MX2008008643A - Thermoplastic composition containing polycarbonate-polyester and nanoclay - Google Patents

Abstract

A thermoplastic composition comprising a resinous blend of (A) aromatic polycarbonate and (B) polyester, (C) nanoclay and (D) carboxylic acid is disclosed. The composition features improved melt stability and impact strength over correspondingcompositions that contain no acid. The nanoclay is present in an amount of 0.1 to 30 percent relative to the weight of the resinous blend, and the acid is present in an amount of 1 to 20 percent relative to the weight of the nanoclay. The average thickness of the clay particles is about 1 to 100 nm, and their average lengths and average widths, independently one of the other are 50 to 700 nm.

Description

THERMOPLASTIC COMPOSITION CONTAINING POLYCARBONATE- POLYESTER AND NANOARCILLA FIELD OF THE INVENTION The invention relates to thermoplastic molding compositions and more particularly, to clay loaded compositions containing a mixture of polycarbonate and polyester. SUMMARY OF THE INVENTION A thermoplastic composition comprising a resin mixture of (A) aromatic polycarbonate and (B) polyester, (C) nanoclay and (D) carboxylic acid is described. The composition exhibits improved melt stability and impact resistance with respect to corresponding compositions that do not contain acid. The nanoclay is present in an amount of 0.1 to 30 percent relative to the weight of the resin mixture and the acid is present in an amount of 1 to 20 percent relative to the weight of the nanoclay. The average thickness of the clay particles is from about 1 to 100 nm and their average lengths and average widths, independently of each other, from 50 to 700 nm. BACKGROUND OF THE INVENTION Polycarbonate resins are well known and have been used for a long time for a variety of applications due to their characteristic combination of good mechanical and physical properties. However, its rigidity (Bending module) is unsuitable for certain structural applications such as covers for power tools. The glass fibers incorporated in the polycarbonate have addressed this disadvantage to a great extent although they have adversely affected the appearance of the molded parts. Blends of polycarbonate with thermoplastic polyester are known. Commercial compositions containing such mixtures are commercially available, for example, in Bayer MaterilScience as Makroblend compositions. Clays with a particle size of less than 100 nm are available on the market in nanoclays. Its utility in polymeric matrices has been described extensively in the literature, for example, J. Materials Res., 1993, Volume 8, page 1179; J. Polym. Sci., Part A: Polym. Chem., 1993, volume 31, page 2493. Nanocomposites are a class of materials that have a phase having particle dimensions in the range of 1 to 100 nm. The technique has now recognized that the inclusion of these materials in polymer matrices results in compounds that have better mechanical properties than their opposites that include micro- and macro-scale particles. Polycarbonate compounds containing organically modified nanoclay (organoclay), modification by tertiary and quaternary ammonium salts, were described by P.J. Yoon, D.L. Hunter and D.R. Paul, in Polycarbonate Nanocomposites. Part 1, Effect of Organoclay Structure on Morphology and Properties, Polymer, 44, 5323 (2003), and by the same authors on Polycarbonate Nanocomposites. Part 2, Degradation and color Formation, Polymer 44, 5341 (2003). Geralda Severem Alex J. Hsieh and Bryan E. Koene described relevant polycarbonate compounds where the incorporated nanoclay had been modified with Cie and C-iß-tributyl phosphonium in an article entitled Effect of Layered Silicates on Thermal Characteristics of Polycarbonate Nanocomposites, Society of Plastics Engineers, ANTEC 2000, pages 1523-6. The technique also recognizes that swelling agents, such as long-chain organic cations, and water-soluble oligomers or polymers between adjacent layers of clay can be interspersed or absorbed and thereby increase the inter-layer separation. U.S. Patent No. 5,552,469 and WO 93/04117 among others have disclosed methods for treating relevant silicates resulting in the imparting of greater mechanical reinforcement to polymeric matrices into which they are incorporated. U.S. Patent No. 5,760,121 has disclosed nanocomposites containing a matrix polymer and exfoliated intercalates formed by contacting a phyllosilicate with a polymer to adsorb or intercalate the polymer between adjacent lamellae of phyllosilicate. Sufficient polymer is adsorbed between adjacent lamellae of phyllosilicate to expand the adjacent lamellae to a spacing of 5 to 100 angstroms in such a way that the interlayer can be exfoliated in a simple manner by mixing it with an organic solvent or a polymer melt. Also pertinent are the descriptions of U.S. Patent Nos. 5,747,560 and 5,385,776. U.S. Patent 6,610,770 has disclosed a polymer flame retardant composition made from a polymer mixed using a defined process with a smectite clay that has been reacted with a specified mixture of organic materials. It is said that the flame retardant properties depend on the degree of dispersion of a smectite organoclay in the polymer matrix. It is said that the proper functioning of the flame retardant polymeric compositions requires that the organoclay be dispersed in the polymer in such a way that it can not be fully exfoliated. further, U.S. Patent No. 6,521,690 has disclosed a composition that includes modified smectite clay with an organic chemical composition and a polymer. The composition consists of an intercalated organic chemical / smectite clay that has been ion exchanged and reacted and has been interspersed with one or more quaternary ammonium compounds and an anionic material and has been further mixed in a polymeric resin to produce a nanocomposite composition. DETAILED DESCRIPTION OF THE INVENTION Compositions containing a polymer matrix and clay are known. Although the flexural modulus of such compositions in which the matrix is polycarbonate is clearly greater than that of resin alone, a noticeable degradation, expressed in terms of the marked increase in the flow index and the decrease in impact properties, results in after extrusion the composition of these compositions and then the molding of articles therefrom. The invention is based on observations that the addition of a carboxylic acid in a small amount to a mixture of polycarbonate, polyester and nanoclay stabilizes the composition, resulting in stabilized compositions exhibiting good impact resistance.

