JP2015091912A - Method for producing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing polyester excellent in color tone and thermal stability, and further copolymerized with isosorbide in which the production amount of by-products is reduced.SOLUTION: Provided is a method for producing polyester where, to a dicarboxylic acid component, isosorbide-containing diol component and isosorbide copolymerization is caused. The method for producing polyester is characterized in that, using refined isosorbide, a series of stages from an isosorbide refining stage to an isosorbide copolymerization step is performed in an inert gas atmosphere.

Description

  The present invention relates to a method for producing a polyester copolymerized with isosorbide, which is excellent in color tone and thermal stability and has a small amount of by-products.

  Polyester is one of the most commonly used synthetic resins in the world as fibers, bottles, films, sheets, containers, etc. because it is excellent in mechanical strength, chemical stability and transparency and inexpensive.

  Usually, polyester is remelted and molded after chipping, but if a thermal history of 250 ° C. or higher is applied at this time, the molding machine may become yellowed due to thermal decomposition, molecular weight decreases, or foreign matter occurs due to gelation. There is a problem that undesired phenomena such as increase in the amount of dirt on the base and clogging of the filter in the manufacturing process occur.

  As a means for improving the thermal stability of polyester, a technique for copolymerizing various glycol components has been studied, and among them, a diol component can be cited as a component for improving the thermal stability. Of these, the use of naturally-derived isosorbide for copolymerization has attracted attention. However, isosorbide tends to turn yellow when exposed to air, and polyesters polycondensed using the discolored isosorbide have a problem of poor color tone.

  In addition, as a means for improving the thermal stability, a technique for suppressing the production of diethylene glycol by-products that can cause a decrease in heat resistance has been studied. For example, in the production of a copolyester containing isosorbide, a method for producing a polyester that improves the reactivity by using a titanium compound as a polymerization catalyst has been proposed (for example, see Patent Document 1). However, the polyester described in Patent Document 1 has a problem in that both color tone and degree of polymerization are not sufficiently compatible with each other. In addition, there is no description about the content of diethylene glycol, which is a by-product that may be eluted, and it is unclear.

  On the other hand, in order to obtain a clear polymer, for example, a method for producing a polyester using purified anhydrous sugar alcohol has been proposed (see, for example, Patent Document 2). However, there is no description of a catalyst for polyester polycondensation, and the degree of polymerization and stability of the resulting polyester are unknown. In addition, the color change of the tone is unclear. Further, the content of diethylene glycol as a by-product is unknown.

  Therefore, there has been a demand for a method for producing an isosorbide copolyester that has excellent color tone and thermal stability, and also has the characteristics that a small amount of by-products are produced.

Special table 2012-514065 gazette Special Table 2002-534486

  An object of the present invention is to provide a method for producing a polyester copolymerized with isosorbide, which is excellent in color tone and thermal stability and has a small amount of by-products. “Excellent color tone” means that the color is light and the b value is low as measured by a color difference meter.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have found a method for producing a polyester copolymerized with isosorbide, which is excellent in color tone and thermal stability and further has a small amount of by-products, and has reached the present invention. .

That is, the present invention is as follows.
(1) For 100 moles of the dicarboxylic acid component,
A method for producing a polyester in which 100 to 200 mol of a diol component is polycondensed,
The diol component is a diol component containing 1 to 100 mol of isosorbide with respect to 100 mol of the dicarboxylic acid component,
The isosorbide is purified isosorbide,
A process for producing a polyester, wherein a series of steps from a purification step of isosorbide to a polycondensation step is performed in an inert gas atmosphere.
(2) The method for producing a polyester according to (1), wherein the dicarboxylic acid component is an aromatic dicarboxylic acid or an aromatic dicarboxylic acid alkyl ester.
(3) The method for producing a polyester according to (1) or (2), wherein the polycondensation is performed using at least an antimony compound and a magnesium compound.
(4) The method for producing a polyester according to any one of (1) to (3), wherein the purification of isosorbide is recrystallization using an organic solvent in which isosorbide is soluble.

  According to the present invention, it is possible to obtain a polyester copolymerized with isosorbide, which is excellent in color tone and thermal stability and has a small amount of by-products.

  The present invention relates to a method for producing a copolyester containing isosorbide. The method for producing the polyester of the present invention comprises the following three steps. That is, (A) a step of purifying isosorbide, (B) a step of adding a dicarboxylic acid component and a diol component other than isosorbide to the purified isosorbide to obtain a low polymer by an esterification reaction or a transesterification reaction, C) A subsequent three-stage process in which polycondensation is performed in the presence of at least an antimony compound and a magnesium compound, and a series of three steps is performed in an inert gas atmosphere.

