RU2295541C1 - Method for preparing synthetic gutta-percha - Google Patents

Abstract

FIELD: chemistry of polymers, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of polydienes on titanium-magnesium catalysts and can be used in synthesis of synthetic gutta-percha. Synthetic gutta-percha is synthesized by polymerization of isoprene in aliphatic solvent medium in the presence of catalytic system consisting of titanium-magnesium catalyst and co-catalyst representing trialkylaluminum. Titanium trichloride co-crystallized with magnesium dichloride is used as titanium-magnesium catalyst. Catalyst is prepared by interaction of magnesium with titanium tetrachloride in the presence of n-butyl chloride at 60-100°C, in the volume ratio titanium tetrachloride : n-butyl chloride = 1:(53-80) and in the content of magnesium 3.5-5.5 g per 1 ml of titanium tetrachloride. The polymerization process of isoprene is carried out at temperature 30-65°C, at the isoprene concentration in polymerization medium 1.0-2.0 mole/l and at the mole ratio co-catalyst : catalyst = 10-20, inclusively. Method provides carrying out the process for a single step and without washing out that simplified a method for synthesis of polymer that represents highly dispersed crumbs and reduces consumptions. Invention can be used in synthesis of synthetic gutta-percha.

EFFECT: improved method of synthesis.

4 cl, 2 tbl, 8 ex

Description

The invention relates to highly efficient metal complex catalyst systems for use in the (co) polymerization reactions of alpha olefins and conjugated dienes.

Synthetic gutta-percha - a highly regular trans-1,4-polyisoprene (TPI) at room temperature - is a thermoplastic crystalline polymer with a melting point of 60 ° C.

TPI is widely used in such fields of medicine as traumatology, orthopedics, reconstructive surgery, dentistry, in the manufacture of sports goods (for example, as a coating for high-quality golf balls), the shoe and tire industry, in the production of insulating materials, materials that can remember their shape etc. Mixtures of TPI with natural rubber (NK), styrene butadiene (SCS) and butadiene (BK) rubbers have a high processing ability and good mechanical properties.

TPI can be used as a new generation of material for the manufacture of high-quality tires. Cost-effective production of TPI is a very promising direction in the polymer industry.

Three well-known commercial companies, namely English firm «Dunlop C ^O", a Canadian firm «Polysar C ^O" and the Japanese firm «Kuraley With ^O", produced industrially from TPI 1960.

Currently, the used processes for the preparation of TPI do not allow for large-scale polymer production, primarily due to the low activity of the used catalysts (as a result, the manufactured products have a high cost). In addition, production is very environmentally unsafe: emissions of heavy metals into the environment (due to the need to wash out low-performance catalyst residues from the polymer), the use of environmentally unfavorable solvents, and a number of other negative factors. As a rule, vanadium-based catalytic systems are used for isoprene polymerization: VCl ₃ , VCl ₄ , VOCl ₃ (Natta G, Porri L. // A. Chim. Ind. (Milan), 1959, v.41, No. 116, p .398; Cooper W. // J. Polym. Sci. Part C: Polym. Symp., 1964, v. 4, p. 211; Lasky JS // IEC Prod. Res. Dev., 1962, v. 1, p. 82), as well as containing Ti (OR) ₄ (Mullagaliev IR, Monakov Yu. B. // Polymer Sci. (Russ.), 2002, v. 44, No. 12, p.2251; UK patent No. 1024179) , and the process itself is carried out in aromatic hydrocarbons.

Titanium-magnesium catalysts (TMK) are widely known in the world as catalysts for the polymerization of olefins (ethylene, propylene, alpha-olefins). Numerous methods for the preparation of TMK are described, the purpose of which is to create improved magnesium-containing, titanium-containing electron-donating catalysts. Known methods for producing TMC are multi-stage, requiring repeated washing of the excess reagents used and, therefore, a sufficiently large time for their preparation (RF patents No. 2152404; No. 2103277; No. 2127148).

A known method of producing polymers of conjugated dienes in the presence of a titanium-magnesium catalyst obtained by a multi-stage method (Mushina EA and others. Polymerization of dienes on titanium-magnesium catalysts. Vysokomolek. Soed., 1996, t. A 38, 3, p. -457).

