WO2003051942A1

WO2003051942A1 - Procedure for the formulation of a catalyst for the manufacture of cis-1,4-polybutadiene of controllable molecular weight

Info

Publication number: WO2003051942A1
Application number: PCT/US2002/039334
Authority: WO
Inventors: Hans A. R. Edel; Hartmut K. Stiller; Guenther H. Stock; Anke Schmudde
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2001-12-14
Filing date: 2002-12-10
Publication date: 2003-06-26
Anticipated expiration: 2004-06-14
Also published as: TW200300768A; AU2002353090A1

Abstract

The invention is a two-step procedure for the formulation of a mixed catalyst of a nickel compound preferably with diene addition, boron trifluoride and an organo-aluminum compound, for the synthesis of cis-1,4-polybutadiene rubber, in which in each case, in a first step boron trifluoride was reacted as an etherate complex (BF3OEt2) with triethyl-aluminum (AlEt3) in toluene, with a contact time in each case of between 10 and 120 minutes; the active component of the catalyst formulation here was the amorphous AlF3 formed and where in a second step nickel carboxylate-also in toluene- was added to the mixture. The procedure is suitable for the synthesis of cis-1,4-polybutadiene rubber with a high cis-1,4 content and a molecular weight controllable over a wide range, with the goal of minimizing gel formation during the polymerization process.

Description

PROCEDURE FOR THE FORMULATION OF A CATALYST FOR THE MANUFACTURE OF CIS-l,4-POLYBUTADIENE OF CONTROLLABLE

MOLECULAR WEIGHT

The invention concerns a procedure for the formulation of a mixed catalyst of a nickel compound preferred with diene addition, boron trifluoride and an organo-aluminum compound, suitable for the synthesis of cis-l,4-polybutadiene rubber with a high cis-1,4 content and a molecular weight controllable over a wide range, with the goal of minimizing gel formation during the polymerization process. In all procedural variants of the manufacture of synthetic rubber, the adjustment to specified molecular weight ranges is of decisive importance, since the application-related properties of polybutadiene are significantly affected thereby.

It is known that polybutadiene with a high cis-l,4-isomer fraction can be manufactured using coordinative catalyst systems. Some catalysts systems suitable in this sense are composed of a nickel compound and a boron trifluoride and an organo-aluminum compound that can also be used industrially (DD 61351, DD 265 150).

In these procedures the catalyst is formulated by combination of the three components which are added to the solution polymerization of butadiene in a hydrocarbon solvent (DE 1620927, GB 905099). The catalysts are dosed in the sequence nickel, boron and aluminum component (DD 213 934).

It can also be manufactured in a two-step formulation procedure (DD 251 149); while the change in the dosing sequence of the catalyst components during the formulation phase achieves a positive change in the polymer product's characteristic application-related parameters, no advantageous effect is described on important reaction quantities such as reaction temperature and reaction time.

As a rule, the desired molecular weights are adjusted by means of the monomer/catalyst concentration ratio, or by the addition of typical control substances, such as the presence of small amounts of 1-olefms (EP 93074, EP 93073) or of alkali carboxylates (US 6,013,746, EP980878). However, these control possibilities are very complicated in their industrial realization and generally also have effects on the catalyst's activity and properties, so that unintended changes in the polymer's properties profile may occur.

DD 296 940 describes a procedure for the formulation of such a three-component catalyst, in which a direct adjustment of the molecular weight of the polybutadiene can be accomplished by variation of the reaction time of two of the catalyst's components in a preliminary reaction. Catalyst formulation is accomplished by reacting a boron trifluoride and an organo-aluminum component over a variable period, in the range of 2-4 hours, and only then adding the nickel component and an additional amount of the aluminum component to the formulation process. In the subsequent solution polymerization, polybutadiene of very high, controllable molecular weight is obtained as a direct function of the reaction time of the preliminary reaction, at constant conversion ratios and a high cis-1,4 content in the polymer.

The disadvantage of this procedure is that because of the relatively long ageing time, the variation in the molecular weight is difficult to realize in the polymerization battery.

The invention is a two-step procedure for the formulation of a mixed catalyst of a nickel compound preferably with diene addition, boron trifluoride and an organo-aluminum compound, for the synthesis of cis-l,4-polybutadiene rubber, in which in each case, in a first step boron trifluoride was reacted as an etherate complex (BF₃OEt₂) with triethyl-aluminum (AlEt3) in toluene, with a contact time in each case of between 10 and 120 minutes; the active component of the catalyst formulation here was the amorphous A1F₃ formed and where in a second step nickel carboxylate - also in toluene — was added to the mixture.

