Copolyester resin, molded article, heat-shrinkable film, and fiber

Abstract

A copolyester resin which overcomes the problems of die fouling and foreign-matter adhesion to films, etc. that occur in continuous production of the films, etc. and the problem of copolyester recyclability. This copolyester resin comprises a dicarboxylic acid and diols as constituent components, and is characterized in that the dicarboxylic acid component comprises terephthalic acid as a main component, that the diol component comprises ethylene glycol as a main component and contains diethylene glycol and triethylene glycol in amounts of 7-30 mol% and 0.05-2 mol%, respectively, with respect to the whole diol component, which is taken as 100 mol%, that the content of a cyclic dimer composed of tetraphthalic acid and diethylene glycol is 7,000 ppm or less, and that the content of a cyclic dimer composed of terethphalic acid, diethylene glycol, and triethylene glycol is 200 ppm or less.

Description

Technical Field

[0001] The present invention relates to a copolymerized polyester resin that is excellent in transparency, color tone, recyclability, and moldability, and has little generation of dirt and foreign matter adhesion around a molding die, a film die head, and a fiber die.

Background Art

[0002] Polyester, especially polyethylene terephthalate (PET) produced from terephthalic acid (hereinafter sometimes abbreviated as TPA) and ethylene glycol (hereinafter sometimes abbreviated as EG) as raw materials, is widely used in applications such as containers, films, sheets, and fibers because of its excellent chemical and physical properties.

[0003] In recent years, a polyester copolymerized with diethylene glycol (hereinafter sometimes abbreviated as DEG) (hereinafter sometimes abbreviated as a copolymerized polyester) during the production of such polyethylene terephthalate (PET) has attracted attention because of its excellent transparency, impact resistance, moldability, heat resistance, etc., and has been used as a raw material polymer for various applications, especially for molded articles such as films, sheets, injection molded articles, and deformed molded articles.

[0004] On the other hand, vinyl chloride resins are used for molded articles for outdoor use such as building materials due to their processability, environmental stability, price competitiveness, etc. However, due to concerns about carcinogenicity and endocrine disrupting effects caused by the elution of monomers and plasticizers from these molded articles, and problems such as the generation of toxic gases during incineration, the demand for alternatives to polyester resins containing the above-mentioned copolymerized polyester with DEG is increasing.

[0005] Technologies related to copolyester with the amount of diethylene glycol copolymerization specified within a specific range to improve transparency, chemical resistance, moldability, etc., and molded articles made from said copolyester have been proposed (see, for example, Patent Documents 1, 2, and 3). However, when continuously producing films or molded articles using these technologies, there is a problem of foreign matter adhering in the vicinity of the die. Also, with regard to the problem of foreign matter adhering in the vicinity of the die, etc., technologies have been proposed to improve by controlling the cyclic trimer of terephthalic acid and ethylene glycol in polyethylene terephthalate (see, for example, Patent Documents 4 and 5). However, when continuously producing films, molded articles, or fibers using these technologies, low melting point foreign matter adheres adhesively in the vicinity of the die or mold, etc., and this adheres adhesively to the surface of the film, reducing the commercial value. Also, there are problems such as coloring and a decrease in molecular weight due to resin degradation, and further problems occur during recycling, etc., and solutions are being sought.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention was devised in view of the problems of such prior art, and solves the problems of die fouling and foreign matter adhesion to films, molded articles, or fibers when continuously producing films, molded articles, or fibers, the problem of recyclability required for the thermal stability and thermal oxidation stability of copolyester, and the problems of resin coloring and molecular weight reduction during recycling.

Means for Solving the Problems

[0008] In response to the above problems, by making the content of the cyclic dimer composed of terephthalic acid and diethylene glycol in the copolyester resin of a specific composition 7000 ppm or less, and the content of the cyclic dimer composed of terephthalic acid, diethylene glycol and triethylene glycol 200 ppm or less, it has been found that a copolyester resin can be provided which has high continuous productivity and can advantageously provide molded articles, films and fibers with high transparency and high commercial value. Furthermore, by using ethylene glycol, diethylene glycol and triethylene glycol in combination, the crystallinity and polymer viscosity are lowered, and the film-forming property of the film, the moldability of the fiber, and the transparency tend to be improved. Diethylene glycol used in the copolyester this time is very excellent in terms of cost, but it has been found that its thermal stability and thermal oxidation stability are low. Therefore, since the thermal stability and thermal oxidation stability of the copolyester during recycling of the film or molded article are low, it is considered that the resin deteriorates due to heating during film formation or molded article production, and the intrinsic viscosity and color of the film or molded article are greatly reduced. Next, the present inventor has discovered that in order to improve the thermal stability and thermal oxidation stability of the copolyester resin, the carboxyl terminal group concentration (AV) of the copolyester resin tends to be improved in the range of 8 to 25 eq / t. Furthermore, in order to further improve the thermal stability and thermal oxidation stability of the copolyester resin, the inventor recalled changing the type of catalyst used in the polymerization. Then, when using a combination of an aluminum compound and a phosphorus compound instead of the antimony compound, titanium compound, and germanium compound used as the polymerization catalyst, the thermal stability and thermal oxidation stability of the resin can be improved, and moreover, the activity as a polymerization catalyst is also excellent. Therefore, even if the number average molecular weight of the resin is lowered to increase the molding speed of the molded article, the film-forming speed of the film, and the productivity of the fiber, the number average molecular weight of the obtained molded article and film does not decrease significantly. As a result, no problems occur in the moldability of the molded article, the film-forming property of the film, or the strength, and it has been found that the manufacturing cost of the molded article, film, and fiber can be reduced.

[0009] The present invention has been completed based on the above findings and has the following configurations (1) to (7). (1) A copolyester resin comprising a dicarboxylic acid and a diol as constituent components, wherein in all polyester resin components, the main component of the dicarboxylic acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and when all the diol components are 100 mol%, the content of diethylene glycol is 7 to 30 mol% and the content of triethylene glycol is 0.05 to 2 mol%, the content of the cyclic dimer composed of terephthalic acid and diethylene glycol is 7000 ppm or less, and the content of the cyclic dimer composed of terephthalic acid, diethylene glycol and triethylene glycol is 200 ppm or less. A copolyester resin characterized by the above. (2) The copolyester resin according to (1), characterized in that the color b value is -5.0 to 10.0. (3) The carboxyl terminal group concentration (AV) is 8 to 25 eq / t, the copolyester resin contains aluminum atoms and phosphorus atoms, the content of aluminum atoms in the copolyester resin is 15 to 40 ppm, and the molar ratio of phosphorus atoms to aluminum atoms in the copolyester resin is 1.8 to 2.6. The copolyester resin according to (1) or (2), characterized by the above. (4) The copolyester resin according to any one of (1) to (3), characterized in that the haze value at a thickness of 5 mm of the stepped molded plate obtained by molding the copolyester resin is 10% or less. (5) A molded article characterized by containing the copolyester resin according to any one of (1) to (4). (6) A heat-shrinkable film characterized by containing the copolyester resin according to any one of (1) to (4). (7) A fiber characterized by containing the copolyester resin according to any one of (1) to (4).

Effects of the Invention

[0010] When continuously producing films, molded articles, or fibers, the copolymer polyester resin of the present invention has less die fouling and less generation of foreign matter adhering to the films or molded articles, and has greatly reduced recyclability required for the thermal stability and thermal oxidation stability of the resin, as well as coloring of the resin during recycling.

