CS255385B1 - A method of protection against yellowing of stabilized polyolefins - Google Patents

Abstract

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

Description

I 3 4 255335

The present invention provides a process for the protection against yellowing of stabilized polyolefins, the most propylene-propylene-containing flame retardants, in particular ultraviolet-based benzophenone and its derivatives, reacting with antioxidants and other auxiliaries by reacting with additives or additives. with the components of the stabilization system to colorless or white complexes.

Polyolefins, such as polyethylene, polypropylene, polybutenes, are characterized by a relatively low thermo-oxidative and photooxidic stability. Particularly demanding requirements are the stability of isotactic polypropylene. However, unlike polyethylene, it has an even lower stability due to its structure. In order to normally use the products made from it, it is necessary to stabilize it prior to processing, most often as soon as it is produced or even after production. How additives are used! teroxoxidation stabilizers - most notably substituted alkylphenols, polymer-protecting compounds. ultraviolet (UV) radiation, process-improving substances, nucleating agents, and optionally other ingredients. The role of UV stabilizers lies either in raising excited states of light-absorbing groups or in absorbing energy quantum and their dispersion of the polymer by a mechanism that does not aid degradation, or a reaction with the resulting radicals. Although the use of thienenamines as UV stabilizers (HALS-γ) has increased considerably in the past, 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. It is believed that their function as UV absorbers consists in converting the light quanta into the vibration energy of the hydrogen bond (Havkins V. L .: Polymer Degradation and Stability, Springer Verlag, Beri, 1984, p. 79). One of the most widely used compounds of this type is 2-hydroxy-, 4-octoxybenzophenone, known under the trade name Cyasorb UV-531 (Cyanamide Corp., USA). It serves both as a nucleating agent as deactivator of acid residues of the catalytic system (Haney MA, DarkW., J. Chromatogr. Sci 18, [1980], 655) & also as processing aid (Allen NS) Chirinos-Padron AJAppleyard JH, Heninan IJ: Polym De-grad Stab 5 [1983], 105), the impregnant of active fillers and the like may be added.

It is also known (Yasuda H., Yamada Y .: Ut-sunomiya Daigaku Kyoikugakubu Kiyo 35, [(1984), 27) that compounds of 2-hydroxybenzo-phenone (BOF) form transition moieties with divalent cations of metals (M) color complexes of type M2 + [BOF_) 2. In the case of Cyasorbu UV-531 and lime salts, chloroform-soluble intense complex is formed in the polymer melt. When such a complex is formed in situ in the molten polypropylene reaction between Cyasorb UV-531 and polypropylene stearate by reaction between Ca-sorbine UV-531 and calcium stearate, the latter after cooling the melt-extruded crystals (Ryan TG, Calvert PD: Po-lymer) 23, [1982J, 877], and in the amorphous partipolymer it substantially increases its concentration. This is manifested by the vivid coloring of the poly-propylene granulate, or the products made therefrom, e.g. Currently, with the use of said stabilizing system for polyolefins, especially polypropylene, there are considerable technical problems, especially in the manufacture of colorless, transparent and white products. It is solved either by the addition of white pigments, by the reduction of the additive concentration of the polyolefins and the like.

However, the aforementioned technical problem is a method of protecting stabilized polyolefins, especially polypropylene against melt-treated yellowing, wherein the polyolefin contains, as stabilizers, radiation absorbers, in particular ultraviolet radiation, based on benzophenone and its derivatives, and optionally other auxiliaries by adding at least one aromatic / or aliphatic monocarboxylic acid to C20 to C20 and / or dicarboxylic acid to C10 to C10 and / or dicarboxylic acid to any one stage of the manufacturing or processing process prior to melt processing in the polyoxyphine; preferably adipic acid, benzoic acid, in an amount of 10. 10 to 3 to 0.5% by weight, calculated on the polyolefin. The advantage of the method of protection against yellow-stabilized polyolefins according to the invention is the high decolorizing efficiency of the additive, its technical availability and its health safety. Furthermore, the technical simplicity of the method, the possibility of using and further extending to the new applications already proven stabilization systems and the recipes based thereon of polyolefin, additive and excipient formulations.

