HK1136000B - Improved processing conditions of polyethylene articles in course of their manufacture by melt processing - Google Patents

Description

Improved processing conditions of polyethylene articles during their preparation by melt processing

The present invention relates to the preparation of polyethylene-based wall articles with improved color and processing conditions, which object can surprisingly be achieved by specific combinations of stabilizers.

Polyolefins and other thermoplastics are susceptible to attack by oxygen at normal and elevated temperatures. Antioxidants and processing stabilizers retard oxidation of the polymer during extrusion, part preparation (injection, blow, rotomolding, etc.) and end use. Antioxidants and processing stabilizers help control the color and melt flow of the polymer and generally help maintain the physical properties of the polymer. The trend toward more severe processing conditions has led to the need for a stabilized "system" process. The combination of phenolic antioxidants and phosphite-based process stabilizers can improve color and melt stability during processing while maintaining long-term thermal stability. The system method protects the polymer from degradation during mixing, manufacturing, and regrinding operations. All formulation components of the polymer system have the following potential effects: (1) providing the environment required for stabilizer activity, and (2) influencing and participating in the stabilization reaction that takes place.

The stabilization principle is of economic value for a series of polyethylene-based plastic articles, which are certain uprights consisting of walls of a determined thickness. Practical examples are polyethylene tanks, receiving basins, cone bottom tanks, cross-linked polyethylene tanks and corresponding double-walled constructions, as well as plating drums, pendulums, plastic baskets for commercial, industrial, agricultural and personal applications.

Rotational molding or centrifugal casting applications are of significant interest. These specific applications are summarized below as rotomoulding, which is commonly used for the production of large hollow bodies from plastics which may additionally be reinforced with glass fibres. The method comprises the following steps: the plastic is filled in the mold and the mold is then closed. The device is heated at a temperature significantly above the melting range of the plastic and is rotated at a low speed around a different axis, resulting in the deposition of plastic melt on the inner wall side of the rotating device. After cooling, the hollow plastic product can be removed. Products such as tanks and containers for truck and stationary storage purposes made from medium density polyethylene (MDPE, which is also commonly classified as high density polyethylene HDPE) or Low Linear Density Polyethylene (LLDPE) can be prepared using this process. Preferably MDPE or LLDPE homopolymers, copolymers of ethylene and butene (MDPE-or LLDPE-butene copolymers), more preferably copolymers of ethylene and hexene or octane (MDPE-or LLDPE-hexene copolymers or MDPE-or LLDPE-octene copolymers), provide the necessary durability and rigid molding while being as easy to process as other rotomolding resins having similar melt indices. Other examples are large agricultural and chemical storage containers and sinks for boats, kayaks and canoes.

The furnace temperatures required in this process are generally higher than 250 ℃ and sometimes even more than 400 ℃. In addition to the need for careful selection of the appropriate polymer species, these harsh conditions also require careful selection of the stabilizer. Rotomolding polyolefin grades must provide a broad processing window (i.e. outstanding color melt flow stability), good oxidation resistance during processing, and should have as low a viscosity as possible for the mold to release the article better after processing. Products molded using the above polyethylene can now replace crosslinked polyethylene, glass fiber and even steel products due to high rigidity and excellent mechanical properties.

From R.H.M muller, "Plastics additives handbook", Hanser Publishers, pages 40-71 (1990) it is known to use stabilizers combinations of phosphites or phosphonites (phosphonites) with sterically hindered phenol-based antioxidants and/or sterically hindered amine-based stabilizers (HAS) in polyolefins.

US2003146542 discloses a process for preparing a rotomoulded polyolefin polymer product.

WO0162832 discloses polyolefin polymer powders for rotational moulding in the presence of stabilizers including UV-stabilizers.

US 3,755,610 discloses a PCl prepared by reacting₃With 4, 4' -thiobis- (6-tert-butyl-m-cresol).

In the case of moulded polyethylene articles, the known stabilizer systems unfortunately only meet all requirements to a certain extent.

It has been surprisingly found that certain combinations of stabilizers improve the state of the art in processing polyethylene-based polymers.

