WO2024038883A1

WO2024038883A1 - Chemically recycled polyethylene terephthalate resin, molded body of same, and method for producing chemically recycled polyethylene terephthalate resin

Info

Publication number: WO2024038883A1
Application number: PCT/JP2023/029643
Authority: WO
Inventors: 佑山本; 珠世佐々井; 万紀木南; 博史柴野
Original assignee: 東洋紡株式会社
Priority date: 2022-08-17
Filing date: 2023-08-16
Publication date: 2024-02-22
Also published as: JP2024028087A; JP7435843B1

Abstract

The present invention addresses the problem of providing a chemically recycled polyethylene terephthalate resin which includes only a few foreign substances that are difficult to remove by a filter. A chemically recycled polyethylene terephthalate resin according to the present invention is characterized by satisfying the requirements (1) and (2) described below. (1) Aluminum atoms and phosphorus atoms are contained. (2) The amount of foreign substances having a particle diameter of 0.50 µm to 0.69 µm as determined by a particle counter is 2,000 per ml or less.

Description

Chemically recycled polyethylene terephthalate resin, molded product thereof, and method for producing chemically recycled polyethylene terephthalate resin

The present invention relates to a chemically recycled polyethylene terephthalate resin, a molded article thereof, and a method for producing a chemically recycled polyethylene terephthalate resin.

Polyester resin is widely used for packaging and industrial materials because it has excellent mechanical strength, chemical stability, heat resistance, and moisture resistance, and can also be highly transparent, as well as being inexpensive and stable in supply. There is.

A general-purpose polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol. Terephthalic acid and ethylene glycol are produced from petroleum, a fossil fuel. In recent years, recycling of fossil fuel-derived products has been progressing in order to reduce environmental impact such as reducing carbon dioxide emissions.In addition to mechanical recycling of polyester, which involves crushing and remelting the product, it is also possible to decompose polyester to the monomer level. However, chemical recycling in which polycondensation is performed again using this as a raw material is also being put into practical use.

Regarding polyester resin, in order to reduce the environmental impact, the use of polyethylene terephthalate obtained through chemical recycling from PET beverage bottles, polyester fibers for clothing, etc. is being considered. Even such environmentally friendly resins are required to be used for the same purposes as non-recycled resins and to have similar properties.

When polyester resin is used for films, fibers, and beverage bottles, if there are many foreign substances in the resin, product yield will decrease due to poor operability such as film breakage and fiber breakage during processing. Otherwise, foreign matter may remain in the product as a defect, leading to deterioration of quality. Furthermore, when used as a raw material for blow molded products, etc., it is difficult to obtain a hollow molded product with excellent transparency.

It is known that foreign matter is generated especially when the metal catalyst is denatured and becomes insolubilized in the resin.
Antimony, germanium compounds, and titanium compounds are widely used as polyester polycondensation catalysts used in polyester polycondensation. Antimony trioxide is a catalyst that is inexpensive and has excellent catalytic activity, but if it is used as the main component, that is, in an amount sufficient to achieve a practical polymerization rate, metallic antimony trioxide will be produced during polycondensation. is precipitated, which causes darkening and foreign matter on the polyester, which causes surface defects on the film.

A catalyst system consisting of an aluminum compound and a phosphorus compound has been disclosed as a polycondensation catalyst that reduces the amount of foreign matter (see, for example, Patent Document 1). In addition, techniques are known to reduce the production of foreign substances caused by polycondensation catalysts by devising a method for preparing ethylene glycol solutions of aluminum compounds and phosphorus compounds used as catalysts, and by adding phosphorus compounds after the ester reaction is completed. (For example, see Patent Documents 2 and 3).

Japanese Patent Application Publication No. 2007-204557 WO2005/075539 Japanese Patent Application Publication No. 2005-187558

However, it has been discovered that even in the above catalyst system consisting of an aluminum compound and a phosphorus compound, there is a problem in that catalytic foreign substances are generated that are difficult to remove with a filter.

The present invention has been made against the background of such problems with the prior art, and by synthesizing a chemically recycled polyethylene terephthalate resin from raw materials obtained by chemically recycling and using an aluminum compound and a phosphorus compound as a catalyst during polymerization. The purpose of the present invention is to provide a chemically recycled polyethylene terephthalate resin containing less foreign matter that is difficult to remove with a filter (specifically, foreign matter having a particle size of 0.5 to 0.69 μm).

The present inventors have repeatedly studied polycondensation of raw materials containing chemically recycled bis-2-hydroxyethyl terephthalate, and have found that chemically recycled bis-2-hydroxyethyl terephthalate is used and an aluminum compound and a phosphorus compound are used as catalysts during polymerization. The researchers found that compared to polyethylene terephthalate resin obtained from virgin terephthalic acid and virgin ethylene glycol raw materials, chemically recycled polyethylene terephthalate resin can contain fewer foreign substances (particularly foreign substances that are difficult to remove with a filter).

That is, the present invention consists of the following configuration.
[1] A chemically recycled polyethylene terephthalate resin that satisfies the following (1) to (2).
(1) Contains aluminum atoms and phosphorus atoms (2) The amount of foreign matter with a particle size of 0.50 to 0.69 μm measured by a particle counter is 2000 particles/ml or less [2] The aluminum in the chemically recycled polyethylene terephthalate resin The chemically recycled polyethylene terephthalate resin according to [1] above, wherein the content of atoms is 50 mass ppm or less, and the content of the phosphorus atoms is 100 mass ppm or less.
[3] The chemically recycled polyethylene terephthalate resin according to [1] or [2] above, which has an intrinsic viscosity retention of 89% or more.
[4] The chemically recycled polyethylene terephthalate resin according to any one of [1] to [3] above, which has a color b value of 10 or less.
[5] A molded article containing the chemically recycled polyethylene terephthalate resin according to any one of [1] to [4] above.
[6] A method for producing polyethylene terephthalate resin using a raw material containing chemically recycled bis-2-hydroxyethyl terephthalate obtained by decomposing a polyester resin, comprising:
Chemically recycled polyethylene terephthalate, characterized in that the raw material containing the chemically recycled bis-2-hydroxyethyl terephthalate is subjected to a polycondensation reaction in the presence of an aluminum compound and a phosphorus compound, either as it is or after esterifying its OH end. Method of manufacturing resin.
[7] The chemical recycling according to the above [6], wherein the amount of free ethylene glycol component in 100 mol% of the total polyhydric alcohol components constituting the chemical recycling bis-2-hydroxyethyl terephthalate is 1.5 mol% or less. Method for producing polyethylene terephthalate resin.

By using a raw material containing chemically recycled bis-2-hydroxyethyl terephthalate and using an aluminum compound and a phosphorus compound as catalysts during polymerization, compared to polyethylene terephthalate resin obtained from virgin terephthalic acid and virgin ethylene glycol raw materials, A chemically recycled polyethylene terephthalate resin containing less foreign matter (particularly foreign matter that is difficult to remove with a filter) can be obtained. Therefore, the chemically recycled polyethylene terephthalate resin of the present invention can be suitably used as a material for various molded products such as films, fibers, beverage bottles, and optical applications.

Furthermore, it is preferable that the chemically recycled polyethylene terephthalate resin of the present invention has high transparency. Further, it is preferable that coloring is suppressed. Furthermore, it is preferable to have high thermal stability. Resins with high transparency, suppressed coloration, and high thermal stability are particularly preferred as materials for various molded products such as films, fibers, beverage bottles, and optical applications.

The method for producing chemically recycled polyethylene terephthalate resin of the present invention is characterized by polycondensing bis-2-hydroxyethyl terephthalate obtained by chemical recycling.
Note that hereinafter, bis-2-hydroxyethyl terephthalate may be abbreviated as BHET, and bis-2-hydroxyethyl terephthalate obtained by chemical recycling may be abbreviated as chemical recycled BHET or CR-BHET.

Furthermore, polyethylene terephthalate resin obtained by polycondensing chemically recycled BHET is sometimes abbreviated as chemically recycled PET or CR-PET. Moreover, polyethylene terephthalate may be abbreviated as PET.

The chemically recycled PET resin according to this embodiment can be a chemically recycled PET resin with a small amount of foreign matter having a particle size of 0.50 to 0.69 μm.
The present inventors have repeatedly investigated polymerizing chemically recycled PET using chemically recycled BHET obtained by decomposing polyester resin as a raw material, and found that free ethylene was present in the oligomer reaction liquid obtained from chemically recycled BHET. It was found that the content of glycol was low. On the other hand, a large amount of free ethylene glycol is present in the oligomer reaction solution obtained by esterifying terephthalic acid and ethylene glycol. It was discovered that when polymerization is carried out by adding a polymerization catalyst, foreign substances derived from the catalyst, which are difficult to remove with a filter, increase in the resulting resin.

The reason for this is surmised as follows, for example. When a polymerization catalyst is added to an oligomer reaction solution containing a large amount of free ethylene glycol and the internal temperature becomes equal to or higher than the boiling point of ethylene glycol, ethylene glycol rapidly evaporates. Since its volatilization rate is fast and its volatilization amount is large, it exerts some kind of action on the catalyst and promotes modification of the catalyst. As a result, foreign matter derived from the catalyst increases in the produced resin.
In order to suppress the increase in foreign matter, it is important to suppress the content of free ethylene glycol at the time of addition of the polymerization catalyst. At the time of addition of the polymerization catalyst, the content of free ethylene glycol in the oligomer reaction solution containing BHET obtained from chemical recycling BHET is lower than that in the oligomer reaction solution obtained from terephthalic acid or ethylene glycol. In addition, it is possible to reduce the volatilization rate and amount of ethylene glycol at the time of addition of the polymerization catalyst, thereby reducing the effect on the catalyst, suppressing the modification of the catalyst, and improving the resulting resin. Foreign matter derived from the catalyst can be reduced. Furthermore, it is presumed that by using an aluminum compound and a phosphorus compound as a catalyst, the amount of foreign substances in chemically recycled PET can be reduced.

