METHOD FOR LOWERING THE CRYSTALIZATION TEMPERATURE OF SEMI-CRYSTALLINE POLYAMIDES, POLYAMIDE MOLDING MATERIAL PRODUCED THEREBY, AND THE USE OF ORGANIC PHOSPHORUS COMPOUNDS FOR LOWERING THE CRYSTALIZATION TEMPERATURE

Description

[0001] Thermoplastic polymers exist in either amorphous or (semi-)crystalline form. In amorphous polymers, the polymer chains are disordered. Amorphous polymers such as polystyrene, PVC, or polycarbonate are often transparent, glossy, mechanically brittle, and frequently exhibit low chemical resistance. When processed using the melting process, their flowability is comparatively low; however, the shrinkage of a molded part made with these amorphous polymers is low, which is advantageous. In (semi-)crystalline polymers, the polymer chains are arranged in an ordered manner in so-called lamellae. (Semi-)crystalline polymers such as polypropylene, polyester, or polyamide are usually opaque with tough, hard mechanical properties and good chemical resistance. Flowability during melting is often high, but shrinkage in the molded part is pronounced.Semicrystalline polymers exhibit both crystalline regions and an amorphous phase. The properties of semicrystalline polymers are determined, among other things, by the proportion of crystallites to amorphous regions (the so-called degree of crystallinity), the shape of the crystallites (so-called spherolites), and their size, number, and distribution within the amorphous matrix.

[0002] To specifically tailor certain properties of plastics during processing and application, the crystallization behavior of plastics can be influenced by processing conditions and also by appropriate additives. For example, so-called nucleating agents (or nucleating agents) are frequently added to the plastic. These additives can then reduce cycle times in the manufacturing process, increase the transparency of the plastic, and improve mechanical properties and heat resistance (see, e.g., J. Kurja, N.A. Mehl, Nucleating agents for semi-crystalline polymers in Plastics Additives Handbook, 6th Edition, H. Zweifel, R.D. Maier, M. Schiller (Editors), Munich 2009, pp. 967–990). A variety of chemical classes are used as nucleating agents, such as sorbitol derivatives, metal phosphates or arylamides in polypropylene, and alkali metal salts.Sodium benzoate in polyethylene terephthalate (PET) and talc or alkaline earth salts of adipic acid in polyamides. The selection of suitable nucleating agents depends on the polymer, its chemical structure, and its crystallization behavior. The physical and chemical processes involved in the nucleation of polymers are described, for example, in JP Mercier, Pol. Eng. Sci. 1990, 30, 270-278.

[0003] On the other hand, it may also be desirable for certain applications to prevent or delay the crystallization of semi-crystalline polymers. However, there are very few additives that can achieve this. For example, in polyesters, crystallization is restricted by the addition of SAN or polystyrene (RMR Wellen, MS Rabello, J. Appl. Pol. Sci. 2009, 114, 1884-1895; RMR Wellen, MS Rabello, J. Appl. Pol. Sci. 2010, 116, 1077-1078; RMR Wellen, EL Canedo, MS Rabello, J. Appl. Pol. Sci. 2012, 125, 2701-2710). In polyamides, aromatic compounds (US 2005 / 0234159) are among those proposed for this purpose.

[0004] Various classes of substances have been investigated for the production of (partially) crystalline polymers, particularly polyamides, with delayed crystallization or a lowered crystallization point, such as polycyclic aromatics (US 2005 / 0234159), including, in particular, dyes like nigrosine or various metal salts (DE 2012105, DE 2229803) such as lithium salts or calcium chloride. Further details are contained in the applicant's own application WO 2016 / 091807, which describes an improved embodiment for a polyamide with delayed crystallization in the combination of azine dyes with metal salts.

[0005] Phosphites and phosphonites are known as processing stabilizers and so-called secondary antioxidants and are used in many polymers. Mechanistically, this effect involves a reaction with the hydroperoxides formed during oxidative degradation, resulting in the reduction of the hydroperoxide and the oxidation of the phosphite / phosphonite to the corresponding phosphate / phosphonate. This well-established mechanism is fundamentally independent of the structure of the specific phosphite / phosphonite.

[0006] However, it is not yet known that selected phosphites / phosphonites or phosphates with at least 3 substituents lead to branched polyamides with reduced crystallization temperature or delayed crystallization behavior via a transesterification / umamidation reaction.

[0007] EP 0407926 describes phosphorus compounds as crystallization retarders in polyphenylene ether molding compounds. Polyphenylene sulfide is described as a semi-crystalline polymer as an example. However, this is a completely different polymer structure, so it is not possible to infer an antinucleating effect on polymers of a different structure. Furthermore, the addition of the phosphite of a specific structure leads to a significant increase in crystallinity (evident from the increased heat transfer in Table 1 upon addition of the phosphorus compound), meaning the additive acts in the opposite way, as a nucleating agent.

[0008] EP 0633287 describes the improvement of polypropylene's transparency through the addition of phosphonites / phosphites, which act as nucleating agents. It cannot be concluded from this that these substances behave similarly in polyamide, nor is it foreseeable that the opposite effect, namely antinucleation, would occur there.

[0009] DE 3821325 describes polyamide molding compounds with improved translucency. Here, the phosphorus compound is added without affecting the processing properties (melt viscosities). Therefore, no branching of the polyamide structure is achieved; the effect of the phosphorus compound is nucleating.

