Light stabilizer mixture

Abstract

A stabilizer mixture containing a sterically hindered amine light stabilizer and a triazine UV absorber in a specific ratio.

Claims

1. A stabilizer mixture, comprising components (A) and (B), wherein: component (A) is at least one compound of formula (A), ##STR00016## wherein A.sub.1 is C.sub.2-C.sub.18alkylene, C.sub.5-C.sub.7cycloalkylene or C.sub.1-C.sub.4alkylenedi(C.sub.5-C.sub.7cycloalkylene), A.sub.2 independently of one another are hydrogen, C.sub.1-C.sub.12alkyl, C.sub.1-C.sub.12alkyloxy, C.sub.5-C.sub.12cycloalkyl or C.sub.5-C.sub.12cycloalkyloxy, A.sub.3 and A.sub.4 independently of one another are hydrogen, C.sub.1-C.sub.12alkyl, C.sub.5-C.sub.12cycloalkyl or a group of formula (a-1), ##STR00017## or A.sub.3 and A.sub.4, together with the nitrogen atom to which they are bonded, form a 5- to 10-membered heterocyclic ring and a is a number from 1 to 20 and the repeating units are identical or different; component (B) is at least one compound of formula (B), ##STR00018## wherein E.sub.1 is C.sub.1-C.sub.18alkyl and E.sub.2, E.sub.3, E.sub.4 and E.sub.5 independently of one another are hydrogen, C.sub.1-C.sub.18alkyl, phenyl or phenyl substituted by 1, 2 or 3 C.sub.1-C.sub.4alkyl; and a weight ratio of (A) to (B) is 23/1 to 40/1.

2. The stabilizer mixture of claim 1, wherein A.sub.1 is C.sub.2-C.sub.8alkylene or cyclohexylene, A.sub.2 independently of one another are hydrogen, C.sub.1-C.sub.8alkyl, C.sub.1-C.sub.12alkyloxy, cyclohexyl or cyclohexyloxy, A.sub.3 and A.sub.4 independently of one another are hydrogen, C.sub.1-C.sub.8alkyl or a group of formula (a-1) or A.sub.3 and A.sub.4, together with the nitrogen atom to which they are bonded, form a morpholino group and a is a number from 1 to 10; and E.sub.1 is C.sub.1-C.sub.8alkyl and E.sub.2, E.sub.3, E.sub.4 and E.sub.5 independently of one another are hydrogen, C.sub.1-C.sub.4alkyl or phenyl.

3. The stabilizer mixture of claim 1, wherein component (A) is at least one compound selected from formulae (A-0), (A-1), (A-2), (A-3) and (A-4): ##STR00019## wherein 1 or 2 of A.sub.2 are hydrogen and the remaining A.sub.2 are propyloxy; ##STR00020## wherein a is a number from 1 to 20; ##STR00021## wherein a is a number from 1 to 20.

4. The stabilizer mixture of claim 1, wherein component (B) is at least one compound selected from formulae (B-1), (B-2) and (B-3); ##STR00022##

5. The stabilizer mixture of claim 1, further comprising component (C) which is a benzotriazole.

6. The stabilizer mixture of claim 1, further comprising component (D) which is at least one compound selected from formulae (D-1) and (D-2); ##STR00023## wherein b is a number from 2 to 20.

7. A composition comprising: (I) an organic material subject to degradation induced by light, heat, oxidation or an agrochemical compound; and (II) the stabilizer mixture of claim 1.

8. The composition of claim 7, wherein the organic material is selected from the group consisting of linear low density polyethylene, low density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-butyl acrylate copolymer, and polypropylene homo- or copolymer.

9. The composition of claim 7, further comprising an additive selected from the group consisting of an antioxidant, a slip agent, an anti-block agent, a thermal filler, a pigment, an anti-fog agent and an anti-mist agent.

10. An article, which is made of the composition of claim 7.

11. The article of claim 10, which is a monolayer film or a multilayer film of three to seven layers.

12. The article of claim 10, which is a multilayer film which comprises a compound of formula (A) in at least one layer and a compound of formula (B) in another layer.

13. The article of claim 10, which is a greenhouse film cover.

14. The article of claim 13, wherein the greenhouse film cover contacts an agrochemical compound.

15. A method for stabilizing an organic material against degradation induced by light, heat, oxidation or an effect of an agrochemical compound, the method comprising incorporating the stabilizer mixture of claim 1 into the organic material.

Description

EXAMPLES

(1) Stabilizers Listed in Tables 1, 2, 3 and 4 Below:

(2) ##STR00013##
wherein a is a number from 1 to 10.

(3) ##STR00014##
wherein a is a number from 1 to 10.

