CS200914B1 - Material based on polyvinylchloride with limited flammability - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a flame retardant polyvinyl chloride based compound for use in electrical engineering and melting.

Currently, polyvinyl chloride is one of the most widely used and most widely used plastics. In addition to its relatively easy processing and very good physico-mechanical properties, this material belongs to a very small group of flame retardant materials with a relatively high halogen content. This property can be further improved by the small addition of synergistic additives, most often antimony trioxide. Therefore, until recently, no further measures have been taken to reduce the flammability of this material.

Recently, however, it has been found that under certain circumstances polyvinyl chloride may burn even if it is retarded by the present methods. This is particularly unpleasant for the electrical industry, where almost 95% of all all-plastic insulations are based on polyvinyl chloride. In fact, at higher operating temperatures of the conductors, this material loses its flame retardancy very quickly and at the time it reaches a temperature of about 120 to 150 ° C, ie temperatures close to the processing temperatures already burn relatively well. In addition, hydrogen chloride begins to cleave at the non-stabilized polymer at temperatures between 16 ° C and 180 ° C. This means that a very small amount of burning polyvinyl chloride forms a considerable amount of breathable, highly toxic fumes. Since this material is used today already

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200 814, not only in industry, but also in the interior and furnishing of buildings, this polymer poses a considerable danger to the health and lives of people. In addition, the resulting hydrogen chloride precipitates in the air together with water vapor and settles in the form of hydrochloric acid, which causes very strong corrosion of most metal parts of the equipment or interior, damages that occur annually as a result of fires. tens of millions of Kcs.

The above-mentioned disadvantages overcome most of the solution according to the invention. The present invention provides a 100 wt. parts by weight of polyvinyl chloride, 4 to 30 wt. 2 parts by weight of melamine and / or tertiary amine; parts by weight of pentaerythritol and / or sorbitol or arabite; parts by weight of starch and / or déxtrin or carboxymethylcellulose; parts of mono or diammonium phosphate and / or organophosphate.

Said mixture is added to the mass during processing, and some components may have a favorable effect on other material properties. For example, organophosphates (tricresyl phosphate, triphenyl phosphate, trichloroethyl phosphate) are simultaneously used as plasticizers and can therefore be formulated in the mixture as desired either in combination with ammonium phosphate or alone, depending on the degree of softening of the mass. The other ingredients of the mixture may replace traditional fillers.

The material expands slightly when exposed to flame and a relatively hard surface crust is formed on its surface, which does not allow further flame spread. In addition, this crust prevents the flow of thermoplastic insulation to a large extent and thus extends the service life of the device, eg cables, while still under power, of course reduces the amount of toxic fumes, furthermore greatly reduces the spread of fire. very little drips.

The applicability of this material is very wide. Main, use can be seen primarily in the area. cable insulation. Here, the advantage of the solution is particularly evident, because it is currently necessary to build for all-plastic conductors with regard to easy fire spread over cables - costly cable fire barriers, barriers and divisions, cables must also be sealed in such barriers, etc. various types of non-flammable arintumescent preparations. If the solution is implemented to a greater extent, there may be a very significant interference with the applicable ČSN standards, especially the ČSN 38 21 56 standard. prescribed different types of bulkheads.

However, mass can also be used in many other industries. For example, classic flooring on this basis also presents a considerable risk of fire in housing units, which is again manifested only by the spread of fire in the building. The various types of industrial gaskets, piping, air handling equipment, etc., especially in the chemical industry, are another example where the application of such modified material can bring significant benefits.

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Example 1

For cable insulation, a common type of PVC compound was used in which tricresyl phosphate plasticizer was used. To this mixture was added 5 wt. parts of diammonium phosphate, wt. parts by weight of pentaerythritol, 8 wt. parts of dextrin and 8 wt. parts by weight of melamine, per 100 wt. parts of the base mixture.

Example 2

Into the polyvinyl chloride casting paste was used per 100 wt., Parts of the paste 8 wt. parts by weight of hexamethylenetetramine, (urotropin), 12 wt. parts by weight of sorbitol, 6 wt. parts of starch and 20 wt. parts of ammonium phosphate.

Claims (1)

SUBJECT OF THE INVENTION Polyvinyl chloride-based flame retardant composition characterized in that it consists of 100 wt. 4 to 30 wt. 2 parts by weight of melamine and / or tertiary amine; parts by weight of pentaerythritol and / or sorbitol or arabite; parts by weight of starch and / or dextrin or carboxymethylcellulose; parts of mono or diammonium phosphate and / or organophosphate.