[0010] EP 0770104 relates to the use of diphosphonites for the molecular weight increase of polycondensation polymers or combinations with reactive difunctional compounds, preferably for recyclates that have corresponding end groups due to prior damage. The patent makes no mention of the production of branched structures or a reduction in the crystallization temperature.

[0011] Y. Shu, L. Ye, T. Yang, J. Appl. Pol. Sci. 110 (2008), 945-958, Study on the long-term thermal-oxidative aging behavior of polyamide 6, compare the aging of polyamide 6 with and without a stabilizer mixture. The stabilizer mixture used contains, among other things, a phosphite. In the stabilized / unstabilized comparison, the crystallinity data show no influence on the crystallization temperature; in fact, during storage, the presence of the additives even leads to an increase in the crystallization temperature. Surprisingly, however, the process according to the invention results in a decrease in the crystallization temperature.

[0012] X. Meng et al., Pol. Degr. Stab. 120 (2015), 283-289, describe the reaction of polylactic acid (PLA) with phosphites and also report a reduction in crystallization. PLA is a polyester and not a polyamide. However, the crystallization is accelerated by the addition of phosphites, and the resulting degree of crystallization is higher.

[0013] B. Jacques et al. describe the reaction of polyesters, among other things, with triphenyl phosphite in the melt in Polymer 37 (1996), 1189-1200, Polymer 37 (1996), 4085-4097 and Polymer 38 (1997), 5367-5377. A decrease in the crystallization temperature is observed after the reaction, but this temperature increases after storage and then even exceeds that of the polyester without the additive. A key element for the molecular weight increase observed there is the reaction with OH end groups. However, polyamides do not have OH end groups, but rather -NH₂ end groups. No information is provided in this article regarding the behavior of phosphite in polyamide.

[0014] FP La Mantia et al. describe the recycling of polyamides in J. Appl. Pol. Sci. 86 (2002), 1899-1903. Their study compares the recycling of virgin material, recycled material, and the wet and dry state of the polyamides with the addition of diphosphonite. The diphosphonite acts as a stabilizer and desiccant; there is no increase in molecular weight, and the degree of crystallinity is higher than that of virgin material.

[0015] The additives described so far as antinucleating agents for polyamides, based on dyes or polycyclic compounds, have the disadvantage that the resulting polyamide is colored. In particular, the preferably highly effective antinucleating agent nigrosine, alone or in synergistic combinations, leads to a black product even at low concentrations. However, for the manufacturer of polyamide parts, it is advantageous not to have any limitations regarding color.

[0016] US Patent 4,417,032 A discloses a process for producing quasi-random copolymers, which involves heating a mixture of polyamides in the presence of one or more phosphite promoters. The process is carried out at temperatures between approximately 265 °C and 315 °C, with the process duration generally ranging from about 2 to about 20 minutes. The process is particularly suitable for producing copolymers from a mixture of poly(caproamide) and poly(hexamethylene adipamide). The copolymer products produced by the process are especially suitable for the production of plastic films that exhibit improved properties compared to the two homopolymers.

[0017] EP 0 770 104 A1 relates to a process for increasing the molecular weight of polycondensates and to the polycondensates obtainable by this process.

[0018] DE 38 21 325 A1 relates to polyamide molding compounds with improved translucency, containing A) 80 to 99.95 wt.% of a thermoplastic polyamide, B) 0.05 to 1.0 wt.% of a specific, more precisely defined phosphorus compound, and also C) 0 to 19.95 wt.% of B) various additives and processing aids.

[0019] WO 2016 / 091807 A1 concerns a polymer composition with delayed crystallization behavior, an additive composition influencing the crystallization behavior, a method for lowering the crystallization point and / or the crystallization rate, and the use of an additive composition.

[0020] Based on this, it is therefore an object of the present invention to provide semi-crystalline polyamides with crystallization delay or with a lowered crystallization point and a method for producing these polyamides which are essentially colorless (white) and thus do not impair a desired coloration for the application.

[0021] This problem is addressed with regard to a method for lowering the crystallization temperature of semi-crystalline polyamides with the features of claim 1, with regard to the use of multifunctional transesterifiable organic phosphonites, phosphites, phosphates and / or mixtures thereof for lowering the crystallization temperature or for crosslinking and / or branching of semi-crystalline polyamides with the features of claim 10, and a polyamide molding compound which can be produced in particular according to the method according to the invention.

[0022] The present invention thus relates in a first aspect to a method for lowering the crystallization temperature of semi-crystalline polyamides, in which a) at least one semi-crystalline polyamide or mixtures of at least two semi-crystalline polyamides are mixed with at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds, b) the mixture formed is transferred into a melt, whereby transesterification of the at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds takes place with simultaneous transamidation of the at least one semi-crystalline polyamide, and finally c) the mixture is cooled.

[0023] Surprisingly, it was found that the crystallization temperature of semi-crystalline polyamides can be lowered by adding multifunctional transesterifiable organic phosphonites, phosphites, phosphates, or mixtures thereof. This is completely unexpected and contradicts previously known findings for other thermoplastic polymer systems. For example, the previously discussed EP 0 407 926 shows that, upon addition of analogous phosphorus compounds to polyphenylene ether molding compounds, the corresponding phosphorus compounds act as nucleating agents. An acceleration of crystallization upon addition of corresponding phosphites has also been observed in polylactic acids (X. Meng et al.).

[0024] A preferred embodiment of the method according to the invention provides that the at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures thereof are used in an amount of 0.05 to 10 wt.%, preferably 0.1 to 5 wt.%, particularly preferably 0.4 to 4 wt.%, based on the total amount of the at least one semi-crystalline polyamide.

[0025] It is further advantageous if the at least one multifunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate has 3 to 6, preferably 3 to 4 transesterifiable functionalities.

[0026] In particular, the at least one multifunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate has a molecular weight of at least 600 g / mol.

[0027] The at least one multifunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate is selected from the group consisting of the following compounds (O) y P(OR) 3 , [(RO) 2 (O) y PO] z X [(RO) 2 P] z X where each is independent of each other y0 or 1, z2, 3 or 4, R is the same or different in each occurrence and is selected from the group consisting of linear or branched alkyl groups, unsubstituted or substituted aromatic groups, wherein any two groups (OR) arranged on the same phosphorus atom may also be connected to each other via a covalent bond, and X is a z-valent group selected from the group consisting of linear or branched, optionally heterosubstituted alkyl groups, unsubstituted or substituted aromatic groups.

[0028] Preferably, in the aforementioned compounds, each is independent of the other R2,4-di-tert-butylphenoxy, 2,6-di-tert-butyl-4-methylphenoxy, 2,4-di-((1-methyl-1-phenyl)ethyl)phenoxy or in the case that two residues (OR) arranged on the same phosphorus atom are also linked to each other via a covalent bond 3,3',5,5'-tetra-tert-butylbiphenyl-2,2'-dioxy, and X is selected from the group consisting of 4,4'-biphenyl, - (CH 2 ) 4 C and tri(2-ethyl)aminyl.

[0029] Preferred organic phosphites are selected from the group consisting of triphenyl phosphite, tri(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, (2,4-Di- tert -butylphenyl)diethyl phosphite, tris-(2,4-di- tert -butylphenyl) phosphite, tristearyl sorbitol triphosphite, bis-(2,4-di-tert-butyl-6-methylphenyl) phosphite, bis-(2,6-di- tert -butyl-4-methylphenyl)phosphite, 2,2',2''-nitrilo[triethyltris(3,3',5,5'-tetra- tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3',5,5'-tetra- tert -butyl-1,1'-biphenyl-2,2'-diyl)-phosphite, 3,9-Bis(2,4-di- tert -butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-Bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-Bis[4-methyl-2,6-bis(2-methyl-2-propanyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, and mixtures and combinations thereof,

[0030] Preferred phosphonites are selected from the group consisting of tetrakis-(2,4-di- tert -butylphenyl)-4,4'-biphenyl diphosphonite, Tetrakis-(2,4-dimethylphenyl)-4,4'-biphenyl diphosphonite, Tetrakis(2,4-bis(1,1-dimethylpropyl)phenyl)-4,4'-biphenyl diphosphonite, and mixtures thereof,

[0031] Preferred organic phosphates are selected from the group consisting of tris(octadecyl) phosphate, tris(dodecyl) phosphate, and mixtures thereof.

[0032] A transesterification catalyst, preferably tin, antimony and / or titanium compounds, such as tin(II) octoate, is preferably added to the mixture.

[0033] Mixtures of several transesterification catalysts can also be added.

[0034] According to a preferred embodiment, in step b) both the at least one semi-crystalline polyamide and the at least one multifunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate are melted.

[0035] Step b) is preferably carried out at temperatures of 230 to 350 °C, preferably 240 and 310 °C, particularly preferably 270 to 300 °C and / or over a period of 0.5 to 60 min, preferably 2 to 10 min.

[0036] Preferably, at least one semi-crystalline polyamide is selected from the group consisting of aliphatic polyamides, in particular PA 6, PA 66, PA610, PA 46, PA 410, PA 612, PA 1212, PA 1010, PA 10 / 12, PA 10, PA 11, PA 12, semi-aromatic polyamides derived from aromatic dicarboxylic acids, such as terephthalic acid and / or isophthalic acid and aliphatic diamines, such as hexamethylenediamine, or semi-aromatic polyamides derived from aliphatic dicarboxylic acids, such as adipic acid and / or sebacic acid and aromatic diamines, such as 1,3- and / or 1,4-diaminobenzene, or polyamide-imides derived from tricarboxylic anhydrides such as trimellitic anhydride and diamines, as well as mixtures or combinations thereof.

[0037] According to the invention, the at least one semi-crystalline polyamide is at least partially or completely end-group blocked.

[0038] It is also advantageous if at least one semi-crystalline polyamide has an amino end group concentration of < 30 meq / kg and / or a carboxylic acid end group concentration of < 30 meq / kg.

[0039] Particularly preferred polyamides are polyamide-6 and polyamide-6.6, as well as mixtures thereof.

[0040] The polymers mentioned can be present not only as virgin material but also in the form of recyclates, e.g. as production waste or from recycling ("post-consumer" recyclates), but virgin material is preferred because the recyclate has free end groups due to prior damage such as hydrolysis.

[0041] Preferred polyamides are end-group blocked, meaning they have no or only a small number of amine and / or acid end groups. This prevents or significantly reduces molecular weight gain via the end groups, thus favoring transesterification / umamidation reactions. Acid end groups, in particular, are to be avoided, as they react with, for example, triphosphites to form phenyl esters and phosphonates, resulting in a bifunctional compound and thus preventing further branching.

[0042] Multifunctional transesterifiable phosphonites and / or phosphites and / or phosphates typically have 3-6, optionally substituted, phenoxy groups, preferably 3-4, optionally substituted, phenoxy groups on the phosphorus group. Two transesterifiable groups are insufficient because no branching occurs; instead, the linearity of the polyamide is maintained under the processing conditions. With a higher number of phenoxy groups and increased concentrations, there is a risk of crosslinking of the polymer chains, which is often undesirable because it negatively affects the processing behavior.

