JPH0219126B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a low molecular weight polymer by polymerizing or copolymerizing a conjugated diolefin or an aromatic vinyl compound therewith. The low molecular weight polymer targeted by the present invention is a liquid or extremely viscous candy-like polymer with an intrinsic viscosity (measured in toluene at 30°C) of 1.0 or less, and is used in injection rubbers, sealants, adhesives, paints, etc. It is an extremely useful material as a molecular modification material. Conventionally, such low molecular weight polymers have been produced by anionic polymerization using, for example, metallic sodium, but this requires the use of a large amount of catalyst, is expensive, and is not industrially practical. Conventionally, ether compounds have been used as microstructure modifiers in anionic polymerization of conjugated dienes.
Alternatively, it is known to be used as a randomizer to randomize styrene bonds in the production of styrene-butadiene copolymers using organolithium compound catalysts. However, simply combining an organolithium compound and an ether compound has little effect on lowering the molecular weight, and a large amount of catalyst is required to obtain a low molecular weight polymer. Therefore, since the organolithium initiator is expensive, it is economically disadvantageous. The present inventors have carried out extensive studies in order to provide a useful method for producing low molecular weight polymers having arbitrary microstructures with a small amount of catalyst that would normally produce high molecular weight polymers. The molecular weight can be easily lowered by adding an ether compound to an organolithium compound and an anionic surfactant having a hydrophilic group represented by -SO ₃ K or -OSO ₃ K in the presence of an aromatic hydrocarbon solvent and polymerizing it. The present invention was achieved by discovering that the microstructure of the resulting low molecular weight diene polymer can be controlled arbitrarily. That is, the present invention relates to the production of a diene-based low molecular weight polymer by polymerizing or copolymerizing at least one type of conjugated diolefin or at least one type of aromatic vinyl compound with the same, an organolithium compound as a polymerization catalyst and an organic lithium compound as a co-catalyst. Polymerization or copolymerization using a combination of an anionic surfactant having a hydrophilic group represented by -SO ₃ K or -OSO ₃ K and an ether compound in a solvent containing 20% by weight or more of an alkyl-substituted aromatic hydrocarbon. This is a characteristic method for producing low molecular weight polymers. Examples of the conjugated diolefin used in the present invention include butadiene, isoprene, and 1,3-pentadiene, and examples of the aromatic vinyl compound include styrene and α-methylstyrene. Examples of the organic lithium compounds used in the present invention include alkyllithiums such as ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, iso-butyllithium, latramethylene dilithium, hexamethylene dilithium, etc. alkylene dilithium such as propenyl lithium; alkenyl lithium such as propenyl lithium; 1,3-dilithiobenzene 1,2,5-trilithionaphthalene, 1,3,5,8-tetralithiodecasane, etc. can be used. As a component of the cocatalyst, the formula −SO ₃ K or −
An anionic surfactant having a hydrophilic group represented by OSO ₃ K is used, and some specific examples are as follows. a Alkylaryl sulfonate Potassium dodecylbenzenesulfonate, potassium tetradecylbenzenesulfonate, potassium hexadecylbenzenesulfonate, potassium octadecylbenzenesulfonate, potassium dibutylnaphthalenesulfonate, potassium diisopropylnaphthalenesulfonate, potassium naphthalenesulfonate formalin condensates, etc. b Amide-bonded sulfonate N-methyl-N-oleyl taurate, N-methyl-N-lauryl taurate, N-methyl-N
- Potassium methanesulfonate laurylamide, etc. c Ester-bonded sulfonate Potassium salt of condensate of oxyethanesulfonic acid and oleic acid, potassium salt of dioctyl sulfosuccinate, etc. d Higher alcohol sulfate ester salt Potassium sulfate ester salt of lauryl alcohol, potassium sulfate ester salt of oleyl alcohol, potassium sulfate ester salt of stearyl alcohol, etc. e Ester-bonded sulfate ester salt Various sulfate potassium salts and sulfonic acid potassium salts such as lauroyl trimethylene glycol sulfate potassium salt and other polyoxyethylene alkyl ether sulfate potassium salts can be used. Note that there are many anionic surfactants having a hydrophilic group represented by -SO ₃ M or -OSO ₃ M, and Na, K, Rb, Cs, etc. are known as M, but from the viewpoint of obtaining low molecular weight polymers, Particularly preferred is K salt. Among the above compounds, alkylbenzenesulfonic acid potassium salts are preferred in terms of chemical stability, price, availability, and solubility in aromatic hydrocarbons. The amount of the anionic surfactant used is 1 lithium
Based on potassium atom to gram atom
0.005-2.0 gram atoms are preferred. If it is less than 0.005 g atoms, the effect of lowering the molecular weight will be small when used in combination with ether, and if it is more than 2.0 g atoms, the polymerization activity will tend to decrease. Examples of the ether compound which is another component of the co-catalyst include the following. For example, diethyl ether, di-butyl ether, diisopropyl ether, dimethyl ether, dioctyl ether, tetrahydrofuran, dioxane, dimethoxyethane, diethoxyethane, diphenyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-
Butyl ether, triethylene glycol dimethyl ether, anisole, ethylene glycol dibutyl ether, etc. are used. The amount of ether used depends on the type of ether used,
Although it cannot be determined unconditionally because the microstructure differs depending on the amount, it is necessary to add 0.01 mol or more per 1 gelam atom of lithium. As the polymerization solvent, an alkyl-substituted aromatic hydrocarbon is used alone or in combination with one or more selected from aliphatic or alicyclic hydrocarbons and benzene. Examples of alkyl-substituted aromatic hydrocarbons include toluene, xylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,
5-trimethylbenzene, ethylbenzene, 1-
Methyl-2-ethylbenzene, isopropylbenzene, etc. are used. Preferred hydrocarbon solvents used in combination therewith include propane, n-butane, iso-pentane, n-hexane, n-heptane, iso-octane, n-decane, cyclopentane, methylcyclopentane, cyclohexane, benzene. etc. The amount of the alkyl-substituted aromatic hydrocarbon used is 20% by weight or more based on the total solvent; if it is less than this, the effects of the present invention cannot be expected. There is no particular restriction on the reaction temperature, but it is usually -80℃~
150°C, preferably -20°C to 120°C. The pressure of the reaction system should be sufficient to maintain the reaction mixture in a liquid phase, and is usually 1 to 5 kg/m ² .
Although the pressure is about gauge pressure, under special conditions the reaction can be carried out at higher or lower pressures. The amount of the polymerization solvent to be used is not particularly limited, but it is usually preferred to use about 1 to 20 parts by weight per 1 part by weight of the monomer. The amount of organic lithium compound used is determined by the reaction rate and the molecular weight of the desired polymer, but the amount of effective lithium per mole of monomer is
Approximately 0.05 to 5 milligram atoms is appropriate. Further, the order of addition of the polymerization catalyst and co-catalyst is not particularly limited. After the reaction is completed, an antiaging agent and a polymerization terminator such as water or alcohol are added in a conventional manner, and if necessary, the resulting polymer is pre-cleaned, separated and dried to obtain the desired low molecular weight polymer. The present invention will be explained in more detail with reference to Examples below. In this example, the microstructure is D.Morero
[Chim.e.Lind., 41 , 758 (1959)]. The intrinsic viscosity was measured in toluene at 30°C using an Ubbelohde viscometer. Example 1 60 g of cyclohexane containing a predetermined amount of toluene and 10 g of butadiene were placed in a 100 ml pressure-resistant glass bottle that had been dried and purged with nitrogen, and the reaction bottle was kept at 50°C. Next, the amount of n necessary to remove impurities in the system is
- Butyllithium was added. Thereafter, predetermined amounts of potassium dodecylbenzenesulfonate (DBS-K) and diethylene glycol dimethyl ether (diglyme) were added, and further, a predetermined amount of n-butyllithium (n-BuLi) was added. The reaction was carried out at 50°C for 2 hours, the reaction was stopped with alcohol, and 2,6
0.5 g of -di-tert-butylcatechol was added, and then the solvent was removed and dried. The results are shown in Table 1. The conversion rate was 100% in all cases.

