Process for decolorization of light stabilizers

Abstract

The present invention relates to a process for decolorization of light stabilizer comprising: a) obtaining at least one light stabilizer of formula (A) or formula (B) wherein Ar 1, Ar 2, Ar 3 R 1, R 2, R 3 and R 4 are defined in the description; b) treating the light stabilizer of formula (A) or (B) with at least one radical initiator selected from azo radical initiators and peroxide radical initiators.

Description

[0001] Process For Decolorization of Light Stabilizers

[0002] Description

[0003] The present invention relates to a process for decolorization of light stabilizer and use thereof.

[0004] Prior Art

[0005] Ultraviolet (UV) light absorbers are an important class of organic compounds which have a wide variety of applications. One of the most important areas of application is the protection and stabilization of organic materials such as plastics, polymers and coating materials against damages by light, heat, oxygen, or environmental forces. Such stabilizers are also widely used in personal care, fibers, paints, dyes among others.

[0006] The two major types of light stabilizer for UV stabilizer applications are substituted benzotriazoles (BTZs) and substituted triazines, such as hydroxy phenyl triazines (HPTs). Unavoidably, known synthetic routes for obtaining said stabilizers are noted to result in the presence of trace amounts of colored by-products. For instance, in US 6369267 several substituted HPTs as well as substituted BTZs were reported in the form of highly colored resins or oils. As a result, especially for coating applications where the presence of white or colorless ingredients are critical, it is common practice in the art, to have an additional processing step of decolorization.

[0007] CN102060794A discloses a method for refining a crude benzotriazole ultraviolet absorber, which comprises the steps of: dissolving the crude benzotriazole ultraviolet absorber in a 1 .8- 3.6 mL / g crude weak polar or non-polar solvent; after dissolving, adding 0.025-0.045g / g crude active carbon, attapulgite or a blend of the crude active carbon and the attapulgite, carrying out decoloring treatment through refluxing, removing the weak polar or non-polar solvent after decoloring, adding a 2.3-3.5 mL / g crude alcohol solvent, heating to refluxing and then cooling to 10-30 °C to separate out crystal, and filtering and drying to obtain the high-purity and high-light-transmittance benzotriazole ultraviolet absorber.

[0008] CN101274971 A relates to a fire-retardant type acoustic celotex board, which includes a panel main part and a plastics bearing structure, which characterized in that, the panel main part is formed by fire-retardant type polymeric material preparation and the fire-retardant type polymeric material's constitution and component ratio are: methyl methacrylate monomer 69.953-95.97%

[0009] 3 to 30 percent of fire retardant

[0010] 0.07-0.3 per mill of initiator, such as, for example, benzoyl peroxide, azobisisobutyronitrile, or azobisisoheptonitrile.

[0011] 0.2-5 per mill of ultraviolet absorbent, such as, for example, -(2'-hydroxy-5' -methylphenyl) benzotriazole, 2- (2 '-hydroxy-5' -tert-octylphenyl) benzotriazole or 2-hydroxy-4-n- octyloxybenzophenone,

[0012] 0.2-5 per mill of hindered amine light stabilizer The above proportions are in weight percent.

[0013] CN105037178B relates to a composite antioxidant composition for preventing discoloration of aromatic amine which is characterized in that: the composite antioxidant composition comprises, by weight, 10-60% of an oxygen scavenger, 10-60% of a free radical trapping antioxidant, 10-60% of a peroxide decomposition antioxidant, i.e. an agent which reduces the amount of peroxides, and 10-30% of a light stabilizer; the hydroxylamine oxygen scavenger is N, N-diethylhydroxylamine or N-isopropylhydroxylamine; the free radical capture type antioxidant is 2, 6-di-tert-butyl-4-methylphenol or 2, 4-dimethyl-6-tert-butylphenol; the peroxide decomposition type antioxidant is sodium N, N-dialkyl dithiocarbamate; the light stabilizer is phenyl salicylate, 2-hydroxy-4-n-octoxybenzophenone or 2- (2 '-hydroxy-5' - methylphenyl) benzotriazole.

[0014] KR101689535B1 relates to the preparation of a polymer compound, which is obtained by curing a mixture, comprising 2,2-bis-(4-(3-methacryloxy-2-hydroxypropoxy) phenylpropane (Bis-GMA), triethylene glycoldimethacrylate (tegdma), and trimethylolpropane triacrylate (TMPTA), barium aluminosilicate, 3-(methacryloyloxy) propyltrimethoxysilane and benzoyl peroxide as polymerization initiator and 2-(2H-benzotriazol-2 yl)-p-cresol as anti-tarnish agent at a temperature of 50 °C to 100 °C for 5 minutes to 150 minutes.

[0015] JP2017177481 A relates to a graphic film for a license plate, comprising a polyurethane surface-protecting layer to which a printing layer is applied, wherein the polyurethane surface-protecting layer comprises: a license plate graphic film comprising: a reactant of a polyol having at least one of a polyester backbone and a polycarbonate backbone, and a polyfunctional aliphatic isocyanate; or an aqueous polyurethane.

[0016] CN117510473A relates to a method for decoloring a polymeric light stabilizer, in particular hindered amine light stabilizer, characterized in that the decoloring method comprises the following steps:

[0017] (1 ) in a batching kettle, contacting and mixing organic solvent, polymeric light stabilizer or solid products of composite particles thereof to obtain solution containing solid products for standby;

[0018] (2) the solution containing the dull product obtained in the step (1 ) enters a hydrogenation reactor filled with a catalyst, and hydrogenation reaction is carried out under the action of the catalyst; after the reaction is completed, obtaining a polymerization type light stabilizer reaction liquid after reduction and decolorization;

[0019] (3) the polymerization type light stabilizer reaction liquid obtained in the step (2) after reduction and decolorization enters a desolventizing kettle for treatment, and all solvents are distilled off to obtain the polymerization type light stabilizer after reduction and decolorization;

[0020] (4) and (3) the obtained polymerized light stabilizer after reduction and decolorization enters a granulating process to prepare product particles, and optionally, the solvent distilled out in the step (3) is applied to a batching kettle of the next batch. Industrially, such decolorization is known to be affected by treatment with an adsorbent material such as charcoal, silica or activated clay. These adsorbents are known to function through chemisorption and / or physisorption, thereby allowing efficient removal of impurities from a solution. Reference is made, for example, to US4226763A, US4315848A, EP0337942A1 , US5585422A, US5688995A, W002 / 079173A1 , US6649770B1 ,

[0021] WO2017 / 140170A1 , CN105348562A, EP0502821 A1 , US6187919B1 and US2006 / 148914A1 . US6187919 describes, for example, a variety of HPTs and their synthesis and a post processing step involving treatment with an adsorbent followed by filtration. Owing to fine particle size and low solubility of the adsorbents, typically large volumes of solvent is necessary during filtration (or “washing”) to ensure complete removal of unwanted ad-sorbent particles. Additionally, the adsorbent adsorbs some of the desired product and causes significant yield loss during the filtration step.

[0022] However, use of large amounts of expensive adsorbents as well as large volumes of solvents during such filtration add undue burden both economically as well as environmentally on the industrial processes. Therefore, there is an unmet need to provide a process for decolorization of light stabilizers, i.e. increase of transparency as well as decrease of yellowness / gardner color value of light stabilizers, which is simple, efficient and both economical and environmentally feasible.

[0023] Summary of the Invention

[0024] Surprisingly it was found that treatment of light stabilizers with at least one radical initiator can result in efficient decolorization.

[0025] Accordingly, the first aspect of the present invention is directed to a process for decolorization of light stabilizer comprising, especially consisting of: a) obtaining at least one light stabilizer of formula or formula

[0026] R1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,

[0027] R2is hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci-C alkoxy, hydroxyl, phenyl or C2-Cisacyloxy;

[0028] R3is hydrogen, halogen, Ci -Cisalkyl, Ci-Cwalkoxy, C2-Cisacyloxy, phenyl, or is Ci-

[0029] Ciafluoroalkyl;

[0030] R4is hydrogen, halogen, Ci -Cisalkyl, Ci-Cwalkoxy, Ca-C acyloxy, phenyl, or is Ci-

[0031] Ciafluoroalkyl; or

[0032] R3and R4together form a ring; R25is hydrogen, Ci -Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or substituted by

[0033] OH, or by , wherein R1, R3and R4are defined above;

[0034] Ar1is a group of the formula (D-2),

[0035] R6is hydrogen, Ci-C24alkyl, Ce-Cscycloalkyl, C7-Ci2phenylalkyl, or halogen;

[0036] R5and R8are independently of each other hydrogen, or Ci-C2oalkyl, especially hydrogen;

[0037] Z is hydrogen, C2-C2oalkenyl, or said C2-C2oalkenyl substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or —

[0038] CO-; especially Ci-C24alkyl or Cs-Ciacycloalkyl; or said Ci-C24alkyl or said C5-Ci2cycloalkyl substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO-;

[0039] R44is Ce-C aryl, Ce-C aryl substituted by one to three halogen, Ci-Csalkyl, Ci-Csalkoxy, or combinations thereof; C5-Ci2cycloalkyl; C7-Ci2phenylalkyl, C7-Ci2phenylalkyl substituted on the phenyl ring by one to three halogen, Ci-Csalkyl, Ci-Csalkoxy, or combinations thereof;

[0040] R45is defined as is R44; or R45is also hydrogen or Ci-C24alkyl;

[0041] Ar2and Ar3in formula (A) are independently of each other selected from a group of the formula (D-2), (D-3), phenyl or phenyl substituted by one to three Ci¬

[0042] Cealkyl, halogen, hydroxy or Ci-Csalkoxy; naphthyl or naphthyl substituted by one to three

[0043] Ci-Cealkyl, halogen, hydroxy or Ci-Csalkoxy; and

[0044] R51, R52, R53, R54and R55are independently of each other hydrogen, hydroxy, cyano, Ci-

[0045] C2oalkyl, Ci-C2oalkoxy, C7-Ci2phenylalkyl, C5-Ci2cycloalkyl, C5-Ci2cycloalkyloxy, or halogen; Z’ is as defined for Z, R6is as defined for R6, R5and R8are as defined for R5and R8, respectively; b) treating the light stabilizer of formula (A) or (B) with at least one radical initiator selected from azo radical initiators and peroxide radical initiators to obtain a decolorized light stabilizer of formula (A) or (B), or a suspension / solution of a decolorized light stabilizer of formula (A) or (B).

[0046] The treatment of the light stabilizer of formula (A) or (B) with the at least one radical initiator my be done in a solvent. The solvent may be removed after the treatment.

[0047] In a preferred embodiment the light stabilizers (A), or (B) are commercially available in the form of a suspension / solution; i.e. are provided in the form of a suspension / solution; and (b) the suspension / solution of the light stabilizer of formula (A) or (B) is treated before sale with at least one radical initiator selected from azo radical initiators and peroxide radical initiators to obtain a suspension / solution of a decolorized light stabilizer of formula (A) or (B).

