Flame retardant articles comprising polypropylene

Abstract

The invention concerns an article, the article being a film or a fibre or a tape, comprising a flame-retardant polypropylene polymer composition which comprises the components: (i) a polypropylene polymer substrate; and (ii) a thio compound of formula (I); and either or both of (iii) at least one sterically hindered amine ether; and / or (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite, (I) wherein A is based on an organic isocyanate or a (meth)acrylate, wherein the radical(s) -S–R are introduced by reaction with isocyanate groups or (meth)acrylate groups, R is C2-C40 alkyl which is optionally substituted and / or interrupted, and n is equal to or greater than 1. The invention also includes a method for preparing the article. Also claimed is use of (ii) a thio compound of formula (I) in conjunction with either or both of (iii) at least one sterically hindered amine ether and / or (iv) at least one phosphorus compound, the phosphorus compound being at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite. The invention further includes an additive mixture comprising these three components and also a composition comprising the additive mixture and a polypropylene polymer substrate (i).

Description

[0001] Flame retardant articles comprising polypropylene

[0002] Field of the Invention

[0003] The present invention is in the field of flame-retardant articles that comprise polypropylene polymer. The invention concerns an article, the article being a film or a fibre or a tape, which comprises a flame-retardant polypropylene polymer composition comprising a polypropylene polymer substrate; a thio compound of formula (I); and either or both of at least one sterically hindered amine ether; and / or at least one phosphorus compound, the phosphorus compound being at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite. The invention further concerns a method for preparing the article and the use of the thio compound in conjunction with the sterically hindered amine ether and / or aforesaid phosphorus compound for improving the flame retardancy of a polypropylene based article. In addition, the invention includes an additive mixture comprising the aforesaid thio compound and at least one sterically hindered amine ether and / or at least one aforesaid phosphorus compound. The invention also includes a composition comprising a polypropylene polymer substrate and the said additive mixture.

[0004] Background of the Invention

[0005] Polypropylene is a thermoplastic polymer and has different applications, for instance components in automobiles, automotive products, textiles, medicine, furniture, electronic casings and interior decoration are just a few examples. Polypropylene, like other organic substances, including polyolefins, is a flammable material.

[0006] It is therefore typical to render polypropylene more flame retardant by the addition of additives which reduce or prevent combustion. Flame retardant additives found to be effective for polypropylene include halogenated compounds, such as bromine or chlorine, which are commonly used for polypropylene. When exposed to fire, these halogenated compounds undergo chemical reactions that release gas, such as hydrogen bromide or hydrogen chloride. This can have the effect of diluting the oxygen concentration in the combustion zone and therefore inhibiting flame propagation. Further, such halogen-containing gases can act as free radical scavengers which can serve the purpose of interrupting the chain reactions that sustain the combustion process.

[0007] Other known flame retardants commonly used for polypropylene include phosphorus-based compounds. Such phosphorus-containing compounds can undergo thermal decomposition when exposed to high temperatures and can form protective charred layers over the surface of the polypropylene which in effect acts as a barrier that will shield material below it from heat and flames. Such an insulating layer would have the benefit of reducing heat transfer and preventing further flame propagation.

[0008] Further, other classes of compounds are proposed to function in the condensed and / or vapour phase. Metal hydrates or metal oxides are proposed to generate water vapour under thermal conditions, the water acting to dilute the fuel mix in the combustion zone and to remove heat from the flame zone via conversion of water to vapour. Alumina trihydrate, magnesium hydroxide or oxide, and other compounds are reported to function in this way.

[0009] It is also common practice to combine halogenated compounds and phosphorus-based additives to improve flame retardancy of polypropylene. Such combination is said to combine the benefits of each additive.

[0010] International Application No W02007010318 A discloses flame retardant thermoplastic moulding compositions comprising polyolefinic polymer particularly polypropylene polymers, a synergic mixture of a hypophosphorous acid metal salt and halogenated organic compounds, a plurality of selected additives consisted of processing aids, heat and process stabilisers, UV stabilisers, anti-dripping agents etc.

[0011] It is also known to employ halogenated organic phosphorus compounds as flame retardants. United States Patent No. US5393812 describes polyolefin compositions which are made flame retardant by a combination of a halogenated hydrocarbyl phosphate or phosphonate ester flame retardant in combination with an alkoxyamine functional hindered amine. European Patent Application No EP0792911 A discloses that alkoxyamine functional hindered amines are effective when used to enhance the flame retardancy efficacy of tris(trihalogenopentyl) phosphate flame retardants.

[0012] The use of the halogenated flame retardants can, however, have various detrimental consequences in addition to the effective flame retarding attributes described. Certain organo-brominated compounds are under governmental scrutiny for the generation of toxic byproducts during the production or combustion such as dioxins from polybrominated diphenyl oxides. Furthermore, there is a desire to move away from halogenated flame retardants to avoid the generation of corrosive hydrogen halide gases. The use of certain metal oxides can also be disadvantageous. Certain metalcontaining flame retardants, notably antimony oxides often contain trace amounts of arsenic compounds which are suspected carcinogens. Overall, there is a growing concern regarding the generation of smoke and toxic gases which are involved from these flame retardants during a fire. While such a retardant may be effective combustion suppressant, the toxic gases form and pose a threat to human exposure.

[0013] Other known additives for improving the flame retardancy of polypropylene include amine base compounds, particularly sterically hindered amines, for instance hindered amine esters and hindered amine ethers. Hindered amine compounds may also be used in combination with phosphorus-based flame-retardant additives.

[0014] United States Patent No US 6117995 discloses that certain N-alkoxy hindered amines may be used as flame retardants for organic polymers.

[0015] US2019 / 010308 A1 discloses a flame-retardant article including a polyolefin substrate having incorporated a specific phosphonate ester and a synergist including an N-alkoxy hindered amine, and a melamine cyanurate as an additive.

[0016] US2017 / 0226321 A1 describes a polyolefin photovoltaic backsheets that comprises a polypropylene layer stabilized with at least one hindered amine with 2, 2,6,6-tetraalkylpiperdine or 2,2,6,6-tetraakylpiperazinone, either or both in combination with a triazine moiety, (B) a thioester, and, optionally, (C) at least one hindered hydroxybenzoate, and / or (D) an ortho hydroxyl triazine compound. Such PV backsheets exhibit a low flame spread index of <100 without the need of flame retardant agents.

[0017] International Application No WO02774847 A describes a method of flame retarding a polymeric substrate by adding an effective flame retarding amount of a mixture of a synergist compound and a known organic or inorganic flame retardant. The synergists are selected from nitroxyl stabilisers, hydroxylamine stabilisers, nitrone stabilisers, substituted hydroxylamine stabilisers, benzofuranone stabilisers, phosphate, phosphonite stabilisers, quinone methide stabilisers and monoacrylate esters of 2,2’-alkylidenebisphenol stabilisers.

[0018] International Application No W003750175 A describes organic polymeric substrates, for example polyolefins such as polypropylene, can be made flame retardant by the incorporation of a synergistic mixture of at least one low molecular weight sterically hindered alkoxyamine stabiliser, at least one high molecular weight sterically hindered alkoxyamine stabiliser and at least one conventional flame retardant selected from the group of organohalogen, phosphorus-containing and melamine based flame retardants. The compositions are said to combine good flame retardancy with properties with light stability and good mechanical properties.

[0019] In halogen free flame-retardant systems for polyolefins and in particular polypropylene in the form of filaments or thin layers, such as thin films, there is a need to improve the performance of nitrogen-based N-alkoxyl hindered amines and / or organic phosphorus-based flame with and products to achieve lower burning times or reduce burning damage to polypropylene as filaments or thin layers.

[0020] Improving the flame retardancy of polypropylene articles such as filaments or thin layers tends to be problematic in view of the inherent flammability of polypropylene and as a filament or thin layer there is a large surface area to mass ratio and there is a tendency for flames to travel very quickly along the filaments or thin layers thus resulting in large lengths or areas of polypropylene being consumed very quickly, which is also further exacerbated by the melting and dripping effect of the polymer. Thus, there is a need to find a flame retardancy additive which will satisfactorily improve the flame retardancy of films, fibres or tapes of compositions comprising polypropylene. Further, it would be desirable for such flame retardancy to be improved compared to the state-of-the-art flame-retardant additives employed for films, fibres or tapes that comprise polypropylene and / or provide improvements in relation to doses or concentrations of the flame-retardant additives employed. Furthermore, it would be more desirable for such flame-retardant additives to be also halogen free.

[0021] International Application No WO2021170615A describes the combination of selected hydroxylamine esters and selected isocyanates which are functionalised with thio compounds and is said to show a significant synergistic effect, for providing excellent degradation of performance even at low temperatures. Disclosed is a composition comprising a first component directed to compounds based on formulae covering N-alkoxyl hindered amine compounds, which are N-alkoxyl hindered amine esters and a second component which is represented by formula corresponding largely formula I of the present invention where A is based on an organic isocyanate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups. A third component of the composition is a polymeric substrate. Preferred polymeric substrates are said to be thermoplastic polymers, more preferably a polyolefin, polyester, polyamide, polyvinyl chloride, polyimide, polyacrylonitrile, polycarbonate or polystyrene polymer, especially a polyolefin. Polyolefins are said to include polyethylene and polypropylene.

[0022] Unexpectedly, it has been found that by combining (ii) a compound of formula (I), notably containing the radical(s) -S–R introduced by reaction with isocyanate groups or (meth)acrylate groups and either or both of (iii) at least one sterically hindered amine ether and / or (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite, with (i) a polypropylene polymer substrate that improved flame retardancy performance and / or dose efficiency of the sterically hindered amine ether and / or phosphorus compound can be achieved for polypropylene based film, fibre or tape articles. Furthermore, the present invention can avoid at least some of the aforementioned disadvantages of the prior art. Summary of the Invention

[0023] A first aspect of the present invention relates to an article, the article being a film or a fibre or a tape, comprising a flame-retardant polypropylene polymer composition which comprises the components,

[0024] (i) a polypropylene polymer substrate; and

[0025] (ii) a thio- compound of formula (I);

[0026] and either or both of

[0027] (iii) at least one sterically hindered amine ether; and / or

[0028] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite,

[0029]

[0030] wherein

[0031] A is based on an organic isocyanate or a (meth)acrylate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups or (meth)acrylate groups,

[0032] R is C2-C40alkyl which is optionally substituted and / or interrupted, and

[0033] n is equal to or greater than 1.

