JP2023027595A - Recycled polyester resin and method for producing recycled polyester resin - Google Patents

Abstract

To provide a copolymerized polyester resin containing 70 mass% or more of a component derived from a recycled polyester raw material.SOLUTION: A polyester resin contains 70 mass% or more of a component derived from a recycled polyester raw material, and satisfies all of (1) to (4). (1) When the total amount of the total acid component constituting polyester is 100 mol%, 70 mol% or more is a terephthalic acid, (2) when the total amount of the total glycol component is 100 mol%, 60-99 mol% is ethylene glycol, 1-20 mol% is an ethylene oxide adduct of bisphenol A, and 4 mol% or less is diethylene glycol, (3) carboxyl terminal group concentration is 40 eq./t, and (4) average pressure increasing speed is 0.6 MPa/h or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a novel recycled polyester resin and a method for producing a recycled polyester resin. In particular, in the present invention, in addition to used polyester products, it is manufactured using recycled polyester raw materials containing unadopted polyester resins generated in the process of manufacturing polyester products, has a small amount of foreign matter mixed in, and is similar to virgin polyester resins. The present invention relates to a recycled polyester resin that can be processed into various molded articles and a method for producing the same.

Polyethylene terephthalate (hereinafter sometimes abbreviated as PET) has a high melting point, chemical resistance, and is relatively inexpensive, so it is widely used for molded products such as fibers, films, and PET bottles. .
These polyester products inevitably generate scraps during the manufacturing and processing stages, and are often disposed of after use. is short. On the other hand, if it is not incinerated, it will remain semi-permanently because it will not rot and decompose.
In recent years, among polyester products that have been used once, plastic containers that have been discarded as garbage flow into the ocean via rivers, and microplastics that are finely crushed by the action of waves and tidal currents accumulate in the bodies of marine organisms. Concentration in the food chain has an adverse effect on the ecosystem of marine organisms, and plastic is a major cause of marine pollution. happening worldwide.

From the viewpoint of reducing the amount of such plastic products used and from the viewpoint of environmental problems, various recycling methods for reusing resources have been carried out. As for polyester products, methods of recycling polyester scraps generated in the manufacturing process and methods of recovering discarded products that have been put on the market and reusing them as raw materials are being studied. Particularly in recent years, with regard to textile products, eco-marked products that are certified by achieving a certain recycling rate have become widespread.

Various methods have been proposed for recycling recycled polyester raw materials. For example, a method of adding methanol to PET waste to decompose it into dimethylene terephthalate (hereinafter sometimes referred to as "DMT") and ethylene glycol (hereinafter sometimes referred to as "EG") (Patent Document 1 ), a method in which EG is added to PET waste to depolymerize it, and then methanol is added to recover DMT (Patent Document 2); A method (Patent Document 3) and the like have been proposed.

In addition, problems that arise when recycling PET bottles that have once been made into products include additives added to the polyester resin, and caps (aluminum, polypropylene, polyethylene) and inner plugs attached to the bottle body. and liners (polypropylene, polyethylene), labels (paper, polystyrene and other resins, inks), adhesives, printing inks, etc.
As a pretreatment for the recycling process, first, collected PET bottles are passed through a vibrating sieve to remove sand, metals, and the like. After that, the PET bottles are washed, the colored bottles are separated, and then coarsely pulverized. Labels and the like are then removed by air separation. Further, the pieces of PET bottles are finely pulverized, except for the pieces of aluminum derived from the cap and the like. Components such as adhesives, proteins and molds are removed by high-temperature alkaline washing, and different components such as polypropylene and polyethylene are separated by specific gravity.

However, even after these steps, it has been difficult to separate non-polyester resins such as polypropylene, polyethylene and polystyrene from PET resins. Therefore, even if the recycled polyester resin is obtained by the recycling method described in Patent Documents 1 to 3 as described above, the foreign matter derived from the non-polyester resin cannot be sufficiently removed, and the amount of foreign matter mixed in cannot be sufficiently reduced. However, it was not possible to obtain a product having the same quality as the virgin polyester resin. Moreover, the methods of Patent Documents 1 to 3 require a large amount of cost for installation, operation, maintenance, etc. of the recovery apparatus, and there is room for improvement in terms of practicality.

Further, the invention described in Patent Document 4 describes a method in which polyester waste is depolymerized with ethylene glycol, filtered through a filter having an average mesh size of 10 to 50 μm, and then subjected to a repolymerization reaction. It is also shown that the resulting recycled polyester resin has a small amount of foreign matter mixed in and is excellent in workability during processing. However, even in this method, the above-described non-polyester resin-derived foreign matter cannot be sufficiently removed, and the amount of foreign matter mixed in cannot be sufficiently reduced.

In general, when manufacturing plastic bottles, etc., die orifices are made of melt-plasticized resin because of its ease of molding, high productivity, and relatively low equipment costs for molding machines and molds. A so-called blow molding method is employed in which a cylindrical parison is formed by extruding through a mold, and air is blown into the inside of the mold. Also in such blow-molded products, the use of recycled polyester resins is being studied from the viewpoint of environmental problems.

In addition, since crystallization tends to occur during blow molding, there is a problem that whitening occurs even if molding is possible, resulting in insufficient transparency.
Therefore, in order to improve transparency, polyester resins obtained by copolymerizing polyethylene terephthalate with other monomer components have been proposed (see, for example, Patent Document 5).

In general, hot-melt binder fibers are widely used for the purpose of bonding fibers constituting pillows, bedding stuffing, quilting stuffing, mattress stuffing, and the like. Among them, copolyester resins containing terephthalic acid, isophthalic acid and ethylene glycol as main components are widely used for polyester binder fibers.

In this way, copolyester resins are used in various molded products and textile products, and there is a great demand for recycled polyester resins that use recycled polyester raw materials in these copolyester resins. However, a copolyester resin has not yet been obtained that can sufficiently remove foreign matters originating from non-polyester resins and that makes it possible to obtain various high-quality products equivalent to virgin polyester resins.

Japanese Patent Publication No. 42-8855 JP-A-48-62732 JP-A-60-248646 JP 2005-171138 A Japanese Patent No. 6297351

The present invention solves the above problems, and has a component derived from recycled polyester raw materials including used polyester products or unadopted polyester resin such as waste generated in the process of manufacturing polyester resin and products at 70% by mass or more. It is an object of the present invention to provide a recycled polyester resin containing a copolyester resin that can be used in the production of various forms of polyester products. Another object of the present invention is to provide a production method capable of obtaining such a recycled polyester resin of the present invention.

As a result of intensive research in view of the problems of the conventional technology, the present inventors have found that by adopting a specific manufacturing method using recycled polyester raw materials, the amount of foreign matter mixed in is small and the heat is equivalent to that of virgin polyester resin. The inventors have found that a recycled polyester resin having stability can be obtained, and have completed the present invention.

In order to solve the above-mentioned problems, the present inventor arrived at the present invention as a result of intensive studies.