  The inert gas of the present invention may be any inert gas with respect to isosorbide and polyester, and examples thereof include nitrogen, argon, helium, and carbon dioxide gas. Nitrogen is preferable from the economical aspect.

  Examples of the method (A) for purifying isosorbide that is the first step include a recrystallization method, a reprecipitation method, and a chromatography method. A recrystallization method using an organic solvent in which isosorbide is soluble is preferable from the viewpoints of economy and purity of the purified product. As said organic solvent, chloroform is preferable. This is because the difference in solubility depending on the temperature of isosorbide in chloroform is large, and recrystallization can be performed with a small amount of solvent and with a high yield. Hereinafter, chloroform will be described as an example of the organic solvent.

  As a method (A) for producing isosorbide, which is the first step, specifically, a suspension obtained by adding 20 to 100 L of chloroform to 100 mol of isosorbide in an inert gas atmosphere is 50 to 61 ° C. Heat to dissolve. At this time, it is preferable to add 20 L or more of chloroform to 100 mol of isosorbide in order to dissolve in chloroform at the time of heating. In order to obtain isosorbide with good yield, it is preferable to add 100 L or less of chloroform, preferably 50 L or less, and more preferably 30 L or less. The temperature of the suspension is preferably 50 ° C. or higher in order to dissolve isosorbide and obtain a good yield. 55 degreeC or more is preferable and 58 degreeC or more is preferable. The upper limit is preferably 61 ° C. or lower, which is the boiling point of chloroform.

  Then, it cools to 30 degrees C or less, and the acicular crystal | crystallization of isosorbide is deposited. At this time, it is preferable to perform recrystallization with slow stirring in order to obtain fine crystals with good operability for filtration. In order to obtain isosorbide crystals in good yield, it is preferable to cool to room temperature over 5 hours, more preferably 8 hours or more, and even more preferably 12 hours or more. The precipitated crystals are filtered through a filter of retained particles 0.1 to 10 micrometers while flowing an inert gas atmosphere or an inert gas, and the isosorbide on the filter is washed with chloroform at a temperature below room temperature. Isosorbide deposited on the filter is dried under reduced pressure at 180 mmHg or less. The reduced pressure drying within the above range is preferable because chloroform can be efficiently removed. Then, it returns to normal pressure using an inert gas so that it may not touch air, and the obtained isosorbide is used for the operation | work of 2nd process (B). In addition, when air touches the isosorbide obtained here, it will change to yellow, and since the color tone of the polyester using it will also deteriorate, it is unpreferable. Moreover, you may repeat the refinement | purification process of isosorbide in multiple times as needed. After carrying out by dividing into a plurality of batches, they may be used together in the next step (B).

  In the second step (B), an esterification reaction is performed when a dicarboxylic acid is used as the dicarboxylic acid component, and an ester exchange reaction is performed when a dicarboxylic acid alkyl ester is used as the dicarboxylic acid component.

  In the esterification reaction, 100 to 200 mol of diol containing isosorbide is reacted at a temperature of 200 to 300 ° C. with respect to 100 mol of dicarboxylic acid, and the reaction is carried out until 200 mol of water is distilled out with respect to 100 mol of dicarboxylic acid. This is a step of obtaining a polymer. In the transesterification reaction, 100 to 200 mol of a diol component containing isosorbide is reacted at a temperature of 200 to 300 ° C. with respect to 100 mol of dicarboxylic acid alkyl ester, and 200 mol of alcohol is distilled with respect to 100 mol of dicarboxylic acid alkyl ester. In this step, a low polymer is obtained by carrying out a reaction until it is carried out. In addition, dicarboxylic acid and dicarboxylic acid alkyl ester are collectively referred to as a dicarboxylic acid component (details will be described later).

  In this invention, 100-200 mol of diol components containing isosorbide are polycondensed with respect to 100 mol of dicarboxylic acid components. When the diol component containing isosorbide is less than 100 mol, polycondensation does not proceed smoothly. When it exceeds 200 mol, a large amount of unreacted diol is present, which is inefficient. The lower limit is preferably 110 mol or more, and more preferably 115 mol or more. The upper limit is preferably 190 mol or less, and more preferably 180 mol or less.

  Isosorbide is 1-100 mol with respect to 100 mol of the dicarboxylic acid component. When the amount is less than 1 mol, the thermal stability of the resulting polyester and the effect of suppressing by-products are not observed, and when the amount is 100 mol or more, non-polycondensed isosorbide remains and the moldability deteriorates. 10-80 mol is preferable and 10-50 mol is more preferable.