[0034] A further aspect of the present invention defines a method for preparing the aforesaid article comprising a flame-retardant polypropylene polymer composition comprising introducing

[0035] a thio- compound (ii) of formula (I) as defined in this specification; and either or both of at least one sterically hindered amine ether (iii) or at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite into a polypropylene polymer substrate (i),

[0036] and then processing the so formed mixture into the article, the article being a film or a fibre or a tape.

[0037] A still further aspect of the present invention is directed to the use of a thio compound (ii) of formula (I) as defined in this specification; and either or both of at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite

[0038] for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape.

[0039] A yet further aspect of the present invention concerns an additive mixture, for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape, wherein the additive mixture comprises the components,

[0040] (ii) a thio compound of formula (I); and either or both of

[0041] (iii) at least one sterically hindered amine ether; and / or

[0042] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite,

[0043] wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4alkyl) amino, or is C4-C20alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol, preferably wherein the additive mixture is in the form of a masterbatch.

[0044] In a preferred embodiment the present invention defines a composition comprising a polymer substrate (i) and the aforesaid additive mixture.

[0045] Detailed Description of the Invention

[0046] In the below description, further explanations to the present disclosure are made with reference to embodiments so as to facilitate sufficient understanding for skilled person in the art. It should be understood that these embodiments are provided merely for better understanding the subject matter of the present disclosure, not for making any limitations to the protection scope, applicability or embodiments as described in the present claims set. It should be understood that the skilled person in the art can omit, replace, or add various technical features to each embodiment based on actual needs, subject to the premise of without departing from the spirit of the present disclosure. In addition, technical features described in some embodiments can be combined with technical features described in other embodiments.

[0047] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by skilled person in the art to which the present disclosure belongs.

[0048] In the present disclosure, terms "comprise", “comprising”, “include”, “including” and various variants thereof can be understood as open-ended terms, which means "include but are not limited to"; in contrast, the term "consisting of” and various variants thereof excludes any component, step or procedure not specifically listed; the term "an embodiment" can be understood as "at least one embodiment"; the term "another embodiment" may be understood as "at least one other embodiment." Other terms that may appear but are not mentioned here, unless explicitly stated, should not be interpreted or limited in a manner that is contrary to the concept on which the embodiments of the present disclosure are based.

[0049] Throughout the present disclosure, expressions "a", "an", "the" and “one or more” are used interchangeably and are intended to include both the plural and the singular except in cases where the singular alone is explicitly specified or is clearly indicated by the context. When the singular alone is intended for, the term “one” is typically used. The term "or" is generally intended to include the sense of "and / or" unless the content clearly dictates otherwise. “Preferred”, “preferable” and “preferably” as used herein refer to embodiments of the present disclosure that may bring certain advantages under certain situations. However, other embodiments may also be preferred, under the same situations. Further, the recitation of one or more preferred embodiments does not mean that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the present disclosure.

[0050] All percentages, ppm, parts and ratios are by weight, unless otherwise specified. And the recitation of numerical ranges by end values includes all numbers subsumed within that range (e.g., 5 to 10 includes 5, 5.1, 5.2, 5.5, 5.6, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10). In the context of the present disclosure, any specific values mentioned for a feature (comprising the specific values mentioned in a range as the end point) can be recombined to form a new range.

[0051] This detailed description and all of the embodiments described herein apply to all of the aspects of the present invention, for instance as set out in the summary of the invention.

[0052] Component (ii) being a thio compound of formula (I) is defined as follows

[0053]

[0054] wherein

[0055] A is based on an organic isocyanate or a (meth)acrylate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups or (meth)acrylate groups,

[0056] R is C2-C40alkyl which is optionally substituted and / or interrupted, and

[0057] n is equal to or greater than 1.

[0058] In one embodiment, A is based on an organic isocyanate, preferably A is based on an organic isocyanate, which is a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4alkyl)amino, or is C4-C20alkyl diisocyanate, or an oligomeric or polymeric product obtained by reaction of the above diisocyanates with themselves and / or with a polyol.

[0059] More desirably, A is based on an organic isocyanate, which is a phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl)amino, or an oligomeric or polymeric product obtained by reaction of the above diisocyanates with themselves and / or with a polyol. It is highly desired that A is based on an organic isocyanate, which is a phenyl diisocyanate which is unsubstituted or substituted by C1-C4 alkyl, or an oligomeric or polymeric product obtained by reaction of the above diisocyanates with themselves and / or with a polyol.

[0060] It is more highly desired that A is based on toluene-2,4-diisocyanate or toluene-2,6-diisocyanate, or an oligomeric or polymeric product obtained by reaction of the above diisocyanates with themselves and / or with a polyol.

[0061] Examples of products obtained by reaction of the above diisocyanates with themselves are the following reaction products of three equivalents of toluene-2,4-diisocyanate or toluene-2,6-diisocyanate, respectively:

[0062]

[0063]

[0064] (XIII).

[0065] Examples of products obtained by reaction of the above diisocyanates with polyols are the following reaction products of toluene-2,4-diisocyanate or toluene-2,6-diisocyanate, respectively, with a polyol of formula HO-CH2-C(CH2-OH)2-CH2-CH3:

[0066]

[0067] (XIV),

[0068]

[0069] (XV).

[0070] A further example of a product obtained by reaction of the above diisocyanates with polyols is the following reaction product of toluene-2,4-diisocyanate with a polyol of formula HO-CH2-CH2-O-CH2-CH2-OH (diethylene glycol), represented by formula (XXX):

[0071]

[0072] In a further embodiment, A is based on an acrylate or a methacrylate, suitably the acrylate or methacrylate is an ester, desirably an ester of a polyol. Examples of acrylate or methacrylate esters with a polyol of formula HO-CH2-C(CH2- OH)3, i.e. pentaerythritol are:

[0073]

[0074] (XVII)

[0075] Examples of acrylate or methacrylate esters with a polyol of formula HO-CH2-C(CH2- OH)2-CH2-CH3 are:

[0076]

[0077] (XVIII)

[0078]

[0079] In the present invention the polyol is preferably C1-C10 alkanol comprising two or more hydroxy groups, or a poly-C2-C10alkylene glycol.

[0080] Preferred as C1-C10 alkanol for the polyols are those which are substituted by two to four, especially two or three, hydroxy groups. Particularly preferred is C2-C10 alkanol, especially C2-C6 alkanol, which are correspondingly substituted by hydroxy groups. Highly preferred is the polyol of formula HO-CH2-C(CH2-OH)2-CH2-CH3.

[0081] Preferred as poly-C2-C10 alkylene glycol is poly-C2-C6 alkylene glycol, especially those of formula

[0082]

[0083] wherein y is a number from 2 to 600, especially from 2 to 200 and most preferably from 2 to 100. Highly preferred is a number from 2 to 50, especially 2 to 20.

[0084] As to formula (XX), preference is given to corresponding polyethylene glycol or polypropylene glycol.

[0085] Preferably, the polyol is C2-C6alkanol, which is substituted by two to four hydroxy groups, or poly-C2-C6alkylene glycol, especially such of formula (XX).

[0086] In case of a reaction of the diisocyanates with themselves, or the reaction of different types of diisocyanates with themselves, this can result in mixtures of different oligomers or polymers, and in case of the additional reaction with polyols even more complex mixtures can be obtained.

[0087] Corresponding organic isocyanates are known or can be obtained according to known processes, for example from WO 05 / 070987.

[0088] Corresponding acrylates or methacrylates are known or can be obtained according to known processes, for example International Application No. PCT / CN 2024 / 113293, unpublished at the date of filing.

[0089] R can, for example, be interrupted by -O-, -NH-, -S- and / or a carbonyl group. A possible substituent for R is -SH. Corresponding C8-C40alkyl, desirably C8-C30alkyl, more desirably C12-C25alkyl is preferred.

[0090] R is preferably C2-C40alkyl, desirably C8-C30alkyl, more desirably C12-C25alkyl, which is uninterrupted or interrupted by -O-, -NH-, -S- and / or a carbonyl group, especially by -0- and / or a carbonyl group.

[0091] Particularly preferably R is C8-C40alkyl, desirably C8-C30alkyl, more desirably C10-C25alkyl, which is uninterrupted or interrupted by -0- and / or a carbonyl group, particularly by -0- and a carbonyl group, more particularly an ester group. One particular embodiment R is C10-C25alkyl which is interrupted by an ester group. In another particular embodiment R is C10-C25alkyl which is uninterrupted.

[0092] In one form of the invention the compounds of formula (I) are obtainable by reaction of an organic isocyanate with thiols of formula

[0093] H-S-R (XXI),

[0094] wherein for R the above definitions and preferences apply.

[0095] The radical(s) -S-R are introduced by reaction with isocyanate groups of the organic isocyanate, and in the reaction product are bonded as groups of formula

[0096]

[0097] (XXII),

[0098] wherein R is as defined above.

[0099] In view of the above, the term “isocyanates functionalized with thio compounds” relates to corresponding thiourethanes.

[0100] Suitable thio compounds according to formula (I) based on the products obtained by reaction of diisocyanates with themselves include the addition product of the compound of formula (XII) with octadecyl 3-mercaptopropanoate, illustrated in the molecular structure shown by formula (XXVIII).

[0101]

[0102] (XXVIII)

[0103] The compound according to formula (XXVIII) may be prepared in accordance with the Synthesis Example 4 of International Publication No. WO 2021 / 170615. A further thio compound according to formula (I) based on the products obtained by reaction of diisocyanates with themselves is the addition product of the compound of formula (XII) with octadecylthiol, illustrated in the molecular structure shown by formula (XXIX).

[0104] (XXIX)

[0105]

[0106] The compound according to formula (XXIX) may be prepared according to the Synthesis Example 5 of International Publication No. WO 2021 / 170615.

[0107] Preferred examples of suitable compounds of formula (I) based on the structure shown by formula (XXII), being isocyanates functionalised with thio compounds i.e. a thiourethane, includes the compound having the molecular structure illustrated by formula (XXIII).

[0108]

[0109] (XXIII)

[0110] Compound of formula (XXIII) may be obtained by the preparation procedure described in Synthesis Example 6 of International Application Publication No. WO 2021 / 170615A1.

[0111] The above process for the preparation of the compounds of formula (I) is typically, as a rule, carried out in presence of catalysts, like tertiary amines, for example triethylene diamine, dimethylpiperazine, dimethylethanolamine, 1,4-diazabicyclo[2.2.2]octane or 1,8-diazabicyclo[5,4,0]undec-7-ene, or with tin compounds as catalysts, for example dibutyl tin dilaurate. Triethylamine is preferred. The catalyst is, for example, used in an amount of 0.1 to 10 weight-%, based on the weight of the organic isocyanate.

[0112] The reaction is usually carried out in presence of an organic solvent, like tetrahydrofuran or ethyl acetate, and at temperatures of, for example 30 to 80°C.

