JP4389646B2 - Method for adjusting molecular weight of trans-1,4-polybutadiene - Google Patents

Description

  The present invention relates to a novel process for producing trans-1,4-polybutadiene.

  Butadiene is known to obtain polymers having various microstructures with a polymerization catalyst. Polybutadiene containing a lot of trans-1,4 bonds is a crystalline polymer that causes a solid phase transition phenomenon, and polybutadiene containing 95% or more of the trans bonds is particularly prominent in volume change and heat transfer due to the solid phase transition phenomenon. For example, Japanese Patent Application Laid-Open No. 9-268208 (Patent Document 1) discloses use as a heat storage material, and Japanese Patent Application Laid-Open No. 2003-45704 (Patent Document 2) discloses use as a PTC material. When used as a material in this way, it is desirable that high trans-1,4-polybutadiene has an appropriate molecular weight depending on the application.

  Such a high trans polybutadiene can be produced using a vanadium catalyst as described in, for example, Japanese Patent Publication No. 44-21104 (Patent Document 3). However, in the production of high trans polybutadiene using a vanadium catalyst, there is no known additive (chain transfer agent) capable of adjusting the molecular weight by performing chain transfer instead of chain termination.

Further, when transpolybutadiene is produced using an alphine catalyst, a molecular weight is obtained by adding a cyclic ether such as trioxane to the reaction system as described in, for example, Japanese Patent Publication No. 48-16059 (Patent Document 4). It is known that the trans 1,4- content is at most 70%.
In addition, when transpolybutadiene is produced using an organic cobalt compound catalyst, for example, as described in JP-A-8-67716 (Patent Document 5) and JP-A-2002-145921 (Patent Document 6), It is known that the molecular weight can be adjusted by adding a sulfoxide compound such as dimethyl sulfoxide to the reaction system, but the trans 1,4- content is at most 85%. Moreover, when these molecular weight regulators are added, the activity (yield) of the polymerization reaction decreases. There has been a demand for a molecular weight regulator that does not cause a decrease in activity. In addition, there is no known example in which a high-trans polybutadiene having a high phase transition heat quantity can be produced using these catalysts.

  In the production of high cis-1,4-polybutadiene having a trans bond ratio of 1.3% at most, JP 2003-82008 (Patent Document 7), JP 2003-82009 (Patent Document). As described in 8), hydrogen alone is known to act as a chain transfer agent. However, there is no known example in which hydrogen acts as a chain transfer agent in the production of trans-1,4-polybutadiene.

Similarly, in the production of cis-1,4-polybutadiene having a low trans bond ratio, as described in, for example, Japanese Patent Publication No. 36-4747 (Patent Document 9), α-olefins and non-conjugated dienes are substantially not used. Are known to be chain transfer agents, but no examples are known to act as chain transfer agents in the production of trans-polybutadiene,

  Thus, in the production of polybutadiene having a trans bond content exceeding 90%, a molecular weight regulator that does not affect physical properties other than molecular weight, that is, a chain transfer agent is not known. For this reason, a novel chain transfer agent has been demanded.

Japanese Patent Laid-Open No. 9-268208 Japanese Patent Laid-Open No. 2003-45704 Japanese Examined Patent Publication No. 44-21104 Japanese Patent Publication No. 48-16059 JP-A-8-67716 JP 2002-145921 A Japanese Patent Laid-Open No. 2003-82008 JP 2003-82009 A Japanese Patent Publication No. 36-4747

  The present invention enables the adjustment of the molecular weight without affecting the catalytic activity and the physical properties other than the molecular weight of the polymer produced during the production of polybutadiene having a trans-1,4-structure as the main structure. A method for controlling the molecular weight is provided.

In the present invention, 1,3-butadiene is polymerized to produce polybutadiene having 90% or more of butadiene units having a trans-1,4 bond structure , and (A) ethylene and (B) hydrogen are used as chain transfer agents. The present invention relates to a process for producing trans-1,4-polybutadiene, characterized in that the molecular weight is adjusted by this.