  The polycondensation reaction (C) in the third step is preferably performed using at least an antimony compound and a magnesium compound. Specifically, the inside of the reactor to which the low polymer obtained by the esterification reaction or transesterification reaction is added is heated to 250 to 350 ° C. to melt the low polymer. By adding at least 0.3 to 30 mmol of an antimony compound and 0.3 to 30 mmol of a magnesium compound and then reducing the pressure to 1000 to 0.1 Pa with respect to 100 mol (charge amount) of the dicarboxylic acid component. The polycondensation reaction is started (hereinafter referred to as “the time when the polycondensation reaction is started”), and the polycondensation reaction is performed. By using a magnesium compound in combination with the antimony compound, the polycondensation reaction proceeds smoothly. In addition, the range of 0.3-10 mmol of antimony compounds and 0.3-10 mmol of magnesium compounds is more preferable with respect to 100 mol of dicarboxylic acid components. The polycondensation reaction is carried out until the stirring torque reaches a predetermined value, that is, until the polyester reaches a desired viscosity (hereinafter referred to as “the final arrival point of the polycondensation reaction”) to obtain a high molecular weight polyester. The desired viscosity is estimated by measuring the torque of the stirring shaft during the polycondensation reaction. The obtained pellet is dissolved in orthochlorophenol and measured using an Ubbelohde viscometer (IV). Is in a range of 0.6 to 0.7 dl / g. If it is this range, it will become polyester excellent in a moldability and heat stability.

  As the dicarboxylic acid component of the present invention, as the aliphatic dicarboxylic acid component, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid or dimer acid, or an alkyl ester thereof, aromatic Terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, 5-tetrabutylphosphonium isophthalic acid, 5-sodium sulfoisophthalic acid, or alkyl esters thereof Etc. Aromatic dicarboxylic acid or aromatic dicarboxylic acid alkyl ester is preferably used, and terephthalic acid or terephthalic acid dimethyl ester is more preferable in that a polyester having a high melting point and can be easily processed into a fiber or a film can be obtained.

  As diol components other than isosorbide of the present invention, ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, cyclohexanedimethanol, xylylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or bisphenol A-ethylene oxide adduct, etc. Among these, ethylene glycol is preferable in that a polyester that can be easily processed into a fiber or a film can be obtained.

  The polyester of the present invention may be any polyester as long as it can be obtained using a preferred diol component using isosorbide and a preferred dicarboxylic acid component. Each of the dicarboxylic acid component and the diol component may be used alone, or two or more types may be used in combination.

  In the polyester production method of the present invention, a catalyst may be used in the esterification reaction, or no catalyst may be used. When using a catalyst, compounds such as manganese, cobalt, zinc, titanium and calcium are listed. Moreover, as a catalyst used for transesterification, compounds such as magnesium, manganese, calcium, cobalt, zinc, lithium, and titanium are used. In the polycondensation reaction, at least an antimony compound and a magnesium compound are used as a catalyst, and other compounds such as titanium, aluminum, tin, and germanium may be added.

  Examples of antimony compounds include antimony oxides, antimony carboxylic acids, and antimony alkoxides. Specifically, antimony oxides include antimony trioxide, antimony pentoxide, and the like, and antimony carboxylic acid. Examples include antimony acetate, antimony oxalate, and antimony potassium tartrate, and examples of the antimony alkoxide include antimony tri-n-butoxide and antimony triethoxide.

  Specific examples of the magnesium compound include magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, and magnesium carbonate.

  Titanium compounds include titanium alkoxides such as titanium complex, tetra-i-propyl titanate, tetra-n-butyl titanate, or tetra-n-butyl titanate tetramer, titanium oxide obtained by hydrolysis of titanium alkoxide, titanium acetyl Examples include acetonate. Among these, a titanium complex having a polycarboxylic acid and / or a hydroxycarboxylic acid and / or a polyhydric alcohol as a chelating agent is preferable from the viewpoint of the thermal stability of the polymer, the color tone, and the small amount of deposit around the mouthpiece. Examples of the chelating agent for the titanium compound include lactic acid, citric acid, mannitol, and tripentaerythritol.

  Examples of the aluminum compound include aluminum carboxylate, aluminum alkoxide, aluminum chelate compound, or basic aluminum compound. Specifically, aluminum acetate, aluminum hydroxide, aluminum carbonate, aluminum ethoxide, aluminum isopropoxide, Examples thereof include aluminum acetylacetonate and basic aluminum acetate.