[0043] Particularly favored phosphites / phosphonites are:

[0044] An example of a phosphate is tris(octadecyl)phosphate.

[0045] Furthermore, the phosphite / phosphonite / phosphate is selected such that it exhibits no or only low volatility at the necessary melting temperature of the polymer; therefore, phosphites / phosphonites / phosphates with a molecular weight of at least 600 g / mol are preferred.

[0046] The production of the polyamide according to the invention in the melt can, in principle, take place in any heatable reaction vessel or in a processing machine such as a kneader or extruder. Preferred processing machines include extruders such as single-screw extruders, twin-screw extruders, planetary roller extruders, ring extruders, and co-kneaders, which are preferably equipped with vacuum degassing. Vacuum degassing has the advantage that undesirable byproducts of the transesterification / umamidation reaction can be removed from the polymer. Processing can be carried out under atmospheric or, if necessary, inert gas conditions.

[0047] The present invention also relates to the use of multifunctional transesterifiable organic phosphonites, organic phosphites, organic phosphates or mixtures of at least two of the aforementioned compounds for lowering the crystallization temperature of semi-crystalline polyamides and / or for crosslinking and / or branching of semi-crystalline polyamides.

[0048] Another aspect of the present invention relates to a polyamide molding compound comprising a reaction product obtained by reacting at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds and at least one semi-crystalline polyamide, wherein the reaction involves transesterification of the at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds with simultaneous transamidation of at least one semi-crystalline polyamide.

[0049] The polyamide molding compound according to the invention can in particular be produced by means of the inventive method described at the outset.

[0050] Preferably, the reaction product obtained is a branched polyamide.

[0051] In addition, the polyamide molding compound according to the invention may contain additives selected from the group consisting of UV absorbers, light stabilizers, stabilizers, hydroxylamines, benzofurans, metal deactivators, filler deactivators, flame retardants, impact improvers, plasticizers, lubricants, rheology modifiers, processing aids, pigments, dyes, fillers, reinforcing agents, optical brighteners, antimicrobial agents, antistatic agents, slip agents, antiblocking agents, coupling agents, dispersing agents, compatibilizers, oxygen scavengers, acid scavengers, marking agents, antifogging agents, as well as mixtures and combinations of at least two of the aforementioned additives.

[0052] In particular, the polyamide molding compound according to the invention is free of nucleating agents, such as talc or sodium benzoate.

[0053] The polyamide molding compound according to the invention is preferably free of nigrosine.

[0054] In a preferred embodiment, the compositions contain in particular acid scavengers, e.g. based on salts of long-chain acids such as calcium stearate, magnesium stearate, zinc stearate, calcium lactate or hydrotalcites and / or stabilizers from the group of phenolic antioxidants and / or copper compounds and / or metal deactivators and / or light stabilizers from the group of hindered amines (HALS) and / or dispersants and / or flame retardants and / or pigments and / or fillers / reinforcing agents.

[0055] Suitable phenolic antioxidants include, for example: Octadecyl-3-(3,5-di- tert -butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di- tert -butyl-4-hydroxyphenyl)propionate, tris(3,5-di- tert -butyl-4-hydroxyphenyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di- tert-butyl-4-hydroxyphenyl)isocyanurat, 1,3,5-Trimethyl-2,4,6-tris(3,5-di- tert -butyl-4-hydroxybenzyl)benzol, Triethylenglycol-bis[3-(3- tert -butyl-4-hydroxy-5-methylphenyl)propionat, N,N'-Hexan-1,6-diyl-bis[3-(3,5-di- tert -butyl-4-hydroxyphenyl)propionsäureamid.

[0056] Weitere geeignete Stabilisatoren sind aminische Antioxidantien, wie z. B. N,N'-Di-isopropyl-p-phenylendiamin, N,N'-Di-sec-butyl-p-phenylendiamin, N,N'-Bis(1,4-dimethylpentyl)-p-phenylendiamin, N,N'-Bis(1-ethyl-3-methylpentyl)-p-phenylendiamin, N,N'-Bis(1-methylheptyl)-p-phenylen-diamin, N,N'-Dicyclohexyl-p-phenylendiamin, N,N'-Diphenyl-p-phenylen-diamin, N,N'-Bis(2-naphthyl)-p-phenylendiamin, N-Isopropyl-N'-phenyl-p-phenylendiamin, N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylen-diamin, N-(1-Methylheptyl)-N'-phenyl-p-phenylendiamin, N-Cyclohexyl-N'-phenyl-p-phenylendiamin, 4-(p-Toluolsulfamoyl)diphenylamin, N,N'-Dimethyl-N,N'-di-sec-butyl-p-phenylendiamin, Diphenylamin, N-Allyldiphenylamin, 4-Isopropoxydiphenylamin, N-Phenyl-1-naphthylamin, N-(4-tert-Octylphenyl)-1-naphthylamin, N-Phenyl-2-naphthylamin, octyliertes Diphenylamin, z.B.p,p'-Di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octa-decanoylaminophenol, bis(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N,N,N',N'-tetra-methyl-4,4'-diaminodiphenyl-methane, 1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane, (o-tolyl)biguanide, Bis[4-(1',3'-dimethylbutyl)phenyl]amine, . tert -octylated N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated tert -Butyl / tert -Octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopropyl / isohexyl diphenylamines, a mixture of mono- and dialkylated tert -Butyldiphenylamines, 2,3-Dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono- and dialkylated tert-Butyl / tert -Octylphenothiazines, a mixture of mono- and dialkylated tert -Octylphenothiazines, N-allylphenothiazine, N,N,N',N'-tetraphenyl-1,4-diaminobut-2-ene and mixtures or combinations thereof.