The subject of the present invention is a process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, comprising a component a, a component B and a component D;

component A comprises a passable PCl₃A compound of formula (I) obtained by reaction with a compound of formula (Ia);

component B is selected from compounds of formula (II), (IV) and (IX);

component D is selected from the group consisting of compounds of formulae (XXV), (XXVI), (XXVII), (XXVIII), (XXIX), (XXXI) and (LIII) and combinations of compounds of formulae (XXV) and (XXVIII);

and optionally at least one component selected from component C, component E and component F;

component C is an antioxidant based on a primary sterically hindered phenol,

component E is a UV absorber, and

the component F is an antacid.

4, 4' -thiobis- (6-tert-butyl-m-cresol)

Tris (2, 4-di-tert-butylphenyl) phosphite

Bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite

Tetrakis (2, 4-di-tert-butylphenyl) [1, 1-biphenyl ] -4, 4' -diyl diphosphonite (bisphonite)

Polymerized [ N, N' -bis (2, 2, 6, 6-tetramethyl-4-piperidyl) hexanediamine/2, 4-dichloro-N- (1, 1, 3, 3-tetramethylbutyl) -1, 3, 5-triazin-2-amine ]

(XXVI)

And polymers of epichlorohydrin

Polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin

1, 6-hexanediamine, N, N' -bis (2, 2, 6, 6-tetramethyl-4-piperidyl) -, polymers with 2, 4, 6-trichloro-1, 3, 5-triazine, reaction products with N-butyl-1-butylamine and N-butyl-2, 2, 6, 6-tetramethyl-4-piperidinamine

Poly- [1- (2' -hydroxyethyl) -2, 2, 6, 6-tetramethyl-4-hydroxypiperidinyl succinate

Poly- [ (6-morpholino-s-triazine-2, 4-diyl) [2, 2, 6, 6-tetramethyl-4-piperidyl) imino ] -hexylidene- [ (2, 2, 6, 6-tetramethyl-4-piperidyl) imino ] ]

1, 3-bis- [2 '-cyano-3', 3-diphenylacryloyl) oxy ] -2, 2-bis- { [ 2-cyano-3 ', 3' -diphenylacryloyl) oxy ] methyl } propane

Malonic acid [ (4-methoxyphenyl) -methylene ] -bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) ester

In a preferred embodiment, the combination COMB comprises component F.

In another preferred embodiment, the combination COMB comprises component C.

In a more preferred embodiment, the combination COMB comprises component C and component F.

Components A, B, C, D, E and F are known from the literature, for example "Plastics Additives Handbook", 5 th edition, compiled by H.Zweifel, Hanser Publishers, Munich (2001). In principle, all components A, B, C and D cited in the "plastics additives handbook" can be used.

Preferably component A comprises at least 10% by weight, preferably 20% by weight, more preferably 30% by weight, more preferably 40% by weight, especially 50% by weight, of the compound of formula (I), based on the total weight of component A. The remainder of component A is generally composed of other substances formed during the preparation of the compounds of the formula (I).

Component A, which preferably comprises compounds of the formula (I), is a commercially available productOSP-1。

Component A may also consist of compounds of the formula (I).

Preferably, component B is a compound of formula (II) (preferablyPAR 24) or compounds of the formula (IX), preferablyP-EPQ)。

Preferably, component D is a compound of the formula (XXVI) (preferablyN30)。

In all embodiments and preferred embodiments of the present invention, preferably component C is selected from compounds of formula (XI), (XII), (XIII), (XIV), (XV), (XVI), (XVII), (XVIII), (XIX), (XXXII), (LXXII), (LXXIV) and (LXXV);

2, 6-di-tert-butyl-4-methyl-phenol

Octadecyl 3, 5-di-tert-butyl-4-hydroxyhydrocinnamate

Tetrakis [ methylene (3, 5-di-tert-butylhydroxyhydrocinnamate) ] -methane

1, 3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene

1, 3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate

3, 5-bis (1, 1-dimethyl-ethyl) -4-hydroxy-C₇-C₉-alkyl esters

Triethylene glycol bis (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionate

1, 6-hexanediol bis-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate

Bis [3, 3-bis- (4 '-hydroxy-3' -tert-butylphenyl) butanoic acid ] -ethylene glycol ester

