CS225481B1 - Light stability agent based on sterically hindered amine and its preparation - Google Patents

Description

Light stabilizer of sterically hindered amine type and method of its preparation

BACKGROUND OF THE INVENTION The present invention relates to a sterically hindered amine light stabilizer, which is represented by: the compound 2,2,6,6-tetramethyl-4-piperidyl ester, respectively. 2-methyl-3- [5- (7,15-diazadispiro [5,1,5,3] hexadecyl) propanoic acid 1,2,2,6,6-pentamethyl-4-piperidyl ester and a process for their preparation.

Sterically hindered amines are a modern class of light stabilizers for plastics. It is known from the literature that stabilizers containing two active ingredients per molecule are more effective than stabilizers containing only one active ingredient. Similar compounds with one active ingredient are the subject of US Patent 3,992,351.

This disadvantage is substantially eliminated by the present invention, which is based on a sterically hindered amine light stabilizer, which is 2-methyl-3- [15,5] / 7,15-di azadispiroic acid 2,2,6,6-tetramethylpiperidine ester. ≫ 1,5, 3] hexadecyl / J propane of formula I

wherein R is a proton or methyl

The present invention further provides a process for the preparation of these compounds which is characterized in that, for methyl 2-methyl-3- [15 '- [7,15-diazadispiro 5,1,5,3-hexadecyl] -propanoic acid methyl ester (II).

of formula II

T \

CHI HN N-CH ₉ -CH-COOCH _q y ³

is reacted with the formula III

4-hydroxy-2,2,6,6-tetramethylpiperidine

OH (III?

wherein K is a proton or methyl in a higher boiling (110 at 160 ° C) hydrocarbon solvent in the presence of a re-esterification catalyst (lithium amide, tetrapropylorthotitanate and the like).

In particular, the compounds contain two active ingredients per molecule, thereby impurities increasing the icb activity in the stabilization process.

Example 1

Subsequent treatment of 1 mole of 2-methyl-3- (15- / 7,15-diaza dispiro [5,1,5,3] hexadecyl) propanoic acid methyl ester and 1.2 mole of 4-hydroxy-2,2,6, -tetramethylpiperidine in 150 ml of xylene was refluxed for 8 hours in the presence of lithium amide After cooling, the reaction mixture was washed with water and dried over magnesium sulphate. = 70-72 ° C) was obtained in a yield of 70%.

Analysis for

calculated

Found ^G 27 ^H 49 ^N 3 ^C 2 72.44% C 72.68% C Molecular weight 447.72

% H, 11.33;% N, 9.38

N, 11.60

Example 2

A solution of 1 mole of 2-methyl-3 '- {1,5- / 7,15-diazadispiro [5,1,5,33-hexadecyl] -propanoic acid methyl ester and 1,2 mole of 4-hydroxy-1,2,2,6,6-pentamethylpiperidine in 1500 ml of xylene was refluxed for 8 hours in the presence of tetrapropylortotitanate. The reaction mixture was washed with water, dried over magnesium sulfate, and the xylene was distilled off in a vacuum evaporator. The product as a pale yellow oil was obtained in 68% yield.

Analysis for

calculated

Found ^C 28 ^H 51 ^N 3 ° 2 Molecular Weight: 461.83

72.82% C 72.98% C

H, 11.15; H, 11.36

N 9.10% N 8.79%

Example 3

The polypropylene mixture with 0.1% antioxidant content (2,6-di-tert-butyl-4-methylphenol) 0.15% calcium stearate content and 0.2% stabilizer content stood in dichloromethane for 18 hours at room temperature. After distillation of the dichloromethane on a rotary evaporator, a powder was obtained, which was further homogenized in a plastograph mixing chamber for 5 minutes at 200 ° C. Films of a thickness of 0.18 mm at t. = 190 ° C and a pressing time of 30 seconds. A control film was prepared in the same manner, except that no stabilizer was added. The foils were irradiated with a 125 W mercury vapor lamp. Irradiation uniformity was achieved by rotating the samples around the radiation source. The increase in carbonyl groups as a function of the irradiation time is a measure of the degradation of the polymer by UV radiation. The growth of carbonyl groups was monitored by IR spectrophotometer. The film without light stabilizer achieved an increase in carbonyl groups AA _cq = 0.3 after 300 hours. The film containing the light stabilizer according to formula II has reached ΔA _cq = 0.3 after 600 hours.

In the case of the light stabilizer prepared in Example 1, a value of = 0.3 was achieved after 1600 hours, and in the case of the light stabilizer prepared in Example 2, an increase in carbonyl groups of Δ Α θ = 0.3 was achieved after 1,300 hours.

Said compounds can be used as light stabilizers in polymers, especially polyolefins.

Claims (2)

OBJECT OF THE INVENTION 1. Sterically hindered amine light stabilizer, represented by 2-methyl-3- {15- / 7,15-diazadispiro [5.1,5,3] hexadecyl]} propanoic acid 2,2,6,6-tetramethyl-4-piperidyl ester wherein R is a proton or methyl 2. A process for the preparation of the compounds of the formula I according to claim 1, characterized in that to the methyl ester of 2-methyl-3 {15- / 7,15-diazadispiro [5,1,5,3] hexadecyl]} propane of the formula II HN N-CH _? -CH-COOCH ₇ (II) is treated with 4-hydroxy-2,2,6,6-tetramethylpiperidine of formula III wherein P is a proton or methyl With hours in xylene at 150 ° C under the catalytic action of lithium amide or tetrapropyl ortho-titanate.