KR100944428B1 - Process for Preparing Polytetramethylene ether glycol with Low Molecular Weight Distribution - Google Patents

Abstract

The present invention relates to a method for producing polytetramethylene ether glycol from tetrahydrofuran (THF) using a heteropoly acid (HPA) catalyst layer, wherein polytetramethylene ether glycol having a molecular weight of 300 to 2,000 Daltons by ring-opening polymerization of tetrahydrofuran. Generating a first reaction step; And

And a second reaction step of chain-extending the polytetramethylene ether glycol produced in the first reaction, the second reaction step being connected in parallel with a column capable of removing water, and attaching a heteropolyacid catalyst to the surface. It provides a production method made in a tubular reactor. In addition, according to the production method of the present invention, polytetramethylene glycol having a narrow molecular weight distribution (Mw / Mn) can be prepared.

Heteropoly acid, polytetramethylene glycol, molecular weight distribution, chain extension reaction, HPA catalyst adhesion

Description

Process for Preparing Polytetramethylene ether glycol with Low Molecular Weight Distribution

The present invention relates to a method for preparing polytetramethylene ether glycol (hereinafter referred to as "PTMG") from tetrahydrofuran (THF) using a heteropolyacid (HPA) catalyst layer, the polymerization in the first reaction step The present invention relates to a method for producing PTMG having a narrow molecular weight distribution with easy molecular weight control by performing a second reaction step, which is a reaction of a polymer and a chain extension reaction in a state where a monomer is removed.

There are several methods of polymerizing PTMG, which is currently used as a spandex main material. The method of producing PTMG in one-step using a heteropoly acid (hereinafter referred to as "HPA") catalyst and silica alumina (Sillica) Alumina) is used to generate PTMEA and displace the terminal to generate PTMG. The main factor in determining the process of producing PTMG is the type of catalyst. That is, the process is determined by which catalyst is used and how it is controlled.

In other words, the molecular weight distribution is determined according to the type of the process and by using this the molecular weight distribution is determined. However, PTMG, which is required by spandex, maintains uniformity of physical properties when the molecular weight distribution is narrow in the required physical properties, and thus has advantages in low temperature characteristics and process progress. In addition, there is an advantage that can be advantageous to the uniformity of the spandex quality using the same. Therefore, the conventional techniques have a part for explaining a method for controlling the molecular weight distribution, and in particular, according to Canadian Application No. 800 659, a polymer having a relatively narrow molecular weight distribution can be obtained by stopping the polymerization before reaching equilibrium. According to German patent 2453114 it is possible to partially biodegrade the polymer with an acidic cation exchanger to reduce polydispersity. Other patent applications, such as U.S. Patent No. 4510333 or German Patent No. 4205984, describe polymerization carried out at step reaction temperatures to narrow the molecular weight distribution. In addition, according to Korean Patent No. 422177, tetrahydrofuran polymer or tetrahydrofuran alkyl, characterized by mixing the starting polymer with cycloalkane methanol and water and separating the different phases generated when mixing at a temperature of 40 ~ 80 ℃ A technique for classifying lene oxide copolymers is specified.

However, the above-described techniques are difficult to control the product in the middle of the reaction and after the reaction by adding an additive for separation of molecular weight requires a separate additive removal process, which may be affected by another impurity in the post-processing.

Accordingly, the present invention is to provide a method for easily controlling the polytetramethylene glycol molecular weight distribution and additionally easy to move the number average molecular weight (Mn) value without the addition of additives.

The present invention ultimately results in a primary reaction of ring-opening polymerization of tetrahydrofuran (THF) with an HPA catalyst, whereby the molecular weight distribution is controlled using a self-reaction of the resulting polymer, i. It is an object of the present invention to provide a method for controlling the target molecular weight by controlling the extension reaction.

According to a preferred embodiment of the present invention, a method for producing polytetramethylene ether glycol from tetrahydrofuran (THF) using a heteropolyacid (HPA) catalyst layer, wherein the tetrahydrofuran is ring-opened polymerized to have a molecular weight of 300 to 2,000 Daltons. A first reaction step of producing polytetramethylene ether glycol; And

And a second reaction step of chain-extending the polytetramethylene ether glycol produced in the first reaction, the second reaction step being connected in parallel with a column capable of removing water, and attaching a heteropolyacid catalyst to the surface. It provides a process for producing polytetramethylene ether glycol, characterized in that it is made in a tubular reactor.

