WO2011117344A1

WO2011117344A1 - Post-crosslinked polyamides and method for producing same

Info

Publication number: WO2011117344A1
Application number: PCT/EP2011/054532
Authority: WO
Inventors: Julien Courtois; Alexander Traut; Vijay Immanuel Raman; Rabie Al-Hellani; Philipp Zacharias; Christian Schmidt
Original assignee: Basf Se
Priority date: 2010-03-24
Filing date: 2011-03-24
Publication date: 2011-09-29

Abstract

The invention relates to a method for producing post-crosslinked polyamide, comprising the steps of (a) providing a mixture having 80 to 90 wt % of polyamide (A), 0.1 to 20 wt % of component (B), carrying at least three functional groups that can react with the functional groups present in the polyamide (A), and 0 to 25 wt % of additive (C), each based on the total weight of (A), (B), and (C), (b) shaping the mixture obtained from step (a), and (c) heat treating the formed body obtained from step (b) for post-cross linking the polyamide.

Description

Postcrosslinked polyamides and process for their preparation

description

The present invention relates to a process for the preparation of postcrosslinked polyamide, the moldings, films and fibers which can be produced by this process, and components for mechanical engineering, precision engineering, vehicle construction, electrical engineering, the construction industry and the furniture industry comprising the postcrosslinked shaped bodies, fibers which can be prepared by the novel process and slides.

In addition to textile fiber production, polyamides are used because of their high impact resistance and wear resistance for the production of mechanical components such as gears and other items such as housings, cable sheathing, dowels and protective helmets. They are also used as aroma-tight packaging films. The polyamides are usually processed with the known molding processes for thermoplastics such as injection molding, extrusion and film blowing. The polyamides are essentially uncrosslinked. An improvement of the already very good mechanical properties of the polyamides can be achieved by crosslinking of the polyamides. However, crosslinked polymers are generally no longer thermoplastically deformable, therefore, uncrosslinked polyamides are prepared with additives which are inactive during the molding process, but allow crosslinking of the polyamides in a post-treatment of the resulting molded article for the preparation of crosslinked moldings and films of polyamides.

For example, EP 0 345 649 A1 describes a process for preparing crosslinked polyamide molded articles in which polyamides containing at least 30% by weight of branched polymer chains are mixed and reacted in the melt with silanes. The silanes contain at least one hydrolyzable upon entry of moisture radical and a functional group which reacts with the amino groups, carboxyl groups or amide groups of the polyamides in the melt to form a chemical bond. There is still no networking. The resulting reaction products are subjected to a shaping process, and the resulting shaped articles are subsequently brought into contact with water or moisture. Under the action of water or moisture, the crosslinked structure of the polyamide molecules is formed by intermolecular formation of Si-O-Si bridges from the hydrolyzable Si-OR groups. This method is not applicable to the standard commercially available polyamides, since the polyamides to be used as starting compounds must contain at least 30 wt .-% branching. In addition, the silane components are relatively expensive to produce.

Another method in the production of moldings from thermoplastic polymers which are crosslinked after shaping is the addition of crosslinking agents which are reacted by radiation after the shaping process. Thus, JP 1 1315156 describes the preparation of crosslinked, non-crystalline polyamide moldings by irradiation of the shaped bodies, wherein the polyamide contains a crosslinker.

The uniform irradiation of larger moldings is on the one hand technically complex and limited on the other hand by the penetration depth of the radiation in the moldings, so that a uniform cross-linking is difficult to achieve with larger objects.

There was therefore a need for a further process for producing postcrosslinked shaped polyamide, in which customary commercially available polyamides can be processed into postcrosslinked moldings, fibers and films. The method should enable the production of larger items without expensive and expensive devices. In addition, moldings should be obtained with a uniform crosslinking density. This object is achieved by the following process for producing postcrosslinked polyamide comprising the steps

(a) providing a mixture containing

80 to 99.9% by weight of polyamide (A),

0.1 to 20 wt .-% of a component (B) carrying at least three functional groups which can react with the functional groups contained in the polyamide (A), and

0 to 25% by weight of one or more additives (C),

in each case based on the total weight of (A), (B) and (C),

(b) shaping the mixture obtained from step (a), and

(c) dissolving heat treatment of the molded body obtained from step (b) to post-crosslink the polyamide. For the inventive method no special polyamides, for example, have a certain amount of branches or of functional monomer required, but industrially produced, commercially available polyamides such as polyamide-6 (for example Ultramid ^® B BASF SE), and polyamide 6/66 / 136 (for example Ultramid ^® 1C by BASF SE) can be processed with the inventive method to post-crosslinked moldings, fibers and films. Existing plants for thermoplastic molding can continue to be used for the process according to the invention without modifications. The post-crosslinking of the polyamide chains in the moldings is carried out by annealing the moldings, films and fibers at elevated temperatures. This can be achieved with simpler compared to the irradiation or the controlled exposure to a humid environment devices such as conventional heating cabinets.