[0011] In addition, molded articles, films, and fibers obtained from the copolymer polyester resin of the present invention can have recyclability, heat resistance, and a beautiful appearance.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the copolymer polyester resin of the present invention will be specifically described. The copolymer polyester resin of the present invention is a polyester resin composed of a dicarboxylic acid component and a diol component. When the main component of the dicarboxylic acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and all the diol components are 100 mol%, the content of diethylene glycol is 7 to 30 mol% and the content of triethylene glycol is 0.05 to 2 mol%. Although the main component of the dicarboxylic acid component is terephthalic acid, this means that terephthalic acid is the most contained in the dicarboxylic acid component in terms of mol%. Although the main component of the diol component is ethylene glycol, this means that ethylene glycol is the most contained in the diol component in terms of mol%. The content of diethylene glycol is preferably 10 to 30 mol%, more preferably 15 to 25 mol%. The content of triethylene glycol is preferably 0.05 to 1.5 mol%, more preferably 0.1 to 1.2 mol%.

[0013] In the present invention, the cyclic dimer composed of terephthalic acid and diethylene glycol, and the cyclic dimer composed of terephthalic acid, diethylene glycol, and triethylene glycol represent the following compounds. The former is a cyclic dimer (hereinafter abbreviated as T2D2) in which terephthalic acid, diethylene glycol, terephthalic acid, and diethylene glycol are cyclically bonded in this order, and the latter is a cyclic dimer (hereinafter abbreviated as T2D1TE1) in which terephthalic acid, diethylene glycol, terephthalic acid, and triethylene glycol are cyclically bonded in this order. It is characterized in that the content of T2D2 is 7000 ppm or less and the content of T2D1TE1 is 200 ppm or less. In the present invention, the "copolyester resin" refers not only to the chemical substance called polyester, but also to those containing oligomer components such as T2D2 and T2D1TE1, and catalyst components described later. However, when explaining the chemical substance called polyester, for convenience, it may be described as "copolyester resin".

[0014] When the contents of diethylene glycol and triethylene glycol are within the above ranges, it becomes possible to obtain a copolyester resin with high transparency, that is, amorphous. When the contents of diethylene glycol and triethylene glycol are less than the lower limit of the above range, crystallinity occurs, so the transparency of molded products and films deteriorates, sufficient transparency cannot be achieved, and the commercial value tends to be lost. When the content of triethylene glycol exceeds 2 mol%, the heat resistance tends to decrease. Also, the lower limit value of this content is 0.05 mol% from the economic efficiency during production. Here, "amorphous" refers to a sample left at 120°C for 120 minutes in a Yamato DP63 dryer, which is heated from -100°C to 300°C at 20°C / min using a differential scanning calorimeter (DSC), then cooled from 300°C to -100°C at 50°C / min, and subsequently heated from -100°C to 300°C at 20°C / min again, and shows no melting peak in either of the two heating processes. Due to its amorphous nature, the copolyester resin of the present invention can have sufficient transparency to be suitably used, especially for thick molded articles. That is, being "amorphous" under these measurement conditions means that the transparency of the film can be maintained at a high quality, and furthermore, even for a thick film, sufficient transparency can be maintained. Additionally, as the amount of T2D2 also increases, the fouling near the resin outlet of the die of the continuous film forming machine, the fiber extrusion molding machine, or the mold of the injection molding machine becomes extremely severe, and the adhered foreign matter tends to adhere to the surface of the molded article, resulting in a decrease in commercial value. Also, when exceeding the above range, the amount of free T2D1TE1 increases, and the fouling near the resin outlet of the die of the extrusion molding machine, the mold of the injection molding machine, etc. becomes extremely severe during continuous film formation and fiber extrusion, and the adhered foreign matter tends to adhere to the surface of the film, molded product, or fiber, leading to a decrease in commercial value. The adhesion mechanism is unclear, but due to the influence of diethylene glycol in T2D2, the melting point and glass transition temperature are low, resulting in adhesiveness and acting as an adhesive. Furthermore, due to the influence of diethylene glycol and triethylene glycol in T2D1TE1, the melting point and glass transition temperature are lower than those of T2D2, resulting in strong adhesiveness, and it is considered that the synergistic effect of T2D2 and T2D1TE1 increases the adhesion to the die during molding or film extrusion molding.

[0015] Diethylene glycol is also generated by the condensation of ethylene glycol during the polymerization of the copolyester resin. The amount of diethylene glycol generated by this condensation varies depending on the polymerization conditions and the manufacturing equipment, but is about 0.5 to 2.0 mol% based on all diol components. Considering this amount, the amount of diethylene glycol added as a raw material can be considered. In addition, triethylene glycol is also produced by the condensation of ethylene glycol and diethylene glycol during the polymerization of the copolyester resin. The amount of triethylene glycol produced by this condensation varies depending on the polymerization conditions and the production equipment. However, when only ethylene glycol is present at the start of polymerization, it is about 0.01 to 0.3 mol% based on all the diol components. Considering this amount, the amount of triethylene glycol added as a raw material can be determined. In some cases, it may not be necessary to add triethylene glycol as a raw material. Since triethylene glycol is also produced by the condensation of ethylene glycol and diethylene glycol, controlling it within the above range is important for maintaining the commercial value.

[0016] The content of T2D2 is preferably 6000 ppm or less, more preferably 5000 ppm or less. When it exceeds 7000 ppm, the fouling near the resin outlet of the die of the extrusion molding machine during the production of films and fibers becomes severe, and the attached foreign substances adhere to the surface of the molded body, deteriorating the surface state and also affecting the transparency, resulting in a decrease in commercial value. Also, during the continuous injection molding of molded products, the exhaust port of the injection mold becomes clogged, and normal molded products cannot be obtained. The lower limit value of this content is 1000 ppm based on the economic efficiency during production. The content of T2D2 is the value quantified by the measurement method in the examples described later.

[0017] The content of T2D1TE1 is preferably 150 ppm, more preferably 100 ppm or less. When it exceeds 200 ppm, the fouling near the resin outlet of the die of the extrusion molding machine during the production of films and fibers becomes severe, and the attached foreign substances adhere to the surface of the molded body, deteriorating the surface state and also affecting the transparency, tending to result in a decrease in commercial value. Also, during the continuous injection molding of molded products, the exhaust port of the injection mold becomes clogged, and normal molded bodies cannot be obtained. The lower limit value of this content is 1 ppm based on the economic efficiency during production. The content of T2D1TE1 is the value quantified by the measurement method in the examples described later.

[0018] The main dicarboxylic acid component of the copolymerized polyester resin of the present invention is terephthalic acid, and the proportion of the terephthalic acid component to the total dicarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and most preferably 100 mol%.

[0019] As other dicarboxylic acid components that can be used together with terephthalic acid, there are (1) aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid and functional derivatives thereof; (2) aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, glutaric acid, dimer acid, dodecanedicarboxylic acid, azelaic acid and functional derivatives thereof; (3) alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid and functional derivatives thereof, and the like.

[0020] It is preferable that the total diol components of the copolymerized polyester resin of the present invention are composed of ethylene glycol, diethylene glycol and triethylene glycol. However, other diol components may be used in order to impart other functions or improve characteristics without inhibiting various characteristics aimed at by the present invention. The total amount of ethylene glycol, diethylene glycol and triethylene glycol with respect to the total diol components is preferably 85 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and most preferably 100 mol%.

