The method of producing polystyrene

 

(57) Abstract:

Usage: upon receipt of foam and suspension of polystyrene. The inventive method of producing polystyrene polymerization in aqueous suspension in the presence of a radical initiator and stabilizer suspension of partially saponified polyvinyl alcohol in an amount of 0.1 - 0.25. % and addition of sodium polyphosphate in an amount of 0.05 to 0.15% by weight of the aqueous phase, and polyphosphate sodium is introduced into the initial solution of the stabilizer. table 2.

The invention relates to plastics industry, and in particular to methods of producing foam and suspension of polystyrene polymerization in aqueous suspension.

It is known the use of polyvinyl alcohol (PVA) and natriumpyrofosfaatti in-water suspension polymerization processes (encyclopedia of polymer. M. 1977, so 3, S. 568-570; C. I. Beilin, S. C. Kusevitsky, I. E. Rentmeester. Production of expandable polystyrene M. niitekhim, 1985, S. 18-19). However, in the known methods use one of these types of stabilizers or nonionic stabilizer, which include PVA, or solid stabilizer in the form of water-insoluble fine powders with whom I [ Mg3(PO4)2The use of polyvinyl alcohol in a mixture with polysiloxane and other additives, the main purpose of which is to obtain a polymer with a homogeneous particle size distribution (State and prospects of development of production of EPS abroad. M niitekhim. 1978, S. 18-19). Pyrophosphates are widely used when receiving a suspension of polystyrene (Patent Germany N 2640999, CL CO 8 F 12/08, 1978).

There is also known a method of producing polystyrene by suspension polymerization of styrene using as a stabilizer of 0.001 to 0.4 wt. natriumpyrofosfaatti [1] those And other pyrophosphates are used as raw materials for the preparation of phosphates of calcium, magnesium or iron in stekhiometricheskikh quantities. The preparation of these stabilizers is carried out before the water-suspension polymerization in the preparation of the aqueous phase for carrying out the process. Moreover, the stabilizer is prepared with some excess of the second component, so a water-soluble salt of Nutripro(poly)phosphate in an aqueous-suspension medium during the polymerization process is missing.

The disadvantages of these methods are great losses of the polymer with the aqueous phase, separated the one phase fraction of polymer (emulsion polymer).

Closest to the present invention is a method of producing polystyrene polymerization in aqueous suspension, in which suspension polymerization of styrene is carried out in aqueous medium in the presence of polymerization initiators and stabilizers suspension. Upon receipt expandable polystyrene (block-suspension method), in which the polymerization is carried out in the presence of flame retardants. After completion of the polymerization cycle the product is separated from the aqueous phase by centrifugation or filtration. The filtrate is directed to the neutralization often by burning. Drying of the granules of the finished product is sent for screening to form, mostly 3-5 grades of the product by the size of the beads [2] as stabilizers suspension in this process is to apply an organic colloids: a partially saponified polyvinyl alcohol.

The disadvantage of this method is the formation in the polymerization process a large amount of polymer, it is difficult separated from the aqueous phase by known methods, which leads to a high concentration of polymer in the filtrate entering the neutralization, and, as a consequence, leads to the necessity of a complicated scheme of neutralization increases deadweight loss of polymer from the aqueous phase the polarization of the generated fractions of granules of the polymer, emerging sieving in a separate brands, which are of limited use. For example, mark N 5 (a byproduct, unfit to obtain polystyrene products OST 6-35-202-83 NCDs. N 1, 2, 3, S. 3).

The objective of the invention is to reduce losses of the polymer, reducing the formation of by-product credits, simplification of process waste water.

The technical result is achieved by the fact that the suspension stabilizer in the form of an organic colloid, specifically aqueous solution of partially saponified polyvinyl alcohol concentration of 0.1 to 0.15 wt. additionally contains Na5P3010or Na4P207H20 in quantities of 0.05 to 0.15% by weight of the aqueous phase. And (the last) of sodium polyphosphate with block-suspension polymerization process is introduced with the second portion of the aqueous phase, and when the suspension polymerization process in the original solution of the stabilizer.