  The present invention also relates to a method for producing the above trans-1,4-polybutadiene, characterized in that the polymerization of 1,3-polybutadiene is carried out in the presence of (C) a transition metal catalyst.

  The present invention also relates to a method for producing the above trans-1,4-polybutadiene, wherein the transition metal catalyst (C) is a vanadium compound.

The present invention also shows that the produced trans-1,4-polybutadiene exhibits a solid phase-solid phase crystal transition phenomenon and is heated at 200 ° C. for 10 minutes in a nitrogen atmosphere measured by a differential scanning calorimeter (DSC). After complete melting, the temperature is lowered to -30 ° C at -5 ° C / min, recrystallized, and the phase transition enthalpy ( ΔHtr ) when heated at 10 ° C / min is 50 J / g or more. It is related with the manufacturing method of said trans-1, 4-polybutadiene.

  According to the present invention, when polybutadiene having a trans-1,4-structure as a main structure is produced, the molecular weight can be adjusted without affecting the catalytic activity and physical properties other than the molecular weight of the produced polymer. A molecular weight control method can be provided.

Examples of the polymerization method that can be used for the polymerization of 1,3-butadiene of the present invention include bulk polymerization, solution polymerization, gas phase polymerization, and emulsion polymerization. Solvents for solution polymerization include aromatic hydrocarbons such as toluene, benzene and xylene, aliphatic hydrocarbons such as n-hexane, butane, heptane and pentane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, cis Examples include olefinic hydrocarbons such as -2-butene and trans-2-butene, hydrocarbon solvents such as mineral spirit, solvent naphtha, and kerosene, and halogenated hydrocarbon solvents such as methylene chloride. Further, 1,3-butadiene itself may be used as a polymerization solvent.
The solvent for solvent polymerization or the 1,3-butadiene monomer may contain a trace amount of water.

In the trans-1,4-polybutadiene of the present invention, the content of the trans-1,4 bond in the butadiene unit in the polymer chain is calculated from an IR spectrum, or a spectrum such as 1H-NMR, 13C-NMR, It is 90 mol% or more, preferably 95% or more, and more preferably 99% or more. The structure of the butadiene unit other than the trans bond may be a 1,2-vinyl bond or a cis bond, but more cis bonds are preferred.
In addition, the trans-1,4-polybutadiene of the present invention can contain a polymerized unit of the chain transfer agent component (A) ethylene in the polymer chain as long as the physical properties of the polymer are not impaired.

In the present invention, the “chain transfer agent” is introduced into the system at the time of polymerization of 1,3-butadiene, thereby reducing the molecular weight without causing a decrease in polymerization activity and without decreasing the thermophysical properties. It is a substance that works.
Here, the decrease in polymerization activity means that the yield of trans-1,3-butadiene at the same reaction time decreases or the same yield is obtained under the same reaction conditions except for the introduction of the substance. This means that the reaction time required for is increased.
Here, the decrease in thermophysical properties means the disappearance of the solid phase transition phenomenon observed by a differential scanning calorimeter (DSC), or a significant decrease in any of the solid phase transition temperature, melting point, and solid phase transition enthalpy. To do.
Here, the molecular weight is a number average molecular weight (Mn) and a weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) using styrene as a standard substance and o-dichlorobenzene as a solvent.

The trans-1,3-polybutadiene produced in the present invention has a solid phase transition temperature Ttr (° C.) and (A) trans-1, polymerized under the same conditions except that no ethylene and (B) hydrogen are added. The difference Ttr0-Ttr from the solid phase transition temperature Ttr0 (° C.) of 3-polybutadiene is 5 or less, preferably 2 or less, particularly preferably 0 or less.

Trans-1,3-polybutadiene having a melting point Tm (° C.) of trans-1,3-polybutadiene produced in the present invention and polymerized under the same conditions except that (A) ethylene and (B) hydrogen are not added The difference Tm0-Tm from the solid phase transition temperature Tm0 (° C.) is 5 or less, preferably 2 or less, particularly preferably 0 or less.

