CS232651B1 - Preparation method of polymers with reactive end functional groups - Google Patents

Description

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of reactive end-functional polymers by treating a living polymer with a functionalizing agent prepared by anionic polymerization in the presence of an organoalkal metal compound or an alkali metal initiator.

The functionalization is carried out at the same time kneading the mixture at a temperature of -30 to +80 ° C for at least 5 s. In particular, it is operated at a pressure of 0.1 to 4.0 MPa and the mixture is treated with a minimum energy of 15 W / kg. The advantage of the process is a better mixing of the polymer with the functionalizing agent and thus achieving a better chemical reaction of the components and the possibility to perform the functionalization at higher viscosities of the reactants and the resulting gel, which results in a reduction in the need for diluents.

The invention relates to a process for the preparation of end-functional polymers by treating a living polymer with a functionalizing agent, prepared by anionic polymerization in the presence of an organometallic compound or an alkali metal polymerization initiator.

By anionic polymerization of unsaturated compounds in aliphatic or aromatic solvents and ethers in the presence of initiators based on organometallic compounds or alkali metals, the so-called living polymers can be prepared from unsaturated compounds, for example from isadiene butadiene, alphamethylsyrene, styrene and others. at the chain ends of the reactive organometallic group.

These living polymers react with a variety of substances to convert the organometallic groups into reactive functional groups, such as carboxyl, hydroxyl, mercaptan, and others. Suitable functionalizing agents are, in particular, carbon dioxide, alkylene oxides, aldehydes, ketones, oxygen, sulfur and others.

The process of functionalization is chemically described in a number of publications, for example in VB 1 029 451, VB 921 803.

In the course of the functionalization reaction, carboxylic acid salts, metal alcoholates, mercaptides and the like are formed first, which associate in a low-polar environment and the solution suddenly turns into a gel. That causes . problems in the technological realization of the process of functionalization, because of the high degree of conversion of organometallic groups into functional groups. It is necessary to achieve a perfect dispersion of the functionalizing agent in the living polymer solution and suppression of unwanted side reactions by selecting suitable reaction conditions.

Therefore, the functionalization is carried out, for example, by mixing the stream of polymer solution with carbon dioxide in a tube shape. T, the carboxylation reaction being carried out on the contact of both components (U.S. 3,225,089). In practice, it is also common to carry out a functionalizing agent in a flow mixer on an injector and jet principle or in a centrifugal pump (VB 921 803). Similarly, spraying a stream of polybutadiene solution with a gaseous functionalizing agent is described.

Carboxylation by spraying a polymer solution has also been described. a rapidly rotating disk into the atmosphere of a gaseous functionalizing agent which was carbon dioxide (U.S. 3,227,701).

The resulting gel must then be destroyed by hydrolysis after addition of water or acid. In the processes described above, the resulting gel is collected at the bottom of the reaction vessel and hydrolyzed directly therein with water or acid, or discontinuously transported further to hydrolysis, washing, and isolation.

Common lack of the mentioned ways of functionalization. there is a need to reduce the viscosity of the living polymer / gel solution by reducing the polymer concentration by adding sufficient solvent or strongly polar substances. The functionalizing agent should be dosed in high stoichiometric excesses and diluted with solvents. These solvents must then be separated from the polymer and recovered.

The above disadvantages are overcome by the process of preparing polymers with reactive end-functional groups by treating the living polymer with an anionic polymerization in the presence of an organoalkyl metal compound or an alkali metal by the functionalizing agent according to the invention. 30 to + 80 ° C for at least 5 seconds. .

The functionalization can advantageously be carried out under the evacuation of the heat produced, at a pressure of from 1 to 40 bar. It is advisable to apply at least 15 W of energy per kg of the mixture.

An advantage of the process of the invention is that it allows for substantially better contact between the living polymer and the functionalizing agent. Problems associated with the sudden increase in viscosity by polymers during functionalization and gel handling are easier to handle. is easier. In particular, this results in the possibility of treating substantially less dilute starting reactants. This will not only reduce the solvent consumption but also the associated advantages of handling, separating and recovering smaller volumes of solvents. This will also be reflected in the possibility of choosing an economically more advantageous lower solvent ratio when preparing the living polymer.

Functionalization can be easily realized as a continuous process on various kneaders. devices. Very advantageous is the use of the worm reactor according to U.S. Pat. No. 231 602 (PV 4801-80), in which the living polymer and the functionalizing agent are added along the extruder screw and the functionalization conditions can be continuously controlled by varying the amount of reactants to be supplied,. screw speed, creating back pressure at the outlet, and controlling. temperature during kneading. Kneading but. can also be carried out on conventional known screw extruders or screw extruders. mixing machines or other mixing and milling machines which may optionally be treated.

The process according to the invention is further explained in the following examples of practical implementation, wherein the functionalization was carried out on a screw reactor according to the art. No. 231 602 (PV 4801-80).

Example 1

First, a solution of live polybutadiene having a molecular weight of 2100 was prepared in a manner known per se by adding successively to a reaction solution containing 84 parts by weight of a solution of 4-dilithiobutane in methyl tert-butyl ether of 0.63 mol / kg and 290 parts by weight of toluene. stirring for · 90 minutes at 50 ° C 100 parts by weight · 1,3-butadiene. The solution of living polybutadiene in toluene and methyl tert-butyl ether had a concentration of 22% by weight of polybutadiene and a viscosity of 105 MPa. with.