[0021] As other diol components, there are (1) aliphatic glycols such as tetramethylene glycol, pentamethylene glycol, hexamethylene glucol; (2) alicyclic glycols such as 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol; (3) aromatic glycols such as p-xylylene glycol, m-xylylene glycol and the like. Among these, 1,4-cyclohexanedimethanol is preferable. Also, these diol components may be used alone or in combination of two or more in any ratio.

[0022] In the copolymerized polyester resin of the present invention, it is preferable to contain 0.001 to 5 mol% of a polyfunctional compound having three or more carboxyl groups, hydroxyl groups or their ester-forming groups (for example, trimellitic acid, pyromellitic acid, glycerin, trimethylolpropane, etc.) in the acid component and / or glycol component of the copolymerized polyester resin in order to enhance the profile extrusion moldability.

[0023] The copolymerized polyester resin of the present invention can be produced by any of the production methods by direct esterification reaction and polycondensation reaction, or by transesterification reaction and polycondensation reaction. The above reactions may be carried out in a batch reactor or a continuous reactor, but it is preferable to use a continuous reactor in terms of economy and quality stability.

[0024] In a continuous reactor (continuous polycondensation method), the esterification reaction, transesterification reaction and melt polycondensation reaction may each be carried out in one step, but it is preferable to carry them out in multiple steps. When the esterification reaction or transesterification reaction is carried out in multiple steps, the number of reaction vessels is preferably 2 to 3. Also, when the melt polycondensation is carried out in multiple steps, the number of reaction vessels is preferably 3 to 7.

[0025] When the copolymerized polyester resin of the present invention is produced by a continuous polycondensation method, a slurry containing 1.02 to 1.5 moles, preferably 1.03 to 1.4 moles of all glycols per mole of all dicarboxylic acids or their ester derivatives is prepared, and this is continuously supplied to the esterification reaction step containing oligomers. The esterification reaction temperature is usually 240 to 270°C, preferably 250 to 265°C. Also, the pressure in the reaction vessel is usually 0.2 MPa or less, preferably 0.01 to 0.05 MPa. Further, the temperature of the polycondensation reaction is usually 265 to 285°C, preferably 270 to 280°C, and the pressure in the reaction vessel is usually 1.5 hPa or less, preferably 0.5 hPa or less. The reaction time of the esterification reaction is preferably 5 hours or less, particularly preferably 2 to 3.5 hours. Also, the reaction time of the polycondensation reaction is preferably 3 hours or less, particularly preferably 1 to 2 hours.

[0026] When the copolymerized polyester resin of the present invention is produced by a batch polycondensation method, the esterification reaction temperature is usually 220 to 250°C, preferably 230 to 245°C. Also, the pressure in the reaction vessel is usually 0.2 to 0.4 MPa, preferably 0.25 to 0.30 MPa. Further, the polycondensation reaction may be carried out in one step or divided into a plurality of steps. When carried out in one step, the pressure is gradually reduced and the temperature is raised, and the final temperature is in the range of 260 to 280°C, preferably 265 to 275°C, and the final pressure is usually 3 hPa or less, preferably 0.5 hPa or less. The reaction time of the esterification reaction is preferably 4 hours or less, particularly preferably 2 to 3 hours. Also, the reaction time of the polycondensation reaction is preferably 5 hours or less, particularly preferably 1 to 3 hours.

[0027] Next, when producing a low polycondensate by a continuous transesterification reaction, a solution containing dimethyl terephthalate and 1.1 to 1.6 moles, preferably 1.2 to 1.5 moles, of glycol per mole of dimethyl terephthalate is prepared and continuously supplied to the transesterification reaction step. The transesterification reaction temperature is usually 200 to 270°C, preferably 230 to 265°C. In the case of the transesterification method, it is necessary to use a transesterification catalyst in addition to the polycondensation catalyst. The obtained low polycondensate is reacted in the same manner as the above-mentioned continuous polycondensation.

[0028] Also, when producing a low polycondensate by a batch transesterification reaction, dimethyl terephthalate and 2.3 to 2.0 moles, preferably 2.2 to 2.0 moles, of glycol per mole of dimethyl terephthalate are charged into a batch reactor and reacted in the presence of a transesterification catalyst. The obtained low polycondensate is polycondensed in the same manner as in the case of the above-mentioned esterification reaction.

[0029] As the polycondensation catalyst, at least one of an antimony compound, a germanium compound, a titanium compound, and an aluminum compound can be used. Examples of the antimony compound include antimony trioxide, antimony pentoxide, antimony acetate, and antimony glycoloxide. Among these, antimony trioxide, antimony acetate, and antimony glycoloxide are preferred, and antimony trioxide is particularly preferred. These antimony compounds are preferably contained in an amount of 50 to 400 ppm, more preferably 100 to 350 ppm, and particularly preferably 150 to 300 ppm, based on the copolymerized polyester resin to be produced.

[0030] In addition, examples of the germanium compound include compounds such as crystalline germanium dioxide, amorphous germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, germanium phosphite, etc. Among these, crystalline germanium dioxide and amorphous germanium dioxide are more preferable, and amorphous germanium dioxide is particularly preferable. These germanium compounds are preferably contained in an amount of 10 to 100 ppm, more preferably 30 to 70 ppm, and particularly preferably 30 to 50 ppm, based on the copolymerized polyester resin to be produced.

[0031] In addition, examples of the titanium compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyl titanate and their partial hydrolyzates, titanium acetate, titanyl oxalate, ammonium titanyl oxalate, sodium titanyl oxalate, potassium titanyl oxalate, calcium titanyl oxalate, strontium titanyl oxalate and other titanyl oxalate compounds, titanium trimellitate, titanium sulfate, titanium chloride, hydrolyzates of titanium halides, titanium cyanide, titanium fluoride, potassium hexafluorotitanate, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, titanium complex compounds with hydroxy polycarboxylic acids or nitrogen-containing polycarboxylic acids, composite oxides composed of titanium and silicon or zirconium, reaction products of titanium alkoxides and phosphorus compounds, etc. Among these, titanium tetraisopropoxide, titanium tetrabutoxide, and potassium titanyl oxalate are preferable, and titanium tetrabutoxide is particularly preferable. These titanium compounds are preferably contained in an amount of 1 to 50 ppm, more preferably 2 to 20 ppm, and particularly preferably 3 to 10 ppm, based on the copolymerized polyester resin to be produced.

[0032] As a polycondensation catalyst, an aluminum compound is preferred in terms of recyclability (heat resistance, thermal oxidation stability). The aluminum compound is preferably used in combination with a phosphorus compound. As the aluminum compound constituting the polymerization catalyst used in producing the copolyester resin of the present invention, known aluminum compounds can be used without limitation.

[0033] Specific examples of the aluminum compound include aluminum acetate, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxychloride, and organic aluminum compounds such as aluminum acetylacetonate and aluminum oxalate, and partial hydrolyzates thereof. Among these, carboxylates, inorganic acid salts, and chelate compounds are preferred. Among these, aluminum acetate, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxychloride, and aluminum acetylacetonate are more preferred, and aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, and aluminum hydroxychloride are even more preferred, and aluminum acetate and basic aluminum acetate are most preferred.

[0034] The amount of the aluminum compound used in the polymerization catalyst is preferably such that, as aluminum atoms, 15 to 40 ppm remains with respect to the total mass of the resulting polyester resin, more preferably 17 to 38 ppm, and still more preferably 20 to 35 ppm. If the residual amount of aluminum atoms is less than the above range, the catalytic activity may be poor. On the other hand, if the residual amount of aluminum atoms exceeds the above range, problems may arise such as a decrease in thermal stability and thermal oxidation stability, or the generation of foreign substances and an increase in coloring due to aluminum. As described above, since almost 100% of the amount of the aluminum compound used as the polymerization catalyst remains even when placed in a reduced-pressure environment during polyester polymerization, the amount used can be considered to be the residual amount. If it is acceptable to slightly sacrifice the properties of the copolyester resin, the content of aluminum atoms in the copolyester resin may be 9 to 42 ppm.