The solid phase transition enthalpy ΔHtr (J / g) of trans-1,3-polybutadiene produced in the present invention and (A) trans-polymerized under the same conditions except that no ethylene and (B) hydrogen are added. The ratio of the 1,3-polybutadiene to the solid phase transition enthalpy ΔHtr0 (J / g), ΔHtr / ΔHtr0, is 0.85 or more, preferably 0.90 or more, particularly preferably 0.95 or more.

  The composition ratio of 1,3-butadiene monomer to (A) ethylene is usually 1000: 1 to 1: 1, preferably 100: 1 to 5: 1, and particularly preferably 80: 1 to 20: 1. It is.

  The composition ratio of (A) ethylene and (B) hydrogen is usually 10: 1 to 1: 1000, preferably 5: 1 to 1:50, particularly preferably 1: 1 to 1:10. .

  Each component constituting the chain transfer agent of the chain transfer agent of the present invention is introduced into the polymerization system, for example, as a gas, dissolved in a solvent, or generated by a chemical reaction in the reaction system. be able to.

  The polymerization temperature of 1,3-butadiene in the present invention is usually -78 ° C to 110 ° C, preferably 0 ° C to 80 ° C, particularly preferably 20 ° C to 60 ° C.

  The polymerization of 1,3-butadiene in the present invention may be batch polymerization or continuous polymerization. The polymerization time in the batch polymerization is usually 1 second to 90 hours, preferably 30 seconds to 2 hours, and particularly preferably 5 minutes to 1 hour. The average residence time in the continuous polymerization is usually 5 seconds to 24 hours, preferably 30 seconds to 3 hours, and particularly preferably 5 minutes to 1 hour.

  Examples of the catalyst system component (C) transition metal compound in the present invention include a titanium compound, a vanadium compound, a chromium compound, a cobalt compound, a nickel compound, a rhodium compound, and a lanthanum compound.

  Examples of the titanium compound include titanium tetrachloride, titanium tetraiodide, tetraphenyltitanium, tetraisopropoxytitanium, tetra (diethylamino) titanium, and the like.

  Examples of vanadium compounds include vanadium triacetylacetonate, vanadium trichloride, vanadium trichloride THF complex, vanadium oxytrichloride, vanadium oxydichloride acetylacetonate, vanadium naphthenate, vanadium oxyalkoxide, and the like. it can.

  Examples of the chromium compound include tri (π-crotyl) chromium and tripropylchromium.

  Examples of the cobalt compound include cobalt dibromide and cobalt dichloride.

  Examples of the nickel compound include π allyl nickel, nickel diiodide, biscyclopentadienyl nickel, bis (1,5-cyclooctadodecyl) nickel, and the like.

  Examples of the rhodium compound include rhodium trichloride, rhodium tribromide, rhodium triacetylacetonate, and rhodium nitrate.

  Examples of the lanthanum compound include lanthanum bis (2-ethylhexyl) phosphate.

  The transition metal catalyst in the present invention can be introduced into the reaction system, for example, in the form of a liquid simple substance, dispersed in an appropriate solvent, or supported on a support.

  The molar ratio of the transition metal catalyst and butadiene in the present invention is usually from 1:10 to 1: 1000000, preferably from 1: 100 to 1: 100000, particularly preferably from 1: 500 to 1: 10000.

  In the transition metal catalyst system of the present invention, a group 1 to 3 organometallic compound in the periodic table can be used as a co-catalyst or initiator. Examples of the organometallic compound include organometallic compounds, organometallic halogen compounds, hydrogenated organometallic compounds, and alumoxanes.

  Examples of the organometallic compound include organic lithium compounds such as methyllithium, butyllithium, and phenyllithium, organic magnesium compounds such as dibutylmagnesium, organic materials such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum. An aluminum compound is mentioned.

  Examples of the organometallic halogen compound include Grignard compounds such as ethylmagnesium chloride and butylmagnesium chloride, and halogenated organoaluminum compounds such as dimethylaluminum chloride, diethylaluminum chloride, sesquiethylaluminum chloride, and ethylaluminum dichloride. . Examples of the hydrogenated organometallic compound include diethylaluminum hydride and sesquiethylaluminum hydride.

