DE1229296B - Stabilized molding compounds made from polyolefins - Google Patents

Description

Stabilized molding compounds made from polyolefins, high polymer compounds are known to be very sensitive to oxygen, heat and exposure to light. this is particularly important for polyolefins, whether they are made using the high or low pressure process are made, the case. The influence of oxygen, heat and light does not lead only to a lowering of the molecular weight, but runs in parallel Embrittlement of the polymers, combined with a reduction in mechanical values. These relationships are particularly evident in the case of polyolefins, the tertiary ones Contain carbon atoms - such as polypropylene and polybutylene.

It is known to use color pigments for stabilization, such as. B. Soot, too use. You can also use substituted phenols, sulfur-containing phenols, substituted Use p-phenyldiamines and esters of thiodipropionic acid as stabilizers. Particularly the combination of substituted phenols with sulfur-containing organic compounds is effective Links. But all of these stabilizer combinations are either free oxy groups or contain reactive amino groups, tend to granulation or when accelerated aging to the fact that they with those resulting from the polymerization Catalyst residues form color complexes. Another disadvantage of all these additives, especially the injection-molded bodies produced with dilaurylthiodipropionic acid in the case of polypropylene is that the finished products have an unpleasant smell attached to them.

These findings led to the development of stabilizer systems, which contain neither free OH groups nor aliphatically bound sulfur.

Suitable stabilizers are the phosphite ester to that meet these synthesis conditions.

Here too, however, it can be seen that, for example, those from PCh and substituted phenols do not form suitable stabilizers, which is probably due to the spherical shape of the molecule, which is exuding favored from the indifferent polyolefins.

The invention is now based on the basic idea of stabilization of the polyolefins phosphite esters with the most elongated molecule possible.

The invention relates to stabilized molding compositions made from polyolefins and an ester of phosphorous acid, optionally mixed with thiodipropionic acid esters and / or benzotriazole derivatives, characterized in that the phosphite ester is a compound of the general formula where X - 5 S - or = C (CH3, Arl is an arylene radical which is mono- or disubstituted by alkyl or cycloalkyl groups with 3 to 17 carbon atoms and Ar2 is an aryl radical which is mono- to triple by alkyl or cycloalkyl groups with 3 is substituted up to 12 carbon atoms, wherein one of these groups can also be an alkoxy group.

These phosphite esters are products that are in an known way were obtained by reaction of PCh with phenols, which up to three times with alkyl groups or cycloalkyl groups with 3 to 12 carbon atoms sub are substituted (isosubstituents preferred), one of these groups being an alkoxy group can be, according to which this reaction product with aromatic dihydroxy compounds from the condensation of acetone with phenols, one or two times with alkyl or cycloalkyl groups with 3 to 12 carbon atoms are substituted (isosubstituents preferred), or aromatic dihydroxy compounds from the condensation of sulfur dichloride and phenols of the last-mentioned type is implemented.

A compound of this type is, for example, the product which is obtained by reacting PCI3 with 3-tert.-butyl-4-oxy-anisole and then reacting the product obtained in this way with 4,4-thio-bis- (6-tert.- butyl-m-cresol) contains: The reaction is generally carried out in such a way that 1 mole of PCl3 is reacted with 2 moles of the substituted phenol. This is followed, after the product of the first stage has been suitably purified by distillation, then the reaction with the aromatic dihydroxy compounds. The possibility of purifying the product after the first stage by distillation is an additional advantage over the aforementioned trieste generally a viscous mass. It can be used directly for stabilization.

The above-mentioned products show when added to polyolefins a high stabilizing effect with regard to oxygen, heat and exposure to light. These effects occur very clearly when the stabilizer is only added is low; for example, very good effects can be achieved by adding 0.1% of the phosphite ester.

The stabilizing effect can be further increased by adding other known stabilizers such as thiodipropionic acid esters (e.g. dilauryl or distearyl thiodipropionate) and / or benzotriazole derivatives, e.g. B. Products of the following general formula: The amounts of these additional stabilizers should likewise not exceed about 1 percent by weight, based on the mass to be stabilized.

Examples The tests were carried out on an isotactic polypropylene carried out, its reduced specific viscosity (orea) measured on a 0.1% solution in decahydronaphthalene at 135 "C, stabilized with 0.50 / 0 phenol-B-naphthylamine, 3.1 was. (To determine this value, the polypropylene was treated with O, 201o N-phenyl-ß-naphthylamine stabilized in order to avoid degradation during the determinations.) As a stabilizer Phosphite ester used was dissolved in petroleum ether and made into one with polypropylene Mixed concentrate; then the petroleum ether was removed to the dried one Product optionally stabilizers (see table) given, with polypropylene filled up to the right concentration and then mixed well. In the table the characteristic mixtures are listed. One served as the UV light source Osram Vitalux lamp GUR 53, which provided a spectrum similar to that of the sun.

At a distance of 50 cm, the irradiance has compared to the Sunlight a factor of 10. The test specimens were compression plates 10 cm in length, 1 cm in width and 1 mm in thickness and were used both for the irradiation tests and used for the tempering tests.

Embrittlement times on press plates made of polypropylene Temper value UV irradiation Stabilizer amounts 145 ° C before after tempering in days Brabender a) reaction product from the reaction product of PCl3 and 3-tert-butyl-4-oxy-anisole with 4,4-thio-bis- (6-tert-butyl-m-cresol) ......... 0.5 41 21 3.0 2.9 2.2 b) like a) ................................... 0.25 31 20 3.1 2, 8 2.3 c) like a) ................................... 0.25 # 40 22 3.0 2.8 2.1 + Dilauryl thiodipropionate ............... 0.1 d) like a) ................................... 0.1 # 35 18 3.0 2.7 2.1 + Dilauryl thiodipropionate ............... 0.5 e) like a) ................................... 0.5 # 45 22 3.0 2.9 2.4 + 3- (3'-octyl-4'-oxyphenyl) -4-methylbenz- # 45 22 3.0 2.9 2.4 triazole ................................ 0.2 COMPARATIVE EXAMPLES For comparison with the above results - in particular in example c) - the stabilizing effect of other stabilizer mixtures on polypropylene was investigated according to the same criteria, the following values being obtained: Temper value UV irradiation before after Stabilizer amounts to 145 ° C tempering in days Brabender 1. Di-monophenylphosphite-α², α6-bis- (3-tert-butyl- 5-methyl-2-hydroxyphenyl) mesitol * .......... 0.25 27 13 3.1 2.6 1.8 + Dilauryl thiodipropionate .............. 0.1 2. Triphenyl phosphite ** ...................... | 0.25 18 12 3.1 2.4 1.7 + Dilauryl thiodipropionate ........ 0.1 * According to French patent specification 1,324,451, p. 4, left column, lines 27 to 29, or sample no.729, table I.

** According to French patent specification 1 016, example 5.

Claims (1)

Claim: Stabilized molding compounds made from polyolefins and an ester of phosphorous acid, optionally mixed with thiodipropionic acid esters and / or benzotriazole derivatives, characterized in that they are a compound of the general formula as the phosphite ester where X -S- or> Ar1 is an arylene radical which is mono- or disubstituted by alkyl or cycloalkyl groups having 3 to 12 carbon atoms and Ar2 is an aryl radical which is mono- to trisubstituted by alkyl or cycloalkyl groups having 3 to 12 carbon atoms , wherein one of these groups can also be an alkoxy group. Documents considered: French patents No. 1 235 047, 1 295 016, 1324451.