Thermoplastic nanocomposites

Details Thermoplastic nanocomposites Thermoplastic nanocomposites

2001-07-02

2004-01-06

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...

C524S446000, C524S447000, C524S186000

Reexamination Certificate

active

06673860

ABSTRACT:

This application is a 371 of PCT/EP00/00967 filed Feb. 7, 2000.
The invention relates to thermoplastic nanocomposites with an advantageously balanced mechanical property profile.
Composite materials made from organic polymers, such as polyamides, and from phyllosilicates are known. These materials have high stiffness. However, while addition of the phyllosilicates improves stiffness, it reduces toughness.
It is usual for a stable mixture of the organic material with the inorganic material to be achieved by using an upstream step to modify the inorganic material.
WO 93/04117 relates to composite materials which have a polymer matrix and, dispersed therein, lamellar particles, preferably phyllosilicates. The particles are associated with onium compounds of the formulae
+
NH
3
R
1
,
+
NH
2
R
2
R
3
,
+
PR
4
R
5
R
6
R
7
,
thus being hydrophobicized. The hydrophobicization step carried out is upstream of the mixing with the polymer.
DE-A 43 21 247 relates to polyamide resin compositions which comprise a polyamide component and an inorganic filler. Known silane coupling agents may be applied to the inorganic fillers in an upstream step in order to give stable mixing of the polyamide and the inorganic fillers.
It is an object of the present invention to provide thermoplastic nanocomposites with a balanced and advantageous mechanical property profile, dispensing with any modification of the inorganic material by way of an upstream step, such as hydrophobicization of the phyllosilicates used.
We have found that this object is achieved by way of thermoplastic nanocomposites comprising
a) a thermoplastic (A), in which from 0.1 to 10% by weight of the monomer units present in component (A) bear ionic groups, and
b) at least one phyllosilicate (B), uniformly dispersed in component (A).
The proportion of the monomer units present in component (A) which bear ionic groups is preferably from 2 to 8% by weight, particularly preferably from 4 to 6% by weight.
Injection moldings made from the thermoplastic nanocomposites of the invention have higher heat resistance, higher strength, and higher stiffness than those produced from known thermoplastic nanocomposites.
In comparison with glass-fiber-reinforced thermoplastics, an improvement is achieved in the surface of moldings produced from the thermoplastic nanocomposites, with comparable mechanical properties, with a lower filler content.
The thermoplastic nanocomposites of the invention preferably comprise
a) from 30 to 99.99% by weight, preferably from 30 to 79% by weight, particularly preferably from 30 to 68% by weight, of component (A),
b) from 0.01 to 20% by weight, preferably from 1 to 15% by weight, particularly preferably from 4 to 10% by weight, of component (B),
c) from 0 to 50% by weight, preferably from 10 to 30% by weight, particularly preferably from 15 to 20% by weight, of other fillers (C), and
d) from 0 to 50% by weight, preferably from 10 to 30% by weight, particularly preferably from 15 to 20% by weight, of other additives (D),
where all of the components together give 100% by weight.
COMPONENT A
Thermoplastics
The thermoplastics are preferably those selected from polyamides, vinyl polymers, polyesters, polycarbonates, polyaldehydes and polyketones. Polyamides are particularly preferred.
Possible polyamide-forming monomers are lactams, such as &egr;-caprolactam, enantholactam, capryllolactam and laurolactam, and also mixtures of these, preferably &egr;-caprolactam. Examples of other polyamide-forming monomers which may be used are dicarboxylic acids, for example 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 or sebacic acid, or else terephthalic acid or isophthalic acid, diamines, for example C
4
-C
12
-alkyldiamines, in particular having from 4 to 8 carbon atoms, such as hexamethylenediamine, tetramethylenediamine, or octamethylenediamine, or else m-xylylenediamine, bis(4-aminophenyl)methane, 2,2-bis(4-aminophenyl)propane, or bis(4-aminocyclohexyl)methane, or else 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 or tetramethylenediammonium adipate, preferably hexamethylenediammonium adipate or hexamethylenediammonium terephthalate. Particular industrial importance is attached to polycaprolactam, to polyamides composed of hexamethylenediamine and adipic acid, to polyamides composed of &egr;-caprolactam, hexamethylenediamine, isophthalic acid and/or terephthalic acid, in particular nylon-6 (from &egr;-caprolactam) and nylon-6,6 (from hexamethylenediamine/adipic 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, methyl acrylate, 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, norbornadiene, 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.
According to the invention, from 0.1 to 10% by weight, preferably from 2 to 8% by weight, particularly preferably from 4 to 6% by weight, of the monomer units present in component (A) bear ionic groups.
This achieves stable mixing of the inorganic material with the thermoplastic without any need for modification of the inorganic material in an upstream step.
Preferred ionic groups are anionic groups, such as carboxylates, sulfonates, and phosphates, as long as it is possible to prepare the appropriate monomers suitable for polymerization. The ionic groups in the monomer units are particularly preferably carboxylates or sulfonates. The sodium salt of sulfoisophthalic acid is very particularly preferred.
Examples of suitable appropriate monomers are tri- and tetracarboxylic acids, and also carboxylic dianhydrides, and salts of tri- or tetrasulfonic acids.
Examples of tricarboxylic acids are benzene-1,2,3-tricarboxylic acid, 2-methylbenzene-1,3,5-tricarboxylic acid, trimellitic acid (benzene-1,2,4-tricarboxylic acid), and cis,cis-1,3,5-trimethyl-cyclohexane-1,3,5-tricarboxylic acid.
Examples of tetracarboxylic acids are cyclopentane-1,2,3,4-tetracarboxylic acid, cyclobutane-1,2,3,4-tetracarboxylic acid, and 2,2-dimethylcyclo-butane-1,1,3,3-tetracarboxylic acid.
Examples of suitable carboxylic dianhydrides are pyromellitic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, and 3,3,4,4-biphenyltetracarboxylic dianhydride.
Examples of suitable salts of tri- or tetrasulfonic acids are the trisodium salt of naphthalene-1,3,6-trisulfonic acid, the trisodium salt of 8-tetradecyloxypyrene-1,3,6-trisulfonic acid, and the tetrasodium salt of pyrene-1,3,6,8-tetrasulfonic acid.
It is preferable to use carboxylic dianhydrides, and particular preference is given to pyromellitic dianhydride.
In the aqueous polymerization solution, the monomers mentioned are present in the form

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