EP3526281A1

EP3526281A1 - Process for preparing polyamide materials having improved long-term use properties

Info

Publication number: EP3526281A1
Application number: EP17791573.3A
Authority: EP
Inventors: Klaus Bergmann
Original assignee: L Brueggemann GmbH and Co KG
Current assignee: L Brueggemann GmbH and Co KG
Priority date: 2016-10-17
Filing date: 2017-10-16
Publication date: 2019-08-21
Also published as: WO2018072874A1; KR20210076188A; US20190248986A1; JP2019532168A; JP7314201B2; KR20220070061A; CN110177832A; KR20190076997A; JP2021152168A

Abstract

The present invention relates to a method for long-term stability of polyamides and to the use of a specific additive composition for long-term stability of polyamides.

Description

Process for the preparation of polyamide materials with improved

Long-term use properties

description

The present invention relates to a process for the long-term stabilization of polyamides and the use of a specific additive composition for the long-term stabilization of polyamides.

Background of the invention

In the presence of atmospheric oxygen take place at temperatures above 70 ° C or by high-energy radiation at the polyamide surface thermo-oxidative or photo-oxidative reactions. The surface yellows and becomes increasingly dull and cracked. These surface changes lead to embrittlement of the material and thus to the impairment of the mechanical properties of the molded part. By adding suitable stabilizers, the oxidative damage of the polyamide can be delayed, so that the time to embrittlement of the polyamide parts can be delayed.

It is usually between stabilizers for various

Temperature ranges differ. Typical classes of stabilizers for polyamides are copper-based stabilizers and stabilizers based on hindered phenols. Sterically hindered phenols are usually used in combinations with secondary antioxidants, especially phosphites. These blends of sterically hindered phenols with phosphites are hereafter referred to as phenolic

Stabilizers or referred to as phenolic antioxidants. The on copper

based stabilizers typically comprise at least one

Copper compound and at least one other halogen-containing component, which is referred to as a synergist. The combination of copper compounds with halogen-containing synergists is referred to below as a copper stabilizer.

So far, copper stabilizers are almost only used in practice when high continuous service temperatures in the range above 150 ° C required in the application are. In addition to the issues of discoloration and lower creep resistance, which typically occur with the use of classical copper stabilizers (copper salts in combination with halogen salts), the main reason for this is that, based on the previous conviction in the prior art, those based on copper

Heat stabilizers in the temperature range below 150 ° C are inferior to the phenolic antioxidants in terms of stabilization against loss of mechanical properties.

Therefore, for requirements in the temperature range below 150 ° C in

Substantially used phenolic antioxidants. For applications that have a

Stabilization of polyamide materials over a very wide temperature range require, so far in practice copper stabilizers (for the

High-temperature stabilization) combined with phenolic antioxidants. This leads to high stabilization costs, so that thus stabilized polyamide materials are economically less attractive.

This is clear from the most important textbooks for plastic additives that teach the skilled worker and users that copper stabilizers are very effective over 150 ° C, phenolic antioxidants, however, at temperatures below 150 ° C are more effective than copper stabilizers. Examples are:

• "Plastics Additives Handbook" by Hans Zweifel, Ralph D. Maier and Michael

Schiller (6th Edition 2009) p. 80-84.

• "Resistance and Stability of Polymers" by Gottfried Ehrenstein and Sonja Pongratz, Carl Hanser Verlag 01.10.2013, chapter 3.7.8, page 308 - 313.

• "Iodine Chemistry and Application", Tatsuo Kaiki, (1 ^st Edition), Chapter 31, p. 551 f.

• Lecture by J.R. Pauquet and A.G. Oertli (Ciba) held at the World Congress

POLYAMIDE 2000, Zurich, Switzerland, 14.-16.03.2000.

The online platform "Specialchem" also reveals this conviction:

http://polvmeradditives.specialchem.com/selection-guide/light-stabilizers-and- antioxidants-for-polvamides / heatstabilizers-for-aliphatic-polvamides /

The published patent application "With copper salt and aliphatic halogenated

Phosphate stabilized polyamide composition "DE 198476216 discloses

Polyamide compositions, which are characterized in that as stabilizer at least one copper salt and at least one halogen-containing aliphatic phosphate are included, thereby increasing the continuous service temperature in the

Temperature range of over 150 ° C, improved creep resistance and a lower discoloration splash-fresh and can be achieved after conditioning.

DE 198 47 626 A1 discloses one with copper salt and aromatic

Halogen compound stabilized polyamide composition. This doctrine focuses on the stabilization of the polyamide while increasing the

Continuous use temperature. Heat aging tests are given at temperatures of 150 ° C and 165 ° C. The data of the tests at 150 ° C do not differ within the scope of the measurement accuracy from the comparative data with the conventional stabilizers tested there with salt-like halogen compounds. A significant improvement in the stabilizing effect is only at higher

Temperatures, in accordance with the objective of this teaching, stabilize at elevated continuous service temperatures (165 ° C or higher).

