KR100558707B1 - Method for preparing polytetramethylene ether glycol diester - Google Patents

Abstract

The present invention relates to a method for producing polytetramethylene ether glycol diester, wherein tungsten or molybdenum is supported on a support material using an acid solution, and metal sulfides or chlorides are supported on the support material, followed by 500 to 900 ° C. It is characterized by using a catalyst prepared by calcining at a temperature of, and polymerizing tetrahydrofuran in the presence of carboxylic anhydride, when performing THF polymerization by the method of the present invention, the catalyst can be reused without loss In addition, PTMG having an appropriate molecular weight can be obtained with a relatively high polymerization yield.

Description

Preparation method of polytetramethylene ether glycol diester {Preparation Method of Polytetramethylene Ether Glycol Diester}

The present invention relates to a method for producing polytetramethylene ether glycol diester, and more particularly to a method for producing polytetramethylene ether glycol diester with improved yield.

The polytetramethylene ether glycol diesters prepared are readily hydrolyzed in the presence of a base catalyst and converted into polytetramethylene ether glycols (hereinafter abbreviated as "PTMG") in which the end groups are present in OH groups.

PTMG, also referred to as polyoxybutylene glycol, functions as an intermediate for the production of polyurethanes, polyesters and polyamide elastomers in which it is used as a diol component. PTMG is also used as a component of the soft segments for these polymers, since polymers containing PTMG in these polymers become flexible in their chains and become ductile.

It is also used as a plasticizer, impregnating agent, monomer, emulsifier, and dispersion aid, and is an industrially useful polymer that can be used as a solvent, pressure fluid, etc. used for removing ink in waste paper recycling, and its use continues to increase.

The production of PTMG by polymerization of tetrahydrofuran (hereinafter abbreviated as "THF") uses a cationic polymerization method, and the polymerization method is well known. The polymerization of THF is a ring-opening polymerization reaction, and usually does not occur easily, so that polymerization is possible only by using a catalyst having a very high acidity.

According to US Pat. No. 3,358,042, a THF polymerization reaction is carried out using two molecules of fluorosulfonic acid as a catalyst to prepare PTMG. According to US Pat. No. 3,712,930, fuming sulfuric acid is used as a catalyst to perform THF polymerization.

In addition, No. 4,120,903 uses Nafion ion exchanger resin as a catalyst and acetic anhydride as a reactive activator. The defect of the ion exchanger catalyst is that the production of the ion exchanger is very difficult, and the production cost of PTMG is increased due to the lack of long-term stability of the catalyst.

In addition, there is a method for producing PTMG in the presence of perchloric acid-acetic anhydride or BF ₃ -HF-acetic anhydride and amorphous synthetic aluminum silicate and acetic anhydride as disclosed in PCT / EP93 / 02735, which are carried out industrially.

U. S. Patent No. 5,344, 964 describes a process for preparing polytetramethylene diesters by reacting a mixture of monocarboxylic acid anhydrides and THF with metal oxides of Group III and Group IV metals of the Periodic Table.

Korean Patent No. 86-1766 describes a method of producing THMG by polymerizing THF using heteropoly acid as a catalyst and using water as a telogen at 60 ° C. and atmospheric pressure. However, this method has the advantage of simplifying the process by polymerizing PTMG in one step, but has the disadvantage that the conversion of the final THF to PTMG is only about 14%. When the polymerization yield is increased, the produced PTMG increases the molecular weight, which is not effective. In addition, the heteropolyacid catalysts used are very expensive and the process for recovering them after the reaction tends to be complicated.

Korean Patent Laid-Open Publication No. 97-701812 describes a method for producing PTMG by polymerizing THF using a zirconium-based super acid catalyst. According to this, when zirconium-based super acid is used, PTMG can be produced in THF in one step with a yield of about 30-60%, but the reaction time is very long as 20 hours, and the molecular weight of the prepared PTMG is very high as 3000 or more. This is less.

As described above, the above-described methods have disadvantages such that the catalyst is expensive, decomposition may occur during the reaction, making it impossible to reuse, low conversion of THF to PTMG, or low molecular weight of polymerized PTMG.

The present invention has been made to solve the above-mentioned problems, and aims at improving process economics by enabling reuse of a catalyst in producing PTMG by polymerizing THF and increasing the yield per unit time.

In the present invention, tungsten or molybdenum is supported on a support material using an acid solution, and metal sulfides or chlorides are supported thereon using an acid solution, and then calcined at a temperature of 500 to 900 ° C. It consists of polymerizing THF in the presence of acid anhydride to produce polytetramethylene ether glycol diesters.

Hereinafter, the present invention will be described in detail.

Materials that can be used as the support of the catalyst system according to the present invention include activated carbon, silica-alumina, zeolite, alumina, silica and zirconium oxide, hafnium oxide, titanium oxide, zinc oxide, tin oxide, vanadium oxide, chromium oxide, iron oxide, magnesium oxide Oxides, such as these, can be used.

Preferably, activated carbon, alumina, zeolite, silica, or the like, and the type of the appropriate support may vary depending on the active material or cocatalyst supported, and the calcination temperature showing the best catalytic activity also varies.

The main active metals are tungsten and molybdenum. The supported form of these metals may be used in the form of carbonate, nitrate, acetate, oxalate, carboxylate, organometallic compound, halogen salt or oxide.

The supporting ratio of the active metal is usually about 5 to 50% by weight of the support. Preferably it is about 10 to 30%. The supporting ratio of the active metal varies depending on the type of the support.

When the active metal is supported, the supported solvent may be a method using water that is commonly used. Preferably, an acid such as sulfuric acid, hydrochloric acid, acetic acid, nitric acid, hydrofluoric acid, phosphoric acid, etc., whose concentration is appropriately adjusted may be used. More preferred are sulfuric acid and hydrochloric acid, and their proper concentration depends on the type of support.

When the additional metal (cocatalyst) is supported at about 1 to 10%, more preferably at about 1 to 5% together with the active metal, the activity of the catalyst is further enhanced. The metal that can be used may be a single metal such as Ti, Zr, V, Mn, Re, Co, Ni and Sn, Mn, Cu, Ag, Zn, Hg, Ga, or a mixture of two or more kinds of single metals. .

When supporting the promoter, as in the case of the active metal, as the supported solvent, water may be used, but it is preferable to use acids such as sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, acetic acid and nitric acid. The supporting order of the active metal and the promoter may be a sequential method of supporting the active metal first and the promoter or supporting the promoter first, and a method of simultaneously supporting the active metal and water.

Heteropoly acid using tungsten or molybdenum as a coordination metal may be used as a precursor of the active metal. In the case of using a heteropoly acid, the catalyst can be converted into an active metal material by sufficiently raising the firing temperature of the catalyst.

When carrying a heteropoly acid, it may be used as a mother acid itself, and may be used in the form of a substituted salt. If the metal to be used as a cocatalyst is previously used in the form of a salt, the proton and the substituted ring salt of the heteropolyacid may simultaneously support the active ingredient and the cocatalyst ingredient. The method for preparing a substitution salt is to select a cocatalyst component, quantify the heteropolyacid, and dissolve in distilled water. It can be stirred for 0.5 to 3 hours while slowly heating to a temperature of 20 to 80 ℃ to form a heteropolyacid, which is dried under atmospheric pressure or reduced pressure to obtain a heteropolyacid crystal.

After the firing process in order to activate the dried catalyst is carried out in the range of 300 to 900 ℃. If the calcination temperature is low enough that the heteropolyacid does not undergo pyrolysis, THF polymerization occurs due to the catalytic properties of the heteropolyacid. The pyrolysis temperature of the heteropolyacid depends on the type of substituted salt or the type of coordinated metal, but in general, the W coordination is higher than the Mo or V coordination.

When the heteropoly acid is calcined above the pyrolysis temperature, the structure of the heteropoly acid is destroyed, and the fact that the heteropoly acid is destroyed is sufficiently observed as FT-IR. When the structure is destroyed by pyrolysis of heteropolyacids, tungsten or molybdenum oxides are formed and they act as main active metals.

When forming a material for use as a support, a catalyst may be prepared by precipitating both the active metal and the metal used as a promoter. It is prepared by coprecipitation using a metal oxide or a halide of a metal in a reduced form, preferably nitrate, carbonate or carboxylate and in particular its acetate, to support the hydroxides of the substances constituting the respective supporting components. The corresponding hydroxides from the solution of these salts at coprecipitation may be prepared by precipitation using an aqueous ammonia solution or weak base, or by adding a weak acid such as acetic acid to the water-soluble hydroxide complex of each metal until precipitation of each hydroxide occurs.