(Chemical Recycling BHET)
Chemically recycled BHET is obtained by heating and depolymerizing PET resin in the presence of ethylene glycol. The original PET resin is preferably one that has been used in some way; examples include containers such as PET bottles and trays collected from the city, fibers and products, and products released during manufacturing before being used as products. , products that were not shipped to the market as B-class products, selvedge parts that are held during film stretching, slit scraps, molded products that were returned due to complaints, etc. Terephthalic acid and ethylene glycol of these PET resins may be derived from petroleum, or may be derived from biomass. It may also be a mechanically recycled molded product. Alternatively, a mixture of these PET resins may be used.

These PET resins are generally used in the depolymerization process after being crushed, washed, and foreign matter removed.
In depolymerization, ethylene glycol and alkaline compounds such as sodium hydroxide and potassium hydroxide are added to PET resin and heated to advance depolymerization. The obtained reaction product is filtered and decolorized to remove solid matter, if necessary, and further, excess ethylene glycol and the like are distilled off to obtain a BHET crude product. By purifying this BHET crude product by distillation, crystallization, etc., it is possible to obtain chemically recycled BHET of a purity used for polycondensation.

Note that, as described above, "chemically recycled BHET" in the present invention refers to one obtained by depolymerizing PET resin, and may contain components other than BHET as impurities. Specifically, in the chemical recycling BHET, BHET, a dicarboxylic acid diester composed of one molecule of a polyhydric carboxylic acid component and two molecules of a polyhydric alcohol component such as bis-2-hydroxyethyl isophthalate; linear dimers and higher polymers; carboxylic acid monoesters composed of one molecule of polyhydric carboxylic acid component and one molecule of polyhydric alcohol component such as mono-2-hydroxyethyl terephthalate; free terephthalic acid Free polyhydric carboxylic acids such as; free polyhydric alcohols such as free ethylene glycol; and the like may be included. The chemically recycled BHET contains BHET as a main component, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more.

The total acid value and hydroxyl value of the chemically recycled BHET is preferably 6,500 eq/ton or more, more preferably 7,000 eq/ton or more, and even more preferably 7,500 eq/ton or more. The upper limit is preferably 9500 eq/ton, more preferably 9000 eq/ton, still more preferably 8500 eq/ton. That is, the total acid value and hydroxyl value of the chemically recycled BHET is preferably 6,500 to 9,500 eq/ton, more preferably 7,000 to 9,000 eq/ton, and still more preferably 7,500 to 8,500 eq/ton. By keeping it within the above range, productivity can be ensured while maintaining sufficient purity. Note that an acid value of 1 eq/ton means that 1 mole of carboxylic acid group (-COOH) is contained per ton of the target (here, chemical recycling BHET), and a hydroxyl value of 1 eq/ton means that the target (here, chemical recycling BHET) contains 1 mole of carboxylic acid group (-COOH). BHET) means that 1 mol of OH groups is contained per ton. Hereinafter, the same meaning applies when specifying the acid value and hydroxyl value for other objects (oligomers, resins, etc.).

As mentioned above, the chemical recycling BHET may contain a polyhydric carboxylic acid component other than the terephthalic acid component and a polyhydric alcohol component other than ethylene glycol. Examples of polyhydric carboxylic acid components other than terephthalic acid components include isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, and cyclohexanedicarboxylic acid, and polyhydric alcohol components other than ethylene glycol include , diethylene glycol, neopentyl glycol, cyclohexanedimethanol, trimethylene glycol, tetramethylene glycol, an ethylene glycol or propylene glycol adduct of bisphenol A, an ethylene glycol or propylene glycol adduct of bisphenol S, and the like. The chemical recycling BHET may contain one or more polyhydric carboxylic acid components, and may contain one or more polyhydric alcohol components.

The amount of terephthalic acid component contained in the chemically recycled BHET is preferably 98.0 mol% or more (or exceeds), more preferably 98.0 mol% or more, when the total polyhydric carboxylic acid component of the chemically recycled BHET is 100 mol%. .3 mol% or more, more preferably 98.5 mol% or more, even more preferably 98.8 mol% or more, particularly preferably 99.0 mol% or more, and most preferably 99.0 mol% or more. It is 2 mol% or more.

As mentioned above, chemically recycled BHET is preferably one obtained by depolymerizing PET resin containing products recovered from the market, and PET recovered from the market is one in which components other than PET are added to adjust crystallinity and physical properties. However, in terms of cost, it is not desirable to select only pure PET from recovered materials or to refine BHET to a level where acid components other than terephthalic acid are undetectable. Therefore, the amount of terephthalic acid component contained in the chemically recycled BHET is preferably 99.98 mol% or less, more preferably 99.95 mol% or less, when the total polyhydric carboxylic acid component of the chemically recycled BHET is 100 mol%. It may be 99.9 mol% or less, 99.85 mol% or less, or 99.8 mol% or less.
That is, the amount of terephthalic acid component contained in the chemically recycled BHET is preferably 98.0 to 99.98 mol%, more preferably 98.0 to 99.98 mol%, when the total polyhydric carboxylic acid component of the chemically recycled BHET is 100 mol%. 3 to 99.95 mol%, more preferably 98.5 to 99.95 mol%, 98.8 to 99.9 mol%, 99.0 to 99.85 mol%, or 99.2 to 99. It may be 8 mol%.

The polycarboxylic acid component other than the terephthalic acid component contained in chemically recycled BHET often contains isophthalic acid component, and the content of isophthalic acid component is equal to the total polycarboxylic acid component of chemically recycled BHET. When taken as 100 mol%, it is preferably 2.0 mol% or less (or less), next preferably 1.7 mol% or less, more preferably 1.5 mol% or less, and even more preferably is 1.2 mol% or less, particularly preferably 1.0 mol% or less, and most preferably 0.8 mol% or less. Further, the content of the isophthalic acid component may be 0.15 mol% or less or less than 0.15 mol%.
The content of the isophthalic acid component is preferably 0.02 mol% or more, more preferably 0.05 mol% or more, 0.1 mol% or more, 0.15 mol% or more, or 0.2 mol% or more. It may be mol% or more.
That is, the content of the isophthalic acid component is preferably 0.02 to 2.0 mol%, more preferably 0.02 to 1.7 mol%, and still more preferably 0.05 to 1.5 mol%. , 0.1-1.2 mol%, 0.15-1.0 mol%, 0.2-0.8 mol%, or 0.02-0.15 mol%.

The amount of ethylene glycol component contained in the chemically recycled BHET is preferably 98.7 mol% or more, more preferably 99.0 mol% or more, when the total polyhydric alcohol component of the chemically recycled BHET is 100 mol%. and may be 99.2 mol% or more, 99.3 mol% or more, or 99.4 mol% or more. Further, the amount of the ethylene glycol component may be 98.0 mol% or more, 98.3 mol% or more, 98.6 mol% or more, or 98.8 mol% or more.

The amount of free ethylene glycol in the ethylene glycol component contained in the chemically recycled BHET is preferably 1.5 mol% or less, more preferably 1.5 mol% or less, when the total polyhydric alcohol component of the chemically recycled BHET is 100 mol%. 1.3 mol% or less, more preferably 1.2 mol% or less, even more preferably 1.0 mol% or less, particularly preferably 0.8 mol% or less, most preferably 0 .6 mol% or less. In this case, the content of free ethylene glycol in the oligomer reaction liquid obtained from chemical recycling BHET is reduced, and the amount of foreign substances that are difficult to remove with a filter in the resulting resin can be further suppressed.

As mentioned above, it is not desirable from a cost standpoint to select only pure PET from recovered materials from the market or to refine BHET to a level where polyhydric alcohol components other than ethylene glycol are not detected. Furthermore, diethylene glycol is generated as a side reaction during the PET manufacturing process, and it is difficult to avoid this.
Therefore, the amount of ethylene glycol component in the total polyhydric alcohol component of chemically recycled BHET is preferably 99.9 mol% or less, more preferably 99.8 mol% or less, and still more preferably 99.75 mol% or less. It is particularly preferably 99.7 mol% or less.
That is, the amount of the ethylene glycol component is preferably 98.0 to 99.9 mol%, more preferably 98.3 to 99.8 mol%, still more preferably 98.6 to 99.75 mol%, Even more preferably it is 98.8 to 99.7 mol%.

Among the polyhydric alcohol components other than ethylene glycol contained in chemically recycled BHET, diethylene glycol component is often contained, and the content of diethylene glycol component is 100 mol% of the total polyhydric alcohol component of chemically recycled BHET. In this case, it is preferably 2.0 mol% or less, more preferably 1.7 mol% or less, even more preferably 1.4 mol% or less, particularly preferably 1.2 mol% or less. The content of the diethylene glycol component is preferably 0.1 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.5 mol% or more, and particularly preferably 0.6 mol%. % or more. That is, the content of the diethylene glycol component is preferably 0.1 to 2.0 mol%, more preferably 0.3 to 1.7 mol%, even more preferably 0.5 to 1.4 mol%, Particularly preferred is 0.6 to 1.2 mol%.

The above-mentioned polycarboxylic acid components such as terephthalic acid component and isophthalic acid component, and polyhydric alcohol components such as ethylene glycol component and diethylene glycol component are present in the chemical recycling BHET as a single substance (that is, one molecule of the compound is liberated). The value also includes the

In order to reduce the amount of diethylene glycol contained in the chemically recycled BHET, it is also preferable to appropriately adjust the amount and time of ethylene glycol added during depolymerization of PET. If the amount of ethylene glycol is small, sufficient transesterification with diethylene glycol in PET may not occur. Furthermore, if the amount of ethylene glycol is too large, diethylene glycol may be generated from ethylene glycol and incorporated into the chemical recycling BHET. The amount of ethylene glycol added is preferably 5 to 7 times the weight of PET.
If the depolymerization time is short, sufficient transesterification with diethylene glycol in PET may not occur. If the time is long, diethylene glycol may be generated from ethylene glycol and incorporated into the chemical recycling BHET. The depolymerization time is preferably 3 to 10 hours. It is preferable that the PET resin be pulverized to an appropriate size so that depolymerization is completed in an appropriate amount of time.
In order to further reduce the amount of diethylene glycol in the obtained chemically recycled BHET, it is preferable to perform recrystallization.