The patent EP 1 121 388 B1 discloses "polyamide compositions stabilized with copper complexes and organic halogen compounds"

Polyamide compositions in which at least one complex of the copper with at least one organic halogen compound for stabilization are included, whereby improved thermal stability at temperatures above 150 ° C, improved tracking resistance and low discoloration is achieved splash-fresh and after conditioning.

Object of the invention

Due to the ever increasing area of use plastic based

Materials, for example in the automotive sector, better stabilization components, especially for continuous use temperatures in the range of below 150 ° C are sought, especially for polyamides. Typical continuous service temperatures are, for example, temperatures with a temperature maximum value of about 120 ° C., which are frequently required, for example, in the electrical or automotive sector. In this temperature range phenol / phosphite blends are typically used as stabilizers, but do not allow a stabilization beyond a maximum time range, even with an increase in the amount used. Therefore, the present invention has the object to provide a way with which the desired stabilization at rather low to medium

Long-term use temperatures can be achieved, ie in particular

To enable polyamide compositions that improved

Long-term stabilization against heat over a wide range (even at high temperatures)

Temperatures above 150 ° C and up to 180 ° C), and at the same time be particularly efficient stabilized at temperatures below 150 ° C with respect to a clear

Extension of the possible service life, preferably both: a) maintaining the tensile strength and the impact strength (preventing the

Embrittlement);

b) concerning very good retention of the elongation at break with at the same time good preservation of the elongation at break

Tensile strength and impact resistance.

Brief description of the invention

This object is solved by the subject matter of claims 1 and 2.

Preferred embodiments are specified in the subclaims, as well as in the following description.

Brief description of the figure

Figure 1 shows the half-lives of the elongation at break for various examples and comparative examples under heat storage at 120 ° C.

Detailed description of the invention

The present invention surprisingly allows the desired stabilization of polyamides by the use of already known components, but which were previously known in the art only for high temperature stabilization. Nevertheless, significantly improved stabilization can be achieved

Continuous use temperatures of 150 ° C or less, such as 120 ° C can be achieved, especially in comparison with the compounds previously used for the stabilization of polyamides at lower continuous service temperatures. There are the stabilizers to be used according to the invention are readily dispersible in polyamides, so that easy handling is provided. The stabilizers according to the invention can be incorporated and distributed in polyamides by conventional methods, moreover, the stabilizer components can be easily used

compounded, for example, by compounding with a matrix of conventional materials, such as waxes or polymers. The present invention thus makes possible the realization of the following advantages:

1. Improvement of the stabilization of unreinforced and reinforced polyamides

against long-term stress at temperatures below 150 ° C. As long as possible a delay of degradation and associated reduction of the performance characteristics, in particular as long as possible preserving the mechanical characteristics of tensile strength and impact resistance.

2. The elongation at break is generally particularly fast and at heat aging

clearly off. A particularly important advantage for the practical use of polyamide materials is therefore the possibility according to the invention of significantly longer retention of the elongation at break during long-term storage under temperature load (at temperatures below 150 ° C.) in comparison to phenolic antioxidants. A high elongation at break of the polymeric matrix leads (also in reinforced polyamides) to a significant improvement in the application properties of the entire material and to increase the energy absorption capacity.

3. The amount of stabilizer used can be adjusted to the desired stabilization time

(Life of the product) are adapted, since the invention

to be used stabilizers when increasing the amount used to allow an extension of the stabilizing properties, an effect that is not so pronounced especially in phenolic stabilizers. These stabilizers show rather no longer extending the stabilizing effect, even with a significant increase in the amount used. On the contrary, it can be at high

Doses (for example, in the range above 1%) even come to a deterioration of the stabilizing effect. In FIG. 1, the half-life is

Elongation at break (determined at 120 ° C) of polyamide 6.6 shown using different stabilizers. Sample R01 is non-stabilized polyamide, and samples R02 and R09 are phenolic-stabilized polyamides (in all samples the identical polyamide 6.6 was used), where in sample R09 the

Use amount of the phenolic antioxidant has been doubled compared to R02. However, this has hardly any effect on the elongation at break. Sample R07 is a sample stabilized according to the invention (amount of stabilizer is equivalent to the amount in sample RO2). Here is the dramatic and surprising increase in the half-life to be achieved (ie the time that elapses until the original value of the elongation at break has fallen to half) compared to the phenolic stabilizers. For sample R014, in turn, the amount used was doubled (compared to R07) - here is a very clear further

Extension of the half-life. This effect is analogous to the

according to the invention stabilized samples R06 and R13 (double the amount of additive compared to R06) clearly visible. This enormous stabilization efficiency of the method according to the invention can also be used to small

Use stabilizer amounts to ensure the level of continuous service life that can be achieved with phenolic stabilizers. This results in cost advantages, advantages regarding freedom from labeling as well as the possibility of coping with low halogen contents, so that use is facilitated even in difficult electrical and electronic applications.