For example, when using alumina as an oxidizing support material, a solution in which one or two or more metals to be added to alumina hydrosol formed by dissolving aluminum metal with hydrochloric acid is previously dissolved in weak or strong acid is quantified. The concentration of the solution should not be too dilute. When hexamethylenetetraamine or 5% aqueous ammonia solution is dropped to the above alumina hydrosol and heated to about 80 ° C., a precipitate is formed. The resulting precipitate is filtered off, washed with distilled water and calcined at 500 to 900 ° C. for 3 to 10 hours to have catalytic activity.

When polymerizing THF using the catalyst according to the present invention, it is advantageous to increase the polymerization rate and conversion rate with the help of a reaction accelerator such as carboxylic anhydride.

The accelerator is advantageous to use aliphatic or aromatic polycarboxylic acids having 2 to 12, preferably 2 to 8 carbon atoms, and more preferably carboxylic anhydrides derived from monocarboxylic acids. Examples are acetic anhydride, propionic anhydride, butyric anhydride or acrylic acid or methacrylic anhydride and succinic anhydride. Carboxylic anhydride as a reaction accelerator may be used alone or in the form of a mixture of two or more kinds. However, from an economic point of view, acetic anhydride is preferred.

In most cases, the polymerization proceeds to terminate the conversion of the carboxylic anhydride. Therefore, the content of the reaction promoter is related to the control of the degree of polymerization and the yield of the polymer according to the reaction time. In general, as the content of the carboxylic acid anhydride increases, the degree of polymerization decreases and the yield tends to increase. The conversion rate of THF to PTMG changes with polymerization temperature. Generally, the lower the temperature, the higher the conversion, but the slower the reaction.

The polymerization of THF is carried out at a temperature of 0 ° C to 80 ° C and preferably at a temperature of 25 ° C to 70 ° C. THF conversion in this case depends on the temperature and the content of carboxylic anhydride, but in most cases polymerization takes place in the range of 20 to 60%. Since the polymerization of THF is not sensitive to pressure, it is usually carried out in the range of atmospheric pressure or water pressure.

Since THF easily generates ether peroxide in the presence of oxygen, it is important to block oxygen even in the polymerization reaction and before the reaction. Generally, the polymerization is usually carried out in the presence of an inert gas, and nitrogen, hydrogen, carbon dioxide and gas of group 0 may be used as the inert gas, but nitrogen is generally used preferably.

The polymerization method according to the present invention may be used in a batch or continuous form, and the continuous process is easier in terms of controlling reaction variables such as control of molecular weight.

The amount of catalyst used when carrying out the polymerization is usually 1 to 200% by weight, preferably 20 to 100% by weight, more preferably 30 to 80% by weight, based on the weight of the THF used. desirable. The reaction time is 0.1 to 5 hours, preferably 0.5 to 3 hours, depending on the amount of catalyst added.

When carrying out the reaction according to the invention, it is usually advantageous to rotate part or all of the reaction product back to the vessel in a stirred vessel or loop reactor at a constant polymerization temperature until the desired yield of THF is achieved. In general, a rotational flow rate of 3 to 10 times the volume of the reactor per hour is suitable.

For continuous polymerization, a fresh feed of THF mixture is added to the rotating product at 0.01 to 0.1 times the rotational flow rate per hour.

Another suitable reactor of the polymerization reaction according to the invention is a rotating basket in which a catalyst is filled in the form of a basket in a stirrer of a rotary reactor in a reactor additionally equipped with a stirrer.

Purification of the reaction product resulting from the batch process can be separated from the catalyst by filtration, standing, centrifugation, or the like, and separation of the catalyst and reaction product is simpler when using a fixed bed reactor. The remaining catalyst after separation can be reused continuously without further treatment, and no decrease in activity is seen, but if necessary the catalyst can be added again. The reaction product from which the catalyst is separated is usually separated from the unreacted THF by distillation, and the separated THF is reused for the reaction.

THF polymerized by the process according to the invention takes the form of polytetramethylene ether glycol diesters in which the end groups are formed of ester groups. The polymer obtained in this way can be hydrolyzed by a known method or transesterified with methanol to replace the terminal group with an alcohol group, and this substitution can produce polytetramethylene ether glycol as a final target.

A simple method of substituting an ester group for an alcohol group is an ester hydrogenation method using an oxide catalyst. Copper catalysts are used to convert diesters to diols without loss at high pressure, medium temperature without solvents or in the presence of ethanol or ethanol solvents.

The product obtained by the process according to the invention can simply be hydrogenated to obtain a product with a sufficiently low residual ester amount of 1 mg KOH / g.