[0048] The second aspect of the invention is directed to a decolorized light stabilizer obtained from the process according to the first aspect. The decolorized light stabilizer has preferably a gardner color < 7.0. In addition, the decolorized light stabilizer has preferably a Yellowness Index Change (AYI) according to Equation 1 of > 0.5, more preferably > 1 , even more preferably in the range of from 1 .0 to 7.0:

[0049] Yellowness Change (AYI) = Yellowness Index of the light stabilizer obtained in step b) - Yellowness Index of the light stabilizer obtained in step a) [Equation 1],

[0050] The decolorized light stabilizer contains the degradation product(s) of the azo radical initiators and peroxide radical initiators, respectively. In case of a suspension / solution of the light stabilizer of formula (A) or (B) the suspension / solution is treated before sale with at least one radical initiator selected from azo radical initiators and peroxide radical initiators, said suspension / solution contains besides the decolorized light stabilizer the degradation product(s) of the azo radical initiators and peroxide radical initiators, respectively.

[0051] The third aspect of the invention is directed to a composition comprising the decolorized light stabilizer according to the second aspect.

[0052] The fourth aspect of the invention is directed to the use of the decolorized light stabilizer according to the second aspect as an ultraviolet stabilizer.

[0053] The fifth aspect of the invention is directed to a process of protecting a material or coating from light, wherein the process comprises a step of providing the decolorized light stabilizer according to the second aspect.

[0054] Detailed Description The ranges defined throughout the specification include the end values as well the start values i.e. a range of 1 to 10 implies that both 1 and 10 are included in the range.

[0055] In the following passages, different aspects of the invention are illustrated in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0056] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the presently claimed invention. Thus, appearances of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment.

[0057] Radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. Typical examples are azo compounds (azo radical initiators) and organic and inorganic peroxides (peroxide radical initiators).

[0058] Here and throughout the specification, the term "halogen" denotes fluorine, bromine, chlorine or iodine, especially chlorine, bromine or iodine, very especially chlorine.

[0059] The term "Ci-Cn-alkyl" denotes a group of linear or branched saturated hydrocarbon radicals having from 1 to n carbon atoms. For example, the term Ci-C24alkyl denominates a group of linear or branched saturated hydrocarbon radicals having from 1 to 24 carbon atoms, while the term Ci-C4alkyl denominates a group of linear or branched saturated hydrocarbon radicals having from 1 to 4 carbon atoms, the term C4-C5oalkyl denominates a group of linear or branched saturated hydrocarbon radicals having from 4 to 50 carbon atoms and the term Ci- Cisalkyl denominates a group of linear or branched saturated hydrocarbon radicals having from 1 to 18 carbon atoms. Examples of alkyl include but are not limited to methyl, ethyl, n- propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-methylpropyl (isopropyl),

[0060] 1 .1 -dimethylethyl (tert-butyl), pentyl, 1 -methylbutyl, 2-methylbutyl, 3-methylbutyl,

[0061] 2.2-dimethylpropyl, 1 -ethylpropyl, hexyl, 1 ,1 -dimethylpropyl, 1 ,2-dimethylpropyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1 ,1 -dimethylbutyl,

[0062] 1 .2-dimethylbutyl, 1 ,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1 - ethylbutyl, 2-ethylbutyl, 1 ,1 ,2-trimethylpropyl, 1 ,2,2-trimethylpropyl, 1 -ethyl-1 -methylpropyl, 1- ethyl-2-methylpropyl, heptyl, octyl, 2-ethylhexyl, 1 ,1 ,3,3-tetramethylbutyl (tert-octyl), nonyl, isononyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl docosyl and in case of nonyl, isononyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl docosyl their isomers, in particular mixtures of isomers such as "isononyl", "isodecyl". Examples of Ci-C4alkyl are for example methyl, ethyl, propyl, 1 -methylethyl, butyl, 1 -methylpropyl, 2-methylpropyl or 1 ,1 -dimethylethyl. The term "Ci-C24alkoxy" as used herein denotes straight-chain or branched Ci-C24alkyl as defined above bound to the remainder of the molecule through an oxygen. Examples for Ci- C4-alkoxy are methoxy, ethoxy, n-propoxy, 1 -methylethoxy, butoxy, 1 -methylpropoxy,

[0063] 2-methylpropoxy and 1 ,1 -dimethylethoxy.

[0064] The term "Ci-Ci2fluoroalkyl" as used herein denotes straight-chain or branched Ci-Ci2alkyl as defined above, where some or all of the hydrogen atoms in these groups may be replaced by fluorine. Examples for Ci-C2-fluoroalkyl are fluoromethyl, difluoromethyl, trifluoromethyl, 1 - fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl and pentafluoroethyl.

[0065] As C5-Ci2cycloalkyl, R6, for example, can be be cyclopentyl, cyclooctyl or cyclododecyl, but especially cyclohexyl.

[0066] The term "Ce-Cio-aryl" as used herein denotes phenyl or naphthyl.

[0067] C7-Ci2phenylalkyl can, for example, be phenylethyl, 2-hydroxy-2-phenylethyl, 2-phenylpropyl,

[0068] 3-phenylpropyl, 4-chlorobenzyl or 4-methylbenzyl, but especially benzyl.

[0069] As C4-C5oalkyl which is interrupted by O and / or substituted by OH, R25, for example, can be alkyl which is substituted by OH, alkyl which is interrupted by O, or alkyl which is interrupted by O and substituted by OH. Examples of these are the groups -CH2CH2OH, -CH2CH(OH)CH3, -CH2CH(OH)C6Hi3, -CH2CH2OC4H9, -CH2CH2OCH2CH2OH or -CH2CH2(OCH2CH2)POH in which p=2-9. In case Ci-Cisalkyl is interrupted by O said alkyl group has at least 2 carbon atoms.

[0070] An example of a ring formed by R3and R4is , wherein R56is Ci-C24alkyl, especially Ci-C24alkyl.

[0071] If groups, such as, for example R1, R2, R3and R4, may occur multiple times in one molecule, they can be the same, or different, but are preferably the same.

[0072] Accordingly, the presently claimed invention is directed to a process for decolorization of light stabilizer comprising: a) obtaining at least one light stabilizer of formula or formula wherein

[0073] Ar1, Ar2and Ar3in formula (A) are defined above, or below, and

[0074] R1, R2, R3and R4in formula (B) are defined above, or below; b) treating the light stabilizer of formula (A) or (B) with at least one radical initiator selected from azo radical initiators and peroxide radical initiators.

[0075] The process of the presently claimed invention involves the treatment of a light stabilizer with a radical initiator.

[0076] Light stabilizers, in this regard, may be defined as compounds with ability to absorb light in the UVA and / or UVB. These stabilizers protect materials by converting absorbed ultraviolet rays into low-impact heat and energy through chemical reactions. The stabilizers are mainly used to curtail photodegradation (for instance in plastics or polymers) by playing a key role in suppressing the generation of radicals that cause plastic to degrade. Suitable stabilizers typically have at least one absorption maxima in the range between 280 to 420 nm.

[0077] Preferably, the light stabilizer of formula (A) or (B) has an absorption spectrum in the ultraviolet range with at least one absorption maximum Xmax in the range of 280 and 420 nm, more preferably in the range of 280 and 400 nm. Light stabilizers having an absorption maximum > 420 nm are noted to be too colored and therefore unsuitable for coating applications.

[0078] The light stabilizers suitable for the presently claimed process of formula (A) or (B) fall into the category of substituted triazines and benzotriazoles.

[0079]

[0080] The at least one light stabilizer has the formula (A), especially the formula

[0081] Ar1is a group of the formula (D-2),

[0082] R6is hydrogen, Ci-C24alkyl, C5-Ci2cycloalkyl, C7-Ci2phenylalkyl, or halogen;

[0083] R5and R8are independently of each other hydrogen, or Ci-C2oalkyl, especially hydrogen;

[0084] Z is hydrogen, especially Ci-C24alkyl or C5-Ci2cycloalkyl; or said Ci-C24alkyl or said C5- Ci2cycloalkyl substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO — ;

[0085] R44is Ce-Cwaryl, Ce-C aryl substituted by one to three halogen, Ci-Csalkyl, Ci-Csalkoxy, or combinations thereof; C5-Ci2cycloalkyl; C7-Ci2phenylalkyl, C7-Ci2phenylalkyl substituted on the phenyl ring by one to three halogen, Ci-Csalkyl, Ci-Csalkoxy, or combinations thereof; R45is defined as is R44; or R45is also hydrogen or Ci-C24alkyl.

[0086] Z is preferably (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;

[0087] R12is Ci -Cisalkyl or Ce-Cwaryl or CO-Ci-C alkyl;

[0088] R13is H or Ci-Csalkyl; R14is Ci-Csalkyl or C2-Ci2alkenyl or Cs-Cecycloalkyl.

[0089] R14is preferably Ci-Csalkyl or C5-Cecycloalkyl.

[0090] R5and R6are preferably hydrogen. R8is preferably hydrogen or methyl. Ar2and Ar3in formula (A) can be the same, or different and are selected from a group of the formula (D-2), (D-3), phenyl or phenyl substituted by one to three Ci-

[0091] Cealkyl, halogen, hydroxy or Ci-Ci2alkoxy; and (D-4).

[0092] In an embodiment Ar2and Ar3in formula (A) are independently of each other selected from a group of the formula (D-2). In said embodiment the compound of formula (A) is preferably a compound of formula (A-1 ), wherein

[0093] Z is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ; R12is Ci -Cisalkyl, or Ce-Ci2aryl or CO-Ci-Cisalkyl; R13is H or Ci-Csalkyl; R14is Ci -Ci2alkyl or C2- Ci2alkenyl or Cs-Cecycloalkyl.

[0094] R14is preferably Ci-Ci2alkyl or C5-C6cycloalkyl.

[0095] In another embodiment Ar2and Ar3in formula (A) are independently of each other phenyl or phenyl substituted by one to three Ci-Cealkyl. In said embodiment the compound of formula

[0096] (A) is preferably a compound of formula

[0097] R5', R5”, R7' and R7are hydrogen or Ci-Cealkyl, especially Ci-Csalkyl.

[0098] In another embodiment Ar2and Ar3in formula (A) are independently of each other a group of the formula ; wherein R51, R52, R53, R54and R55are preferably hydrogen.

[0099] In said embodiment the compound of formula (A) is preferably a compound of formula

[0100] R51, R52, R53, R54and R55are defined above and preferably hydrogen.

[0101] For the process described herein, a few exemplary light stabilizers of formula (A) are listed hereinbelow.

