JP2004285328A - Polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a packaging material which is excellent in transparency, has an appropriate, stable crystallization rate, exhibits excellent heat-resistant dimensional stability, can efficiently give a molded item inhibited from emission of fluorescence under ultraviolet irradiation, particularly a heat-resistant blow-molded item, and exhibits a long-term continuous molding property excellent enough hardly to cause mold stains and an excellent flavor-retaining property. <P>SOLUTION: The polyester resin is composed mainly of a terephthalic acid component and a glycol component and has a fluorescence emission intensity (B<SB>0</SB>) of at most 20 at 450 nm in the fluorescence spectrum emitted when irradiated with an exciting light of a wavelength of 343 nm. The polyester gives an increase (B<SB>h</SB>-B<SB>0</SB>) in the fluorescence emission intensity of at most 30, where (B<SB>h</SB>) is the fluorescence emission intensity at 450 nm in the fluorescence spectrum obtained when the polyester resin having been subjected to a heat treatment at 180°C for 10 hr is irradiated with an exciting light of a wavelength of 343 nm and (B<SB>0</SB>) is the fluorescence emission intensity at 450 nm obtained when a non-heat-treated polyester resin is irradiated likewise. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyester resin suitably used as a material of a molded article such as a beverage bottle, a hollow molded article such as a sheet, a film, and a monofilament, a polyester resin composition comprising the same, and a polyester molded article composed thereof. In particular, it is excellent in transparency, moderate, and has a stable crystallization rate, giving a molded article and the like having excellent heat-resistant dimensional stability, and a molded article and the like in which the emission of fluorescence during ultraviolet irradiation is prevented. The present invention also relates to a polyester resin which gives a hollow molded article, a sheet-like material, and a stretched film excellent in flavor retention and hardly generates mold stains during molding of the molded article, and a polyester resin composition comprising the same. It is.

Polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties. Ideal as a material and used in large quantities.
It is also used in large quantities on a global scale as industrial materials such as clothing fibers and tire cords.
In a polyester bottle for beverages, the bottle is hot-filled with a beverage sterilized at a high temperature, or after filling the beverage, the bottle is sterilized at a high temperature. However, deformation occurs and becomes a problem.

  Therefore, as a method for improving the heat resistance of the polyester bottle, a method has been proposed in which the crystallinity of the bottle is increased by heat treatment of the bottle stopper, or the stretched bottle is heat-fixed. In particular, when the crystallization of the plug portion is insufficient or when the degree of crystallization varies widely, the sealing performance with the cap is deteriorated and the contents may leak. In addition, when the degree of crystallinity at the shoulder and the body of the bottle is insufficient, thermal deformation may occur and the commercial value may decrease.

  Specifically, in the case of beverages that require hot filling, such as fruit juice beverages, Wurong tea, mineral water, etc., the preform or molded bottle is heat-treated at the plug portion to crystallize. (See, for example, Patent Documents 1 and 2). When the preform plug in the amorphous state is heated and crystallized, so-called spherulite crystallization is promoted and the plug appearance becomes white, but the crystallinity increases and the heat resistance (that is, the heat distortion temperature) increases. Becomes higher). Further, in order to improve the heat resistance of the bottle body, a method of performing heat treatment by setting the temperature of a stretch blow mold to a high temperature is adopted (for example, see Patent Document 3).

  When heat treatment is performed by contacting the shoulder and body of a bottle obtained by stretching and blowing such a preform with a high-temperature mold wall surface, in addition to oriented crystallization by stretch blowing, crystallization from spherulites is performed. The generation of small-sized microcrystals is promoted, the degree of crystallization is increased, and the heat resistance of the bottle can be improved.

  Such a method, that is, a method of improving the heat resistance by heat treatment of the plug portion and the shoulder portion, the time and temperature for the crystallization treatment greatly affect the productivity, and the crystal can be treated at a low temperature and in a short time. It is preferable that the PET is a PET having a high conversion rate. On the other hand, the body is required to be transparent even when subjected to heat treatment during molding so as not to deteriorate the color tone of the contents of the bottle and from the aspect of design, and the plug and the body are required to be transparent. Conflicting properties are required. However, if the crystallization rate of PET is too high, crystallization of the preform surface proceeds during reheating of the preform before stretch blowing, and the bottle surface becomes clouded after stretch blowing and heat setting. There is a thing.

  Further, in order to improve the heat resistance of the bottle body, a method of performing heat treatment at a high temperature of a stretch blow mold is employed (for example, see Patent Document 3). However, when a large number of bottles are continuously formed using the same mold by such a method, the bottle obtained with a long operation is whitened and the transparency is reduced, and only a bottle having no commercial value is obtained. . It was found that this was because the mold surface was stained by deposits caused by PET, and this mold stain was transferred to the bottle surface. In particular, in recent years, the molding speed has been increased along with the miniaturization of bottles, and from the viewpoint of productivity, the shortening of the heating time for crystallization of the plug and the contamination of the mold have become more serious problems. .

  Various proposals have been made to solve such a problem. For example, a method of adding an inorganic nucleating agent such as kaolin and talc to polyethylene terephthalate (for example, see Patent Documents 4 and 5), and a method of adding an organic nucleating agent such as a montanic acid wax salt (for example, Patent Document 6) , 7), but these methods involve the generation of foreign matter and cloudiness, and have problems in practical use. In addition, there is a method of adding a treated polyester obtained by pulverizing a polyester molded product obtained by melt-molding the polyester to the raw material polyester (for example, see Patent Document 8), but this method requires an extra step of melt-molding and pulverization. It is necessary, and there is a risk that foreign substances other than polyester may be mixed in such a post-process, which is not a preferable method economically and quality. In addition, although a method of inserting a heat-resistant resin piece into the plug (for example, see Patent Documents 9 and 10) has been proposed, the productivity of the bottle is poor, and there is a problem in recyclability. .

  Further, when PET is extruded into a sheet-like material, and the molded product obtained by vacuum forming the product is filled with food and covered with a lid made of the same material and left as it is, shrinkage occurs and the opening property of the lid deteriorates. Also, if the molded body is left for a long period of time, shrinkage occurs and the lid cannot be formed.

  As a solution for further solving such a problem, a method for modifying PET by contacting a PET chip with a polyethylene member under flowing conditions (for example, see Patent Document 11), A method of modifying PET by contacting a member made of a polypropylene-based resin or a polyamide-based resin (for example, see Patent Document 12) has been proposed. However, even with such a method, a moderate and stable crystallization rate can be obtained. It has been found that it is very difficult to obtain a polyester which gives a molded article having excellent dimensional stability and transparency of the plug after heat crystallization.

  The plug portion of the hollow molded body made of polyester contact-treated with the polyethylene member or the like is crystallized by heat treatment with an infrared heating device or the like to improve heat-resistant dimensional stability. It has been found that if the crystallization rate is too high, crystallization of the plug portion of the hollow molded article from the polyester subjected to the contact treatment becomes excessive, and the dimensions of the plug portion do not fall within the standard value range. As a result, it has been found that normal capping becomes impossible, so that the adhesion between the cap and the plug portion is deteriorated, and a fatal problem of leakage of contents occurs. Further, since the plug portion of the hollow molded body is generally heated only from the outside, the outer surface portion of the plug portion crystallizes faster than the inner surface portion and the intermediate portion. As a result, the degree of crystallinity of the plug becomes uneven in the inner and outer layers. Also, since the plug has a complicated shape with different thicknesses, the dimensions of the plug vary depending on the crystallinity of the polyester and the heating conditions. Therefore, in the case of external heating, if a polyester having a very high crystallization rate is used, the variation in the plug size becomes very large depending on the heating conditions, and stable operation becomes difficult, or the plug standard is not used. It has been found that the frequency of occurrence of foreign articles increases, and that the transparency of the obtained molded article also deteriorates.

  In general, it is common to dry resin chips before molding.However, molding may be stopped due to trouble or drying may be prolonged more than necessary in various situations. However, when a polyester having a prolonged length was used, there were problems such as a decrease in transparency, an unstable crystallization rate, and a deterioration in flavor retention.

  Further, for polyester generally used as a beverage container, a method of increasing the molecular weight of a polymerization chip obtained by melt polymerization by solid phase polymerization is often adopted. The solid-phase polymerization treatment is performed at a temperature equal to or lower than the melting point of the polyester under reduced pressure or in an inert gas atmosphere. Among them, the continuous solid-state polymerization method in which solid-state polymerization is performed while continuously supplying a polyester chip under an inert gas atmosphere, which is excellent in cost performance and widely used, has excellent flavor properties. In order to produce polyethylene terephthalate (hereinafter sometimes abbreviated as PET), the solid-state polymerization temperature and the oxygen concentration in the solid-state polymerization tank are controlled under certain conditions, that is, the solid-state polymerization temperature X (° C.) In some cases, a solid-phase polymerization treatment is performed under conditions that satisfy 190 ≦ X ≦ 230 and Y ≦ −0.8696X + 230.0 for the oxygen concentration Y (ppm) in the phase polymerization tank (Patent Document 13).

  In order to obtain a final product with excellent flavor properties, in order to suppress the generation of by-products such as acetaldehyde and formaldehyde during the solid-state polymerization reaction, an inert gas stream containing hydrogen in the absence of oxygen is used. In other words, the oxygen concentration in the inert gas during the solid-state polymerization is 0.1 mol% or less in the whole gas, and the amount of hydrogen in the inert gas is 0.1 mol% or more in the whole gas. It is carried out at 70 mol% or less (for example, Patent Document 14).

Further, in order to reduce acetaldehyde and formaldehyde in a molded beverage container, there is a method in which solid-phase-polymerized PET is dried under an inert gas stream containing hydrogen in the absence of oxygen (for example, Patent Document 15). ).
However, even if such a method is used, or even if such a polyester resin composition is used, the flavor itself is not sufficiently improved, or the crystallization rate of PET may fluctuate. It has been found that it is very difficult to obtain a polyester which has a stable crystallization rate and gives a molded article having excellent dimensional stability and transparency of the plug after heat crystallization.

  In general, resin chips are usually dried before molding.However, molding may be stopped due to trouble, drying may be prolonged more than necessary in various situations, or resin containing a large amount of moisture may be dried. In the case of conventional polyesters, as in the case of polyesters that have been dried for a long time, such as forced drying for a long period of time, transparency decreases, crystallization speed is not stable, and flavor retention is maintained. There was a problem that the quality deteriorated.

JP-A-55-79237 JP-A-58-110221 JP-B-59-6216 JP-A-56-2342 JP-A-56-21832 JP-A-57-125246 JP-A-57-207639 JP-A-5-105807 JP-A-61-259946 JP-A-2-26938 JP-A-9-71639 JP-A-11-209492 JP-A-9-59362 JP-A-9-3179 JP-A-9-3182

  The present invention solves the problems of the polyester resin according to the prior art described above, and has excellent transparency, a moderate and stable crystallization rate, excellent heat-resistant dimensional stability, and emission of fluorescent light when irradiated with ultraviolet light. Polyester that can efficiently produce prevented molded articles, especially heat-resistant hollow molded articles, and that provides excellent long-term continuous moldability that does not stain the mold, and that provides packaging materials with excellent flavor retention It is an object to provide a resin, a polyester resin composition, and a polyester molded article. Furthermore, the present invention provides a polyester resin, a polyester resin composition, and a polyester molded article, which have little change in the above-mentioned properties even when exposed to unnecessary drying.

  The present inventors have used polyesters mainly composed of a terephthalic acid component and a glycol component, are excellent in transparency and heat-resistant dimensional stability, and as a result of earnestly studying polyesters that give molded bodies with little change in crystallization speed, The inventors have found that the fluorescence emission intensity of the polyester is related to the properties such as the transparency and the crystallization speed of the molded article made of the polyester, and completed the present invention.

The present invention is as follows.
(1) A polyester resin mainly composed of a terephthalic acid component and a glycol component, and has a fluorescence emission intensity (B ₀ ) of 450 nm in a fluorescence spectrum obtained when the polyester resin is irradiated with excitation light having a wavelength of 343 nm. A polyester resin having a molecular weight of 20 or less.

(2) A fluorescence spectrum obtained when the polyester resin mainly composed of a terephthalic acid component and a glycol component, which has been heated at a temperature of 180 ° C. for 10 hours, is irradiated with excitation light having a wavelength of 343 nm. When the fluorescence emission intensity at 450 nm is (B _h ) and the same fluorescence emission intensity at 450 nm of the unheated polyester resin is (B ₀ ), (B _h −B ₀ ) is 30 or less. Polyester resin.

(3) The fluorescence emission intensity at 450 nm (B _h ) in the fluorescence spectrum obtained when the polyester resin heat-treated at a temperature of 180 ° C. for 10 hours was irradiated with excitation light having a wavelength of 343 nm was determined in the same manner as the unheated polyester resin. The polyester resin according to (1), wherein (B _h −B ₀ ) is 30 or less when the fluorescence emission intensity at 450 nm is (B ₀ ).

(4) A polyester resin mainly composed of a terephthalic acid component and a glycol component, and the fluorescence emission intensity at 395 nm in the fluorescence spectrum obtained when the polyester resin is irradiated with excitation light having a wavelength of 343 nm is (A ₀ ), Wherein (B ₀ / A ₀ ) is 0.4 or less when the fluorescence emission intensity at 450 nm is (B ₀ ).

(5) When the fluorescence emission intensity at 395 nm is (A ₀ ) and the fluorescence emission intensity at 450 nm is (B ₀ ) in the fluorescence spectrum obtained by irradiating excitation light having a wavelength of 343 nm, (B ₀ / A ₀₎ ) Is 0.4 or less, the polyester resin according to any one of (1) to (3).

(6) A polyester resin mainly composed of a terephthalic acid component and a glycol component, which has been heated at a temperature of 180 ° C. for 10 hours and is irradiated with excitation light having a wavelength of 343 nm. The ratio (B _h / A _h ) when the fluorescence emission intensity at 395 nm is (A _h ) and the fluorescence emission intensity at 450 nm is (B _h ), and the same fluorescence emission intensity at 395 nm of the unheated polyester resin are ( a _0), a polyester resin difference between the ratio at the time of the fluorescence relative intensity of 450nm and _{(B 0) (B 0 /} a 0) is equal to or is 0.7 or less.

(7) In the fluorescence spectrum obtained when the polyester resin heat-treated at a temperature of 180 ° C. for 10 hours is irradiated with excitation light having a wavelength of 343 nm, the fluorescence emission intensity at 395 nm is (A _h ) and the fluorescence emission intensity at 450 nm is ( _Bh ), the ratio (B _h / A _h ), the fluorescence emission intensity of the unheated polyester resin at 395 nm (A ₀ ), and the fluorescence emission intensity at 450 nm of (B ₀ ) (B ₀ ). The polyester resin according to any one of (1) to (5), wherein the difference from (B ₀ / A ₀ ) is 0.7 or less.

(8) In a fluorescence spectrum obtained when a chip selected from a chip-shaped polyester resin mainly composed of a terephthalic acid component and a glycol component is irradiated with excitation light having a wavelength of 343 nm, the fluorescence emission intensity at 395 nm is (A _S0 ), Wherein (B _S0 / A _S0 ) is 0.3 or less when the relative intensity of fluorescence at 450 nm is (B _S0 ).

(9) The chip-shaped polyester resin according to any one of (1) to (9), wherein a fluorescence spectrum of 395 nm is obtained in a fluorescence spectrum obtained when the selected fluorescent light emitting chip is irradiated with excitation light having a wavelength of 343 nm. A polyester resin, wherein (B _S0 / A _S0 ) is 0.3 or less when the emission intensity is (A _S0 ) and the fluorescence emission intensity at 450 nm is (B _S0 ).

(10) Fluorescence obtained when a chip-shaped polyester resin mainly composed of a terephthalic acid component and a glycol component is heated at a temperature of 180 ° C. for 10 hours and then irradiated with excitation light having a wavelength of 343 nm to a selected fluorescent light emitting chip. A polyester resin, wherein (B _Sh / A _Sh ) is 0.5 or less when the fluorescence emission intensity at 395 nm is (A _Sh ) and the fluorescence emission intensity at 450 nm is (B _Sh ) in the spectrum.

(11) The chip-shaped polyester resin described in any one of (1) to (7), wherein the chip is subjected to a heat treatment at a temperature of 180 ° C. for 10 hours, and then a fluorescent light-emitting chip selected to have excitation light having a wavelength of 343 nm. (B _Sh / A _Sh ) is 0.5 or less when the fluorescence emission intensity at 395 nm is (A _Sh ) and the fluorescence emission intensity at 450 nm is (B _Sh ) in the fluorescence spectrum obtained when A polyester resin, characterized in that:

(12) When a polyester resin mainly composed of a terephthalic acid component and a glycol component, which is heat-treated at a temperature of 180 ° C. for 10 hours and crushed into a powder, is irradiated with excitation light having a wavelength of 343 nm. The ratio (B _Ph / A _Ph ) when the fluorescence emission intensity at 395 nm is (A _Ph ) and the fluorescence emission intensity at 450 nm is (B _Ph ) in the fluorescence spectrum obtained in (1), Polyester resin characterized in that the difference from the ratio (B _P0 / A _P0 ) when the fluorescence emission intensity at 395 nm is (A _0P ) and the relative fluorescence intensity at 450 nm is (B _P0 ) is 0.5 or less. .

(13) A polyester resin mainly composed of a terephthalic acid component and a glycol component, which is obtained by irradiating excitation light having a wavelength of 343 nm to a powder obtained by pulverizing the polyester resin into a powdery form. (A _P0 ) A polyester resin characterized in that (B _P0 / A _P0 ) is 0.3 or less, where (B _P0 ) is the fluorescence emission intensity at 450 nm.

(14) The fluorescence emission intensity at 395 nm in the fluorescence spectrum obtained when irradiating excitation light having a wavelength of 343 nm to a pulverized polyester resin is (A _P0 ), and the fluorescence emission intensity at 450 nm is (B _P0 ). The polyester resin according to any one of (1) to (12), wherein (B _P0 / A _P0 ) is 0.3 or less.

(15) The polyester resin according to any one of (1) to (14), wherein the amount of increase in the color b value when heat-treated at a temperature of 180 ° C. for 10 hours is 4 or less.

(16) The polyester resin according to any one of (1) to (15), which is a polyester resin having a cyclic trimer content of 0.7% by weight or less and containing ethylene terephthalate as a main repeating unit. Polyester resin as described.

(17) The method according to any one of (1) to (16), wherein the amount of increase in the cyclic ester oligomer when the polyester resin is melted at a temperature of 290 ° C. for 60 minutes is 0.50% by weight or less. Polyester resin.

(18) The method according to any one of (1) to (17), wherein a content of the polyester fine having the same composition as the polyester is 0.1 to 10000 ppm, and the melting point of the fine measured by DSC is 265 ° C. or less. Polyester resin as described.

(19) The dimensional change rate of a 3 mm-thick molded plate obtained by injection molding measured by thermomechanical analysis (TMA) is 1.0% to 7.0%. The polyester resin according to any one of (18).

The polyester resin of the present invention is a polyester resin having specific fluorescence emission characteristics as described above, and includes (A ₀ ), (B ₀ ), (A _h ), (B _h ), (A _S0 ), and (B ₀ ). _S0 ), (A _Sh ), (B _Sh ), (A _P0 ), (B _P0 ), (A _Ph ), and (B _Ph ) are defined as follows. Fulfill. Note that the characteristics of these equations may be collectively referred to as fluorescence emission characteristics.

Formula 1 (B ₀ ) ≦ 20
Equation 2 (B _h −B ₀ ) ≦ 30
Equation 3 (B ₀ / A ₀ ) ≦ 0.4
Equation 4 (B _h / A _h ) − (B ₀ / A ₀ ) ≦ 0.7
Equation 5 (B _S0 / A _S0 ) ≦ 0.3
Equation 6 (B _Sh / A _Sh ) ≦ 0.5
Equation 7 (B _Ph / A _Ph ) − (B _P0 / A _P0 ) ≦ 0.5
Equation 8 (B _P0 / A _P0 ) ≦ 0.3

(A ₀ ): Fluorescence emission intensity at 395 nm (B ₀ ) in a fluorescence spectrum obtained when the polyester resin was irradiated with excitation light having a wavelength of 343 nm: A fluorescence spectrum obtained when the polyester resin was irradiated with excitation light having a wavelength of 343 nm. Emission intensity at 450 nm

(A _h ): Fluorescence emission intensity at 395 nm (B _h ) in a fluorescence spectrum obtained when the polyester resin heat-treated at a temperature of 180 ° C. for 10 hours was irradiated with excitation light having a wavelength of 343 nm: 10 hours at a temperature of 180 ° C. Fluorescence emission intensity at 450 nm in a fluorescence spectrum obtained when the heat-treated polyester resin is irradiated with excitation light having a wavelength of 343 nm.