Examples and comparative examples are described below for the detailed description of the invention. The following examples are intended to illustrate the method according to the invention in more detail and do not limit the invention.

<Example 1>

50 g of H ₂ WO ₄ was added to 500 ml of 2 mol sulfuric acid solution and stirred until it was completely dissolved. Then, after adding 250 g of powdered alumina, the mixture was further stirred for about 30 minutes and dried at 120 ° C. for 12 hours to obtain tungstic acid-supported alumina. Next, HgSO ₄ was quantified to 1.5% by weight of Hg metal, dissolved in 500 ml of a 2-mol sulfuric acid solution, and tungsten-supported alumina was added thereto, followed by stirring for 30 minutes. After drying at 120 ° C. for 12 hours or more, water was removed, and then heated to 700 ° C. at a temperature rising rate of 10 ° C./min, and then calcined at 700 ° C. for 5 hours.

100 g of the catalyst prepared as described above was put into a 1 liter glass reactor equipped with a reflux condenser and blown all the oxygen remaining in the reactor with nitrogen. Then, 250 g of THF containing 8 g of acetic anhydride was added and the temperature was fixed at 50 ° C. for 1 hour. The stirring was continued for a while. Nitrogen was blown in continuously during the reaction to block contact between the reactants and oxygen. After the reaction was completed, the reaction mixture was filtered and analyzed from the catalyst. The concentration of unreacted acetic anhydride in the reaction product was 300 ppm or less.

Unreacted THF in the obtained reaction mixture was evaporated using an aspirator. Thereafter, the polymer obtained through the hydrolysis was substituted with the end group, and then impurities and oligomers were removed using a thin film evaporator. The molecular weight of the obtained PTMG was measured using an OH titration method, and the measured molecular weight was 1848. The PTMG obtained weighed 151 g.

<Example 2>

The catalyst used in Example 1 was again filtered and dried, followed by polymerization in the same manner as in Example 1 to obtain 150 g of PTMG having a molecular weight of 1845.

Comparative Example 1

250 g of alumina without tungstic acid was omitted in the same manner as in Example 1 above, followed by skipping the process of HgSO ₄ in 2 mol sulfuric acid solution, stirred for 30 minutes, and dried at 120 ° C. for 12 hours or more. The catalyst was prepared by heating to 700 ° C. at a temperature increase rate of 10 ° C./min and calcining at 700 ° C. for 5 hours.

100 g of this catalyst was reacted in the same manner as in Example 1 to obtain PTMG 72 having a molecular weight of 1703.

Comparative Example 2

The catalyst was prepared in the same manner as in Example 1 except that the supported solution was used as distilled water instead of using 2 mol of sulfuric acid solution.

THF polymerization was carried out using the catalyst 100 g in the same manner as in Example 1 to obtain 88 g of PTMG having a molecular weight of 1723.

<Example 3>

48 g of H ₃ PW ₁₂ O ₄₀ was dissolved in 500 ml of distilled water, and 250 g of powdered alumina was added thereto, stirred for about 30 minutes, and dried at 120 ° C. for 12 hours to obtain alumina loaded with tungstophosphoric acid. Next, HgSO ₄ was quantified to 1.5 wt% based on Hg metal, dissolved in 500 ml of a 2 mol sulfuric acid solution, and tungsten-supported alumina was added thereto, followed by stirring for 30 minutes. After drying at 120 ° C. for 12 hours or more, water was removed, and then heated to 700 ° C. at a temperature rising rate of 10 ° C./min, and then calcined at 700 ° C. for 5 hours.

100 g of the catalyst prepared as described above was used in the same manner as in Example 1 to obtain 142 g of PTMG having a molecular weight of 1835.

<Example 4>

A catalyst was prepared in the same manner as in Example 1 except that the final calcination temperature was 500 ° C. The yield of the polymer obtained as a result of the same reaction experiment was 48%.

<Example 5>

The catalyst was prepared in the same manner as in Example 1 except that the final firing temperature was set at 600 ° C. The yield of the polymer obtained as a result of the same reaction experiment was 35%.

<Example 6>

A catalyst was prepared in the same manner as in Example 1 except that the final calcination temperature was 800 ° C. The yield of the polymer was 55%.

