JP3985099B2 - Method for drying trace volatile content of ethylene oxide-butylene oxide copolymer resin and ethylene oxide-butylene oxide copolymer resin dried by the method - Google Patents

Description

  The present invention relates to a method for drying a small amount of volatile components of an ethylene oxide-butylene oxide copolymer resin, and an ethylene oxide-butylene oxide copolymer resin dried using the method.

  An ethylene oxide-butylene oxide copolymer (hereinafter referred to as EO / BO copolymer) resin may exhibit excellent electrochemical characteristics, and is useful as a material for electrochemical devices such as batteries. It is attracting attention. However, since the organic solvent and moisture contained in the resin are closely related to the physical properties and electrical characteristics of the resin, reduction thereof is an important issue.

  As a method for drying the resin, for example, as disclosed in JP-A-7-316223, a method of allowing dry air to flow into a pellet-like or powder-like resin product stored in a storage tank is used. Yes. However, this method has a problem that it is difficult to dry the resin product evenly in a short time, and the drying efficiency is low.

Japanese Patent Application Laid-Open No. 2002-1727 discloses that a heated gas is blown into a resin pellet storage tank, and the state is maintained and allowed to stand. After standing for a certain period of time, the pellet in the storage tank is extracted and returned to the storage tank. A method of performing such a cycle has been proposed. Such a hot air drying method does not contain an organic solvent in the atmosphere, and is therefore suitable for removing an organic solvent such as heptane and drying the resin. However, when water is removed, it is difficult to dry to 1% (thousands of ppm) or less, especially to several hundreds of ppm or less, because it contains moisture in the atmosphere. . In addition, extracting the pellet from the storage tank and circulating it back to the storage tank has a problem that a large-scale apparatus is required because the resin is not in contact with the atmosphere.
JP 7-316223 A JP 2002-1727 A

  In view of the above, an object of the present invention is to provide an efficient drying method capable of removing even a small amount of moisture from a resin with a relatively simple apparatus.

The drying method of the present invention is a method for drying an ethylene oxide-butylene oxide copolymer resin containing a small amount of volatile matter, and in order to solve the above-mentioned problems, the resin is charged in a substantially conical type or a substantially cylindrical type. When using an apparatus equipped with an evaporating tank and a stirring blade that revolves along the wall surface while rotating, the inside of the evaporating tank is depressurized and dried while stirring the resin with the stirring blade. A dry gas having a dew point of −40 ° C. or less as a gas from the lower part of the evaporation tank is within a range of 0.1 to 3.0 in terms of the ratio of the resin charge (gas amount (L / min) / charge amount (kg)) it is intended to introduce in to become a flow rate (claim 1).

In the drying method, the inside of the evaporation tank is preferably decompressed to a pressure of 5 to 40 kPa (Claim 2). More preferably, the temperature of the carrier gas is adjusted within a range of ± 10 ° C. of the crystallization temperature of the resin to be dried (hereinafter referred to as Tc). Moreover, melting or deterioration of the resin can be prevented by performing low speed stirring or intermittent stirring (Claim 4).

When performing the said drying method, drying required time can be estimated based on following formula (1).

In the formula (1), a is the initial volatile concentration (ppm), b is the target volatile concentration (ppm), c is the charged amount (kg), d is the drying coefficient (kg / L), e is the amount of gas introduced ( L / min), respectively, and the drying coefficient d is obtained from the following equation;

However, the unit of each numerical value is as follows;
Volatile concentration: ppm, charge amount: kg, time: min, gas introduction amount: L / min

  The ethylene oxide-butylene oxide copolymer resin of the present invention is one dried by any one of the above drying methods.

  According to the drying method of the present invention, it is possible to efficiently remove a minute amount of moisture from the resin by efficiently using a relatively simple apparatus.

By operating in a reduced pressure system, trace solvent components can be removed at a low product temperature, preventing thermal degradation of the resin, and introducing a dry gas from the bottom to keep the trace amount in the system. The solvent gas component can be efficiently discharged out of the system (claims 1 and 2).

  Further, by adjusting the temperature of the carrier gas within (Tc ± 10) ° C. of the resin, it is possible to dry efficiently and prevent the resin from being softened (Claim 3).

  Further, by performing low-speed stirring or intermittent stirring, resin melting and mechanical deterioration due to heat generated by continuous stirring can be prevented (claim 4).

  Further, the end point management of the removal operation is facilitated by estimating the time required for removing the trace solvent component to the target value.

  The EO / BO copolymer resin obtained by the above drying method has excellent physical properties and electrochemical characteristics, and can be useful as a material for electrochemical devices (claim 6).

