WO2008084013A2

WO2008084013A2 - Polyamide nanocomposite

Info

Publication number: WO2008084013A2
Application number: PCT/EP2008/050062
Authority: WO
Inventors: Sachin Jain; Hans-Helmut Görtz; Claus Gabriel; Philippe Desbois
Original assignee: Basf Se
Priority date: 2007-01-11
Filing date: 2008-01-04
Publication date: 2008-07-17
Also published as: WO2008084013A3

Abstract

The invention relates to a nanocomposite which comprises a polyamide component (A) and a nanoparticulate component (B), wherein nanoparticulate component (B): a) is based on at least one oxide or mixed oxide/ oxide hydrate of one or more metals or half metals M, b) has a mean particle diameter of up to 10 nm, and c) is obtainable in a process comprising sol-gel synthesis that is carried out in the presence of an acid. The invention also relates to methods of making polyamide nanocomposites and to the use of nanoparticulate components to increase the flow of polyamide containing melts. The invention furthermore relates to molded parts made of the nanocomposite and to the use of a nanocomposite to produce thin-walled molded parts.

Description

Polyamide nanocomposite

Description

The invention relates to a nanocomposite which comprises a polyamide component (A) and a nanoparticulate component (B), wherein nanoparticulate component (B)

(a) is based on at least one oxide or mixed oxide/ oxide hydrate of one or more metals or half metals M, (b) has a mean particle diameter of up to 10 nm, and

(c) is obtainable in a process comprising sol-gel synthesis that is carried out in the presence of an acid.

The invention also relates to methods of making polyamide nanocomposites and to the use of nanoparticulate components to increase the flow of polyamide containing melts. The invention furthermore relates to molded parts made of the nanocomposite and to the use of a nanocomposite to produce thin-walled molded parts.

Preferred embodiments are outlined in the claims and in the description. Combinations of preferred embodiments are within the scope of the present invention.

High-molecular weight polyamides generally have a high melt viscosity and poor melt flow behavior. High-molecular weight polyamides do however have very good mechanical properties, in particular high values of impact resistance, stiffness, deforma- tion resistance and dimensional stability on heating, elongation at break and modulus of elasticity.

For the purpose of improving the mechanical properties even further the polyamide is often mixed with inorganic fillers such as glass fibers, impact modifiers or nanoparticu- late clay minerals. However, this typically leads to even further deterioration of the flow behavior, so that it becomes difficult to injection-mold large or thin-walled molded parts that also have an optically perfect surface. Obtaining a high-molecular polyamide composition with good flow behavior and with the typical polyamide properties being retained is of great importance for the purpose of obtaining films, fibers or molded parts, in particular thin-walled molded parts, that are obtained with the aid of the injection- molding process.

WO-2006/027123 A1 describes thermoplastic polyamide composite materials having improved flow properties for producing molded parts. The composite materials of this application are based on polyamides and fillers in the range of less than 1 Micron, especially layered silicates. The reduced melt viscosity has been attributed to slipping of the material at the walls of the mold. Another publication (Cho et al., Polymer 42 (2001 ), 1083-1094) attributes the occurrence of shear thinning behavior in polyamide/organoclay nanocomposite melts to a slip of the exfoliated platelets and the polyamide matrix during high shear flow or to molecular degradation.

A slip at high rates of shear induces instability of the flow of the polymer melt, resulting in defects and deterioration of mechanical properties of molded products subsequently obtained. A reduced melt viscosity of polyamide compositions at high shear rates with- out such slip effect would be desirable.

Polyamide nanocomposites based on synthetic oxide or oxide hydrate fillers are known per se.

WO-2004/104082 A2 discloses a composition which comprises a matrix-forming substance and at least 5 % by weight of nanoparticles with increased surface charge, the composition showing a non-Newtonian flow behavior. Polyamide is mentioned as one suitable matrix-forming substance, even though functionalized polymers that are cross- linkable such as organically modified inorganic polycondensates are preferred. The compositions disclosed exhibit an increased melt viscosity when nanofiller is present. As suitable nanoparticulate component, oxides and oxidhydrates of a wide range of metals or half metals, including Siθ2 and Tiθ2 are described. The possibility of producing the particles by a sol-gel process is mentioned.

EP-A 97108006 describes molded material containing polyamide and a nanodisperse filler. The material is especially suitable as packaging material because of its low permeability for oxygen, water, fat and other components of food. As additives, oxides or oxidhydates of metals and half metals in a concentration of 0,1 to 10 % by weight are proposed, and a broad range of particle sizes from at least 0,5 nm to below 1 Micron are mentioned. The filler can be produced in-situ as well as added subsequently to the polyamide, can be surface modified, and can for instance be derived from sol-gel synthesis. No further details on the nanoparticles are given.

DE-O 10 2004 029 303 A1 relates to a process for manufacturing highly concentrated, transparent and stable TiO2 dispersions with a particle size distribution between 2 and 50 nm. The dispersion is obtained by a sol-gel process comprising the acid catalyzed hydrolysis of a titanium alkoholate, and is stabilized with alkyl trialkoxy silanes. The TiO2 particles can be synthesized in-situ or added subsequently to a polymer matrix, for instance a polyamide leading to a transparent thermoplastic material. No further details on the nanocomposites are given, especially no details on melt flow behavior. The effect of a decrease of the melt viscosity in nanocomposites is known from polyole- fins. WO-2006/089676 A1 discloses nanocomposites comprising a polyolefin and up to 8 % by weight of a nanofiller based on oxides of Si, Ti, Zr, Sn, or Al. The nanofiller is obtained by a sol-gel process. The nanocomposite has improved processing character- istics and a reduced dynamic viscosity in a certain concentration range of the nanofiller. The particles used are mesoporous (pore size from 2 to 50 nm) and exhibit an average particle diameter of 5 to 250 nm. The decrease of the dynamic viscosity of polyolefins has been attributed to a selective adsorption of high molecular weight chains on the surface of the mesoporous nanofiller.

Compared to polyamides, polyolefins have a very different chemical and molecular structure resulting in different physical properties. The latter material involves hydrogen bonds leading for instance to melt flow crystallization, and also often involves lower molecular weight and a smaller radius of gyration. In the case of polyamides, the nano- particles for instance would be expected to strongly interact via hydrogen bonds and therefore increase melt viscosity.

It is the object of this invention to provide a polyamide composite material with mechanical properties that are substantially unchanged or improved compared to the polyamide without such modification, and which polyamide composite material shows improved processing characteristics, especially a decreased melt viscosity.

It is a further aspect of the invention to obtain a decrease in the melt viscosity using a minimal amount of a modifier. It is another object of the invention to provide a polyam- ide composite with improved processing properties, especially with improved melt flow, with no degradation of macromolecular chains occurring under extrusion conditions. It also has been an object to avoid agglomeration of nanoparticles during extrusion. It has been yet another object to avoid shear thinning by shear-induced slip of polymer chains in the melt. It has been possible to achieve these objects by a nanocomposite as defined above.

