JPH0469179B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polycarbonate polyols, and in particular to an improved method for producing aliphatic polycarbonate polyols by transesterification of an organic carbonate compound and a hydroxyl compound. The present invention relates to producing functional hydroxyl-terminated polycarbonates. Carbonate compounds conventionally used in transesterification include dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, ethylene carbonate, 1,2-propylene carbonate, diphenyl carbonate, and the like. These carbonate compounds are usually produced by reacting alcohol or phenol with phosgene, and they usually have a hydrolyzable chlorine content of about
20 ppm, which is undesirable for the production of polymers, such as coloration of the polymer due to halogen compounds formed as by-products in this phosgenation reaction, especially alkyl or aryl chloroformates remaining due to incomplete reaction. cause side reactions,
It has been observed that non-uniform reactions hinder the production of high quality polymers. However, in the polymer production process, the effect of halogens can be reduced by using alkali or alkaline earth metals or their metal compounds as transesterification catalysts, but these catalysts have a slow reaction rate and are difficult to carry out such as decarboxylation. Post-treatments such as washing or neutralization are required to accelerate decomposition and cause abnormal reactions with the isocyanate during urethanization. The present invention was developed in order to eliminate the drawbacks of the above-mentioned prior art, and aims to quickly produce high-quality polycarbonate with little coloring. In the method for producing a polycarbonate polyol by the transesterification reaction of a hydroxy compound with a dialkyl carbonate, an alkylene carbonate or a diaryl carbonate, the reaction is preferably carried out in the presence of an epoxy-containing compound and a titanium compound. is an epoxy group whose general formula is represented by the following formula (1) as an epoxy-containing compound: At least one compound containing one or more of
It is used in a proportion of ~0.0002 mole. Dialkyl carbonate compounds used in the production of polycarbonate are normally required to be purified by high-level washing or distillation, but according to the production method of the present invention, they can be purified by washing with a normal alkaline aqueous solution and distillation. Since the obtained quality dicarbonate compound is sufficient,
It does not require high-level purification of raw materials, and considering the steps required for this and the reduction in yield, it can be seen that it is an energy-saving and economical method. The dialkyl carbonate, alkylene carbonate or diaryl carbonate used in the method of the present invention includes, for example, dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, di-iso-butyl carbonate, ethylene carbonate, which can be obtained by a phosgenation method. Propylene carbonate, diphenyl carbonate and the like are preferred. Hydroxy compounds used in the method of the present invention include 1,3-propanediol, 1,
4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-ethyl-1,6-hexanediol, 2-methyl-
1,3-propanediol, neopentyl glycol, 1,3-cyclohexanediol, 1,4
-cyclohexanediol, 2,2'-bis-(4
-hydroxycyclohexyl)-propane, p-
xylene diol, p-tetrachloroxylene diol, 1,4-dimethylolcyclohexane,
(3(4),8(9)-bis-(hydroxymethyl)-tricyclodecanedimethylol, bis-hydroxymethyltetrahydrofuran, di(2-hydroxyethyl)dimethylhydantoin, diethylene glycol, triethylene glycol, polyethylene glycol, dimethyl These include propylene glycol, polypropylene glycol, polytetramethylene glycol, thioglycol, trimethylolethane, trimethylolpropene, hexanetriol, pentaerythritol, etc. These hydroxy compounds can be used alone or in combination in the transesterification reaction. The epoxy compound used in the method of the present invention is one containing at least one epoxy group structure of formula (1) in one molecule, and includes ethylene oxide, 1,2-propylene oxide, 1,2-propylene oxide, etc. −
Butylene oxide, epichlorohydrin, glycidol, methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether,
Allyl glycidyl ether, 2-ethylhexyl glycidyl ether, 2-methyloctyl glycidyl ether, phenyl glycidyl ether,
sec-butylglycidyl ethyl, epoxidized soybean oil, epoxidized linseed oil, diglycidyl ether of polyethylene glycol, polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane triglycidyl ether, vinylcyclohexene dioxide, dicyclopentadiene dioxide oxide,
1,2-epoxycyclododecane, 2(3,4-