Polycarbonates (component A) suitable in the context of the invention include homopolycarbonates, copolycarbonates and mixtures thereof. Included in the term copolycarbonate as used herein are polyestercarbonates in which the ester linkages are present in a lower molar amount with respect to the carbonate linkages. Polycarbonates are known and their structure and methods of preparation have been described, for example, U.S. Patent Nos. 3,030,331; 3,169,121; 3,395,119; 3,729,447; 4,255,556; 4,260,731; 4,369,303, 4,714,746 and 6,306,507, which are all incorporated by reference in this document. The polycarbonates generally have a weight average molecular weight of 10,000 to 200,000, preferably 20,000 to 80,000 and their melt flow rate by ASTM D-1238 at 300 ° C, under a load of 1.2 kg, is from about 1 to about 65 g / 10 min, preferably from approximately 2 to 35 g / 10 min. They can be prepared, for example, by the known process of diphasic interface from a carbonic acid derivative such as phosgene and dihydroxy compounds by polycondensation (see German Published Patent Applications 2,063,050, 2,063,052, 1,570,703).; 2,211,956; 2,211,957 and 2,248,817; French Patent No. 1,561,518; and H. Schnell's monograph, "Chemistry and Physics of Polycarbonates", Interscience Publishers, New York, New York, 1964, which all are incorporated as a reference in this document). In the present context, suitable dihydroxy compounds for the preparation of the polycarbonates of the invention are adjusted to structural formulas (1) or (2). (1) (2) wherein A denotes an alkylene group having 1 to 8 carbon atoms, an alkylidene group with 2 to 8 carbon atoms, a cycloalkylene group with 5 to 15 carbon atoms, a cycloalkylidene group with 5 to 15 carbon atoms, carbon, a carbonyl group, an oxygen atom, a sulfur atom, -SO- or -SO2- or a radical that conforms to e and g both indicate the number from 0 to 1; Z denotes F, Cl, Br or C 4 alkyl and if several Z radicals are substituents on an aryl radical, they can be identical or different from each other; d indicates an integer from 0 to 4; and f denotes an integer from 0 to 3. Among the dihydroxy compounds useful in the practice of the invention are hydroquinone, resorcinol, bis- (hydroxyphenyl) -alkanes, bis- (hydroxyphenyl) -ethers, bis- (hydroxyphenyl) -ketones, bis- (hydroxyphenyl) -sulphoxides, bis- (hydroxyphenyl) -sulfides, bis- (hydroxyphenyl) -sulphones and a, bis (hydroxyphenyl) -diiopropylbenzenes as well as their alkylated compounds in the nucleus. These and other suitable aromatic dihydroxy compounds are described, for example, in U.S. Patent Nos. 5,105,004; 5,126,428; 5,109,076; 5,104,723; 5,086,157; 3,028,356; 2,999,835; 3,148,172; 2,991,273; 3,271,367; and 2,999,846, which are all incorporated herein by reference. Further examples of suitable bisphenols are 2,2-bis- (4-hydroxyphenyl) -propane (bisphenol A), 2,4-bis- (4-hydroxyphenyl) -2-methylbutane, 1,1-bis- (4-hydroxyphenyl) ) -cyclohexane, a, a'-bis- (4-hydroxyphenyl) -p-di-propylbenzene, 2,2-bis (3-methyl-4-hydroxyphenyl) -propane, 2,2-bis (3-chloro) -4-hydroxyphenyl) -propane, bis- (3,5-dimethyl-4-hydroxyphenyl) -methane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, bis- (3,5 -dimethyl-4-hydroxy-phenyl) -sulfide, bis- (3,5-dimethyl-4-hydroxyphenyl) -sulfoxide, bis- (3,5-dimethyl-4-hydroxyphenyl) -sulfone, dihydroxybenzophenone, 2,4-bis- (3,5-dimethyl-4-hydroxyphenyl) -cyclohexane, a, a'-bis- (3,5-dimethyl-4-hydroxyphenyl) -p-diisopropyl-benzene and 4,4'-sulfonyl diphenol. Examples of particularly preferred aromatic bisphenols are 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, 1,1-bis- ( 4-hydroxyphenyl) -cyclohexane and 1,1-bis- (4-hydroxyphenyl) -3,3,5 trimethylcyclohexane. The most preferred bisphenol is 2,2-bis- (4-hydroxyphenyl) -propane (bisphenol A). The polycarbonates of the invention may include in their structure units derived from one or more of the suitable bisphenols. Among the resins suitable in the practice of the invention are polyester carbonates based on resorcinol and bisphenol A (registration number 265997-77-1), polycarbonate based on phenolphthalein, copolycarbonates and terpoly carbonates such as are described in U.S. Patent Nos. 6,306,507, 3,036,036 and 4,210,741, all incorporated by reference herein. The polycarbonates of the invention can also be branched by condensing in the same small amounts, for example, from 0.05 to 2.0% mol (with respect to the bisphenols) of polyhydroxyl compounds. Polycarbonates of this type have been described, for example, in the German Published Patent Applications 1,570,533.; 2,116,974 and 2,113,374; British Patents No. 885,442 and 1,079,821 and United States Patent No. 3,544,514. Below are some examples of polyhydroxyl compounds that can be used for that purpose: phloroglucinol; 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptane; 1, 3,5-tri- (4-hydroxyphenyl) -benzene; 1,1,1- tri- (4-hydroxyphenyl) -ethane; tri- (4-hydroxyphenyl) -phenylmethane; 2,2-bis- [4,4- (4,4, -d-hydroxydiphenyl)] - cyclohexyl-propane; 2,4-bis- (4-hydroxy-1-isopropylidino) -phenol; 2,6-bis- (2'-dihydroxy-5'-methylbenzyl) -4-methylphenol; 2,4-dihydroxybenzoic acid; 2- (4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) -propane and 1,4-bis- (4,4'-dihydroxytriphenylmethyl) -benzene. Some of the other polyfunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanide chloride and 3,3-bis- (4-hydroxy-phenyl) -2-oxo-2,3-dihydroindole. In addition to the polycondensation process mentioned above, other processes for the preparation of the polycarbonates of the invention are polycondensation in a homogeneous phase and transesterification. Suitable processes are described in the United States Patents incorporated herein by reference No. 3,028,365; 2,999,846; 3,153,008; and 2,991,273. The preferred process for the preparation of polycarbonates is the interfacial polycondensation process. Other synthesis methods can be used to form the polycarbonates of the invention, such as those described in U.S. Patent No. 3,912,688, incorporated herein by reference.