[Table] When the amount of toluene in the solvent is subtracted, [η] decreases from 1.90 to 0.41 even with the same amount of catalyst, indicating that the molecular weight reduction effect is large. Example 2 The same procedure as in Example 1 was carried out except that the reaction solvent used in Example 1 was only 55 ml of toluene, and the amounts of DBS-K and diglyme added were changed as shown in Table 2. The results are shown in Table 2. The conversion rate was 100% in all cases.

[Table] As shown in Table 2, it is not possible to obtain a low molecular weight polymer even in polymerization in toluene unless DBS-K and diglyme are used in combination as co-catalysts.
It is also shown that the microstructure of the low molecular weight polymer can be freely controlled by changing the amount of diglyme, which is an ether. Example 3 Polymerization was carried out in the same manner as in Example 2 except that the type of ether was changed. The results are shown in Table 3. In both cases, the conversion rate was 100%.

[Table] Example 4 The same procedure as in Example 2 was carried out except that a mixture of butadiene and styrene was used as the monomer and the butadiene/styrene (BD/ST) ratio was changed. The conversion rate was 100% in all cases.

[Table] Example 5 The same procedure as Example 2 was carried out except that the monomer was changed to isoprene.

【table】

Claims (1)

[Scope of Claims] 1. In producing a diene-based low molecular weight polymer by polymerizing or copolymerizing at least one conjugated diolefin or at least one aromatic vinyl compound therewith, an organolithium compound or a cocatalyst is used as a polymerization catalyst. Polymerization or copolymerization in a solvent containing 20% by weight or more of an alkyl-substituted aromatic hydrocarbon using a combination of an anionic surfactant having a hydrophilic group represented by the formula -SO ₃ K or -OSO ₃ K and an ether compound. A method for producing a low molecular weight polymer, characterized by: