JP2006225621A - Method for producing polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing a polyester resin composed of dicarboxylic acid constituent units and diol constituent units in which 5-60 mol% of the diol constituent units is a constituent unit having a cyclic acetal skeleton according to an industrial and advantageous method. <P>SOLUTION: The method for producing the polyester resin composed of the dicarboxylic acid constituent units and the diol constituent units in which at least 5-60 mol% of the dicarboxylic acid constituent units has the cyclic acetal skeleton is provided. The method for producing the polyester resin is characterized as comprising an oligomerization step of carrying out transesterification of an ester (D) having ≤30 μequivalents/g acid value and represented by a specific chemical formula and a diol (A) having the cyclic acetal skeleton in the presence of a titanium compound (E) and a polymerization step of polymerizing the oligomer to increase the molecular weight. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a polyester resin composed of a dicarboxylic acid structural unit and a diol structural unit having a cyclic acetal skeleton, which is excellent in mechanical properties, particularly impact resistance, and has a small yellowness.

Polyethylene terephthalate (hereinafter sometimes referred to as “PET”) has the characteristics of excellent transparency, mechanical performance, melt stability, solvent resistance, fragrance retention, recyclability, etc., film, sheet, hollow container Widely used. However, since heat resistance is not always good, modification by copolymerization is widely performed.
On the other hand, it is generally known that when a polymer is modified with a compound having a cyclic acetal skeleton, the heat resistance, adhesiveness, flame retardancy, etc. are improved due to the rigid skeleton and acetal bond of the cyclic acetal. The modification of a polyester resin by copolymerizing a compound having a skeleton is disclosed.
For example, PET modified with 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane has a high glass transition point and high heat resistance. It is described that it is excellent in performance (see Patent Document 1). Moreover, the copolymer polyester container excellent in transparency and heat resistance which consist of terephthalic acid, 1, 4- butanediol, and the glycol which has a cyclic acetal frame | skeleton, and its manufacturing method are disclosed (refer patent document 2). Furthermore, a polyester using a diol having a cyclic acetal skeleton is disclosed as a polyester excellent in heat resistance and transparency (see Patent Document 3).

Moreover, as an example using the adhesiveness derived from an acetal bond, a polyester-based adhesive, an adhesive composition or a coating agent using a diol having a cyclic acetal skeleton or a dicarboxylic acid is disclosed (Patent Document 4). ~ 7).
In addition, as polyester using dicarboxylic acid or diol having a cyclic acetal skeleton, for example, polyester shrinkage difference mixed yarn (see Patent Document 8), modified polyester film (see Patent Document 9), biodegradable polyester ( Patent Document 10), electrostatic charge developing toner (see Patent Document 11), flame retardant resin composition (see Patent Document 12), and the like.

By the way, as a method for producing a polyester resin, generally a direct esterification method in which a dicarboxylic acid is converted into an ester with an excessive amount of a diol to form a bishydroxyalkyl ester of the dicarboxylic acid, and this ester is polycondensed under reduced pressure to form a polymer. And a transesterification method in which an ester of a dicarboxylic acid and a monoalcohol and an excess amount of a diol are transesterified to form a bishydroxyalkyl ester of a dicarboxylic acid, and this ester is polycondensed under reduced pressure to form a polymer. Yes. In PET, since terephthalic acid is less expensive than dimethyl terephthalate, the direct esterification method can be said to be an industrially advantageous production method over the transesterification method. In addition, since the direct esterification method does not require a catalyst when producing an ester of a dicarboxylic acid and a diol, there are few impurities such as catalyst residues, and a high-quality polyester resin can be obtained. It can be said that this is an advantageous method for the transesterification method. Furthermore, since the by-product in producing an ester of a dicarboxylic acid and a diol is an alcohol in the transesterification method, it is water in the direct esterification method. It can be said that this is a manufacturing method with less environmental impact. For these reasons, the direct esterification method has become the mainstream in the industrial production of PET.

However, when a polyester resin containing a diol structural unit having a cyclic acetal skeleton is produced by a normal direct esterification method, the cyclic acetal skeleton is decomposed by the carboxyl group present in the reaction system and the generated water. The diol having a skeleton is trifunctional and tetrafunctionalized, and the resulting polyester resin may have a remarkably broad molecular weight distribution or a gel, and the moldability and mechanical performance are the same as produced by the transesterification method. The problem that it was remarkably inferior compared with the polyester resin of a structure arose.
In the above-mentioned patent documents relating to polyester resins containing a diol structural unit having a cyclic acetal skeleton, only Patent Document 8 describes a direct esterification method. However, the production conditions and the opening of the cyclic acetal skeleton by a dicarboxylic acid are described. There is no specific disclosure about the ring.

  On the other hand, in recent years, PET recycling, particularly chemical recycling, has attracted attention, and many chemical recycling methods have been proposed (see Patent Documents 13 to 15). The production method using bis (β-hydroxyethyl) terephthalate (hereinafter sometimes abbreviated as “BHET”) recovered from PET by chemical recycling is a production method with a low environmental load. Not only is it industrially advantageous. Furthermore, since BHET has substantially no acid terminal derived from dicarboxylic acid, it is suitable as a raw material for polyesters containing a diol constituent unit having a cyclic acetal skeleton. However, any of the publications mentioned above discloses a method for producing a polyester containing a diol structural unit having a cyclic acetal skeleton using a bishydroxyalkyl ester of a dicarboxylic acid obtained by depolymerizing a polyester resin as a raw material. It has not been.

Regarding the production of a polyester resin containing a diol structural unit having a cyclic acetal skeleton, we esterify a dicarboxylic acid with a diol having no cyclic acetal skeleton to obtain a bishydroxyalkyl ester of the dicarboxylic acid or a polymer thereof, The present inventors have found a method in which a part is transesterified with a diol having a cyclic acetal skeleton and then subjected to a polycondensation reaction. Furthermore, in this method, it is important to control the concentration of the carboxyl group present in the reaction system and the amount of water during the transesterification reaction between the bishydroxyalkyl ester of dicarboxylic acid or a polymer thereof and a diol having a cyclic acetal skeleton. By controlling these, the degradation of the cyclic acetal skeleton and the trifunctional and tetrafunctionalization of the diol having the cyclic acetal skeleton can be suppressed, thereby causing the gelation of the polyester resin and the increase in the molecular weight distribution. However, the inventors have found that a polyester resin can be produced stably and applied for a patent (see Patent Document 16). In addition, as a method for producing a polyester resin containing a diol structural unit having a cyclic acetal skeleton, a method using BHET having a low environmental load as a raw material was found and a patent application was filed (see Patent Document 16). However, there is no description about the blockage of the piping at the time of production when the diol having a cyclic acetal skeleton has sublimability. In addition, the mechanical properties and yellowness of the polyester resin containing a diol structural unit having a cyclic acetal skeleton produced by this method are not described.
US Pat. No. 2,945,008 Japanese Patent No. 2971942 Japanese Patent No. 1979830 Japanese Patent No. 1843892 Japanese Patent No. 1855226 Japanese Patent No. 1902128 JP-A-4-88078 JP-A-3-130425 JP-A-8-104742 Japanese Patent Laid-Open No. 9-40762 Japanese Patent No. 1652382 JP 2000-344939 A JP 2002-60543 A JP 2002-60369 A JP 2002-167469 A JP 2004-137477 A

  An object of the present invention is to industrially favor a polyester resin comprising a dicarboxylic acid structural unit and a diol structural unit, wherein 5 to 60 mol% of the diol structural unit is a structural unit having a cyclic acetal skeleton. It is providing the method of manufacturing stably with a simple manufacturing method. Another object of the present invention is to provide a method for stably producing the polyester resin by an industrially advantageous production method, which has excellent mechanical properties, particularly impact resistance, and low yellowness.