The living polymer solution was fed to a screw reactor in which a temperature of 5 ° C was maintained. At the same time, a solution of ethylene oxide in toluene at a concentration of 60% by weight of ethylene oxide was added in an amount to maintain a one molar excess of ethylene oxide relative to the active lithium in the living polymer.

The residence time of the mixtures in the worm reactor was 45 s. The pressure was maintained in the range of 1.4-1.5 MPa and a solid gel-like string was discharged. The worm reactor was fed with 230 W of energy per kg of reaction mixture.

The resulting gel was then decomposed in a manner known per se by adding water and after centrifugation it was washed with water until neutral. After evaporation of the solvent, polybutadiene with a molecular weight of 2500 and a hydroxyl end group content of 0.7 mmol / g was obtained having a viscosity of 12,000 MPa. s at 30 ° C and a 1.2 structure content · 48.4 ° / o. The stoichiometric conversion efficiency of the organometallic group to the hydroxyl group was 92%.

Example 2

The living polybutadiene of Example 1 was treated in the same worm reactor, except that instead of ethylene oxide, carbon dioxide gas was fed in a 10 molar excess relative to the active lithium. In the screw reactor, the temperature of the mixture was maintained at -15 ° C and carbon dioxide * was fed to the extruder at 0.24 MPa. The screw reactor was maintained at 0.35 MPa.

The resulting stiff white gel was decomposed with hydrogen chloride and after washing the solvents were removed from the polymer solution on a rotary evaporator. A polymer containing 0.77 mmol / g of carboxyl groups having a molecular weight of 3557 and a viscosity of 1400 · 0 MPa was obtained. . at 30 ° C.

Example 3

A living polybutadiene solution was prepared in the same manner as in Example 1 except that the solvent in the polymerization was methyl tert-butyl ether. The batch composition was 76 parts by weight of methyl tert-butyl ether and 4.3 parts by weight of 1,4-dilithiobutane. 100 parts by weight of 1,3-butadiene were gradually added to the batch over a period of 75 minutes. The temperature was maintained at 30 ° C. ^x

This resulted in a solution of live polybutadiene at a concentration of 51% polybutadiene having a viscosity of 130 MPa at 30 ° C. The functionalization was carried out in a screw machine from a modified kitchen machine for grinding meat by adding an ethylene oxide solution as in Example 1. Also the further treatment after the functionalization was the same. The functionalization was circulated at a pressure of 0.5 MPa with a holding time of 6 seconds.

The obtained functionalized polybutadiene had a molecular weight of 3000, a hydroxyl group content of 0.68 mmol / g and contained 55% by weight of 1.2 structure.

Example 4

The procedure of Example 1 was repeated except that the living polybutadiene solution was prepared from 355 parts by weight of toluene and in the presence of 42 parts by weight of dilithiooligoisoprene dissolved in a mixture of toluene with 20% by weight of tetrahydrofuran. The initiator concentration was 0.95 mol / kg, so that 29.5 parts by weight of toluene and 7.3 parts by weight of tetrahydrofuran were added to the batch from the initiator solution. The polymerization was carried out at 30 ° C by adding 100 parts by weight over 90 minutes.

The living polybutadiene solution had a concentration of 20% by weight, a viscosity of 80 MPa. . and was fed into the hydroxylation worm reactor along with the functionalizing agent. During hydroxylation, the polymer solution was maintained at a temperature of -5 to -8 ° C and the pressure at the top of the screw reactor upstream of the discharge valve was 0.7 to 1.7 MPa. The residence time was 40 s and the power input per kg of the 130 W mixture.

A one molar excess of the functionalizing agent relative to the active lithium was used, which was successively ethylene oxide, γ-butyrolactone, 50% w / v ethylene oxide and carbon dioxide. In carboxylation with carbon dioxide, the temperature of the mixture was maintained at -15 ° C and the head pressure at 1.5-1.9 MPa, in contrast to the above values. The carbon dioxide: Li molar ratio was 5, the residence time of the mixture was 75 s and the power input per kg of the mixture was 400 W.

After gel decomposition and polymer isolation, liquid polybutadienes having end groups containing 87% by weight of structures 1.2 and having the properties according to the table below were obtained.

232851

Molecular weight

Functionalizing agent

Functional group type content: mmol / g

ethylene oxide 2600 - OH 0.8 butyrolactone 3500 —OH 0.6 butyrolactone + ethylene oxide 3200 —OH 0.7 carbon dioxide 2800 —COOH 0.8

Both the carboxyxylating agent and the living polybutadiene solution were dosed to the 10th screw of screw 2.

OBJECT OF THE INVENTION

Claims (4)

A process for preparing polymers with reactive end-functional groups by treating a living polymer with a functionalizing agent, prepared by anionic polymerization in the presence of an organometallic compound or an alkali metal polymerization initiator, characterized in that the living polymer is kneaded in the presence of the functionalizing agent at temperatures from -30 to + 80 ° C for at least 5 s. 2. Process according to claim 1, characterized in that the kneading is carried out at a pressure of 0.1 to 4.0 MPa. 3. A method according to claim 1 or 2, characterized in that kneading on the mixture is applied with an energy of at least 15 W per kg of mixture. Method according to one of Claims 1 to 3, characterized in that the functionalization takes place under the removal of the heat produced. Severography, n. P., Plant 7, Most