Methods and containers for the storage and transport of polyamide granules and correspondingly stored or transported polyamide granules, as well as molded articles produced therefrom

Description

[0001] The invention relates to a method for storing and transporting polyamide granules containing at least one amorphous or microcrystalline polyamide. This novel method can prevent or at least reduce yellowing during further processing into molded articles. The invention also relates to a corresponding container in which the polyamide granules are stored. The invention also relates to correspondingly stored or transported polyamide granules and molded articles produced therefrom.

[0002] The storage and transport of polyamide granulate prior to further processing usually takes place in various types of containers, such as sacks, pouches, big bags, boxes, octabins, barrels, buckets, canisters or cans.

[0003] It is well known that yellowing is often observed during further processing of polyamide granules, even though the granules themselves do not exhibit yellowing after storage, when stored. While a large number of heat stabilizers are available for use in polyamides, these are ineffective during storage or transport of polyamide granules.

[0004] The state of the art currently includes solutions based on preventing or at least minimizing contact between sensitive products and the ambient air.

[0005] In the food industry, it is known to use oxygen absorbers to prevent food spoilage. Such an approach is known, for example, from EP 0864 630 A1, which describes packaging containing small sachets of oxygen-absorbing compounds for food preservation.

[0006] EP 1 347 007 A1 relates to a process for solid phase drying or solid phase polymerization, wherein a polyamide which is stored for 20 days or longer after its production serves as starting material for the solid phase drying or solid phase polymerization.

[0007] EP 1 186 552 A1 describes a packaging container comprising an article packaging bag made of a packaging material having high moisture permeability and high air permeability for packaging a solid or powder, an inner packaging bag made of a packaging material having at least low moisture permeability and low air permeability for containing the article packaging bag, a desiccant or an oxygen absorber arranged between the article packaging bag and the inner packaging bag, and an outer packaging container for containing the inner packaging bag.

[0008] US Pat. No. 5,977,212 A relates to an oxygen-scavenging composition consisting of a carrier and an ascorbate-based agent. The agent is impregnated into a porous, particulate material distributed throughout the carrier. The composition is contained in the inner cavity of a container to capture oxygen therein. Based on this, the object of the present invention was to enable improved storage and transport conditions for polyamides, so that further processing with as little yellowing as possible can be achieved without the addition of additives to the polyamide.

[0009] This object is achieved by the method having the features of claim 1. The further dependent claims show advantageous developments.

[0010] According to the invention, a method is provided for storing and transporting polyamide granules containing at least one amorphous or microcrystalline polyamide while avoiding or reducing the yellowing of molded articles produced from the granules. The method comprises storing the polyamide granules in a container with a barrier effect against oxygen and moisture, which contains at least one oxygen absorber that creates a substantially oxygen-free atmosphere in the container, substantially preventing contact of the granules with oxygen from the ambient air. The barrier effect of the container substantially prevents the penetration of additional oxygen and moisture from the ambient air into the container. This means that the container is gas-tight and moisture-tight.

[0011] Surprisingly, it was found that the addition of an oxygen absorber and the resulting essentially oxygen-free atmosphere enables storage and transport of polyamide granules without leading to any significant yellowing during further processing of the granules.

[0012] According to the invention, all compounds that enable the absorption of oxygen from the ambient air can be considered as oxygen absorbers.

[0013] In a preferred embodiment, the oxygen absorber is at least one oxidizable metal compound from the group of metal powders, metal oxides, metal salts or mixtures thereof.

[0014] Particularly preferred oxidizable metal powders are powders of iron, tin, copper, cobalt, chromium, manganese, vanadium, titanium, or mixtures thereof. Particularly preferred oxidizable metal oxides or metal salts are oxides or salts of iron, copper, cobalt, chromium, or mixtures thereof.

[0015] It is preferred that the amount of oxidizable metal compounds in the container is preferably in the range of 20 to 400 mmol, preferably 30 to 300 mmol, particularly preferably 40 to 200 mmol per liter of residual volume. Residual volume here refers to the volume of the container not occupied by the polyamide granules.

[0016] To enhance their effectiveness as oxygen absorbers, the oxidizable metal powders, oxidizable metal oxides, or oxidizable metal salts can preferably be combined with oxidation catalysts. The oxidation catalysts for oxidizable metal powders, oxidizable metal oxides, or oxidizable metal salts are halides of alkali metals, alkaline earth metals, or mixtures thereof. The halides are preferably selected from the group consisting of chlorine, bromine, and iodine. The halides are particularly preferably selected from the group consisting of chlorine and iodine. The alkali or alkaline earth metals are preferably selected from the group consisting of sodium, potassium, calcium, magnesium, and barium. The alkali or alkaline earth metals are particularly preferably selected from the group consisting of sodium, potassium, and calcium.

[0017] The oxidation catalysts for oxidizable metal powders, oxidizable metal oxides or oxidizable metal salts are preferably added in amounts of 0.05 to 35 wt.%, preferably 0.1 to 17 wt.%, particularly preferably 0.5 to 10 wt.%, based on the oxidizable metal powder, the oxidizable metal oxide or the oxidizable metal salt.

[0018] A humectant can optionally be added to systems containing oxidizable metal powders and oxidation catalysts, oxidizable metal oxides and oxidation catalysts, or oxidizable metal salts and oxidation catalysts. The humectant is selected from the group consisting of activated carbon, silicates, zeolites, molecular sieves, hydrogels, perlites, and diatomaceous earth.

[0019] A further preferred embodiment provides that the oxygen absorber is an oxidizable organic or inorganic compound or an enzyme. Preferred oxidizable organic compounds are ascorbic acid, isoascorbic acid, pyrocatechol, hydroquinone, unsaturated carboxylic acids, derivatives of unsaturated carboxylic acids (e.g., esters), or mixtures thereof. Preferred oxidizable inorganic compounds are sulfites (e.g., CaSO 3 ), dithionites (e.g., sodium dithionite, zinc dithionite), or mixtures thereof.