As a result of intensive studies, the inventors of the present invention have produced an acid value in the production of a polyester resin comprising a dicarboxylic acid structural unit and a diol structural unit, in which 5 to 60 mol% of the diol structural unit is a structural unit having a cyclic acetal skeleton. A bishydroxyalkyl ester of dicarboxylic acid and / or a polymer thereof having a predetermined amount or less and a diol (A) having a cyclic acetal skeleton are transesterified in the presence of a titanium compound (E) to produce an oligomer. The oligomerization step and the method comprising a high molecular weight step for increasing the molecular weight of the oligomer, thereby suppressing the decomposition of the cyclic acetal skeleton at the time of production, the molecular weight distribution of the polyester resin is significantly increased, The polyester resin does not gel, and during polycondensation, the diol (A) sublimates due to sublimation. Stable and found that the polyester resin is obtained without you, and have completed the present invention. In addition, the present inventors perform the oligomerization step in the presence of a predetermined amount of the phosphorus compound (F), or the phosphorus compound (F) and the germanium compound (G), so that the mechanical properties of the polyester resin, particularly the resistance The inventors have found that the impact property is remarkably improved and the yellowness is remarkably reduced, and the present invention has been completed.
That is, the present invention is a method for producing a polyester resin comprising a dicarboxylic acid structural unit and a diol structural unit, wherein at least 5 to 60 mol% of the diol structural unit is a diol structural unit having a cyclic acetal skeleton, Oligomerization for producing an oligomer by transesterifying the ester (D) represented by the formula (1) which is 30 μeq / g or less and the diol (A) having a cyclic acetal skeleton in the presence of the titanium compound (E) The present invention relates to a method for producing a polyester resin, comprising a step and a step of increasing the molecular weight of the oligomer.

（式中、Ｒ^１、Ｒ^２、及びＲ^３はそれぞれ独立して、炭素数が１〜１０の脂肪族炭化水素基、炭素数が３〜１０の脂環式炭化水素基、及び炭素数が６〜１０の芳香族炭化水素基からなる群から選ばれる炭化水素基を表す。ｎは１以上２００以下である。）

(In the formula, R ¹ , R ² , and R ³ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a carbon number. Represents a hydrocarbon group selected from the group consisting of 6 to 10 aromatic hydrocarbon groups, n is 1 or more and 200 or less.)

  According to the present invention, it is composed of a dicarboxylic acid structural unit and a diol structural unit having a cyclic acetal skeleton, which is superior in mechanical properties, particularly impact resistance, and more industrially than a conventional transesterification method in producing a polyester resin having a small yellowness. This is advantageous and enables stable production by a production method with a low environmental load, and the industrial significance of the present invention is great.

The production method of the present invention will be described in detail below.
In the production method of the present invention, an ester (D) represented by the formula (1) having an acid value of 30 μeq / g or less and a diol (A) having a cyclic acetal skeleton are esterified in the presence of a titanium compound (E). The present invention relates to a method for producing a polyester resin comprising an oligomerization step for producing an oligomer by exchange reaction, and a high molecular weight step for increasing the molecular weight of the oligomer. In formula (1), R ¹ , R ² , and R ³ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and carbon. This represents a hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups having 6 to 10 numbers. n is 1 or more and 200 or less. When n is 2 or more, the plurality of R ¹ and R ² may be the same or different. The manufacturing method of this invention can use the conventionally well-known manufacturing apparatus used for manufacture of a polyester resin as it is.
The acid value of the ester (D) is 30 μeq / g or less, preferably 1 to 30 μeq / g. When the acid value of the ester (D) exceeds 30 μeq / g, the diol (A) having a cyclic acetal skeleton is decomposed by an acid in the oligomerization step and trifunctional and tetrafunctionalized, which is not preferable. The ester (D) may be a monomer or a polymer as long as it is 30 μeq / g or less, and the average degree of polymerization of the ester (D) is preferably 1 or more and less than 200. The average degree of polymerization in the present invention is a value obtained by dividing the number average molecular weight obtained from gel permeation chromatography by the molecular weight of the repeating unit of ester (D).
The ester (D) used in the present invention is a bishydroxyalkyl ester of dicarboxylic acid and / or a polymer thereof, preferably a bishydroxyalkyl ester of aromatic dicarboxylic acid and / or a polymer thereof, It is preferably a bishydroxyalkyl ester of at least one dicarboxylic acid selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid and / or a polymer thereof.
Although there is no restriction | limiting in particular in the method of manufacturing ester (D), For example, the following manufacturing methods (1) thru | or manufacturing methods (3) are mentioned.

  In the production method (1) of the ester (D), the dicarboxylic acid (B) and the diol (C) having no cyclic acetal skeleton are esterified, and then subjected to a polycondensation reaction, whereby the average degree of polymerization is 15 or more and 200. The following is a method for producing ester (D1).

  Although it does not restrict | limit especially as dicarboxylic acid (B) which can be used by the manufacturing method (1) of ester (D), Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, decanedicarboxylic acid, norbornane dicarboxylic acid, tricyclodecanedicarboxylic acid, pentacyclododecanedicarboxylic acid; terephthalic acid, isophthalic acid, phthalic acid, 2-methylterephthalic acid, 1 And aromatic dicarboxylic acids such as 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetralindicarboxylic acid. Aromatic dicarboxylic acids are preferred from the viewpoint of mechanical performance and heat resistance of the polyester resin of the present invention, and terephthalic acid, 2,6-naphthalenedicarboxylic acid, and isophthalic acid are particularly preferred. Among these, terephthalic acid is most preferable from the viewpoint of economy. The illustrated dicarboxylic acids can be used alone or in combination. Furthermore, monocarboxylic acids such as benzoic acid, propionic acid and butyric acid can be used within a range not impairing the object of the present invention.

The diol (C) having no cyclic acetal skeleton that can be used in the production method (1) of the ester (D) is not particularly limited, but ethylene glycol, trimethylene glycol, 1,4-butanediol, 1, Aliphatic diols such as 5-pentanediol, 1,6-hexanediol, diethylene glycol, propylene glycol, and neopentyl glycol; polyether diols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; 1,3-cyclohexanedimethanol 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalene diethanol, 1,3-decahydronaphthalene diethanol, 1,4-decahydronaphthalene diethanol, 1,5-decahydronaphthalene diethanol Alicyclic diols such as 1,6-decahydronaphthalene diethanol, 2,7-decahydronaphthalene diethanol, tetralin dimethanol, norbornane dimethanol, tricyclodecane dimethanol, pentacyclododecane dimethanol; Bisphenols such as 4 ′-(1-methylethylidene) bisphenol, methylene bisphenol (bisphenol F), 4,4′-cyclohexylidene bisphenol (bisphenol Z), 4,4′-sulfonylbisphenol (bisphenol S); Alkylene oxide adducts; aromatic dihydroxy such as hydroquinone, resorcin, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylbenzophenone Compound, alkylene oxide adducts of and the aromatic dihydroxy compound and the like. Ethylene glycol is particularly preferred from the standpoints of mechanical performance and economy of the polyester resin of the present invention. The exemplified diols can be used alone or in combination.
Furthermore, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and trihydric or higher polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used within the range not impairing the object of the present invention.

