CS255385B1 - Method of stabilized polyolefins' yellowing prevention - Google Patents

Abstract

Protection against yellowing stabilized polyolefins, especially polypropylene, containing radiation absorbers, especially ultraviolet based on benzophenone and its derivatives, further antioxidants and optionally excipients so that the polyolefin is disposable and at least one aromatic is added in portions or an aliphatic carboxylic acid (benzoic acid, 2-ethylhexanoic acid, adipic acid, glutaric acid) in an amount of 1: 10 3 to 0.5 wt. The method is suitable for use in production i in the processing of polymers, especially polypropylene. for plastic and fiber products.

Description

(54) Means of protection against yellowing of stabilized polyolefins

Protection against yellowing of stabilized polyolefins, in particular polypropylene, containing radiation absorbers, in particular ultraviolet based on benzophenone and its derivatives, antioxidants and, where appropriate, auxiliaries, by adding at least one aromatic or aliphatic carboxylic acid (benzoic acid) to the polyolefin. 2-ethylhexanoic acid, adipic acid, glutaric acid) in an amount of 1: 10 ³ to 0.5 wt. The method is suitable for use in production and processing of polymers, especially polypropylene. for plastic and fiber products.

I

The invention relates to a method of protecting against yellowing of stabilized polyolefins, in particular polypropylene, containing radiation absorbers, in particular ultraviolet based benzophenone and its derivatives, furthermore antioxidants and other auxiliaries, additivation with an additive or additives reacting with coloring or white stabilizing system components.

Polyolefins such as polyethylene, polypropylene, polybutenes are characterized by relatively low thermooxidative and photooxidic stability. Particularly demanding requirements are the stability of the isotactic polypropylene. Moreover, unlike polyethylene, it has an even lower stability due to its structure. In order to be able to routinely use products made from it, it is necessary to stabilize it before processing, but most often immediately after production or even during production. Thermo-oxidizing stabilizers - especially substituted alkylphenols, polymer-protecting compounds, are used as additives. exposure to ultraviolet (UV) radiation, processability enhancers, nucleating agents, and possibly other ingredients.

The role of UV stabilizers is either to quench excited states of light-absorbing groups or to absorb energy quanta and scatter it into the polymer by a mechanism that does not aid degradation or reaction with the resulting radicals. Although the use of shielded amines as UV stabilizers (HALS-γ) has been widespread in recent years, many stabilization systems are still based on the effect of substituted o-hydroxybenzophenones. These compounds are known to form. a six membered ring containing a hydrogen bond. Their function as UV absorbers is believed to be the conversion of light quantum into the vibrational energy of the hydrogen bond (Havkins, V.L .: Polymer Degradation and Stability, Springer Verlag, Berlin, 1984, p. 79). One of the most commonly used compounds of this type is 2-hydroxy-, 4-n-octoxybenzoophenone, known under the tradename Cyasorb UV-531 (Cyanamide Corp., USA).

A frequently used additive to polypropylene is calcium stearate, which has several functions here. It serves both as a nucleating agent, as deactivator of acidic residues from the catalytic system (Haney MA, Dark WA: J. Chromatogr. Sci 18, [1980], 655) and also as a processing aid (Allen NS, Chirinos-Badron AJ Appleyard JH, Heninan IJ: Polym. Degrad. Stab. 5 [1983], 105), optionally impregnating active fillers and the like.

It is also known (Yasuda H., Yamada Y .: Utsunomiya Daigaku Kyoikugakubu Kiyo 35, [(1984), 27) that 2-hydroxybenzophenone-type (BOF) compounds form M ^2- type color complexes with divalent transition metal (M) cations ⁺ [BOF ^- ] 2. In the case of Cyasorb UV-531 and calcium salts, an intensively lived complex soluble in both chloroform and melt polymers is formed. When such a complex is formed in situ in molten polypropylene by reaction between Cyasorb UV-531 and polypropylene stearate by reaction between Cyasorb UV-531 and calcium stearate, this is extruded from the crystallites upon cooling of the melt (Ryan TG, Calvert PD: Polymer 23, [1982J, 877) and its concentration is substantially increased in the amorphous portion of the polymer. This is manifested by the luster coloring of the polypropylene granulate or the products made therefrom, e.g. v ákien.

At present, the use of said stabilizing system for polyolefins, in particular polypropylene, presents considerable technical problems, particularly in the manufacture of colorless, transparent and white products based thereon. It is solved either by adding white pigments, reducing the concentration of additives and thus the stability of polyolefins etc.

