolefin wherein the flame retarding portion of the polyolefin comprises ammonium polyphosphate, tris(2-hydroxyethyl) isocyanurate and a selected silica, wherein:
- a) the ammonium polyphosphate is a compound of formula (NH.sub.4 PO.sub.3).sub.n in which n is an integer from about 200 to about 1000 and has a particle size less that 45 microns;
- b) the total amount of ammonium polyphosphate and tris(2-hydroxyethyl) isocyanurate in the polyolefin is from about 20 percent to about 50 percent by weight;
- c) the ratio of ammonium polyphosphate to tris(2-hydroxyethyl) isocyanurate is from about 2:1 to about 6:1;
- and
- d) said selected silica is added in an amount of from 0.5 percent by weight to an amount equal to one-half the amount by weight of said tris(2-hydroxyethyl) isocyanurate and wherein said selected silica has a surface area of at least 450 m.sup.2 /gram, a particle size less than or equal to 4.5 microns, a tapped density of less than or equal to 80 grams/liter and a dibutyl phthalate absorption value of at least 330 percent.
A method for producing a flame retardant polyolefin comprising the steps of combining:
- a) a polyolefin selected from the group consisting of polyethylene, polypropylene, ethyl vinyl acetate copolymer, polybutylene, and ethylene, copolymers or terpolymers of said polyolefins, and blends of two or more of said polyolefins;
- and
- b) ammonium polyphosphate, tris(2-hydroxyethyl) isocyanurate and a selected silica, wherein:
- i) the ammonium polyphosphate is a compound of formula (NH.sub.4 PO.sub.3).sub.n in which n is an integer from about 200 to about 1000 and has a particle size less that 45 microns;
- ii) the total amount of ammonium polyphosphate and tris(2-hydroxyethyl) isocyanurate in the polyolefin is from about 20 percent to about 50 percent by weight;
- iii) the ratio of ammonium polyphosphate to tris(2-hydroxyethyl) isocyanurate is from about 2:1 to about 6:1;
- and
- iv) said selected silica is added in an amount of from 0.5 percent by weight to an amount equal to one-half the amount by weight of said tris(2-hydroxyethyl) isocyanurate and wherein said selected silica has a surface area of at least 450 m.sup.2 /gram, a particle size less than or equal to 4.5 microns, a tapped density of less than or equal to 80 grams/liter and a dibutyl phthalate absorption value of at least 330 percent.
Dependencies are inferred from the claim text.