As a result of the improved stabilization, components may possibly be thinner, since a material thickness hitherto regarded as necessary can be reduced (owing to a desired redundancy or a corresponding safety coefficient) (since the polyamides stabilized according to the invention have a lower content)

Material thicknesses are longer loadable). In addition, according to the invention, the following advantages can also be realized:

• Long delay in degradation and associated reduction in performance characteristics, especially long-term preservation of mechanical properties

Characteristics Tensile strength, elongation at break and impact resistance;

Efficient stabilization of polyamides (and prevention of embrittlement) over a very wide temperature range, even at temperature peaks of up to about 200 ° C (eg materials that are rather low) Need to withstand continuous service life, being in the life cycle

Temperature peaks may occur), without having to expect a deterioration in material quality (since the effectiveness of the

known combination of copper component and synergist used at high temperatures is known). Phenolic stabilizers alone are not suitable for such applications because they can not prevent rapid degradation of essential material properties at high temperatures (> 150 ° C.). In such application requirements with different temperature loads, the use of different stabilizer systems for the different temperature ranges is no longer necessary due to the stabilization methods of the invention (eg, a combination of both phenolic stabilizers and copper-based stabilizers);

• color neutrality or only slight discolouration after conditioning;

• No or at least only an acceptable influence on tracking resistance, which is very important for use in the electrical and electronics industry.

Surprisingly, therefore, an improved stabilization can be achieved in that methods are used in which polyamides with

Copper compounds are stabilized, which suitably with a

synergistically acting halogen-containing aliphatic phosphate are combined. Polyamide compositions provided with this stabilizer combination have better stabilization at temperatures below 150 ° C., preferably at

Temperatures of 145 ° C or less, such as 140 ° C or less, 130 ° C or less, such as at 125 ° C or less, in particular 120 ° C or less, compared to conventional copper-based and / or organic stabilizers ( phenolic antioxidant combinations alone and with phosphites). In particular, the tensile strength and impact resistance of these polyamide compositions at temperatures below 150 ° C are significantly longer obtained at a high level.

In addition, it was surprisingly found in the combination of complexes of copper with halogenated aliphatic phosphate that specifically the

Elongation at break after heat aging is kept much longer at a high level can be compared with the previously known stabilizer systems for polyamides, also compared to combinations of copper salts or others

Copper compounds (which are not copper complexes) with halogenated phosphate or with other halogen compounds, including halogen salts. This effect occurs especially at temperatures below 150 ° C. At higher temperatures, e.g. at 180 ° C there are no differences in terms of retention of elongation at break compared to stabilization with conventional copper stabilizers.

Overall, therefore, with the stabilizer combinations to be used according to the invention, long-term stabilization over an extremely broad temperature range can be achieved with a single stabilizing component (the combination to be used according to the invention). The following statements and examples show that, in addition to the discussed, surprising stabilization at temperatures below 150 ° C with the combination used according to the invention, in addition also a stabilization at a temperature range of well above 150 ° C, such as above 180 ° C to about 200 ° C is certainly possible. In the prior art combinations of different stabilizers are considered necessary for such stabilizations over such a broad temperature range. Thus, for stabilization at low temperatures, the use of those described is typically used

phenolic compounds considered essential, but at temperatures above 150 ° C de facto show no effect. Therefore, in the prior art, if stabilization is desired, for example, for the temperature range of 120 ° C to 180 ° C, a combination of the phenolic antioxidants with other, for example, copper-based stabilizers for the temperature range above 150 ° C must be used. Such combinations are in

No longer necessary in accordance with the findings of the present invention, since the particular stabilizer combinations of the present invention can safely cover the entire temperature range.

Thus, in addition to the disclosed method and use for long-term stabilization at temperatures less than 150 ° C, the present invention provides a system that safely transfers polyamides over a broad range of temperatures

Temperature range can stabilize, said temperature range includes temperatures below 150 ° C and also temperatures of 150 ° C or more. The temperature range of 150 ° C or higher extends in particular over Temperatures of 160 ° C or higher, including 180 ° C or higher, and usually up to 200 ° C. Thus, the present invention enables the combinations of several different stabilization systems considered necessary in the prior art to be replaced by a single system as described herein. Stabilized polyamide compositions of this aspect of the present invention therefore preferably comprise as stabilizer exclusively the temperature stabilization system described here. This simplifies both the compounding and cost savings, as can be dispensed in particular to the phenolic systems. For this, as evidenced in particular by the following experimental data, an overall improved system is provided, so that it is also possible to realize significant extensions of the stabilization periods.

If a stabilization in an upwardly even wider temperature window desired, ie in particular at temperatures above 200 ° C, known high temperature stabilizers for polyamides can be used. In particular, polyols having 2 or more hydroxyl groups can be used for this purpose. Known examples of such compounds are polyols having 2 to 12 hydroxyl groups and a molecular weight of 64 to 2000 g / mol. Particularly suitable examples thereof are pentaerythritol, dipentaerythritol and tripentaerythritol, especially dipentaerythritol. Such compounds can be incorporated into the polyamide in a conventional manner. Particularly suitable is incorporation via a premix, particularly preferably via a masterbatch, wherein the premix or the masterbatch also contains the other stabilizing components in accordance with the present invention. The amounts of such further high temperature stabilizers can be selected by the skilled person based on already known information or determined by simple experiments for a desired polyamide composition.