[0102] Most preferably the light stabilizer of formula (A) is selected from 2-(4,6-diphenyl-1 ,3,5- triazin-2-yl)-5-(hexyloxy)-phenol, 2-(4,6-bis-(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl)-5- (octyloxy)-phenol, 2-[4,6-Bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2- hydroxypropoxy]phenol and 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3- (tridecyloxy)propoxy]phenol, 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-[(2- ethylhexyl)oxy]-2-hydroxypropoxy]phenol, 2-[4,6-Bis([1 , 1 '-biphenyl]-4-yl)-1 ,3, 5-triazin-2-yl]-5- [(2-ethylhexyl)oxy]phenol, 2-[2-hydroxy-4-(1 -octyloxycarbonylethyl)oxyphenyl]-4,6-di(4- phenyl)phenyl-1 ,3,5-triazine, 2,4,6-tri(2,4-dihydroxyphenyl)-1 ,3,5-triazine, 2,4-bis[2-hydroxy- 4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1 ,3,5-triazine, 2,2'-[6-(4-methoxyphenyl)-1 ,3,5- triazine-2,4-diyl]bis(5-((2-ethylhexyl)oxy)-phenol, 2,4,6-tris-(2'-hydroxy-4'-butoxyphenyl)- 1 ,3,5-triazine, 2,2',2"-(1 ,3,5-triazine-2,4,6-triyl)tris[5-(octyloxy)phenol], 2,4,6-tris(2-hydroxy-4- hexyloxy-3-methylphenyl)-1 ,3,5-triazine, 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5- [2-hydroxy-3-(tridecyloxy)propoxy]-phenol, 2,4,6-tris[4-(1 -octyloxycarbonyl)ethyloxy-2- hydroxyphenyl]-1 ,3,5-triazine, 1 ,1 '-dioctyl 2,2'-[[4-[4,6-bis[2-hydroxy-4-[1 -methyl-2-(octyloxy)- 2-oxoethoxy]phenyl]-1 ,3,5-triazin-2-yl]-1 ,3-phenylene]bis(oxy)]bis[propanoate], 2,4-bis(2,4- dihydroxyphenyl)-6-(4-methoxyphenyl)-1 ,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl- 1 ,3,5-triazine, 2,6-bis(2,4-dimethylphenyl)-4-(2,4-dihydroxyphenyl)-s-triazine, 4-[4,6-bis([1 ,1 biphenyl]-4-yl)- 1 ,3,5-triazin-2-yl]-1 ,3-benzenediol and 2,4,6-tris(2,4-dihydroxy-3- methylphenyl)-1 ,3,5-triazine and 2,4,6-tribiphenyl-4-yl-1 ,3,5-triazine. One or more of the mentioned compounds may exist in one or more isomeric or polymorphic forms, one or more of which may reveal an improved activity. Such forms or isomers are considered to be included within the scope of the present invention. Purification and isolation to yield one or more of such preferred isomers or forms is considered within the scope of this application.

[0103] A few exemplary light stabilizers of formula (A) are selected from Tinuvin® 1577 (CAS 147315-50-2), Cyasorb® UV-1 164 (CAS 2725-22-6), Tinuvin® 400, Tinuvin® 405 (CAS 137658-79-8), Tinuvin® 1600 (CAS 204583-39-1 ), Tinuvin® 479 (CAS 204848-45-3, CAS 304671 -49-6), Tinuvin® 460 (CAS 208343-47-9), Tinuvin® 477, Tinuvin® 41 1 , Tinosorb® S (CAS 187393-00-6), Triazin 5 (CAS 3135-19-1 ), P 800 (CAS 13681 -75-9), LA-F 70 (CAS 222529-65-9), 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3- (tridecyloxy)propoxy]-phenol (CAS 178905-32-3) and 6-[(2E)-4,6-bis[(1 E)-4-(octyloxy)-6- oxocyclohexa-2,4-dien-1-ylidene]-1 ,3,5-triazinan-2-ylidene]-3-(octyloxy)cyclohexa-2,4-dien-1 - one (CAS 2733595-35-0).

[0104] In another embodiment the at least one light stabilizer has the formula wherein

[0105] R1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,

[0106] R2is hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci-C alkoxy, hydroxyl, phenyl or Ca-Ciaacyloxy;

[0107] R3is hydrogen, halogen, Ci -Cisalkyl, Ci-Cwalkoxy, Ca-Ciaacyloxy, phenyl, or is Ci-

[0108] Ciafluoroalkyl, especially hydrogen;

[0109] R4is hydrogen, halogen or Ci-Cisalkyl, especially hydrogen or halogen, especially chlorine; and

[0110] R25is Ci -Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or substituted by OH, or by

[0111] , wherein R1, R3and R4are defined above, or below.

[0112] R1is preferably hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl.

[0113] R2is preferably hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci- Ciaalkoxy, hydroxyl, phenyl or Ca-Ciaacyloxy.

[0114] R3is preferably hydrogen.

[0115] R4is preferably hydrogen, or halogen, especially chlorine.

[0116] R25is preferably Ci -Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or substituted by

[0117] OH, or by , wherein R1, R3and R4are defined above.

[0118] Most preferably the light stabilizer of formula (B) is selected from 2-(benzotriazol-2-yl)-4- methylphenol, 2-(2'-hydroxy-3',5'-di-t-butyl-phenyl)benzotriazole, 2-(5-chlor-2H-benzotriazol- 2-yl)-4-methylphenol, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2H- benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2'-hydroxy-5'-(1 ,1 ,3,3- tetramethylbutyl)phenyl)benzotriazole, 2-(benzotriazol-2-yl)-6-butan-2-yl-4-tert-butylphenol, 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1 ,1 ,3,3-tetramethylbutyl)phenol), 2-(2H- benzotriazol-2-yl)-6-dodecyl-p-cresol, 2-(2-benzotriazolyl)-6-dodecyl-4-methylphenol, polyethylene glycol di[3-[3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]-1 -oxopropyl] ether, 2-(2H-benzotriazol-2-yl)-4,6-bis(1 -methyl-1 -phenylethyl)phenol, 2-(2H-benzotriazol-2- yl)-6-(1 -methyl-1 -phenylethyl)-4-(1 , 1 ,3,3-tetramethylbutyl)phenol, 3-(2H-benzotriazol-2-yl)-5- (1 ,1 -dimethylethyl)-4-hydroxybenzenepropanoic acid, a-[3-[3-(2H-benzotriazol-2-yl)-5-(1 ,1- dimethylethyl)-4-hydroxyphenyl]-1 -oxopropyl]-®-hydroxypoly(oxy-1 ,2-ethanediyl), octyl 3-[3- (2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate, octyl 3-[3-(2H-Benzotriazol-2- yl)-5-tert-butyl-4-hydroxyphenyl]propionate, 6-butyl-2-[2-hydroxy-3-(2-phenyl-2-propyl)-5- (2,4,4-trimethyl-2-pentyl)phenyl]-[1 ,2,3]triazolo[4,5-f]isoindole-5,7(2H,6H)-dione, 6-butyl-2-[2- hydroxy-3-(1 -methyl-1 -phenylethyl)-5-(1 ,1 ,3,3-tetramethylbutyl)phenyl]pyrrolo[3,4- f]benzotriazole-5,7(2H,6H)-dione, octyl 3-[3-tert-butyl-5-(5-chlorobenzotriazol-2-yl)-4- hydroxyphenyl]propanoate, 2-(benzotriazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol, 3-[3- (2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionic acid, methyl 3-[3-tert-butyl-5- (2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate, 2-[3-(2H-benzotriazol-2-yl)-4- hydroxyphenyl]ethyl methacrylate and 2-(2H-benzotriazol-2-yl)-4-methyl-6-[2-methyl-3- [1 ,3,3,3-tetramethyl-1 - [(tri methy Isi ly I) oxy]- 1 -disiloxanyl]propyl]phenol. One or more of the mentioned compounds may exist in one or more isomeric or polymorphic forms, one or more of which may reveal an improved activity. Such forms or isomers are considered to be included within the scope of the present invention. Purification and isolation to yield one or more of such preferred isomers or forms is considered within the scope of this application

[0119] A few exemplary light stabilizers of formula (B) are selected from Tinuvin® P (CAS 2440-22- 4), Tinuvin® 320 (CAS 3846-71 -7), Tinuvin® 326 (CAS 3896-11 -5), Tinuvin® 327 (CAS 3864-99-1), Tinuvin® 328 (CAS 25973-55-1), Tinuvin® 329 (CAS 3147-75-9), Tinuvin® 350 (CAS 36437-37-3), Tinuvin® 360 (CAS 103597-45-1 ), Tinuvin® 171 (CAS 23328-53-2), Tinuvin® 213 (mixture of PEG and CAS 104810-48-2 and CAS 104810-47-1 ), Tinuvin® 900 (CAS 70321 -86-7), Tinuvin® 928 (CAS 73936-91 -1 ), Tinuvin® 840 (CAS 84268-08-6), Tinuvin® 1130 (CAS 104810-47-1), Tinuvin® 384 (CAS 84268-23-5), Tinuvin® 99 (CAS 84268-23-5), Xymara Carboprotect® (CAS 945857-19-2), Tinuvin® 970 (CAS 945857-19-2), Tinuvin® 109 (CAS 83044-89-7), Uvinul® 3029 (CAS 3147-75-9), 3-[3-(2H-Benzotriazol-2- yl)-5-tert-butyl-4-hydroxyphenyl]propionic acid (CAS 84268-36-0), Methyl 3-[3-tert-butyl-5- (2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate (CAS 84268-33-7), RUVA 93 (CAS 96478-09-0) and Mexoryl XL (CAS 155633-54-8). Tinuvin® and CarboProtect® are trademarks of BASF SE, Ludwigshafen.

[0120] Compounds of formula (A’) can be prepared by i) reacting (A’) with to obtain a compound of formula wherein Ar1and Ar2are defined above; and ii) converting the compound of formula (I) to a compound of formula (A’).

[0121] Examples of the compounds of formula (I) are shown below:

[0122] The conversion of (I) into (A’) can be effected by various processes known per se, depending on the nature of the group Z.

[0123] If Z is a group (CH2-CH2-O-)ni-R12; the compound of formula (I) or an alkali metal salt thereof can be reacted with a halogen compound of the formula Hal-Z.

[0124] If Z is a group -CH(R13)-CO-O-R14; the compound of formula (I) or an alkali metal salt thereof can be reacted with a halogen compound of the formula Hal-Z.

[0125] If Z is a group -CH2-CH(OH)-CH2-O-R12such compounds can be prepared by reacting a compound of the formula (I) or a metal salt thereof with an epoxide of the formula

[0126] C wherein R2is Ci-Cisalkyl which is substituted by COOR25, such as, for example, (a-[3-[3-(2 / - / -benzotriazol-2-yl)-5-(1 ,1 - dimethylethyl)-4-hydroxyphenyl]-1 -oxopropyl]-co-hydroxy-poly(oxy-1 ,2-ethanediyl, CAS 104810-48-2; Tinuvin 1130) can be synthesized analogously to a procedure as described in example 117b of US6369267 by using, for example, methyl 3-[3-(benzotriazol-2-yl)-5-tert- butyl-4-hydroxy-phenyl]propanoate and polyethylene glycol 300 under solvent-free conditions.

[0127] Light stabilizers are well known, per se, and light stabilizers are described together with their preparation in, for example, W02005023878, US8454940, W02004 / 106311 , WO96 / 28431 , EP-A-323408, EP-A-57160, US5736597, US4619956, DE3135810A and GB1336391 A.

[0128] The process according to the presently claimed invention preferably utilizes at least one radical initiator that readily disintegrates to release radicals at suitably low temperatures. The process according to the presently claimed invention preferably utilizes, the radical initiators having half-life periods in the radical decomposition process of 1 hour at temperatures < 280 °C, more preferably < 250 °C, even more preferably < 200 °C, most preferably < 120 °C. More preferably, the radical initiators having half-life periods in the radical decomposition process of 1 hour in the range from 20 to 280 °C, preferably from 30 to 280 °C, more preferably from 30 to 250 °C, most preferably from 40 to 120 °C. On the other hand, radical initiators having half-life periods in the radical decomposition process of 1 hour < 20 °C are expected to have problems associated with safe handling and storage.

[0129] The process according to the present invention uses radical initiators (also referred to as free-radical polymerization initiators), that is to say initiators which form free radicals under the reaction conditions. These may be peroxides or they may be azo compounds. Redox initiator systems are of course also suitable.

[0130] Peroxide radical initiators used may in principle be inorganic peroxides and / or organic peroxides. Examples of suitable inorganic peroxides include hydrogen peroxide and peroxodisulfates, such as the mono- or dialkali metal or ammonium salts of peroxodisulfuric acid, for example the mono- and disodium, mono- and dipotassium, or ammonium salts thereof. Examples of suitable organic peroxides are diacyl peroxides, such as diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, dilauroyl peroxide, disuccinic acid peroxide, benzoyl peroxide, or a mixture of dibenzoyl peroxide, benzoyl m-methylbenzoyl peroxide, and m-toluoyl peroxide; peroxyketals, such as 2,2-bis(4,4-di-tert- butylperoxycyclohexyl)propane, 1 , 1 -di(tert-hexylperoxy)cyclohexane, 1 , 1 -d i (tert- butylperoxy)cyclohexane, n-butyl 4,4-di(tert-butylperoxy)valerate, or 2,2-di(tert- butylperoxy)butane; peroxy(di)carbonates, peroxyesters, dialkyl peroxides, such as tert- butylcumyl peroxide, di-tert-butyl peroxide, or di-tert-hexyl peroxide; and hydroperoxides.

[0131] In a preferred embodiment the at least one radical initiator is a peroxide radical initiator selected from dilauroyl peroxide, didecanoyl peroxide, diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxypivalate, tert-amyl peroxypivalate, tertbutyl peroxypivalate, di(3,5,5-trimethylhexanoyl) peroxide, 2,5-dimethyl-2,5-di(2- ethylhexanoylperoxy)hexane, 1 ,1 ,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, 1 ,1 -di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1 ,1 -di (tert- amylperoxy)cyclohexane, 1 ,1 -di(tert-butylperoxy)cyclohexane, tert-amylperoxy-2-ethylhexyl carbonate, tert-amyl peroxyacetate, tert butyl peroxy-3,5,5-trimethylhexanoate, 2,2-di(tert- butylperoxy)butane, tert-butylperoxy isopropyl carbonate, tert-butylperoxy 2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert- butylperoxy)valerate, tert-butyl peroxybenzoate, dicumyl peroxide, di(tert- butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-tri methyl-1 ,4,7-triperoxonane, 3,6, 9-triethyl-3,6, 9-tri methyl- 1 ,2,4,5,7,8-hexoxonane, 3,6,9-trimethyl-3,6,9-tripropyl- 1 ,2,4,5,7,8-hexoxonane, isopropylcumyl hydroperoxide, 1 ,1 ,3,3-tetramethylbutyl hydroperoxide, cumyl hydroperoxide, tert-butyl hydroperoxide, tert-amyl hydroperoxide, 3,3,5,7,7-pentamethyl-1 ,2,4-trioxepane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, tert-butyl cumyl peroxide, di(4-methylbenzoyl) peroxide and di(2,4-dichlorobenzoyl) peroxide.

[0132] As a peroxide radical initiator dialkyl peroxide, diacyl peroxide, and peroxyketal are preferable, and diacyl peroxide is more preferable.

[0133] In a preferred embodiment the at least one radical initiator is an azo radical initiator which is preferably selected from azo nitril initiators, azo ester initiators, azo amide initiators, azo imidazoline initiators, azo amidine initiators and macro azo initiators, such as, for example, 4,4’-azobis(4-cyanopentanoicacid) polyethyleneglycolpolymer.

[0134] More preferably, the azo radical initiator has a formula (C), wherein

[0135] Y is selected from CN, -C(=O)ORe, wherein Reis Ci-Cealkyl; -C(=O)NHRf, wherein Rfis Ci- Cealkyl, which may optionally be substituted by -OH; -C(=NH)NH2 * HCI; -C(=NH)NHRh, wherein Rhis Ci-Cealkyl, which may optionally be substituted by -C(=O)OH; 2-imidazolin-2-yl and 2-imidazolin-2-yl * hydrochloride,

[0136] Ra, Rb, Rc and Rd are independently of each other selected from Ci-Csalkyl, or Ci-Csalkyl, which is substituted by -COOH, or -OR9, wherein R9is Ci-Cealkyl; and / or interrupted by -O-; Ce-Cscycloalkyl, which may optionally be substituted by one, or more Ci-C4alkyl; or Ramay be bonded to Rb and / or Rcmay be bonded to Rd to form a cyclopentane, or cyclohexane ring, which may optionally be substituted by one, or more Ci-C4alkyl.

[0137] Most preferably, the azo radical initiator is selected from 2,2’-azobis(isobutyronitrile), 2,2’- azobis(2-methylbutyronitrile), 1 ,1 ’-azobis(cyclohexane-1 -carbonitrile), 2,2’-azobis(2,4- dimethylvaleronitrile), dimethyl 2,2’-azobis(2-methylpropionate), 2,2’-azobis(4-methoxy-2,4- dimethylvaleronitrile), 4,4’-azobis(4-cyanovaleric acid), 2,2’-azobis[2-methyl-N-(2- hydroxyethyl)propionamide], 2,2’-azobis(N-butyl-2-methylpropionamide), 2,2’-azobis[2-(2- imidazolin-2-yl)propane]dihydrochloride, 2,2’-azobis[2-(2-imidazolin-2-yl)propane], 2,2’- azobis(2-methylpropionamidine) dihydrochloride, 2,2’-azobis[N-(2-carboxyethyl)-2- methylpropionamidine] n-hydrate and 4,4’-azobis(4-cyanopentanoicacid) polyethyleneglycolpolymer. Among the above listed azo radical initiators azo nitril initiators are preferred:

[0138] (C), wherein

[0139] Y is CN;

[0140] Ra, Rb, Rc and Rd are independently of each other selected from Ci-C4alkyl, Ci-C4alkyl, which is substituted by -COOH and -OR9, wherein R9is Ci-C4alkyl; or

[0141] Ramay be bonded to Rb and / or Rcmay be bonded to Rd to form a cyclohexane ring.

[0142] 2,2’-Azobis(isobutyronitrile) is most preferred.

[0143] Redox initiator systems are combined systems made up of at least one organic or inorganic reducing agent and at least one peroxide. Suitable oxidants for redox initiator systems are essentially the peroxides mentioned above. Corresponding reducing agents that may be used are sulfur compounds in a low oxidation state such as alkali metal sulfites, for example potassium and / or sodium sulfite, alkali metal hydrogen sulfites, for example potassium and / or sodium hydrogen sulfite, alkali metal metabisulfites, for example potassium and / or sodium metabisulfite, acetone bisulfite, formaldehyde sulfoxylates, for example potassium and / or sodium formaldehyde sulfoxylate, potassium and / or sodium salts of aliphatic sulfinic acids and alkali metal hydrogen sulfides, for example potassium and / or sodium hydrogen sulfide, salts of polyvalent metals, such as iron(ll) sulfate, iron(ll) ammonium sulfate, iron(ll) phosphate, enediols, such as dihydroxymaleic acid, benzoin and / or ascorbic acid, and reducing saccharides, such as sorbose, glucose, fructose and / or dihydroxyacetone.

[0144] Preferred free-radical initiators are inorganic and organic peroxides, preferably ammonium or alkali metal salts of peroxosulfates or peroxodisulfates, and tert-butyl, p-menthyl and cumyl hydroperoxide, in particular selected from sodium and potassium peroxodisulfate, tert-butyl hydroperoxide and cumyl hydroperoxide. Particular preference is given to using both at least one inorganic peroxide, preferably peroxodisulfate, in particular sodium peroxodisulfate, and / or one organic peroxide, preferably alkyl hydroperoxide, in particular t-butyl hydroperoxide.

[0145] Preferably, the weight ratio of light stabilizer of formula (A) or (B) to the radical initiator is in the range from 50000:1 to 100:1 , more preferably 30000:1 to 100:1 , more preferably 28000:1 to 120:1 , even more preferably 25000:1 to 120:1 , more preferably 20000:1 to 130:1.

[0146] The process may be performed in presence of a solvent or alternatively at high temperatures to ensure molten reaction conditions. When present, the solvent may be in a minimum quantity as would be necessary to ensure appropriate mixing. Some light stabilizers (A), or (B) are commercially available in the form of a suspension / solution. In said case the suspension / solution of the light stabilizer of formula (A) or (B) is treated before sale with at least one radical initiator selected from azo radical initiators and peroxide radical initiators. When the process is carried out in the presence of a solvent, the solvent is preferably selected from alcohols, ethers, lactones, carbonates, sulfones, N, N-dimethylformamide, N, N- dimethylacetamide, acetonitrile, dimethylsulfoxide, N-methyl-pyrrolidone, N-ethyl-pyrrolidone, aromatic hydrocarbons, dichloroethane, halogenated aromatic hydrocarbon and a combination of two or more thereof, more preferably the solvent is selected from alcohols, ethers, ketones, esters, water, N, N-dimethylformamide, N, N-dimethylacetamide, acetonitrile, dimethylsulfoxide, N-methyl-pyrrolidone, N-ethyl-pyrrolidone, aromatic hydrocarbons, dichloroethane, halogenated aromatic hydrocarbon and a combination of two or more thereof, even more preferably the solvent is selected from alcohols, ethers, N, N-dimethylformamide, N-methyl-pyrrolidone, N-ethyl-pyrrolidone, aromatic hydrocarbons, dichloroethane, halogenated aromatic hydrocarbon and a combination of two or more thereof, most preferably the solvent is selected from alcohols, ethers, N, N-dimethylformamide, N-methyl-pyrrolidone, N-ethyl-pyrrolidone, aromatic hydrocarbons, halogenated aromatic hydrocarbon and a combination of two or more thereof, and in particular the solvent is selected from alcohols, ketones, esters, ethers, aromatic hydrocarbons, halogenated aromatic hydrocarbon, water and a combination thereof.

[0147] Preferably, the reaction is carried out in presence of a solvent in an amount in the range of 0.01 to 20 times based of total amount of formula (A) or (B), more preferably the reaction is carried out in presence of a solvent in an amount in the range of 0.1 to 10 times based of total amount of formula (A) or (B), even more preferably the reaction is carried out in presence of a solvent in an amount in the range of 0.2 to 5.0 times based of total amount of formula (A) or (B), most preferably the reaction is carried out in presence of a solvent in an amount in the range of 0.5 to 3.0 times based of total amount of formula (A) or (B), and in particular the reaction is carried out in presence of a solvent in an amount in the range of 0.5 to 2.0 times based of total amount of formula (A) or (B).

[0148] Preferably, the pH of the reaction is maintained <9.0, more preferably the pH of the reaction is maintained in the range of > 0.0 to <8.0, even more preferably the pH of the reaction is maintained in the range of > 5.0 to <8.0.

[0149] Preferably, the step b) is carried out at a temperature > 20 °C, more preferably > 40 °C, even more preferably 60 °C, more preferably 80 °C. The step b) is preferably carried out at a temperature of from 20 to 200 °C, more preferably of from 40 to 160 °C, even more preferably of from 60 to 120 °C.

[0150] The treatment of step b) is preferably carried out for 1 minute to 48 hours. More preferably, the treatment of step b) is carried out for 1 minute to 12 hours, even more preferably from 30 minutes to 3 hours. The treatment of step b) is preferably carried out in the presence of mechanical agitation such as stirring. The same may be performed by any known method using external mechanical shakers or by using magnetic stirring beads among others.

[0151] The present invention is also directed to a decolorized light stabilizer obtained from the process described hereinabove.

[0152] Preferably, the decolorized light stabilizer has preferably a gardner color < 8.0, more preferably < 7.0, even more preferably < 6.5. The gardner color was measured in accordance with method as described herein below.

[0153] Preferably, the decolorized light stabilizer is characterized by a Yellowness Index Change (AYI) according to Equation 1 of > 0.5, more preferably > 1 , even more preferably in the range of from 1 .0 to 7.0:

[0154] Yellowness Change (AYI) = Yellowness Index of the light stabilizer obtained in step b) - Yellowness Index of the light stabilizer obtained in step a) [Equation 1],

[0155] Traditional synthetic routes are noted to result in the presence of trace amounts of colored by-products. Typically, these by-products are not well-characterized and impart an unwanted “yellowness” to the light stabilizer. Without being bound by theory, it is noted that the process of the present invention involving treatment of light stabilizers with radical initiators, chemically deactivates the colored by-products. Said treatment renders them benign and their presence in the light stabilizer no longer impairs application. Therefore, no additional filtration step is necessary and the decolorized light stabilizer can be used as such without any further treatment for removal of by-products.

[0156] Said decolorized light stabilizer is noted to provide long term stability comparable with commonly used industry standard UV absorber (for e.g., hydroxyphenyl benzotriazole class absorber).

[0157] The presently claimed invention is also directed to a compositions comprising the decolorized light stabilizer obtained from the process described hereinabove.

[0158] Preferably the composition may be solvent based or water based. Typical examples of organic solvents are aliphatic, aromatic or cycloaliphatic hydrocarbons, alcohols, glycols, esters, acetates and ketones.

[0159] The presently claimed invention is also directed to a use of the decolorized light stabilizer obtained from the process described hereinabove as ultraviolet stabilizer. The use of the decolorized light stabilizer as ultraviolet stabilizer may be in personal and home care such as in cosmetics, plastics or surface coatings. The presently claimed invention is also directed to a method of protecting a material or coating from light, wherein the method comprises a step of providing the decolorized light stabilizer obtained from the process described hereinabove, as an ultraviolet stabilizer.

[0160] Preferably the coatings are surface coatings. Preferably, the composition is an automotive coating composition.

[0161] The coating composition is preferably a laquer, in particular a stoving laquer which is used for coating automobiles (automobile finishing lacquers), for example stoving lacquers comprising alkyd / melamine resins and alkyd / acrylic / melamine resins (see H. Wagner and H. F. Sarx, "Lackkunstharze" (1977), pages 99-123), epoxy / carboxy resins, isocyanate crosslinked acrylic polyols or polyester polyols. Other crosslinking agents include glycoluril resinsor blocked isocyanates.

[0162] The coating composition preferably contains 0.01 -10 parts by weight, especially 0.05-10 parts by weight, more especially 0.1 -5 parts by weight, of the product, or a salt thereof according to the invention per 100 parts by weight of a solid binder. The binders may in principle be any binders that are customary in the art, for example those described in Ullmann’s Encyclopedia of Industrial Chemistry, 5th ed., Vol. A18, pp. 368-426, VCH, Weinheim 1991 . The binder will generally be a film-forming binder, based on a thermoplastic or thermosetting resin, predominantly on a thermosetting resin. Examples thereof are alkyd, acrylic, polyester, phenolic, melamine, epoxy and polyurethane resins and mixtures thereof.

[0163] It may be a cold-curable or a hot-curable binder, and the addition of a curing catalyst may be advantageous. Suitable catalysts, which accelerate full curing of the binder, are described, for example, in Ullmann’s Encyclopedia of Industrial Chemistry, Vol. A18, p. 469, VCH Verlagsgesellschaft, Weinheim 1991.

[0164] Multilayer systems are possible here as well, it being possible for the concentration of the stabilizers in the top layer to be higher, for example from 1 to 15 parts by weight, especially from 3 to 10 parts by weight, based on 100 parts by weight of solid binder.

[0165] The examples below serve to illustrate the invention without limiting it in any way.

[0166] Examples

[0167] Materials and Methods

[0168] 1 -Methoxy-2-propanol (MP) is available from Sigma-Aldrich, Germany.

[0169] Attapulgite Clay Micro-Sorb 300 LVM (Fuller’s Earth) is available from Active Minerals International LLC, USA.

[0170] Trigonox 421 (1 ,1 ,3,3-Tetramethylbutyl peroxy-2-ethylhexanoate, CAS 22288-43-3) is available from Nouryon Functional Chemicals B.V., Netherlands. Dilauroylperoxide, tert-Amylperoxy-2-ethylhexanoate, 1 ,1 ,3,3-tetramehylbutylperoxy-2- ethylhexanoate, tert-Butylperoxy-2-ethylhexanoate and 2,2’-azodi-(2-methylbutyronitril) (AMBN, CAS 13472-08-7) are available from PERGAN GmbH, Germany.

[0171] Dimethyl 2,2'-azobis(2-methylpropionate) V-601 (CAS 2589-57-3), 2,2'-azobis(2,4- dimethylvaleronitrile) V-65 B (CAS 4419-11 -8) and 1 ,1-azobis(cyclohexanecarbonitrile) Wako V-40 (CAS 2094-98-6) are available from Fujifilm Wako Chemicals Europe GmbH, Germany. 2,2’-Azodiisobutyronitril (AIBN) and polyethylene glycol 300 (PEG 300) are available from Sigma-Aldrich, Germany.

[0172] Light stabilizer 1 of Formula (A) (2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2- hydroxy-3-(dodecyloxy- and tridecyloxy)propoxy]phenols, CAS 192662-79-6) was synthesized analogously to a procedure as described in Example 14 of US6187919 by using ethyl triphenylphosphonium bromide instead of ethyl triphenylphosphonium iodide and by eliminating the adsorption treatment step with Filtrol 4 (fuller’s earth).

[0173] Light stabilizer 2 of Formula (B) (a-[3-[3-(2 / - / -benzotriazol-2-yl)-5-(1 , 1 -dimethylethyl)-4- hydroxyphenyl]-1 -oxopropyl]-co-hydroxy-poly(oxy-1 ,2-ethanediyl, CAS 104810-48-2; Tinuvin 1130) was synthesized analogously to a procedure as described in example 117b of US6369267 by using methyl 3-[3-(benzotriazol-2-yl)-5-tert-butyl-4-hydroxy-phenyl]propanoate and polyethylene glycol 300 under solvent-free conditions.

[0174] Light stabilizer 3 of Formula (A) (2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-[(2- ethylhexyl)oxy]-2-hydroxypropoxy]-phenol, CAS 137658-79-8) was synthesized analogously to a procedure as described in Example 13 of US6187919 by using ethyl triphenylphosphonium bromide instead of tetrabutylammonium bromide under solvent-free conditions.

[0175] Color values were determined by a Lico 690 colorimeter (Hach-Lange) using 11 mm round cuvettes. The Gardner was determined according to ASTM D1544-04.

[0176] The Yellowness Index has been determined according to ASTM D 5386-93b based on CIE XYZ-tristimulus values, standard ilium inant C and a 2° standard observer.

[0177] Example 1

[0178] Light stabilizer 1 (85% in MP, 134.1 grams) was charged into a 250 mL glass flask and heated to 100°C under an inert nitrogen atmosphere. Azo radical initiator V40 (0.093 grams) was added and the mixture was stirred for 1 hour.

[0179] The transmittance measurements were recorded before adding the radical initiator (blank in table 1 ) in the visible region, i.e., at 460 nm. The efficiency of the decolorization step was determined by measuring the transmittance at 460 nm after the decolorization treatment. In Table 1 below the treatment process conditions and the transmittance value at 460 nm of the untreated and treated UV light stabilizer are summarized.

[0180] Example 2-11 : Examples 2-11 were conducted in accordance with example 1 with different radical initiators as depicted in the Table 1 below. The efficiency of the decolorization is indicated by the % transmittance values at 460 nm. High % transmittance values indicate higher decolorization of the light stabilizer and better color properties of the light stabilizer.

[0181] Table 1 :

[0182] *amounts mentioned correspond to 85% solution in MP;#transmittance measured after treatment step;**weight ratio.

[0183] As evident from the high % transmittance at 460 nm, the examples 1 -11 were decolorized to a higher extent and had better color properties than the blank example (example 0).

[0184] Example 12

[0185] Light stabilizer 2 (53.3 grams) was charged into a glass flask. Under an inert argon atmosphere the flask contents were heated to 85°C. Dilauroylperoxide (0.0313 grams) was added and the mixture was stirred for 2 hours at 85°C (light stabilizer to radical initiator weight ratio = 1703:1). The Gardner color of Light stabilizer 2 before treatment and after the decolorization step was determined by filling sample into a 11 mm round glass cuvette and performing centrifugation at 300 rotations / min for 10 min. The Gardner color was measured using a colorimeter LIGO 690 from Dr. Lange against water as reference and the results are indicated in the Table 2 below. A low Gardner color indicates less colorization and better color performance of the light stabilizer.

[0186] Table 2

[0187] The decolorized light stabilizer obtained in accordance with the present process (treatment with diauroylperoxide) yielded improved color properties.