[0113] Another suitable compound of formula (I) based on the structure shown by formula (XXII) is illustrated by the compound having the molecular structure illustrated by formula (XXXII).

[0114]

[0115] (XXXII)

[0116] Compound of formula (XXXII) may be prepared by the reaction of the compound of formula (XIV) with octadecylthiol. The synthesis of compound of formula (XXXII) is given in Synthesis Example 7 of International Publication No. WO 2021 / 170615.

[0117] A further suitable thio compound according to formula (I) is the addition product of octadecyl 3-mercaptopropanoate with the diisocyanate compound of formula (XXX), said addition product having the molecular structure according to formula (XXXI).

[0118]

[0119] The compound of formula (XXXI) may be prepared by the reaction of the compound of formula (XXX) with octadecyl 3-mercaptopropanoate analogously to the synthesis method provided for the compound of formula (XXIII) and the subsequent two paragraphs, including the general description of International Publication No. WO 2021 / 170615.

[0120] Another desirable thio compound according to formula (I) is the addition product of octadecylthiol with toluene-2,4-diisocyanate, said addition product having the molecular structure according to formula (XXVI).

[0121]

[0122] (XXVI) The compound of formula (XXVI) may be prepared by the method described in Synthesis Example 1 of International Publication No. WO 2021 / 170615.

[0123] A further desirable thiol compound according to formula (I) the addition product of octadecyl 3-mercaptopropanoate with toluene-2,4-diisocyanate, said addition product having the molecular structure according to formula (XXVII).

[0124]

[0125] (XXVII)

[0126] The compound according to formula (XXVII) may be prepared by the method described in Synthesis Example 3 of International Publication No. WO 2021 / 170615, except replacing the said isomer mixture by solely toluene-2,4-diisocyanate.

[0127] A yet further desirable thiol compound is an isomer mixture of the compound according to formula (XXVII) and the compound according to formula (XXXIII).

[0128]

[0129] The isomer mixture may more desirably comprise about 80 weight-% of the compound of formula (XXVII) and about 20 weight-% of the compound of formula (XXXIII). This isomer mixture may be prepared according to the description given in Synthesis Example 3 of International Publication No. WO 2021 / 170615.

[0130] In an alternative form of the invention the compounds of formula (I) are obtainable by reaction of an acrylate or methacrylate with thiols of formula

[0131] H-S-R (XXI),

[0132] wherein for R the above definitions and preferences apply.

[0133] The radical(s) -S-R are obtainable by the reaction with the ethylenically unsaturated groups of the acrylate or methacrylate by a Michael addition reaction, and the reaction product is bonded as groups of formula

[0134]

[0135] (XXIV), wherein

[0136] R is as defined above,

[0137] R’ is either hydrogen or methyl.

[0138] In view of the above, the term “acrylates or methacrylates functionalised with thio compounds relates to the corresponding thioethers.

[0139] Preferred examples of suitable compounds of formula (I) based on the structure shown by formula (XXIV), being acrylates or methacrylates functionalised with thio compounds i.e. a thioether, includes the compound having the molecular structure illustrated by formula (XXV).

[0140]

[0141] Compound of formula (XXV) is available commercially as SEENOX® 412S, available from the company, Shipro Kasei Kaisha. The compound may typically be prepared by the Michael addition reaction of 4 moles of n-dodecylthiol with 1 mole of the acrylate ester compound of formula (XVI), by the analogous reaction protocol described herein.

[0142] The above process for the preparation of the thiourethane (isocyanate modified with thiol) compounds of formula (I) may typically be carried out in presence of catalysts, like tertiary amines, for example triethylene diamine, dimethylpiperazine, dimethylethanolamine, 1,4-diazabicyclo[2.2.2]octane or 1,8-diazabicyclo[5,4,0]undec- 7-ene, or with tin compounds as catalysts, for example dibutyl tin dilaurate. Triethylamine is preferred. The catalyst is, for example, used in an amount of 0.1 to 10 weight-%, based on the weight of the organic isocyanate. The reaction is usually carried out in presence of an organic solvent, like tetrahydrofuran or ethyl acetate, and at temperatures of, for example 30 to 80°C.

[0143] The above process for the preparation of the thioether ((meth)acrylate modified with thiol) compounds of formula (I) may typically be carried out in a first step by reacting acrylic acid or methacrylic acid with the polyol form the (meth)acrylate ester with the polyol. Typically, this reaction can be carried out in the presence of a reducing agent, for example hypophosphorous acid which may be added generally in an amount of 50 ppm to 5% by weight, preferably 100 ppm 4% by weight, more preferably 1000 ppm to 3% by weight, based on the weight of polyol.

[0144] This reaction may be accelerated by the addition of acid catalysts, for instance acids with a pKa of less than 2.2, such as phosphoric acid, phosphorous acid, pyrophosphoric acid, polyphosphoric acid, hydrogen sulfate, methanesulfonic acid, sulfuric acid, perchloric acid, hydrochloric acid, hydrobromic acid, chlorosulfonic acid, trichloromethanesulfonic acid, trifluoromethylsulfonic acid, benzenesulfonic acid or p-toluene sulfonic acid. The acid catalyst may be added generally in an amount of 50 ppm to 15% by weight, preferably 100 ppm to 14% by weight and more preferably 1000 ppm to 12% by weight or 1 % to 12% by weight, based on the amount of the polyol.

[0145] In addition, in this first step a stabilizer can be used in the reaction. Such stabilizer may be used to prevent polymerisation of the (meth) acrylate. The stabilizer can be selected from p-hydroxy anisole and butylated hydroxy anisole. Further, the reaction can be carried out in a solvent, typically an aprotic solvent, for example toluene, benzene. Typically, the reaction temperature may be from 60 to 120°C, preferably 70 to 110°C, more preferably from 70 to 100°C, most preferably from 75 to 90°C. Water produced can be removed during the course of the reaction from the reaction equilibrium to accelerate the action, for example by using molecular sieves or by Dean Stark assembly. The molecular sieves can be used on any pore size or morphology, for instance 4A, 3A, 5A, etc. Generally, the reaction time of this first step may range from 2 to 36 h, preferably from 5 to 30 h, more preferably from 10 to 25 h. The second step of the process to produce the thioether compounds of formula (I), the (meth)acrylate ester with the polyol so formed in the first step of the process would be reacted with a thiol of formula (XXI).

[0146] Typically, the second step can be carried out in the presence of a base. The base may comprise either inorganic base or organic base or both. Suitable inorganic bases include alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates, for instance sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, etc. Suitable organic bases include amine, for example primary amine, secondary amine and tertiary amine, such as triethylamine, dibutyl amine, triethyl amine, diisopropyl amine, etc. The amount of the base can be in the range from 5 to 60% weight, preferably from 10 to 55% by weight.

[0147] The reaction in this second step can be carried out in suitable solvents, such as aprotic solvent, for instance dimethylformamide (DMF) and / or tetrahydrofuran (THF). The reaction temperature can be from 25 to 75°C, preferably from 40 to 65°C, and the reaction time can be from 3 to 20 h, from 4 to 16 h or from 5 to14 h.

[0148] Thio compounds of formula (I) denoted by compounds having the structure of formula (XXIV) are available commercially, for instance from Shipro Kasei Kaisha in the SEENOX® product range, for instance SEENOX® 412S.

[0149] Component (iii) according to the present invention is at least one sterically hindered amine ether.

[0150] Suitably the sterically hindered amine ether may be an N-alkoxy- compound. Preferably the sterically hindered amine ether is an N-alkoxy piperidine.

[0151] Preferably the sterically hindered amine ether comprises at least one group having the structure below.

[0152]

[0153] wherein

[0154] B1 and B3 are independently linear or branched C1-C4 alkyl, preferably methyl, B2 and B4 are independently linear or branched C1-C4 alkyl, preferably methyl or ethyl, R' is independently selected from unsubstituted or substituted, linear or branched C₁-C₄₀ alkyl and unsubstituted or substituted C₃-C₁₀ cycloalkyl, and

[0155] * denotes the point of attachment to the remainder of the sterically hindered amine ether molecule.

[0156] More preferably, in accordance with the flame retardant polypropylene polymer composition according to the first aspect of the invention and the method according to the second aspect of the invention and the use according to the third aspect of the invention, the at least one sterically hindered amine is selected from the compounds of formula (III), compounds of formula (IV), compounds of formula (V), compounds of formula (VI), compounds of formula (VII), compounds of formula (VIII) and compounds of formula (IX).

[0157]

[0158] (III),

[0159] wherein Ri and R2 are independently selected from formula (IIIa);

[0160] R3 and R4 are independently selected from H and formula (IIIa);

[0161]

[0162] (IIIa),

[0163] R₅ and R₆ are independently selected from unsubstituted or substituted, linear or branched C₁₋₁₂ alkyl, preferably C₄ alkyl;

[0164] R₇ and R₈ are independently selected from unsubstituted or substituted, linear or branched C₁₋₁₂ alkyl and unsubstituted or substituted C₃₋₁₀ cycloalkyl, preferably cyclohexyl;

[0165]

[0166] wherein

[0167] m is 1 to 10, R₉ and R₁₀ are independently selected from unsubstituted or substituted, linear or branched C₁₋₁₂ alkyl;

[0168] R11 and R12 are independently selected from unsubstituted or substituted, linear or branched C1-12 alkoxy and unsubstituted or substituted C3-10 cycloalkoxy,

[0169]

[0170] (V),

[0171] wherein n is a number from 2 to 14;

[0172]

[0173]

[0174] (IX),

[0175] wherein R13 is –OC(O)–C₁₁-C₂₀ saturated / C₁₇ unsaturated.

[0176] Preferably the article according to the present invention may contain the at least one sterically hindered amine, as defined herein above, in an amount from 0.05% to 10% by weight based on the weight of the polypropylene polymer substrate. More preferably the at least one sterically hindered amine should be present in an amount from 0.1 % to 5%, more preferably from 0.25% to 2.5%, by weight, based on the weight of the polypropylene polymer substrate.

[0177] Component (iv) of the present invention is at least one phosphorus compound, being one or more of phosphinate, phosphinate, phosphate and alkali metal hypophosphite. This component employed in the present invention, including all aspects of the invention and the formation more specific definitions, may be used in place of or in combination with component (iii), the sterically hindered amine ether.

[0178] Preferably the phosphorus compound is a phosphonate. The phosphonate may be alkyl- or aryl- phosphonic acids, where the alkyl may be a straight or branched chain alkyl group having 1 to 4 carbon atoms, and the aryl group may be a substituted or unsubstituted benzyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, or a salt or ester of the aforementioned phosphonic acid.

