WO2008055832A2

WO2008055832A2 - Process using liquid phenolic antioxidants

Info

Publication number: WO2008055832A2
Application number: PCT/EP2007/061745
Authority: WO
Inventors: Laurent Cavin; Paul Nebel; Andreas Cendra
Original assignee: Ciba Holding Inc.
Priority date: 2006-11-09
Filing date: 2007-10-31
Publication date: 2008-05-15
Also published as: TW200844158A; WO2008055832A3

Abstract

The invention relates to a process for process for stabilizing polymers by addition of phenolic antioxidants in the form of a concentrated fluid, which comprises cooling, dosing in suitable containers and storing the fluid under the exclusion of oxygen and light, optionally remelting and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

Description

Preparation of fluid phase of phenolic antioxidants

The invention relates to a process for process for stabilizing polymers by addition of phenolic antioxidants in the form of a concentrated fluid and to the preparation of that fluid.

Solid phenolic additives, such as commercial antioxidants from the Irganox® and Irgafos® (trade marks of Ciba Specialty Chemicals) series, e.g. IRGANOX 1010: pentaerythritol tetra- kis[3-(3,5-di-tert-butyl4-hydroxyphenyl)-propionate], IRGANOX 1076: octadecyl-3-(3,5- di-tert-butyl-4-hydroxyphenyl)-propionate, IRGANOX 1098: N,N'-hexane-1 ,6-diyl-bis[3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide)], or IRGAFOS 168: tris(2,4-di-t-butylphenyl)- phosphite, are used for a great variety of technical applications, particularly for the stabilisa- tion of thermoplastic polymers against oxidative, thermal or light induced degradation.

Most of these additives are added in solid form, e.g. in crystal form, to the polymer materials, which are commercially in solid form as well, particularly in the form of pellets or granulates. The mixtures of antioxidants with polymers are further processed by various moulding methods, particular kneading or extrusion methods. Therefore, phenolic antioxidants are commercially available in the form of solid particles, e.g. powders, comminuted powders or granulates. In the event that reaction conditions are applied in the liquid phase, the isolation of these particles from the liquid phase requires a separation step.

According to WO 01/98249 IRGANOX 1010 is available as a melt by re-esterification of mol- ten 3-(3,5-di-tert-butyl4-hydroxyphenyl)-propionic acid methyl ester with pentaerythritol. The melt phase is subsequently dried and recrystallised from a solvent. Any subsequent separation of solid particles obtained in crystal form from solvents or liquid reaction mixtures has certain drawbacks. The formation of crystalline particles in a liquid phase is a time and energy consuming process that has to be carefully monitored with regard to the composition of the liquid phase, concentration and temperature.

Solid phenolic antioxidants, such as IRGANOX 1010 or 1098, are presently isolated in crystal form from the solvent methanol, which reduces the formation of larger amounts of amorphous material. It has been found that amorphous particles of these phenolic antioxidants are subject to undesirable discolouration processes. An explanation for this effect is the pos- sible migration of oxygen in amorphous material. The crystal lattice of crystalline material would prevent the migration of oxygen.

According to EP-A-O 403 431, solid particles of phenolic antioxidants, such as IRGANOX 1010, are prepared by introducing a melt of the phenolic antioxidant into a cold agitated solution of an organic water-miscible solvent, such as methanol, and isolating the particles obtained. The disadvantage of this process is seen in the fact that mixtures of solid particles of low homogeneity are obtained which contain varying amounts of amorphous and crystalline material. According to WO 2004/048312 solid particles of phenolic antioxidants, such as

IRGANOX 1010 or 1098, are obtained from an aqueous phase to which a selected non-ionic surfactant, e.g. Tween®80, and larger amounts of seed crystals have been added.

According to WO 2006/010718, a solidified melt of the above-mentioned phenolic antioxidants, e.g. IRGANOX 1010 or 1098 or IRGAFOS 168, and the addition of the melt to an aqueous dispersion of these phenolic antioxidants in an organic water-miscible solvent, e.g. methanol, produces solid particles in essentially crystalline form.

The further processing of solid particles obtained from solution, such as crystals, to dry particle forms, such as granulates, bears the risk of undesirable dust formation resulting from abrasion, attrition or inter-particle friction. The formation of dust is a well-known problem that may eventually extend as far as dust explosion. More common are feeding and dosage problems when producing precise and reproducible weight amounts. A possible explanation is given by the lack of homogeneity and irregular shape of the particles formed.

There is a strong need for an improved alternative process that avoids the problems of the crystal formation process presently used for the preparation of solid phenolic antioxidants, such as IRGANOX 1010 or 1098.

It has surprisingly been found that polymers are stabilized by the direct addition of phenolic antioxidants in the form of a concentrated fluid, e. g. as a melt, as opposed to the addition of solid materials, e.g. granulates.

Therefore, the present invention relates to process for stabilizing polymers by addition of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives, which comprises preparing a concentrated fluid of

At least one compound of the formula:

(l)>

Wherein one of Ri and R₂ independently of one another represents hydrogen or d-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and R₃ represents groups of the partial formulae

Wherein one of R-T and R₂' independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and y represents a numeral from 2 - 6; or a concentrated fluid mixture thereof with other polymer additives; cooling and storing the fluid under the exclusion of oxygen and light; optionally remelting the solidified fluid; and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

An alternative embodiment of the invention relates to a process for stabilizing polymers by addition of a mixture of phenolic antioxidants, which comprises preparing a concentrated fluid mixture of At least one compound of the formula: - A -

Wherein one of Ri and R₂ independently of one another represents hydrogen or d-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and R₃ represents C₈-C₂₂alkyl; And at least one compound (I),

Wherein one of Ri and R₂ independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and R₃ represents groups of the partial formulae

Wherein one of Ri' and R₂' independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and y represents a numeral from 2 - 6; or a concentrated fluid mixture thereof with other polymer additives; cooling and storing the fluid under the exclusion of oxygen and light; optionally remelting the solidified fluid; and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

The general terms used in the description of the instant invention, unless defined otherwise, are defined as follows:

The term concentrated fluid comprises within its scope emulsion, suspensions, melts or melt solutions, wherein at least 75%, preferably at least 90%, particularly at least 95%, and most preferably at least 98%, phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives are present.

The term concentrated fluid is defined within the limits of so-called solid/liquid or liquid/liquid disperse systems, as opposed to other types of disperse systems, such as solid/gas, e.g. fumes, or gas/liquid, e.g. foams. Solid/liquid dispersions that apply here consist of a fluid two-phase system containing solid particles, such as crystals, within a liquid, particularly a melt phase. According to a preferred embodiment, the amount of solid particles in the liquid is up to 90.0% by weight, particularly 0.1 to 55.0% by weight.

In a compound (I) Ri and R₂ defined as Ci-C₄alkyl comprise the unbranched and branched (where possible) groups methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl.

Ri and R₂ defined as C₃-C₄alkyl comprises unbranched and preferably branched groups, e.g. isopropyl, isobutyl or tert-butyl.

In a preferred embodiment of the invention one of Ri and R₂ represents hydrogen or Ci-C₄alkyl, particularly methyl or tert-butyl, and the other one represents C₃-C₄alkyl, particu- larly tert-butyl.

In a compound (I) the index x represents 0 (direct bond) or a numeral from 1 - 3. In the event that x is 0, the direct bond is defined.

In the event that x is 1 , the group -[C_xH_2x]- represents methylene.

In a preferred embodiment x represents 2. In that case the group -[C_xH_2x]- represents 1 ,1- or preferably 1 ,2-ethylene. In the event that x represents the numeral 3, the group -[C_xH_2x]- represents 1 ,1-, 1 ,2- or preferably 1 ,3-propylene.

R₃ defined as C₈-C₂₂alkyl represents, for example, n-octyl, 2-ethylhexyl, 1 ,1 ,3,3-tetramethyl- butyl, 1-methylheptyl, n-nonyl or 1 ,1 ,3-trimethylhexyl or Ci_O-C₂₂alkyl, particularly straight chained Ci_O-C₂₂alkyl, e.g. n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl or n-octadecyl or higher homologues thereof.

