DE1067586B - Process for the production of flame-retardant foam compounds or bodies from flammable, thermoplastic plastics - Google Patents

Description

Foam compositions made from thermoplastics, e.g. B. made of polystyrene, have in recent years under Among other things as an insulating material in the cooling technology and in the building industry as well as molded bodies of all kinds of considerable importance attained. In many areas of application, especially in the construction industry, flame retardant Foam body preferred. The present invention relates to a method for producing foam masses from combustible, to make thermoplastic plastics flame-retardant in an advantageous manner.

Attempts have been made in numerous ways to make combustible foam bodies flame-retardant. Either the expandable plastics have been mixed with incombustible substances and the flame-retardant mixtures have been foamed, or finished foam bodies have been coated with incombustible substances. It is also known that flammable materials can be made flame-retardant with the aid of halogen compounds. Among the halogen compounds, the bromine compounds are known to be more effective in reducing flammability than chlorine compounds. In order to make foam bodies flame-retardant, the expandable plastics have already been mixed with halogen compounds. However, the difficulty of obtaining homogeneous mixtures and the need for an additional mixing process are disadvantageous in this process. To avoid these disadvantages, halogen compounds, in particular bromine compounds, have also been added to the monomeric starting materials of plastics and these mixtures have been polymerized and foamed. Here, however, the halogen compounds often have an undesirable effect on the polymerization process . The finished foam body has finally been treated with aqueous ammonium salt solutions, e.g. B. with ammonium bromide solutions, or they have been coated with water glass, mortar or similar mineral substances. However, water-soluble compounds can easily be dissolved out of the foam bodies and also have a corrosion-promoting effect if the foam bodies are processed together with iron. Coatings and casings can finally never provide the same fire protection as flame-retardant substances distributed in the foam body.

It has now been found that the flammability of foam bodies made of combustible, thermoplastic plastics can be reduced very effectively in a simple manner without the technological properties of the polymers or the foam bodies being adversely affected by expandable structures made of thermoplastics or finished, foam-shaped plastic bodies and water-insoluble with solutions of water-insoluble, organic bromine compounds, resinous compound m en treated in organic solvents.

Method of manufacture
flame-retardant foam compounds
or bodies made of flammable,
thermoplastics

Applicant:
Aniline & Soda Factory in Baden
Corporation,
Ludwigshafen / Rhine

Dr. Fritz Stastny, Dr. Karl Buchholz
and Dr. Heinz Müller-Tamm, Ludwigshafen / Rhine,
have been named as inventors

Suitable organic bromine compounds are those known per se for making foam bodies flame resistant Bromine compounds, insofar as they are insoluble in water but soluble in organic solvents, e.g. B. alcohol soluble are, such as 2,3-dibromopropanol, di- (2,3-dibromopropyl) ether, 2,3-dibromopropanol phosphate, formaldehyde di (2,3-dibromopropyl) acetal or acetate aldehyde di (2,3-dibromopropyl) acetal.

Resin-like compounds are soluble in organic solvents, e.g. B. alcohol-soluble, but water-insoluble substances that dry to tack-free, cohesive films, e.g. shellac, polyvinyl acetals, phenol-formaldehyde resins or with a polyhydric alcohol, e.g. B '. Butanediol, glycerol or pentaerythnt-esterified addition products of rosin and an unsaturated carboxylic acid or dicarboxylic acid, e.g. B. maleic acid.
The bromine compounds and resinous compounds.

are in the case of foamable particles or foam moldings made of polystyrene, preferably dissolved in an alcohol, expediently in an aliphatic alcohol such as methanol, ethanol or butanol, because alcohols do not dissolve polystyrene. Advantageous to set forth solutions containing about 40 ° / ₀ of the bromine compound and about 40% of the resinous compound.

