NO141289B - PROCEDURES FOR AN INSULATED MULTI-THREAD LEADER, TO PROVIDE A STRIPPED LEADERSHIP ENTER PART BY USING A FIXER ATTACHED THREADS - Google Patents

Description

Stabilizer for polyolefins.

High polymer compounds are known to be sensitive to oxygen, heat and exposure to light, as a breakdown occurs which makes the products brittle. This relationship is also known for polymers of the olefin series. Both high- and low-pressure polyethylene have therefore been protected, and

then, according to the low-pressure method, polymers produced from α-olefins, for example from propylene, butene and 4-methylpentene-1. against the effects of heat, oxygen and light by adding substances that have a stabilizing effect.

Thus it is used for stabilization

of polyolefins, e.g. substituted phenols such as 2,6-di-tert.butyl-p-cresol or also sulfur-containing phenolic compounds such as 4,4'-thio-bis-(6-tert.butyl-m-cresol). Likewise, amines are known as stabilizers, such as dinaphthyl-p-phenylene-diamine. Combinations of phenolic compounds with organic sulphidic compounds prove particularly effective with polymers containing

where tertiary C atoms in the chain molecule, the improvement being attributable to a synergism. Thus, Belgian patent no. 577,252 describes the use of the condensation product of nonylphenol and acetone in combination with thio-di(propionic acid lauryl ester), whereby a significant improvement is achieved in the heat stability of the polyolefin, especially of polypropylene.

It is also known that the presence of certain metals, such as copper and its alloys, manganese, cobalt, iron and others, significantly reduces the heat and oxidation stability of the polyolefins. Thus, e.g. moldings of polyolefins containing particles of the above-mentioned metals, significantly poorer aging properties. The use of polyolefins as insulation material for sheathing electrical conductors is therefore only possible to a limited extent, as the insulation of polyolefins standing in contact with the mentioned metals without the addition of suitable stabilizers relatively quickly embrittles at higher temperatures. Protective coatings applied to metals by the vortex sintering process also embrittle after a short time for this reason.

The object of the invention is a stabilizing agent to counteract the catalysis of the thermal degradation by metals of conventionally stabilized polyolefins, especially those with tert.-C atoms in the polymeric chain such as polypropylene, polybutyl

lene, poly-4-methylpentene-1, by means of an organic phosphorus compound, and the stabilizer is characterized in that the organic phosphorus compound has the general formula

where R = H, alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl.

Preferably, any stabilizers used are di-aryl <:>di-thiophosphinic acids, the aryl radical being a phenyl or o-, m-, p-tolyl radical, which gives the following structural formulas:

The described stabilizers can be used together with known stabilizers and fillers such as carbon black, zinc oxide, zinc sulphide and the like.

As known stabilizers, the phenolic stabilizers such as alkylphenols with up to 12 C atoms in the alkyl group are particularly suitable, e.g. p-tert-butylphenol, amyl-phenol, p-octylphenol, p-nonylphenol, p-dodecylphenol, 2,4-di-tert-butylphenol, 2,4-dioctylphenol, dinonylphenol, 2,4, 6-tri-tert.-butyl-phenol, 2,6-di-tert.-butyl-p-cresol, nonylresorcin, dodecylhydroquinone and the bis-phenols such as e.g. 4,4'-dihydroxy-diphenyl-dimethylmethane, bis-(4-hydroxy-3-methylphenyl)-propane-(2,2), 4,4'-dihydroxydiphenyl, bis-(4-hydroxy-3,5 -dimethyl-phenyl)-methane, bis-(4-hydroxy-3,5-di-tert-butylphenyl)-methane, bis-(2-hydroxy-3-tert-butyl-5-methyl-phenyl) -methane, bis-(2-hydroxy-5-chloro-phenyl)-methane, bis-(4-hydroxy-3-methylphenyl)-pentane, bis-(2-hydroxy-phenyl)-cyclo -hexane, 4,4'-thio-bis-(6-tert-butyl-m-cresol).

Naphthols and bis-naphthols such as (3-dinaphthol, bis-(2-hydroxy-naphthyl)-methane, bis-(2-hydroxy-3-nonyl-naphthyl)-methane, terpene-substituted phenols and bis-phenols such as 6-iso -bornyl-o-cresol, 6-isobornyl-1,2,4-xylenol, 2,6-diiso-bornyl-p-cresol, 6-isobornyl-3,4-dimethylphenol, 2,6-diisobornyl -3,4-dimethylphenol, 6,6'-methylene-bis-(2-isobornyl-4-methylphenol), 6,6'-methylene-bis-(2,4-diisobornylphenol).