  The production method (1) of the ester (D) can be carried out without any change from the esterification step and the polycondensation step in the conventional production method by direct esterification of a polyester resin. That is, the number of diol (C) molecules having no cyclic acetal skeleton is preferably 1.01 to 10 times, more preferably 1.1 to 5 times, still more preferably 1 times the number of dicarboxylic acid (B) molecules. The dicarboxylic acid (B) and the diol (C) are charged so as to be 15 to 2 times. Thereby, undesirable side reactions such as dehydration etherification of the diol (C) can be suppressed.

  The temperature and pressure of the esterification reaction can be carried out without any change from the esterification step in the conventional method for producing a polyester resin by direct esterification, and the temperature is not particularly limited but is preferably 80 to 270 ° C., more preferably Is 100 to 260 ° C, more preferably 150 to 250 ° C, and the pressure is not particularly limited, but is preferably 10 kPa to 500 kPa. The esterification reaction is carried out while extracting the generated water out of the reaction system until the ester conversion calculated from the amount of water extracted is preferably 90% or more, more preferably 92% or more, and still more preferably 95% or more. . The esterification reaction is preferably carried out without a catalyst in terms of the transparency and yellowness of the resin, but the number of metal atoms in the catalyst is 0.0001 to 5% of the number of dicarboxylic acid (B) molecules. A catalyst may be used. A conventionally known catalyst can be used and is not particularly limited. For example, zinc, lead, cerium, cadmium, manganese, cobalt, lithium, sodium, potassium, calcium, nickel, magnesium, vanadium, aluminum, Metal compounds such as titanium, germanium, antimony, tin (for example, fatty acid salts, carbonates, phosphates, hydroxides, chlorides, oxides, alkoxides); metal magnesium and the like. These can be used alone or in combination. In the esterification reaction, conventionally known etherification inhibitors and heat stabilizers can also be used. Examples of the etherification inhibitor include amine compounds, and examples of the heat stabilizer include phosphoric acid, phosphorous acid, phosphoric acid ester, and phosphorous acid ester.

  If the acid value of the ester (D1) does not become 30 μeq / g or less only by the esterification reaction, it is necessary to carry out a polycondensation reaction. The temperature and pressure of the polycondensation reaction can be carried out without any change from the polycondensation step in the conventional polyester resin production method, and the temperature is gradually increased, and finally preferably 200 to 300 ° C., and the pressure is gradually increased. The pressure is finally reduced to 300 Pa or less. The polycondensation reaction may be performed without a catalyst, but a catalyst may be used so that the number of metal atoms in the catalyst is 0.0001 to 5% of the number of dicarboxylic acid (B) constituent units. A conventionally known catalyst can be used, and is not particularly limited, and those described above can be used. These can be used alone or in combination. Among them, it is preferable to use a metal compound of aluminum, titanium, germanium, antimony, and tin, and it is particularly preferable to use an alkoxide, oxide, or carboxylate of titanium; an alkoxide of germanium, an oxide, or an oxide of antimony. In the polycondensation reaction, conventionally known heat stabilizers as described above can be used.

  The polycondensation reaction may be performed until the acid value of the ester (D1) becomes 30 μeq / g or less. That is, when the acid value of the ester (D1) becomes 30 μeq / g or less before reaching the final temperature and pressure as described above, the reaction may be terminated at that point. When the ester (D1) has an acid value of 30 μeq / g or less at the end of the esterification reaction, it is not necessary to perform a polycondensation reaction.

  The production method (2) of the ester (D) is obtained by polycondensing a low polymer obtained by esterifying the dicarboxylic acid (B) with a diol (C) having no cyclic acetal skeleton. High polymers (hereinafter referred to as esters (D2 ′)) are depolymerized with a diol (C) having no cyclic acetal skeleton until the average polymerization degree is less than 15 and the melting point is 240 ° C. or less. This is a method for producing an ester (D2). The ester (D2 ′) is used as a precursor of the ester (D2). Even if the ester (D2 ′) is a low polymer prepared by an esterification step in the conventional method for producing a polyester resin as described above, a high weight prepared by performing a polycondensation step after the esterification step. Although it may be a coalescence, it is preferable to prepare only by an esterification step from the viewpoint of reduction of heat history, simplification of process, reduction of energy consumption, and the like. The low polymer is a polymer obtained by an esterification step in the production of a conventional polyester resin. Although there is no particular limitation, the average degree of polymerization is 2 or more and less than 25, and a high polymer is a polycondensation. This is a polymer obtained by the process, and there is no particular limitation, but the average degree of polymerization is 10 or more and less than 200. The average degree of polymerization of the ester (D2 ′) is 2 or more and less than 200, preferably 2 or more and less than 70, and more preferably 2 or more and less than 25. The acid value of the ester (D2 ′) may be 30 μeq / g or more.

  Although it does not restrict | limit especially as dicarboxylic acid (B) which can be used with the manufacturing method (2) of ester (D), and the diol (C) which does not have a cyclic acetal skeleton, The manufacturing method (1) of ester (D) Can be used.

  The depolymerization reaction of the ester (D2 ′) has a value obtained by dividing the number of diol (C) molecules having no cyclic acetal skeleton by the number of dicarboxylic acid structural units in the ester (D2 ′), 1.1 to 10, Preferably, the diol (C) is added so as to be 1.3 to 5, more preferably 1.5 to 3. The conditions for the depolymerization reaction are a temperature of 150 to 250 ° C., preferably 180 to 230 ° C., and a pressure of 50 kPa to 500 kPa, preferably 100 kPa to 300 kPa. When the depolymerization reaction conditions are equal to or lower than the vapor pressure of the diol (C), it is preferable to advance the depolymerization reaction while refluxing the diol (C) without extracting it from the reaction system. By performing the depolymerization under the above conditions, undesirable side reactions such as dehydration etherification of the diol (C) can be suppressed.

  The depolymerization reaction is preferably performed without a catalyst from the viewpoint of the transparency and yellowness of the polyester resin, but the number of metal atoms in the catalyst is 0.0001, which is the number of dicarboxylic acid constituent units in the ester (D2 ′). You may use a catalyst so that it may become -5%. A conventionally known catalyst can be used and is not particularly limited. For example, those exemplified in the production method (1) can be used. Of these, metal carboxylates and oxides of metals such as zinc, lead, cerium, cadmium, manganese, cobalt, lithium, sodium, potassium, calcium, nickel, magnesium, vanadium, aluminum, titanium, germanium, antimony, and tin are preferable. Lead, cerium, cadmium, manganese, cobalt acetate, antimony trioxide, and germanium oxide are particularly preferable. These can be used alone or in combination.

  In the depolymerization of the ester (D2 ′), esterification reaction of the carboxyl group remaining at the terminal occurs simultaneously. Therefore, the acid value of the ester (D2) obtained by depolymerization is usually smaller than the acid value of the ester (D2 ′) before depolymerization. In addition, the acid value of ester (D2 ') can be effectively reduced by distilling off the water produced | generated by esterification at the time of depolymerization. Therefore, this method is preferable because an ester (D2) having an acid value of 30 μeq / g or less, further 20 μeq / g or less, and particularly 10 μeq / g or less can be obtained relatively easily. The melting point of the ester (D2) obtained by depolymerization is usually lower than the melting point of the ester (D2 ′) before depolymerization. Therefore, this method is preferable because an ester (D2) having a melting point of 240 ° C. or lower, further 220 ° C. or lower, particularly 210 ° C. or lower can be obtained relatively easily. Since the melting point of the ester (D2) is in the above range, the reaction temperature in the subsequent oligomerization step can be 240 ° C. or less, and the thermal decomposition of the diol (A) having a cyclic acetal skeleton in the oligomerization step is suppressed. This is preferable because it can be performed. For these reasons, as the ester (D) used in the production method of the present invention, the ester (D2) may be preferable to the ester (D1).