With the inventively stabilized polyamide compositions based on copper complexes and halogenated aliphatic phosphates also a very good color and high tracking resistance are also achieved simultaneously. This also allows for use in areas requiring high tracking resistance in the form of a CTI value (comparative tracking index) of 600 V (for unreinforced polyamides). Surprisingly, in the context of the present invention, that by combining a copper component with a specific synergist as defined in claims 1 and 2, an unexpected improvement in the stabilization of polyamides can be achieved, which are both the classical phenolic

Stabilizers surpasses, as well as with other combinations of known

Copper stabilizers and halogen-containing synergist can not be achieved. This is particularly evident in the following examples, where conventional copper-based systems (copper salt and halogen salt or copper complex and halogen-containing organic compound (no aliphatic phosphate)) do not allow the effects to be achieved with the combination according to the invention.

The inventively used copper stabilizers consist of two essential components, namely a mixture of copper compounds and special halogen-containing compounds (also referred to as synergists). The copper compound used in the invention may be any copper salt (CuI, CuBr, copper acetate, CuCN, copper stearate, etc.) or any other

Copper compound such as CuO, Cu ₂ 0, copper carbonate or any complex of copper be. The synergist to be used according to the invention is a halogen-containing aliphatic phosphate.

These two components are typically used in amounts such that a ratio of Cu: halogen of 1: 1 to 1:50 (molar ratio) results, preferably 1: 4 to 1:20, more preferably 1: 6 to 1: 15.

The amounts of copper and halogen in the polyamide are selected depending on the desired use of the polyamide and the desired stabilization. The amount of copper used therein is not limited so long as the mechanical properties of the polyamide are not adversely affected. The amounts of copper used are usually in the range of 1 to 1000 ppm Cu, preferably 3 to 200 ppm Cu, more preferably 5 to 150 ppm Cu. Concrete examples are 33 ppm, 66 ppm and 100 ppm. The amounts of synergist (in each case based on ppm of halogen) thus result from the ratios disclosed above. The addition amount for the synergist is not particularly limited. However, additions above 1% generally do not lead to any improvement in the

Stabilizer effect. The amounts used are typically in the range 10 to 10,000 ppm. Preferred amounts are in the range of 30 to 2000 ppm, more preferably 50 to 1500 ppm.

According to the invention, all conventional polyamides can be stabilized. Polyamides are polymers with recurring carboxamide groups -CO-NH- in the main chain. They are training

(a) aminocarboxylic acids or their functional derivatives, e.g. lactams; or off

(b) diamines and dicarboxylic acids or their functional derivatives.

By variations of the monomer units polyamides are available in great variety. The most important representatives are polyamide 6 from ε-caprolactam, polyamide 6.6 from hexamethylenediamine and adipic acid, polyamide 6.10 and 6.12, polyamide 11, polyamide 12, PACM-12 and polyamide 6-3-T, PA4.6 and semiaromatic polyamides (polyphthalamide PPA). ,

However, according to the invention all other polyamides can also be stabilized, for example copolyamides or copolymers of polyamides with other segments, for example with polyesters. It is also possible to stabilize blends of various polyamides and blends of polyamides with other polymers. Particularly preferred are polyamide 6 and polyamide 6.6.

The stabilizer mixtures according to the invention can be used in all the aforementioned polyamides and blends, both in unfilled or unreinforced, as well as in filled or reinforced polyamides. As fillers / reinforcing materials, for example, glass fibers, carbon fibers, glass beads, diatomaceous earth, fine-grained minerals, talc, kaolin, phyllosilicates, CaF ₂ , CaC0 ₃ and aluminum oxides can be used.

Copper complexes to be used according to the invention are complexes of copper with ligands such as triphenylphosphines, mercaptobenzimidazoles, glycine, oxalates and Also suitable are chelating ligands, such as ethylenediaminetetraacetates, acetylacetonates, ethylenediamines, diethylenetriamines, triethylenetetraamines

Phopsin chelate ligands or bipyridines. Examples of the preferred ones

Phosphine chelate ligands are 1,2-bis (dimethylphosphino) ethane, bis (2-diphenylphosphinoethyl) phenylphosphine, 1,6-bis (diphenylphosphino) hexane, 1,5-bis (diphenylphosphino) pentane, Bis (diphenylphosphino) methane, 1, 2-bis (diphenylphosphino) ethane, 1, 3-bis (diphenylphosphino) propane, 1, 4-bis (diphenylphosphino) butane and 2,2'-bis (diphenylphosphino) -1, 1'-binaphthyl.

These ligands can be used individually or in combination for complex formation. The syntheses necessary for this are known to the person skilled in the art or described in the specialist literature on complex chemistry. As usual, these complexes may contain, in addition to the above-mentioned ligands, typical inorganic ligands such as water, chloride, cyano ligands, etc.

Preference is given to copper complexes with the complex ligands triphenylphosphines, mercaptobenzimidazoles, acetylacetonates and oxalates. Particular preference is given to triphenylphosphines and mercaptobenzimidazoles.