[0188] Example 13

[0189] Light stabilizer 3 (165.6 grams) was charged into a 250 mL glass flask. Under an inert nitrogen atmosphere, ethanol 94% (41.4 grams) was added. The flask contents were heated to 75°C yielding a yellow liquid. Dilauroylperoxide (0.0087 grams) was added. After stirring for 1 hour a second portion of dilauroylperoxide (0.0087 grams) were added. After 1 hour stirring the yellowness index was determined by weighing 0.4500 - 0.5500 g of the sample into a 50 ml narrow neck flask. Butyl acetate (p.a., available from Merck, Germany) was added using an automatic burette (available from Metrohm) to make up a final concentration of 3% (w / w) and the contents are dissolved at room temperature (20 - 25°C). The Yellowness Index is measured using a colorimeter LIGO 690 from Dr. Lange and additionally transmittance value at 460 nm were measured before and after the decolorization treatment step. A low yellowness index indicate less coloration and better color properties of the light stabilizer.

[0190] Table 3

[0191] The decolorized light stabilizer obtained in accordance with the presently claimed process (treatment with diauroylperoxide) yielded improved color properties. Embodiments:

[0192] In the following, there is provided a list of embodiments to further illustrate the present disclosure without intending to limit the disclosure to the specific embodiments listed below.

[0193] 1. A process for decolorization of light stabilizer comprising: a) obtaining at least one light stabilizer of formula formula wherein

[0194] R1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,

[0195] R2is hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci- C alkoxy, hydroxyl, phenyl or C2-Cisacyloxy;

[0196] R3is hydrogen, halogen, Ci -Cisalkyl, Ci-C alkoxy, C2-Cisacyloxy, phenyl, or is Ci- Ci2fluoroalkyl;

[0197] R4is hydrogen, halogen, Ci -Cisalkyl, Ci-C alkoxy, C2-Cisacyloxy, phenyl, or is Ci-

[0198] Ci2fluoroalkyl; or

[0199] R3and R4together form a ring;

[0200] R25is hydrogen, Ci-Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or

[0201] R6is hydrogen, Ci-C24alkyl, C5-Ci2cycloalkyl, C7-Ci2phenylalkyl, or halogen;

[0202] R5and R8are independently of each other hydrogen, or Ci-C2oalkyl, especially hydrogen;

[0203] Z is hydrogen, C2-C2oalkenyl, or said C2-C2oalkenyl, substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO — ; especially Ci-C24alkyl or C5-Ci2cycloalkyl; or said Ci-C24alkyl or said C5-Ci2cycloalkyl substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO — ;

[0204] R44is Ce-C aryl, Ce-C aryl substituted by one to three halogen, Ci-Csalkyl, Ci- Csalkoxy, or combinations thereof; C5-Ci2cycloalkyl; C7-Ci2phenylalkyl, C7- Ci2phenylalkyl substituted on the phenyl ring by one to three halogen, Ci-Csalkyl, C1- Csalkoxy, or combinations thereof;

[0205] R45is defined as is R44; or R45is also hydrogen or Ci-C24alkyl;

[0206] Ar2and Ar3in formula (A) are independently of each other selected from a group of the formula (D-2), (D-3), phenyl or phenyl substituted by one to three

[0207] Ci-Cealkyl, halogen, hydroxy or Ci-Ci2alkoxy; naphthyl or naphthyl substituted by one to three Ci-Cealkyl, halogen, hydroxy or Ci-Ci2alkoxy; and

[0208] R51, R52, R53, R54and R55are independently of each other hydrogen, hydroxy, cyano, Ci-C2oalkyl, Ci-C2oalkoxy, C7-Ci2phenylalkyl, C5-Ci2cycloalkyl, C5-Ci2cycloalkyloxy, or halogen;

[0209] Z’ is as defined for Z; R6is as defined for R6, R5and R8are as defined for R5and R8, respectively; b) treating the light stabilizer of formula (A) or (B) with at least one radical initiator selected from azo radical initiators and peroxide radical initiators to obtain a decolorized light stabilizer of formula (A) or (B). The process according to embodiment 1 , wherein the azo radical initiator is selected from azo nitril initiators, azo ester initiators, azo amide initiators, azo imidazoline initiators, azo amidine initiators and macro azo initiators, such as, for example, 4,4’- azobis(4-cyanopentanoicacid) polyethyleneglycolpolymer. The process according to embodiment 2, wherein the azo radical initiator has a formula

[0210] (C), wherein

[0211] Y is selected from CN, -C(=O)ORe, wherein Reis Ci-Cealkyl; -C(=O)NHRf, wherein Rfis Ci-Cealkyl, which may optionally be substituted by -OH; -C(=NH)NH2 HCI; - C(=NH)NHRh, wherein Rhis Ci-Cealkyl, which may optionally be substituted by - C(=O)OH; 2-imidazolin-2-yl and 2-imidazolin-2-yl * hydrochloride,

[0212] Ra, Rb, Rc and Rd are independently of each other selected from Ci-Csalkyl, Ci-Csalkyl, which is substituted by -COOH, or -OR9, wherein R9is Ci-Cealkyl, and / or interrupted by -O-; C5-C8cycloalkyl, which may optionally be substituted by one, or more Ci-C4alkyl; or Ramay be bonded to Rb and / or Rcmay be bonded to Rd to form a cyclopentane, or cyclohexane ring, which may optionally be substituted by one, or more Ci-C4alkyl.

[0213] 4. The process according to embodiments 1 to 3, wherein azo radical initiator is selected from 2,2’-azobis(isobutyronitrile), 2,2’-azobis(2-methylbutyronitrile), 1 ,1 ’- azobis(cyclohexane-1 -carbonitrile), 2,2’-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2’- azobis(2-methylpropionate), 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile), 4,4’- azobis(4-cyanovaleric acid), 2,2’-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2’-azobis(N-butyl-2-methylpropionamide), 2,2’-azobis[2-(2-imidazolin-2- yl)propane]dihydrochloride, 2,2’-azobis[2-(2-imidazolin-2-yl)propane], 2,2’-azobis(2- methylpropionamidine) dihydrochloride, 2,2’-azobis[N-(2-carboxyethyl)-2- methylpropionamidine] n-hydrate, 4,4-azobis(4-cyanovaleric acid), 4,4’-azobis(4- cyanopentanoicacid) polyethyleneglycolpolymer and mixtures thereof.

[0214] 5. The process according to embodiment 1 , wherein the peroxide radical initiator is selected from dilauroyl peroxide, didecanoyl peroxide, diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2- ethylhexyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5- trimethylhexanoyl) peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane,

[0215] 1 ,1 ,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, 1 ,1 -di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1 ,1 -di(tert- amylperoxy)cyclohexane, 1 ,1 -di(tert-butylperoxy)cyclohexane, tert-amylperoxy-2- ethylhexyl carbonate, tert-amyl peroxyacetate, tert butyl peroxy-3,5,5- trimethylhexanoate, 2,2-di(tert-butylperoxy)butane, tert-butylperoxy isopropyl carbonate, tert-butylperoxy 2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert- butylperoxy)hexane, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1 ,4,7- triperoxonane, 3,6,9-triethyl-3,6,9-trimethyl-1 ,2,4,5,7,8-hexoxonane, 3,6,9-trimethyl- 3,6,9-tripropyl-1 ,2,4,5,7,8-hexoxonane, isopropylcumyl hydroperoxide, 1 ,1 ,3,3- tetramethylbutyl hydroperoxide, cumyl hydroperoxide, tert-butyl hydroperoxide, tertamyl hydroperoxide, 3,3,5,7,7-pentamethyl-1 ,2,4-trioxepane, 2,5-dimethyl-2,5-di(tert- butylperoxy)hexyne-3, tert-butyl cumyl peroxide, di(4-methylbenzoyl) peroxide, di(2,4- dichlorobenzoyl) peroxide and mixtures thereof. The process according to embodiments 1 to 5, wherein

[0216] Ar1in formula (A) is a group of the formula (D-2), wherein

[0217] Z is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;

[0218] R12is Ci -Ci salkyl or Ce-Ci2aryl or CO-Ci-Cisalkyl;

[0219] R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci-Ci2alkyl or C5-C6cycloalkyl; and

[0220] R6, R5and R8are hydrogen.

[0221] The process according to embodiments 1 to 6, wherein

[0222] Ar2and Ar3in formula (A) are independently of each other a group of the formula

[0223] (D-2), wherein

[0224] Z is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;

[0225] R12is Ci -Ci salkyl or Ce-Ci2aryl or CO-Ci-Cisalkyl;

[0226] R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci-Ci2alkyl or Cs-Cscycloalkyl; and

[0227] R6, R5and R8are hydrogen; or

[0228] Ar2and Ar3in formula (A) are independently of each other a group of the formula

[0229] (D-3), wherein Z’ is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-

[0230] R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;

[0231] R12is Ci -Ci salkyl or Ce-Ci2aryl or CO-Ci-Cisalkyl;

[0232] R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci-Ci2alkyl or C5-C6cycloalkyl; and R6, R5and R8are hydrogen; or

[0233] Ar2and Ar3in formula (A) are independently of each other phenyl or phenyl substituted by one to three Ci-Cealkyl; or

[0234] Ar2and Ar3in formula (A) are independently of each other a group of the formula

[0235] R51, R52, R53, R54and R55are hydrogen. The process according to embodiments 1 to 7, wherein

[0236] R1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,

[0237] R2is hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci-

[0238] Cisalkoxy, hydroxyl, phenyl or Ca-Cisacyloxy;

[0239] R3is hydrogen, halogen, Ci-Cisalkyl;

[0240] R4is hydrogen, and

[0241] R25is Ci -Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or substituted by OH, or by , wherein R1, R3and R4are defined above, or below. The process according to embodiments 1 to 8, wherein the light stabilizer of formula (A) or (B) has an absorption spectrum in the ultraviolet range with at least one absorption maximum Xmax in the range of 280 and 420 nm. The process according to embodiments 1 to 7 and 9, wherein the at least one light stabilizer of formula (A) is selected from 2-(4,6-diphenyl-1 ,3,5-triazin-2-yl)-5-(hexyloxy)- phenol, 2-(4,6-bis-(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl)-5-(octyloxy)-phenol, 2-[4,6- Bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol and 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3-

[0242] (tridecyloxy)propoxy]phenol, 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-[(2- ethylhexyl)oxy]-2-hydroxypropoxy]phenol, 2-[4,6-Bis([1 , 1 '-biphenyl]-4-yl)-1 ,3,5-triazin-2- yl]-5-[(2-ethylhexyl)oxy]phenol, 2-[2-hydroxy-4-(1-octyloxycarbonylethyl)oxyphenyl]-4,6- di(4-phenyl)phenyl-1 ,3,5-triazine, 2,4,6-tri(2,4-dihydroxyphenyl)-1 ,3,5-triazine, 2,4-bis[2- hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1 ,3,5-triazine, 2,2'-[6-(4- methoxyphenyl)-1 ,3,5-triazine-2,4-diyl]bis(5-((2-ethylhexyl)oxy)-phenol, 2,4,6-tris-(2'- hydroxy-4'-butoxyphenyl)-1 ,3,5-triazine, 2,2',2"-(1 ,3,5-triazine-2,4,6-triyl)tris[5- (octyloxy)phenol], 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1 ,3,5-triazine, 2- [4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3-(tridecyloxy)propoxy]- phenol, 2,4,6-tris[4-(1 -octyloxycarbonyl)ethyloxy-2-hydroxyphenyl]-1 ,3,5-triazine, 1 ,1 '- dioctyl 2 ,2'-[[4-[4, 6-bis[2-hydroxy-4-[1 -methyl-2-(octyloxy)-2-oxoethoxy]phenyl]-1 ,3,5- triazin-2-yl]-1 ,3-phenylene]bis(oxy)]bis[propanoate], 2,4-bis(2,4-dihydroxyphenyl)-6-(4- methoxyphenyl)-1 ,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1 ,3,5-triazine, 2,6- bis(2,4-dimethylphenyl)-4-(2,4-dihydroxyphenyl)-s-triazine, 4-[4,6-bis([1 ,1 '-biphenyl]-4- yl)- 1 ,3,5-triazin-2-yl]-1 ,3-benzenediol and 2,4,6-tris(2,4-dihydroxy-3-methylphenyl)-