In chemically recycled BHET, the original PET resins may not be the same, and the amounts of copolymer components are not always the same. Furthermore, it is difficult to completely avoid the production of diethylene glycol in the production of PET resin, and the amount of diethylene glycol produced varies depending on differences in production conditions and equipment conditions. These factors cause the composition of the obtained PET resin to vary, and if it exceeds a certain range, the resin properties of the chemically recycled PET resin may deteriorate. In order to obtain molded products of stable quality from chemically recycled PET resin, it is preferable to keep the copolymerization component of chemically recycled PET resin within a specific range. Furthermore, in order to obtain a chemically recycled PET resin with good productivity, it is preferable that the polyhydric carboxylic acid component and polyhydric alcohol component of the chemically recycled BHET be within a certain range.

For example, in PET bottles, PET resin is often copolymerized with a small amount of isophthalic acid or diethylene glycol. In addition to selecting based on standards, we also adjust the proportion of PET resin used as the source of depolymerization, blend multiple chemically recycled BHETs to meet the above range, and appropriately refine chemically recycled BHETs. , (e), (f), and (g).

(e) The amount of terephthalic acid component in the chemically recycled bis-2-hydroxyethyl terephthalate is 98.0 mol% or more and 99.98 mol% or less based on the total polyhydric carboxylic acid components (f) Chemically recycled bis-2-hydroxyethyl terephthalate The amount of ethylene glycol component is 98.0 mol% or more and 99.9 mol% or less (preferably 98.7 mol% or more and 99.9 mol% or less) based on the total polyhydric alcohol components.
(g) Chemical recycling Bis-2-hydroxyethyl terephthalate has a diethylene glycol component amount of 0.1 mol% or more and 2.0 mol% or less based on the total polyhydric alcohol component.

Furthermore, it is preferable to keep it within the range of (h).
(h) The amount of isophthalic acid component based on the total polyvalent carbon components in chemical recycled bis-2-hydroxyethyl terephthalate is 0.02 mol% or more and 2.0 mol% or less

In order to reduce the amount of free ethylene glycol contained in chemically recycled BHET, the ethylene glycol solution of crude BHET obtained by chemical recycling is appropriately purified in the purification process so that it falls within the range of (i). Adjustment is preferred. Alternatively, a plurality of chemically recycled BHETs may be blended and adjusted to fall within the range (i).
(i) The amount of free ethylene glycol component is 1.5 mol% or less based on the total polyhydric alcohol component in chemically recycled bis-2-hydroxyethyl terephthalate.

Note that a copolymerized polyhydric alcohol component such as diethylene glycol has a higher boiling point than ethylene glycol and is less likely to volatilize during polycondensation, so it is easily incorporated into the polyester resin. It is preferable to take these things into account and decide the range of the amount of polyhydric alcohol components other than ethylene glycol.
The amount of terephthalic acid component based on 100 mol% of the total polyhydric carboxylic acid component in the above chemically recycled bis-2-hydroxyethyl terephthalate is TPA (b) mol%, and the total polyhydric carboxylic acid component in the chemically recycled bis-2-hydroxyethyl terephthalate is When the amount of ethylene glycol component with respect to 100 mol% of alcohol component is defined as EG (b) mol%,
The upper limit of the value of (100-TPA(b))+(100-EG(b))×2 is preferably 4 mol%, more preferably 3.5 mol%, still more preferably 3 mol%. The content is particularly preferably 2.8 mol%.
The lower limit of the value of (100-TPA(b))+(100-EG(b))×2 is preferably 0.15 mol%, more preferably 0.3 mol%, still more preferably 0. It is 5 mol%.
That is, the value of (100-TPA(b))+(100-EG(b))×2 is preferably 0.15 to 4 mol%, more preferably 0.3 to 3.5 mol%. , more preferably 0.5 to 3 mol %, particularly preferably 0.5 to 2.8 mol %.
By setting it within the above range, the thermal stability of the obtained chemically recycled PET resin can also be maintained high. Furthermore, the range of selection of manufacturing conditions for chemically recycled PET can be expanded, and chemically recycled PET can be obtained with high productivity.

Chemically recycled BHET may contain a polymerization catalyst for the base PET resin, and may act as a catalyst during the polycondensation reaction to produce chemically recycled PET from chemically recycled BHET. It is preferable that the polymerization catalyst for the original PET resin is not contained in the chemical recycling BHET or is contained at an undetectable level. It is preferable to use chemically recycled BHET that has been purified through the purification process to a level where metal components derived from the polymerization catalyst are not detected.

(Method for producing chemically recycled PET resin)
The method for producing chemically recycled PET resin of the present invention uses chemically recycled BHET obtained by decomposing polyester resin as a raw material, and uses a polyester polymerization catalyst consisting of an aluminum compound and a phosphorus compound as a catalyst. , can be carried out by a method including known steps.

The method for producing the chemically recycled PET resin of the present invention involves polycondensation of raw materials containing recycled BHET obtained by decomposing polyester resins as they are, or after esterification and/or transesterification of their OH terminals. It has a process of Specifically, the first step is to add the chemically recycled BHET to a reaction vessel and melt it, or to add the chemically recycled BHET and, if necessary, a copolymerization component to the reaction vessel and melt it, and then esterify the OH end of the chemically recycled BHET. and a second step of further adding an aluminum compound and a phosphorus compound to the reaction product obtained in the first step to perform a polycondensation reaction. The second step is preferably performed under reduced pressure while removing the produced glycol from the system in a rectification column. As the copolymerization component in the first step, the above-mentioned polyhydric carboxylic acid is preferable, and terephthalic acid is more preferable.

The method for producing chemically recycled PET resin is not particularly limited as long as the above steps are satisfied. For example, chemically recycled BHET obtained by decomposing a polyester resin and, if necessary, other copolymerization components are directly reacted, water is distilled off and esterified, and then polycondensation is carried out under normal pressure or reduced pressure. A direct esterification method is mentioned. Furthermore, if necessary, solid phase polymerization may be performed to increase the intrinsic viscosity.

The first step may be performed in one step or may be performed in multiple steps. The polycondensation in the second step may be carried out in one step or may be carried out in multiple stages. In the case of multiple stages, a multi-can system in which two or more polycondensation cans are connected is preferred. Further, the polycondensation in the second step may be performed only by melt polymerization, but the chemically recycled PET resin produced by melt polymerization may be additionally polymerized by solid phase polymerization.

(polymerization catalyst)
The chemically recycled PET resin of the present invention is produced using a polymerization catalyst consisting of an aluminum compound and a phosphorus compound. As a result, the chemically recycled PET resin of the present invention contains a catalytic amount of an aluminum compound-derived component and a phosphorus compound-derived component. include. In other words, the chemically recycled PET resin of the present invention contains aluminum atoms and phosphorus atoms.

Examples of aluminum compounds and phosphorus compounds include the following.

(aluminum compound)
The aluminum compound is not limited as long as it is soluble in the solvent, and any known aluminum compound can be used without limitation, and among these, at least one selected from carboxylates, inorganic acid salts, and chelate compounds is preferred. Among these, at least one selected from aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, and aluminum acetylacetonate is more preferable, and aluminum acetate, basic aluminum acetate, aluminum chloride, water At least one selected from aluminum oxide, aluminum hydroxide chloride, and aluminum acetylacetonate is more preferred, at least one selected from aluminum acetate and basic aluminum acetate is particularly preferred, and basic aluminum acetate is most preferred.

It is preferable to use the aluminum compound as an aluminum compound solution dissolved in at least one solvent selected from the group consisting of water and alkylene glycol because the effects of the present invention can be significantly exhibited. As the alkylene glycol, it is preferable to use a solvent that dissolves the aluminum compound, and it is more preferable to use a glycol that is a constituent of the target polyester resin, such as ethylene glycol.

In particular, it is preferable to prepare an aqueous solution of an aluminum compound, add alkylene glycol, and then distill off water to obtain an alkylene glycol solution of an aluminum compound.
Specifically, the amount of alkylene glycol added to the aqueous solution of the aluminum compound is preferably 0.5 to 3 times the volume ratio. It is preferable to stir the solution after addition of alkylene glycol for several hours (for example, 0.2 to 5 hours) at room temperature (for example, 18 to 25°C) to obtain a uniform water/alkylene glycol mixed solution. Thereafter, an alkylene glycol solution can be obtained by heating the solution and distilling off water. The heating temperature is preferably 40 to 120°C. Note that, if necessary, the above heating may be performed under reduced pressure (for example, 1 to 30 kPa).

The concentration of the aluminum compound solution is preferably 10 to 30 g/L, more preferably 15 to 25 g/L.

The amount of the aluminum compound added is preferably 5 to 70 mass ppm, more preferably 7 to 55 mass ppm, still more preferably 8 to 50 mass ppm, and even more preferably It is preferably 10 to 40 ppm by weight, particularly preferably 10 to 30 ppm by weight. Polymerization activity can be further increased by adjusting the amount of aluminum atoms to 5 mass ppm or more. On the other hand, by adjusting the content to 70 mass ppm or less, the amount of aluminum-based foreign matter (particularly foreign matter that is difficult to remove with a filter) tends to be further reduced. In particular, from the viewpoint of further reducing the amount of aluminum-based foreign matter, it is preferably 50 mass ppm or less. In addition, in this specification, mass ppm means 10 ^-4 mass %.