The alumoxane is a linear or cyclic polymer represented by the general formula (—Al (R) O—) _m (R is a hydrocarbon group having 1 to 10 carbon atoms, and partially halogen atoms and / or Or an organic aluminum oxy compound (including m substituted with 5 or more, preferably 10 or more). Examples of R include methyl, ethyl, propyl, and isobutyl groups, with a methyl group being preferred.

  Among the above, the promoter is preferably an organoaluminum compound, more preferably a halogenated organoaluminum compound, and particularly preferably diethylaluminum chloride and ethylaluminum sesquichloride.

  In the present invention, although not particularly limited, butadiene can be polymerized using the above catalyst system. However, copolymerization with a small amount of linear olefin, cyclic olefin, conjugated diene, or non-conjugated diene may be performed within a range not impairing the polymer physical properties. Examples of the olefin include 1-hexene, 1-octene, norbornene, cyclopentene, and trimethylvinylsilane. Examples of the conjugated diene include isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene. Examples of the non-conjugated diene include dicyclopentadiene, 5-ethylidene-2-norbornene, and 1,5-hexadiene.

  The order of addition of the catalyst component, the monomer and the chain transfer agent is not particularly limited, but it is preferable to introduce the chain transfer agent into the monomer before contacting the catalyst and the monomer.

  The trans-1,4-polybutadiene of the present invention has a number average molecular weight of 500,000 or less, preferably 1000 to 200,000.

  The trans-1,4-polybutadiene of the present invention preferably has a molecular weight distribution (Mw / Mn) of 1 to 50, particularly preferably 2 to 22.

The trans-1,4-polybutadiene of the present invention exhibits a solid phase-solid phase crystal transition phenomenon, and has a phase transition enthalpy ( ΔHtr ) measured by a differential scanning calorimeter (DSC) of 50 J / g or more, preferably 70 J. / G or more, particularly preferably 100 J / g or more.

  In addition, the trans-1,4-polybutadiene of the present invention has a crystal transition temperature from a low-temperature crystal structure to a high-temperature crystal structure of 50 to 80 ° C., preferably 60 to 80 ° C., and may vary depending on the molecular weight, microstructure, and the like. it can.

  The trans-1,4-polybutadiene of the present invention can be molded into pellets, thin plates, lamination with metal plates, hollow fibers, structures, cast films, and the like. Moreover, you may mix and use with the other polymer which does not show a phase transition phenomenon.

  In addition, the trans-1,4-polybutadiene of the present invention may be used by compounding an organic or inorganic filler by a method such as kneading, solvent casting, or polymerization in the presence of the filler.

  The trans-1,4-polybutadiene of the present invention can be used as a thermal energy storage material, a thermal stimulus relaxation material, a PTC material, and the like.

  In the examples, “yield” is a value obtained by dividing the weight of the produced trans-1,4-polybutadiene by the weight of the 1,3-butadiene monomer introduced into the reaction system.

  “Crystal phase transition point” and “crystal phase transition heat” were determined as follows. Using a differential scanning calorimeter (DSC) of SSC 5200 manufactured by Seiko Instruments Inc., a sample of about 5 mg placed in an aluminum sample pan and sealed was heated at 200 ° C. for 10 minutes in a nitrogen atmosphere. After melting, the temperature was lowered to −30 ° C. at −5 ° C./min for recrystallization. The temperature of this polymer was raised at 10 ° C./min, the temperature showing the maximum value of the endothermic peak accompanying the crystal transition was taken as the crystal transition temperature, and the total amount per unit polymer of the endotherm due to the crystal transition was taken as the crystal transition heat quantity. Further, the temperature showing the maximum value of the endothermic peak accompanying crystal melting was taken as the melting point, and the total amount per unit polymer of the endothermic quantity accompanying crystal melting was taken as the heat of fusion.