That is, the gist of the present invention is the following (a) to (c).
(a) A polyester resin containing 70% by mass or more of a component derived from at least one recycled polyester raw material of (a) used polyester products and (b) unadopted polyester resin generated in the process of manufacturing polyester products, A recycled polyester resin characterized by satisfying all of (1) to (4).
(1) When the total amount of all acid components constituting the polyester is 100 mol%, 70 mol% or more is terephthalic acid,
(2) When the total amount of all glycol components is 100 mol%, 60 to 99 mol% is ethylene glycol, 1 to 20 mol% is an ethylene oxide adduct of bisphenol A, and 4 mol% or less is diethylene glycol. and
(3) a carboxyl terminal group concentration of 40 equivalents/t;
(4) The average pressurization rate is 0.6 MPa / h or less (however, the average pressurization rate is a value calculated by the following procedure: Using a pressurization tester including an extruder and a pressure sensor, the extruder Stainless steel filter at the tip (nominal size mesh: 1400 mesh, weaving method: twilled dutch, vertical mesh: 165 mesh, horizontal mesh: 1400 mesh, vertical wire diameter: 0.07 mm, horizontal wire diameter: 0.04 mm, filtration particle size : 12 μm) is set, the polyester resin is melted at 300 ° C. with an extruder, and the pressure value applied to the filter when extruding the melt at a discharge rate of 29.0 g / min from the filter is the start of extrusion. If the pressure value at the time of extrusion is defined as "initial pressure value (MPa)" and the pressure value at the time of continuous extrusion for 12 hours is defined as "final pressure value (MPa)", the following calculation is based on those pressure values. Calculate the average pressure rise rate by Equation A:
Average pressure increase rate (MPa/h) = (final pressure value - initial pressure value) / 12) ... A)
(b) A blow-molded article containing the recycled polyester resin described in (a).
(C) A method for producing a recycled polyester resin using at least one recycled polyester raw material from among a) used polyester products and b) unused polyester resins generated in the process of producing polyester products, the method comprising the following (1) ) to (4) are all included.
(1) To a mixture containing ethylene glycol and an ethylene oxide adduct of bisphenol A, a recycled polyester raw material is added so that the molar ratio of all glycol components/total acid components is 1.10 to 1.35, and 245 A step of obtaining a depolymer having a melt viscosity of 10 to 1500 mPa s by performing depolymerization under heat treatment conditions of up to 280 ° C. (2) Passing the depolymer through a filter having a filtration particle size of 10 to 25 μm to obtain a filtrate. Step of collecting (3) Step of adding a polycondensation catalyst to the filtrate and kneading to obtain a reaction product (4) Performing a polycondensation reaction on the reaction product at a temperature of 250° C. or higher and under reduced pressure of 1.0 hPa or lower process

The recycled polyester resin of the present invention contains 70% by mass or more of a component derived from at least one recycled polyester raw material of a) used polyester products and b) unadopted polyester resins generated in the process of manufacturing polyester products. Also, the content of ethylene oxide adducts of diethylene glycol and bisphenol A satisfies specific ranges, so that the amount of foreign matter mixed in is small, and the content of ethylene oxide adducts of diethylene glycol and bisphenol A satisfies specific ranges. Therefore, in the blow molding process, an optimum crystallization rate is achieved, which enables long-term continuous operation, and high-quality products can be obtained with good productivity. In particular, direct blow molding can be performed with high productivity, and a product having excellent appearance, transparency and strength equivalent to those using a virgin polyester resin can be obtained.
Further, according to the method for producing a recycled polyester resin of the present invention, it is possible to obtain a recycled polyester resin with a small amount of foreign substances mixed in as described above and excellent in crystallinity and heat resistance with good productivity.

The present invention will be described in detail below.
The recycled polyester resin of the present invention (hereinafter sometimes referred to as the resin of the present invention) is at least one recycled polyester of a) used polyester products and b) unadopted polyester resin generated in the process of manufacturing polyester products. It is a polyester resin containing 70% by mass or more of components derived from raw materials.

Examples of the used polyester products of a) above include, for example, polyester molded articles (including fibers) that have been put on the market once and collected after use. Typical examples include containers or packaging materials such as PET bottles.
Unused polyester resin generated in the process of manufacturing polyester products in b) above is polyester that has not been commercialized. Fragments, scraps generated during molding, processing, etc., cuttings of transitional products generated at the time of brand change, cuttings of prototypes and defective products, etc.

The above a) and b) are not limited in their form, etc., and may be pelletized by further processing such as pulverization and cutting as necessary, or may be melted and pelletized. good.
The above a) and b) may be used alone or in combination.
In addition, the recycled polyester raw materials of a) and b) may be either crystalline or amorphous. Therefore, for example, pellets of amorphous polyester waste not subjected to heat treatment, crystalline pellets subjected to heat treatment, mixtures of crystalline pellets and amorphous pellets, and the like can be used. In the present invention, it is preferable to use a crystalline recycled polyester raw material for the purpose of preventing fusion between pellets, particularly during charging into a can or depolymerization reaction. Therefore, it is possible to preferably use a material obtained by crystallizing the above material a) or b) by heat treatment (crystallized pellets, etc.).
In addition, the properties of the recycled polyester raw materials of a) and b) are not limited, and may be in the form of a) and b), or cut pieces obtained by further processing such as cutting and crushing. , pulverized products (powder) and the like, as well as solid forms such as compacts (such as pellets) formed by molding these. More specific examples include pellets obtained by cooling and cutting melted polyester scraps, cut pieces obtained by finely cutting polyester molded articles such as PET bottles, and the like. In addition, it may be in the form of a liquid obtained by dispersing or dissolving the above cut pieces, pulverized material (powder), etc. in a solvent. When these raw materials are used to produce polyester products, they can be melted at a temperature higher than their melting point and put into a can as a melt, if necessary.

Since the object of the present invention is to obtain a recycled polyester resin with a high usage rate of recycled polyester raw materials, the recycled polyester resin of the present invention is derived from at least one of the above a) and b) recycled polyester raw materials. It contains 70% by mass or more of the component, preferably 75% by mass or more, and more preferably 80% by mass or more.
According to the production method of the present invention, which will be described later, it is possible to easily obtain a recycled polyester resin having a content of components derived from recycled polyester raw materials of 70 to 99% by mass.

The resin of the present invention preferably contains 70 mol % or more of terephthalic acid, preferably 85 mol % or more of terephthalic acid, when the total amount of all acid components constituting the polyester is 100 mol %. If the proportion of terephthalic acid is less than 70 mol %, the obtained polyester resin will be inferior in crystallinity and heat resistance.

Acid components other than terephthalic acid contained in the recycled polyester resin include phthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, adipic acid, sebacic acid, dimer acid, and the like. Two or more of these may be used in combination, and ester-forming derivatives of these acids may also be used.

When the total amount of all glycol components is 100 mol%, the resin of the present invention contains 60 to 99 mol% of ethylene glycol and 1 to 20 mol% of ethylene oxide adduct of bisphenol A, and 4 mol% or less. is diethylene glycol. That is, it contains ethylene glycol as a main component, and an ethylene oxide adduct of bisphenol A and diethylene glycol as copolymer components.

The content (copolymerization amount) of the ethylene oxide adduct of bisphenol A is 1 to 20 mol%, preferably 3 to 15 mol%, more preferably 3 to 12 mol% of the total glycol component. is preferred. By copolymerizing an appropriate amount of the ethylene oxide adduct of bisphenol A, the crystallization speed of the polyester resin can be adjusted to be suitable for blow molding, and crystallization during blow molding can be prevented.

When the content of the ethylene oxide adduct of bisphenol A is less than 1 mol %, the crystallization rate of the resin composition is high, so that the resulting blow-molded article crystallizes and turns white. On the other hand, if it exceeds 20 mol %, it becomes amorphous, and drying at high temperature and solid phase polymerization become difficult. Alternatively, blocking is likely to occur during high-temperature drying or in the solid-phase polymerization process, which is not preferable.