When the value obtained by dividing the number of diol structural units in the depolymerized product by the number of dicarboxylic acid structural units is larger than 3.0, the diol (mainly until the value becomes 3.0 or less after the completion of the depolymerization reaction. C) must be distilled off under a temperature condition of 150 to 250 ° C. and a pressure condition of 0.5 kPa to 100 kPa. When the value is larger than 3.0, dehydration etherification of the diol (C) is likely to occur, and the generated water decomposes the diol (A) having a cyclic acetal skeleton in the subsequent oligomerization step, trifunctional, 4 Functionalization may be caused. In addition, the generated ether may reduce the physical properties of the polyester resin. Even when the value obtained by dividing the number of diol constituent units in the depolymerized product by the number of dicarboxylic acid constituent units is 3.0 or less, the diol (C) is mainly added under the above conditions in order to further reduce the value. Can be distilled off.
The value obtained by dividing the number of diol constituent units of the ester (D2) thus obtained by the number of dicarboxylic acid constituent units is 1.1 to 3.0, preferably 1.1 to 2.0, more preferably 1.1 to 1.7, particularly preferably 1.1 to 1.5. By making the said value into the said range, undesirable side reactions, such as dehydration etherification in a subsequent oligomerization process, can be suppressed.

The production method (3) of the ester (D) is a diol having no cyclic acetal skeleton in the same manner as the production method (2) except that a preformed polyester resin (D3 ′) is used instead of the ester (D2 ′). In (C), the depolymerization is carried out until the average degree of polymerization is less than 15 and the melting point is 240 ° C. or less to produce the ester (D3).
Polyester resin (D3 ′) in production method (3) is not particularly limited, but polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, isophthalic acid-modified polyethylene terephthalate, 1,4-cyclohexanedimethanol-modified polyethylene terephthalate, 3,9 -Bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane modified polyethylene terephthalate and 5-methylol-5-ethyl-2- (1, Examples thereof include 1-dimethyl-2-hydroxyethyl) -1,3-dioxane-modified polyethylene terephthalate.
The acid value of the ester (D3) may be smaller than the acid value of the polyester resin (D3 ′) for the same reason as described above, and is relatively easily 30 μeq / g or less, more preferably 20 μeq / g or less, 10 μequivalent / g or less. For this reason, decomposition | disassembly of diol (A) which has a cyclic acetal frame | skeleton in a subsequent oligomerization process, trifunctional, and tetrafunctionalization can be suppressed, and it is preferable. The melting point of the ester (D3) is 240 ° C. or lower, further 220 ° C. or lower, particularly 210 ° C. or lower for the same reason as described above. For this reason, since the reaction temperature of a subsequent oligomerization process can be 240 degrees C or less and the thermal decomposition of diol (A) in an oligomerization process can be suppressed, it is preferable. The depolymerization may be performed using the catalyst described in the production method (2) for the ester (D).
The value obtained by dividing the number of diol constituent units in the ester (D3) by the number of dicarboxylic acid constituent units is 1.1 to 3.0, preferably 1.1 to 2.0, more preferably 1.1 to 1.7. Particularly preferred is 1.1 to 1.5. By making the said value into the said range, undesirable side reactions, such as dehydration etherification of the diol in a subsequent oligomerization process, can be suppressed.

  In the production methods (1) to (3), orthoformate triester and / or carbonic acid diester may be added. Thereby, the acid value of ester (D) may be able to be reduced effectively. Examples of the orthoformate triester include trimethyl orthoformate and triethyl orthoformate, and examples of the carbonic acid diester include dimethyl carbonate and diethyl carbonate.

  As the ester (D), bis (β-hydroxyethyl) terephthalate (ester (D4)) may be used. The acid value of the ester (D4) is 30 μeq / g or less, preferably 20 μeq / g or less, more preferably 10 μeq / g or less. The method for preparing the ester (D4) is not particularly limited, but it is preferable to prepare it by chemical recycling of PET from the viewpoint of reducing the environmental load.

  As the ester (D), one produced by the production method (1) (ester (D1)), one produced by the production method (2) (ester (D2)), one produced by the production method (3) (ester ( One or more esters selected from the group consisting of D3)) and esters (D4) can be used in admixture at any ratio.

  In the oligomerization step in the method for producing a polyester resin of the present invention, the ester (D) and the diol (A) having a cyclic acetal skeleton are reacted in the presence of the titanium compound (E), and mainly the ester (D) and This is a step of producing an oligomer comprising a dicarboxylic acid structural unit, a diol structural unit having a cyclic acetal skeleton, and a diol structural unit not having a cyclic acetal skeleton by an ester exchange reaction with the diol (A).

  The diol (A) having a cyclic acetal skeleton used in the present invention is not particularly limited, and examples thereof include compounds represented by the formula (2) or (3).

In Formula (2), R ^{4 to} R ⁵ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and 6 to 6 carbon atoms. A divalent hydrocarbon group selected from the group consisting of 10 aromatic hydrocarbon groups, preferably a methylene group, an ethylene group, a propylene group, a butylene group or a structural isomer thereof such as an isopropylene group or an isobutylene group. To express. In Formula (3), R ⁶ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms. It represents a divalent hydrocarbon group selected from the group consisting of a methylene group, an ethylene group, a propylene group, a butylene group, or a structural isomer thereof such as an isopropylene group or an isobutylene group. R ⁷ is 1 selected from the group consisting of an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms. A valent hydrocarbon group, preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a structural isomer thereof such as an isopropyl group or an isobutyl group.
Specific examples thereof include 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 5-methylol-5-ethyl-2. Examples include-(1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane.

  The amount of the diol (A) having a cyclic acetal skeleton in the oligomerization step is 0.05 to 0.60, obtained by dividing the number of diols (A) by the number of dicarboxylic acid structural units in the ester (D). Do as follows. By making the said value into the said range, 5-60 mol% in a diol structural unit can obtain the polyester resin which is a diol structural unit which has a cyclic acetal skeleton, transparency of this polyester resin, mechanical performance, Various physical properties such as heat resistance are excellent. From the viewpoint of various physical properties, the charged amount of the diol (A) is preferably a value obtained by dividing the number of diols (A) by the number of dicarboxylic acid constituent units in the ester (D), preferably 0.10 or more and 0.55 or less. Preferably it is carried out so that it becomes 0.20 or more and 0.45 or less.

  In the production method of the present invention, when an oligomer is produced from an ester (D) and a diol (A) having a cyclic acetal skeleton, the acid value of the ester (D) in the oligomerization step is 30 μeq / g or less. Decomposition, trifunctional and tetrafunctionalization of the diol (A) having a cyclic acetal skeleton by a free carboxyl group can be prevented. As a result, the polyester resin can be stably produced without causing gelation and significant increase in molecular weight distribution. For this reason, the mechanical performance of the obtained polyester resin is excellent, and the moldability and secondary processability are also good. From these facts, the acid value of the ester (D) is preferably 20 μeq / g or less, more preferably 10 μeq / g or less.

  In the production method of the present invention, it is important to perform the oligomerization step in the presence of the titanium compound (E). Since the titanium compound (E) serves as a transesterification catalyst in the oligomerization step, the transesterification reaction between the ester (D) and the diol (A) having a cyclic acetal skeleton can be performed quickly.

