DD228551B1 - METHOD FOR THE CATALYTIC SOLUTION POLYMERIZATION OF 1,3-BUTADIENES - Google Patents

Description

Characteristic of the known technical solutions

Since the beginning of the 1960s, poly-cis-butadiene has been produced industrially by the solution polymerization process using Ziegler-Natta catalysts or Philips catalysts. In general, combinations of aluminum alkyl halides with organically soluble heavy metal complex compounds are used (Saltmann, W.M., Kuzma, Ll .: Chem. Techno!., 1973, 1055).

The chosen catalyst system predominantly determines the stereospecific orientation of the polymer. In order to achieve the highest possible 1,4-cis fraction, the catalyst complexes AIR2-COCl2, TiCl ₂ -Ilg-I ₂ and Ni complexes are particularly suitable.

The use of various solvents is described in numerous patents. So z. B. in DE-AS 1420456 as suitable solvents saturated alkanes such as butane, hexane, heptane, individually or in admixture, deobase kerosene, or benzene hydrocarbons such as benzene, toluene or cycloalkanes such as cyclohexane, methylcyclohexane recommended. It is apparent from this application that the absence of oxygen, water, peroxides, dihydric sulfur compounds and various other impurities is very important to the polymerization.

It has been known since the mid-1940s that butadiene dimers and other high-boiling hydrocarbons retard or negatively affect the polymerization of butadiene (Robey, R.F., et al., Ind. Eng. Chem., 36, 3, 1944). The formation of dimers can i.a. during storage of the butadiene or during the recovery stages.

At the present time, the most effective catalyst for the stereospecific butadiene polymerization is a three-component catalyst, e.g. B.

aluminum triethyl, nickel carboxylate and boron trifluoride etherate in aromatic solvents. After Yoshimoto, Komatsu, Sakata, Yamamoto, Takeuchi, Onishi and Uedain Makromolek. Chem. 139 (1970), page 61 et seq., The molar ratios of the three components depending on the desired course of polymerization 0.6 to 1.0: 0.05: 0.8 to 6.0 mmol / 100 g of 1,3-butadiene.

The use of toluene for the polymerization of 1,3-butadiene to 1,4-cis-polybutadiene is described in several Japanese patents and by G.W. Poehlein and D.I. Dougherty in Rubber Chem. Technol. 50, pp. 601-638 (1977).

The requirements for the highest degree of purity of toluene are contained in the TGL 26812/02 for the so-called pure toluene 1.

The following criteria are listed: Sulfuric acid reaction max. 0,3g / l, bromine consumption max. 0.1 g / l, evaporation residue max.

5mg / 100ml, free of active sulfur.

Since no conclusions can be drawn on the suitability of the toluene for the polymerization on the basis of these criteria, it is customary to determine this by a laboratory test polymerization. For this purpose, the so-called.

Flaschenpolymerisation. The control is carried out by sales determination and is then available as an operational specification with the appropriate solvent as standard. Although the cause of polymerization delays is mostly known, it is still unclear why polymerization under identical conditions with the same catalyst system and toluene as a solvent with the same analytical indexes is sometimes faster than the standard polymerization.

Object of the invention

The aim of the invention is to increase the speed of the known stereospecific polymerization of 1,3-butadiene to cis-polybutadiene in solvent toluene, without adversely affecting the physical characteristics of the rubber and thus its utility properties.

The increase in the reaction rate should always remain the same, the economics of the production of cis-polybutadiene should be improved.

Explanation of the essence of the invention

The invention has for its object to develop a process for the catalytic solution polymerization of 1,3-butadiene in toluene with known catalyst systems using suitable additives, the above requirements should be guaranteed.

The object is achieved according to the invention by polymerizing, in a manner known per se, 1,3-butadiene in toluene in the presence of a known catalyst system, to which 0.01 to 0.05% cyclooctadiene is added to the toluene.

