Note: Descriptions are shown in the official language in which they were submitted.
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CuO/ZnO compounds as stabilisers for flame retardant polyamides
Description
The invention relates to thermoplastic molding compositions comprising
F) from 10 to 99.8% by weight of a thermoplastic polyamide,
G) from 0.1 to 60% by weight of red phosphorus,
H) from 0.05 to 5% by weight of a catalyst comprising copper and zinc and
support
material,
I) from 0 to 40% by weight of an impact modifier,
J) from 0 to 60% by weight of further additives,
where the total of the percentages by weight of A) to E) is 100%.
The present invention also relates to the use of molding compositions of this
type for
producing fibers, films, and moldings, and to the moldings, fibers, and films
of any type thus
obtainable.
Addition of red phosphorus to thermoplastics, especially to reinforced or
filled polyamides, is
known to lead to effective fire protection (DE-A-1931387). However, under
unfavorable
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conditions, e.g. elevated temperature or moisture, or presence of alkali or
oxygen, red
phosphorus tends to form decomposition products, such as phosphine and acids
of mono- to
pentavalent phosphorus. Although red phosphorus incorporated within
thermoplastics, e.g.
polyamides, has substantial protection from thermal oxidation as a consequence
of
embedment into the polymer, formation of decomposition products can
nevertheless still
occur here over prolonged periods. This is disadvantageous because if pellets
are not
correctly processed in the injection-molding process, the resultant phosphine
can cause odor
problems and is moreover toxic. The phosphorus acids produced at the same time
can
deposit on the surface of moldings, a particular result being that the
moldings have reduced
tracking resistance. There has therefore been no lack of attempts to improve
the stability of
red phosphorus used as flame retardant for plastics. By way of example, a
stabilizing effect
can be achieved via addition of oxides or hydroxides of zinc, of magnesium, or
of copper. In
DE-A-2625691, in addition to said stabilization via metal oxides, a polymer is
used to coat
the phosphorus particles. However, said coating or encapsulation process is
very
complicated, and the stabilizing effect of the system is moreover not always
satisfactory.
Catalysts based on CuO/ZnO are available commercially and are generally used
as
synthesis gas catalysts or for gas purification: see by way of example DE-A 37
17 111, DE-
A 43 01 469, W02002/94435, W02004/22223, and W02007/093526.
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It is therefore an object of the present invention to develop thermoplastic
molding
compositions which comprise, as flame retardant, a red phosphorus that has
been stabilized
in an effective manner. The stabilizers are moreover intended to feature good
stability during
processing and particularly homogeneous dispersibility in the plastics melt.
The intention was
moreover to reduce or eliminate the release of volatile phosphorus compounds
which are
responsible for the formation of contact deposits on metallic conductors.
The molding compositions defined in the introduction have accordingly been
found. Preferred
embodiments are given in the dependent claims.
Surprisingly, it has been found that thermoplastic molding compositions which
comprise even
small amounts of above catalysts as stabilizer provide excellent compliance
with the
properties required.
The molding compositions of the invention comprise, as component A), from 10
to 99.8% by
weight, preferably from 20 to 98% by weight, and in particular from 30 to 90%
by weight, of at
least one polyamide.
The polyamides of the molding compositions of the invention generally have an
intrinsic
viscosity of from 90 to 350 ml/g, preferably from 110 to 240 ml/g, determined
in a 0.5%
strength by weight solution in 96% strength by weight sulfuric acid at 25 C to
ISO 307.
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Preference is given to semicrystalline or amorphous resins with a molecular
weight (weight
average) of at least 5000, described by way of example in the following US
patents: 2 071
250, 2 071 251, 2 130 523, 2 130 948, 2 241 322, 2 312 966, 2 512 606, and 3
393 210.
Examples of these are polyam ides that derive from lactams having from 7 to 13
ring
members, e.g. polycaprolactam, polycaprylolactam, and polylaurolactam, and
also
polyamides obtained via reaction of dicarboxylic acids with diamines.
Dicarboxylic acids which may be used are alkanedicarboxylic acids having 6 to
12, in
particular 6 to 10, carbon atoms, and aromatic dicarboxylic acids. Merely as
examples, acids
that may be mentioned here are adipic acid, azelaic acid, sebacic acid,
dodecanedioic acid
and terephthalic and/or isophthalic acid.
Particularly suitable diamines are alkanediamines having from 6 to 12, in
particular from 6 to
8, carbon atoms, or else m-xylylenediamine (e.g. Ultramid X17 from BASF SE,
where the
molar ratio of MXDA to adipic acid is 1:1), di(4-aminophenyl)methane, di(4-
aminocyclohexyl)-
methane, 2,2-di(4-aminophenyl)propane, 2,2-di(4-aminocyclohexyl)propane, or
1,5-diamino-
2-methylpentane.
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Preferred polyamides are polyhexamethyleneadipamide,
polyhexamethylenesebacamide,
and polycaprolactam, and also nylon-6/6,6 copolyamides, in particular having a
proportion of
from 5 to 95% by weight of caprolactam units (e.g. Ultramid C31 from BASF
SE).
Other suitable polyamides are obtainable from w-aminoalkylnitriles, e.g.
aminocapronitrile
5 (PA 6) and adiponitrile with hexamethylenediamine (PA 66) via what is
known as direct
polymerization in the presence of water, for example as described in DE-A
10313681,
EP-A 1198491 and EP 922065.
Mention may also be made of polyamides obtainable, by way of example, via
condensation
of 1,4-diaminobutane with adipic acid at an elevated temperature (nylon-4,6).
Preparation
processes for polyamides of this structure are described by way of example in
EP-A 38 094,
EP-A 38 582, and EP-A 39 524.
Other suitable examples are polyamides obtainable via copolymerization of two
or more of
the abovementioned monomers, and mixtures of two or more polyamides in any
desired
mixing ratio. Particular preference is given to mixtures of nylon-6,6 with
other polyamides, in
particular nylon-6/6,6 copolyamides.
