PLASTIC COMPOSITION WITH IMPROVED WEATHER RESISTANCE

Abstract: The invention relates to a plastic composition that contains a polymer, at least one hindered amine light stabiliser (HALS compound) and at least one bridged amine compound containing at least one N bridgehead. Preferably the plastic composition contains a salt of a bridged amine compound containing at least one N bridgehead and a HALS compound having a molecular weight of less than 1000 g/mol, or a bridged amine compound containing at least one N bridgehead which is not a salt and a HALS compound having a molecular weight of more than 1000 g/mol.

Description: PLASTIC COMPOSITION WITH IMPROVED WEATHER RESISTANCE The invention relates to a plastic composition containing a polymer and at least one hindered amine light stabiliser. In what follows below a hindered amine light stabiliser will be called a 'HALS compound' . A plastic composition containing a polymer and at least one HALS compound is known from US-A- 3.904.581. Patent US-A-3.90 .581 describes a plastic composition that contains a polymer and a 4-amino- piperidine compound, being a HALS compound, as a result of which the plastic composition is stabilised against degradation under the influence of heat and light. It is commonly known that stabilising a plastic composition against degradation under the influence of heat and light, in particular against degradation under the influence of Uv " radiation, causes the plastic composition's weather resistance to improve, as a result of which the plastic composition becomes suitable for certain applications, for example for outdoor applications. Although a plastic composition that contains a polymer and at least one HALS compound already has good weather resistance, there is still a need for a plastic composition with improved weather resistance. The aim of the invention is to provide a plastic composition having such improved weather resistance. This aim is achieved according to the invention in that the plastic composition according to the invention contains a polymer, at least one HALS compound and at least one bridged amine compound containing at least one N bridgehead. It has surprisingly been found that a plastic composition that contains a polymer, at least one HALS compound and at least one bridged amine compound containing at least one N bridgehead exhibits a weather resistance that is substantially better than that of the known plastic composition that does not contain the bridged amine compound containing at least one N bridgehead. It was also found that a plastic composition that contains a polymer, at least one HALS compound and at least one bridged amine compound containing at least one N bridgehead has a weather resistance that is better than the sum of the contributions of the HALS compound and the bridged amine compound would suggest. This is all the more surprising in that it has also been found that a plastic composition that contains a polymer and only one bridged amine compound is scarcely stabilised against degradation under the influence of heat and light. With certain choices of the components of the plastic composition according to the invention it was for example found that the weather resistance of the plastic composition according to the invention sometimes showed a weather resistance that was more than double the weather resistance of the known plastic compositions . In the context of the present invention a Xenon test is used as a measure of the weather resistance. The Xenon test determines a plastic composition's resistance to degradation under the influence of light from a filtered (borosilicate glass) Xenon lamp at a black panel temperature of 62°C with an intensity of 0.35 W.m " .nm "1 , at a wavelength of 340 nm and at a relative humidity of 55 vol . % in a wet/dry cycle of 18 minutes wet and 102 minutes dry. The degradation of the plastic composition is measured as