<Example 7>

1720 g of distilled water and 515 g of 35 wt% hydrochloric acid were added to 2000 g of aluminum metal, and gradually heated to produce an alumina hydrosol. After filtering out the unreacted aluminum, MoO ₃ was quantified in 10% by weight based on Mo metal, 1% by weight of HgSO ₄ was added to concentrated sulfuric acid, completely dissolved, and mixed with the prepared alumina hydrosol. Hexamethylenetetraamine or 5% aqueous ammonia solution was dropped into the alumina hydrosol, and the precipitate was heated to about 80 ° C.

The resulting precipitate was filtered off, washed with distilled water and calcined at 700 ° C. for 5 hours. THF polymerization was carried out in the same manner as in Example 1, to obtain 132 g of PTMG having a molecular weight of 1836.

<Example 8>

100 g of KL-zeolite was added to 350 ml of a 2 mol sulfuric acid solution in which 2.5 g of AgSO ₄ was dissolved, and stirred for 12 hours at a suitable speed at room temperature. Next, the temperature was raised to 100 ° C., and the water was blown out, dried at 150 ° C. for 2 hours, and calcined at 550 ° C. for 6 hours. 20 g of tungstic acid was dissolved in 200 ml of a 2-mol hydrochloric acid solution, followed by stirring at a temperature of 80 ° C. for 36 hours. After washing several times with filtration and distilled water, the mixture was dried at 150 ° C. for 6 hours, and then heated to 550 ° C. at an elevated temperature rate of 1 ° C. per minute under oxygen flow, and maintained at this temperature for 2 hours.

100 g of the catalyst prepared above was put into a 500 ml fixed bed reactor, and the inside was completely replaced with nitrogen, and filled with THF containing acetic anhydride. After the reaction temperature was fixed at 50 ° C., the reaction mixture was continuously circulated using a circulation pump. Then THF containing acetic anhydride was added to the circulator over 100 hours. The ratio of circulation / feed was about 70: 1. The average polymer yield over the entire reaction time was 52% and the average molecular weight of the obtained PTMG was 1900.

As can be seen from the above embodiment, when the THF polymerization is carried out by the method of the present invention, the catalyst can be reused without loss, and PTMG having an appropriate molecular weight can be obtained with a relatively high polymerization yield.

Claims (10)

A catalyst prepared by supporting tungsten or molybdenum as the main active metal on the support material using an acid solution and then supporting metal sulfide or chloride with an acid solution as a promoter and calcining at a temperature of 500 to 900 ° C. And tetrahydrofuran is polymerized in the presence of a carboxylic anhydride. The metal sulfide or chloride used as the promoter according to claim 1 is a single metal such as Ti, Zr, V, Mn, Rc, Co, Ni and Sn, Mn, Cu, Ag, Zn, Hg, Ga, or 2 A method for producing a polytetramethylene ether glycol diester, characterized by mixing at least one type of single metal. The support according to any one of claims 1 to 4, wherein the support is activated carbon, silica-alumina, zeolite, alumina, silica, etc., and zirconium oxide, hafnium oxide, titanium oxide, zinc oxide, tin oxide, vanadium oxide, chromium oxide, A method for producing a polytetramethylene ether glycol diester characterized by using oxides such as iron oxide and magnesium oxide. The method for producing a polytetramethylene ether glycol diester according to any one of claims 1 to 3, wherein the addition of the cocatalyst is carried out before or after the main active metal is supported or at the same time. . The method for producing polytetramethylene ether glycol diester according to claim 4, wherein the weight ratio of the promoter is about 1 to 10 parts by weight, more preferably 1 to 5 parts by weight based on 100 parts by weight of the support. The method according to claim 1 or 2, wherein the supported solvent is supported by using acids such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid, phosphoric acid, hydrofluoric acid, etc. The method for preparing polytetramethylene ether glycol diester according to claim 1, wherein a catalyst prepared by supporting a support using a heteropolyacid containing a main active metal and then calcining at a temperature of 500 to 900 占 폚 is used. The method for producing polytetramethylene ether glycol diester according to claim 7, wherein a catalyst prepared by supporting a heteropolyacid prepared by salt-substituting a metal used as a cocatalyst with a heteropolyacid in advance on a support is used. [Claim 2] The polytetramethylene ether glycol di according to claim 1, wherein the used catalyst is separated / recovered from the reaction product by filtration, standing, centrifugation, or the like, and the recovered catalyst is continuously used in a polymerization reaction. Process for the preparation of esters. The method for producing polytetramethylene ether glycol diester according to claim 1, wherein tetrahydrofuran is copolymerized with tetrahydrofuran and another cyclic ether copolymerizable with tetrahydrofuran.