1, 3, 5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) -1, 3, 5-triazine-2, 4, 6- (1H, 3H, 5H) -trione

Calcium bis (((3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl) methyl) -diethylphosphonate

2, 6-di-tert-butyl-4-ethyl-phenol

2- (1, 1-Dimethylethyl) -6- [3- (1, 1-Dimethylethyl) -2-hydroxy-5-methylphenyl ] -4-methylphenyl-acrylate

More preferably component C is selected from compounds of formula (XII), (XIII), (XIV), (XV), (XIX) and (XXXII);

more preferably component C is selected from compounds of formula (XII) (preferablyO16), a compound of formula (XIII) (preferablyO10) and compounds of the formula (XIX) (preferred)O3)；

Particularly preferably, component C is a compound of the formula (XII) (preferablyO16)。

In all embodiments and preferred embodiments of the present invention, it is preferred that component E is selected from the group consisting of hydroxybenzotriazoles, hydroxybenzophenones, hydroxyphenyl triazines, cyanoacrylates, cinnamic acid derivatives, benzylidene malonates, oxalanilides, benzoxazinones, zinc oxide, titanium dioxide, carbon black and nickel quenchers;

more preferably component E is selected from hydroxybenzotriazoles, hydroxybenzophenones, hydroxyphenyltriazines and benzylidene malonates;

more preferably, component E is selected from compounds of formula (XXXV), (XXXVI), (XXXVII), (XXXVIII), (XXXIX), (XL), (XLI), (XLIIII), (XLIV), (XLVVI), (XLVVII), (XLVVIII), (XLIX), (L), (LI), (LII), (LIII), (LIV), (LV), (LVI), (LVII), (LVIII), (LIX) and (LXXII);

2-hydroxy-4-n-octoxy benzophenone

2-hydroxy-4-methoxybenzophenone

2, 4-dihydroxy benzophenone

Bis- (2-hydroxy-4-methoxyphenyl) methanone

2, 2 ', 4, 4' -tetrahydroxybenzophenone

2-hydroxy-2' -allyloxybenzophenones

2-hydroxy-2' -methoxybenzophenone

2, 2 ' -dihydroxy-4, 4 ' -dimethoxy benzophenone-5, 5 ' -disulfonic acid sodium salt

2, 2' -dihydroxy-4-methoxybenzophenone

2- (2 '-hydroxy-5' -methylphenyl) benzotriazole

2- [ 2-hydroxy-3, 5-bis- (a, a-dimethylbenzyl) phenyl ] -2H-benzotriazole

2- (5-chlorobenzotriazol-2-yl) -4-methyl-6-tert-butyl-phenol

2- (2 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) -benzotriazole

2- (2H-Benzotriazol-2-yl) -4- (tert-butyl) -6- (sec-butyl) phenol

2- (4, 6-Diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol

- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol

Malonic acid, [ (4-methoxyphenyl) -methylene ] -dimethyl ester

Malonic acid [ (4-methoxyphenyl) -methylene ] -bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) ester

Tetra-ethyl-2, 2' - (1, 4-phenylene-dimethylene) -dimalonate

2-ethyl-2' -ethoxy-oxalanilides

Ethyl-2-cyano-3, 3-diphenylacrylate

(2-ethylhexyl) -2-cyano-3, 3-diphenylacrylate

1, 3-bis- [ (2 '-cyano-3', 3 '-diphenylacryloyl) oxy ] -2, 2-bis- { [ (2' -cyano-3 ', 3' -diphenylacryloyl) oxy ] methyl } -propane

2, 2' - (1, 4-phenylene) bis [4H-3, 1-benzoxazin-4-one ]

2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol

Particularly preferably, component E is selected from compounds of formula (XXXV), (XLVII), (XLVIII), (L), (LI) and (LXXII).