(4) ##STR00015##
wherein b is a number from 2 to 10.
A) Preparation of the Film Samples:

(5) Stabilization of LDPE (low density polyethylene) multi-layer films: Formulations containing LDPE powder (Polimeri Europa Riblene® FC 30, characterized by a density of 0.922 g/cm.sup.3 and a melt flow index (190° C./2.16 Kg) of 0.27 g/10 min), 0.04% by weight, relative to the weight of the LDPE, of tris{2,4-di-tert-butylphenyl} phosphite, 0.01% by weight, relative to the weight of the LDPE, of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and the stabilizer mixtures indicated in Tables 1, 2 and 4, are prepared. The formulations are mixed in a turbo-mixer. Each formulation is extruded at a maximum temperature of 200° C. in a lab-scale single-screw Collin extruder (ø 42 mm, L/D=25). Then, each final formulation is blown in a lab-scale Collin® 5-layer blow-extruder (ø 20-25-30 mm, L/D 25), at a maximum temperature of 210° C., to give a 5-layer film of overall 180 μm thickness (55 μm-7.5 μm-55 μm-7.5 μm-55 μm), having the same formulation in all layers.

(6) Test Method A-I:

(7) An agrochemical treatment is carried out on the prepared films before artificial weathering. Specimens of the films for each formulation are mounted on a small experimental greenhouse (geographical coordinates: Lat. 44°25′40″N Long. 11°16′39″E), inside of which two burners of the type used in common agricultural practice are placed to allow sublimation of elemental sulfur, a widely used fungicide. The so-called “sulfur burning” is carried out for 13 consecutive days, 6 hours per day, while the films are mounted on the small experimental greenhouse. The film specimens are covered with an additional single piece of opaque film to minimize the direct exposure of the sample to sunlight, in order to minimize in turn the effects of solar irradiation and hence the possible differences on samples exposed in subsequent test series. The amount of burnt sulfur is regulated and the weathering conditions closely monitored, so as to obtain the desired level of contamination from sulfur in the film samples, measured by Inductively Coupled Plasma.

(8) After the agrochemical treatment, the film specimens for each formulation are exposed in an Atlas Weather-O-Meter (WOM, as per ASTM G155, 0.35 W/m2 at 340 nm, dry cycle), for accelerated light weathering. Specimens of the film samples are taken at defined intervals of time after exposure and underwent tensile testing. The residual tensile strength is measured, by means of a Zwick® Z1.0 constant velocity tensiometer (as per modified ISO 527), in order to evaluate the decay of the mechanical properties of the film samples, as a consequence of the polymer degradation after its oxidation. The test results are listed in Table 1:

(9) TABLE-US-00001 TABLE 1 Film samples contaminated up to level of sulfur of 5000 ppm and exposed in a WOM. Time until retained Weight ratio of elongation at break components (A) in hours is 50% of Stabilizer mixture to (B) the initial value 1.000% of Compound (A-4-1) 33/1 6000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.900% of Compound (A-4-1) 33/1 6000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.100% of Compound (D-1) 0.700% of Compound (A-4-1) 33/1 6000 0.300% of Compound (A-3-1) 0.03% of Compound (B-1) 0.097% of Compound (C-1) 0.700% of Compound (A-4-1) 33/1 6000 0.300% of Compound (D-2) 0.03% of Compound (B-1) 0.097% of Compound (C-1) 0.700% of Compound (A-4-1) 23/1 6000 0.03% of Compound (B-1) 0.097% of Compound (C-1) 0.100% of Compound (D-1) 0.200% of Compound (D-2) % means % by weight, relative to the weight of LDPE.
Test Method A-II:

(10) Specimens of the multilayer films are put into a dryer. The dryer is immersed into a water bath kept at 30° C. The films inside the dryer are hanged over a 2 liter solution containing 836 ml of a commercial solution of metam-sodium (Sodium N-methyldithiocarbamate). The films are stored in the dryer for 20 days. This simulates an agrochemical treatment in presence of the films.

(11) After the agrochemical treatment, the film specimens for each formulation are exposed in an Atlas Weather-O-Meter (WOM, as per ASTM G155, 0.35 W/m2 at 340 nm, dry cycle), for accelerated light weathering. Specimens of the film are taken at defined intervals of time after exposure and underwent tensile testing. The residual tensile strength is measured, by means of a Zwick® Z1.0 constant velocity tensiometer (as per modified ISO 527), in order to evaluate the decay of the mechanical properties of the plastic film, as a consequence of the polymer degradation after its oxidation. The results are listed in Table 2.