In the groups of the partial formulae (A), (B) and (C) Ri' and R₂' defined as Ci-C₄alkyl are identical with R₁ and R₂ defined above.

In a group of the partial formula (A) x represents 0 (direct bond) or a numeral from 1 - 3. In a preferred embodiment x represents 2.

In a group of the partial formula (B) x represents 0 (direct bond) or a numeral from 1 - 3 and y represents a numeral from 2 - 10. In a preferred embodiment x represents 2 and y represents 6.

In a group of the partial formula (C) x represents 0 (direct bond) or a numeral from 1 - 3 and y represents a numeral from 2 - 10. In a preferred embodiment x represents 2 and y represents 3.

A particularly preferred compound (I), wherein Y represents a group of the partial formula (A), R₁ and R₂ and, correspondingly, R₁' and R₂' represent tert-butyl and x represents two, is IRGANOX 1010: pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]. A particularly preferred compound (I), wherein Y represents a group of the partial formula (B), R₁ and R₂ and, correspondingly, R₁' and R₂' represent tert-butyl, x represents two and y represents six, is IRGANOX 1098: N,N'-hexane-1 ,6-diyl-bis[3-(3,5-di-tert-butyl-4- hydroxyphenylpropionamide)].

A particularly preferred compound (I), wherein Y represents a group of the partial for- mula (C), one of R₁ and R₂ and, correspondingly, one of R₁' and R₂' represents methyl and the other one represents tert-butyl, x represents two and y represents three, is IRGANOX 245: ethylene bis(oxyethylene)-bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate].

The concentrated fluid may comprise additional additives suitable for use in polymers, preferably additives customarily used for improving the chemical and physical properties of poly- mers containing these additives. The auxiliaries can be present in the dispersion in varying proportions, for example, in amounts of up to 80.0% by weight, preferably from 0.05% to 55.0% by weight. Suitable groups of additional additives are listed up here by way of example: antioxidants selected from the group consisting of alkylated monophenols, alkylthiomethylphenols, hydro- quinones and alkylated hydroquinones, tocopherols, hydroxylated thiodiphenyl ethers, alky- lidene-bis-phenols, O-, N- and S-benzyl compounds, hydroxybenzylated malonates, aromatic hydroxybenzyl compounds, triazine compounds, benzylphosphonates, acylaminophenols, other esters and amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid, β-(3,5-di-t-bu- tyl-4-hydroxy-3-methylphenyl)propionic acid, or β-(3,5-dicyclohexyl-4-hydroxyphenyl)propi- onic acid, ascorbic acid and aminic antioxidants, light stabilisers, phosphites, phosphines, phosponites, hydroxylamines, nitrones, thiosynergists, peroxide scavengers, polyamide stabilisers, basic co-stabilisers, nucleating agents, fillers and reinforcing agents, plasticisers, lubricants, emulsifiers, pigments, rheological additives, levelling assistants, optical bright- eners, flame proofing agents, antistatic agents, blowing agents, benzofuranones or indoli- nones.

A particularly preferred group comprises phosphorus containing additives selected from the group consisting of phosphines, phosphites and phosphonites, such as, in particular, tri- phenyl phosphite, diphenyl alkyl phosphite, phenyl dialkyl phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4- di-tert-butylphenyl) phosphite (lrgafos^®168, Ciba Specialty Chemicals), diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (formula (d) be- low), bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (formula (e)), bisisode- cyloxy-pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tristearyl sorbitol tri- phosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylenediphosphonite (lrgafos^®PEP-Q, Ciba Specialty Chemicals, formula (h)), 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo- [d,g]-1 ,3,2-dioxaphosphocin (formula (c)), 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyldiben- zo[d,g]-1 ,3,2-dioxaphosphocin (formula (a)), bis(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite (formula (g)).

Suitable additives optionally present in the concentrated fluid according to the present invention may be selected from the following non-exhaustive list of specific additives: The following additional polymer additives can be mixed together with the above-described phenolic polymer additives to form so-called blends:

1. Antioxidants

1.1 Alkylated monophenols, e.g. 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobu- tylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α,α-methylcyclohexyl)-4,6-dimethylphe- nol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-meth- oxymethylphenol, straight-chain or branched nonylphenols; e.g. 2,6-dinonyl-4-methyl- phenol, 2,4-dimethyl-6-(1 -methylundec-1 '-yl)-phenol, 2,4-dimethyl-6-(1 '-methylheptadec- 1 '-yl)-phenol, 2,4-dimethyl-6-(1'-methyltridec-1 '-yl)-phenol and mixtures thereof.

1.2 Alkylthiomethylphenols, e.g. 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthio- methyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-didodecylthiomethyl-4- nonylphenol.

1.3 Hydroquinones and alkylated hydroquinones, e.g. 2,6-di-tert-butyl-4-methoxyphenol, 2,5- di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxy- phenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl- 4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenylstearate, bis(3,5-di-tert-butyl-4-hy- droxyphenyl)adipate.

1.4 Tocopherols, e.g. α-, β-, γ- or δ-tocopherols and mixtures thereof (vitamin E). 1.5 Hydroxylated thiodiphenyl ethers, e.g. 2,2'-thio-bis(6-tert-butyl-4-methylphenol), 2,2'-thio- bis(4-octylphenol), 4,4'-thio-bis(6-tert-butyl-3-methylphenol), 4,4'-thio-bis(6-tert-butyl-2- methylphenol), 4,4'-thio-bis(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxy- phenyl) disulphide.

1.6 Alkylidene-bis-phenols, e.g. 2,2'-methylene-bis(6-tert-butyl-4-methylphenol), 2,2'-methyl- ene-bis(6-tert-butyl-4-ethylphenol), 2,2'-methylene-bis[4-methyl-6-(α-methylcyclohexyl)- phenol], 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis(6-nonyl-4- methylphenol), 2,2'-methylene-bis(4,6-di-tert-butylphenol), 2,2'-ethylidene-bis(4,6-di-tert- butylphenol), 2,2'-ethylidene-bis(6-tert-butyl-4-isobutylphenol), 2,2'-methylene-bis[6- (α-methylbenzyl)-4-nonylphenol], 2,2'-methylene-bis[6-(α,α-dimethylbenzyl)-4-nonylphe- nol], 4,4'-methylene-bis(2,6-di-tert-butylphenol), 4,4'-methylene-bis(6-tert-butyl-2-methyl- phenol), 1 ,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5- methyl-2-hydroxybenzyl)-4-methylphenol, 1 ,1 ,3-tris(5-tert-butyl-4-hydroxy-2-methyl- phenyl)butane, 1 ,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobu- tane, ethylene glycol bis[3,3-bis(3'-tert-butyl-4'-hydroxyphenyl)butyrate], bis(3-tert-butyl-4- hydroxy-5-methylphenyl)dicyclopentadiene, bis[2-(3'-tert-butyl-2'-hydroxy-5'-methylben- zyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1 ,1-bis(3,5-dimethyl-2-hydroxyphenyl)bu- tane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(5-tert-butyl-4-hydroxy-2- methylphenyl)-4-n-dodecylmercaptobutane, 1 ,1 ,5,5-tetra(5-tert-butyl-4-hydroxy-2-methyl- phenyl)pentane. 1.7 Q-, N- and S-benzyl compounds, e.g. 3,5,3',5'-tetra-tert-butyl-4,4'-dihydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzyl mercaptoacetate, tridecyl 4-hydroxy-3,5- di-tert-butylbenzyl mercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bis(4- tert-butyl-3-hydroxy-2,6-dimethylbenzyl) dithioterephthalate, bis(3,5-di-tert-butyl-4-hy- droxybenzyl) sulphide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzyl mercaptoacetate.

1.8 Hydroxybenzylated malonates, e.g. dioctadecyl 2,2-bis(3,5-di-tert-butyl-2-hydroxybenzyl) malonate, dioctadecyl 2-(3-tert-butyl-4-hydroxy-5-methylbenzyl) malonate, didodecyl mercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl) malonate, di-[4-(1 ,1 ,3,3-tetra- methylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl) malonate. 1.9 Aromatic hydroxybenzyl compounds, e.g. 1 ,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-

2,4,6-trimethylbenzene, 1 ,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylben- zene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

1.10 Triazine compounds, e.g. 2,4-bisoctylmercapto-6-(3,5-di-tert-butyl-4-hydroxyanilino)-

1 ,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1 ,3,5-triazine, 2- octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1 ,3,5-triazine, 2,4,6-tris(3,5-di- tert-butyl-4-hydroxyphenoxy)-1 ,2,3-triazine, 1 ,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1 ,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 2,4,6- tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1 ,3,5-triazine, 1 ,3,5-tris(3,5-di-tert-butyl-4-hy- droxyphenylpropionyl)hexahydro-1 ,3,5-triazine, 1 ,3,5-tris(3,5-dicyclohexyl-4-hydroxyben- zyl) isocyanurate.

1.1 1 Benzyl phosphonates, e.g. dimethyl-2,5-di-tert-butyl-4-hydroxybenzyl phosphonate, di- ethyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphonate, dioctadecyl-3,5-di-tert-butyl-4-hy- droxybenzyl phosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzyl phosphonate, calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

1.12 Acylaminophenols, e.g. 4-hydroxylauranilide, 4-hydroxystearanilide, octyl-N-(3,5-di-tert- butyl-4-hydroxyphenyl) carbamate.

1.13 Ascorbic acid (vitamin C).

1.14 Aminic antioxidants, e.g. N,N'-diisopropyl-p-phenylenediamine, N,N'-di-sec-butyl-p- phenylenediamine, N,N'-bis(1 ,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-bis(1-ethyl-3- methyl-pentyl)-p-phenylenediamine, N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'- dicyclohexyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di(2-naph- thyl)-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1 ,3-dimethyl- butyl)-N'-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, 4-(p-toluenesulphonamido)-diphenylamine, N,N'-dimethyl-N,N'-di-sec-butyl-p-phenylenediamine, diphenylamine, N-allyldiphenyl- amine, 4-isopropoxydiphenylamine, N-phenyl-1-naphthylamine, N-(4-tert-octylphenyl)-1- naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, e.g. p,p'-di-tert-oc- tyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol,

4-dodecanoylaminophenol, 4-octadecanoylaminophenol, di(4-methoxyphenyl)amine, 2,6- di-tert-butyl-4-dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodi- phenylmethane, N,N,N',N'-tetramethyl-4,4'-diamino-diphenylmethane, 1 ,2-di[(2-methyl- phenyl)amino]ethane, 1 ,2-diphenylaminopropane, o-tolylbiguanide, di[4-(1 ',3'-dimethyl- butyl)phenyl]amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and di- alkylated tert-butyl-/tert-octyl-diphenylamines, a mixture of mono- and di-alkylated non- yldiphenylamines, a mixture of mono- and di-alkylated dodecyldiphenylamines, a mixture of mono- and di-alkylated isopropyl-/isohexyl-diphenylamines, mixtures of mono- and di- alkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1 ,4-benzothiazines, phe- nothiazines, a mixture of mono- and di-alkylated tert-butyl-/tert-octyl-phenothiazines, a mixture of mono- and di-alkylated tert-octyl-phenothiazines, N-allylphenothiazines, N,N,N',N'-tetraphenyl-1 ,4-diaminobut-2-ene, N,N-bis(2,2,6,6-tetramethylpiperidin-4- yl)hexamethylenediamine, bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 2,2,6,6- tetramethylpiperidin-4-one and 2,2,6,6-tetramethylpiperidin-4-ol. 1.15 Polyphenols antioxidants, e.g. derivatives of p-cresol and dicyclopentadiene, e.g. ®WINGSTAY L (Goodyear), CAS-No. 68610-51-5.

2. UV Absorbers and light stabilisers

2.1 2-(2'-Hvdroxyphenyl)benzotriazoles, e.g. 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2- (3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphenyl)ben- zotriazole, 2-(2'-hydroxy-5'-(1 ,1 ,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert- butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-methyl- phenyl)-5-chlorobenzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl)benzotria- zole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxy- phenyl)benzotriazole, 2-(3',5'-bis(α,α-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, 2- (3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chlorobenzotriazole, 2-(3'- tert-butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chlorobenzotriazole, 2- (3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl- 2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethyl- hexyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'- methylphenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)- phenylbenzotriazole, 2,2'-methylene-bis[4-(1 ,1 ,3,3-tetramethylbutyl)-6-benzotriazol-2-yl- phenol]; the transesterification product of 2-[3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'- hydroxyphenyl]-2H-benzotriazole with polyethylene glycol 300; R- CH CH - COO - CH CH -U_> wherein R is 3'-tert-butyl-4'-hydroxy-5'-2H-benzotriazol-2-

2 2 2 2 I r₎ ylphenyl, 2-[2'-hydroxy-3'-(α,α-dimethylbenzyl)-5'-(1 ,1 ,3,3-tetramethylbutyl)phenyl]benzo- triazole; 2-[2'-hydroxy-3'-(1 ,1 ,3,3-tetramethylbutyl)-5'-(α,α-dimethylbenzyl)phenyl]benzo- triazole.

2.2 2-Hvdroxybenzophenones, e.g. the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4- dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy or 2'-hydroxy-4,4'-dimethoxy derivatives.

2.3 Benzoic acid esters, e.g. 4-tert-butylphenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoylresorcinol, bis(4-tert-butylbenzoyl)resorcinol, benzoylresorcinol, 2,4- di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-tert-butyl-4-hy- droxybenzoate, octadecyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butyl- phenyl-3,5-di-tert-butyl-4-hydroxybenzoate.

2.4 Acrylates, e.g. ethyl-α-cyano-β,β-diphenylacrylate or isooctyl-α-cyano-β,β-diphenylacry- late, methyl-α-carbomethoxycinnamate, methyl-α-cyano-β-methyl-p-methoxycinnamate or butyl-α-cyano-β-methyl-p-methoxycinnamate, methyl-α-carbomethoxy-p-methoxycin- namate and N-(α-carbomethoxy-β-cyanovinyl)-2-methylindoline. Z5 Nickel compounds, e.g. nickel complexes of 2,2'-thio-bis[4-(1 ,1 ,3,3-tetramethylbutyl)phe- nol], e.g. the 1 :1 or 1 :2 complex, optionally with further ligands, e.g. n-butylamine, trietha- nolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters, e.g. methyl or ethyl esters, 4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximines, e.g. 2-hydroxy-4-methylphenylundecylketoximes or nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, optionally with further ligands.