[0035] The phosphorus compounds used in the polymerization catalyst are not particularly limited. However, when phosphonic acid-based compounds or phosphinic acid-based compounds are used, the effect of improving the catalyst activity is great and preferable. Among these, when a phosphonic acid-based compound is used, the effect of improving the catalyst activity is particularly great and preferable.

[0036] Among these phosphorus compounds, when a phosphorus compound having a phenol moiety in the same molecule is used, the effect of improving the thermal stability and thermo-oxidative stability of the resin is great and preferable. The phosphorus compound having a phenol structure is not particularly limited. However, when one or more compounds selected from the group consisting of phosphonic acid-based compounds and phosphinic acid-based compounds having a phenol moiety in the same molecule are used, both the effect of improving the catalyst activity and the effect of improving the thermal stability and thermo-oxidative stability of the resin are great and preferable. Among these, when one or more phosphonic acid-based compounds having a phenol moiety in the same molecule are used, both the effect of improving the catalyst activity and the effect of improving the thermal stability and thermo-oxidative stability of the resin are particularly great and preferable.

[0037] Examples of the phosphorus compound having a phenol moiety in the same molecule include compounds represented by the following general formulas (1) and (2).

[0038]

Chemical formula

[0039]

Chemical formula

[0040] (In general formulas (1) to (2), R 1 represents a hydrocarbon group having 1 to 50 carbon atoms containing a phenol moiety, a hydroxyl group, a halogen group, an alkoxyl group, an amino group or other substituents and a hydrocarbon group having 1 to 50 carbon atoms containing a phenol moiety. R 4represents hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, a hydroxyl group, a halogen group, or a hydrocarbon group having 1 to 50 carbon atoms containing a substituent such as an alkoxyl group or an amino group. R 2 , R 3 each independently represents hydrogen, a hydrocarbon group having 1 to 50 carbon atoms, a hydroxyl group, or a hydrocarbon group having 1 to 50 carbon atoms containing a substituent such as an alkoxyl group. However, the hydrocarbon group may contain a branched structure, an alicyclic structure such as cyclohexyl, or an aromatic ring structure such as phenyl or naphthyl. R 2 and R 4 may be bonded to each other at their terminals.)

[0041] Examples of the phosphorus compound having a phenol moiety in the same molecule include p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonate, diethyl p-hydroxyphenylphosphonate, diphenyl p-hydroxyphenylphosphonate, bis(p-hydroxyphenyl)phosphinic acid, methyl bis(p-hydroxyphenyl)phosphinate, phenyl bis(p-hydroxyphenyl)phosphinate, p-hydroxyphenylphenylphosphinic acid, methyl p-hydroxyphenylphenylphosphinate, phenyl p-hydroxyphenylphenylphosphinate, p-hydroxyphenylphosphinic acid, methyl p-hydroxyphenylphosphinate, phenyl p-hydroxyphenylphosphinate, and the like. In addition, a phosphorus compound represented by the following general formula (3) can be mentioned.

[0042]

Chemical formula

[0043] In the general formula (3), X1 and X2 each represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or a metal having a valence of 1 or more. Further, when the metal has a valence of 2 or more, X2 may not be present. Furthermore, an anion corresponding to the excess valence of the metal may be arranged with respect to the phosphorus compound. Preferred metals include Li, Na, K, Ca, Mg, and Al.

[0044] When a phosphorus compound having a phenol moiety in these same molecules is added during the polymerization of a polyester, the catalytic activity of the aluminum compound is improved, and the thermal stability and thermal oxidation stability of the polymerized polyester resin are also improved. The reason is considered to be that the hindered phenol moiety in the phosphorus compound improves the thermal stability and thermal oxidation stability of the polyester resin. In this case, when the residual amount of the phosphorus compound becomes less than 31 ppm, the above-mentioned effects of improving thermal stability and thermal oxidation stability are diminished, and as a result, the effects of improving the thermal stability and thermal oxidation stability and the effect of improving coloring of the polyester resin of the present invention may not be observed.

[0045] Among the above, the phosphorus compound preferably used as a polycondensation catalyst is at least one phosphorus compound selected from the compounds represented by the following chemical formula (4) and chemical formula (5).

[0046]

Chemical formula

[0047]

Chemical formula

[0048] As the compound represented by the above chemical formula (4), Irganox 1222 (manufactured by BASF) is commercially available. Also, as the compound represented by chemical formula (5), Irganox 1425 (manufactured by BASF) is commercially available and can be used.

[0049] The amount of the phosphorus compound used in the polymerization catalyst is preferably such that the residual amount of phosphorus atoms is 31 to 119 ppm, more preferably 39 to 105 ppm, and still more preferably 48 to 92 ppm, based on the total mass of the resulting copolymerized polyester resin. If the amount of phosphorus atoms remaining exceeds the above upper and lower limits, the polymerization activity may be decreased. As described above, when the phosphorus compound is placed in a reduced-pressure environment during the polymerization of the polyester resin, a part of the amount initially added to the system as a catalyst is removed outside the system. Since this removal amount is at a substantially constant ratio, it can be said that it is appropriate to define it by the residual amount in consideration of the removal ratio. When the properties of the copolymerized polyester resin may be slightly sacrificed, the content of phosphorus atoms in the copolymerized polyester resin may be 19 to 125 ppm.

[0050] Also, as described above, in the present invention, the ratio of the phosphorus compound to the aluminum compound is also important. Specifically, in the present invention, the molar ratio of phosphorus atoms to aluminum atoms (P / Al ratio) in the polyester resin is preferably 1.8 to 2.6, more preferably 2.0 to 2.4, and still more preferably 2.1 to 2.3. The aluminum compound alone cannot fully exhibit its catalytic activity even when used as a polymerization catalyst. By using the phosphorus compound in combination with the aluminum compound as a polymerization catalyst at a specific ratio, the catalytic activity can be sufficiently enhanced. If the molar ratio of phosphorus atoms to aluminum atoms in the polyester resin is outside the above range, there is a possibility that the function as a polymerization catalyst cannot be fully achieved.

[0051] In the present invention, in addition to the above-mentioned aluminum compound and phosphorus compound, in order to further improve the catalytic activity without impairing the effects of the present invention, metal-containing polycondensation catalysts such as titanium compounds, tin compounds, and germanium compounds may be used in combination. In that case, the germanium compound is preferably 10 ppm or less as germanium atoms with respect to the mass of the obtained polyester resin, the titanium compound is preferably 3 ppm or less as titanium atoms with respect to the mass of the obtained polyester resin, and the tin compound is preferably 3 ppm or less as tin atoms with respect to the mass of the obtained polyester resin. However, for the purpose of the present invention, it is preferably not to use these metal-containing polycondensation catalysts such as titanium compounds, tin compounds, and germanium compounds as much as possible. Also, since the antimony compound generally used as a polymerization catalyst is inferior in the effect of improving the thermal stability and thermal oxidation stability of the resin as described above, it is better to refrain from using it in the present invention.

[0052] In addition, in the production of the copolymerized polyester resin of the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination. Examples of the alkali metal compound or alkaline earth metal compound include carboxylates such as acetates of these elements and alkoxides, and they are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, etc.