In all embodiments and preferred embodiments of the present invention, preferably component F is selected from calcium lactate of formula (LX), hydrotalcite, sodium benzoate, zinc oxide of formula (LXIX) and metal stearates; preferably the hydrotalcite is selected from the formulae (LXI), (LXII), (LXIII) and (LXIV); preferably sodium benzoate is of formula (LXV); preferably the metal stearate is selected from calcium stearate of formula (LXVI), zinc stearate of formula (LXVII) or sodium stearate of formula (LXVIII), more preferably zinc stearate;

calcium lactate

{Mg₆Al₂(OH)₁₆CO₃-4H₂O}

(LXI), Natural mineral hydrotalcite

{Mg_4.5Al₂(OH)₁₃CO₃.3.5H₂O}

(LXII), preferably synthetic hydrotalcite DHT-4A

{Mg_4.35Al₂(OH)_11.36(CO₃)_1.67.xH₂O}

(LXIII), preferably synthetic hydrotalcite L-55RII

{Mg₄Al₂(OH)₁₂CO₃.2.85H₂O}

(LXIV), preferably the synthetic hydrotalcite, Balropol MC 6280

Sodium benzoate

Metal stearate:

(LXVI): Me-Ca, calcium stearate

(LXVII): Me-Zn, zinc stearate

(LXVIII): me is Na, sodium stearate

ZnO

(LXIX), Zinc oxide

More preferably, component F is ZnO, hydrotalcite or a metal stearate; preferably the hydrotalcite is selected from the formulae (LXI), (LXII), (LXIII) and (LXIV), more preferably the hydrotalcite is of formula (LXII); preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate;

more preferably component F is ZnO, a hydrotalcite of formula (LXII) or a metal stearate; preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate.

More preferably component F is a metal stearate; preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate.

Particularly preferably, the subject of the invention is a process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, said combination COMB comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX); and

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin;

and optionally at least one component selected from

Component C, component C is selected from octadecyl 3, 5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis [ methylene (3, 5-di-tert-butylhydroxyhydrocinnamate) ] -methane and bis [3, 3-bis- (4 '-hydroxy-3' -tert-butylphenyl) butanoic acid ] -ethylene glycol ester;

component E, component E is selected from 2-hydroxy-4-n-octoxybenzophenone, 2- (5-chlorobenzotriazol-2-yl) -4-methyl-6-tert-butyl-phenol, 2- (2 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) -benzotriazole, 2- [4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazin-2-yl ] -5- (octyloxy) phenol, 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol and 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol; and

and the component F is metal stearate.

Particularly preferably, the subject of the invention is a process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, said combination COMB comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component C, component C is selected from octadecyl 3, 5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis [ methylene (3, 5-di-tert-butylhydroxyhydrocinnamate) ] -methane or bis [3, 3-bis- (4 '-hydroxy-3' -tert-butylphenyl) butanoic acid ] -ethylene glycol ester; and

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin;

and optionally at least one component selected from

Component E, component E is selected from 2-hydroxy-4-n-octoxybenzophenone, 2- (5-chlorobenzotriazol-2-yl) -4-methyl-6-tert-butyl-phenol, 2- (2 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) -benzotriazole, 2- [4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazin-2-yl ] -5- (octyloxy) phenol, 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol and 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol; and

and the component F is metal stearate.

Also particularly preferred, the subject of the invention is a process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, said combination COMB comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin;

component F, component F being a metal stearate, preferably zinc, calcium or sodium stearate, more preferably zinc stearate;

and optionally at least one component selected from

Component C, component C is selected from octadecyl 3, 5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis [ methylene (3, 5-di-tert-butylhydroxyhydrocinnamate) ] -methane and bis [3, 3-bis- (4 '-hydroxy-3' -tert-butylphenyl) butanoic acid ] -ethylene glycol ester; and

component E, component E is selected from 2-hydroxy-4-n-octoxybenzophenone, 2- (5-chlorobenzotriazol-2-yl) -4-methyl-6-tert-butyl-phenol, 2- (2 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) -benzotriazole, 2- [4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazin-2-yl ] -5- (octyloxy) phenol, 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol and 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol.