There are epoxy resins represented by epoxycyclohexyl)ethylmethoxysilane, diglycidyl ether of bisphenol A, and the like. The effects of these epoxy compounds depend on the concentration of the epoxy group of formula (1) in the system. For example, even if a large excess amount is added than necessary, the effect will not be much different from the case where the minimum appropriate amount is added. In addition, the most effective amount of dialkyl carbonate, diaryl carbonate, or hydroxy compound to be added depends on the type and quality of each compound, but even if an excess amount is added, the weight ratio to the polymer is extremely small, so epoxy group-containing compounds No inconveniences are observed due to the addition of . Therefore, usually polymer 1000
It is sufficient to add the epoxy group of formula (1) at a ratio of 0.2 to 0.0002 mol per 1000 g of polymer, but when using commonly available raw materials, it is recommended to add about 0.05 to 0.005 mol per 1000 g of polymer. is preferred. When these epoxy group-containing compounds are added and reacted, the epoxy group of formula (1) reacts with hydrogen halide that is originally present in the raw material or generated during the transesterification reaction, resulting in a hydroxyl group-terminated compound. It is estimated that it generates . For example, if 1,2-propylene oxide is used as the epoxy group-containing compound, the 1-chloro-2
-Propanol is likely to be produced. [X represents halogen] Since the boiling point of this compound is 127°C, it is expected that it will be discharged from the system due to an increase in reaction temperature or vacuum reaction. When actually comparing the chlorine content before and after the transesterification reaction, it appears that about 90% or more is removed from the system when 1,2-propylene oxide is used. However, even when trimethylolpropane triglycidyl ether and epoxy resin compound (diglycidyl ether of bisphenol A), which are considered difficult to discharge outside the system, are used alone, the polymer is The coloring property is very good, and the discharge of halogen from the system is not necessarily a necessary condition. However, in consideration of long-term polymer stability, etc., when using raw materials containing a large amount of halogen, ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, It is preferable to use a low molecular weight substance such as methyl glycidyl ether. Furthermore, although excess epoxy groups may react with carboxylic acid or hydroxyl groups, since the amount required to be added is extremely small, it is unlikely to be a problem as a polyol for polyurethane. By adding such an epoxy group-containing compound, in the reaction of dialkyl carbonate, alkylene carbonate, or diallyl carbonate with a hydroxy compound, there is no particular restriction on the reaction temperature, but hydrogen halide and epoxy can be reacted at a relatively low temperature of 180°C or less. After allowing the group reaction to proceed to a certain extent,
It is preferable to carry out the reaction at a temperature of 150°C to 280°C, preferably 190°C to 220°C, and finally react for several hours at a pressure of 20 mmHg or less while maintaining the reaction temperature at 190°C to 220°C. Particularly at high temperatures of 220°C or higher, more complete halogen removal is expected, but there are also disadvantages such as a large amount of hydroxyl compounds being distilled off and the coloring of the polymer becoming stronger. Therefore, in order to suppress the distillation of hydroxy compounds as much as possible, a reaction apparatus equipped with a manual reflux condenser and a rectification column filled with Raschig rings, McMahons, etc. must be used.
Hydroxy compounds, dialkyl carbonates, alkylene carbonates,
It is possible to reduce distillation of diallyl carbonate and discharge unnecessary halogen compounds from the system. Examples of titanium compounds include organic titanium, titanium halides, titanic acid, and other inorganic titanium compounds such as tetraethyl titanate, tetra-iso-propyl titanate, tetra-n-titanate, acetylacetone titanium, titanyl ammonium oxalate, titanium trichloride, and tetraethyl titanate. Titanium chloride, titanium tetrafluoride, sodium titanate chloride, ammonium titanate chloride, ammonium titanate fluoride, titanic acid (), titanium sulfate, etc., but preferably titanium tetrachloride and tetra-n-butyl titanate, or Tetra-iso-propyl titanate. The amount of the titanium compound used is usually in the range of 0.05% to 0.0001% by weight, preferably 0.01% to 0.0005% by weight of titanium based on the polymer.