  The titanium compound (E) used in the production method of the present invention is not particularly limited, but tetra-n-butyl titanate, tetra-n-butyl titanate dimer, tetra-n-butyl titanate trimer, tetra-n- Orthotitanate such as butyl titanate tetramer, tetra-t-butyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate; titanium such as titanium acetate and titanium oxalate Carboxylate; titanate of alkali metal such as potassium titanate and sodium titanate; titanium halide such as titanium chloride, titanium bromide and titanium fluoride; titanium oxide; titanium titanate-aluminum hydroxide mixture; titanium chloride chloride Aluminum mixture; hexafluoride potassium titanium hexafluoride titanium manganese hexafluoride of titanium fluoride such as titanium ammonium salt; titanium acetylacetonate; potassium titanium oxalate; oxalate Sodium like can be exemplified. Of these, orthotitanate is preferable, and tetra-n-propyl titanate, tetra-i-propyl titanate, and tetra-n-butyl titanate are particularly preferable. These can be used alone or in combination. Addition of the titanium compound (E) may be performed at any time before the start of the oligomerization step, at the start of the production of the ester (D), during the production, or after the production (at the start of the oligomerization step). When an ortho titanic acid ester is used as the titanium compound (E), it is preferably added after completion of the production of the ester (D) in order to prevent deactivation due to moisture.

  In the oligomerization step, the number of titanium atoms is preferably 0.0001% to 5%, more preferably 0.0005% to 0.5%, and still more preferably the number of dicarboxylic acid structural units in the ester (D). Is carried out in the presence of an amount of titanium compound E that is 0.001% or more and 0.1% or less. When the ratio is within the predetermined range, the ester exchange reaction between the ester (D) and the diol (A) having a cyclic acetal skeleton can be quickly performed as described above. Thereby, an oligomerization process can be shortened and side reactions, such as decomposition | disassembly of diol (A) at this process, coloring of a polyester resin, etc. can be prevented. Even if the diol (A) having a cyclic acetal skeleton has sublimability, the diol (A) can be quantitatively incorporated into the oligomer chain, so that the unreacted diol (A) is polycondensed. Occasionally, there is no problem in production such as sublimation and clogging of the decompression pipe, and quality problems such that a predetermined amount of the diol (A) structural unit is not incorporated in the polymer chain.

  The temperature of the reaction system in the oligomerization step is preferably 80 to 240 ° C, more preferably 100 to 235 ° C, and particularly preferably 150 to 230 ° C. By performing the oligomerization step under the above conditions, undesirable side reactions such as decomposition, trifunctional, and tetrafunctionalization of the diol (A) having a cyclic acetal skeleton can be suppressed. The pressure of the reaction system in the oligomerization step is preferably 10 kPa to 500 kPa, more preferably 10 kPa to 100 kPa. By carrying out the oligomerization step under the above-mentioned conditions, the diol (C) having no cyclic acetal skeleton formed by the transesterification reaction between the ester (D) and the diol (A) having a cyclic acetal skeleton is quickly retained outside the reaction system. This is preferable because the transesterification reaction between the ester (D) and the diol (A) is promoted. In addition, this can suppress undesirable side reactions such as dehydration etherification of the diol (C), and can quickly remove water generated by dehydration etherification.

  In the oligomerization step, the diol (C) having no cyclic acetal skeleton is distilled out of the reaction system, preferably the sum of the number of structural units of the diol (A) and the number of structural units of the diol (C) is an oligomer. It is good to carry out until it becomes 1.05-2.0 times of the number of the dicarboxylic acid structural units in it, More preferably, it is 1.05-1.5 times, Most preferably, it is 1.05-1.2 times. Distilling diol (C) out of the reaction system within the above range is preferable because the ester exchange reaction between ester (D) and diol (A) is promoted. Further, it is preferable to distill diol (C) out of the reaction system in the above range because undesirable side reactions such as dehydration etherification of diol (C) can be suppressed.

  The oligomerization step may be performed until the reaction rate of the transesterification reaction between the ester (D) and the diol (A) is 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more. Judgment of the end of the oligomerization step is preferable because it is easy to carry out from the amount of diol (C) distilled off. The oligomerization step is preferably performed within 5 hours, more preferably within 3 hours, particularly within 2 hours. By completing the reaction time, decomposition of the diol (A) having a cyclic acetal skeleton, trifunctional, and tetrafunctional Undesirable side reactions such as crystallization can be suppressed.

  The oligomerization step of the present invention may be performed in the presence of a phosphorus compound (F) in addition to the titanium compound (E). In the phosphorus compound (F), the number of phosphorus atoms is 0.0001% to 5%, preferably 0.001% to 0.5%, more preferably the number of dicarboxylic acid structural units in the ester (D). It is used so that it may become 0.005% or more and 0.1% or less. When the ratio is in the predetermined range, it is possible to suppress coloring of the specific polyester resin when the titanium compound (E) is used as a catalyst.

  The phosphorus compound (F) is not particularly limited, and examples thereof include phosphoric acid; phosphorous acid; methyl phosphate, ethyl phosphate, butyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, Phosphate esters such as diphenyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate; methyl phosphite, ethyl phosphite, butyl phosphite, phenyl phosphite, dimethyl phosphite And phosphite esters such as diethyl phosphite, dibutyl phosphite, diphenyl phosphite, trimethyl phosphite, triethyl phosphite, tributyl phosphite and triphenyl phosphite. Of these, phosphate esters are preferable, and trimethyl phosphate is particularly preferable. These can be used alone or in combination. The phosphorus atom may be present at a predetermined ratio to the number of dicarboxylic acids of the ester (D) at the start of the oligomerization step, and a phosphorus compound is used as a heat stabilizer during the production of the ester (D). When phosphorus atoms are already present at a predetermined ratio at the start of the process, the phosphorus compound (F) may not be newly added at the start of the oligomerization process.

  When the oligomerization step is performed in the presence of the phosphorus compound (F) in addition to the titanium compound (E), the ratio (Ti / P) of the number of titanium atoms to the number of phosphorus atoms is 0.02 or more and 2 or less. It is preferable to do this. Ti / P is more preferably 0.035 or more and 1.0 or less, and still more preferably 0.05 or more and 0.5 or less.

  In the production method of the present invention, the oligomerization step may be performed in the presence of the phosphorus compound (F) and the germanium compound (G) in addition to the titanium compound (E). The number of phosphorus atoms in the oligomerization step is 0.0001% to 5%, preferably 0.001% to 0.5%, more preferably 0.005, of the number of dicarboxylic acid structural units in the ester (D). The phosphorus compound (F) is preferably present so as to be not less than 0.1% and not more than 0.1%, and the number of germanium atoms is 0.0001 mol% to 5 mol%, preferably 0.001 mol% to 0.5%. The germanium compound (G) may be present so as to be not more than mol%, more preferably not less than 0.01 mol% and not more than 0.1 mol%. The presence of phosphorus atoms and germanium atoms in the above proportions can suppress specific coloration of the polyester resin when the titanium compound (E) is used as a catalyst to a degree that cannot be achieved by the phosphorus compound (F) alone.