the difference between the carbonyl absorption at 1713 cm "1 and the absorption at 1860 cm "1 as a function of the length of time for which the plastic composition is subjected to said combination of light, temperature and humidity. The weather resistance is expressed as the difference between the measured carbonyl absorptions of the films before and after 2500 hours' ageing according to said combination of light, temperature and humidity. A 'hindered amine light stabiliser' is understood to be compounds having the following general formulas : and combinations hereof. Ri up to and including R 5 are independent substituents . Examples of suitable substituents are hydrogen, ether, ester, amine, amide, alkyl, alkenyl, alkynyl, aralkyl, cycloalkyl and aryl groups, which substituents may in turn contain functional groups; examples of functional groups are alcohols, ketones, anhydrides, imines, siloxanes, ethers, carboxyl groups, aldehydes, esters, amides, imides, amines, nitriles, ethers, urethanes and any combination hereof. A hindered amine light stabiliser may also form part of a polymer. Preferably a compound derived from a substituted piperidine compound is chosen as the HALS compound, in particular any compound derived from an alkyl-substituted piperidyl, piperidinyl or piperazinone compound and substituted alkoxypiperidinyl compounds. Examples of such compounds are - 2,2,6, 6-tetramethyl-4-piperidone; - 2,2,6, 6-tetramethyl-4-piperidinol; - bis- (1,2,2, 6, 6-pentamethylpiperidyl) - (3 ' , 5 ' -di-tert- butyl-4 ' -hydroxybenzyl) butylmalonate; - di- (2 , 2 , 6, 6-tetramethyl-4-piperidyl) sebacate (Tinuvin ® 770) ; - oligomer of N- (2-hydroxyethyl) -2 , 2 , 6, 6-tetramethyl-4- piperidinol and succinic acid (Tinuvin ® 622) ; - oligomer of cyanic acid and N,N-di (2 , 2 , 6, 6- tetramethyl-4 -piperidyl) hexamethylenediamine; - bis- (2 , 2 , 6, 6-tetramethyl-4-piperidinyl) succinate; - bis- (l-octyloxy-2 , 2,6, 6-tetramethyl-4-piperidinyl) sebacate (Tinuvin ® 123) ; - bis- (1, 2, 2 , 6, 6-pentamethyl-4-piperidinyl) sebacate (Tinuvin ® 765) ; - tetrakis- (2,2, 6, 6-tetramethyl-4-piperidyl) -1,2, 3,4- butane-tetracarboxylate; - N,N' -bis- (2,2,6, 6-tetramethyl -4-piperidyl) -hexane- 1,6-diamine (Chimassorb ® T5) ; - oligomer of cyanic acid and N,N-di (2, 2 , 6, 6- tetramethyl-4 -piperidyl) hexamethylenediamine (Chimassorb ® 944) ; - N-butyl-2 ,2,6, 6-tetramethyl-4-piperidinamine; - 2,2'-[(2,2,6, 6-tetramethyl-piperidinyl) -imino] -bis- [ethanol] ; - poly ( (6-morpholine-S-triazine-2,4-diyl) (2,2, 6, 6- tetramethyl-4-piperidinyl) -iminohexamethylene- (2,2,6, 6-tetramethyl-4-piperidinyl) -imino) (Cyasorb ® UV 3346) ; - 5- (2 , 2 , 6, 6-tetramethyl -4 -piperidinyl) -2-cyclo- undecyl-oxazol) (Hostavin ® N20) ; - 1,1'- (1, 2-ethane-di-yl) -bis- (3,3 ' ,5,5' -tetramethyl - piperazinone) ; - 8-acetyl-3-dodecyl-7, 7,9, 9-tetramethyl-1, 3 , 8- triazaspiro (4 , 5) decane-2 , 4-dione; - polymethylpropyl-3-oxy- [4 (2 , 2 , 6, 6-tetramethyl) - piperidinyl) siloxane (Uvasil ® 299) ; - 1, 2 , 3 , 4 -butane-tetracarboxylic acid-1,2,3- tris (1,2,2,6, 6-pentamethyl-4 -piperidinyl) -4-tridecyl ester; - copolymer of alpha-methylstyrene-N- (2 , 2 , 6, 6- tetramethyl-4-piperidinyl) maleimide and N-stearyl- maleimide; - polymer of 1, 2 , 3 , 4-butanetetracarboxylic acid, and beta, beta, beta ' , bet ' -tetramethyl -2 ,4,8,10- tetraoxaspiro [5.5] undecane-3 , 9-diethanol, 1,2,2,6,6- pentamethyl-4 -piperidinyl ester (Mark ® LA63) ; - polymer of 2 , 4 , 8 , 10 -tetraoxaspiro [5.5] undecane-3 , 9- diethanol, beta, beta, beta' ,beta' -tetramethyl- , and with 1, 2 , 3 , 4-butanetetracarboxylic acid, 2,2,6,6- tetramethyl-4 -piperidinyl ester (Mark ® LA68) ; - D-glucitol, 1, 3 : 2 , 4-bis-O- (2 , 2 , 6, 6-tetramethyl-4- piperidinylidene) - (HALS 7) ; - oligomer of 7-oxa-3,20- diazadispiro [5.1.11.2] heneicosan-21-one, 2,2,4,4- tetramethyl-20- (oxiranylmethyl) (Hostavin ® N30) ; - propanedioic acid, [ (4-methoxyphenyl) methylene] - ,bis (1,2,2,6, 6-pentamethyl -4 -piperidinyl) ester (Sanduvor ® PR 31) ; - formamide, N,N' -1, 6-hexanediylbis [N- (2 , 2 , 6, 6- tetramethyl-4 -piperidinyl (Uvinul ® 4050H) ; - 1, 3, 5-triazine-2,4, 6-triamine, N,N" "- [1, 2- ethanediylbis [ [ [4 , 6-bis [butyl (1,2,2,6,6- pentamethyl-4-iperidinyl) amino] -1,3, 5-triazine-2- yl] imino] -3 , 1-propanediyl] ] -bis [N' ,N" '-dibutyl- N',N"-bis(l,2,2,6, 6-pentamethyl-4 -piperidinyl) (Chimassorb ® 119) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (2, 2 , 6, 6 -tetramethyl-4 -peridinyl) ester (Cyasorb ® UV-500) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (1, 2, 2, 6, 6-pentamethyl -4 -peridinyl) ester (Cyasorb ® UV-516) ; - N-2 , 2,6, 6-tetramethyl-4-piperidinyl-N-amino-oxamide; - 4 -acryloyloxy-1, 2,2, 6, 6-pentamethyl -4 -piperidine; - l,5,8,12-tetrakis[2 ' ,4' -bis (1" , 2 " , 2 " , 6" , 6" - pentamethyl -4 " -piperidinyl (butyl ) amino) - 1 ' , 3 ' , 5 ' - triazin-6'-yl] -1,5,8, 12-tetrazadodecane; HALS PB-41 (Clariant Huningue S.A.); - Nylostab ® S-EED (Clariant Huningue S.A.); 3-dodecyl-l- (2,2,6, 6 -tetramethyl -4 -piperidyl) - pyrrolidin-2 , 5-dione; Uvasorb ® HA88; - 1,1'- (1,2-ethane-di-yl) -bis- (3,3' ,5, 5' -tetra-methyl- piperazinone) (Good-rite ® 3034) ; - 1, 1' , 1 ' " - (1, 3 , 5-triazine-2 , 4, 6-triyltris ( (cyclohexylimino) -2, 1-ethanediyl) tris (3,3,5,5- tetramethylpiperazinone) ; (Good-rite ® 3150) ; - 1,1',1"-(1,3, 5-triazine-2, 4 , 6-triyltris ( (cyclohexylimino) -2 , 1-ethanediyl) tris(3,3,4,5,5- tetramethylpiperazinone) (Good-rite ® 3159) . Preferably use is made of - di- (2 , 2, 6, 6-tetramethyl-4 -piperidyl) sebacate (also known under the trade name of Tinuvin R 770) , - oligomer of N- (2-hydroxyethyl) -2 , 2 , 6, 6-tetramethyl-4- piperidinol and succinic acid (Tinuvin ® 622); - bis- (l-octyloxy-2 ,2,6, 6-tetramethyl-4-piperidinyl) sebacate (Tinuvin ® 123) ; - bis- (1, 2 , 2, 6, 6-pentamethyl-4 -piperidinyl) sebacate (Tinuvin ® 765); N,N' -bis- (2 , 2 , 6, 6-tetramethyl-4- piperidyl) -hexane-1 , 6-diamine (Chimassorb ® T5) ; - poly ( (6-morpholine-S-triazine-2,4-diyl) (2,2,6,6- tetramethyl-4 -piperidinyl ) -iminohexamethylene- (2,2,6, 6-tetramethyl-4-piperidinyl) -imino) (Cyasorb® UV 3346) ; - 5- (2 , 2 , 6, 6-tetramethyl-4-piperidinyl) -2-cyclo- undecyl-oxazol) (Hostavin ® N20) ; - polymethylpropyl-3-oxy- [4(2,2,6, 6-tetramethyl) - piperidinyl) siloxane (Uvasil ® 299) ; - 1 , 2 , 3 , 4-butanetetracarboxylic acid, polymer with beta, beta, beta' ,beta' -tetramethyl-2 , 4,8, 10- tetraoxaspiro [5.5] undecane-3 , 9-diethanol , 1,2,2,6,6- pentamethyl -4 -piperidinyl ester (Mark ® LA63) ; - 2,4,8, 10 -tetraoxaspiro [5.5] undecane-3 , 9- diethanol,beta,beta, beta ' ,beta ' -tetramethyl- , polymer with 1, 2, 3 , 4-butanetetracarboxylic acid, 2,2,6,6- tetramethyl-4-piperidinyl ester (Mark ® LA68) ; - D-glucitol, 1, 3 : 2 , -bis-O- (2 , 2 , 6, 6-tetramethyl-4- piperidinylidene) (HALS 7) ; - oligomer of 7-oxa-3,20- diazadispiro [5.1.11.2] heneicosan-21-one, 2 , 2,4,4- tetramethyl-20- (oxiranylmethyl) (Hostavin ® N30) ; - propanedioic acid, [ (4-methoxyphenyl) methylene] - ,bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) ester (Sanduvor ® PR 31) ; - formamide, N,N' -1 , 6-hexanediylbis [N- (2 , 2 , 6, 6- tetramethyl-4-piperidinyl (Uvinul ® 4050H) ; - 1, 3 , 5-triazine-2 , 4, 6-triamine, N,N""-[1,2- ethanediylbis [ [ [4, 6-bis [butyl (1,2,2,6,6- pentamethyl-4-iperidinyl) amino] -1,3, 5-triazine-2- yl] imino] -3 , 1-propanediyl] ] -bis [N' ,N"-dibutyl- N' , N' '-bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) (Chimassorb ® 119) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (2 , 2, 6, 6-tetramethyl-4-peridinyl) ester (Cyasorb ® UV-500) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (1, 2, 2, 6, 6-pentamethyl-4-peridinyl) ester (Cyasorb ® UV516) ; - mixtures of esters of 2 , 2 , 6, 6-tetramethyl-4- piperidinol and fatty acids (Cyasorb ® UV 3853) ; HALS PB-41 (Clariant Huningue S.A.); - Nylostab ® S-EED (Clariant Huningue S.A.); - 3-dodecyl-l- (2,2,6, 6-tetramethyl-4-piperidyl) - pyrrolidin-2, 5-dione Uvasorb ® HA88; - 1,1'- (1, 2-ethane-di-yl) -bis- (3,3' ,5,5' -tetra-methyl- piperazinone) (Good-rite ® 3034) ; - 1,1',1"-(1,3, 5-triazine-2 , 4, 6-triyltris ( (cyclohexylimino) -2 , 1-ethanediyl) tris (3,3,5,5- tetramethylpiperazinone) ; (Good-rite ® 3150) ; - 1,1',1'"-(1,3, 5-triazine-2,4, 6- triyltris ( (eyelohexylimino) -2, 1- ethanediyl) tris (3,3,4,5, 5-tetramethylpiperazinone) (Good-rite ® 3159) . The bridged amine compound containing at least one N bridgehead that can be used in the context of this invention is preferably a compound derived from a compound having the general formulas in which M x to M 4 are bridgeheads and the individual bridgeheads are chosen independently of one another from the group comprising carbon, nitrogen, silicon and phosphorus, it being understood that at least one bridgehead must always be a nitrogen atom and carbon and silicon may be substituted; an N bridgehead is defined as a bridgehead that is a nitrogen atom; Di, D m , D n , D 0 , D p and D q here each represent a chain with a length of from 1 to 20 atoms, the number of atoms of which the chains are composed being equal to l,m,n,o,p and q, it being possible to choose each number and type of atoms independently of one another and it being possible for the chains to have different lengths and to be composed of different types of atoms. The chains may also contain side groups, the number of atoms in the side groups not being included in the number of atoms in the chain. Suitable choices for atoms of which the chains may be composed are carbon, nitrogen, oxygen, silicon and phosphorus. Preferably the chains are composed of from 1 to 3 carbon atoms . Preferably the bridged amine compound containing at least one N bridgehead is used with a HALS compound in a ratio, relative to the amount of HALS compound, of between approximately 1:20 (m.-m) and approximately 20:1 (rrt:m) , more preferably in a ratio of between approximately 1:10 (m:m) and approximately 10:1 (m:m) , most preferably in a ratio of between approximately 1:5 (m:m) and approximately 5:1 (m:m) . Within the limits of the ratios last mentioned the weather resistance is better than would be expected on the basis of the contained amounts of the bridged amine compound containing at least one N bridgehead and the HALS compound. The amount of bridged amine compound containing at least one N bridgehead that can be used in the plastic composition may vary within a wide range, which can easily be determined by an average person skilled in the art. The range may vary in accordance with for example the type of polymer, the type of HALS compound, the other additives in the additives package, the weather resistance to be achieved or in general the type, the properties and the specific application of the plastic composition. It is for example possible for the bridged amine compound containing at least one N bridgehead to be present in the plastic composition in an amount, relative to the amount of polymer in the plastic composition, of between preferably approximately 0.01 wt.% and approximately 10.0 wt.%, more preferably in an amount of between 0.05 wt.% and 5 wt.%, most preferably in an amount of between 0.1 wt . % and 2.5 wt . % . Suitable choices for the bridged amine compound containing at least one N bridgehead are - derivatives of 7-nitro-l, 3 , 5, triazadamantane and 7- amino-1, 3,5, -triazadamantane, - derivatives of 7-amino-1, 3, 5 -triazadamantane having the general structure I or II: where R and R' are independent substituents; examples of suitable substituents are hydrogen, ether, ester, amine, amide, alkyl, alkenyl, alkynyl, aralkyl, cycloalkyl and aryl groups, which substituents may in turn contain functional groups; examples of functional groups are