Ethylene glycol accounts for 60 to 99 mol% of the total glycol components, preferably 70 to 90 mol%. If the content of ethylene glycol is less than 60 mol %, the crystallinity and heat resistance of the resulting polyester resin will be poor. On the other hand, when it exceeds 99 mol%, the ratio of the ethylene oxide adduct of bisphenol A decreases, making it difficult to adjust the crystallization speed, and the effect of preventing whitening due to crystallization during blow molding is poor.
The total amount of ethylene glycol and the ethylene oxide adduct of bisphenol A is preferably 70 mol % or more, more preferably 80 mol % or more, of the total glycol components.

In the resin of the present invention, the content of diethylene glycol is 4 mol % or less, preferably 3.5 mol % or less, when the total amount of all glycol components is 100 mol %. In particular, in the resin of the present invention obtained by the production method of the present invention, ethylene glycol is used as one of raw materials, and diethylene glycol may be produced as a by-product at that time. The resin of the present invention has a small amount of diethylene glycol as a by-product, and has excellent crystallinity due to the content of diethylene glycol being 4 mol % or less. Therefore, it becomes possible to obtain molded articles such as fibers, injection molded articles, various blow molded articles, sheets, films, etc. with good productivity. The lower limit of the diethylene glycol content can be, for example, about 0.5 mol %, but is not limited to this.

Examples of diol components other than ethylene glycol and ethylene oxide adducts of bisphenol A include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4- Cyclohexanedimethanol, diethylene glycol, dimer diol, ethylene oxide adduct of bisphenol S, and the like can be used.

The resin of the present invention contains a polycondensation catalyst, and may contain various additives depending on the application.
First, as the polycondensation catalyst, at least one of germanium compounds, antimony compounds, titanium compounds, cobalt compounds, zinc compounds, tin compounds and the like can be used, although not limited thereto. Among them, it is particularly preferable to use at least one of a germanium compound and an antimony compound. When the transparency of the resulting recycled polyester resin is important, it is preferable to use a germanium compound. As the above compounds, oxides such as germanium, antimony, titanium and cobalt, inorganic acid salts, organic acid salts, halides and sulfides can be used.

The amount of the polycondensation catalyst to be used is not particularly limited, but for example, it is preferably 1×10 ⁻⁵ mol or more, preferably 6×10 ⁻⁵ mol or more, per 1 mol of the acid component of the polyester resin to be produced. is more preferable. The upper limit of the amount used can be, for example, about 1×10 ⁻³ mol, but is not limited to this.

The polycondensation catalyst contained in the recycled polyester raw material may also act as a catalyst during the polycondensation reaction, so when adding the polycondensation catalyst in the polycondensation process, the polycondensation catalyst contained in the recycled polyester raw material It is preferable to consider the type of catalyst and its content.

Various additives added depending on the application include fatty acid esters that can adjust the melt viscosity, hindered phenolic antioxidants, phosphorus compounds that can suppress thermal decomposition of the resin, and improve the appearance of the resin. and a titanium compound that improves the whiteness of the resin, a crystal nucleating agent that improves the crystallinity of the resin, and the like.

Examples of fatty acid esters include beeswax (a mixture containing myricyl palmitate as a main component), stearyl stearate, behenyl behenate, stearyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin tri Stearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, dipentaerythritol hexastearate and the like. Among these, glycerin monostearate, pentaerythritol tetrastearate, and dipentaerythritol hexastearate are preferred. These can be used alone or in combination of two or more.

Examples of hindered phenol antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl ) propionate, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 4 , 4′-butylidenebis-(3-methyl-6-t-butylphenol), triethylene glycol-bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], 3,9-bis {2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1′-dimethylethyl}-2,4,8,10-tetraoxaspiro[5,5 ] undecane and the like are used, but tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane is preferred from the viewpoint of effect and cost. These can be used alone or in combination of two or more.

Phosphorus compounds such as phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite, trimethyl phosphate, triethyl phosphate, tridecyl phosphate, and triphenyl phosphate are used as the phosphorus compound. be able to. These can be used alone or in combination of two or more.

Examples of color tone modifiers include cobalt compounds such as cobalt acetate, manganese compounds such as manganese acetate, dyes (blue, purple, and red), and copper phthalocyanine compounds. Among them, cobalt acetate and dyes are preferable from the viewpoint of polycondensation catalytic activity, physical properties of the resulting polyester resin, and cost.
In addition, it is preferable that the dye contains a blue dye, a red dye, a purple dye, or the like, because the color tone is good.

As the dyes, blue dyes such as SOLVENT BLUE 104, SOLVENT BLUE 122, and SOLVENT BLUE 45, SOLVENT RED 111, SOLVENT RED 179, SOLVENT RED 195, SOLVENT RED 135, P IGMENT RED 263, red dyes such as VATRED 41; and purple dyes such as DESPERSE VIOLET 26, SOLVENT VIOLET 13, SOLVENT VIOLET 37, and SOLVENT VIOLET 49. Among them, SOLVENT BLUE 104, SOLVENT BLUE 45, SOLVENT RED 179, SOLVENT RED 195, SOLVENT RED 135, and SOLVENT which do not contain halogen, which tends to cause equipment corrosion, have relatively good heat resistance at high temperatures, and have excellent color development. VIOLET 49 is preferred. These can be used alone or in combination of two or more.

Titanium oxide is preferably used as the titanium compound. Titanium oxide is generally used as a matting agent or white pigment for polyester resins. By adding an appropriate amount of titanium oxide to the resin of the present invention, the whiteness of the fiber is improved, It is preferable in that a woven or knitted fabric with a good color tone can be obtained. The amount of titanium oxide to be added is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the polyester resin.

Crystal nucleating agents include carbon black, calcium carbonate, synthetic silicic acid and silicates, zinc oxide, high-site clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, and titanium oxide. , zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, etc.; compounds and the like. Among them, mica, talc, and high molecular weight organic compounds are preferred. These can be used alone or in combination of two or more.

The resin of the present invention has the characteristic values shown below.
(a) carboxyl terminal group concentration of 40 equivalents/t or less (b) average pressure increase rate measured by a pressure tester of 0.6 MPa/h or less can be obtained by

First, as the characteristic value of (a), the resin of the present invention has a carboxyl terminal group concentration of 40 equivalents/t or less, preferably 35 equivalents/t or less, and more preferably 30 equivalents/t or less. preferable.
Since the resin of the present invention has a carboxyl terminal group concentration of 40 equivalents/t or less, it has excellent heat resistance performance, and it is possible to obtain molded articles with excellent heat resistance by various molding methods. Become.

Although the intrinsic viscosity of the recycled polyester resin of the present invention is not particularly limited, it is usually preferably about 0.44 to 0.80. Further, as described later, the recycled polyester resin of the present invention can be used for molding by increasing the degree of polymerization through a solid phase polymerization process. In this case, the intrinsic viscosity of the resulting recycled polyester resin is preferably 0.80 to 1.25. In addition, the intrinsic viscosity (IV) is measured at a temperature of 20° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.

As the characteristic value of (b), the resin of the present invention has an average pressure increase rate measured by the following method of 0.6 MPa/h or less, preferably 0.5 MPa/h or less, especially 0.4 MPa/h. The following are preferable. The average pressurization rate in the present invention is an index of the amount of foreign substances derived from various inorganic substances and foreign substances derived from non-polyester resins. is shown. When the average pressurization rate is 0.6 MPa/h or less, it becomes possible to produce fibers having a single filament fineness of 0.6 decitex or less by, for example, melt spinning. The lower limit of the average pressure increase rate can be set to, for example, about 0.01 MPa/h, but is not limited to this.

The method for measuring the average pressurization rate uses a pressurization tester including an extruder and a pressure sensor, and a stainless steel filter (nominal size mesh: 1400 mesh, weave: twill weave, vertical mesh: 165 mesh) at the tip of the extruder , horizontal mesh: 1400 mesh, vertical wire diameter: 0.07 mm, horizontal wire diameter: 0.04 mm, filtration particle size: 12 μm), the polyester resin is melted at 300 ° C. in an extruder, and the discharge amount from the filter As the pressure value applied to the filter when the melt is extruded at 29.0 g / min, the pressure value at the start of extrusion is defined as the “initial pressure value (MPa)”, and the pressure value at the time of continuous extrusion for 12 hours. When the pressure value is the "final pressure value (MPa)", the average pressure increase rate is calculated by the following formula A based on those pressure values.
Average pressure increase rate (MPa/h) = (final pressure value - initial pressure value) / 12) ... A)

By adopting the production method described later, the resin of the present invention can reduce the amount of foreign substances derived from various inorganic substances and foreign substances derived from non-polyester resins. It is possible to reduce the average pressure rise rate measured by a tester to 0.6 MPa/h or less.

As the extruder, filter and the like used in the above measurements, known or commercially available ones can be used as appropriate as long as they satisfy the stipulations of the present invention.

In the present invention, if necessary, a reinforcing material may be added to the filter as long as it does not substantially affect the measurement results. In the above measurement method, extremely high pressure is applied to the filter, so the filter alone may be deformed or damaged. In such cases, it is preferable to support the filter with stiffeners. A mesh-like metal member or the like can be used as the reinforcing material. More specifically, a metal filter having a strength that prevents deformation of the filter and having a coarse mesh that does not substantially affect the measurement results can be suitably used as the reinforcing material. Then, such a reinforcing material can be used by laminating it on the downstream side of the filter.

Next, a method for producing the resin of the present invention will be described. In the production method of the present invention, it is important to perform the steps (1) to (4) in order.
(1) To a mixture containing ethylene glycol and an ethylene oxide adduct of bisphenol A, a recycled polyester raw material is added so that the molar ratio of all glycol components/total acid components is 1.10 to 1.35, and 245 A step (2) of obtaining a depolymer having a melt viscosity of 10 to 1500 mPa·s by performing depolymerization under heat treatment conditions of up to 280° C. (2) passing the depolymer through a filter having a filtration particle size of 10 to 25 μm to obtain a filtrate; Step of collecting (3) adding a polycondensation catalyst to the filtrate and kneading to obtain a reaction product; process

First, in the depolymerization step (1), a mixture containing an ethylene oxide adduct of ethylene glycol and bisphenol A is added with a recycled polyester raw material so that the molar ratio of the total glycol component/total acid component is 1.10 to 1.35. A depolymer having a melt viscosity of 10 to 1,500 mPa·s is obtained by adding the components so as to obtain a depolymerization condition under a heat treatment condition of 245 to 280°C.
In the production method of the present invention, the melt viscosity of the depolymer is a value measured at the heat treatment temperature during depolymerization, and is measured using a VISCO METER DV2T type melt viscometer manufactured by Brookfield.

Ethylene glycol and cyclohexanedimethanol to be added to the recycled polyester raw material can be obtained by known methods or commercially available.

The amount of the mixture containing the ethylene oxide adduct of ethylene glycol and bisphenol A (hereinafter sometimes referred to as mixture E) in step (1) is the total amount of mixture E and the recycled polyester raw material, which is 100 parts by mass. It is preferably 1 to 35 parts by mass, more preferably 5 to 30 parts by mass.
On the other hand, the amount of the recycled polyester raw material to be added is preferably 65 parts by mass or more, more preferably 70 to 95 parts by mass, when the total amount is 100 parts by mass.
If the amount of the mixture E is less than the above, the recycled polyester raw materials tend to block each other when the recycled polyester raw materials are added, which is not preferable because the stirrer is overloaded. If the amount of the mixture E is more than the above range, no particular problem will occur in the depolymerization reaction, but the use rate of the recycled raw material in the finally obtained regenerated polyester resin becomes low, which is not preferable.

In the step (1), when the recycled polyester raw material is added to the mixture E, the molar ratio of the total glycol component/total acid component is 1.10 to 1.35 while stirring, and the C. to obtain a depolymer having a melt viscosity of 10 to 1500 mPa.s.
This step is important in the production method of the present invention. That is, in the present invention, the recycled polyester raw material is depolymerized in the presence of the ethylene oxide adduct of ethylene glycol and bisphenol A. At this time, all of the ethylene oxide adduct of ethylene glycol and bisphenol A and the recycled polyester raw material are added so that the molar ratio of all glycol components/total acid components is 1.10 to 1.35, and depolymerization is carried out.

If the content of the component derived from the recycled polyester raw material in the recycled polyester resin obtained by the production method of the present invention is 70% by mass or more, in the step (1), the ethylene oxide adduct of ethylene glycol and bisphenol A And in addition to the recycled polyester raw material, ethylene terephthalate oligomer may be added for depolymerization. Also when adding ethylene terephthalate oligomer, it is necessary to carry out depolymerization so that the molar ratio of all glycol components/total acid components is 1.10 to 1.35.

As the ethylene terephthalate oligomer, for example, an esterification reaction product of ethylene glycol and terephthalic acid can be suitably used. The number average degree of polymerization of the ethylene terephthalate oligomer is not limited, but can be, for example, about 2-20.

In step (1), it is important to set the melt viscosity of the depolymer obtained by performing the above depolymerization to 10 to 1500 mPa·s.
By performing depolymerization by adjusting the molar ratio of all glycol components / all acid components and obtaining a depolymer with a melt viscosity of 10 to 1500 mPa s, not only various inorganic substances contained in recycled polyester raw materials, but also non- Since foreign substances derived from the polyester resin are deposited efficiently, these foreign substances can be completely filtered in the step (2).

Then, in the step (3) of adding and kneading the polycondensation catalyst and various additives added according to the application, it is possible to uniformly knead without aggregating the polycondensation catalyst and various additives. .
As a result, in the polycondensation reaction of the step (4), the characteristic values of the present invention are that the diethylene glycol content (copolymerization amount) and the carboxyl terminal group concentration are not more than a specific amount, and the amount of foreign matter mixed in. It is possible to obtain a recycled polyester resin with less

In the step (1) of the present invention, it is desirable that the depolymerization reaction described above decomposes the recycled polyester raw material into oligomers having about 5 to 20 repeating units without decomposing them into monomers.

If the molar ratio of the total glycol component/total acid component during the depolymerization reaction is outside the above range, the resulting recycled polyester resin will have at least one of the carboxyl terminal group concentration and the diethylene glycol content specified in the present invention. is not satisfied, and the average boosting speed is high. This is because, when the molar ratio of all glycol components/total acid components during the depolymerization reaction is outside the above range, precipitation of various inorganic substances in the recycled polyester raw material and foreign matters derived from non-polyester resins is efficiently carried out. Therefore, in the step (2), these foreign substances cannot be completely filtered out, and the foreign substances precipitate after the polycondensation reaction in the step (4), resulting in a recycled polyester resin with a high average pressurization rate. .

In addition, in the defusion reaction step (1), if the melt viscosity of the resulting depolymer is less than 10 mPa·s, the viscosity becomes too low, and liquid leakage occurs from the pipe and the filter connection portion during filtering of foreign matter. It is easy to filter, the filtration efficiency is poor, foreign matter cannot be filtered sufficiently, and productivity deteriorates. On the other hand, if the melt viscosity of the depolymer exceeds 1500 mPa s, the viscosity becomes too high, which increases the load on the stirring blade during the depolymerization reaction, and also increases the pressure when filtering foreign matter, resulting in production. sexuality worsens.

In the production method of the present invention, the reactor used in the step (1) has no particular problem with the capacity and shape of the stirring blades of a commonly used esterification reactor. In order to proceed, it is preferable to have a structure in which a distillation column is provided side by side so as not to distill ethylene glycol out of the system.
When the recycled polyester raw material is added, it is preferably stirred under normal pressure, and more preferably after purging with a small amount of inert gas (generally nitrogen gas is used).

In addition, when the depolymerization reaction is performed using an ester reactor, a method of performing the depolymerization reaction by adding a mixture of ethylene oxide adduct of ethylene glycol and bisphenol A to the recycled polyester raw material and performing the depolymerization reaction in multiple steps. Alternatively, it is preferable to employ a method in which a recycled polyester raw material is added little by little to a mixture containing ethylene glycol and an ethylene oxide adduct of bisphenol A.

When performing the depolymerization reaction, a melt extruder may be used instead of the ester reactor. In the method using a melt extruder, the polymer is sealed in the extruder and extruded, so there is no contact with air (especially oxygen), so there is no oxidative decomposition of the polymer, resulting in color deterioration and an increase in carboxyl end groups. The problem of viscosity reduction of the molten polymer associated with this does not occur. Moreover, if a melt extruder is used, the reaction can be carried out under all pressure conditions such as normal pressure, increased pressure, and reduced pressure.
The melt extruder may be either a single-screw extruder or a twin-screw extruder, but it is preferable to use a twin-screw extruder because the above advantages can be easily obtained.

Furthermore, when using a melt extruder in step (1), the depolymerization reaction proceeds inside the extruder by supplying ethylene glycol to the inside of the extruder. When supplying the recycled polyester raw material, adding ethylene glycol and passing it through a melt extruder makes it easier to lower the viscosity, and discharge from the tip nozzle becomes smooth. Also, the melting temperature of the melt extruder (the temperature of the depolymerization reaction) can be lowered by changing the pressure conditions to lower the viscosity.

The melt viscosity of the depolymerized product can be adjusted within the range of the present invention by appropriately adjusting the molar ratio of all glycol components/total acid components, heat treatment temperature, heat treatment time, pressure, etc. during depolymerization. Become.

The reaction temperature during depolymerization performed in step (1) is preferably carried out by setting the internal temperature of the reactor or melt extruder in the range of 245 to 280 ° C., especially the internal temperature in the range of 250 to 275 ° C. is more preferable. If the reaction temperature during depolymerization is less than 245°C, a long heat treatment is required to reduce the melt viscosity of the depolymerized product to 1500 mPa s or less, resulting in poor workability and the resulting recycled polyester resin. , the color tone deteriorates, and the content of diethylene glycol and the concentration of carboxyl terminal groups increase.
On the other hand, when the reaction temperature exceeds 280° C., the melt viscosity of the depolymerized product becomes too low, and the diethylene glycol content and carboxyl terminal group concentration of the resulting recycled polyester resin become high.
The reaction time at the time of depolymerization (reaction time after the completion of the addition of the recycled polyester raw material) is preferably within 4 hours, and within 2 hours from the viewpoint of suppressing the amount of by-product diethylene glycol and suppressing the deterioration of the color tone of the polyester. is more preferable.

In the step (2), the depolymerized product obtained by the depolymerization reaction in the step (1) is passed through a filter having a filtration particle size of 10 to 25 μm to filter out foreign matters. As described above, by performing a depolymerization reaction under the conditions of the step (1) and obtaining a depolymer having a melt viscosity within a specific range, even if the amount of recycled polyester raw material used is large, these raw materials Not only various inorganic substances abundantly contained in the resin, but also foreign substances derived from non-polyester resins are deposited efficiently. Therefore, by passing through a filter having a filtration particle size of 10 to 25 μm, the precipitated foreign matter can be completely caught by the filter, and a filtrate containing a small amount of foreign matter can be obtained.

If a filter with a filtration particle size of more than 25 μm is used, foreign matter in the depolymerized product cannot be sufficiently removed, and the resulting regenerated polyester resin contains a large amount of foreign matter. For this reason, when spinning is performed using such a resin, pressure rise in the nozzle pack and yarn breakage occur. On the other hand, when a filter having a filtration particle size of less than 10 μm is used, clogging due to foreign matter is likely to occur, and the filter life is shortened, which is disadvantageous in terms of cost and also deteriorates operability.

In addition, as the filter that can be used in the step (2) of the production method of the present invention, there is no particular problem with general filters, but examples thereof include screen changer filters, leaf disk filters, candle-type sintered filters, and the like.

Then, in step (3) of the production method of the present invention, the above-described polycondensation catalyst is added to the filtrate obtained through step (2) and kneaded to obtain a reaction product. In step (3), when additives are added according to various uses, they are preferably added together with the polycondensation catalyst and kneaded. In addition, the above-mentioned additive can be used for the additive added according to various uses.
The temperature at which kneading is performed in step (3) is preferably within the range of plus or minus 10° C. of the temperature at which polycondensation reaction is performed in step (4).

Next, as step (4), the reaction product obtained in step (3) is subjected to a polycondensation reaction in a polycondensation reactor at a temperature of 250° C. or higher and under reduced pressure of 1.0 hPa or lower.
If the polycondensation reaction temperature is less than 250°C or the pressure during the polycondensation reaction exceeds 1.0 hPa, the polycondensation reaction time will be long, resulting in poor productivity or slow progress of the polycondensation reaction. , the recycled polyester resin cannot be obtained.

More preferably, the polycondensation reaction temperature is 260° C. or higher. However, if the polycondensation reaction temperature is too high, the polymer will be colored due to thermal decomposition, and the color tone will deteriorate, and the amount of terminal groups (COOH) will increase due to thermal decomposition. , 285° C. or lower. The intrinsic viscosity of the recycled polyester resin (prepolymer) obtained here is preferably 0.44 to 0.80.

Furthermore, in order to increase the intrinsic viscosity of the recycled polyester resin, it is preferable to subject the prepolymer obtained by the polycondensation reaction to solid phase polymerization. At this time, the prepolymer is made into chips of any shape such as dice or cylinder, and the polyester chips are continuously supplied to a crystallizer and crystallized at a temperature of 150 to 190° C., and then placed in a dryer. After drying at a temperature of 190° C. or less for 4 to 16 hours, it is sent to a preheater and heated to the following solid phase polymerization temperature for 2 to 5 hours, and then continuously fed to a solid phase polymerizer. A polyester resin having a target intrinsic viscosity can be obtained by performing a solid phase polymerization reaction. Solid state polymerization is preferably carried out under an inert gas such as nitrogen gas. Solid phase polymerization is usually carried out at a temperature within the range of 170 to 230°C, more preferably within the range of 180 to 220°C. Moreover, the polymerization time is in the range of 20 hours to 80 hours, and the reaction is carried out in a solid phase polymerization machine.

The resin of the present invention can be molded into molded articles (blow molded articles, injection molded articles, sheets, films, etc.) excellent in color tone and transparency by adopting blow molding, injection molding, stretching methods, etc., and can be melt-spun. Fibers can also be obtained by
In both the molded product containing the resin of the present invention and the fiber containing the resin of the present invention, the content of the resin of the present invention is preferably 50% by mass or more of the resin constituting the molded product or fiber, and especially 60% by mass. % or more, more preferably 80 mass % or more, most preferably 100 mass %. If the proportion of the resin of the present invention in the resin constituting the molded product or fiber is less than 50% by mass, the usage rate of recycled raw materials will be low, making it difficult to produce environmentally friendly products.

Molded articles containing the resin of the present invention can be produced, for example, by applying various molding methods such as press molding, extrusion molding, air pressure molding and blow molding using raw materials containing the resin of the present invention. This makes it possible to provide various parts including containers. The resin of the present invention has properties close to those of virgin polyester resin and is particularly suitable for the production of blow-molded articles because of its excellent thermal stability. Therefore, it is possible to suitably employ a method for producing a molded article, which includes a step of obtaining a parison from a melt of a raw material containing the resin of the present invention and a step of blowing gas into the parison. Thereby, a molded body such as a container can be manufactured.

As described above, the resin of the present invention has excellent thermal stability because the content of diethylene glycol and the concentration of carboxyl terminal groups are not more than specific amounts. For this reason, when obtaining the above-mentioned molded article, it is possible to obtain a molded article with a high degree of uniformity with good workability without causing thickness unevenness or the like. Furthermore, as described above, the resin of the present invention has an average pressurization rate of 0.6 MPa/h or less, and contains a small amount of foreign matter. Inorganic substances and foreign substances derived from non-polyester resins are assumed to be the foreign substances present in the resin. can.

In the case of a molded article, a decrease in intrinsic viscosity and a deterioration in color tone after molding can be prevented by containing 0.1 to 1.0% by mass of a hindered phenolic antioxidant.

In the case of molded articles, it is preferable to contain a germanium-based compound and a cobalt compound as polymerization catalysts. The germanium compound is preferably contained in an amount of 5.0×10 ⁻⁵ to 3.0×10 ⁻⁴ mol per 1 mol of the acid component of the polyester. If it is less than 5.0×10 ⁻⁵ mol, it will be difficult to obtain a polyester resin with the desired degree of polymerization. On the other hand, when the amount exceeds 3.0×10 ⁻⁴ mol, by-products resulting from the reaction between the cobalt compound and the germanium compound deteriorate the stability of the polyester over time, resulting in a decrease in the intrinsic viscosity of the polyester resin composition after long-term storage, or This is not preferable because it causes deterioration of color tone.

Germanium compounds include germanium dioxide, germanium tetrachloride, germanium tetraethoxide, etc. Germanium dioxide is preferred from the viewpoints of polymerization catalyst activity, physical properties of the obtained polyester resin, and cost.

The content of the cobalt compound must be 1.0×10 ⁻⁵ mol to 1.0×10 ⁻⁴ mol per 1 mol of the acid component of the polyester, and 2.0×10 ⁻⁵ mol to 8 mol. .0×10 ⁻⁵ mol is preferred.
less than 1.0×10 ⁻⁵ mol. Color tone of polyester deteriorates. On the other hand, if the amount exceeds 1.0×10 ⁻⁴ mol, the stability of the polyester resin over time will also deteriorate. Cobalt compounds include cobalt acetate, cobalt formate, cobalt chloride, cobalt oxide, etc. Cobalt acetate is preferred from the viewpoint of polymerization catalyst activity, physical properties of the obtained polyester resin, and cost.

In the case of fibers containing the resin of the present invention, the fibers can be produced by, for example, a manufacturing method including a step of melting and spinning a raw material containing the resin of the present invention. This makes it possible to produce, for example, ultrafine fibers having a single filament fineness of 0.8 dtex or less (preferably 0.6 to 0.3 dtex). The spinning method and the like can be carried out according to known conditions.

As described above, the resin of the present invention has a relatively low content of foreign matter and has properties equivalent to those of virgin polyester resin, so that there is a problem of yarn breakage in any of the melt spinning, drawing / heat treatment, and winding processes. is less likely to occur, and polyester fibers can be obtained with good productivity.

The fibers of the present invention containing the resin of the present invention may be, for example, monofilaments, multifilaments, or the like, and may be long fibers, short fibers, or the like.

EXAMPLES Next, the present invention will be specifically described using examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(a) Melt Viscosity of Depolymer The depolymer obtained in production step (1) was measured using a VISCO METER DV2T melt viscometer manufactured by Brookfield at the same temperature as the treatment temperature during depolymerization.
(b) Intrinsic viscosity The intrinsic viscosity is measured at a temperature of 20°C using the obtained recycled polyester resin and an equal mass mixture of phenol and ethane tetrachloride as a solvent.
(c) Composition of polyester resin The obtained polyester resin is dissolved in a mixed solvent having a volume ratio of deuterated hexafluoroisopropanol and deuterated chloroform of 1/20, and is subjected to an LA-400 type NMR device manufactured by JEOL Ltd. 1H-NMR was measured at , and the type and content of the copolymer component were determined from the integrated intensity of the proton peak of each component in the obtained chart.
(d) Carboxyl Terminal Group Concentration Dissolve 0.1 g of the obtained recycled polyester resin in 10 ml of benzyl alcohol, add 10 ml of chloroform to this solution, and titrate with a 1/10 N potassium hydroxide benzyl alcohol solution. rice field.
(e) Average pressurization rate measured by pressurization tester The obtained recycled polyester resin is melted at 300 ° C. in an extruder, and a stainless steel twilled woven filter (nominal size mesh: 1400 mesh, weave: twill weave, vertical mesh: 165 mesh, horizontal mesh: 1400 mesh, vertical wire diameter: 0.07 mm, horizontal wire diameter: 0.04 mm, filtration particle size: 12 μm, viscous drag coefficient (m ⁻¹ ) : 2.60 × 10 ⁷ , inertial resistance coefficient: 5.14 × 10, manufactured by Kamijo Seiki Co., Ltd.), and a reinforcing material (stainless steel plain weave wire mesh (nominal size mesh: 40 mesh, Weaving method: plain weave, wire diameter: 0.21 mm (manufactured by Kamijo Seiki Co., Ltd.) After laminating, the polymer discharge rate is set to 29.0 g / min, and the filter pressure is increased using a pressurization tester; "Measured using a detector. The pressure rise test using the pressure test machine was performed continuously for 12 hours, and the initial pressure value (MPa) when starting the pressure rise test (5 to 5 after the polyester resin started passing through the filter The initial pressure is the minimum value of the pressure for 10 minutes.) and the final pressure value (MPa) after 12 hours, the average pressure increase rate was calculated by the following formula.
Average pressure rise rate (MPa/h) = (final pressure value - initial pressure value)/12
(f) Melting point and glass transition temperature The obtained recycled polyester resin is heated (decreased) in a nitrogen stream in a temperature range of 25°C to 280°C using a differential scanning calorimeter (Diamond DSC) manufactured by PerkinElmer. Measurement was performed at a speed of 20°C/min and a sample amount of 8 mg.