  As the phosphorus compound (F), those described above can be used, and the germanium compound (G) is not particularly limited, but germanium oxides such as amorphous germanium dioxide and crystalline germanium dioxide; germanium tetraethoxide, germanium Germanium alkoxides such as tetraisopropoxide and germanium tetra-n-butoxide; germanium carboxylates such as germanium acetate; germanium halides such as germanium chloride; germanium hydroxide and the like can be used. Of these, germanium dioxide is preferable. The germanium compound (G) can be used alone, or a plurality of them can be used simultaneously. Germanium dioxide is preferably used in either an aqueous solution or a solution of diol (C) having no cyclic acetal skeleton. The phosphorus atom may be present at a predetermined ratio to the number of dicarboxylic acids of the ester (D) at the start of the oligomerization step, and a phosphorus compound is used as a heat stabilizer during the production of the ester (D). When phosphorus atoms are already present at a predetermined ratio at the start of the process, the phosphorus compound (E) may not be newly added at the start of the oligomerization process. The same applies to germanium atoms. When a germanium compound is used as a catalyst at the time of producing the ester (D), and germanium atoms are already present at a predetermined ratio at the start of the oligomerization step, germanium is used at the start of the oligomerization step. It is not necessary to newly add the compound (G). When germanium dioxide is used as an aqueous solution as the germanium compound (G), if it is added after the production of the ester (D), the water content of the reaction mixture in the oligomerization step exceeds 0.5% by weight, and the diol having a cyclic acetal skeleton Decomposition of (A), trifunctional, and tetrafunctionalization may occur, which is not preferable. For the above reasons, when germanium dioxide is used as the germanium compound (G) in an aqueous solution, it is most preferable to add it at the start of the production of the ester (D).

  In the production method of the present invention, when the phosphorus compound (E) and the germanium compound (G) are used in addition to the titanium compound (E), the ratio between the number of titanium atoms and the number of phosphorus atoms present in the oligomerization step The ratio between the number of titanium atoms and the number of germanium atoms is preferably within a predetermined range. That is, a value obtained by dividing the number of titanium atoms (Ti) by the number of phosphorus atoms (P) (Ti / P) is 0.02 or more and 2 or less, and a value obtained by dividing Ti by the number of germanium atoms (Ge) (Ti / Ge) is preferably 0.05 or more and 1 or less.

  In the production method of the present invention, in the oligomerization step, the number of basic compound molecules is 0.0001% or more and 5% or less, preferably 0.001% or more and 0.005% or less of the number of dicarboxylic acid structural units in the ester (D). The basic compound (H) may be present so that it is 5% or less, more preferably 0.005% or more and 0.1% or less. When the ratio is within a predetermined range, thermal stability can be imparted to the polyester resin. Therefore, it is possible to obtain a molded article having excellent appearance and mechanical strength without causing a significant decrease in molecular weight when molding the obtained polyester resin. The basic compound (H) is most preferably added at the start of the oligomerization step.

  The basic compound (H) used in the production method of the present invention is not particularly limited, but carbonates, hydroxides, carboxylates, oxides, chlorides of alkali metals such as lithium, sodium, and potassium. And alkoxides; carbonates, hydroxides, carboxylates, oxides, chlorides, alkoxides of alkaline earth metals such as beryllium, magnesium and calcium; and amine compounds such as trimethylamine and triethylamine. Among these, alkali metal carbonates, hydroxides, and carboxylates; alkaline earth metal carbonates, hydroxides, and carboxylates are preferred, and alkali metal carboxylates are particularly preferred. By using an alkali metal carboxylate, the heat decomposability can be particularly improved, and in addition, the transparency of the resin is particularly excellent. As alkali metal carboxylates, for example, alkali metal formate, acetate, propionate, butyrate, isobutyrate, valerate, caproate, caprylate, caprate, laurate, Examples include myristate, palmitate, stearate, benzoate, among which alkali metal formate, acetate, propionate, butyrate, isobutyrate, and benzoate are preferred, potassium acetate Sodium acetate, lithium acetate, potassium propionate, sodium propionate, and lithium propionate are particularly preferred. These can be used alone or in combination.

  In the oligomerization step, when the moisture content of the reaction mixture is 0.5% by weight or less, when the oligomer is produced from the ester (D) and the diol (A) having a cyclic acetal skeleton, The decomposition of the diol (A) it has can be suppressed. The water content of the reaction mixture is preferably 0.3% by weight or less, more preferably 0.1% by weight or less.

  The high molecular weight process in the method for producing a polyester resin of the present invention is a process for increasing the molecular weight by polycondensing the oligomer produced in the oligomerization process under reduced pressure. The high molecular weight process can be performed without any change from the polycondensation process in the conventional polyester resin production method. That is, the pressure of the reaction system is gradually lowered and finally lowered to about 0.1 to 300 Pa. If the final pressure in the polycondensation reaction exceeds 300 Pa, the reaction rate of the polycondensation reaction may not be sufficiently increased, which is not preferable. In addition, the temperature of the polycondensation reaction is gradually increased, and is preferably performed at 190 to 300 ° C. If the temperature of the polycondensation reaction exceeds 300 ° C., undesirable side reactions such as thermal decomposition of the reaction product may occur, which is not preferable. In addition, at the above temperature, yellowing of the obtained polyester resin may become remarkable, which is not preferable. Determination of completion | finish of a high molecular weight process can be performed similarly to the manufacturing method of a general polyester resin. That is, it can be performed by detecting that the polyester resin has reached a desired degree of polymerization by melt viscosity. As a method for detecting the melt viscosity, it is convenient and preferable to read the load of the stirrer as torque, the load current value of the motor, and the like. The reaction time of the high molecular weight process is preferably within 6 hours, more preferably within 4 hours, and by the reaction time being within the above range, decomposition of the diol (A) having a cyclic acetal skeleton, trifunctional, tetrafunctional Undesirable side reactions such as conversion can be suppressed and the yellowness of the polyester resin is also small.

  Since the titanium compound (E) functions as a polycondensation catalyst, it is not necessary to add a new catalyst in the high molecular weight process, but the number of metal atoms in the catalyst as a cocatalyst is 0.0001, which is the number of dicarboxylic acid structural units. A conventionally known catalyst may be added so as to be ˜5%.

  In the production method of the present invention, conventionally known etherification inhibitors, various stabilizers of heat stabilizers, polymerization regulators and the like can be used. Examples of the etherification inhibitor include amine compounds. Other light stabilizers, antistatic agents, lubricants, antioxidants, mold release agents and the like may be added.

  The molecular weight distribution (Mw / Mn) of the polyester resin produced by the method for producing a polyester resin of the present invention is preferably 2.5 to 12.0, more preferably 2.5 to 7.0, still more preferably. Is 2.5 to 5.0. When the molecular weight distribution of the polyester resin is within the above range, the moldability of the polyester resin becomes good.

  When molding using the polyester resin obtained in the present invention, a conventionally known molding method can be used and is not particularly limited. For example, injection molding, extrusion molding, calendar molding, extrusion foam molding, Extrusion blow molding, injection blow molding, etc. can be illustrated.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples. The evaluation method is as follows.

[Evaluation of ester (D)]
(1) Acid value 1 g of ester (D) was precisely weighed and dissolved in 50 ml of o-cresol / chloroform / 1,1,2,2-tetrachloroethane (mass ratio 70/15/15). This solution was subjected to potentiometric titration with 0.1N potassium hydroxide ethanol solution. The titration was performed with Hiranuma Sangyo Co., Ltd. automatic titrator COM-2000.
(2) Average degree of polymerization 2 mg of ester (D) was dissolved in 20 g of chloroform / 1,1,1,3,3,3-hexafluoro-2-propanol (mass ratio 99/1) and gel permeation chromatography. Measured by chromatography (GPC) and calibrated with standard polystyrene. GPC was measured at a column temperature of 40 ° C. using TOSOH 8020 manufactured by Tosoh Corporation, to which two columns TSK GMHHR-L manufactured by Tosoh Corporation and one TSK G5000HR were connected. As an eluent, chloroform was flowed at a flow rate of 1.0 ml / min, and measurement was performed with a UV detector.