Particularly preferably, the subject of the invention is a process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, said combination COMB comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component C, component C is selected from octadecyl 3, 5-di-tert-butyl-4-hydroxyhydrocinnamate, tetrakis [ methylene (3, 5-di-tert-butylhydroxyhydrocinnamate) ] -methane and bis [3, 3-bis- (4 '-hydroxy-3' -tert-butylphenyl) butanoic acid ] -ethylene glycol ester;

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin; and

component F, component F being a metal stearate, preferably zinc, calcium or sodium stearate, more preferably zinc stearate;

and optionally at least one component selected from

Component E, component E is selected from 2-hydroxy-4-n-octoxybenzophenone, 2- (5-chlorobenzotriazol-2-yl) -4-methyl-6-tert-butyl-phenol, 2- (2 ' -hydroxy-3 ', 5 ' -di-tert-butylphenyl) -benzotriazole, 2- [4, 6-bis (2, 4-dimethylphenyl) -1, 3, 5-triazin-2-yl ] -5- (octyloxy) phenol, 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] -phenol and 2, 4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol.

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component D, component D being selected from the group consisting of compounds of the formulae (XXV), (XXVI), (XXVII), (XXVIII), (XXIX), (XXXI) and (LIII) and combinations of compounds of the formulae (XXV) and (XXVIII).

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component D, component D being selected from the group consisting of compounds of formulae (XXV), (XXVI), (XXVII), (XXVIII), (XXIX), (XXXI) and (LIII) and combinations of compounds of formulae (XXV) and (XXVIII); and

component F, component F is a metal stearate, preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate.

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component D, component D is a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin.

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, selected from compounds of formulae (II), (IV) and (IX), preferably compounds of formulae (II) and (IX);

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin; and

component F, component F is a metal stearate, preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate.

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, which is a compound of formula (II) or (IX);

component D, component D is a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin.

Another subject of the invention is a composition comprising

Component A, component A comprising a compound of formula (I);

component B, which is a compound of formula (II) or (IX);

component D, component D being a polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin; and

component F, component F is a metal stearate, preferably the metal stearate is zinc stearate, calcium stearate or sodium stearate, more preferably zinc stearate.

Preferred compositions comprising components A, B and D and compositions comprising components A, B, D and F are compositions wherein component A comprises at least 10% by weight, preferably 20% by weight, more preferably 30% by weight, more preferably 40% by weight and especially 50% by weight of a compound of formula (I), based on the total weight of component A. Preferably, the compounds of formula (I) are obtainable by PCl₃With a compound of formula (Ia). The remainder of component A is generally composed of other substances formed during the preparation of the compounds of the formula (I). Component A, which preferably comprises compounds of the formula (I), is a commercially available productOSP-1。

Component A may also consist of compounds of the formula (I).

The composition comprising components A, B and D and the composition comprising components A, B, D and F comprise at least 50%, preferably 75%, more preferably 90% by weight of the sum of the weights of components A, B and D or the sum of the weights of components A, B, D and F, respectively, based on the total weight of the composition. Compositions comprising components A, B and D and compositions comprising components A, B, D and F may also consist only of components A, B and D and components A, B, D and F, respectively. The relative ratio of the total weight of components B and D or of components B, D and F to the weight of component A can be from 1: 20 to 20: 1, preferably from 1: 10 to 10: 1, more preferably from 1: 5 to 5: 1.

The composition comprising components A, B and D and the composition comprising components A, B, D and F may comprise further components, preferably selected from the group consisting of primary sterically hindered phenol based antioxidants, antacids, UV absorbers, metal deactivators, sulfur based thioethers, antistatic agents and lubricants.

Compositions comprising components A, B and D and compositions comprising components A, B, D and F can be prepared by physically combining the components, preferably by blending or mixing, preferably in the solid or molten state of the compounds; blending or mixing is preferably carried out by means of dry blending. Another subject of the present invention is therefore a process for preparing a composition comprising components A, B and D or a composition comprising components A, B, D and F by physically combining the components.

Another subject of the present invention is the use of a composition comprising components A, B and D or a composition comprising components A, B, D and F for stabilizing polyethylene, preferably in a rotomolding polyethylene process.

Another subject of the present invention is a polyethylene article stabilized during its preparation by adding to the polyethylene during processing of the polyethylene, preferably during rotomoulding of the polyethylene, a composition comprising components A, B and D or a composition comprising components A, B, D and F.

