LIGHT STABILIZER MIXTURE

Abstract

A stabilizer mixture comprising a sterically hindered amine light stabilizer, a triazine UV absorber and a benzophenone UV absorber.

Claims

1. A stabilizer mixture comprising the components (a), (b) and (c), wherein component (a) is at least one compound of the formula (A), ##STR00020## 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), radicals 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 the formula (a-1), ##STR00021## and a is a number from 1 to 20 and the repeating units are identical or different; component (b) is at least one compound selected from the formulae (B-I) and (B-II), ##STR00022## wherein 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; n is 1 or 2, when n is 1, E.sub.1 is C.sub.1-C.sub.18alkyl, or C.sub.2-C.sub.18hydroxyalkyl which is interrupted by oxygen, and when n is 2, E.sub.1 is a bridging group of formula
—CH.sub.2CH.sub.2—O—C(O)—(CH.sub.2).sub.10—C(O)—O—CH.sub.2CH.sub.2—, ##STR00023## wherein Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are independently of one another hydrogen, C.sub.1-C.sub.18alkyl, C.sub.1-C.sub.18alkyl substituted by hydroxy, C.sub.2-C.sub.18alkyl or C.sub.2-C.sub.18hydroxyalkyl interrupted by oxygen, and T.sub.1, T.sub.2 and T.sub.3 are independently from each other hydrogen or C.sub.1-C.sub.18alkyl; component (c) is a compound of formula (C) ##STR00024## and wherein the weight ratio of component (b) to (c) is 1:50 to 50:1.

2. The stabilizer mixture according to claim 1, wherein A.sub.1 is C.sub.2-C.sub.8alkylene or cyclohexylene, radicals 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 the formula (a-1), and a is a number from 1 to 10.

3. The stabilizer mixture according to claim 1, wherein E.sub.2, E.sub.3, E.sub.4 and E.sub.5 are independently from each other hydrogen, C.sub.1-C.sub.4alkyl or phenyl, Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are independently from each other hydrogen or C.sub.1-C.sub.10alkyl, and T.sub.1, T.sub.2 and T.sub.3 are independently from each other hydrogen or C.sub.1-C.sub.4alkyl.

4. The stabilizer mixture according to claim 1, wherein component (a) is at least one compound selected from the formulae (A-0), (A-1), (A-2), (A-3), and or (A-4), ##STR00025## wherein 1 or 2 of radicals A.sub.2 are hydrogen and the remaining radicals A.sub.2 are propyloxy, ##STR00026## wherein a is a number from 1 to 20; ##STR00027## wherein a is a number from 1 to 20.

5. The stabilizer mixture according to claim 1, wherein component (b) is at least one compound selected from the formulae (B-1), (B-2) and/or (B-3) ##STR00028##

6. The stabilizer mixture according to claim 1, further comprising component (d) which is at least one compound selected from the formulae (D-1) and/or (D-2) ##STR00029## 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 agrochemical compounds and (II) a stabilizer mixture as defined in claim 1.

8. The composition according to 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, and mixtures thereof.

9. The composition according to claim 7, further comprising an additive selected from the group consisting of antioxidants, slip agents, anti-block agents, thermal fillers, pigments, anti-fog and anti-mist agents.

10. An article made of a composition according to claim 7.

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

12. The article according to claim 10, which is a multilayer film.

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

14. The article according to claim 13, wherein the greenhouse film cover is in contact with an agrochemical compound.

15. A method for stabilizing an organic material against degradation induced by light, heat, oxidation or the effect of agrochemical compounds, which comprises incorporating into the organic material a stabilizer mixture as defined in claim 1.

16. The article according to claim 12, wherein the multilayer film is a polyolefin film.

17. The article according to claim 16, wherein the polyolefin film comprises a compound of the formula (A) in at least one layer and a compound of the formula (B-I) or (B-II) in another layer.

Description

EXAMPLES

[0191] Stabilizers Listed in Tables 1 to 4 Below:

##STR00016##

[0192] wherein a is a number from 1 to 10.

##STR00017##

[0193] wherein a is a number from 1 to 10.

##STR00018## ##STR00019##

[0194] wherein b is a number from 2 to 10.

Application Examples 1 to 7

[0195] A) Preparation of Film Samples:

[0196] 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 and 2 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 having the same formulation in all layers. The overall thickness of the film was 160 μm (50 μm-15 μm-30 μm-15 μm-50 μm).

[0197] B) Test Method

[0198] 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.

[0199] 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.

[0200] The test results are listed in Tables 1 and 2.

TABLE-US-00001 TABLE 1 Film samples contaminated up to level of sulfur of 5000 ppm and exposed in a WOM. Stabilizer mixture Retained elongation at (weight-% based on break (as % of initial) after polymer composition) 4000 hours WOM treatment Example 1 0.550% of Compound 6.4 (Comparative) (A-4-1) 0.064% of Compound (C) Example 2 0.550% of Compound 77.1 (A-4-1) 0.015% of Compound (B-1) 0.049% of Compound (C) Example 3 0.550% of Compound 78.9 (A-4-1) 0.015% of Compound (B-2) 0.049% of Compound (C) Example 4 0.550% of Compound 69.4 (A-4-1) 0.015% of Compound (B-3) 0.049% of Compound (C)

[0201] High values are desired.