Suitable polycarbonate resins are commercially available, for example, Makrolon 2400, Makrolon 2458, Makrolon 2600, Makrolon 2800 and Makrolon 3100, which are all bisphenol-based homopolycarbonate resins that differ in terms of their respective molecular weights and which are characterized in that their melt flow rates (MFR at 300 ° C, 1.2 kg) per ASTM D-1238 are approximately 16.5 to 24, from 13 to 16, from 7.5 to 13.0 and from 3.5 to 6.5 g / 10 min, respectively. These are products of Bayer MateriaIScience LLC of Pittsburgh, Pennsylvania. The polyester, component (B), suitable in the present context includes resins of homo-polyesters and with-polyesters and mixtures thereof. Included in the term "polyesters" as used herein are polyester carbonates in which the carbonate bonds are present in a lower molar amount with respect to the ester linkages. These known resins can be prepared by condensation or ester exchange polymerization of the diol component with the diacid according to known methods. Examples are esters obtained from the condensation of a cyclohexanedimethanol with an ethylene glycol with a terephthalic acid or with a combination of terephthalic acid and isophthalic acid. Also suitable are polyesters obtained from the condensation of a cyclohexanedimethanol with an ethylene glycol with a 1,4-cyclohexanedicarboxylic acid. Suitable resins include poly (alkylene dicarboxylates), especially poly (ethylene terephthalate) (PET), poly (1,4-butylene terephthalate) (PBT), poly (trimethylene terephthalate) (PTT), poly (ethylene naphthalate) (PEN), poly (butylenenaphthalate) (PBN), poly (cyclohexanedimethanol terephthalate) (PCT), poly (cyclohexanedimethanol-co-ethylene terephthalate) (PETG or PCTG) and poly (1,4-cyclohexanedimethyl-1,4-cyclohexanedicarboxylate) (PCCD).

