CZ260693A3 - Process of suspension polymerization of vinyl chloride - Google Patents

Abstract

The invented Suspension polymerization and/or copolymerization process of vinyl chloride being carried out discontinuously in polymerization reactors with a reflux condenser for removal of a portion of polymerization heat is stabilized by stabilizer solutions or a mixture of stabilizer solutions based on cellulose ethers, from which at least one amounting to 1 to 60 percent by weight from the total amount of stabilizer has opalescence point temperature higher than 70 degC. Salts of unsaturated fatty acids and polyvalent metals are used as grain porosity regulator.

Description

The invention relates to slurry polymerization or copolymerization of vinyl monomers carried out batchwise in polymerization reactors equipped with a reflux condenser to remove some of the polymerization heat. The resulting polymer is characterized by improved qualitative and utility properties.

Process for suspension polymerization of vinyl chloride

Suspension polymerization of e.g. vinyl chloride is generally carried out under pressure in stirred polymerization reactors, where the released polymerization heat is dissipated both by cooling the reactor jacket with a cooling medium, and in some cases with a reflux condenser.

In suspension polymerization, the monomer is dispersed and stabilized in water by means of macromolecular dispersants, such as cellulose ethers, partially hydrolyzed polyvinyl acetates, or polymers. combinations thereof. One characteristic of these dispersants is the turbidity temperature, i.e., the temperature above which the precipitation of the dispersant occurs, thereby reducing its efficiency. Commonly used dispersants (stabilizers) have a cloud point below 65 ° C.

In the dopolymerization of a monomer such as vinyl chloride, which takes place at a temperature higher than the cloud point of the dispersants used (e.g. S-PVC with a K-value of 55-50), or in polymerization technology which, in order to increase conversion, With the use of a reflux condenser to remove reaction heat, a portion of the vaporized and condensed monomer cannot be sufficiently stabilized due to the precipitation of a portion of the stabilizers at a higher temperature. This negatively affects the quality of the resulting polymer, especially the formation of larger amorphous particles, impaired flowability, reduced bulk density ev. inhomogeneous particles may occur during processing. Some technologies solve this problem by blocking the reflux condenser function for part of the polymerization time.

To improve the inner grain structure of the polymer, so-called porosity regulators (emulsifiers or secondary stabilizers) are used in the polymerization. These may be nonionic surfactants such as esters of higher fatty acids with sorbitan, glycerides of higher fatty acids and the like. Preference is also given to using salts of unsaturated fatty acids with cations of divalent and polyvalent metals formed in situ, which favorably influence the shape, size and pore distribution of the polymer grain.

The invention solves the above problems by introducing a multi-component stabilization system, wherein at least one of the stabilizers used has a cloud point above 70 ° C and the concentration of the stabilizer is at most 50% and at least 1% of the total amount of stabilizers (preferably 20-40%). ). Possible negative effect of the presence of this stabilizer on the internal grain structure; % of the polymer may be eliminated by increasing the concentration of the unsaturated fatty acid based poresir regulator.

Examples

1.) 450 L of demineralized water was metered into a 1-volume polymerization reactor equipped with a stirrer and reflux condenser and 12.5 kg of cellulose derivative solutions as stabilizers were added. Of this, 40% stabilizer with a cloud point of about 45 ° C and 50% with a cloud point of 65 ° C were further dosed: 0.4 kg of a solution of a mixture of unsaturated fatty acids (ΚΙΊΚ), 0.52 kg of initiator (org. Peroxyd) . 0,2 kg of solution 'θ' ¹

Ca (OH) ₉ and 0.01 kg of antioxydant. After dosing, the reactor was subjected to inertization, further evacuated and after tightness of the vacuum test was dosed.

340 kg vinyl chloride. After heating the reactor with jacket, polymerization was started at 52 + 0.5 ° C. After the polymerization was completed in 220 min. The residual monomer was then degassed by pressure and vacuum and the remaining slurry was subjected to dc monomer stripping by direct steam at a temperature of max. 95 ° C. The demonomerized suspension was then centrifuged and sieved in a jet and fluidized bed drier.

The resulting product exhibited the following parameters:

K value - 63.7; bulk density 0.45 kg / dm; sieve analysis: sieve 0.25 mm 0.4 0.160 mm 3.5%; 0.100 mm

71.6%; 0.053 mm 13.2% and less than 0.053 mm 5.2%; plasticizer absorption time (AS) - 10 min., fish eye (PO) 1 pc / g.