Other copolyamides which have proven particularly advantageous are
semiaromatic
copolyamides, such as PA 6/6T and PA 66/6T, where the triamine content of
these is less
than 0.5% by weight, preferably less than 0.3% by weight (see EP-A 299 444).
Other
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polyamides resistant to high temperatures are known from EP-A 19 94 075
(PA 6T/6I/MXD6).
The processes described in EP-A 129 195 and 129 196 can be used to prepare the
preferred
semiaromatic copolyamides with low triamine content.
The following list, which is not comprehensive, comprises the polyamides A)
mentioned and
other polyamides A) for the purposes of the invention, and the monomers
comprised.
AB polymers:
PA 4 Pyrrolidone
PA 6 c-Caprolactam
PA 7 Ethanolactam
PA 8 Caprylolactam
PA 9 9-Aminopelargonic acid
PA 11 11-Aminoundecanoic acid
PA 12 Laurolactam
AA/BB polymers
PA 46 Tetramethylenediamine, adipic acid
PA 66 Hexamethylenediamine, adipic acid
PA 69 Hexamethylenediamine, azelaic acid
PA 610 Hexamethylenediamine, sebacic acid
PA 612 Hexamethylenediamine, decanedicarboxylic acid
PA 613 Hexamethylenediamine, undecanedicarboxylic acid
PA 1212 1,12-Dodecanediamine, decanedicarboxylic acid
PA 1313 1,13-Diaminotridecane, undecanedicarboxylic acid
PA 6T Hexamethylenediamine, terephthalic acid
PA 9T 1,9-Nonanediamine, terephthalic acid
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PA MXD6 m-Xylylenediamine, adipic acid
PA 61 Hexamethylenediamine, isophthalic acid
PA 6-3-T Trimethylhexamethylenediamine, terephthalic acid
PA 6/6T (see PA 6 and PA 6T)
PA 6/66 (see PA 6 and PA 66)
PA 6/12 (see PA 6 and PA 12)
PA 66/6/610 (see PA 66, PA 6 and PA 610)
PA 61/6T (see PA 61 and PA 6T)
PA PACM 12 Diaminodicyclohexylmethane, laurolactam
PA 6I/6T/PACM as PA 6I/6T + diaminodicyclohexylmethane
PA 12/MACM1 Laurolactam, dimethyldiaminodicyclohexylmethane,
isophthalic acid
PA 12/MACMT Laurolactam, dimethyldiaminodicyclohexylmethane,
terephthalic acid
PA PDA-T Phenylenediamine, terephthalic acid
Preferred flame retardant B) is elemental red phosphorus, in particular in
combination with
glass fiber-reinforced molding compositions; it can be used in untreated form.
However, particularly suitable preparations are those in which the phosphorus
has been
surface-treated with low-molecular-weight liquid substances, such as silicone
oil, paraffin oil,
or esters of phthalic acid (in particular dioctyl phthalate, see EP 176 836)
or adipic acid, or
with polymeric or oligomeric compounds, e.g. with phenolic resins or
aminoplastics, or else
with polyurethanes (see EP-A 384 232, DE-A 196 48 503). Amounts comprised of
these
"phlegmatizing agents" are generally from 0.05 to 5% by weight, based on 100%
by weight of
B).
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Concentrates of red phosphorus are also suitable as flame retardant, e.g. in a
polyamide or
elastomer. Particularly suitable concentrate polymers are polyolefin
homopolymers and
polyolefin copolymers. However, the proportion of the concentrate polymer - if
no polyamide
is used as thermoplastic - should not exceed 35% by weight, based on the
weight of
components A) and B) in the molding compositions of the invention.
Preferred concentrate compositions are
Bi) from 30 to 90%-by weight, preferably from 45 to 70% by weight,
of a polyamide or
elastomer, and
B2) from 10 to 70% by weight, preferably from 30 to 55% by weight,
of red
phosphorus.
The polyamide used for the masterbatch can differ from A) or can preferably be
identical with
A), so that the molding composition does not suffer any adverse effect caused
by
incompatibility phenomena or by melting point differences.
The average particle size (d50) of the phosphorus particles dispersed in the
molding
compositions is preferably in the range from 0.0001 to 0.5 mm; in particular
from 0.001 to
0.2 mm.
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The content of component B) in the molding compositions of the invention is
from 0.1 to 60%
by weight, preferably from 0.5 to 40% by weight, and in particular from 1 to
15% by weight,
based on the entirety of components A) to E).
The molding compositions of the invention comprise, as component C), from 0.05
to 5% by
weight, preferably from 0.1 to 2% by weight, and in particular from 0.1 to
1.5% by weight, and
very particularly preferably from 0.1 to 1% by weight, of a catalyst
comprising Cu, Zn, and
support material.
For the actual purposes of the person skilled in the art, these involve
adsorption
compositions or absorption compositions which are however often termed
"catalysts" even
though when they are used in accordance with instructions they do not actually
have catalytic
effect.
The BET surface area of the component is preferably from 1 to 350 m2/g, in
particular from
10 to 250 m2/g, particularly preferably from 20 to 150 m2/g (in accordance
with ISO 9277,
under nitrogen).
Suitable inert support materials are Al oxides, silicon dioxides, titanium
dioxides, magnesium
oxide, iron oxides, zirconium dioxide, aluminosilicates, clays, zeolites,
kieselguhr,
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hydrotalcites, fumed silica, or a mixture of these, preference being given to
Al oxides and/or
zirconium dioxides.
The catalysts of the invention comprise copper, which is to some extent
present as metallic
5 Cu and otherwise is present in the form of Cu(I) oxides and of Cu(II)
oxides.
The amount of catalyst Cu present in the preferred catalyst mixture,
calculated as CuO, is at
least 30% by weight, preferably 35% by weight, and in particular 40% by
weight, and at most
70% by weight, preferably at most 65% by weight, of CuO, based in each case on
the total
10 amount of the catalyst composition.