In the following, the present invention will be described in detail.

The polyamides (PA) to be used according to the invention as polyamide (A) are preferably composed of bifunctional monomer units selected from lactams, aminocarboxylic acids, diamines in combination with dicarboxylic acids or mixtures thereof. Thus, PA 6 is usually produced from caprolactam, PA 66 from hexamethylenediamine in combination with adipic acid. PA 6/66/136 contains a mixture of the monomer units caprolactam, hexamethylenediamine in combination with adipic acid and a cycloaliphatic diamine with 13 C atoms, also in combination with adipic acid. The amino carboxylic acid, diamine and dicarboxylic acid monomer units contained in the polyamides (A) are independently selected from aliphatic and aromatic compounds, with polyamides containing only aliphatic monomer units being referred to as aliphatic polyamides, polyamides containing only aromatic monomer units, aromatic Polyamides are called and polyamides, which consist partly of aromatic building blocks, are called partially aromatic polyamides.

As the aliphatic Aminocarbonsäuremonomereinheiten linear, branched and / or cycloaliphatic dicarboxylic acids having 6 to 14 carbon atoms are preferred. These include, for example, adipic acid, azelaic acid, sebacic acid, 1, 10-dodecane dicarboxylic acid and 1, 1 1 -Tridecandicarbonsäure.

As the aliphatic diamine monomer units, preferred are linear, branched and / or cycloaliphatic diamines having 4 to 14 carbon atoms. These include compounds such as 1, 4-butylenediamine, 1, 6-hexylenediamine, 1, 10-decylenediamine, 1, 12-dodecylenediamine, bis (p-aminocyclohexylmethane), 1, 4-cyclohexylenediamine, 2,4,4- Trimethyl-1,6-hexamethylenediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (isophoronediamine), 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

The aliphatic aminocarboxylic acid monomer units are preferably linear, branched and / or cycloaliphatic aminocarboxylic acids, for example 10-aminoundecanoic acid. The aminocarboxylic acids are usually used in the form of their lactams in the production of polyamides, for example the 5-aminocaproic acid as ε-caprolactam. The aromatic monomer units are selected from aromatic diamines, aromatic dicarboxylic acids and aromatic aminocarboxylic acids, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acids or p- and m-phenylenediamine can be used. An overview of polyamides which can be used according to the invention can be found, for example, in H.-G. Elias "Macromolecules", Vol. 2, 2007, Whiley-VCH, pp. 456-482.

Linear polyamides are preferably used according to the invention, the polyamide chains in the main chain preferably having from 4 to 10 methylene groups. Polyamide 6, polyamide 66, polyamide 6T / 6 and polyamide 6/66/136 are particularly preferably used as polyamides (A).

For the purposes of the present invention, postcrosslinked polyamide means that a polyamide is first subjected to a shaping step, during which essentially no crosslinking takes place during the shaping step, and the shaped articles obtained during the shaping step are subjected to a further, subsequent crosslinking step in which the molded particles are formed Objects contained polyamide molecules are crosslinked with each other. The crosslinking of the polyamide takes place after shaping.

According to the invention, the polyamide (A) is uncrosslinked and thermoplastically processable, this means that the polyamides are plastically deformable or molten by sufficient heat input and after cooling to normal temperature again solid and resilient.

