TPU elastomer composition based on dialkyl dithiohypophosphite composite flame retardant system for electric wires and cables and preparation method thereof

Abstract

The invention discloses a TPU elastomer composition based on a dialkyl dithiohypophosphite composite flame retardant system for electric wires and cables. The TPU elastomer composition comprises 65-90wt% of a TPU matrix material, 9-30wt% of a composite flame retardant system and 0.1-5wt% of an assistant. The composite flame retardant system comprises dialkyl dithiohypophosphite and a carbon-forming component. The dialkyl dithiohypophosphite is shown in the formula (I) and in the formula, R1 and R2 independently represent a linear alkyl group or a branched alkyl group, M represents Mg, Ca, Al,Sb, Sn, Ge, Ti, Fe, Zr, Zn, Ce, Bi, Sr, Mn, Li, Na, K, H or NH4 and m is 1-4. The cable material prepared from the TPU elastomer composition has the characteristics of no molten droplet, high flame retardancy, migration resistance, softness, wear resistance and oil resistance.

Description

technical field [0001] The invention relates to the technical field of halogen-free flame-retardant TPU, in particular to a TPU elastomer composition for electric wires and cables based on a dialkyl dithiophosphinate composite flame-retardant system and a preparation method thereof. Background technique [0002] Polyurethane is a type of polymer whose main chain contains -NHCOO- repeating structural units, abbreviated as PU in English, which is polymerized from isocyanate (monomer) and hydroxyl compound. Because it contains a strong polar carbamate group, it is insoluble in non-polar solvents, and has good oil resistance, toughness, wear resistance, aging resistance, etc., and has been widely used in many fields. Polyurethane includes two types of materials, one is thermosetting PU, which is usually used in synthetic leather, foaming and other fields; the other is thermoplastic polyurethane, referred to as TPU, which has the processing method of thermoplastic materials and h...

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Problems solved by technology

At present, the most widely used are ammonium polyphosphate (APP) with high polymerization degree and organic phosphates, ammonium polyphosphate (APP) flame retardant system with high polymerization degree, which belongs to an intumescent flame retardant system, because of its flame retardant Compared with the inorganic hydroxide system, the addition amount of APP is much lower than that of the inorganic hydroxide system. However, APP is still incompatible with the matrix material due to its hydrophilic surface and certain water solubility. Therefore, the flame-retardant TPU of the APP system is elastic The mechanical strength of bulk materials is still low, and at the same time, it is easy to migrate and precipitate, and the whitening phenomenon of precipitation occurs on the surface of the cable, which not only affects the appearance, but also causes the flame retardancy of the cable to gradually decrease with the precipitation

In addition, due to the presence of ammonium ions, APP is easy to absorb moisture. After a period of time, there will be water droplets on the surface of the TPU cable, which reduces the insulation performance of the material and poses a major safety hazard; while some organic phosphates are still water-soluble, and some Although the water solubility is small and overcomes the problem of moisture absorption, its flame retardant mechanism belongs to condensed phase flame retardant, which belongs to non-intumescent type. For TPU elastomer materials, it is easy to form drips and ignite when it is on fire. For other combustibles, molten droplets will affect the flame retardant effect, and it is difficult to meet the standard requirements

[0007] In general, the main defects of the flame retardant system currently used in cable TPU materials are: poor flame retardancy, easy to melt, easy to absorb moisture, migration and whitening, etc.

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