Preferred amounts of ZnO are from 15 to 60% by weight, preferably from 15 to
55% by
weight, and in particular from 15 to 48% by weight, of ZnO.
The preferred proportion of the support material is from 1 to 35% by weight,
preferably from
10 to 35% by weight, and in particular from 13 to 30% by weight, preference
being given to
aluminum dioxide and/or zirconium dioxide.
The catalysts C) can moreover comprise, within the mixture, from 0 to 5% by
weight,
preferably from 0 to 2% by weight, and in particular from 0 to 1% by weight,
of further
promoters.
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These are elements or oxides selected from alkali metals, alkaline earth
metals, rare earths,
Sc, Ti, V, Cr, Y, Zr, B, Si, Ge, P, Bi, or a mixture of these, and preferably
Co, Fe, Ni, W, Cr,
Mo, Mn, K, Mg, Ca, Cu, Zn or Al.
Particularly preferred catalysts C) are mixtures of
from 30 to 65% by weight, preferably from 35 to 65% by weight of CuO,
from 15 to 60% by weight, preferably from 15 to 55% by weight of ZnO,
from 10 to 35% by weight, preferably from 13 to 30% by weight of Al dioxides,
from 0 to 5% by weight, preferably from 0 to 2% by weight of promoters,
where the total of the percentages by weight is 100% by weight.
The shape and form of the catalysts of the invention can be selected as
desired, examples
being tablets, rings, stars, wagon-wheels, and extrudates, such as cylinders,
pellets, or
strands, preference being given to annular tablets or tablets or in powder
form as component
C).
Production of the catalysts of the invention generally gives these in
"oxidized" form, i.e. the
copper in the catalyst takes the form of copper oxides in a mixture with Cu.
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The production of the catalysts C) is known to the person skilled in the art
and can by way of
example be achieved by precipitating the corresponding salts together with an
alkaline
precipitant reagent and then drying and calcination of the solids at elevated
temperature (see
DE-A 37 17 111).
Another production method as in DE-A 43 01 469 uses aqueous impregnation of
spinels of
the structure M-A1204 in an A1203 matrix with metal salt solutions, and
kneading with the
corresponding metal oxides and subsequent calcination (see DE-A 43 01 469).
Further production methods can be found in W02002/94435, W02004/22223, and
W02007/093526.
Preferred catalysts C) are used together with acid scavengers based on
hydrotalcites or
oxides or hydroxides or salts of zinc or of the alkaline earth metals, in the
molding
composition.
The mixing ratio is preferably from 10:1 to 1:10, in particular from 5:1 to
1:5 (ratio by weight).
Suitable acid scavengers are ZnO, Zn borate, Zn stannate, MgO, Mg(OH)2, ZnCO3,
MgCO3,
CaCO3, Mg Ca carbonates A100H, and particular preference is given here to ZnO,
basic
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ZnCO3, Mg(OH)2 or CaCO3.
The molding compositions comprise, as component D), amounts of from 0 to 40%
by weight,
preferably from 1 to 30% by weight, in particular from 2 to 20% by weight, of
elastomeric
polymers (often also termed impact modifiers, elastomers, or rubbers).
These are very generally copolymers preferably composed of at least two of the
following
monomers: ethylene, propylene, butadiene, isobutene, isoprene, chloroprene,
vinyl acetate,
styrene, acrylonitrile and acrylates and/or methacrylates having from 1 to 18
carbon atoms in
the alcohol component.
Polymers of this type are described, for example, in Houben-Weyl, Methoden der
organischen Chemie, Vol. 14/1 (Georg-Thieme-Verlag, Stuttgart, Germany, 1961),
pages
392-406, and in the monograph by C.B. Bucknall, "Toughened Plastics" (Applied
Science
Publishers, London, 1977).
Some preferred types of such elastomers are described below.
Preferred types of such elastomers are those known as ethylene-propylene (EPM)
and
ethylene-propylene-diene (EPDM) rubbers.
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EPM rubbers generally have practically no residual double bonds, whereas EPDM
rubbers
may have from 1 to 20 double bonds per 100 carbon atoms.
Examples which may be mentioned of diene monomers for EPDM rubbers are
conjugated
dienes, such as isoprene and butadiene, non-conjugated dienes having from 5 to
25 carbon
atoms, such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethy1-1,5-
hexadiene
and 1,4-octadiene, cyclic dienes, such as cyclopentadiene, cyclohexadienes,
cyclooctadienes and dicyclopentadiene, and also alkenylnorbornenes, such as 5-
ethylidene-
2-norbornene, 5-butylidene-2-norbornene, 2-methallyI-5-norbornene and 2-
isopropeny1-5-
norbornene, and tricyclodienes, such as 3-methyltricyclo[5.2.1.02,6]-3,8-
decadiene, and
mixtures of these. Preference is given to 1,5-hexadiene, 5-
ethylidenenorbornene and
dicyclopentadiene. The diene content of the EPDM rubbers is preferably from
0.5 to 50% by
weight, in particular from 1 to 8% by weight, based on the total weight of the
rubber.
EPM rubbers and EPDM rubbers may preferably also have been grafted with
reactive
carboxylic acids or with derivatives of these. Examples of these are acrylic
acid, methacrylic
acid and derivatives thereof, e.g. glycidyl (meth)acrylate, and also maleic
anhydride.
Copolymers of ethylene with acrylic acid and/or methacrylic acid and/or with
the esters of
these acids are another group of preferred rubbers. The rubbers may also
comprise
dicarboxylic acids, such as maleic acid and fumaric acid, or derivatives of
these acids, e.g.
