DE1770277C - Process for the polymerization of isoprene - Google Patents

Description

Approach-
No. 3-bromophenyI-
lithium
mhm 1,3-dibromo
benzene
mhm Conversion (3)
"/. Micro structure (4)
· / Ice I ^{0 /} · ³ ^
1 ° ^CIS I addition 6.7
6.5
6.2 Inhfxente
Viscosity (S) Time to sink
the steel ball
Minutes (6) 1
2
3 1.0
1.0
1.0 0
0.025
0.10 85
87
90 92
77
83 5.15
4.85
4.07 3.5
2.6
1.4

The data of Table II -provides that when using- The above procedure was used for four more Generation of ', 3-dibromobenzene repeats the inherent viscosity approaches with the main difference that of the polyisoprene produced decreased from 5.15 to 4.07, using 1,4-dibromobenzene in place of 1,3-dibromobenzene at the same time the conversion was turned from 85 to 90%. The results of these further approaches rise. This is a very surprising result. 35 are the following:

Table III

Approach-
Ni. 3-broniphenyl
lithium
mhm 1,4-dibromo
benzene
mhm Conversion (3) Mikrostn
7o ice structure (4)
7 3,4-
addition Inherent
Viscosity (5) Time to sink
the steel ball
Minutes (6) 4th
5
6th
7th 1.0
1.0
1.0
1.0 0
0.05
0.10
0.15 92
85
95
85 81
86
83 6.5
6.3
6.8 4.69
5.01
4.55
5.03 3.6
3.8
3.3
3.3

The data in Table III show that 1,4-dibromo-Three further runs were made in the same manner as

benzene has the surprising results shown in Table II- described above with the exception of

results were not achieved and that 1,4-dibromobenzene 50 leads to bromobenzene instead of 1,3-dibromobenzene

no functional one was used in the present invention. The results of these approaches were

Represents equivalent to 1,3-dibromobenzene. the following:

Table IV

Approach-
No. 3-uromphcnyl-
lithium
mhm Broinbcnzol
mhm Conversion
lung (3)
¹ Vn Microstr
Vo ice icture (4)
7 "3,4-
Addiliun Inherent
Viscosity (5) Time to sink
the steel ball
Minutes (6) 8th
9
10 1.0
1.0
1.0 0
0.05
0.10 82
83
91 84
92 6.5
6.7 4.95
5.09
5.11 3.4
4.0
4.4

The data in Table IV show that bromobenzene In all tables from II to IV the changes were

the surprising conversion values, microstructure values, inherent viscosity

nissc was not achieved and that bromobenzene is therefore

The present invention does not have a functional equivalence:

is valent of 1,3-dibromobenzene. (3) The conversion was made by multiplying

the weight of the obtained polyisoprene by 100 and dividing the resulting number by the weight of the charged isoprene is determined.

(4) The microstructure was made according to that given in U.S. Patent 3,215,679 (column 11, lines 4 to 25) Method received.

(5) The inherent viscosities were determined according to the method described in U.S. Patent 3,215,679 (column 11, line 26 to 39), with the exception that line 39 should read: »by the weight of the ίο soluble portion of the original sample ".

(6) The steel ball sinking time is the period between the first contact with the 3.52 g rounds Steel ball with the surface of the polymerization mixture in the reactor and arrival of the steel ball on the bottom of the reactor, with the polymerization mixture is still reasonable and the ball is lowered from a standard six inches. at In each of the approaches, the polymerization was carried out in an equally sized reactor using the same Reactant quantities carried out so that the volume of substances in the reactor standardized and the Distance between the surface of the polymerization mixture and the reactor floor was also standardized. In this way the steel ball enclosed essentially the same removal in each batch by essentially the same amount of polymerization mixture back; the shorter the time it takes for the steel ball to sink, the less viscous; is then the polymerization mixture.

Claims (2)

1 corresponds to 2 isoprene to be polymerized. The amount of modifying agent used may also vary widely, but will generally be so. that they - with constant initiator contents - reduce the inherent viscosity of the resulting polyisocyanate 1. Process for the polymerization of isoprene to prens despite increasing percentages of the monomer rubber-like polyisoprene in the presence of conversion is sufficient, and in general it is in monobromophenyllithium as initiator, thereby range from about 0.01 to about 5 or 10 mol modifige k en η zei ch η et that the polymerization agent per mol in the polymerization in the presence of a small amount of 1,3-io mixture of initiator present.
Dibromobenzene and optionally a small amount of tetravinyltin or tetraallyl tin is carried out in the customary manner known in this field. carried out, and generally tempera- 2. The method according to claim 1, characterized in that it is in the range from about -100 to 150 "C and indicates that the initiator used is 3-bromine-phenol is nii? Rpirh <» nflp nriirlie; intK »u / pnrli» t hatred Here, polymeric lithium is used, a cationic mixture essentially in a liquid state is held. The polymerization can be carried out in the presence or absence of customary diluents. to suitable diluents include aromatic, aliphatic, cycloaliphatic agents, their combinations, such as alkyl aromatic agents, these diluents preferably 4 to 15 carbon The invention relates to a new and improved atom per molecule containing. About suitable dilution processes for the polymerization of isoprene. 25 solvents include benzene, toluene, cyclohexane, So far, conjugated dienes have been made using methylcyclohexane, xylene, n-butene, η-hexane, n-pentane, vi »n organolithium compounds polymerized. With isooctane. some polymerization processes wind modifi / ie- The reactants can be customary in this funds used. Area known way in the polymerization reactor It has now been ascertained that isoprene is introduced under Ver 30. To be used according to the invention Modifying agents present in monobromophenyllithium can be present in the polymerisation unit Can be polymerized by 1.3 · dibromobenzene / ol, tion reactor simultaneously with the initiator, before the and the surprising result was obtained, charging the initiator or at any time that the inherent viscosity of the point before polymerization is 70% of the normal resultant Polyisoprene is reduced, whereby 35 wise has reached a complete degree of polymerization, the polyisoprene is made easier to process, whether or not it is introduced. The modifying agent can be in probably at the same time the monomer conversion increased proportions, completely at once or to others will. It was very unexpected to find that the former wise be admitted. inherent viscosity of the polyisoprene is reduced The could while at the same time the Percentage / 40 procedure won and treated, and it can with the monomer conversion in the process customary additives such as carbon black, pigments, antioxidants was, since it is common practice in this field, other stabilizers and the like, to be mixed up, expects conversion increases in polymers If desired, polyisoprene can be used according to the result with increasing viscosity. It should be noted lying invention under additional presence that this determination is based on the condition that 45 of tetraallyl tin (TAT) or tetravinyl tin (TVT) the initialor content remains the same, while the percentage produced during the polymerization is around the rate of conversion and inherent viscosity, processability of the polyisoprene produced varies will. improve. In general, about 0.025 to about F-in will be the overriding result of 1.25 mmoles of TAT or TVT per 100 grams to polymerize isoprene monomer obtained by using 1,3-dibromohenzene. The TAT or Effect with 1,4-dibromobenzene or bromobenzene TVT can essentially at any point in time was not achieved. During the polymerization process according to customary methods, such as simple stirring-in, can be added Polyisoprene is available as rubber / ur production of the whole quantity or (at intervals) separately of pneumatic tires and the like. 55 proportions of TAT or TVT in the polymerization reaction Iindig Isoprene is mixed in the usual way. The TAT or TVT is preferred polymerizes using a monobromine in the polymerization reaction mixture to form some phosphorus lithium compound, like 3- or 4-Hromphenyl- a point in time up to 90% 'gcn completion Lithium, preferably .I-Bromphcnyllilhium, added as an initiator of the polymerization reaction (bcdeulor. however, in the presence of a small amount of 60 let, the time at which the Polymerisa-1,3-Dihrcmhen / ol as a modifying agent, and ionic reaction is complete, regardless of the percentage accident a small amount of telravinyltin sat / es the conversion of the isoprene monomer). At the or Ietraallylzinn. "most suitable becomes the TAT or TVT to either The Iniliatormcngc used can vary widely, point in time after about 10% completion and before However, it generally proceeds in such a way that it takes 65 to 90% completion of the polymerization (lcr l'oljinerisalion of isoprene is sufficient, and in all-reaction added. In general, a method similar to that of the following example illustrates the invention without 0.05 to about 50 milliequivalents of lithium per K) Og to limit their use.