However, this technical problem solves the method of protecting stabilized polyolefins, in particular polypropylene against melt-yellowing, wherein the polyolefin contains radiation absorbers, in particular ultraviolet radiation, based on benzophenone and its derivatives, further antioxidants and optionally other auxiliaries as stabilizers. at least one aromatic and / or aliphatic monocarboxylic acid C 6 to C 20 and / or dicarboxylic acid C 4 to C 10, preferably adipic acid, benzoic acid, is added in one portion or in portions at any stage of the manufacturing or processing process prior to melt processing 10. 10 to ³ % by weight, calculated on the polyolefin.

The advantage of the method of protection against yellowing of the stabilized polyolefins according to the invention is the high decolorizing efficiency of the additives, their technical availability and their health safety. Furthermore, the technical simplicity of the method, the possibility to use and further extend to new applications already proven stabilization systems and based on them formulations of polyolefin formulations, additives and excipients.

The polyolefin yellowing protection method according to the present invention also relates to olefin copolymers, including homopolymers and copolymers of styrene, especially those in which stabilizers based on benzophenone and its derivatives are used as a stabilizing system. Suitable antioxidants are, on the one hand, phenolic-type compounds, such as

2,6-di-tert-butyl-4-methylphenol,

2.4.6- tri-tert-butylphenyl,

2-tert-butyl-4-cumylphenol, octadecyl-3- (3‘, 5‘-di-tert-butyl-4‘-hydroxyphenyl) propionate,

2,6-di-tert-butyl-4-sec-butylphenol,

2,2-bis- (4‘-hydroxyphenyl) propane,

2.2-Methylene-bis (4-methyl-6-tert-butylphenyl),

2,2‘-methylene-bis (4,6-di-tert-butyl phenol),

4,4'-motylene-bis (2,6-di-tert-butylphenol), 1,1,3-tris (2'-methyl-4'-hydroxy-5'-tert-butylphenyl) buffet, tetrakis [methylene] -3 (3 ', 5'-di-tert-butyl) -4'-hydroxyphenyl propionate)] methane, bis [3,3'-bis- (3'-tert-butyl-4'-hydroxyphenyl)] butyl] succinate,

2,4-bis- (n-octylthio) -6- (3 ‘, 5‘-di-tert-butyl-4‘-hydroxyanilino) -1,3,5-triazine,

4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-, 6-tert-butylphenol), N, N'-diphenyl-p-phenylenediamine, thiodipropionic dilauryl ester, octadecylsulfide, pentaerythritol tetrakis (3-dodecylthiodipropionate), triphenylphosphite, tri (4-nonylphosphite), tris [2,4- (1'-phenylatyl) phenyl] phosphite, tris- (2,4-di-tert-butyl) butylphenyl) phosphite, bis (2,4-di-tert-butylphenyl) pentaerythroldol diphosphite, trilauryltrithiophosphite, tetrakis (2,4 di-tert-butylphenyl) -4,4'-biphenylidene diphosphite and others.

As UV stabilizers, resp. radiation absorbers include substituted benzotriazoles, especially 2-hydroxyphenylbenzotriazoles, salicylates such as phenyl salicylate,

4-octylphenyl salicylate,

4-tert-butylphenyl;

2-hydroxybenzophenones and benzolenone derivatives such as

2.4- dihydroxybenzophenone,

2-hydroxy-4-methoxybenzophenone,

2,2'-dihydroxy-4,4'-dimethoxybenzophenone,

2,2-dihydroxy-4-methoxybenzophenone, 2,2 ‘, 4,4‘-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-4‘-methylbenzopheuone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone,

2.2-hydroxy-5-chlorobenzophenone,

2,2'-dihydroxy-4-octyloxybenzoferone, 2-hydroxy-4- (1'-ethylhexyloxy) benzolenone, 2-hydroxy-4- (2'-hydroxy-3'-acryloxypropoxy) benzophenone; nickel chelates and complexes; as 2,2'-thiobis (4-tert.octylphenolate) -2-ethylhexylamine, nickel, dibutyldithiocarbamate, nickel, [2,2'-thiobis (4-tert.octylphenolate), n-triethylamine, nickel, [2,2-thiobisphenol] (tert-octylphenolate)] cyclohexyldiethylamine nickel, nickel salt of (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) phosphoric acid monoethyl ester,

Nickel (2,2-thiobis (4-t-octylphenolate)), 1-ethylhexyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3,3-diphenyl acrylate,

Nickel (II) 2,2‘-thiobis (4-tertioctylphenolate), nickel-n-butylamine-2,2‘-thiobis (4-tertioctylphenolate), etc .;

spatially shielded amines, substituted oxanilides, and the like.

Adjuvants are known antioxidants, glidants, flame retardants, pigments, anti-blocking agents, fillers, antistatic agents, blowing agents, modifiers. dyes, in particular surface dyes, dyes, optical brighteners, metal deactivators and the like.

Suitable aromatic carboxylic acids are benzoic acid, p-hydroxybenzoic acid, naphthalenecarboxylic acids and the like.

