Method of producing heat stabilisers for chlorine-containing polymers

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of making heat stabilisers for chlorine-containing hydrocarbons, specifically to a method of obtaining stearates of bivalent metals used in polymer compositions based on chlorine-containing polymers such as polyvinyl chloride, vinylchloride copolymers, chlorinated polyvinylchloride etc. The method of producing heat stabilisers of chlorine-containing hydrocarbons involves reacting stearic acid and oxides or hydroxides of calcium, zinc, barium, magnesium or lead in form of separate of mixed salts of stearic acid in a solid phase with intense stirring. The process is carried out in the presence of sodium hydroxide or potassium hydroxide in amount of 0.05-0.15% of the mass of stearic acid and propylene carbonate or dimethylformamide, or hexamethapol or sulfolane or dimethylsulfoxide in amount of 0.005-0.05% of the mass of stearic acid at 40-95°C in a double-screw reactor. Catalysts of the process - sodium hydroxide or potassium hydroxide and propylene carbonate, or dimethylformamide, hexamethapol, sulfolane or dimethylsulfoxide facilitate considerable increase in activity of the surface of the substrate and, as a result, increase in the rate of the process and obtaining products in form of a homogeneous highly dispersed powder and prevention of secondary oligomerisation of the end product.

EFFECT: use of the invention enables design of a continuous highly efficient method of producing heat stabilisers of chlorine-containing polymers with high heat stabilising capacity due to formation of products in form a homogeneous highly dispersed powder.

2 cl, 4 tbl, 15 ex

The invention relates to stabilizers of chlorinated hydrocarbons, in particular to a method of obtaining stearates divalent metals used in polymer compositions based on chlorinated polymers such as polyvinyl chloride, copolymers of vinyl chloride, chlorinated polyvinyl chloride and other

The stabilizers to prevent degradation of the polymer, which is manifested in the elimination of Hcl and education in macromolecules isolated and conjugated double bonds, crosslinking, degradation of chlorine-containing polymers such as during processing at elevated temperatures and during operation ready materials and products. The primary stabilizers include stearates of divalent metals (CA, Zn, Ba, Mg, Pb), which always contains almost all industrial formulations of polymeric compositions based on chlorinated polymers.

A method of obtaining salts of organic acids by the interaction of oxides of metals with organic acids, including stearic acid, at a temperature of 200-240°C. the Interaction of metal oxide and stearic acid is as follows:

2C₁₇H₃₅COOH+MeO→IU(R)₂+H₂O where Me is CA, Ba, Zn, Cd.

The process is conducted as follows. Acid, heated to the above temperature, gradually, porci the mi (avoid strong foaming) to introduce the metal oxides in the form of pastes in dehydrated flax oil (introduction of metal oxides in the form of pastes prevents their aggregation). The process is carried out to obtain a homogeneous reaction mass (Sorokin F and other Chemistry and technology of film-forming substances. - M.: Chemistry, 1981, s-400).

The disadvantage of this method is the high temperature of the process and, as a consequence, the impurity salts of organic acids of the products of thermal degradation and deterioration, the complexity of hardware design due to the necessity of the introduction stage of milling the metallic stearates to the desired sizes (up to 80% and above up to 2-4 μm) (K.S. K.S. Minsker, Fedoseeva GT Degradation and stabilization of PVC. - M.: Chemistry, 1972, 424 S.).

Closest to the present invention is a method of obtaining thermal stabilizers of polyvinyl chloride interaction of stearic acid and hydroxides of calcium, zinc, barium, under strong stirring process is carried out in the solid phase in the fluidized bed at a temperature of 25-30°C and the number of revolutions of the mixing device 1000-2000 rpm (Method of obtaining of thermal stabilizers of polyvinyl chloride. RF patent №2243243 C2, 7 SK 5/09, Appl. 20.03.2003, publ. 27.12.2004, bull. No. 36. Rizaev US and others)

The disadvantage of this method is the complexity of the technological design for organization of continuous process, the possibility of secondary aggregation particles of metallic stearates in the stages of selection of the finished product due to the presence of stagnant zones of the mixer.

The purpose of the invention is the development of a continuous method of obtaining individual and mixed salts of stearic acid - stabilizers chlorine-containing polymers, the simplification and cheapening of the process, the performance increase due to the organization of production in continuous mode, the expansion of the range of the products of individual and mixed salts of stearic acid, the improvement of the quality.

This objective is achieved in that the process is carried out by reacting equimolar proportions of stearic acid with oxides and/or hydroxides of Zn, Ca, Mg, Ba, Pb, or mixtures thereof in the presence as catalyst of 0.05-0.15% of caustic soda or caustic potash and 0.005 to 0.05% by weight of stearic acid, propylene carbonate, or dimethylformamide, or hexadecapole (hexamethylphosphoramide), or sulfolane (tetramethylsilane), or dimethyl sulfoxide (DMSO) at a temperature 40-95°C. and a residual pressure of from 40 to 60 kPa at intensive mixing in twin-screw reactor.