[Evaluation of reaction mixture at start of oligomerization process]
(1) Water content 0.1 g of the reaction mixture of ester (D) and diol (A) was precisely weighed, and the water vaporized with a water vaporizer was measured with a moisture analyzer under a nitrogen flow. The measurement was performed using a trace moisture measuring device CA-05 type manufactured by Mitsubishi Chemical Corporation, a nitrogen flow rate of 200 ml / min, a temperature of the moisture vaporizer of 235 ° C., and a measuring time of 30 minutes.

[Evaluation of adhesion of sublimate]
(1) Pressure observation during high molecular weight process The pressure after full vacuum in the high molecular weight process was observed and evaluated according to the following criteria.
○: Ultimate pressure was 100 Pa or less, pressure was generally constant or gradually decreased Δ: Ultimate pressure exceeded 100 Pa, and was 300 Pa or less ×: Ultimate pressure was not 300 Pa or less (2) High molecular weight Visual evaluation of piping after the conversion step After the high molecular weight conversion step, the inside of the vacuum piping of the apparatus was visually observed and evaluated according to the following evaluation criteria.
○: Sublimation hardly adheres. △: Sublimation adheres. ×: Piping is blocked by sublimation.

[Evaluation of polyester resin]
(1) Number average molecular weight, molecular weight distribution (Mw / Mn)
Polyester resin (2 mg) was dissolved in 20 g of chloroform, measured by gel permeation chromatography (GPC), and calibrated with standard polystyrene as Mn1 and Mw / Mn. GPC was measured at a column temperature of 40 ° C. using TOSOH 8020 manufactured by Tosoh Corporation, to which two columns TSK GMHHR-L manufactured by Tosoh Corporation and one TSK G5000HR were connected. As an eluent, chloroform was flowed at a flow rate of 1.0 ml / min, and measurement was performed with a UV detector.
(2) Copolymerization rate of diol having cyclic acetal skeleton 20 mg of polyester resin was dissolved in 1 g of deuterated chloroform, and the copolymerization rate of diol having a cyclic acetal skeleton was calculated from 1H-NMR measurement and peak area ratio. The measurement was performed at 400 MHz using NM-AL400 manufactured by JEOL Ltd.
(3) Introduction rate of diol having a cyclic acetal skeleton Dividing the copolymerization rate of the diol having a cyclic acetal skeleton calculated by the above method by the theoretical copolymerization rate calculated from the charged amount and multiplying by 100, the cyclic acetal The introduction rate of the diol having a skeleton was used.
(4) Evaluation of Yellowness A polyester resin is 3.2 mm thick under the conditions of a cylinder temperature of 240 ° C. to 280 ° C. and a mold temperature of 35 ° C. using a screw type injection molding machine (screw diameter: 32 mm, mold clamping force: 9.8 kN). The sample was molded into a disk with a diameter of 100 mm and used as a measurement sample. The yellowness was measured according to JIS K 7103 by a transmission method using a color difference meter (model: Z-II) manufactured by Nippon Denshoku Industries Co., Ltd. in an atmosphere of 23 ° C. and 50% relative humidity.
(5) Evaluation of impact resistance The molded body having a thickness of 3.2 mm obtained by the above method was evaluated. When a tip having a hemispherical shape with a diameter of 20 mm and a weight of 19.4 kg was freely dropped from a predetermined height onto the molded body, the height at which the molded body was not broken was measured, and the weight was given to the molded body. Expressed in energy. The apparatus used was a falling weight impact measuring tester manufactured by PARKER CORPORATION.

Examples 1-12
The dicarboxylic acid (B) shown in Tables 1 to 3 and a diol (C) having no cyclic acetal skeleton, a phosphorus compound (F), and a germanium compound (G) were charged, and an esterification reaction was carried out in a conventional manner. The amounts of diol for depolymerization (C) and manganese acetate described in Tables 1 to 3 were added to the obtained ester, and depolymerization was performed at 215 ° C. and normal pressure. The reaction was carried out for 3 hours while distilling off the water produced, and then the diol (C) was distilled off at 215 ° C. and 13.3 kPa to obtain esters (D2-1 to D2-12) (production method (2 )). Table 1 shows the average degree of polymerization and acid value of the obtained esters (D2-1 to D2-12). The germanium compound (G) was added as a 1 wt% aqueous solution.
To the obtained esters (D2-1 to D2-12), a predetermined amount of a titanium compound (E) described in Tables 1 to 3, a diol (A) having a cyclic acetal skeleton, and a basic compound (H) is added, The reaction was performed at 225 ° C. and 13.3 kPa for 3 hours. During the reaction, the diol (C) is distilled out of the reaction system, and the sum (mol) of the constituent units of the diol (A) and the diol (C) in the oligomer is the constituent unit amount (mol) of the dicarboxylic acid (B). The divided value (expressed as diol / acid in the table) was the value shown in Tables 1 to 3 (oligomerization step).
The oligomer was heated and depressurized, and finally subjected to a polycondensation reaction at 270 ° C. under a high vacuum (300 Pa or less). When the predetermined melt viscosity was reached, the reaction was terminated to obtain a polyester resin (high molecular weight) Process).
The evaluation results of the obtained polyester resin are shown in Tables 1-3.
Abbreviations PTA: terephthalic acid PET: polyethylene terephthalate BHET: bis-β-hydroxyethyl terephthalate EG: ethylene glycol SPG: 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8 , 10-tetraoxaspiro [5.5] undecane DOG: 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane TBT: tetra-n-butyl titanate TMP: trimethyl phosphate GeO ₂ : germanium dioxide Sb ₂ O ₃ : antimony trioxide Ti ratio (%): ratio of number of titanium atoms to number of dicarboxylic acid structural units in ester (D) P ratio (%): ester Ratio of the number of phosphorus atoms to the number of dicarboxylic acid structural units in (D) Ge ratio (%): Tel ratio of the number of germanium atoms to the number of the dicarboxylic acid constitutional units in the (D)

Examples 13-16
The dicarboxylic acid (B) shown in Table 4 and a diol (C) having no cyclic acetal skeleton, a phosphorus compound (F), and a germanium compound (G) were charged, and an esterification reaction was performed by a conventional method. After completion of the esterification reaction, a polycondensation reaction was performed by a conventional method to obtain esters (D1-1 to D1-3) (production method (1)). Table 4 shows the average degree of polymerization and acid value of the obtained esters (D1-1 to D1-3). The germanium compound (G) was added as a 1 wt% aqueous solution.
To the obtained esters (D1-1 to D1-3), a predetermined amount of a titanium compound (E) described in Table 4, a diol (A) having a cyclic acetal skeleton, and a basic compound (H) is added, and the temperature is 225 ° C. The reaction was performed at 13.3 kPa for 3 hours. During the reaction, the diol (C) is distilled out of the reaction system, and the sum (mol) of the constituent units of the diol (A) and the diol (C) in the oligomer is the constituent unit amount (mol) of the dicarboxylic acid (B). The divided value (expressed as diol / acid in the table) was the value shown in Table 4 (oligomerization step).
The oligomer was heated and depressurized, and finally subjected to a polycondensation reaction at 270 ° C. under a high vacuum (300 Pa or less). When the predetermined melt viscosity was reached, the reaction was terminated to obtain a polyester resin (high molecular weight) Process).
Table 4 shows the evaluation results of the obtained polyester resin.