In step (a) of the process according to the invention, a mixture is provided which comprises 80 to 99.9% by weight of polyamide (A), preferably 85 to 99% by weight and particularly preferably 87.5 to 97% by weight of polyamide ( A), based on the total weight of polyamide (A), at least one component (B) and additive (C). As polyamide (A) it is possible to use a polyamide or mixtures of several polyamides having, for example, different molecular weights. According to the invention, the polyamide (A) preferably has a number-average molecular weight of 5,000 to 200,000 g / mol, preferably 10,000 to 30,000 g / mol, and more preferably 12,000 to 25,000 g / mol, determined by the amino and carboxyl groups. The molecular weight of polyamide can also be determined by the viscosity number in sulfuric acid. The polyamides used according to the invention preferably have a viscosity number of from 70 to 300 ml / g, particularly preferably from 90 to 250 ml / g and in particular from 100 to 200 ml, measured in accordance with ISO 307 in sulfuric acid.

The mixture provided in step (a) contains a component (B) containing at least three functional, i. having reactive groups in the polyamide (A) functional groups. The functional groups contained in the at least one component (B), which can react with the functional groups contained in the polyamide, are also referred to below as reactive groups.

The concentration of component (B) in the mixture is from 0.1 to 20% by weight, preferably from 1 to 15% by weight and more preferably from 3 to 12.5% by weight, based on the total weight of polyamide (A) , Component (B) and additive (C).

The functional groups contained in the polyamide (A) are usually amide groups, carboxyl groups and / or amino groups.

Depending on the molecular structure and possibly further groups contained in the molecule of the compound (s) used as component (B), the functional groups of a compound have different degrees of reactivity. According to the invention, compounds which only react above 70 ° C. with the functional groups contained in the polyamide are used as component (B). Preferably, the at least three reactive groups present in component (B) are independently selected from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic acid ester, carboxylic acid halide, isocyanate, primary amine and secondary amine, more preferably the at least three reactive groups described in US Pat Component (B) are selected from the group consisting of carboxylic acid, carboxylic acid anhydride, carboxylic acid ester and carboxylic acid halide, most preferably the at least three reactive groups of component (B) are selected from carboxylic acid, carboxylic anhydride and carboxylic acid halide. According to the invention, component (B) contains at least three reactive groups, preferably at least five and particularly preferably at least ten reactive groups. In this case, component (B) is particularly preferably selected from homopolymers and copolymers which contain monomer units bearing reactive groups. According to the invention, copolymer is understood to mean a polymer which is made up of at least two different monomer units, block copolymers, random copolymers, alternating copolymers and graft copolymers, in particular having a core-shell structure being included. Polymers formed from a monomer type are called homopolymers in the context of the present invention. According to the invention, the homopolymers and copolymers used as component (B) preferably contain a multiplicity of reactive groups which can react with the functional groups contained in polyamide (A), in particular at least 5% by weight, preferably at least 10% by weight and more preferably At least 15 wt .-% reactive groups carrying monomer units, based on the total weight of the copolymer.

Very particular preference is given to using as component (B) homopolymers and copolymers present as nanoparticles. According to the invention, nanoparticles are particles having an average diameter of the primary particles of from 3 to 500 nm, preferably from 5 to 250 nm and particularly preferably from 10 to 50 nm. The particle size is determined by means of dynamic light scattering and / or TEM. Such nanoparticles can be prepared, for example, by dispersion polymerization; the corresponding processes are known to the person skilled in the art. Very particularly preferred graft copolymers are used according to the invention as nanoparticles. The preparation of such graft copolymers can be carried out analogously to the process described in WO 2008/101888 A1. The nanoparticles can also be present in agglomerated form.

Homopolymers and copolymers are particularly preferred according to the invention set mono-, from monomers selected from the group (meth) acrylic acid, dC ₈ - alkyl (meth) acrylate, maleic acid, semi- and fully with -C ₈ alkyl esterifiable te maleic acid and maleic anhydride, in particular selected from the group of (meth) acrylic acid, (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate , Maleic acid, fumaric acid, maleic anhydride and 2-ethylhexyl acrylate. Particularly preferably, these homopolymers and copolymers are present as nanoparticles.

Very particular preference is given to using, as component (B), homopolymers and copolymers containing acrylic acid according to the invention. Component (B) may comprise one, two or more compounds, for example a mixture of a graft copolymer and a homopolymer.

The homopolymers and copolymers used as component (B) usually have a weight-average molecular weight of from 1,000 to 1,000,000, preferably from 5,000 to 500,000 and more preferably from 10,000 to 100,000 g / mol, determined by means of GPC.