The proposed method for polystyrene polymerization in aqueous suspension allows to reduce the loss of polymer from the aqueous phase, to reduce the release of brand N 5 (a byproduct, not suitable for derivation of EPS products, OST 6-05-202-83 with ISM. N 1, 2, and also to simplify the process, for example to exclude stage terpolymerization and to reduce the duration of the process.

This effect is due to the fact that in contrast to the known method, the presence of polyphosphate sodium in an aqueous solution of polyvinyl alcohol in the polymerization of styrene leads to the formation of a smaller amount of polymer, it is difficult to separate from the aqueous phase (presumably polymerizable by the mechanism of emulsion polymerization) due to a change in the hydrophilic-hydrophobic balance (the pH of the aqueous phase varies from 6-7 to 3-3 .5). This can explain the decrease of issue of the stamp N 5. The attempt to achieve a similar effect by known methods, for example by changing the concentration of polyvinyl alcohol in aqueous solution or reducing intensive mixing of the reaction mass, does not give the desired result, since on the one hand not achieved the same effect by reducing the formation of polymer, it is difficult to separate from the aqueous phase and reduction of output brand N 5, on the other hand the decrease in the concentration of the stabilizer reduces the stability of the emulsion against merging in the agglomerate and decrease the intensity of mixing does not provide heat removal the polymerization reaction.

new share styrene n/m 99,6 99,8%

mass fraction of polymer absence;

the basicity of the n/b is 0.0001 mg HCl/g;

mass fraction of p-tributylphosphine n/b 0,001%

2. Peroxide benzene GOST 14888-78 with ISM. 1 (PB)

mass fraction of water 25-30%

mass fraction of peroxide benzene in a dry product of n/m of 98.2%

mass fraction of total chlorine n/a ± 0.3%

including chlorine ions n/b 0.25% of

3. Peroxide Dicumyl (MAC)

mass fraction of the main substances n/m 95%

melting point 38-41oC.

4. Tert-butylperbenzoate THE 6-05-1997-85 (TBPB)

mass fraction of the main substances n/m 96,2%

mass fraction of active 02 n/m 8,1%

5. Hexabromocyclododecane THE 6-47-06-89 (HBCD)

mass fraction of bound bromine n/m 70%

the initial melting point of not lower than 175oC,

mass fraction of volatile substances n/b 0,65%

6. Tetrabromphenol THE 6-22-3-76 (TBPC)

the content of bromine in the side chain of 73.5%

the content of volatile substances n/a ± 0.3%

acidity n/a ± 0.1%

7. Polyvinyl alcohol GOST 107779-78, mark 18/11 (PVA)

mass fraction of volatile substances n/b 4,0%

dynamic viscosity of a 4% solution of 15-20 pas 103/cm;

the content of acetate groups of 10-14%

8. Isopentane run THE 101494-79, mark A (IPF)

mass fraction of sapanta the 02 mg EQ/l;

the content of chlorides n/b 3.55 mg/l;

pH 5,5 5,7.

10. Sodium tripolyphosphate, Na5P3010GOST 13493-86.

11. Pyrophosphate sodium Na4P207GOST 342-77.

Example 1. In the reactor-polymerization with stirrer volume of 10 m3download Mac. demineralized water from the total number l 60; styrene 100; peroxide benzene 0,3; peroxide Dicumyl 0,2; tertbutylbenzene 0,1; HBCD 0,85; Terpolymerization lead 762oC until the conversion of monomer 37-40% then enter to 0.04 wt. TBPC and finish terpolymerization when conversion of the monomer 44-45% In the prepolymer is injected 20 wt. demineralized water with a temperature of 20-30oC and 0.05 wt. Na5P3010, stirred for 15-20 min, then enter 20% of the aqueous phase in the form of a 1% aqueous solution of PVA, 7,0% isopentanol faction and conduct polymerization in suspension under stirring at 802oC 6-7 hours, ascent and endurance at 105oC-6 to 7 hours

Polymer beads are separated from the aqueous phase onto the belt vacuum filter, followed by centrifugation, dried, and scatter on the screens of continuous receipt of grades 1, 2, 3, 4, 5 in accordance with OST 6-05-202-83 (var. N 1, 2, 3). The aqueous phase separated from the beads, sent for incineration in a special pechyony type expandable styrene (polystyrene) type PSV-SV.