Preferred complexes used in the invention of the copper are usually by reaction of copper (l) ions with the phosphine or

Mercaptobenzimidazole compounds formed. For example, these complexes can be prepared by reacting triphenylphosphine with a compound suspended in chloroform

Copper (I) halide (G. Kosta, E. Reisenhofer and L. Stafani, J. Inorg. Nukl. Chem. 27 (1965) 2581). However, it is also possible to reductively react copper (II) compounds with triphenylphosphine so as to obtain the copper (I) addition compounds (FU Jardine, L. Rule, AG Vohrei, J. Chem. Soc. (A) 238-241 ( 1970)).

However, the complexes used in the invention can also be prepared by any further suitable method. Suitable copper compounds for preparing these complexes are the copper (I) or copper (II) salts of

Hydrohalic acids, hydrocyanic acid or the copper salts of aliphatic carboxylic acids. Examples of suitable copper salts are copper (I) chloride, copper (I) bromide, copper (I) iodide, copper (I) cyanide, copper (II) chloride, copper (II) acetate or copper (II) stearate. Particularly preferred are copper (I) iodide and copper (I) cyanide.

In principle, all alkyl or arylphosphines are suitable. Examples

According to the invention usable phosphines are triphenylphosphine (TPP), substituted triphenylphosphines, trialkylphosphines and Diarylphosphine. An example of a suitable trialkyl phosphine is tris (n-butyl) phosphine. Generally, the

Triphenylphosphine complexes more stable than the trialkylphosphine complexes.

Triphenylphosphine is also preferred because of its commercial availability in economic terms.

Examples of suitable complexes can be represented by the following formulas:

[Cu (PPh ₃ ) ₃ X], [Cu ₂ X ₂ (PPh 3) 3], [Cu (PPh ₃ ) X] ₄ and [Cu (PPh ₃ ) ₂ X], where X is selected from Cl, Br, I, CN, SCN or 2-MBI.

However, complexes which can be used according to the invention can also additionally contain further complex ligands. Examples are bipyridyl (eg CuX (PPh ₃ ) (bipy), where X is Cl, Br or I), biquinoline (eg CuX (PPh ₃ ) (biquin), where X is Cl, Br or I) and 1, 10 Phenanthroline, o-phenylenebis (dimethylarsine), 1,2-bis (diphenylphosphino) ethane and terpyridyl.

These complexes are generally electrically non-conductive and diamagnetic. They are usually colorless and occur as water-insoluble crystals that melt undecomposed. In polar organic solvents such as DMF, chloroform and hot ethanol, the complexes are readily soluble.

The copper salt to be used according to the invention can be any desired copper salt.

Preference is given to salts of monovalent or divalent copper with inorganic or organic acids.

Examples of suitable copper salts are copper (I) salts such as Cul, CuBr, CuCl or CuCN, copper (II) salts, such as CuCl _2, CuBr _2, Cul _2, copper acetate, copper sulfate, Copper stearate, copper propionate, copper butyrate, copper lactate, copper benzoate or copper nitrate, as well as the ammonium complexes of the abovementioned salts.

Furthermore, compounds such as copper acetylacetonate or copper EDTA can be used. It is also possible to use mixtures of different copper salts. Optionally, in addition, copper powder can be used.

The copper (I) halides and the copper salts of organic acids are preferred. Particularly preferred are copper (I) iodide and copper acetate.

The aforementioned copper components may be used singly or in mixtures of two or more components.

The synergist to be used according to the invention is a halogen-containing aliphatic phosphate.

Thus, according to the invention, at least one halogen-containing aliphatic phosphate, preferably in the form of a tris (halohydrocarbyl) phosphate or a phosphonate ester, is used. Preference is given to tris (bromohydrocarbyl) phosphates (brominated aliphatic phosphates). In particular, in these compounds, no hydrogen atoms are attached to an alkyl carbon atom which is in the alpha position to a carbon atom attached to a halogen. This can not be

Dehydrohalogenation reactions occur. Exemplary compounds are tris (3-bromo-2,2-bis (bromomethyl) propyl) phosphate, tris (dibromoneopentyl) phosphate,

Tris (trichloroneopentyl) phosphates, tris (chlorodibromoneopentyl) phosphates and

Tris (bromodichloroneopentyl) phosphates. Preference is given to tris (dibromoneopentyl) phosphate and tris (tribromoneopentyl) phosphate.

It is also possible to use mixtures of several halogen-containing aliphatic phosphates. Furthermore, mixtures of halogen-containing aliphatic phosphates with aromatic halogenated compounds, e.g.

brominated polystyrenes or poly (pentabromobenzyl) acrylates can be used. As aromatic halogenated compounds can continue

Tris (haloaromatic) phosphates or phosphonate esters are used, for example Tris (2,4- dibromophenyl) phosphate, tris (2,4-dichlorophenyl) phosphate and tris (2,4,6-tribromophenyl) phosphate. However, the use of only the halogenated aliphatic phosphates as synergist is preferred.

Preferred combinations (referred to below as stabilizer blends) are combinations of copper salt, in particular Cul, and those described herein

Phosphates, in particular bromine-containing phosphates, and combinations of

Copper complexes, in particular complexes with TPP ligands and the here

described phosphates, in particular bromine-containing phosphates.

Polyamide and stabilizer blend are either melted together and mixed, or it is first melted the polyamide and then blended the stabilizer blend, the latter variant is preferred. In a

In a preferred embodiment, the stabilizer blend is added in the form of a premix (concentrate or masterbatch) to the molten polyamide.