Preferably the polyethylene is selected from HDPE, MDPE, LDPE, LLDPE and copolymers of ethylene with butene, hexene or octene, more preferably HDPE, MDPE, LLDPE and copolymers thereof based on butene, hexene or octene, more preferably MDPE, LLDPE and ethylene hexene or ethylene octene copolymers thereof.

Preferably, the MDPE has a density of 0.92 to 0.95g/cm³While LLDPE having a density of 0.91 to 0.94g/cm is preferred³

Component A is preferably used in an amount of from 0.01 to 1.0% by weight, more preferably from 0.02 to 0.2% by weight, based on the weight of the polyethylene.

Preferably, components B, C, D, E and F are used in amounts of from 0.01 to 5% by weight, more preferably from 0.02 to 0.5% by weight, each independently of the other, based on the weight of the polyethylene.

It is possible to use more than one of the individual components B, C, D, E and/or F, for example component A with two different components B and one component D. In this case, the sum of the weights of the combination components A, based on the weight of the polyethylene, is in accordance with the weight ranges mentioned above; this also applies to the sum of the weights of the combined components of B, C, D, E and F, respectively.

Component A, B, C, D, E and/or F can be added to the polyethylene as separate components, in the form of a composition, in the form of one or more masterbatches, or a combination of these possible forms; each composition or masterbatch may comprise one or more of components A, B, C, D, E and/or F in all possible combinations.

Component A, B, C, D, E and/or F can be added before processing the polyethylene or at any time during processing of the polyethylene.

Component a and components B, C, D, E and F are preferably added to polyethylene as separate components, in the form of a masterbatch or a combination of both before or during processing of the polyethylene, preferably before or during extrusion of the polyethylene, more preferably before or during melt extrusion of the polyethylene, to give a polyethylene composition comprising polyethylene and components a-F, which is usually referred to as polyethylene compound (compound). Preferably the polyethylene compound is ground prior to further processing, preferably said further processing is rotational moulding, extrusion, melt extrusion, extrusion blow moulding, injection moulding and film blow moulding, more preferably rotational moulding.

The combination of component a with component B, C, D, E and/or F in all of the preferred embodiments and combinations serves to stabilize the polyethylene during processing, preferably as a processing stabilizer to improve thermal stability and oxidation resistance, to prevent discoloration during processing of the polyethylene and to improve mold release at the end of processing of the polyethylene. Preferably, the component A, B, C, D, E and/or F combination in all of the preferred embodiments and combinations is used to stabilize polyethylene and is added before or during rotomoulding, extrusion, melt extrusion, extrusion blow moulding, injection moulding and film blow moulding, more preferably before or during rotomoulding.

Preferably the polyethylene is rotomoulded at a temperature above 250 ℃, more preferably above 280 ℃, more preferably above 300 ℃.

The rotomolding polyethylene preferably has a processing time of 5 minutes or more, more preferably 10 minutes or more, and still more preferably 20 minutes or more.

The combination COMB of component a with component B, C, D, E and/or F in all the preferred embodiments and combinations can also comprise customary processing additives, such as metal deactivators, sulfur-based thioethers, antistatics or lubricants.

Another subject of the present invention is a polyethylene article prepared by any one of the processes described and stabilized thereby by a combination of compounds COMB described in all the preferred embodiments and combinations.

It is surprising that the use of the combination of components A, B and C and/or D and optionally F improves the processability of the polyethylene in terms of thermal stability and oxidation resistance. Significant antioxidant effect, high melt flow stability, reduced coloring tendency and improved mold release properties of the processed polyethylene and the prepared articles are observed, especially during wall formation in rotomolding processes.

Discoloration of the article, often indicated by an increase in the Yellowness Index (YI), is reduced. Mold release capacity (DMA) is increased, meaning that less or no intrinsic mold release aids, such as metal stearates, are required, which can adversely affect color and melt flow properties.

Also, when a metal stearate is used, the use of component a greatly reduces the yellowness index. The melt flow index shows an unexpected synergistic effect when both the metal stearate and component a are used.

The combination of component A, B and C and/or D and optionally F shows an improved antioxidant effect as measured by the Oxidation Induction Time (OIT). During rotomoulding, the polymer article is primarily exposed to heat, which over processing time leads to polymer oxidation, in other words resin degradation. Oxidation Induction Time (OIT), an indicator of antioxidant efficiency in a resin to prevent oxidation with exposure time, is a key factor in rotomoulding processes.

