DD251768A1 - METHOD FOR THE PRODUCTION OF RUBBER MIXTURES WITH TRAIGERED FLAME PROTECTION AGENTS - Google Patents

Abstract

A process for the preparation of rubber mixtures with carrier-bound flame retardants is described. The flame-retardant substances are applied to an adsorptive carrier material and added as a phyllosilicate / flame retardant adduct of the rubber mixture during the mixing process. As flame-retardant substances halogenated compounds are used. With the use of phyllosilicate / flame retardant adducts, selective desorption of the flame retardant from the carrier substance is possible. Since the compatibility of the adducts with the various types of rubber need not be taken into account, a higher dosage, based on the active substance of the flame retardants in rubber mixtures is possible, so that a greater flame retardancy can be achieved. The process can be used in the rubber and plastic processing industry.

Description

Field of application of the invention

The invention relates to a process for the preparation of rubber blends having supported flame retardants whose elastomer base is natural and / or synthetic rubbers containing fillers, plasticizers, accelerators and other blend ingredients. During the mixing process, a phyllosilicate / flame retardant adduct is added to the rubber mixture. The process can be used in the plastics and rubber processing industry in the manufacture of all types of products. Polymer products are rendered flame-retardant by the addition of carrier-bound flame retardants, which inhibit combustion in competing reactions.

Characteristic of the known technical solutions

It is known that the rubber mixtures inorganic and / or organic flame retardants are added for the production of flame-retardant products. As flame retardants antimony trioxide, aluminum hydroxide, boron compounds and halogenated hydrocarbon compounds are used. The mode of action of the flame retardants is due to synergistic effects between inorganic and organic flame retardants. If the rubber used does not contain halogen itself, halogenated compounds must be used. The choice of halogen compounds requires some care, since the product must not decompose during processing, but under the action of the flame to split off the corresponding hydrogen halide. Chloroparaffins are the simplest and cheapest representatives of this class, but their compatibility and effectiveness with different rubbers is quite different and thus their optimal effectiveness is often called into question. Chlorinated rubbers have flame retardant properties right from the start, but improved flame retardancy is required for many applications. At times, such more stringent requirements can be met by the addition of antimony trioxide, which, however, leads to an unfavorable mass / power ratio. In other cases, it proves necessary to increase the halogen content of the rubber mixture, that is to add halogenated substances. The use of chlorinated rubbers and / or chlorinated compounds during the processing phase of the rubber mixture lead to significant corrosion phenomena at the processing plants.

Object of the invention

The aim of the invention is the preparation of rubber mixtures with carrier-bound flame retardants. With the use of phyllosilicate / flame retardant adducts, the particular adsorption properties with regard to selectivity and adsorption capacity of flame retardants on phyllosilicates are to be utilized for the production of flame-retardant rubber mixtures. During the processing phase of the rubber compounds, the carrier-bound flame retardants must not desorb.

Explanation of the essence of the invention

The invention has for its object to provide a process for the preparation of rubber mixtures with carrier-bound flame retardants. The object is achieved in that the rubber mixture, a layered silicate / flame retardant adduct is added. Phyllosilicates are polysilicates of the general formula M ₂ O.ySiO ₂ ZH ₂ OmJt layer structure, where M is an Al kai ion or proton, y a Za hl between 4 and 48 and ζ a number between 5 and 25.

The synthesis of the phyllosilicates takes place by crystallization in the ternary system. Thereafter, the separation of the water-insoluble phyllosilicates from the suspension takes place by mechanical means. Na magadiite z. For example, the formula has Na ₂ O. 14SiO ₂ .9H ₂ O and is dewatered by drying. The active substance of the flame retardant is - based on the total mass of the rubber mixture - 10Gew .-% to 15Gew .-%. The flame-retardant substances are applied to a carrier substance and added as a layered silicate / flame retardant adduct during the mixing process of the rubber mixture. The phyllosilicate / flame retardant adducts contain from 90% by weight to 40% by weight phyllosilicate and from 10% by weight to 60% by weight flame retardant. With the use of phyllosilicate / flame retardant adducts, selective desorption of the flame retardant from the vehicle to achieve its effectiveness as a flame retardant substance is possible. The inhibition in the gas phase is likely to be the most important measure for increasing the flame retardancy, on the one hand because of the relatively low. Amounts of flame-retardant additives that give a clear effect, on the other hand because they allow to elucidate the reactions occurring in the flame. Since the relatively small amounts of halogen compounds should not substantially alter the specific heat and thermal conductivity of the rubber composition, the conclusion appears to be that they exert an influence directly on the gas phase combustion process.