Furthermore, the mixture provided in step (a) may contain 0 to 25% by weight, preferably 0.2 to 20% by weight, particularly preferably 1 to 10% by weight, of one or more further additives (additive (C)) , based on the total weight of (A), (B) and (C). Other additives include, for example, processing aids, stabilizers and antioxidants, agents against heat decomposition and decomposition by ultraviolet light, lubricants and mold release agents, flame retardants, dyes and pigments and plasticizers.

Particulate and fibrous fillers, such as mineral fillers or glass fibers, can also be used as additive (C). When selecting the additive (C), it must be ensured that these additives do not undergo any undesirable secondary reactions or that they do not significantly impair the crosslinking reaction of the polyamide molecules by reaction with the compound or additives (C).

To provide the mixture comprising polyamide (A), component (B) and optionally additive (C), it may be advantageous to premix individual components of the mixture, for example by mixing the dry components, by mixing dispersions of the components or by mixing partially as Dispersion and partially dry components, wherein the dispersion medium is preferably removed before step (b). The dry mixtures may be blended by coextruding, kneading or rolling the components, optionally with the components previously isolated from the solution obtained in the polymerization or from the aqueous dispersion. Mixing devices such as screw extruders, for example twin-screw extruders, masterbatch mixers, Banbury mixers and kneaders, are suitable for the melt mixture.

The mixture can also be prepared in solution, this means that the polyamide (A) is dissolved in a solvent 1 and component (B) is added to this solution or a solution of component (B) is prepared in the same solvent 1 and both solutions are put together. The optionally present additive (C) is added to one of the solutions as appropriate, or a separate solution or dispersion of (C) is prepared, which is then added. The polyamide (A), component (B) and a common solvent and optionally additive (C) containing solution can then be further processed directly in a molding process, the solvent can also be removed by drying (for example freeze-drying) or the polyamide (A ) and the component (B) can be precipitated by adding a common precipitating agent, for example, to prepare a dry mixture suitable for extrusion and similar processes. The optionally present additive (C) can also be added only after the mixture of (A) and (B) has been prepared. Solvents for polyamides are known to those skilled in the art and described in corresponding tabular works. According to the invention, mixed solvents are also referred to as solvents. For amorphous polyamide, for example, a mixture of 80% by weight of ethanol and 20% by weight of water is suitable as the solvent, for semicrystalline polyamide, for example, hexafluoroisopropanol can be used as the solvent.

According to a particular embodiment of the present invention, the mixture provided in step (a) contains at least one common solvent for the polyamide (A) and the component (B).

If the mixture provided in step (a) contains at least one common solvent for (A) and (B), then the total concentration of (A) and (B) and optionally (C), based on the total weight of solvent, (A), (B) and optionally (C) usually 1 to 50 wt .-%.

In step (b) of the process according to the invention, the mixture provided in step (a) is subjected to a shaping step. In this case, the shaping step depends on the mixture obtained from (a). Processes for shaping thermoplastically processable mixtures are known to the person skilled in the art, as is the processing of polymer solutions into moldings, films and fibers.

According to one embodiment of the present invention, the mixture prepared in step (a) is molded into shaped articles, films or fibers by injection molding, extrusion, calendering, extrusion blow molding and / or film blowing in step (b). This can be excellently applied, for example, to mixtures which do not contain a common solvent for polyamide (A) and at least one component (B), in particular if component (B) is selected from homopolymers and / or copolymers. According to a further embodiment of the present invention, the mixture containing at least one common solvent for (A) and (B) provided in step (a) is molded into shaped parts in step (b), spun into fibers or by casting, dipping, brushing, Squeegeeing, rolling and / or spraying introduced into a mold and then carried out a drying step.

The spinning of polymer solutions into fibers is known to the person skilled in the art and can be carried out, for example, by spinning the fibers into a precipitating agent bath.

In the context of the present invention, the term "mold" encompasses three-dimensionally formed molds for the production of moldings as well as only two-dimensionally configured molds for producing films and plates. In step (c) of the process according to the invention, a heat treatment of the shaped body obtained from step (b) takes place. In this heat treatment, a crosslinking reaction takes place between the functional groups contained in the polyamide (A) and the reactive groups of the component (B). Depending on the reactivity of the polyamide and of component (B), shorter or longer time periods and / or higher or lower temperatures are necessary for the crosslinking reaction. Usually, the heat treatment in step (c) is carried out at 70 to 250 ° C for 1 minute to 7 days. Preferably, the heat treatment is carried out for 2 minutes to 6 days, and more preferably for 3 minutes to 5 days. The preferred temperature range for the heat treatment is 80 to 240 ° C, more preferably 90 to 220 ° C. The heat treatment at relatively high temperatures is comparatively short, at low temperatures, the heat treatment is carried out correspondingly longer. For example, by a heat treatment of 10 minutes at 200 'Ό, a similar result can be obtained as with a heat treatment of 3 days at 120' Ό.