The set of essential features ensures the achievement of the goal, namely the creation of a continuous high-performance method of obtaining thermal stabilizers chlorine-containing polymers individual and mixed salts of stearic acid with high " oven " ability due clicks the education products in the form of a homogeneous fine powder. The catalysts caustic soda or caustic potash and propylene carbonate, or dimethyl formamide, or hexameter, or sulfolane, or dimethylsulfoxide contribute to a significant increase in the activity of the surface of the substrate and, consequently, increase the speed of process and receipt of the products in the form of a homogeneous fine powder and to prevent the secondary agglomeration of the target product.

The invention is illustrated by the following examples:

Example 1

Example 1 shows the General methodology and description of twin-screw reactor (see drawing).

Twin screw reactor consists of three main components:

1) working part - two parallel spaced vzaimostsepljaemost of the screw 1, is placed in a sectional casing; augers consist of a shaft with mounted screw elements made of stainless steel 18CR10NITI. The inner part of the housing in contact with the material is also made of stainless steel AISI 18CR10NITI. External parts do not have contact with the reaction medium, made of carbon steel 3.

2) Drive screw reactor consists of the engine 2, the variator 3, gear 4 and razdvoilas 5. Between the drive and the working part of the installed clutch. Resouses pin protects the machine from exceeding the maximum allowable torque. The drive and the working hour is ü mounted on a common base, made of carbon steel.

To drive the screw reactor used:

- motor brand AOL 2-11-6, n=910 rpm, N=1.4 kW;

- variable VI IB-131-01 with the number of revolutions of the input n=1420 rpm, output n_min=344 rpm, power consumption N_min=0,7 kW; N_max=1,1 kW;

- gearbox CO-100-31,5-21 To with a transmission ratio of i=31,5.

3) thermostat 6 and the flexible hoses 7 are used for heating the reaction zone. In sections of the reactor can be maintained the same or different temperature. Each section has a fitting for input 8 and output 9 of the carrier and the socket to measure the temperature on the outer wall of the housing. Workshops have an outside insulation of asbestos cord.

Technical characteristics of the installation:

1. Capacity, kg/h in 4.3 (n=10 rpm).

2. The reaction volume (theoretical) - 0.54 DM³.

3. The residence time of material in the reaction zone - max 22,5 minutes

- min 7,5 min

4. Coolant - water and steam.

5. The frequency of rotation of the augers - 5...23 rpm

Main dimensions:

The total length of the working part and the drive - 1920 mm, maximum height (drive) - 550 mm, maximum width (drive) - 390 mm, the length of the drive - 970 mm, body length - 750 mm, height working part - 340 mm, width working part - 190 mm, number of sections - 5, the length of each section is 150 mm, the diameter is of neki - 50 mm, the pitch is 10 mm, the depth of the channel is 5 mm

For preparation of the complex catalyst is used NaOH according to GOST 2263-79, CON GOST 9285-78, dimethylformamide beyond 6-09-3720-79, propylene carbonate, sulfolane, hexadecapole, DMSO - brand HC (reagents).

50 kg (0.18 mol) of stearic acid (acid number 201 mg KOH/g), 6,7 kg (0.09 mol) of calcium hydroxide, 0.1 kg of NaOH, 0.01 propylene carbonate are mixed in a mixer without heating, and then the mixture was fed to the twin screw reactor, where the temperature of the zones: zone 1 - 30-40°C, zone 2 - 50-60°C, 3 zone - 70-80°C, 4 zone 90-95°C. in the discharge area is supported by the residual pressure of 40 to 60 kPa. At the exit of the reactor, the acid number of the finished product is not more than 0.45 mgKOH/g

Acid number, electrical conductivity, mass fraction of residue during sifting, the mass fraction of water was determined by THE 6-09-17-317.

Time thermal stability of the polymer compositions was determined according to GOST 14041-91 at 175°C, the melt flow index according to GOST 11645-73.

Examples 2-15. Syntheses carried out analogously to example 1, the composition of the reaction mixture, the characteristic of the stabilizers shown in table 1. For reference, here is the stabilizer obtained in example 1 prototype, which is closer in composition to declared.

The test results of stearates the divalent mellow as stabilizers in unplasticized formulations based on PVC and chlorinated PVC, as well as in the formulation of a polyvinyl chloride film marks "HE" is given in tables 2-4.

1. The method of receiving stabilizers of chlorinated hydrocarbons by the interaction of stearic acid and oxides or hydroxides of calcium, zinc, barium, magnesium or lead in the form of individual or mixed salts of stearic acid in the solid phase under vigorous stirring, and the process is carried out in the presence of caustic soda or caustic potash 0.05 to 0.15% by weight of stearic acid and propylene carbonate, or dimethylformamide, or hexadecapole, or sulfolane or dimethyl sulfoxide in an amount of 0.005-0.05% of the t mass of stearic acid at a temperature 40-95°C. in a twin-screw reactor.

2. The method according to claim 1, characterized in that the interaction of stearic acid is carried out with the oxides of Mg, Pb.