[0057] Other suitable amine antioxidants are hydroxylamines or N-oxides (nitrons), such as N,N-dialkylhydroxylamines, N,N-dibenzylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-distearylhydroxylamine, N-benzyl-α-phenylnitrone, N-octadecyl-α-hexadecylnitrone.

[0058] Other suitable stabilizers are thiosynergists. Examples of suitable thiosynergists are distearylthiodipropionate and dilauryldipropionate.

[0059] Other particularly suitable stabilizers for polyamides are copper salts such as halides, oxides or complexes, such as copper(I) oxide, copper(I) thiocyanate, copper(I) chloride, copper(I) bromide, copper(I) iodide, carboxylic acid salts such as copper(I) acetate, copper(I) stearate, copper(I) oxalate and complexes with the ligands triphenylphosphine, mercaptobenzimidazole, acetylacetonate, bipyridyl or glycine.

[0060] Other suitable stabilizers for polyamides are silver(I) salts such as Ag2O, AgBr or Agl.

[0061] Suitable light stabilizers include compounds based on 2-(2'-Hydroxyphenyl)benzotriazoles, 2-Hydroxybenzophenones, esters of benzoic acids, acrylates, oxamides and 2-(2-Hydroxyphenyl)-1,3,5-triazines.

[0062] Suitable hindered amines include, for example, 1,1-bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebazate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebazate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, linear or cyclic condensation products of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine, and 4-tert-Octylamino-2,6-dichloro-1,3,5-triazine, Tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate, Tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, 1,1'-(1,2-ethanediyl)-bis(3,3,5,5-tetramethyl-piperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, linear or cyclic condensation products of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the reaction product of 7,7,9,9-Tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro-[4,5]decane and epichlorohydrin.

[0063] Suitable metal deactivators include, for example, N,N'-diphenyloxamide, N-salicylal-N'-salicyloylhydrazine, N,N'-bis(salicyloyl)hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyldihydrazide, oxanilide, isophthaloyldihydrazide, sebacoyl-bisphenylhydrazide, N,N'-diacetyladipoyldihydrazide, N,N'-bis(salicyloyl)oxylyldihydrazide, and N,N'-bis(salicyloyl)thiopropionyldihydrazide. Suitable dispersing agents include, for example:

[0064] Polyacrylates, e.g., copolymers with long-chain side groups, polyacrylate block copolymers, alkylamides: e.g., N,N'-1,2-ethanediylbisoctadecanamide; sorbitan esters, e.g., monostearyl sorbitan esters; titanates and zirconates; reactive copolymers with functional groups, e.g., polypropylene-co-acrylic acid, polypropylene-co-maleic anhydride, polyethylene-co-glycidyl methacrylate; polystyrene-alt-maleic anhydride polysiloxanes: e.g., dimethylsilanediol-ethylene oxide copolymer, polyphenylsiloxane copolymer; amphiphilic copolymers: e.g.,

[0065] Polyethylene block polyethylene oxide, dendrimers, e.g. dendrimers containing hydroxyl groups.

[0066] Suitable flame retardants include, for example, inorganic flame retardants such as Al(OH)₃, Mg(OH)₂, AlO(OH), layered silicates such as montmorillonite or sepiolite, antimony oxides or zinc stannate, nitrogen-containing flame retardants such as melamine cyanurate, melamine polyphosphate, melamine metal phosphates such as melamine aluminum phosphate, melamine zinc phosphate, melamine magnesium phosphate, radical initiators such as alkoxyamines, hydroxylamine esters, azo compounds, dicumyl or polycumyl, hydroxyimides or their derivatives such as hydroxyimide esters or hydroxyimide ethers, phosphorus-containing flame retardants such as red phosphorus, phosphates such as resorcinol diphosphate, bisphenol A diphosphate and their oligomers, triphenyl phosphate, ethylenediamine diphosphate, phosphinates such as salts of hypophosphorous acid and their derivatives. Alkyl phosphinate salts, for exampleDiethylphosphinate aluminum or diethylphosphinate-zinc or aluminum phosphinate, aluminum phosphite, aluminum phosphate, aluminum phosphonate, phosphonate esters, oligomeric and polymeric derivatives of methanephosphonic acid, 9,10-dihydro-9-oxa-10-phosphorylphenanthrene-10-oxide (DOPO) and their substituted compounds, halogen-containing flame retardants based on chlorine and bromine such as polybrominated diphenyl oxides, such as decabromodiphenyl oxide, tris(3-bromo-2,2-bis(bromomethyl)propyl phosphate, tris(tribromoneopentyl)phosphate, tetrabromophthalic acid, 1,2-bis(tribromphenoxy)ethane, hexabromocyclododecane, brominated diphenylethane, tris-(2,3-dibromopropyl)isocyanurate, ethylene bis(tetrabromophthalimide), Tetrabromobisphenol-A-bis(2,3)dibromopropyl ether), Tetrabromobisphenol A, brominated polystyrene, brominated polybutadiene or polystyrene-brominated polybutadiene copolymers, brominated epoxy resin, polypentabrombenzyl acrylate, brominated polyphenylene ethers, if applicable.in combination with Sb 2 O 3 and / or Sb 2 O 5, borates such as zinc borate or calcium borate, possibly on carrier materials such as silica, sulfur-containing compounds such as elemental sulfur, disulfides and polysulfides, thiuram sulfide, dithiocarbamates, mercaptobenzthiazole and sulfenamides, anti-drip agents such as polytetrafluoroethylene, silicon-containing compounds such as polyphenylsiloxanes and / or carbon modifications such as carbon nanotubes (CNTs) or graphene.

[0067] Suitable pigments can be inorganic or organic. Examples of suitable inorganic pigments include titanium dioxide, zinc oxide, zinc sulfide, iron oxide, ultramarine, and carbon black. Examples of suitable organic pigments include anthraquinones, anthanthrones, benzimidazolones, quinacridones, diketopyrrolopyrroles, dioxazines, indanthrones, isoindolinones, azo compounds, perylenes, phthalocyanines, and pyranthrones. Other suitable pigments include metal-based effect pigments and metal oxide-based pearlescent pigments.

[0068] Suitable fillers and reinforcing materials include synthetic or natural materials such as calcium carbonate, silicates, glass fibers, glass beads (solid or hollow), talc, mica, kaolin, barium sulfate, metal oxides and hydroxides, carbon black, graphite, carbon nanotubes, graphene, wood flour, or fibers from natural products such as cellulose or synthetic fibers, as well as metal fibers. Other suitable fillers include hydrotalcites or zeolites or layered silicates such as montmorillonite, bentonite, beidelite, mica, hectorite, saponite, vermiculite, ledikite, magadite, illite, kaolinite, wollastonite, attapulgite, and sepiolite.

[0069] The present invention is explained in more detail with reference to the following examples, without limiting the invention thereto. Example 1-11, Comparative Example 1-3: Production and testing of polyamide 6 compositions with reduced crystallization temperature

[0070] A polyamide 6 (Alphalon 27, Grupa Azoty ATT Polymers GmbH) was blended with the additives listed in Table 1 in the melt. Melt processing was carried out using a co-rotating twin-screw extruder (Thermo Scientific Process 11). The screw speed was 450 min⁻¹, with a throughput of 800 g / h and a melt temperature of 260°C. The hot melt was then cooled in a water bath and subsequently extruded into strands.

[0071] The thermal analysis of the compounds was performed using differential scanning calorimetry (DSC). A DSC 822e (Mettler-Toledo AG) with a constant nitrogen flow rate of 20 ml min⁻¹ and nitrogen cooling was used to investigate the melting and crystallization behavior. The temperature and heat flow rate were calibrated using indium and zinc. The sample quantity was always 5 mg with a deviation of 0.1 mg. An aluminum crucible was used. The samples were heated from 0°C to 270°C at a rate of 10°C min⁻¹ and held there for 3 minutes. The sample was then cooled back to 0°C at a rate of 10°C min⁻¹. The peak crystallization temperature, Tpc, was used to analyze the crystallization rate. The relevant characteristic value, Tpc, is shown in Table 1 for all examples. Table 1: Compositions and crystallization temperatures of compositions according to the invention and comparative examples Example Additive(s) Weight [%] T PC [°C] Comparative example 1 - 0 186,9 Comparative example 2 Calcium phosphate 0,5 187,5 Comparative example 3 Calcium phosphate 3,0 187,2 Example according to the invention 1 phosphate 1,5 181,7 Example 2 according to the invention phosphate 3,0 181,0 Example according to the invention 3 Phosphite A 0,5 184,4 Example according to the invention 4 Phosphite A 1,5 183,6 Example according to the invention 5 Phosphite A 3,0 181,5 Example according to the invention 6 Diphosphite A 1,5 182,8 Example according to the invention 7 Diphosphite B 1,5 181,6 Example according to the invention 8 Diphosphite C 1,5 183,0 Example according to the invention 9 Diphosphonite 0,5 184,7 Example according to the invention 10 Diphosphonite 1,5 182,3 Example according to the invention 11 Diphosphonite 3,0 179,5 Tpc: Peak crystallization temperature; Weight: mass fraction of the additive(s) calcium phosphate: calcium phosphate phosphate: octadecyl phosphate (ADK rod AX-71) phosphite A: 2,4-bis(1,1-dimethylethyl)phenol phosphite (Irgafos 168) diphosphite A: bis(2,4-dicumylphenyl) pentaerythritol diphosphite (Doverphos S9228) Diphosphite B: Pentaerythritol bis(2,4-di-tert-butylphenyl) diphosphite (ADK rod PEP 24) Diphosphite C: Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (ADK rod PEP 36) Diphosphonite: Tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite (Hostanox P-EPQ)

[0072] Surprisingly, the examples according to the invention show a significantly reduced crystallization temperature compared to the comparison examples without additives. Example 12-13, Comparative Example 4: Production and testing of polyamide 6,6 compositions with reduced crystallization temperature

[0073] A polyamide 6.6 (Radipol A45, Radici Chimica SpA) was blended with the additives listed in Table 2 in the melt. Melt processing was carried out analogously to Example 1. The melt temperature was 285°C.