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esters and anhydrides, and/or monomers comprising epoxy groups. These monomers
comprising dicarboxylic acid derivatives or comprising epoxy groups are
preferably
incorporated into the rubber by adding to the monomer mixture monomers
comprising
dicarboxylic acid groups and/or epoxy groups and having the general formulae I
or II or III or
5 IV
R1C(COOR2)=C(COOR3)R4 (I)
RI\ R4
(II)
OC CO
0
CHR7=CH¨ (CH2)m¨ 0 ¨ (CHR6)g¨CH¨CHR5 (III)
CH2=_¨CR9¨ COO¨ (¨CH2)p¨CH¨CHR8 (IV)
0
where R, to R9 are hydrogen or alkyl groups having from 1 to 6 carbon atoms,
and m is a
whole number from 0 to 20, g is a whole number from 0 to 10 and p is a whole
number from
0 to 5.
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The radicals R1 to R9 are preferably hydrogen, where m is 0 or 1 and g is 1.
The
corresponding compounds are maleic acid, fumaric acid, maleic anhydride, allyl
glycidyl
ether and vinyl glycidyl ether.
Preferred compounds of the formulae I, II and IV are maleic acid, maleic
anhydride and
(meth)acrylates comprising epoxy groups, such as glycidyl acrylate and
glycidyl
methacrylate, and the esters with tertiary alcohols, such as tert-butyl
acrylate. Although the
latter have no free carboxy groups, their behavior approximates to that of the
free acids and
they are therefore termed monomers with latent carboxy groups.
The copolymers are advantageously composed of from 50 to 98% by weight of
ethylene,
from 0.1 to 20% by weight of monomers comprising epoxy groups and/or
methacrylic acid
and/or monomers comprising anhydride groups, the remaining amount being
(meth)acrylates.
Particular preference is given to copolymers composed of
from 50 to 98% by weight, in particular from 55 to 95% by weight, of ethylene,
from 0.1 to 40% by weight, in particular from 0.3 to 20% by weight, of
glycidyl acrylate
and/or glycidyl methacrylate, (meth)acrylic acid and/or maleic
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anhydride, and
from 1 to 45% by weight, in particular from 5 to 40% by weight, of n-butyl
acrylate and/or
2-ethylhexyl acrylate.
Other preferred (meth)acrylates are the methyl, ethyl, propyl, isobutyl and
tert-butyl esters.
Comonomers which may be used alongside these are vinyl esters and vinyl
ethers.
The ethylene copolymers described above may be prepared by processes known per
se,
preferably by random copolymerization at high pressure and elevated
temperature.
Appropriate processes are well known.
Other preferred elastomers are emulsion polymers whose preparation is
described, for
example, by Blackley in the monograph "Emulsion Polymerization". The
emulsifiers and
catalysts which can be used are known per se.
In principle it is possible to use homogeneously structured elastomers or else
those with a
shell structure. The shell-type structure is determined by the sequence of
addition of the
individual monomers. The morphology of the polymers is also affected by this
sequence of
addition.
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Monomers which may be mentioned here, merely as examples, for the preparation
of the
rubber fraction of the elastomers are acrylates, such as n-butyl acrylate and
2-ethylhexyl
acrylate, corresponding methacrylates, butadiene and isoprene, and also
mixtures of these.
These monomers may be copolymerized with other monomers, such as styrene,
acrylonitrile,
vinyl ethers and with other acrylates or methacrylates, such as methyl
methacrylate, methyl
acrylate, ethyl acrylate or propyl acrylate.
The soft or rubber phase (with a glass transition temperature of below 0 C) of
the elastomers
may be the core, the outer envelope or an intermediate shell (in the case of
elastomers
whose structure has more than two shells). Elastomers having more than one
shell may also
have more than one shell composed of a rubber phase.
If one or more hard components (with glass transition temperatures above 20 C)
are
involved, besides the rubber phase, in the structure of the elastomer, these
are generally
prepared by polymerizing, as principal monomers, styrene, acrylonitrile,
methacrylonitrile, a-
methylstyrene, p-methylstyrene, or acrylates or methacrylates, such as methyl
acrylate, ethyl
acrylate or methyl methacrylate. Besides these, it is also possible to use
relatively small
proportions of other comonomers.
It has proven advantageous in some cases to use emulsion polymers which have
reactive
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groups at their surfaces. Examples of groups of this type are epoxy, carboxy,
latent carboxy,
amino and amide groups, and also functional groups which may be introduced by
concomitant use of monomers of the general formula
R1 R11
CH2¨C _________________________________ X¨N ___ C __ R12
0
where the substituents can be defined as follows,
R10 is hydrogen or a Ci-C4-alkyl group,
R11 is hydrogen, a Ci-C8-alkyl group or an aryl group, in particular
phenyl,
R12 is hydrogen, a Ci-Cio-alkyl group, a C6-C12-aryl group, or -0R13
R13 is a Ci-C8-alkyl group or a C6-C12-aryl group, which can optionally have
substitution by
groups that comprise 0 or by groups that comprise N,
X is a chemical bond, a C-i-Cio-alkylene group, or a C6-C12-arylene
group, or
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0
¨C
Y is O-Z or NH-Z, and
5 Z is a C1-C10-alkylene or C6-C12-arylene group.
The graft monomers described in EP-A 208 187 are also suitable for introducing
reactive
groups at the surface.
10 Other examples which may be mentioned are acrylamide, methacrylamide and
substituted
acrylates or methacrylates, such as (N-tert-butylamino)ethyl methacrylate,
(N,N-
dimethylamino)ethyl acrylate, (N,N-dimethylamino)methyl acrylate and (N,N-
diethylamino)ethyl acrylate.
15 The particles of the rubber phase may also have been crosslinked.
Examples of crosslinking
monomers are 1,3-butadiene, divinylbenzene, diallyl phthalate and
dihydrodicyclopentadienyl
acrylate, and also the compounds described in EP-A 50 265.
