The method of obtaining low molecular weight polystyrene

 

(57) Abstract:

Usage: the invention relates to the chemistry of polymers and can be used to obtain a low viscosity of polystyrene, which finds wide application in the manufacture of electrophotographic developing compositions (toners). The inventive method of obtaining low molecular weight polystyrene by the polymerization of styrene at 84 110°C in aqueous suspension in the presence of a radical initiator and regulator of the molecular weight, as the regulator of the molecular weight of a mixture of Izmerov: 2,4-diphenyl-4-methylpentan-1,2,4-diphenyl-4-methylpentan-2 and 1,1,3-trimethylaniline in quantities of 1 to 3% by weight of the monomer, the mass ratio of the regulator and initiator support is equal to 0.67 1,5 1,0. table 1.

The invention relates to the chemistry of polymers and can be used to obtain a low viscosity of polystyrene, which finds wide application in the manufacture of electrophotographic developing compositions (toners).

Known methods for producing low molecular weight polystyrene, the technology of which is to conduct a radially-initiated polymerization of styrene with the addition of agents transfer circuit such as golojuch is unsuitable for use in some areas of technology, where the polymer of high purity.

The closest in technical essence and the achieved effect is a method of obtaining low molecular weight polystyrene, according to which it is obtained polymer with a low softening temperature when used as a regulator of the molecular weight of tetrabromphenol (TBPC) in the amount of 0.5 to 5.0% by weight of monomer [1]

The disadvantage of this method is the large variation of quality parameters of the finished product, the high toxicity of the process and finished product through the use of TBPC.

The technical task of the invention is the reduction of scatter indicators of the quality of the finished product, reducing the toxicity of the product and the polymerization process.

The technical result is achieved by conducting the polymerization of styrene in the presence of 1-3 wt. controller, representing a non-toxic mixture of isomers 2,4-diphenyl-4-methylpentene-1; 2,4-diphenyl-4-methylpentan-2 and 1,1,3-trimethyl-phenylindane in their mass ratio(0,52-0,40) (0,4-0,5) (0,08-0,10) accordingly, the mass ratio of the regulator and initiator maintained within the range of 0.67 to 1.5 1.0 to temperature change for 4-6aboutWith increasing the concentration rempah proposed ratios, technology method of producing polymer complicated by significant fluctuations in the rate of polymerization. This is the reason for the increase of the variance with regard to the quality of the finished product.

P R I m e R 1. For testing the raw materials used:

1. Styrene GOST 10003-81 with ISM. 1.

mass fraction of styrene at least 99.6-99.8% of

mass fraction of polymer absence

the basicity of the n/b, mg HCl/g of styrene,

mass fraction of p-tert-butylpyrocatechol not more than 0.001%

2. Benzoyl peroxide GOST 14888-78 with ISM. 1

mass fraction of the main in the society not less than 95%

melting point 38-41aboutWITH

3. Mixture of isomers:

the formula of the linear isomers:

2,4-diphenyl-4-methylpentene-1 (52-40%)

CH3--

2,4-diphenyl-4-methylpentan-2 (40-50%)

CH3-=C

1,1,3-trimethylaniline (8-10%)

< / BR>
the refractive index of the mixture of isomers

ND251,5685-1,5715

density at 20aboutWith 0,980-0,992 g/cm3< / BR>
4. Magnesium sulfate as per GOST 4523-77 with a basic substance content not less than 99% alkalinity not more than 0.02%

5. The caustic alkali according to GOST 2263-79 brand RD liquid content of the basic substance is not less than 44%

6. Demineralized water:

hardness not more than Janie basic substance 30-35%

the content of sodium sulfate not more than 6 wt.

pH 7,5-8,5

8. Calcium carbonate GOST 4530-76:

the basic substance content not less than 98%

chlorides not more than 0.05%

In the reactor-polymerization with stirrer volume of 10 m3download: 12-15% solution of MgSO47H2O 350 20 l 3-5% solution of NaOH 300 200 l of demineralized water 2600 100 litres

The parameters of the obtained aqueous phase, the concentration of Mg(OH)20,22% to 0.3% concentration of MgSO47H2O 0,1-0,2%

pH 8-11

In the apparatus of the pre-mixing load: styrene 5500 l; benzoyl peroxide (in terms of dry weight) of 50-150 kg (1-3%); a molecular weight regulator 25,0-175 kg (0.5 to 3.5%).

After 30-40 min of mixing the oil phase is produced by its suspension in the aqueous phase by adding surfactants "Progress" 0.25 l and calcium carbonate 3-5 kg.

Then the device is sealed and conduct the polymerization at a predetermined temperature for 3-6 h, and then incubated 100-110aboutC for 1-3 h

The finished product is analyzed for indicators:

softening temperature (using the ring and ball)

the melting point (capillary tube),

the ratio of viscosities (viscometric).

The results are shown in the table.

P R and Modact shown in the table.

P R I m e R 3. Analogously to example 1, the amount of the mixture of isomers of 2% benzoyl peroxide 2.0% temperature polymerization 90aboutC.

P R I m e R 4. Analogously to example 1, the amount of the mixture of isomers of 2% benzoyl peroxide 1.5% temperature polymerization 94aboutC.

P R I m e R 5. Analogously to example 1, the amount of the mixture of isomers 3% benzoyl peroxide 3,0% temperature polymerization 92aboutC.

P R I m e R 6. Analogously to example 1, the amount of the mixture of isomers 3% benzoyl peroxide 2.0% temperature polymerization 98aboutC.

P R I m e R 7 (control). Analogously to example 1, the amount of the mixture of isomers of 0.5% benzoyl peroxide 1.0% temperature polymerization 84aboutC.

P R I m e R 8 (control). Analogously to example 1, the amount of the mixture of isomers of 3.5% benzoyl peroxide 3,0% temperature polymerization 84aboutC.

The table shows that in comparison with the prototype, the proposed method (examples 1-6) is a high homogeneity of the basic characteristics of the product: T 1,5aboutWith the method of the rings and the ball, T2aboutWith capillary andRel0,02. The rate of polymerization varies 13,5-15,5/h, which ensures the normal heat removal exothermic reaction. The data in 2-5 RA and obtain polymer eliminates the risk of increasing the toxicity of the finished product.

The METHOD of OBTAINING low MOLECULAR weight POLYSTYRENE by the polymerization of styrene in aqueous suspension in the presence of a radical initiator and regulator of the molecular weight at 84 110o, Characterized in that as the regulator of the molecular weight of a mixture of isomers 2,4-diphenyl-4-methylpentan-1,2,4-diphenyl-4-methylpentan-2 and 1,1,3-trimethylaniline in quantities of 1 to 3% by weight of styrene in a mass ratio 0,52 0,40 0,4 0,5 0,08 0,10 accordingly, the mass ratio of the regulator and initiator maintained within the range of 0.67 to 1.5 to 1.0, and by increasing the concentration of the regulator 30% of the temperature increase on 4 of the 6oC.

 

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