[0243] 1 ,3,5-triazine and 2,4,6-tribiphenyl-4-yl-1 ,3,5-triazine. The process according to embodiments 1 to 5 and 8 to 10, wherein the at least one light stabilizer of formula (B) is selected from 2-(benzotriazol-2-yl)-4-methylphenol, 2- (2'-hydroxy-3',5'-di-t-butyl-phenyl)benzotriazole, 2-(5-chlor-2H-benzotriazol-2-yl)-4- methylphenol, 2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2H- benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2'-hydroxy-5'-(1 ,1 ,3,3- tetramethylbutyl)phenyl)benzotriazole, 2-(benzotriazol-2-yl)-6-butan-2-yl-4-tert- butylphenol, 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1 ,1 ,3,3- tetramethylbutyl)phenol), 2-(2H-benzotriazol-2-yl)-6-dodecyl-p-cresol, 2-(2- benzotriazolyl)-6-dodecyl-4-methylphenol, polyethylene glycol di[3-[3-(2H-benzotriazol- 2-yl)-5-tert-butyl-4-hydroxyphenyl]-1 -oxopropyl] ether, 2-(2H-benzotriazol-2-yl)-4,6- bis(1 -methyl-1 -phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-6-(1 -methyl-1 -phenylethyl)- 4-(1 ,1 ,3,3-tetramethylbutyl)phenol, 3-(2H-benzotriazol-2-yl)-5-(1 ,1 -dimethylethyl)-4- hydroxybenzenepropanoic acid, a-[3-[3-(2H-benzotriazol-2-yl)-5-(1 ,1 -dimethylethyl)-4- hydroxyphenyl]-1 -oxopropyl]-®-hydroxypoly(oxy-1 ,2-ethanediyl), octyl 3-[3-(2H- benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate, octyl 3-[3-(2H-Benzotriazol- 2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate, 6-butyl-2-[2-hydroxy-3-(2-phenyl-2- propyl)-5-(2,4,4-trimethyl-2-pentyl)phenyl]-[1 ,2,3]triazolo[4,5-f]isoindole-5,7(2H,6H)- dione, 6-butyl-2-[2-hydroxy-3-(1 -methyl-1 -phenylethyl)-5-(1 , 1 ,3,3- tetramethylbutyl)phenyl]pyrrolo[3,4-f]benzotriazole-5,7(2H,6H)-dione, octyl 3-[3-tert- butyl-5-(5-chlorobenzotriazol-2-yl)-4-hydroxyphenyl]propanoate, 2-(benzotriazol-2-yl)-4- (2,4,4-trimethylpentan-2-yl)phenol, 3-[3-(2H-benzotriazol-2-yl)-5-tert-butyl-4- hydroxyphenyl]propionic acid, methyl 3-[3-tert-butyl-5-(2H-benzotriazol-2-yl)-4- hydroxyphenyl]propionate, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate and 2-(2H-benzotriazol-2-yl)-4-methyl-6-[2-methyl-3-[1 ,3,3,3-tetramethyl-

[0244] 1 -[(trimethylsilyl)oxy]- 1 -disiloxanyl]propyl]phenol. The process according to embodiments 1 to 11 , wherein the weight ratio of light stabilizer of formula (A) or (B) to the radical initiator is in the range from 50000:1 to 50:1 , preferably from 30000:1 to 100:1. The process according to embodiments 1 to 12, wherein the step b) is carried out at a temperature > 20 °C, preferably at a temperature from 20 to 200 °C, more preferably from 40 to 160 °C, even more preferably from 60 to 120 °C. 14. A decolorized light stabilizer obtained from the process of any of the embodiments 1 to 11 , wherein the decolorized light stabilizer has a gardner color < 7.0 and is preferably characterized by a Yellowness Index Change (AYI) according to Equation 1 of > 0.5, more preferably > 1 , even more preferably in the range of from 1 .0 to 7.0: Yellowness Index Change (AYI) = Yellowness Index of the light stabilizer obtained in step b) - Yellowness Index of the light stabilizer obtained in step a) [Equation 1],

[0245] 15. A composition comprising the decolorized light stabilizer according to embodiment 14. 16. Use of the decolorized light stabilizer according to embodiment 14 as ultraviolet stabilizer. . A process of protecting a material or coating from light, wherein the process comprises a step of providing the decolorized light stabilizer according to embodiment 14 as ultraviolet stabilizer.

Claims

ClaimsA process for decolorization of light stabilizer comprising, especially consisting of: a) providing, or obtaining at least one light stabilizer of formulaformula, whereinR1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,R2is hydrogen, Ci -Cisalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci-Cisalkoxy, hydroxyl, phenyl or C2-Cisacyloxy;R3is hydrogen, halogen, Ci -Cisalkyl, Ci-C alkoxy, Ca-Cisacyloxy, phenyl, or is Ci-Ciafluoroalkyl;R4is hydrogen, halogen, Ci -Cisalkyl, Ci-C alkoxy, C2-Cisacyloxy, phenyl, or is Ci-Ci2fluoroalkyl; orR3and R4together form a ring;R25is hydrogen, Ci-Cisalkyl or C4-C5oalkyl interrupted by one or more O and / orsubstituted by OH, or by , wherein R1, R3and R4are defined above;Ar1is a group of the formula (0-2),R6is hydrogen, Ci-C24alkyl, C5-Ci2cycloalkyl, C7-Ci2phenylalkyl, or halogen;R5and R8are independently of each other hydrogen, or Ci-C2oalkyl, especially hydrogen;Z is hydrogen, C2-C2oalkenyl, or said C2-C2oalkenyl, substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO — ; especially Ci-C24alkyl or C5-Ci2cycloalkyl; or said Ci-C24alkyl or said C5-Ci2cycloalkyl substituted by one to three — R44, — OR45, — COOR45, — OCOR45and / or interrupted by one to three — O — , — COO — , — OCO — or — CO — ;R44is Ce-C aryl, Ce-Cioaryl substituted by one to three halogen, Ci-Csalkyl, Ci-Csalkoxy, or combinations thereof; C5-Ci2cycloalkyl; C7-Ci2phenylalkyl, C7-Ci2phenylalkyl substituted on the phenyl ring by one to three halogen, Ci-Csalkyl, Ci- Csalkoxy, or combinations thereof;R45is defined as is R44; or R45is also hydrogen or Ci-C24alkyl;Ar2and Ar3in formula (A) are independently of each other selected from a group of theformula (D-2), (D-3), phenyl or phenyl substituted by one to threeCi-Cealkyl, halogen, hydroxy or Ci-Ci2alkoxy; naphthyl or naphthyl substituted by one to three Ci-Csalkyl, halogen, hydroxy or Ci-Ci2alkoxy; andR51, R52, R53, R54and R55are independently of each other hydrogen, hydroxy, cyano, Ci-C2oalkyl, Ci-C2oalkoxy, C7-Ci2phenylalkyl, C5-Ci2cycloalkyl, C5-Ci2cycloalkyloxy, or halogen;Z’ is as defined for Z; R6is as defined for R6, R5and R8are as defined for R5and R8, respectively; b) treating the at least one light stabilizer of formula (A) or formula (B) with at least one radical initiator selected from azo radical initiators and peroxide radical initiators optionally in a solvent; and optionally removing the solvent; to obtain a decolorized light stabilizer of formula (A) or (B), or a suspension / solution of a decolorized light stabilizer of formula (A) or (B).

2. The process according to claim 1 , wherein the light stabilizer (A), or (B) are commercially available in the form of a suspension / solution; i.e. are provided in the form of a suspension / solution and (b) the suspension / solution of the light stabilizer of formula (A) or (B) is treated before sale with at least one radical initiator selected from azo radical initiators and peroxide radical initiators to obtain a suspension / solution of a decolorized light stabilizer of formula (A) or (B).

3. The process according to claim 1 , or 2, wherein the azo radical initiator is selected from azo nitril initiators, azo ester initiators, azo amide initiators, azo imidazoline initiators, azo amidine initiators and macro azo initiators, such as, for example, 4,4’-azobis(4- cyanopentanoicacid) polyethyleneglycolpolymer.

4. The process according to claim 3, wherein the azo radical initiator has a formula(C), whereinY is selected from CN, -C(=O)ORe, wherein Reis Ci-Cealkyl; -C(=O)NHRf, wherein Rfis Ci-Cealkyl, which may optionally be substituted by -OH; -C(=NH)NH2* HCI; - C(=NH)NHRh, wherein Rhis Ci-Cealkyl, which may optionally be substituted by - C(=O)OH; 2-imidazolin-2-yl and 2-imidazolin-2-yl * hydrochloride,Ra, Rb, Rc and Rd are independently of each other selected from Ci-Csalkyl, Ci-Csalkyl, which is substituted by -COOH, or -OR9, wherein R9is Ci-Cealkyl, and / or interrupted by -O-; Ce-Cscycloalkyl, which may optionally be substituted by one, or more Ci-C4alkyl; or Ramay be bonded to Rb and / or Rcmay be bonded to Rd to form a cyclopentane, or cyclohexane ring, which may optionally be substituted by one, or more Ci-C4alkyl.

5. The process according to claims 1 to 4, wherein azo radical initiator is selected from 2,2’-azobis(isobutyronitrile), 2,2’-azobis(2-methylbutyronitrile), 1 ,1 ’-azobis(cyclohexane- 1 -carbonitrile), 2,2’-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2’-azobis(2- methylpropionate), 2,2’-azobis(4-methoxy-2,4-dimethylvaleronitrile), 4,4’-azobis(4- cyanovaleric acid), 2,2’-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2’- azobis(N-butyl-2-methylpropionamide), 2,2’-azobis[2-(2-imidazolin-2- yl)propane]dihydrochloride, 2,2’-azobis[2-(2-imidazolin-2-yl)propane], 2,2’-azobis(2- methylpropionamidine) dihydrochloride, 2,2’-azobis[N-(2-carboxyethyl)-2- methylpropionamidine] n-hydrate, 4,4-azobis(4-cyanovaleric acid), 4,4’-azobis(4- cyanopentanoicacid) polyethyleneglycolpolymer and mixtures thereof.