  Examples of tin compounds include monobutyltin oxide, dibutyltin oxide, methylphenyltin oxide, tetraethyltin oxide, hexaethylditin oxide, triethyltin hydroxide, monobutylhydroxytin oxide, monobutyltin trichloride, or dibutyltin sulfide. It is done.

  Examples of germanium compounds include germanium oxides and germanium alkoxides. Specifically, germanium oxides include germanium dioxide, germanium tetroxide, germanium alkoxides, germanium tetraethoxide, germanium tetrabutoxide, and the like. Is mentioned.

  Specific examples of the manganese compound include manganese chloride, manganese bromide, manganese nitrate, manganese carbonate, manganese acetylacetonate, and manganese acetate.

  Specific examples of the calcium compound include calcium oxide, calcium hydroxide, calcium alkoxide, calcium acetate, and calcium carbonate.

  Specific examples of the cobalt compound include cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt acetylacetonate, cobalt naphthenate, and cobalt acetate tetrahydrate.

  Specific examples of the zinc-based compound include zinc oxide, zinc alkoxide, and zinc acetate.

  These metal compounds may be hydrates.

  In the method for producing a polyester of the present invention, at least a phosphorus compound or an alkali metal hydroxide may be added as a stabilizer. Specifically, phosphoric acid, trimethyl phosphate, ethyl diethylphosphonoacetate and the like are preferable, and 3,9-bis (2,6-di-t-butyl-4-methylphenoxy) -2,4,8,10. -Tetraoxa-3,9-diphosphaspiro [5,5] undecane (PEP-36: manufactured by Asahi Denka) or tetrakis (2,4-di-t-butyl-5-methylphenyl) [1,1-biphenyl]- Trivalent phosphorus compounds such as 4,4'-diylbisphosphonite (GSY-P101: manufactured by Osaki Kogyo Co., Ltd.) and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide improve the color tone and thermal stability. From the aspect, it is more preferable.

  Furthermore, if necessary, color tone adjusters, antioxidants, ultraviolet absorbers, flame retardants, fluorescent brighteners, matting agents, plasticizers or antifoaming agents, or other additives may be blended as necessary. Also good. These may be used alone or in combination of two or more.

  In the present invention, solid phase polymerization may be further performed in order to obtain a higher molecular weight polyester. The solid-state polymerization is not particularly limited in apparatus and method, but is carried out by heat treatment under an inert gas atmosphere or under reduced pressure. Further, as the reduced pressure, it is advantageous to use a reduced pressure condition because the time required for the solid phase polymerization reaction can be shortened, but it is preferable to maintain 110 Pa or more.

  In addition, it is preferable that the hunter value (b value) of a polyester pellet is 10 or less as a color tone of the polyester obtained by the present invention using a color difference meter (SM color computer model SM-T45 manufactured by Suga Test Instruments Co., Ltd.). 7 or less is more preferable. The larger the b value, the stronger the yellow and the worse the color tone.

  Moreover, it is preferable that the glass transition temperature (Tg) of a polyester pellet is 82 degreeC or more, and 85 degreeC or more is more preferable using a differential scanning calorimeter (DSC7 by Perkin-Elmer Co.) as thermal stability. When Tg is high, the thermal stability of the polyester is excellent.

The content of diethylene glycol as a by-product is preferably 0.8 wt% or less. The obtained polyester pellets are dissolved in a solvent, and the filtrate is measured by gas chromatography.

  The polyester obtained in the present invention can be molded by a known processing method, and can be processed into various products such as fibers, films, bottles, and injection molded products.

  When processing the polyester of the present invention into various products, various additives such as colorants including pigments and dyes, lubricants, antistatic agents, flame retardants, ultraviolet absorbers, as long as the effects of the present invention are not impaired. One or more additives such as an antibacterial agent, a nucleating agent, a plasticizer, and a release agent may be added.

  The polyester of the present invention is excellent in color tone and thermal stability, further utilizing the feature that the production amount of diethylene glycol, which is a by-product that may be eluted when formed into a molded product, is small, fibers, films, bottles, It can be used as various products such as injection-molded products. These products can be used for agricultural materials, horticultural materials, fishery materials, civil engineering / architectural materials, stationery, medical supplies, automotive parts, electrical / electronic parts or It is useful for other purposes.

  The physical property values in the examples were measured by the methods described below.

(1) Color tone of polyester Using a color difference meter (SM color computer model SM-T45, manufactured by Suga Test Instruments Co., Ltd.), the Hunter value (b value) of the polyester pellets was measured. The larger the b value, the stronger the yellow and the worse the color tone.