According to the method according to the invention, expandable gabildas or finished foam bodies made of thermoplastic are made Plastics treated with solutions of bromine compounds and resinous compounds. The expandable structures, z. B. expandable particles of polystyrene, the low-boiling petroleum ether than Contain blowing agents, are expediently mixed with so much alcoholic solution that for 100 weight-

909 639/346

Claims (1)

: quick expandable particles together 5 to 20 weight: quick bromine compound and resin come. In the aJkohoischen Solvents can also contain pigments or other additives, e.g. B. powdered, chlorine-containing compounds or antimony trioxide are dissolved or suspended. After the expandable particles have been uniformly coated with the alcoholic solution by briefly mixing them, they can be dried to remove the alcohol or foamed directly without intermediate drying. In the conventional method, expandable polystyrene particles, the low-boiling organic liquids as the blowing agent develop prefoamed by storage in water at 95 ° C or with the aid of 100 to Ilo ⁰ C hot water vapor. In this process step, most of the alcohol is removed with the water or steam, so that a dry, flame-retardant material is available for further processing. In comparison, the mixtures of expandable particles and alcoholic solutions for the production of TOn pre-expanded material or of finished foamed molded bodies have to be heated somewhat longer than the expandable material without the flame-retardant additive. A good flame-retardant effect can also be achieved if the non-foamed expandable particles are used instead The pre-expanded material is treated with the alcoholic solution of the bromine compound and the resin will. The partially foamed and soaked with the solution particles can also after drying or can be foamed without removing the alcohol beforehand. Finally, you can also use pre-foamed Make molded bodies flame-retardant by dipping them into the alcoholic solutions and allowing the alcohol through Drying away. The finished foam bodies are made with approximately the same amounts of bromine compound and resin to be treated like the intumescent particles. This is not only done with the coating of foam bodies Flame-repellent agents achieve a pure surface effect, but also deeper layers of the Molded body made difficult to burn in this way. According to the method according to the invention, foam compositions made of thermoplastics can through the mass - or, when treating the finished foam body, at least with a certain depth effect - be made flame-proof. The treatment of the expandable particles or the foam masses is simple and does not require any additional equipment. The technological characteristics will be not worsened by treatment; on the contrary, the foam compositions made flame-proof according to the process have a stronger structure density, which results in increased compressive strength and reduced water vapor permeability makes noticeable. The density is only slightly increased. Compared to with the help of water-soluble Compounds of flame-retardant foam masses the quality of the foam compositions made flame-resistant according to the process is determined by the action of moisture or water hardly deteriorates and the fire protection effect is practically not reduced. The parts mentioned in the examples are parts by weight. example 1 10 parts of 2,3-dibromopropanol phosphate and 10 parts of an addition product, esterified with butanediol, of rosin and an α, / 3-unsaturated carboxylic acid, which has an acid number of about 165, are dissolved in 50 parts of ethyl alcohol. The solution is added to 100 parts of expandable polystyrene particles and mixed with it mechanically. The expandable particles are then heated for 2 minutes with the aid of steam at 107 ° C., their original bulk density being reduced from 500 g / l to 30 g / l. The pre-expanded particles thus obtained are filled into a perforated metal mold and the closed mold is stored in a steam autoclave at 107 ° C. for 6 minutes. After cooling, a foam body with a specific weight of 0.03 is obtained, which only burns in the external flame while melting, but goes out when the external flame is removed. Foam compounds of this type are ideally suited as insulating material in construction and in cooling technology. They can also be used for decoration purposes and to make lifebuoys, or they can be used in Build in ships to make them unsinkable. Example 2 100 parts of pre-expanded but still expandable polystyrene particles with a bulk density of 50 g / 1 are used with 30 parts of a solution consisting of 10 parts of ethyl alcohol, 10 parts of 2,3-dibromopropyl ether, 10 parts Shellac and 0.1 part of an alcohol-soluble dye is mixed. After storing the Particles at room temperature in a layer about 5 cm high, the mass is enclosed in a perforated metal mold and stored in boiling water for 10 minutes. After cooling, you get a marbled colored foam with a specific gravity of 0.07, which does not burn without an external flame. Claim: - 'Process for the production of flame-retardant foam masses or bodies from flammable, thermoplastic Plastics, characterized in that expandable structures made of thermoplastics or finished, foam-shaped plastic bodies with water-insoluble, organic bromine compounds and water-insoluble resinous compounds, both dissolved in organic volatile solvents, be treated. © m 639/346 10.59