It is more preferable to add the titanium compound after adding the epoxy group-containing compound. In other words, the purpose is to remove impurities in raw materials, alkyl or aryl chloroformates, other hydrolyzable chlorine-containing compounds, hydrogen chloride produced by the reaction of titanium chloride, etc. with hydroxy compounds before they affect other components. . The composition of the polycarbonate polyol produced in this way was analyzed by ¹³ C-NMR, but it was found that the alkyl terminal structure, which lacks a terminal hydroxyl group, and the thermal stability caused by decarboxylation, etc. There are very few or almost no ether group structures that have an adverse effect. moreover,
According to a thermal stability test using a gear oven, a product with very little coloration and little decrease in viscosity was obtained. Further, transesterification reactions are usually carried out in large stainless steel reaction vessels, but unless this production method is used, corrosion of the reaction vessels will be observed. On the other hand, according to the manufacturing method of the present invention, corrosion of mild steel and stainless steel is not observed, and damage to the reaction vessel can be reduced without using special acid-resistant materials. Example 1 780 g of diethyl carbonate prepared by the reaction of ethyl alcohol and phosgene and 1,6-
Place 840 g of hexanediol in a glass reaction vessel. Next, 0.5 g of 1,2-propylene oxide and 0.03 g of titanium tetrachloride diluted in ethyl alcohol are added. The glass reaction vessel consists of 2 glass 4-necked flasks with a stainless steel stirring blade rotated by a motor, and an inner diameter of 18 mm and height.
Install a distillation column equipped with a 300mm reflux condenser. The inside of the distillation column is filled with 6 mm stainless steel McMahon. The transesterification reaction maintains the reaction mixture at a temperature of approximately 125°C to 130°C and distills off the ethyl alcohol produced. When the distillation of ethyl alcohol reaches 50% (weight) of the theoretical production amount, the temperature is slowly raised to 200°C. After reacting at a reaction temperature of 200°C for about 2 hours,
The reaction was carried out under reduced pressure. For reduced pressure reactions, the reaction temperature is
While maintaining the temperature at 200℃, increase the vacuum level to 50-100mmHg/60
The pressure is gradually reduced from normal pressure at a rate of 20 minutes.
After reacting for 2 hours at a pressure of mmHg, the temperature was raised to 220°C and a portion of 1,6-hexanediol was distilled off to obtain a polycarbonate polyol with a molecular weight of about 1000. When the hydroxyl value of this polyol was measured by the phthalation method, the hydroxyl value of this polyol was 115, the viscosity was 351 cs/75°C using a Canon Fuenske viscometer, and the melting color (APHA) was 100. Comparative Example 1 For comparison, titanium tetrachloride was added to the same diethyl carbonate and 1,6-hexane glycol as in Example 1, and the reaction was carried out without adding any epoxy group-containing mixture, and the resulting polymer was yellow. It was brown and warm. In this reaction, corrosion was observed on the stainless steel stirring rod. Comparative Example 2 Similar to Comparative Example 1, no epoxy group-containing compound was added, but tetra-n-butyl titanate was used as a catalyst.
When 0.4g was added and reacted, the resulting polymer had a hydroxyl value of 113, a viscosity of 357cs/75°C, and a pale yellow melting color (APHA) of 400. In this reaction, corrosion was observed on the stainless steel stirring rod. Example 2 660 g of dimethyl polycarbonate obtained by the reaction of methyl alcohol and phosgene and 1,6
-Pour 1000g of hexanediol into a stainless steel pressure-resistant reaction tank, add 1.0g of glycidol and 0.04g of tri-n-butyl titanate, and then seal the tank.
The reaction was carried out at 140°C for 16 hours. Next, the mixture is transferred to the same glass reaction vessel as in Example (1), and the methyl alcohol is expelled while being heated and stirred, and the temperature is gradually increased while adjusting to the distillation rate of the methyl alcohol to bring the reaction temperature to approximately 200°C. After continuing the reaction for about 1 hour, the reaction is carried out under reduced pressure. The degree of vacuum is gradually reduced from normal pressure at a rate of 100mmHg/60 minutes, and finally
A part of 1,6-hexanediol was distilled off at a vacuum degree of 10 mmHg to obtain a polycarbonate polyol having a molecular weight of 900. This polyol is a colorless waxy solid with a hydroxyl value of 126 and a viscosity of 281cs/75.