[0179] Preferably the at least one phosphorus compound includes a phosphonate

[0180] of the formula (X)

[0181]

[0182] wherein A1 and A2 are independently selected from a group consisting of alkyl, optionally substituted alkyl, benzyl, optionally substituted benzyl, phenyl, optionally substituted phenyl, naphthyl, optionally substituted naphthyl, preferably methyl or benzyl and more preferably where A1 and A2 are both methyl or both benzyl.

[0183] In another suitable Embodiment of the invention the phosphonate may be at least one phosphonate compound of the formula (XI)

[0184]

[0185] where A3 and A4 independently denote C1-C4 alkyl, preferably methyl or ethyl and A5 denotes a straight or branched chain alkyl having 1 to 4 carbon atoms or a phenyl or benzyl group having up to 3 methyl groups respectively.

[0186] The at least one phosphorus compound may be a mixture of phosphonate compounds, in particular a mixture of at least one phosphonate compound according to formula (X) and at least one phosphonate compound according to formula (XI). Such a mixture may also additionally include other phosphonate compounds, for instance any of the compounds referred to as alkyl- or aryl-phosphonates as described above.

[0187] Suitably the phosphorus compound may be present in the article in an amount of at least 0.1% by weight based on the weight of the polypropylene polymer substrate. Typically, the phosphorus compound would be present in the article in an amount from 0.1% to 20%, preferably from 0.5% to 10% by weight, based on the weight of the polypropylene polymer substrate.

[0188] In one embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (IV), and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X), preferably where A1 and A2 are both methyl or are both benzyl.

[0189] In another embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (V), and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X), preferably where A1 and A2 are both methyl or are both benzyl.

[0190] In yet another embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (VI) and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X).

[0191] In a further embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (VIII) and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X).

[0192] In a yet further embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (IX) and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X).

[0193] In a preferred embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (III) with Formula (Illa), and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X), preferably where A1 and A2 are both methyl or are both benzyl.

[0194] In another preferred embodiment, the article comprises the sterically hindered amine (iii) which is a compound of Formula (VII), and comprises the phosphorus compound (iv) which is a phosphonate of Formula (X), preferably where A1 and A2 are both methyl or are both benzyl.

[0195] In accordance with the various aspects of the present invention, component (i) is a polypropylene polymer substrate.

[0196] Polypropylene is a thermoplastic polymer which can be prepared by different methods from propylene monomer. Typically, this may be a radical polymerisation or catalytic polymerisation.

[0197] Producing polypropylene by a radical polymerisation is normally carried out a high pressure and at elevated temperature.

[0198] Polypropylene synthesis by catalytic polymerisation typically employs a catalyst containing one or more metals of groups IVb, Vb, Vlb (for example chromium) or VIII of the Periodic Table. These metals usually have one or more than one ligand, typically 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, typically activated magnesium chloride, titanium (III) chloride, alumina or silicon oxide. These catalysts may be soluble or insoluble in the polymerisation medium. The catalyst can be used by themselves in the polymerisation or further activators may be used, typically methyl alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyloxanes, said metals being elements of group la, Ila and / or Illa of the Periodic Table. The activators may be modified conveniently 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). The polypropylene may be a copolymer of propylene with other olefinic comonomers such as ethylene or butylene, for instance n-butylene or isobutylene, provided that propylene is the main constituent of the monomers. Desirably where the polypropylene is a copolymer propylene should form at least 90% by weight of the monomer mixture, for instance from 90 to 99.9% by weight propylene based on the total weight of monomer mixture, preferably from 95 to 99.9% by weight, based on the total weight of monomer mixture, more preferably from 98 to 99.9% by weight, based on the total weight of the monomer mixture, where the other olefinic comonomers make up the difference to 100% by weight.

[0199] The polypropylene may be a mixture of a polypropylene polymer with other thermoplastic polymers, especially polyolefins, provided that the polypropylene polymer forms the major component, for example at least 90% polypropylene, for instance from 90% to 99.9% by weight polypropylene, based on the total weight of the polymer mixture, preferably from 95% to 99.9% by weight polypropylene, based on the weight of the polymer mixture, more preferably from 98% 99.9% by weight polypropylene, based on the total weight of the polymer mixture, where other thermoplastic polymers would form the difference up to 100% by weight. Where the polypropylene is such a mixture, it is preferred that the polypropylene polymer is a propylene homopolymer.

[0200] Preferably the polypropylene is a homopolymer of propylene or a mixture of different polypropylene homopolymers. More preferably, the polypropylene is a homopolymer of propylene.

[0201] Polypropylene polymers suitable for this invention are commercially available, for example MOPLEN® HP552R, a polypropylene homopolymer having a Melt Flow Index of 25 g / 10 min at 230°C / 2.16 kg, a density of 0.9 g / cm3, manufactured by LyondellBasell. Films, Fibres and Tapes

[0202] The article according to the present invention is a film, fibre or a tape.

[0203] When the article is a film, including a single layer film or a multilayer film, the film may be obtained by subjecting the polypropylene polymer composition to film extrusion or coextrusion process, casting process, blowing process or a biaxially orientation process, usually in the course of an extrusion process. The biaxially orientation process, usually during an extrusion process may be desirable, yielding so-called biaxially orientated films.

[0204] In another embodiment, the film of the polypropylene polymer composition may be subjected to stretching or biaxial orientation, which can be performed by any methods known to those skilled in the art.

[0205] In another embodiment, the film of the polypropylene polymer composition is stretched by guiding it over at least one roll, preferably a roll system, or by extending it widthwise. If the film is obtained in the form of a tube, it is likewise possible that the film is stretched by blowing air into the tube of the film and hand stretching the polymer film. It will be appreciated that combinations of the methods are also possible.

[0206] In another embodiment, the film of the polypropylene polymer composition is guided over at least one roll, preferably through a roll system, the film is stretched in extrusion direction i.e. lengthwise. If the said film, by contrast, is extended widthwise, it is stretched at right angles to extrusion direction.

[0207] In an embodiment, the said film of the polypropylene polymer composition, for stretching, is guided over at least one roll, preferably through a roll system, the polymer chains of the polypropylene polymer composition comprising thio compound of formula (I) and at least one of an preferably both the sterically hindered amine ether and the phosphorus compound as described above are aligned parallel to the direction in which stretching is performed. The stretched polypropylene film obtained is then uniaxially oriented. The stretched polypropylene film obtained is likewise uniaxially oriented when said film, for stretching, is extended widthwise. In that case too, the polymer chains of the polypropylene polymer composition as described above are aligned parallel to the direction in which the stretching is performed.

[0208] In an embodiment, "uniaxially oriented" means that the polypropylene chains are aligned essentially in one direction.

[0209] In an embodiment, the said polypropylene film, for stretching, is guided over a roll system and additionally extended widthwise, the polymer chains of the polypropylene polymer composition as described above are aligned parallel to both directions in which stretching is performed. The stretched polypropylene film obtained is then biaxially oriented.

[0210] In an embodiment, "biaxially oriented" means that the polymer chains are aligned essentially in two different directions preferably at right angles to one another.

[0211] In an embodiment, if the above-described processes for stretching the said polymer film are combined, the polypropylene film is thus obtained, for example, in tubular form and the film is stretched by blowing air into the tube of the polymer film and simultaneously guided over rolls and likewise stretched; thus, the stretched polypropylene film (SP) obtained is biaxially oriented.

[0212] In an embodiment, the said polypropylene film is typically stretched at a temperature above the glass transition temperature (Tg) of the at least one polypropylene and below the melting temperature (Tm) of the at least one polypropylene. If the said film is a multilayer film, it is also preferable that the film is stretched at a temperature below the melting temperature (Tm) of the at least one further polymer, especially preferably at a temperature below the melting temperature of the at least one further polymer having the lowest melting temperature.

[0213] In one preferred embodiment, the article according to the present invention is a film suitably with a thickness of up to 5 mm. Suitably the film may have a thickness from 0.1 mm to 5 mm. In some applications the film may have a thickness, for instance from 0.1 mm to 1 mm, for instance from 0.2 mm to 0.8 mm or from 0.3 mm to 0.7 mm, such as from 0.4 mm to 0.6 mm. In other applications the film may have a thickness in the range from 0.25 mm to 5 mm, such as from 0.3 mm to 4 mm, suitably from 0.4 mm to 3 mm, more preferably from 0.5 mm to 2.5 mm.

[0214] In another embodiment, the article according to the present invention is a tape. In one aspect the tape may be produced by extruding a melt of the polypropylene polymer composition through a die in a similar fashion a film as described above. Generally, the extruded polypropylene would be cut to the required dimensions in order to provide the tape. Alternatively solid or partly melted polypropylene may be compressed by a suitable pressing device in order to provide the tape. In this case, the compression would generally achieve a multi-orientated layer can be cut to the relevant dimensions required for the tape. Typically, once the layer has been formed it will often be desirable to stretch the tape layer, for instance by calendaring or other suitable rollers in order to avoid the formed tape stretching during use.

[0215] The so formed tape may have a thickness analogous to the aforementioned films, suitably with a thickness of up to 5 mm. Suitably the tape may have a thickness from 0.1 mm to 5 mm. In some applications the tape may have a thickness, for instance from 0.1 mm to 1 mm, for instance from 0.2 mm to 0.8 mm or from 0.3 mm to 0.7 mm, such as from 0.4 mm to 0.6 mm. In other applications the tape may have a thickness in the range from 0.25 mm to 5 mm, such as from 0.3 mm to 4 mm, suitably from 0.4 mm to 3 mm, more preferably from 0.5 mm to 2.5 mm.

[0216] The article according to the present invention may be a fibre. Typically, the polypropylene polymer composition would be extruded to form fibres. Normally this would be achieved by extruding the polypropylene polymer composition through an extrusion device typically known as a spinneret which is employed to extrude a polymer solution or polymer melt to form fibres. In the case of the present invention, the polypropylene would more desirably be extruded as a polymer melt. The polypropylene melt would be ejected from the spinneret as a viscous polymer into air or liquid leading to a phase inversion which allows the polypropylene to solidify. Suitably individual polypropylene chains tend to align in the fibre in view of the viscous flow. It may be desirable to spin the polypropylene fibres as solid fibres or hollow fibres, preferably the fibres are solid. In such embodiment where the article according to the present invention is a fibre, desirably the fibre may have a diameter of up to 200 μm. Suitable fibres may have a diameter of from 0.1 μm to 200 μm, preferably from 0.5 μm to 200 μm, for instance from 0.6 μm to 150 μm, more preferably from 0.75 μm to 100 μm, for instance from 0.7 μm to 75 μm, more preferably still from 0.75 μm to 50 μm.