An improvement in Melt Flow Index (MFI) or Melt Flow Rate (MFR) was also observed.

Examples

Measurement of the different exposure times T according to DIN 6167_mYellowness index YI of (1). The smaller the YI, the better.

The melt flow index MFI [ g/10min ] is determined in accordance with ISO 1133. The larger the MFI, the better.

The oxidation induction time in minutes, OIT, was measured using differential scanning calorimetry, DSC: the sample was heated at 20 ℃/min (in a DSC oven) from 40 ℃ up to 200 ℃ isothermally held for 3 minutes in a nitrogen atmosphere. The recycle gas was then replaced with oxygen until oxidation was observed, which involved an exothermic reaction. The onset time of the exothermic reaction determines the OIT value.

The larger the OIT, the better.

Empirically evaluating different exposure times T_mAnd is described in three categories

"E": easy demoulding

"M": demolding with moderate difficulty

"D": difficult to demould

The substances used were:

polyethylene:

LLDPE-1: ethylene-butene copolymer, d ═ 0.938g/cm³MFI 4g/10 min, rotomolding grade, in powder form

And (2) component A:

comprising a compound of formula (I)OSP1(OSP-1)。

And (B) component:

PAR24(PAR24)

P-EPQ(P-EPQ)

and (3) component C:

O16(O16)

and (3) component D:

N30(N30)

component E

UV absorbers

And (3) component F:

zinc stearate (stearic acid Zn)

Examples 1-13, mold release and OIT improvement

The mixture of LLDPE-1 and components was prepared in a low speed mixer (Kenwood type blender) and then poured into an aluminum pan. The sample was then introduced into a ventilated oven at a temperature of 190 ℃ and maintained T therein_m15 minutes. The OIT values and DMA for the different powder mixtures are shown in table 1:

the first result was that Hostanox OSP-1 exhibited an elevated OIT value when included in the formulation. Furthermore, as shown in table 1, it was surprisingly observed that all samples containing OSP-1 were very easy to demould relative to all other formulations.

Examples 20 to 23, improvement in color stability and mold releasability

The mixture of LLDPE-1 polymer and components was prepared in a low speed mixer (Kenwood type blender) and then extruded and pelletized in a single screw extruder. The processed granules were poured into an aluminum pan. The sample was then introduced into a ventilated oven at a temperature of 190 ℃ T_m30, 60, 90 and 120 minutes. The YI results are shown in Table 2.

Outstanding color stability (resistance to yellowing) was observed for the Hostanox OSP-1 based formulations relative to other formulations including those based on P-EPQ and N30. The DMA results are shown in Table 3.

The samples containing Hostanox OSP-1 showed significantly easier mold release capability relative to other formulations including P-EPQ and N30 based formulations.

Examples 30 to 33, color stability and MFI stability

The mixture of LLDPE-1 and components was prepared in a low speed mixer (Kenwood type blender) and then extruded and pelletized in a single screw extruder. The processed granules were poured into an aluminum pan. The samples were then introduced into the vented oven at 190 ℃ for 30, 60, 90 and 120 minutes. MFI and YI are shown in tables 4 and 5.

Most formulations contain a metal stearate as a release agent or release agent. Zinc stearate used as a releasing agent has disadvantages of causing color shift and changing melt flow properties.

Color stability: OSP-1 based formulations with or without zinc stearate exhibit outstanding color stability during curing over other formulations including P-EPQ and N30 based formulations in combination with zinc stearate.

MFI stability:

does not have zinc stearate: OSP-1 based formulations exhibit outstanding MFI stability.

The zinc stearate formula comprises: OSP-1 based formulations showed improved MFI protection over P-EPQ and N30 based formulations combined with zinc stearate.