℃, and the melting color (APHA) was 80. Example 3 Diethyl carbonate (Hani Chemical Co., Ltd. Reagent GR) 860 g, 1,5 pentanediol 810
g was placed in a reaction vessel similar to that in Example (1), and 1 g of bisphenol type epoxy resin (trade name: Epicote 828, manufactured by Yuka Ciel Co., Ltd.) and 0.1 g of tri-iso-propyl titanate were added. while stirring
When the reaction is carried out at 125° to 130°C and the distillation of ethyl alcohol exceeds 50% by weight of the theoretical production amount, the reaction is continued while gradually increasing the temperature, and when the distillation of alcohol becomes extremely small at normal pressure. , the vacuum reaction was started. The degree of vacuum is gradually reduced from normal pressure at a rate of 100 mmHg/60 minutes, and finally the reaction is carried out for more than 2 hours at a degree of vacuum of 20 mmHg or less, and a part of 1,5 pentanediol is distilled out to form a colorless wax with a molecular weight of 2000. A solid polycarbonate polyol was obtained. This product had a hydroxyl value of 56.6, a viscosity of 1780 cs/75°C, and a melting color (APHA) of 150. Example 4 780 g of diethyl carbonate prepared by the reaction of ethyl alcohol and phosgene and 1,4
- 997 g of cyclohexane dimether was placed in the same reaction vessel as in Example (1), approximately 0.5 g of trimethylolpropane triglycidyl ether (manufactured by Nagase Sangyo Co., Ltd., trade name: Denacol EX-321) was added, and the reaction vessel was heated. do. When 1,4-cyclohexanedimethanol is dissolved, stirring is started, and when the reactant is at 126°C, 0.1 g of titanium tetrachloride is directly added. The reaction is carried out at a temperature of 125°C to 130°C, and when the distillation of ethyl alcohol reaches 40% by weight of the theoretical production amount, the reaction temperature is slowly raised to 200°C.
Subsequently, when distillation becomes extremely poor even at this temperature, a further vacuum reaction is carried out. While keeping the reaction temperature at 200℃, the degree of vacuum gradually increases from normal pressure to 50mmHg.
Depressurize at a rate of 100mmHg/60 minutes, finally 10mm
The reaction was carried out under a vacuum of Hg for more than 2 hours, and the temperature was raised to 220° C. while maintaining the vacuum to distill off a portion of 1,4 cyclohexanedimethanol, yielding a polycarbonate polyol with a molecular weight of 1000. This polyol had a hydroxyl value of 56.0, a viscosity of 3500cs/75°C, and a melting color (APHA) of 200. Example 5 Dimethyl carbonate (Tokyo Kasei Reagent Special Grade) was distilled and purified, and 1100 g of it was placed in a three-neck round bottom flask equipped with a thermometer and a packed distillation column. moreover
Iso-butyl alcohol (Tokyo Kasei Reagent Special Grade) was purified by distillation in the same way, and 1500 g of it was then added. Approximately 15 g of tetra-n-butyl titanate is added and a small amount of zeolite is added to carry out a transesterification reaction between methyl groups and n-butyl groups. Keep the reaction temperature at around 90℃, and make sure that the temperature at the fractionation head does not exceed 70℃.
The produced methanol was distilled out while the part to be distilled was refluxed. Next, excess dimethyl carbonate was distilled out while gradually increasing the temperature, and when the distillation temperature reached 190°C, the receiver was switched and the di-iso-
Butyl carbonate was obtained. When this di-iso-butyl carbonate was analyzed by gas chromatography, traces of methyl-iso-butyl carbonate were found, but no other impurities were found.