In addition, when cost is important, the content of aluminum atoms in chemically recycled PET is preferably 9 to 20 mass ppm, more preferably 9 to 19 mass ppm, still more preferably 10 to 17 mass ppm, especially Preferably it is 12 to 17 ppm by mass. By adjusting the amount of aluminum atoms to 9 mass ppm or more, the polycondensation rate can be further increased and productivity can be ensured. On the other hand, by adjusting the amount to 20 mass ppm or less, it becomes easier to suppress the increase in the amount of aluminum-based foreign substances (particularly foreign substances that are difficult to remove with a filter), regardless of the content of phosphorus atoms, which will be described later. Therefore, the cost of the catalyst can be reduced.

(phosphorus compound)
The phosphorus compound is not particularly limited, but it is preferable to use a phosphonic acid-based compound and/or a phosphinic acid-based compound because it has a large effect of improving the catalytic activity. Among these, the use of a phosphonic acid-based compound has the effect of improving the catalytic activity. is particularly large, so it is more preferable.

Among the above phosphorus compounds, phosphorus compounds having a phosphorus atom and a phenol structure in the same molecule are preferred. Phosphorus compounds that have a phosphorus atom and a phenol structure in the same molecule are not particularly limited, but include phosphonic acid compounds that have a phosphorus atom and a phenol structure in the same molecule, and phosphines that have a phosphorus atom and a phenol structure in the same molecule. It is preferable to use one or more compounds selected from the group consisting of acid-based compounds because both the effect of improving the catalytic activity of the aluminum compound and the effect of improving the thermal stability of the resin are large. It is more preferable to use a phosphonic acid compound having a phosphorus atom and a phenol structure therein, since both the effect of improving the catalyst activity and the effect of improving the thermal stability of the resin are very large. The reason for this is thought to be that the phenol moiety (preferably the hindered phenol moiety) in the phosphorus compound improves the thermal stability of the chemically recycled PET resin.

In addition, phosphorus compounds that have a phosphorus atom and a phenol structure in the same molecule are represented by P(=O)R ¹ (OR ² ) (OR ³ ) and P(=O)R ¹ R ⁴ (OR ² ). Examples include compounds such as R ¹ represents a hydrocarbon group having 1 to 50 carbon atoms containing a phenol structure, a substituent such as a hydroxyl group, a halogen group, an alkoxyl group or an amino group, and a hydrocarbon group having 1 to 50 carbon atoms containing a phenol structure. R ⁴ represents a hydrogen atom, a hydrocarbon group having 6 to 50 carbon atoms, a hydrocarbon group having 6 to 50 carbon atoms containing a substituent such as a hydroxyl group, a halogen group, an alkoxyl group, or an amino group. R ² and R ³ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 50 carbon atoms, or a hydrocarbon group having 1 to 50 carbon atoms containing a substituent such as a hydroxyl group or an alkoxyl group. However, the hydrocarbon group may include not only a linear structure but also a branched structure, an alicyclic structure such as cyclohexyl, and an aromatic ring structure such as phenyl or naphthyl. The ends of R ² and R ³ or R ² and R ⁴ may be bonded to each other.

Examples of phosphorus compounds having a phosphorus atom and a phenol structure in the same molecule include p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonate, diethyl p-hydroxyphenylphosphonate, diphenyl p-hydroxyphenylphosphonate, bis (p-hydroxyphenyl)phosphinic acid, methyl bis(p-hydroxyphenyl)phosphinate, phenyl bis(p-hydroxyphenyl)phosphinate, p-hydroxyphenylphosphinic acid, methyl p-hydroxyphenylphosphinate, p-hydroxyphenyl Examples include phenyl phosphinate.

In addition to the above-mentioned examples, examples of phosphorus compounds having a phosphorus atom and a phenol structure in the same molecule include a phosphorus atom and a hindered phenol structure (alkyl group having a tertiary carbon (preferably t-butyl group, thexyl group)). Examples include phosphorus compounds having a phenol structure in which an alkyl group having a tertiary carbon at the benzylic position; such as a neopentyl group) is bonded to one or two ortho positions of a hydroxyl group. It is preferable that it is a phosphorus compound having an atom and the structure shown below (formula A), and among them, the compound shown below (formula B) is more preferable, and in the following (formula B), X ¹ and X ² have the number of carbon atoms. More preferred is dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, which is an alkyl group having 1 to 4 atoms. The phosphorus compound used in the production of chemically recycled PET resin is a compound shown below (formula B) (preferably dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate). is preferred, but a modified version of the compound shown below (formula B) (preferably dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate) may also be included. Details of the modified product will be described later.

(In (formula A), * represents a bond.)

(In (formula B), X ¹ and X ² each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

The chemically recycled PET of the present invention is preferably a polyester resin produced using a phosphorus compound having a phosphorus atom and a hindered phenol structure in the same molecule as a polymerization catalyst.

In the above (formula B), each of X ¹ and X ² is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms. In particular, an ethyl ester having 2 carbon atoms is preferred because it is commercially available as Irganox 1222 (manufactured by BASF) and is easily available.

It is preferable to use the phosphorus compound after heat treatment in a solvent. Note that the details of the heat treatment will be described later. When dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate in the above (formula B) is used as the phosphorus compound, in the heat treatment, 3,5-di-tert-butyl-4-hydroxy A part of the dialkyl benzylphosphonate undergoes a structural change. For example, it changes due to elimination of a t-butyl group, hydrolysis of an alkyl ester group (preferably an ethyl ester group), and a hydroxyethyl transesterification structure (transesterification structure with ethylene glycol). Therefore, in the present invention, the phosphorus compound may include structurally changed phosphorus compounds in addition to dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate. Note that the elimination of the t-butyl group occurs significantly at high temperatures during the polymerization process.

The solvent in the heat treatment is not limited as long as it is at least one selected from the group consisting of water and alkylene glycol, but as the alkylene glycol, it is preferable to use a solvent that dissolves a phosphorus compound, and it is preferable to use a solvent that dissolves a phosphorus compound, such as ethylene glycol. It is more preferable to use glycol, which is a constituent component of the polyester resin. The heat treatment in a solvent is preferably performed after the phosphorus compound has been dissolved, but it is not necessary to completely dissolve the phosphorus compound.
The temperature of the heat treatment is not particularly limited, but is preferably 20 to 250°C, more preferably 150 to 200°C.
The heat treatment time is not particularly limited, but is preferably 50 to 300 minutes, more preferably 100 to 200 minutes.
The concentration of the phosphorus compound solution is preferably 30 to 70 g/L, more preferably 40 to 60 g/L.

In the following, when diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate is used as a phosphorus compound, part of diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate has a structure Nine phosphorus compounds that have changed are shown. The amount of each structurally changed phosphorus compound in the glycol solution can be determined by P-NMR measurement.

Therefore, as the phosphorus compound in the present invention, in addition to dialkyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5-di-tert-butyl-4 as shown by the nine chemical formulas above may be used. - Modified dialkyl hydroxybenzylphosphonates may also be included.

When the above-mentioned Irganox 1222 is used as the phosphorus compound, it is preferable that at least one of the nine types of phosphorus compound residues shown in Table 1 below is contained in the chemically recycled PET resin. If at least one of the nine types of phosphorus compound residues shown in Table 1 is detected by the P-NMR measurement method, the chemically recycled PET resin has a phosphorus atom and a hindered phenol structure in the same molecule. It can be said that this is a chemically recycled PET resin manufactured using a phosphorus compound having this as a polymerization catalyst. By using a phosphorus compound having a hindered phenol structure, sufficient polymerization activity can be exhibited while reducing the cost of the catalyst.

In the present invention, it is preferable that at least one of the above formulas 1, 4, and 7 is included.

The content of phosphorus atoms in chemically recycled PET is preferably 5 to 1000 mass ppm, more preferably 10 to 500 mass ppm, even more preferably 15 to 200 mass ppm, and 15 to 100 mass ppm. Particularly preferably ppm, most preferably 15 to 80 ppm by weight. By adjusting the amount of phosphorus atoms to 5 mass ppm or more, the effect of improving polymerization activity and the effect of suppressing the amount of aluminum-based foreign substances (particularly foreign substances that are difficult to remove with a filter) can be further enhanced. On the other hand, the polymerization activity can be increased by adjusting the amount to 1000 mass ppm or less, and the catalyst cost can be suppressed by reducing the amount of the phosphorus compound added.

If cost is more important, the content of phosphorus atoms in chemically recycled PET is preferably 13 to 31 mass ppm, more preferably 15 to 29 mass ppm, and even more preferably 16 to 28 mass ppm. By adjusting the amount of phosphorus atoms to 13 mass ppm or more, the effect of improving polymerization activity and the effect of suppressing the amount of aluminum-based foreign matter (particularly foreign matter that is difficult to remove with a filter) can be further enhanced. On the other hand, by adjusting the content to 31 mass ppm or less, the polymerization activity can be further increased, and the catalyst cost can be further suppressed by further reducing the amount of the phosphorus compound added.

The molar ratio of phosphorus atoms to aluminum atoms in chemically recycled PET is preferably from 1.00 to 5.00, more preferably from 1.10 to 4.00, and more preferably from 1.20 to 3.50. It is more preferably 1.25 to 3.00, particularly preferably 1.25 to 3.00. As mentioned above, the aluminum and phosphorus atoms in chemically recycled PET are derived from the aluminum and phosphorus compounds used as polymerization catalysts, respectively. By using these aluminum compounds and phosphorus compounds together in a specific ratio, a complex having catalytic activity is functionally formed in the polymerization system, and sufficient polymerization activity can be exhibited. In addition, resins manufactured using polymerization catalysts consisting of aluminum compounds and phosphorus compounds have higher catalyst costs (higher manufacturing costs) than chemically recycled PET resins manufactured using catalysts such as antimony catalysts. However, by using an aluminum compound and a phosphorus compound together in a specific ratio, it is possible to exhibit sufficient polymerization activity while suppressing the cost of the catalyst. By adjusting the residual molar ratio of phosphorus atoms to aluminum atoms to 1.00 or more, thermal stability and thermal oxidation stability can be improved, and aluminum-based foreign substances (especially foreign substances that are difficult to remove with a filter) can be improved. The amount can be further suppressed. On the other hand, by adjusting the remaining molar ratio of phosphorus atoms to aluminum atoms to 5.00 or less, the catalyst cost can be suppressed by reducing the amount of the phosphorus compound added.
When cost is more important, the residual molar ratio of phosphorus atoms to aluminum atoms is preferably 1.32 to 1.80, more preferably 1.38 to 1.68.

As described above, by adjusting the content of aluminum atoms and phosphorus atoms and the molar ratio of phosphorus atoms to aluminum atoms, it is possible to further suppress the amount of foreign substances that are difficult to remove with a filter. Foreign matter can function as a crystallization agent and speed up the crystallization rate of chemically recycled PET resin. Therefore, if the amount of foreign matter in the chemically recycled PET resin is large, the resin will easily crystallize during processing, which may lead to deterioration of quality such as decreased transparency due to whitening of the resin. In order to improve transparency, there is a method of adding a copolymer component such as isophthalic acid to polyethylene terephthalate resin to reduce the crystallization rate, but this method may lead to a decrease in the physical properties of the resin.
On the other hand, the chemically recycled PET resin of the present invention has a suppressed amount of foreign matter and a suppressed crystallization rate of the chemically recycled PET resin, so it does not contain copolymerized components such as isophthalic acid or has a small content. It is also preferable in that it can be used.

(Catalysts other than aluminum compounds and phosphorus compounds)
Furthermore, in the present invention, in addition to the above-mentioned aluminum compounds and phosphorus compounds, other polymerization catalysts such as antimony compounds, germanium compounds, titanium compounds, and cobalt compounds are used to improve the properties, processability, color tone, etc. of the chemically recycled PET resin of the present invention. They may be used together as long as they do not cause any problems to the product.

The content of antimony atoms in the chemically recycled PET resin of the present invention is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, even more preferably 20 mass ppm or less. The content of germanium atoms in the chemically recycled PET resin is preferably 40 mass ppm or less, more preferably 20 mass ppm or less, and the content of titanium atoms in the chemically recycled PET resin of the present invention is 10 mass ppm or less. ppm or less, more preferably 5 mass ppm or less, and the content of cobalt atoms in the chemically recycled PET resin of the present invention is preferably 40 mass ppm or less, and 20 mass ppm or less. It is more preferable.

However, for the purpose of the present invention, it is preferable to use as few of the other polymerization catalysts as possible.

By using aluminum compounds and phosphorus compounds as polymerization catalysts, the amount of foreign matter is reduced compared to when other polymerization catalysts (e.g., titanium compounds and antimony compounds) are used, but in order to further reduce the amount of foreign matter, It is preferable to add an aluminum compound and a phosphorus compound to the polymerization catalyst from the end of the first step to before the start of the second step. The above-mentioned "before the start of the second step" includes the time when the pressure is reduced and polycondensation is started. In addition, as mentioned above, when adding an aluminum compound and a phosphorus compound, it is preferable to add them as an aluminum compound solution and a phosphorus compound solution.

In addition, since the amount of free ethylene glycol component in chemically recycled BHET varies from lot to lot, it is necessary to not only reduce the amount of free ethylene glycol in chemically recycled BHET to a certain amount or less, but also to produce chemically recycled PET using chemically recycled BHET. It is preferable to reduce as much as possible the amount of free ethylene glycol contained in the reaction solution at the end of the first step in producing the resin. Preferably, the amount of free ethylene glycol component is 1.5 mol% or less based on 100 mol% of the total amount of all polyhydric alcohol components contained in the reaction solution at the end of the first step. More preferably, it is 1.0 mol% or less, still more preferably 0.7 mol% or less, particularly preferably 0.5 mol% or less.

In order to reduce as much as possible the amount of free ethylene glycol component contained in the reaction solution at the end of the first step, it is preferable to perform the first step in a short time, for example.

The reaction temperature is preferably 80 to 285°C, more preferably 90 to 282°C, even more preferably 100 to 280°C, particularly preferably 110 to 278°C. The pressure is preferably 0.05 to 0.60 MPa, more preferably 0.055 to 0.55 MPa, even more preferably 0.060 to 0.50 MPa, particularly preferably 0.065 to 0.45 MPa. . The reaction time is preferably 200 minutes or less, more preferably 195 minutes or less, even more preferably 190 minutes or less, particularly preferably 185 minutes or less. By using a raw material containing chemically recycled BHET, it is possible to carry out the esterification reaction without going through the esterification reaction or in a short time, and in this case, the generation of free ethylene glycol can be suppressed.
Note that when only chemically recycled BHET is used as a raw material, the first step may be completed at the time when chemically recycled BHET is added to the reaction vessel and melted.

It is also preferable to add an alkali agent during the first step (for example, during the esterification reaction). In this case, the first step can be performed in a short time. Examples of alkaline agents include tertiary amines such as triethylamine, tri-n-butylamine, and benzyldimethylamine, and quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, and trimethylbenzylammonium hydroxide. and lithium carbonate, sodium carbonate, potassium carbonate, sodium acetate, and the like.

The lower limit of the amount of the alkali agent added is preferably 0.01 mol%, more preferably 0.05 mol%, and even more preferably It is 0.1 mol%. The upper limit of the amount of alkali agent is preferably 2 mol%, more preferably 1.5 mol%, and even more preferably 1 mol%.

In the production of the chemically recycled PET resin of the present invention, the physical properties of the reaction intermediate oligomer after the first step (e.g., esterification reaction) are such that the acid value is 80 to 2000 eq/ton and the hydroxyl value is 2800 to 8000 eq/ton. It is preferable that Thereby, the reaction rate of the polycondensation reaction can be increased. As for the physical properties of the reaction intermediate oligomer, it is more preferable that the acid value is 90 to 1900 eq/ton and the hydroxyl value is 3000 to 7800 eq/ton.
In the present invention, an oligomer is a reaction intermediate after the first step (e.g., esterification reaction) and before the polycondensation reaction, including any unreacted raw materials, if any. shows.

In order to reduce the amount of foreign matter in the chemically recycled PET resin, it is also preferable to perform the second step in a short time, for example.

For this purpose, it is preferable to carry out the first step in the presence of terephthalic acid. That is, it is preferable to add terephthalic acid to the chemical recycling BHET and perform the first step in the presence of terephthalic acid. In this case, the reaction is activated by the acid group of terephthalic acid, making it possible to perform the second step in a short time, and making it possible to reduce the thermal history in the polycondensation reaction. When adding an acid component, it is preferable to perform the esterification reaction of the acid component in a short time.
Specifically, for example, the first step is carried out while water or alcohol produced by the reaction is removed from the system in a rectification column. The temperature in the first step is preferably 80 to 285°C, more preferably 90 to 282°C, even more preferably 100 to 280°C, particularly preferably 110 to 278°C. The pressure is preferably 0.05 to 0.60 MPa, more preferably 0.055 to 0.55 MPa, even more preferably 0.060 to 0.50 MPa, particularly preferably 0.065 to 0.45 MPa. be exposed. The reaction time is preferably 200 minutes or less, more preferably 195 minutes or less, still more preferably 190 minutes or less, particularly preferably 185 minutes or less, and most preferably 100 minutes or less.
The amount of terephthalic acid to be added (hereinafter sometimes referred to as added terephthalic acid) should be 40 mol% or less based on the total of 100 mol% of all polyhydric carboxylic acid components and added terephthalic acid in the chemical recycling BHET. preferable. More preferably it is 30 mol% or less, and still more preferably 20 mol% or less.

In order to carry out the second step in a short time, it is preferable to carry out the polycondensation while adjusting the temperature and degree of vacuum so that the degree of polymerization increases in a short time. At the initial stage of polycondensation, the temperature is preferably 260 to 270°C and the pressure is preferably 0.01 to 0.001 MPa, and the pressure is lowered while gradually increasing the temperature, and finally the temperature is preferably 270 to 270°C. It is carried out at 285° C. and a pressure of preferably 0.0002 to 0.000005 MPa or 0.00002 to 0.000005 MPa. The time for the polycondensation reaction is preferably within 200 minutes, more preferably within 180 minutes, even more preferably within 160 minutes, particularly preferably within 140 minutes, most preferably 120 minutes or less, from when the above temperature is reached until the end of the polycondensation reaction. Within minutes. Further, it is preferable to quickly raise the temperature to the initial temperature after charging the reactants after the first step. In order to shorten the heating time, it is preferable to optimize the size and shape of the reaction vessel, such as by increasing the surface area relative to the contents, and to optimize the amount of reactants added after the first step. . Further, it is preferable to perform sufficient stirring.
It is also important to optimize the amount of polycondensation catalyst added so as to obtain a high polymerization rate, and to perform sufficient stirring to renew the catalyst surface. If the amount of the catalyst is too large, foreign matter may be formed and the transparency of the film may be reduced or defects may increase. Depending on the use of the film, it is preferable to increase the amount of catalyst within a range that allows these problems to be avoided. The time for the polycondensation reaction is preferably 30 minutes or more, more preferably 45 minutes or more, from the viewpoint of appropriate catalyst amount and stirring.

Of the raw materials for chemically recycled PET, chemically recycled BHET is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more. It is also preferable that the amount is 100% by mass.

The amount of foreign substances with a particle size of 0.50 to 0.69 μm measured by a particle counter in the chemically recycled PET resin thus obtained is 2000 particles/ml or less, preferably 1500 particles/ml or less, and more preferably is 800 pieces/ml or less, particularly preferably 300 pieces/ml or less, and most preferably 150 pieces/ml or less.
By adjusting the amount of foreign matter within the above range, it is possible to suppress a decrease in transparency and a deterioration in the quality of the molded product.