2.6 So-called sterically hindered amines, e.g. bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(2,2,6,6-tetramethylpiperidin-4-yl) succinate, bis(1 ,2,2,6,6-pentamethylpiperidin-4-yl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(1 ,2,2,6, 6-penta- methylpiperidyl)-n-butyl-3,5-di-tert-butyl-4-hydroxybenzyl malonate, the condensate of 1- hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the linear or cyclic condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4- tert-octylamino-2,6-dichloro-1 ,3,5-s-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotri- acetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1 ,2,3,4-butanetetraoate, 1 ,1 '-(1 ,2- ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1 ,2,2,6,6-pentamethylpiperidyl)-2-n-butyl- 2-(2-hydroxy-3,5-di-tert-butylbenzyl) malonate, 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triaza- spiro[4.5]decane-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate, bis(1- octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, the linear or cyclic condensate of N, N'- bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-morpholino-2,6-dichloro- 1 ,3,5-triazine, the condensate of 2-chloro-4,6-di(4-n-butylamino-2,2,6,6-tetramethyl- piperidyl)-1 ,3,5-triazine and 1 ,2-bis(3-aminopropylamino)ethane, the condensate of 2- chloro-4,6-di(4-n-butylamino-1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis(3- aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro-

[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione, 3-dodecyl-1-(1 ,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione, a mixture of 4-hexa- decyloxy- and 4-stearyloxy-2,2,6,6-tetramethylpiperidine, the condensate of N, N'- bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and 4-cyclohexylamino-2,6-di- chloro-1 ,3,5-triazine, the condensate of 1 ,2-bis(3-aminopropylamino)ethane and 2,4,6-tri- chloro-1 ,3,5-triazine and 4-butylamino-2,2,6,6-tetramethylpiperidine {CAS No. 136504- 96-6); N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimide, N-(1 ,2,2,6,6-pentame- thyl-4-piperidyl)-n-dodecylsuccinimide, 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4- oxospiro[4.5]decane, the reaction product of 7,7,9, θ-tetramethyl^-cycloundecyl-i-oxa- 3,8-diaza-4-oxospiro[4.5]decane and epichlorohydrin, 1 , 1-bis(1 , 2,2,6, 6-pentamethyl-4- piperidyloxycarbonyl)-2-(4-methoxyphenyl) ether, N,N'-bis-formyl-N,N'-bis(2,2,6,6-tetra- methyl-4-piperidyl)hexamethylenediamine, the diester of 4-methoxymethylenemalonic acid with 1 ,2,2,6,6-pentamethyl-4-hydroxypiperidine, poly[methylpropyl-3-oxy-4-(2, 2,6,6- tetramethyl-4-piperidyl)]siloxane, the reaction product of maleic anhydride/α-olefin co- polymer and 2,2,6,6-tetramethyl-4-aminopiperidine or 1 , 2,2,6, 6-pentamethyl-4-amino- piperidine.

2.7 Oxalamides, e.g. 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5,5'-di- tert-butyloxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butyloxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'-bis(3-dimethylaminopropyl)oxalamide, 2-ethoxy-5-tert-butyl-2'-ethyloxanilide and the mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butyloxanilide and mixtures of o- and p-meth- oxy- and o- and p-ethoxy-disubstituted oxanilides.

2.8 2-(2-Hydroxyphenyl)-1 ,3,5-triazines, e.g. 2, 4, 6-tris(2-hydroxy-4-octyloxyphenyl)-1 ,3,5- triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-(2,4- dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2,4-bis(2-hydroxy-4-propyl- oxyphenyl)-6-(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6- bis(4-methylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimeth- ylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)- 1 ,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-butoxypropyloxy)phenyl]-4,6-bis(2,4-dimethyl- phenyl)-1 ,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)-phenyl]-4,6-bis- (2,4-dimethylphenyl)-1 ,3,5-triazine, 2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hy- droxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-do- decyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazine, 2-(2-hydroxy-4- hexyloxy)phenyl-4,6-diphenyl-1 ,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-di- phenyl-1 ,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxy-propoxy)phenyl]-1 ,3,5- triazine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1 ,3,5-triazine, 2-{2-hydroxy-

4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1 ,3,5- triazine.

3. Metal deactivators, e.g. N,N'-diphenyloxalamide, N-salicylal-N'-salicyloylhydrazine, N, N'- bis(salicyloyl)hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)hydrazine, 3- salicyloylamino-1 ,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyl- dihydrazide, sebacoylbisphenyl hydrazide, N,N'-diacetyladipoyl dihydrazide, N, N'- bis(salicyloyl)oxalyl dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide.

4. Phosphites, phosphines and phosphonites, e.g. triphenyl phosphite, diphenyl alkylphos- phites, phenyl dialkylphosphites, trisnonylphenyl phosphite, trilauryl phosphite, trioctadecyl phosphite, trimethylphosphine, tri-n-butylphosphine, triphenylphosphine, distearylpentae- rythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol di- phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4- methylphenyl)pentaerythritol diphosphite, bisisodecyloxypentaerythritol diphosphite, bis- (2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl)- pentaerythritol diphosphite, tristearylsorbitan triphosphite, tetrakis(2,4-di-tert-butylphenyl)-

4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g]- 1 ,3,2-dioxaphosphocine, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g]-1 ,3,2-di- oxaphosphocine, bis(2,4-di-tert-butyl-6-methylphenyl)methyl phosphite, bis(2,4-di-tert-bu- tyl-6-methylphenyl)ethyl phosphite, 2,2',2"-nitrilo[triethyl-tris(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.

The following phosphites are especially preferred: tris(2,4-di-tert-butylphenyl) phosphite (lrgafos^®168, Ciba Specialty Chemicals), trisnonylphenyl phosphite and the phosphites having the structural formulae (a), (b), (c), (d), (e), (f) and (g):

O — CH₂CH(C₄H₉)CH₂CH₃ (d),

5. Hydroxylamines, e.g. N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine, N,N-dioctyl- hydroxylamine, N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine, N,N-dihexa- decylhydroxylamine, N,N-dioctadecylhydroxylamine, N-hexadecyl-N-octadecylhydroxyl- amine, N-heptadecyl-N-octadecylhydroxylamine, N,N-dialkylhydroxylamine from hydro- genated tallow fatty acid amines.

6. Nitrones, e.g. N-benzyl-α-phenylnitrone, N-ethyl-α-methylnitrone, N-octyl-α-heptylnitrone, N-lauryl-α-undecylnitrone, N-tetradecyl-α-tridecylnitrone, N-hexadecyl-α-pentadecylni- trone, N-octadecyl-α-heptadecylnitrone, N-hexadecyl-α-heptadecylnitrone, N-octadecyl-α- pentadecylnitrone, N-heptadecyl-α-heptadecylnitrone, N-octadecyl-α-hexadecylnitrone and nitrones from N,N-dialkylhydroxylamines of hydrogenated tallow fatty acid amines.

7. Thiosynergists, e.g. dilauryl- or distearyl-thiodipropionate.

8. Peroxide absorbers, e.g. esters of β-thiodipropionic acid, e.g. the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazoles, the zinc salt of 2-mercaptobenzimidazole, zinc dibutyl dithiocarbamate, dioctadecyl disulphide, pentaerythritol tetrakis(β-dodecylmercapto)propionate.

9. Polyamide stabilisers, e.g. the copper salts combined with iodides and/or phosphorus compounds and salts of divalent manganese.

10. Basic co-stabilisers, e.g. melamine, polyvinylpyrrolidone, dicyandiamide, triallylcyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal and alkaline earth metal salts of higher fatty acids, e.g. calcium stearate, zinc stearate, magnesium behenate or stearate, sodium ricinoleate, potassium palmitate, antimony or zinc pyrocatecholate.

1 1. Nucleating agents, e.g. inorganic fillers, e.g. talcum, metal oxides, e.g. titanium dioxide or magnesium oxide, phosphates, carbonates or sulphates, preferably of alkaline earth metals, organic acids, e.g. mono- or poly-carboxylic acids and their salts, e.g. 4-tert- butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or benzoate and also polymeric compounds, e.g. ionic copolymers (ionomers).

12. Benzofuranones and indolinones, e.g. according to U.S. 4,325,863; U.S. 4,338,244; U.S. 5, 175,312, U.S. 5,216,052; U.S. 5,252,643; DE-A-4 316 611; DE-A-4 316 622; DE-A-4 316 876; EP-A-O 589 839 or EP-A-O 591 102, or 3-[4-(2-acetoxyethoxy)phenyl]-

5,7-di-tert-butylbenzofuran-2-one, 5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]ben- zofuran-2-one, 3,3'-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one], 5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4-acetoxy-3,5-dimethylphenyl)- 5,7-di-tert-butylbenzofuran-2-one, 3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl- benzofuran-2-one, 3-(3,4-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one, 3-(2,3-di- methylphenyl)-5,7-di-tert-butylbenzofuran-2-one.

13. Further additives, e.g. plasticisers, lubricants, emulsifiers, pigments, flow agents, catalysts, fluorescent whiteners, antistatic agents or blowing agents. According to a preferred embodiment, the invention relates to process, which comprises preparing a concentrated fluid of at least one phenolic antioxidant (I) selected from the group consisting of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate] and N,N'-hexane-1 ,6-diyl-bis-[3(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)].

According to a further preferred embodiment, the invention comprises preparing a concen- trated fluid mixture of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate with at least one phenolic antioxidant (I) selected from the group consisting of pentaerythritol-tetrakis[3- (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and N,N'-hexane-1 ,6-diyl-bis-[3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide)].

According to a particularly preferred embodiment, the invention relates to a process, which comprises preparing a concentrated fluid of at least one phenolic antioxidant (I) admixed with other phenolic additives, phosphorus containing additives selected from the group consisting of phosphines, phosphites and phosphonites, calcium stearate or blends thereof.

According to a highly preferred embodiment, the invention relates to a process, which comprises preparing a fluid of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphen- yl)-propionate] admixed with tris(2,4-di-tert-butylphenyl)phosphite, particularly in a weight ratio of 90:10 to 10:90, preferably 70: 30 to 30:70.

According to an optional step, even distribution of components in the concentrated fluid is obtained by conventional mixing methods, such as the ones known for preparing emulsions. Mixing can be effected by vigorous shaking using a dispersing machine, for example a Vor- tex mixer, or using dispersing machines of the ^®POLYTRON type (Kinematica AG, Littau

Switzerland) or dispersing machines produced by IKA (Staufen Germany), a static mixer and conventional stirring machines having a propeller or paddle blade or using a magnetic stirrer or phase mixer.

In order to obtain an especially homogeneous mixture, stirring is carried out at high speed, for example using Y-beam agitators (^®Y-Strahl, ^®Ultraturrax) or stirring machines produced by Polytron, for example Polytron PT 3000 or DH 30/30 or using a rotor/stator mixer, obtainable, for example from Greerco. According to a preferred embodiment of the process, the concentrated fluid of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives is prepared by heating solid particles, emulsions, suspensions, melts or melt solutions to temperatures between 50⁰C and 220⁰C, particularly 100°C to 190⁰C, to give a melt which may be directly added to the polymer to be stabilised.

The time period needed for heating may vary within wide limits between min and hours, depending on the amount (laboratory scale, pilot scale or production scale) of the concentrated fluid produced. The minimum time period appears to be the beginning formation of a fluid melt phase. The maximum time period is the complete conversion to a fluid melt phase. According to a preferred embodiment, the melt may be obtained directly from the preceding process, such as the one described in WO 2004/048312, for the preparation of the compound (I). IRGANOX 1010 is obtained without the presence of a solvent by catalytic trans- esterification of methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate with pentaerythritol and subsequent distillation of the melt in the vacuum at elevated temperatures. According to a preferred embodiment, the process further comprises cooling, dosing in suitable containers and storing the fluid under the exclusion of oxygen and light, remelting and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

The cooling step is particularly carried out gradually by allowing the fluid to cool to room tem- perature. According to a preferred embodiment, the fluid is cooled step-wise, e.g. by keeping the melt at elevated temperatures, for example from 50 - 160°C, preferably 60 - 110°C, and most preferably 80 - 1 10⁰C, which maintains a sufficiently high viscosity of the fluid to prevent phase separation. In a subsequent step, the fluid may be cooled to room temperature. Cooling may be applied in regular devices, such as heat exchangers or jacket cooling. The process according to the invention allows for long term storage without conditioning and for a recovery of the phenolic antioxidants in bulk containers as a melt which is directly applied to the polymer material.

A further embodiment of the invention relates to the process for preparing concentrated fluid of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives, which comprises preparing a melt phase by heating a compound of the formula:

Wherein one of R-T and R₂' independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and y represents a numeral from 2 - 6; or a concentrated fluid mixture thereof with other polymer additives; cooling and storing the melt phase under the exclusion of oxygen and light; and optionally remelting the solidified melt phase under the optional addition of further polymer additives. The concentrated fluid obtained by this method, particularly a melt, can be directly stored without undesirable effects such as discolouration and other losses of product quality. Furthermore, the concentrated fluid can further processed thermally to allow the liquid dosing to polymer streams, which reduces significantly handling problems and simplifies the supply chain.

According to a preferred embodiment, the invention relates to a process, which comprises preparing a concentrated fluid of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphen- yl)-propionate].

The invention also relates to the use of a concentrated fluid of phenolic antioxidants or mix- tures of phenolic antioxidants with other polymer additives for stabilizing polymers, particularly a concentrated fluid of pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propi- onate or pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate admixed with tris(2,4-di-tert-butylphenyl)phosphite.

Examples of polymer materials to be stabilised are:

1. Polymers of monoolefins and diolefins, for example polypropylene, polyisobutylene, poly- but-1-ene, poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well as polymers of cycloolefins, for example of cyclopentene, norbornene or dicyclopentadiene; furthermore polyethylene (which optionally can be crosslinked), for example high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE).

Polyolefins, i.e. polymers of monoolefins exemplified in the preceding paragraph, in particular polyethylene and polypropylene, can be prepared by different, and especially by the following, methods:

a) Radical polymerisation (normally under high pressure and at elevated temperature)

b) Catalytic polymerisation using a catalyst that normally contains one or more metals of group IVb, Vb, VIb or VIII of the Periodic Table. These metals usually have one or more ligands, such as oxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenyls and/or aryls that may be either π- or σ-coordinated. These metal complexes may be in the free form or fixed on substrates, for example on activated magnesium chloride, titanium(lll) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be active as such in the polymerisation or further activators may be used, for example metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, the metals being elements of groups Ia, Na and/or Ilia of the Periodic Table. The activators may be modified, for example, with further ester, ether, amine or silyl ether groups. These catalyst systems are usually termed Phillips, Standard Oil Indiana, Ziegler (Natta), TNZ (DuPont), metallocene or single site catalysts (SSC).

2. Mixtures of the polymers mentioned under 1 ), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE).

3. Copolymers of monoolefins and diolefins with each other or with other vinyl monomers, for example ethylene-propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene-but-1-ene copolymers, propylene-isobutylene copolymers, ethylene-but-1-ene copolymers, ethylene-hexene co- polymers, ethylene-methylpentene copolymers, ethylene-heptene copolymers, ethylene- octene copolymers, propylene-butadiene copolymers, isobutylene-isoprene copolymers, ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, ethylene-vi- nyl acetate copolymers and their copolymers with carbon monoxide or ethylene-acrylic acid copolymers and their salts (ionomers) as well as terpolymers of ethylene with pro- pylene and a diene such as hexadiene, dicyclopentadiene or ethylidene-norbornene; and mixtures of such copolymers with one another and with polymers mentioned under 1 ), for example polypropylene-ethylene-propylene copolymers, LDPE-ethylene-vinyl acetate copolymers, LDPE-ethylene-acrylic acid copolymers, LLDPE-ethylene-vinyl acetate copolymers, LLDPE-ethylene-acrylic acid copolymers and alternating or random polyal- kylene-carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides.

4. Hydrocarbon resins (for example C₅-C₉) including hydrogenated modifications thereof (e.g. tackifier resins) and mixtures of polyalkylenes and starch.

5. Polystyrene, poly(p-methylstyrene), poly(alpha-methylstyrene). 6. Copolymers of styrene or alpha-methylstyrene with dienes or acrylic derivatives, for example styrene-butadiene, styrene-acrylonitrile, styrene-alkyl methacrylate, styrene-bu- tadiene-alkyl acrylate, styrene-butadiene-alkyl methacrylate, styrene-maleic anhydride, styrene-acrylonitrile-methyl acrylate; mixtures of high impact strength of styrene copolymers and another polymer, for example a polyacrylate, a diene polymer or an ethylene- propylene-diene terpolymer; and block copolymers of styrene such as styrene-butadiene- styrene (SBS), styrene-isoprene-styrene, styrene-ethylene-butylene-styrene or styrene- ethylene-propylene-styrene.