alcohols, ketones, anhydrides, imines, siloxanes, ethers, carboxyl groups, aldehydes, esters, amides, imides, amines, nitriles, ethers, urethanes and any combination thereof. The substituent may moreover connect several compounds I and/or II to one another. - derivatives obtained in a reaction of 7-amino-l, 3 , 5- triazadamantane with compounds which one or more functional groups. Examples of these functional groups are aldehydes, acids, esters, amides, ketones, anhydrides and isocyanates . - triazadamantane derivatives that are bound to a polymer (preferably a polyolefin) with the aid of an imide functionality; - polymer-bound compounds obtained in the reaction of 7-amino-l, 3 , 5-triazadamantane with a polymer (preferably a polyolefin) functionalised with maleic anhydride; - hexamethylenetetra ine (HMTA) , diazabicyclo [2.2.2] - octane (DABCO) or derivatives thereof. HMTA and DABCO are commercially readily available or can be easily prepared using commonly known processes. HMTA can for example be easily prepared from the cheap, readily available basic raw materials ammonia and formaldehyde. The bridged amine compound containing at least one N bridgehead is preferably used as a salt, more preferably as an ammonium salt in combination with a HALS compound having a molecular weight of less than 1000 g/mol. Preferably a carboxylic acid is chosen as a salt former. Examples of suitable carboxylic acids are aliphatic carboxylic acids, aliphatic dicarboxylic acids and aromatic carboxylic acids. Suitable choices are stearic acid, sebacic acid, cyclohexanedicarboxylic acid and benzenetricarboxylic acid. Preferably the bridged amine compound containing at least one N bridgehead is not used as a salt if the salt former contains a halogen or sulphur, it being commonly known that compounds containing halogen or sulphur can reduce the effect of the HALS stabiliser. Preferably the bridged amine compound containing at least one N bridgehead is substituted with at least one substituent having a molecular weight preferably of at least 50, more preferably of at least 100. It has surprisingly been found that the use of the bridged amine compound containing at least one N bridgehead either in the form of its salt, or substituted with at least one substituent having a molecular weight of more than about 50, or in the form of its salt and substituted with at least one substituent having a molecular weight of more than about 50, results in a plastic composition having even better weather resistance. The plastic composition according to the invention preferably contains a thermoplastic polymer chosen from the group consisting of polyolefins and styrene polymers. Suitable choices are for example - propylene polymers, such as propylene homopolymer, ethylene-propylene random copolymer, ethylene-propylene block copolymer and mixtures hereof. Also defined as propylene polymers in the context of this invention are mixtures containing at least 50 wt.% of one of the aforementioned propylene polymers with for example polyethylene or ethylene-propylene-diene copolymers ; - ethylene polymers, such as low-density polyethylene (LDPE) , high-density polyethylene (HDPE) , very-low- density polyethylene (VLDPE) , linear-low-density polyethylene (LLDPE) or ultra-high-molecular-weight polyethylene (UHMWPE) ; - butylene polymers, such as polybutylene-1. Suitable choices of styrene polymers are for example polystyrene, high-impact-resistant polystyrene (HIPS) , styrene-acrylonitrile copolymer (SAN) , acrylonitrile- butadiene-styrene copolymer (ABS) , styrene-maleic anhydride copolymer (SMA) and styrene-maleimide copolymer (SMI) . More preferably the polymer is a propylene polymer or an ABS, even more preferably a propylene polymer. The bridged amine compound containing at least one N bridgehead can easily, and at any desired time before a plastic article, such as a moulded part, foil, film, fibre, coating, foam, tape, latex