The lower limit of the cooling crystallization temperature of the chemically recycled PET resin is, for example, 175°C or higher, preferably 178°C or higher, more preferably 180°C or higher, particularly preferably 183°C or higher, and most preferably 185°C or higher. ℃ or higher. The upper limit of the cooling crystallization temperature of chemically recycled PET resin is, for example, 202°C or lower, preferably 200°C or lower, more preferably 198°C or lower, particularly preferably 196°C or lower, and most preferably 194°C or lower. be. That is, the cooling crystallization temperature of the chemically recycled PET resin is, for example, 175 to 202°C, preferably 178 to 200°C, more preferably 180 to 198°C, still more preferably 183 to 196°C, particularly preferably 185°C. ~194°C.

The lower limit of the amount of terephthalic acid component based on 100 mol% of the total polyhydric carboxylic acid components in the chemically recycled PET resin is preferably 98 mol%, next preferably 98.3 mol%, and more preferably 98.5 mol%. %, more preferably 98.8 mol%, particularly preferably 99 mol%, most preferably 99.2 mol%. The upper limit of the amount of terephthalic acid component is preferably 99.98 mol%, more preferably 99.95 mol%, even if it is 99.9 mol%, 99.85 mol%, or 99.8 mol%. good. In this specification, the lower limit of 98 mol% means that it may be 98 mol% or more, or may be more than 98 mol%. Further, in this specification, the upper limit of 99.98 mol% means that it may be 99.98 mol% or less, or may be less than 99.98 mol%. The same applies to the upper and lower limits of other components and physical properties.
That is, the amount of terephthalic acid component based on 100 mol% of the total polycarboxylic acid components in the chemically recycled PET resin is preferably 98 to 99.98 mol%, more preferably 98.3 to 99.95 mol%. It may be 98.5 to 99.9 mol%, 98.8 to 99.85 mol%, 99 to 99.8 mol%, or 99.2 to 99.8 mol%.

The lower limit of the amount of isophthalic acid component based on 100 mol% of the total polycarboxylic acid components in the chemically recycled PET resin is preferably 0.02 mol%, more preferably 0.05 mol%, 0.1 mol%, 0. It may be 15 mol% or 0.2 mol%. In this case, the crystallization rate can be optimized and a highly transparent resin can be obtained. The upper limit of the amount of isophthalic acid component is preferably 2 mol%, next preferably 1.7 mol%, more preferably 1.5 mol%, still more preferably 1.2 mol%, especially Preferably it is 1 mol%, most preferably 0.8 mol%, and may be 0.15 mol%. Note that the upper limit of 2 mol% means that it may be 2 mol% or less, or may be less than 2 mol%.
That is, the amount of isophthalic acid component is preferably 0.02 to 2 mol%, more preferably 0.05 to 1.7 mol%, based on 100 mol% of the total polycarboxylic acid components in the chemically recycled PET resin. It may be 0.1 to 1.5 mol%, 0.15 to 1.2 mol%, 0.2 to 1 mol%, or 0.02 to 0.15 mol%.

The lower limit of the ethylene glycol component amount relative to 100 mol% of the total polyhydric alcohol components in the chemically recycled PET resin is preferably 97.5 mol%, more preferably 97.7 mol%, and even more preferably 97.8 mol%. %, particularly preferably 97.9 mol%, most preferably 98 mol%. The upper limit of the amount of ethylene glycol component is preferably 99.3 mol%, more preferably 99.1 mol%, even more preferably 99 mol%, particularly preferably 98.9 mol%, and most preferably is 98.8 mol%.
That is, the amount of ethylene glycol component relative to 100 mol% of the total polyhydric alcohol component in the chemically recycled PET resin is preferably 97.5 to 99.3 mol%, more preferably 97.7 to 99.1 mol%. It is more preferably 97.8 to 99 mol%, particularly preferably 97.9 to 98.9 mol%, and most preferably 98 to 98.8 mol%.

The lower limit of the amount of diethylene glycol component relative to 100 mol% of the total polyhydric alcohol components in the chemically recycled PET resin is preferably 0.7 mol%, more preferably 0.9 mol%, and even more preferably 1 mol. %, particularly preferably 1.1 mol %, most preferably 1.2 mol %. The upper limit of the amount of diethylene glycol component is preferably 2.5 mol%, more preferably 2.3 mol%, even more preferably 2.1 mol%, particularly preferably 1.9 mol%, Most preferably it is 1.7 mol%. That is, the amount of diethylene glycol component relative to 100 mol% of the total polyhydric alcohol component in the chemically recycled PET resin is preferably 0.7 to 2.5 mol%, more preferably 0.9 to 2.3 mol%. The content is more preferably 1 to 2.1 mol%, particularly preferably 1.1 to 1.9 mol%, and most preferably 1.2 to 1.7 mol%.
By adjusting the amount of diethylene glycol component within the above range, the chemically recycled PET resin can have high thermal stability and coloration of the resin can be suppressed. In particular, if the amount of the diethylene glycol component exceeds 2.5 mol%, the intrinsic viscosity retention of the chemically recycled PET resin may become low, and the mechanical properties of the molded article may deteriorate.

The amount of terephthalic acid component relative to 100 mol% of the total polyhydric carboxylic acid component in the above chemically recycled PET resin is TPA (r) mol%, and the amount of ethylene glycol component is relative to 100 mol% of the total polyhydric alcohol component in the chemically recycled PET resin. When the amount is expressed as EG(r) mol%,
The lower limit of the value of 200-TPA(r)-EG(r) is preferably 0.8 mol%, more preferably 0.9 mol%, still more preferably 1 mol%, particularly preferably 1 .2 mol%. The upper limit of the value of 200-TPA(r)-EG(r) is preferably 4 mol%, more preferably 3.5 mol%, still more preferably 3.2 mol%, particularly preferably 3 0 mole%, most preferably 2.8 mole%. That is, the value of 200-TPA(r)-EG(r) is preferably 0.8 to 4 mol%, more preferably 0.9 to 3.5 mol%, and still more preferably 1 to 4 mol%. It is 3.2 mol%, particularly preferably 1.2 to 3.0 mol%, and most preferably 1.2 to 2.8 mol%.

By setting the composition of the chemically recycled PET resin within the above range, coloring can be suppressed and it can have high thermal stability.

(Physical properties of chemically recycled PET resin)
The lower limit of the intrinsic viscosity of the chemically recycled PET resin is preferably 0.5 dL/g, more preferably 0.55 dL/g, and even more preferably 0.58 dL/g. The upper limit of the intrinsic viscosity is preferably 0.8 dL/g, more preferably 0.77 dL/g, even more preferably 0.75 dL/g. That is, the intrinsic viscosity of the chemically recycled PET resin is preferably 0.5 to 0.8 dL/g, more preferably 0.55 to 0.77 dL/g, and still more preferably 0.58 to 0.8 dL/g. It is 75 dL/g. By setting it within the above range, the strength as a film and the stability of film formation can be ensured. In order to obtain chemically recycled PET with high intrinsic viscosity, it is preferable to perform solid phase polymerization after melt polymerization.

The lower limit of the acid value of the chemically recycled PET resin is preferably 0 equivalent/ton, more preferably 1 equivalent/ton, still more preferably 2 equivalent/ton, particularly preferably 3 equivalent/ton, and most preferably Preferably it is 4 equivalents/ton. In order to lower the acid value, it is preferable to perform solid phase polymerization, but if solid phase polymerization is not performed, the lower limit of the acid value of PET is preferably 15 equivalents/ton, more preferably 20 equivalents. /ton, more preferably 23 equivalents/ton, particularly preferably 25 equivalents/ton.
The upper limit is preferably 60 equivalents/ton, more preferably 55 equivalents/ton, even more preferably 50 equivalents/ton, particularly preferably 45 equivalents/ton, and most preferably 40 equivalents/ton. . That is, the acid value of the chemically recycled PET resin is preferably 0 to 60 equivalents/ton, more preferably 1 to 55 equivalents/ton, even more preferably 2 to 50 equivalents/ton, and particularly preferably 3 to 45 equivalents/ton, most preferably 4 to 40 equivalents/ton, 15 to 60 equivalents/ton, 20 to 60 equivalents/ton, 23 to 60 equivalents/ton, or 25 to 60 equivalents/ton. There may be. By setting it as the said range, the productivity of chemically recycled PET can be ensured, and the acid value of the obtained film can be made into the appropriate range. In order to keep the acid value within the above range, it is necessary to maintain the above-mentioned appropriate temperature and reduced pressure during polycondensation, and to replace the inside of the reaction vessel with an inert gas such as nitrogen during polycondensation to create a low oxygen state. It is preferable to adopt the method.

The intrinsic viscosity retention after melt-kneading of chemically recycled PET is preferably 89% or more, more preferably 90% or more, still more preferably 91% or more, particularly preferably 92% or more. preferable. If the intrinsic viscosity retention is less than 89%, the thermal stability of the resin may be low and the mechanical properties of the molded product may be insufficient. In addition, in this specification, when it is simply described as "intrinsic viscosity retention rate", it refers to the intrinsic viscosity retention rate after kneading which is melted and kneaded once.

The color b value of the chemically recycled PET resin is preferably 10 or less, more preferably 8 or less, even more preferably 5 or less, and particularly preferably 3 or less. The color b value indicates the yellow/blue coordinate, positive values indicate yellow, negative values indicate blue, and the color b value is affected by the amount of foreign substances and thermal stability of chemically recycled PET resin. it is conceivable that.

This application benefits from the priority rights based on Japanese Patent Application No. 2022-130235 filed on August 17, 2022 and Japanese Patent Application No. 2023-005108 filed on January 17, 2023. It is something that is claimed. The entire contents of the specification of Japanese Patent Application No. 2022-130235 filed on August 17, 2022, and the specification of Japanese Patent Application No. 2023-005108 filed on January 17, 2023. The entire contents are incorporated by reference into this application.

Hereinafter, the present invention will be explained with reference to Examples, but the present invention is not limited to these Examples.