The heat treatment is preferably, but not necessarily, carried out in an inert gas atmosphere, for example under nitrogen or argon.

The mixture provided in step (a) comprising polyamide (A), component (B) having at least two reactive groups, optionally additive (C) and at least one common solvent for (A) and (B) is prepared in step (b) according to this preferred embodiment in step (b) spun into fibers or introduced by casting, knife coating, rolling, dipping and / or spraying in a mold, and then a drying step is carried out. The drying step may be carried out under conditions in which the crosslinking of the polyamide molecules by the at least one component (B) does not yet take place, but it is also possible to use the Select temperature conditions such that at the same time the solvent is removed and the crosslinking reaction takes place, in which case the drying step and step (c) coincide. Another object of the present invention are postcrosslinked moldings, films and fibers produced by the inventive method described above. The postcrosslinked moldings, films and fibers according to the invention may already be finished components and articles of daily use for the various fields such as mechanical engineering, precision engineering, vehicle construction, electrical engineering, the construction industry, the furniture industry and the packaging industry. However, the postcrosslinked moldings, films and fibers according to the invention may also be precursors, which are then further processed into components and articles of daily use in the areas mentioned. The present invention therefore also relates to components and articles of daily use for mechanical engineering, precision engineering, vehicle construction, electrical engineering, the construction industry, the furniture industry and the packaging industry comprising the postcrosslinked shaped bodies, films and fibers according to the invention.

These components and commodities include, for example, gears, pinions, rollers, bearings, bolts and nuts, general housings for headlamps, cameras, flash units, pumps, etc. Also, there may be pump parts, slideways, fuel lines, fenders and tanks for motorcycles , wear-resistant cable and wire sheathing, parts for refrigerators and other household appliances, dowels, fuel oil tanks, door fittings and latches, furniture hinges, combs, buttons, buckles, protective helmets, packaging tapes and films (aroma-tight) and the like.

The postcrosslinked moldings, films and fibers according to the invention have improved heat resistance, improved Young's modulus, improved creep resistance and increased counter-abrasion and show increased resistance to chemicals and media, for example to ethylene glycol, ethylene glycol-water mixtures, aqueous urea solutions, acids and alkalis, diesel and other fuels. The invention will be explained in more detail below with reference to examples.

Example 1 (comparison)

By dissolving polyamide (Ultramid ^® 1C, PA 6/66/613, M _n 40000 g / mol GPC in granular form in a mixture of 80 wt .-% ethanol and 20 wt .-% water at 70 ° C was added a 20 % by weight polyamide solution transparent. Using an Erichsen doctor blade, films of the polymer solution having a gap thickness of 800 μm were drawn on a polyester film. These were pre-dried overnight in the air, the remaining solvent residues were removed under vacuum at 50 'Ό. The dried films had a layer thickness of about 100 μηι. The dried films are soluble in the solvent mixture of 80 wt .-% ethanol and 20 wt .-% water without residue.

Example 2 (according to the invention): Preparation of postcrosslinked polyamide with

polyacrylic acid

As described in Example 1, first a 20 wt .-% solution of polyamide (Ultramid ^® 1 C) in a mixture of 80 wt .-% ethanol and 20 wt .-% water was prepared. To this was added 3 to 14% by weight of a 35% aqueous solution of polyacrylic acid (molecular weight about 100,000 g / mol). Based on the total weight of polyamide and polyacrylic acid, this corresponded to a polyacrylic acid concentration of 1 to 5 wt .-%. Films were prepared and dried according to the procedure in Example 1. The dried films from Example 2 and reference-dried films from Comparative Example 1 were annealed for 3 days at 120 ° C. (Example 2a) or 10 minutes at 200 ° C. (Example 2b) under an inert gas atmosphere.