According to another suitable embodiment of the present invention, the polytetramethylene ether glycol produced in the first reaction has a molecular weight of 5 to 50 wt% of the molecular weight of the polytetramethylene ether glycol after the second reaction. Provided are methods for preparing glycols.

According to another suitable embodiment of the present invention, the secondary reaction provides a process for producing polytetramethylene ether glycol, wherein the tetrahydrofuran is removed in a tubular reactor.

According to another suitable embodiment of the present invention, the secondary reaction temperature provides a process for producing polytetramethylene ether glycol, characterized in that 50 ~ 70 ℃.

According to another suitable embodiment of the present invention, the molecular weight distribution (Mw / Mn) of the polytetramethylene ether glycol produced in the final production is polytetra, characterized in that 5 to 30% of the molecular weight distribution produced in the first reaction step Provided is a method for producing methylene ether glycol.

Polytetramethylene ether glycol is a polymer that can be used as a raw material, an oil additive, or a softener of polyurethane, and the width of the molecular weight range (Range) is required to vary in width and distribution. In particular, in the case of spandex having the highest utilization of PTMG, the lower the molecular weight and the lower the molecular weight distribution, the better the mechanical properties, the low temperature properties of the yarn, and the recovery properties. For the expression of these properties, it is easier to control in a separate second reaction step than the change in the first reaction step, and it is possible to generate PTMG with a narrow molecular weight distribution than the existing molecular weight distribution and to make a simple process configuration. It was.

Hereinafter, the present invention will be described in detail by using examples, but the examples presented are for a clear understanding of the present invention and are not intended to limit the scope of the present invention.

1 shows a polymerization apparatus of polytetramethylene ether glycol according to the present invention.

Referring to FIG. 1, a continuous polymerization apparatus for preparing polytetramethylene ether glycol includes a primary reactor 1, a phase separation vessel 2, a monomer separation and water removal column 3, and a secondary reactor 4. ) Is included.

Catalysts that can be used in the process for producing PTMG according to the present invention include heteropolyacids (HPA). Generally, 20 to 40 molecules of water per unit molecule of HPA are coordinated, but this type of HPA cannot effectively induce the polymerization of tetrahydrofuran (THF). Therefore, in order to properly induce the polymerization of tetrahydrofuran, the number of water molecules coordinated to a heteropoly-anion needs to be controlled. In order to control the number of water molecules coordinated to a heteropoly acid, the heteropoly acid is heated to a temperature of, for example, 100 to 300 ° C. as is generally used as a method of changing the activity of the catalyst. The heating temperature and the heating time can be adjusted according to the number of water molecules to be coordinated, but can be adjusted such that the coordination number of water molecules to heteropoly acid is 3 to 18, for example.

Tetrahydrofuran is first introduced into the first reactor (1). Tetrahydrofuran can be prepared, for example, from 1,4-butanediol. However, tetrahydrofuran used in the preparation of PTMG according to the invention can be prepared according to methods known in the art. The prepared tetrahydrofuran is introduced into the primary reactor (1) with water. Then, the heteropolyacid with the coordination number of water is added to the first reactor 1 again. The amount of water present on the catalyst in the reactor 1 can be adjusted so that the coordination number of the water is 3 to 18.

As the polymerization reaction proceeds, the amount of water may be reduced. Therefore, water may be added so that the polymerization reaction can proceed in a state having a constant number of coordination water. If the amount of water is present so that the coordination number of water to heteropoly-anion is 20 or more, or the molar ratio of water to heteropoly acid is 0.1 or less, the efficiency of the polymerization reaction can be significantly reduced. The amount of water added may be determined depending on the progress of the polymerization reaction.

The molecular weight of PTMG produced in the reaction system is 300-2,000 Daltons to form a molecular weight of 0.05 ~ 0.5 times the final molecular weight to be produced.

 In the next step, the reactant and the catalyst are transferred to the mixed phase in the specific gravity separator 2 and the phase separation occurs in the catalyst layer and the polymer layer by having a constant residence time in the specific gravity separator. At this time, the catalyst layer is reduced to the primary reactor 1 and the polymer layer is transferred to the residual catalyst removal process.

In the residual catalyst production process, the catalyst remaining on the polymer is removed by passing through a filter, an ion resin tower, and the like, and the produced polymer is introduced into a secondary reactor including an unreacted monomer and a water removal column. Difference reactions (chain extension reactions) occur.

The type of secondary reactor is a tube type to which the HPA catalyst is attached, that is, a heat exchanger shell and tube type. In order to increase the efficiency of the HPA catalyst, THF: HPA is injected at a ratio of 10: 1 (weight ratio) of the HPA catalyst dissolved in THF to the total surface area of the heat exchanger tube side of the secondary reactor. Thereafter, the temperature is raised to 150 ° C to 180 ° C at 10 ° C / min at room temperature and circulated using a pump. At this time, the total amount of the mixed solution to be added is adjusted so that the catalyst content is 1 kg per 1 m ² relative to the surface area of the tube side. After THF is evaporated, the temperature is maintained at 150 ° C. to 180 ° C. for about 2 hours, and then the temperature is lowered to obtain a secondary reactor in which a catalyst is attached. In this type of secondary reactor, a catalyst having a coordination number of 1 or less adheres to the surface of the reactor, thereby forming a condition sufficient to cause chain extension reaction of PTMG. Artificially bonded HPA catalysts do not dissolve on PTMG or monomers, so after the chain extension reaction, PTMG can be used without a separate purification process.

The reaction residence time in the secondary reaction is within 0.1 ~ 1 hour, the reaction occurs in a very short time, the molecular weight and molecular weight distribution is controlled by the reaction temperature, the reaction contact length.

Efficient removal of water molecules by end elimination of PTMG produced in the chain extension reaction is the biggest factor in determining the uniformity of the reaction.

When the chain extension reaction occurs in the present invention, since the H ₂ O molecules are generated as by-products after the reaction, the step of removing water at the same time as the preliminary reaction must be included.

Water molecules in the reaction are removed on the column connected to the secondary reactor, and the conditions of the column are controlled so that the water content in the reaction system is 100 ppm or less. The molecular weight produced after the reaction is 1500 ~ 10,000 Daltons can be adjusted according to the user's convenience.

In order to control the molecular weight, it is possible to control the desired molecular weight by adjusting the residence time by installing equipment that can exhibit representative characteristics of PTMG molecular weight such as NIR on-line.

 In the present invention, the use of a secondary reactor in the manufacturing process causes a reaction between the PTMG chains, resulting in a more uniform molecular weight distribution. In other words, PTMG having a molecular weight of 300 ~ 2,000 Daltons in the first reaction can be produced, and a chain extension reaction (addition reaction) of the PTMG generated in the first reaction can be formed to form a desired molecular weight. As the desired molecular weight, various molecular weights can be obtained from 1,500 to 10,000 Daltons, and the molecular weight distribution value of the produced PTMG is 1.2 to 1.4, which is more uniform than 1.4 to 1.5 generated in the previous step (first reaction). This makes it possible to produce PTMG with a uniform distribution, which can be expected to be excellent mechanical properties in the post-processing process. In this case, the mechanical property is the reaction of PTMG and MDI in the first polymerization of the spandex process. When the molecular weight distribution resulting in the equivalent reaction is low, a uniform primary polymer can be produced after the equivalent reaction. It acts advantageously in regulation and the like. In addition, if the molecular weight distribution is narrow, the ratio of melting to a solvent (Solvent) by maintaining a low viscosity can be increased, which acts as a factor that can lower the cost in the process.

In addition, in the existing process, if it is necessary to move the specification of the product produced in the actual process, it takes time to adjust the variables in the reaction stage and to replace the molecular weight of each stream, but the present invention In the case of the molecular weight can be shifted only by adjusting the residence time in the post-reaction unless the median is adjusted to a large width (more than 2000 Daltons). That is, the molecular weight distribution can be adjusted only by adjusting the residence time in the secondary reaction without significantly changing the molecular weight in the primary reaction.

Examples for the present invention are described below.