[0020] The oxidizable metal compounds, oxidizable organic or inorganic compounds used as oxygen absorbers are preferably filled into sachets, wherein the sachets preferably consist of oxygen-permeable materials, in particular paper, polyolefins, fabric, filter paper, textile membranes, materials provided with holes or micropores or combinations thereof.

[0021] A further preferred embodiment provides that the oxygen absorber is an oxidizable polymer.

[0022] The oxidizable polymer is preferably selected from the group consisting of olefinic polymers with aliphatic carbon-carbon double bonds in the main chain or the side chain, containing linear or cyclic polyenes with conjugated or unconjugated double bonds, olefinic polymers with tertiary carbon atoms in the main chain, polymers containing activated methylene groups in the main chain and polymers containing aldehyde groups.

[0023] Preferred olefinic polymers having aliphatic carbon-carbon double bonds in the main chain or the side chain, containing linear or cyclic polyenes having conjugated or unconjugated double bonds are polybutadiene, polyisoprene, ethylene-propylene-diene copolymers, polyterpenes, dicyclopentadiene-containing polymers or polymers containing polyunsaturated norbornene derivatives, such as: vinylnorbornene, ethylidenenorbornene, isopropylidenenorbornene or diisopropylidenenorbornene.

[0024] Preferred olefinic polymers with tertiary carbon atoms in the main chain are polymers formed from α-olefins having 3 to 20, preferably 3 to 10, carbon atoms, or polymers or copolymers with benzene rings in the side chains. Particularly preferred olefinic polymers or copolymers with tertiary carbon atoms in the main chain are polypropylene, poly-1-butene, poly-1-hexene, poly-1-octene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-propylene-butene-1 copolymer, polystyrene, styrene-butadiene copolymer, or styrene-isoprene copolymer.

[0025] Preferred polymers containing activated methylene groups in the main chain are polyamides or olefin-carbon monoxide copolymers. Among the polyamides, polyamides containing m-xylylenediamine, p-xylylenediamine, or mixtures thereof are preferred. Particularly preferred polyamides are PA MXD6, PA MXD10, PA MXD9, PA MXD7, PA MXD6 / MXDI, or mixtures or copolymers thereof, where the MXD can be completely or partially replaced by PXD and where lactams or ω-amino acids having 4 to 12 carbon atoms can also be present as comonomers. The maximum possible proportion of lactams or ω-amino acids is 30 mol%, based on 100 mol% of the total polyamide. The polyamides are most preferably free of lactams or ω-amino acids. The proportion of isophthalic acid in the polyamide PA MXD6 / MXDI is preferably 2 to 15 mol%, particularly preferably 2 to 12 mol%, very particularly preferably 2 to 8 mol%, the sum of the two dicarboxylic acids being 100 mol%.

[0026] Preferred polymers containing aldehyde groups are polymers containing acrolein, methacrolein or mixtures thereof as monomer or are copolymers of these monomers or monomer mixtures with styrene.

[0027] To achieve their effect as oxygen absorbers, the oxidizable polymers must be combined with oxidation catalysts. The oxidation catalysts for oxidizable polymers are added in amounts of 0.001 to 3 wt.%, preferably 0.005 to 1 wt.%, particularly preferably 0.01 to 0.5 wt.%, and most preferably 0.03 to 0.15 wt.%, based on the oxidizable polymer.

[0028] The oxidation catalysts for oxidizable polymers are transition metal compounds. The transition metal compounds are preferably selected from the group consisting of halides, sulfates, nitrates, phosphates, silicates, complex salts, sulfonic acid salts, phosphonic acid salts, and carboxylic acid salts. The carboxylic acids used for the carboxylic acid salts are linear or branched. The carboxylic acids preferably have 2 to 22 carbon atoms. Particularly preferred carboxylic acids are neodecanoic acid or stearic acid.

[0029] The transition metals are selected from the group consisting of iron, cobalt, nickel, copper, silver, zinc, tin, titanium, zirconium, vanadium, chromium, and manganese. The transition metals are preferably selected from the group consisting of iron, cobalt, nickel, copper, zinc, chromium, and manganese. The transition metals are particularly preferably selected from the group consisting of cobalt, copper, zinc, and manganese. The transition metal is most preferably cobalt.

[0030] Particularly preferred oxidation catalysts for oxidizable polymers are the carboxylic acid salts of transition metals. Particularly preferred oxidation catalysts for oxidizable polymers are the carboxylic acid salts of cobalt.

[0031] A particularly preferred embodiment provides that the oxygen absorber is selected from the group consisting of oxidizable metal powders and oxidizable polymers.

[0032] According to the invention, a container with a barrier effect against oxygen and moisture is used, whereby the penetration of additional oxygen and moisture from the ambient air into the container is substantially prevented. The container can contain at least one barrier layer, which is in particular selected from the group consisting of metal, aluminum, ethylene-vinyl alcohol copolymers (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), polyolefins, polyethylene, and combinations thereof.

[0033] The polyamides to be stored or transported are specified in more detail below.

[0034] The notation and abbreviations for polyamides and their monomers are defined in the ISO standard 16396-1:2015. Among others, the following abbreviations are used for aromatic or non-linear aliphatic monomers: For diamines, MXD stands for m-xylylenediamine, PXD for p-xylylenediamine, MACM for 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, PACM for bis(p-aminocyclohexyl)methane, TMDC for 3,5,3',5'-tetramethyl-4,4'-diaminodicyclohexylmethane, ND for 1,6-diamino-2,2,4-trimethylhexane, and IND for 1,6-diamino-2,4,4-trimethylhexane.

[0035] For dicarboxylic acids, T stands for terephthalic acid, I for isophthalic acid and N for naphthalenedicarboxylic acid.

[0036] If the polyamides contain only dicarboxylic acids and diamines, their molar amounts add up to 50 mol% for the sum of all diamines and 50 mol% for the sum of all dicarboxylic acids, and the sum of the diamine and dicarboxylic acid amounts results in 100 mol% for the polyamide.

[0037] If the polyamides contain lactams or ω-amino acids in addition to dicarboxylic acids and diamines at X mol%, the sum of all diamines is only (50 - 0.5 X) mol% and the sum of all dicarboxylic acids is (50 - 0.5 X) mol%, based on 100 mol% of polyamide.