The method of protection against yellowing of the polyolefins according to the invention also relates to copolymers of olefins, including homopolymer copolymers of styrene, especially those used as stabilizers on the basis of benzophenone-based stabilizers and derivatives thereof. Suitable antioxidants are, on the one hand, phenolic compounds such as 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenoyl, 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, 5 255385 2,2-methylene-bis (4-methyl-6-tert-butyl-phenyl), 2,2'-methylene-bis (4,6-di-tert-butyl-phenol), 4,4'-butyl .beta.-bis (2,6-di-tert-butylphenol), 1,1,3-tris (2'-methyl-4'-hydroxy-5'-tert-butylphenyl) buffane, tetrakis [methylene-3] (3 ', 5'-di-tert-butyl) -4'-hydroxyphenylpropionate)] methane, bis [3,3'-bis- (3'-tert-butyl-4'-hydroxy-phenyl) 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-butyl phenol), 4,4'-thiobis (2-methyl-, 6-tert-butylphenol), N, N'-diphenyl-p-phenylenediamine, thiodipropionic acid dilauryl ester, octadecylsulfide, pentaerythritoletrakis (3-dodecylt i-dipropionate), triphenylphosphite, tri (4-nonylphosphite, tris [2,4- (1-phenylatyl) phenyl] phosphite, tris- (2,4-di-tert-butylphenyl) phenyl). bisphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol D-diphosphite, trilauryltrithiophosphite, tetrakis (2,4 di-tert-butylphenyl) -4,4‘-biphenylidene diphosphite and others.

As UV stabilizers, respectively. the radiation absorbers are substituted benzotriazoles, mainly 2-hydroxyphenylbenzotriazoles, salicylates such as phenylsalicylate, 4-octylphenylsalicylate, 4-tert-butylphenyl salicylate; 2-hydroxybenzophenones and benzolone derivatives such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2-dihydroxy-4-inethoxybenzophenone, 2,2 ' 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzofeuon, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2,2-hydroxy-5-chlorobenzophenone, 2,2 ' -dihydroxy-4-octyloxybenzophenone, 2-hydroxy-4- (Γ-ethylhexyloxy) benzophenone, 2-hydroxy-4- (2'-hydroxy-3'-acryloxypropoxy) benzophenone, nickel chelates and complexes such as 2,2 nickel nickel thiobis [4-tert-octylphenolate] -2-ethylhexylamine, nickel dibutyldithiocarbamate, [2,2'-thiobis (4-tert-octylphenolate)] n-triethylamine nickel, [2,2-thiobis (4 tert-octylphenate]] - nickel cyclohexyldiethylamine, nickel salt of (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) phosphoric acid monoethyl ester, 2,2-thiobis 4-tert-octylphenate) ethylhexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3- diphenyl acrylate, 2,2‘-thiobis (4-tert-octylphenolate) nickel, n-butylamine-2,2‘-thiobis (4-tert-octyl phenolate) and the like; spatially shielded amines, substituted o-xanilides, and the like.

Excipients are known antioxidants, glidants, flame retardants, pigments, anti-lock agents, fillers, anti-statics, blowing agents, modifiers. dyes, especially surface dyes, dyes, optical brighteners, metal deactivators, and the like.

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

Suitable aliphatic monocarboxylic acids for carrying out the process of the present invention are monocarboxylic acids C 5 to C 20, but in particular Ca to C 18, further the dicarboxylic acids C 8 to C 12, but the acids are: glutaric, succinic, adipose, sebacic. However, care should be taken not to contain crystalline or dissolved water, or other low boiling components. As a rule, from 0.01 to 0.1% by weight of polyolefin is sufficient in terms of the amount of said carboxylic acids, provided that the usual amounts of the other additive additives are used. The carboxylic acid additives of the present invention may be added to the polyolefin or polyolefins while they are produced after leaving the polymerization or copolymerization reactor, most preferably still by pre-granulating the polymer. However, carboxylic acid additives can be added to the polymers in any further stage of their manufacture, handling, including storage, or simultaneously with the addition of other ingredients prior to processing or during processing. polymers. In fact, the composition of the present invention avoids yellowing or eliminates yellowing mainly due to the polymer stabilization system. Further details of the method of the invention as well as other advantages are apparent from the examples. 1 and 1