Suitable mixing devices are familiar to the person skilled in the art and comprise

Mixing mills, discontinuous internal mixers and kneaders, continuous extruders and kneaders, and static mixers. Preference is given to the use of continuously operating extruders, both single-screw and

Twin screw extruders that allow good mixing. In this case, the polyamide is usually first melted in the extruder and the stabilizer blend is then metered through suitable openings (gravimetrically or volumetrically). These methods and the devices required for this purpose are known to the person skilled in the art.

But it is also possible, the stabilizing components already in the preparation of the polyamide, i. the monomer mixture, add. As a result, a very good mixing without additional mixing process is possible, which reduces production costs and times.

If a preconcentrate of the stabilizer blend is used, then this preconcentrate can be prepared in batch mixers which allow a very good, homogeneous distribution, for example in a Buss kneader. Usually however, continuous mixers are used as preferred

Twin-screw extruder or ZSK extruder. As matrix material is thereby

Usually uses the same polyamide, which is then mixed with the preconcentrate. But it is also possible, another polyamide or another

To choose polymer. Optionally, further additives may be added during masterbatch production.

Alternatively, in a further preferred embodiment, a preconcentrate can be prepared by mixing the stabilizer blend together with further additives and / or additives, for example lubricants, mold release agents, nucleating agents, etc., and subsequently agglomerated or pelletized, compacted or tabletted. The corresponding methods and the devices necessary for this are known to the person skilled in the art.

The additives and / or additives mentioned may also be used separately in the

inventive methods are used, for example by a separate metering in the preparation of stabilized polyamides according to the invention.

Another positive effect of the present invention relates to the aspects of occupational safety, environmental protection and applicability in electrical and

Electronic applications (despite content of halogen-containing compounds). Classic copper stabilizers and halogen-containing materials are subject to special

Provisions relating to marking, transport, storage and storage

Handling according to CLP Regulation No. 1272/2008.

A critical issue in the use of halogen-containing materials is the topic of corrosion, especially electrical corrosion. In this context, halogens, in particular bromine and chlorine, but also iodine, are considered detrimental to electrical components due to interactions of the halide anions with intermetallic phases. Therefore, a demand for reducing the halogen content in the electrical and electronic industry is now widespread. Following international standards IEC 61249-2-21 and EN 61249-2-21 and IPC 4101 for PCBs (printed circuit boards), materials containing less than 1500 ppm of Cl and Br are considered, with a maximum of Br and Cl of 900 ppm each as halogen-free. The stabilizer combination to be used according to the invention can be used because of the extreme Good efficacy can be used in low doses, so that appropriate limits can be met. It is also possible to keep the concentrations of copper and halogens low even during the preparation of the stabilizer combinations, for example by preparing the preconcentrates described above. In this way, low-concentration additives (based on the

Stabilizer combination of the invention) accessible, with the advantages already described above. Overall, the handling of the stabilizer components to be used according to the invention is thereby simplified for the user since no labeling according to GHS / CLP Regulation (EC) No. 1272/2008 is required. This leads to reduced costs, inter alia, during storage and transport.

Such materials also have fewer risks in terms of environmental hazard and occupational safety.

The following examples illustrate the invention.

Examples:

In all examples, polyamide was compounded with said stabilizers in a conventional manner and evaluated the mechanical and other properties to be tested on test specimens. The aging conditions are indicated in each case.

A polyamide 6.6 from BASF was used (Ultramid A27 E).

Compounding was carried out with a twin-screw extruder from Leistritz ZSE27MAXX-48D.

The additives were added gravimetrically during compounding.

After drying, standard test bars for determining the mechanical characteristics (ISO 527) and the impact strength (ISO 179/1 eil) were produced from the compound on an injection molding machine "Demag Ergotech 60 / 370-120 concept".

In heat circulation ovens, the test bars were stored at the temperatures mentioned in the examples (120 ° C, 140 ° C, 150 ° C and 180 ° C). The measurement of modulus of elasticity [MPa], tensile strength [MPa] (elongation [%]) and fracture stress [MPa] (elongation [%]) was carried out in the tensile test according to ISO 527 using a static material testing machine Zwick Ζ0 0.

The impact resistance was measured according to ISO 179/1 in the Charpy impact test using a HIT PSW 5.5J pendulum impact tester.

Used chemical compounds and abbreviations:

TPP: triphenylphosphine; P (C6H5) 3

PDBS: polydibromostyrene; [CH2-CH (C6H3Br2) -] n

Phosphate 1: tris (tribromoneopentyl) phosphate; Ci ₅ Br ₉ H240 ₄ P

Phenol / Phosphite Blend B1 171: 1.1 Mixture of tris (2,4-di-tert-butylphenyl) phosphite and N, N'-hexane-1,6-diylbis (3- (3,5-di-tert. butyl-4-hydroxyphenylpropionamid))

Table 1: Stabilization of polyamide 6.6 natural; Heat aging at 120 ° C

Comparative Experiments with Phenolic Antioxidants and Other Copper Stabilizers (Inventive Combinations and Comparative Variants); Measurement of tensile strength,

Elongation at break and impact strength on the corresponding test specimens.