The formulation according to the invention of a mixed catalyst of a nickel compound preferably with diene addition, boron trifluoride and an organo-aluminum compound for the synthesis of cis-l,4-polybutadiene rubber talces place in two steps, whereby the added diene can be butadiene, cyclooctadiene or vinylcyclhexene, preferably butadiene, and the added amounts of diene are 2 - 5 mol/mol Ni. It is possible to add triene, that is cyclododecatriene, at all.

In a first step the boron trifluoride compound, preferably its etherate (BF₃OEt₂), and the aluminum triethyl component (AlEt₃) are aged in an aliphatic or aromatic solvent, preferably toluene, at 0-150 °C, preferably 20-30 °C, so that a 0.1-10 %, preferably a 0.5-1 % suspension of amorphous A1F₃ results. Here the molar ratio of BF₃OEt₂ to AlEt₃ is of 0.6- 1.5 : 1, preferably 0.8-1.3 : 1. The residence time in the first mixer is of 10-120 min, preferably 60-80 min. In the second ageing step in a second mixer, the nickel compound - preferably nickel carboxylate - also in the same solvent as in step 1 or in a different solvent if the two are miscible - is added, in a concentration of 0.01-1 %, where the molar ratio of Al to Ni is of 0.5-20 : 1, preferably of 6-15 : 1 and where the nickel carboxylate contains 0.5-5 mol, preferably 1-3 mol diene, preferably butadiene. The residence time in the second mixer is also of 10- 120 min, preferably 60-80 min.

The two-stage ageing can be realized continuously or discontinuously.The polymerization of butadiene takes place at a temperature of 40-110 °C, in an aromatic or cycloaliphatic solvent, preferably toluene. One advantage of the solution according to the invention is that due to the temporal variability of the two ageing steps, the molecular weight values of the polybutadiene can be adjusted as a function of the intended application, with the catalyst formed in each case with resulting Mooney values ML 1+4 between 10 and 140 The products obtained are characterized by their low gel content. The end product's freedom from gels can be proven both in a strongly reduced cleaning effort for the reactors and the pipelines, as well as in the polymer solution filtering cycles. Thus, within one operating period (approx. 180 days) the polymer solution filter changes are no longer necessary, with the solution according to the invention, in comparison with the traditional mode of operation.

EXAMPLES

The following discontinuous polymerization experiments are performed in 20 L stirrer reactors. Ageing takes place under nitrogen, in each case in 1 L stirrable glass containers.

Example 1

A 114 g of a 0.5 % BF₃OEt₂ solution (0.004 mol) in toluene,

B 45.45 g of a 1 % AlEt₃ solution (0.004 mol) in toluene and

- C 23.52 g of a 0.1 % Ni carboxylate solution with added butadiene (0.0004 mol) in toluene were used.

A was aged with B for 60 min at 30 °C, in formulation container 1. Amorphous A1F₃ separated in the form of a white colloid. The mixture was then transferred to formulation container 2. C was then added. Age for another 10 min and use the orange colored catalyst suspension formed directly for polymerization. To this end the catalyst was introduced into the reactor charged with 10,000 g toluene and 1000 g butadiene. After a polymerization period of 4 h at 60 °C, 945 g polymer were obtained after processing the polymer solution (94.5 % of theoretical) of cis- 1,4-polybutadiene with a > 96 % 1,2-cis fraction and with a non-measurable gel content (10 μm filter). The resulting Mooney value ML 1+4 was 65.

Example 2

A 114 g of a 0.5 % BF₃OEt₂ solution (0.004 mol) in toluene,

B 45.45 g of a 1 % AlEt₃ solution (0.004 mol) in toluene and C 23.52 g of a 0.1 % Ni carboxylate solution with added butadiene (0.0004 mol) in toluene were used.

Proceed as in 1.

1. Age 20 min at 20 °C.

2. Age 60 min at 35 °C After a 4 h polymerization time at 60 °C, 940 g polymer were obtained after processing the polymer solution (94 % of theoretical) of cis- 1,4-polybutadiene with a > 96 % 1,2-cis fraction and with a non-measurable gel content (10 μm filter). The resulting Mooney value ML 1+4 was 63.

