NO134225B - - Google Patents

Description

Process for making olefin polymers fireproof.

Olefin polymers can be produced

according to different methods and thereby their physical properties vary widely according to the intended purpose of use. But they always have the disadvantage that, as low molecular weight paraffins, they burn easily. For most areas of application, this is unimportant. For certain purposes, e.g. in electrical engineering, however, it is desirable to be able to use a non-combustible plastic with the mechanical properties of a polyolefin.

Many have therefore already been undertaken

attempts to make olefin polymers refractory, e.g. by the addition of chlorinated paraffins or mixtures of chlorinated aliphatic and cycloaliphatic coal hydrosubstances and antimony oxide (U.S. Patent No. 2,669,521). However, it has so far not been successful in practice in finding suitable additives for this, either because these have not been sufficiently effective or incompatible with the olefin polymers and thus significantly deteriorated their colors or mechanical properties. Due to the non-polar character of the olefin polymers and the polarity of most flame retardants, the prospect of a solution to the problem has been small. The proposed chlorinated paraffins already split off HC1 at the processing temperatures so that a processing on the extruder or injection molding machines is unlikely to be used due to the corrosion that occurs.

It has now been found that olefin polymers can be made fireproof by homogeneously mixing them with octachlorodiphenyl dioxide and an oxygen or sulfur compound of an element from the periodic table

system's 5th main group of the elements with

an atomic weight of at least 74, such as arsenic, antimony, and bismuth. Surprisingly, the additives according to the invention give the olefin polymers self-extinguishing properties. The ultimate bending stress, ball compressive hardness and torsional modulus are also improved, while the polymer's color and mechanical properties are not reduced.

Olefin polymers which according to the invention can be made fireproof can be mentioned: Polymers of polymerizable monomers with the general formula CH > = CHR, in which R either means a hydrogen atom, a CH.i group or an unbranched or branched saturated or unsaturated aliphatic carbon-hydrogen residue with 2-10 carbon atoms, but especially ethylene, propylene, butylene, iso-butylene, pentene, methylpentene, butadiene,

dimethylbutadiene, cyclic polymerizable

compounds such as styrene, dimethylstyrene, mixture polymers of the above-mentioned compounds with themselves or with other, thus mixture-polymerizable compounds

such as unsaturated organic acids or their

esters or nitriles, e.g. maleic acid, citraconic acid, itaconic acid, acrylic acid, methacrylic acid ester, acrylonitrile or with vinyl and vinylidene compounds, above all vinyl chloride, vinylidene chloride, vinyl acetate, as well as polymer mixtures of all the above-mentioned polymers. A particularly advantageous effect according to the invention is achieved by polyethylene and its mixed polymers of ethylene with its higher homologues.

The production of the octachlorodiphenylene dioxide can take place according to known methods, for example by continuous heating of pentachlorophenol at 300° <C.

As oxygen and sulfur compounds which, according to the invention, are used in a mixture with octachlorodiphenylene dioxide, the following are above all relevant: Antimony trioxide, antimony pentoxide, antimony trisulfide, antimony pentasulfide, arsenic trioxide, arsenic pentoxide, arsenic trisulfide, as well as bismuth trioxide. Optionally, the use of a mixture of several of the aforementioned compounds brings advantages. The addition of octachlorodiphenyl dioxide to the polyolefin usually amounts to between 5 and 80% by weight, preferably between 8 and 40% by weight, calculated on the total amount of polyolefin. According to the invention, the mentioned oxides and sulfides of the mentioned elements are mixed into the polymer in an amount between 3 and 50%, especially between 5 and 20% (referred to the total olefin polymer).

The mixing of octachlorodiphenylene dioxide and the oxides and/or sulfides of the aforementioned elements to the olefin polymer can be done separately, however, it pays to mix these two components in advance and then first add them to the polymer in question.

Olefin polymers that have been made fireproof with octachlorodiphenyl dioxide can be used everywhere where these properties are required and for this reason the olefin polymers could not be used until now, e.g. in specific areas within the electrical industry.

The invention shall be explained by means of some examples:

Example 1:

760 g of powdered low-pressure polyethylene (density 0.95 g/cm<8>), 190 g of octachlorodiphenyl dioxide and 50 g of antimony trioxide are mixed in a commercial high-speed mixer (Starmix) for one minute, then rolled for 10 minutes at 160°C on a two-roll chair, the rolled skin is cut into small pieces and this is pressed on a heatable hydraulic press at 160° C under contact pressure into a 3 mm thick plate. During cooling, the pressure is increased to 100 kg/cm<a>. When submixing and processing octachlorodiphenylene dioxide and the antimony trioxide with the low-pressure polyethylene, the mixture retains a light colour. Ball compressive hardness, ultimate bending stress and torsional modulus of the produced plate are higher than those of the corresponding plate of only the polyethylene used. The average property is hardly falling.