In the copper stabilizers, the Cu concentration was 33ppm and the

Halogen concentration 400ppm.

The time was determined until the impact strength fell to the absolute value of 10 kJ / m2. Furthermore, the time was determined until the tensile strength on the 90% value of

Initial strength drops and until the elongation at break reaches half of the initial value (half-value measurement).

(92% after 5,000h)

Table 2: Stabilization of polyamide 6.6 natural; Heat aging at 120 ° C

Comparative Experiments with Phenolic Antioxidants and Copper Stabilizers (Inventive Combinations and Comparative Variants);

Measurement of tensile strength and elongation at break on the corresponding test specimens. In the copper stabilizers, the Cu concentration was 66ppm and the

Halogen concentration 800 ppm.

The time was determined until the tensile strength reached the 70% value of

Initial strength drops and the time until the elongation at break half of the

Output value reached (half-value measurement). Series Type Composition Time to reach half-life of

70% of the elongation at break

initial tensile

R08 Without stabilizer 500 h 400 h

R09 Comparison 1% B1171 (phenol / phosphite 2,100h 1,100h

blend)

RIO Comparison Cul / Kl 6,200 h 3,300 h

RH Comparison Cul (TPP) 3 / PDBS 5,900 h 1,000 h

Rl ₂ Comparison Cul (TPP) / PDBS 5,800 h 1,300 h

R13 Invention Cul (TPP) / phosphate 1 9,200 h 4,700 h

R14 Invention Cul (TPP) 2 / Phosphate 1 9,800 h 4,600 h

Table 3: Stabilization of polyamide 6.6 natural; Heat aging at 180 ° C

Comparative experiments with copper stabilizers (inventive combinations and

Comparison variant);

Measurement of tensile strength, elongation at break and impact resistance on the corresponding test specimens.

In the copper stabilizers, the Cu concentration was 100ppm and the

Halogen concentration 1200ppm.

The times were determined until the impact strength, tensile strength and elongation at break reached half of the respective initial value (half-value measurements).

Table 4: Color and creep resistance of polyamide 6.6

Comparative experiments with phenolic antioxidants and other copper stabilizers

(inventive combinations and comparison variants);

For copper stabilizers add 100ppm Cu / 1000ppm halogen.

From the granules described above, test pieces of 3 × 5 cm and 3 mm thickness were produced on the injection molding machine and the CTI values were measured according to the IEC-60112 standard. The discoloration of the test slides was assessed visually.

* applies to typical formulations of stabilizer blends that are adjusted so that the addition level is in the range of 0.5 to 3% stabilizer (based on the polyamide content).

Tables 1 to 4 summarize different experiments and comparative experiments together. These impressively demonstrate that with the present invention

associated benefits. Thus, it can be seen in Table 1 that the stabilizer components used according to the invention can keep the mechanical property profile of the stabilized polyamide for a considerably longer period of time in a very good range, compared with the standard phenolic stabilizers, but also compared with known ones on copper based systems. Although the stabilizer systems copper iodide / potassium iodide and copper complex and aromatic halogen compounds show stabilizers comparable to the phenolic stabilizers, the high level of the polyamides stabilized according to the invention can not be achieved.

Table 2 summarizes corresponding experiments, but with increased amounts of stabilizer. This shows that increasing the amount of

phenolic stabilizer leads to only minor improvements over lower levels. Here, a plateau is reached, so that even further increases in the amount used lead to no further improvements. In contrast, the stabilizer combinations according to the invention show a significant prolongation of the stabilizing effect.

Table 3 shows heat aging tests at high temperatures

summarized. This shows that both combinations of the invention and conventional copper-based systems (here copper iodide / potassium iodide) show approximately the same stabilizing effects, which again can be taken as evidence that the improved stabilizing effect at low temperatures for the combinations according to the invention as surprising is to be regarded as at the typical for these stabilizers higher temperatures no significant difference in the

Stabilization effect can be seen.

In Table 4 experiments and comparative experiments are given, which lists the suitability of the respective stabilizers for the stabilization of polyamides, which are in the range

Electrics / electronics should be used. In particular, the CTI value is relevant here, since in many areas stabilized polyamides are only used when the CTI value is 600 V, or at least not very far below 600 V. It is shown here that the stabilizer combinations according to the invention fulfill this requirement, in particular stabilizer combinations according to the invention which contain no salt-based components. In contrast, classic, salt-based copper stabilizers are not suitable for these applications.

These experiments and comparative experiments thus show again that the

Stabilized polyamides according to the invention have excellent property profiles. With the stabilizer components to be used according to the invention can be targeted

Properties are controlled over a wide range of a matrix of properties. On the one hand, it is possible to adjust the mechanical stability of the polyamide to be stabilized over a wide range, which is even higher than that with conventional low-to-medium phenolic stabilizers, even at low use levels Temperature range is reached. At the same time, it is also possible to obtain stabilized polyamides which have high creep resistance (high CTI values) and show no or only a slight tendency to discoloration after conditioning. This again confirms the excellent property profile of the invention used

Stabilizer combination.