The hydrolyzable chlorine content determined by chemical analysis is
An extremely high quality product with a content of less than 0.5ppm was obtained. 1066 g of di-iso-butyl carbonate obtained by the above method is placed in the same reaction vessel as in Example (1), and 0.31 g of ethyl chloroformate is accurately added thereto using a microsyringe to completely dissolve. Next, 841 g of 1,6-hexanediol was added, and then 1 g of 1,2-propylene oxide and tetra-
Add 0.03 g of n-butyl titanate and react at 130°C for 1 hour. Then it gradually rises to 180℃
After reacting for 18 hours, the reaction was continued for about 2 hours at 200°C. While keeping the reaction temperature at 200°C, the degree of vacuum was gradually reduced from normal pressure at a rate of 50 mmHg to 100 mmHg/60 minutes, and finally the degree of vacuum was 10 mmHg, about 2
Allowed time to react. The obtained polycarbonate polyol had a hydroxyl value of 109.4, a viscosity of 348cs/75℃,
The melting color (APHA) was 60. When we measured the chlorine content in this polymer
It was below 10ppm. The 0.31 g of ethyl chloroformate added prior to the reaction is equivalent to 0.10 g of chlorine, but since the chlorine present before the reaction is converted to a concentration of 100 ppm in the polymer, it accounts for at least 90% of the added chlorine. It is estimated that the amount was discharged outside the system. Furthermore, the hydrolyzable chlorine content was measured and found to be 0.5 ppm. Example 6 3168 g of diphenyl carbonate produced by the reaction of phenol and phosgene and 2032 g of 1,6-hexanediol were mixed into a glass tube equipped with a thermometer, a stainless steel stirrer, a branched fractionator tube and a nitrogen inlet tube. Transfer to reaction vessel. After adding 2 g of methyl glycidyl ether to this, the temperature was raised and when the reaction mixture was dissolved, 0.08 g of tetra-n was added while stirring.
- Add butyl titanate. 210 in about 2 hours
The temperature was raised to °C, and the phenol produced by the reaction was distilled off. In addition, in order to aid the distillation of phenol, the temperature was heated to 200℃ while a small amount of nitrogen gas was aerated.
The reaction was carried out in a temperature range of 220°C for about 10 hours. The amount of phenol distilled so far was approximately 70% by weight based on the theoretical amount produced. Next, while maintaining the temperature of the reaction mixture at 200℃, the degree of vacuum is increased to 50-100mm.
The pressure was gradually reduced from normal pressure at a ratio of Hg/30 minutes, and the reaction was finally carried out at a pressure of about 10 mmHg for 2 hours. Next, the temperature was raised to 220° C. while maintaining the pressure at 10 mmHg, and a small amount of 1,6-hexanediol was distilled out to obtain a polycarbonate polyol with a molecular weight of 1000. The free phenol content in this polyol was 0.01% by weight or less according to gas chromatography analysis. The hydroxyl value was 118, the viscosity was 340cs/75°C, and the melting color (APHA) was 200. Furthermore, it was possible to produce the product in an extremely short time of 20 hours from the start to the end of the reaction. Comparative Example 3 For comparison, 1,6-hexanediol was added to 3168 g of diphenyl carbonate under the same conditions as Example 3.
When 0.08 g of tetra-n-butyl titanate was added to 2032 g and reacted without adding any epoxy group-containing compound, the melting color (APHA) of the obtained polymer was 400. Comparative Example 4 In order to compare the time required for producing polycarbonate polyol and the quality of the obtained polyol, polycarbonate was synthesized according to the production conditions of Example 1 according to Japanese Patent Publication No. 46-42384. That is, 3168 g of diphenyl carbonate of Example 6,
2032 g of 1,6-hexanediol is placed in a glass reaction vessel (No. 5) equipped with a thermometer, a stainless steel stirrer, a branched fractionator tube, and a carbon dioxide gas inlet tube. The reaction mixture is brought to 155° C. with stirring. Vacuum is then applied and distillation of phenol begins at a pressure of about 200 mmHg. The pressure was reduced to 25 mmHg over 24 hours while maintaining the temperature at 155°C. Next, slowly raise the temperature to 200℃, and reduce the pressure to 10℃.
Reduced to 12mmHg in hours. After reacting for about 14 hours while maintaining the same temperature and pressure, carbon dioxide gas was passed through the reactor at a rate that maintained a degree of vacuum of 30 mmHg, and the reaction was completed after 8 hours. The obtained reaction product was a pale yellow solid with a melting color (APHA) of 500 or more. Furthermore, the free phenol contained in the polyol was 0.04%.
Polyols produced by this method were significantly colored due to the prolonged reaction. Comparative Example 5 For comparison, ethylene carbonate was used in JP-A-1988.
