Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-04-12
2001-07-17
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S155000, C521S168000, C521S169000, C521S170000, C521S906000
Reexamination Certificate
active
06262135
ABSTRACT:
BACKGROUND OF THE INVENTION
A wide variety of disclosures exist in regard to flame retardant additives for polymers, such as polyurethane foams. Two representative examples of disclosures of this type, which relate to blends of two differing flame retardant additives, include the following:
U.S. Pat. No. 4,273,881 to J. G. Otten describes the use of a 50:50 mixture of flame retardant A, sold under the trademark ANTIBLAZE 19, and bis-(2-chloroethyl)-2-chloroethyl-phosphonate (See Col. 9, lines 61-62).
U.S. Pat. No. 3,956,200 to J. Biranowski describes the use of flame retardant blends comprising a polyglycol hydrogen polyphosphonate and an additive, non-reactive flame retardant in a ratio of from about 20:1 to 1:1, preferably from about 5:1 to 1:1.
In addition to the foregoing patent disclosures, certain blends of monomeric and oligomeric flame retardants have also been sold to the polyurethane industry, including compositions carrying the trademarks FYROL® 25 and FYROL® EFF of Akzo Nobel Chemicals Inc. The product sold under the former mark included an oligomer that contained a blend of both phosphate and phosphonate moieties, whereas the product sold under the latter mark contained a major amount (about 66%) of the oligomeric component and a minor (about 32.5%) of the monomeric flame retardant component.
SUMMARY OF THE INVENTION
The present invention relates to a flame retardant blend comprising: (a) a monomeric halogenated organic flame retardant that is adapted for use in a polyurethane foam formulation; and (b) an oligomeric organophosphate flame retardant having a phosphorus content of no less than about 10%, by weight, and at least three phosphate ester units therein, the amount of (a) in the blend being no less than the amount of (b). The use of this blend in polyurethane foam compositions forms another aspect of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The monomeric halogenated flame retardant that forms one essential component of the blends of the present invention are those flame retardants additives that have hitherto been used in conferring flame retardancy on polyurethane foams (especially flexible polyurethane foams).
One representative class that can be selected include the halogenated phosphate esters containing from about 1 to about 5 carbon atoms in their alkyl groups. Representative additives include: tris(dichloropropyl) phosphate; tris(2-chloroethyl)phosphate; tris(dibromopropyl) phosphate; tris(bromochloropropyl)phosphate; and the like. In addition, a polybrominated diphenyl oxide-containing additive can be selected, such as one comprising pentabromodiphenyl oxide (e.g., about 65% to about 85% of pentabromodiphenyl oxide and about 15% to about 35% of an aryl phosphate). The amount of such additive in the blend will range from about 50% to about 95%, by weight of the blend, more preferably from about 60% to about 90%.
The second component of the blend is an oligomeric organophosphate flame retardant having a phosphorus content of no less than about 10%, by weight, and at least three phosphate ester units therein (at least two phosphate ester repeat units and a phosphate capping unit). The amount of this additive in the blend will range from about 5% to about 50%, by weight of the blend, more preferably from about 10% to about 30%. A representative additive of this type is generally described in U.S. Pat. No. 4,382,042 to T. A. Hardy with the non-halogenated versions being preferred (e.g., especially the ethyl group-containing composition). These oligomers can be formed by reacting phosphorus pentoxide with the selected trialkyl phosphate (e.g., triethyl phosphate) to form a polyphosphate ester containing P—O—P bonds that is then reacted with epoxide (e.g., ethylene oxide) to form the desired product. This oligomeric organophosphate flame retardant is preferably of the formula:
where n (which designates the “repeat” phosphate ester units) can range, on a number average basis, from 2 to about 20, preferably from 2 to about 10, and R is selected from the group consisting of alkyl, haloalkyl and hydroxyalkyl and R′ is alkylene. The alkyl and alkylene groups will generally contain from about two to about ten carbon atoms.
Especially preferred oligomeric polyphosphates for use herein will comprise ethyl and ethylene groups as the alkyl and alkylene moieties, will have a hydroxy functionality of no more than about 30 mg KOH/g, will have an acid number of no more than about 2.5 mg KOH/g, and will have a phosphorus content that ranges from about 17% to about 24%, by weight.
The flame retardant blend of this invention can be added to the selected polyurethane foam formulation at from about 2 to about 35 parts by weight of the blend per 100 parts by weight of the polyol that is in the formulation. The weight percent phosphorus that is in the final polyurethane foam formulation will range from about 0.25 wt % to about 3.5 wt %. The foregoing type of flame retardant blend is especially adapted for use in flexible and rigid polyurethane foams and, in certain embodiments (e.g., at ratios of from about 1:1 to about 20:1 of the monomeric additive:oligomeric additive) in typical polyester polyurethane flexible foams, have shown unexpectedly greater efficiency of the blend as compared to the additive sums of the individual components thereof. This performance is especially attractive since the oligomeric material is typically much more expensive than the monomeric material making cost efficiency of the blend particularly beneficial.
The density of the foam is an important factor. In general, the higher the density, the less flame retardant additive required to pass the flame test. The addition of the blended product is more enhanced with this rule. For example, the present blend when at a 3:1 ratio will pass the TB117 test in a 1.0 pcf density foam at 14 parts per hundred. The same blend will meet the TB117 test in a 1.8 pcf density foam at 6 parts per hundred.
A blend of two phosphorus containing products differing in efficiency (as measured by parts required to pass a given test) can be further compared by, parts of phosphorus required to pass a given test. For blends of these two products it is expected that the phosphorus requirement to pass said test will fall between the two. If less phosphorus is required for the blend than for either Individual product, it is clearly synergistic/advantageous. For example (from Example 9-19), additive product A, a monomeric halogenated flame retardant requires 0.99% of phosphorus to pass the TB117 test, and product B, an oligomeric organophosphate flame retardant requires 0.95% phosphorus to meet the TB117 test. The blend of the two products in a 3:1 ratio requires 0.60% phosphorus in a 1.8 pcf density foam.
U.S. Pat. No. 3,956,200 is incorporated herein (see, for example, Col. 6, line 25 to Col. 8, line 15) to illustrate how such flexible foams, which are preferred, can be made.
REFERENCES:
patent: 3891727 (1975-06-01), Weil
patent: 3956200 (1976-05-01), Biranowski
patent: 4133846 (1979-01-01), Albright
patent: 4194068 (1980-03-01), Miller et al.
patent: 4273881 (1981-06-01), Otten
patent: 4382042 (1983-05-01), Hardy et al.
patent: 4458035 (1984-07-01), Hardy et al.
patent: 4746682 (1988-05-01), Green
patent: 5086082 (1992-02-01), Stone
patent: 5157056 (1992-10-01), McGovern
patent: 5164417 (1992-11-01), Anderson
patent: 5547614 (1996-08-01), Fesman et al.
patent: 5608100 (1997-03-01), Sicken
patent: 5672645 (1997-09-01), Eckel et al.
patent: 5679288 (1997-10-01), Kim et al.
patent: 5985965 (1999-11-01), Sicken et al.
patent: 255381 (1988-02-01), None
patent: 428221 (1991-05-01), None
patent: 640655 (1995-03-01), None
Bradford Larry L.
Halchak Theodore
Pinzoni Emanuel
Williams Barbara A.
Akzo Nobel nv
Fennelly Richard P.
Sergent Rabon
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