Examples 17-19
Bis (β-hydroxyethyl) terephthalate (BHET) manufactured by Kanto Chemical Co., Ltd. was used as the ester (D).
To BHET, the amount of diol (A), titanium compound (E) phosphorus compound (F), germanium compound (G) and 0.02 mol% of potassium acetate based on the dicarboxylic acid structural unit are added to BHET, Reaction was performed at 225 degreeC and 13.3 kPa for 3 hours (oligomerization process). The germanium compound (G) was added as a 0.5 wt% EG solution.
The oligomer was heated and depressurized, and finally subjected to a polycondensation reaction at 270 ° C. under a high vacuum (300 Pa or less). When the predetermined melt viscosity was reached, the reaction was terminated to obtain a polyester resin (high molecular weight) Process).
Table 5 shows the evaluation results of the obtained polyester resin.

Comparative Examples 1-4
Except that 0.03 mol% of antimony trioxide or germanium dioxide was used instead of the titanium compound (E) in the oligomerization step with respect to the dicarboxylic acid structural unit in the ester (D), the same as in Examples 1-3. A polyester resin was obtained (Table 6). Note that antimony trioxide was added in a 2 wt% EG solution, and germanium dioxide was added in a 0.5 wt% EG solution.
Since the titanium compound (E) was not used, the introduction rate was remarkably reduced. Further, since the diol (C) has sublimability, the ultimate pressure may increase or the piping may be blocked, and stable operation is difficult. In Comparative Example 2, the reaction was terminated halfway due to the blockage of the pipe, and the polyester resin could not be obtained in a form that could be injection molded.

Claims (19)

A method for producing a polyester resin comprising a dicarboxylic acid structural unit and a diol structural unit, wherein 5 to 60 mol% of the diol structural unit is a structural unit having a cyclic acetal skeleton, and has an acid value of 30 μeq / g or less. An oligomerization step of producing an oligomer by transesterifying the ester (D) represented by the formula (1) and the diol (A) having a cyclic acetal skeleton in the presence of the titanium compound (E); A method for producing a polyester resin, comprising a step of increasing the molecular weight of the polymer.

(In the formula, R ¹ , R ² , and R ³ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a carbon number. Represents a hydrocarbon group selected from the group consisting of 6 to 10 aromatic hydrocarbon groups, n is 1 or more and 200 or less.) The method for producing a polyester resin according to claim 1, wherein the ester (D) is a bishydroxyalkyl ester of dicarboxylic acid and / or a polymer thereof. The ester (D) is a bishydroxyalkyl ester of one or more dicarboxylic acids selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid and / or a polymer thereof. The manufacturing method of the polyester resin in any one of claim | item 1-2. The ester (D) is a dicarboxylic acid bishydroxyalkyl having an average polymerization degree of 15 or more and 200 or less obtained by esterification of the dicarboxylic acid (B) with a diol (C) having no cyclic acetal skeleton and then polycondensation. It is a polymer of ester, The manufacturing method of the polyester resin in any one of Claims 1-3 characterized by the above-mentioned. A low polymer obtained by esterifying the dicarboxylic acid (B) with a diol (C) having no cyclic acetal skeleton and / or a high polymer obtained by polycondensation of the low polymer. Is a polymer of a bishydroxyalkyl ester of a dicarboxylic acid having an average degree of polymerization of less than 15 and a melting point of 240 ° C. or less, obtained by depolymerization with a diol (C) having no cyclic acetal skeleton. The manufacturing method of the polyester resin in any one of claim | item 1-3. Ester (D) is polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, isophthalic acid modified polyethylene terephthalate, 1,4-cyclohexanedimethanol modified polyethylene terephthalate, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) ) -2,4,8,10-tetraoxaspiro [5.5] undecane-modified polyethylene terephthalate and 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3 A dicarboxylic acid having an average polymerization degree of less than 15 and a melting point of 240 ° C. or less, obtained by depolymerizing one or more polyester resins selected from the group consisting of dioxane-modified polyethylene terephthalate with a diol (C) having no cyclic acetal skeleton. Bishydroxyal Process for producing a polyester resin according to any one of claims 1 to 3, characterized in that a polymer of glycol ester. The method for producing a polyester resin according to claim 1, wherein the ester (D) is bis (β-hydroxyethyl) terephthalate. The method for producing a polyester resin according to claim 1, wherein the diol (A) having a cyclic acetal skeleton is a compound represented by the formula (2) and / or a compound represented by the formula (3). .

(In the formula, R ⁴ and R ⁵ are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and 6 to 10 carbon atoms. Represents a divalent hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups.)

(In the formula, R ⁶ is a group consisting of an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms. A divalent hydrocarbon group selected from R ⁷ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic group having 6 to 10 carbon atoms Represents a monovalent hydrocarbon group selected from the group consisting of hydrocarbon groups.) Diol (A) having a cyclic acetal skeleton is 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane or 5- It is methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane, The manufacturing method of the polyester resin in any one of Claims 1-8 characterized by the above-mentioned. The number of titanium atoms in an oligomerization process is 0.0001 to 5% of the number of dicarboxylic acid structural units in ester (D), The polyester resin in any one of Claims 1-9 characterized by the above-mentioned. Production method. The titanium compound (E) is at least one selected from the group consisting of orthotitanate, titanium carboxylate, alkali metal titanate, titanium halide, and titanium oxide. The manufacturing method of the polyester resin in any one of Claims 1-10 to do. The oligomerization step is performed in the presence of a phosphorus compound (F), and the number of phosphorus atoms is 0.0001 to 5% of the number of dicarboxylic acid structural units in the ester (D). The manufacturing method of the polyester resin in any one of 11. The value (Ti / P) obtained by dividing the number of titanium atoms (Ti) in the titanium compound (E) by the number of phosphorus atoms (P) in the oligomerization step is 0.02 or more and 2 or less. The manufacturing method of the polyester resin of Claim 12. The oligomerization step is performed in the presence of the phosphorus compound (F) and the germanium compound (G), and the number of phosphorus atoms and the number of germanium atoms are 0.0001 to 0.001 to the number of dicarboxylic acid constituent units in the ester (D), respectively. It is 5%, The manufacturing method of the polyester resin in any one of Claims 1-11 characterized by the above-mentioned. The value (Ti / P) obtained by dividing the number of titanium atoms (Ti) in the titanium compound (E) by the number of phosphorus atoms (P) in the oligomerization step is 0.02 or more and 2 or less, and (Ti ) Divided by the number of germanium atoms (Ge) (Ti / Ge) is from 0.05 to 1, the method for producing a polyester resin according to claim 14. The phosphorus compound (F) is at least one selected from the group consisting of phosphoric acid, phosphorous acid, phosphoric acid ester, and phosphorous acid ester, according to any one of claims 12 to 15. A method for producing a polyester resin. The germanium compound (G) is at least one selected from the group consisting of germanium oxide, germanium alkoxide, germanium carboxylate, germanium halide, and germanium hydroxide. The manufacturing method of the polyester resin in any one of 16. The oligomerization step is performed in the presence of the basic compound (H), and the number of molecules of the basic compound is 0.0001 to 5% of the number of dicarboxylic acid constituent units in the ester (D). The manufacturing method of the polyester resin in any one of Claims 1-17. The method for producing a polyester resin according to any one of claims 1 to 18, wherein in the oligomerization step, the moisture content of the reaction mixture is 0.5% by weight or less.