SU952893A1 - Process for producing agglomerated composition for foamed plastic - Google Patents

Description

the measured foam composition by introducing polyethylene aerodide carbonamide and activator of its decomposition, including a salt of a fatty acid and a metal of groups II-IV, a metal oxide of groups II-IV of the periodic system, and fatty acid, the components are introduced in waste the following sequence: azodicarbonamide, fatty acid, salt of a fatty acid and a metal of groups II-IV and oxide of a metal of groups II-IV of the periodic system.

Introduction of polyethylene components and components processed in a 7 agglomerator for mixing foaming agent in the sequence aodicarbonamide - fatty acid - salt of fatty acid - metal of II-IV groups -. metal oxide of groups II-IV leads to the fact that, introduced first, azodicarbonamyl is enclosed in the core of the formed agglomerate grains, and the components of the decomposition activator are located in the subsequent layers in order to increase their activating properties, in particular, in the layer adjacent to the other polymer the least effective decomposition activator is a fatty acid, in the subsequent layer an activator of moderate strength (salt of a fatty acid and metal of groups II-IV) is distributed, and finally, in the outer layer of the polymer it is the most effective activator (ox d of the metal II-IV group). .

When a foam is obtained from an agglomerate of such a structure, the probability of local contacts of large amounts of azodicarbonamide with large amounts of decomposition activator components is significantly reduced. Moreover, the decomposition of aerodicarbonamide begins when interacting with the least effective activator fatty acid located closer to it and continues in the presence of the activator of medium activity first — a salt of the fatty acid and a metal of groups II-IV, and then in the presence of the most effective activator, metal oxide II-IV which causes at the beginning of the process a uniform and slow increase in the rate of decomposition reaction to a constant value maintained at subsequent stages of the foaming process.

Such a change in the rate of decomposition of aerodicarbonamide contributes to a more uniform gassing in the volume of the polymer, accompanied by the formation of a uniform cellular structure of the foam, and ultimately an improvement in its quality. Reverse order of introduction of foaming additives to polyethylene waste; first, activators. decomposition, and then azodicarbonamide leads to azodicrabonamide getting on the surface of the agglomerate grains. In this case, the azodicone and the water introduced into the material come into contact to fix the grain sizes of the agglomerate, and during storage with moisture in the air, which drastically reduces the amount of gas released during the decomposition of azodicarbonamide

In addition, such a sequence of introduction of foam-producing dybavok leads to an increase in the loss of azodicarbonamide and deterioration of working conditions.

Example 1. 40 kg of polyethylene film waste is loaded into a rotor agglomerator (diameter of the tank is 900 mm, drive power 100 kW /, rotor speed 1000 rpm) When the material reaches the temperature, 1.2 kg of azodicarbonamide is added to the processed material, then 0.1 kg of stearic acid, 0.4 kg of zinc stearate and 0.7 kg of zinc oxide. The interval between the administration of the individual components is 15-20 seconds. When the material reaches its temperature, 4 liters of water are introduced into it and, after its evaporation, the resulting composition is discharged, which is processed into foam plastic by pressing.

Example 2. 40 kg of polyethylene waste in the form of obsolete bags from under mineral fertilizers are loaded into a rotary agglomerator of Example 1, and upon reaching the temperature 0.2 kg of azodicarbonamide is introduced, and then sequentially at intervals of 20-30 seconds, 0 , 04 kg of stearic acid, 0.1 kg of barium ricinoleate and 0.06 kg of titanium dioxide are then treated as in Example 1. The composition is processed by injection molding into a foam plastic.

Comparative properties of the foam obtained by the known and proposed method are shown in the table.

The introduction of polyethylene waste components, processed in an agglomerator in a mixer, into an azodicarbonamide fatty acid – salt of lithium acid of a metal of groups II – IV groups – metal oxide of groups II – IV allows the use of differences in activating properties of azodicarbonamide decomposition activators to ensure uniform gassing in the polymer and obtaining foam with improved physico-mechanical properties and with a uniform defect-free finely cellular structure

Breaking stress

at stretching, MPa

Relative extension

at break,%

Damping ability,%

Average cell size, mm

2 Number of cells per 1 mm square

sample cut.

Claims (2)

1. Zubov c. C. and others. Recycling 30 foaming compositions in articles. Experience of the plant. Komsomolskaya Pravda, L., 1977, p. 20-22. 2. Larionov A.I. and others. Foam polyethylene, its properties and application. 35 LDTP, L., 1973, p. 48 (prototype).