It has been found that the cyclooctadiene concentrations mentioned act so activating on known catalyst systems that with the same amount of catalyst up to 10% more 1,3-butadiene can be polymerized without the physical or utility properties changing noticeably. The discovery that this amount of cyclooctadiene, which in principle is present in traces, exerts such a control effect on the rate of polymerization or the activity of the catalyst system is surprising to the person skilled in the art, since butadiene dimers are known as polymerization retardants (Robey, RF, et al., Ind. Eng. Chem., 36, 3 [1944]). Although this polymerization delay occurs, but only at concentrations of about 0.05% cyclooctadiene in toluene.

Although the effect of the cyclooctadiene mentioned occurs more or less strongly in any known stereospecific butadiene polymerization catalyst system, it is particularly pronounced in the system of organoaluminum compounds, preferably in the tri-tri-butane, nickel naphthenate and boron trifluoride etherate three-component catalyst.

A further surprising effect has been found in the fact that the aging time of the catalyst solution required for obtaining an optimal activity is considerably shortened by the addition of cyclooctadiene according to the invention.

For the process according to the invention, neither the polymerization temperature nor the pressure to which the catalyst solution with the butadiene is exposed are decisive. Pressures of 0.1 MPa and above or below and temperatures between -5O ⁰ C to 100 ⁰ C can be applied. In a preferred embodiment, liquid butadiene is dissolved in toluene under an inert gas atmosphere, such as nitrogen, and polymerized under autogenous pressure of the present substances at -20 ⁰ C to + 100 ⁰ C, preferably 50 to 90 ⁰ C.

The inventions will be explained below with reference to exemplary embodiments.

embodiments

For the polymerization experiments, toluene according to TGL 26812/02 quality 1, which was distilled again, was used, later called toluene 1. Toluene 1 with an addition of 0.01% cyclooctadiene leads the name toluene 2, with 0.05% cyclooctadiene toluene. 3

Three polymerizations on a laboratory scale (Examples 1 to 3) and two large-scale continuous butadiene polymerizations (Examples 4 and 5) were carried out.

Examples 1, 2 and 3

The polymerization vessels were thoroughly cleaned, dried and purged with argon. To remove any residual air and moisture, 1 ml of a 10% strength aluminum triethylalcohol solution in toluene was introduced with an injection syringe and removed immediately before the beginning of the polymerization. As a catalyst, nickel naphthenate, boron trifluoroetherate and aluminum triethylamine were injected. After aging of the catalyst of 60 minutes at 5O ⁰ C 1,3-butadiene in toluene was added and held the polymerization temperature at 4O ⁰ C. After 60.90 and 120 minutes respectively, sales provisions were made.

Table 1 summarizes the degrees of implementation of the 3 laboratory tests.

Table 1:

Control polymerization with

Sales (%) after 90

120 minutes

Toluene 1 (standard) toluene 2 toluene 3

83 87 90

88 92 94

Example 1 a

Analogously to Examples 1 to 3, 1,3-butadiene was polymerized with the three-component catalyst system, which, however, contained nickel octoate instead of nickel aprothiate. The butadiene conversion was of the same order of magnitude as shown in Table 1.

Claims (1)

Process for catalytic! Solution polymerization of 1,3-butadiene in toluene and in the presence of a tri-component aluminum triethyl (TEAI), nickel carboxylate (NiOct), and boron trifluoride etherate (HX) with TEAL: NiOct: HX 0.6 to 1.0: 0.05: 0 molar ratios , 8 to 6.0mmol / 100g of 1,3-butadiene, characterized in that 0.01 to 0.05% of cyclooctadiene is added to the toluene. Field of application of the invention The invention relates to a process for the catalytic solution polymerization in toluene for the preparation of the stereo-rubber 1,4-cis-polybutadiene. This rubber is particularly suitable for the treads of vehicle tires, as it over SBR and natural rubber has significant advantages such. B. higher abrasion resistance, lower gas permeability, higher bending, tear strength and better electrical properties.