When evaluating the color changes occurring in the melt of polypropylene (PP), the C 2 H 12 (eicosan) hydrocarbon is used as the mode compound. To highlight the color intensity, a 50 fold higher concentration of additives is used than is commonly used in PP. 2 geicosan, 0.2 g of 2-hydroxy-4-n-octoxybenzenenone [Cyasorbu UV-531 [CUVj] and 0.1 g of calcium stearate (CaST) were weighed into the tube. The mixture was heated in an oil bath at 20 to 200 ° C. At 150 ° C, when the melting point of CaSt is already reached, an intensely precipitated precipitate is formed which dissolves by further heating. Cooling below 40 ° C mixture

Claims (1)

7 8 255383 solidifies, and its lived color is several times more intense than when CaSt is not used (Gya-sorb UV-531 powder itself is slightly yellowish). 0.02 g of benzoic acid is added to the yellowish mixture of CUV and CaSt in eicosane. The mixture becomes colorless and, after cooling below 40 ° C, is still used, as is the case with Cyasor UV-531 in eicosane. Examples 2 to 5 The procedure is similar to that of Example 1, except that other acids are used in place of benzoic acid in an amount of 0.02 to 0.05 g, shown in Table 1. In all cases, the product is less live than the Cya-sorb mixture. UV-531 in eicosan. T δ bu 1 'ka 1 Use of different organic acids Example Acid type amount Decolorizing effect 2 valeric acid 0.02 complete 3 capric acid 0.02 complete 4 lauric acid 0.05 partial (approximate half 5 adipic acid 0.02 complete Example 0 A calcium complex (Cyasor-bu UV-531] - 2-hydroxy-4-n-octoxybenzophenone) is prepared by reacting calcium chloride with CUV in a sodium ethoxide solution to give an intensely powdered powder and adding 0.2 g of the complex in 2 g of chloroform. Example 7 A mixture of unstabilized propylene powder is mixed with 0.2% by weight of Cya-sorb UV-531, 0.1% by weight of 2.6 di-tert-butyl acid. 0.1% by weight of calcium stearate, 0.1% of di-stearyl thiodipropionate and 0.05% by weight of benzoic acid, and the mixture is reshaped in plastic at 200 ° C. ° C for 5 min ozdie, when polypropylene granules containing otherwise equal amounts of additives but without benzoic acid are used. EXAMPLE 8 Proceed as described in Example 7, only 0.05 wt%. benzoic acid is added to 0.01 wt. benzoic acid and 0.1 wt. stearic acid, thus obtaining a colorless extrudate. EXAMPLE 9 The procedure is similar to that described in Example 7, instead of 0.05% by weight. benzoic acid is added to 0.3 wt. tetradeeylsalicylic acid, thus obtaining a colorless exudate. EXAMPLE 1 Proceed as described in Example 1, only 0.05% by weight. benzoic acid is added with 0.1% azelaic acidHOOC [CH 2] 1 COOH, thus also obtaining a colorless extrudate. OBJECTIVE A method of protecting stabilized polyolefins, in particular melt-treated polypropylene, with the polyolefin containing, as stabilizers, radiation absorbers, in particular ultraviolet radiation, based on benzophenone and its derivatives, and antioxidants and optionally containing additional excipients, as indicated by that at least one aromatic and / or aliphatic monocarboxylic acid C 5 to C 20 and / or dicarboxylic acid C 1 to C 10, preferably acidic adipic acid, is added to the polyolefin in any stage of the invention of the manufacturing or processing process prior to melt processing. , benzoic acid, 10 -10 to 3 to 0.5 wt.%, calculated on polyolefin. Sevarojzrafia np zňvort 7, Most Price 2.40 Eurs