[0053] In the case of the direct esterification method, the polycondensation catalyst can be added at any time before the start of the esterification reaction or from after the completion of the pressurized esterification reaction to before the start of the initial polycondensation reaction. However, when an antimony compound or a titanium compound is used as the polycondensation catalyst, it is preferably added before the esterification reaction. Also, other polycondensation catalysts, heat stabilizers, and additives are preferably added after the esterification reaction.

[0054] In the case of the transesterification method, the polycondensation catalyst can be added at any time from before the start of the transesterification reaction to before the start of the initial polycondensation reaction. However, since the titanium compound has not only the function as a polycondensation catalyst but also the function as a transesterification catalyst, it is preferably added before the start of the transesterification reaction. Further, other polycondensation catalysts, heat stabilizers, and additives are preferably added after the completion of the transesterification reaction. Preferred examples of the transesterification catalyst include manganese acetate, magnesium acetate, and titanium compounds such as titanium tetrabutoxide. It is necessary to add the transesterification catalyst before the start of the transesterification reaction.

[0055] In addition, when using a catalyst other than the above aluminum compound, a phosphorus compound can be used as a stabilizer. Examples of the phosphorus compound include phosphoric acid, phosphorous acid, phosphonic acid, and their derivatives. Preferred specific examples include phosphoric acid, trimethyl phosphate, tributyl phosphate, triphenyl phosphate, monomethyl phosphate, dimethyl phosphate, monobutyl phosphate, dibutyl phosphate, phosphorous acid, trimethyl phosphite, tributyl phosphite, methylphosphonic acid, dimethyl methylphosphonate, dimethyl ethylphosphonate, dimethyl phenylphosphonate, diethyl phenylphosphonate, and diphenyl phenylphosphonate. Among these, trimethyl phosphate and phosphoric acid are particularly preferred. These phosphorus compounds are preferably contained in the resulting copolyester at 1 to 100 ppm, more preferably 3 to 70 ppm, and particularly preferably 5 to 50 ppm.

[0056] A cobalt compound can be blended to improve the color tone of the copolyester resin. By adding this cobalt compound, the color b value can be particularly reduced. The cobalt compound is preferably contained in the copolyester resin at 0.5 to 30 ppm as cobalt atoms, more preferably 1 to 20 ppm, and particularly preferably in the range of 1 to 15 ppm. When the content of cobalt atoms exceeds the above range, the copolyester resin turns black or has a strong blue tint due to the reduction of cobalt metal, the color L value becomes less than 50, the color b value becomes less than -5, and the commercial value decreases. Examples of the cobalt compound include cobalt acetate, cobalt chloride, cobalt benzoate, cobalt chromate, etc. Among these, cobalt acetate is preferred.

[0057] The copolyester resin obtained by the above continuous polycondensation method or batch polycondensation method is usually drawn out in a strand form from a discharge port provided at the bottom of the reaction vessel, cooled with water, and then cut into chips or sheets.

[0058] While controlling the amount of triethylene glycol in the present invention, a copolyester resin with a low content of free T2D2 and T2D1TE1 can be produced by the following method. A method of adding a specific diol component during or after the esterification reaction or transesterification reaction and then performing a polycondensation reaction is preferred. The specific diol component is preferably diethylene glycol or triethylene glycol, and more preferably diethylene glycol. For example, an amount of raw material monomers considering the additional amount to be added is first subjected to an esterification reaction or transesterification reaction. After the reaction, diethylene glycol is added, stirred for 5 minutes or more, and then polycondensed. The diethylene glycol component added additionally is preferably 7.5 to 30 mol% of the total diethylene glycol component. Alternatively, an amount of raw material monomers that takes into account the additional amount to be added is first subjected to an esterification reaction or a transesterification reaction, diethylene glycol is added during the reaction, and further diethylene glycol is additionally added after the reaction. After stirring for 5 minutes or more, polycondensation is carried out. The diethylene glycol component added additionally is preferably 5 to 20 mol% of the total diethylene glycol component. Furthermore, an amount of raw material monomers that takes into account the additional amount to be added is first subjected to an esterification reaction or a transesterification reaction, diethylene glycol and triethylene glycol are added during the reaction, and further diethylene glycol is additionally added after the reaction. After stirring for 5 minutes or more, polycondensation is carried out. The diol (diethylene glycol + triethylene glycol) component added additionally is preferably 7.5 to 30 mol% of the total diol (diethylene glycol + triethylene glycol) component.

[0059] Since triethylene glycol is also produced by the condensation of ethylene glycol and diethylene glycol, by adding and stirring a specific diol component during or after the esterification reaction or transesterification reaction, the amount of triethylene glycol produced in the esterification reaction or transesterification reaction can be controlled. Furthermore, during the polycondensation reaction, the cyclic T2D2 and T2D1TE1 already produced in the esterification reaction or transesterification reaction are ring-opened, and it is considered that T2D2 and T2D1TE1 are reduced. Furthermore, by extracting in a strand shape, cooling with water, and then contacting the chipped, sheet-shaped, or cut material with the vapor of diethylene glycol or triethylene glycol for a certain period of time, T2D2 and T2D1TE1 can also be reduced. The detailed mechanism is unknown, but it is thought that the cyclic T2D2 and T2D1TE1 are ring-opened by the vapor of diethylene glycol or triethylene glycol.

[0060] The copolymerized polyester resin obtained as described above preferably has a terminal carboxyl group concentration of 8 to 25 equivalents per ton of the polymer. More preferably, the terminal carboxyl group concentration is 23 equivalents / ton or less. When the terminal carboxyl group concentration is within the above range, it can contribute to suppressing the coloring of the copolymerized polyester resin. When the coloring of the copolymerized polyester resin may be slightly inferior, the terminal carboxyl group concentration may be 32 equivalents / t or less. If productivity (reaction time) is not considered, the lower limit of the terminal carboxyl group concentration is 0 equivalents / t.

[0061] The number average molecular weight of the copolymerized polyester resin of the present invention is preferably 15,000 to 30,000, more preferably 17,000 to 28,000, and still more preferably 18,000 to 27,000. When the number average molecular weight is less than the above range, the crystallinity increases, the haze increases, and furthermore, due to insufficient resin cohesive force, the strength and elongation of the molded product may be insufficient, resulting in brittleness and unusability. On the other hand, when it exceeds the above range, the melt viscosity increases too much, so the temperature optimal for various molding processes also increases, the thermal stability is poor, the sheet film-forming property decreases, and furthermore, the above-mentioned T2D2 and T2D1TE1 increase, resulting in deterioration of the transparency of the molded body.

[0062] The glass transition temperature of the copolymerized polyester resin of the present invention is preferably 40°C or higher and less than 120°C, more preferably 45°C or higher and less than 115°C, still more preferably 50°C or higher and less than 110°C, and particularly preferably 50°C or higher and less than 70°C. Here, the glass transition temperature refers to the value measured by raising the temperature at 20°C / min using a differential scanning calorimeter (DSC). When the glass transition temperature is less than the above range, when a profiled extruded molded product is used outdoors in summer, or during product transportation or warehouse storage in a sealed state in summer, the film or profiled extruded molded product is likely to undergo thermal deformation, resulting in many problems. Also, when the glass transition temperature exceeds the above range, the film-forming property and transparency of the sheet tend to decrease, and in some cases, it may not be usable depending on the application.