[0038] The quantities given with regard to the monomers are to be understood in such a way that a corresponding molar ratio of these monomers used in the polycondensation is also found in the polyamides produced by polycondensation in this way.

[0039] When specifying the quantities of dicarboxylic acids and diamines in the polyamides, the sum of the molar amounts of all diamines is essentially equal to the sum of the molar amounts of all dicarboxylic acids. "Essentially equal" means a maximum excess of dicarboxylic acids or diamines of 5%, i.e., the molar ratio of dicarboxylic acids to diamines is 1.05:1 to 1:1.05. A maximum excess of dicarboxylic acids or diamines of 2% is preferred, i.e., the molar ratio of dicarboxylic acids to diamines is 1.02:1 to 1:1.02.

[0040] The polyamide granulate is produced with at least one amorphous or microcrystalline polyamide or mixtures of at least one amorphous or microcrystalline polyamide with at least one semi-crystalline polyamide and / or with at least one impact modifier.

[0041] The mixtures can be in the form of physical mixtures or extruded or compounded mixtures.

[0042] The amorphous or microcrystalline polyamides preferably exhibit a heat of fusion of a maximum of 30 J / g, preferably a maximum of 25 J / g, particularly preferably 0 to 22 J / g, in differential scanning calorimetry (DSC) according to ISO 11357 at a heating rate of 20 K / min.

[0043] Compared to microcrystalline polyamides, amorphous polyamides exhibit an even lower heat of fusion. In differential scanning calorimetry (DSC) according to ISO 11357 at a heating rate of 20 K / min, amorphous polyamides preferably exhibit a heat of fusion of a maximum of 5 J / g, preferably a maximum of 3 J / g, and particularly preferably between 0 and 1 J / g.

[0044] Amorphous polyamides have no melting point due to their amorphicity.

[0045] Microcrystalline polyamides are semi-crystalline polyamides and therefore have a melting point. Their melting point is preferably a maximum of 260 °C, measured according to ISO 11537. They have a morphology in which the crystallites are so small that a sheet made from them with a thickness of 2 mm is still transparent, meaning its light transmission is at least 75%, measured according to ASTM D 1003.

[0046] There are no restrictions with regard to the at least one amorphous or microcrystalline polyamide. The amorphous or microcrystalline polyamide is preferably selected from the group consisting of amorphous or microcrystalline polyamides with a glass transition temperature (measured according to ISO 11357) of 40 to 225 °C, preferably of 60 to 215 °C, particularly preferably of 105 to 210 °C, and most preferably of 130 to 205 °C.

[0047] The amorphous or microcrystalline polyamide is preferably formed from at least one diamine and at least one dicarboxylic acid and optionally from at least one lactam and / or at least one ω-amino acid.

[0048] Preferably, the at least one diamine is selected from a group consisting of ethylenediamine, butanediamine, pentanediamine, methylpentanediamine, hexamethylenediamine, octanediamine, methyloctanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, diaminotrimethylhexane, bis(aminocyclohexyl)methane and its alkyl derivatives, bis(aminocyclohexyl)propane and its alkyl derivatives, isophoronediamine, norbornanediamine, bis(aminomethyl)norbornane, xylylenediamine, cyclohexanediamine and bis(aminomethyl)cyclohexane and its alkyl derivatives.

[0049] Preferably, the at least one dicarboxylic acid is selected from a group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, japannic acid, cyclohexanedicarboxylic acid, phenylindanedicarboxylic acid, phenylenedioxydiacetic acid, dimer fatty acid having 36 or 44 C atoms, isophthalic acid, terephthalic acid and naphthalenedicarboxylic acid.

[0050] Preferably, the at least one lactam or the at least one ω-amino acid is selected from the group consisting of the lactams having 4 to 15 C atoms and the ω-amino acids having 4 to 15 C atoms.

[0051] Particularly preferably, the at least one diamine is selected from the group consisting of hexamethylenediamine, 1,6-diamino-2,2,4-trimethylhexane, 1,6-diamino-2,4,4-trimethylhexane, 2-methyl-1,5-pentanediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, bis(p-aminocyclohexyl)methane, 3,3'-diethyl-4,4'-diaminodicyclohexylmethane, 3,5,3',5'-tetramethyl-4,4'-diaminodicyclohexylmethane, 2,2-bis(p-aminodicyclohexyl)propane, isophoronediamine, norbornanediamine, m-xylylenediamine, p-xylylenediamine and 1,3-bis(aminomethyl)cyclohexane.

[0052] Particularly preferably, the at least one dicarboxylic acid is selected from the group consisting of 1,6-hexanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,12-dodecanedioic acid, 1,13-tridecanedioic acid, 1,14-tetradecanedioic acid, 1,15-pentadecanoic acid, 1,16-hexadecanedioic acid, 1,18-octadecanedioic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phenylindanedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, dimer fatty acid having 36 or 44 C atoms, isophthalic acid, terephthalic acid and 2,6-naphthalenedicarboxylic acid.

[0053] Particularly preferred lactams are lactams or ω-amino acids with 4, 6, 7, 8, 11, or 12 carbon atoms. These are selected from the group consisting of pyrrolidin-2-one (4 carbon atoms), ε-caprolactam (6 carbon atoms), enanthlactam (7 carbon atoms), capryllactam (8 carbon atoms), laurolactam (12 carbon atoms), 4-aminobutanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0054] Most preferably, the lactams or ω-amino acids are selected from the group consisting of ε-caprolactam (6 C atoms), laurolactam (12 C atoms), 6-aminohexanoic acid and 12-aminododecanoic acid.

[0055] Preferably, the amorphous or microcrystalline polyamide is formed from at least one diamine and at least one dicarboxylic acid and optionally from at least one lactam and / or at least one ω-amino acid and contains at least one cycloaliphatic diamine or at least one aliphatic diamine with an aromatic structural component or at least one aromatic dicarboxylic acid.

[0056] Preferably, the at least one cycloaliphatic diamine or the at least one aliphatic diamine with an aromatic structural component is selected from the group consisting of bis(aminocyclohexyl)methane and its alkyl derivatives, bis(aminocyclohexyl)propane and its alkyl derivatives, isophoronediamine, norbornanediamine, bis(aminomethyl)norbornane, xylylenediamine, cyclohexanediamine, bis(aminomethyl)cyclohexane and its alkyl derivatives.

[0057] In particular, it is preferred if the amorphous or microcrystalline polyamides are selected from the group consisting of PA 6I, PA 6I / 6T, PA 6I / 6T / 6N, PA MXDI / 6I, PA MXDI / MXDT / 6I / 6T, PA MXDI / 12I, PA MXDI, PA MXDI / MXD6, PA MACM10, PA MACM12, PA MACM14, PA MACM18, PA NDT / INDT, PA TMDC10, PA TMDC12, PA TMDC14, PA TMDC18, PA PACM12, PA PACM14, PA PACM18, PA PACM10 / 11, PA PACM10 / 12, PA PACM12 / 612, PA PACM12 / PACM14 / 612 / 614, PA MACMI / 12, PA MACMT / 12, PA MACMI / MACM12, PA MACMI / MACMN, PA MACMT / MACM12, PA MACMT / MACMN, PA MACM36, PA TMDC36, PA MACMI / MACM36, PA 6I / MACMI / 12, PA MACMT / MACM36, PA MACMI / MACMT / 12, PA 6I / 6T / MACMI / MACMT, PA 6I / 6T / MACMI / MACMT / 12, PA MACM6 / 11, PA MACM6 / 12, PA MACM10 / 11, PA MACM10 / 12, PA MACM10 / 1010, PA MACM12 / 1012, PA MACM12 / 1212, PA MACM14 / 1014, PA MACM14 / 1214, PA MACM18 / 1018, PA 6I / 6T / MACMI / MACMT / MACM12 / 612, PA 6I / 6T / MACMI / MACMT / MACM12, PA MACMI / MACMT / MACM12 / 12, PA MACMI / MACMT / MACM12, PA 6I / 6T / MACMI / MACMT / 12, PA 6I / 6T / 6N / MACMI / MACMT / MACMN, PA TMDC12 / TMDCT / TMDC36,PA TMDC12 / TMDCI, PA TMDC12 / TMDCI / TMDC36 and PA TMDC12 / TMDCT and mixtures or copolymers thereof, wherein the MACM may be replaced by PACM and / or TMDC up to a maximum of 35 mol%, based on the sum of the molar proportions of all monomers of 100 mol% and / or the laurolactam may be completely or partially replaced by caprolactam.

[0058] With regard to the naphthalenedicarboxylic acid content, an amount of a maximum of 10 mol%, based on the sum of the molar proportions of all monomers of 100 mol%, is preferred.

[0059] The lactam and / or ω-amino acid content of the amorphous or microcrystalline polyamide is 0 to 40 mol%, preferably 0 to 35 mol%, based on the sum of the molar proportions of all monomers of 100 mol%.

[0060] Das amorphous oder mikrokristalline Polyamid ist besonders beserbett geschäftung aus der Gruppe bestehen aus PA 6I / 6T, PA MXDI / 6I, PA MXDI / MXD6, PA MACM10, PA MACM12, PA MACM14, PA MACM18, PA MACM36, PA TMDC10, PA TMDC12, PA TMDC14, PA TMDC18, PA PACM12, PA PACM14, PA PACM18, PA NDT / INDT, PA PACM10 / 11, PA PACM10 / 12, PA PACM12 / 612, PA PACM12 / PACM14 / 612 / 614, PA MACMI / 12, PA MACMT / 12, PA MACMI / MACM12, PA MACMT / MACM12, PA MACMI / MACMT / 12, PA MACMI / MACMT / MACM12 / 12, PA MACMI / MACMT / MACM12, PA 6I / 6T / MACMI / MACMT, PA 6I / 6T / MACMI / MACMT / 12, PA 6I / 6T / MACMI / MACMT / MACM12 / 12, PA 6I / 6T / MACMI / MACMT / MACM12, PA MACM6 / 11, PA MACM6 / 12, PA MACM10 / 11, PA MACM10 / 12, PA MACM10 / 1010, PA MACM12 / 1012, PA MACM12 / 1212, PA MACM14 / 1014, PA MACM14 / 1214, PA MACM10 / PACM10, PA MACM12 / PACM12, PA MACM14 / PACM14, PA MACM18 / PACM18, PA 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12, PA 6I / 6T / MACMI / MACMT / MACM12 / PACMI / PACMT / PACM12 und Mischungen oder Copolymeren hiervon.

[0061] The amorphous or microcrystalline polyamide is most preferably selected from the group consisting of PA MXDI / 6I, PA MXDI / MXD6, PA MACM10, PA MACM12, PA MACM14, PA MACM18, PA TMDC10, PA TMDC12, PA PACM12, PA PACM14, PA PACM18, PA NDT / INDT, PA PACM12 / 612, PA PACM12 / PACM14 / 612 / 614, PA MACMI / 12, PA MACMT / 12, PA MACMI / MACM12, PA MACMI / MACMT / 12, PA MACMI / MACMT / MACM12, PA 6I / 6T / MACMI / MACMT / 12, PA MACM10 / 1010, PA MACM12 / 1012, PA MACM12 / 1212, PA MACM14 / 1014, PA MACM14 / 1214, PA MACM10 / PACM10, PA MACM12 / PACM12, PA MACM14 / PACM14, PA MACM18 / PACM18 and PA 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12.

[0062] The proportion of 1,6-hexanediamine in the PA MXDI / 6I is preferably 15 to 40 mol%, particularly preferably 20 to 35 mol%, with the sum of the molar proportions of all monomers being 100 mol%. The PA MXDI / 6I particularly preferably has a molar ratio of 46 / 54.

[0063] The proportion of 1,6-hexanediamine in the PA PACM12 / 612 is preferably 2 to 24 mol%, particularly preferably 6 to 15 mol%, the sum of the molar proportions of all monomers being 100 mol%.