Preparation Example of Secondary Reactor

The secondary reactor is a heat exchanger shell and tube type, and the HPA catalyst dissolved in THF with a THF: HPA of 10: 1 (weight ratio) is added to the total surface area of the heat exchanger tube side of the secondary reactor. Thereafter, using a pump while circulating at room temperature to 10 ℃ / min to 150 ℃. At this time, the total amount of the mixed solution to be added is adjusted so that the catalyst content is 1 kg per 1 m ² relative to the surface area of the tube side. After THF is evaporated, the temperature is maintained at 150 ° C. for 2 hours and then lowered to obtain a secondary reactor in which a catalyst is attached.

Example 1

60 kg of tetrahydrofuran monomer was charged to the reactor and 60 kg of phosphotungstic acid was added to the first reactor with a small amount of water equal to the number of moles of catalyst and PTMG produced. The temperature of the reactor was maintained at 60 ° C. At this time, as the tungsten acid in the reactor, a coordination number of 7 was used. After 24 hours of continuous operation of the stirrer, THF monomer was continuously supplied at a rate of 6 kg / hour, and the catalyst layer and the PTMG mixture were sent to the specific gravity separator, and the catalyst layer was recovered into the first reactor. Then, the PTMG without the catalyst was transferred to a secondary reactor to which a column was attached and to which the catalyst was attached in this manner. The PTMG produced in the first reactor had a molecular weight (Mn) of 300 Daltons and a molecular weight distribution (Mw / Mn) of 1.49. The secondary reactor transported the PTMG produced in the secondary reactor to the storage tank while controlling the residence time to 20 minutes while maintaining the reaction temperature of 60 ℃. At this time, the molecular weight of PTMG produced through the secondary reactor was 1800, and the molecular weight distribution was 1.30.

Comparative Example 1

 As in Example 1, only the first reaction was carried out to obtain a molecular weight of 1,800 and a molecular weight distribution of 1.49.

 As a later step, the final molecular weight was 1790 and the molecular weight distribution was 1.48 through a catalyst residual amount and an oligomer removal step.

Example 2

 The reaction was carried out in the same manner as in Example 1 to obtain a molecular weight of 300, a molecular weight distribution of 1.49, and the like in the first reaction. In the second reaction, the residence time was adjusted to 40 minutes under the same conditions as in Example 1 to obtain PTMG having a molecular weight of 2500 molecular weight distribution of 1.24.

Example 3

 In the same manner as in Example 1, the preparation of the first reaction was carried out by adjusting the coordination number of the introduced catalyst to 6 and proceeding with the reaction to obtain a PTMG having a molecular weight of 1,000 and a molecular weight distribution of 1.49. The catalyst was removed and introduced into a secondary reactor to adjust the residence time to 50 minutes to obtain PTMG having a molecular weight 10,000 molecular weight distribution of 1.18.

1 schematically illustrates a process for preparing polytetramethylene ether glycol according to the present invention.

Claims (6)

In the process for producing polytetramethylene ether glycol from tetrahydrofuran (THF) using a heteropoly acid (HPA) catalyst layer, A first reaction step of ring-opening polymerization of tetrahydrofuran to produce polytetramethylene ether glycol having a molecular weight of 300 to 2,000 Daltons; And And a second reaction step of chain extending the polytetramethylene ether glycol produced in the first reaction, The secondary reaction step is carried out in a state in which the tetrahydrofuran is removed in a separate tubular reactor in which a heteropoly acid catalyst is adhered to the surface in parallel with the water-removable column, The method for producing polytetramethylene ether glycol is characterized in that the molecular weight of the final produced polytetramethylene ether glycol is adjusted to have a residence time of 0.1 to 1 hour in a secondary reactor. The method for preparing polytetramethylene ether glycol according to claim 1, wherein the molecular weight of polytetramethylene ether glycol produced in the first reaction is 5 to 50% by weight of the molecular weight of polytetramethylene ether glycol after the second reaction. . delete delete The method of claim 1, wherein the secondary reaction temperature is 50 ~ 70 ℃. According to claim 1, wherein the molecular weight distribution (Mw / Mn) of the polytetramethylene ether glycol produced in the final production of polytetramethylene ether glycol, characterized in that 5 to 30% of the molecular weight distribution produced in the first reaction step Way.

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