7. Graft copolymers of styrene or alpha-methylstyrene, for example styrene on polybutadi- ene, styrene on polybutadiene-styrene or polybutadiene-acrylonitrile copolymers, styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl methacrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; styrene and maleimide on polybutadiene, styrene and alkyl acrylates or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene-propylene-diene terpolymers, styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acry- late-butadiene copolymers, as well as mixtures thereof with the copolymers mentioned under 6), for example the copolymer mixtures known as ABS, MBS, ASA or AES polymers. 8. Halogen-containing polymers such as polychloroprene, chlorinated rubber, chlorinated or sulphochlorinated polyethylene, copolymers of ethylene and chlorinated ethylene, epichlorohydrine homo- and copolymers, especially polymers of halogen-containing vinyl compounds, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride; as well as copolymers thereof such as vinyl chloride-vinylidene chloride, vinyl chloride-vinyl acetate or vinylidene chloride-vinyl acetate.

9. Polymers derived from a,b-unsaturated acids and derivatives thereof such as polyacry- lates and polymethacrylates, polymethyl methacrylates, polyacrylamides and polyacry- lonitriles, impact-modified with butyl acrylate.

10. Copolymers of the monomers mentioned under 9) with each other or with other unsatu- rated monomers, for example acrylonitrile-butadiene copolymers, acrylonitrile-alkyl acrylate copolymers, acrylonitrile-alkoxyalkyl acrylate copolymers, acrylonitrile-vinyl halide copolymers or acrylonitrile-alkyl methacrylate-butadiene terpolymers.

1 1. Polymers derived from unsaturated alcohols and amines or the acyl derivatives or acetals thereof, such as polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzo- ate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate or polyallylmelamine; as well as their copolymers with olefins mentioned in paragraph 1.

12. Homopolymers and copolymers of cyclic ethers such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers. 13. Polyacetals such as polyoxymethylene and those polyoxymethylenes that contain co- monomers, for example ethylene oxide; polyacetals modified with thermoplastic polyure- thanes, acrylates or MBS.

14. Polyphenylene oxides and sulphides, and mixtures thereof with styrene polymers or poly- amides.

15. Polyurethanes derived from hydroxyl-terminated polyethers, polyesters and polybutadie- nes on the one hand and aliphatic or aromatic polyisocyanates on the other, as well as precursors thereof.

16. Polyamides and co polyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, 6, 6/6, 6/10,

6/9, 6/12, 4/6, 12/12,1 1 and 12, aromatic polyamides starting from m-xylene, diamine and adipic acid; polyamides prepared from hexamethylenediamine and isophthalic and/or terephthalic acid and with or without an elastomer as modifier, for example poly-2,4,4- trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide. Block co- polymers of the aforementioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, e.g. with polyethylene glycol, polypropylene glycol or polytetramethylene glycol. As well as polyamides or co- polyamides modified with EPDM or ABS; and polyamides condensed during processing (RIM polyamide systems). 17. Polyureas, polyimides, polyamide-imides and polybenzimidazoles.

18. Polyesters derived from dicarboxylic acids and dialcohols and/or from hydroxycarboxylic acids or the corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly-1 ,4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates, as well as block polyether esters derived from hydroxyl-terminated polyethers; and also polyesters modified with polycarbonates or MBS.

19. Polycarbonates and polyester carbonates.

20. Polysulphones, polyether sulphones and polyether ketones.

21. Crosslinked polymers derived from aldehydes on the one hand and phenols, urea or melamine on the other hand, such as phenol/formaldehyde resins, urea/formaldehyde resins and melamine/formaldehyde resins.

22. Drying and non-drying alkyd resins. 23. Unsaturated polyester resins derived from co polyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols and vinyl compounds as cross-linking agents, and also halogen-containing modifications thereof of low flammability.

24. Crosslinkable acrylic resins derived from substituted acrylates, for example from epoxy acrylates, urethane acrylates or polyester acrylates.

25. Alkyd resins, polyester resins and acrylate resins crosslinked with melamine resins, urea resins, polyisocyanates or epoxy resins.

26. Crosslinked epoxy resins derived from polyepoxides, for example from bisglycidyl ethers, or cycloaliphatic diepoxides. 27. Natural polymers such as cellulose, natural rubber, gelatin and derivatives thereof which have been chemically modified in a polymer-homologous manner, for example cellulose acetates, cellulose propionates and cellulose butyrates, or the cellulose ethers such as methylcellulose; and also rosins and derivatives.

28. Blends (polyblends) of the aforementioned polymers, for example PP/EPDM, polyam- ide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA,

PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP or PA/PPO.

29. Aqueous emulsions of natural or synthetic rubbers, for example natural rubber latex or lattices of carboxylated styrene-butadiene copolymers.

30. Natural and synthetic organic substances which are pure monomeric compounds or mixtures thereof, for example mineral oils, animal or vegetable fats, oils and waxes, or oils, waxes and fats based on synthetic esters (e.g. phthalates, adipates, phosphates or trimellitates), and also blends of synthetic esters with mineral oils in any desired propor- tions by weight, as are employed, for example, as spin finishes, and also the aqueous emulsions thereof.

The concentrated fluid is particularly suitable for stabilising polymers, specifically styrene (co) polymers, such as polystyrene, ABS (acrylonitrile-butadiene-styrene), IPS (impact polystyrene, graft copolymer of styrene on polybutadiene), MBS (methacrylonitrile-butadiene-sty- rene) and SBS (styrene-butadiene-styrene). In this context, they act in particular as antioxidants.

According to a preferred embodiment, the invention relates to process, which comprises adding the phenolic antioxidants or mixtures of phenolic antioxidants with other polymer ad- ditives in the form of a fluid to the polymer selected from the group consisting of polyolefins, polyesters, polystyrenes, polyacrylates, polyurethanes, polyamides and polycarbonates.

The incorporation into the polymer materials can be carried out, for example, by mixing in the concentrated fluid, particularly a melt fluid, and, if desired, further additives in accordance with known methods. The incorporation into the polymeric material may take place prior to or during the shaping operation or by applying the concentrated fluid to the polymer, with or without subsequent evaporation of a solvent. In the case of elastomers, these can also be stabilised as lattices. The invention therefore relates in particular to compositions, wherein the concentrated fluid defined above is incorporated into and/or chemically linked with an elastomer/ polymer.

The concentrated fluid can also be added in the form of a master batch, which contains the individual components defined above in a concentration, for example, of from 1.0 - 40%, preferably 2.5 to 25.0%, by weight, to the polymer material which is to be stabilised.

The concentrated fluid defined above can expediently be incorporated into polymers as fol- lows:

• As an emulsion or dispersion (e.g. to lattices or emulsion polymers);

• As a mix during the mixing in of additional components or polymer mixtures;

• By direct addition as a melt to the processing apparatus (e.g. extruder, internal mixer, etc.). Further additives customarily present in polymer compositions:

Such additives can be added in small amounts, e.g. UV absorbers or light stabilisers, for example from the series of hydroxyphenylbenzotriazoles, hydroxyphenylbenzophenones, ox- alamides and hydroxyphenyl-s-triazines. Especially suitable are light stabilisers from the group of so-called sterically hindered amines (HALS), e.g. the 2-(2-hydroxyphenyl)-1 ,3,5-tri- azine or 2-hydroxyphenyl-2H-benzotriazole types. Examples of light stabilisers of the 2-(2- hydroxyphenyl)-1 ,3,5-triazine type are known from the patent literature, e.g. US-A-4 619 956, EP-A-434 608, US-A-5 198 498, US-A-5 322 868, US-A-5 369 140, US-A-5 298 067, WO- 94/18278, EP-A-704 437, GB-A-2 297 091 or WO-96/28431.