U.S. Patent Nos. 2,465,319, 3,953,394 and 3,047,539, all incorporated by reference herein, describe suitable methods for preparing such resins. Suitable polyalkylene terephtalates are characterized by an intrinsic viscosity of at least 0.2 and preferably at least 0.4 deciliters / gram as measured by the relative viscosity of an 8% solution in orthochlorophenol at about 25 ° C. The upper limit is not critical but generally does not exceed approximately 2.5 deciliters / gram. Especially preferred polyalkylene terephthalates are those which have an intrinsic viscosity in the range of 0, 4 to 1, 3 deciliters / gram. The alkylene units of the polyalkylene terephthalates which are suitable for use in the present invention contain from 2 to 5, preferably from 2 to 4, carbon atoms. Polybutylene terephthalate (prepared from 1,4-butanediol) and polyethylene terephthalate are the preferred polyalkylene terephthalates for use in the present invention. Other suitable polyalkylene terephthalates include polypropylene terephthalate, polyisobutylene terephthalate, polypentilterephthalate, polyisopentylterephthalate and polyneopentylterephthalate. The alkylene units may be straight chains or branched chains. The component (C) of the inventive composition is clay, whose particle size is in the order of nanometers (in this document nanoclay). The nanoclay is known and described in U.S. Patent No. 5,747,560 which is incorporated herein by reference. Preferred clays include natural or synthetic phyllosilolates such as montmorillonite, hectorite, vermiculite, beidilite, saponite, nontronite or synthetic fluoromica. A preferred nanoclay is illustrated by montmorillonite, hectorite or synthetic fluoromica, more preferably montmorillonite or hectorite and much more preferably montmorillonite. The nanoclay preferably has a median lamella thickness in the range of about 1 nm to about 100 nm and a mean length and average width ranging from about 50 nm to about 700 nm each. In the preferred embodiment, the clay has been modified by a cation exchange reaction with a suitable organic salt such as ammonium salt, phosphonium and quaternary imidazolium. Suitable quaternary ammonium salts are structurally adjusted to R. where R ^ denotes a linear or branched aliphatic or aromatic hydrocarbyl or hydroxyalkyl radical containing from 1 to 40 carbon atoms, R2, R3 and R independently denote any hydrocarbon radical or straight or branched aliphatic or aromatic hydroxyalkyl radical containing from 1 to 40 carbon atoms, oligomeric or polymeric alkylene oxide or oligomeric or polymeric alkylene ester. Suitable counter-anions of the quaternary ammonium cation are chlorine, bromine, iodine, methylsulfate or acetate. Suitable quaternary phosphonium salts are structurally adjusted to R, - p - R4 and FU where R ^ denotes a linear or branched aliphatic or aromatic hydrocarbon or hydroxyalkyl radical containing from 1 to 40 carbon atoms, R2, R3 and R independently denote any linear or branched aliphatic or aromatic hydrocarbon or hydroxyalkyl radical containing from 1 to 40 carbon atoms, oligomeric or polymeric alkylene oxide or oligomeric or polymeric alkylene ester and wherein the counter anion is a member selected from the group consisting of chlorine, bromine, iodine, methylsulfate and acetate. Organically modified nanoclays are available commercially from Southern Clay Products, Inc. and Nanocor, Inc. under the trademarks Cloisite and Nanomer, respectively. The preferred modified nanoclays, modified with quaternary ammonium salts, are Cloistite of Southern Clay qualities 10A, 20A and 25A. The acid used as component (D) of the inventive composition is a carboxylic acid. Suitable acids include both aliphatic and aromatic acids. Fatty acids, both saturated and unsaturated, are included in the appropriate acids. Preferably, the carboxylic acid is aliphatic and most preferably contains from 2 to 30 carbon atoms. Citric acid is used advantageously.