(A _S0 ): When irradiating excitation light having a wavelength of 343 nm to a fluorescent light-emitting chip selected by the method described in the measurement method section of Example while irradiating excitation light composed of ultraviolet light having a maximum wavelength of 352 nm and 300 to 400 nm. Fluorescence intensity (B _S0 ) at 395 nm in the fluorescence spectrum obtained in Example 1. Fluorescence emission selected by the method described in the measurement method section of the Examples while irradiating excitation light composed of ultraviolet rays having a maximum wavelength of 352 nm and 300 to 400 nm. Fluorescence emission intensity at 450 nm in the fluorescence spectrum obtained when the chip is irradiated with excitation light having a wavelength of 343 nm

(A _Sh ): Fluorescence emission selected by the method described in the measurement method section of the example while irradiating excitation light consisting of ultraviolet light having a maximum wavelength of 352 nm and 300 to 400 nm after heat treatment at a temperature of 180 ° C. for 10 hours. A fluorescence emission intensity (B _Sh ) at 395 nm in a fluorescence spectrum obtained when the chip is irradiated with excitation light having a wavelength of 343 nm: a UV light having a maximum wavelength of 352 nm and a wavelength of 300 to 400 nm after a heat treatment at a temperature of 180 ° C. for 10 hours. The fluorescence emission intensity at 450 nm in the fluorescence spectrum obtained when the fluorescence emission chip selected by the method described in the measurement method section of the example is irradiated with the excitation light while irradiating the excitation light with the excitation light having the wavelength of 343 nm.

(A _P0 ): Fluorescence emission intensity at 395 nm (B _P0 ) in a fluorescence spectrum obtained when irradiating excitation light having a wavelength of 343 nm to a polyester resin pulverized in a powder form: Excitation at a wavelength of 343 nm in a polyester resin pulverized into a powder form Fluorescence emission intensity at 450 nm in the fluorescence spectrum obtained when irradiated with light

(A _Ph ): 395 nm fluorescence emission intensity (B _Ph ) in a fluorescence spectrum obtained when a polyester resin pulverized into a powder after being heat-treated at a temperature of 180 ° C. for 10 hours is irradiated with excitation light having a wavelength of 343 nm. Fluorescence emission intensity of 450 nm in a fluorescence spectrum obtained when a polyester resin pulverized into a powder after being heat-treated at a temperature of 10 ° C. for 10 hours is irradiated with excitation light having a wavelength of 343 nm.

In the present invention, the fluorescence emission intensity (B ₀ ) at 450 nm of the polyester is preferably 15 or less, more preferably 10 or less, and further preferably 7 or less.
(B _h −B ₀ ) is preferably 25 or less, more preferably 20 or less, and most preferably 15 or less.
(B ₀ / A ₀ ) is preferably 0.30 or less, more preferably 0.20 or less, and most preferably 0.10 or less.
( _Bh / _Ah )-( _B0 / _A0 ) is preferably 0.5 or less, more preferably 0.45 or less, still more preferably 0.40 or less, and most preferably 0.35 or less.
(B _S0 / A _S0 ) is preferably 0.20 or less, more preferably 0.10 or less, and most preferably 0.07 or less. (B _Sh / A _Sh ) is preferably 0.45 or less, more preferably Preferably it is 0.40 or less, most preferably 0.35 or less.
(B _Ph / A _Ph ) − (B _P0 / A _P0 ) is preferably at most 0.45, more preferably at most 0.40, particularly preferably at most 0.35, most preferably at most 0.20.
(B _P0 / A _P0 ) is preferably 0.20 or less, more preferably 0.15 or less, and most preferably 0.10 or less.

  It is not necessary to satisfy all of these fluorescence emission characteristics, but it is preferable that at least two, more preferably three or more, desirably four or more, and especially five or more are satisfied in any combination. Most preferably, all are satisfied.

  If the polyester resin has a fluorescence emission property outside the above range, the crystallization rate of the plug portion of the hollow molded article obtained from such a polyester resin is high, so that the crystallization becomes excessive, and the The dimensions are no longer within the specified range, and the difference between the crystallinity of the outer surface of the heat-crystallized hollow plug and the crystallinity of the inner surface and middle part of the plug becomes large. In some cases, the degree of non-uniformity of the crystallinity may increase, and the fluctuation of the crystallinity between the molded products may become very large. Due to these factors, the shrinkage amount of the plug portion does not fall within the specified value range, and capping failure of the plug portion occurs, which may cause leakage of the contents. Further, the preform for hollow molding is whitened, and the transparency of the hollow molded body obtained by stretch-blowing becomes extremely poor, and normal stretching may not be possible. In addition, when a molded article such as a hollow molded article obtained from such a polyester resin is irradiated with ultraviolet rays and visually observed, the commercial value is reduced due to the undesirable characteristic of strongly emitting pale fluorescent light. There is. These problems become significant when exposed to prolonged drying before molding.

  According to the study of the present inventors, a polyester mainly composed of a terephthalic acid component and a glycol component essentially has fluorescence emission characteristics, and when this is irradiated with excitation light of 343 nm, a peak near 395 nm is obtained. And emits fluorescence up to a region of about 600 nm. The emitted fluorescence spectrum is measured in the range of 350 nm to 600 nm by the method described in the section of the measurement method, and the relative intensity of the fluorescence emission at 450 nm is obtained. This is referred to as the fluorescence emission intensity in the present invention.

  It has been found that the fluorescence intensity at the 395 nm peak of the normal polyester produced with great care in the laboratory is less than 85 and the fluorescence intensity at 450 nm is less than about 20.

In the present invention, fluorescence is emitted when a certain substance absorbs light energy to be in an excited state and returns to a ground state, as described in the Analytical Chemistry Experiment Handbook (edited by the Analytical Chemistry Society of Japan: 425: Maruzen). Light. The intensity If of the emitted fluorescence is proportional to the intensity Ia of the absorbed excitation light and the quantum yield φf, and is expressed by If = kIaφf. Since the absorption of the excitation light follows Lambert-Beer's law, If = kIo (1-10- ^ecd ) .phi.f. Here, k is a device constant such as light collection and detection efficiency, Io is the intensity of the excitation light, e is the molar extinction coefficient, c is the sample concentration, and d is the length of the sample layer. Here, when the excitation fluorescence wavelength and the apparatus conditions are kept constant, e and φf are values peculiar to the sample, and these values are irrelevant in the same sample, which is expressed as If = kc, and the fluorescence intensity becomes relative. Expressed as strength.

However, the quality of the terephthalic acid used, the polycondensation method, the polycondensation apparatus and the polycondensation conditions, or the drying method, the drying apparatus and the drying conditions affect the fluorescence emission intensity of the polyester resin, and especially industrial continuous production. When the test was performed, it was found that there was a large tendency that the fluorescence emission intensity increased and that chips having different fluorescence emission intensity and fluorescence spectrum were mixed. This tendency is remarkable when continuous production is performed by a batch-type melt polycondensation apparatus or a subsequent batch-type solid-state polymerization apparatus. Therefore, it is important to maintain a normal fluorescence emission intensity and to obtain a polyester resin under conditions sufficient to minimize or minimize polyesters having different fluorescence emission intensities and different fluorescence spectra as much as possible. The method is described below. The reason for the increase in fluorescence emission intensity of polyester resin and the mixture of chips with different fluorescence emission intensity and fluorescence spectrum are as follows. The resin itself or organic substances incorporated in the resin are thermally oxidized and decomposed, resulting in a trace amount of fluorescent substance. Is considered to be generated, but it is not certain, nor is it due to any cause.
The fluorescence emission intensity of the polyester resin and the increase in the fluorescence emission intensity are measured by the following method.

  The polyester resin of the present invention is excellent in transparency, has little change in transparency, prevents emission of fluorescent light upon irradiation with ultraviolet rays, does not easily cause mold contamination during molding, and has a crystallization control for the plug portion. It is a polyester resin that gives a molded article with excellent heat resistance, and has excellent heat resistance, mechanical properties, residual off-flavors, unpleasant odors, and excellent fragrance retention hollow molded articles, sheet-like materials, stretched films, or monofilaments. give. In particular, even when subjected to excessive drying before molding or the like, a molded article of the above-mentioned stable quality can be obtained.

Hereinafter, embodiments of the polyester resin of the present invention, a polyester resin composition comprising the same, and uses thereof will be specifically described.
The polyester resin of the present invention is a polyester resin obtained mainly from a terephthalic acid component and a glycol component, preferably a polyester resin containing at least 70 mol% of a structural unit obtained from a terephthalic acid component and a glycol component, and more preferably. Is a polyester resin containing at least 85 mol%, particularly preferably at least 95 mol%.

  Examples of the glycol component constituting the polyester resin of the present invention include aliphatic glycols such as ethylene glycol, 1,3-propylene glycol, and tetramethylene glycol, and oils such as cyclohexanedimethanol. And cyclic glycols.

  Examples of the dicarboxylic acid as a copolymer component used when the polyester resin is a copolymer include isophthalic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and 4,4′- Aromatic dicarboxylic acids such as diphenyl ether dicarboxylic acid, 4,4′-diphenyl ketone dicarboxylic acid and functional derivatives thereof, p-oxybenzoic acid, oxy acids such as oxycaproic acid and functional derivatives thereof, adipic acid, sebacic acid, Examples include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, and dimer acid and functional derivatives thereof, and alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, and cyclohexanedicarboxylic acid, and functional derivatives thereof.

  Glycols as copolymer components used when the polyester resin is a copolymer include diethylene glycol, 1,3-trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol. Aliphatic glycols such as methylene glycol, octamethylene glycol, decamethylene glycol, 2-ethyl-2-butyl-1,3-propanediol, neopentyl glycol, and dimer glycol; 1,2-cyclohexanediol; Alicyclic glycols such as 1,4-cyclohexanediol, 1,1-cyclohexane dimethylol, 1,4-cyclohexane dimethylol, 2,5-norbornane dimethylol, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4'-β-hydroxyeth Aromatic glycols such as (xylphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and alkylene oxide adduct of bisphenol A, polyethylene glycol, polybutylene And polyalkylene glycols such as glycols.

  Further, as the polyfunctional compound as a copolymer component used when the polyester resin is a copolymer, as the acid component, trimellitic acid, pyromellitic acid and the like can be mentioned, and as the glycol component, Glycerin and pentaerythritol can be mentioned. The amount of the above-mentioned copolymer component to be used must be such that the polyester resin substantially maintains a linear shape. Further, a monofunctional compound such as benzoic acid or naphthoic acid may be copolymerized.

  One preferred example of the polyester resin of the present invention is a polyester resin whose main constituent unit is composed of ethylene terephthalate, more preferably 70% by mole or more of ethylene terephthalate unit, and isophthalic acid as a copolymerization component. , 1,4-cyclohexanedimethanol, etc., and particularly preferably a polyester resin containing at least 90 mol% of ethylene terephthalate units.

  Examples of these polyester resins include polyethylene terephthalate (hereinafter abbreviated as PET), poly (ethylene terephthalate-ethylene isophthalate) copolymer, poly (ethylene terephthalate-1,4-cyclohexane dimethylene terephthalate) copolymer, (Ethylene terephthalate-dioxyethylene terephthalate) copolymer, poly (ethylene terephthalate-1,3-propylene terephthalate) copolymer, poly (ethylene terephthalate-ethylene cyclohexylene dicarboxylate) copolymer and the like.

  Another preferred example of the polyester resin of the present invention is a polyester resin whose main structural unit is composed of 1,3-propylene terephthalate, and more preferably a 1,3-propylene terephthalate unit. A polyester resin containing at least 70 mol%, particularly preferably a polyester resin containing at least 90 mol% of 1,3-propylene terephthalate units.

  Examples of these polyester resins include polypropylene terephthalate (PTT), poly (1,3-propylene terephthalate-1,3-propylene isophthalate) copolymer, and poly (1,3-propylene terephthalate-1,4-cyclohexanediphthalate). Methylene terephthalate) copolymer.

  Still another preferred example of the polyester resin of the present invention is a polyester resin whose main constituent unit is butylene terephthalate, and more preferably a copolymer containing at least 70 mol% of butylene terephthalate unit. It is a polyester resin, particularly preferably a polyester resin containing 90 mol% or more of butylene terephthalate units.

  Examples of these polyester resins include polybutylene terephthalate (PBT), poly (butylene terephthalate-butylene isophthalate) copolymer, poly (butylene terephthalate-1,4-cyclohexane dimethylene terephthalate) copolymer, (Butylene terephthalate-1,3-propylene terephthalate) copolymer, poly (butylene terephthalate-butylene cyclohexylene dicarboxylate) copolymer and the like.

  The above polyester resin can be basically produced by a conventionally known continuous melt polycondensation method or a continuous melt polycondensation-continuous solid state polymerization method. That is, in the case of PET, terephthalic acid is directly reacted with ethylene glycol and, if necessary, other copolymerization components to distill off water, esterify, and then carry out polycondensation under reduced pressure. Or a transesterification method in which dimethyl terephthalate is reacted with ethylene glycol and, if necessary, other copolymerization components to remove methyl alcohol and transesterify, followed by polycondensation under reduced pressure. Manufactured.

  Then, if necessary, the intrinsic viscosity may be increased, or the content of acetaldehyde or the content of a low cyclic trimer may be reduced, as in the case of a low-flavor beverage heat-resistant container or a film for the inner surface of a beverage metal can. Therefore, the melt-polycondensed polyester resin thus obtained is continuously subjected to solid-state polymerization.

Hereinafter, an example of a preferred continuous production method of the polyester resin of the present invention will be described with reference to polyethylene terephthalate as an example, but the production method of the polyester resin of the present invention is not limited thereto.
First, a case where a low polymer is produced by an esterification reaction will be described. A slurry containing 1.02 to 1.9 moles, preferably 1.03 to 1.7 moles of ethylene glycol per 1 mole of high-purity terephthalic acid or an ester derivative thereof was prepared, and the resulting slurry was esterified. Continuously supplied to the chemical reaction step.

  At this time, an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less is allowed to flow through the gas phase portion of the slurry preparation tank or the slurry storage tank, so that the raw material and It is desirable to remove oxygen mixed into the system together and to prevent air from being mixed. It is desirable that the oxygen concentration in the gas phase be maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less.

  In particular, high-purity terephthalic acid is usually in the form of a powder, and contains air between these particles and the like, and oxygen is introduced into the slurry preparation tank or slurry storage tank. It is desirable that the atmosphere in the atmosphere be an inert gas atmosphere having an oxygen concentration of 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less.

  In addition, since oxygen is also dissolved in ethylene glycol, ethylene glycol is previously bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less. It is also preferable that the slurry preparation tank and the slurry storage tank be subjected to bubbling with the above-mentioned inert gas after the slurry preparation.

  The esterification reaction is carried out in a single-stage apparatus consisting of one esterification reactor or a multi-stage apparatus in which at least two esterification reactors are connected in series, under the condition that ethylene glycol is refluxed, in a gas phase. An inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less is passed through the portion, and water or alcohol produced by the reaction is taken out of the system by a rectification column. Perform while removing. The oxygen concentration in the gas phase is preferably maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 10 ppm or less.

The temperature of the first-stage esterification reaction is 240 to 270 ° C, preferably 245 to 265 ° C, and the pressure is 0.2 to 3 kg / cm ² G, preferably 0.5 to ² kg / cm ² G. The temperature of the final esterification reaction is usually from 250 to 275 ° C, preferably from 255 to 270 ° C, and the pressure is usually from 0 to 1.5 kg / cm ² G, preferably from 0 to 1.3 kg / cm ² G. . When the reaction is carried out in three or more stages, the reaction conditions of the intermediate stage esterification reaction are those between the above-mentioned first stage reaction conditions and the last stage reaction conditions. The increase in the conversion of these esterification reactions is preferably distributed smoothly at each stage. Finally, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. A low-order condensate having a molecular weight of about 500 to 5,000 is obtained by these esterification reactions.

  When terephthalic acid is used as a raw material, the above esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst.

  Tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine; quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and trimethylbenzylammonium hydroxide; and lithium carbonate. When a small amount of a basic compound such as sodium carbonate, potassium carbonate or sodium acetate is added, the ratio of the dioxyethylene terephthalate component unit in the main chain of polyethylene terephthalate is relatively low (total amount). (5 mol% or less based on the diol component).

  Next, when a low polymer is produced by transesterification, 1.1 to 1.8 mol, preferably 1.2 to 1.6 mol, of ethylene glycol is contained per 1 mol of dimethyl terephthalate. The prepared solution is prepared and continuously supplied to the transesterification step.

  At this time, the oxygen concentration is 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, most preferably 1 ppm or less in the dimethyl terephthalate dissolution tank or the ethylene glycol solution dissolution tank thereof or the gas phase portion of the solution storage tank. It is preferable that an inert gas is allowed to flow to remove oxygen mixed into the system together with the raw materials so that air is not mixed at the same time. The oxygen concentration in the gas phase is preferably maintained at 100 ppm or less, more preferably 70 ppm or less, further preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less. It is also preferable that the dissolving tank is bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less.

  In particular, dimethyl terephthalate is usually in the form of powder or flakes, contains air between these particles and the like, and brings oxygen into the dissolution tank or storage tank. It is desirable that the atmosphere be an inert gas atmosphere of 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less.

  In addition, since oxygen is also dissolved in ethylene glycol, ethylene glycol is previously bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less. It is also preferable to bubble the dissolving tank and the storage tank with the above-mentioned inert gas after preparing the slurry.

  In the transesterification reaction, the oxygen concentration in the gas phase is 50 ppm or less, preferably 10 ppm or less under conditions in which ethylene glycol is distilled back using a device in which one or two transesterification reactors are connected in series. More preferably, the reaction is carried out by passing an inert gas of 5 ppm or less, most preferably 1 ppm or less, and removing methanol produced by the reaction outside the system by a rectification column. The oxygen concentration in the gas phase is preferably maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 10 ppm or less.

  The temperature of the first-stage transesterification reaction is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the final transesterification reaction is usually from 230 to 270 ° C, preferably from 240 to 265 ° C. As the transesterification catalyst, fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca and Ba, carbonates Or Pb, Zn, Sb, Ge oxide, or the like. A low-order condensate having a molecular weight of about 200 to 500 is obtained by these transesterification reactions.

As one of the methods for maintaining the fluorescence emission intensity (B ₀ ) of the polyester resin and the increase in the fluorescence emission intensity during the heat treatment (B _h −B ₀ ) within the above-mentioned target ranges, the raw materials as described above are used. It is a very important element to control the oxygen concentration of the gas phase of the preparation tank or the reactor within the above range, and as a result, it has excellent transparency, a stable crystallization rate, and excellent flavor retention. It is possible to obtain a polyester resin which gives a molded article or the like.

  The starting materials dimethyl terephthalate, terephthalic acid or ethylene glycol include dimethyl terephthalate of virgin derived from para-xylene, ethylene glycol derived from terephthalic acid or ethylene, and methanol decomposition from used PET bottles. Raw materials such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered by a chemical recycling method such as decomposition of ethylene glycol or ethylene glycol can also be used as at least a part of the starting materials. It goes without saying that the quality of the recovered material must be purified to a purity and quality according to the purpose of use.

  Next, the obtained low-order condensate is supplied to a multi-stage liquid-phase polycondensation step. The polycondensation reaction conditions are as follows: the first stage polycondensation reaction temperature is 250 to 285 ° C., preferably 260 to 280 ° C., and the pressure is 100 to 10 Torr, preferably 70 to 15 Torr. Is from 265 to 290 ° C., preferably from 275 to 285 ° C., and the pressure is from 5 to 0.01 Torr, preferably from 3 to 0.2 Torr. It is preferable to increase the degree of vacuum so that the polycondensation reaction proceeds at a temperature as low as possible and in a short time. The time for the polycondensation reaction is preferably 1 to 7 hours, and the temperature at 270 ° C. or higher is preferably within 5 hours. When the reaction is carried out in three or more stages, the reaction conditions for the polycondensation reaction in the intermediate stage are those between the above-mentioned first-stage reaction conditions and the last-stage reaction conditions. It is preferred that the degree of increase in intrinsic viscosity achieved in each of these polycondensation reaction steps be distributed smoothly.

  It is natural that the melt polycondensation reactor should be designed so that air leakage into the system from the design stage does not occur as much as possible.In addition, during the periodic overhaul such as during regular maintenance, the melt polycondensation reaction It is important to take measures to prevent air leakage under reduced pressure at the maximum. In particular, the effect of air leakage from the sealing part of the movable part such as a pump used for transportation between the stirring shaft and the reaction tank is large, and in addition to a sealing structure with little leakage, the oxygen concentration in the sealing part is preferably 5 ppm or less, preferably. It is preferable to flow an inert gas of 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less.