(1) Intrinsic viscosity (IV)
Approximately 3g of PET resin was freeze-pulverized and dried at 140°C for 15 minutes, then 0.20g was weighed, and 1,1,2,2-tetrachloroethane and p-chlorophenol were mixed at a ratio of 1:3 (mass ratio). Using 20 ml of the mixed solvent, the mixture was stirred at 100° C. for 60 minutes to completely dissolve, cooled to room temperature, and then passed through a glass filter to be used as a sample. The falling time of the sample and solvent was measured using an Ubbelohde viscometer (manufactured by Rigosha Co., Ltd.) whose temperature was controlled at 30° C., and the intrinsic viscosity [η] was determined using the following formula.
[η] = (-1+√(1+4K'η _sp ))/2K'C
η _sp = (τ−τ ₀ )/τ ₀
here,
[η]: Intrinsic viscosity (dl/g)
η _sp : Specific viscosity (-)
K': Huggins' constant (=0.33)
C: Concentration (=1g/dl)
τ: Sample falling time (sec)
τ ₀ : Falling time of solvent (sec)

(2) Content of specified metal atoms in sample PET resin was weighed in a platinum crucible, carbonized on an electric stove, and then incinerated in a muffle furnace at 550° C. for 8 hours. The sample after incineration was dissolved in 1.2M hydrochloric acid to prepare a sample solution. The prepared sample solution was measured under the following conditions, and the concentrations of antimony atoms, aluminum atoms, titanium atoms, germanium atoms, and cobalt atoms in the PET resin were determined by high-frequency inductively coupled plasma emission spectrometry.
Equipment: CIROS-120 manufactured by SPECTRO
Plasma output: 1400W
Plasma gas: 13.0L/min
Auxiliary gas: 2.0L/min
Nebulizer: Crossflow nebulizer Chamber: Cyclone chamber Measurement wavelength: 167.078nm

(3) Content of phosphorus atoms in PET resin After performing wet decomposition of PET resin with sulfuric acid, nitric acid, and perchloric acid, it was neutralized with aqueous ammonia. After adding ammonium molybdate and hydrazine sulfate to the prepared solution, the absorbance at a wavelength of 830 nm was measured using a UV-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-1700). The concentration of phosphorus atoms in the PET resin was determined from a calibration curve prepared in advance.

(4) Content of polycarboxylic acid component and polyhydric alcohol component in PET resin, polymer acid value, oligomer acid value, oligomer hydroxyl value/amount of polycarboxylic acid component in PET resin Total polycarboxylic acid component The amount (mol %) of each polycarboxylic acid component relative to 100 mol % was determined.
- Amount of polyhydric alcohol component in PET resin The amount of each polyhydric alcohol component (mol %) with respect to 100 mol % of the total polyhydric alcohol component was determined.
・Polymer acid value (AV)
The equivalent amount of acid (unit: eq/ton) per ton of PET resin was determined.
・Acid value in oligomer (OLG-AV)
The acid equivalent (unit: eq/ton) per ton of oligomer was determined.
・Hydroxyl value in oligomer (OLG-OHV)
The equivalent weight (unit: eq/ton) of hydroxyl groups per ton of oligomer was determined.
(Measuring method)
20 mg of PET resin was dissolved in 0.6 ml of a mixed solvent of deuterated hexafluoroisopropanol and deuterated chloroform at a ratio of 1:9 (volume ratio), and centrifuged.
Thereafter, the supernatant was collected and subjected to H-NMR measurement under the following conditions.
Equipment: Fourier transform nuclear magnetic resonance apparatus (AVANCE NEO600, manufactured by BRUKER)
^1H resonance frequency: 600.13MHz
Lock solvent: deuterated chloroform Flip angle: 30°
Data acquisition time: 4 seconds Delay time: 1 second Measurement temperature: 30℃
Accumulated number of times: 128 times

(5) Calculation of the proportion of hydroxyl groups in oligomers (OLG-OH%)
The proportion of hydroxyl groups was calculated according to the following formula from the acid value and hydroxyl value determined by the above method. The oligomer end is the sum of the acid value and hydroxyl value.
Ratio of hydroxyl groups = {hydroxyl value / (hydroxyl value + acid value)} x 100

(6) Content of polyhydric carboxylic acid component and polyhydric alcohol component in chemically recycled BHET Chemically recycled BHET was dissolved in heavy methanol, and H-NMR measurement was performed under the following conditions.
Equipment: Fourier transform nuclear magnetic resonance apparatus (manufactured by BRUKER)
^1H resonance frequency: 500.13MHz
Lock solvent: Heavy methanol Flip angle: 45°
Data acquisition time: 4 seconds Delay time: 1 second Measurement temperature: 27℃
Accumulated number of times: 36 times

(7) Amount of foreign matter 0.06 g of PET resin was dissolved in 100 ml of HFIP (hexafluoro-2-propanol) and measured with a particle counter to evaluate the number of particles with a particle size of 0.50 to 0.69 μm.
AccuSizer A7000/SIS, number counting method, particle size distribution measuring device manufactured by Nippon Entegris LLC
Measurement range: 0.5-400μm

(8) Cooling crystallization temperature (Tc2)
Using a differential scanning calorimeter "DSC220 model" manufactured by Seiko Electronics Co., Ltd., 5 mg of PET resin was placed in an aluminum pan, and the lid was pressed to seal the pan. Next, the temperature was once held at 290° C. for 5 minutes, and then cooled at a temperature decreasing rate of 10° C./min. The peak top value of the exothermic peak obtained during cooling was defined as the cooling crystallization temperature.

(9) Color b value of PET resin Approximately 50 g of PET resin was packed into a measurement cell and measured while rotating, and the color b value was measured from the tristimulus values XYZ, which express the basic amount of color stimulation. . The higher the value, the stronger the yellow color.
Equipment: Tokyo Denshokusha precision spectrophotometer colorimeter TC-1500SX
Measurement method: JIS Z8722 compliant Transmitted light 0 degree, -0 degree method Detection element: Silicon photodiode array Light source: Halogen lamp 12V100W 2000H
Measurement area: Transmission 25mmφ
Humidity temperature condition: 25℃, RH50%
Measuring cell: φ35mm, height 25mm Rotating type (pellet)
Measurement details: X, Y, Z tristimulus values CIE chromaticity coordinates x=X/(X+Y+Z) y=Y/(X+Y+Z)

(10) Thermal decomposition test PET resin was vacuum dried at 140° C. for 16 hours to produce a dry crystallized polyester with a moisture content of 150 ppm or less. Using this dry crystallized polyester, measure the intrinsic viscosity (IV after treatment) after melt-kneading in a twin-screw extruder under the following conditions, and calculate the intrinsic viscosity retention (IV retention) using the following formula: did.
Twin screw extruder: KZW15TW-45/60MG-NH (-2200) manufactured by Technovel
Set temperature: 300℃
Screw rotation speed: 200rpm
Discharge amount: 1.7-2.0kg/h
Intrinsic viscosity retention rate (%) = 100 × Intrinsic viscosity after kneading / Intrinsic viscosity before kneading The moisture content was measured using a Karl Fischer moisture meter (manufactured by Mitsubishi Chemical Analytic Corporation, CA-200), which is a coulometric titration method. Using this method, 0.6 g of a sample was measured at 230° C. for 5 minutes under a nitrogen flow of 250 mL/min.

Hereinafter, the preparation of an aluminum-containing ethylene glycol solution, a phosphorus-containing ethylene glycol solution, and chemically recycled BHET will be explained.

(Preparation of aluminum-containing ethylene glycol solution s)
A 20 g/L aqueous solution of basic aluminum acetate and an equal amount (volume ratio) of ethylene glycol were charged into a mixing tank, stirred for several hours at room temperature (23°C), and then heated to 50 to 90 g/L under reduced pressure (3 kPa). Water was distilled off from the system while stirring at °C for several hours to prepare an aluminum-containing ethylene glycol solution s containing 20 g/L of an aluminum compound.

(Preparation of phosphorus-containing ethylene glycol solution t)
As a phosphorus compound, Irganox 1222 (manufactured by BFA) was charged into a preparation tank together with ethylene glycol, and heat treated at 175°C for 150 minutes with stirring under nitrogen substitution to obtain a phosphorus-containing ethylene glycol solution containing 50 g/L of phosphorus compound. was prepared.

(Preparation of chemically recycled BHET)
The following (j) to (l) were mixed so that the chemically recycled BHET had the composition ratio shown in Table 2 to prepare CR-BHET1, CR-BHET2, and CR-BHET3.
(j) Chemical recycled BHET obtained from recovered beverage bottles and containing isophthalic acid components
(k) Chemical recycled BHET obtained from recovered beverage bottles and containing diethylene glycol components
(l) Chemical recycled BHET obtained from recovered PET film and containing isophthalic acid components

Note that TPA refers to terephthalic acid, IPA refers to isophthalic acid, EG refers to ethylene glycol, and DEG refers to diethylene glycol. Moreover, TPA (b) and EG (b) are as described above.

Example 1
A 5L stainless steel autoclave equipped with a stirrer was charged with CR-BHET1 shown in Table 2 as a chemical recycling BHET, and 0.3 mol% of triethylamine was added as an alkali agent based on the terephthalic acid component in the chemical recycling BHET. Thereafter, BHET was melted to obtain an oligomer (first step). The oligomer properties after the first step are 100 eq/t for OLG-AV, 7600 eq/t for OLG-OHV, and free ethylene glycol content when the total amount of all polyhydric alcohol components contained in the reaction solution is 100 mol%. The amount was 0.1 mol%. Thereafter, a mixed solution obtained by mixing the aluminum-containing ethylene glycol solution s and the phosphorus-containing ethylene glycol solution t prepared by the above method into one liquid was added. The mixed liquid was added so that the amounts of aluminum atoms and phosphorus atoms in the chemically recycled PET were 30 mass ppm and 74 mass ppm. The molar ratio of phosphorus atoms to aluminum atoms was (P/Al)=2.15.
Thereafter, while stirring, the temperature of the system was raised to 278°C, during which time the pressure of the system was gradually reduced to 0.1 kPa, a polycondensation reaction was carried out under these conditions, and the resulting molten resin was fed to a strand cutter to obtain pelletized chemically recycled PET resin. The time from the start of temperature rise to the end of the reaction was 180 minutes.