[0063] The color b value of the copolymerized polyester resin of the present invention is preferably from -5.0 to 10.0, more preferably the lower limit is -3.0, still more preferably -2.5, and the upper limit is more preferably 8, still more preferably 7. When the color b value exceeds 10.0, the yellowness of the copolymerized polyester resin becomes strong, which is not preferable in terms of color tone. On the other hand, when the numerical value of the color b value becomes larger in the negative direction than -5.0, the blueness of the copolymerized polyester resin becomes prominent, and it may not be usable depending on the application.

[0064] The haze value at the 5 mm thickness part of the stepped molded plate obtained by molding the copolymerized polyester resin of the present invention at a mold temperature of 10°C is preferably 15% or less, more preferably 10% or less, particularly preferably 7% or less. When the haze value exceeds the above value, the transparency of the molded product or film deteriorates, and it may not be usable in applications where strict transparency requirements are imposed.

[0065] Other components can be appropriately added to the copolymerized polyester resin of the present invention according to the application. For example, an impact resistance improver, a filler, an ultraviolet absorber, a surface treatment agent, a lubricant, a light stabilizer, a pigment, an antistatic agent, an antibacterial agent, a crosslinking agent, a sulfur-based antioxidant, a flame retardant, a plasticizer, a processing aid, a foaming agent, etc. can be added. The copolymerized polyester of the present invention can be suitably molded into various molded bodies by extrusion blow molding, extrusion molding, injection molding, profile extrusion molding, calender processing molding, etc., which have been generally used for PET, polyvinyl chloride, etc.

Examples

[0066] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. The properties of the copolymerized polyester resin were measured according to the following methods.

[0067] 1) Number average molecular weight It was measured by Waters gel permeation chromatography using chloroform / hexafluoroisopropanol mixed solvent (volume ratio = 9 / 1) as the solvent and polystyrene as the assay standard. A measured value in terms of polystyrene was obtained using the chloroform / hexafluoroisopropanol mixed solvent (volume ratio = 9 / 1) as the eluent.

[0068] 2) Intrinsic viscosity (IV) of the copolyester resin 0.1 g of the sample dried at 60 °C for 24 hours was accurately weighed, dissolved in 25 mL of a mixed solvent of phenol / tetrachloroethane (3 / 2 (mass ratio)), and measured at 30 °C using an Ostwald viscometer.

[0069] 3) T2D2 content 50 mg of the copolyester resin was dissolved in 1 mL of a hexafluoroisopropanol / chloroform mixed solution (volume ratio = 1 / 9), and further diluted by adding 4 mL of chloroform. 10 mL of methanol was added thereto to precipitate the polymer, followed by centrifugation. The supernatant after centrifugation was concentrated to dryness, redissolved in 0.4 mL of dimethylformamide, and the T2D2 content was measured by high performance liquid chromatography. Apparatus: Waters ACQUITY UPLC Column: Waters BEH-C18 2.1×150 mm (manufactured by Waters)

[0070] 4) T2D1TE1 content The T2D1TE1 content was measured by high performance liquid chromatography in the same manner as the above measurement of the T2D2 content.

[0071] 5) Composition ratio of the copolyester resin Approximately 5 mg of the copolyester resin sample was dissolved in 0.7 ml of a mixed solution of deuterated chloroform and trifluoroacetic acid (volume ratio 9 / 1), 1 and determined using 1H-NMR (manufactured by Varian, UNITY50).

[0072] 6) Color tone The color of the chips of the copolyester resin was measured using a colorimeter (Nippon Denshoku Co., Ltd., Model 1001DP), and the color b value was determined.

[0073] 7) Haze value Using an injection molding machine (Meiki Seisakusho Co., Ltd., M-150C-DM), the copolyester resin was melted at 280 °C, and a stepped molding plate with a thickness of 2 to 11 mm was molded at a mold temperature of 10 °C. The haze value (%) of the 5-mm-thick part was measured using a haze meter (Nippon Denshoku Co., Ltd., Model NDH2000).

[0074] 8) Molding test (sheet film formation evaluation) The dried copolyester resin sample was put into an extruder with a sheet die and a sheet with a thickness of about 0.5 mm was continuously molded for 2 days. The fouling adhesion situation at the die outlet and the state of the sheet surface were visually evaluated according to the following criteria. (Evaluation criteria) ◎: Almost no fouling adheres to the die outlet, and the sheet surface state is good ○: There is a little fouling adhering to the die outlet, but the sheet surface state is good △: There is a little fouling adhering to the die outlet, and there is a little foreign matter adhering to the sheet surface ×: The fouling adhering to the die outlet is extremely severe, and there are many adherents on the sheet surface

[0075] 9) DSC measurement of copolyester resin The sample left in a Yamato DP63 dryer at 120 °C for 120 minutes was heated from -100 °C to 300 °C at 20 °C / min using a differential scanning calorimeter (DSC), then cooled from 300 °C to -100 °C at 50 °C / min, and then heated from -100 °C to 300 °C at 20 °C / min again. Whether a melting peak appears in the two heating processes was confirmed. Those that do not show a melting peak in either of the two heating processes are marked as "○", and those that show a melting peak in either one are marked as "×".

[0076] 10) Thermal stability evaluation: Thermal oxidation decomposition parameter (TD) Place 3 g of chips of the dried copolymerized polyester resin into a glass test tube and immerse it in an oil bath at 280 °C for 120 minutes under a nitrogen atmosphere to melt it. It is determined by the following formula. [IV] after heating f1 was measured. TD was determined as follows. However, [IV] i and [IV] f1 respectively refer to IV (dL / g) before and after the heating test. TD = 0.245{[IV] f1 -1.47 - [IV] i -1.47} The thermal oxidative degradation parameter (TD) of the copolymerized polyester resin indicates that the smaller the value, the higher the thermal stability.

[0077] (Example 1) To a first esterification reaction vessel in which reactants remained in advance, a slurry prepared by adjusting the molar ratio (G / A) of all glycol components to the dicarboxylic acid component to 2.2, with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) as the glycol components, was continuously supplied. Next, under stirring, an esterification reaction was carried out at a tank internal pressure of 0.15 MPa and 257 °C so that the average residence time was 3 hours. This reaction product was transferred to a second esterification reaction vessel, and an esterification reaction was carried out at a tank internal pressure of 0.05 MPa under stirring at 257 °C so that the average residence time was 1 hour. Next, this esterification reaction product was transferred to a third esterification reaction vessel, and an esterification reaction was carried out under stirring at a tank internal pressure of 0.05 MPa and 257 °C. To the generated oligomer, an amount corresponding to 20% of the amount of diethylene glycol added before the esterification reaction was added so as to match the target composition, and it was stirred and reacted for 15 minutes.

[0078] To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added, and it was continuously supplied to the first polycondensation reaction vessel. Under stirring, at 261 °C and 6.7 kPa for 1 hour, then in the second polycondensation reaction vessel under stirring, at 272 °C and 0.6 kPa for 1 hour, and further in the final polycondensation reaction vessel under stirring, at 275 °C and 0.10 - 0.20 kPa for 1 hour to carry out the polycondensation reaction. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, water-cooled in a cooling bath, and then cut into chips. The number average molecular weight was 19,000. The evaluation results are shown in Table 1. The copolymer polyester resin obtained in this example was evaluated by sheet molding according to the method of 8), and the moldability was good.