6. The process according to claim 1 , wherein the peroxide radical initiator is selected from dilauroyl peroxide, didecanoyl peroxide, diisobutyryl peroxide, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, di-sec-butyl peroxydicarbonate, diisopropyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, di(2- ethylhexyl) peroxydicarbonate, tert-butyl peroxyneodecanoate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1 ,1 ,3,3-tetramethylbutyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5- trimethylhexanoyl) peroxide, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane,1 ,1 ,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-amyl peroxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisobutyrate, 1 ,1 -di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1 ,1 -di(tert- amylperoxy)cyclohexane, 1 ,1 -di(tert-butylperoxy)cyclohexane, tert-amylperoxy-2- ethylhexyl carbonate, tert-amyl peroxyacetate, tert butyl peroxy-3,5,5- trimethylhexanoate, 2,2-di(tert-butylperoxy)butane, tert-butylperoxy isopropyl carbonate, tert-butylperoxy 2-ethylhexyl carbonate, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1 ,4,7- triperoxonane, 3,6,9-triethyl-3,6,9-trimethyl-1 ,2,4,5,7,8-hexoxonane, 3,6,9-trimethyl- 3,6,9-tripropyl-1 ,2,4,5,7,8-hexoxonane, isopropylcumyl hydroperoxide, 1 , 1 ,3,3- tetramethylbutyl hydroperoxide, cumyl hydroperoxide, tert-butyl hydroperoxide, tertamyl hydroperoxide, 3,3,5,7,7-pentamethyl-1 ,2,4-trioxepane, 2,5-dimethyl-2,5-di(tert- butylperoxy)hexyne-3, tert-butyl cumyl peroxide, di(4-methylbenzoyl) peroxide, di(2,4- dichlorobenzoyl) peroxide and mixtures thereof.

7. The process according to claims 1 to 6, whereinAr1in formula (A) is a group of the formula (D-2), whereinZ is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;R12is Ci -Ci salkyl or Ce-Ci2aryl or CO-Ci-Cisalkyl;R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci-Ci2alkyl or C5-C6cycloalkyl; andR6, R5and R8are hydrogen.

8. The process according to claims 1 to 7, whereinAr2and Ar3in formula (A) are independently of each other a group of the formula(D-2), whereinZ is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;R12is Ci -Ci salkyl or Ce-Ci2aryl or CO-Ci-Cisalkyl;R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci -Ci2alkyl or Cs-Cscycloalkyl; andR6, R5and R8are hydrogen; orAr2and Ar3in formula (A) are independently of each other a group of the formula(D-3), wherein Z’ is (CH2-CH2-O-)ni-R12; -CH2-CH(OH)-CH2-O-R12; or -CH(R13)-CO-O-R14; n1 is 0 or 1 ;R12is Ci -Ci salkyl or C6-Ci2aryl or CO-Ci-Cisalkyl;R13is H or Ci-Csalkyl; R14is C2-Ci2alkenyl, especially Ci-Ci2alkyl or C5-C6cycloalkyl; andR6, R5and R8are hydrogen; orAr2and Ar3in formula (A) are independently of each other phenyl or phenyl substituted by one to three Ci-Cealkyl; orAr2and Ar3in formula (A) are independently of each other a group of the formula; whereinR51, R52, R53, R54and R55are hydrogen.

9. The process according to claims 1 to 8, whereinR1is hydrogen, Ci -Cisalkyl, or Ci -Cisalkyl which is substituted by phenyl,R2is hydrogen, Ci-Ciaalkyl, or is Ci -Cisalkyl which is substituted by COOR25, Ci-Cisalkoxy, hydroxyl, phenyl or C2-Cisacyloxy;R3is hydrogen, halogen, Ci-Ciaalkyl;R4is hydrogen, andR25is Ci -Cisalkyl or C4-C5oalkyl interrupted by one or more O and / or substituted by OH,or by , wherein R1, R3and R4are defined above, or below.

10. The process according to claims 1 to 8, wherein the light stabilizer of formula (A) or (B) has an absorption spectrum in the ultraviolet range with at least one absorption maximum max in the range of 280 and 420 nm.11 . The process according to claims 1 to 8 and 10, wherein the at least one light stabilizer of formula (A) is selected from 2-(4,6-diphenyl-1 ,3,5-triazin-2-yl)-5-(hexyloxy)-phenol, 2- (4,6-bis-(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl)-5-(octyloxy)-phenol, 2-[4,6-Bis(2,4- dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol and 2- [4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3- (tridecyloxy)propoxy]phenol, 2-[4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[3-[(2- ethylhexyl)oxy]-2-hydroxypropoxy]phenol, 2-[4,6-Bis([1 , 1 '-biphenyl]-4-yl)-1 ,3,5-triazin-2- yl]-5-[(2-ethylhexyl)oxy]phenol, 2-[2-hydroxy-4-(1-octyloxycarbonylethyl)oxyphenyl]-4,6- di(4-phenyl)phenyl-1 ,3,5-triazine, 2,4,6-tri(2,4-dihydroxyphenyl)-1 ,3,5-triazine, 2,4-bis[2- hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1 ,3,5-triazine, 2,2'-[6-(4- methoxyphenyl)-1 ,3,5-triazine-2,4-diyl]bis(5-((2-ethylhexyl)oxy)-phenol, 2,4,6-tris-(2'- hydroxy-4'-butoxyphenyl)-1 ,3,5-triazine, 2,2',2"-(1 ,3,5-triazine-2,4,6-triyl)tris[5-(octyloxy)phenol], 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1 ,3,5-triazine, 2- [4,6-bis(2,4-dimethylphenyl)-1 ,3,5-triazin-2-yl]-5-[2-hydroxy-3-(tridecyloxy)propoxy]- phenol, 2,4,6-tris[4-(1 -octyloxycarbonyl)ethyloxy-2-hydroxyphenyl]-1 ,3,5-triazine, 1 ,1 '- dioctyl 2 ,2'-[[4-[4, 6-bis[2-hydroxy-4-[1 -methyl-2-(octyloxy)-2-oxoethoxy]phenyl]-1 ,3,5- triazin-2-yl]-1 ,3-phenylene]bis(oxy)]bis[propanoate], 2,4-bis(2,4-dihydroxyphenyl)-6-(4- methoxyphenyl)-1 ,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-diphenyl-1 ,3,5-triazine, 2,6- bis(2,4-dimethylphenyl)-4-(2,4-dihydroxyphenyl)-s-triazine, 4-[4,6-bis([1 ,1 '-biphenyl]-4- yl)- 1 ,3,5-triazin-2-yl]-1 ,3-benzenediol and 2,4,6-tris(2,4-dihydroxy-3-methylphenyl)- 1 ,3,5-triazine and 2,4,6-tribiphenyl-4-yl-1 ,3,5-triazine.

12. The process according to claims 1 to 6 and 9 to 10, wherein the at least one light stabilizer of formula (B) is selected from 2-(benzotriazol-2-yl)-4-methylphenol, 2-(2'- hydroxy-3',5'-di-t-butyl-phenyl)benzotriazole, 2-(5-chlor-2H-benzotriazol-2-yl)-4- methylphenol, 2-(2'-Hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2H- benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2'-hydroxy-5'-(1 ,1 ,3,3- tetramethylbutyl)phenyl)benzotriazole, 2-(benzotriazol-2-yl)-6-butan-2-yl-4-tert- butylphenol, 2,2'-methylenebis(6-(2H-benzotriazol-2-yl)-4-(1 ,1 ,3,3- tetramethylbutyl)phenol), 2-(2H-benzotriazol-2-yl)-6-dodecyl-p-cresol, 2-(2- benzotriazolyl)-6-dodecyl-4-methylphenol, polyethylene glycol di[3-[3-(2H-benzotriazol- 2-yl)-5-tert-butyl-4-hydroxyphenyl]-1 -oxopropyl] ether, 2-(2H-benzotriazol-2-yl)-4,6- bis(1 -methyl-1 -phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-6-(1 -methyl-1 -phenylethyl)- 4-(1 ,1 ,3,3-tetramethylbutyl)phenol, 3-(2H-benzotriazol-2-yl)-5-(1 ,1 -dimethylethyl)-4- hydroxybenzenepropanoic acid, a-[3-[3-(2H-benzotriazol-2-yl)-5-(1 ,1 -dimethylethyl)-4- hydroxyphenyl]-1 -oxopropyl]-w-hydroxypoly(oxy-1 ,2-ethanediyl), octyl 3-[3-(2H- benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate, octyl 3-[3-(2H-Benzotriazol- 2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate, 6-butyl-2-[2-hydroxy-3-(2-phenyl-2- propyl)-5-(2,4,4-trimethyl-2-pentyl)phenyl]-[1 ,2,3]triazolo[4,5-f]isoindole-5,7(2H,6H)- dione, 6-butyl-2-[2-hydroxy-3-(1 -methyl-1 -phenylethyl)-5-(1 , 1 ,3,3- tetramethylbutyl)phenyl]pyrrolo[3,4-f]benzotriazole-5,7(2H,6H)-dione, octyl 3-[3-tert- butyl-5-(5-chlorobenzotriazol-2-yl)-4-hydroxyphenyl]propanoate, 2-(benzotriazol-2-yl)-4- (2,4,4-trimethylpentan-2-yl)phenol, 3-[3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionic acid, methyl 3-[3-tert-butyl-5-(2H-benzotriazol-2-yl)-4- hydroxyphenyl]propionate, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate and 2-(2H-benzotriazol-2-yl)-4-methyl-6-[2-methyl-3-[1 ,3,3,3-tetramethyl- 1 -[(trimethylsilyl)oxy]- 1 -disiloxanyl]propyl]phenol.

13. The process according to claims 1 to 12, wherein the weight ratio of light stabilizer of formula (A) or (B) to the radical initiator is in the range from 50000:1 to 50:1 , preferably from 30000:1 to 100:1.

14. The process according to claims 1 to 13, wherein the step b) is carried out at a temperature > 20 °C, preferably at a temperature from 20 to 200 °C, more preferably from 40 to 160 °C, even more preferably from 60 to 120 °C.

15. A decolorized light stabilizer obtained from the process of any of the claims 1 to 14, wherein the decolorized light stabilizer has a gardner color < 7.0 and is preferably characterized by a Yellowness Index Change (AYI) according to Equation 1 of > 0.5, more preferably > 1 , even more preferably in the range of from 1 .0 to 7.0:Yellowness Index Change (AYI) = Yellowness Index of the light stabilizer obtained in step b) - Yellowness Index of the light stabilizer obtained in step a) [Equation 1],16. A composition comprising the decolorized light stabilizer according to claim 15.

17. Use of the decolorized light stabilizer according to claim 15 as ultraviolet stabilizer.

18. A process of protecting a material or coating from light, wherein the process comprises a step of providing the decolorized light stabilizer according to claim 15 as ultraviolet stabilizer.

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