Polyamide component (A)

As polyamide component (A) in principle any of the known polyamides, copolyamides, modified polyamides such as reinforced polyamides, in particular glass-fiber reinforced polyamides, and blends of polyamides with further polymers, in particular those that are compatible with polyamide, can be employed.

Preferably, polyamide component (A) contains from 40 to 100 % by weight of at least one polyamide or copolyamide. More preferably, (A) contains from 51 to 100 % by weight of at least one polyamide or copolyamide, in particular from 60 to 100 % by weight. By way of example, use may be made of polyamides having an aliphatic, semicrystal- line or semi-aromatic, or else amorphous structure of any type and their blends, including polyetheramides, such as polyether-block-amides. Semicrystalline or amorphous resins with a molecular weight (weight-average) of at least 5000 are preferred. Examples of these are polyamides derived 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 from 6 to 12, in particular from 6 to 10, carbon atoms, and aromatic dicarboxylic acids. Acids which may be mentioned here are adipic acid, azelaic acid, sebacic acid, do- decanedioic acid (= decanedicarboxylic acid), terephthalic and/or isophthalic acid.

Particularly suitable diamines are alkanediamines having from 6 to 12, in particular from 6 to 8, carbon atoms, and also m-xylylenediamine, di(4-aminophenyl) methane, di(4-aminocyclohexyl) methane, di(4-amino-3-methylcyclohexyl) methane, iso- phoronediamine, 1 ,5-diamino-2-methylpentane, 2,2-di(4-aminophenyl) propane, and/or 2,2-di(4-aminocyclohexyl) propane.

Preferred polyamides are polyhexamethyleneadipamide (PA-66) and polyhexamethyl- enesebacamide (PA-610), polycaprolactam (PA-6), and also nylon-6/6,6 copolyamides, in particular having a proportion of from 5 to 95% by weight of caprolactam units. PA-6, PA-66, and nylon-6/6,6 copolyamides are particularly preferred; PA-6 and PA-66 are very particularly preferred.

Other suitable polyamides are obtainable from ω-aminoalkyl nitriles, e.g. aminocaproni- trile (PA-6) and adipodinitrile 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-A 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 exam- pie in EP-A 38 094, EP-A 38 582, and EP-A 39 524.

Other examples are polyamides obtainable via copolymerization of two or more of the above-mentioned monomers, and mixtures of two or more polyamides in any desired mixing ratio.

Other polyamides which have proven 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. The processes described in EP-A 129 195 and 129 196 can for instance be used to prepare the semi-aromatic copolyamides with low triamine content.

The following list, which is not comprehensive, comprises the polyamides and copolyamides mentioned above as well as other polyamides and copolyamides useful for the purposes of the invention, and the monomers present:

AB type polymers and their monomers (A reflects an amino group, B reflects a carbox- ylic group, AB also includes cyclic amides):

PA-6 ε-Caprolactam

PA-7 Ethanolactam

PA-8 Caprylolactam

PA-9 9-Aminopelargonic acid PA-11 1 1-Aminoundecanoic acid

PA-12 Laurolactam

AA/BB type 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-MXD6 m-Xylylenediamine, adipic acid PA-6I 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-6I/6T (see PA-6I and PA-6T)

PA-PACM 12 Diaminodicyclohexylmethane, laurolactam

PA-6I/6T/PACM as PA-6I/6T plus diaminodicyclohexylmethane

PA-12/MACMI Laurolactam, dimethyldiaminodicyclohexylmethane, isophthalic acid PA-12/MACMT Laurolactam, dimethyldiaminodicyclohexylmethane, terephthalic acid

PA-PDA-T Phenylenediamine, terephthalic acid

PA-DT Bis(4-aminocyclohexyl)methane, terephthalic acid. Polyamides and their preparation are known, for example from Ullmann's Enzyklopadie der Technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th edition, Vol. 19, pp. 39-54, Verlag Chemie, Weinheim 1980; Ullmann's Encyclopedia of Indus- trial Chemistry, Vol. A21 , pp. 179-206, VCH Verlag, Weinheim 1992; Stoeckhert,

Kunststofflexikon [Plastics Encyclopedia], 8th edition, pp. 425-428, Carl Hanser Verlag Munich 1992 (key word "Polyamide" [Polyamides] et seq.) and Saechtling, Kunststoff- Taschenbuch [Plastics Handbook], 27^th edition, Carl Hanser-Verlag Munich 1998, pages 465-478.

Brief details are given below of the preparation of the preferred polyamides PA-6, PA- 66, and nylon-6/6,6 copolyamide. The polymerization or polycondensation of the starting monomers to give the polyamide is preferably carried out by conventional processes. For example, caprolactam may be polymerized by the continuous processes described in DE A 14 95 198 and DE A 25 58 480. AH salt may be polymerized to prepare PA-66 by a conventional batch processes (see: Polymerization Processes pp. 424-467, in particular pp. 444-446, Interscience, New York, 1977), or by a continuous process, e.g. as in EP-A 129 196.

Concomitant use may be made of conventional chain regulators during the polymerization process. Examples of suitable chain regulators are triacetonediamine components (see WO-A 95/28443), monocarboxylic acids, such as acetic acid, propionic acid, and benzoic acid, dicarboxylic acids, such as adipic acid, sebacic acid, 1 ,4- cyclohexanedicarboxylic acid, isophthalic acid, and terephthalic acid, and also bases, such as hexamethylenediamine, benzylamine, and 1 ,4-cyclohexyldiamine.

The resultant polymer melt is discharged from the reactor, cooled, and pelletized. The resultant pellets may be subjected to a continued polymerization process, which generally takes from 2 to 24 hours. This is achieved in a manner known per se via heating of the pellets to a temperature T below the melting point T_m or crystallite melting point Tc of the polyamide. The continued polymerization process gives the polyamide its final viscosity number VN. The person skilled in the art correlates VN with the molecular weight.

The viscosity number VN of suitable polyamides (A) measured prior to extrusion is generally from 50 to 300 cm³/g, preferably from 100 to 300 cm³/g and particularly preferably from 130 to 280 cm³/g, for example from 130 to 200 cm³/g, determined pursuant to ISO 307 EN (2003) in a 0,005 g/ml solution of the polyamide in concentrated sulfuric acid (96% strength by weight) at 25°C. These viscosity numbers represent conven- tional and high molecular weights. The polyamide component (A) used in the present invention may contain fibrous reinforcing agents (such as glass fibers, carbon fibers, wollastonite, aramids) as well as further additives, for example impact modifiers, plasticizers, thermal stabilizers, oxidative stabilizers, UV light stabilizers, flame retardants, chemical stabilizers, lubricants, colorants (such as carbon black, other pigments, dyes), mold-release agents, nucleating agents, and nanoparticulate clay minerals, all additives being different from component (B).