Further, in the second and subsequent stages of the polycondensation, particularly as the final stage polycondensation reactor, the retention of the polyester is small, and the polyester of the intermediate stage polymerization degree introduced into the reactor is sequentially polycondensed to form the final polycondensate. It is preferable to use a plug having high plug flowability discharged as a gas. For this purpose, it is preferable that the shape of the stirring blade is optimal and the rotation speed of the stirring blade is appropriately set, and a reactor equipped with a biaxial stirring blade is also preferable.
A one-stage polycondensation apparatus may be used for the polycondensation reaction.

  The polycondensation reaction is performed using a polycondensation catalyst. As the polycondensation catalyst, it is preferable to use at least one compound selected from Ge, Sb, Ti, and Al compounds. These compounds are added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, a slurry of ethylene glycol, and the like.

  These catalyst solutions, slurries, etc. are bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, most preferably 1 ppm or less, or at the same time. After bubbling with an inert gas, a similar inert gas is desirably circulated in the gas phase.

  Examples of the Ge compound include amorphous germanium dioxide, crystalline germanium dioxide powder or a slurry of ethylene glycol, a solution in which crystalline germanium was dissolved in water by heating, or a solution in which ethylene glycol was added thereto and heat-treated. In order to obtain the polyester resin used in the present invention, it is particularly preferable to use a solution obtained by heating and dissolving germanium dioxide in water or a solution obtained by adding ethylene glycol to the solution and heating. In addition to these, compounds such as germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite are exemplified. When a Ge compound is used, the amount of the Ge compound used is 10 to 150 ppm, preferably 13 to 100 ppm, more preferably 15 to 70 ppm as the amount of Ge remaining in the polyester resin.

  When germanium dioxide is used as the catalyst, the content of sodium or potassium or the total content of sodium and potassium of germanium dioxide is preferably 100 ppm or less, preferably 50 ppm or less, and more preferably 10 ppm or less. Further, the heating loss of germanium dioxide is preferably in the range of 1.5 to 15.0%, preferably 1.5 to 4.5%, and more preferably 1.5 to 4.0%.

  Examples of the Ti compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, and tetra-n-butyl titanate, and partial hydrolysates thereof, titanium acetate, titanyl oxalate, titanyl ammonium oxalate, titanyl oxalate. Sodium, titanyl potassium oxalate, titanyl calcium oxalate, titanyl oxalate compounds such as strontium titanyl oxalate, titanium trimellitate, titanium sulfate, titanium chloride, hydrolyzate of titanium halide, titanium oxalate, titanium fluoride, titanium hexafluoride Potassium oxide, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, a composite oxide composed of titanium and silicon or zirconium, Reaction products of Tan alkoxide and the phosphorus compound. The Ti compound is added so that the residual amount of Ti in the produced polymer is in the range of 0.1 to 50 ppm.

Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, antimony tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony.
The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 250 ppm.

  As the Al compound, specifically, aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, Carboxylates such as aluminum lactate, aluminum citrate, and aluminum salicylate; aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, polyaluminum chloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, and aluminum phosphonate Acid salt, aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide, aluminum Aluminum chelate compounds such as n-butoxide, aluminum t-butoxide, aluminum alkoxide, aluminum acetylacetonate, aluminum acetylacetate, aluminum ethyl acetoacetate, aluminum ethyl acetoacetate diiso-propoxide, and organic compounds such as trimethylaluminum and triethylaluminum. Aluminum compounds and their partial hydrolysates, aluminum oxide and the like can be mentioned. Of these, carboxylate, inorganic acid salt and chelate compound are preferred, and among these, basic aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, polyaluminum chloride and aluminum acetylacetonate are particularly preferred. preferable. The Al compound is added so that the residual amount of Al in the produced polymer is in the range of 5 to 200 ppm.

  In the method for producing a polyester resin of the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination. The alkali metal or alkaline earth metal is preferably at least one selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba. More preferred. When an alkali metal or a compound thereof is used, it is particularly preferable to use Li, Na, and K. Examples of the alkali metal or alkaline earth metal compounds include, for example, saturated aliphatic carboxylate such as formic acid, acetic acid, propionic acid, butyric acid, and oxalic acid, and unsaturated aliphatic carboxylate such as acrylic acid and methacrylic acid. Aromatic carboxylate such as benzoic acid, halogen-containing carboxylate such as trichloroacetic acid, hydroxycarboxylate such as lactic acid, citric acid, salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as oxyhydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid, and bromic acid; and organic sulfonic acid salts such as 1-propanesulfonic acid, 1-pentanesulfonic acid, and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butyl Alkoxides such as alkoxy, chelate compounds and the like acetylacetonate, hydrides, oxides, and hydroxides and the like.

  The above alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution or the like. The alkali metal compound or alkaline earth metal compound is added to the resulting polymer so that the remaining amount of these elements is in the range of 1 to 50 ppm.

  Furthermore, the polyester resin of the present invention contains a metal compound containing at least one element selected from the group consisting of silicon, manganese, iron, cobalt, zinc, gallium, strontium, zirconium, tin, tungsten and lead. You may.

  These metal compounds include saturated aliphatic carboxylate such as acetate of these elements, unsaturated aliphatic carboxylate such as acrylate, aromatic carboxylate such as benzoic acid, and halogen containing such as trichloroacetic acid. Carboxylates, hydroxycarboxylates such as lactates, inorganic salts such as carbonates, organic sulfonates such as 1-propanesulfonate, organic sulfates such as lauryl sulfate, oxides, hydroxides, chlorides And chelate compounds with alkoxide, acetylacetonate and the like, and are added to the reaction system as powder, aqueous solution, ethylene glycol solution, slurry of ethylene glycol and the like. These metal compounds are added so that the residual amount of the elements of these metal compounds is in the range of 0.05 to 3.0 mol per ton of the produced polymer. These metal compounds can be added at any stage of the polyester production reaction step.

In addition, various P compounds can be used in combination with the above-mentioned polymerization catalyst. Among the P compounds, it is particularly preferable to use a phosphorus compound having a phenol moiety in the same molecule.
The P compound is not particularly limited, but one or two selected from the group consisting of phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinous acid compounds, and phosphine compounds. It is preferable to use the above compounds. Among these, it is particularly preferable to use one or more phosphonic acid compounds. Among these phosphorus compounds, it is preferable to use a compound having an aromatic ring structure.

  Specific examples of the P compound used in the present invention include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, monophenyl phosphate, dimethyl phosphate, and phosphoric acid. Derivatives of phosphoric acid such as monobutyl ester and dibutyl phosphate; phosphorous acid derivatives such as phosphorous acid, trimethyl phosphite, triethyl phosphite and tributyl phosphite; methylphosphonic acid; dimethyl methylphosphonate Derivatives of phosphonic acids such as esters, dimethyl ethyl phosphonate, dimethyl phenyl phosphonate, diethyl phenyl phosphonate, diphenyl phenyl phosphonate, diphenyl phosphinic acid, diphenyl phosphite Methyl acid, diphenyl phosphinic acid, phenyl phosphinic acid, methylphenyl phosphinic acid, derivatives of phosphinic acids such as phenyl phosphinic acid.

  Phosphorus compounds having a phenol moiety in the same molecule, for example, p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonate, diethyl p-hydroxyphenylphosphonate, diphenyl p-hydroxyphenylphosphonate, bis (p-hydroxyphenylphosphonate) Phenyl) phosphinic acid, methyl bis (p-hydroxyphenyl) phosphinate, phenyl bis (p-hydroxyphenyl) phosphinate, p-hydroxyphenylphenylphosphinic acid, methyl p-hydroxyphenylphenylphosphinate, p-hydroxyphenylphenylphosphine Phenyl acid, p-hydroxyphenylphosphinic acid, methyl p-hydroxyphenylphosphinate, phenyl p-hydroxyphenylphosphinate, bis (p-hydroxyphenyl) phosphonate Fin oxide, tris (p- hydroxyphenyl) phosphine oxide, bis (p- hydroxyphenyl) methyl phosphine oxide and the like can be used.

Also, ethyl benzylphosphonate, benzylphosphonic acid, ethyl (9-anthryl) methylphosphonate, ethyl 4-hydroxybenzylphosphonate, ethyl 2-methylbenzylphosphonate, phenyl 4-chlorobenzylphosphonate, 4-aminobenzylphosphonic acid Methyl, ethyl 4-methoxybenzylphosphonate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate and the like can also be used.
Furthermore, metal salt compounds of phosphorus such as lithium [3,5-di-tert-butyl-4-hydroxybenzylphosphonate], sodium [3,5-di-tert-butyl-4-hydroxybenzylphosphonate] Ethyl], potassium [ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate], magnesium bis [3,5-di-tert-butyl-4-hydroxybenzylphosphonate], magnesium bis [3 , 5-di-tert-butyl-4-hydroxybenzylphosphonic acid], calcium bis [3,5-di-tert-butyl-4-hydroxybenzylphosphonate], calcium bis [3,5-di-tert-acid] Butyl-4-hydroxybenzylphosphonic acid], beryllium bis [3,5-di-tert-butyl-4-hydroxybenzylphosphonate] Methyl acid, strontium bis [3,5-di-tert-butyl-4-hydroxybenzylphosphonate], barium bis [3,5-di-tert-butyl-4-hydroxybenzylphosphonate] and the like are also used. it can.

  These may be used alone or in combination of two or more. The P compound can be added at any stage of the polyester production reaction step so that the residual amount of P in the produced polymer is in the range of 1 to 1000 ppm.

It is also preferable to add a hindered phenolic antioxidant.
As such a hindered phenol-based antioxidant, a known one may be used. For example, pentaerythritol-tetraextract [3- (3,5-di-tert-butyl-4-hydrid-3-) (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5- Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,9-bis {2- [3- (3-tert-butyl-4-hydroxy-5) -Methyl 3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,3,5- Lis (4-tert-butyl-3-hydroxy-2,6-dimethylbenzene) isophthalic acid, triethylglycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxy-3- (3-tert- Butyl-5-methyl-4-hydroxyphenyl) propionate), 1,6-hexanediol-bis [3- (3,3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 2 , 2-thio-diethylene-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl-3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5-di-tert- Methyl tyl-4-hydroxybenzylphosphonate, isopropyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, phenyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5- Octadecyl di-tert-butyl-4-hydroxybenzylphosphonate and 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid can be exemplified.

  In this case, the hindered phenol-based oxidation stabilizer may be bonded to the polyester, and the amount of the hindered phenol-based oxidation stabilizer in the polyester resin is preferably 1% by weight or less based on the weight of the polyester resin. . This is because if it exceeds 1% by weight, coloring may occur, and even if 1% by weight or more is added, the ability to improve the melt stability is saturated. Preferably, it is 0.02 to 0.5% by weight.

The above-mentioned metal compounds, stabilizers, antioxidants and the like are added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, a slurry of ethylene glycol, and the like.
These solutions or slurries are subjected to bubbling with an inert gas having an oxygen concentration of 50 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less, most preferably 1 ppm or less at the time of or after the preparation, or in the gas phase. It is desirable to pass a similar inert gas through the air.

The melt polycondensation polyester obtained as described above is formed into chips after the completion of the melt polycondensation, so that it can be kept in a molten state at a temperature as low as possible and for a short time until being extruded from the pores. is necessary. The holding conditions in the molten state after the completion of the melt polycondensation are as follows: the melting point or more and 290 ° C. or less, preferably 285 ° C. or less, more preferably 280 ° C. or less, for 20 minutes or less, preferably 15 minutes or less, more preferably 10 minutes or less. Within minutes, particularly preferably within 5 minutes, it is necessary to design piping and the like so as to quickly form a cooling chip after melt polycondensation. When staying at a high temperature of 290 ° C. or more for a long time of 20 minutes or more, the fluorescence emission intensity (B ₀ ) is 20 or less, and the increase in the fluorescence emission intensity (B _h −B ₀ ) after the heat treatment is 30 or less. However, the crystallization speed of the obtained molded article becomes too high, and the above-mentioned problem occurs, and at the same time, the flavor retention of the content may be deteriorated. When the polyester resin is left in the air for a long time even at a temperature lower than the melting point, the fluorescence emission intensity (B ₀ ) is 20 or less, and the increase in the fluorescence emission intensity after the heat treatment (B _h −B _0). ) May not be below 30 ° C., it is desirable to cool to about 100 ° C. or below as quickly as possible by the following method.

The melt polycondensation polyester obtained as described above has a chemical oxygen demand (COD) from the pores after the completion of the melt polycondensation of preferably 2.0 mg / l or less, more preferably 1.5 mg / l or less. More preferably, it is extruded into cooling water of 1.0 mg / l or less and cut in water, or extruded into the atmosphere and immediately cut while cooling with cooling water having the same COD value as above. Is done. Although the lower limit of the COD is not particularly limited, it is 0.01 mg / l in practical terms, and if it is less than 0.01 mg / l, the cost of equipment is high and economical chipping is not possible. May be possible. When the COD of the cooling water used in the chipping step exceeds 2.0 mg / l, the fluorescence emission intensity (B ₀ ) of the polyester resin is 20 or less, and the increase in the fluorescence emission intensity during the heat treatment ( B _h −B ₀ ) does not become 30 or less, and the crystallization speed of the obtained molded article becomes too fast, which causes the above-mentioned problem. At the same time, the flavor retention of the content may be deteriorated. It is.

Hereinafter, a method of reducing the COD in the cooling water in the chipping step will be described, but the present invention is not limited thereto.
In order to reduce the COD of new water introduced into the chipping process, a device that reduces the COD of water in at least one place before the industrial water is sent to the chipping process to supply it to the chipping process Install. Further, a device for reducing COD may be installed in at least one or more places in a process until water discharged from the chipping process is returned to the chipping process again. Examples of an apparatus for reducing COD include an apparatus for performing ultrafiltration, reverse osmosis filtration, coagulation sedimentation, activated sludge treatment, activated carbon treatment, and ultraviolet irradiation.
The temperature of the chip cooling water is preferably in the range of about 5 ° C. to about 40 ° C. from the viewpoint of the shape and fusion of the chips.

  In the present invention, the content of sodium (N), the content of magnesium (M), the content of silicon (S), and the content of calcium (C) as the cooling water in the chipping step are as follows: It is even more preferred that at least one of (4) to (4) be further formed into chips of the melt polycondensed polyester using cooling water that satisfies all requirements.

N ≦ 1.0 (ppm) (1)
M ≦ 0.5 (ppm) (2)
S ≦ 2.0 (ppm) (3)
C ≦ 1.0 (ppm) (4)

  The sodium content (N) in the cooling water is preferably N ≦ 0.5 ppm, and more preferably N ≦ 0.1 ppm. The magnesium content (M) in the cooling water is preferably M ≦ 0.3 ppm, more preferably M ≦ 0.1 ppm. Further, the content (S) of silicon in the cooling water is preferably S ≦ 0.5 ppm, and more preferably S ≦ 0.3 ppm. Further, the calcium content (C) in the cooling water is preferably C ≦ 0.5 ppm, and more preferably C ≦ 0.1 ppm.

  The lower limits of the sodium content (N), the magnesium content (M), the silicon content (S) and the calcium content (C) in the cooling water are not particularly limited, but in practical terms, N ≧ 0.001 ppm, M ≧ 0.001 ppm, S ≧ 0.02 ppm and C ≧ 0.001 ppm. In order to reduce the amount to less than the lower limit, enormous capital investment is required, and operating costs are extremely high, so that economical production may be difficult.

  When using cooling water that deviates from the above conditions, these metal-containing compounds adhere to the polyester resin chip surface, the crystallization speed of the obtained polyester resin is extremely fast, and the fluctuation thereof is unfavorably increased. . The content of the metal in the industrial water fluctuates considerably throughout the year, and the metal content adhering to the polyester resin fluctuates in accordance with this fluctuation, or at least one of the above (1) to (4) Compared to the case of using cooling water that satisfies one, the transparency of the molded body from the polyester resin obtained by using industrial water as the cooling water at the time of chipping is poor, and the fluctuation is very large . It is preferable that all of the above (1) to (4) are satisfied.

In addition, when solid-state polymerization of the melt-polycondensed polyester chipped while cooling using cooling water that deviates from the above-described conditions, the metal adhered to the chip surface in the chip-forming step and brought into the solid-state polymerization reaction device. The contained material adheres to the vessel wall of the solid-state polymerization apparatus together with a part of the surface layer of the polyester resin chip, and becomes a scale having a high metal content by prolonged heating at a high temperature of about 170 ° C. or more. It adheres to the vessel wall. Then, there is a case where a problem arises that this peels off from time to time and mixes into the polyester resin chip, which becomes a foreign matter in a molded product such as a bottle, thereby lowering the commercial value.
Further, when producing a sheet, the above-mentioned scale is clogged in the molten polymer filtration filter at the time of film formation, so that the filter-filtration pressure increases sharply, and the operability and productivity are deteriorated. May also occur.

A method for controlling the sodium content, magnesium content, silicon content, and calcium content of the cooling water of the chip within the above ranges will be described below, but the present invention is not limited thereto.
In order to reduce the amount of sodium, magnesium, calcium, and silicon in the cooling water, an apparatus for removing sodium, magnesium, calcium, and silicon is installed at at least one or more locations in the chip cooling step until industrial water is sent. In addition, a filter is installed in order to remove clay minerals such as silicon dioxide and aluminosilicate which have become particulate. Examples of an apparatus for removing sodium, magnesium, calcium, and silicon include an ion exchange apparatus, an ultrafiltration apparatus, and a reverse osmosis membrane apparatus.

  Further, it is desirable to use, as chip cooling water, water in which particles having a particle size of 1 to 25 μm existing in water introduced from outside the system are reduced to 50,000 particles / 10 ml or less. The number of particles having a particle size of 1 to 25 μm in the cooling water is preferably 10,000 particles / 10 ml or less, more preferably 1,000 particles / 10 ml or less. Particles having a particle diameter of more than 25 μm in the introduced water are not particularly limited, but are preferably 2000 particles / 10 ml or less, more preferably 500 particles / 10 ml or less, further preferably 100 particles / 10 ml, and particularly preferably 10 particles / ml. It is 10 ml or less.

Hereinafter, a method of controlling particles having a particle size of 1 to 25 μm to 50,000 particles / 10 ml or less in the introduced water to be introduced in the chipping step will be exemplified, but the present invention is not limited thereto.
As a method for reducing the number of particles in water to 50,000 particles / 10 ml or less, an apparatus for removing particles is installed at at least one or more points until natural water such as industrial water is supplied to the chipping step. Preferably, an apparatus for removing particles is installed from the natural water sampling port to the above-described chipping step, and the content of particles having a particle size of 1 to 25 μm in water supplied to the chipping step is adjusted. It is preferable that the concentration be 50000 particles / 10 ml or less. Examples of the device for removing particles include a filter filtration device, a membrane filtration device, a sedimentation tank, a centrifugal separator, and a foam entrainer. For example, in the case of a filter filtration device, a filtration device such as a belt filter system, a bag filter system, a cartridge filter system, and a centrifugal filtration system may be used. Above all, a belt filter system, a centrifugal filtration system, and a bag filter system are suitable for continuous operation. In the case of a belt-filter-type filtration device, examples of the filter medium include paper, metal, and cloth. Further, in order to efficiently remove particles and flow the introduced water, the size of the mesh of the filter is 5 to 100 μm, preferably 10 to 70 μm, and more preferably 15 to 40 μm.

  In addition, it is preferable to use the cooling water of the chips while repeatedly recycling them from the viewpoint of improving economic efficiency and productivity. During the cooling water recycling process, a filter, a temperature controller, a device for removing impurities such as acetaldehyde, and the like can be provided. Further, an apparatus for removing the particles, sodium, magnesium, calcium, and silicon may be provided.

Further, in the present invention, it is preferable to form chips by maintaining the dissolved oxygen concentration of cooling water used in the chip forming step from outside the system at about 45 cm ³ / l or less.
At the same time, the dissolved oxygen concentration ycm ³ / l of cooling water, if the temperature of the cooling water was set to X ° C., preferably logY ≦ 1.78-8.23 × 10 ^-3 X, more preferably logy ≦ 1 .73−8.23 × 10 ⁻³ X, more preferably logY ≦ 1.68−8.23 × 10 ⁻³ X, and most preferably logY ≦ 1.63−8.23 × 10 ⁻³ X. Fulfill.

In general, the oxygen solubility in water is about 38.0 cm ³ / l at 1 atmosphere and 10 ° C., and about 26.0 cm ³ / l at 30 ° C. However, when using industrial water having a low water temperature, for example, In the supersaturated state, oxygen is dissolved in excess of the solubility, or at the bottom of the storage tank, more oxygen is dissolved by the pressure due to the weight of water. In particular, when the chip cooling water is reused while being recycled as described above, low-molecular compounds such as monomers and oligomers dissolved in the cooling water due to the influence of oxygen such as supersaturation and organic compounds from outside the system. It is also conceivable that the oxidation reaction of impurities such as compounds progresses and the residual off-tastes and off-flavors increase. Further, it is considered that oxygen enters the resin chip and the chip easily emits fluorescence.