It is also possible to use the monomers known as graft-linking monomers, i.e.
monomers
20 having two or more polymerizable double bonds which react at different
rates during the
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polymerization. Preference is given to the use of compounds of this type in
which at least
one reactive group polymerizes at about the same rate as the other monomers,
while the
other reactive group (or reactive groups), for example, polymerize(s)
significantly more
slowly. The different polymerization rates give rise to a certain proportion
of unsaturated
double bonds in the rubber. If another phase is then grafted onto a rubber of
this type, at
least some of the double bonds present in the rubber react with the graft
monomers to form
chemical bonds, i.e. the phase grafted on has at least some degree of chemical
bonding to
the graft base.
Examples of graft-linking monomers of this type are monomers comprising allyl
groups, in
particular allyl esters of ethylenically unsaturated carboxylic acids, for
example allyl acrylate,
allyl methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate,
and the
corresponding monoallyl compounds of these dicarboxylic acids. Besides these
there is a
wide variety of other suitable graft-linking monomers. For further details
reference may be
made here, for example, to US patent 4 148 846.
The proportion of these crosslinking monomers in the impact-modifying polymer
is generally
up to 5% by weight, preferably not more than 3% by weight, based on the impact-
modifying
polymer.
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Some preferred emulsion polymers are listed below. Mention may first be made
here of graft
polymers with a core and with at least one outer shell, and having the
following structure:
Type Monomers for the core Monomers for the envelope
1,3-butadiene, isoprene, n-butyl acrylate, styrene, acrylonitrile, methyl
methacrylate
ethylhexyl acrylate, or a mixture of these
II as I, but with concomitant use of as I
crosslinking agents
Ill as I or II n-butyl acrylate, ethyl
acrylate, methyl
acrylate, 1,3-butadiene, isoprene,
ethylhexyl acrylate
IV as I or II as I or III, but with
concomitant use of
monomers having reactive groups, as
described herein
V styrene, acrylonitrile, methyl methacrylate, first envelope
composed of monomers as
or a mixture of these described under I and ll for
the core,
second envelope as described under I or
IV for the envelope
Instead of graft polymers whose structure has more than one shell, it is also
possible to use
homogeneous, i.e. single-shell, elastomers composed of 1,3-butadiene, isoprene
and n-butyl
acrylate or of copolymers of these. These products, too, may be prepared by
concomitant
use of crosslinking monomers or of monomers having reactive groups.
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Examples of preferred emulsion polymers are n-butyl acrylate-(meth)acrylic
acid copolymers,
n-butyl acrylate-glycidyl acrylate or n-butyl acrylate-glycidyl methacrylate
copolymers, graft
polymers with an inner core composed of n-butyl acrylate or based on butadiene
and with an
outer envelope composed of the abovementioned copolymers, and copolymers of
ethylene
with comonomers which supply reactive groups.
The elastomers described may also be prepared by other conventional processes,
e.g. by
suspension polymerization.
Preference is also given to silicone rubbers, as described in DE-A 37 25 576,
EP-A 235 690,
DE-A 38 00 603 and EP-A 319 290.
Particularly preferred rubbers D) are ethylene copolymers, as described above,
which
comprise functional monomers, where the functional monomers have been selected
from the
group of the carboxylic acid, anhydride, carboxylic ester, carboxamide,
carboximide, amino,
hydroxy, epoxy, urethane, and oxazoline groups, and mixtures of these.
The proportion of the functional groups is from 0.1 to 20% by weight,
preferably from 0.2 to
10% by weight, and in particular from 0.3 to 7.0% by weight, based on 100% by
weight of D).
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Particularly preferred monomers are composed of an ethylenically unsaturated
mono- or
dicarboxylic acid or of a functional derivative of this type of acid.
In principle any of the primary, secondary, and tertiary C1-C18-alkyl esters
of acrylic acid or
methacrylic acid is suitable, but preference is given to esters having from 1
to 12 carbon
atoms, in particular having from 2 to 10 carbon atoms.
Examples of these are methyl, ethyl, propyl, n-butyl, isobutyl, and tert-
butyl, 2-ethylhexyl,
octyl, and decyl acrylates and the corresponding methacrylates. Among these,
particular
preference is given to n-butyl acrylate and 2-ethylhexyl acrylate.
Instead of the esters or in addition to these, it is also possible that the
olefin polymers
comprise acid-functional and/or latent acid-functional monomers of
ethylenically unsaturated
mono- or dicarboxylic acids, or comprise monomers having epoxy groups.
Other examples that may be mentioned of monomers are acrylic acid, methacrylic
acid,
tertiary alkyl esters of said acids, in particular tert-butyl acrylate, and
dicarboxylic acids, such
as maleic acid and fumaric acid, and derivatives of said acids, and also
monoesters of these.
Latent acid-functional monomers are compounds which form free acid groups
under the
polymerization conditions and, respectively, during incorporation of the
olefin polymers into
CA 02864942 2014-08-19
the molding compositions. Examples of these that may be mentioned are
anhydrides of
dicarboxylic acids having up to 20 carbon atoms, in particular maleic
anhydride, and tertiary
C1-C12-alkyl esters of the abovementioned acids, in particular tert-butyl
acrylate and tert-butyl
methacrylate.
5
The acid-functional or latent acid-functional monomers and the monomers
comprising epoxy
groups are preferably incorporated into the olefin polymers via addition of
compounds of the
general formulae I-IV to the monomer mixture.
10 The melt index of the ethylene copolymers is generally in the range from
1 to 80 g/10 min
(measured at 190 C with 2.16 kg load).
The molar mass of said ethylene-a-olefin copolymers is from 10 000 to 500 000
g/mol,
preferably from 15 000 to 400 000 g/mol (Mn, determined by means of GPO in
1,2,4-
15 trichlorobenzene with PS calibration).
In one particular embodiment, ethylene-a-olefin copolymers are used which have
been
produced by means of what are known as "single site catalysts". Further
details can be found
in US 5,272,236. In this case, the molecular weight distribution of the
ethylene-a-olefin
20 copolymers is narrow for polyolefins, being smaller than 4, preferably
smaller than 3.5.