[0217] The second aspect of the present invention defines a method for preparing the aforesaid article comprising a flame-retardant polypropylene polymer composition comprising introducing

[0218] a thio- compound (ii) of formula (I) as defined in this specification; and either or both of at least one sterically hindered amine ether (iii) or at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite into a polypropylene polymer substrate (i),

[0219] and then processing the so formed mixture into the article, the article being a film or a fibre or a tape, as described hereinabove.

[0220] Suitably in this second aspect, the composition comprising the polypropylene polymer substrate (i) and the thio compound (ii) of formula (l);and either or both of the at least one sterically hindered amine ether (iii) and / or the at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite (iv) is formed into the article being a film or a fibre or a tape.

[0221] In a preferred embodiment of the second aspect, one or more of the at least one thio compound (ii), at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) are introduced prior to or during the melt processing of the polypropylene polymer substrate, preferably wherein the thio compound (ii) is introduced in the form of a masterbatch, more preferably wherein the components (ii) and (iii) and / or (iv) are introduced in the form of a masterbatch.

[0222] The third aspect of the present invention is directed to the use of a thio compound (ii) of formula (I); and either or both of at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape.

[0223] In a preferred embodiment of this inventive use, the thio compound (ii) of formula (I) is used in conjunction with both the at least one sterically hindered amine ether (iii) and the at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite. More preferably still according to this inventive use a thio compound (ii) of formula (I); and both at least one sterically hindered amine ether (iii) and at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite are introduced in the form of a masterbatch.

[0224] The fourth aspect of the present invention concerns an additive mixture, for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape, wherein the additive mixture comprises the components,

[0225] (ii) a thio compound of formula (I) as defined in this specification; and either or both of

[0226] (iii) at least one sterically hindered amine ether; and / or

[0227] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite, wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4alkyl) amino, or is C4-C20alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol, preferably wherein the additive mixture is in the form of a masterbatch.

[0228] Preferably, in accordance with this fourth aspect, the additive mixture comprises the components, (ii) a thio compound of formula (I); and both of (iii) at least one sterically hindered amine ether; and(iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite. In a preferred embodiment of the present invention defines a composition comprising a polypropylene polymer substrate (i) and an additive mixture comprising,

[0229] (ii) a thio compound of formula (I); and either or both of

[0230] (iii) at least one sterically hindered amine ether; and / or

[0231] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite

[0232] wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4alkyl) amino, or is C4-C20alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol, preferably wherein the additive mixture is in the form of a masterbatch.

[0233] Preferably in accordance with this preferred embodiment, the composition comprises the polypropylene polymer substrate (i) wherein the additive mixture comprises the components, (ii) a thio compound of formula (I); and both of (iii) at least one sterically hindered amine ether; and (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite.

[0234] Further additives

[0235] It may be desirable to include further additives into the polypropylene polymer composition, typically by incorporating one or more of these additives into the polypropylene polymer in the form of a melt.

[0236] Such further additives may be at least one selected from the group consisting of UV absorbers and light stabilisers; antioxidants; metal deactivators; phosphites and phosphonites; nitrones; thiosynergists; peroxide scavengers; basic co-stabilisers; nucleating agents; fillers and reinforcing agents; other additives; and benzofuranones and indolinones. Other examples of further additives include slip additives which are used to help film surfaces slide over each other, acid scavengers, for instance as described in Chapter 4 of the Plastic Additives Handbook; lubricants, for instance as described in Chapter 5 of the Plastic Additives Handbook polymer processing aids, for instance as described in Chapter 6 of the Plastic Additives Handbook; anti blocking additives, for instance as given in Chapter 7 of the Plastic Additives Handbook; and antifogging additives, for instance as given in Chapter 9 of the Plastic Additives Handbook. Each refers to Plastic Additives Handbook, 5thEdition, Edited by Hans Zweifel, Hanser Munich, ISBN 3-446-21654-5.

[0237] Specific examples of these further additives are shown below.

[0238] 1. Antioxidants

[0239] 1.1. Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-di methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(a-methylcyclohexyl)-4,6-dimethyl phenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-meth oxymethylphenol, nonylphenols which are linear or branched in the side chains, for example, 2,6-di-nonyl-4-methylphenol, 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.

[0240] 1.2. Alkylthiomethylphenols, for example 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctyl thiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4- nonylphenol.

[0241] 1.3. Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxy phenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 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-hydroxyphenyl stearate, bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.

[0242] 1.4. Tocopherols, for example α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (vitamin E). 1.5. Hydroxylated thiodiphenyl ethers, for example 2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6-tert-butyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2- methylphenol), 4,4'-thiobis(3,6-di-sec-amylphenol), 4,4'-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.

[0243] 1.6. Alkylidenebisphenols, for example 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'methylenebis(6-tert-butyl-4-ethylphenol), 2,2'-methylenebis[4-methyl-6-(a-methylcyclohexyl) phenol], 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl-4-methylphenol), 2,2'-methylenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butyl phenol), 2,2'-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis[6-(a-methylbenzyl)-4-nonylphenol], 2,2'-methylenebis[6-(a,a-dimethylbenzyl)-4-nonylphenol], 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-2-methylphenol), 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-methylphenyl)butane, 1,1-bis(5-tert-butyl-4- hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis[3,3-bis(3'-tert butyl-4'-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene, bis[2-(3'-tert-butyl-2'-hydroxy-5'-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephtha late, 1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(5-tert-butyl-4-hydroxy2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.

[0244] 1.7. 0-, N- and S-benzyl compounds, for example 3,5,3',5'-tetra-tert-butyl- 4,4'-dihydroxydi benzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, 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-hydroxy-benzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate.

[0245] 1.8. Hydroxybenzylated malonates, for example dioctadecyl-2, 2-bis(3,5-di-tert-butyl-(2-hydroxybenzyl)malonate, di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate, di dodecylmercaptoethyl-2,2-bis (3,5-di-tert-butyl-4- hydroxybenzyl)malonate, bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.

[0246] 1.9. Aromatic hydroxybenzyl compounds, for example 1,3,5-tris(3,5-di-tert-butyl-4-hydroxy benzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.

[0247] 1.10. Triazine compounds, for example 2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxy anilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-tri azine, 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- 15 (3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1, 3, 5-tris(3, 5-di-tert-butyl-4-hydroxy-phenylpropionyl)-hexahydro-1,3,5-triazine, 1, 3, 5-tris(3, 5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.

[0248] 1.11. Benzylphosphonates, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3, 5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl3,5-di-tert-butyl-4-hy- droxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

[0249] 1.12. Acylaminophenols, for example 4-hydroxylauranilide, 4-hydroxystearanilide, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate.

[0250] 1.13. Esters of 13-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N, N'-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylol propane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. 1.14. Esters of 13-(5-tert-butyl- -hydroxy-3-methylphenyl)propionic acid with mono- or poly hydric alcohols, e.g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N, N'-bis-(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane; 3,9-bis[2-{3-(3-tert butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5] undecane.

[0251] 1.15. Esters of 13-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, tri ethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N, N'-bis(hydroxyethyl)ox amide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0252] 1.16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N, N'-bis(hydroxyethyl)ox amide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

[0253] 1.17. Amides of 13-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid e.g. N, N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide, N, N'-bis(3,5-di-tert-butyl-4-hydroxy phenylpropionyl)trimethylenediamide, N, N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazide, N, N'-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide (Nau gard®XL-1, supplied by Uniroyal).

[0254] 1.18. Ascorbic acid (vitamin C) 1.19. Aminic antioxidants, for example N, N'-di-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N, N'-bis( 1,4-dimethylpentyl)-p-phenylenediamine, N, N'-bis(1-ethyl-3- methylpentyl)-p-phenylenediamine, N, N'-bis(1-methylheptyl)-p-phenylenediamine, N, N'-dicyclohexyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N'-bis(2-naphthyl)-p phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N' phenyl-p-phenylenediamine, 4-(p-toluenesulfamoyl)diphenylamine, N, N'-dimethyl-N, N'-di-5 sec-butyl-p-phenylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxydiphenyl amine, N-phenyl-1 -naphthylamine, N-(4-tert-octylphenyl)-1 -naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, for example p,p'-di-tert-octyldiphenylamine, 4-n-butyl aminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octadecanoylaminophenol, bis(4-methoxyphenyl) amine, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N, N, N', N'-tetra methyl-4,4'-diaminodiphenylmethane, 1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenyl amino)propane, (o-tolyl)biguanide, bis[4-(1 ',3'-dimethylbutyl)phenyl]amine, tert-octylated N phenyl-1 -naphthylamine, a mixture of mono- and dialkylated tert-butyl / tert-octyldiphenyl amines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopropyl / isohexyl diphenylamines, a mixture of mono- and dialkylated tert-butyldiphenylamines, 2,3-dihydro- 3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono-and dialkylated tert-butyl / tert-octylphenothiazines, a mixture of mono- and dialkylated tert-octyl-phenothiazines, N-allylphenothiazine, N, N, N', N'-tetraphenyl-1,4-diaminobut-2-ene.

[0255] 2. UV absorbers and light stabilizers

[0256] 2.1. 2-(2'-Hydroxyphenyl)benzotriazoles, for example 2-(2'-hydroxy-5'-methylphenyl)-benzo triazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 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'-methylphe-nyl)-5-chloro-benzotriazole, 2-(3'-sec-butyl-5'-tert-butyl-2'-hydroxyphenyl) benzotriazole, 2-(2' hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(a,a-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylhexyl oxy)-carbonylethyl]-2'-hydroxyphenyl)-5-chloro-benzotriazole, 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-octyloxycarbonyl ethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-5'-[2-(2-ethylhexyloxy)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-benzotriazole-2-ylphenol]; the transesterification product of 2-[3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl]-2H-benzotriazole with polyethylene glycol 300; - [- R-CH2CH2COO-CH2CH2-]2-, where R = 3'-tert-butyl-4'-hydroxy-5'-2H-benzotriazol-2-ylphenyl, 2-[2'-hydroxy-3'-(a,a-dimethylbenzyl)-5'-(1,1,3,3-tetramethylbutyl)-phenyl] benzotriazole; 2-[2'-hydroxy-3'-( 1,1,3,3-tetramethylbutyl)-5'-(a,a-dimethylbenzyl)-phenyl]ben zotriazole.

[0257] 2.2. 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyl oxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives.

[0258] 2.3. Esters of substituted and unsubstituted benzoic acids, for example 4-tert-butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl)resorcinol, benzoyl resorcinol, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate.