The acid is used in the practice of the invention in an amount of 1 to 20, preferably 5 to 15, more preferably 8 to 12 percent relative to the weight of the nanoclay. The preparation of the inventive composition is conventional and follows procedures and uses apparatus known to those skilled in the art. The invention is further illustrated but is intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified. EXAMPLES Compositions were prepared according to the present invention and their properties were evaluated. The preparation of these compositions and their test were conventional; the properties are tabulated below. The components used for the preparation of the compositions illustrated were: Polycarbonate 1: Makrolon 5208, a homopolycarbonate in powder form based on bisphenol-A having a melt index (MFR) of 5.5 g / 10 min per ASTM D 1238 with a load of 1, 2 kg at 300 ° C), a product of Bayer MateriaIScience LLC. Polycarbonate 2: Makrolon 3208 homopolycarbonate based on bisphenol A having a melt index of about 5.1 g / 10 min per ASTM D 1238 with a loading of 1.2 kg at 300 ° C), a product of Bayer Polymers LLC. PET: Polyethylene terephthalate, Versatray 12822, a product of Voridian, which has an intrinsic viscosity of 0.92 to 0.98.

Clay: Cloisite 25A, a natural montmorillonite modified with a dimethyl quaternary ammonium salt, hydrogenated tallow and 2-ethylhexyl with a methylisulfate as an anion, product of Southern Clay Products. The citric acid that was used in the course of the experiments was of chemically pure quality. The melt index of the compositions was determined in accordance with ASTM D 1238 with a load of 1.2 kg at 300 ° C. The instrumented (multi-axle) impact resistance was determined using an Instron instrumented impact tester with a 7.62 cm (3 inch) platform and a 1.27 cm (0.5 inch) pylon hammer with a speed of 24.14 km / h (15 mph) dart. The thickness of all the test samples was 3.18 cm (1/8") Table 1 1A 1 B 1C 1 D 1 E 1 F Polycarbonate 1,% at 5.0 5.0 5.0 5.0 5.0 0.0 weight Polycarbonate 2,% at 95.0 75.0.0.0 35.0.0.0.0.0.0.0 PET weight, % by weight 0.0 20.0 40.0 60.0 80.0 100.0 Properties: melt index, g / 10 min 5.5 8.0 8.3 6.1 5.3 31, 3 Bending module, MPa 2403.3 2474.3 2499.2 2512.9 2515.7 2455.0 Bending tension,% 7.5 6.8 6.4 5.7 5.7 5.2 Resistance to bending at 5% tension, MPa 94.5 99.4 97.9 97.9 96.6 91, 1 Resistance to bending, final, MPa 104.2 106.3 102.8 100.1 97.9 91, 1 Impact strength, Izod, at 3.18 cm Without notch, J 85.7 76.2 70.0 77.2 70.6 70.2 Impact resistance, instrumented (total energy) at 3.18 cm, at 230C, J 77.0 68.7 62.6 64.1 66.0 60.3 Table 1 shows the properties of the compositions containing polycarbonate and polyester. Consequently, the inclusion of polyester (PET) leads to an increase in flexural modulus and a significant decrease in impact properties. Table 2 2A 2B 2C 2D 2E 2F Polycarbonate 1,% in 5.0 5.0 5.0 5.0 5.0 0.0 weight Polycarbonate 2,% in 90.0 71, 0 52.0 33.0 14.0 0.0 0.05 PET weight, % by weight 0.0 19.0 38.0 57.0 76.0 95.0 Clay,% by weight 5.0 5.0 5.0 5.0 5.0 5.0 Properties: melt index, g / 10 min 31, 5 40.0 32.8 25.7 30.3 79.8 Bending module, MPa 3072.6 3208.6 3296.1 3298.9 3343.1 3387, 2 Bending tension,% 6.2 5.9 5.5 5.2 4.2 4.8 Resistance to bending at 5% tension, MPa 111, 1 115.2 113.2 111, 1 111, 1 Nd3 Resistance to bending, final, MPa 114.5 117.3 113.2 111, 1 110.4 93.8 Resistance to impact, Izod, at 3.18 cm without notch, J 37.7 28.6 80.5 41, 9 20.5 8.9 Impact resistance, instrumented (total energy) at 3.18 cm, at 23 ° C, J 27.3 37.6 54.8 10.0 2.6 1, 3 3- less than 5% tension The comparison of the results shown in Tables 2 and 3 suggests that the increase of the fusion and the decrease in impact resistance caused by the addition of clay are mitigated by the inclusion of acid according to the invention. Table 3 3A 3B 3C 3D 3E 3F Polycarbonate 1,% at 5.0 5.0 5.0 5.0 5.0 0.0 weight Polycarbonate 2,% at 89.5 70.6 51, 7 32.8 13 , 9 0.0 PET weight 0.0 18.9 37.8 56.7 75.6 94.5 Clay 5.0 5.0 5.0 5.0 5.0 5.0 Citric acid 0,5 0,5 0,5 0,5 0,5 0,5 Properties: melt index, g / 10 min 6.4 13.1 16.3 19.2 27.0 69.1 Bending module, MPa 3061, 5 3285.8 3307.2 3317.5 3248.5 3367, 2 Bending tension,% 6.1 5.9 5.7 5.5 4.8 3.8 Resistance to bending at 5% tension, MPa 112.5 117.3 114.5 112.5 109.7 Nd (3) Resistance to bending, final, MPa 115,92 118,7 115,9 113,16 109,0 98,7 Resistance to impact, Izod, at 3.18 cm without notch, J 85.2 81, 4 81, 4 42.6 22.4 9.4 Impact resistance, instrumented (total energy) at 3.18 cm, at 23 ° C, J 59.3 60.8 60.8 42.8 3.1 1, 2 (3) - less than 5% tension The inventive composition is demonstrated by Examples 3B, 3C, 3D and 3E.

Although the invention has been described in detail above for the purpose of illustration, it is to be understood that such detail is only for that purpose and that variations may be made therein by those skilled in the art without departing from the spirit and scope of the invention. invention except for what may be limited by the claims.

Claims (14)

1. A thermoplastic composition comprising aromatic polycarbonate, polyester, nanoclay and carboxylic acid in which the nanoclay is present in an amount of 0.1 to 30 percent relative to the total weight of the polycarbonate and polyester, and wherein the amount of acid it is about 1 to 20 percent relative to the weight of the nanoclay, said nanoclay having an average lamella thickness of 1 to 100 nm and an average length and average width, independently of each other, of 50 to 700 nm.

2. The thermoplastic molding composition of claim 1 wherein the polycarbonate is present in an amount of 99 to 10 percent and the polyester is present in an amount of 1 to 90 percent, the percentages, both presentations, being relative to the weight of the composition.

3. The thermoplastic molding composition of claim 1 wherein the polycarbonate is present in an amount of 99 to 20 percent and the polyester is present in an amount of 1 to 80 percent, with the percentages, both presentations, being relative to the weight of the composition.

4. The thermoplastic molding composition of claim 1 wherein the amount of the nanoclay is from 0.1 to 15 percent.

5. The thermoplastic molding composition of claim 1 wherein the nanoclay is montmorillonite modified with a quaternary ammonium salt or a quaternary phosphonium salt.

6. The thermoplastic molding composition of claim 5 wherein the quaternary ammonium salt is structurally adjusted to R 2 where Ri denotes a linear or branched aliphatic or aromatic hydrocarbyl or hydroxyalkyl radical containing from 1 to 40 carbon atoms, R2, R3 and R independently denote any hydrocarbon radical or straight or branched aliphatic or aromatic hydroxyalkyl radical containing from 1 to 40 carbon atoms, oligomeric or polymeric alkylene oxide or oligomeric or polymeric alkylene ester and wherein the counter anion is a member selected from the group consisting of chlorine, bromine, iodine, methylisulfate or acetate.

7. The thermoplastic molding composition of claim 5 wherein the quaternary phosphonium salt is structurally adjusted to where Ri denotes a linear or branched aliphatic or aromatic hydrocarbyl or hydroxyalkyl radical containing from 1 to 40 carbon atoms, R2, R3 and R independently denote any hydrocarbon radical or straight or branched aliphatic or aromatic hydroxyalkyl radical containing from 1 to 40 carbon atoms, oligomeric or polymeric alkylene oxide or oligomeric or polymeric alkylene ester and wherein the counter anion is a member selected from the group consisting of chlorine, bromine, iodine, methylisulfate or acetate.

8. The thermoplastic molding composition of claim 1 wherein the acid is carboxylic acid.

9. The thermoplastic molding composition of claim 8 wherein the carboxylic acid is aliphatic.

10. The thermoplastic molding composition of claim 9 wherein the carboxylic acid is citric acid.

11. The thermoplastic molding composition of claim 1 wherein the amount of acid is 5 to 15 percent relative to the weight of the nanoclay.

12. The thermoplastic molding composition of claim 1 wherein the amount of acid is from 8 to 12 percent relative to the weight of the nanoclay.

13. The thermoplastic molding composition of claim 1 wherein the nanoclay is a member selected from the group consisting of montmorillonite, hectorite and synthetic fluoromica.

14. The thermoplastic molding composition of claim 1 wherein the nanoclay is montmorillonite.