CA 02864942 2014-08-19
26
Preferred commercially available products B used are Exxelor VA 1801 or 1803,
Kraton G
1901 FX or Fusabond N NM493 D or Fusabond A560 from Exxon, Kraton and
DuPont,
and also TafmeroMH 7010 from Mitsui.
It is also possible, of course, to use mixtures of the types of rubber listed
above.
The molding compositions of the invention can comprise, as component E), up to
60% by
weight, preferably up to 50% by weight, of further additives.
Fibrous or particulate fillers E) that may be mentioned are carbon fibers,
glass fibers, glass
beads, amorphous silica, calcium silicate, calcium metasilicate, magnesium
carbonate,
kaolin, chalk, powdered quartz, mica, barium sulfate, and feldspar, and the
amounts of these
that can be used are from 1 to 50% by weight, in particular from 5 to 40% by
weight,
preferably from 10 to 40% by weight.
Preferred fibrous fillers that may be mentioned are carbon fibers, aramid
fibers, and
potassium titanate fibers, particular preference being given to glass fibers
in the form of E
glass. These can be used as rovings or in the commercially available forms of
chopped
glass.
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27
The fibrous fillers may have been surface-pretreated with a silane compound to
improve
compatibility with the thermoplastic.
Suitable silane compounds have the general formula
(X¨(CH2)n)k¨Si¨(0¨CmH2m4.1)4-k
where the definitions of the substituents are as follows:
X NH-, CH2-CH-, HO-,
n is a whole number from 2 to 10, preferably 3 to 4,
m is a whole number from 1 to 5, preferably 1 to 2, and
k is a whole number from 1 to 3, preferably 1.
Preferred silane compounds are aminopropyltrimethoxysilane,
aminobutyltrimethoxysilane,
aminopropyltriethoxysilane and aminobutyltriethoxysilane, and also the
corresponding
silanes which comprise a glycidyl group as substituent X.
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The amounts of the silane compounds generally used for surface-coating are
from 0.01 to
2% by weight, preferably from 0.025 to 1.0% by weight and in particular from
0.05 to 0.5% by
weight (based on E)).
Acicular mineral fillers are also suitable.
For the purposes of the invention, acicular mineral fillers are mineral
fillers with strongly
developed acicular character. An example is acicular wollastonite. The mineral
preferably
has an L/D (length to diameter) ratio of from 8:1 to 35:1, preferably from 8:1
to 11:1. The
mineral filler may, if appropriate, have been pretreated with the
abovementioned silane
compounds, but the pretreatment is not essential.
Other fillers which may be mentioned are kaolin, calcined kaolin,
wollastonite, talc and chalk,
and also lamellar or acicular nanofillers, the amounts of these preferably
being from 0.1 to
10%. Materials preferred for this purpose are boehmite, bentonite,
montmorillonite,
vermiculite, hectorite, and laponite. The lamellar nanofillers are organically
modified by prior-
art methods, to give them good compatibility with the organic binder. Addition
of the lamellar
or acicular nanofillers to the inventive nanocomposites gives a further
increase in mechanical
strength.
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The molding compositions of the invention can comprise, as component E), frpm
0.05 to 3%
by weight, preferably from 0.1 to 1.5% by weight, and in particular from 0.1
to 1% by weight,
of a lubricant.
Preference is given to the salts of Al, of alkali metals, or of alkaline earth
metals, or esters or
amides of fatty acids having from 10 to 44 carbon atoms, preferably having
from 12 to 44
carbon atoms.
The metal ions are preferably alkaline earth metal and Al, particular
preference being given
to Ca or Mg.
Preferred metal salts are Ca stearate and Ca montanate, and also Al stearate.
It is also possible to use a mixture of various salts, in any desired mixing
ratio.
The carboxylic acids can be monobasic or dibasic. Examples which may be
mentioned are
pelargonic acid, palmitic acid, lauric acid, margaric acid, dodecanedioic
acid, behenic acid,
and particularly preferably stearic acid, capric acid, and also montanic acid
(a mixture of fatty
acids having from 30 to 40 carbon atoms).
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The aliphatic alcohols can be monohydric to tetrahydric. Examples of alcohols
are n-butanol,
n-octanol, stearyl alcohol, ethylene glycol, propylene glycol, neopentyl
glycol, pentaerythritol,
preference being given to glycerol and pentaerythritol.
ethylenediamine, propylenediamine, hexamethylenediamine, di(6-
aminohexyl)amine,
particular preference being given to ethylenediamine and hexamethylenediamine.
Preferred
esters or amides are correspondingly glycerol distearate, glycerol
tristearate,
ethylenediamine distearate, glycerol monopalmitate, glycerol trilaurate,
glycerol
It is also possible to use a mixture of various esters or amides, or of esters
with amides in
combination, in any desired mixing ratio.
by weight, preferably from 0.1 to 1.5% by weight, and in particular from 0.1
to 1% by weight,
of a Cu stabilizer, preferably of a Cu(I) halide, in particular in a mixture
with an alkali metal
halide, preferably KI, in particular in the ratio 1:4, or of a sterically
hindered phenol, or a
mixture of these.
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31
Preferred salts of monovalent copper used are copper(I) acetate, copper(I)
chloride,
copper(I) bromide, and copper(I) iodide. Phosphine complexes (specifically
bis(triphenylphosphine)copper iodide) may also be present. The materials
comprise these in
amounts of from 5 to 500 ppm of copper, preferably from 10 to 250 ppm, based
on
polyamide.
The advantageous properties are in particular obtained if the copper is
present with
molecular distribution in the polyamide. This is achieved if a concentrate
comprising the
polyamide, and comprising a salt of monovalent copper, and comprising an
alkali metal
halide, in the form of a solid, homogeneous solution is added to the molding
composition. By
way of example, a typical concentrate is composed of from 79 to 95% by weight
of polyamide
and from 21 to 5% by weight of a mixture composed of copper iodide or copper
bromide and
potassium iodide. The copper concentration in the solid homogeneous solution
is preferably
from 0.3 to 3% by weight, in particular from 0.5 to 2% by weight, based on the
total weight of
the solution, and the molar ratio of copper(I) iodide to potassium iodide is
from 1 to 11.5,
preferably from 1 to 5.