[0064] The proportion of 1,6-hexanediamine in PA PACM12 / PACM14 / 612 / 614 is preferably 2 to 24 mol%, particularly preferably 6 to 15 mol%, with the sum of the molar proportions of all monomers being 100 mol%. The proportion of 1,14-tetradecanedioic acid in PA PACM12 / PACM14 / 612 / 614 is preferably 2 to 24 mol%, particularly preferably 6 to 15 mol%, with the sum of the molar proportions of all monomers being 100 mol%.

[0065] Among the PA MACMI / 12s, those with a laurolactam content of 15 to 50 mol% are preferred, with the sum of the molar fractions of all monomers equal to 100 mol%. PA MACMI / 12s with a laurolactam content of 20 to 40 mol% are particularly preferred. PA MACMI / 12s with a laurolactam content of 19 mol% or 35 mol% are especially preferred.

[0066] Among the PA MACMI / MACMT / 12, those with an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 15 to 40 mol% are preferred, with the sum of the molar proportions of all monomers equal to 100 mol%. Particularly preferred are PA MACMI / MACMT / 12 with an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 20 to 30 mol%. Particularly preferred is PA MACMI / MACMT / 12 with a molar ratio of 38 / 38 / 24.

[0067] Among the PA MACMI / MACMT / MACM12, those with an equimolar ratio of isophthalic acid to terephthalic acid and a dodecanedioic acid content of 30 to 60 mol% are preferred, with the sum of the molar proportions of all monomers equal to 100 mol%. Particularly preferably, the PA MACMI / MACMT / MACM12 has an equimolar ratio of isophthalic acid to terephthalic acid and a dodecanedioic acid content of 40 to 50 mol%. Especially preferably, the PA MACMI / MACMT / MACM12 has a molar ratio of 27 / 27 / 46.

[0068] Among the PA 6I / 6T / MACMI / MACMT / 12, those with an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 1 to 25 mol% are preferred, with the sum of the molar proportions of all monomers equal to 100 mol%. Particularly preferably, the PA 6I / 6T / MACMI / MACMT / 12 has an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 2 to 15 mol%. Especially preferably, the PA 6I / 6T / MACMI / MACMT / 12 has a molar ratio of 34 / 34 / 14 / 14 / 4.

[0069] The proportion of the linear aliphatic diamine in PA MACM10 / 1010, PA MACM12 / 1012, PA MACM12 / 1212, PA MACM14 / 1014, PA MACM14 / 1214 is preferably 5 to 45 mol%, particularly preferably 8 to 27 mol%, very particularly preferably 10 to 22 mol%, the sum of the molar proportions of all monomers being 100 mol%.

[0070] The proportion of PACM in PA MACM10 / PACM10, PA MACM12 / PACM12, PA MACM14 / PACM14 or PA MACM18 / PACM18 is preferably 1 to 35 mol%, particularly preferably 2 to 25 mol%, the sum of the molar proportions of all monomers being 100 mol%.

[0071] Among the PA 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12, those with an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 1 to 25 mol% are preferred, with the sum of the molar proportions of all monomers equal to 100 mol%. Particularly preferably, the PA 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12 have an equimolar ratio of isophthalic acid to terephthalic acid and a laurolactam content of 2 to 15 mol%. Especially preferably, the PA 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12 have an equimolar ratio of isophthalic acid to terephthalic acid, a PACM content of 2 to 7 mol%, and a laurolactam content of 2 to 7 mol%.

[0072] The polyamide granulate exhibits a light transmission measured according to ASTM D 1003 on plates of thickness 2 mm (manufactured in a highly polished tool) of at least 75%, preferably of at least 83%, particularly preferably of at least 88% and most particularly preferably of at least 90%.

[0073] In mixtures of amorphous or microcrystalline and at least one semi-crystalline aliphatic polyamide, the proportion of semi-crystalline aliphatic polyamide is 2 to 40 wt.%, preferably 3 to 30 wt.%, particularly preferably 10 to 20 wt.%.

[0074] The at least one semi-crystalline aliphatic polyamide as a blend component for the amorphous or microcrystalline polyamides is preferably selected from the group consisting of PA 6, PA 46, PA 49, PA 410, PA 411, PA 412, PA 413, PA 414, PA 415, PA 416, PA 418, PA 436, PA 66, PA 69, PA 610, PA 611, PA 612, PA 613, PA 614, PA 615, PA 616, PA 617, PA 618, PA 1010, PA 66 / 6, PA 6 / 66 / 12, PA 6 / 12, PA 11, PA 12, PA 912, PA 1212, PA MXD6, PA MXD9, PA MXD10, PA MXD11, PA MXD12, PA MXD13, PA MXD14, PA MXD15, PA MXD16, PA MXD17, PA MXD18, PA MXD36, PA PACM9, PA PACM10, PA PACM11, PA PACM12, PA PACM13, PA PACM14, PA PACM15, PA PACM16, PA PACM17, PA PACM18, PA PACM36, polyetheramides, polyetheresteramides, polyesteramides and their mixtures or copolymers.

[0075] Particularly preferably, the semi-crystalline aliphatic polyamide is selected from the group consisting of PA 6, PA 69, PA 610, PA 612, PA 614, PA 1010, PA 1212, PA 6 / 66 / 12, PA 6 / 66, PA 6 / 12, PA 11, PA 12, polyetheramides and polyetheresteramides.

[0076] In mixtures of amorphous or microcrystalline polyamides and at least one impact modifier, the proportion of impact modifier is 2 to 14 wt.%, preferably 4 to 12 wt.%.

[0077] The at least one impact modifier as a mixture component for the amorphous or microcrystalline polyamides is preferably selected from the group consisting of acrylate copolymers, acrylic acid copolymers, vinyl acetate copolymers, styrene copolymers, styrene block copolymers, core-shell impact modifiers and mixtures thereof.

[0078] Particularly preferably, the impact modifier is selected from the group consisting of ethylene-glycidyl methacrylate copolymers, ethylene-acrylate copolymers, styrene-butadiene-styrene triblock copolymers (SBS), styrene-ethylene / butylene-styrene triblock copolymer (SEBS), methacrylate-butadiene-styrene core-shell impact modifiers and mixtures thereof.