(2) Thermal characteristics of polyester Using a differential scanning calorimeter (DSC7 manufactured by Perkin Elmer), the glass transition temperature (Tg) of the polyester pellets was measured. In addition, it has the outstanding thermal stability, so that Tg is high.

(3) Diethylene glycol content in polyester Aminoethanol and 1,6-hexanediol as an internal standard substance were added to the polyester pellets and decomposed at 260 ° C. After cooling, methanol was added, neutralized with acid, and the precipitate was filtered. The filtrate was measured by gas chromatography (manufactured by Shimadzu Corporation, GC-14B).

Example 1
After adding 50 L of chloroform to 100 mol of isosorbide in a nitrogen atmosphere to form a suspension, the mixture was refluxed by heating to an internal temperature of 61 ° C. using an oil bath while maintaining the nitrogen atmosphere to dissolve isosorbide. Then, it cooled to room temperature over 12 hours, stirring slowly, and the crystal | crystallization of isosorbide was deposited. Under a nitrogen atmosphere, the precipitated crystals of isosorbide were filtered through a filter with 5 μm retained particles and washed with chloroform. The obtained crystal was transferred to a flask and dried under reduced pressure at 100 mmHg. The flask containing isosorbide was returned to normal pressure using nitrogen, and 20 moles of the obtained isosorbide (75 moles) were weighed into a flask for transesterification reaction in a nitrogen atmosphere.

  To the flask was added 100 mol of dimethyl terephthalate, 160 mol of ethylene glycol, and 10 mmol of magnesium acetate tetrahydrate. After melting at 150 ° C. in a nitrogen atmosphere, the temperature was raised to 240 ° C. with stirring, and methanol was distilled off. A transesterification reaction was performed to obtain bis (hydroxyethyl) terephthalate containing isosorbide.

  The obtained bis (hydroxyethyl) terephthalate containing isosorbide was put into a test tube for polycondensation and kept in a molten state at 250 ° C. in a nitrogen atmosphere, and then 5 mmol of antimony trioxide and 5 mmol of magnesium acetate tetrahydrate. 1 mmol of potassium hydroxide and 10 mmol of phosphoric acid were added. The reaction was started after 5 minutes had passed since each compound was added. The temperature in the reactor was raised from 250 ° C. to 280 ° C., the pressure was reduced from normal pressure to 100 Pa, and a polycondensation reaction was performed at 280 ° C. and 100 Pa for 60 minutes. After completion of the polycondensation reaction, the melt was discharged in the form of strands, cooled, and immediately cut to obtain pellets. The obtained pellet was dissolved in orthochlorophenol, and the intrinsic viscosity (IV) measured using an Ubbelohde viscometer was 0.6 dl / g. Moreover, color tone, thermal stability, and diethylene glycol content were measured using the obtained pellets. The results are shown in Table 1.

Example 2
Example 1 was repeated except that the weight of isosorbide used in the transesterification reaction and the weight of ethylene glycol were changed. Intrinsic viscosity (IV) was 0.6 dl / g.

Comparative Example 1
The same procedure as in Example 1 was performed except that the isosorbide used for the transesterification reaction was changed to a commercially available non-recrystallized isosorbide. Intrinsic viscosity (IV) was 0.6 dl / g.

Comparative Example 2
The same procedure as in Example 1 was conducted except that isosorbide was not used in the transesterification reaction and the weight of ethylene glycol was changed. Intrinsic viscosity (IV) was 0.6 dl / g.

  Example 1 of the present invention is particularly excellent in color tone as compared with Comparative Example 1 in which isosorbide is not recrystallized. Moreover, compared with the comparative example 2 which does not use an isosorbide, Example 1 and 2 improved thermal stability and content of diethylene glycol fell.

Claims (4)

For 100 moles of dicarboxylic acid component
A method for producing a polyester in which 100 to 200 mol of a diol component is polycondensed,
The diol component is a diol component containing 1 to 100 mol of isosorbide with respect to 100 mol of the dicarboxylic acid component,
The isosorbide is purified isosorbide,
A process for producing a polyester, wherein a series of steps from a purification step of isosorbide to a polycondensation step is performed in an inert gas atmosphere. The method for producing a polyester according to claim 1, wherein the dicarboxylic acid component is an aromatic dicarboxylic acid or an aromatic dicarboxylic acid alkyl ester. The method for producing a polyester according to claim 1 or 2, wherein the polycondensation is performed using at least an antimony compound and a magnesium compound. The method for producing a polyester according to any one of claims 1 to 3, wherein the purification of the isosorbide is recrystallization with an organic solvent in which isosorbide is soluble.