Example 3 A 148.2 g of a 0.5 % BF₃OEt₂ solution (0.0052 mol) in toluene,

A was aged with B at 30 °C for 60 min in formulation container 1. Amorphous A1F₃ separated in the form of a white colloid. The mixture was then transferred to formulation container 2. Then C was added. Age for another 60 min and use the orange colored catalyst suspension formed directly for polymerization. To this end the catalyst was introduced into the reactor charged with 10,000 g toluene and 1000 g butadiene. After a polymerization period of 4 h at 60 °C, 950 g polymer were obtained after processing the polymer solution (95 % of theoretical) of cis- 1,4-polybutadiene with a > 96 % 1,2-cis fraction and with a non-measurable gel content (10 μm filter). The resulting Mooney value ML 1+4 was 45.

Example 4

A 114 g of a 0.5 % BF₃OEt₂ solution (0.004 mol) in toluene,

B 59.08 g of a 1 % AlEt₃ solution (0.0052 mol) in toluene and C 23.52 g of a 0.1 % Ni carboxylate solution with added butadiene (0.0004 mol) in toluene were used.

A was aged with B at 30 °C for 60 min in formulation container 1. Amorphous A1F₃ separated in the form of a white colloid.

The mixture was transferred to formulation container 2. Then C was added. Age for another 60 min and use the orange colored catalyst suspension formed directly for polymerization. To this end the catalyst was introduced into the reactor charged with 10,000 g toluene and 1000 g butadiene. After a polymerization period of 4 h at 60 °C, 950 g polymer were obtained after processing the polymer solution (95 % of theoretical) of cis- 1 ,4-polybutadiene with a > 96 % 1,2-cis fraction and with a non-measurable gel content (10 μm filter). The resulting Mooney value ML 1+4 was 86.

The continuous experiments for catalyst formulation were performed in a stirrer vessel cascade of 2 reactors, at 60 °C.

Figure 1 : B/Al ratio - Mooney relation in continuous experiments [KEY: Verhaltnis = ratio]

B/Al-Verhaltnis- Mooney- Relation

0,85 0,95 1,05 1,15 1,25 1,35 1,45 1,55

B/Al [mol/mol]

As in the discontinuous experiments, 2 temperature-controllable formulation containers in series are used.

A 0.5 % BF₃OEt₂ solution in toluene,

B 1 % % AlEt₃ solution in toluene and

C 0.1 % Ni solution in toluene were used.

The residence time in the formulation containers was realized over the addition of the corresponding standard solutions. In direct analogy to the discontinuous experiments, the desired molecular weights could be obtained by adjusting the B:A1 ratio.

As in the discontinuous experiments, cis-polybutadiene with a > 96 % 1,4-cis fraction and a non-measurable gel content (10 μm) was obtained. The resulting Mooney values ML 1+4 can be controlled without problem over a very wide range.

Claims

WHAT IS CLAIMED IS:

1. Procedure for the formulation of a catalyst suitable for the manufacture of cis- 1,4- polybutadiene of controllable molecular weight, comprising of a nickel compound soluble in hydrocarbons, preferably with diene addition, a boron trifluoride and organo-aluminum compound, characterized by the formulation being carried out in two steps, whereby in the first step the boron trifluoride compound and the aluminum triethyl compound are aged at 0-150 °C, so that a 0.01-10 % suspension of aluminum trifluoride results, with the molar ratio of boron trifluoride to organo- aluminum compound being of 0.6-1.5 : 1 and where in a second step the nickel compound is added in a concentration of 0.01-1 %, such that the molar ratio of Al to Ni is of 0.5-20 : 1, the nickel compound contains 0.5-5 mol diene, preferably butadiene and the residence time in both steps is of 10-120 min.

2. Procedure for the formulation of a catalyst according to claim 1 , characterized by the boron trifluoride compound and the aluminum triethyl compound being aged at 20-30 °C, in the first step.

3. Procedure for the formulation of a catalyst according to claim 1, characterized by a

0.5-1 % suspension of aluminum trifluoride resulting in the first step.

4. Procedure for the formulation of a catalyst according to claim 1, characterized by the molar ratio of boron trifluoride to the organo-aluminum compound being of 0.8- 1.3 : 1.

5. Procedure for the formulation of a catalyst according to claim 1, characterized by the residence time in the reactor being of 60-80 min in each step.

6. Procedure for the formulation of a catalyst according to claim 1 , characterized by the molar ratio of Al to Ni being of 6-15 : 1

7. Procedure for the formulation of a catalyst according to claim 1, characterized by the nickel compound containing 1-3 mol butadiene.