[0259] 2.4. Acrylates / Cinnamates, for example ethyl a-cyano-p,p-diphenylacrylate, isooctyl a-cyano-p,p-diphenylacrylate, methyl a-carbomethoxycinnamate, methyl a-cyano-p-methyl-p-methoxycinnamate, butyl a- cyano-p, p-methyl-p-methoxycinnamate, methyl a-carbomethoxy-p-methoxycin-namate, N-(P-carbomethoxy- p -cyanovinyl)-2-methylindoline, neopentyl tetra(a-cyano-|3,|3-diphenylacrylate. Other cyanoacrylates may also be used and such compounds are given in EP 3587425.

[0260] 2.5. Nickel compounds, for example nickel complexes of 2,2'-thio-bis[4-(1,1,3,3-tetramethyl butyl)phenol], such as the 1:1 or 1:2 complex, with or without additional ligands such as n butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. the methyl or ethyl ester, of 4-hydroxy-3,5-di-tert butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenylundecylketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or with out additional ligands.

[0261] 2.6. Sterically hindered amines, for example bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, bis( 1, 2, 2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis( 1,2,2,6,6-pentamethyl-4- piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxyethyl)-2, 2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, linear or cyclic condensates of N, N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert octylamino-2,6-dichloro-1,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, 1, 1'-(1,2-ethanediyl) bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethyl piperidine, 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-triazaspiro[4.5]decane-2, 4-dione, bis( 1 -octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate, bis( 1 -octyloxy- 2.2.6.6- tetramethylpiperidyl)succinate, linear or cyclic condensates 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-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-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-hexadecyloxy- and 4-stearyloxy-2, 2, 6, 6- tetramethylpiperidine, a condensate of N, N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a condensate of 1,2-bis(3-aminopropylamino)ethane and 2,4,6-trichloro- 1.3.5-triazine as well as 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.

[0262] [136504-96-6]); a condensate of 1,6-hexanediamine and 2, 4, 6-trichloro-1,3,5-triazine as well as N, N-dibutylamine and 4-butylamino-2, 2,6,6-tetramethylpiperidine (CAS Reg. No. [192268-64-7]); N-(2,2,6,6- tetramethyl-4-piperidyl)-n-dodecylsuccinimide, N-(1, 2,2,6, 6-pentamethyl-4-piperidyl)-n-dodecylsuccinimide, 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane, a reaction product of 7,7,9, 9-tetramethyl-2-cycloundecyl-1 -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)ethene, N, N'-bis-formyl-N, N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexa methylenediamine, a 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, a reaction product of maleic acid anhydride-a-olefin copolymer with 2,2,6,6-tetramethyl-4-aminopiperidine or 1,2,2,6, 6-pentamethyl-4-aminopiperidine, 2,4-bis[N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidine-4-yl)-N-butylamino]-6-(2-hydroxyethyl)amino-1,3,5-triazine, 1 -(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine, 5-(2-ethylhexanoyl)oxymethyl-3,3,5-trimethyl-2-morpholinone, Sanduvor 3058 (Clariant; CAS Reg. No. 106917-31-1 ] 1-(1-acetyl-2,2,6,6-tetramethylpiperidin-4-yl)-3-dodecylpyrrolidine-2,5-dione,, the reaction product of 2,4-bis [(1-cyclohexyloxy-2,2,6,6-piperidine-4-yl)butylamino]-6-chloro-s-triazine with N, N'-bis(3-ami nopropyl)ethylenediamine), 1.3.5-tris(N-cyclohexyl-N-(2,2,6,6-tetramethylpiperazine-3-one-4- yl)amino)-s-triazine, 1,3,5-tris(N-cyclohexyl-N-(1,2,2,6,6-pentamethylpiperazine-3-one-4-yl) amino)-s-triazine.

[0263] 2.7. Oxamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy- 5,5'-di-tert-butoxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide, N, N'-bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyl-2'-ethoxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide, mixtures of o- and p-methoxy-disubstituted oxanilides and mixtures of o- and p-ethoxy-disubstituted oxanilides.

[0264] 2.8. 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example 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-propyloxyphenyl)-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-dimethylphenyl)- 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-butyloxypropoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine, 2-[4-(dodecyloxy / tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)- 1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethyl phenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2-hydr oxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxypropoxy)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, 2,4-bis(4-[2-ethylhexyloxy]-2-hydroxyphenyl)-6-(4- methoxyphenyl)-1,3,5-triazine.

[0265] 3. Metal deactivators, for example N, N'-diphenyloxamide, N-salicylal-N'-salicyloyl hydrazine, N, N'-bis(salicyloyl)hydrazine, N, N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide, N, N'-diacetyladipoyl dihydrazide, N, N'-bis(salicyloyl)oxalyl dihydrazide, N, N'-bis(salicyloyl)thiopropionyl dihydrazide.

[0266] 4. Phosphites and phosphonites, for example triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,4-di cumylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tris(tert-butylphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenz[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert- butyl-6-methylphenyl)methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite, 6-fluoro-2,4,8, 10-tetra-tert-butyl-12-methyl-dibenz[d,g]-1,3,2-dioxaphosphocin, 2, 2', 2"-nitri Io [triethyltris(3,3',5,5'-tetra-tert-butyl-1, 1 '-biphenyl-2,2'-diyl)phosphite], 2-ethylhexyl(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite, 5-butyl-5-ethyl-2-(2,4,6-tri-tert-butylphenoxy)-1,3,2-dioxaphosphirane, poly(4,4'{-isopropylidenediphenol}-octylphosphite), poly(4,4'-{isopropylidenebis[2,6-dibromophenol]}-octylphosphite), poly(4,4'- {2,2'-dimethyl-5,5'-di-t-butylphenylsulfide}-pentaerythrityl diphosphite), phosphorous acid, mixed 2,4-bis(1,1-dimethylpropyl)phenyl and 4-(1,1-dimethylpropyl)phenyl triesters (CAS No. 939402-02-5), phosphorous acid, triphenyl ester, polymer with alpha-hydro-omega-hydroxypoly[oxy(methyl-1,2-ethanediyl)], C10-16alkyl esters (CAS No.

[0267] 1227937-46-3).

[0268] The following phosphites are especially preferred:

[0269] Tris(2,4-di-tert-butylphenyl) phosphite (lrgafos®168, BASF SE), tris(nonylphenyl) phosphite, 09

[0270]

[0271]

[0272] 5. Hydroxylamines, for example N, N-dibenzylhydroxylamine, N, N-diethylhydroxylamine, N, N-dioctylhydroxylamine, N, N-dilaurylhydroxylamine, N, N-ditetradecylhydroxylamine, N, N dihexadecylhydroxylamine, N, N-dioctadecylhydroxylamine, N-hexadecyl-N-octadecylhydrox ylamine, N-heptadecyl-N-octadecylhydroxylamine, N, N-dialkylhydroxylamine derived from hydrogenated tallow amine or derived from vegetable source.

[0273] 6. Nitrones, for example, N-benzyl-alpha-phenylnitrone, N-ethyl-alpha-methylnitrone, N-octyl-alpha-heptylnitrone, N-lauryl-alpha-undecylnitrone, N-tetradecyl-alpha-tridecylnnitrone, N-hexadecyl-alpha-pentadecylnitrone, N-octadecyl-alpha-heptadecylnitrone, N-hexadecyl-alpha-heptadecylnitrone, N-ocatadecyl-alpha-pentadecylnitrone, N-heptadecyl-alpha-hepta decylnitrone, N-octadecyl-alpha-hexadecylnitrone, nitrone derived from N, N-dialkylhydroxyl amine derived from hydrogenated tallow amine.

[0274] 7. Thiosynergists, for example dilauryl thiodipropionate, dimistryl thiodipropionate, distearyl thiodipropionate, pentaerythritol tetrakis[3-(dodecylthio)propionate] or distearyl disulfide.

[0275] 8. Peroxide scavengers, for example esters of -thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or the zinc salt of 2-mercapto benzimidazole, zinc dibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritol tetrakis(P -dodecylmercapto)propionate.

[0276] 9. Basic further stabilizers, for example melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids, for example calcium stearate, zinc stearate, magnesium behenate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate or zinc pyrocatecholate.

[0277] 10. Nucleating agents, for example inorganic substances, such as talcum, metal oxides, such as titanium dioxide or magnesium oxide, phosphates, carbonates or sulfates of, preferably, alkaline earth metals; organic compounds, such as mono- or polycarboxylic acids and the salts thereof, e.g. 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate or sodium benzoate; polymeric compounds, such as ionic copolymers (ionomers).

[0278] 11. Fillers and reinforcing agents, for example calcium carbonate, silicates, glass fibers, glass beads, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, car bon black, graphite, wood flour and flours or fibers of other natural products, synthetic fibers.

[0279] 12. Other additives, for example plasticisers, lubricants, emulsifiers, pigments, rheology additives, catalysts, flow-control agents, optical brighteners, flameproofing agents, antistatic agents and blowing agents. Other additives may also include anti-block additives, as referred to above, which are used in films to reduce the negative adhesion of two polyethylene surfaces to one another which would otherwise result in difficulties separating the films. Antifogging agents, as referred to above, may also be added.

[0280] 13. Benzofuranones and indolinones, for example those disclosed in U. S.

[0281] 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-4316611; DE-A-4316622; DE-A-4316876; EP-A-0589839, EP-A-0591102; EP-A-1291384 or 3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-tert-butylbenzofuran-2-one, 5,7-di-tert-butyl-3-[4-(2-stearoyloxy ethoxy)phenyl]benzofuran-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-di methylphenyl)-5,7-di-tert-butylbenzofuran-2-one, 3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di tert-butylbenzofuran-2-one, 3-(3,4-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one, 3-(2,3-dimethylphenyl)-5,7-di-tert-butylbenzofuran-2-one, 3-(2-acetyl-5-isooctylphenyl)-5-isooctyl benzofuran-2-one. Suitable benzofuranones also include compounds identified in WO2015 / 121445 and WO2017 / 025431.

[0282] The co-additive is for example present in the polypropylene melt in an amount of 0.001 to 10 % by weight, preferably 0.001 to 5 % by weight, relative to the weight of the polypropylene melt. Conventional fillers or reinforcing agents may be present in the polymer melt in amounts of 0.1 to 10 % by weight, preferably 1 to 5 % by weight, in certain cases in amounts up to 70 % by weight, relative to the weight of the polypropylene melt.

[0283] Examples of films tapes and fibres and end use products they are used in are illustrated below.

[0284] 1) Foils for condensers, refrigerators, heating devices, air conditioners, encapsulating of electronics, semi-conductors, coffee machines, and vacuum cleaners.