Suitable polyamides for the concentrate are homopolyamides and copolyamides,
in particular
nylon-6 and nylon-6,6.
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Suitable sterically hindered phenols E) are in principle all of the compounds
which have a
phenolic structure and which have at least one bulky group on the phenolic
ring.
It is preferable to use, for example, compounds of the formula.
R2 R3
HO 41
R1
where:
R1 and R2 are an alkyl group, a substituted alkyl group, or a substituted
triazole group, and
where the radicals R1 and R2 may be identical or different, and R3 is an alkyl
group, a
substituted alkyl group, an alkoxy group, or a substituted amino group.
Antioxidants of the abovementioned type are described by way of example in DE-
A 27 02 661 (US-A4 360 617).
Another group of preferred sterically hindered phenols is provided by those
derived from
substituted benzenecarboxylic acids, in particular from substituted
benzenepropionic acids.
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33
Particularly preferred compounds from this class are compounds of the formula
R4 R7
0
(?
HO lit CH2¨CH2.--C i
¨0¨R=0¨C¨CH2.--CH2 111 OH
R5 R5
where R4, R6, R7, and R8, independently of one another, are Ci-C8-alkyl groups
which
themselves may have substitution (at least one of these being a bulky group),
and R6 is a
divalent aliphatic radical which has from 1 to 10 carbon atoms and whose main
chain may
also have C-0 bonds.
Preferred compounds corresponding to this formula are
CH,\/CH, CH,\c/CH,
CHc'c 0 0
II II CH
HO 1110 CH2¨CH2¨C-0¨CH ¨CH ¨0-CH ¨CH ¨0-CH ¨CH¨O-C-CH2-CH2 411 OH 3
2 2 2 2 2 2
CI-13 CI-13
(Irganox0 245 from BASF SE)
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34
CH3\ / CH0 CH3\
/CH3
,C
CH' 0 0 CN
cH,
Ho3 cH2¨cH2¨c-o¨(cH2)6-o-c-cHT-cH2 OH
CH3 ,,CH3
CH3/ \ CH3
CH3 CH3
(Irganox0 259 from BASF SE)
All of the following should be mentioned as examples of sterically hindered
phenols:
2,2'-methylenebis(4-methyl-6-tert-butylphenol), 1,6-hexanediol bis[3-(3,5-di-
tert-buty1-
4-hydroxyphenyl)propionate], pentaerythrityl tetrakis[3-(3,5-di-tert-buty1-4-
hydroxypheny1)-
propionate], distearyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2,6,7-
trioxa-1-
phosphabicyclo[2.2.2]oct-4-ylmethyl 3,5-di-tert-buty1-4-hydroxyhydrocinnamate,
3,5-di-tert-
buty1-4-hydroxypheny1-3,5-distearylthiotriazylamine, 2-(2'-hydroxy-3'-hydroxy-
3',5'-di-tert-
butylpheny1)-5-chlorobenzotriazole, 2,6-di-tert-butyl-4-hydroxymethylphenol,
1,3,5-trimethy1-
2,4,6-tris(3,5-di-tert-buty1-4-hydroxybenzyl)benzene, 4,4'-methylenebis(2,6-di-
tert-
butylphenol), 3,5-di-tert-butyl-4-hydroxybenzyldimethylamine.
Compounds which have proven particularly effective and which are therefore
used with
preference are 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 1,6-hexanediol
bis(3,5-di-tert-
buty1-4-hydroxyphenyl)propionate (Irganox 259), pentaerythrityl tetrakis[3-
(3,5-di-tert-butyl-
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4-hydroxyphenyl)propionate], and also N,N'-hexamethylenebis-3,5-di-tert-buty1-
4-hydroxy-
hydrocinnamide (Irganox0 1098), and the product Irganox 245 described above
from BASF
SE, which has particularly good suitability.
5 The amount comprised of the antioxidants E), which can be used
individually or as a mixture,
is from 0.05 up to 3% by weight, preferably from 0.1 to 1.5% by weight, in
particular from 0.1
to 1% by weight, based on the total weight of the molding compositions A) to
E).
In some instances, sterically hindered phenols having not more than one
sterically hindered
10 group in ortho-position with respect to the phenolic hydroxy group have
proven particularly
advantageous; in particular when assessing colorfastness on storage in diffuse
light over
prolonged periods.
The molding compositions of the invention can comprise, as component E), from
0.05 to 5%
15 by weight, preferably from 0.1 to 2% by weight, and in particular from
0.25 to 1.5% by weight,
of a nigrosin.
Nigrosins are generally a group of black or gray phenazine dyes (azine dyes)
related to the
, indulines and taking various forms (water-soluble, oleosoluble, spirit-
soluble), used in wool
20 dyeing and wool printing, in black dyeing of silks, and in the coloring
of leather, of shoe
CA 02864942 2014-08-19
36
creams, of varnishes, of plastics, of stoving lacquers, of inks, and the like,
and also as
microscopy dyes.
Nigrosins are obtained industrially via heating of nitrobenzene, aniline, and
aniline
hydrochloride with metallic iron and FeCI3 (the name being derived from the
Latin niger =
black).
Component E) can be used in the form of free base or else in the form of salt
(e.g.
hydrochloride).
Further details concerning nigrosins can be found by way of example in the
electronic
encyclopedia Rompp Online, Version 2.8, Thieme-Verlag Stuttgart, 2006, keyword
"Nigrosin".
The thermoplastic molding compositions of the invention can comprise, as
component E),
conventional processing aids, such as stabilizers, oxidation retarders, agents
to counteract
decomposition by heat and decomposition by ultraviolet light, lubricants and
mold-release
agents, colorants, such as dyes and pigments, nucleating agents, plasticizers,
etc.