To demonstrate the crosslinking reaction, the solubility of the polymer films was tested. For this purpose, the films were each stored in a solvent mixture of 80 wt .-% ethanol and 20 wt .-% water for 1 day at 50 'Ό with stirring. The polymer concentration was 5 wt .-% based on solvent mixture and polymer. The extracted films were removed from the solution and dried. In Examples 2a and 2b, the extractable content of the crosslinked polymer film was about 40% by weight. The comparison films tested in parallel without polyacrylic acid additives which were subjected to the same temperature treatment were soluble without residue.

Example 3 (according to the invention): Preparation of postcrosslinked polyamide with

Graft copolymers based on polystyrene and polyacrylic acid

According to Example 1, a 20 wt .-% polyamide (Ultramid ^® 1 C) solution was prepared in a mixture of 80 wt .-% ethanol and 20 wt .-% water. From 5 to 25% by weight of a 20% strength by weight aqueous nanoparticle dispersion was added to this solution. The nanoparticles were based on a core / shell graft copolymer with the core made of polystyrene and the shell made of polyacrylic acid. The weight ratio of polystyrene to polyacrylic acid was 1: 1. The size of the particles was on average at 30 to 40 nm. The synthesis was carried out analogously to the method described in WO 2008/101888 A1. This corresponds to a nanoparticle concentration, based on the total Weight of polyamide and nanoparticles from 1 to 5 wt .-%. The resulting polymer solution was transparent. Films were prepared and dried analogously to the process described in Comparative Example 1. The dried films had a layer thickness of about 100 μηι and were soluble in the solvent mixture of 80 wt .-% ethanol and 20 wt .-% water without residue.

The dried films were annealed at temperatures of 120 'Ό for 3 days (Example 3a) or 200 ° C for 10 minutes (Example 3b) under an inert gas atmosphere. The same treatment was subjected as reference films of Comparative Example 1. According to the method described in Example 2, the solubility of the annealed films was determined. The extractable fraction of the crosslinked polymer films was about 55 to 65 wt .-%. The reference samples tested in parallel without nanoparticle addition were residue-free soluble. Example 4 (according to the invention): Preparation of postcrosslinked polyamide with

Nanoparticles based on polyacrylic acid and polybutyl acrylate

Analogously to Example 1, a 20 wt .-% polyamide solution (Ultramid ^® 1 C) was prepared. 3 to 17% by weight of a 30% nanoparticle dispersion in butyl acetate were added thereto. The nanoparticles were based on a core-shell graft copolymer, the core consisting of polyacrylic acid and the shell of polybutyl acrylate. The weight ratio of polyacrylic acid to polybutyl acrylate was 1: 1. The size of the particles was on average 20 to 30 nm. The synthesis was carried out analogously to the process described in WO 2008/101888 A1. The nanoparticle concentration corresponded to 1 to 5% by weight, based on the total amount of polyamide and nanoparticles. The resulting polymer solution was transparent. Films were prepared analogously to Example 1. The dried films had a layer thickness of about 100 μηι and were soluble in the solvent mixture of 80 wt .-% ethanol and 20 wt .-% water without residue.

The dried films and reference samples according to Example 1 were annealed for 3 days at 120 ° C. (Example 4a) or 10 minutes at 200 ° C. (Example 4b) under an inert gas atmosphere. The solubility of the polymer films was detected analogously to Example 2. The extractable content of the crosslinked polymer films was about 45 to 60 wt .-%. The reference samples tested in parallel without nanoparticle addition were residue-free soluble. Example 5 (Comparison): Polyamide Granules Based on PA 6 (PA-E)

Polyamide powder (PA 6, Ultramid ^® B27E (PA-e), viscosity number according to ISO 307: 150 mlJg BASF SE) was dried (<0.1% H ₂ 0), and in a laboratory extruder with melting recirculation at 260 '(mini-extruder from the company DSM). Homogen Homogenized for 3 minutes, extruded as a 2 mm thick strand and granulated.