[0285] 2) Woven fabrics continuous and staple, fibers (carpets I hygienic articles I geotextiles I monofilaments, such as artificial turf; filters; wipes I curtains (shades) I medical applications), bulk fibers (applications such as gown I protection clothes), nets, ropes, cables, strings, cords, threads, safety seat-belts, clothes, underwear, gloves; boots; rubber boots, intimate apparel, garments, swimwear, sportswear, umbrellas (parasol, sunshade), parachutes, paraglides, sails, “balloon-silk”, camping articles, tents, airbeds, sun beds, bulk bags, and bags. Non-woven fabrics such as medical fabrics and related apparel, industrial apparel, outdoor fabrics, in-home furnishing and construction fabrics.

[0286] 3) Films (packaging, dump, laminating, agriculture and horticulture, greenhouse, mulch, tunnel, silage), bale wrap, swimming pools, waste bags, wallpaper, stretch film, raffia, desalination film, batteries, and connectors.

[0287] 4) Examples of Tapes include the following. 4.1 ) Big-bags or FIBC (flexible intermediate bulk container), bags: These are large bags made from woven polymer tapes that are used for transporting and storing bulk materials such as sand, gravel, food products, chemicals, and more.

[0288] 4.2) Safety cords: These are high-strength polymer tapes that are used for securing loads on trucks, trailers, and other vehicles. They are also used in construction to secure scaffolding and other equipment.

[0289] 4.3) Packaging tape: This is a type of polymer tape that is used for sealing boxes and packages. It is available in various widths and strengths depending on the application.

[0290] 4.4) Strapping tape: This is a heavy-duty polymer tape that is used for bundling and reinforcing heavy items such as pipes, lumber, and machinery.

[0291] 4.5) Woven polyester tape: This is a polymer tape that is made from woven polyester fibers. It is used for a wide range of applications, including reinforcing seams on industrial fabrics, reinforcing conveyor belts, and securing cargo in transit.

[0292] The following examples are intended to illustrate the invention using non-limiting embodiments in accordance with the various aspects of the invention.

[0293] In a preferred embodiment the present invention refers to the following further items.

[0294] 1. An article, the article being a film or a fibre or a tape, comprising a flame-retardant polypropylene polymer composition which comprises the components,

[0295] (i) a polypropylene polymer substrate; and

[0296] (ii) a thio- compound of formula (I);

[0297] and either or both of

[0298] (iii) at least one sterically hindered amine ether; and / or

[0299] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite,

[0300]

[0301] wherein A is based on an organic isocyanate or a (meth)acrylate, wherein the radical(s) -S-R are introduced by reaction with isocyanate groups or (meth)acrylate groups, R is C2-C40alkyl which is optionally substituted and / or interrupted, and

[0302] n is equal to or greater than 1.

[0303] The article according to item 1, wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl) amino, or is C4-C20 alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

[0304] The article according to item 1 or item 2, wherein A is based on an organic isocyanate, the organic isocyanate being a phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl)amino, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

[0305] The article according to any of items 1 to 3, wherein A is based on an organic isocyanate, the organic isocyanate being a phenyl diisocyanate which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl)amino, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

[0306] The article according to item 1, wherein A is based on an acrylate or a methacrylate, the acrylate or methacrylate being an ester of a polyol.

[0307] The article according to any of items 2 to 5, wherein the polyol is a C1-C10 alkanol comprising two or more hydroxy groups, or a poly-C2-C10alkylene glycol, preferably a C3-C8 alkanol comprising two or more hydroxy groups.

[0308] The article according to any of items 1 to 6, wherein R is C2-C40 alkyl which is uninterrupted or interrupted by -O-, -NH-, -S- and / or a carbonyl group, preferably wherein R is C8-C40 alkyl which is uninterrupted or interrupted by -0- and / or a carbonyl group, more preferably wherein R is C10-C22 alkyl which is uninterrupted or interrupted by -0- and / or a carbonyl group, more preferably still wherein R is an uninterrupted C11-C21 alkyl.

[0309] . The article according to any of items 1 to 7, wherein the at least one sterically hindered amine ether is selected from the compounds of formula (III), compounds of formula (IV), compounds of formula (V), compounds of formula (VI), compounds of formula (VII), compounds of formula (VIII), and compounds of formula (IX),

[0310]

[0311] (III),

[0312] wherein Ri and R2 are independently selected from formula (Illa),

[0313] R3 and R4 are independently selected from H and formula (IIIa);

[0314]

[0315] (Illa),

[0316] R5and R6are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl, preferably C4alkyl,

[0317] R7and R8are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl and unsubstituted or substituted C3-10cycloalkyl, preferably cyclohexyl;

[0318]

[0319] (IV),

[0320] wherein

[0321] m is 1 to 10,

[0322] R9and R10are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl,

[0323] R11and R12are independently selected from unsubstituted or substituted, linear or branched C1-12alkoxy and unsubstituted or substituted C3-10cycloalkoxy;

[0324]

[0325] (V),

[0326] wherein n is a number from 2 to 14;

[0327]

[0328] (IX), wherein R13 is –OC(O)–C11-C20saturated / C17unsaturated, preferably wherein the at least one sterically hindered amine ether is selected from the compounds of formula (III) and the compounds of formula (VII).

[0329] The article according to any of items 1 to 8, wherein the at least one phosphorus compound includes a phosphinate of the formula (X)

[0330]

[0331] wherein A1 and A2 are independently selected from a group consisting of alkyl, optionally substituted alkyl, benzyl, optionally substituted benzyl, phenyl, optionally substituted phenyl, naphthyl, optionally substituted naphthyl, preferably methyl or benzyl and more preferably where A1 and A2 are both methyl or both benzyl.

[0332] The article according to any of items 1 to 9, wherein the thio- compound is present in the article in an amount from 0.001% to 10% by weight, desirably from 0.01% to 5% by weight and suitably from 0.02% to 2% by weight, based on the weight of the polypropylene polymer substrate.

[0333] The article according to any of items 1 to 10, wherein the at least one sterically hindered amine ether is present in the article in an amount from 0.05% to 10% by weight, preferably from 0.1 % to 5% by weight, more preferably from 0.25% to 2.5% by weight, based on the weight of the polypropylene polymer substrate.

[0334] The article according to any of items 1 to 11, wherein the phosphorus compound is present in the article in an amount from 0.1% to 20% by weight, preferably from 0.5% to 10% by weight, based on the weight of the polypropylene polymer substrate. The article according to any of items 1 to 12, wherein the article comprises the thiocompound (ii) which is a compound of formula (I), and the sterically hindered amine ether (iii) which is a compound of formula (III).

[0335] The article according to any of items 1 to 13, wherein the article comprises the thiocompound (ii) which is a compound of formula (I), and the sterically hindered amine ether (iii) which is a compound of formula (VII).

[0336] The article according to any of items 1 to 14, wherein the article comprises the thiocompound (ii) which is a compound of formula (I), and the phosphorus compound (iv) which is a compound of formula (X), preferably where A1 and A2 are both methyl or are both benzyl.

[0337] The article according to any of items 1 to 15, the article being a film having a thickness of up to 5 mm, preferably from 0.25 mm to 5 mm, more preferably from 0.5 mm to 2.5 mm.

[0338] The article according to any one of items 1 to 15, the article being a tape having a thickness of up to 5 mm, preferably from 0.25 mm to 5 mm, more preferably from 0.5 mm to 2.5 mm.

[0339] The article according to any of items 1 to 15, the article being a fibre having a diameter of up to 200 pm, preferably from 0.5 pm to 200 pm, more preferably from 0.75 pm to 100 pm, more preferably still from 0.75 pm to 50 pm.

[0340] A method for preparing an article, defined according to any of items 1 to 18, comprising a flame-retardant polypropylene polymer composition,

[0341] comprising introducing

[0342] a thio- compound (ii) of formula (I); and either or both of at least one sterically hindered amine ether (iii) or at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite into a polypropylene polymer substrate (i),

[0343] and then processing the so formed mixture into the article. The method according to items 19, wherein one or more of the at least one thio compound (ii), at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) are introduced prior to or during melt processing of the polypropylene polymer substrate, preferably wherein the thio- compound is introduced in the form of a masterbatch, more preferably wherein components (ii) and (iii) and / or (iv) are introduced in the form of a masterbatch.

[0344] Use of a thio- compound (ii) of formula (I) as defined in any one of items 1 to 18; and either or both of at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape.

[0345] The use according to item 21 which includes any other features according to items 2 to 18.

[0346] An additive mixture, for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape, wherein the additive mixture comprises the components,

[0347] (ii) a thio compound of formula (I) as defined in any one of items 1 to 18; and either or both of

[0348] (iii) at least one sterically hindered amine ether; and / or

[0349] (iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4alkyl) amino, or is C4-C20alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol, preferably wherein the additive mixture is in the form of a masterbatch. The additive mixture according to items 23, wherein the additive mixture comprises any of the features described in any of items 2 to 9.

[0350] The additive mixture according to item 23 or item 24, wherein the additive mixture is in the form of a masterbatch.

[0351] A composition comprising a polypropylene polymer substrate (i) and an additive mixture defined according to any of items 23 to 25. Examples

[0352] Flame retardancy performance of polypropylene 250 μm cast film containing as component (ii) either an oligomeric isocyanate thiol (thiourethane according to formula (I) and formula (XXIII) or an acrylate ester thiol (thioether according to formula (I) and formula (XXV));

[0353] and either or both of

[0354] N-alkoxyl hindered amine ether molecule (component (iii)) and / or organic phosphorous compound (component (iv)).

[0355] The following examples illustrate the improvement in FR performance (UL94 VTM and DIN 4102 part 1) when the oligomeric isocyanate thiol of the invention is employed.

[0356] The materials employed in these examples were as follows:

[0357] a) Polymer Component

[0358] Polymer component (PP): Polypropylene homopolymer MOPLEN® HP552R, Melt Flow Index: 25 g / 10 min at 230°C / 2.16Kg, density: 0.9 g / cm3, manufacturer LyondellBasell.

[0359] b) Flame retardant additives

[0360] FR1: N-alkoxy hindered amine ether based on the compound of formula (III), where R3 is hydrogen and R1, R2 and R4 are formula (Illa), where R5 and R6 are both C4 alkyl and R7 and R8 are both cyclohexyl.

[0361] FR2: sterically-hindered amine ether being the compound of formula (VII)

[0362] FR3: Aflammit® PCO 900 from the company Thor, it is an organic phosphorus-based, flame retardant, based on the compound of formula (X) where A1 and A2 are both methyl.

[0363] FR4: Compound of formula (I) being a thiourethane and having the formula (XXIII):

[0364]

[0365] (XXIII)

[0366] The preparation of this compound (XXIII) is described in patent WO2021 / 170615 A1, Example 6 and corresponds to the compound of formula (107) described therein.

[0367] FR5: SEENOX® 412S, supplied from the company Shipro Kasei Kaisha, being a thioether compound of formula (I) and having the formula (XXV).

[0368]

[0369] c) Production of blended polypropylene (PP from (a)) containing flame retardant additive as a masterbatch (M1 and M2) Both FR4 and FR5 were liquid additives at ambient temperature (25°C). In order to facilitate the dosing of each of FR4 and FR5 were provided as masterbatches by mixing each with polypropylene (PP) in accordance with the following procedure

[0370] Unless stated otherwise, PP and flame-retardant compounds FR4 and FR5 were each mixed at high speed mixed in the amounts as indicated in Table 1 using a Mixaco Lab CM 12 at 3000 rpm for 5 minutes.

[0371] TABLE 1: Concentrations of flame retardants in polypropylene mixture

[0372]

[0373] d) PP film manufacture

[0374] Unless stated otherwise, ground and the respective amounts of the flame-retardant additives FR1, FR2, FR3, M1 and M2 were dry blended in the amounts as indicated in Table 2 and then melt compounded into pellets on a 25 mm co-rotating twin-screw extruder Collin ZSK25, operating at set temperatures of 210 °C.

[0375] The pelletized fully formulated resin is then casted at a maximum temperature Tmax of 220 °C into 250 pm films using a cast film equipment Collin CR-136 / 350 coupled with an extruder Collin E 30 M.

[0376] e) Performance of formulation as flame retardant

[0377] The produced films are evaluated according to the standards UL 94 VTM and DIN4102-Part 1 (May 1998). TABLE 2: Concentrations of added additives in the PP cast film

[0378]

[0379] Comparative Compositions (compositions not according to the present invention): Ref.

[0380] 1, 2, 3 and 4

[0381] Compositions according to the present invention: Inv. 1, Inv. 2, lnv.3, lnv.4, lnv.5 and lnv.6

[0382] UL 94-VTM Test:

[0383] A flame is applied twice to the lower end of the test specimen positioned vertically. UL 94-VTM is a well-known test for classifying the flame retardancy of very thin material in 3 classes VTM-0, VTM-1 and VTM-2. The best rating is VTM-0. TABLE 3: Flaming test on 250 μm PP cast films according to UL94-VTM flame retardant performance.

[0384]

[0385] a) Average flaming time per specimen and after maximum 2 ignitions The efficacy of each of FR4 and FR5 when used in combination with FR1 or FR2 and / or FR3 as flame retardant is demonstrated with lower average flaming time, and VTM-2 or even VTM-0 classification.

[0386] FR4 makes it possible to reach VTM-2 classification when used at 0.1% (active concentration) in combination with FR1 (Inv. 1), compared to the non-classified result when FR1 is used alone (Ref. 2).

[0387] The same was observed with FR2 when used alone at 0.35% produced a nonclassification level (Ref. 3) in contrast to when combined with FR4 at 350ppm (active concentration) and at reduced concentration of only 0.25% of FR2 a VTM-2 classification was achieved (Inv. 2).

[0388] Similarly, when FR2 was used at 0.35% in combination with FR4 at 0.1% (active) in Inv. 3 a classification of VTM-2 was also achieved but with less than half of the burning time by comparison to Inv. 2.

[0389] For Inv. 4 the use of FR-4 at 0.1% (active) allows a reduction of 25% for the overall flame-retardant active content while at the same time improving the classification to VTM-0 compared to Ref. 4.

[0390] Similarly, FR5 made it possible to reach VTM-2 classification when used at 0.0175% (active concentration) both with FR1 with an average burning time of less than 4sec and with FR2 with an average burning time of just above 6 sec.

[0391] DIN4102-Part 1 Test:

[0392] The specimen is positioned vertically, and the ignition flame is applied at the lower edge of the specimen (edge ignition test).

[0393] Classification is based on the time for flames to spread 150 mm of the specimen. If the flame does not reach the 150 mm reference mark within 20 s, the tested film passes the test and is classified B2.

[0394] If the flame reaches the 150 mm reference mark within 20 s, the tested film is non classified (n.c.). TABLE 4: Flaming test on 250 μm PP cast films according to DIN 4102-Part 1 (edge ignition)

[0395]

[0396] a) Rated "pass" if flaming does not reach the 150 mm gauge mark within 20 seconds after flame application according to the DIN 4102-Part 1 test norm.

[0397] b) Burning time, in second, is the duration of the flaming after flame application up to the extinction of flame.

[0398] c) Damaged length, in mm, is the vertical part of the film being burned after the extinction of flame.

[0399] d) Rated "no" if molten and burning drips that have fallen on the filter paper does not ignite the paper placed underneath the test specimen according to the DIN 4102-Part 1 test norm, "no" is the best rating. Inv. 1 with just a 0.1% of active FR4 compared to Ref. 2 showed similar average burning time but a significant reduction of the average burning length of the 5 samples. In Inv. 2 the addition of small amount of masterbatch M1 allows a reduction of the amount of main compound FR-2 from 0.35% to 0.25% and still achieve better performance with no burning drips when compared with Ref. 3.

[0400] In a similar way to Inv. 1, Inv. 3 also employing 0.1% of active FR4 showed both reduced burning time and damaged length compared to Ref. 3.

[0401] For Inv. 4 the use of FR4 at 0.1% (active) shows a reduction of 25% for the overall flame-retardant active content while at the same time keeping similar performance and B2 classification as Ref. 4.

Claims

Claims1. An article, the article being a film or a fibre or a tape, comprising a flame-retardant polypropylene polymer composition which comprises the components,(i) a polypropylene polymer substrate; and(ii) a thio- compound of formula (I);and either or both of(iii) at least one sterically hindered amine ether; and / or(iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite,(I)nwhereinA is based on an organic isocyanate or a (meth)acrylate, wherein the radical(s) - S-R are introduced by reaction with isocyanate groups or (meth)acrylate groups, R is C2-C40alkyl which is optionally substituted and / or interrupted, andn is equal to or greater than 1.

2. The article according to claim 1, wherein A is based on an organic isocyanate, the organic isocyanate being a cyclohexyl diisocyanate, methylenebis(cyclohexyl) diisocyanate, isophorone diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl) amino, or is C4-C20 alkyl diisocyanate, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

3. The article according to claim 1 or claim 2, wherein A is based on an organic isocyanate, the organic isocyanate being a phenyl diisocyanate, diphenylmethane diisocyanate or naphthyl diisocyanate each of which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl)amino, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

4. The article according to any of claims 1 to 3, wherein A is based on an organic isocyanate, the organic isocyanate being a phenyl diisocyanate which is unsubstituted or substituted by C1-C4 alkyl or di(C1-C4 alkyl)amino, or an oligomeric or polymeric product obtained by the reaction of the above isocyanates with themselves and / or a polyol.

5. The article according to claim 1, wherein A is based on an acrylate or a methacrylate, the acrylate or methacrylate being an ester of a polyol.

6. The article according to any of claims 2 to 5, wherein the polyol is a C1-C10 alkanol comprising two or more hydroxy groups, or a poly-C2-C10alkylene glycol, preferably a C3-C8 alkanol comprising two or more hydroxy groups.

7. The article according to any of claims 1 to 6, wherein R is C2-C40alkyl which is uninterrupted or interrupted by -O-, -NH-, -S- and / or a carbonyl group, preferably wherein R is C8-C40alkyl which is uninterrupted or interrupted by -O- and / or a carbonyl group, more preferably wherein R is C10-C22alkyl which is uninterrupted or interrupted by -O- and / or a carbonyl group, more preferably still wherein R is an uninterrupted C11-C21alkyl.

8. The article according to any of claims 1 to 7, wherein the at least one sterically hindered amine ether is selected from the compounds of formula (III), compounds of formula (IV), compounds of formula (V), compounds of formula (VI), compounds of formula (VII), compounds of formula (VIII), and compounds of formula (IX),(III),wherein R1 and R2 are independently selected from formula (Illa),R3 and R4 are independently selected from H and formula (IIIa);(Illa),R5and R6are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl, preferably C4alkyl,R7and R8are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl and unsubstituted or substituted C3-10cycloalkyl, preferably cyclohexyl;(IV),whereinm is 1 to 10,R9and R10are independently selected from unsubstituted or substituted, linear or branched C1-12alkyl,R11and R12are independently selected from unsubstituted or substituted, linear or branched C1-12alkoxy and unsubstituted or substituted C3-10cycloalkoxy;wherein n is a number from 2 to 14;(VII);(IX),wherein R13 is –OC(O)–C11-C20saturated / C17unsaturated, preferably wherein the at least one sterically hindered amine ether is selected from the compounds of formula (III) and the compounds of formula (VII).

9. The article according to any of claims 1 to 8, wherein the at least one phosphorus compound includes a phosphinate of the formula (X)wherein A1 and A2 are independently selected from a group consisting of alkyl, optionally substituted alkyl, benzyl, optionally substituted benzyl, phenyl, optionally substituted phenyl, naphthyl, optionally substituted naphthyl, preferably methyl or benzyl and more preferably where A1 and A2 are both methyl or both benzyl.

10. The article according to any of claims 1 to 9, wherein the article comprises the thiocompound (ii) which is a compound of formula (I), and the sterically hindered amine ether (iii) which is a compound of formula (III).

11. A method for preparing an article, defined according to any of claims 1 to 10, comprising a flame-retardant polypropylene polymer composition, comprising introducinga thio- compound (ii) of formula (I); and either or both of at least one sterically hindered amine ether (iii) or at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite into a polypropylene polymer substrate (i),and then processing the so formed mixture into the article.

12. Use of a thio- compound (ii) of formula (I) as defined in claim 1; and either or both of at least one sterically hindered amine ether (iii) and / or at least one phosphorus compound (iv) selected from at least one of phosphinate, phosphonate, phosphate or alkali metal hypophosphite for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape.

13. The use according to claim 12 which includes any other features according to claims 2 to 10.

14. An additive mixture, for improving the flame retardancy of an article comprising a polypropylene polymer composition, the article being a film or a fibre or a tape, wherein the additive mixture comprises the components,(ii) a thio compound of formula (I) as defined in claim 2; and either or both of (iii) at least one sterically hindered amine ether; and / or(iv) at least one phosphorus compound selected from at least one of phosphinate, phosphonate, phosphate and alkali metal hypophosphite.

15. The additive mixture according to claim 14, wherein the additive mixture comprises any of the features described in any of claims 3 to 10.

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