(12) TABLE-US-00002 TABLE 2 Film samples contaminated up to level of sulfur of 5000 ppm using Metam-Sodium and exposed in a WOM. Time until retained Weight ratio of elongation at break components (A) in hours is 50% of Stabilizer mixture to (B) the initial value 1.000% of Compound (A-4-1) 33/1 7000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.900% of Compound (A-4-1) 30/1 7000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.100% of Compound (D-1) 0.700% of Compound (A-4-1) 33/1 7000 0.300% of Compound (A-3-1) 0.03% of Compound (B-1) 0.097% of Compound (C-1) 0.700% of Compound (A-4-1) 23/1 7000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.300% of Compound (D-2) 0.700% of Compound (A-4-1) 23/1 7000 0.030% of Compound (B-1) 0.097% of Compound (C-1) 0.100% of Compound (D-1) 0.200% of Compound (D-2) % means % by weight, relative to the weight of LDPE.
B) Preparation of the Film Samples:

(13) Stabilization of LDPE (low density polyethylene) mono-layer films: Formulations containing LDPE powder (Polimeri Europa Riblene® FF 29, characterized by a density of 0.921 g/cm.sup.3 and a melt flow index (190° C./2.16 Kg) of 0.60 g/10 min), 0.04% by weight of tris{2,4-di-tert-butylphenyl} phosphite, 0.01% by weight of octadecyl 3-(3,5-di-tertbutyl-4-hydroxyphenyl)propionate and the stabilizer mixture indicated in Table 3 are prepared. The formulations are mixed in a turbo-mixer. Each formulation is extruded at a maximum temperature of 200° C. in a OMC twin-screw extruder (ø 19 mm, L/D=25). Then, each final formulation is blown in a Dolci mono-layer blow-extruder (ø 40 mm, L/D 26), at a maximum temperature of 210° C., to give a mono-layer film of overall 150 μm thickness.

(14) Text Method B-1:

(15) Specimens of the monolayer films are put into a dryer. The dryer is immersed into a water bath kept at 30° C. The films inside the dryer are hanged over a 2 liter solution containing 836 ml of a commercial solution of metam-sodium (Sodium N-methyldithiocarbamate). The films are stored in the dryer for 20 days. This simulates an agrochemical treatment in presence of the films. After the agrochemical treatment, the film specimens of each formulation are exposed in an Atlas Weather-O-Meter (WOM, as per ASTM G155, 0.35 W/m2 at 340 nm, dry cycle), for accelerated light weathering. Specimens of the required formulations are taken at defined intervals of time after exposure and underwent tensile testing. The residual tensile strength is measured, by means of a Zwick® Z1.0 constant velocity tensiometer (as per modified ISO 527), in order to evaluate the decay of the mechanical properties of the plastic film, as a consequence of the polymer degradation after its oxidation. The results are listed in Table 3.

(16) TABLE-US-00003 TABLE 3 Film samples contaminated up to level of sulfur of 5000 ppm using Metam-Sodium and exposed in a WOM. Retained elongation at break (as % of Weight ratio of initial) after 6000 components (A) hours WOM + Stabilizer mixture to (B) treatment 0.600% of Compound (A-4-1) 24/1 80 0.025% of Compound (B-1) % means % by weight, relative to the weight of LDPE.

(17) The following stabilizer mixtures also show an excellent stabilizing effect of LDPE film samples in the above described test methods.

(18) TABLE-US-00004 TABLE 4 Weight ratio of components (A) Stabilizer mixture to (B) 1.000% of Compound (A-4-1) 33/1 0.030% of Compound (B-1) 1.000% of Compound (A-2) 33/1 0.030% of Compound (B-1) 0.500% of Compound (A-1) 33/1 0.500% of Compound (A-2) 0.030% of Compound (B-1) 0.666% of Compound (A-1) 33/1 0.333% of Compound (A-2) 0.030% of Compound (B-1) 0.750% of Compound (A-1) 33/1 0.250% of Compound (A-2) 0.030% of Compound (B-1) 0.500% of Compound (A-2) 33/1 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.050% of Compound (D-1) 0.275% of Compound (A-1) 37/1 0.275% of Compound (A-2) 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.367% of Compound (A-1) 37/1 0.183% of Compound (A-2) 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.413% of Compound (A-1) 37/1 0.137% of Compound (A-2) 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.350% of Compound (A-2) 23/1 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.050% of Compound (D-1) 0.150% of Compound (D-2) 0.350% of Compound (A-4-1) 23/1 0.015% of Compound (B-1) 0.049% of Compound (C-1) 0.050% of Compound (D-1) 0.150% of Compound (D-2) % means % by weight, relative to the weight of LDPE.