[0079] (Example 2) A slurry prepared by adjusting the molar ratio (G / A) of the total glycol component to the dicarboxylic acid component to 2.2, with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG) and diethylene glycol as the glycol components, was continuously supplied to the first esterification reaction vessel in which reactants remained beforehand. Then, under stirring, at a tank internal pressure of 0.15 MPa and 257 °C, the esterification reaction was carried out so that the average residence time was 3 hours. This reaction product was transferred to the second esterification reaction vessel, and the esterification reaction was carried out under stirring at 257 °C with a tank internal pressure of 0.05 MPa so that the average residence time was 1 hour. Then, this esterification reaction product was transferred to the third esterification reaction vessel, and the esterification reaction was carried out under stirring at a tank internal pressure of 0.05 MPa and 257 °C. To the generated oligomer, an amount corresponding to 20% of the amount of diethylene glycol added before the esterification reaction was added to match the target composition, and it was stirred and reacted for 15 minutes.

[0080] To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added, and it was continuously supplied to the first polycondensation reaction vessel. Under stirring, at 261 °C and 6.7 kPa for 1 hour, then in the second polycondensation reaction vessel under stirring, at 272 °C and 0.6 kPa for 1 hour, and further in the final polycondensation reaction vessel under stirring, at 275 °C and 0.10 - 0.20 kPa for 1 hour to conduct a polycondensation reaction. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, water-cooled in a cooling bath, and then cut into chips. The number average molecular weight was 20,000.

[0081] The evaluation results are shown in Table 1. The copolymer polyester resin obtained in this example was evaluated by sheet molding according to the method of 8), and the moldability was good.

[0082] (Examples 3 - 5) Reacted in the same manner as in Example 2 to obtain a copolymer polyester resin. The evaluation results are shown in Table 1. The copolymer polyester resin obtained in this example was evaluated by sheet molding according to the method of 8), and the moldability was good.

[0083] (Example 6) To the first esterification reaction vessel in which reactants remained in advance, a slurry prepared by adjusting the molar ratio (G / A) of the total glycol components to the dicarboxylic acid component to 1.6 with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG) and diethylene glycol (DEG) as the glycol components was continuously supplied. Then, under stirring, under the conditions of a tank internal pressure of 0.15 MPa and 257 °C, an esterification reaction was carried out so that the average residence time was 3 hours. This reaction product was transferred to the second esterification reaction vessel, and an esterification reaction was carried out under stirring at 257 °C under the condition of a tank internal pressure of 0.05 MPa so that the average residence time was 1 hour. Then, this esterification reaction product was transferred to the third esterification reaction vessel, and an esterification reaction was carried out under stirring at a tank internal pressure of 0.05 MPa and 257 °C. To the generated oligomer, an amount corresponding to 20% of the amount of diethylene glycol added before the esterification reaction was added so as to match the target composition, and the mixture was stirred and reacted for 15 minutes.

[0084] To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added, and the mixture was continuously supplied to a first polycondensation reaction vessel. Under stirring, the reaction was carried out at 261 °C and 6.7 kPa for 1 hour, then in a second polycondensation reaction vessel under stirring at 272 °C and 0.6 kPa for 1 hour, and further in a final polycondensation reaction vessel under stirring at 275 °C and 0.10 - 0.20 kPa for 1 hour to carry out a polycondensation reaction. After the polycondensation reaction, the polymer was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, cooled with water in a cooling bath, and then cut into chips. A copolymer polyester resin having a number average molecular weight of 20,000 and a polymer carboxyl end group concentration of 24 eq / t was obtained. The evaluation results are shown in Table 1. When the copolymer polyester resin obtained in this example was evaluated by sheet molding by the method of 8), the moldability was good, but the resin color was 4.5 and the thermal stability evaluation was 0.10, showing a slight decrease.

[0085] (Example 7) Into an esterification reaction vessel with a volume of 10 L equipped with a stirrer and a distillation condenser, 2414 parts by mass of terephthalic acid (TPA), ethylene glycol (EG) and diethylene glycol (DEG) were charged, and an ethylene glycol solution of antimony trioxide and cobalt acetate was added as a catalyst so that the copolymer polyester resin contained 250 ppm of antimony metal and 10 ppm of cobalt metal. Thereafter, the temperature inside the reaction system was gradually increased to 240 °C, and the esterification reaction was carried out at a pressure of 0.25 MPa for 180 minutes. After confirming that no more distillate water came out from the reaction system, the pressure inside the reaction system was returned to normal pressure. To the produced oligomer, diethylene glycol was added in an amount corresponding to 20% of the amount added before the esterification reaction and diethylene glycol was added so as to match the target composition, and the mixture was stirred and reacted for about 15 minutes. A trimethyl phosphate ethylene glycol solution was added to the produced copolyester so that the residual phosphorus atoms were contained at 50 ppm.

[0086] The obtained oligomer was transferred to a polycondensation reaction tank, the pressure was reduced while gradually increasing the temperature, and finally the temperature was 270 °C and the pressure was 0.2 hPa. The reaction was carried out until the torque value of the stirring blade corresponding to the intrinsic viscosity reached the desired value, and the polycondensation reaction was terminated. The obtained molten copolyester resin was drawn out in a strand form from the extraction port at the bottom of the polycondensation tank, cooled in a water tank, and then cut into chips. The number average molecular weight was 19,000. Heat treatment was carried out in the same manner as in Example 1. The results are shown in Table 1. The copolyester resin obtained in this example was evaluated by sheet molding by the method of 8), and the moldability was good. The haze and thermal stability of the stepped molding plate tended to be slightly inferior, but there was no problem.

[0087] (Examples 8, 9) The reaction was carried out in the same manner as in Example 2 to obtain a copolyester resin. The evaluation results are shown in Table 1. The copolyester resin obtained in this example was evaluated by sheet molding by the method of 8), and the moldability was good. The haze of the stepped molding plate tended to be slightly inferior, but there was no problem.

[0088] (Example 10) A slurry prepared by adjusting the molar ratio (G / A) of the total glycol component to the dicarboxylic acid component to 2.2, with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG) and diethylene glycol (DEG) as the glycol components, was continuously supplied to a first esterification reactor in which reactants remained beforehand. Subsequently, under stirring, an esterification reaction was carried out at a tank internal pressure of 0.15 MPa and 257 °C such that the average residence time was 4 hours. This reaction product was transferred to a second esterification reactor, and an esterification reaction was carried out at a tank internal pressure of 0.05 MPa under stirring at 257 °C such that the average residence time was 2 hours. Next, this esterification reaction product was transferred to a third esterification reactor, and an esterification reaction was carried out under stirring at a tank internal pressure of 0.05 MPa and 257 °C. An amount corresponding to 20% of the amount of diethylene glycol added before the esterification reaction was added to the produced oligomer so as to match the target composition, and it was stirred and reacted for 15 minutes.

[0089] To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added and continuously supplied to a first polycondensation reactor. Under stirring, at 261 °C and 6.7 kPa for 1 hour, then in a second polycondensation reactor under stirring, at 272 °C and 0.6 kPa for 1 hour, and further in a final polycondensation reactor under stirring, at 275 °C and 0.10 - 0.20 kPa for 1 hour, a polycondensation reaction was carried out. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, cooled with water in a cooling bath, and then cut into chips. The number average molecular weight was 19,000. The evaluation results are shown in Table 1. The copolymer polyester resin obtained in this example was evaluated by sheet molding by the method of 8), and the moldability was good.