A polymer was produced according to the method disclosed in Japanese Patent No.-56124. That is, 900 g of ethylene carbonate (Tokyo Kasei Reagent Grade 1) and 1000 g of 1,6-hexanediol were placed in a second four-neck flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a packed distillation column, and tetra-n-butyl titanate was added. 0.2g of was added. The temperature of the reaction mixture was maintained at 150°C to 155°C and the reaction was carried out under a pressure of 150 mmHg, yielding a considerable amount of distillate. This distillate component was a mixture of ethylene glycol, a reaction product, unreacted ethylene carbonate, and 1,6-hexanediol. The pressure was further reduced and the reaction temperature was increased to 210°C to distill off ethylene glycol, yielding a colorless waxy polymer. This polymer has a hydroxyl value of 123 and a viscosity of 268cs/
The melt color (APHA) was 100 at 75°C. 100g of each of the polycarbonate polyols obtained in this way was placed in a 200ml glass sample bottle, and the cap was screwed shut to allow slight ventilation.
The samples were placed in a gear oven at 200°C for about 70 hours, and changes in color and viscosity were compared (Table 1). As shown in the gear oven test results in Table 1, the less coloring is originally caused by thermal deterioration, and the polycarbonate polyol obtained by the production method of the present invention was found to be excellent in thermal deterioration. However, polyols made from dialkyl carbonates were superior to polyols made from diphenyl carbonate as raw materials, especially in terms of heat deterioration resistance. This is considered to be due to the phenol or phenyl compound remaining in the polyol. Polyols made from ethylene carbonate were obtained with little coloring, but in the gear oven test, they were inferior in terms of coloring and had low viscosity. This is due to the ether groups generated by the side reaction of ethylene carbonate, and in addition to the low melting point of the polyol, ¹³ C-NMR measurements (Table 2) also confirmed that there were a large number of ether groups. Polycarbonate polyols made from diphenyl carbonate usually contain 0.03% phenol.
% to 0.10% by weight, but according to ¹³ C-NMR, 0.2% by weight or more of phenyl ether groups are present. On the other hand, in polycarbonate polyols made of dialkyl carbonate or alkylene carbonate, no non-reactive terminal structure due to methyl, ethyl or butyl groups was observed.

【table】

【table】

【table】

[Table] Example 7 700 g of ethylene carbonate synthesized from ethylene glycol and phosgene and 1090 g of 1,6-hexanediol were placed in a reaction vessel, and glycidol
0.5 g and 0.05 g of tetrabutyl titanate were placed in two glass reactors equipped with a packed distillation column, a thermometer, and a stirrer, and reacted for about 5 hours at a temperature of 180° C. and a vacuum of 150 mmHg. Next, while maintaining the pressure at 150 mmHg, the temperature was gradually raised to 200°C after 5 hours.The composition of the distillate components so far was approximately 70% ethylene glycidol, 25% ethylene carbonate,
1,6-hexanediol was 5%. 10mm per hour while keeping the reaction temperature at 200℃
The pressure was reduced at a rate of Hg, and when the pressure reached 10 mmHg, the reaction was continued for about 2 hours. Furthermore, the excess 1,6-hexanediol resulting from the distillation of ethylene carbonate was removed for about 1 hour at a temperature of 200°C and a pressure of 5 mm.
Distilled with Hg, hydroxyl value 120, viscosity 270cs/75℃,
A polymer with a color (APHA) of 100 was obtained.

Claims (1)

[Scope of Claims] 1. A method for producing a polycarbonate polyol by transesterifying a hydroxy compound with a dialkyl carbonate, alkylene carbonate, or diaryl carbonate containing a hydrolyzable chlorine compound as an impurity, wherein the above reaction is carried out with an epoxy-containing compound and titanium. A method characterized in that it is carried out in the presence of a compound. 2 An epoxy group represented by the general formula (1) below as an epoxy-containing compound: At least one compound containing one or more of
The method according to claim 1, wherein the amount is used in a proportion of 0.2 to 0.002 mole. 3. The method according to claim 1, wherein at least one of an organic titanium compound and an inorganic titanium compound is used as the titanium compound in a proportion of 0.05 to 0.0001% by weight of titanium based on the polymer.