The polymers to be stabilized by the process defined above may comprise additional addi- tives, too, for example thickeners, fillers, e.g. calcium carbonate, silicates, glass or glass fibre material, talcum, kaolin, mica, barium sulphate, metal oxides and hydroxides, carbon black, graphite, powdered wood and powdered or fibrous material of other natural products, synthetic fibres, plasticisers, lubricants, emulsifiers, pigments, flow auxiliaries, catalysts, optical brighteners, flame-retardants, antistatics and blowing agents.

These polymer compositions can be used for a very wide variety of technical applications, for example as adhesives, detergent adjuvants, detergents, dispersants, emulsifiers, surfactants, antifoams, tackifiers, corrosion inhibitors, viscosity improvers, lubricants, flow improvers, thickeners, cross linking agents, as additives for water treatment, electronic materials, paints and lacquers, coatings, inks, photo developers, super absorbents, cosmetics, preservatives, or as biocides or modifiers and adjuvants for asphalt, textiles, ceramics and wood.

The polymer compositions can be employed in various forms and processed to give various products, for example as or to films, fibres, tapes, moulding compounds or profiles, or as binders for coating materials, adhesives or putties.

The following Examples illustrate the invention: Examples

Example 1 : Preparation of a pure IRGANOX 1010 fluid (Pilot Scale)

Charge a double jacketed, stirred reactor (afterwards called melt buffer) with 1000 kg of IRGANOX 1010 powder. Apply vacuum of 10 mbar. Break the vacuum with nitrogen. Repeat operation twice. Apply vacuum of 10 mbar and heat double jacket with steam 6 bar (158.9°C). Wait until enough powder melts (8-10 h) and switch on stirrer to 100 rpm (rotations per minute). Wait until the powder has completely melted (additional 3-4 h).

Prepare a mobile, heatable, vacuum resistant, opaque 1000 I container. Apply vacuum of 10 mbar. Break the vacuum with nitrogen. Repeat operation twice. Set a control valve to release pressure in the container at a gage pressure of 15 mbar. Align the melt buffer containing IRGANOX 1010 with a mobile container with traced lines through a shell and tube heat exchanger (exchange surface: 1 m²; cooling media water inlet 60⁰C). Activate line tracing (heat double jacket of pipes) with steam of 3 bar (133.5°C). When a stable temperature is reached in the lines, transfer within 30 min to the container 1 m³ of the IRGANOX 1010 melt. The melt is cooled to 137.5°C during the transfer (viscosity: 0.19 Pas).

Switch on cooling on the container jacket (cooling water 20⁰C) until temperature in the core of the container drops below 130⁰C (24 h). Keep constant elevated pressure of 15 mbar of nitrogen in the container. Then switch off cooling water, seal container. The container is stored sealed but without any conditioning.

After 10 days of storage, connect nitrogen to the container and activate the control valve to keep an elevated pressure of 20 mbar of nitrogen in the container. The content of the container is solidified. The container is heated with steam at 3 bar (133.5°C). The heating is continued for 3 days. At this point, the content of the container is liquid and has a viscosity of 0.397 Pas. It can be pumped with a gear pump and dosed as a liquid in an extruder.

A liquid sample has been taken and showing that the product is still within product specifications:

Initial (in melt buffer) Final (liquid pumped from container)

IRGANOX 1010 content: 94. 6 % 94 .6%

Transmission 425 nm: 98. 1 % 96 .8%

It has been shown that the same experimental trial when storing for 27 days and subsequent heating for more than 10 days did leave the product within specifications: Initial (in melt buffer) Final (liquid pumping from container)

IRGANOX 1010 content: 94.6% 94.9%

Transmission 425 nm: 98.1 % 96.5%

Example 2: IRGANOX 1010 and IRGAFOS 168 mixture 2.1 Preparation of IRGANOX 1010 melt 1896 g (6.5 mol) of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester, 170 g (1.25 mol) pentaerythritol and 4 g sodium acetate are mixed and heated to 120⁰C in nitrogen atmosphere. When the mixture starts melting, stirring is switched on. After completing the melt preparation, the reactor is slowly evacuated and heated at the same time to an internal temperature of 160-170⁰C. Methanol is produced by the reaction and is distilled off, and re- covered in a cold trap. As soon as a vacuum lower than 10 mbar is reached, the temperature is increased to 180⁰C and evacuation continues until a pressure of less than 1 mbar is reached. When 1 mbar and 180°C are reached, the conditions are kept constant under stirring during 1 h. The temperature is increased to 200-210⁰C, and the excess of beta-(3,5-di- tert-butyl-4-hydroxyphenyl)propionic acid methyl ester is distilled off. The reaction mass comprises now less than 0.2% of beta-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester and contains a concentration higher than 96% in tetrakis-[beta-(3,5-di-tertbutyl- 4-hydroxyphenyl)-propionyloxy-methyl]methane. The vacuum is broken with nitrogen. The colourless reaction melt is filtered, and stored at 160⁰C in an opaque, double-jacketed buffer.

2.2 Preparation of the fluid phase

Fill a double-jacketed glass reactor with 600 g of IRGAFOS 168 powder. Evacuate to 10 mbar. Break the vacuum with argon. Repeat operation three times. Transfer 1400 g of IRGANOX 1010 melt from the melt-buffer in the glass reactor. Evacuate reactor to 10 mbar. Set double-jacket oil temperature to 185°C. Switch on stirrer to 150 rpm. Break the vacuum with argon and evacuate to 10 mbar every 30 min. When the full amount of IRGAFOS 168 is dissolved in the IRGANOX 1010 (internal temperature: 165°C), the temperature of the double jacket is adjusted to 175°C to keep the content of the reactor at 168°C.

Prepare a mobile, heatable, vacuum resistant, opaque 2 I container. Apply vacuum of 10 mbar. Break the vacuum with nitrogen. Repeat operation twice. Set a control valve to release pressure in the container at elevated pressure higher than 15 mbar.

Align the container with the reactor with double-jacketed lines. Activate line tracing (heat double jacket of pipes) with hot oil at 170⁰C. Stop the stirrer in the reactor. Transfer quickly the content of the reactor to the opaque container.

Keep constant elevated pressure of 15 mbar of nitrogen in the container; cool the container with cooled oil (-15⁰C) in the bottom and side jackets, control the temperature in the reactor (half of the height of liquid, half of the distance between the jacket and the core) to have a cooling ramp of 50°C per hour. When the temperature reaches 80⁰C (after about 100 min), switch off the cooling oil and let the container cool to room temperature by itself. When a temperature below 45°C is reached in the center (about 6 h), seal the container. The container is stored sealed but without any conditioning.

After 10 days of storage, connect nitrogen to the container and activate the control valve to keep an elevated pressure of 20 mbar of nitrogen in the container. The content of the container is solidified. Prepare a double-jacketed glass reactor. Apply vacuum of 10 mbar. Break the vacuum with argon. Repeat operation three times. Preheat the reactor jacket to 170°C.

The container is heated with hot oil at 200⁰C in the bottom jacket. Set an oil temperature of 50⁰C on the side jackets. Connect the bottom exit of the container to the glass reactor with double-jacketed lines heated at 170°C. Increase the pressure in the container to 1.5 bar with nitrogen. As the product melts at the bottom of the container, it flows slowly in the glass reactor (viscosity is 0.12 Pas). The glass reactor contains an evenly distributed melt (solution is clear) ready for dosing to an extruder. Analytics show a proportion IRGANOX 1010/IRGAFOS 168 within detection limits of the initial mixture in three samples taken during the transfer of the melt from the container to the glass reactor. The following product specifications are met: Clear solution

Transmission 425 nm: >95% Transmission 500 nm: >97% Content IRGANOX 1010: 67.5% - 72.5% Content IRGAFOS 168: 27.5% - 32.5%

Cross contamination: <1%

Example 3: IRGANOX 1010 and IRGAFOS 168 suspension Prepare an IRGANOX 1010 melt according to Example 2.1.

Preheat the jacket of a glass reactor to 130⁰C. Transfer 1400 g of IRGANOX 1010 melt from the melt-buffer in the glass reactor.