(g) Formability The thickness of the trunk portion of the obtained containers (100 samples) was measured, and those with a thickness difference of up to 0.30 mm between the thickest and thinnest portions were accepted. At this time, when 90 or more samples passed the test, it was evaluated as ◯, and the moldability was evaluated as good.
(h) Haze A sample piece (20 pieces) was cut out from the obtained container, and the turbidity was measured with a turbidity meter MODEL 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. (air: haze 0%), n number 20 was taken as the average value of The smaller this value, the better the transparency, and the value of 6% or less was judged to be excellent in transparency.
(i) Impact resistance (g) The molded product (100 samples) that passed the moldability evaluation was filled with 340 ml of tap water and placed on a P tile at room temperature at a height of 200 cm. Then, the molded body was dropped once with the bottom surface facing downward and the side surface facing downward. When the number of molded bodies that did not crack at this time was 90 or more, it was evaluated that the impact resistance was good.

Example 1
[Recycled polyester resin]
37.6 parts by mass of recycled polyester raw material (recycled PET flakes made from used products) was charged into an esterification reactor, and then 4.4 masses of ethylene glycol (EG) was added while the stirrer of the esterification reactor was turned. and 1.6 parts by mass of an ethylene oxide adduct of bisphenol A (hereinafter referred to as BAEO) were added. 56.4 parts by mass of recycled polyester raw material (recycled PET flakes made from used products) was fed through a rotary valve from the point where the internal temperature of the esterification reactor (hereinafter referred to as "ES can") stopped falling. , was metered in over about 2 hours.
At this time, the recycled polyester raw material was added so that the molar ratio of all glycol components/total acid components (hereinafter sometimes referred to as G/A) was 1.16.
Thereafter, a depolymerization reaction was carried out under heat treatment conditions of 260°C for 1 hour to obtain a depolymer having a melt viscosity of 40 mPa·s at 260°C.
A candle filter with an opening of 20 μm was set between the esterification reactor and the polycondensation reactor, and the obtained depolymerized product was pressure-fed to the polycondensation reactor (hereinafter referred to as a PC can). At this time, the filtrate was recovered by passing the depolymerized product through the filter.
In the PC can, antimony trioxide was added as a polymerization catalyst to the filtrate in an amount of 1.0×10 ⁻⁴ mol per 1 mol of the acid component of the polyester, and tetrakis[methylene-3] was added as a hindered phenolic antioxidant. -(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (manufactured by ADECA Co., Ltd.: Adekastab AO-60) was added so as to be 0.2% by mass with respect to the obtained polyester resin, and the temperature was 280. ℃ to obtain a reaction product.
Next, the PC can was evacuated and after 60 minutes, polycondensation reaction was carried out at a final pressure of 0.5 hPa and a temperature of 280° C. for 4 hours to obtain recycled polyester resin A (intrinsic viscosity of 0.66).
Subsequently, the obtained recycled polyester resin A was continuously supplied to a crystallizer, crystallized at 150°C, supplied to a dryer, dried at 130°C for 10 hours, and sent to a preheater at 180°C. After heating to , it was supplied to a solid phase polymerizer. Then, a solid phase polymerization reaction was carried out at 190° C. for 50 hours under nitrogen gas to obtain a recycled polyester resin B having an intrinsic viscosity of 1.1.
[Blow molded product]
After chipping the obtained recycled polyester resin B and drying it, the resin is extruded at an extrusion temperature of 280° C. using a direct blow molding machine (manufactured by Tahara Co., Ltd.) to form a cylindrical parison, and the parison is in a softened state. It was sandwiched between molds, the bottom part was formed, and this was blown to form a bottle. At this time, when the parison had a diameter of 3 cm and a length of 25 cm, the bottom was formed and blow-molded to obtain a 350-ml hollow container (direct blow molded product).

Example 2
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol, and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, the same procedure as in Example 1 was carried out except that the drying conditions in the dryer were 160°C for 8 hours, the heating temperature in the preliminary dryer was 190°C, and the solid phase reaction time was 60 hours. Solid-phase polymerization was carried out in a place where B was obtained as a recycled polyester resin having a limiting viscosity of 1.23.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 3
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol, and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, solid phase polymerization was performed in the same manner as in Example 1 except that the drying conditions of the dryer were 160 ° C. for 8 hours and the heating temperature of the preliminary dryer was 190 ° C. A recycled polyester resin B having a viscosity of 1.14 was obtained.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 4
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol, and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, solid phase polymerization was performed in the same manner as in Example 1 except that the drying conditions of the dryer were 120 ° C. for 18 hours and the heating temperature of the preliminary dryer was 175 ° C. A recycled polyester resin B having a viscosity of 1.12 was obtained.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 5
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol, and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, the same procedure as in Example 1 was carried out except that the drying conditions in the dryer were 110°C for 24 hours, the heating temperature in the preliminary dryer was 170°C, and the solid phase reaction time was 60 hours. Solid-phase polymerization was carried out using the same method, and a recycled polyester resin B having an intrinsic viscosity of 1.26 was obtained.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 6
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, a solid phase polymerization reaction was performed in the same manner as in Example 2 except that the solid phase polymerization reaction was performed for 15 hours, thereby obtaining a recycled polyester resin B having an intrinsic viscosity of 0.75. .
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 7
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, a solid phase polymerization reaction was performed in the same manner as in Example 2 except that the solid phase polymerization reaction was performed for 35 hours, thereby obtaining a recycled polyester resin B having an intrinsic viscosity of 1.14. .
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Examples 8 and 9
A recycled polyester resin A was obtained in the same manner as in Example 1, except that the heat treatment temperature in the depolymerization step was changed to the temperature shown in Table 1. Then, using the obtained recycled polyester resin A, the solid phase polymerization reaction was performed in the same manner as in Example 1 except that the solid phase polymerization reaction time was set to 35 hours. Resin B was obtained.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 10
A recycled polyester resin A was obtained in the same manner as in Example 7, except that the heat treatment temperature in the depolymerization step was changed to the temperature shown in Table 1. Using the obtained recycled polyester resin A, a solid-phase polymerization reaction was carried out in the same manner as in Example 7 to obtain a recycled polyester resin B having an intrinsic viscosity of 1.14.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Example 11
A recycled polyester resin A was obtained in the same manner as in Example 3, except that the heat treatment temperature in the depolymerization step was changed to the temperature shown in Table 1. Using the obtained recycled polyester resin A, a solid-phase polymerization reaction was performed in the same manner as in Example 3 to obtain a recycled polyester resin B having an intrinsic viscosity of 1.14.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Examples 12 and 13
A recycled polyester resin A was obtained in the same manner as in Example 3, except that the filtration particle size of the filter in the step of collecting the filtrate was changed to that shown in Table 1. Using the obtained recycled polyester resin A, a solid-phase polymerization reaction was carried out in the same manner as in Example 3 to obtain recycled polyester resin B having intrinsic viscosities of 1.01 and 1.05.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Comparative example 1
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol, and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, a solid phase polymerization reaction was performed in the same manner as in Example 2 except that the solid phase polymerization reaction was performed for 35 hours, thereby obtaining a recycled polyester resin B having an intrinsic viscosity of 0.99. .
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Comparative example 2
Recycled polyester resin A was prepared in the same manner as in Example 1, except that the amounts of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction and the G/A values were changed as shown in Table 1. Obtained. Then, using the obtained recycled polyester resin A, a solid phase polymerization reaction was performed in the same manner as in Example 4 except that the solid phase polymerization reaction was performed for 80 hours, thereby obtaining a recycled polyester resin B having an intrinsic viscosity of 1.29. .
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Comparative example 3
Example 1 was repeated except that the heat treatment temperature in the depolymerization step was changed to the temperature shown in Table 1. However, the contents solidified in the reactor, making it impossible to continue the reaction thereafter.