The flame-retardant additive / layered silicate combinations are stable enough to withstand the processing of the rubber composition unchanged, but again not too stable, because the phyllosilicate / flame retardant adduct must desorb the halogen compound during firing of the rubber material. With the use of phyllosilicate / flame retardant adducts, selective desorption of the flame retardant from the vehicle to achieve its most effective efficacy as a flame retardant substance is possible. The stability of the phyllosilicate / flame retardant adducts during the processing of the rubber mixture has the effect that the corrosive effects on the processing plants can be largely avoided. Furthermore, with the use of the carrier-bound flame retardants there is the possibility of a higher dosage of effective flame retardant substance, since the compatibility of the adducts with the various types of rubber need not be taken into account. In the following, embodiments explain the method according to the invention without restricting it.

test formulation

FROM

Styrene-butadiene copolymer 60.00% by weight

HAF soot 14.00% by weight petroleum softener. 5.00% by weight

Zinc oxide 2.00% by weight

Stearic acid 1.00% by weight

N-cyclohexyl-2-benzothiazyl sulfenamide 1.50% by weight

Sulfur 1.50% by weight

Chlorinated paraffin 5.00% by weight

Antimony trioxide 10.00% by weight

Na magadiite / flame retardant adduct - 60.00% by weight

Degree of loading: 25% by weight

test values

- vulcanization behavior (Mooney viscometer)

Material- Loading rate of temperature tg-time V ₃₀ Tempe H variant phyllosilicate ⁰ C min ME Min " ¹ ture Sh Wt .-% ⁰ C A - 150 13.3 25.0 150 70 B + 1,1,2,2 25 150 14.1 16.7 150 69 Tetrachloroethane B + ethyl bromide 25 150 13.7 22.5 150 71 - Physical-mechanical characteristics Material- Vulkanisa F D variant tion time MPa % min A 30 14.8 367 B + 1,1,2,2 30 13.8 342 Tetrachloroethane B + ethyl bromide 30 14.1 396

- Determination of the oxygen characteristic value The test was carried out in accordance with DIN 22117 - November 1984. Material variant Oxygen characteristic value in%

A 25.5 B + 1,1,2,2-tetrachloroethane 27.6 B + ethyl bromide 29.2

The higher oxygen characteristic indicates the greater flame retardancy of the rubber material.

Reference installation / Symbols Characteristic symbol

Scorch time t _s in minutes

Vulcanization rate V ₃₀ in Mooney units

per minute

Tensile strength Fin MPa

Breaking elongation Din%

Hardness H in Sh A

Claims (5)

A process for the preparation of rubber mixtures with carrier-bound flame retardants whose elastomer base natural and / or synthetic rubber containing fillers, plasticizers, accelerators and other Mischungsingredienzien, characterized in that in the rubber blend a phyllosilicate / flame retardant adduct with a mass fraction of active flame retardant substance from 5% by weight to 30% by weight, preferably 10% by weight to 15% by weight, based on the total mass of the rubber mixture. 2. The method according to item 1, characterized in that the proportion of phyllosilicates 90% by weight to 40% by weight and that of the flame retardant 10% by weight to 60% by weight in the phyllosilicate / flame retardant adducts. 3. The method according to points 1 to 2, characterized in that the flame retardants are halogenated hydrocarbons. 4. The method according to points 1 to 3, characterized in that the flame retardants are inorganic substances. 5. The method according to points 1 to 4, characterized in that is used as a layered silicate Natriummagadiit.