Weigh 600 g of IRGAFOS 168 powder in a hopper. Evacuate the hopper to 10 mbar. Break the vacuum with argon and repeat operation three times. Preheat the IRGAFOS to 130⁰C by blowing hot air on the hopper. Attach hopper to the glass reactor. Switch on agitation of the glass reactor at 250 rpm. Add the IRGAFOS 168 powder slowly to the reactor (about 50 g/min). Evacuate reactor to 10 mbar. Break the vacuum with argon. Repeat operation three times. Evacuate reactor to 10 mbar. Keep stirring in the reactor until the IRGAFOS powder is in suspension in the IRGANOX 1010 (2 h). Break the vacuum with argon and evacuate to 10 mbar every 30 min.

Prepare a mobile, double-jacketed, vacuum resistant, opaque 2 I container. Evacuate to 10 mbar. Break the vacuum with nitrogen. Repeat operation twice to lower the oxygen concentration in the container. Set a control valve to release pressure in the container at elevated pressure higher than 15 mbar.

Align the container with the reactor with double-jacketed lines. Activate line tracing (heat double jacket of pipes) with oil at 130°C. While stirring, transfer quickly the content of the reactor to the opaque container. Keep constant elevated pressure of 15 mbar of nitrogen in the container; cool the container with cooled oil in the jacket, control the temperature in the container (half of the height of liquid, half of the distance between the jacket and the core) to have a cooling ramp of 50⁰C per hour by adapting the cooled oil inlet temperature. When the temperature has reached 80⁰C (after about 60 min), switch off the cooling oil and let the container cool to room temperature by it- self. When a temperature below 45°C is reached in the center of the container (after about 6 h), seal the container. The container is stored sealed but without any conditioning.

After 10 days of storage, connect nitrogen to the container and activate the control valve to maintain an elevated pressure of 20 mbar of nitrogen in the container. The content of the container is solidified as a solid milky mass. Prepare a double-jacketed glass reactor. Apply vacuum of 10 mbar. Break the vacuum with argon. Repeat operation three times. Preheat the reactor jacket to 130⁰C.

The container is heated with hot oil at 200⁰C in the bottom jacket. Set an oil temperature of 50°C on the side jackets. Connect the bottom exit of the container to the glass reactor with double jacketed lines heated at 130⁰C. Increase the pressure in the container to 1.5 bar with nitrogen. As the product melts at the bottom of the container, it flows slowly in the glass reactor (viscosity is 0.12 Pas). The glass reactor contains an evenly distributed suspension ready for dosing to an extruder.

Example 4: IRGANOX 1010 and IRGAFOS 168 mixture with concentration adjustment

Prepare and restore a melt mixture according to Example 2. Heat the receiver glass reactor double jacket to 185°C. Weigh 333 g of IRGAFOS 168 powder in a hopper. Evacuate the hopper to 10 mbar. Break the vacuum with argon and repeat operation three times. Preheat the IRGAFOS to 150⁰C by blowing hot air on the hopper. Attach hopper to the glass reactor. Switch on agitation of the glass reactor at 250 rpm.

Add the IRGAFOS 168 powder slowly to the reactor (about 20 g/min). Evacuate reactor to 10 mbar. Break the vacuum with argon. Repeat operation three times. Evacuate reactor to 10 mbar. Keep stirring in the reactor until the IRGAFOS powder is completely dissolved. The reactor contains a transparent liquid mixture of 40% IRGAFOS 168 and 60% IRGANOX 1010, ready for liquid dosing in an extruder.

Claims

1. A process for stabilizing polymers by addition of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives, which comprises preparing a concentrated fluid of

At least one compound of the formula:

2. A process according to claim 1 , which comprises preparing a concentrated fluid of at least one phenolic antioxidant (I) selected from the group consisting of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate] and N,N'-hexane-1 ,6-diyl-bis-[3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide)].

3. A process according to claim 1 , which comprises preparing a fluid of at least one phenolic antioxidant (I) admixed with further additives selected from the group consisting of antioxidants selected from the group consisting of alkylated monophenols, alkylthiomethyl- phenols, hydroquinones and alkylated hydroquinones, tocopherols, hydroxylated thiodi- phenyl ethers, alkylidene-bis-phenols, O-, N- and S-benzyl compounds, hydroxybenzy- lated malonates, aromatic hydroxybenzyl compounds, triazine compounds, benzylphos- phonates, acylaminophenols, esters and amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)- propionic acid, β-(3,5-di-t-butyl-4-hydroxy-3-methylphenyl)propionic acid, or β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid, ascorbic acid, aminic antioxidants, light stabilisers, phosphites, phosphines, phosponites, hydroxylamines, nitrones, thiosyn- ergists, peroxide scavengers, polyamide stabilisers, basic co-stabilisers, nucleating agents, fillers and reinforcing agents, plasticisers, lubricants, emulsifiers, pigments, rheological additives, levelling assistants, optical brighteners, flame proofing agents, antistatic agents, blowing agents, benzofuranones and indolinones.

4. A process according to claim 1 , which comprises preparing a fluid of at least one phenolic antioxidant (I) admixed with other phenolic additives, phosphorus containing additives selected from the group consisting of phosphines, phosphites and phosphonites, calcium stearate or blends thereof.

5. A process according to claim 1 , which comprises preparing a fluid of pentaerythritol- tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate admixed with tris(2,4- di-tert-butylphenyl)phosphite.

6. A process according to claim 5, which comprises preparing a fluid of pentaerythritol- tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate admixed with tris(2,4- di-tert-butylphenyl)phosphite in a weight ratio of 90:10 to 10:90.

7. A process according to claim 1 , which comprises adding the phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives in the form of a fluid to the polymer selected from the group consisting of polyolefins, polyesters, polystyrenes, poly- acrylates, polyurethanes, polyamides and polycarbonates.

8. A process according to claim 1 , which comprises cooling, dosing in suitable containers and storing the fluid under the exclusion of oxygen and light, remelting and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

9. A process for preparing a concentrated fluid of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives, which comprises preparing a melt phase by heating a compound of the formula:

Wherein one of Ri' and R₂' independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and y represents a numeral from 2 - 6; or a concentrated fluid mixture thereof with other polymer additives; cooling and storing the melt phase under the exclusion of oxygen and light; and optionally remelting the solidified melt phase under the optional addition of further polymer additives.

10. The use of a concentrated fluid of phenolic antioxidants or mixtures of phenolic antioxidants with other polymer additives for stabilizing polymers.

1 1. The use according to claim 10 of a concentrated fluid of pentaerythritol-tetrakis[3- (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate for stabilizing polymers.

12. The use according to claim 10 of a concentrated fluid of pentaerythritol-tetrakis[3- (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate admixed with tris(2,4- di-tert-butylphenyl)phosphite for stabilizing thermoplastic polymers.

13. A process for stabilizing polymers by addition of a mixture of phenolic antioxidants, which comprises preparing a concentrated fluid mixture of

At least one compound of the formula:

Wherein one of Ri and R₂ independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and R₃ represents C₈-C₂₂alkyl; And at least one compound (I),

Wherein one of R-T and R₂' independently of one another represents hydrogen or Ci-C₄alkyl and the other one represents C₃-C₄alkyl; x represents zero (direct bond) or a numeral from 1 - 3; and y represents a numeral from 2 - 6; and or a concentrated fluid mixture thereof with other polymer additives; cooling and storing the fluid under the exclusion of oxygen and light; optionally remelting the solidified fluid; and adding the fluid under the optional addition of further polymer additives to the polymer to be stabilized.

14. A process according to claim 13, which comprises preparing a concentrated fluid mixture of at least one phenolic antioxidant (I) selected from the group consisting of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate with at least one phenolic antioxidant (I) selected from the group consisting of pentaerythritol-tetrakis[3-(3,5-di-tert-bu- tyl-4-hydroxyphenyl)-propionate and N,N'-hexane-1 ,6-diyl-bis-[3(3,5-di-tert-butyl- 4-hydroxyphenylpropionamide)].