In particular, it is possible to use the same glass fibers as reinforcing agents in the na- nocomposites of this invention that are generally suited for use in thermoplastic molding materials. Those glass fibers can be produced according to methods known to the person skilled in the art. Optionally, the glass fibers are surface modified. For instance, the glass fibers can be covered with a layer of a compatibilizing material for better compatibility with the matrix material, as for instance described in DE-10 1 17 715.

If glass fibers are used in the nanocomposites of this invention, it is preferred to use glass fibers with a mean diameter from 1 to 30 Microns, in particular from 5 to 20 Microns, for instance from 5 to 15 Microns. The glass fibers can be incorporated in the form of cut glass fibers or in the form of rovings. In the case of cut glass fibers, the length of the glass fibers is from 4 to 5 mm prior to incorporation into the matrix material. After processing, for instance by co-extrusion with the other components, the glass fibers typically have a length of 100 to 500 Microns, preferably 200 to 400 Microns.

Preferably, polyamide component (A) contains from 40 to 100 % by weight, in particular from 51 to 100 % by weight, for example 60 to 100 % by weight, of at least one polyamide or copolyamide selected from PA-6, PA-66, PA-66/6, PA-612, and PA-6/6T.

In one preferred embodiment, polyamide component (A) contains from 40 to 80 % by weight, for example from 51 to 80 % by weight, of at least one polyamide or copolyam- ide selected from PA-6, PA-66, PA-66/6, PA-612, and PA-6/6T, and from 20 to 40 % by weight of a fibrous reinforcing agent other than component (B), for instance glass fibers, and from 0 to 20 % by weight, for example from 0 to 9 % by weight, of further additives.

In another preferred embodiment, polyamide component (A) contains from 80 to 100 % by weight, for example from 90 to 100 % by weight, of at least one polyamide or copolyamide selected from PA-6, PA-66, PA-66/6, PA-612, and PA-6/6T, and from 0 to 20 % by weight, for example from 0 to 10 % by weight, of further additives.

Nanoparticulate component (B) According to the invention, the nanoparticulate component (B) is based on at least one oxide or mixed oxide/oxide hydrate of one or more metals or half metals. Suitable metals or half metals M are those capable of forming oxides or oxide hydrates during a sol- gel process starting from a precursor containing M. Examples for suitable metals and half metals M are Si, Ti, Fe, Ba, Zr, Zn, Al, Ga, In, Sb, Bi, Cu, Ge, Hf, La, Li, Nb, Na, Ta, Y, Mo, V and Sn.

The oxides or mixed oxide/ oxide hydrates can be based on a single metal or half metal M or on a combination of two or more metals or half metals M. The metal or half metal oxides and oxide hydrates used in this invention also comprise oxo-bridged polymers and networks. The metal or half metal oxides used in this invention essentially contain the metal or half metal M and oxygen bridges in a solid network as well as potentially impurities stemming from incomplete hydrolysis of the precursors, for example alkoxy groups. The mixed metal or half metal oxide/ oxide hydrates used in this invention comprise essentially M, oxygen, and hydrogen either in the form of OH-ligands or water, as well as impurities stemming from incomplete hydrolysis of the precursors, for example alkoxy groups.

In one embodiment, nanoparticulate compound (B) is based on an oxide or mixed ox- ide/ oxide hydrate comprising more than one metal or half metal M, for example BaTiCh or its corresponding oxide hydrate form. In another embodiment, nanoparticulate compound (B) is based on the oxide or mixed oxide/ oxide hydrate of a single metal or half metal M, for example Si or Ti.

In one preferred embodiment, Si is selected as metal or half metal M. Preferably, the nanoparticulate component (B) according to this embodiment is based on silica. In another preferred embodiment, Ti is selected as metal or half metal M. Preferably, the nanoparticulate component (B) according to this embodiment is based on Tiθ2. In yet another preferred embodiment, the nanoparticulate component (B) is based on BaTiCh.

Pursuant to the invention, the nanoparticulate component (B) has a mean particle diameter of up to 10 nm, preferably up to 8 nm, in particular from 1 to 6 nm, very particularly preferred from 1 to 4,5 nm, for example from 1 to 4 nm.

The particle size is advantageously chosen such that the mean particle diameter is smaller than the z-averaged radius of gyration R₉. Preferably, the nanoparticulate component (B) has a mean particle diameter of at least 1 nm and less than R₉, in particular at least 1 nm and less than R₉ minus 3 nm.

The z-averaged radius of gyration R₉ for the purpose of this invention is calculated according to the following equation:

where b is the segmental length of one monomer unit of the polyamide. The person skilled in the art calculates b as atomic distance between the two ends of one monomer unit from molecular modeling calculations. M_n refers to the number-averaged molecular weight as determined by gel permeation chromatography according to ISO 16014-4 at a temperature of 140 ⁰C using sulphuric acid as solvent.

For the determination of mean particle diameters, in principle different methods can be applied. If the mean particle diameter of the particles in a dispersion is to be deter- mined, ultracentrifuge measurements or transmission electron microscopy are suitable methods.

Mean particle diameters of nanoparticulate components in polymer matrixes can for instance be determined by electron microscopy. To that end, a microtome cut from the nanocomposite sample is prepared and analyzed by transmission electron microscopy (TEM).

Throughout the entire invention, a mean particle diameter refers to the median value (dδo value) determined via image analysis of a TEM image that has been recorded from a microtome cut slice of the nanocomposite with a thickness of 70 nm or less or a film derived from nanoparticulate component (B) (subsequently referred to as "TEM image"). The person skilled in the art chooses the position of the slice cut out of the nanocomposite such that a statistically meaningful mean value is derived. The mean particle diameter of nanoparticulate component (B) in this invention shall be the number- weighted median diameter (dso value) determined within a group of at least 100 particles in the diameter range of up to 100 nm in the TEM image.

For the determination of the mean particle diameter of nanoparticulate component (B), all individual nanoparticles visible in the "TEM image" and satisfying the criteria for component (B) are taken into account if they have an individual particle diameter of up to 100 nm. Otherwise they are not considered to be nanoparticulate and are therefore not comprised by nanoparticulate component (B).

The particle diameter of an individual particle pursuant to this invention is the smallest diameter of the particle through its geometric center in the TEM image. By way of example, if the particle is a sphere, the particle will appear as a circle in the TEM image. The shortest diameter is twice the radius of the circle. If the particle is an ellipsoid, the particle will appear as an oval slice in the image. The particle diameter is the shortest diameter through the center of the oval. In case the particle is tube-shaped, the particle will appear as a "needle" in the image. The diameter of the particle then is the thickness of the needle. If nanoparticles are clustered or partially touch each other in the image, the particle diameter shall refer to the shortest diameter of each individual particle as far as its shape can be determined by extrapolation. If a cluster does not allow the particles to be analyzed as individual particles due to strong agglomeration, then the particle diameter shall be the shortest diameter through the center of the agglomerated particle as long as it does not exceed the 100 nm limit according to the definition of nanoparticulate component (B).