  The EO / BO copolymer resin to which the present invention is applied refers to those obtained by addition copolymerization of ethylene oxide, butylene oxide and glycidyl ethers, and within the scope of not impairing the object of the present invention. Monomers may be included. The constituent ratios of ethylene oxide, butylene oxide and glycidyl ethers in the copolymer are not particularly limited. For electrochemical applications, ethylene oxide is 90 to 95% by weight, butylene oxide is 3 to 10% by weight, and glycidyl ethers are 0 to 5% by weight. % Is generally used. The molecular weight of the resin (referring to the weight average molecular weight, hereinafter the same) is usually about 20,000 to 500,000, preferably about 20,000 to 200,000. The form of the resin is not particularly limited, and pellets and powder are generally used, but granular materials and pulverized materials may be used.

  The drying apparatus used in the present invention uses an apparatus comprising an evaporating tank and a stirring blade that revolves around the evaporating tank while rotating. An outline of the apparatus will be described with reference to the drawings.

  In FIG. 1, reference numeral 10 denotes an evaporation tank into which resin is introduced, reference numeral 11 denotes a resin introduction port, reference numeral 12 denotes a resin discharge port, reference numeral 20 denotes a stirring device, reference numeral 21 denotes a rotating shaft, reference numeral 22 denotes an arm, and reference numeral 23 denotes stirring. Reference numeral 30 denotes a jacket filled with a heat medium, reference numeral 40 denotes a carrier gas supply source such as a cylinder, reference numeral 41 denotes a carrier gas introduction pipe, and reference numeral 50 denotes a resin supply source such as a pellet storage container.

The stirring device 20 is provided with an arm 22 perpendicular to the rotating shaft 21 and a screw-type stirring blade 23 provided at the tip of the arm 22 at an acute angle. The agitating blade 23 rotates (revolves) in the evaporation tank 10 along the wall surface according to the arm 22 while rotating (rotating) about its own axis. By performing such a stirring operation, the resin is sufficiently stirred in the evaporation tank, and efficient drying becomes possible. In the apparatus shown in FIG. 1, the evaporation tank has a substantially conical shape, and the stirring blades 23 are inclined along the inclination of the wall surface. However, the shape of the apparatus is not limited to this. For example, the evaporation tank may be substantially cylindrical, and in this case, the stirring blade is provided in a direction perpendicular to the arm along the wall surface. Is preferred.

  When the resin is dried using the apparatus as described above, the inside of the evaporation tank is reduced to a pressure of about 5 to 40 kPa and cooled as necessary to keep the temperature in the tank (product temperature) below the Tc of the resin. However, it is preferable to introduce a carrier gas into the tank.

  When operated in a reduced pressure system in this way, trace solvent components can be removed even when the product temperature is low, so that thermal degradation of the resin can be prevented. Moreover, softening of the resin can be prevented by keeping the temperature of the resin below Tc.

  As the carrier gas to be introduced, a dry gas having a dew point of −40 ° C., more preferably −60 ° C. or less is used. The type of dry gas is not particularly limited as long as it does not have reactivity with the resin, and examples thereof include air, nitrogen, helium, argon, carbon dioxide gas, etc. From the viewpoint of cost, air, nitrogen Is preferred. By introducing such a dry gas from the bottom to the top of the evaporation tank, it is possible to extract a trace amount of the solvent gas component remaining in the system into the dry gas and efficiently discharge it outside the system. . The flow rate of the carrier gas is preferably 0.1 to 3.0 as a ratio (gas amount (L / min) / charge amount (kg)) to the charge amount of the resin.

When the room temperature is low, the carrier gas can be dried efficiently by heating and introducing. The temperature is preferably (Tc-10) ° C. or higher, more preferably Tc or higher. However, the softening of the resin in order was proof member is preferably (Tc + 10) ℃ or less.

  In order to prevent fusion or mechanical or thermal deterioration due to softening of the resin, low-speed stirring or intermittent operation can be performed. When performing low speed stirring, for example, it is preferable to stir at a rotation speed of 10 to 50 rpm and a revolution speed of 1.0 to 3.0 rpm. The intermittent operation is to alternately perform operation and stop, and the operation time is 5 to 15 minutes and the stop time is about 10 to 60 minutes.

  Once the flow rate of the introduced gas and the drying temperature are determined, the drying coefficient d is determined experimentally, so that even if the initial volatile concentration (ppm) and the amount of charge (kg) before drying are changed, the estimation formula (1) is used. Time estimation is possible. Therefore, the end point management of the removal operation becomes easy. However, the range in which the drying coefficient d can be used is a range where the gas amount relative to the charged amount (gas amount (L / min) / charged amount (kg)) is 0.1 to 3.0.

  In addition, when the volatile matter density | concentration after drying falls below a target volatile matter density | concentration, a suitable quantity of solvent can be added and it can adjust within the range of a target volatile matter density | concentration. As a method for adding the solvent, it is preferable to spray by providing a nozzle having a spray function in the evaporation tank from the viewpoint of making the volatile content uniform and efficiency, and the nozzle revolves together with the revolution shaft to remove the solvent. It is preferable to arrange the spray blades to spray forward in the direction of travel (revolution direction). In order to adjust the addition amount of the solvent, the necessary amount may be weighed and transferred to a container and then supplied, or directly supplied while adjusting the flow rate from a supply source (for example, water supply) using a flow meter. May be. Moreover, it is preferable that a solvent addition rate exists in the range of 10-150 weight ppm / min with respect to resin. If it is less than 10 ppm by weight, the efficiency is poor, and if it exceeds 150 ppm by weight, the resin may be dissolved or expanded and aggregated. The method described here can also be applied to volatile concentration adjustment when the initial volatile concentration is less than or equal to the target volatile concentration. Further, the volatile component concentration adjustment (humidification) when the solvent is water can be achieved by introducing a gas having humidity (for example, air) into the evaporation tank.

  Examples of the present invention are shown below, but the present invention is not limited thereto.

  In the following examples and comparative examples, the moisture concentration in the pellets was measured by the Karl Fischer method. Specifically, the resin was dissolved in dehydrated toluene to prepare a solution having a solid concentration of 10% by weight, and the water content was measured with Hiranuma Sangyo Co., Ltd. Hiranuma trace moisture measuring device AQ-2000. This measured value was corrected by the moisture content of dehydrated toluene measured separately.

  The crystallization temperature (Tc) was measured by thermal analysis (DSC), and the molecular weight was measured by GPC analysis.

  Thermal analysis was performed using DSC220C manufactured by Seiko Instruments Inc. As measurement conditions, the temperature was raised from room temperature to 100 ° C. at a rate of 10 ° C./min under a nitrogen atmosphere, held at 100 ° C. for 1 minute, and then from 100 ° C. to −20 ° C. at a rate of 5 ° C./min. The temperature was lowered and the temperature at which the exothermic peak reached the peak during this period was measured, and this was taken as the crystallization temperature.

The measurement conditions for GPC are as follows:
Column: Guard column PWXL + G5000PWXL
+ G4000PWXL + G3000PWXL
+ G2500PWXL (above, manufactured by Tosoh Corporation)
Column size: 7.8mmφ × 30cm
Column temperature: 40 ° C
Eluent: acetonitrile / 0.08M-sodium acetate solution = 50/50 (solution ratio)
Flow rate: 1.0 ml / min
Detector: Differential refraction detector Standard material: Polyethylene oxide manufactured by Tosoh Corporation, molecular weight 20,000 to 900,000

[Synthesis Example 1]
A pressurized reaction vessel equipped with a stirrer is charged with 150 kg of dehydrated toluene, added with 27 g of sodium methylate as a catalyst, heated to 100 ° C., adjusted to a pressure of 200 kPa or less and a temperature of 120 ° C. or less, ethylene oxide, 1 , 2-butylene oxide and allyl glycidyl ether were sequentially added at a ratio of 90: 7: 3 (weight ratio) to a total of 100 kg to obtain a resin (polymer) solution.

[Example 1]
The solvent was removed from the polymer solution obtained in Synthesis Example 1 under reduced pressure, and after forming into a sheet, the pellet was obtained by cutting. The polymer had a Tc of 22 ° C. and a molecular weight of 100,000.

  100 kg of the obtained pellets were charged into 200 L of a conical mixing stirrer SV mixer, cold water was passed through the jacket of the SV mixer, the inside of the tank was brought to 20 ° C., the inside of the tank was reduced to 12 kPa, and then, 300 L / min of nitrogen was introduced. Stirring was performed intermittently (running: 10 minutes, pause: 10 minutes) at a rotation of 0.8 kW and a revolution of 0.2 kW.

The drying time was estimated by using a drying coefficient of 3.67 × 10 ⁻³ to estimate the time to reach a target moisture of 200 ppm. As for the drying coefficient, 130 kg of resin pellets were charged into a 200 L conical mixer / stirrer, cold water was passed through the jacket of the SV mixer, the inside of the tank was brought to 20 ° C., the inside of the tank was decompressed, and 300 L / min of nitrogen was introduced Then, the drying operation was performed, and the moisture concentration before and after drying, the amount charged, the drying time, and the amount of gas introduced were obtained. Table 1 shows the moisture concentration before and after drying, the drying time, and the deviation from the target value.