  The “number average molecular weight” was determined as follows. By gel permeation chromatography (GPC) of Waters 150C type using styrene as a standard substance (using 2 ShodexHT-806M columns manufactured by Showa Denko and 1 ShodexHT-800P as a precolumn), solvent o-dichlorobenzene at a column temperature of 135 ° C. The standard polystyrene is measured under the same conditions, and a calibration curve is created and calibrated to obtain the GPC curve.

  The number of molecular chains per V atom (index) indicates a value obtained by dividing the weight of the obtained trans 1,4-polybutadiene by the number average molecular weight and the number of moles of vanadium used. (However, since the molecular weight used here is a polystyrene standard, it is an index value approximately proportional to the number of molecular chains per true catalyst.)

The “trans-1,4 bond content” was calculated from the intensity ratio of each peak in the C ¹³ -NMR spectrum measured using EX-400 manufactured by JEOL.

When water was added into the polymerization system, the water content was determined by a coulometric titration method using a trace moisture measuring device (AQ-7 manufactured by Hiranuma Sangyo Co., Ltd.).

(Examples 1 to 4) A small pressure polymerization apparatus having an internal volume of 15 ml was sufficiently purged with nitrogen, then 2 ml of toluene was added, and 0.05 mmol (0.05 M toluene solution) of diethylaluminum chloride (DEAC) was added as a promoter. , After introducing hydrogen at a predetermined pressure, 2 ml of butadiene (Bd) was added. After heating the inside of the reaction vessel to 35 ° C., 0.01 mmol (0.01 M) of vanadium oxytrichloride (VOCl 3) was added as a catalyst to start polymerization, and at the same time, ethylene at a predetermined pressure was introduced. The polymerization operation was performed in a closed system at 35 ° C. for 15 minutes in a nitrogen atmosphere. After stopping the polymerization reaction by injecting 6 ml of ethanol, the whole reaction solution was added to 15 ml of ethanol (100 ppm additive of anti-aging agent Irganox 1076) to precipitate and collect the polymer. The recovered polymer was washed with ethanol and dried.
As shown in Table 1, a chain transfer effect was produced by the coexistence of ethylene and hydrogen.

(Comparative example 1) It carried out like Examples 1-4 except that ethylene and hydrogen were not added. (Table 1) The microstructure of the polymer produced was 99.0% trans-1,4 bond, 0.8% cis-1,4 bond, and 0.3% 1,2-bond.

(Comparative Examples 2-6) It carried out similarly to Examples 1-4 except not having added ethylene. As shown in Table 1, no chain transfer effect was observed with hydrogen alone.

(Comparative Examples 7-9) It carried out similarly to Examples 1-4 except not having added hydrogen. As shown in Table 1, no increase in the number of molecular chains is observed at an ethylene partial pressure of 1 bar. Further, when the ethylene partial pressure was increased, the thermophysical properties were lowered.

(Comparative Examples 10-12) The same operation as in Comparative Example 1 was conducted except that dimethyl sulfoxide (DMSO) was added. As shown in Table 2, the number average molecular weight decreased, but the activity decreased, and the number of molecular chains per V atom also decreased.

Comparative Examples 13 to 15 Comparative Examples 13 to 15 were carried out in the same manner as Comparative Example 1 except that cyclooctadiene (COD), which is a nonconjugated diene, was added. As shown in Table 2, the number average molecular weight decreased, but the activity decreased, and the number of molecular chains per V atom also decreased.

(Examples 5-7)
A pressure polymerization apparatus with an internal volume of 2L was fixed and installed after fixing a glass ampule filled with vanadium oxytrichloride (0.3mmol / 0.2M dehydrated toluene solution) inside, and the inside of the apparatus was sufficiently replaced with nitrogen. After that, 800 ml of dry toluene was introduced. Next, 200 ml of butadiene was introduced, and 1.5 mmol of diethylaluminum chloride (DEAC: 1 M toluene solution) as a cocatalyst was further added. After the inside of the reaction vessel was heated to 35 ° C., hydrogen and ethylene at a predetermined partial pressure were introduced, and polymerization was started by crushing the catalyst glass ampoule. The polymerization operation was performed in a sealed manner at 35 ° C. for 15 minutes in a nitrogen atmosphere. After terminating the polymerization reaction by injecting 5 ml of ethanol, the entire reaction solution was added to 1 L of ethanol (additive of anti-aging agent Irganox 1076 700 ppm) to precipitate and collect the polymer. The recovered polymer was washed with ethanol and dried. The results are shown in Table 3 and Table 4. A chain transfer effect of thermophysical properties was obtained.