For the nanoparticulate component (B) according to this invention it is advantageous if the spacial distribution of the particles in the nanocomposite is relatively homogeneous.

It is furthermore preferred if nanoparticulate component (B) has a narrow particle diameter distribution, for instance a particle diameter distribution essentially from 1 to 20 nm. Even more preferred, the particle diameter distribution of (B) is essentially from 1 to 10 nm, in particular from 2 to 8 nm, for example from 2 to 6 nm. Preferably, the particle diameter distribution is essentially monomodal. Such narrow particle diameter distributions can be obtained by producing the nanocomposite in a process comprising sol-gel synthesis.

The mean aspect ratio of nanoparticulate component (B) can vary over a broad range. The aspect ratio of an individual particle according to this invention shall be the ratio of the length and the width (l/w) through the geometric center of the particle. The mean aspect ratio is determined by transmission electron microscopy in combination with image analysis, analogously to the particle diameter and is quoted as a median value (dso).

Nanoparticulate component (B) preferably has a mean aspect ratio from 4 to 1 , in particular from 3 to 1 , for instance 2 to 1. In one particularly preferred embodiment the mean aspect ratio of (B) is essentially 1.

Preferably, the nanoparticulate component (B) according to the present invention is microporous. Generally, a porous material contains voids or tunnels of different shapes and sizes. Microporous materials are materials with micropores. Micropores pursuant to this invention are pores with diameters smaller than 2 nm in accordance to the IU- PAC classification. Such microporous materials have large specific surface areas.

The person skilled in the art knows that within the argon adsorption isotherm the area of low argon pressure is characteristic for the microporosity. A microporous component pursuant to the invention adsorbs a quantity of at least 30 cm³ argon per gram sample in a volumetric measurement of the adsorption isotherm at standard temperature and pressure (STP) at an absolute pressure of 2670 Pa. The adsorption isotherm thereby is recorded at a temperature of 87,4 K with a equilibration interval of 10 s pursuant to DIN 66135-1.

Preferably, nanoparticulate component (B) adsorbs at least 60 cm³ argon per gram sample according to the above-described method at an absolute pressure of 2670 Pa and a temperature of 87,4 K according to DIN 66135-1. The amount of argon adsorbed per gram sample under the above-defined conditions can also be slightly below 60 cm³, even though in general the value is 60 cm³ or higher. More preferably, nanoparticulate component (B) adsorbs at least 80 cm³ argon per gram sample, in particular at least 100 cm³/g, in the above-described method at an absolute pressure of 2670 Pa and a temperature of 87,4 K according to DIN 66135-1.

It is furthermore preferred if nanoparticulate component (B) adsorbs at least 50 cm³ argon per gram sample, preferably at least 70 cm³, in particular at least 90 cm³, in the above-described method at an absolute pressure of 1330 Pa and a temperature of 87,4 K according to DIN 66135-1. The amount of argon adsorbed per gram sample under the above-defined conditions can also be slightly below 50 cm³, even though in general the value is 50 cm³ or higher.

For structural reasons, suitable nanoparticulate components (B) according to this invention have an upper limit concerning the amount of argon adsorbed under to the a- bove-described conditions. Such an upper limit is for example 500 cm³ argon per gram sample according to the above described method at an absolute pressure of 2670 Pa and a temperature of 87,4 K and for example 400 cm³ argon per gram sample accord- ing to the above described method at an absolute pressure of 1330 Pa and a temperature of 87,4 K.

Different methods can be applied to calculate specific micropore surface areas and micropore volumes from the above described argon adsorption isotherm. One of those methods is the DFT (density functional theory) method according to Olivier and Conklin as outlined in Olivier, J. P., Conklin, W. B., and v. Szombathely, M. in "Characterization of Porous Solids III" (J. Rouquerol, F. Rodrigues-Reinoso, K. S. W. Sing, and K. K. Unger, Eds.), p. 81 Elsevier, Amsterdam, 1994, subsequently referred to as Olivier- Conklin-DFT method.

It is preferred if the nanoparticulate component (B) pursuant to this invention has a cumulative area of micopores (pores smaller than 2nm) of at least 40 m²/g, preferably at least 60 m²/g, in particular at least 100 m²/g, for instance at least 150 m²/g determined by the Olivier-Conklin-DFT method analyzing the argon adsorption isotherm recorded at a temperature of 87,4 K according to DIN 66135-1 when applying the following modeling parameters: slit pores, non-negative regularization, no smoothing. To be still usable as nanoparticulate component (B) in the matrix of polyamide component (A), an upper limit for the cumulative specific surface area of pores with diameters smaller than 2 nm is for instance around 600 m²/g. For instance, nanoparticulate component (B) has a cumulative specific surface area of pores with diameters smaller than 2 nm of from 40 to 500 m²/g, in particular from 100 to 400 m²/g.

For the sake of completeness, nanoparticulate component (B) can be further characterized by the method of Brunauer, Emmet and Teller (BET). The BET method pursuant to the present invention refers to the analysis of nitrogen adsorption isotherms at a temperature of 77,35 K according to DIN 66131. The BET method is known not to be selective for micropores.

Preferably, nanoparticulate component (B) has a specific surface area of at least 250 m²/g measured by the BET method. More preferably, nanoparticulate component (B) has a surface area of at least 350 m²/g measured by the BET method, even more preferred at least 450 m²/g.

The nanoparticulate component (B) according to the invention is obtainable by a process comprising sol-gel synthesis. Sol-gel synthesis for the preparation of nanoparticles is known per se. Such sol-gel processes are for instance described in Sanchez et al., Chemistry of Materials 2001 , 13, 3061-3083.

A sol-gel synthesis suitable to produce a nanoparticulate component (B) pursuant to the invention comprises the following steps:

A precursor component is mixed with a solvent and optionally further additives, optionally in the presence of a substrate or the polyamide component (A); The precursor undergoes hydrolysis and polycondensation catalyzed by an acid, thereby yielding the nanoparticulate component (B); - Optionally, nanoparticulate component (B) is dried.

The precursor component used in this invention contains at least one metal or half metal M, i. e., either one metal or half metal M or a mixture of at least two different metals and/or half metals M. In general, any metal or half metal capable of forming oxides or mixed oxide/ oxide hydrates in the presence of a protic solvent can be used. Examples for suitable metals and half metals M are Si, Ti, Fe, Ba, Zr, Zn, Al, Ga, In, Sb, Bi, Cu, Ge, Hf, La, Li, Nb, Na, Ta, Y, Mo, V and Sn. Preferably, M is selected from Si, Ti, and Ba.