A 3 cm wide strip of the plate is held for 10 seconds. in the non-luminous flame of

a Teklu burner and then so that the lower edge of the strip is 1 cm above the tip of the inner flame cone and then slowly pulled out, then it goes out within 3 seconds. The test can be repeated with the same strip several times in succession with the same result.

Example 2:

75 g of a powdered mixed polymer of approx. 90 mole percent ethylene and 10 mole percent propylene (density = 0.925), 20 g of octachlorodiphenylene dioxide and 5 g of antimony trioxide are mixed in a commercial high-speed mixer (Starmix) for 1 minute, then rolled for 10 minutes at 145° C on a two-roll chair, the rolling skin is cut in small pieces and these are pressed on a heatable hydraulic press at 160° C under contact pressure into a 3 mm thick plate. During cooling, the pressure is increased to 100 kg/cm<2>. When mixing and processing the octachlorodiphenylene dioxide and the antimony trioxide with the mixed polymer, the mixture retains a light colour.

A 3 cm wide strip of the plate is held for 10 seconds. in the non-luminous flame of a Teklus burner and then so that the lower edge of the srtimme lens is 1 cm above the tip of the flame cone and then slowly pulled out, then it goes out within 10 seconds.

Example 3:

Proceed as described in example 2. Instead of the ethylene-propylene mixture polymer, however, one of approx. 99.2 mole percent ethylene and 0.8 mole percent butene (density is equal to 0.945 g/cm<:1>) and instead of antimony trioxide, arsenic trioxide is added. The test strip extinguishes during the flame test within 3 seconds.

Example 4:

750 g of high-pressure polyethylene granules with an ij value of 1.5 (according to ASTM 1238—

52T) and a density of 0.918 g/cm<3>, is rolled

with 150 g of octachlorodiphenyl dioxide and 100

g SbaO:! on a two-roll chair for 10 minutes at 130° C. The rolling skin is cut into small pieces

and these are compressed on a heatable bar

hydraulic press at 140° C under contact pressure to a 3 mm thick plate. During cooling, the pressure is increased to 100 kg/cm<2>. The mixture has a light color.

A 3 cm wide strip of the plate is held for 10 seconds. in a Teklusl burner's non-luminous flame and so that the lower edge of the strip is 1 cm above the tip of the inner flame cone and is slowly pulled out from here, then it goes out within 5-10 sec. Example 5: A mixture of 500 g of low-pressure polyethylene with a density of 0.95 g/cm<3> and 100 g of high-pressure polyethylene with a density of 0.918 g/cm<3> is rolled on a two-roll chair for 10 minutes at 155° C with 300 g octachlorodiphenylene dioxide and 100 g of Sb^O.i. Press plates of 1 mm thickness, 2 cm width and 3 cm length produced from this mixture are clamped with one end of a horizontal fork. In a room protected from drafts, direct a gas flame for 10 sec. obliquely from below towards the free front edge of the sample, so that the sample starts to burn. After removing the flame, the plate goes out after 2 seconds.

Example 6: Press plates of a mixture of 500 g low-pressure polyethylene (density 0.95), 100 g of a mixed polymer of 90 mol percent ethylene and 10 mol percent propylene (density 0.925), 350 g octachlorodiphenyl dioxide and 50 g Bi::0:i are examined as described in example 5 on its refractoriness. The sample extinguishes after removing the flame after 10 se-customers.

Example 7: Of a mixed polymer of 60 mole percent ethylene and 40 mole percent propylene (density 0.840), which was rolled out on a two-roll chair for 10 minutes at 160° C with 200 g octachlorodiphenyl dioxide and 50 g Sb-iSn, test plates with 1 mm thickness, 2 cm width and 3 cm length are pressed. In the flame test described in example 5, the flame extinguishes in 7 seconds. after the flame is removed.

Claims (5)

1. Process for making polyolefins fireproof, characterized by homogeneously mixing polyolefins with octachlorodiphenyl dioxide and at least one oxygen or sulfur compound of an element from the 5th main group of the periodic system with an atomic weight of at least 74. 2. Method according to claim 1, characterized in that the addition of at least one oxygen or sulfur compound of an element from the 5th main group of the periodic system with an atomic weight of at least 74 amounts to between 3 and 50 percent by weight, preferably between 5 and 20 percent by weight, calculated on the polyolefin. 3. Method according to claims 1 and 2, characterized in that polyethylene is made fireproof with octachlorodiphenyl dioxide and antimony trioxide. 4. Method according to claims 1, 2 and 3, characterized in that the addition of octachlorodiphenyl dioxide amounts to between 5 and 80% by weight, preferably between 8 and 40% by weight, calculated on the polyolefin. 5. Method according to claims 1, 2 and 4, characterized in that the mixed polymer of ethylene and propylene is made fireproof.