Suitable aliphatic monocarboxylic acids for carrying out the process according to the invention are the monocarboxylic acids Cs to C20, in particular Cs to Cts, furthermore the dicarboxylic acids Ca to C12, in particular: glutaric, succinic, adipic, sebacic acids. However, be careful not to contain crystalline or dissolved water, or other low-boiling components.

Generally, from 0.01 to 0.1% by weight is sufficient for the amount of said carboxy-left acid. the polyolefin provided using ^common: YCH amounts of other additives to polymers.

The carboxylic acid additives of the present invention may be added to the polyolefin or polyolefins during their manufacture after leaving the polymerization or copolymerization reactor, most preferably before the polymer granulation. However, the carboxylic acid additives can be added to the polymers at any other stage of their manufacture, naniptilation with them, including storage. Furthermore, separately or simultaneously with the addition of other additives before or during processing of the polymers. Indeed, the method according to the invention prevents yellowing or removes yellowing caused mainly by the polymer stabilization system.

Further details, method of the invention as well as other advantages are apparent from the examples.

i 'r 1 and t 1

For the color changes occurring in the melt of polypropylene (PP), the C20H12 hydrocarbon (eicosan) is used as the mode compound. A 50-fold higher additive concentration than is commonly used in PP is weighed in a test tube to weigh 2 g. eicosan, 0.2 g of 2-hydroxy-4-n-octoxybenzoophenone [Cyasorbu UV-531 (CUVjj) and 0.1 g calcium stearate (CaST) .The mixture is heated in an oil bath at a temperature of 20 to 200 ° C. 150 ° C, once the melting point of CaSt is reached, an intensely lived precipitate is formed, which dissolves by further heating.

255383 solidifies, with a lively color that is several times more intense than when CaSt is not used in the mixture (Cyasorb UV-531 powder itself is slightly yellowish). 0.02 g of benzoic acid is added to the yellow melt of a mixture of CUV and CaSt in eicosan. The mixture was discolored and, after cooling below 40 ° C, was even less lived than with Cyasorb UV-531 alone in eicosan.

Examples 2 to 5

The procedure is similar to Example 1 except that the other acids in the amount of 0.02 to 0.05 g shown in Table 1 are used instead of benzoic acid. In all cases the product is less lived than the mixture of Cyasorb UV-531 in eicosan.

Τ δ b u 1 'k and 1

Use of various organic acids

Example

Acid kind amount

Decolourizing effect

2 valeric acid 0.02 full 3 caproic acid 0.02 full 4 lauric acid 0.05 part time (approx 5 adipic acid 0.02 full

Example 0

A calcium complex (Cyasorbu UV-531) -2-hydroxy-4-n-octoxybenzophenone is prepared by reacting calcium chloride with CUV in sodium ethanolate solution. After drying, an intensely lived powder is obtained. To 0.2 g of the complex in 2 g of chloroform 0.5 grams of adipic acid to decolorize the rye rosette.

Example 7

Mix the unstabilized polypropylene powder with 0.2 wt. % Cyasorb UV-531, 0.1 wt. 2,6 di-tert-butyl-4-methylphenol as an antioxidant (AO 4K). 0.1 wt. calcium stearate, 0.1% distearyl thiodipropionate and 0.05 wt. benzoic acid. The mixture is remelted in a plastomer at 200 ° C for 5 min. A colorless extrudate is obtained, in contrast to the lived one, when using a polypropylene granulate containing otherwise equal amounts of additives but without benzoic acid.

Example B

Proceed as in Example 7, but instead of 0.05% w / w. % of benzoic acid is added 0.01 wt. % benzoic acid and 0.1 wt. stearic acid, whereby a colorless extrudate is also obtained.

Example 9

The procedure is similar to that of Example 7, but instead of 0.05 wt. % benzoic acid is added 0.3 wt. tetradecylsalicylic acid, whereby a colorless extrudate is also obtained.

? r i i d 1 fl

The procedure is as in Example 1, but instead of 0.05% w / w. of benzoic acid is added 0.1% azelaic acid HOOC (CH 2) 1 COOH to also produce a colorless extrudate.

Claims (1)

SUBJECT A method for protecting stabilized polyolefins, in particular polypropylene, from melt-yellowing, wherein the polyolefin comprises radiation stabilizers, in particular ultraviolet radiation, based on benzophenone and its derivatives, furthermore antioxidants and optionally further auxiliaries, characterized in that the polyolefin is present in the polyolefin. any stage OF THE INVENTION before or after melt processing, at least one aromatic and / or aliphatic monocarboxylic acid C 5 to C 20 and / or a dicarboxylic acid C 4 to C 10, preferably adipic acid, benzoic acid, is added in an amount of 10. . 10 ~ ³ to 0.5% by weight, calculated on the polyolefin.