Suitable precursors for instance contain at least three alkoxylate groups RO bound to M. It is preferred to use a precursor that carries no substituents other than alkoxylate groups. In one preferred embodiment, the precursor has the structure M(OR)_n where n = 2,3 or 4, in particular n = 4.

In one preferred embodiment, the alkoxylate groups bound to M are all of the same structure RO. In yet another embodiment, at least one group R¹ is different from the other groups R present in the precursor. Accordingly, the precursor of the second mentioned embodiment has the structure M(OR)_r(OR¹)t, where r = 2 or 3 and t = 1 or 2. It is preferred if r + t = 4.

In general, R and R¹ can be any linear or branched aliphatic group consisting of 1 to 12 carbon atoms. In particular, linear or branched aliphatic groups R with 2 to 8 carbon atoms can be used. Suitable groups R are linear or branched aliphatic alkyl groups, for instance methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, n-pentyl, n-hexyl, and n- octyl. Further suitable groups R are aromatic hydrocarbon groups, for instance phenyl. It is preferred if R has from 2 to 4 carbon atoms, for instance R = ethyl, n-propyl, iso- propyl, n-butyl, and iso-butyl.

In a further preferred embodiment, two different precursors with two different metals and/or half metals M are used in order to obtain the metal or half metal oxide or mixed oxide/ oxide hydrate according to the invention. According to this embodiment, both different metals and / or half metals M are preferably selected from the list described above. Preferably, at least one precursor is selected according to the alkoxylate structures described above. A second and optionally further precursors can consist of soluble metal salts, for instance metal acetates or metal hydroxides. Alternatively, two or more different precursors are selected according to the metal or half metal alkoxylate structures described above.

As precursors particularly preferred are tetraethyl orthosilicate (TEOS), titanium tetrai- sopropoxide (TPOT), and titanium tetra-n-butoxide. It is furthermore preferred to use a mixture of TPOT and barium hydroxide as a mixture of two precursors.

In general, any protic solvent can be used as solvent in the sol-gel synthesis of this invention. Suitable solvents are for instance water, alcohols and mixtures of water and alcohols.

Mixtures of water and alcohols are preferred. Preferred alcohols are aliphatic alcohols with one or two hydroxyl groups. Linear or branched aliphatic alcohols with one hy- droxyl group and from 1 to 6 carbon atoms are preferred, for instance methanol, etha- nol, n-propanol, iso-propanol, n-butanol, iso-butanol, n-hexanol or mixtures of one or more of the before-mentioned alcohols. The preferred ratio of a solvent mixture of al- cohol and water is a weight ratio of wateπalcohol from 1 :30 to 4:1 , preferably from 1 :5 to 3:1 , especially from 1 :2 to 2:1. In one preferred embodiment, a mixture of an aliphatic alcohol with one hydroxyl group and water is used as the solvent. In yet another preferred embodiment, a mixture of an aliphatic alcohol with two hydroxyl groups (glycol) and water is used as the solvent.

According to the invention, the sol-gel synthesis yielding the nanoparticulate component is carried out in the presence of an acid in order to catalyze and control the hydrolysis and the polycondensation reaction. It is preferred to carry out the sol-gel synthesis in the presence of a strong acid. It is particularly preferred to carry out the sol-gel synthesis in the presence of a strong inorganic acid, in particular hydrochloric acid.

The sol-gel synthesis according to the invention is conducted under acidic conditions. It is preferred to conduct the sol-gel synthesis at pH values below 5, for instance from 1 to 4, preferably from 2 to 4.

It is possible to carry out the sol-gel synthesis in one step or in more than one step. In one preferred embodiment, the sol-gel synthesis is carried out in at least two subsequent steps. According to this embodiment, in a first step (the mixing step), the precursor is mixed with the solvent or parts of a solvent or solvent mixture, for instance a solvent mixture containing an alcohol and water. The temperature during the first step can vary over a moderately wide range. Suitable temperatures are below 80⁰C, especially below 70⁰C. Suitable temperatures on the other hand are above 0°C, for instance between 15°C and 70⁰C.

The period of time in which the mixing step is carried out can vary over a broad range. It is possible to conduct the mixing step in a period of time from a few minutes to a few hours. Preferably, the mixing step is carried out within a period of time lasting from 5 to 60 minutes, more preferably from 10 to 45 minutes.

In an optional intermediate step of this preferred embodiment, the pH of the solvent is adjusted by adding an acid to the mixture. Preferably, a mixture of water with an acid, preferably hydrochloric acid, is added such that a pH value within the above described preferred pH range is achieved. Alternatively, the intermediate step of this embodiment is combined with the mixing step such that the optional pH adjustment is carried out together with the mixing step.

In a second step (the reaction step) according to this preferred embodiment, the reaction including hydrolysis and polycondensation of the precursor of nanoparticulate component (B) is carried out at a temperature within the range described above (in the section describing the mixing step). The reaction step can vary over a broad range. In ge- neral, the reaction step lasts for at least 1 hour, preferably between 1 and 8 hours, more preferably between 2 and 6 hours. In an optional third step (the reaction step at increased temperature) according to this preferred embodiment, the temperature is increased compared to the second step, for instance by at least 10 ⁰C, preferably by at least 15°C, for example by 15 to 30⁰C. The optional third step can last for several hours, for instance from 1 to 5 hours, preferably from 2 to 4 hours.

Further additional reaction steps can follow, preferably at an increased temperature compared to the first step. Each additional step can last from a few minutes to several hours, for instance within the range already described above. Alternatively, instead of adjusting the temperature step-wise, the temperature may be modified continuously within the range described above.

The nanoparticulate component (B) can optionally be surface modified. Pursuant to one preferred embodiment, nanoparticulate component (B) is not surface modified. In another preferred embodiment, nanoparticulate component (B) has a modified surface to improve its dispersibility in the polymer matrix. Surface modification in the context of the present invention corresponds to the incorporation of organic groups or molecules bound to the surface of the nanoparticles in order to modify its surface properties.

Preferably, a surface modified nanoparticulate component (B) carries terminal groups R² preferably bound to the metal or half metal M on its surface, where R² is a saturated or unsaturated hydrocarbon group having from 1 to 150 carbon atoms, preferably from 1 to 50 carbon atoms, and M has the meaning as described above.

In one preferred embodiment R² is a linear or branched aliphatic alkyl group of from 1 to 12 carbon atoms. In particular, linear or branched aliphatic groups R² with 2 to 8 carbon atoms can be used. Suitable groups R² are for instance ethyl, n-propyl, iso- propyl, n-butyl, iso-butyl, n-pentyl, n-hexyl, heptyl and octyl. It is preferred if R² has from 3 to 4 carbon atoms, for instance R³ = n-propyl, iso-propyl, n-butyl, or iso-butyl.

In another preferred embodiment, R² is bearing at least one epoxy, hydroxy, amino, carboxy, (meth)acrylate, isocyanate, thiol, glycidyl, or aromatic group and has from 5 to 20 carbon atoms, preferably from 6 to 10 carbon atoms.

A surface-modified nanoparticulate component (B) according to this invention is obtainable by a process comprising sol-gel synthesis. Advantageously, the surface modification is carried out as an additional step in the above-described sol-gel process.

If a surface modified nanoparticulate component (B) is to be obtained by a process comprising sol-gel synthesis, the surface modification is advantageously carried out subsequently to the last step of the process described above, i.e., when the particle has essentially its final size and shape. Surface modification can be advantageously carried out by adding components suitable for surface modification to the dispersion obtained in the last step of the above described sol-gel synthesis.

The surface-modification preferably takes place via treatment with a siloxane, chlorosi- lane, silazane, titanate, or zirconate, or a mixture of these. These preferably have the general formulae M(OR¹)_n(R²)₄-n, SiCI_n(R²Kn, or ((R²)_m(OR¹)₃-mSi)₂NH, where R¹, R², and M have the meaning as described above, m = 1 or 2 and n = 1 or 2 or 3. Preferably, M is selected from Si. Ti, and Zr, even more preferably M = Si.

The groups R¹ bonded via the oxygen atom are eliminated in the form of the alcohol during hydrolysis. In the case of modification with the silazane, ammonia is eliminated, and in the case of the chlorosilanes hydrochloric acid is eliminated. The alcohol formed, or the hydrochloric acid, or the ammonia is essentially no longer present in the nanocomposite prepared in the subsequent steps.

Further preferred components for surface modification are aminopropyltrimethoxysi- lane, aminobutyltrimethoxysilane, aminopropyltriethoxysilane, aminobutyltriethoxysi- lane, and also the corresponding silanes which contain a glycidyl group, and also phenyltriethoxysilane, and phenyltrimethoxysilane, as well as silane-functionalized polymers (e.g. silane-terminated polystyrene or PMMA).

An alkyl trimethoxysilane (R²)Si(OMe)3 is particularly preferred as component for surface modification, for example isobutyl trimethoxy silane.

While the main parameters that influence particle size and morphology in the sol-gel process, pH, solvent, and precursors as well as reaction times and temperatures of the different reaction steps are outlined above, the person skilled in the art of sol-gel processes chooses further additives as well as suitable concentrations according to routine experiments.

The nanoparticulate component (B) obtainable by a process comprising sol-gel synthesis can be added to the polyamide component (A) as a dispersion or in dried form as powder. In one embodiment, nanoparticulate component (B) is dried before combining it with the polyamide component (A). The dried form can for instance conveniently be mixed with the polyamide component (A) in an extruder.

In principle any known drying method can be applied. In one preferred embodiment, drying is accomplished in a spray-drying unit in timeframes typical for spray-drying processes, which is often in the minute range or less. In a second preferred embodiment, drying can be carried out in other drying means such as drying chambers or vessels at increased temperature or under reduced pressure or under both, increased temperature and reduced pressure. A suitable temperature for drying component (B) according to the second embodiment is typically from 50 to 90⁰C and a suitable pressure is typically below 100 mbar. The time until the nanoparticulate component (B) is sufficiently dry to be further used in powder form depends on the drying conditions and can vary over a wide range. In the case of the second embodiment, the drying step typically lasts for at least 1 hour, for instance for at least 3 hours, in particular for at least 5 hours. Optionally, the powder obtained can be further dried in a second drying step. Preferably, the powder is further dried in a second step at a temperature of at least 80⁰C at reduced pressure, for instance below 100 mbar, for at least one hour, for instance 5 to 15 hours. For drying a heatable vacuum unit such as a vacuum oven can be used according to this second embodiment. A combination of different drying methods is also suitable.

Nanocomposite

To obtain its final structure, composition and properties, the nanocomposite of this invention is preferably extruded prior to use. Typical conditions for extrusion of polyam- ides can be applied and are well known to the person skilled in the art.

The nanocomposite can be present as final mixture or as masterbatch. A masterbatch is an intermediate product and carries an enriched amount of nanocomposite mixed with the matrix material of the composite or with material compatible to the matrix material. If the nanocomposite according to this invention is present as a masterbatch, it is eventually co-extruded with further polyamide component (A) to yield the final mixture with its final properties.

It is preferred if the nanoparticles present in the nanocomposite do not agglomerate in the melt under shear.

The nanocomposite of this invention comprises from 50 to 99,9 % by weight of polyam- ide component (A) and from 0,1 to 50 % by weight of nanoparticulate component (B).

In one embodiment, the nanocomposite of this invention comprises from 50 to 95 % by weight of polyamide component (A) and from 5 to 50 % by weight of nanoparticulate component (B) for use as masterbatch. The nanocomposite of this embodiment exhib- its an improved melt flow after having been mixed with further polyamide component (A) such that eventually a nanocomposite according to a second embodiment is obtained.

According to a second preferred embodiment, the nanocomposite comprises from 95 to 99,9 % by weight of polyamide component (A) and from 0,1 to 5 % by weight of nanoparticulate component (B). Preferably, the nanocomposite according to this preferred embodiment comprises from 96 to 99,8 % by weight, in particular from 97 to 0,3 % by weight, of a polyamide component (A) and from 0,2 to 4 % by weight of a nanoparticulate component (B), in particular from 0,3 to 3 % by weight. The % numbers of (A) and (B) always add up to 100 % by weight.

The nanocomposite according to this second embodiment is particularly useful for use as molding material. The nanocomposite of this second embodiment exhibits improved processing characteristics, in particular improved melt flow characteristics such as a reduced dynamic melt viscosity and an increased melt volume-flow rate (MVR), both occurring already at low contents of nanoparticular component (B). The nanocomposite at the same time has favorable mechanical properties substantially unchanged compared to the polyamide component (A) without nanoparticulate component (B).

In general, the nanocomposite of the present invention does not contain more than 1 % by weight of water to prevent unwanted degradation in particular during processing. Preferably, the nanocomposite according to the invention contains 0,6 % by weight of water or less, in particular 0,4 % by weight or less.

In the melted state, the nanocomposite according to the invention shows essentially no degradation of polymer chains under extrusion conditions and no slip of polymer chains at walls or at nanoparticles causing unwanted defects.

The nanocomposite of the present invention can be manufactured by different means.

In one embodiment, the preparation of the nanocomposite is performed according to a process comprising the following steps:

Preparing (B) by a process comprising sol-gel synthesis, for instance according to one of the embodiments described above; Mixing (B) with a precursor of (A); - Polymerizing of the precursor of (A) in the presence of (B).

The precursor of polyamide component (A) can be a reactive mixture of monomers of (A) or prepolymers of (A) or both, monomers and prepolymers of (A).

The process of preparing polyamide component (A) by polymerization is well known to the person skilled in the art and was already outlined above.

According to a second embodiment, the preparation of the nanocomposite is performed according to a process comprising the following steps:

Preparing (B) by a process comprising sol-gel synthesis for instance according to one of the embodiments described above; Preparing (A); Mixing (A) and (B), for example in an extruder.

In a third embodiment, the preparation of the nanocomposite is performed according to a process comprising the following steps:

Preparing (A);

Mixing (A) with a precursor of (B);

Synthesize (B) by a process comprising sol-gel synthesis in the presence of (A), for instance in the presence of (A) in powder form.

Pursuant to the invention, the melt flow characteristics of a polyamide component (A) can be improved by a method which comprises combining a polyamide containing component (A) with a nanoparticulate component (B) thereby obtaining a nanocompo- site in accordance to the invention.

The nanoparticulate component (B) described above can be advantageously used to improve the flow characteristics of polyamide containing melts, for example to increase the melt volume flow rate MVR of polyamide component (A).

Use of the nanocomposite

The nanocomposite of the invention can be molded to yield a molded part. The methods to mold a nanocomposite are known to the person skilled in the art. For instance, the nanocomposites can be injection molded.

The nanocomposite according to the invention is particularly useful for the preparation of molded parts comprising walls thinner than 1 mm, for example walls with thickness of 0,6 mm or less.

The nanocomposite pursuant to the invention can be used to produce molded parts for various applications. These applications include automotive engineering, where the nanocomposite can for instance be used to produce housings and functional parts in electrical and electronic components as well as components for many other automotive parts such as air intake manifolds, windscreen wiper arms, door handles, headlamp structures, mirror systems, connectors, sun-roof components, and housings for locking systems.

The nanocomposites pursuant to the invention can also be used to produce parts for electrical engineering, parts for electronics and telecommunication equipment, parts for electrical appliances, and parts for household applications including food-contact parts. Applications also include the construction industry and the food industry. Household applications include for instance exterior parts for deep fryers, waffle irons, toasters, bread baking machines, coffee machines, steam irons, cooker knobs and handles. In the personal care sector, potential applications include for instance toothbrush bristles, toothpaste tub lid.

Based on their demanding requirements concerning processing characteristics, the nanocomposites according to the invention are particularly advantageous for producing parts for electrical engineering technology and parts for electronics and telecommunication equipment, for example in automotive applications.

Examples

1.) Characterization of the nanocomposite

Mean particle diameter

The mean particle diameter of nanoparticulate component (B) was determined by TEM image analysis of a film of nanoparticulate component (B) as described above. TEM measurements were performed using a field emission gun (FEG) transmission electron microscope with a resolution of 1 nm (corresponding to an electron beam energy of 20 keV) with an energy dispersive x-ray spectrometer attached as auxiliary unit for elemental detection.

Dynamic viscosity

The dynamic viscosity was measured according to ISO 6721-10 (1999) using a paral- lel-plate oscillatory rheometer, diameter 25mm, distance between plates h=1 mm at a deformation of 10% in frequency-sweep modus in a temperature range from 240⁰C to 280⁰C. The measurement time was 20 min.

Melt volume-flow rate (MVR) The melt volume-flow rate (MVR) was measured with a load of 2,16 kg at 190 ⁰C according to ISO 1 133.

Viscosity number (VN)

The viscosity number (VN) was determined pursuant to ISO 307 (2003) in a dilute solu- tion of the nanocomposite with a concentration of 0,005 g/ml in sulphuric acid (cone. 96%) with a Ubbelohde capillary viscometer (capillary constant of 0,104; measurements were performed at 25⁰C for 100s).

Tensile modulus Tensile testing was performed according to ISO 527-2 (1993) using injection molded specimens as described in EN ISO 1873-2 (dog bone shape, 3 mm thickness). The tensile modulus (E-modulus) was determined according to ISO 527-2 (1993) and calculated from the linear part of the tensile test results.

Specific surface area according to BET The specific surface area according to BET was determined by measurement of nitrogen adsorption isotherms at 77,35 K and analyzing them according to the BET method. As described above, the BET method refers to the method of Brunauer, Emmet and Teller pursuant to DIN 66131. Dried nanoparticulate component (B) in powder form was used for the determination of the specific surface area according to BET.

Particle porosity measurements

Particle porosity measurements were performed by volumetric measurement of the adsorption isotherm at standard temperature and pressure (STP). For the determination of the micropore content, the volume of adsorbed Argon in cm³/g was determined in the linear absolute plot (quantity adsorbed argon vs. absolute pressure) of the adsorption isotherm at an absolute pressure of 2670 Pa and 1330 Pa. The argon adsorption isotherm was recorded at a temperature of 87,4 K according to DIN 66135-1. Dried nanoparticulate component (B) in powder form was used for the determination of the particle porosity.

2.) Composition of the polyamide component (A)

Table 1 - Polyamide component (A)

¹ Ultrabatch is a heat stabilizer conta n ng u an

² Black color batch based on polyethylene containing carbon black

³ Flexamine® is a mixture of condensation products of secondary aromatic amines and aldehydes and/or ketones

⁴ Glass fibers with a mean diameter of 10 to 20 microns and a mean length of 200 to 250 microns, for example Ownes Corning Fiberglass OFC 1110 3.) a) Composition of nanoparticulate component (B)

Nanoparticulate component (B) was prepared according to procedures B-1 to B-6V:

B-1

100 g TEOS was mixed with 500 g Ethanol at 6O⁰C for 30 min. Subsequently, 352 g water was added under continuous stirring after HCI (concentration 2 mol/l in water) was added to it drop-wise until pH = 3 was achieved. After completion of the addition, the reaction was carried out at 6O⁰C for 3 hours. Subsequently, the temperature was raised to 8O⁰C for another 3 hours. The dispersion of silica particles obtained was clear with 3,5 % by weight solid content. From this solution, silica in powder form was obtained by drying. The drying was carried out at 8O⁰C and 50 mbar for 8 hrs. In a second step, the powder was dried in a vacuum oven at 100⁰C for 12 hours.

B-2

100 g TEOS was mixed with 500 g Ethanol at 6O⁰C for 30 min. Subsequently, 352 g water was added under continuous stirring after HCI (concentration 2 mol/l in water) was added to it drop-wise until a pH of 3 was achieved. After completion of the addition, the reaction was carried out at 6O⁰C for 3 hours. Subsequently, the temperature was raised to 8O⁰C for another 3 hours. The dispersion of silica particles obtained was clear with 3,5 % by weight solid content. For surface modification, isobutyl trimethoxy silane was added and the reaction was carried out for additional 3 hours. From this solution, silica in powder form was obtained by drying. The drying was carried out at 8O⁰C and 50 mbar for 8 hrs. In a second step, the powder was dried in a vacuum oven at 100⁰C for 12 hours.

B-3

237.4 g Ba(OH)₂ was mixed with 1336 g butyl glycol at 150 ⁰C using a stirrer at 10.000 rev/min for 45 min and then 407,0 g of 21 % titanium tetra-n-butoxide was pumped in the reactor and stirred for another 30 min. The pH value was approximately 3. The reaction was carried out at 14O⁰C for 24 hrs. A dispersion of particles with 15% by weight solid content was obtained. From this solution, BaTiθ3 in powder form was obtained by spray drying. Further drying was carried out at 8O⁰C and 50 mbar for 8 hrs to achieve a moisture content below 0,6 % by weight. In a second step, the powder was dried in a vacuum oven at 100⁰C for 12 hours. % by weight.

B-4c

100 g TEOS was mixed with 500 g Ethanol at 6O⁰C for 30 min. Subsequently, a mixture of water and NH₄OH (concentration 29% by weight) with pH of 9 was added drop-wise under continuous stirring. After completion of the addition, the reaction was carried out at 6O⁰C for 3 hours. Subsequently, the temperature was raised to 8O⁰C for another 3 hours. The dispersion of silica particles obtained was clear with 3,5 % by weight solid content. From this solution, silica in powder form was obtained by drying. The drying was carried out at 8O⁰C and 50 mbar for 8 hours. In a second step, the powder was dried in vacuum oven at 100°C for 12 hours.

B-5c

ZnO nanoparticles were prepared by co-precipitation of 100 ml of a 0,2 M solution of ZnCb in water and 100 ml of a 0,4 M solution of NaOH in water in the presence of 0,4 g sodium polyaspartate. Subsequently, the resulting Zn(OH)2 containing precipitate was heated at 90 ⁰C for 20 min in order to form ZnO. The ZnO-in-water dispersion was washed, centrifuged and dried at 80 ⁰C for 8 hours in a vacuum oven.

3.) b) Properties of nanoparticulate compound (B)

Table 2 - properties of nanoparticulate compound (B)

n.d. = not determined

¹ Argon adsorbed at given pressure at T = 87,4 K according to adsorption isotherm measurement pursuant to DIN 66135-1

² According to TEM image analysis of a film derived from a dispersion of nanoparticulate component (B)

3.) c) Procedure for preparing comparison example 14c

3,5 g of sol-gel silica (12g TEOS/ 45g Water/ammonium hydroxide mixed and sol is prepared) was mixed with 400 g ε-caprolactam and 4Og water in a reactor. Then the pressure was increased to 20 bar and the temperature to 28O⁰C. The reaction was carried out for 1 hour. Subsequently the pressure was released to remove water over a period of 1 hour. During this time the temperature dropped to 25O⁰C. After that the reactor was sealed again at a pressure of 18-22 bar and a temperature of 28O⁰C for post- condensation reaction for two hours. 4.) Preparation of specimen for the determination of VN, tensile modulus, dynamic viscosity, and MVR.

The nanoparticulate component (B) obtained in powder form was mixed with the poly- amide component (A) in a twin-screw extruder at varying conditions (for 2 to 5 minutes at 260 to 28O⁰C) at a throughput of 5 kg/h and strands were obtained. These strands were dried at 8O⁰C for 5 days and injection molded into discs for measurement of the VN, the tensile modulus, dynamic viscosity, and MVR. The results concerning VN, tensile modulus, dynamic viscosity, and MVR of examples 1 to 12 and comparison exam- pies 13c to 15c are summarized in Table 3 (see Annex).

The examples according to Table 3 demonstrate that the nanocomposites according to the present invention exhibit an improved melt volume-flow rate and a decreased dynamic viscosity at low contents of nanoparticulate component (B), while their mechani- cal data is substantially unchanged. Nanocomposites that do not satisfy the features of the present invention do not show a corresponding improvement concerning the processing characteristics.

M

^J

OO n.d. = not determined a) extruded for 2 minutes at 280⁰C b) extruded for 5 minutes at 280⁰C c) increase of VN due to traces of water

Claims

1. A nanocomposite comprising a polyamide component (A) and a nanoparticulate component (B), wherein nanoparticulate component (B)

(a) is based on at least one oxide or mixed oxide/ oxide hydrate of one or more metals or half metals M,

(b) has a mean particle diameter of up to 10 nm, and

2. The nanocomposite according to claim 1 , wherein nanoparticulate component (B) is microporous.

3. The nanocomposite according to claim 1 or 2, wherein nanoparticulate component (B) adsorbs at least 60 cm³/g argon at 2670 Pa absolute pressure according to an adsorption isotherm recorded at a temperature of 87,4 K.

4. The nanocomposite according to any of claims 1 to 3, wherein the surface of nanoparticulate component (B) is modified by reaction with an alkyl alkoxy silane.

5. The nanocomposite according to any of claims 1 to 4, wherein nanoparticulate component (B) has a mean particle diameter from 1 to 4 nm.

6. The nanocomposite according to any of claims 1 to 5, wherein said nanoparticulate component (B) is based on at least one oxide selected from SiC"2, TiC"2, or BaTiC"3 or a mixture thereof.

7. The nanocomposite according to any of claims 1 to 6, wherein nanoparticulate component (B) is obtainable by a process further comprising

(c1 ) using at least one precursor according to the structure M(OR)_n where n = 2, 3 or 4 and R is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, Cs-alkyl, Cβ-alkyl, and phenoxide.

8. The nanocomposite according to any of claims 1 to 7, comprising from 51 to

99,9 % by weight of polyamide component (A) and from 0,1 to 49 % by weight of nanoparticulate component (B) and in which the sum of (A) and (B) is 100 % by weight.

9. A method of making a nanocomposite according to any of claims 1 to 8 comprising the following steps: (α) Preparing nanoparticulate component (B) by a process comprising sol-gel synthesis that is carried out in the presence of an acid; (β) Preparing polyamide component (A); (γ) Combining (A) and (B) by mixing.

10. A method for producing a nanocomposite according to any of claims 1 to 8 comprising the following steps:

(α) Preparing nanoparticulate component (B) by a process comprising sol-gel synthesis that is carried out in the presence of an acid;

(β) Combining (B) with a precursor or precursors of (A);

(γ) Polymerizing said precursor or precursors in the presence of (B).

1 1. Use of a nanoparticulate component (B) according to any of claims 1 to 8 for increasing the flow of polyamide containing melts.

12. Molded part comprising a nanocomposite according to any of claims 1 to 8.

13. Use of a nanocomposite according to any of claims 1 to 8 for the manufacturing of molded parts containing walls thinner than 1 mm.