Examples of oxidation retarders and heat stabilizers are sterically hindered
phenols and/or
phosphites and amines (e.g. TAD), hydroquinones, aromatic secondary amines,
such as
CA 02864942 2014-08-19
37
diphenylamines, various substituted members of these groups, and mixtures of
these, in
concentrations of up to 1% by weight, based on the weight of the thermoplastic
molding
compositions. -
UV stabilizers that may be mentioned, the amounts of which used are generally
up to 2% by
weight, based on the molding composition, are various substituted resorcinols,
salicylates,
benzotriazoles, and benzophenones.
Materials that can be added as colorants are inorganic pigments, such as
titanium dioxide,
ultramarine blue, iron oxide, and carbon black, and also organic pigments,
such as
phthalocyanines, quinacridones, perylenes, and also dyes, such as
anthraquinones.
Materials that can be used as nucleating agents are sodium phenylphosphinate,
aluminum
oxide, silicon dioxide, and also preferably talc powder.
The thermoplastic molding compositions of the invention can be produced by
processes
known per se, by mixing the starting components in conventional mixing
apparatus, such as
screw-based extruders, Brabender mixers, or Banbury mixers, and then extruding
the same.
The extrudate can be cooled and pelletized. It is also possible to premix
individual
components and then to add the remaining starting materials individually
and/or likewise in
the form of a mixture. The mixing temperatures are generally from 230 to 320
C.
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In another preferred mode of operation, components B) and C) and also, if
appropriate, D)
and E) can be mixed with a prepolymer, compounded, and pelletized. The
resultant pellets
are then solid-phase condensed under an inert gas continuously or batchwise at
a
temperature below the melting point of component A) until the desired
viscosity has been
reached.
The thermoplastic molding compositions of the invention feature good flame
retardancy and
excellent phosphorus stability. These materials are therefore suitable for
producing fibers,
foils, and moldings of any type. Some examples are mentioned hereinafter: plug
connectors,
plugs, plug parts, cable harness components, circuit mounts, circuit mount
components,
three-dimensionally injection-molded circuit mounts, electrical connector
elements, and
mechatronic components.
The moldings or semifinished products to be produced in the invention from the
thermoplastic molding compositions can be used by way of example in the motor
vehicle
industry, electrical industry, electronics industry, telecommunications
industry, information
technology industry, entertainment industry, or computer industry, in vehicles
and other
conveyances, in ships, in spacecraft, in households, in office equipment, in
sports, in
medicine, and also generally in articles and parts of buildings which require
increased fire
protection.
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39
Improved-flow polyam ides can be used in the kitchen and household sector for
producing
components for kitchen equipment, e.g. fires, smoothing irons, buttons, and
also for garden-
and leisure-sector applications.
Examples
The following components were used:
Component A:
Nylon-6,6 with intrinsic viscosity IV 150 mL/g, measured in 0.5% by weight
solution in 96%
by weight sulfuric acid at 25 C to ISO 307 (using Ultramid A27 from BASF SE).
Component B:
50% concentrate of red phosphorus of average particle size (d50) from 10 to 30
pm in an
olefin polymer made of: 59.8% by weight of ethylene, 35% by weight of n-butyl
acrylate,
4.5% by weight of acrylic acid, and 0.7% by weight of maleic anhydride
(component D) with
melt index MFI (190/2.16) 10 g/10 min. The copolymer was produced via
copolymerization of
the monomers at elevated temperature and elevated pressure.
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Component C/1: commercially available zinc oxide (for comparison).
Component C/2:
5 Cu/Zn/AI oxide mixture catalyst:
40% by weight of CuO
40% by weight of ZnO
20% by weight of A1203
(Puristar0 R3-12 from BASF SE)
10 BET surface area: 70 m2/g
Component E/1:
Standard chopped glass fiber for polyamides, length = 4.5 mm, diameter = 10
pm.
15 Component E/2:
N,N'-Hexamethylenebis-3,5-di-tert-buty1-4-hydroxyhydrocinnamide (Irganox0
1098)
Component E/3:
Ca stearate
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41
In order to provide evidence of the phosphorus stability improvements
described in the
invention, appropriate plastics molding compositions were manufactured via
compounding.
To this end, the individual components were mixed in a ZSK 26 (Berstorff) twin-
screw
extruder with throughput 20 kg/h and a flat temperature profile at about 270
C, extruded in
the form of strand, cooled until pelletizable, and pelletized.
The test specimens for the study set out in Table 1 were injection-molded in
an Arburg 4200
injection-molding machine at a melt temperature of about 270 C and mold
temperature of
about 80 C.
Testing of plastics parts for phosphorus deposition:
A plastics specimen (125 x 12.5 x 1.6 mm) was halved, and each half was placed
in a 10 ml
glass beaker. A silver contact material (10 x 50 x 0.125 mm) was placed in a
short test tube.
The three specimens were then placed in a 100 ml screw-cap bottle, 5 ml of
water was
added, and the sealed system was placed in a drying oven at 70 C. After 28
days, the test
tube was removed and filled to the top with water, and the entire contents
were placed in a
glass beaker. 5 ml of conc. hydrochloric acid were added to this, and the
mixture was
evaporated almost to dryness. The metal specimen was then removed and rinsed
with water;
1 ml of sulfuric acid was admixed with the residue, and the mixture was again
evaporated
almost to dryness. 20 ml of water is then used for dilution, 4 ml of 5%
potassium
peroxodisulfate solution are added, and the mixture is heated for 30 minutes.
Phosphorus
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42
was then determined photometrically by using molybdenum blue, in pg of
phosphorus/plastics specimen.
The table gives the constitutions of the molding compositions and the results
of the
measurements.
Table:
Components [% by weight] Comparative example
Inventive example
A 60.6 61.05
B + D 12 12
E/1 26 26
C/1 0.7
C/2 0.25
E/2 + E/3 (50:50) 0.7 0.7
Phosphorus deposition after 150 7
28 days / 70 C in pg of
phosphorus/specimen