  Hereinafter, a method for reducing the dissolved oxygen concentration in water used as cooling water to the above value or less will be exemplified, but the present invention is not limited thereto. In order to suppress the dissolved oxygen concentration in the water used as the cooling water, at least one step in the process up to the supply as the cooling water, and to suppress the dissolved oxygen concentration in the water in the cooling water tank, Appropriate for reducing dissolved oxygen in at least one place during the process until the circulating water is discharged and returned to the cooling water storage tank again, and in the cooling tank to reduce the dissolved oxygen concentration in the cooling tank. It is preferable to install an appropriate device. Examples of a device for reducing dissolved oxygen include a degassing device for blowing an inert gas such as nitrogen gas or carbon dioxide gas, a vacuum heating degassing device, and a heating degassing device. Such a device can also be used in the case of water treatment described below.

  In addition, after extruding the polyester melt into the atmosphere from the pores of the die after melt polycondensation, and then chipping by cutting while cooling with cooling water, the inert gas exits from the pores of the die. It is also preferable that oxygen is not adsorbed to the high-temperature resin before the molten polymer is sprayed and comes into contact with cooling water. The oxygen concentration of the inert gas to be blown is 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less.

  In the case of employing a method in which the cooling water is sprayed onto the molten resin in a shower form to cool the oxygen, the oxygen is dissolved in the cooling water and the dissolved oxygen concentration increases, so that the oxygen concentration in the gas phase in the cooling step is 500 ppm or less. It is preferably maintained at 300 ppm or less, more preferably at 100 ppm or less, still more preferably at 50 ppm or less, most preferably at 10 ppm or less, and its fluctuation range is preferably kept within 30%, preferably within 20%. As a method for controlling the oxygen concentration in the gas phase in the cooling step, it is preferable to flow an inert gas sprayed on the molten polymer to the cooling step as it is.

Still further, in the method for producing a polyester resin of the present invention, the attached moisture of the molten polycondensed polyester resin chip obtained in the chipping step is preferably 3000 ppm or less, more preferably 2500 ppm or less, and still more preferably 2000 ppm or less. preferable. When the attached moisture exceeds 3000 ppm, when such a polyester resin chip is subjected to a drying treatment or a solid-phase polymerization treatment, the fluorescence emission intensity (B ₀ ) is 20 or less, and the fluorescence emission intensity during the heat treatment is reduced. it may increase (B _h -B ₀₎ to difficult to maintain the 30 following Do re problems. The attached water is measured using a trace moisture meter (model: CA-06 / VA-06) manufactured by Mitsubishi Chemical Corporation. As a method of reducing the attached water to 3000 ppm or less, a centrifugal separation method, a vibration method, or a method of spraying a heated gas when water is removed from the chip is often used, but it can be achieved by strengthening these operating conditions. .

  When the molten polycondensed resin is used as it is for molding or the like, the polyester chips whose adhering moisture is reduced to 3000 ppm or less after chipping are sent to a drying step and dried. Also, during the period from the cooling to the drying step, the oxygen concentration in the gas phase is maintained at 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less. Is desirable.

The drying temperature is from about 50C to about 150C, preferably from about 60C to about 140C, and the drying time is from about 3 hours to about 30 hours, preferably from about 4 hours to 20 hours. Particularly preferably, it is 4 hours to 15 hours.
As the dry gas, an inert gas having a dew point of -25 ° C or less and an oxygen concentration of 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less is preferable.

The inert gas used in the above includes nitrogen gas, carbon dioxide gas, helium gas and the like, and nitrogen gas is most convenient.
However, if the use of an inert gas is problematic in terms of economics, the dew point is −25 ° C. or less, the SOx is about 0.01 ppm or less, and the NOx is about 50 ppm using dehumidified air of about 0.01 ppm or less. Drying at a temperature of from about 100C to about 100C for a time of from about 3 hours to about 10 hours is also possible. In this case, it is necessary to suppress the fluorescence emission intensity by making other conditions strict. As a means for removing SOx and NOx from the air, an activated carbon filter, a filter containing metal particles having a catalytic action, or the like can be used.

  If the various drying conditions are out of the above ranges, the fluorescence emission characteristics of the polyester resin may be deteriorated, which is very likely to cause a problem.

  It is also important that the drying apparatus has no dead space in which abnormally shaped products such as chips and fines may stay for a long time. If there is a dead space, a chip or the like that has stayed there for a long time may have a problem in that the fluorescence emission characteristics may be deteriorated.

  In the drying apparatus, it is preferable that the introduced resin is sequentially discharged. When an average residence time of the resin is t, 95 wt%, preferably 98 wt% between 0.9 t and 1.1 t. It is more preferable that the apparatus discharges 99% by weight of the resin. As these devices, with a vertical hopper type dryer, the angle of the apex angle of the inverted cone portion at the bottom where the outlet of the dried chips is installed is set to an angle appropriately obtained from the angle of repose of the chips. In addition, it is preferable to use a baffle cone or a horizontal dryer in which a transport paddle or a disc is installed on a rotating shaft to enhance plug flow.

  If the chips are not discharged smoothly and there is a dead space, the heat history of a chip or the like that has stayed there for a long period of time will increase, and if this chip is mixed, the fluorescent light emission characteristics may worsen, which may be a problem. High.

  Next, in the case of solid-phase polymerization, the obtained melt polycondensed polyester chip has an oxygen concentration of 100 ppm or less, preferably 50 ppm or less, more preferably 30 ppm or less, most preferably 10 ppm or less under an inert gas atmosphere. It is preferable that the polyester is continuously solid-phase polymerized in order to reduce the acetaldehyde content and increase the intrinsic viscosity following the melt polycondensation by temporarily transporting it to a storage tank. First, the polyester subjected to solid-phase polymerization is pre-crystallized under an inert gas or under an atmosphere of water vapor or an inert gas containing water vapor, and subsequently dried to a moisture content of about 10 ppm (hereinafter referred to as pre-crystallization-drying). Is referred to as pre-crystallization). First, by pre-crystallization before completely drying, it is considered that penetration of oxygen into the resin is blocked, and the resin is less susceptible to oxygen during subsequent drying.

  The temperature during the pre-crystallization is preferably 180 ° C. or lower, more preferably 175 ° C. or lower, and even more preferably 170 ° C. or lower, and the lower limit of the temperature is preferably 100 ° C. or higher, more preferably 120 ° C. or higher. The time for the crystallization step is preferably 5 hours or less, more preferably 4 hours or less, even more preferably 3.5 hours or less, and the lower limit is 0.5 minutes or more, more preferably 1 minute or more. If the temperature during pre-crystallization is increased, the time must be shortened, and if the time is increased, the temperature must be decreased. For example, it is preferably about 2 hours at 180 ° C., about 3 hours at 160 ° C., and about 3.5 hours at 150 ° C.

  At this time, the oxygen concentration in the inert gas atmosphere is preferably 50 ppm or less, preferably 40 ppm or less, more preferably 30 ppm or less, still more preferably 20 ppm or less, and most preferably 10 ppm or less.

  Next, solid-state polymerization is performed in an inert gas atmosphere having an oxygen concentration of preferably 50 ppm or less, more preferably 40 ppm or less, still more preferably 30 ppm or less, and most preferably 20 ppm or less. Cooling is performed in an active gas atmosphere so that the chip temperature becomes about 60 ° C. or less. The upper limit of the solid-state polymerization temperature is preferably 220 ° C. or lower, more preferably 215 ° C. or lower, particularly preferably 210 ° C. or lower, and the lower limit is 190 ° C. or higher, preferably 195 ° C. or higher. The solid phase polymerization time depends on the desired degree of polymerization, but is preferably 30 hours or less, more preferably 15 hours or less, further preferably 10 hours or less, particularly preferably 8 hours or less, and most preferably 7 hours or less. It is. Also in solid-state polymerization, when the temperature is high, the time must be shortened, and when the solid-state polymerization is performed for a long time, the temperature must be set low, and excessive temperature and time history must be avoided. As a guide, it is about 20 hours or less at 210 ° C. and about 25 hours or less at 205 ° C. It is necessary to adjust the degree of pressure reduction, increase the flow rate of the inert gas, or increase the specific surface area of the polyester chip shape so that the solid phase polymerization is completed at a relatively low temperature and in a short time. is there.

  If the oxygen concentration in the inert gas exceeds 50 ppm during the pre-crystallization and during the solid-phase polymerization, and if the temperature and the time are longer than necessary, the fluorescence emission characteristics may deteriorate, which is not preferable.

Further, the storage of the melt polycondensation chip before the solid phase polymerization is limited to a maximum of 10 days even under the above-mentioned conditions, and it is desirable to keep the chip as short as possible. Solid state polymerization of the molten polycondensed polyester after standing in air for a long time must be avoided.
However, when the melt polycondensation reaction device and the solid-state polymerization device are directly connected and operated continuously, if the storage of the melt polycondensation polymer is within one day, the fluorescence of the solid-state polymerization polyester obtained even under atmospheric storage is obtained. It is also possible not to affect the light emission characteristics.

  In addition, the inert gas discharged from each step in the present invention removes solid substances such as monomers, water, ethylene glycol, and volatile compounds such as aldehydes by appropriate equipment, and fresh inert gas. The oxygen concentration can be reduced as described above by mixing with a gas or contacting with an oxygen scavenger, and can be reused.

  Furthermore, during pre-crystallization or solid-state polymerization, it is necessary to reduce long-term residence of polyester chips. If the polyester chips remain, some of the chips may have a heat history that is more than necessary, and the fluorescence emission characteristics may be deteriorated as a whole. For this purpose, it is important that the precrystallization apparatus and the solid-phase polymerization apparatus have no dead space in which abnormal shaped products such as chips and fines may stay for a long time. In a pre-crystallization or solid-phase polymerization apparatus, it is preferable to adopt a structure in which the introduced resin is sequentially discharged. If the average residence time of the resin is t, 95 wt% is between 0.9 t and 1.1 t. Preferably, the apparatus discharges 98% by weight, more preferably 99% by weight of resin. It is preferable to use the above-mentioned apparatus as the pre-crystallization apparatus. The solid-state polymerization apparatus is a vertical hopper-type solid-state polymerization reactor. The angle of the apex angle of the inverted conical part at the bottom where the outlet of the chip subjected to solid-state polymerization is installed is determined by the angle of repose of the chip. It is preferable that the angle be determined more appropriately, and a system in which accessory equipment such as a baffle cone or the like is installed at the chip outlet to prevent the chip from coming off is used.

If the chips are not discharged smoothly and there is a dead space, the chip or the like that has stayed there for a long time has a large thermal history. When this chip is mixed, the fluorescence emission intensity (B ₀ ) exceeds 20, and the heat treatment The amount of increase in the fluorescence emission intensity (B _h −B ₀ ) can be as high as more than 30, which is very likely to cause a problem.
The inert gas used in the above includes nitrogen gas, carbon dioxide gas, helium gas and the like, and nitrogen gas is most convenient.

  The limiting viscosity of the polyester resin of the present invention, especially the polyester resin whose main repeating unit is composed of ethylene terephthalate, is 0.55 to 2.00 deciliter / gram, preferably 0.60 to 1.50 deciliter / gram. G, more preferably from 0.65 to 1.00 deciliter / gram, and most preferably from 0.65 to 0.90 deciliter / gram. If the intrinsic viscosity of the polyester resin is less than 0.55 deciliter / gram, the mechanical properties of the obtained molded article and the like are poor. When the intrinsic viscosity of the polyester resin exceeds 2.00 deciliters / gram, the resin temperature rises during melting by a molding machine or the like, and thermal decomposition becomes severe, and free low-molecular-weight compounds that affect the fragrance retention properties are reduced. There are problems such as an increase in the number and an increase in the color of the molded body to yellow.

  The limiting viscosity of the polyester resin of the present invention, particularly the polyester resin whose main constituent unit is composed of 1,3-propylene terephthalate, is 0.50 to 2.00 deciliter / gram, preferably 0.55 to 2.00 deciliter / gram. It is in the range of 1.50 deciliter / gram, more preferably 0.60 to 1.00 deciliter / gram. If the intrinsic viscosity is less than 0.50 deciliters / gram, there is a problem that the obtained fiber has poor elastic recovery and durability. The upper limit of the intrinsic viscosity is 2.00 deciliters / gram. If it exceeds this, the resin temperature rises during melt spinning and the thermal decomposition becomes severe, the molecular weight decreases drastically, and the color is yellow. The problem arises.

  The polyester resin of the present invention has a color b value increase of 4 or less, more preferably 3.5 or less, still more preferably 3.0 or less, and most preferably, when the polyester resin is heat-treated at a temperature of 180 ° C. for 10 hours. It is preferably 2.0 or less. If the increase in the color b value after the above-mentioned heat treatment exceeds 4, the hue of the obtained molded article or the like becomes very yellow, which is problematic.

The density of chips of the polyester resin of the present invention, particularly the polyester resin whose main repeating unit is composed of ethylene terephthalate and which has been subjected to crystallization or solid-state polymerization treatment, has a density of 1.37 g / cm ³ or more, preferably It is preferably from 1.38 to 1.43 g / cm ³ , more preferably from 1.39 to 1.42 g / cm ³ .

  The content of the dialkylene glycol copolymerized in the polyester resin of the present invention is preferably 0.5 to 7.0 mol%, more preferably 1.0 to 6 mol% of the glycol component constituting the polyester resin. 0.0 mol%, more preferably 1.0 to 5.0 mol%. If the amount of the dialkylene glycol exceeds 7.0 mol%, the thermal stability becomes poor, the molecular weight is greatly reduced at the time of molding, and the content of aldehydes is undesirably increased. In order to produce a polyester resin having a dialkylene glycol content of less than 0.5 mol%, it is necessary to select uneconomic production conditions as transesterification conditions, esterification conditions or polycondensation conditions, Costs do not match. Here, the dialkylene glycol copolymerized in the polyester resin is, for example, in the case of a polyester resin whose main structural unit is ethylene terephthalate, diethylene glycol by-produced during production from ethylene glycol which is a glycol. Among them, diethylene glycol (hereinafter abbreviated as DEG) copolymerized with the polyester resin, and in the case of a polyester resin having 1,3-propylene terephthalate as a main structural unit, Among di (1,3-propylene glycol) (or bis (3-hydroxypropyl) ether) by-produced during production from 1,3-propylene glycol which is a glycol, the di ( 1,3-propylene glycol (hereinafter referred to as DPG).

  The amount of diethylene glycol copolymerized with the polyester resin of the present invention, particularly the polyester resin whose main repeating unit is composed of ethylene terephthalate, is 1.0 to 5.0 mol of the glycol component constituting the polyester resin. %, Preferably 1.3 to 4.5 mol%, more preferably 1.5 to 4.0 mol%. If the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability becomes poor, the molecular weight decreases during molding, and the acetaldehyde content and the formaldehyde content increase unfavorably. If the diethylene glycol content is less than 1.0 mol%, the transparency of the obtained molded article will be poor.

  It is desirable that the content of aldehydes such as acetaldehyde in the polyester resin of the present invention is 50 ppm or less, preferably 30 ppm or less, more preferably 10 ppm or less. In particular, when the polyester resin of the present invention is used as a material for containers for low-flavor beverages such as mineral water, the content of aldehydes in the polyester resin is 8 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less. It is desirable that: When the aldehyde content exceeds 50 ppm, the effect of retaining the flavor of the contents such as a molded article molded from the polyester resin becomes poor. Further, these lower limits are preferably 0.1 ppb in view of manufacturing problems. Here, the aldehydes are acetaldehyde when the polyester resin is a polyester resin having ethylene terephthalate as a main constituent unit, and is an aldehyde when the polyester resin is a polyester resin having 1,3-propylene terephthalate as a main constituent unit. Is allyl aldehyde.

Further, the content of the cyclic ester oligomer of the polyester resin of the present invention is 70% or less, preferably 60% or less, more preferably 50% or less of the content of the cyclic ester oligomer contained in the melt polycondensate of the polyester resin. And particularly preferably 35% or less.
The polyester generally contains cyclic ester oligomers having various degrees of polymerization, and the cyclic ester oligomer in the present invention is the cyclic ester oligomer having the highest content among the cyclic ester oligomers contained in the polyester. It means an oligomer. For example, in the case of polyester having ethylene terephthalate as a main repeating unit, it means a cyclic trimer.

  Further, the content of the cyclic trimer of the polyester resin of the present invention, particularly, the polyester resin whose main repeating unit is composed of ethylene terephthalate is 0.7% by weight or less, preferably 0.5% by weight or less. More preferably, it is at most 0.40% by weight. When a heat-resistant hollow molded article or the like is molded from the polyester resin of the present invention, heat treatment is performed in a heating mold. However, when the content of the cyclic trimer is 0.7% by weight or more, the heating mold is used. Adhesion of oligomers to the surface of the mold rapidly increases, and the transparency of the obtained hollow molded article or the like is extremely deteriorated.

  The shape of the chip of the polyester resin of the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape and the like, and the average particle size is usually 1.0 to 5 mm, preferably 1.1 to 4 mm. 0.5 mm, more preferably in the range of 1.2 to 4.0 mm. For example, in the case of a cylinder type, it is practical that the length is about 1.0 to 4 mm and the diameter is about 1.0 to 4 mm. In the case of spherical particles, it is practical that the maximum particle diameter is 1.1 to 2.0 times the average particle diameter and the minimum particle diameter is 0.7 times or more the average particle diameter. Further, the weight of the chip is practically in the range of 2 to 40 mg / piece.

  Further, when the polyester resin of the present invention is melted at a temperature of 290 ° C. for 60 minutes, the amount of the cyclic ester oligomer increased is preferably 0.50% by weight or less, more preferably 0.30% by weight or less, further more preferably. Is preferably 0.10% by weight or less. When the amount of the cyclic ester oligomer increased at a temperature of 290 ° C. for 60 minutes exceeds 0.50% by weight, the amount of the cyclic ester oligomer increases at the time of molding resin melting, and the oligomer adheres to the surface of the heating mold. It increases sharply, and the transparency of the obtained hollow molded article and the like becomes very poor.

  The polyester resin of the present invention, in which the amount of increase of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes is 0.50% by weight or less, is obtained by polycondensation of the polyester resin obtained after melt polycondensation or after solid phase polymerization. It can be produced by deactivating the catalyst. Examples of the method for deactivating the polycondensation catalyst of the polyester resin include a method of subjecting the polyester resin chip to contact treatment with water, steam or a steam-containing gas after melt polycondensation or after solid-phase polymerization.

  A method for treating the polyester resin chip with water, steam or a gas containing steam will be described below. In the present invention, the contact treatment of the polyester resin chip with water or steam is referred to as water treatment.

  Examples of the water treatment method include a method of immersing in water and a method of spraying water on a chip with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the temperature of water or steam is 20 to 180 ° C, preferably 40 to 150 ° C, more preferably 50-120 ° C.

  An example of a method for industrially performing water treatment is described below, but the method is not limited thereto. The treatment method may be either a continuous method or a batch method, but the continuous method is preferable for industrial use.

  In the case of treating the chips of the polyester resin with water in a batch system, a silo-type treatment tank may be used. That is, the chips of the polyester resin are received in a silo in a batch system and water treatment is performed. When the polyester resin chips are treated with water in a continuous manner, the polyester resin chips can be continuously or intermittently received in the tower-type treatment tank from above and subjected to water treatment.

In the case where polyester resin chips are industrially treated with water, natural water (industrial water) and wastewater are often reused because of the large amount of water used for the treatment. Normally, this natural water is collected from river water, groundwater, or the like, and is a water (liquid) that has been subjected to a treatment such as sterilization or removal of foreign matter without changing its shape. In general, natural water used industrially is derived from nature, inorganic particles and bacteria represented by clay minerals such as silicates and aluminosilicates, bacteria and the like, and originates from spoiled plants and animals. Contains a lot of organic particles. When water treatment is performed using these natural waters, particles adhere to and penetrate the polyester resin chips to form crystal nuclei, and the transparency of the hollow molded article using such polyester resin chips becomes extremely poor.
Therefore, regardless of whether the water treatment method is a continuous method or a batch method, the number of particles having a particle size of 1 to 25 μm existing in water introduced from outside the system is defined as X, sodium content. When the amount is N, the magnesium content is M, the calcium content C is silicon content, and at least one of the following (5) to (9) is satisfied, the water treatment is performed. desirable.