or powder, is produced from the plastic composition, be introduced into the plastic composition with the aid of one of the many standard methods known to a person skilled in the art. According to a first method the bridged amine compound containing at least one N bridgehead, for example in the form of a powder, solution, emulsion or suspension, is mixed with the other components of the plastic composition, which are in the form of for example a powder or a melt. According to a second method the bridged amine compound containing at least one N bridgehead is first mixed with at least one HALS compound and optionally other additives in a so-called additives package, for example in the form of a powder, solution, emulsion or suspension, and this package is subsequently added to the plastic, for example in the form of a powder or as a melt . The plastic composition containing a polymer, at least one HALS compound and at least one bridged amine compound containing at least one N bridgehead may also contain other additives, for example antioxidants, thermal and UV stabilisers, metal deactivators, fillers, pigments, flame retardants, optical whitening agents and similar additives that are used in plastic compositions. The invention will be further elucidated with reference to the examples without restricting itself hereto. Examples The following general processes were followed in the examples. Preparation of the various bridged amines HMTA stearate: A solution of 28.45 grams (0.1 mol) of stearic acid in ethanol was added, drop by drop, with stirring, to a solution of 14 grams (0.1 Mol) of DABCO in ethanol. The mixture was concentrated by evaporation with the aid of a film evaporator. 7-Nitro-l, 3 , 5-triazadamantane : A mixture of 56.8 ml (1.0 mol) of nitromethane and 45 ml (1.2 mol) of formic acid was added, drop by drop, to a solution of 140.2 grams (1.0 mol) of hexamethylenetetramine in 500 ml of ethanol (80%) , with constant stirring and reflux. The mixture was refluxed for 4 hours and stored overnight . The crystalline product that had separated was washed several times with water and ethanol. After recrystallisation in water the product (white needles) was dried in the vacuum dryer. (Literature: Collection Czechoslov. Chem. Commun [vol.40], 1975, pp. 2179-82). 7-Amino-1 , 3 , 5-triazadamantane : 15.0 grams of 7-nitro-l, 3 , 5- triazadamantane, 100 ml of methanol and 1.5 grams of wet Raney Cobalt catalyst were introduced into a Parr autoclave (160 ml capacity) fitted with a stirrer and baffles. The hydrogenation was carried out for an hour at maximum speed, in hydrogen at a pressure of 8 MPa and 80°C. After the catalyst had been removed through filtration the methanol was removed by means of a film evaporator. The crystalline product was dried in a vacuum dryer. 7-Dodecylideneamino-l, 3 , 5-triazadamantane : 8.4 grams of 7-amino-l, 3 , 5-triazadamantane, 10.0 grams of dodecanal, 85 ml of methanol, 10 ml of toluene and 2.0 grams of wet Raney Cobalt catalyst were introduced into a Parr autoclave (160 ml capacity) fitted with a stirrer and baffles. The reaction was carried out for an hour in a nitrogen atmosphere (0.2 MPa) at max. speed and 80°C. After the catalyst had been removed through filtration the filtrate was evaporated with a rotavapor and dried in a vacuum dryer. Preparation of a plastic composition A polypropylene powder (PP) was mixed with a dichloromethane solution containing an amount of a HALS compound. This mixture was dried in an oven (Hereaus Vacutherm) for 24 hours at a temperature of 28°C and a pressure of approximately 2630Pa. Next, a dichloromethane solution of the bridged amine compound containing at least one N bridgehead was added to the plastic composition. This plastic composition was also dried in the same way as described above. Production of PP films and plates The PP composition was compressed to form a film using a Fontijne