Example 2
The same procedure as in Example 1 was conducted except that CR-BHET2 listed in Table 2 was used as the chemically recycled BHET.

Examples 3-5
Terephthalic acid (hereinafter sometimes referred to as added terephthalic acid) was charged together with CR-BHET1. The same procedure as in Example 1 was carried out except that the molar ratio of CR-BHET1 and added terephthalic acid, the first step time and the polycondensation time were set to the conditions shown in Table 3.

Example 6
The same procedure as in Example 4 was carried out except that aluminum atoms and phosphorus atoms were used in amounts of 15 mass ppm and 38 mass ppm with respect to the mass of the chemically recycled PET resin. The molar ratio of phosphorus atoms to aluminum atoms (P/Al) was 2.20.

Examples 7 and 8
The same procedure as in Example 1 was conducted except that CR-BHET1 and CR-BHET3 were charged at the molar ratio shown in Table 3.

Comparative example 1
The same procedure as in Example 1 was conducted except that CR-BHET3 shown in Table 2 was used as the chemically recycled BHET.

Comparative example 2
Instead of adding the aluminum-containing ethylene glycol solution s and the phosphorus-containing ethylene glycol solution t, an antimony catalyst was added so that the antimony atoms contained in the chemically recycled PET resin was 200 mass ppm, and the polycondensation time was set as shown in Table 3. The same procedure as in Example 1 was carried out except that the time described in .

Comparative example 3
Instead of adding the aluminum-containing ethylene glycol solution s and the phosphorus-containing ethylene glycol solution t, a titanium catalyst was added so that the titanium atoms contained in the chemically recycled PET resin was 30 mass ppm, and the polycondensation time was set as shown in Table 3. The same procedure as in Example 1 was carried out except that the time described in .

Comparative example 4
At the same time as CR-BHET1, tributyl phosphate was added so that the phosphorus atoms contained in the chemically recycled PET resin was 30 ppm, and instead of adding aluminum-containing ethylene glycol solution s and phosphorus-containing ethylene glycol solution t, chemically recycled PET Same as Example 1 except that 2.5 g/L germanium dioxide-containing ethylene glycol solution was added so that the germanium atoms contained in the resin was 115 ppm by mass, and the polycondensation time was set to the conditions shown in Table 3. went.

Comparative example 5
At the same time as CR-BHET1, tributyl phosphate was added so that the phosphorus atoms contained in the chemically recycled PET resin was 30 ppm, and instead of adding aluminum-containing ethylene glycol solution s and phosphorus-containing ethylene glycol solution t, chemically recycled PET Same as Example 1 except that 4.5 g/L of antimony trioxide-containing ethylene glycol solution was added so that the antimony atoms contained in the resin was 700 mass ppm, and the polycondensation time was set to the conditions shown in Table 3. I went to

Comparative example 6
Instead of adding aluminum-containing ethylene glycol solution s and phosphorus-containing ethylene glycol solution t, 2.5 g/L antimony trioxide-containing ethylene glycol solution, 2.5 g/L cobalt acetate-containing ethylene glycol solution, 2.5 g/L The same procedure as in Example 1 was carried out, except that L phosphoric acid-containing ethylene glycol solution and titanium oxide (product name SA-1: manufactured by Sakai Chemical Industries) were added, and the polycondensation time was set to the conditions shown in Table 3. . The 2.5 g/L antimony trioxide-containing ethylene glycol solution was added so that the antimony atoms contained in the chemically recycled PET resin was 250 mass ppm, and the 2.5 g/L cobalt acetate-containing ethylene glycol solution was , the cobalt atoms contained in the chemically recycled PET resin are added so as to be 57 mass ppm, and the 2.5 g/L phosphoric acid-containing ethylene glycol solution is added so that the phosphorus atoms contained in the chemically recycled PET resin are 17 mass ppm. Titanium oxide was added at a concentration of 3000 ppm by mass based on the chemically recycled PET resin.

Comparative example 7
At the same time as CR-BHET1, an 85% by weight aqueous phosphoric acid solution was added so that the phosphorus atoms contained in the chemically recycled PET resin was 20 ppm, and instead of adding the aluminum-containing ethylene glycol solution s and the phosphorus-containing ethylene glycol solution t. The same procedure as in Example 1 was conducted except that germanium dioxide was added so that the germanium atoms contained in the chemically recycled PET resin was 100 mass ppm, and the polycondensation time was set to the conditions shown in Table 3.

Reference example 1
High-purity terephthalic acid and 2.0 times the molar amount of ethylene glycol were placed in a 5L stainless steel autoclave equipped with a stirrer, and 0.4 mol% of triethylamine was added to the polyhydric carboxylic acid component. The esterification reaction was carried out at 0.degree. C. while water was distilled out of the system to obtain a mixture of BHET and oligomer. After that, the same procedure as in Example 1 was carried out.

Reference example 2
The same procedure as in Reference Example 1 was carried out except that ethylene glycol was charged in a molar amount 1.3 times that of high-purity terephthalic acid.

The results are shown in Table 3.
Example 2 is an example in which the amount of free ethylene glycol was increased from Example 1, and although a slight difference was observed in the amount of foreign substances, there was no problem. Comparative Example 1 is an example in which the amount of free ethylene glycol increased significantly, and the amount of foreign matter increased significantly.
Further, Examples 7 and 8 are examples in which the usage ratio of CR-BHET1 and CR-BHET3 is changed. By blending CR-BHET3 with CR-BHET1, the amount of free ethylene glycol in CR-BHET increases (the amount of free ethylene glycol component in 100 mol% of the total polyhydric alcohol component of CR-BHET: Although a slight increase in the amount of foreign matter was observed (1.0 mol%, 1.3 mol% in Example 8), there was no problem.
Examples 3 to 5 are examples in which the usage ratio of CR-BHET and added terephthalic acid was changed, and although a slight difference was observed in the amount of foreign matter, there was no problem.
Example 6 is an example in which the amounts of Al catalyst and Ti catalyst were changed, and although a slight difference was observed in the amount of foreign matter, there was no problem.
Comparative Examples 2, 3, 4, and 7 are examples in which the metal species and/or phosphorus compound of the catalyst were changed, but the amount of foreign matter increased significantly.
Comparative Example 5 is an example in which an ethylene glycol solution of antimony trioxide was used as an antimony catalyst and tributyl phosphate was used as a phosphorus compound, but the amount of foreign matter increased significantly. This is because the use of a dilute antimony-based ethylene glycol solution increased the amount of free ethylene glycol after adding the catalyst compared to Comparative Example 2, and the absolute amount of catalyst was also large, leading to an increase in the amount of foreign matter. Conceivable.
Comparative Example 6 is an example in which a cobalt compound and titanium oxide were added to suppress the color b value, but the amount of foreign matter increased significantly.
In addition, the amount of free ethylene glycol in the oligomers produced from terephthalic acid and ethylene glycol in Reference Examples 1 and 2 was higher than that in the oligomers using CR-BHET in which the amount of free ethylene glycol was controlled, and the resulting PET resin contained foreign substances. The quantity was also large.

In addition, in Table 3, the molar ratio described in the column of CR-BHET of raw materials in Examples and Comparative Examples is CR when the total of all polyhydric carboxylic acid components and added terephthalic acid contained in CR-BHET is 100 mol%. - Indicates the proportion of all polycarboxylic acid components that BHET has, and the molar ratio stated in the TPA column of raw material is when the total of all polycarboxylic acid components and added terephthalic acid that CR-BHET has is 100 mol%. shows the percentage of added terephthalic acid. Moreover, in Table 3, the molar ratio described in the column of EG of raw materials in Reference Examples indicates the ratio of ethylene glycol when the amount of terephthalic acid is 100 mol%.

Chemically recycled polyethylene terephthalate resin obtained using chemically recycled BHET as a raw material and an aluminum compound and a phosphorus compound as a polymerization catalyst can reduce the amount of foreign substances that are difficult to remove with a filter compared to conventional PET resin. This improves the processing suitability and transparency of PET resin. The resin of the present invention can be suitably used for optical purposes and as a material for various molded products such as films, fibers, and beverage bottles.

Claims

A chemically recycled polyethylene terephthalate resin characterized by satisfying the following (1) to (2).
(1) Contains aluminum atoms and phosphorus atoms (2) The amount of foreign matter with a particle size of 0.50 to 0.69 μm measured by a particle counter is 2000 particles/ml or less
The content of the aluminum atom in the chemically recycled polyethylene terephthalate resin is 50 mass ppm or less, and the content of the phosphorus atom is 100 mass ppm or less, according to claim 1. Chemically recycled polyethylene terephthalate resin.
The chemically recycled polyethylene terephthalate resin according to claim 1, which has an intrinsic viscosity retention of 89% or more.
The chemically recycled polyethylene terephthalate resin according to claim 1, which has a color b value of 10 or less.
A molded article comprising the chemically recycled polyethylene terephthalate resin according to any one of claims 1 to 4.
A method for producing polyethylene terephthalate resin using a raw material containing chemically recycled bis-2-hydroxyethyl terephthalate obtained by decomposing a polyester resin, the method comprising:
Chemically recycled polyethylene terephthalate, characterized in that the raw material containing the chemically recycled bis-2-hydroxyethyl terephthalate is subjected to a polycondensation reaction in the presence of an aluminum compound and a phosphorus compound, either as it is or after esterifying its OH end. Method of manufacturing resin.
The chemically recycled polyethylene terephthalate resin according to claim 6, wherein the amount of free ethylene glycol component in 100% by mole of the total polyhydric alcohol component constituting the chemically recycled bis-2-hydroxyethyl terephthalate is 1.5% by mole or less. Production method.