The number of losses of the polymer and the yield of product by brand are shown in table. 1.

Example 2.A method similar to example 1. The number of Na5P30100.1 wt. The quality of the finished product as good as the product in example 1.

The number of losses of the polymer and the yield of product by brand are shown in table. 1.

Example 3. A method similar to example 1. Instead of Na5P3010use Na4P20710 H20 in an amount of 0.1 wt. The quality of the finished product as good as the product in example 1. The number of losses of the polymer and the yield of product by brand are shown in table. 1.

Example 4. A method similar to example 1. The number of Na5P30100.15 wt. The quality of the finished product as good as the product in example 1. The number of losses of the polymer and the yield of product by brand are shown in table. 1.

Example 5. A method similar to example 1. Polyphosphate sodium is not introduced. The quality of the finished product as good as the product in example 1. The number of losses of the polymer and the yield of product by brand are shown in table.1.

When receiving a suspension of polystyrene method is illustrated by the following examples.

5P30100,05 wt. then loaded the styrene obsession peroxide benzene in the amount of 0.55% of the Stirring of the reaction mass is maintained with the speed of 560 rpm

The reaction mass is heated to 90oC for 1.5 h and then maintained at 90oC to the exhaustion of monometr. Polymer beads are separated from the aqueous phase by filtration, dried and scatter on the screens 2; 1; 0,5; 0,25 mm

The aqueous phase is separated from the beads, analyze the content of the polymer. The results are shown in table. N 2.

Example 7. The method is analogous to example 6. The number of Na4P20710 H20 is 0.1 wt. the amount of PVA 0.2 wt.

Example 8. The method is analogous to example 6. The number of Na5P30100.15 wt. the amount of PVA 0.2 wt.

Example 9. The method is analogous to example 6. The number of Na5P30100.1 wt. the amount of PVA to 0.15 wt.

Example 10. The method is analogous to example 6. The number of Na5P30100.1 wt. the amount of PVA 0.1 wt.

Example 11-13 (prototype). The method is analogous to example 6. Polyphosphate sodium is not introduced. The amount of PVA is 0.2; 0.15 and 0.1 wt. respectively. The number potesnivshaya polystyrene in the proposed method (table. 1, examples 1-4) compared to the prototype (table. 1, examples 5-5B) is the reduction of losses Palomera with 39,4 39,0 to 4.9 7.4 kg by reducing the concentration of Philomena in the filtrate from 8-13 1-1,5 g/l and does not form accompanying the product unsuitable for obtaining penopolistirolnyh products (brand N 5), while in the prototype specified product contains 0,55 1,5% Statistics show that, during production of the specified product is formed up to 5%

When receiving a suspension of polystyrene in the proposed method (table. 2, examples 6-10) compared to the prototype (examples 11-13) is achieved by reduction of losses polymer 0.11-5,2 to 0.008=0,026 g by reducing the concentration of polymer in the filtrate from 0.4 to 2.0 0.03 0.1 g/l concentration Reduction of Solwara from 0,2 0,1% (table. 2, an example 11-13) the desired result is not achieved. Further decrease in the concentration of Solwara impossible, because not ensured the stability of the suspension against clumping. Strengthening granules beads in examples 6-10 compared with example 11 shows that the proposed method can simplify the process by eliminating the stage of terpolymerization and reducing the duration of the process.

The decrease in the concentration of polymer in the filtrate to 0.03 g/l allows you to send the article is The method of producing polystyrene by suspension polymerization of styrene in aqueous medium in the presence of a radical initiator and a partially saponified polyvinyl alcohol as a suspension stabilizer, characterized in that the use of polyvinyl alcohol in an amount of 0.1 to 0.25%, and optionally sodium polyphosphate in an amount of 0.05 to 0.15% by weight of the aqueous phase, and polyphosphate sodium is introduced into the initial solution of the stabilizer.

 

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