Comparative example 4
A recycled polyester resin A was obtained in the same manner as in Example 1, except that the heat treatment temperature in the depolymerization step was changed to the temperature shown in Table 1. Then, using the obtained recycled polyester resin A, a solid phase polymerization reaction was performed in the same manner as in Example 1 except that the solid phase polymerization reaction was performed for 65 hours, thereby obtaining a recycled polyester resin B having an intrinsic viscosity of 1.31. .
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Comparative example 5
Same as Example 1, except that the amount of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction, G/A, and the heat treatment temperature in the depolymerization step were changed to the values shown in Table 1. to obtain a recycled polyester resin A. Using the obtained recycled polyester resin A, a solid-phase polymerization reaction was carried out in the same manner as in Example 1, but fusion occurred during the solid-phase polymerization, and the solid-phase polymerization reaction could not be carried out.

Comparative example 6
Same as Example 1, except that the amount of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction, G/A, and the heat treatment temperature in the depolymerization step were changed to the values shown in Table 1. As a result, the melt viscosity of the depolymer obtained in the depolymerization step was too low. For this reason, the filtrate leaked when passing through the filter in the filtration process, and it was not possible to proceed to the next process.

Comparative example 7
Same as Example 1, except that the amount of ethylene glycol, cyclohexanedimethanol and recycled polyester raw material added during the depolymerization reaction, G/A, and the heat treatment temperature in the depolymerization step were changed to the values shown in Table 1. As a result, the melt viscosity of the depolymer obtained in the depolymerization step was too high. For this reason, it became difficult to pass through the filter in the filtration process, and it was not possible to proceed to the next process.

Comparative example 8
A recycled polyester resin A was obtained in the same manner as in Example 3, except that the filtration particle size of the filter in the step of collecting the filtrate was changed to that shown in Table 1. Using the obtained recycled polyester resin A, a solid-phase polymerization reaction was carried out in the same manner as in Example 3 to obtain a recycled polyester resin B of 1.15.
A hollow container was obtained in the same manner as in Example 1 using the obtained recycled polyester resin B.

Comparative example 9
The same procedure as in Example 3 was carried out, except that the filtration particle size of the filter in the step of collecting the filtrate was changed to that shown in Table 1, but clogging occurred during filtration, and the process could proceed to the polycondensation reaction. No resin was obtained.

Comparative example 10
The procedure of Example 1 was repeated except that the heat treatment temperature in the polycondensation reaction step was changed to that shown in Table 1. However, since the heat treatment temperature was low, the polycondensation reaction did not proceed sufficiently, and recycled polyester resin A was obtained. I couldn't.

Table 1 shows the characteristic values and evaluation results of the recycled polyester resin B and the hollow container obtained in Examples 1 to 13 and Comparative Examples 1, 2, 4, 5, and 8.

As is clear from Table 1, the recycled polyester resin B obtained in Examples 1 to 13 has a BAEO copolymerization amount, an intrinsic viscosity, a carboxyl terminal group content, a diethylene glycol content, and an average pressurization rate specified by the present invention. Since the content was within the range, the amount of foreign matter mixed in was small, and the thermal stability was excellent. Therefore, a hollow container excellent in transparency and impact resistance could be obtained with good moldability without causing the problem of whitening due to crystallization during blow molding.

On the other hand, in Comparative Example 1, since the G/A at the time of the depolymerization reaction was low, the obtained recycled polyester resin had a high carboxyl terminal group concentration and a high average pressurization rate. In addition, since the carboxyl terminal group concentration was high, the recycled polyester resin was thermally decomposed during molding, resulting in poor haze of the resulting molded product, and deterioration in moldability and impact resistance.
In Comparative Example 2, since the G/A at the time of the depolymerization reaction was high, the recycled polyester resin obtained had a high content of diethylene glycol and a high average pressurization rate. In addition, since the content of diethylene glycol was high, the recycled polyester resin was thermally decomposed during molding, and the haze of the obtained molded article was poor, and the moldability and impact resistance were also deteriorated.
In Comparative Example 4, since the heat treatment temperature in the depolymerization step was too high, the resulting recycled polyester resin had a high carboxyl terminal group concentration and a high diethylene glycol content. In addition, since both the carboxyl terminal group concentration and the diethylene glycol content were high, thermal decomposition of the recycled polyester resin occurred during molding, resulting in poor haze, moldability and impact resistance.
In Comparative Example 5, since the amount of BAEO copolymerized was large, fusion occurred during solid phase polymerization, and the solid phase polymerization reaction could not be performed. As a result, the resulting recycled polyester resin had a low intrinsic viscosity and could not be subjected to direct blow molding.
In Comparative Example 8, since the filtration particle size of the candle filter provided between the ES can and the PC can was 30 μm, the resulting recycled polyester resin contained a large amount of foreign matter and had a high average pressurization rate. Therefore, the obtained blow-molded article had a high haze and was inferior in transparency.

Claims (3)

A polyester resin containing 70% by mass or more of a component derived from at least one recycled polyester raw material of a) used polyester products and b) unadopted polyester resin generated in the process of manufacturing polyester products, wherein the following (1) A recycled polyester resin characterized by satisfying all of (4).
(1) When the total amount of all acid components constituting the polyester is 100 mol%, 70 mol% or more is terephthalic acid,
(2) When the total amount of all glycol components is 100 mol%, 60 to 99 mol% is ethylene glycol, 1 to 20 mol% is an ethylene oxide adduct of bisphenol A, and 4 mol% or less is diethylene glycol. and
(3) a carboxyl terminal group concentration of 40 equivalents/t;
(4) The average pressurization rate is 0.6 MPa / h or less (however, the average pressurization rate is a value calculated by the following procedure: Using a pressurization tester including an extruder and a pressure sensor, the extruder Stainless steel filter at the tip (nominal size mesh: 1400 mesh, weaving method: twilled dutch, vertical mesh: 165 mesh, horizontal mesh: 1400 mesh, vertical wire diameter: 0.07 mm, horizontal wire diameter: 0.04 mm, filtration particle size : 12 μm) is set, the polyester resin is melted at 300 ° C. with an extruder, and the pressure value applied to the filter when extruding the melt at a discharge rate of 29.0 g / min from the filter is the start of extrusion. If the pressure value at the time of extrusion is defined as "initial pressure value (MPa)" and the pressure value at the time of continuous extrusion for 12 hours is defined as "final pressure value (MPa)", the following calculation is based on those pressure values. Calculate the average pressure rise rate by Equation A:
Average pressure increase rate (MPa/h) = (final pressure value - initial pressure value) / 12) ... A) A blow-molded article containing the recycled polyester resin according to claim 1. A method for producing a recycled polyester resin using at least one recycled polyester raw material of a) a used polyester product and b) an unused polyester resin generated in the process of producing a polyester product, the method comprising the following (1) to ( 4) A method for producing a recycled polyester resin, comprising all of the steps.
(1) To a mixture containing ethylene glycol and an ethylene oxide adduct of bisphenol A, a recycled polyester raw material is added so that the molar ratio of all glycol components/total acid components is 1.10 to 1.35, and 245 A step (2) of obtaining a depolymer having a melt viscosity of 10 to 1500 mPa·s by performing depolymerization under heat treatment conditions of up to 280° C. (2) passing the depolymer through a filter having a filtration particle size of 10 to 25 μm to obtain a filtrate; Step of collecting (3) adding a polycondensation catalyst to the filtrate and kneading to obtain a reaction product; process