1 ≤ X ≤ 50,000 (pcs / 10ml) (5)
0.001 ≦ N ≦ 1.0 (ppm) (6)
0.001 ≦ M ≦ 0.5 (ppm) (7)
0.001 ≦ C ≦ 0.5 (ppm) (8)
0.01 ≦ S ≦ 2.0 (ppm) (9)

  By setting any of the number of particles in the water to be introduced into the water treatment tank and the content of sodium, magnesium, calcium, and silicon within the above ranges, metal-containing substances such as oxides and hydroxides called scales can be obtained. Floating and sedimentation in treated water, and also adhere to treatment tank walls and pipe walls, which adhere to and penetrate polyester resin chips, which promotes crystallization during molding, resulting in poorly transparent bottles Can be prevented.

  As a method for reducing the number of particles in the water introduced into the water treatment tank to 50,000 or less per 10 ml, an apparatus for removing particles is installed at at least one place in a process until natural water such as industrial water is supplied to the treatment tank. I do. These devices include devices similar to those used for the treatment of chip cooling water.

  In addition, in order to reduce sodium, magnesium, calcium, and silicon in the water introduced into the water treatment tank, at least one or more places of sodium, magnesium, calcium, and silicon are required in a process until natural water such as industrial water is supplied to the treatment tank. Install a device to remove the water. These devices include devices similar to those used for the treatment of chip cooling water.

Further, in the present invention, in the case of a continuous water treatment method, water treatment is performed while maintaining the dissolved oxygen concentration of the treated water introduced from outside the system and / or the treated water in the treatment tank at about 18 cm ³ / l or less, In the case of a batch system, it is preferable to carry out water treatment while maintaining the dissolved oxygen concentration of the treated water charged from outside the system and / or the treated water in the treatment tank at about 18 cm ³ / l or less.

At the same time, when the dissolved oxygen concentration of the treated water in the treated layer is Ycm ³ / l and the temperature of the treated water is X ° C., preferably Y ≦ 23.0−0.5.5 × 10 ⁻² X, More preferably, Y ≦ 22.5−0.5.5 × 10 ⁻² X, further preferably, Y ≦ 22.0−0.5.5 × 10 ⁻² X, and most preferably, Y ≦ 21.5-0. .5 × 10 ⁻² X is satisfied.

The oxygen solubility is for normal water, 1 atm, about 17.6cm ³ / l at 80 ° C., is a 17.2cm ³ / l approximately at 90 ° C., in the case of heating the water supersaturation without Kira omission oxygen Oxygen dissolves in excess of the solubility, and more oxygen is dissolved at the bottom of the treatment tank due to the pressure of its own weight. When the polyester resin chips left for a long time after the polycondensation are treated with water, the oxygen absorbed by the chips is released into the treated water and becomes supersaturated. In particular, when the water treatment is performed at a high temperature exceeding 80 ° C., the oxidation reaction of impurities such as monomers and oligomers dissolved in the water treatment tank progresses due to the influence of the temperature and oxygen such as supersaturation, resulting in residual off-flavor and off-flavor. Is thought to be stronger. Further, it is considered that oxygen enters the resin chip and the chip easily emits fluorescence.

The water introduced from outside the system may be directly introduced into the water treatment tank, or may be introduced into the water treatment tank after being mixed with the recycled water in the recycled water storage tank or the piping for sending the recycled water.
Regardless of whether the water treatment method is continuous or batchwise, if all or most of the treated water discharged from the treatment tank is converted into industrial wastewater, a large amount of fresh water is needed. There is a concern about the impact on the environment due to the increase in wastewater volume. That is, at least a part of the treated water discharged from the treatment tank is returned to the water treatment tank and reused, thereby reducing the required amount of water and reducing the effect on the environment by increasing the amount of wastewater. If the wastewater returned to the water treatment tank maintains a certain temperature, the heating amount of the treated water can be reduced.

  However, in the treated water discharged from the treatment tank, fine or film-like materials that have already adhered to the polyester resin chip at the stage of receiving the polyester resin chip into the treatment tank and have not been removed by the above-described water washing treatment, Fine or film-like materials of the polyester resin sometimes generated by friction between the chips of the polyester resin or between the processing tank walls.

  Therefore, when the treated water discharged from the treatment tank is returned to the treatment tank and reused, the content of fines and film-like substances contained in the treated water in the treatment tank gradually increases. For this reason, fine or film-like substances contained in the treatment water may adhere to the treatment tank wall or the pipe wall, and clog the pipe.

  Fine and film-like substances contained in the treated water adhere to the polyester resin chip again, and thereafter, at the stage of drying and removing moisture, the fine and film-like substance adheres to the polyester resin chip by an electrostatic effect. Therefore, it is difficult to remove fine or film-like substances after drying. Since this fine or film-like substance has a crystallization promoting effect, the crystallinity of the polyester resin is promoted, resulting in a bottle with poor transparency, or the crystallinity during crystallization of the plug portion becomes excessive, The dimensions of the plug part do not meet the standard, resulting in poor capping of the plug part.

  Therefore, in the present invention, after being discharged from the water treatment tank, at least a part thereof is returned to the treatment tank again, and particles having a particle size of 1 to 40 μm and having a particle size of 1 to 40 μm are 100000 particles / 10 ml or less. It is desirable to maintain it at 80,000 cells / 10 ml or less, more preferably, at 50,000 cells / 10 ml or less. Here, the treated water returned to the treatment tank and reused in this way is referred to as recycled water.

  A method for reducing the number of particles having a particle size of 1 to 40 μm in the recycled water to 100,000 / 10 ml or less will be exemplified below, but the present invention is not limited thereto. As a method for reducing the number of particles having a particle size of 1 to 40 μm in the recycle water to 100,000 particles / 10 ml or less, particles are treated at least in one or more places in a process until the treated water discharged from the treatment tank is returned to the treatment tank again. Install a device to remove. Examples of the device for removing particles include a filter-filtration device, a membrane filtration device, a sedimentation tank, a centrifugal separator, and a foam entrainer. For example, in the case of a filter-filtration device, examples of the type include a filter device such as an automatic self-cleaning system, a belt filter system, a bag filter system, a cartridge filter system, and a centrifugal filtration system. Of these, a belt filter system, a centrifugal filtration system, and a bag filter system are suitable for continuous operation. In the case of a belt-filter-type filtration device, examples of the filter medium include paper, metal, and cloth. The size of the mesh of the filter is 5 to 100 μm, preferably 5 to 70 μm, and more preferably 5 to 40 μm in order to efficiently remove the particles and flow the treated water.

In the case of treating by contacting the polyester resin chip with steam or a steam-containing gas, steam or a steam-containing gas at a temperature of 50 to 150 ° C., preferably 50 to 110 ° C., preferably steam, per 1 kg of the granular polyester resin, The granular polyester resin is supplied in an amount of 0.5 g or more, or is present, and is brought into contact with steam.
The oxygen concentration in these gases is preferably 50 ppm or less, preferably 10 ppm or less, and more preferably 5 ppm or less.
The contact between the polyester resin chip and water vapor is carried out usually for 10 minutes to 2 days, preferably for 20 minutes to 10 hours.

The method of industrially performing the contact treatment between the granular polyester resin and steam or a steam-containing gas will be exemplified below, but the method is not limited thereto. The processing method may be either a continuous method or a batch method.
When a chip of polyester resin is subjected to a contact treatment with steam in a batch system, a silo-type treatment device may be used. That is, the chip of the polyester resin is received in the silo, and the contact treatment is performed by supplying steam or a steam-containing gas in a batch system.

When the polyester resin chips are continuously subjected to the contact treatment with steam, the granular polyethylene terephthalate is continuously received from the top in a tower-type treatment device, and the steam is continuously supplied in parallel or countercurrent to contact treatment with the steam. be able to.
As described above, when treated with water or steam, the granular polyester resin is drained with a draining device such as a vibrating sieve or a simmon cutter, and is transferred to the next drying step as necessary.

  Drying of the polyester resin chips that have been subjected to the contact treatment with water or steam can be performed by using a commonly used polyester resin drying treatment. As a method of continuously drying, a hopper-type through-air dryer that supplies a polyester resin chip from the upper portion and allows the drying gas to flow from the lower portion is usually used.

As a dryer for drying in a batch system, drying may be performed while passing an inert gas dehumidified under atmospheric pressure.
The drying temperature is from about 50C to about 150C, preferably from about 60C to about 140C, and the drying time is from 3 hours to 15 hours, preferably from 4 hours to 10 hours.

  As the dry gas, an inert gas having a dew point of -25 ° C or less and an oxygen concentration of 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less is preferable.

The inert gas used in the above includes nitrogen gas, carbon dioxide gas, helium gas and the like, and nitrogen gas is most convenient.
However, since the use of an inert gas is problematic in terms of economy, the dew point is −25 ° C. or less, the SOx is about 0.01 ppm or less, and the NOx is about 50 ° C. using dehumidified air with about 0.01 ppm or less. Drying at a temperature of from about 100C to about 100C for a time of from about 3 hours to about 10 hours is also possible.

  In the drying apparatus, it is preferable that the introduced resin is sequentially discharged. When an average residence time of the resin is t, 95 wt%, preferably 98 wt% between 0.9 t and 1.1 t. It is more preferable that the apparatus discharges 99% by weight of the resin. As these devices, with a vertical hopper type dryer, the angle of the apex angle of the inverted cone portion at the bottom where the outlet for dried chips is installed is set to an angle appropriately obtained from the angle of repose of the chips, It is preferable to use a baffle cone or the like or a horizontal dryer having a transport paddle or a disk on a rotating shaft.

If it is not discharged smoothly and there is a dead space, the chip etc. that stayed there for a long time will have a large thermal history, and if this chip is mixed in, the fluorescent light emission characteristics may deteriorate, which may be a problem. Very high.
Further, when separating the polyester resin from water and thereafter, the gas that comes into contact with the polyester resin is preferably an inert gas having the same oxygen concentration as the gas at the time of drying or dehumidified air.

  If the various drying conditions are out of the above ranges, the fluorescence emission characteristics of the polyester resin may be deteriorated, which is very likely to cause a problem.

  It is also important that the drying apparatus has no dead space in which abnormally shaped products such as chips and fines may stay for a long time. If there is a dead space, a chip or the like that has stayed there for a long time may have a problem in that the fluorescence emission characteristics may be deteriorated.

As another means for deactivating the polycondensation catalyst, there is a method of inactivating the polycondensation catalyst by adding and mixing a phosphorus compound to the melt of the polyester after the melt polycondensation or after the solid phase polymerization.
In the case of the melt polycondensation polyester, the polyester resin after the completion of the melt polycondensation reaction and the polyester resin containing the phosphorus compound are mixed in a device such as a line mixer capable of mixing in a molten state, so that the polycondensation catalyst is not obtained. An activation method may be used.

  Examples of the method of blending the phosphorus compound with the solid-phase polymerized polyester resin include a method of dry blending the phosphorus compound with the solid-phase polymerized polyester resin, a polyester master batch chip in which the phosphorus compound is melt-kneaded and blended, and a solid-state polymerized polyester resin. A method in which a predetermined amount of a phosphorus compound is blended into a polyester resin by a method of mixing chips and then melted in an extruder or a molding machine to inactivate a polycondensation catalyst is exemplified.

  Examples of the phosphorus compound to be used include phosphoric acid, phosphorous acid, phosphonic acid and derivatives thereof. Specific examples include various phosphorus compounds used in the above-mentioned melt polycondensation step.

  Generally, a polyester resin contains a considerable amount of fine particles, that is, fines, which are generated during the production process and whose copolymer component content is the same as that of the polyester resin chips. Such fines have the property of accelerating the crystallization of the polyester resin, and when present in a large amount, the transparency of the polyester molded article molded from the polyester resin containing such fines becomes very poor. In the case of a bottle, the amount of shrinkage at the time of crystallization of the bottle plug portion does not fall within a specified value range, so that there is a problem that the bottle cannot be sealed with a cap. Therefore, the fine content of the polyester having the same composition as the polyester in the polyester resin of the present invention is 0.1 to 10000 ppm, preferably 0.5 to 1000 ppm, more preferably 1 to 500 ppm, and still more preferably 1 to 300 ppm. , Most preferably 1 to 100 ppm. When the compounding amount is less than 0.1 ppm, the crystallization speed becomes very slow, for example, the crystallization of the plug portion of the hollow molded container becomes insufficient, and the shrinkage amount of the plug portion is in the range of the specified value. It does not fit in the inside, capping is impossible, and the stretch heat-fixing mold for molding heat-resistant hollow molded containers is very dirty, so if you try to obtain a transparent hollow molded container, you must clean the mold frequently. No. On the other hand, when it exceeds 10,000 ppm, the crystallization speed becomes faster and the fluctuation of the speed becomes larger. Therefore, in the case of a sheet-like material, the transparency and the surface state deteriorate, and when it is stretched, the unevenness of the thickness deteriorates. Also, the crystallinity of the plug part of the hollow molded body becomes excessively large and fluctuates, so that the shrinkage amount of the plug part does not fall within the specified value range, and the cap part of the plug part becomes defective and leakage of contents occurs. In addition, the preform for hollow molding is whitened, which makes normal stretching impossible. In particular, the fine content of the polyester resin for a hollow molded body is preferably from 0.1 to 500 ppm.

  Further, such fine or film-like materials may include those having a melting point higher than the normal melting point by about 10 to 20 ° C. or more. When using a feeding device or a stirrer that applies shear force to the melt polycondensed polyester chip or solid state polymerized polyester chip or applies a shear force to the chip, the melting point is about 10 to 20 ° C. higher than the normal melting point. A very large amount of fine or film-like material is generated. This is presumably because the chip generates heat due to a large force such as an impact force applied to the chip surface, and at the same time, the oriented crystallization of polyester occurs on the chip surface, resulting in a dense crystal structure. If a polyester resin containing such a high melting point fine or the like is further subjected to solid phase polymerization or a contact treatment with water as described below, the melting point of the fine or the like may be further increased. When the polyester resin of the present invention is PET, fine or film-like materials having a melting point exceeding 260 ° C. to 265 ° C. may be problematic.

  In the present invention, the melting points of chips, fines and the like are measured by a differential scanning calorimeter (DSC) by the following method, and the melting peak temperature of the DSC is called the melting point. The melting peak representing this melting point is composed of one or more melting peaks. In the present invention, when there is one melting peak, the peak temperature and the melting peak are determined. In the case where there are a plurality of peaks, the highest melting peak temperature among the plurality of melting peaks is referred to as "the highest peak temperature of the fine melting peak temperature". In Examples and the like, it is referred to as “fine melting point”.

  Fine or film-like materials having such properties have the effect of further promoting the crystallization of the polyester resin, and when present in a large amount, the transparency of the obtained molded article becomes extremely poor, and sometimes, There is a possibility of causing a foreign matter-like defect whitened by crystallization.

  However, when trying to obtain a preform or sheet for hollow molding having good transparency and stretchability from a polyester resin or a polyester resin containing the high melting point fine or the like, for example, in PET, It must be melt molded at a high temperature of 300 ° C. or higher. However, at such a high temperature of 300 ° C. or more, the thermal decomposition of the polyester becomes intense, and a large amount of by-products such as aldehydes such as acetaldehyde is generated, and as a result, the flavor of the contents of the molded article and the like is obtained. Will have a significant effect on When the polyester composition of the present invention contains at least one resin selected from the group consisting of a polyolefin resin, a polyamide resin, and a polyacetal resin as described below, these resins are generally used as the polyester of the present invention. Since the thermal stability is often inferior to that of the resin, in the molding at a high temperature of 300 ° C. or more, as described above, a large amount of by-products is generated due to thermal decomposition. It will have a greater effect on flavor and the like.

  A specific example of a method for preventing the polyester resin of the present invention from containing such fines will be described below. In the case of melt polycondensation polyester, after melt polycondensation, the molten polyester is extruded into water from a die and cut in water, or extruded into the atmosphere and immediately cut into chips while cooling with cooling water. After draining the polyester chips formed into chips, the vibrating sieve process, the airflow classification process using a gas stream, or the washing process is used to remove chips, fines and film-like objects other than the specified size, and then use the plug transport method or bucket. It is sent to a storage tank by a conveyor system.

  Chips are extracted from the tank by a screw type feeder, and transported to the next step by a plug transport system or bucket type conveyor transport system. Air flow classification is performed by an air flow immediately before or immediately after the contact processing step. Fine removal processing is performed by a process.

  Next, the melt polycondensation polyester which has been subjected to the above-mentioned fine or film-like material removal treatment is removed again by a gas stream classification step using an air stream immediately before the solid-state polymerization step, and the solid-state polymerization step is performed. throw into. When transporting the melt-polycondensed prepolymer chips to the solid-state polymerization facility or when sieving the polyester chips after the solid-phase polymerization, transporting the contact processing step or storage tank, etc., most of these transports Uses a plug transport method or a bucket type conveyor transport method, and uses a screw feeder to extract chips from the crystallization apparatus or solid-state polymerization reactor. Use a device that can minimize the impact with the like. In addition, even in these transport pipes and in the removal treatment of fines and films, the oxygen concentration is 100 ppm or less, preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, most preferably 10 ppm or less of inert gas. Preferably, it is used.

  Further, the polyester resin containing a chip that emits fluorescent light usually includes fine particles that emit fluorescent light to the same extent. The crystallization-promoting effect of such a luminescent fine particle is very large and causes various problems to the same extent or more, so that the content of such a fine particle should be reduced as much as possible. This is very important.

  The polyester of the present invention, particularly a polyester resin containing ethylene terephthalate as a main repeating unit, has a molded plate having a thickness of 5 mm obtained by injection molding and having a haze of 30% or less, and a thickness of 2 mm obtained by injection molding. It is desirable that the crystallization temperature (hereinafter, referred to as “Tc1”) of the test piece from the molded article at the time of temperature rise be in the range of 150 to 175 ° C. The haze of the formed plate is preferably 15% or less, more preferably 10% or less, and the crystallization temperature (Tc1) at the time of raising the temperature is preferably 153-173 ° C, more preferably 155-170 ° C. It is.

  When the haze of the molded plate exceeds 30%, the transparency of the obtained hollow molded article is deteriorated, and a problem may occur particularly in the case of a stretched hollow molded article. On the other hand, when Tc1 exceeds 175 ° C., the heating crystallization rate becomes extremely slow, and the crystallization of the plug of the hollow molded article becomes insufficient, which causes a problem of leakage of the contents. Further, when Tc1 is lower than 150 ° C., the transparency of the hollow molded article is reduced, which may cause a problem.

  The polyester resin of the present invention containing ethylene terephthalate as a main repeating unit has a dimensional change rate of 1.0 mm as measured by thermomechanical analysis (TMA) on a molded plate having a thickness of 3 mm obtained by injection molding. % To 7.0%, preferably 1.2% to 6.0%, and more preferably 1.3% to 5.0%.

  When the dimensional change rate is 1.0% or less, the transparency of the heat-resistant hollow molded container is reduced, and this is a problem particularly in a large-sized hollow molded container of 1.5 liter or more. In addition, manufacturing a polyester resin having a dimensional change rate of less than 1.0% involves many problems such as an increase in equipment cost and a very low productivity. If the dimensional change rate exceeds 7.0%, the rate of heat crystallization is low, so that the heat-resistant hollow molded body plug part shrinks greatly during the heat treatment, causing a problem of leakage of the contents. In addition, the productivity of the hollow molded container deteriorates, which is a problem. Also, in the case of vacuum forming of the sheet, the shrinkage after forming becomes large, and the opening property of the lid and the fitting property with the lid are deteriorated, which causes a problem.

  Here, the dimensional change rate of the molded product for specifying the polyester of the present invention was measured by a method described later using a thermomechanical analysis (TMA), type TMA4000S, manufactured by Mac Science Corporation.

  Further, 0.1 ppb to 50,000 ppm of at least one resin selected from the group consisting of a polyolefin resin, a polyamide resin, and a polyacetal resin may be added to the polyester resin of the present invention.

  The mixing ratio of the resin to the polyester resin composition is 0.1 ppb to 50000 ppm, preferably 0.3 ppb to 10000 ppm, more preferably 0.5 ppb to 1000 ppm, and still more preferably 0.5 ppb to 100 ppb. If the compounding amount is less than 0.1 ppb, the crystallization speed becomes very slow, and the crystallization of the plug portion of the hollow molded article becomes insufficient. The capping is poor because it does not fall within the value range, and the stretch heat-fixing mold for molding the heat-resistant hollow molded article is heavily contaminated, and the mold must be cleaned frequently to obtain a transparent hollow molded article. There must be. If the content exceeds 50,000 ppm, the crystallization rate becomes high, and the crystallization of the plug portion of the hollow molded article becomes excessive. As a result, the amount of shrinkage and shrinkage of the plug portion does not fall within the specified value range, resulting in poor capping. Leakage of the product may occur, and the preform for the hollow molded body may be whitened, so that normal stretching may not be possible. In the case of a sheet-like material, if it exceeds 50,000 ppm, the transparency becomes extremely poor, and the stretchability becomes poor, so that normal stretching is impossible, and only a stretched film having large thickness unevenness and poor transparency is obtained. May not be possible.

