The method of producing polystyrene

 

(57) Abstract:

Use: manufacture of plastics, namely suspension of polystyrene. The inventive method of producing polystyrene by polymerization in suspension at a temperature of 85-90oC at a pressure of 525-700 mm RT.article in the presence of initiator and stabilizers suspension when the mass ratio of water:monomer, 0.5-0,33 with the subsequent introduction of demineralized water in the amount of 4% by weight of the aqueous phase, the pressure increases up to 1-1,5 ATM and temperatures up to 130oC. 1 table.

The invention relates to plastics industry, namely to obtain polystyrene polymerization of polystyrene suspension.

Known methods for producing polystyrene polymerization in suspension, in which the ratio of water: monomer is maintained in the range of from 1 to 4 (encyclopedia of polymers, M. 1977 T. C. page 569). For small values of this ratio better use the capacity of polymerizate, reduces the amount of wastewater. The decrease in the ratio is due to the deterioration of the heat sink and comquest reaction mixture.

However, in the known methods of obtaining a suspension of polystyrene without the formation of lumps achieved MinoC, a pressure of 1-2 .5 ATM. Heat carried by the cooling water in the jacket of the reactor (Process the production of a suspension of polystyrene N 46a, , Gorlovka, Donetsk region, the validity of 27.06.98, prototype).

When receiving a suspension of polystyrene on the prototype and the decrease in the ratio of water: monomer to 0.5 is the clumping reaction mixture, and further reduction in the ratio leads to agglomeration of the reaction mass.

The aim of the invention is to find a method of suspension polymerization of polystyrene, which can increase the volume of product per unit of equipment by decreasing the amount of sewage.

The purpose is due to the fact that when the suspension polymerization of styrene in the presence of initiator and stabilizers suspension support mass ratio of water:monomer, 0.5-0,33, the vapor pressure 525-700 mm RT. Art. and the temperature of 85-90oC until the conversion of monomer 90-95% with the subsequent introduction of demineralized water in the amount of 4% by weight of the aqueous phase, the pressure increases up to 1-1,5 ATM. and temperatures up to 130oC.

The proposed method of producing a suspension of polystyrene allows for a 20% increase in the yield calculation, in contrast to the known, the proposed method at the time of the gel effect the polymerization reaction proceeding with sawtoothed heat, heat is carried out by evaporation of the reaction mixture. Given the mass ratio is restored by the introduction of demineralized water in the reaction mixture. It provides carrying out suspension polymerization at a substantially reduced mass ratio without clumping products.

For conducting experiments using raw materials:

Styrene GOST 10003-81 with ISM. N1: mass fraction of polymer absence, the basicity of the n/b 0,001 HCl/g mass fraction of p-tributylphosphine n/b 0,001%

Peroxide benzene GOST 14888-78 with ISM. N1: mass fraction of peroxide-nm 98.2% of mass fraction of water 25-30% mass fraction of chlorine n/a ± 0.3%

Tertbutylbenzene THE 6-05-1997-85: mass fraction of the main substances - n/m 98.2% of mass fraction of active oxygen n/m 8,1%

Demineralized water STF 113-03-04-0315-84: stiffness n/b 0,02 mg mEq/l, chloride n/b 3.55 mg/g, pH 5.5-7.0.

Caustic soda GOST 11078-78: mass fraction of the main substances n/m 94%

Magnesium sulfate as GOST 4523-77: mass fraction of the main substances n/m 99%

Secondary acesulfam sodium (detergents "Progress") - TL3-polymerization with stirrer load (the weight.h.): the aqueous phase 33,0, styrene 100 (ratio of water:monomer 0,33). The aqueous phase contains magnesium hydroxide 0.7 to 0.9 weight. including magnesium sulfate 0.3 to 0.4 weight.h. secondary alkylsulfate sodium 0,007 weight.h. Styrene contains benzoyl peroxide - 0.24 weight.h. tertbutylbenzene 0.06 weight.h. The polymerization reaction mixture is conducted at a temperature of 85oC for 6 h and a pressure of 525 mm RT.article to conversion of 90% then injected into the reactor demineralized water in an amount of 4% from the aqueous phase, the pressure is raised to 760 mm RT.article and the reaction mixture is heated to 130oC for 1.5-2 h, the pressure in polymerizate rises up to 1-1,5 ATM, when 130oC the process is conducted within 2 hours

After completion of the polymerization cycle the finished product is separated from the aqueous phase in the centrifuge, record the presence of lumps, dried at a temperature of 80oC and determine the relative viscosity viscosimetrically, the residual monomer content in the chromatograph. Calculate the output of one operation in tons and the volume of wastewater per 1 ton of product in 1 m3. The results are shown in the table.

Example 2. Analogously to example 1. The mass ratio of water:monomer is equal to 0.37, the temperature until conversion of 95% support 90oC.

Example 3. Analogously to example 2. M is logical to example 2. The mass ratio is equal to 0.5, to conversion of 35% support pressure 760-1200 mm RT. Art. demodu not enter.

Example 5 (prototype). Analogously to example 1. The mass ratio is equal to 0.6, the pressure on the first tread to the conversion 90,0% support 760-1200 mm RT. Art.

The data (table) show that the proposed method (examples 1-3 compared with the prototype (example 5), achieved an increase of yield from one operation from 0.5 to 0.6 t, the amount of waste water per 1 ton of product decreased from 0.6 to 0.33 m3without changing the qualitative indicators of the finished product.

In the case of decreasing mass ratio in comparison with the prototype to 0.5 without changing the mode in accordance with the claimed method (example 4) is the clumping reaction mixture.

The method of producing polystyrene by suspension polymerization of styrene under pressure in the presence of initiator and stabilizers suspension at 85 - 130o, Characterized in that the polymerization is carried out at a mass ratio of the water monomer 0,5 0,33, the vapor pressure of 525 700 mm RT.article and a temperature of 85 90oTo achieve the conversion of monomer and 90 to 95% with the subsequent introduction of demineralized water in the amount of 4% by weight in the

 

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