Example 6 (Inventive): Polyamide (PA 6, PA-E) with nanoparticles

Polyacrylic acid and polybutyl acrylate

A powder based on PA 6 (Ultramid ^® B27E, BASF SE) are mixed for 3 to 17 wt .-% of a 30% nanoparticle dispersion in butyl acetate, the mixture was homogenized and dried at 70 ° C under vacuum. The nanoparticles consisted of a graft copolymer having a core of polyacrylic acid and a shell of polybutyl acrylate. The weight ratio of polyacrylic acid to polybutyl acrylate was 1: 1. The size of the particles was on average 20 to 30 nm. The synthesis was carried out analogously to the method described in WO 2008/101888 A1. The nanoparticle concentration was 1 to 5 wt .-%, based on the total weight of polyamide and nanoparticles. The dried powder mixture was homogenized in a laboratory extruder with melt recycling (mini extruder from. DSM) at 260 'Ό 3 minutes, extruded as a 2 mm thick strand and granulated. A portion of the dried granules is annealed for 3 days at 120 ° C (Example 6a) or 10 minutes at 200 'Ό (Example 6b) under an inert gas atmosphere. The crosslinking of the polyamide molecules was demonstrated by the solubility of the granules. For this purpose, the two tempered granules (according to the invention, Examples 6a and 6b) and for comparison, the non-tempered granules (not according to the invention, Example 6c) were stored in hexafluoroisopropanol for 1 day at 50 ° C with stirring. The concentration of polymer granules in the solvent was 5% by weight, based on the total sample. The tempered granules swelled up, but did not give a homogeneous solution, the unannealed granules were soluble without residue. The polyamide granules from Example 5, which had likewise been tempered for comparison, without addition of nanoparticles, was likewise soluble without leaving any residue. Example 7 (Comparison): Polyamide (PA 6, PA-E)

The polyamide of Example 5 (Ultramid ^® 27E) was dried at 280 ° C with a twin-screw extruder ZSK 25 from the company. Werner & Pfleiderer mixed and specimens for train-strain measurements in accordance with ISO 527-2 extruded (Example 7a). A portion of the samples was annealed for 3 days at 140 'Ό under inert gas atmosphere (Example 7b). Example 8 (Inventive): Polyamide (PA 6, PA-E) with polyacrylic acid

The polyamide from Examples 5 to 7 (Ultramid ^® 27E) was dried in vacuum (35-% ig, molecular weight about 100,000 g / mol) were mixed with aqueous polyacrylic acid, and homogenized at 70 'Ό. The mixture contained after drying 1 wt .-% polyacrylic acid, based on the total weight of the mixture. The mixture was extruded in analogy to Example 7 to test specimens (Example 8a, comparison) and a portion of the resulting measuring body under inert gas atmosphere for 3 days at 140 ° C annealed (Example 8 b, according to the invention).

Example 9 (Comparative) Polyamide (PA 6, PA-ND)

Polyamide powder (Ultramid ^® 27ND15, BASF SE (PA-ND), PA 6 with a viscosity number according to ISO was 307 145-151 ml / g dried according to Example 7 to measuring bodies for train-strain measurements in accordance with ISO 527-2 and bending measurements according to ISO 178 extruded (Example 9a) A portion of the measuring bodies was annealed at 140 ° C. for 3 days under an inert gas atmosphere (Example 9b) Example 10 (Inventive) Polyamide (PA 6, PA-ND) with nanoparticles of polyacrylic acid and polybutyl acrylate

PA-ND was mixed in analogy to Example 6 with the nanoparticle dispersion described there, homogenized and dried. The concentration of the nanoparticles was 1 wt .-%, based on the dried mixture. Subsequently, the mixture according to Example 7 was extruded into measuring bodies (Example 10a, comparison). A portion of the resulting moldings was annealed at 140 'Ό for 3 days under an inert gas atmosphere (Example 10b, according to the invention). Example 11: Solubility

The measuring bodies from Examples 7 to 10 were stored for 1 day at 50 ° C in hexafluoroisopropanol with stirring. The concentration of the solvent was 95 wt .-% to 5 wt .-% measuring body.

The results of the solution experiments are shown in Table 1: Table 1

Example 12: Maximum tensile stress

The measuring bodies from Examples 7 to 10 were examined according to ISO 527-2 with regard to their elongation at break. The results are shown in Table 2.

Table 2

Example 13: Chemical resistance

The chemical resistance of the samples of Examples 9 and 10 with respect to cooling liquids was tested using Glysantin ^® (BASF SE). Glysantin contains essentially monoethylene glycol. The samples were stored for 50 hours at 130 ° C (2 bar) in Glysantin. Samples 9a, 9b and 10a (comparison) showed clear Damage, the sample 10b (according to the invention) has survived the test without externally visible damage, as shown in Figure 1.