2.) Polymerization process and equipment as in Example 1.) except that 12.3 stabilizer solution was metered, of which 40% with a cloud point of 45 ° C, 30% with a cloud point of 65 ° C and 30% with a cloud point temperature of 75%. The resulting product had the following parameters:

K - 53.5; bulk density 0.504 kg / dm ⁰ ; sieve 0.250 mm 0.1%; 0.160 mm - 13.1%; 0.100 mm 77.2%; 0.053 mm 4.3%; less than 0.063 mm 0.3%; time AZ - 12 min .; number of RO - 1 pcs / g.

3.) Procedure, equipment and composition of stabilizers as in Example. 2.); KMK increased by 20% from 0.4 kg to 0.5 kg of solution.

Analysis of results. Product:

K - 59.0; bulk density 0.494 kg dm; screen 0.250 mm - 0.2%; 0.150 mm - 20.5%; 0.100 mm - 75.5 2; 0,063 r.

- 3.2%; less than 0.053 mm - 0.3%, AZ time 9 min .;

PO - 1 pc / g.

4.) Procedure, equipment and concentration ΠΜΚ same as Example. 3.). The stabilizer concentration remains

12.3 kg per batch, composition changes to: 40% stabil. with a turbidity temperature of 40 ° C; 15% with a turbidity temperature of 65 ° C and 40% with a turbidity temperature of 75 ° C.

Analysis results:

_ 3

K - 59.7; bulk density 0.526 kg / dm; screen 0.25 mm-1.5 S; 0.160 mm - 54.3%; 0.100 mm - 44,%;

0,063 mm - 0,2% and less than 0,063 mm - 0%.

Time AZ - 10 min., Number of K0 - 6 pcs / g.

Procedure, equipment and concentration of NMC as in Example 3.). The stabilizer concentration is reduced to 11.5 kg of solution per batch, the composition changes to 35% stabilizer and a turbidity temperature of 45 ° C, 43% with a turbidity temperature of 55 ° C and 22% with a turbidity temperature of 75 ° C.

The resulting product is of quality:

TO - 69.9; bulk density 0.485 kg / dm ^-5 , screen 0,25 mm - - 0,1%, 0.160 mm - 8.7%; 0.1 rum - 77.5%; 0,063 mm- - 13.4% and less than 0.063 mm - 0, r% · time 2 tZ - 10 min. , after platoon KO - 1 pc / g.

6.) Technological equipment and procedure is the same as in point 1.). 430 L of DV is metered in, 11.8 kg of stabilizer solution consisting of 40% stabilizer with a turbidity temperature of 45 ° C and 50% with a turbidity temperature of 55 ° C are added. Furthermore, 0.014 kg of NUK solution 0.275 kg of dilauroyl peroxide and 0.185 kg of dicetylperoxide dicarbonate, 0.2 kg of solution of O 3 / 0.1 kg of Ca (OH) 2, and 0.01 kg of antioxydant. Then dosed 350 kg VCM.

The polymerization temperature was G5 + 0.5 ° C, the dopolymerization was carried out at 82 ° C.

K - 59.0; bulk density 0.580 kg / dm; sewing analysis:

screen 0.25 mm - 2.2%; 0.16 nm - 26.4%; 0.1 mm - 63.5%; 0.063 mm - 7.6% and less than 0.063 mm -0.3%; time AZ - 21 min., number R0 - 2 pcs / g.

Equipment, procedure and recipe as in point 6.). The total amount of stabilizer is 11.8 kg solution per batch with a composition of 40% and a haze temperature of 45 ° C;

% with a haze temperature of 65 ° C and 20% with a haze temperature of 75 ° C.

Achieved quality:

K - 53.2; bulk density 0.615 kg / dm; lysis: 0.250 mm - 0.2%; 0.160 mm - 18 - 67.5%; 0,063 mm - 12,5% and less than time AZ - 23 min., Number R0 - 2 pcs / g.

with:

fi tova anaξ; 0.100 mm

0,05:

1.4

Claims (1)

SUMMARY OF THE INVENTION The present invention provides a process for the polymerization or copolymerization of vinyl monomers, preferably vinyl chloride, carried out batchwise in polymerization reactors provided for the removal of a portion of the polymerization heat by a reflux condenser, which runs throughout the process, respectively. for a part of the polymerization time, respectively. Dopolymerization at a temperature above 65 ° C, characterized in that solutions or mixtures of stabilizer solutions are used as primary stabilizers, at least one of which in the amount of 1-60% (preferably 20-40%) of the total amount of stabilizers has a point temperature turbidity greater than 70 ° C, and salts of unsaturated fatty acids with cations of two or polyvalent metals prepared are used as grain porosity regulator; in situ during the polymerization reaction taking place in an alkaline medium.