[Example 2]
When the same pellets used in Example 1 were left in the atmosphere and absorbed, the moisture was absorbed and the water content became 7658 ppm.

  100 kg of the pellets were charged into a conical mixing stirrer SV mixer 200L. Drying was performed under the same conditions as in Example 1 by estimating the time to reach a target moisture of 200 ppm.

[Synthesis Example 2]
Polymerization was performed under the same conditions as in Synthesis Example 1 except that the monomer composition (weight ratio) was changed to EO: BO = 92: 8 to obtain a polymer solution.

[Example 3]
The solvent was removed from the polymer solution obtained in Synthesis Example 2 under reduced pressure, and after forming into a sheet, the pellet was polymerized by cutting. The pellet had a Tc of 18 ° C. and a molecular weight of 110,000.

1000 kg of the obtained pellets were charged into a conical mixing stirrer (Nauter mixer DBX-2000RWV: manufactured by Hosokawa Micron Corporation) 2000L. Cold water was passed through the jacket of the Nauter mixer, the inside of the tank was brought to 20 ° C., and the inside of the tank was decompressed before introducing 300 L / min of nitrogen. Stirring was performed intermittently (running: 10 minutes, pause: 10 minutes) at a rotation of 2.0 kW (21.5 rpm) and a revolution of 0.75 kW (1.8 rpm). Using a drying coefficient of 3.67 × 10 ⁻³ , the time required to reach a target moisture of 200 ppm was estimated and dried.

[Comparative Example 1]
50 kg of the same resin pellets prepared in Example 1 were charged into a conical mixing stirrer SV mixer 200L. Except for the charged amount, the same conditions as in Example 1 were used to estimate the time to reach the target moisture of 200 ppm, and drying was performed.

[Comparative Example 2]
100 kg of the same resin pellets prepared in Example 3 were charged into a conical mixing stirrer SV mixer 200L. Using the same conditions as in Example 1 except that the amount of nitrogen gas introduced was changed from 300 L / min to 5 L / min, the time when the target moisture was 200 ppm was estimated and dried.

  The ethylene oxide-butylene oxide copolymer resin dried by the drying method of the present invention is suitably used for electrochemical applications.

It is a schematic cross section which shows the outline | summary of the drying apparatus used by this invention.

Explanation of symbols

A: Drying device 10 ... Evaporation tank 11 ... Resin inlet 12 ... Resin outlet 20 ... Stirrer 21 ... Rotating shaft 22 ... Arm 23 ... Stirring blade 30 ... Jacket 40 ... Carrier gas Supply source 41 …… Carrier gas introduction pipe 50 …… Resin supply source

Claims (6)

A method for drying an ethylene oxide-butylene oxide copolymer resin containing a small amount of volatile matter, comprising:
While using a device provided with a substantially conical or substantially cylindrical evaporation tank into which resin is charged and a stirring blade that revolves along the wall surface while rotating , the resin is stirred with the stirring blade. When drying, the inside of the evaporation tank is depressurized, and a dry gas having a dew point of −40 ° C. or less as a carrier gas is supplied from the lower part of the evaporation tank to the resin charge (gas amount (L / min) / charge amount (kg )) Is introduced at a flow rate in the range of 0.1 to 3.0 . The drying method according to claim 1, wherein the inside of the evaporation tank is depressurized to a pressure of 5 to 40 kPa. 2. The drying method according to claim 1 , wherein the temperature of the carrier gas is adjusted within a range of crystallization temperature (Tc) ± 10 ° C. of the resin to be dried.   4. The drying method according to claim 1, wherein melting or deterioration of the resin is prevented by performing low-speed stirring or intermittent stirring. The drying method according to any one of claims 1 to 4, wherein the time required for drying is estimated based on the following formula (1).

In the formula (1), a is the initial volatile concentration (ppm), b is the target volatile concentration (ppm), c is the charged amount (kg), d is the drying coefficient (kg / L), e is the amount of gas introduced ( L / min), respectively, and the drying coefficient d is obtained from the following equation;

However, the unit of each numerical value is as follows;
Volatile concentration: ppm, charge amount: kg, time: min, gas introduction amount: L / min   An ethylene oxide-butylene oxide copolymer resin, which is dried by the drying method according to any one of claims 1 to 5.

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