press (type TP200, 5 minutes pressureless preheating at 190°C, after which the force was raised to 100-120 kNewton, followed by 10 minutes cooling at said pressure) . The thickness was checked with a Heidenhain electronic meter. The films had an average thickness of 120 -150 μm. Determination of the weather resistance The weather resistance of a plastic composition was determined in a weather resistance test, carried out in an Atlas Material Testing Technology Weather-0 meter (type Ci65) according to the method described in the above description. The degradation was measured with the aid of FT-IR. The weather resistance is then expressed as the difference between the measured carbonyl absorptions of the films before and after 2500 hours' ageing according to the aforementioned combination of light, temperature and humidity. The following abbreviations and trade names were used in the examples : PP: polypropylene HMTA: hexamethylenetetramine. HMTA stearate: monosalt of stearic acid and HMTA ATADE: 7-amino-l, 3 , 5-triazadamantane dodecylidene-atade : 7-dodecylideneamino-l , 3,5- triazadamantane . Example I A series of plastic compositions was prepared using the process described above. The composition of the plastic composition was varied. PP was chosen as the polymer (Stamylan R , type P83ml8, DSM, the Netherlands) . Films were produced from the plastic compositions using the process described above. The films were subjected to a weather resistance test and the weather resistance was determined as described above. The results are summarised in Table 1. Table 1: Weather resistance of various compounds containing different HALSes and bridged amines This shows that the plastic composition according to the invention preferably contains a salt of a bridged amine compound containing at least one N bridgehead and a HALS compound having a molecular weight of less than 1000 g/mol, or a bridged amine compound containing at least one N bridgehead which is not a salt and a HALS compound having a molecular weight of more than 1000 g/mol.

Claims: C L A I M S 1. Plastic composition containing a polymer and at least one hindered amine light stabiliser, characterised in that the plastic composition also contains at least one bridged amine compound containing at least one N bridgehead. 2. Plastic composition according to Claim 1, the ratio of the bridged amine compound containing at least one N bridgehead to the HALS compound being between 1:5 (m:m) and 5:1 (m:m) . 3. Plastic composition according to Claim 1 or Claim 2 , the amine compound containing at least one N bridgehead being present in an amount, relative to the total amount of polymer in the plastic composition, of between 0.1 and 2.5 wt.%. 4. Plastic composition according to any one of Claims 1-3, the hindered amine light stabiliser being di- (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (also known under the trade name of Tinuvin ® 770), oligomer of N- (2-hydroxyethyl) - 2 , 2 , 6, 6-tetramethyl-4-piperidinol and succinic acid (Tinuvin ® 622); bis- (l-octyloxy-2 , 2 , 6 , 6- tetramethyl-4-piperidinyl) sebacate (Tinuvin ® 123); bis- (1 , 2 , 2 , 6 , 6-pentamethyl-4 -piperidinyl) sebacate (Tinuvin ® 765); N,N' -bis- (2 , 2 , 6 , 6- tetramethyl-4-piperidyl) -hexane-1, 6-diamine (Chimassorb ® T5) ; poly ( (6-morpholine-S-triazine- 2 , 4-diyl) (2,2,6, 6-tetramethyl-4-piperidinyl) - iminohexamethylene- (2,2,6, 6-tetramethyl-4- piperidinyl) -imino) (Cyasorb ® UV 3346); 5- (2,2,6, 6-tetramethyl-4-piperidinyl) -2-cyclo- undecyl-oxazol) (Hostavin ® N20) ; polymethylpropyl-3-oxy- [4 (2,2,6, 6-tetramethyl) - piperidinyl) siloxane (Uvasil ® 299) , - 1, 2, 3 , 4-butanetetracarboxylic acid, polymer with beta, beta, beta" ,beta' -tetramethyl - 2,4,8, 10 -tetraoxaspiro [5.5] undecane-3 , 9- diethanol, 1,2,2,6, 6 -pentamethyl -4 -piperidinyl ester (Mark LA63) ; - 2,4,8, 10-tetraoxaspiro [5.5] undecane-3, 9- diethanol, beta, beta, beta' ,beta ' -tetramethyl- , polymer with 1 , 2 , 3 , 4-butanetetracarboxylic acid, 2, 2, 6, 6-tetramethyl-4-piperidinyl ester (Mark LA68) ; - D-glucitol, 1, 3 : 2 , 4-bis-O- (2 , 2 , 6, 6 -tetramethyl - 4-piperidinylidene) - (HALS 7) ; - oligomer of 7-oxa-3,20- diazadispiro [5.1.11.2] heneicosan-21- one, 2,2,4 , 4-tetramethyl-20- (oxiranylmethyl) (Hostavin N30) ; - propanedioic acid, [(4- methoxyphenyl) methylene] - ,bis (1,2,2,6,6- pentamethyl -4 -piperidinyl) ester (Sanduvor PR 31) ; - formamide, N,N' -1 , 6-hexanediylbis [N- (2 , 2 , 6, 6- tetramethyl -4 -piperidinyl (Uvinul 4050H) ; - 1, 3 , 5-triazine-2 , 4, 6-triamine, N,N""-[1,2- ethanediylbis [ [ [4, 6 -bis [butyl (1,2,2,6,6- pentamethyl -4 -iperidinyl) amino] -1,3, 5-triazine- 2-yl] imino] -3 , 1-propanediyl] ] -bis [N' ,N"- dibutyl-N' ,N"-bis (1,2,2,6, 6 -pentamethyl -4- piperidinyl) (Chimassorb 119) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (2 , 2 , 6 , 6-tetramethyl-4-peridinyl) ester (Cyasorb UV-500) ; - 1, 5-dioxaspiro (5,5) undecane 3 , 3-dicarboxylic acid, bis (1 , 2 , 2 , 6, 6 -pentamethyl -4 -peridinyl) ester (Cyasorb ® UV516) ; - mixtures of esters of 2 , 2 , 6, 6-tetramethyl-4- piperidinol and fatty acids (Cyasorb ® UV 3853) ; HALS PB-41 (Clariant Huningue S.A.); Nylostab S-EED (Clariant Huningue S.A.); 3-dodecyl-l- (2,2,6, 6-tetramethyl-4-piperidyl) - pyrrolidin-2 , 5-dione Uvasorb HA88; 1,1'- (1,2-ethane-di-yl) -bis- (3,3' ,5,5' -tetramethyl-piperazinone) (Good-rite ® 3034) ; 5-triazine-2,4, 6-triyltris ( (cyclohexylimino) -2 , 1-ethanediyl) tris (3,3,5,5- tetramethylpiperazinone) (Good-rite ® 3150) ; 1, 1', 1"- (1,3,5-triazine-2, 4,6- triyltris ( (cyclohexylimino) -2, 1- ethanediyl) tris (3,3,4,5,5- tetramethylpiperazinone) (Good-rite ® 3159) ; 5. Plastic composition according to any one of Claims 1 to 4, characterised in that the bridged amine compound containing at least one N bridgehead is hexamethylenetetramine, diazabicyclo [2.2.2] octane or a derivative of either compound. 6. Plastic composition according to any one of Claims 1 to 5, characterised in that the bridged amine compound containing at least one N bridgehead is not a salt and the HALS compound has a molecular weight of more than 1000 g/mol. 7. Plastic composition according to any one of Claims 1 to 6 , characterised in that the bridged amine compound containing at least one N bridgehead is a salt and the HALS compound has a molecular weight of less than 1000 g/mol. 8. Plastic composition according to Claim 7, characterised in that the salt is an ammonium salt. 9. Plastic composition according to any one of Claims 1 to 8, characterised in that the bridged amine compound containing at least one N bridgehead is substituted with at least one aliphatic or aromatic substituent having a molecular weight of at least 50. 10. Plastic composition according to any one of Claims 1 to 9, characterised in that the polymer is chosen from the group comprising propylene polymers and acrylonitrile-butadiene-styrene copolymer (ABS) . 11. Use of a bridged amine compound containing at least one N bridgehead, which is not a salt, in combination with a hindered amine light stabiliser having a molecular weight of more than 1000 g/mol as a stabiliser for a plastic composition with improved weather resistance. 12. Use of a salt of a bridged amine compound containing at least one N bridgehead in combination with a hindered amine light stabiliser having a molecular weight of less than 1000 g/mol as a stabiliser for a plastic composition with improved weather resistance. 13. Articles produced from the plastic composition according to any one of Claims 1-10. 14. Plastic composition with improved weather resistance as described and explained with reference to the examples .

Inventors: GIJSMAN PIETER, GIJSMAN, PIETER
Applicants: DSM NV, GIJSMAN PIETER, DSM N.V., GIJSMAN, PIETER
Application year: 1999
Main classification: C08K5
IPC codes: C08K5