Closest to the proposed invention is a known method for producing synthetic gutta-percha by polymerization of isoprene in an aliphatic solvent in the presence of a catalytic system consisting of a titanium-magnesium catalyst and a cocatalyst representing trialkylaluminium (RF patent No. 2196782). The process is carried out at a temperature of 45-50 ° C, the concentration of isoprene in the polymerization medium from 2.5 to 4.8 mol / l, the molar ratio of cocatalyst: catalyst from 22 to 30 mol / mol.

The catalyst used in the known method is prepared according to the following procedure.

Magnesium chips, solvent (heptane or hexane), n-butyl chloride (1/5 part of the total amount) and crystalline iodine are loaded into a reactor equipped with a stirrer, after which the temperature is raised to 65-70 ° C and gradually added (over 3 -4 hours) n-butyl chloride residue. After adding the entire amount of n-butyl chloride, the reaction is carried out for 4 hours with stirring at 65-70 ° C. After completion of the reaction and cooling of the suspension, the solvent is decanted and the precipitate (formed magnesium dichloride) is washed with a pure solvent from unreacted n-butyl chloride. Then, the resulting magnesium dichloride is poured with a solvent, and titanium tetrachloride is added to the reactor at 60-70 ° C with stirring. The application of titanium tetrachloride on magnesium dichloride is completed in 5-6 hours. The reactor is cooled, the solvent is decanted. The resulting titanium-magnesium catalyst (TMK) is washed from excess titanium tetrachloride, stored as a suspension containing 0.05 mol / L of titanium. The final product is titanium tetrachloride supported on magnesium dichloride.

The consumption of reagents for the preparation of TMK: magnesium - 8 g, titanium tetrachloride - 6 ml, n-butyl chloride - 110 ml, iodine - 0.4 g.

In a known manner get the polymer in the form of sticky crumbs, which reduces the manufacturability of the target product. Since the polymer production process includes the stage of preparation of the catalyst, the multi-stage preparation of the catalyst complicates the technology of the entire polymer production process and increases its energy consumption.

The technical task of the invention is to remedy these disadvantages.

The specified technical result is achieved by the fact that in the method for producing synthetic gutta-percha by polymerization of isoprene in an aliphatic solvent in the presence of a catalytic system consisting of a titanium-magnesium catalyst and a cocatalyst representing trialkylaluminum, titanium trichloride crystallized from magnesium dichloride is used as a titanium-magnesium catalyst obtained by the interaction of magnesium with titanium tetrachloride in the presence of n-butyl chloride at 60-100 ° C, volume ratio tetra titanium loride: n-butyl chloride 1: (53-80) and a magnesium content of 3.5-5.5 g per 1 ml of titanium tetrachloride and the isoprene polymerization process is carried out at 30-40 ° C, the concentration of isoprene in the polymerization medium is from 1.0 up to 2.0 mol / l (preferably 1.5 mol / l), the molar ratio of cocatalyst: catalyst is from 10 to 20, inclusive (preferably 20).

Any trialkylaluminum, preferably triisobutylaluminum (TIBA), is used as a cocatalyst.

The resulting polymer according to the invention is a finely divided crumb. Obtaining a catalyst goes in one stage, does not require washing, which simplifies the entire method of producing a polymer and reduces its energy consumption.

Examples 1-4. Synthesis of titanium-magnesium catalyst (TMK).

Ingredients are simultaneously loaded into a stirred reactor to obtain TMK, the process temperature is from 60 to 100 ° C (Example 1 - temperature 60 ° C, Examples 3, 4 - temperature 78 ° C, Example 2 - temperature 100 ° C). The resulting catalyst composition TiCl ₃ * nMgCl _{2 is} dried to obtain a powder containing from 1.36 to 2.40 wt.% Trivalent titanium.

The conditions for the preparation of the catalyst and its titanium content are presented in table 1.