  Examples of the polyolefin resin include a polyethylene resin, a polypropylene resin, and an α-olefin resin. These resins may be crystalline or amorphous.

  As the polyethylene resin, for example, a homopolymer of ethylene, ethylene, propylene, butene-1, 3-methylbutene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene- 1 and other α-olefins having about 2 to 20 carbon atoms, and vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, styrene, and unsaturated epoxy compound. Polymers. Specifically, for example, ethylene homopolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-butene-1 copolymer such as ultra low / low / medium / high density polyethylene (branched or linear) 4-methylpentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer And an ethylene-based resin such as an ethylene-ethyl acrylate copolymer.

  Examples of the polypropylene resin include, for example, propylene homopolymer, propylene, ethylene, butene-1, 3-methylbutene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, and decene-. Copolymers with other α-olefins having about 2 to 20 carbon atoms such as 1 or vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters and styrene, or hexadiene And copolymers with diene such as octadiene, decadiene and dicyclopentadiene. Specific examples include propylene-based resins such as propylene homopolymer (atactic, isotactic, syndiotactic polypropylene), propylene-ethylene copolymer, and propylene-ethylene-butene-1 copolymer.

Examples of the α-olefin resin include homopolymers of α-olefins having about 2 to 8 carbon atoms, such as 4-methylpentene-1, and those α-olefins, ethylene, propylene, butene-1, 3-methylbutene- 1, pentene-1, hexene-1, octene-1, decene-1, and the like, and copolymers with other α-olefins having about 2 to 20 carbon atoms. Specifically, for example, butene-1 based resin such as butene-1 homopolymer, 4-methylpentene-1 homopolymer, butene-1-ethylene copolymer, butene-1-propylene copolymer, and the like; - methylpentene-1 and C ₂ -C ₁₈ copolymer of α- olefins, and the like.

  Examples of the polyamide resin include lactam polymers such as butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, ω-laurolactam, 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Aliphatic diamines such as aminocarboxylic acid polymers, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, undecamethylenediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine Diamine units such as alicyclic diamines such as 1,3- or 1,4-bis (aminomethyl) cyclohexane and bis (p-aminocyclohexylmethane), and aromatic diamines such as m- or p-xylylenediamine; , Glutaric acid, adipic acid, suberic acid, sebashi Aliphatic dicarboxylic acids such as acids, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, terephthalic acid, polycondensates with dicarboxylic acid units such as aromatic dicarboxylic acids such as isophthalic acid, and copolymers thereof. Specifically, for example, nylon 4, nylon 6, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, nylon 66, nylon 69, nylon 610, nylon 611, nylon 612, nylon 6T, nylon 6I , Nylon MXD6, nylon 6 / MXD6, nylon MXD6 / MXDI, nylon 6/66, nylon 6/610, nylon 6/12, nylon 6 / 6T, nylon 6I / 6T, and the like. These resins may be crystalline or amorphous.

Examples of the polyacetal resin include a polyacetal homopolymer and a copolymer. The polyacetal homopolymer has a density of 1.40 to 1.42 g / cm ^{3 as} measured by ASTM-D792 and a melt flow ratio measured at 190 ° C. and a load of 2160 g according to ASTM D-1238. Polyacetal having a (MFR) in the range of 0.5 to 50 g / 10 minutes is preferred.

The polyacetal copolymer has a density of 1.38 to 1.43 g / cm ³ measured by ASTM-D792 and a melt measured at 190 ° C. and a load of 2160 g by ASTM D-1238. A polyacetal copolymer having a flow ratio (MFR) in the range of 0.4 to 50 g / 10 minutes is preferred. Examples of these copolymer components include ethylene oxide and cyclic ether.

  The production of the polyester resin composition containing the polyolefin resin or the like is performed by directly adding and melting and kneading the resin such as the polyolefin resin to the polyester resin so that the content falls within the above range, or -In addition to a conventional method such as a method of melt kneading added as a batch, the resin, the polyester resin in the production step, for example, during melt polycondensation, immediately after melt polycondensation, immediately after pre-crystallization, during solid state polymerization, At any stage, such as immediately after solid-state polymerization, or in a process from the end of the production stage to the molding stage, for example, directly adding it as a granular material, or subjecting the polyester resin chip to flow conditions Or a method in which the mixture is mixed with the resin member, or a method in which the mixture is melted and kneaded after the contact treatment.

  Here, as a method of bringing the polyester resin chip into contact with the resin member under flow conditions, it is preferable that the polyester resin chip be brought into collision with the member within an air gap in which the resin member is present, Specifically, for example, immediately after melt polycondensation of polyester resin, immediately after pre-crystallization, immediately after solid-phase polymerization, etc., or during filling and discharging of a transport container in the transport stage of a polyester resin chip as a product, etc. Also, at the time of injection of the molding machine in the molding step of the polyester resin chip, a part of the pneumatic transport pipe, the gravity transport pipe, the silo, the magnet part of the magnet catcher or the like is made of the resin, or The polyester resin chip is transferred by lining or by installing the resin member such as a rod or a net in the transfer path. How to, and the like. The contact time of the polyester resin chip with the member is usually a very short time of about 0.01 second to several minutes, but a small amount of the resin can be mixed into the polyester resin.

  The polyester resin and the polyester resin composition of the present invention include a PET obtained by using a raw material such as dimethyl terephthalate or terephthalic acid obtained by purifying a used PET bottle by a chemical recycling method as at least a part of a starting material, or a used PET bottle. A PET bottle can be used by mixing it with flake-like PET or chip-like PET that has been purified and recovered by a mechanical recycling method.

  The polyester resin or polyester resin composition of the present invention can be preferably used as a hollow molding, a tray, a packaging material such as a biaxially stretched film, a metal can coating film, a fiber containing a monofilament, and the like. Further, the polyester resin or the polyester resin composition of the present invention can also be used as one constituent layer of a multilayer molded article, a multilayer film and the like.

  The polyester resin or polyester resin composition of the present invention can be used to form films, sheets, containers, and other packaging materials using a commonly used melt molding method. Further, the mechanical strength can be improved by stretching the sheet-like material comprising the polyester resin or the polyester resin composition of the present invention at least uniaxially. The stretched film made of the polyester resin or polyester resin composition of the present invention is obtained by subjecting a sheet-like product obtained by injection molding or extrusion molding to uniaxial stretching usually used for PET stretching, sequential biaxial stretching, and simultaneous biaxial stretching. It is formed using any of these stretching methods. Also, it can be formed into a reccup shape or a tray shape by pressure forming or vacuum forming.

  Prior to molding, the polyester resin or polyester resin composition of the present invention is usually dried, but the drying temperature is about 50 ° C to about 150 ° C, preferably about 60 ° C to about 140 ° C, and the drying time is about 1 hour to about 20 hours, preferably about 2 hours to 10 hours.

  As the dry gas, an inert gas having a dew point of −25 ° C. or less, an oxygen concentration of 100 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less, and most preferably 1 ppm or less is preferred. It is preferably within 30%, preferably within 20%.

The inert gas used in the above includes nitrogen gas, carbon dioxide gas, helium gas and the like, and nitrogen gas is most convenient.
However, since the use of an inert gas is problematic in terms of economy, the dew point is −25 ° C. or less, the SOx is about 0.01 ppm or less, and the NOx is about 50 ° C. using dehumidified air with about 0.01 ppm or less. Drying at a temperature of from about 100C to about 100C for a time of from about 3 hours to about 10 hours is also possible.

  It is also important that the drying apparatus has no dead space in which abnormally shaped products such as chips and fines may stay for a long time. If there is a dead space, a chip or the like that has stayed there for a long time may have poor fluorescence emission characteristics, which is very likely to cause a problem.

  As described above, means for achieving the present invention have been exemplified, but it is not necessary to satisfy these steps and not all conditions. When the fluorescence from the resin is strong, measures such as tightening the above conditions are appropriately performed to obtain a polyester within the scope of the present invention, which can be used.

In the following, specific production methods for various uses in the case of PET will be briefly described.
In producing a stretched film, the stretching temperature is usually from 80 to 130 ° C. The stretching may be uniaxial or biaxial, but is preferably biaxial in view of practical physical properties of the film. The stretching ratio is usually 1.1 to 10 times, preferably 1.5 to 8 times in the case of uniaxial stretching. In the case of biaxial stretching, it is usually 1.1 to 8 times in both the longitudinal and transverse directions. , Preferably in the range of 1.5 to 5 times. Further, the ratio of the vertical / horizontal magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film can be further heat-set to improve heat resistance and mechanical strength. The heat setting is usually performed under tension at 120 ° C. to 240 ° C., preferably 150 ° C. to 230 ° C., usually for several seconds to several hours, preferably for several tens seconds to several minutes.

  In producing the hollow molded article, a preform molded from the polyester resin or the polyester resin composition of the present invention is formed by stretch blow molding, and an apparatus conventionally used in PET blow molding can be used. . Specifically, for example, a preform is once molded by injection molding or extrusion molding, or after processing the plug portion and the bottom portion, and then reheated, and biaxial stretch blow molding such as a hot parison method or a cold parison method is performed. The law applies. In this case, the molding temperature, specifically, the temperature of each cylinder and nozzle of the molding machine is usually in the range of 260 to 300 ° C. The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction. The obtained hollow molded body can be used as it is, but in particular, in the case of beverages requiring heat filling, such as fruit juice beverages, oolong tea, etc., in general, further heat-setting treatment is performed in a blow mold and heat resistance is applied. It is used with imparting properties. The heat setting is generally performed at 100 to 200 ° C., preferably 120 to 180 ° C., for several seconds to several hours, preferably for several seconds to several minutes, under tension by compressed air or the like.

  Also, in order to impart heat resistance to the plug portion, the plug portion of the preform obtained by injection molding or extrusion molding is crystallized in a far infrared or near infrared heater installation oven, Alternatively, the plug portion is crystallized with the heater after the bottle is formed.

  The polyester resin or the polyester resin composition of the present invention, if necessary, known UV absorbers, antioxidants, oxygen scavengers, lubricants added from the outside and lubricants internally deposited during the reaction, lubricants released, Various additives such as a nucleating agent, a stabilizer, an antistatic agent, a dye, and a pigment may be blended.

  Further, when the polyester resin or the polyester resin composition of the present invention is used for film applications, in order to improve handling properties such as slipperiness, winding property, and blocking resistance, calcium carbonate and magnesium carbonate are contained in the polyester resin. Inorganic particles such as barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, and magnesium phosphate; organic salt particles such as terephthalate such as calcium and calcium oxalate, barium, zinc, manganese, and magnesium; and divinylbenzene; Inert particles such as crosslinked polymer particles such as homo- or copolymers of vinyl monomers of styrene, acrylic acid, methacrylic acid, acrylic acid or methacrylic acid can be contained.

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.
The method for measuring the main characteristic values will be described below.
(1) Intrinsic viscosity (IV) of polyester
It was determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

(2) Diethylene glycol content of polyester (hereinafter referred to as [DEG content])
It was decomposed by methanol and the amount of DEG was quantified by gas chromatography and expressed as a ratio (mol%) to the total glycol components.

(3) Content of cyclic trimer of polyester (hereinafter referred to as “CT content”)
After freeze-grinding the sample, the sample is dissolved in a mixed solution of hexafluoroisopropanol / chloroform, and further diluted by adding chloroform. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to a constant volume with dimethylformamide, and the cyclic trimer composed of ethylene terephthalate units was quantified by liquid chromatography.

(4) Acetaldehyde content of polyester (hereinafter referred to as "AA content")
A sample / distilled water = 1 g / 2 cc in a glass ampoule purged with nitrogen was sealed and subjected to extraction at 160 ° C. for 2 hours. After cooling, acetaldehyde in the extract was measured by high-sensitivity gas chromatography. The concentration was expressed in ppm.

(5) Increase of cyclic trimer when polyester is melted (ΔCT amount)
3 g of the dried polyester chip is placed in a glass test tube, and immersed in a 290 ° C. oil bath for 60 minutes in a nitrogen atmosphere to be melted. The amount of increase of the cyclic trimer at the time of melting is obtained by the following equation.
Cyclic trimer increase during melting (% by weight) =
Cyclic trimer content after melting (% by weight)-Cyclic trimer content before melting (% by weight)

(6) Measurement of color b and increase of color b value after heat treatment Measurement of color b value is performed by using a resin chip and a color difference meter (MODEL TC-1500MC-88 manufactured by Tokyo Denshoku Co., Ltd.). Done.
The increase in the color b value after the heat treatment is determined as the difference between the color b value of the chip heat-treated in (12) and the color b value of the unprocessed chip. The larger the b value, the stronger the yellow color.

(7) Measurement of Fine Content Approximately 0.5 kg of the resin is sieved with a wire mesh having a nominal size of 5.6 mm according to JIS-Z8801 (A) and a sieve equipped with a wire mesh having a nominal size of 1.7 mm (diameter 20 cm) (B) was placed on a sieve combined in two stages, and sieved at 1800 rpm for 1 minute with a rocking sieve shaking tow machine SNF-7 manufactured by Teraoka. This operation was repeated to sieve a total of 20 kg of the resin. However, when the fine content is small, the amount of the sample is appropriately changed.
The fines sieved under the sieve (B) are washed with a 0.1% aqueous solution of a cationic surfactant, then washed with ion-exchanged water, and collected by filtration through a G1 glass filter manufactured by Iwaki Glass Co., Ltd. Was. These were dried together with the glass filter in a dryer at 100 ° C. for 2 hours, cooled, and weighed. The same operation of washing and drying with ion-exchanged water was repeated again to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to obtain a fine weight. Fine content is the fine weight / the total resin weight sieved.

(8) Average Density of Polyester Chip, Density of Preform Plug, and Density Deviation of Plug The density was measured at 30 ° C. with a calcium nitrate / aqueous solution density gradient tube.
The plug density was determined as an average value of 10 samples crystallized by the method (11), and the plug density deviation was determined from these 10 values.

(9) Measurement of melting peak temperature of fine (melting point of fine) Measured using a differential scanning calorimeter (DSC), RDC-220, manufactured by Seiko Electronics Co., Ltd. Fines collected from the 20 kg of polyester by the method of (7) were freeze-pulverized, dried under reduced pressure at 25 ° C. for 3 days, and then used in a single measurement using a 4 mg sample at a heating rate of 20 ° C./min. The measurement is performed to determine the melting peak temperature on the highest side of the melting peak temperature. The measurement is performed on a maximum of 10 samples, and the average value of the melting peak temperature on the highest temperature side is obtained.

(10) Haze (haze degree%) and haze spots on a molded plate A sample was cut out from the body (thickness of about 0.45 mm) of the molded article (thickness 5 mm) and the hollow molded article (17) below. Measured with a haze meter, model NDH2000, manufactured by Nippon Denshoku Co., Ltd. Further, the haze of a molded plate (thickness: 5 mm) formed continuously 10 times was measured, and the haze unevenness of the molded plate was determined as follows.

Molded plate haze unevenness (%) = maximum haze value (%) − minimum haze value (%)

(11) Density increase due to heating of preform plug portion The preform plug portion was heat-treated for 180 seconds with a homemade infrared heater, and a sample was taken from the top surface to measure the density.

(12) Measurement of Fluorescence Emission Intensity of Polyester and Confirmation of Fluorescence Emission i) Method of Measuring Fluorescence Emission Approximately 5 to 6 grams of a sample chip taken out randomly was used for a solid sample measurement cell (inner diameter 24.5 mm, height: 24.5 mm) 12 mm), covered with a quartz glass plate, and mounted on a sample holder of a spectrofluorometer (Spectral Fluorometer, Model RF-540, manufactured by Shimadzu Corporation). Excitation light is incident at an angle of 45 degrees, the emitted fluorescence is taken out in a perpendicular direction, introduced into a spectroscope, and a fluorescence spectrum with a vertical axis intensity of 0 to 100 is measured under the following conditions. FIG. 3 shows a fluorescence spectrum of PET.

Measurement condition ABSCISSA SCALE (horizontal axis): × 2
ORDINATE SCALE ((vertical axis): × 4
SCAN SPEED (scanning speed): FAST
SENSITIVITY (sensitivity): LOW
EXCITATION SLIT (slit on excitation side) (nm): 5
EMISSION SLIT (slit on emission side) (nm): 5
EXCITATION WAVELENGTH (excitation light wavelength): 343 nm
EMISSION START WAVELENGTH (emission start wavelength): 350 nm
EMISSION END WAVELENGTH (emission end wavelength): 600 nm

A tangent line is drawn on the low wave number side and the high wave number side of the emission spectrum obtained for the sample chip by the above method, and the length A between the point (a) of the spectrum at 395 nm and the intersection point (b) of the perpendicular line lowered to the tangent line is shown. And the length B between the intersection (d) of the perpendicular drawn from the point (c) of the spectrum at 450 nm to the tangent is measured. A and B are represented by relative values when the length from the fluorescence emission intensity of 0 to 100 is set to 100, and the fluorescence emission intensity at 395 nm (A) and the fluorescence emission intensity at 450 nm (B). Replace with a new chip and measure five times to determine the average value. In actual measurement, the peak at 395 nm and the peak at 450 nm may be shifted by several nm. In this case, the value of the spectrum peak is used, and when no clear peak is recognized, the values of 395 nm and 450 nm are used.
The fluorescence emission intensities A and B of the non-heat-treated chip are represented as A ₀ and B ₀ , respectively.

ii) Fluorescence emission intensity of heat-treated polyester The increase in the fluorescence emission intensity can be determined by measuring the fluorescence spectrum of the polyester chip heat-treated by the method (13) in the same manner, and measuring the fluorescence emission intensity of the heat-treated chip at 395 nm ( A _h ), the fluorescence emission intensity at 450 nm (B _h ).

iii) Screening of fluorescent chips (for measurement of B _S0 , A _S0 , B _Sh , A _Sh )
A black light (National FL20S.BL-B, 20W, emits near-ultraviolet light of 300 to 400 nm, maximum wavelength of 352 nm) is irradiated to about 500 g of the polyester chip which has not been heated or heat-treated by the method of (13), and is visually judged. Approximately 2-3 grams of chips are selected in the order of the intensity of the emitted fluorescence. This is pulverized by a freezing pulverizer (SPEX Freezer Mill), and about 1 g of the pulverized powder is packed in a solid sample measuring cell (inner diameter 24.5 mm, height 2 mm) in a dense state, and covered with a quartz glass plate. To be measured. When almost all of the chips emit the same amount of fluorescence when irradiated with black light, the measurement sample chip may be arbitrarily selected.

iv) Measurement of crushed chips (B _P0 , A _P0 , B _Ph , A _Ph )
Approximately 2-3 grams of the polyester chips unheated or heat-treated by the method of (13) are randomly removed, crushed with a refrigeration mill (SPEX Freezer Mill), and about 1 gram of the crushed powder is measured as a solid sample. The cells are packed in a dense state in a cell for use (inner diameter 24.5 mm, height 2 mm), covered with a quartz glass plate, and measured in the same manner.

v) Fluorescent characteristics The fluorescent emission characteristics in the examples are obtained by the following calculations.
Fluorescence emission intensity = B ₀
Fluorescence intensity ratio = B ₀ / A ₀
Increase in fluorescence emission intensity after heat treatment = B _h −B ₀
Fluorescence intensity ratio after heat treatment = _Bh / _Ah
Difference in fluorescence emission intensity ratio after heat treatment = B _h / A _h −B ₀ / A ₀
Fluorescence intensity ratio of sorting chip = B _S0 / A _S0
Increase in fluorescence emission intensity of chips selected after heat treatment = B _Sh −B _S0
Fluorescence emission intensity ratio after heat treatment of chips selected after heat treatment = B _Sh / A _Sh
Difference in fluorescence emission intensity ratio of crushed chips after heat treatment = B _Ph / A _Ph −B _P0 / A _P0
Fluorescence intensity ratio of crushed chip = B _P0 / A _P0

vi) Confirmation of fluorescence emission of polyester molded article The sample was irradiated with black light (National FL20S.BL-B, 20 W, emitting near-ultraviolet light of 300 to 400 nm, maximum wavelength 352 nm), and judgment was made visually.

(13) Heat treatment of polyester 20 grams of a sample dried under reduced pressure at 10 torr or less at about 80 ° C. for 8 hours is placed in a 100 ml glass container (inner diameter 41 mm, trunk outer diameter 55 mm, overall height 95 mm), and a gear manufactured by Nagano Kagaku Seisakusho Co., Ltd. It is placed on a turntable of a type aging tester NH-202GT and heat-treated at 180 ° C. for 10 hours in an air atmosphere.