[0090] (Example 11) A slurry prepared by adjusting the molar ratio (G / A) of the total glycol component to the dicarboxylic acid component to 2.2, with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG) and diethylene glycol (DEG) as the glycol components, was continuously fed into a first esterification reactor in which reactants remained beforehand. Subsequently, under stirring, an esterification reaction was carried out at a reactor internal pressure of 0.15 MPa and 257 °C such that the average residence time was 2.5 hours. This reaction product was transferred to a second esterification reactor, and an esterification reaction was carried out at a reactor internal pressure of 0.05 MPa under stirring at 257 °C such that the average residence time was 0.8 hours. Subsequently, this esterification reaction product was transferred to a third esterification reactor, and an esterification reaction was carried out under stirring at a reactor internal pressure of 0.05 MPa and 257 °C. An amount corresponding to 20% of the amount of diethylene glycol added before the esterification reaction was added to the produced oligomer so as to match the target composition, and it was stirred and reacted for 15 minutes.

[0091] A certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added to this esterification reaction product, and it was continuously fed into a first polycondensation reactor. Under stirring, a polycondensation reaction was carried out at 261 °C and 6.7 kPa for 1 hour, then in a second polycondensation reactor under stirring at 272 °C and 0.6 kPa for 1 hour, and further in a final polycondensation reactor under stirring at 275 °C and 0.10 - 0.20 kPa for 1 hour. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, water-cooled in a cooling bath, and then cut into chips. The number average molecular weight was 19,000. The evaluation results are shown in Table 1. The copolymer polyester resin obtained in this example was evaluated by sheet molding by the method of 8), and the moldability was good. Although the color tone, haze of the stepped molding plate, and thermal stability tended to be slightly inferior, there were no problems.

[0092] (Comparative Example 1) To a first esterification reactor with residual reactants, a slurry prepared by adjusting the molar ratio (G / A) of the total glycol component to the dicarboxylic acid component to 2.0 with high-purity terephthalic acid (TPA) as the dicarboxylic acid component and ethylene glycol (EG) as the glycol component was continuously supplied. Subsequently, under stirring, an esterification reaction was carried out at a tank pressure of 0.17 MPa and 255 °C so that the average residence time was 3 hours. This reaction product was transferred to a second esterification reactor, and an esterification reaction was carried out at a tank pressure of 0.05 MPa under stirring at 261 °C so that the average residence time was 1 hour. Next, this esterification reaction product was transferred to a third esterification reactor, and an esterification reaction was carried out under stirring at a tank pressure of 0.05 MPa and 266 - 267 °C. To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added and continuously supplied to the first polycondensation reactor. Under stirring, at 268 °C and 4.7 kPa for 1 hour, then in the second polycondensation reactor under stirring at 270 °C and 0.57 kPa for 1 hour, and further in the final polycondensation reactor under stirring at 274 °C and 0.17 kPa for 1 hour, a polycondensation reaction was carried out. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand form from the nozzle of the die, water-cooled in a cooling bath, and then cut into chips. The number average molecular weight was 19,000. The evaluation results are shown in Table 1. The measurement of the amount of cyclic oligomers was not carried out.

[0093] (Comparative Example 2) Using the same synthesis method as in Example 2, the amount of DEG was adjusted to 5 mol% for synthesis and evaluation was carried out. When the amount of DEG was small, it was inferior in any evaluation. The evaluation results are shown in Table 1.

[0094] (Comparative Example 3) Using the same synthesis method as in Example 2, the amount of DEG was adjusted to 34 mol% for synthesis and evaluation was carried out. When the amount of DEG was large, the sheet film-forming evaluation and thermal stability were inferior. The evaluation results are shown in Table 1.

[0095] (Comparative Example 4) Using the same synthesis method as in Example 2, the amount of DEG was adjusted to 19 mol% and the amount of TEG was adjusted to 2.5 mol% for synthesis, and evaluation was carried out. When there was a large amount of TEG, it was inferior in all evaluations. The evaluation results are shown in Table 1.

[0096] (Comparative Example 5) A slurry prepared by adjusting the molar ratio (G / A) of the total glycol component to the dicarboxylic acid component to 2.2, with high-purity terephthalic acid (TPA) as the dicarboxylic acid component, ethylene glycol (EG) and diethylene glycol as the glycol components, was continuously supplied to the first esterification reaction vessel in which reactants remained in advance. Next, under stirring, an esterification reaction was carried out at a tank internal pressure of 0.15 MPa and 257 °C so that the average residence time was 3 hours. This reaction product was transferred to the second esterification reaction vessel, and an esterification reaction was carried out at a tank internal pressure of 0.05 MPa under stirring at 257 °C so that the average residence time was 1 hour. Next, this esterification reaction product was transferred to the third esterification reaction vessel, and an esterification reaction was carried out under stirring at a tank internal pressure of 0.05 MPa and 257 °C.

[0097] To this esterification reaction product, a certain amount of an ethylene glycol solution of an aluminum compound (basic aluminum acetate) and an ethylene glycol solution of a phosphorus compound (Irganox 1222: the compound of the aforementioned chemical formula (4)) were added and continuously supplied to the first polycondensation reaction vessel. Under stirring, at 261 °C and 6.7 kPa for 1 hour, then in the second polycondensation reaction vessel under stirring, at 272 °C and 0.6 kPa for 1 hour, and further in the final polycondensation reaction vessel under stirring, at 275 °C and 0.10 - 0.20 kPa for 1 hour, a polycondensation reaction was carried out. After the polycondensation reaction, it was passed through a polymer filter, and the molten copolymer polyester was extruded in a strand shape from the nozzle of the die, cooled with water in a cooling bath, and cut into chips. The number average molecular weight was 20,000. T2D1TE1 and T2D2 increased, and it was inferior in the sheet film formation evaluation and haze evaluation. The evaluation results are shown in Table 1.

[0098]

Table 1

Industrial Applicability

[0099] The copolymerized polyester resin of the present invention is excellent in transparency, color tone, and moldability, and there is little occurrence of soiling of the molding die and adhesion of foreign substances to the molded product or film. Therefore, it is excellent in economic efficiency and can advantageously provide a molded body with high commercial value, which greatly contributes to the industrial world.

Claims

1. A copolymerized polyester resin comprising dicarboxylic acid and diol as constituent components, wherein the main component of the dicarboxylic acid component is terephthalic acid, the main component of the diol component is ethylene glycol, and when all the diol components are 100 mol%, the content of diethylene glycol is 7 to 30 mol% and the content of triethylene glycol is 0.05 to 2 mol%, the content of the cyclic dimer composed of terephthalic acid and diethylene glycol is 7000 ppm or less, and the content of the cyclic dimer composed of terephthalic acid, diethylene glycol and triethylene glycol is 200 ppm or less. A copolymerized polyester resin characterized by the above.

2. The copolymerized polyester resin according to Claim 1, characterized in that the color b value is -5.0 to 10.

0.

3. The carboxyl terminal group concentration (AV) is 8 to 25 eq / t, the copolymerized polyester resin contains aluminum atoms and phosphorus atoms, the content of aluminum atoms in the copolymerized polyester resin is 15 to 40 ppm, and the molar ratio of phosphorus atoms to aluminum atoms in the copolymerized polyester resin is 1.8 to 2.

6. The copolymerized polyester resin according to Claim 1 or 2, characterized by the above.

4. The copolymerized polyester resin according to any one of Claims 1 to 3, characterized in that the haze value at a thickness of 5 mm of the stepped molded plate obtained by molding the copolymerized polyester resin is 10% or less.

5. A molded article characterized by containing the copolymerized polyester resin according to any one of Claims 1 to 4.

6. A heat-shrinkable film characterized by containing the copolymerized polyester resin according to any one of Claims 1 to 4.

7. A fiber characterized by containing the copolymerized polyester resin according to any one of Claims 1 to 4.

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