Claims (16)

1. A process for stabilizing polyethylene, characterized in that a combination COMB of compounds is used, said combination COMB comprising

Component A, component B and component D;

component A comprises a passable PCl₃A compound of formula (I) obtained by reaction with a compound of formula (Ia);

component B is selected from compounds of formula (II), (IV) and (IX);

component D is selected from the group consisting of compounds of formulae (XXV), (XXVI), (XXVII), (XXVIII), (XXIX), (XXXI) and (LIII) and combinations of compounds of formulae (XXV) and (XXVIII);

and optionally at least one component selected from component C, component E and component F;

component C is an antioxidant based on a primary sterically hindered phenol,

component E is a UV absorber, and

component F is an antacid

4, 4' -thiobis- (6-tert-butyl-m-cresol)

Tris (2, 4-di-tert-butylphenyl) phosphite

Bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite

Tetrakis (2, 4-di-tert-butylphenyl) [1, 1-biphenyl ] -4, 4' -diyl diphosphonite

Polymerized [ N, N' -bis (2, 2, 6, 6-tetramethyl-4-piperidyl) hexanediamine/2, 4-dichloro-N- (1, 1, 3, 3-tetramethylbutyl) -1, 3, 5-triazin-2-amine ]

Polymer of 2, 2, 4, 4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] -heneicosane-21-one and epichlorohydrin

1, 6-hexanediamine, N, N' -bis (2, 2, 6, 6-tetramethyl-4-piperidyl) -, polymers with 2, 4, 6-trichloro-1, 3, 5-triazine, reaction products with N-butyl-1-butylamine and N-butyl-2, 2, 6, 6-tetramethyl-4-piperidinamine

Poly- [1- (2' -hydroxyethyl) -2, 2, 6, 6-tetramethyl-4-hydroxypiperidinyl succinate

Poly- [ (6-morpholino-s-triazine-2, 4-diyl) [2, 2, 6, 6-tetramethyl-4-piperidyl) imino ] -hexylidene- [ (2, 2, 6, 6-tetramethyl-4-piperidyl) imino ] ]

1, 3-bis- [2 '-cyano-3', 3-diphenylacryloyl) oxy ] -2, 2-bis- { [ 2-cyano-3 ', 3' -diphenylacryloyl) oxy ] methyl } propane

Malonic acid [ (4-methoxyphenyl) -methylene ] -bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) ester

Characterized in that component A, B, C, D, E and/or F is added to the polyethylene as a separate component, in the form of a composition, in the form of one or more masterbatches or a combination of these possible forms.

2. The method of claim 1, wherein said combination COMB comprises component F.

3. The method of claim 1 or 2, wherein said component B is a compound of formula (II) or a compound of formula (IX).

4. The process of claim 1 or 2, wherein said component D is a compound of formula (XXVI).

5. The process of claim 1 or 2, wherein component F is ZnO, hydrotalcite or a metal stearate.

6. The process of claim 5, wherein the hydrotalcite is of formula (LXII)

{Mg_4.5Al₂(OH)₁₃CO₃.3.5H₂O}(LXII)。

7. The method of claim 5, wherein the metal stearate is zinc stearate, calcium stearate, or sodium stearate.

8. The method according to claim 1 or 2, characterized in that the processing of the polyethylene is selected from the group consisting of rotomoulding, extrusion blow moulding, injection moulding and film blow moulding.

9. A method according to claim 1 or 2, characterized in that the processing of the polyethylene is rotational moulding.

10. The process according to claim 1 or 2, characterized in that the polyethylene is selected from the group consisting of MDPE, LLDPE and ethylene hexene copolymers.

11. A polyethylene article prepared by the process of any one of claims 1 to 10.

12. A composition comprising

Component a comprising a compound of formula (I) according to claim 1;

component B selected from the group consisting of compounds of formula (II), (IV) and (IX) of claim 1;

component D, component D being selected from the group consisting of the compounds of the formulae (XXV), (XXVI), (XXVII), (XXVIII), (XXIX), (XXXI) and (LIII) according to claim 1 and the combinations of the compounds of the formulae (XXV) and (XXVIII).

13. The composition of claim 12 comprising component F, component F being a metal stearate.

14. A process for preparing the composition of claim 12 or 13 by physically combining the components.

15. Use of a composition according to claim 12 or 13 for stabilizing polyethylene.

16. Use of a composition according to claim 12 or 13 for stabilizing polyethylene during rotomoulding.