(14) Crystallization temperature (Tc1) at the time of temperature rise of the molded body
Measured by RDC-220, a differential thermal analyzer (DSC) manufactured by Seiko-Electronic Industry Co., Ltd. A 10 mg sample from the center of a 2 mm thick plate of the molded plate of (16) below was used. The temperature was raised at a temperature rising rate of 20 ° C./min, and the apex temperature of the crystallization peak observed in the course of the heating was measured and defined as the crystallization temperature during temperature rise (Tc1).

(15) Dimensional change rate of molded product A test piece having a size of 8 mm x 10 mm was cut out from a plate portion having a thickness of 3 mm from the stepped molded plate of the following (16) to obtain a measurement sample. The formed plate has a molecular orientation derived from the flow during the forming process, and the orientation state varies depending on the portion of the formed plate. Therefore, the molding plate is sandwiched between two polarizing plates whose polarization planes are orthogonal to each other, and the orientation is observed by observing the intensity distribution of light passing through the molding plate when irradiating visible light from a direction perpendicular to the polarizing plate surface. I checked the status. A test piece was cut out from a portion where the molecular orientation did not include non-uniformity (such as the degree of orientation and fluctuation in the orientation direction) within the above dimensions. At this time, the orientation of the optical anisotropy is confirmed in advance, and the relationship with the orientation of the test piece to be cut out is as follows. The orientation of the optical anisotropy was determined by a method described in New Polymer Experimental Science 6 Polymer Structure (2) (Kyoritsu Shuppan Co., Ltd.) using a polarizing microscope and a sensitive color plate. The test piece was cut out so that the direction of the axis having a small refractive index (the axis at which the speed of light was high) was parallel to the long axis of the test piece. Alignment disturbances and irregularities on the cut surface, which are introduced when cutting out the test piece, significantly affect the measurement results. Therefore, the unevenness of the cut surface and the portion with disordered orientation were removed using a cutter to obtain a flat surface.

The density of the test piece and the degree of molecular orientation also affect the results. The values of density and birefringence should be 1.3345 to 1.3355 g / cm ³ and 1.30 × 10 ^{-4 to} 1.50 × 10 ^-4 respectively. The density was measured using a resin sampled from the vicinity of the test piece collection site as a sample and using a water-based density gradient tube. The birefringence was measured using a polarization microscope (ECLIPSE E600 POL, manufactured by Nikon Corporation) by the Berek compensator method. As the measured value, the value obtained at the center of the test piece was adopted. The dimensional change in the process of raising and lowering the temperature of the test specimen prepared as described above was measured by thermomechanical analysis (TMA) manufactured by Mac Science Co., Ltd., type TMA 4000S. The measurement was performed in a compression load mode, and a change in the sample length in a direction parallel to the long axis of the test piece was observed. The temperature of the sample was raised from room temperature to 210 ° C. at a rate of 27 ° C./min. Under a constant compressive load of 0.2 g and an Ar atmosphere, kept at 210 ° C. for 180 seconds, and then raised to room temperature by 47 ° C. / Min. And the dimensional change was measured. The following equation was used to calculate the dimensional change rate.

Dimensional change rate (%) =
100 × [(sample length before measurement at room temperature) − (sample length after measurement at room temperature)]
/ (Sample length before measurement at room temperature)

(16) Molding of Stepped Molding Plate In the molding of the stepped molding plate according to the present invention, a polyester chip which has been dried under reduced pressure at 140 ° C. for about 16 hours using a vacuum drying machine is an injection molding machine M- manufactured by Meiki Seisakusho Co., Ltd. As shown in FIGS. 1 and 2, a 150C-DM type injection molding machine has a gate portion (G) of 2 mm to 11 mm (A portion thickness = 2 mm, B portion thickness = 3 mm, C portion thickness = 4 mm, The thickness of the part D was 5 mm, the thickness of the part E was 10 mm, and the thickness of the part F was 11 mm).

  Using a polyester chip previously dried under reduced pressure using a vacuum dryer model DP61 manufactured by Yamato Scientific Co., a dry inert gas (nitrogen gas) purge was performed in the molding material hopper in order to prevent moisture absorption of the chip during molding. The plasticizing conditions of the M-150C-DM injection molding machine were as follows: feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, cylinder temperature 45 ° C., 250 ° C. from immediately below the hopper, and the nozzles thereafter. And 290 ° C. The injection conditions were such that the injection speed and the holding pressure were 20%, and the injection pressure and the holding pressure were adjusted so that the weight of the molded product was 146 ± 0.2 g. At that time, the holding pressure was 0.5 MPa lower than the injection pressure. It was adjusted.

The upper limits of the injection time and the dwell time are set to 10 seconds and 7 seconds, respectively, and the cooling time is set to 50 seconds. The total cycle time including the time for removing the molded product is about 75 seconds.
Cooling water having a water temperature of 10 ° C. is constantly introduced into the mold to control the temperature. The mold surface temperature during stable molding is about 22 ° C.
The test plate for evaluating the characteristics of the molded article was arbitrarily selected from among the stable molded articles at the 11th to 18th shots from the start of molding after the introduction of the molding material and the replacement of the resin.
The 2 mm thick plate (part A in FIG. 1) measures the crystallization temperature (Tc1) when the temperature is raised, the 3 mm thick plate (part B in the figure) measures the dimensional change rate, and the 5 mm thick plate (part D in FIG. 1). ) Is used for haze (haze percentage) measurement.

(17) Molding of Hollow Molded Article Assuming that excessive drying was performed, polyester was dried with a dryer using dehumidified air at normal pressure of 140 ° C. for 10 hours, and M-150C-DM manufactured by each machine was injected. The preform was molded at a resin temperature of 290 ° C. by a molding machine. The plug portion of this preform was heated and crystallized by a home-made plug portion crystallization apparatus. Next, the preformed body is biaxially stretched and blown at a magnification of about 2.5 times in a longitudinal direction and about 3.8 times in a circumferential direction by using an LB-01E molding machine manufactured by COPOPLAST, and then set at about 150 ° C. The container was heat-set in the mold for about 7 seconds to form a container having a capacity of 2000 cc (body thickness 0.45 mm). The stretching temperature was controlled at 100 ° C.

(18) Leakage evaluation of contents from hollow molded body The hollow molded body molded in (17) is filled with hot water at 90 ° C, capped by a capping machine, the container is turned down, and left to stand. Examined. Also, the deformation of the plug after capping was examined.

(19) Chemical oxygen demand (COD) (mg / l) of cooling water in chipping process
The cooling water filtered with a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd. is measured according to the method of JIS-K0101.

(20) Sodium content, calcium content, magnesium content and silicon content in the cooling water in the chipping process and the water introduced in the water treatment process The cooling water and the introduced water after particle removal and ion exchange have been collected, After filtration with a 1G1 glass filter manufactured by KK, the filtrate was measured with an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(21) Measurement of the number of particles in the cooling water in the chipping process, the introduced water in the water treatment process, and the recycled water In the cooling water after the particle removal and ion exchange, the introduced water, or the filtration device (5) and the adsorption tower (8) The treated recycled water was measured using PAC 150 (manufactured by Seishin Enterprise Co., Ltd.), which is a particle measuring device based on the light-blocking method, and the number of particles was indicated in units of 10 ml.

(22) Dissolved oxygen concentration Measured by the dissolved oxygen measurement method described in the section "24. Dissolved oxygen" of JIS-K0101 for industrial water test method. It is measured by any of the Winkle method, Winkle-sodium azide modified method, Miller modified method, or diaphragm electrode method. The water introduced from outside the system is supplied from the cooling water storage tank or the sampling port installed near the ion-exchanged water introduction port of the water treatment tank, and the treated water in the cooling water tank or water treatment tank is supplied to the respective water outlet. Collect from

(Example 1-1)
Using high-purity terephthalic acid and ethylene glycol as raw materials, PET was obtained by a continuous melt polycondensation apparatus and a continuous solid-state polymerization apparatus.
A slurry of high-purity terephthalic acid and ethylene glycol prepared in a slurry preparation tank is continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry is stirred at about 250 ° C. and 0 ° C. under stirring. The reaction was carried out at 0.5 kg / cm ² G for an average residence time of 3 hours.

The reaction product was sent to a second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm ² to a predetermined degree of reaction under stirring. As a polycondensation catalyst, crystalline germanium dioxide (sodium content: 0.7 ppm, potassium content: 0.5 pm, heat loss: 2.8%) is heated and dissolved in water, and ethylene glycol is added thereto. The addition heat-treated solution and the phosphoric acid ethylene glycol solution were separately and continuously fed to the second esterification reactor. In addition, a nitrogen gas having an oxygen concentration of 2 ppm or less is passed through the slurry mixing tank or each reactor, and the oxygen concentration in the gas phase of the slurry mixing tank is 20 to 30 ppm or less, and the first and second esterification reactors have an oxygen concentration of 20 to 30 ppm or less. The oxygen concentration in the gas phase was maintained at 20 to 30 ppm or less. A nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank.

  This esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 torr for 1 hour, and then is stirred at about 265 ° C. and 3 torr for 1 hour in the second polycondensation reactor. The mixture was polycondensed at about 275 ° C. and 0.5 to 1 torr for an additional hour and with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer was 0.54 dl / g.

The obtained melt polycondensation prepolymer is extruded from the pores into cooling water of about 20 ° C. having the following water quality, cut into water to form chips, and after centrifugal separation after solid-liquid separation, the water adhering to chips is reduced to about 800 ppm or less. . Approximately 500 particles having a particle size of 1 to 25 μm are obtained by treating industrial water (derived from underground river water) with a coagulating sedimentation device, a filter-filtration device, a nitrogen gas blowing heating degassing device, an activated carbon adsorption device and an ion exchange device. 10 ml, sodium content 0.06 ppm, magnesium content 0.03 ppm, calcium content 0.05 ppm, silicon content 0.11 ppm, COD 0.3 mg / l, dissolved oxygen about 28.0 cm ³ / l of introduced water is introduced into the cooling water storage tank in the chipping process, and the discharged water from the chipping process is adsorbed by a fine removal device, which is a 30 μm continuous filter made of paper, and ethylene glycol, etc. After being treated in the activated carbon adsorption tower, almost all of the water is returned to the cooling water storage tank, mixed with the introduced water, and used as cooling water. While continuously circulating this cooling water, the shortage is replenished with the above introduced water from outside the system and used as cooling water. The COD of the cooling water was 0.3-0.5 mg / l.

  Next, the chips are transported to a storage tank under a nitrogen atmosphere having an oxygen concentration of 50 ppm or less in the gas phase, and fines and film-like substances are subsequently removed by a vibrating sieving step and an airflow classification step, whereby fines are contained. The amount was about 50 ppm or less. This is sent to a crystallizer, and continuously crystallized at about 155 ° C. for 3 hours under a nitrogen gas flow having an oxygen concentration of 20 ppm or less, and then charged into a column-type solid-state polymerization device, and a nitrogen gas having an oxygen concentration of 15 to 20 ppm or less is introduced. Solid phase polymerization was continuously performed at about 209 ° C. under circulation to obtain a solid phase polymerized polyester. For pre-crystallization and solid-phase polymerization, a silo-type container was used, and the lower angle was set to 5 degrees larger than the repose angle of the resin, and a baffle cone was installed. After the solid-phase polymerization, the mixture was continuously processed in a sieving step and a fine removing step to remove fine and film-like substances. The oxygen concentration in the nitrogen gas discharged from the solid-state polymerization vessel was 25 ppm or less. In addition, a nitrogen gas having an oxygen concentration of 2 ppm or less was passed through a seal portion of a movable portion such as a stirrer or a pump of the melt polycondensation reactor and the solid-state polymerization reactor.

In addition, the molten polycondensation PET chip and the solid-phase polymerization PET chip were transported almost by a bucket-type conveyor transport method or a plug transport method, and a screw-type feeder was mainly used for extraction from a reactor or a storage tank. During the transportation in each step, a nitrogen atmosphere having an oxygen concentration of 30 to 50 ppm was used, and nitrogen gas having an oxygen concentration of 30 to 50 ppm was used for airflow classification.
Various evaluations were performed on the obtained PET by such a production method. The results are shown in Tables 1 and 2.

(Example 1-2)
PET was obtained using a continuous melt polycondensation apparatus and a continuous solid-state polymerization apparatus different from those in Example 1-1.
A slurry of high-purity terephthalic acid and ethylene glycol prepared in a slurry preparation tank is continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry is stirred at about 250 ° C. and 0 ° C. under stirring. The reaction was carried out at 0.5 kg / cm ² G for an average residence time of 3 hours. The reaction product was sent to a second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm ² to a predetermined degree of reaction under stirring. A catalyst obtained by heating and dissolving crystalline germanium dioxide (sodium content: 0.5 ppm, potassium content: 0.3 pm, weight loss by heating: 2.7%) in water, and adding ethylene glycol to the solution, followed by heat treatment. The solution and the phosphoric acid in ethylene glycol solution were separately fed continuously to the second esterification reactor. In addition, a nitrogen gas having an oxygen concentration of 1 ppm or less is passed through these mixing tanks and each reactor, the oxygen concentration in the gas phase of the slurry mixing tank is 20 to 30 ppm or less, and the first and second esterification reactors are used. The oxygen concentration in the gas phase of was maintained at 20 to 30 ppm or less. A nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank. This esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 torr for 1 hour, and then is stirred at about 265 ° C. and 3 torr for 1 hour in the second polycondensation reactor. The mixture was polycondensed at about 275 ° C. and 0.5 to 1 torr for an additional hour and with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer was 0.54 dl / g.

The obtained molten polycondensation prepolymer is extruded from the pores into cooling water of about 20 ° C. having the following water quality, cut in water to form chips, and after centrifugation after solid-liquid separation, the water adhering to chips is reduced to about 900 ppm or less. . Approximately 700 particles having a particle size of 1 to 25 μm, obtained by treating industrial water (derived from underground river water) with a coagulating sedimentation device, a filter-filtration device, a nitrogen gas blowing heating degassing device, an activated carbon adsorption device and an ion exchange device. 10 ml, sodium content 0.06 ppm, magnesium content 0.03 ppm, calcium content 0.02 ppm, silicon content 0.11 ppm, COD 0.3 mg / l, dissolved oxygen about 28.0 cm ³ / l of introduced water is introduced into the cooling water storage tank in the chipping process, and the discharged water from the chipping process is adsorbed by a fine removal device, which is a 30 μm continuous filter made of paper, and ethylene glycol, etc. After the treatment in the activated carbon adsorption tower, almost the entire amount is returned to the cooling water storage tank, mixed with the introduced water, and used as cooling water. While continuously circulating this cooling water, the shortage is replenished with the above introduced water from outside the system and used as cooling water. The COD of the cooling water was 0.3-0.5 mg / l.

  Then, fine and film-like substances are removed by a vibrating sieving step and a gas stream classification step to reduce the fine content to about 50 ppm or less, and then the molten polycondensation prepolymer is precrystallized by a continuous solid-state polymerization apparatus. Until it is supplied to the reactor, it is stored in the atmosphere for about 3 to 5 hours and then immediately sent to the crystallizer, and continuously crystallized at about 155 ° C. for 3 hours under a nitrogen gas flow having an oxygen concentration of 20 ppm or less, and then The mixture was charged into a tower-type solid-phase polymerization vessel, and was continuously subjected to solid-phase polymerization at about 208 ° C. under a nitrogen gas flow having an oxygen concentration of 15 to 20 ppm or less to obtain a solid-phase polymerized polyester. For pre-crystallization and solid-phase polymerization, a silo-type container was used, and the lower angle was set to 5 degrees larger than the repose angle of the resin, and a baffle cone was installed. After the solid-phase polymerization, the mixture was continuously processed in a sieving step and a fine removing step to remove fine and film-like substances. The oxygen concentration in the nitrogen gas discharged from the solid-state polymerization vessel was 30 ppm or less.

In addition, nitrogen gas having an oxygen concentration of 1 ppm was supplied to the seal portions of the stirrers of the melt polycondensation reactor and the solid-state polymerization reactor. The transport of the melt-polycondensation PET chips and the solid-state polymerization PET chips was performed by using a bucket-type conveyor-transport system or a plug-transport system, and a screw-type feeder was mainly used for extracting from a reactor or a storage tank. During the transportation in each step, a nitrogen atmosphere having an oxygen concentration of 30 to 50 ppm was used, and nitrogen gas having an oxygen concentration of 30 to 50 ppm was used for airflow classification.
Various evaluations were performed on the obtained PET by such a production method. The results are shown in Tables 1 and 2.

(Example 1-3)
Using high-purity terephthalic acid and ethylene glycol as raw materials, PET was obtained by a continuous melt polycondensation apparatus and a continuous solid-state polymerization apparatus.
A slurry of high-purity terephthalic acid and ethylene glycol prepared in a slurry preparation tank is continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry is stirred at about 250 ° C. and 0 ° C. under stirring. The reaction was carried out at 0.5 kg / cm ² G for an average residence time of 3 hours. The reaction product was sent to a second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm ² to a predetermined degree of reaction under stirring. As a polycondensation catalyst, crystalline germanium dioxide (sodium content: 0.7 ppm, potassium content: 0.5 pm, heat loss: 2.8%) is heated and dissolved in water, and ethylene glycol is added thereto. The addition heat-treated solution and the phosphoric acid ethylene glycol solution were separately and continuously fed to the second esterification reactor. In addition, a nitrogen gas having an oxygen concentration of 2 ppm or less is passed through these mixing tanks and each reactor, the oxygen concentration in the gas phase of the slurry mixing tank is 20 to 30 ppm or less, and the first and second esterification reactors are used. The oxygen concentration in the gas phase of was maintained at 20 to 30 ppm or less. A nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank. This esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 torr for 1 hour, and then is stirred at about 265 ° C. and 3 torr for 1 hour in the second polycondensation reactor. The mixture was polycondensed at about 275 ° C. and 0.5 to 1 torr for an additional hour and with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer was 0.54 dl / g.

The obtained melt polycondensation prepolymer is extruded from the pores into cooling water of about 20 ° C. having the following water quality, cut into water to form chips, and after centrifugal separation after solid-liquid separation, the water adhering to chips is reduced to about 800 ppm or less. . Approximately 500 particles having a particle size of 1 to 25 μm, obtained by treating industrial water (derived from underground river water) with a coagulating sedimentation device, a filter-filtration device, a nitrogen gas blowing heating degassing device, an activated carbon adsorption device and an ion exchange device. 10 ml, sodium content 0.06 ppm, magnesium content 0.03 ppm, calcium content 0.04 ppm, silicon content 0.11 ppm, COD 0.3 mg / l, dissolved oxygen about 28.0 cm ³ / l of introduced water is introduced into the cooling water storage tank in the chipping process, and the discharged water from the chipping process is adsorbed by a fine removal device, which is a continuous filter of 30 μm made of paper and ethylene glycol, etc. After the treatment in the activated carbon adsorption tower, almost all of the water is returned to the cooling water storage tank, mixed with the introduced water, and used as cooling water. While continuously circulating this cooling water, the shortage is replenished with the above introduced water from outside the system and used as cooling water. The COD of the cooling water was 0.3-0.5 mg / l.

  Next, the chips are transported to a storage tank under a nitrogen atmosphere having an oxygen concentration of 50 ppm or less in the gas phase, and fines and film-like substances are subsequently removed by a vibrating sieving step and an airflow classification step, whereby fines are contained. The amount was about 50 ppm or less. This is sent to a crystallizer, and continuously crystallized at about 155 ° C. for 3 hours under a nitrogen gas flow having an oxygen concentration of 20 ppm or less, and then charged into a column-type solid-state polymerization device, and a nitrogen gas having an oxygen concentration of 15 to 20 ppm or less is introduced. Solid phase polymerization was continuously performed at about 209 ° C. under circulation to obtain a solid phase polymerized polyester. For pre-crystallization and solid-phase polymerization, a silo-type container was used, and the lower angle was set to 5 degrees larger than the repose angle of the resin, and a baffle cone was installed. After the solid-phase polymerization, the mixture was continuously processed in a sieving step and a fine removing step to remove fine and film-like substances. The oxygen concentration in the nitrogen gas discharged from the solid-state polymerization vessel was 25 ppm or less. In addition, nitrogen gas having an oxygen concentration of 2 ppm was supplied to the seal portions of the stirrers of the melt polycondensation reactor and the solid-state polymerization reactor.

In addition, the molten polycondensation PET chip and the solid-phase polymerization PET chip were transported almost by a bucket-type conveyor transport method or a plug transport method, and a screw-type feeder was mainly used for extraction from a reactor or a storage tank. During the transportation in each step, a nitrogen atmosphere having an oxygen concentration of 30 to 50 ppm was used, and nitrogen gas having an oxygen concentration of 30 to 50 ppm was used for airflow classification.
Various evaluations were performed on the obtained PET by such a production method. The results are shown in Tables 1 and 2.

(Example 1-4)
Using high-purity terephthalic acid and ethylene glycol as raw materials, PET was obtained by a continuous melt polycondensation apparatus and a continuous solid-state polymerization apparatus.
A slurry of high-purity terephthalic acid and ethylene glycol prepared in a slurry preparation tank is continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry is stirred at about 250 ° C. and 0 ° C. under stirring. The reaction was carried out at 0.5 kg / cm ² G for an average residence time of 3 hours. The reaction product was sent to a second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm ² to a predetermined degree of reaction under stirring. As a polycondensation catalyst, crystalline germanium dioxide (sodium content: 0.7 ppm, potassium content: 0.5 pm, heat loss: 2.8%) is heated and dissolved in water, and ethylene glycol is added thereto. The addition heat-treated solution and the phosphoric acid ethylene glycol solution were separately and continuously fed to the second esterification reactor. In addition, a nitrogen gas having an oxygen concentration of 2 ppm or less is passed through these mixing tanks and each reactor, the oxygen concentration in the gas phase of the slurry mixing tank is 20 to 30 ppm or less, and the first and second esterification reactors are used. The oxygen concentration in the gas phase of was maintained at 20 to 30 ppm or less. A nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank.

This esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 torr for 1 hour, and then is stirred at about 265 ° C. and 3 torr for 1 hour in the second polycondensation reactor. The mixture was polycondensed at about 275 ° C. and 0.5 to 1 torr for an additional hour and with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer was 0.54 dl / g.
The obtained melt polycondensation prepolymer is extruded from the pores into cooling water of about 20 ° C. having the following water quality, cut into water to form chips, and after centrifugal separation after solid-liquid separation, the water adhering to chips is reduced to about 800 ppm or less. . Approximately 500 particles having a particle size of 1 to 25 μm, obtained by treating industrial water (derived from underground river water) with a coagulating sedimentation device, a filter-filtration device, a nitrogen gas blowing heating degassing device, an activated carbon adsorption device and an ion exchange device. 10 ml, sodium content 0.06 ppm, magnesium content 0.03 ppm, calcium content 0.04 ppm, silicon content 0.11 ppm, COD 0.3 mg / l, dissolved oxygen about 28.0 cm ³ / l of introduced water is introduced into the cooling water storage tank in the chipping process, and the discharged water from the chipping process is adsorbed by a fine removal device, which is a continuous filter of 30 μm made of paper and ethylene glycol, etc. After the treatment in the activated carbon adsorption tower, almost all of the water is returned to the cooling water storage tank, mixed with the introduced water, and used as cooling water. While continuously circulating this cooling water, the shortage is replenished with the above introduced water from outside the system and used as cooling water. The COD of the cooling water was 0.3-0.5 mg / l.

  Then, fine and film-like substances are removed by a vibrating sieving step and a gas stream classification step to reduce the fine content to about 50 ppm or less, and then the molten polycondensation prepolymer is precrystallized by a continuous solid-state polymerization apparatus. Until it is supplied to the reactor, it is stored in the atmosphere for about 3 to 5 hours and then immediately sent to the crystallizer, and continuously crystallized at about 155 ° C. for 3 hours under a nitrogen gas flow having an oxygen concentration of 20 ppm or less, and then The mixture was charged into a tower-type solid-phase polymerization vessel, and was continuously subjected to solid-phase polymerization at about 208 ° C. under a nitrogen gas flow having an oxygen concentration of 15 to 20 ppm or less to obtain a solid-phase polymerized polyester. For pre-crystallization and solid-phase polymerization, a silo-type container was used, and the lower angle was set to 5 degrees larger than the repose angle of the resin, and a baffle cone was installed. After the solid-phase polymerization, the mixture was continuously processed in a sieving step and a fine removing step to remove fine and film-like substances. The oxygen concentration in the nitrogen gas discharged from the solid-state polymerization vessel was 30 ppm or less.

In addition, nitrogen gas having an oxygen concentration of 1 ppm was supplied to the seal portions of the stirrers of the melt polycondensation reactor and the solid-state polymerization reactor. The transport of the melt-polycondensation PET chips and the solid-state polymerization PET chips was performed by using a bucket-type conveyor-transport system or a plug-transport system, and a screw-type feeder was mainly used for extracting from a reactor or a storage tank. During the transportation in each step, a nitrogen atmosphere having an oxygen concentration of 30 to 50 ppm was used, and nitrogen gas having an oxygen concentration of 30 to 50 ppm was used for airflow classification.
Various evaluations were performed on the obtained PET by such a production method. The results are shown in Tables 1 and 2.

(Example 1-5)
Using high-purity terephthalic acid and ethylene glycol as raw materials, PET was obtained by a continuous melt polycondensation apparatus and a continuous solid-state polymerization apparatus.
A slurry of high-purity terephthalic acid and ethylene glycol prepared in a slurry preparation tank is continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry is stirred at about 250 ° C. and 0 ° C. under stirring. The reaction was carried out at 0.5 kg / cm ² G for an average residence time of 3 hours. The reaction product was sent to a second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm ² to a predetermined degree of reaction under stirring. As a polycondensation catalyst, crystalline germanium dioxide (sodium content: 0.6 ppm, potassium content: 0.4 pm, heat loss: 2.9%) is dissolved by heating in water, and ethylene glycol is added thereto. The addition heat-treated solution and the phosphoric acid ethylene glycol solution were separately and continuously fed to the second esterification reactor. In addition, a nitrogen gas having an oxygen concentration of 1 ppm or less is passed through these mixing tanks and each reactor, the oxygen concentration in the gas phase of the slurry mixing tank is 20 to 30 ppm or less, and the first and second esterification reactors are used. The oxygen concentration in the gas phase of was maintained at 20 to 30 ppm or less. A nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank. This esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 torr for 1 hour, and then is stirred at about 265 ° C. and 3 torr for 1 hour in the second polycondensation reactor. The mixture was polycondensed at about 275 ° C. and 0.5 to 1 torr for an additional hour and with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer was 0.56 dl / g.

The obtained molten polycondensation prepolymer is extruded from the pores into cooling water of about 20 ° C. having the following water quality, cut in water to form chips, and after centrifugation after solid-liquid separation, the water adhering to chips is reduced to about 900 ppm or less. . Approximately 600 particles having a particle diameter of 1 to 25 μm, obtained by treating industrial water (derived from underground river water) with a coagulating sedimentation device, a filter-filtration device, a nitrogen gas blowing heating degassing device, an activated carbon adsorption device and an ion exchange device. 10 ml, sodium content 0.05 ppm, magnesium content 0.04 ppm, calcium content 0.02 ppm, silicon content 0.10 ppm, COD 0.3 mg / l, dissolved oxygen about 28.0 cm ³ / l of introduced water is introduced into the cooling water storage tank in the chipping process, and the discharged water from the chipping process is adsorbed by a fine removal device, which is a continuous filter of 30 μm made of paper and ethylene glycol, etc. After being treated in the activated carbon adsorption tower, almost all of the water is returned to the cooling water storage tank, mixed with the introduced water, and used as cooling water. While continuously circulating this cooling water, the shortage is replenished with the above introduced water from outside the system and used as cooling water. The COD of the cooling water was 0.3-0.5 mg / l.

  Then, fines and films are removed by a vibrating sieving step and a gas stream classification step to reduce the fine content to about 50 ppm or less, and then the molten polycondensation prepolymer is subjected to a pre-crystallization apparatus of a continuous solid-state polymerization apparatus. Until it is supplied to the reactor, it is immediately stored in the atmosphere for about 3 to 5 hours, immediately sent to a crystallization apparatus, continuously crystallized at about 155 ° C. for 3 hours under a nitrogen gas flow having an oxygen concentration of 20 ppm or less, and then The mixture was charged into a tower-type solid-state polymerization reactor, and was continuously subjected to solid-state polymerization at about 207 ° C. under a nitrogen gas flow having an oxygen concentration of 15 to 20 ppm or less to obtain a solid-phase-polymerized polyester. For pre-crystallization and solid-phase polymerization, a silo-type container was used, and the lower angle was set to 5 degrees larger than the repose angle of the resin, and a baffle cone was installed. After the solid-phase polymerization, the mixture was continuously processed in a sieving step and a fine removing step to remove fine and film-like substances. The oxygen concentration in the nitrogen gas discharged from the solid-state polymerization vessel was 30 ppm or less.

In addition, nitrogen gas having an oxygen concentration of 1 ppm was supplied to the seal portions of the stirrers of the melt polycondensation reactor and the solid-state polymerization reactor. The transport of the melt-polycondensation PET chips and the solid-state polymerization PET chips was performed by using a bucket-type conveyor-transport system or a plug-transport system, and a screw-type feeder was mainly used for extracting from a reactor or a storage tank. During the transportation in each step, a nitrogen atmosphere having an oxygen concentration of 30 to 50 ppm was used, and nitrogen gas having an oxygen concentration of 30 to 50 ppm was used for airflow classification.
Various evaluations were performed on the obtained PET by such a production method. The results are shown in Tables 1 and 2.

(Example 2)
The same conditions as in Example 1 except that an ethylene glycol solution of basic aluminum acetate, Irganox 1222 (manufactured by Ciba Specialty Chemicals) and an ethylene glycol solution in which ethylene glycol was previously heat-treated were used as the polycondensation catalyst. A melt polycondensation PET was obtained in the same manner as described below. The intrinsic viscosity of the obtained melt polycondensation PET was 0.58 deciliter / gram. Next, solid-state polymerization was performed in the same manner as in Example 1.
This was evaluated in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained PET, the molded plate obtained by molding the PET, and the biaxially stretched bottle. The result was good and no problem.

(Example 3)
Melt polycondensation PET was obtained in the same manner as in Example 1, except that an ethylene glycol solution of titanium tetrabutoxide, an ethylene glycol solution of magnesium acetate tetrahydrate, and an ethylene glycol solution of phosphoric acid were used as the polycondensation catalyst. The intrinsic viscosity of the obtained melt polycondensation PET was 0.56 deciliter / gram. Next, solid-state polymerization was performed in the same manner as in Example 1.
This was evaluated in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained PET, the molded plate obtained by molding the PET, and the biaxially stretched bottle. The result was good and no problem.

(Example 4)
A melt polycondensation PET was obtained in the same manner as in Example 1, except that an ethylene glycol solution of antimony trioxide, an ethylene glycol solution of magnesium acetate tetrahydrate, and an ethylene glycol solution of phosphoric acid were used as the polycondensation catalyst. The intrinsic viscosity of the obtained melt polycondensation PET was 0.59 deciliter / gram. Next, solid-state polymerization was performed in the same manner as in Example 1.
This was evaluated in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained PET, the molded plate obtained by molding the PET, and the biaxially stretched bottle. The result was good and no problem.

(Example 5)
After sorting and removing different kinds of resin bottles, the used polyethylene terephthalate bottle from which the label and cap have been removed is pulverized, and the recovered flakes obtained by washing with water are depolymerized with ethylene glycol in the presence of a depolymerization catalyst, and then transesterified with methanol. The crude dimethyl terephthalate obtained by the reaction was purified by distillation, and the purified dimethyl terephthalate thus obtained was hydrolyzed to obtain high-purity terephthalic acid. The quality was comparable to high purity terephthalic acid produced from para-xylene.
Solid phase polymerized PET was obtained in the same manner as in Example 1 except that a mixture of 30 parts by weight of the high-purity terephthalic acid thus obtained and 70 parts by weight of the high-purity terephthalic acid obtained from para-xylene was used.
This was evaluated in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained PET, the molded plate obtained by molding the PET, and the biaxially stretched bottle. The result was good and no problem.

(Comparative Example 1)
Nitrogen gas bubbling during the preparation of the polycondensation catalyst or phosphoric acid solution and the nitrogen gas flow to the catalyst solution tank were stopped, and nitrogen gas was not allowed to flow through the reaction tank from the raw material preparation tank to the esterification reaction. The same as Example 1 except that the oxygen concentration in the gas phase of the gas was 1000 ppm or more), nitrogen gas was not flowed into the seal of the stirrer of the reactor, and industrial water at about 10 to 15 ° C. was used as it was as chip cooling water. To obtain a prepolymer having an intrinsic viscosity of 0.56 dl / g.

The industrial water used for cooling at the time of chipping has about 60,000 to 80,000 particles / 10 ml of particles having a particle size of 1 to 25 μm, a sodium content of 3.5 to 5.0 ppm, and a magnesium content of 0.7 to 1.0. 0 ppm, calcium content is 2.0-2.5 ppm, silicon content is 3.0-4.5 ppm, COD is 4.0-6.7 mg / l, and dissolved oxygen content is about 42-45 cm ³ / l. There was, and the attached water at the time of chip formation was about 5000 to 7000 ppm.

  After leaving this prepolymer filled in a flexible container in the atmosphere for about 3 months, it was supplied to the same continuous solid-state polymerization apparatus as in Example 1 to perform solid-state polymerization. However, the reaction was carried out in the same manner as in Example 1 except that nitrogen gas was not passed through a seal portion such as a stirrer of each reactor, and the oxygen concentration in the heated nitrogen supplied to the solid-state polymerization apparatus was 300 to 1000 ppm. I let it.

This was evaluated in the same manner as in Example 1. Tables 1 and 2 show the properties of the obtained PET, the molded plate obtained by molding the PET, and the biaxially stretched bottle.
The transparency of the obtained bottle was poor, and gray-brown foreign substances were scattered on the body. Deformation of the plug and leakage of the contents were examined, but leakage of the contents was observed.
In addition, the bottle was irradiated with the black light used in the measurement method (12), and the bottle was observed with naked eyes.

  ADVANTAGE OF THE INVENTION According to the polyester resin of this invention, it is excellent in transparency, has a moderate and stable crystallization rate, and provides a molded object excellent in heat-resistant dimensional stability and flavor retention, especially a heat-resistant hollow molded object. Furthermore, a molded product of stable quality can be obtained even when the product is exposed to excessive drying or the like before molding.

Top view of the stepped plate used in the examples Side view of the step-formed plate of FIG. PET fluorescence spectrum

Claims (18)

A polyester resin mainly composed of a terephthalic acid component and a glycol component, and a fluorescence emission intensity (B ₀ ) at 450 nm in a fluorescence spectrum obtained when the polyester resin is irradiated with excitation light having a wavelength of 343 nm is 20 or less. Polyester resin characterized by the following. 450 nm fluorescence in a fluorescence spectrum obtained when the polyester resin mainly composed of a terephthalic acid component and a glycol component is heated at 180 ° C. for 10 hours and irradiated with excitation light having a wavelength of 343 nm. When the emission intensity is (B _h ) and the same fluorescence emission intensity at 450 nm of the unheated polyester resin is (B ₀ ), the increase in fluorescence emission intensity (B _h −B ₀ ) is 30 or less. Characterized polyester resin. The fluorescence emission intensity at 450 nm (B _h ) in the fluorescence spectrum obtained when the polyester resin heat-treated at a temperature of 180 ° C. for 10 hours was irradiated with excitation light having a wavelength of 343 nm was the same as the 450 nm fluorescence of the unheated polyester resin. upon the emission intensity and (B _0), the polyester resin of claim 1, fluorescence intensity increase (B _h -B ₀₎ is equal to or is 30 or less. It is a polyester resin mainly composed of a terephthalic acid component and a glycol component. The fluorescence emission intensity at 395 nm of the fluorescence spectrum obtained when the polyester resin is irradiated with excitation light having a wavelength of 343 nm is (A ₀ ), 450 nm The polyester resin, wherein (B ₀ / A ₀ ) is 0.4 or less when the fluorescence emission intensity is (B ₀ ). When the fluorescence emission intensity at 395 nm is (A ₀ ) and the fluorescence emission intensity at 450 nm is (B ₀ ) in the fluorescence spectrum obtained by irradiating excitation light having a wavelength of 343 nm, (B ₀ / A ₀ ) is 0. The polyester resin according to any one of claims 1 to 3, which is not more than 0.4. 395 nm fluorescence in a fluorescence spectrum obtained when a polyester resin mainly composed of a terephthalic acid component and a glycol component is heated at 180 ° C. for 10 hours and irradiated with excitation light having a wavelength of 343 nm. The ratio (B _h / A _h ) when the emission intensity is (A _h ) and the fluorescence emission intensity at 450 nm is (B _h ) and the same fluorescence emission intensity at 395 nm of the unheated polyester resin are (A ₀ ). , A difference from the ratio (B ₀ / A ₀ ) when the relative intensity of fluorescence at 450 nm is (B ₀ ) is 0.7 or less. In the fluorescence spectrum obtained when the polyester resin heat-treated at a temperature of 180 ° C. for 10 hours was irradiated with excitation light having a wavelength of 343 nm, the fluorescence emission intensity at 395 nm was (A _h ), and the fluorescence emission intensity at 450 nm was (B _h ). (B _h / A _h ), the ratio (B ₀ /) when the fluorescence emission intensity at 395 nm of the unheated polyester resin is (A ₀ ), and the fluorescence emission intensity at 450 nm is (B ₀ ). polyester resin according to claim 1, the difference between a ₀₎ is equal to or is 0.7 or less. In a fluorescence spectrum obtained when a chip selected from a chip-shaped polyester resin mainly composed of a terephthalic acid component and a glycol component is irradiated with excitation light having a wavelength of 343 nm, the fluorescence emission intensity at 395 nm is (A _S0 ) and 450 nm. Wherein (B _S0 / A _S0 ) is 0.3 or less when the fluorescence emission intensity of (B _S0 ) is _defined as (B _S0 ). The chip-shaped polyester resin according to any one of claims 1 to 7, wherein a fluorescence emission intensity at 395 nm is (A) in a fluorescence spectrum obtained when the selected fluorescence emission chip is irradiated with excitation light having a wavelength of 343 nm. _S0), when the fluorescence intensity of the 450nm and (B _S0), a polyester resin characterized in that it is 0.3 or less (B _S0 / a _S0). In a fluorescence spectrum obtained when a fluorescent light-emitting chip selected after subjecting a chip-shaped polyester resin mainly composed of a terephthalic acid component and a glycol component to heat treatment at a temperature of 180 ° C. for 10 hours and irradiating excitation light having a wavelength of 343 nm, A polyester resin, wherein (B _Sh / A _Sh ) is 0.5 or less when the fluorescence emission intensity at 395 nm is (A _Sh ) and the fluorescence emission intensity at 450 nm is (B _Sh ). The chip-shaped polyester resin according to any one of claims 1 to 7, wherein the chip is heated at a temperature of 180 ° C for 10 hours, and then irradiated with excitation light having a wavelength of 343 nm to the selected fluorescent light-emitting chip. In the obtained fluorescence spectrum, (B _Sh / A _Sh ) is 0.5 or less when the fluorescence emission intensity at 395 nm is (A _Sh ) and the fluorescence emission intensity at 450 nm is (B _Sh ). Polyester resin. A polyester resin mainly composed of a terephthalic acid component and a glycol component, which is obtained by irradiating excitation light having a wavelength of 343 nm to a pulverized resin obtained by heating at 180 ° C. for 10 hours. In the fluorescence spectrum, the ratio (B _Ph / A _Ph ) when the fluorescence emission intensity at 395 nm is (A _Ph ) and the fluorescence emission intensity at 450 nm is (B _Ph ), and the same 395 nm fluorescence of the unheated polyester resin A polyester resin, wherein the difference from the ratio (B _P0 / A _P0 ) when the emission intensity is (A _0P ) and the relative fluorescence intensity at 450 nm is (B _P0 ) is 0.5 or less. 395 nm fluorescence emission intensity in a fluorescence spectrum obtained when a polyester resin mainly composed of a terephthalic acid component and a glycol component, which is obtained by irradiating a powdered polyester resin with excitation light having a wavelength of 343 nm. Wherein (B _P0 / A _P0 ) is 0.3 or less, where (A _P0 ) is the fluorescence emission intensity at 450 nm (B _P0 ). When the fluorescence emission intensity at 395 nm in the fluorescence spectrum obtained by irradiating excitation light having a wavelength of 343 nm to a pulverized polyester resin is defined as (A _P0 ), and the fluorescence emission intensity at 450 nm is defined as (B _P0 ). The polyester resin according to claim 1, wherein (B _P0 / A _P0 ) is 0.3 or less.   The polyester resin according to any one of claims 1 to 14, wherein the amount of increase in the color b value when heat-treated at a temperature of 180 ° C for 10 hours is 4 or less.   The polyester resin according to any one of claims 1 to 15, wherein the polyester resin comprises ethylene terephthalate as a main repeating unit and has a cyclic trimer content of 0.7% by weight or less.   The polyester resin according to any one of claims 1 to 16, wherein the polyester resin contains 0.1 to 10000 ppm of a polyester fine having the same composition as the polyester, and has a melting point of 265 ° C or lower measured by DSC.   18. A molded plate having a thickness of 3 mm obtained by injection molding and having a dimensional change rate measured by thermomechanical analysis (TMA) of 1.0% to 7.0%. Polyester resin described in Crab.

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