In order to demonstrate the surprising effectiveness of the stabilizers to be used according to the invention, in particular in comparison with the known phenolic stabilizers, the half-lives of the elongation at break for compositions with PA 6.6 were evaluated for different combinations.

Table 5: Half-life [h] of the elongation at break of polyamide 6.6 as a function of the stabilization.

Comparative experiments with phenolic antioxidants and copper stabilizers

(inventive combinations);

Measurement of the elongation at break on the corresponding test specimens.

The time was determined until the elongation at break reached half of the initial value (half-value measurement).

The data in the above table show that especially at 120 ° C. and 140 ° C. in polyamide 6.6 a better (longer) maintenance of the elongation at break is achieved with the inventive variants compared to a classic phenol / phosphite-based system (B1171). At the same time, it becomes clear that the use according to the invention also offers protection against temperature peaks of above 150 ° C., temperature ranges, in which stabilizers based on phenol / phosphite have only a very small effect. This is especially true for temperatures in the range of 170 ° C and higher, in which an effectiveness of these stabilizers is no longer present. Due to the high effectiveness of the stabilizers according to the invention can also be used with low copper and

Halogen concentrations in the polyamide very good long-term performance characteristics of the respective materials over a wide temperature range can be achieved. Due to the low required use concentrations, light colors, good electrical properties, low costs for stabilization and a significantly reduced tendency for electrocorrosion can be achieved.

Claims

claims

1. A process for the stabilization of polyamides at temperatures of less than 150 ° C, characterized in that a polyamide is mixed with a copper compound and a halogen-containing aliphatic phosphate.

2. Use of a composition comprising a copper compound and a halogen-containing aliphatic phosphate for stabilizing polyamides at temperatures of less than 150 ° C.

3. The method of claim 1 or use according to claim 2, characterized in that the stabilization of polyamides at temperatures of 145 ° C or less, in particular at temperatures of 130 ° C or less.

4. The method of claim 1 or 3 or use according to claim 2 or 3, characterized in that the copper compound is a copper (l) salt, a copper (II) salt or a copper complex.

5. A method or use according to claim 4, characterized in that the copper (l) salt is selected from Cul, CuBr, CuCl, CuCN, Cu ₂ 0 or mixtures thereof.

6. A method or use according to claim 4, characterized in that the copper (II) salt is selected from copper acetate, copper stearate, copper sulfate, copper propionate, copper butyrate, copper lactate, copper benzoate, copper nitrate, CuO, CuCl ₂ or mixtures thereof.

7. A method or use according to claim 4, characterized in that the copper complex is selected from copper acetylacetonate, copper oxalate, copper-EDTA, [Cu (PPh ₃ ) ₃ X], [Cu ₂ X ₂ (PPH ₃ ) 3], [Cu (PPh ₃ ) X], [Cu (PPh ₃ ) ₂ X], [CuX (PPh ₃ ) (bipy)], [CuX (PPh ₃ ) (biquin)] where X = Cl, Br, I, CN, SCN or 2-mercaptobenzimidazole.

8. A method or use according to any one of claims 1 to 7, characterized in that the halogen-containing aliphatic phosphate is a tris (halohydrocarbyl) phosphate or a phosphonate ester.

9. A method or use according to claim 8, characterized in that the tris (halohydrocarbyl) phosphate is selected from tris (3-bromo-2,2- bis (bromomethyl) propyl) phosphate, tris (dibromoneopentyl) phosphate tris (trichloroneopentyl) phosphate, tris (bromodichlorneopentyl) phosphate,

Tris (chlorodromoneopentyl) phosphate, tris (tribromoneopentyl) phosphate or mixtures thereof.

10. A method or use according to any one of claims 1 to 9, further comprising at least one halogenated aromatic compound and / or at least one polyol having 2 or more hydroxyl groups, preferably a polyol having 2 to 12 hydroxyl groups and a molecular weight of 64 to 2000 g / mol , more preferably pentaerythritol, dipentaerythritol and tripentaerythritol, especially dipentaerythritol.

11. A method or use according to claim 10, characterized in that the halogenated aromatic compound is selected from brominated polystyrenes, poly (pentabromobenzyl) acrylates, tris (2,4-dibromophenyl) phosphate, tris (2,4-dichlorophenyl) phosphate, Tris (2,4,6-tribromophenyl) phosphate or mixtures thereof.

12. A method or use according to any one of claims 1 to 11, characterized in that the polyamide is selected from reinforced or unreinforced PA 6, PA 6.6, PA 4.6, PA 11, PA 12 or mixtures thereof.

13. A method for stabilizing polyamides over a temperature range of less than 150 ° C and more than 150 ° C, characterized in that a polyamide is mixed with a copper compound and a halogen-containing aliphatic phosphate.

14. Use of a composition comprising a copper compound and a halogen-containing aliphatic phosphate for stabilizing polyamides over a temperature range of less than 150 ° C and more than 150 ° C.

15. The method of claim 13 or use of claim 14, wherein the copper compound, the halogen-containing aliphatic phosphate and / or the polyamide are as in any one of claims 3 to 12.