Compsn. contg. magnesium hydroxide carbonate and opt. other fire retardant - used in cable e.g. as core filler or in sheath, electrical equipment etc., withstanding high processing temp.

摘要

Compsn. (I) contains fire-retardant additive(s) (II), including Mg hydroxide-carbonate (IIA). (IIA) is used alone; or (II) also contains (IIB) and/or (IIC) and the ratio of (IIA) + (IIB), if used, to (IIC) pref. is 1:10 to 100:1. USE/ADVANTAGE - (I) is used in cables, pref. as filler for the cable core, additive to the material of the cable sheath and/or any other constituents of the cable; and in equipment, esp. electrical components (claimed). It ensures good processing properties and improved the fire retardancy. Since (IIA) decomposes only above 225 deg. C., it can be can be mixed with plastics for extrusion of relatively high temp.. The use of (IIA) allows the total (II) content to be minimised, which is important for electric and optical cables. (IIA) is a very effective smoke inhibitor and its limiting oxygen index (LDI) is partly highly than that of Al hydroxide. In a fire, (I) forms a protective crust. In addn. of mixt. of (IIA) and Mg-Ca carbonate (IIB) is cheaper than Al hydroxide and/or Mg-OH).2 A synergistic increase in the LOI is obtd. with a mixt. of (IIA), (IIB) and Al(OH)3 (IIC). In an example, mixts. were prepd. from (A) 20.32, (B, C, E) 19.69, (D) 21.85% 'Levapren 400' (RTM), (A) 46.48, (B) 74.91, (C) 3.15, (D) 45.15, (E) 44.91% 'Apyral 90' (RTM), (A) 27,80, (B-E) 0% chalk, (A, B) 0, (C) 72.200, (D, E) 30.00% (IIA), (A, B, C, E) 0.40, (D) 0% stearic acid and 3.00% napthenic plasticiser and 2.00% dispersant, (A, B) being controls. The LOI was (A) 50/56, (B) 86, (C) 46/42. (D) 68/66. (E) 66. Initially/after 7 days at 80 deg. C., the tensile strength was (A) 2.5%/4.1, (B) 4.1/6.3, (C) 2.4/4.1, (D) 3.5/4.9, (E) 2.4/4.7 N/mm2; and elongation at break (A) 165/80, (B) 90/55, (C) 330/100, (D) 180115, (E) 170-150/80%. Samples (A, C, D, E) were used as gap filler, whereas (B) could not be processed in this way. (C, D, E) withstood a burning test, whereas (A) did not.