[0074] The thermal analysis of the compounds was carried out analogously to Example 1. The samples were heated from 0°C to 300°C at a rate of 10°C min⁻¹ and held there for 3 minutes. The sample was then cooled back to 0°C at a rate of 10°C min⁻¹. The peak crystallization temperature TPC was used to analyze the crystallization rate. The characteristic value TPC relevant to the invention is shown in Table 2 for all examples. Table 2: Compositions and crystallization temperatures of compositions according to the invention and comparative examples Example Additive(s) Weight [%] T PC [°C] Comparative example 4 - 0 229,4 Inventive example 12 Diphosphonite 0,5 226,7 Example according to the invention 13 Diphosphonite 1,5 223,7 Tpc: Peak crystallization temperature; wt.: Mass fraction of the additive(s) Diphosphonite: Tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite (Hostanox P-EPQ)

[0075] Surprisingly, the examples according to the invention show a significantly reduced crystallization temperature compared to the comparison examples without additives. Example 14, Comparative Example 5-6 : Detection of the branching of a polyamide 6 by a diphosphonite

[0076] To demonstrate branching of polyamide 6 through reaction with a diphosphonite during melt processing, the shear rate-dependent viscosity was examined. A polyamide 6 (Alphalon 27, Grupa Azoty ATT Polymers GmbH) was blended with the additive specified in Table 3 in the melt. Melt processing was carried out analogously to Example 1. Type 1A test specimens according to DIN EN ISO 527-2 were produced from the compounds. The specimens were manufactured in accordance with DIN EN ISO 294-1. A Klöckner Ferromatik Desma injection molding machine, type FX 75-2F, with a clamping force of 750 kN and a cylinder diameter of 30 mm, was used. Before processing, the compounds were dried for 12 hours at 80 °C in a dry air dryer to a residual moisture content of less than 0.05 wt%. The melt temperature was 260 °C.From the wide range of test specimens, discs with a diameter of 20 mm and a thickness of 1.6 mm were milled. The discs were dried at 80°C until a constant mass was achieved to prevent polymer degradation by hydrolysis during the rheological measurements. To determine the shear rate-dependent viscosity, a frequency sweep was performed in the frequency range between 10⁻¹ < -10³ < rads⁻¹ at a temperature of 260°C. The test was carried out using an ARES rheometer from TA Instruments, equipped with a plate-to-plate measuring system. Upon reaching the measurement temperature, the disc-shaped test specimen was compressed to a thickness of 1.0 mm by narrowing the measuring gap, and the excess melt was removed. To prevent oxidative degradation of the polymer, the measurement was performed in a nitrogen atmosphere. Table 3: Compositions and zero viscosities of compositions according to the invention and comparative examples Example Additive(s) Weight [%] η 0 [Pa s] Comparative example 5 - 0 174,0 Comparative example 6 -* 0 446,4 Inventive example 14 Diphosphonite 1,5 519,8 η 0 : Zero viscosity; wt.: Mass fraction of additive PA 6: Alphalon 27, *unprocessed Diphosphonite: Tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite (Hostanox P-EPQ)

[0077] Figure 1The shear rate-dependent viscosity of compositions according to the invention and comparative examples are shown. Polyamides exhibit an increase in shear rate-dependent viscosity with increasing molar mass M across the entire shear rate range [HM Laun, Rheol. Acta 18 (1979), 478-491]. In contrast, branching of polymers primarily affects the zero viscosity, i.e., the viscosity in the low shear rate range [JM Dealy, RG Larson, Structure and rheology of molten polymers, Carl Hanser Verlag, Munich 2006]. The type and length of the branching determine whether the zero viscosity increases or decreases. While the influence on the zero viscosity in a star-shaped branching structure depends on the length of the branches, a highly branched structure leads to a decrease in the zero viscosity. By introducing a backbone segment, such as, for example,The biphenyl unit of tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite generally increases the zero viscosity and enhances the shear rate dependence of the polymer's viscosity. Comparing Example 17 according to the invention with Comparative Examples 1 and 3 in [reference missing]... Figure 1 It becomes apparent that the reaction of polyamide 6 with tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite leads to an "H"-shaped branching structure.

[0078] Additives for (partially) crystalline thermoplastic polymers, particularly in the form of injection-molded parts, films or foils, foams, fibers, cables and tubes, profiles, hollow bodies, tapes, membranes, such as geomembranes, which are produced by extrusion, injection molding, blow molding, calendering, compression molding, spinning, rotomoulding, or coating processes, e.g., for the electrical and electronics industry, the construction industry, the transport industry (automotive, aircraft, ship, rail), for medical applications, for household and electrical appliances, vehicle parts, consumer goods, packaging, furniture, and textiles. Another preferred application of the compositions according to the invention is polymer materials used for additive manufacturing processes, such as laser sintering or 3D printing.

Claims

1. A method for lowering the crystallization temperature of semi-crystalline polyamides, in which a) at least one at least partially or completely end-blocked semi-crystalline polyamide or mixtures of at least two semi-crystalline polyamides is mixed with at least one multifunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds, b) the mixture formed is converted into a melt, wherein a transesterification of the at least one polyfunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds with simultaneous transamidation of the at least one semi-crystalline polyamide occurs, and finally c) the mixture is cooled down.

2. The method according to claim 1, characterized in that the at least one polyfunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures thereof is used in an amount of 0.05 to 10% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.4 to 4% by weight, based on the total amount of the at least one semi-crystalline polyamide, has 3 to 6, preferably 3 to 4 transesterification-capable functionalities, and / or has a molecular weight of at least 600 g / mol.