TABLE-US-00002 TABLE 2 Film samples contaminated up to level of sulfur of 5000 ppm and exposed in a WOM. Stabilizer mixture Retained elongation at (weight-% based on break (as % of initial) after polymer composition) 4000 hours WOM treatment Example 5 0.350% of Compound 61.8 (Comparative) (A-4-1) 0.050% of Compound (D-1) 0.150% of Compound (D-2) 0.064% of Compound (C) Example 6 0.350% of Compound 88.2 (A-4-1) 0.050% of Compound (D-1) 0.150% of Compound (D-2) 0.049% of Compound (C) 0.015 of Compound (B-1) Example 7 0.350% of Compound 79.7 (A-4-1) 0.050% of Compound (D-1) 0.150% of Compound (D-2) 0.049% of Compound (C) 0.015 of Compound (B-3)

[0202] High values are desired.

Application Examples 8 to 11

[0203] A) Preparation of Film Samples:

[0204] Preparation of stabilized LDPE (low density polyethylene)/LLDPE (linear low density polyethylene)/EVA (ethylene-vinyl acetate copolymer) multi-layer film samples:

[0205] Concentrated formulations containing in total 20% of the stabilizer mixtures indicated in Tables 3 and 4 below, LDPE powder (Polimeri Europa Riblene® FC 30, characterized by a density of 0.922 g/cm3 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 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 double-screw Comac extruder (Ø 34 mm, L/D=32). Then, the concentrates are blown in an industrial-scale 3-layer blow-extruder (Ø 20-25-30 mm, L/D 25), at a maximum temperature of 210° C. to the final formulations indicated in Tables 3 and 4, by dosing the appropriate amounts of each concentrated formulation and a mixture of the following polymers: 66% of Polimeri Europa Riblene® FF30, 19% of Exxon Enable® 2005HH and 15% of Polimeri Europa Greenflex® FC45. The produced 3-layer films have the same composition of the polymer mixtures in all layers and, as a result, of the stabilization composition. The overall thickness of the films is 150 μm (45 μm-60 μm-45 μm) for Test method B1 and 200 μm (60 μm-80 μm-60 μm) for Test method B2.

[0206] B1) Test Method

[0207] Specimens of the films for each formulation are placed on the roof of an experimental greenhouse (geographical coordinates: Lat. 44° 25′40″N Long. 11° 16′39″E) facing the South and wherein spraying with agrochemicals can be carried out, mounted on frames made in such a way that the specimen is in direct contact with a metal (galvanized iron) bar, simulating the contact with metallic supports in a real greenhouse. Treatments with Fumathane 510, a sulfur-based broad-spectrum fumigant, and with Pertrin S, a chlorine-based insecticide, are performed, respectively twice per year and monthly.

[0208] Specimens of the film samples in contact with the metal are taken at defined intervals of time after exposure and undergo 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.

[0209] The test results are listed in Table 3.

TABLE-US-00003 TABLE 3 Film samples exposed outdoor and contaminated up to level of sulfur of 3000 ppm Retained elongation Stabilizer mixture at break on galvanized (weight-% based on iron after specified solar polymer composition) irradiation Example 8 0.30% of Compound Not measurable, because (Comparative) (A-3-1) brittle after 10.8 GJ/m.sup.2 0.30% of Compound (A-4-1) 0.05% of Compound (B-1) Example 9 0.30% of Compound 100% after 16 GJ/m.sup.2 (A-3-1) 0.30% of Compound (A-4-1) 0.02% of Compound (B-1) 0.30% of Compound (C)

[0210] High elongation value after more irradiation is desired

[0211] B2) Test Method

[0212] Specimens of the films for each formulation are placed on the roof of a small experimental greenhouse (geographical coordinates: Lat. 44° 25′40″N Long. 11° 16′39″E) facing the South and inside of which a burner of the type used in common agricultural practice is placed, to allow sublimation of elemental sulfur, a widely used fungicide. The burner is operated every day of the exposure for three hours overnight.

[0213] Specimens of the film samples are taken at defined intervals of time after exposure and undergo 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.

[0214] The test results are listed in Table 4.

TABLE-US-00004 TABLE 4 Film samples exposed outdoor and contaminated up to level of sulfur of 15000 ppm. Stabilizer mixture Solar irradiation to (weight-% based on 30% of the initial polymer composition) elongation at break Example 10 1.20% of Compound 9.2 GJ/m.sup.2 (Comparative) (A-4-1) 0.15% of Compound (B-1) Example 11 1.20% of Compound 9.4 GJ/m.sup.2 (A-4-1) 0.05% of Compound (B-1) 0.30% of Compound (C)

[0215] High solar irradiation value is desired