A method of obtaining self-extinguishing polystyrene

 

(57) Abstract:

Use: receive foaming self-extinguishing polystyrene, used for the manufacture of insulation boards and soft packaging. The inventive method allows to reduce the time-extinguishing, to increase the melt index and the relative viscosity of polystyrene by block polymerization with subsequent suspension polymerization in a suspension stabilizer in the presence of an initiator and a mixture of flame retardants. A mixture of flame retardants contains tetrabromphenol and tennispalatsi, taken in a mass ratio of 4 : 1 to 1 : 1, respectively. table 1.

The invention relates to plastics industry, in particular the production of self-extinguishing polystyrene, which is widely used for the manufacture of heat-insulating plates in the construction and soft packaging.

Known methods for producing self-extinguishing polystyrene, in which the flame retardant used halogenated components in the amount of 0.2 - 15 wt.% depending on the method of administration [1].

A disadvantage of known methods is that the use of these flame retardants known in the combinations and quantities causes mustache is - C.

Recently used as synergists waxy halogenated and not halogenated paraffins, which improves the fluidity of the polymer during combustion.

A method of obtaining self-extinguishing polystyrene, whereby to reduce the time of drying of the polymer as a flame retardant, a mixture of tetrabromphenol (TBPC) and triarylphosphite, taken in a mass ratio of 0.47:1 to 2.5:1, in the amount of 0.5 - 1% by weight of styrene [2] the prototype.

The disadvantage of this method is the high time-extinguishing polymer 1 - 6 and low melt index compared with the polymer obtained in industrial flame retardant TBPC.

Object of the invention is to provide such a method of obtaining polystyrene, which will allow to reduce time of self-extinguishing polymer when making it from the flame and increase the melt flow without reducing the molecular weight of the polymer.

This is achieved by the fact that, as a flame retardant, a mixture of TBPC and three-(n - nonylphenyl)phosphite - (TNF), taken in a mass ratio of 4:1 to 1: 1, in the amount of 0.5 to 0.6% by weight of styrene.

The proposed method of producing self-extinguishing polystyrene allows the molten polymer without reducing the rate of polymerization and molecular weight of the polymer. It is not only explains the synergistic effect of extinguishing combustion, but also improves the conditions of processing of the polymer in penisgay due to the softening. This increases the processing productivity, reduced energy consumption, improved sintering products.

This effect is due to the fact that in contrast to the known method in the proposed method as a synergist used three-(n-nonylphenyl)-pofit, which is an effective thermo stabilizer of many polymers and used for this purpose in different quantities and with other substances.

Identified additional effect in mixture with TBPC at a certain ratio makes it possible to achieve a positive result. Changes in the concentration of components outside of the proposed relationship leads to the loss of the achieved effect. So, when the concentration of TNF below the lower limit is not achieved the desired effect on samostojatelnosti, and with increasing TNF above stated limits almost twice reduced the speed of the polymerization process, which is also undesirable. Not achieved this and when to use each component separately, even much of Valenzuela - GOST 14888-78 with ISM. N 1.

TBPC - TU 6-22-3-76 with ISM. N 3.

TNF - TU 6-02-680-89.

Polyvinyl alcohol (PVA or solar) - GOST 10779-78.

Isopentane run - TU 38-10149-79.

Demineralized water, the hardness is not more than 0.02, mgecw/L.

Example 1.

In the reactor-polymerization with stirrer volume of 10 m3download marketed 4 367 kg of styrene, 262 kg of demineralized water, marketed 4 367 kg peroxide benzene. Terpolymerization carried out at a temperature of 74 - 78oC until the conversion of monomer 35 - 40%, after which the prepolymer is injected 873,5 kg of demineralized water with t = 20 - 30oC, stirred for 15 to 20 minutes, enter 24 kg of benzoyl peroxide, 17,468 kg (0.4% by weight of styrene) TBPC and 4,367 kg (0.1% by weight of styrene) TNFF. Then add 873,5 kg of demineralized water containing 8,755 kg of Solwara, 305,7 kg isopentanol faction, and conduct the polymerization in suspension at t = 802oC 6 h and at t = 105oC 7 h After cooling, the polymer beads are separated from the aqueous phase by centrifugation and dried in the dryer fluidized bed. The finished product is analyzed according to OST 6-35-202-83 with ISM. 1, 2, 3. The melt index is determined according to GOST 11645-73 when a load of 10 kg and a temperature of 170oC. the Results are shown in the table.

Example 2. Analogously to example 1.

To the,3 wt.%, TNF - 0.3 wt.%.

Example 4 (control). Analogously to example 1.

The number TBPC - 0.3 wt.%, TNF - 0.1 wt.%, below the lower limit.

Example 5 (control). Analogously to example 1.

The number TBPC - 0.3 wt.%, TNF - 0.5 wt.%, above the upper limit.

Example 6 (control). Analogously to example 1.

As a flame retardant is used only TBPC in the amount of 0.55 wt.%.

Example 7 (control). Analogously to example 1.

As a flame retardant is used only TNF in the amount of 1.0 wt.%.

Data presented in table show that the proposed method (examples 1 to 3) compared with the prototype (see table description of the invention A. C. N 519427) time-extinguishing, 1 - 6 times less, a melt index higher. The speed of the suspension polymerization, mass fraction of residual monomer and the composition does not change compared with the polymer obtained in industrial flame retardant (see example 6), which concerns the relative viscosity, it is in the proposed method even higher.

Lowering the concentration TNFF below the lower limit (see example 4) time-extinguishing increases to 3, and at higher concentrations, overzeese the residual monomer content in the polymer up to 0.23% in comparison 0.11 - 0.12% in the proposed method.

When using one of the components individually, even with a significant increase in the concentration (examples 6 and 7) is not achieved effect on samostojatelnosti or melt index that characterizes the effectiveness of the proposed mix.

A method of obtaining self-extinguishing polystyrene by suspension polymerization of styrene in the presence of the initiator is benzoyl peroxide, styrene prepolymer, stabilizer suspension and the mixture of flame retardants containing tetrabromphenol, characterized in that the prepolymer get in the presence of initiator in an aqueous medium at a temperature of 74 - 78oC to the conversion of styrene and 35 to 40%, the suspension polymerization is carried out in the presence of pore-forming - isopentanol fraction at a temperature of 80 - 105oC, and as a stabilizer suspension use of 0.2% aqueous solution of polyvinyl alcohol, the mixture of the flame retardant further comprises tennispalatsi when the mass ratio of tetrabromphenol to triarylphosphite 4 : 1 to 1 : 1 in the amount of 0.5 to 0.6% by weight of styrene.

 

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