Table 1 No. Mg, g TiCI ₄ ml N-BH, ml TiCI ₄ / H-BH (bulk) Mg, g / 1 ml of titanium Ti (III), wt.% In the catalyst one 3.6 0.9 54 1:60 4.0 2,36 2 12.0 3.4 180 1:53 3,5 2.40 3 12.0 2.2 175 1:80 5.5 1.36 four 24.0 4.4 350 1:80 5.5 1.36

IR spectral and X-ray diffraction studies of TMC were carried out. The IR spectrum of MgCl _{2 is} characterized by wide bands of 613 and 430 cm ^-1 belonging to the Mg-Cl terminal bonds, and bands in the region of 280 cm ^-1 and below belong to Mg-Cl bridge bonds.

In the IR spectrum of TMK, bands 451, 432, 417, 400, 361, and 343 cm ⁻¹ belong to TiCl ₃ , which has MgCl ₂ in the coordination sphere. A strong splitting of the bands indicates coordination of the components of the complex with each other.

X-ray diffraction studies of MgCl ₂ and TMK carried out on a DRON-3M diffractometer in the “pass through” survey mode showed that the scattering curve corresponding to MgCl ₂ in the angle range 2θ = 3.5-10 ° has a sharply decreasing character, and in the interval 10-16 ° on the x-ray there is a wide peak with maximums at 14.5 ° and in the range of angles 27-33 °. Such a picture is characteristic of highly dispersed systems such as nanoparticles. The curve corresponding to TMC practically coincides with the MgCl ₂ curve, which indicates the formation of TiCl ₃ during the preparation of the catalyst (the crystal structures of MgCl ₃ and TiCl ₃ are similar), i.e. on the preparation of a catalyst, which is titanium trichloride, co-crystallized with magnesium dichloride.

The possibility of obtaining a catalyst of such a structure, in one stage, without washing the product is provided by the selected process conditions (ratio of components, reaction temperature).

Examples 5-8. Obtaining synthetic gutta-percha.

The conditions and results are shown in table 2.

All operations for the preparation of the catalyst and the polymerization reaction are carried out in an inert gas atmosphere.

Polymerization of isoprene is carried out in metal reactors - 20-liter autoclaves.

A mixture containing 15-16 wt.% Of isoprene is loaded into a stirred reactor, then triisobutylaluminum and titanium-magnesium catalyst obtained in Examples 1-4 are introduced. The resulting product has the form of non-sticking finely divided chips.

table 2 No. of examples 5 6 7 8 Charge volume, l 12 8 fourteen 12 The titanium content in TMK, wt.% 2,36 2.40 1.36 1.36 Used TMK, example no. one 3 3 four The titanium content, mol / l * 10 ³ 0.5 0.5 0.15 0.5 Co-catalyst ratio: TMK, mol / mol 10 twenty 10 twenty Isoprene concentration, mol / L 1,5 1,5 1,5 1,5 Polymerization temperature, ° C thirty 40 thirty 40 The conversion of monomer, wt.% (For 6 hours) 95 90 85 90 The microstructure of polyisoprene, wt.%: 1.4 - trans 98 97 97 98 3,4- 2 3 3 2 The size of the crumb, mm 0.5-2.0 1.0-3.0 1.0-2.0 1.0-3.0

Claims (4)

1. The method of producing synthetic gutta-percha by polymerization of isoprene in an aliphatic solvent in the presence of a catalytic system consisting of a titanium-magnesium catalyst and a cocatalyst representing trialkylaluminium, characterized in that titanium trichloride crystallized with magnesium dichloride obtained from titanium-magnesium catalyst is used the interaction of magnesium with titanium tetrachloride in the presence of n-butyl chloride at 60-100 ° C, the volume ratio of titanium tetrachloride: n-butyl chloride 1: (53-80) and the magnesium content of 3.5-5.5 g per 1 ml of titanium tetrachloride, and the polymerization of isoprene is carried out at 30-65 ° C, the concentration of isoprene in the polymerization medium from 1.0 to 2.0 mol / l, the molar ratio of cocatalyst: catalyst from 10 to 20 inclusive. 2. The method according to claim 1, characterized in that the polymerization of isoprene is carried out at a concentration of isoprene in the polymerization medium from 1.5 mol / L. 3. The method according to claim 1, characterized in that the polymerization of isoprene is carried out at a molar ratio of cocatalyst: catalyst equal to 20. 4. The method according to claim 1, characterized in that triisobutylaluminium is used as a cocatalyst.