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Polymer substrate is commercially available polyolefin blend POLYTROPEfi TPP 518-01 supplied by A Schulman Inc. Akron, Ohio) 

Color package is 0.025% Red 3B -Pigment Red 177, C.I. #65300. 

Each plaque contains: 

0.2% TINUVINfi 328; 

0.1 % calcium stearate; and 

15% talc. 

The Control plaques additionally contain 

0.1 % IRGANOXfi B225 (50:50 blend of IRGANOXfi 1010, Ciba (neopentanetetrayl tetrakis(4-hydroxy-3,5-di› tert-butylhydrocinnamate) and IRGAFOSfi 168, Ciba [tris› (2,4-di-tert-butylphenyl) phosphite; 

0.2% TINUVINfi 770, Ciba [bis(2,2,6,6- tetramethylpiperidin-4-yl) sebacate ]; 

0.2% CHIMASSORB 944, Ciba [polycondensation prod› uct of 4,4’-hexamethylene-bis(amino-2,2,6,6- tetramethylpiperidine) and 2,4-dichloro-6-tert-octylamino› s-triazine]. 

The two test plaques (NOR-1 and NOR-2) each contain 0.05% N,N,-dialkylhydroxylamine; 

NOR-1 additionally contains 

0.2% of CHIMASSORBfi 119; and 

0.2% of TINUVINfi 123, Ciba, [bis(l-octyloxy-2,2,6,6- tetramethylpiperidin-4-yl) sebacate]. 

NOR-2 additionally contains 

0.2% of CHIMASSORBfi 119; and 

0.2% of the compound of Example 73. 

The results of the UV testing are given in the table below. 

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The compound of Example 73 present in test plaques NOR-2 specifically shows greatly improved gloss retention compared to the less effective control system and in fact is also more effective that a related hindered amine compound (TINUVINfi 123) present in test plaques NOR-1. Resis› tance to color change upon UV exposure is also enhanced. 

Polymer blends containing an unsaturated ternary component, such as EPDM blends, are especially benefited with the more efficient instant light stabilizer systems described above. 

In all cases, the light stabilized formulations show much greated resistance to photodegradation than unstabilized specimens which fail quickly under the UV exposure con› ditions outlined above. 

Molded test specimens are prepared by injection molding thermoplastic olefin (TPO) pellets containing the instant compounds, pigments and other coadditives as described in Example 76. 

The light stable formulations are painted with one-pack paint systems and tested for TPO/paint interactions. Before painting, the test specimens are first washed in accordance with GM998-4801 and dried for 15 minutes at 200° F. (94° 

## EXAMPLE 77 

Paintable TPO 

C.). Adhesion promoter is applied to the dry film thickness of 0.2-0.4 mils. The samples are dried for five minutes before a 1 K basecoat is applied to a film thickness of 1.2-1.4 mils. The painted panels are dried for three minutes, a clearcoat is then applied to a dry film thickness of 1.2-1.5 mils followed by ten minutes flash drying and a 30 minute oven bake at 250° F. (121 ° C.). 

Paint adhesion is measured by Aggressive Adhesion Test› ing (proprietary test procedure conducted at Technical Finishing, Inc.) and Taber Scuff. Painted panels which retain greater than 80% of the paint finish are considered accept› able. After Aggressive Adhesion Testing, samples with less than 5% paint loss are deemed acceptable. 

Samples are tested to evaluate the TPO/paint interactions as follows: 

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Formulation A contains 0.2% CHIMASSORBfi 944, 0.2% TINUVINfi 328, 500 ppm calcium stearate and 750 ppm N,N-dialkylhydroxylamine in reactor-grade TPO. 

A also contains 0.2% of bis(2,2,6,6-tetramethylpiperidin-4- yl) sebacate (TINUVINfi 770, pKa of 9.1). 

Formulations B and C contain 0.2% CHIMASSORBfi 119, 0.2% TINUVINfi 328, 500 ppm calcium stearate and 750 ppm N,N-dialkylhydroxylamine in reactor-grade TPO. 

B also contains 0.2% of bis(l-octyloxy-2,2,6,6- tetramethylpiperidin-4-yl) sebacate (TINUVINfi 123, pKa of 4.6). 

C also contains 0.2% of 1-(2-hydroxy-2-methylpropoxy)-4- octadecanoy loxy-2,2,6,6-tetramethy lpiperidine ( compound of Example 73, pKa of 4.0) 

The data in the table indicate that, although formulation A failed in both the Taber Scuff and Aggressive Adhesion Tests, both formulations B and C passed both paint adhesion tests. However, as inspection of the pKa values attests, the lower the pKa value (less basic) for the test hindered amine compound the less paint loss results in this Aggressive Adhesion Test. The instant compound of Example 73 having the hydroxyl moiety present has the lowest pKa value and also the least paint loss even better than the close prior art compound where no hydroxyl moiety is present. 

Stabilization of Polypropylene Molded Articles 

Molded test specimens are prepared by injection molding polypropylene pellets containing pigments, a phosphite, a phenolic antioxidant or hydroxylamine, a metal stearate, ultraviolet light absorbers or a hindered amine stabilizers or a mixture of UV absorbers and hindered amine stabilizers. 

Pigmented polypropylene pellets are prepared from pure pigment or pigment concentrates, stabilizers, co-additives and commercially available polypropylene by mixing the components in a Superior/MPM 1" single screw extruder with a general all-purpose screw (24:1 LID) at 475° F. (250° C.), cooled in a water bath and pelletized. The resulting pellets are molded into 60 mil (0.06 inch thick) 2"x2" plaques at about 475° F. (250° C.) on a BOY 30M Injection Molding Machine. 

## EXAMPLE 78 