Example 14 Polyamide (PA 6, PA-ND) with 5% by Weight Nanoparticles (Inventive)

Ultramid ^® B27-ND15 and the nanoparticles dispersion described in Example 6 were mixed, homogenized and dried in vacuo at 70 ° C. From this mixture according to Example 7 measuring body for measuring the bending properties according to ISO 178 were prepared. The mixture contained 5% by weight of nanoparticles.

Example 15: Bending stress / bending strain under chemical stress

Several measuring bodies from Examples 9a and 14 were stored as in Example 13 at 130 'Ό (2 bar) in a 1: 1 mixture of glysantin and water. At the beginning, after 500 h and after 1000 h, in each case the maximum bending stress and bending strain according to ISO 178 were determined on the basis of wet samples. The tested measuring bodies were discarded. The results are shown in Table 3. The unannealed samples were used, respectively, since the temperature prevailing in the glysantin treatment and the duration of the glysantin treatment were sufficient to produce a crosslinking reaction.

Table 3

Duration PA-ND (Example PA-ND + 5% by weight

Glysantin treatment 9a, comparison) Nanoparticles (Bei¬

[h] game 14)

Maximum bending stress 286 281 tension 500 72 74

[MPa] 1000 23 27

Bending strain 0 4.48 4.69 at the maximum 500 2.57 3.17

[%] 1000 0.89 1, 31

Claims

claims

Process for the preparation of postcrosslinked polyamide comprising the steps

(a) providing a mixture containing

80 to 99.9% by weight of polyamide (A),

0.1 to 20 wt .-% of component (B), which carries at least three functional groups which can react with the functional groups contained in the polyamide (A), and

0 to 25% by weight of additive (C),

in each case based on the total weight of (A), (B) and (C),

(b) shaping the mixture obtained from step (a), and

(c) heat-treating the molded body obtained from step (b) to post-crosslink the polyamide.

A method according to claim 1, characterized in that the polyamide (A) has a number average molecular weight of 5,000 to 200,000 g / mol.

A method according to claim 1 or 2, characterized in that in the component (B) at least contained three functional groups which can react with the functional groups contained in the polyamide (A) are independently selected from the group consisting of carboxylic acid, carboxylic anhydride Carboxylic acid ester, carboxylic acid halide, isocyanate, primary amine and secondary amine.

Method according to one of claims 1 to 3, characterized in that the component (B) is selected from homopolymers and copolymers containing functional group-carrying monomer units which can react with the functional groups contained in the polyamide (A).

A method according to claim 4, characterized in that the homopolymers and copolymers are used as nanoparticles.

A method according to claim 4 or 5, characterized in that the homopolymers and copolymers of monomers selected from the group consisting of (meth) acrylic acid, C 1 to C ₈ alkyl (meth) acrylic acid ester, maleic acid, half and completely with C to C ₈ alkyl esterified maleic acid and maleic anhydride are prepared.

7. The method according to any one of claims 1 to 6, characterized in that the additive (C) is selected from the group processing aids, stabilizers, oxidation inhibitors, agents against heat decomposition and decomposition by ultraviolet light, lubricants and mold release agents, flameproofing agents, dyes, pigments, particulate and fibrous fillers and / or plasticizers.

8. The method according to any one of claims 1 to 7, characterized in that the heat treatment in step (c) for 1 minute to 7 days at 70 to 250 ^ is performed.

9. The method according to any one of claims 1 to 8, characterized in that in step (b) the mixture provided in step (a) is formed by injection molding, extrusion, calendering, extrusion blow molding and / or film blowing into moldings, films or fibers.

10. The method according to any one of claims 1 to 9, characterized in that the mixture provided in step (a) contains at least one common solvent for (A) and (B).

1 1. A method according to claim 10, characterized in that the mixture provided in step (a) is injection molded into moldings, spun into fibers or introduced into a mold by casting, dipping, brushing, knife coating, rolling and / or spraying in step (b), and then a drying step is carried out.

12. Post-crosslinked shaped bodies, films and fibers producible according to one of claims 1 to 11.

13. Components and articles of daily use for mechanical engineering, precision engineering, vehicle construction, electron engineering, construction industry and furniture industry containing post-crosslinked shaped bodies, films and fibers according to claim 12.