Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-05-09
2002-10-01
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S444000, C524S445000, C523S201000
Reexamination Certificate
active
06458879
ABSTRACT:
The invention relates to thermoplastic nanocomposites with advantageously balanced mechanical properties.
Composite materials made from organic polymers, such as polyamides, and from layer-type silicates are known. These materials have high stiffness. However, while addition of the phyllosilicates improves stiffness it also reduces toughness.
EP-B 0 387 903 therefore proposes the use of impact modifiers in thermoplastic polypropylene resin compositions. The compositions disclosed comprise a modified polypropylene, for example grafted with unsaturated carboxylic acids, and comprise a polyamide modified with clay minerals and also an ethylene-&agr;-olefin copolymer rubber or a derivative thereof and/or a block polymer and/or an inorganic filler. No specific rubber is disclosed for increasing impact resistance.
EP-B 0 352 042 describes a highly rigid and impact-resistance resin mixture made from a polyamide resin composite material which is composed of, alongside a layered silicate, a polyphenyl ether resin and/or a resin which improves impact resistance but is not further defined. The particle sizes of the resin which improves impact resistance are not defined.
It is an object of the present invention to provide thermoplastic nanocomposites with advantageously balanced mechanical properties. These should have improved mechanical and processing properties, in particular excellent stiffness and at the same time excellent toughness.
We have found that this object is achieved by thermoplastic nanocomposites, comprising
a) a thermoplastic (A),
b) at least one compound (B) (delaminated phyllosilicate), whose structure has been built up from negatively charged phyllosilicates and from cations embedded between these, and which have been dispersed uniformly in component (A), and
c) a rubber or rubber mixtures (C),
wherein component (C) has a particle size distribution with a d(50) value of from 10 to 1000 nm.
These fine-particle rubbers or rubber mixtures (C) used according to the invention have dimensions similar to those of the phyllosilicates used. The dispersion achieved of the phyllosilicates in the thermoplastic is therefore improved.
This improvement in toughness while retaining stiffness in the novel thermoplastics is surprising, since fine-particled rubbers or rubber mixtures of this type as used according to the invention do not bring about any significant increase in toughness in thermoplastic polymer compositions in which no phyllosilicates are present.
The fine-particle rubbers or rubber mixtures (C) used according to the invention have a particle size distribution with a d(50) value of from 10 to 1000 nm, preferably from 15 to 500 nm, particularly preferably from 20 to 250 nm. The dimensions of these rubber particles therefore correspond to those of delaminated phyllosilicates, which usually have a maximum side length of from 200 nm to 2 &mgr;m and a thickness of from 8 to 100 Å.
The d(50) value here is defined as the value at which 50% by weight of the particles have a diameter greater, and 50% by weight of particles have a diameter smaller than this value.
The proportion of component (C) used, based on the total weight of the thermoplastic nanocomposites, is small. Use is generally made of from 0.1 to 15% by weight, preferably from 1 to 10% by weight and particularly preferably from 2 to 4% by weight, of component (C), based on the total weight of the thermoplastic nanocomposite.
Component (C) is used in the novel thermoplastic nanocomposites to increase impact resistance. No significant impairment, and preferably no impairment at all, of the stiffness or strength of the thermoplastic nanocomposites results from the use of component (C).
The novel thermoplastic nanocomposites preferably comprise
a) from 10 to 99.89% by weight of component (A),
b) from 0.01 to 15% by weight, preferably from 1 to 12% by weight, particularly preferably from 2 to 7% by weight of component (B),
c) from 0.1 to 15% by weight, preferably from 1 to 10% by weight, particularly preferably from 2 to 4% by weight, of component (C),
d) from 0 to 50% by weight of other fillers (D), and
e) from 0 to 50% by weight of other additives (E),
where the total of all of the components is 100% by weight.
Component A: Thermoplastics
The thermoplastics have preferably been selected from the group consisting of polyamides, vinyl polymers, polyesters, polycarbonates, polyaldehydes and polyketones. The thermoplastics are particularly preferably polyamides. Possible polyamide-forming monomers are lactams, such as &egr;-caprolactam, enantholactam, caprylolactam and laurolactam, and also mixtures of these, preferably &egr;-caprolactam. Examples of other polyamide-forming monomers which may be used are dicarboxylic acids, such as alkanedicarboxylic acids having from 6 to 12 carbon atoms, in particular from 6 to 10 carbon atoms, such as adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid, and also terephthalic acid and isophthalic acid, diamines, such as C
4
-C
12
-alkyl diamines, in particular having from 4 to 8 carbon atoms, such as hexamethylenediamine, tetramethylenediamine and octamethylenediamine, and also m-xylylenediamine, bis(4-aminophenyl)methane, 2,2-bis(4-aminophenyl)propane and bis(4-aminocyclo-hexyl)methane, and also mixtures of dicarboxylic acids and diamines in any desired combination within each group but preferably in an equivalent ratio each to the other, for example hexamethylenediammonium adipate, hexamethylenediammonium terephthalate and tetramethylenediammonium adipate, preferably hexamethylenediammonium adipate and hexamethylenediammonium terephthalate. Particular industrial importance is attached to polycaprolactam and polyamides built up from caprolactam, hexamethylenediamine, isophthalic acid and/or terephthalic acid. Monomers suitable for preparing vinyl polymers are ethylene, propylene, butadiene, isoprene, chloroprene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, styrene, &agr;-methylstyrene, divinylbenzene, acrylic acid, methacrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, acrylamide, methacrylamide, ethylacrylamide, n-propylacrylamide, isopropylacrylamide, acrylonitrile, vinyl alcohol, norbomadiene, N-vinylcarbazole, vinylpyridine, 1-butene, isobutene, vinylidene cyanide, 4-methyl-1-pentene, vinyl acetate, vinyl isobutyl ether, methyl vinyl ketone, vinyl vinyl ketone, methyl vinyl ether, vinyl vinyl ether, vinyl vinyl sulfide and acrolein. These monomers may be used alone or in combination with one another. Preferred vinyl polymers are polystyrene, in particular syndiotactic polystyrene, polyethylene, polypropylene and polyvinyl chloride.
Polyesters are also suitable thermoplastics, preferably those based on terephthalic acid and diols, particularly preferably polyethylene terephthalate and polybutylene terephthalate.
Other suitable thermoplastics are polycarbonates, polyketones and polyaldehydes, such as polyoxymethylene.
Component B: Phyllosilicates
Phyllosilicates are generally understood to be silicates in which the SiO
4
tetrahedra have been bonded in infinite two-dimensional networks. (The empirical formula for the anion is (Si
2
O
5
2−
)
n
. The individual layers having bonding to one another via the cations lying between them, and the cations mostly present in the phyllosilicates which occur naturally are Na, K, Mg, Al or/and Ca.
Examples which should be mentioned of synthetic and naturally occurring phyllosilicates are montmorillonite, smectite, illite, sepiolite, palygorskite, muscovite, allevardite, amesite, hectorite, fluorohectorite, saponite, beidellite, talc, nontronite, stevensite, bentonite, mica, vermiculite, fluorovermiculite, halloysite and fluorine-containing synthetic varieties of talc.
For the purposes of the present invention, a delaminated or hydrophobicized ph
Grutke Stefan
Mc Kee Graham Edmund
Mehler Christof
BASF - Aktiengesellschaft
Cain Edward J.
Keil & Weinkauf
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