(Comparative Examples 16-21)
The same procedure as in Examples 5 to 11 was performed except that either hydrogen or ethylene or both were not added. The results are shown in Table 3 and Table 4. When only hydrogen is added, the molecular chain does not increase, and it is clear that hydrogen alone has no chain transfer effect. In addition, when only ethylene is added, the weight average molecular weight does not decrease, and when the gas phase partial pressure is 1 kgf / cm 2 where the chain transfer effect is significant in terms of the number of molecular chains, the thermophysical properties are decreased. occured.

(Example 8)
Using a combination of toluene containing saturated water as a solvent and dry toluene, except that about 0.044 to 0.047 mmol (Al / H2Omol ratio: 0.33 to 0.34) of water was present in the polymerization system, It carried out similarly to Examples 5-11. The results are shown in Tables 5 and 6. A chain transfer effect has occurred.

(Comparative Example 22)
The same operation as in Example 8 was performed except that hydrogen and ethylene were not added. The results are shown in Tables 5 and 6.

Example 9
The same procedure as in Example 8 was performed except that the water content in the polymerization system was about 0.024 to 0.030 mmol (Al / H2Omol ratio: 5.0 to 6.3). The results are shown in Tables 7 and 8. A chain transfer effect has occurred.

(Comparative Example 23)
The same operation as in Example 11 was performed except that hydrogen and ethylene were not added. The results are shown in Tables 7 and 8.

(Examples 12 to 17)
Example 8 except that vanadium oxytrichloride (0.1 mmol / 0.2 M dehydrated toluene solution) was used as the catalyst and 2.0 mmol of ethylaluminum sesquichloride ((EASC: 1 M toluene solution) was used as the cocatalyst. The results were the same and the results are shown in Tables 9 and 10. A chain transfer effect has occurred, and Figures 1 and 2 show the DSC and NMR spectra of the polymer of Example 16.

(Comparative Examples 24-28)
The same procedure as in Example 11 was performed except that one or both of hydrogen and ethylene were not added. The results are shown in Tables 9 and 10. When only ethylene is added, a decrease in thermophysical properties and an increase in weight average molecular weight (Mw) are observed.

The DSC spectrum of the trans-1,4-polybutadiene of Example 16 was shown.

The NMR spectrum of the trans-1,4-polybutadiene of Example 17 was shown.

Claims (4)

In the production of polybutadiene having a trans-1,4 bond structure in which 90% or more of butadiene units are polymerized by polymerization of 1,3-butadiene, the molecular weight is increased by using (A) ethylene and (B) hydrogen as chain transfer agents. A process for producing trans-1,4-polybutadiene, characterized by adjusting. The method for producing trans-1,4-polybutadiene according to claim 1 , wherein the polymerization of 1,3-polybutadiene is carried out in the presence of (C) a transition metal catalyst. The process for producing trans-1,4-polybutadiene according to claim 2 , wherein the transition metal catalyst (C) is a vanadium compound. The produced trans-1,4-polybutadiene exhibits a solid phase-solid phase crystal transition phenomenon, and is completely melted by heating at 200 ° C. for 10 minutes in a nitrogen atmosphere measured by a differential scanning calorimeter (DSC). after recrystallized lowered to -30 ° C. at -5 ° C. / min, the phase transition enthalpy in the case of raising the temperature at 10 ° C. / min (ΔHtr) is such that 50 J / g or more, according to claim 1 A process for producing trans-1,4-polybutadiene as described in 2 or 3 .

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