Flame retardant combinations for thermoplastic polymers II

Details Flame retardant combinations for thermoplastic polymers II Flame retardant combinations for thermoplastic polymers II

2000-01-29

2002-02-05

Medley, Margaret (Department: 1714)

Compositions

Fire retarding

For solid synthetic polymer and reactants thereof

C524S116000

Reexamination Certificate

active

06344158

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a flame retardant combination for thermoplastic polymers and the use thereof.
DESCRIPTION OF THE RELATED ART
The salts of phosphinic acids (phosphinates) have proven to be effective flame-retardant additives for thermoplastic polymers. This applies both to the alkali metal salts (DE-A-22 52 258) and to the salts of other metals (DE-A-24 47 727).
Calcium phosphinates and aluminum phosphinates have been described as particularly effective in polyesters and give less impairment of the material properties of the polymeric molding compositions than do the alkali metal salts (EP-A-0 699 708).
Alicyclic phosphinates, e.g. the salts of 1-hydroxyphospholane oxides, also have flame-retardant properties and are particularly suitable for polyesters and polyamides (EP-A-0 794 191).
Synergistic combinations of the phosphinates mentioned with certain nitrogen-containing compounds have also been found, and in a large number of polymers these are more effective flame retardants than the phosphinates alone (PCT/EP97/01664, and also DE-A-197 34 437 and DE-A-197 37 727).
SUMMARY OF THE INVENTION
Surprisingly, it has now been found that the flame-retardant effect of the various phosphinates in thermoplastic polymers can also be markedly improved by adding small amounts of inorganic compounds which do not contain nitrogen. It has moreover been found that the additives mentioned can also improve the flame-retardant effect of phosphinates in combination with nitrogen-containing synergists.
The invention therefore provides a flame retardant combination for thermoplastic polymers comprising, as component A, a salt of 1-hydroxydihydrophosphole oxides of formula (Ia) or formula (Ib) and/or 1-hydroxyphospholane oxides of formula (II),
and, as component B, a synthetic inorganic compound and/or a mineral product.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
R
1
to R
4
, which are identical or different, are preferably hydrogen or C
1
-C
4
-alkyl, linear or branched.
R
1
to R
4
, which are identical or different, are particularly preferably methyl or ethyl.
The metal is preferably magnesium, calcium, zinc and/or aluminum.
Component B is preferably an oxygen compound of silicon, a magnesium compound, a metal carbonate of metals of the second main group of the Periodic Table, red phosphorus, a zinc compound or an aluminum compound.
The oxygen compounds of silicon are preferably salts or esters of orthosilicic acid and condensation products thereof, silicates, zeolites, silicas, glass powders, glass-ceramic powders or ceramic powders.
The magnesium compounds are preferably magnesium hydroxide, hydrotalcites, magnesium carbonates or magnesium calcium carbonates.
The red phosphorus is preferably elemental red phosphorus or a preparation in which the surface of the phosphorus has been coated with low-molecular-weight liquid substances, such as silicone oil, paraffin oil or esters of phthalic acid or adipic acid, or with polymers or oligomeric compounds, e.g. with phenolic resins or amino plastics, or else with polyurethanes.
The zinc compounds are preferably zinc oxide, zinc stannate, zinc hydroxystannate, zinc phosphate, zinc borate or zinc sulfides.
The aluminum compounds are preferably aluminum hydroxide or aluminum phosphate.
The novel flame retardant combination preferably comprises, as further component C, nitrogen compounds.
The nitrogen compounds preferably have the formulae (III) to (VIII) or are mixtures of these
or the nitrogen compounds are oligomeric esters of tris(hydroxyethyl) isocyanurate with aromatic polycarboxylic acids or are nitrogen-containing phosphates of the formula (NH
4
)
y
H
3−y
PO
4
or (NH
4
PO
3
)
z
, where y is from 1 to 3 and z is from 1 to 10,000.
Component C is preferably benzoguanamine, tris(hydroxyethyl) isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, melamine phosphate, dimelamine phosphate and/or melamine pyrophosphate.
The invention further provides the use of the novel flame retardant combination for rendering thermoplastic polymers flame-retardant. For the purposes of the present invention and as set out by Hans Domininghaus in “Die Kunststoffe und ihre Eigenschaften” [Plastics and their Properties], 5
th
edition (1998), p. 14, thermoplastic polymers are polymers in which the molecular chains have no lateral branching or else have varying numbers of lateral branches of different lengths, soften on heating and can be shaped in virtually any way desired.
These thermoplastic polymers are preferably HI (high-impact) polystyrene, polyphenylene ethers, polyamides, polyesters, polycarbonates or blends or polymer blends of ABS (acrylonitrile-butadiene-styrene) type or of PC/ABS (polycarbonate/acrylonitrile-butadiene-styrene) type. HI polystyrene is a polystyrene with increased impact strength.
Particularly preferred thermoplastic polymers are polyamides, polyesters and ABS.
The term plastic molding compositions is used below for thermoplastic polymers which comprise the novel flame retardant combinations and, if desired, fillers and reinforcing materials and/or other additives as defined below. The component B which has been mentioned earlier is a synthetic inorganic compound and/or a mineral product selected from the groups mentioned below:
Oxygen compounds of silicon, such as salts or esters of orthosilicic acid and condensation products thereof (silicates). An overview of suitable silicates is given, for example, by Riedel in Anorganische Chemie, 2
nd
edn., p. 490-497, Walter de Gruyter, Berlin-N.Y., 1990. Of particular interest here are phyllosilicates (laminar or layer silicates) such as talc, kaolinite and mica, and the group comprising the bentonites and montmorillonites, and also tectosilicates, e.g. the group comprising the zeolites. Besides these, it is also possible to use silicon dioxide in the form of finely dispersed silica.
The silica here may have been prepared pyrogenically or by a wet chemical process. The silicates and silicas mentioned may have been provided with organic modifiers in order to achieve certain surface properties.
Other components B which may be used are glass powders, glass-ceramic powders and ceramic powders with a variety of makeups, e.g. as described in “Ullmann's Encyclopedia of Industrial Chemistry,” 5
th
edition, Vol. A 12 (1989), pp. 372-387 (Glass) and pp. 443-448 (Glass-ceramics). Appropriate ceramic materials are described in Vol. 6 (1986) on pp. 12-18 (Commercial Ceramic Clays). It is possible to use either glasses and/or ceramics with defined melting points or else mixtures of products with a broad melting range, such as ceramic frits as used for preparing glazes. Frits of this type, or mixtures of two or more frits, may also comprise glass fibers, basalt fibers or ceramic fibers. Mixtures of this type are described, for example, in EP 0 287 293 B1.
Other compounds which may be used as component B are magnesium compounds, such as magnesium hydroxide, or also hydrotalcites of the formula
Mg
(1−a)
Al
a
(OH)
2
A
a/2
·pH
2
O,
where
A is an anion SO
4
2−
or CO
3
2−
,
a is greater than 0 and equal to or less than 0.5, and
p is the number of water molecules in the hydrotalcite and is from 0 to 1.
Preference is given to hydrotalcites in which A is the anion CO
3
2−
and 0.2≦a≦0.4. The hydrotalcites may be either naturally occurring hydrotalcites, which may, if desired, have been modified by an appropriate chemical treatment, or synthetically prepared products.
Other compounds which may be used as component B are metal carbonates of metals of the second main group of the Periodic Table and mixtures of these.
Suitable compounds are magnesium calcium carbonates (b
1
) of the formula
 Mg
b
Ca
c
(CO
3
)
b+c
·qH
2
O,
where
b and c are numbers from 1 to 5 and b/c≧1 and q≧0, and basic magnesium carbonates (b
2
) of the formula
Mg
d
(CO
3
)
e
(OH)
2d-2e
·rH
2
O,
where
d is a number from 1 to 6, e is a number greater than 0 and smaller than 6 and d/e>1 and r≧0. Particularly suitable mixtures are those made fro

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