3. The method according to one of the preceding claims, characterized in that the at least one polyfunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate is selected from the group consisting of the compounds shown below         (O)yP(OR)3,         [(RO)2(O)yP-O]zX         [(RO)2P]zX wherein in each case independently of one another y is 0 or 1, z is 2, 3 or 4, R is the same or different in each occurrence and is selected from the group consisting of linear or branched alkyl radicals, unsubstituted or substituted aromatic radicals, where in each case two radicals (OR) arranged on the same phosphorus atom can also be linked to one another via a covalent bond, and X is a z-valent radical selected from the group consisting of linear or branched, optionally heterosubstituted alkyl radicals, unsubstituted or substituted aromatic radicals, wherein in particular R is 2,4-di-tert-butylphenoxy, 2,6-di-tert-butyl-4-methylphenoxy, 2,4-di-((1-methyl-1-phenyl)ethyl)phenoxy or, in the case where two radicals (OR) located on the same phosphorus atom are also linked to each other via a covalent bond, 3,3',5,5'-tetra-tert-butylbiphenyl-2,2'-dioxy, and X is selected from the group consisting of 4,4'-biphenyl, - (CH2)4C and tri(2-ethyl)aminyl.

4. The method according to one of the preceding claims, characterized in that the phosphites are selected from the group consisting of triphenylphosphite, tri(nonylphenyl)phosphite, trilaurylphosphite, trioctadecylphosphite, (2,4-di-tert-butylphenyl)diethylphosphite, tris-(2,4-di-tert-butylphenyl)phosphite, tristearylsorbitol triphosphite, bis-(2,4-di-tert-butyl-6-methylphenyl)phosphite, bis-(2,6-di-tert-butyl-4-methylphenyl)phosphite, 2,2',2"-nitrilo[triethyltris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3' 5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite, 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(2,4-dicumylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis[4-methyl-2,6-bis(2-methyl-2-propanyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane and mixtures and combinations thereof, the phosphonites are selected from the group consisting of tetrakis-(2,4-di-tert-butylphenyl)-4,4'-biphenyldiphosphonite, tetrakis-(2,4-dimethylphenyl)-4,4'-biphenyldiphosphonite, tetrakis(2,4-bis(1,1-dime-thylpropyl)phenyl)-4,4'-biphenyldiphosphonite, and mixtures thereof, and the phosphates are selected from the group consisting of tris(octadecyl)phosphate, tris(dodecyl)phosphate, and mixtures thereof.

5. The method according to one of the preceding claims, characterized in that at least one transesterification catalyst, preferably tin, antimony and / or titanium compounds, such as tin (II) octoate, is added to the mixture.

6. The method according to one of the preceding claims, characterized in that in step b) both the at least one semi-crystalline polyamide and the at least one polyfunctional transesterifiable organic phosphonite, organic phosphite and / or organic phosphate are melted.

7. The method according to one of the preceding claims, characterized in that step b) is carried out at temperatures of 230 to 350 °C, preferably 240 and 310 °C, particularly preferably 270 to 300 °C and / or is carried out over a period of 0.5 to 60 min, preferably 2 to 10 min.

8. The method according to one of the preceding claims, characterized in that the at least one semi-crystalline polyamide is selected from the group consisting of aliphatic polyamides, in particular PA 6, PA 66, PA610, PA 46, PA 410, PA 612, PA 1212, PA 1010, PA 10 / 12, PA 10, PA 11, PA 12, partially aromatic polyamides derived from aromatic dicarboxylic acids, such as terephthalic acid and / or isophthalic acid and aliphatic diamines, such as hexamethylenediamine, partially aromatic polyamides derived from aliphatic dicarboxylic acids, such as adipic acid and / or sebacic acid and aromatic daimines, such as 1,3- and / or 1,4-diaminobenzene, Polyamide imides derived from tricarboxylic acid anhydrides such as trimellitic acid anhydride and diamines, and mixtures or combinations thereof.

9. The method according to one of the preceding claims, characterized in that the at least one semi-crystalline polyamide has an amino end group concentration of < 30 meq / kg and / or a carboxylic acid end group concentration of < 30 meq / kg.

10. A use of multifunctional transesterifiable organic phosphonites, organic phosphites, organic phosphates or mixtures of at least two of the aforementioned compounds for lowering the crystallization temperature of at least partially or completely end-group-blocked semi-crystalline polyamides, and / or for crosslinking and / or branching of at least partially or completely end-blocked semi-crystalline polyamides.

11. A polyamide molding composition comprising a reaction product obtained by reacting at least one polyfunctional transesterifiable organic phosphonite, organic phosphites, organic phosphates or mixtures of at least two of the aforementioned compounds and at least one at least partially or completely endblocked semi-crystalline polyamide, wherein the reaction involves transesterification of the at least one polyfunctional transesterifiable organic phosphonite, organic phosphite, organic phosphate or mixtures of at least two of the aforementioned compounds with simultaneous transamidation of at least one semi-crystalline polyamide.

12. The polyamide moulding composition according to the preceding claim, characterized in that the reaction product obtained is a branched polyamide.

13. The polyamide molding compound according to one of the two preceding claims, characterized in that it contains additives selected from the group consisting of UV absorbers, light stabilizers, stabilizers, hydroxylamines, benzofurans, metal deactivators, filler deactivators, flame retardants, impact strength improvers, plasticizers, lubricants, rheology modifiers, processing aids, pigments, dyes, fillers, reinforcing agents, optical brighteners, antimicrobial agents, antistatic agents, slip agents, antiblocking agents, coupling agents, dispersing agents, compatibilizers, oxygen scavengers, acid scavengers, marking agents, antifogging agents and mixtures and combinations of at least two of the aforementioned additives.

14. A polyamide molding compound according to any one of claims 11 to 13, characterized in that it is free of nucleating agents.