NO124889B - - Google Patents

Description

Stabilized masses of halogen-containing polyvinyl derivatives and mixed polymers thereof.

The hitherto common methods for stabilizing polyvinyl chlorides and their mixed polymers with heavy metal compounds, especially lead salts, almost without exception lead to cloudy masses, as these themselves and their cleavage products are insoluble in polymers. In addition, larger amounts of this are mostly used, approx. 2 to 8 percent by weight, in order to achieve the required high resistance values, for example in softener-containing polyvinyl chloride spray compositions for the electrical insulation of wires and cables, with a simultaneous high thermal stability.

Also in the stabilization of plasticizer-free masses and masses that are heat-exposed to great stresses of polyvinyl chlorides or their mixed polymers with other vinyl compounds relatively large addition quantities of the usual metal stabilizers are required, so e.g. in the case of masses to be processed in injection molding processes.

Directly opposite this, e.g. cadmium compounds and above all organotin compounds or their combinations with alkaline earth and/or epoxy compounds are certainly more effective as they, due to their good solubility in the vinyl chloride polymers, mostly give clear transparent masses of very high light- and var-mestability. The additives required for this mostly vary to approx. 3 to 5 percent by weight. Their use in masses which are exposed to large electrical stresses, e.g. for the insulation of wires and cables, is however limited precisely because of this solubility and a certain conductivity. In particular, the cleavage products formed will more or less quickly reduce the initially still usable resistance values of such overcoating compounds.

It now turned out that from halogen-containing polyvinyl compounds and/or their mixed polymers you get particularly highly stabilized masses when you process them with dialkyl tin timer captides of the general formula

where Ri, R2-, R» and R4 mean the same or different alkyl residues and are simultaneously processed with an addition of heavy metal compounds.

Suitable halogen-containing polyvinyl compounds are e.g. polymers of the vinyl chloride or mixed polymers thereof with vinylidene chloride, vinyl acetate or vinyl propionate, as well as butadiene-containing mixtures of the polyvinyl chloride.

As dialkyltin dimercaptides, for example: dibutyltin-di-octadecylmercaptide, dibutyltin-bis-dodecyl-mercaptide, dibutyltin-di-octylmercaptide, dioctyltin-di-octylmercaptide, dioctyltin-bis-dodecylmercaptide, dioctyltin-di-hexylmercaptide, didecyl-tin -di-octylmercaptide, bis-dodecyltin-di-hexyl-mercaptide and bis-dodecyltin-bis-dodecylmer-captide.

Of the heavy metal compounds, besides the cadmium compounds, e.g. cadmium stearate etc., above all suitable basic lead compounds, lead oxides and lead carbonate. Common lead stabilizers are e.g. known: tribasic lead sulfate, tribasic lead maleinate, dibasic lead phthalate, basic lead silicate sulfate, basic lead chlorosilicate, dibasic lead phosphite, lead salicylate, lead cyanamide, basic and neutral lead stearate or -ricinoleate, etc. 1.

Surprisingly enough, the incorporation of both types of stabilizer is already achieved with relatively small weight fractions of dialkyltin dimer peptides, e.g. amounts up to 1 percent by weight, and the same or a simple multiple thereof, e.g. the 5- or 10-fold amount of the heavy metal compounds, stability values which often change to twice and more than the stability values for the tin-free comparison samples at the same lead content. Here, for the most part, the same high resistance values are also maintained for the vinyl polymer masses stabilized in this way, as for the tin-free comparison samples.

It turns out to be particularly advantageous to incorporate relatively small amounts of the tin stabilizer already during the production of the halogen-containing vinyl polymer, and this only slightly pre-stabilized product is only afterwards mixed with the heavy metal compounds and the mixture is then processed in the usual way.

The stabilized masses obtained in this way are, in particular, when only small amounts of stabilizer are used in general, generally light-colored and possess very high heat and light stability with good electrical insulation properties at the same time. They can, for example, also be processed without softening agents into light-coloured sprayable compounds, into almost transparent foils or also into hollow cores. Gram-mophone records with noise-free tone reproduction can also be produced from masses stabilized in this way on the basis of halogen-containing mixed polymers.

Example:

A mixture of 75 parts by weight of a polyvinyl chloride produced in a suspension process (of K-value 70), 25 parts by weight of dioctyl phthalate and 0.2 parts by weight of a purified montan wax as a lubricant is rolled for 10 minutes at 160° C and of a sample of the stripped roll skin the heat stability at 175° C is determined according to Meixner.

For comparison, a similar batch (2) of polyvinyl chloride is rolled which already contains 0.2% by weight of dioctyltin bis-dodecyl mercaptide.

Finally, the two batches of the tin-free (3) and the tin-containing (4) polyvinyl chloride are repeated and 2.25 parts of tribasic lead sulphate are added each time.

The heat stabilities determined on these 4 roller skin samples are entered as minute values in the following table. The table also includes the results of similar trials of polyvinyl chloride with a different pre-stabilisation (other tin stabilizers) and other lead compounds. In the intersection points for the individual rows, the stability times for the combinations are listed, which therefore simultaneously contain both lead and tin stabiliser.

Claims (2)

1. Stabilized masses of halogen-containing polyvinyl derivatives and mixed polymers thereof, characterized in that the finished masses contain up to 1% dialkyl tin dimer captide of the general formula where Ri, R->, Ra and R4 mean the same or different alkyl groups, and at the same time in does not contain heavy metal compounds, preferably lead or cadmium compounds, as stabilizers. 2. Process for the production of stabilized masses according to claim 1, characterized in that the dialkyl tin dimer caps are added to the halogen-containing vinyl polymer already during its production and the heavy metal compounds are added to this pre-stabilized product only afterwards, advantageously during its further processing.