[0079] The at least one impact modifier is preferably functionalized, either by copolymerization or by grafting with unsaturated carboxylic acids, unsaturated carboxylic acid derivatives and / or unsaturated glycidyl compounds.

[0080] The relative viscosity (RV) of the amorphous or microcrystalline polyamides is preferably 1.35 to 2.15, preferably 1.40 to 1.85, particularly preferably 1.45 to 1.75, measured with 0.5 g in 100 ml of m-cresol at 20°C. The relative viscosity (RV) of the semi-crystalline aliphatic polyamides is preferably 1.40 to 2.15, preferably 1.45 to 2.0, particularly preferably 1.50 to 1.90, measured with 0.5 g in 100 ml of m-cresol at 20°C.

[0081] The polyamide granules may additionally contain further additives, in particular selected from the group consisting of condensation catalysts, chain regulators, defoamers, inorganic stabilizers, organic stabilizers, lubricants, dyes, marking agents, pigments, dyes, nucleating agents, crystallization inhibitors, antistatic agents, mold release agents, optical brighteners, natural phyllosilicates, synthetic phyllosilicates and mixtures thereof.

[0082] Antioxidants, antiozonants, light stabilizers, UV stabilizers, UV absorbers or UV blockers can be used as stabilizers or anti-aging agents in amorphous or microcrystalline polyamides.

[0083] The further additives may preferably be present in an amount of 0.01 to 6 wt.%, based on the total polyamide molding compound.

[0084] A container for the storage and transport of polyamide granules containing at least one amorphous or microcrystalline polyamide is also described. In addition to the polyamide granules, this container also contains at least one oxygen absorber to prevent or reduce the yellowing of molded articles produced from the granules.

[0085] The container has a barrier effect against oxygen and moisture, i.e., the container is essentially gas- and moisture-tight, and is preferably selected from the group consisting of sacks, pouches, big bags, boxes, octabins, barrels, buckets, canisters, and cans. The container preferably has a capacity of 1 to 1000 kg of polyamide granules, more preferably 5 to 700 kg, most preferably 15 to 200 kg, especially 18 to 28 kg.

[0086] The oxygen barrier essentially prevents the penetration of additional oxygen from the ambient air into the container. For this purpose, the container contains at least one barrier layer, which is selected in particular from the group consisting of metal, aluminum, ethylene-vinyl alcohol copolymers (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), and combinations thereof.

[0087] To prevent the penetration of moisture, the container also contains a barrier layer, which is in particular selected from the group consisting of metal, aluminum, polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), polyolefins, polyethylene and combinations thereof.

[0088] Depending on the material from which the barrier layer is made, it can be effective against both the penetration of oxygen and the penetration of moisture.

[0089] For bags, for example, a laminate with a structure of PE / PE / Alu / PE / PE and layer thicknesses of 100 / 25 / 7 / 25 / 100 µm is used.

[0090] Big bags, boxes, and octabins also contain liners that provide a barrier against oxygen and moisture. Drums, buckets, canisters, and cans may contain liners that provide a barrier against oxygen and moisture, provided they are not made of metal.

[0091] The barrier effect is particularly preferably ensured by one or more layers of aluminum. The thickness of each aluminum layer is 4 to 15 µm.

[0092] Inliners are sleeves made of extruded or laminated films with one or more layers. The films for inliners can be simpler in construction than films for sacks or bags themselves, since the mechanical strength of packaging with inliners is already ensured by the outer packaging, e.g., a box, octabin, or drum.

[0093] Sacks or bags may contain single-layer or multi-layer inliners without oxygen barrier to improve the mechanical properties of the packaging, in particular toughness or puncture resistance.

[0094] There are no restrictions on how the oxygen absorber is placed in the packaging. It is only necessary to ensure that the oxygen absorber is not processed together with the polyamide granules. If the oxygen absorber is added to the polyamide granules in the form of sachets, this can be done, for example, by means of warning labels on the outside of the packaging. Particularly if several sachets are used, these can be gathered in a net or cage for easier removal before the granules are processed. The sachets, net or cage can also be fixed to the inside of the packaging in contact with the residual air, for example by gluing, stapling or sewing. In a preferred embodiment, the sachets, nets or cages are provided with an extension, e.g. a cord or tab, for easier fastening.By means of this extension, the oxygen absorber can be fixed to the sealing seam, for example during the sealing of the sack, bag or inliner.

[0095] The oxygen absorber can also be incorporated into one of the innermost layers of the packaging, whereby the layers between the polyamide granules and the layer containing the oxygen absorber must be oxygen-permeable. The oxygen absorber is preferably incorporated into the innermost or second-innermost layer. The oxygen absorber is preferably an oxidizable metal powder or an oxidizable polymer.

[0096] If the oxygen absorber is an oxidizable polymer, one of the innermost layers of the packaging can be formed from it, preferably the innermost or second-innermost layer. If the oxidizable polymer is a polyamide, it is preferably incorporated into the innermost or second-innermost layer, or this layer is made from it. The second-innermost layer is particularly preferably made from polyamide.

[0097] A polyamide granulate stored or transported according to the previously described process is also described. A polyamide granulate stored at 60 °C for six weeks according to this process exhibited, after further processing into 2 mm thick sheets, a yellow index that was at least 0.2, preferably at least 0.7, particularly preferably at least 1.3, and most preferably at least 1.8 lower than the yellow index of an identically manufactured 2 mm thick sheet that was stored and transported under otherwise identical conditions without the addition of an oxygen absorber. Carrying out the storage tests

[0098] For storage, 35 cm x 53.5 cm bags made of a PET / aluminum / PE laminate with layer thicknesses of 12 / 9 / 100 µm, solvent-free laminated with 2-component adhesive were used (supplier: Vacopack H. Buchegger AG, Switzerland).

[0099] Unstored polyamide granules were molded into 60 x 60 x 2 mm sheets. The yellow index of these sheets is the yellow index at 0 h of storage. The values given are the arithmetic mean of the measurements on five sheets.

[0100] 2 kg of polyamide granules were weighed into the bag. Depending on the storage test, one sachet of oxygen absorber S1 or S2 was placed in the bag or not. The remaining air was pressed out, and the bag was hermetically sealed just above the fill line. This compression of the bag prior to sealing ensures that residual air is only present between the individual granules.

[0101] One bag each with and without an oxygen absorber sachet was stored in a drying oven at 60 °C for two, four, or six weeks. After storage, the bags were opened, the polyamide granules were molded into 60 x 60 x 2 mm plates, and the yellow index of these plates was measured. The values given are the arithmetic mean of the measurements on five plates. Calculation of the residual air quantity

[0102] The residual air quantity is calculated from the initial weight, the bulk density and the density of the polyamide granulate, using the formula (I): Restluft − Menge in ml = Einwaage in g / Schüttdichte in g / ml − Einwaage in g / Dichte in g / ml

[0103] In the case of non-compressible containers, the unused volume of the container remaining above the polyamide granulate must of course also be taken into account when calculating the residual air quantity. Production of the panels 60 x 60 x 2 mm

[0104] The sheets were manufactured on an Arburg Allrounder 420 C 1000-250 injection molding machine. Cylinder temperatures ranged from 260 to 300 °C. The mold temperature was 80 to 100 °C.

[0105] The plates were used in a dry state; for this purpose, they were stored for at least 48 h at room temperature in a dry environment, ie, over silica gel, after injection molding.

[0106] The following measurement methods were used in this application: Relative viscosity: ISO 307 Granules 0.5 g in 100 ml m-cresol Temperature 20 °C Calculation of the relative viscosity (RV) according to RV = t / t 0 in accordance with section 11 of the standard.

[0107] Glass transition temperature (Tg), heat of fusion and melting point: ISO 11357 Granules Differential scanning calorimetry (DSC) was performed at a heating and cooling rate of 20 K / min. The melting point is given as the temperature at the peak maximum. The midpoint of the glass transition region, which is given as the glass transition temperature (Tg), was determined using the half-step height method.

[0108] Yellow Index ASTM E313 plate 60 x 60 x 2 mm temperature 23 °C

[0109] The following examples are intended to explain the subject matter of the invention in more detail, without wishing to restrict it to the specific embodiments shown here.

[0110] Table 1 lists the materials used in the examples and comparative examples. Table 1 material Description Manufacturer Polyamide A1 amorphous polyamide MACM12 from bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid EMS-CHEMIE AG, Switzerland RV* 1.70 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 155 °C Density 1.00 g / ml, bulk density 0.630 g / ml Polyamide A2 amorphous polyamide 6I / 6T / MACMI / MACMT / PACMI / PACMT / 12 in the molar ratio 39 / 39 / 7.1 / 7.1 / 2.5 / 2.5 / 2.8 from 1,6-hexanediamine, bis(3-methyl-4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)methane, isophthalic acid, terephthalic acid and laurolactam EMS-CHEMIE AG, Switzerland RV* 1.62 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 159 °C Density 1.15 g / ml, bulk density 0.685 g / ml Polyamide A3 microcrystalline polyamide MACM12 / PACM12 made from bis(3-methyl-4-amino-cyclohexyl)methane, bis(4-amino-cyclohexyl)methane and 1,12-dodecanedioic acid EMS-CHEMIE AG, Switzerland Molar ratio MACM: PACM = 30:70 RV* 1.80 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 145 °C, melting point 237 °C Density 1.02 g / ml, bulk density 0.650 g / ml Polyamide A4 amorphous polyamide MACMI / MACMT / 12 in the molar ratio 38 / 38 / 24 from bis(3-methyl-4-amino-cyclohexyl)methane, isophthalic acid, terephthalic acid and laurolactam EMS-CHEMIE AG, Switzerland RV* 1.53 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 190 °C Density 1.06 g / ml, bulk density 0.645 g / ml Polyamide A5 amorphous polyamide MACMI / 12 in a molar ratio of 65 / 35 from bis(3-methyl-4-amino-cyclohexyl)methane, isophthalic acid and laurolactam EMS-CHEMIE AG, Switzerland RV* 1.56 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 160°C Density 1.06 g / ml, bulk density 0.645 g / ml Polyamide A6 amorphous polyamide 6I / 6T from hexamethylenediamine, isophthalic acid and terephthalic acid EMS-CHEMIE AG, Switzerland Molar ratio of isophthalic acid to terephthalic acid 67 : 33 RV* 1.54 (measured with 0.5 g in 100 ml m-cresol at 20 °C) Glass transition temperature 125 °C Density 1.18 g / ml, bulk density 0.715 g / ml Oxygen absorber S1 Sachets with iron powder (approx. 3.1 g) and zeolite (approx. 1.3 g) with Mitsubishi Gas Chemical Company Inc., Japan Sodium chloride coating Size** of iron particles: 100 - 400 µm Trade name: Ageless ZPT-200 Oxygen absorber S2 Sachets with iron powder (approx. 6.4 g) and zeolite (approx. 4.2 g) with Mitsubishi Gas Chemical Company Inc., Japan Sodium chloride coating Size** of iron particles: 100 - 400 µm Trade name: Ageless ZPT-500 * RV relative viscosity, measured on a solution of 0.5 g polyamide in 100 ml m-cresol at 20 °C ** Determined by scanning electron microscopy

[0111] Table 2 shows a comparison of the yellow index of polyamide A1 granules for different storage times at a temperature of 60 °C. The granules stored in the container according to the invention are compared with identical granules stored in containers without oxygen absorbers. Table 2 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A1 without oxygen absorbers VB1 - 0.6 1.8 2.4 3.3 Granules A1 with oxygen absorber S1 B2 - 0.6 1.0 1.2 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0112] Table 3 shows the yellow index for a granulate made of polyamide A2 for different storage times at a temperature of 60 °C. The granulate stored in the container according to the invention is compared with identical granulates stored in containers without oxygen absorbers. Table 3 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A2 without oxygen absorbers VB3 - 2.1 4.7 6.0 6.3 Granules A2 with oxygen absorber S1 B4 - 3.0 3.7 4.4 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0113] Table 4 shows the yellow index of the polyamide A3 granules for different storage times at a temperature of 60 °C. The granules stored in the container according to the invention are compared with identical granules stored in containers without oxygen absorbers. Table 4 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A3 without oxygen absorbers VB5 - 0.2 1.0 2.0 2.8 Granules A3 with oxygen absorber S1 B6 - 0.3 0.3 1.0 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0114] The residual air quantity was calculated according to formula (I) for Example B6 with the microcrystalline polyamide granules A3 (PA MACM12 / PACM12 molar ratio 30:70) from the initial weight (2000 g), the bulk density (0.650 g / ml), and the density (1.02 g / ml) of the polyamide granules A3 to be 1116 ml. In Example B6, 49.7 mmol of iron were used as an oxygen absorber per liter of residual air.

[0115] Table 5 shows the yellow index of the polyamide A4 granules for different storage times at a temperature of 60 °C. The granules stored in the container according to the invention are compared with identical granules stored in containers without oxygen absorbers. Table 5 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A4 without oxygen absorbers VB7 - 1.3 5.0 5.6 6.3 Granules A4 with oxygen absorber S1 B8 - 3.1 3.6 3.6 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0116] Table 6 shows the yellow index of the polyamide A5 granules for different storage times at a temperature of 60 °C. The granules stored in the container according to the invention are compared with identical granules stored in containers without oxygen absorbers. Table 6 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A5 without oxygen absorbers VB9 - 2.4 3.2 4.1 4.1 Granules A5 with oxygen absorber S1 B10 - 2.1 3.1 3.2 Granules A5 with oxygen absorber S2 B11 - 1.2 2.3 2.8 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0117] The residual air quantity was calculated according to formula (I) for Examples B10 and B11 using amorphous polyamide granules A5 (PA MACMI / 12 molar ratio 65:35) to be 1214 ml. In Example B10, 45.7 mmol of iron were used as oxygen absorber per liter of residual air, whereas in Example B11, 94.4 mmol were used. The comparison of the values for Examples B10 and B11 thus demonstrates the advantage of using a higher amount of oxygen absorber.

[0118] Table 7 shows the yellow index of the polyamide A6 granules for different storage times at a temperature of 60 °C. The granules stored in the container according to the invention are compared with identical granules stored in containers without oxygen absorbers. Table 7 Experiment number Unit Yellow Index* Storage period h 0 336 672 1008 Granules A6 without oxygen absorbers VB12 - 3.6 5.0 6.0 6.1 Granules A6 with oxygen absorber S1 B13 - 4.0 5,3 5.9 Granules A6 with oxygen absorber S2 B14 - 3.6 5.2 5.3 * measured on plates 60 x 60 x 2 mm made from the stored granulate

[0119] Tables 2 to 7 show that, regardless of whether the stored polyamide granules were amorphous or microcrystalline, the addition of an iron powder-based oxygen absorber (S1 or S2) reduced the Yellow Index of the boards produced from the stored polyamide granules. This positive effect was observed for all storage periods (2, 4, and 6 weeks, respectively).

[0120] Tables 7 and 8, when comparing the values of examples B10 and B11 and B13 and B14, also demonstrate the advantage of using an increased amount of oxygen absorber since S2 contains more iron powder than S1.

Claims

1. Method for storage and for transport of polyamide granulate, comprising at least one amorphous or microcrystalline polyamide, whilst avoiding or reducing yellowing of moulded articles produced from the granulate, in which method the polyamide granulate is kept in a container with a barrier effect relative to oxygen and moisture, at least one oxygen absorber being provided in the container and producing an essentially oxygen-free atmosphere in the container, and wherein the container comprises at least one barrier layer.

2. Method according to claim 1, characterised in that the oxygen absorber comprises at least one oxidisable metal compound selected from the group of oxidisable metal powders, oxidisable metal oxides, oxidisable metal salts or mixtures hereof, the quantity of oxidisable metal compound in the container being preferably in the range of 20 to 400 mmol per litre of residual volume in the container.

3. Method according to one of the preceding claims, characterised in that the oxygen absorber is filled into sachets, the sachets consisting preferably of oxygen-permeable materials, in particular made of paper, polyolefins, material, filter paper, textile membranes, materials provided with holes or micropores or combinations thereof.

4. Method according to one of the preceding claims, characterised in that the oxygen absorber is an oxidisable organic or inorganic compound or an enzyme.

5. Method according to one of the preceding claims, characterised in that the oxygen absorber is an oxidisable polymer, the oxidisable polymer being disposed preferably as one of the innermost polymer layers in the container or being incorporated in one of the innermost polymer layers of the container.

6. Method according to one of the preceding claims, characterised in that the at least one barrier layer is selected from the group consisting of metal, aluminium, ethylene-vinyl alcohol copolymers (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), polyolefins, polyethylene and combinations thereof.

7. Method according to one of the preceding claims, characterised in that the amorphous or microcrystalline polyamide is formed from at least one diamine and at least one dicarboxylic acid and possibly from at least one lactam.

8. Method according to one of the preceding claims, characterised in that the amorphous or microcrystalline polyamide is formed from at least one diamine and at least one dicarboxylic acid and possibly from at least one lactam, and comprises at least one cycloaliphatic diamine or at least one aliphatic diamine with an aromatic structural component, or at least one aromatic dicarboxylic acid.

9. Method according to claim 8, characterised in that the at least one cycloaliphatic diamine or the at least one aliphatic diamine with an aromatic structural component is selected from the group consisting of bis(aminocyclohexyl)methane and the alkyl derivatives thereof, bis(aminocyclohexyl)propane and the alkyl derivatives thereof, isophorone diamine, norbornane diamine, bis(aminomethyl)norbornane, xylylene diamine, cyclohexane diamine, bis(aminomethyl)cyclohexane and the alkyl derivatives thereof.

10. Method according to one of the preceding claims, characterised in that the polyamide granulate comprises at least one amorphous or microcrystalline polyamide or mixtures of at least one amorphous or microcrystalline polyamide with at least one partially crystalline polyamide and / or with at least one impact modifier.