A particularly good stabilization is achieved when the cost stabilizer according to the invention is used together with a combination of phenolic stabilizers and organic sulphidic compounds. Particularly suitable as sulphidic compounds are: thio-ethers, preferably of aliphatic alcohols with 4-18 C atoms, such as e.g. dioctyl sulphide, didodecyl sulphide, dioctadecyl sulphide and bis-(2-hydroxy-naphthyl) sulphide and the corresponding polythioethers, such as e.g. di-dodecyl-disulfide, di-octyl-trisulfide, di-octade-cyl-tetrasulfide, bis-(2-hydroxynaphthyl)-disulfide, also thio- and polythio-di(carboxylic acid alkyl esters), preferably of aliphatic alcohols with 4-18 C atoms, such as thio-di(acetic acid dodecyl ester), thio-di(propionic acid lauryl ester), dithio-di(butyric acid octadecyl ester), dithio-di(valeric acid butyl ester), trithio-di(undecanoic acid nonyl ester), tetrathio -di(butyric acid octyl ester), S-Cert.-butyl mercaptoacetic acid lauryl ester.

As a particularly preferred embodiment, the costabilizer according to the invention (the phosphorus compounds) is used together with the condensation product of 2 mol nonylphenol and 1 mol acetone (according to German patent no. 1,062,926) or together with the combination of this product and thio-di(pro -pionic acid lauryl ester).

The production of the low-pressure polyolefins to be stabilized with the stabilizer according to the invention can take place according to the method described in Belgian patent no. 538,782. Further information on the production of polyolefins according to the low-pressure method can also be found in the book by Raff and Allison: "Polyethylene", Interscience Publishers 1956, pages 72-81.

The stabilizer according to the invention is particularly suitable for stabilizing homo- and copolymers of olefins, preferably polypropylene, which may also contain monomer units other than olefins, and which are used for metal coating, e.g. according to the vortex sintering process or for wire insulation.

As a measurement method for aging studies of polyolefins, the so-called

"Brittle test" has generally been introduced, as the decrease in the flexibility of polyolefins during aging is very characteristic. (Compare Renfrew & Morgan, "Polythene",

London, Iliffe & Sons Ltd. 1957, page 77). For the most part, the "brittle test" is carried out in such a way that pressed samples with approximate dimensions (80x20x1) mm<:i >are suspended in a drying cabinet at a specific aging temperature. Daily it is checked whether the sample still shows a tough elastic condition when bent by hand 180J. Before the bending test, the sample is cooled to 20° C. After a certain time, the so-called "brittle time", the samples break during the bending test.

Another test method to specifically examine plaster's suitability as an insulating material for electrical conductors is the so-called "loop test", ("Lockentest"). Below, a plastic-sheathed electrical conductor is wound around its own axis in small turns, and the "loops" thus formed are subjected to heat cabinet storage. During the winding, the plastic is exposed to stresses, and the brittleness manifests itself in the formation of cracks in the insulation. The time after which cracking occurs is also referred to as "Brittle time". In order to determine the effect of the stabilizer in the presence of metals such as copper, this is added in powder form to the polyolefin, and the Brittle time is measured.

The co-stabilizer according to the invention (the phosphorus compounds) can be mixed alone or together with the other stabilizers by adding in finely powdered form to the powdered polymer in a fast-running mixer, or by dissolving in a suitable organic solvent and adding this solution to the polymer. It is often appropriate to first mix the stabilizer with a small amount of the powdered polymer, so that you get a polymer mixture with 30-40 percent stabilizers (Master batch), with the help of which you can then bring the total amount of polymer to the desired stabilizer concentration. tion. Foils of 1 mm thickness were produced from the stabilized plastic powder on a heated press under the following conditions: 10 minutes pre-heating at 200° C under contact pressure, 2 minutes pressing at 200° C under a pressure of 10 kg/cm - and cooling within 7 minutes at 50 kg/cm2.

Example.

An isotactic polypropylene with a melting point of 164°C and a density of 0.905 g/cm<3 >be blended with 0.25% by weight of the condensation product of nonylphenol and acetone and 0.25% by weight of diphenyl-di-thio-phosphinic acid, and Brittle- the time was determined at 120 and 140° C. The reduced viscosity of the polypropylene powder, measured on a 0.1% solution in decahydronaphthalene at 135° C using 0.5% phenyl-a-naphthylamine as stabilizer, was 8 .9 dl/g.

For comparison, the same polypropylene was also mixed with known stabilizers. The table shows the results of tests according to the invention and the comparison tests.

Claims (1)

Stabilizer for counteracting the catalysis of the thermal degradation by metals of conventionally stabilized polyolefins, consisting of a sulfur-containing organic phosphorus compound, characterized in that the phosphorus compound has the general formula where R = H, alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl.