JP2022063218A - Recycled polyester resin and method for producing recycled polyester resin - Google Patents

Abstract

To provide a copolyester resin derived from recycled polyester material.SOLUTION: A recycled polyester resin contains a component derived from recycled polyester material, the recycled polyester resin satisfying all of the following (1)-(4): (1) with the total amount of acid components constituting polyester being 100 mol%, 50-98 mol% is terephthalic acid and 2-50 mol% is isophthalic acid; (2) with the total amount of glycol components being 100 mol%, ethylene glycol is 80 mol% or more and diethylene glycol is 4 mol% or less; (3) the content of carboxyl terminal groups is 40 eq./t or less; and (4) the average rate of pressure rise is 0.6 MPa/h or less.SELECTED DRAWING: None

Description

The present invention relates to a novel recycled polyester resin and a method for producing a recycled polyester resin. In particular, the present invention is manufactured using a recycled polyester raw material derived from a used polyester product and a recycled polyester raw material derived from an unadopted polyester generated in the process of manufacturing the polyester product, and the amount of foreign matter mixed is small. The present invention relates to a recycled polyester resin that can be processed into various molded products in the same manner as a virgin polyester resin, and a method for producing the same.

Polyethylene terephthalate (hereinafter, may be abbreviated as PET) is widely used for molded products such as fibers, films, and PET bottles because of its high melting point, chemical resistance, and relatively low cost. ..
These polyester products inevitably generate waste at the manufacturing and processing stages, and are often disposed of after use.However, when incinerating, high heat is generated, so the incinerator is severely damaged and has a long life. There is a problem that becomes shorter. On the other hand, if it is not incinerated, it will remain semi-permanently because it will not decompose.
Of the polyester products that have been used once in recent years, plastic containers that have been thrown away as garbage flow out 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 and become food. The fact that it is concentrated in a chain and has an adverse effect on the ecosystem of marine organisms, and that plastics are a major cause of marine pollution are regarded as problems, and there is a worldwide movement to reduce usage and switch to biodegradable plastics. Is happening.

From the viewpoint of reducing the amount of such plastic products used and from the viewpoint of environmental problems, recycling that reuses resources is carried out by various methods. With regard to polyester products, methods of recycling polyester waste generated in the manufacturing process and methods of collecting and reusing products that have once been on the market and discarded are being studied. In particular, in recent years, with regard to textile products, products bearing the Eco Mark, which is certified by achieving a certain recycling rate, have become widespread.

Various methods have been proposed as a method for recycling recycled polyester raw materials. For example, a method of adding methanol to PET waste and decomposing it into dimethylene terephthalate (hereinafter, may be referred to as “DMT”) and ethylene glycol (hereinafter, may be referred to as “EG”) (Patent Document 1). ), A method of adding EG to PET waste and depolymerizing it, and then adding methanol to recover DMT (Patent Document 2). PET waste is depolymerized with EG to form an oligomer, which is used for the polycondensation reaction. A method (Patent Document 3) and the like have been proposed.

In addition, when regenerating PET bottles that have become products once, the problems are the additives added to the polyester resin and the caps (aluminum, polypropylene, polyethylene) and inner plugs that are attached to the bottle body. , Liners (polypropylene, polyethylene), labels (paper, resins such as polystyrene, inks), adhesives, printing inks, etc.
As a pretreatment for the regeneration process, first, the collected PET bottles are subjected to a vibration sieve to remove sand, metal and the like. Then, the PET bottle is washed, the colored bottle is separated, and then rough pulverization is performed. Then, the label etc. are removed by wind power separation. Further, the PET bottle piece is finely crushed except for the aluminum piece derived from the cap or the like. Components such as adhesives, proteins and molds are removed by high-temperature alkaline cleaning, and dissimilar components such as polypropylene and polyethylene are separated by specific gravity.

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

Further, the invention described in Patent Document 4 describes a method of depolymerizing polyester waste with ethylene glycol, filtering it with a filter having an average opening of 10 to 50 μm, and then performing a repolymerization reaction. It has been shown that the obtained recycled polyester resin has a small amount of foreign matter mixed in and is excellent in operability during processing. However, even in this method, the foreign matter derived from the non-polyester resin as described above could not be sufficiently removed, and the amount of the foreign matter mixed could not be sufficiently reduced.

Generally, when manufacturing plastic bottles, melt-plasticized resin is used as a die orifice because of its ease of molding, high productivity, and relatively low equipment costs for molding machines and dies. A so-called blow molding method is adopted in which a cylindrical parison is formed by extruding through a mold, sandwiched between molds, and air is blown into the inside. The use of recycled polyester resin in such blow-molded products is also being considered from the viewpoint of environmental problems.

Since crystallization is likely 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 the transparency, a polyester resin obtained by copolymerizing polyethylene terephthalate with another monomer component has been proposed (see, for example, Patent Document 5).

Further, in general, hot melt type binder fibers are widely used for the purpose of adhering fibers constituting stuffing for pillows and bedding, quilting stuffing, mattress stuffing and the like. Among them, a copolymerized polyester resin containing terephthalic acid, isophthalic acid and ethylene glycol as main components is widely used as the polyester-based binder fiber.

As described above, although there is a great demand for copolymerized polyester resins using recycled polyester raw materials in various molded products and textile products, not only various inorganic substances but also foreign substances derived from non-polyester resins can be sufficiently removed. , A copolymerized polyester resin capable of obtaining various high-quality products similar to the virgin polyester resin has not yet been obtained.

Special Publication No. 42-8855 Japanese Unexamined Patent Publication No. 48-62732 Japanese Unexamined Patent Publication No. 60-248646 Japanese Unexamined Patent Publication No. 2005-171138 Japanese Patent No. 6297351

The present invention solves the above problems and is a copolymerized polyester made from a recycled polyester raw material derived from a used polyester product, or a recycled polyester raw material derived from polyester resin and waste generated in the process of manufacturing the product. It is an object of the present invention to provide a recycled polyester resin which is a resin and can be used for manufacturing various forms of polyester products. Another object of the present invention is to provide a manufacturing method capable of obtaining such a recycled polyester resin of the present invention.

As a result of diligent research in view of the problems of the prior art, the present inventor has a small amount of foreign matter mixed in by a specific manufacturing method using a recycled polyester raw material, and has the same thermal stability as a virgin polyester resin. They have found that a recycled polyester resin can be obtained, and have completed the present invention.

That is, the gist of the present invention is the following (a) to (e).
(A) A polyester resin containing a component derived from at least one recycled polyester raw material of a) used polyester product and b) unadopted polyester generated in the process of manufacturing the polyester product, and the following (1) to 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%, 50 to 98 mol% is terephthalic acid and 2 to 50 mol% is isophthalic acid.
(2) When the total amount of all glycol components is 100 mol%, ethylene glycol is 80 mol% or more and diethylene glycol is 4 mol% or less.
(3) The carboxyl terminal group concentration is 40 equivalents / t, and the concentration is 40 equivalents / t.
(4) The average boosting speed is 0.6 MPa / h or less (however, the average boosted speed is a value calculated by the following procedure: using a booster tester including an extruder and a pressure sensor, the extruder Stainless steel filter at the tip (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 grain size : 12 μm) is set, the polyester resin is melted at 300 ° C. with an extruder, and the extruding is started as the pressure value applied to the filter when the melt is extruded at a discharge rate of 29.0 g / min from the filter. When the pressure value at the time is "initial pressure value (MPa)" and the pressure value at the time of continuous extrusion for 12 hours is "final pressure value (MPa)", the following calculation is performed based on those pressure values. The above average boosting speed is calculated by the formula A:
Average boost rate (MPa / h) = (final pressure value-initial pressure value) / 12) ... A)
(B) The regenerated polyester resin (c) (a) or (b) according to (a), wherein 1 to 10 mol% of an ethylene oxide adduct of bisphenol A is contained as a glycol component in the above (2). Molded product containing recycled polyester resin.
(D) A fiber containing the recycled polyester resin according to (a) or (b).
(E) A method for manufacturing a recycled polyester resin using at least one recycled polyester raw material of unadopted polyester generated in the process of manufacturing a used polyester product and b) a polyester product, which is described in (1) below. )-(3) The method for producing a recycled polyester resin, which comprises the steps of (3).
(1) A recycled polyester raw material is added to a mixture containing an ethylene terephthalate oligomer, ethylene glycol and isophthalic acid so that the molar ratio of the total glycol component / total acid component is 1.05 to 1.20, and 245 to 280. Step of obtaining a reaction product containing a depolymerized product by performing depolymerization under heat treatment conditions at ° C. (2) A step of passing the reaction product through a filter having a filtration particle size of 10 to 25 μm and recovering the filtrate (3). A step of adding a polymerization catalyst to the filtrate and performing a polycondensation reaction of the depolymerized product under a reduced pressure of 250 ° C. or higher and 1.0 hPa or lower.

The recycled polyester resin of the present invention contains at least one recycled polyester raw material of a) used polyester product and b) unadopted polyester generated in the process of manufacturing the polyester product, but has a small amount of foreign matter mixed in. Moreover, the carboxyl terminal group concentration and the diethylene glycol content satisfy a specific range, and the thermal stability is excellent. For this reason, for example, in the process of obtaining fibers by melt spinning, the process of obtaining a sheet or film by film formation, and the process of obtaining molded products such as bottles, continuous operation for a relatively long period of time becomes possible, and products of various forms with good productivity are possible. Can be manufactured. Since it is a recycled polyester resin but contains a copolymerizable component, it is suitably used for various applications such as molded products such as bottles that require transparency and textile applications that require adhesiveness. Can be done.

Further, according to the method for producing a recycled polyester resin of the present invention, it is possible to obtain the recycled polyester resin of the present invention having a copolymerization component at low cost with good operability without requiring complicated processes and equipment. , Practical merit is great.

Hereinafter, the present invention will be described in detail.
The recycled polyester resin of the present invention (resin of the present invention) is a polyester resin containing a component derived from at least one recycled polyester raw material of a) used polyester product and b) unadopted polyester generated in the process of manufacturing the polyester product. Is. These components are a part of the polyester constituting the resin of the present invention.

Examples of the used polyester product in a) above include polyester molded products (including fibers) that have been put on the market once and collected after use. A typical example thereof is a container such as a PET bottle or a packaging material.
The unadopted polyester generated in the process of manufacturing the polyester product of b) above is a polyester that has not been commercialized, for example, non-standard resin pellets, materials that are no longer needed during molding, and fragments cut during molding. , Waste generated during molding, processing, etc., cut products of transition products generated at the time of brand change, cut products of prototypes / defective products, etc.

The forms of a) and b) are not limited, and they may be pelletized by further processing such as crushing or cutting as necessary, or may be melted and pelletized. good.
The above a) and b) may be used alone or a mixture of both may be used. Further, the recycled polyester raw materials of a) and b) may be either crystalline or amorphous. Therefore, for example, pellets of amorphous polyester waste that have not been heat-treated, crystalline pellets that have been heat-treated, a mixed product of crystalline pellets and amorphous pellets, and the like can be used. In the present invention, it is particularly preferable to use a crystalline recycled polyester raw material for the purpose of preventing fusion of pellets to each other during charging into a can or depolymerization reaction. Therefore, the material of the above a) or b) crystallized by heat treatment (crystallized pellets or the like) can be preferably used.
The properties of the recycled polyester raw materials of a) and b) are not limited, and the forms of a) and b) may be used as they are, and the cut pieces obtained by further processing such as cutting and crushing may be used. In addition to crushed products (powder) and the like, solid forms such as molded bodies (pellets and the like) obtained by molding these can be mentioned. More specifically, pellets obtained by cooling and cutting a melt of polyester waste, cut pieces obtained by finely cutting a polyester molded product such as a PET bottle, and the like are exemplified. In addition, it may be in the form of a liquid obtained by dispersing or dissolving the above-mentioned cut pieces, crushed material (powder) or the like in a solvent. When producing polyester products using these raw materials, if necessary, they can be melted at a temperature equal to or higher than the melting point and charged into a can as a melt.

The recycled polyester resin of the present invention preferably contains 40% by mass or more, and more preferably 50% by mass or more, of a component derived from the recycled polyester raw material which is at least one of the above a) and b).
If the content of the component derived from the recycled polyester raw material is less than 40% by mass, the purpose of considering the environmental problem cannot be achieved. The upper limit of the content of the recycled polyester raw material is not particularly limited, but according to the production method of the present invention described later, the recycled polyester resin containing 40 to 80% by mass of the component derived from the recycled polyester raw material. Can be easily obtained.

In the resin of the present invention, when the total amount of all acid components constituting the polyester is 100 mol%, 50 to 98 mol% is terephthalic acid and 2 to 50 mol% is isophthalic acid. That is, terephthalic acid is the main component of the acid component, and isophthalic acid is the copolymerization component.
The copolymerization amount of isophthalic acid is preferably adjusted in the range of 2 to 50 mol% depending on the use of the obtained recycled polyester resin. For example, when used for molding purposes, the copolymerization amount of isophthalic acid is preferable. Is preferably 2 to 15 mol%. Above all, it is preferably 3 to 10 mol%, more preferably 4 to 8 mol%. By copolymerizing 2 to 15 mol% of isophthalic acid, the crystallization rate of the polyester resin can be adjusted to be suitable for direct blow molding, and whitening due to crystallization during direct blow molding can be prevented. The melting point of the obtained recycled polyester resin is preferably 210 to 250 ° C.

If the copolymerization amount of isophthalic acid is less than 2 mol%, the crystallization rate of the resin composition becomes high, so that the molded product crystallizes and whitens during direct blow molding, resulting in inferior transparency. It becomes. On the other hand, when the copolymerization amount of isophthalic acid exceeds 15 mol%, the resin composition becomes amorphous, so that blocking is likely to occur at the time of high temperature drying or in the solid phase polymerization step.

Further, when the fiber is used as a main fiber, the copolymerization amount of isophthalic acid is preferably 2 to 15 mol%, and more preferably 2 to 10 mol%. By copolymerizing 2 to 15 mol% of isophthalic acid, the main fiber has performance such as appropriate strength, and is suitable for obtaining products such as non-woven fabrics and woven and knitted fabrics. The melting point of the obtained recycled polyester resin is preferably 210 to 250 ° C.
When used for binder fiber applications, the copolymerization amount of isophthalic acid is preferably 15 to 50 mol%, particularly preferably 20 to 40 mol%. By copolymerizing 15 to 50 mol% of isophthalic acid, the melting point of the polyester resin can be lowered or the polyester resin can be made amorphous, which can be suitable for binder use. The melting point of the obtained recycled polyester resin is preferably 190 to 210 ° C., and when it does not have a melting point, the glass transition temperature is preferably 62 to 80 ° C.

When the copolymerization amount of isophthalic acid is less than 15 mol%, the melting point of the resin becomes high, which is not suitable for binder fiber use. On the other hand, if the copolymerization amount of isophthalic acid exceeds 50 mol%, the crystallinity and the glass transition temperature of the obtained resin composition are excessively lowered, and it becomes difficult to perform melt spinning and drawing to form fibers.

The ratio of terephthalic acid in the acid component is 50 to 98 mol%, and the ratio of terephthalic acid is preferably 60 to 97 mol%. When the proportion of terephthalic acid is less than 50 mol%, the crystallinity of the resin composition is lowered and it tends to be amorphous. On the other hand, when the ratio of terephthalic acid exceeds 98 mol%, the amount of isophthalic acid copolymerized decreases, so that it becomes difficult to achieve the effect obtained by copolymerizing isophthalic acid in various products.

Examples of the acid component other than terephthalic acid and isophthalic acid in the resin of the present invention include phthalic acid, 5-sophthalosulfisophthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, adipic acid, sebacic acid, dimer acid and the like. Two or more kinds may be used in combination, and ester-forming derivatives of these acids may be used.

In the resin of the present invention, when the total amount of the total glycol components is 100 mol%, ethylene glycol is 70 mol% or more of the total glycol components, and more preferably 80 mol% or more. When the content of ethylene glycol is less than 70 mol%, the crystallinity and heat resistance of the obtained polyester resin are inferior.

Further, in the resin of the present invention, when the total amount of all glycol components is 100 mol%, the content of diethylene glycol is 4 mol% or less, and more preferably 3 mol% or less. 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 the 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 produced as a by-product, and has excellent thermal stability because the content of diethylene glycol is 4 mol% or less. Therefore, it is possible to obtain molded products such as fibers, injection molded products, various blow molded products, sheets, and films with high productivity. The lower limit of the content of diethylene glycol can be, for example, about 0.5 mol%, but is not limited to this.

In the resin of the present invention, examples of the diol component other than ethylene glycol and diethylene glycol in the total glycol component include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. 1,4-Cyclohexanedimethanol, diethylene glycol, dimerdiol, ethylene oxide adduct of bisphenol S, ethylene oxide adduct of bisphenol A and the like can be used.

Above all, when the resin of the present invention is used for the main fiber application among the fiber applications, it is preferable that the ethylene oxide adduct of bisphenol A is contained as a 1 to 10 mol% copolymerization component, and above all, 2 to 8 mol. % Is preferably contained. By copolymerizing the ethylene oxide adduct of bisphenol A, the resulting fiber can be imparted with shrinkage. If the copolymerization amount of the ethylene oxide adduct of bisphenol A is less than 1 mol%, the resulting fiber cannot be imparted with shrinkage. On the other hand, if the copolymerization amount of the ethylene oxide adduct of bisphenol A exceeds 10 mol%, the melting point of the polyester resin becomes low and the heat resistance becomes inferior, which is not preferable.

At this time, when 1 to 10 mol% of the ethylene oxide adduct of bisphenol A is contained as a copolymerization component, the copolymerization amount of isophthalic acid is preferably 2 to 15 mol%, and more preferably 2 to 10 mol%. Is preferable.
When the shrinkage of the obtained fiber becomes large, when the woven or knitted fabric obtained by using this fiber is heat-treated, the dough shrinks, and it becomes possible to obtain a high-density and compact woven or knitted fabric.

Further, the polycondensation catalyst used in the resin of the present invention is not limited, and for example, at least one of a germanium compound, an antimony compound, a titanium compound, a cobalt compound and the like can be used. Among them, at least one of a germanium compound and an antimony compound is used in particular. When the transparency of the obtained recycled polyester resin is important, it is preferable to use a germanium compound. Examples of the above compounds include oxides such as germanium, antimony, titanium and cobalt, inorganic acid salts, organic acid salts, halides and sulfides.

The amount of the polycondensation catalyst used is not particularly limited, but is preferably 5 × 10 ^-5 mol / unit or more with respect to 1 mol of the acid component of the polyester resin to be produced, and among them, 6 × 10 ^-5 mol / unit. It is more preferable to set it to unit or more. The upper limit of the amount used can be, for example, about 1 × 10 ^-3 mol / unit, but is not limited thereto.

Since the polymerization catalyst contained in the recycled polyester raw material may also act as a catalyst during the polycondensation reaction, the type of polymerization catalyst contained in the recycled polyester raw material when the polymerization catalyst is added in the polycondensation step. And its content are preferably taken into account.

Further, during the polycondensation reaction, if necessary, in addition to the above polycondensation catalyst, it is possible to suppress the thermal decomposition of fatty acid esters, hindered phenolic antioxidants, and resins that can adjust the melt viscosity. A phosphorus compound and titanium oxide for improving whiteness can also be added.

Examples of the fatty acid ester include beeswax (a mixture containing myricyl palmitate as a main component), stearyl stearate, behenyl behenate, stearyl behenate, glycerin monopalmitate, glycerin monostearate, glycerin disstearate, and glycerin tri. Examples thereof include 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 preferable. These can be used in one kind or two or more kinds.

Examples of the hindered phenol-based antioxidant include 2,6-di-t-butyl-4-methylphenol and n-octadecyl-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl). ) Propionate, Tetrax [Methyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methyl, 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 preferable in terms of effectiveness and cost. These can be used in one kind or two or more kinds.

As the phosphorus compound, for example, phosphorous acid, phosphoric acid, trimethylphosphite, triphenylphosphite, tridecylphosphite, trimethylphosphate, tridecylphosphate, triphenylphosfort and the like can be used. These can be used in one kind or two or more kinds.
Titanium oxide is generally used as a matting agent for polyester resins and white pigments. However, by adding an appropriate amount of titanium oxide to the resin of the present invention, the whiteness of the fibers is improved. It is preferable in that a woven or knitted fabric having a good color tone can be obtained. The amount of titanium oxide added is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the polyester resin.

The resin of the present invention has the above-mentioned composition and the characteristic values shown below.
(3) Concentration of carboxyl terminal groups is 40 equivalents / t or less (4) Average step-up rate measured by a booster tester is 0.6 MPa / h or less The resin of the present invention having these characteristic values is the production method of the present invention described later. Can be obtained by

First, as the characteristic value of (3), the resin of the present invention preferably has a carboxyl-terminal group concentration of 40 equivalents / t or less, more preferably 30 equivalents / t or less, and further preferably 25 equivalents / t or less. preferable.
The resin of the present invention has excellent heat resistance because the carboxyl terminal group concentration is 40 equivalents / t or less, and a molded product having excellent heat resistance can be obtained with good productivity by various molding methods. Is possible.

The ultimate viscosity of the regenerated polyester resin of the present invention is not particularly limited, but is usually preferably about 0.35 to 0.80. Further, as will be described later, the regenerated polyester resin of the present invention can also be used for molding by increasing the degree of polymerization through a solid phase polymerization step. In this case, the ultimate viscosity of the obtained recycled polyester resin is preferably 0.80 to 1.25. The ultimate 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 (4), the resin of the present invention has an average boosting speed of 0.6 MPa / h or less, preferably 0.5 MPa / h or less, particularly 0.4 MPa / h, as measured by the following method. The following is preferable. The average step-up rate in the present invention is an index of a large amount of foreign substances derived from various inorganic substances and non-polyester resin, and the smaller the average step-up rate, the smaller the amount of foreign substances mixed. It shows. The lower limit of the average boosting speed can be, for example, about 0.01 MPa / h, but is not limited to this.

To measure the average boosting speed, use a booster tester including an extruder and a pressure sensor, and use a stainless steel filter (nominal dimension 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, Filter particle size: 12 μm), melt the polyester resin at 300 ° C. with an extruder, and discharge 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 extruding is set to "initial pressure value (MPa)", and then continuously extruded for 12 hours. When the pressure value is set to the "final pressure value (MPa)", the average boosting speed is calculated by the following formula A based on those pressure values.
Average boost rate (MPa / h) = (final pressure value-initial pressure value) / 12) ... A)

Since the resin of the present invention can reduce the amount of foreign matter derived from various inorganic substances and foreign matter derived from non-polyester resin by adopting the manufacturing method described later, the pressure boosting which is the characteristic value of (4). The average boosting speed measured by the testing machine can be set to 0.6 MPa / h or less.

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 carry out the steps shown in (1) to (3) in order.
(1) A recycled polyester raw material is added to a mixture containing an ethylene terephthalate oligomer, ethylene glycol and isophthalic acid so that the molar ratio of the total glycol component / total acid component is 1.05 to 1.28, and 245 to 280. A step of obtaining a reaction product containing a depolymerized product by performing depolymerization under heat treatment conditions at ° C.
(2) A step of passing the reaction product through a filter having a filtration particle size of 10 to 25 μm and collecting the filtrate.
(3) A step of adding a polymerization catalyst to the filtrate and performing a polycondensation reaction at a temperature of 250 ° C. or higher and a reduced pressure of 1.0 hPa or lower.

First, in the depolymerization step (1), a recycled polyester raw material is added to a mixture containing ethylene terephthalate oligomer, ethylene glycol and isophthalic acid, and the molar ratio of total glycol component / total acid component is 1.05 to 1.28. The reaction product containing the depolymerized product is obtained by performing depolymerization under heat treatment conditions of 245 to 280 ° C.

As the ethylene terephthalate oligomer, ethylene glycol and isophthalic acid, known or commercially available ones can be used. It can also be manufactured by a known manufacturing method.

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

The amount of the mixture containing ethylene terephthalate oligomer, ethylene glycol and isophthalic acid (hereinafter, may be referred to as mixture E) may be 20 to 80% by mass in 100% by mass of the finally obtained recycled polyester resin. It is preferably 30 to 70% by mass, more preferably 30 to 70% by mass.
When the amount of the mixture E is smaller than the above, when the recycled polyester raw materials are added, the recycled polyester raw materials tend to block each other, which is not preferable because an excessive load is applied to the stirrer.

On the other hand, when the amount of the mixture E is larger than the above range, there is no particular problem in the depolymerization reaction, but the recycling rate of the finally obtained recycled polyester resin (the ratio of the components derived from the recycled polyester raw material) is low, which is not preferable. ..
When the resin of the present invention contains a copolymerization component other than isophthalic acid such as an ethylene oxide adduct of bisphenol A, it may be added so as to be contained in the mixture E before adding the recycled polyester raw material. preferable.

In the step (1), the ratio of adding ethylene terephthalate oligomer, ethylene glycol, isophthalic acid, and recycled polyester raw material may be appropriately changed depending on the copolymerization amount of isophthalic acid of the polyester resin to be finally obtained. , Generally, it is preferable to add in the following ratio (100 parts by mass in total). 5 to 40 parts by mass of ethylene terephthalate oligomer, 1 to 18 parts by mass of ethylene glycol, 1 to 40 parts by mass of isophthalic acid, 1 to 10 parts by mass of bisphenol A ethylene oxide adduct, recycled polyester raw material It is preferably 40 to 80 parts by mass.

Above all, the amount of ethylene glycol added is preferably 1 to 18 parts by mass, and more preferably 3 to 15 parts by mass in order to sufficiently proceed the depolymerization reaction. If the amount of ethylene glycol added exceeds 18 parts by mass, the ethylene terephthalate oligomer tends to solidify in the reactor, and the subsequent reaction may not be continued, which is not preferable.
When ethylene glycol is added to the ethylene terephthalate oligomer in the mixture E, it is preferable to make the temperature of the content uniform while turning the stirrer and then add the ethylene glycol in order to prevent the oligomer from solidifying.

When the recycled polyester raw material is added to the mixture E in the step (1), the molar ratio of the total glycol component / total acid component is set to 1.05 to 1.28 while stirring, and it is particularly preferable. Depolymerization is carried out under heat treatment conditions of 245 to 280 ° C. so as to be 1.05 to 1.20.
This step is important in the production method of the present invention. That is, in the conventional method using the recycled polyester raw material, depolymerization is performed using only the recycled polyester raw material, but in the present invention, the recycled polyester raw material is present in the presence of ethylene terephthalate oligomer, ethylene glycol, and isophthalic acid. And put the recycled polyester raw material into the mixture E so that the molar ratio of the total glycol component / total acid component is 1.05 to 1.28 for all the components of the recycled polyester raw material. , Depolymerization is performed.

When the copolymerization amount of isophthalic acid is 2 to 15 mol% in the total acid component, the molar ratio of the total glycol component / total acid component is preferably 1.08 to 1.20. When the copolymerization amount of isophthalic acid exceeds 15 mol% in the total acid component and is 50 mol% or less, the molar ratio of the above total glycol component / total acid component shall be 1.05 to 1.15. Is preferable.

By performing the step (1) as described above, not only various inorganic substances but also foreign substances derived from non-polyester resin can be efficiently deposited. Therefore, in the step (2), these foreign substances are completely filtered. be able to. In the polycondensation reaction of the step (3), the characteristic values of the present invention are that the content (copolymerization amount) of diethylene glycol and the concentration of the carboxyl terminal group are less than a specific amount, and the amount of foreign matter mixed is small. It becomes possible to obtain a recycled polyester resin.

Furthermore, by depolymerizing the recycled polyester raw material in the presence of ethylene terephthalate oligomer, ethylene glycol and isophthalic acid, the copolymerization component is present as compared with the case where the depolymerization is performed using only the recycled polyester raw material. Therefore, it becomes possible to proceed the depolymerization reaction at a low temperature. This is a great advantage when implemented on an industrial basis.

In the production method of the present invention, it is desirable that the recycled polyester raw material is not decomposed into monomers but is decomposed into oligomers having a repeating unit of about 5 to 20 by the above depolymerization reaction. By controlling the depolymerization reaction in this way, not only various inorganic substances but also foreign substances derived from non-polyester resin can be efficiently deposited, and as a result, more foreign substances can be removed.

When the molar ratio of the total glycol component / total acid component in the depolymerization reaction is out of the above range, the obtained regenerated polyester resin has at least one of the carboxyl terminal group concentration and the diethylene glycol content specified in the present invention. Will not be satisfied, and the average boosting speed will be high. This is because when the molar ratio of the total glycol component / total acid component during the depolymerization reaction is out of the above range, foreign substances derived from various inorganic substances and non-polyester resins are not efficiently precipitated (2). In the step (3), these foreign substances cannot be completely filtered, and the foreign substances are precipitated after the polycondensation reaction in the step (3), resulting in a regenerated polyester resin having a high average step-up rate.

The reactor used in the production method of the present invention has no particular problem in the capacity and the shape of the stirring blade in the generally used esterification reactor, but in order to efficiently proceed with the depolymerization reaction, ethylene glycol is used. It is preferable that the structure is provided with a distillation column that does not allow the reactor to accumulate outside.
When the recycled polyester raw material is added, it is preferable to carry out the process while stirring under normal pressure, and it is more preferable to add the recycled polyester raw material in a state of being purged with a small amount of inert gas (generally, nitrogen gas is used).

The reaction temperature at the time of depolymerization performed in the step (1) is preferably set in the range of 245 to 280 ° C. for the internal temperature of the reactor, and in particular, the internal temperature is set in the range of 255 to 280 ° C. It is more preferable to do so. When the reaction temperature at the time of depolymerization is less than 245 ° C, the reactants solidify and the operability deteriorates, and even if a recycled polyester resin is obtained, the content of diethylene glycol and the concentration of carboxyl terminal groups are high. Too much. When the reaction temperature exceeds 280 ° C., the content of diethylene glycol and the concentration of carboxyl terminal groups in the obtained regenerated polyester resin become too high.
The reaction time for depolymerization (reaction time after the completion of charging of the recycled polyester raw material) is preferably 4 hours or less, and is within 2 hours from the viewpoint of suppressing the by-product amount of diethylene glycol and suppressing the deterioration of the color tone of the polyester. It is more preferable to do so.

In the step (2), the reaction product containing 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 foreign substances. As described above, by carrying out the depolymerization reaction under the conditions of the step (1), not only various inorganic substances but also foreign substances derived from non-polyester resin are efficiently deposited. Therefore, a filter having a filtration particle size of 10 to 25 μm is efficiently deposited. By passing through the above, the precipitated foreign matter can be filtered to obtain a filtrate having a small amount of foreign matter mixed.

If a filter having a filtration particle size larger than 25 μm is used, the foreign matter in the polymer cannot be sufficiently removed, and the foreign matter in the obtained recycled polyester resin increases. Therefore, when spinning is performed using such a resin, the pressure of the nozzle pack is increased and the yarn is cut. On the other hand, if a filter having a filtration particle size smaller 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 deteriorates operability.

Further, the filter that can be used in the step (2) of the present invention is a general one and has no particular problem, but examples thereof include a screen changer type filter, a leaf disc filter, and a candle type sintered filter.

Then, in the production method of the present invention, the polymerization catalyst as described above is added to the filtrate obtained through the above step (2), and the polycondensation reaction is carried out at a temperature of 250 ° C. or higher and a reduced pressure of 1.0 hPa or lower. conduct.

Then, in the polycondensation reaction tank, the polycondensation reaction is carried out under a reduced pressure of 250 ° C. or higher and 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 becomes long and the productivity becomes inferior.
The polycondensation reaction temperature is more preferably 270 ° C. or higher. However, if the polycondensation reaction temperature is too high, the polymer will be colored by thermal decomposition and the color tone will deteriorate, and the amount of terminal groups (COOH) will also increase due to thermal decomposition. Therefore, in the present invention, the upper limit of the polycondensation reaction temperature is reached. Is preferably 285 ° C. or lower. The ultimate viscosity of the regenerated polyester (prepolymer) obtained here is preferably 0.44 to 0.80.

The resin of the present invention may contain various additives other than the above-mentioned additives such as a polymerization catalyst, an antioxidant, and a phosphorus compound, as long as the effect is not impaired.
As various additives, additives such as manganese compounds such as manganese acetate, anthraquinone dye compounds, and copper phthalocyanine compounds may be contained in order to suppress coloring due to thermal decomposition of the polyester resin.

Subsequently, the prepolymer obtained by the above-mentioned melt polymerization reaction is used as chips having an arbitrary shape such as a die shape or a columnar shape, and the polyester chips are continuously supplied to a crystallizer and crystallized at a temperature of 150 to 190 ° C. After conversion, it is supplied to a dryer, dried at a temperature of 190 ° C. or lower for 4 to 16 hours, sent to a preheater, heated to the following solid phase polymerization temperature in a range of 2 to 5 hours, and then solidified. A polyester resin having a target ultimate viscosity is obtained by continuously supplying it to a phase polymerizer and performing a solid phase polymerization reaction. The solid phase polymerization is preferably carried out under an inert gas such as nitrogen gas. The solid phase polymerization is usually preferably carried out at a temperature in the range of 170 to 230 ° C, more preferably in the range of 180 to 220 ° C. 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 obtain a molded product (blow molded product, injection molded product, sheet, film, etc.) having excellent color tone and transparency by adopting blow molding, injection molding, stretching method, etc. Fibers can be obtained by melt spinning.

A molded product containing the resin of the present invention can be produced, for example, by applying various molding methods such as press molding, extrusion molding, pneumatic molding, and blow molding using the raw material containing the resin of the present invention. This makes it possible to provide various parts including containers. The resin of the present invention has characteristics similar to those of a virgin polyester resin and is excellent in thermal stability, and is therefore particularly suitable for producing blow-molded products. Therefore, a method for producing a molded product including 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 can be suitably adopted. This makes it possible to manufacture a molded product such as a container.

As described above, the resin of the present invention is excellent in thermal stability because the content of diethylene glycol and the concentration of the carboxyl-terminal group are not more than a specific amount. Therefore, when a molded product as described above is obtained, thickness unevenness or the like is unlikely to occur, and a molded product with a high degree of uniformity can be obtained with good operability. Further, as described above, the resin of the present invention has an average step-up speed of 0.6 MPa / h or less, and a small amount of foreign matter mixed therein. As foreign substances existing in the resin, inorganic substances and foreign substances derived from non-polyester resin are assumed, but by reducing these foreign substances, it is possible to obtain a molded product having a good surface appearance and excellent impact resistance and strength. can.

In the case of a molded product, by containing 0.1 to 1.0% by mass of a hindered phenolic antioxidant, it is possible to prevent a decrease in the ultimate viscosity and a deterioration in color tone after molding.

In the case of a molded product, it is preferable to contain a germanium-based compound and a cobalt compound as a polymerization catalyst. It is preferable that the germanium compound is contained in an amount of 5.0 × 10 ^-5 mol to 3.0 × 10 ^-4 mol per 1 mol of the acid component of the polyester. If it is less than 1.0 × ^10-5 mol, it becomes difficult to obtain a polyester resin having a target degree of polymerization. On the other hand, if it exceeds 3.0 × 10 ^-4 mol, the stability over time of the polyester deteriorates due to the by-product of the reaction between the cobalt compound and the germanium compound, and the ultimate viscosity of the polyester resin composition after long-term storage decreases. It is not preferable because the color tone deteriorates.

Examples of the germanium compound include germanium dioxide, germanium tetrachloride, germanium tetraethoxydo and the like, and germanium dioxide is preferable from the viewpoint of polymerization catalytic activity, physical properties of the obtained polyester resin and cost.

The content of the cobalt compound needs to be 1.0 × 10 ^-5 mol to 1.0 × 10 ^-4 mol, and 2.0 × 10 ^-5 mol to 8 mol, with respect to 1 mol of the acid component of polyester. It is preferably 0.0 × ^10-5 mol.
Less than 1.0 x ^10-5 mol. The color tone of polyester gets worse. On the other hand, if it exceeds 1.0 × 10 ^-4 mol, the stability of the polyester resin with time also deteriorates. Examples of the cobalt compound include cobalt acetate, cobalt formic acid, cobalt chloride, and cobalt oxide, and cobalt acetate is preferable from the viewpoint of polymerization catalytic activity, physical properties of the obtained polyester resin, and cost.

In the case of a fiber containing the resin of the present invention, for example, the fiber can be manufactured by 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 yarn fineness of 0.8 decitex or less (preferably 0.6 to 0.3 decites). 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 the same characteristics as the virgin polyester resin. Is less likely to occur, and polyester fibers can be obtained with good productivity.

The fiber of the present invention containing the resin of the present invention may be, for example, any of monofilaments, multifilaments and the like, and may be any of long fibers, short fibers and the like. Further, the fiber of the present invention may be either a fiber used as a main fiber or a fiber used as a binder fiber. Further, a fiber made of only the resin of the present invention or a composite fiber using another resin together with the resin of the present invention may be used.

For example, when the fiber of the present invention is used as the main fiber, the composite fiber may be in the form of a resin of the present invention and another resin bonded together side by side. It should be noted that the other resin used to form such a composite fiber may be appropriately selected depending on the required fiber characteristics and application. In the case of side-by-side type composite fibers, the resin of the present invention (copolymerized with an ethylene oxide adduct of bisphenol A) shrinks highly during heat treatment, so that three-dimensional spiral crimping occurs. Due to this developed spiral crimp, the fiber of the present invention becomes a fiber having a high elasticity.
Further, for example, when the fiber of the present invention is used as a binder fiber, it may be a core-sheath type binder fiber using the resin of the present invention only in the sheath portion, in addition to the fully fused binder fiber using only the resin of the present invention.

Further, the fiber of the present invention may contain a colored pigment. Examples of the colored pigment include inorganic pigments such as iron oxide, ultramarine blue, and titanium oxide, and organic pigments such as cyanine, polyazo, anthraquinone, carbon black, and the like. In order to obtain the desired color development, these colored pigments can be appropriately selected and used alone or in a blend.
As for the method of adding the colored pigment, the fiber of the present invention may be added in any of the processes of melt spinning, and examples thereof include a masterbatch method and a liquid color method. Therefore, the masterbatch method is preferable. When the masterbatch method is adopted, a method of measuring and mixing at the stage of raw material pellets and melt-spinning, a method of measuring and mixing separately melted polymers and spinning, etc. can be mentioned. May be good.

Further, in the production of fibers, it is generally more difficult to produce long fibers (multifilaments), but in the fiber of the present invention, for example, the single yarn fineness is 0.3 to 30 decitex and the number of single yarns is 2 to 300. A multifilament having a total fineness of 5 to 350, a strength of 1 to 5 cN / decitex, and an elongation of 10 to 400% can be obtained.

As described above, the resin of the present invention is excellent in thermal stability because the content of diethylene glycol and the concentration of the carboxyl-terminal group are not more than a specific amount. Therefore, when the long fibers as described above are obtained, thickness unevenness and the like are less likely to occur, and fibers having a high degree of uniformity can be obtained with good operability. Further, as described above, the resin of the present invention has an average step-up speed of 0.6 MPa / h or less, and a small amount of foreign matter mixed therein. As foreign substances existing in the resin, inorganic substances and foreign substances derived from non-polyester resin are assumed, but due to the small amount of these foreign substances, the single yarn fineness is 1.0 decitex or less, especially 0.6 decitex or less. Can be obtained with good operability.

When the fiber of the present invention is a staple fiber, for example, a fiber having a single yarn fineness of 0.5 to 25.0 decitex, a strength of 0.1 to 6.0 cN / decitex, and an elongation of 20 to 600% can be obtained. can. As described above, the resin of the present invention is excellent in thermal stability because the content of diethylene glycol and the concentration of the carboxyl-terminal group are not more than a specific amount. Therefore, when the staple fibers as described above are obtained, the single yarn fusion in the spinning and drawing steps is suppressed, the single yarn fineness is less likely to vary, and the fibers having a high degree of uniformity can be obtained with good operability. can. Further, in the case of staple fibers used for wet nonwoven fabric applications, single yarn fusion in the spinning and drawing steps is suppressed, so that fibers having good single yarn dispersibility in water can be obtained. Further, as described above, the resin of the present invention has an average step-up speed of 0.6 MPa / h or less, and a small amount of foreign matter mixed therein. As the foreign matter existing in the resin, an inorganic substance or a foreign substance derived from a non-polyester resin is assumed, but due to the small amount of these foreign substances, a product such as a non-woven fabric obtained by using the fiber of the present invention as a main fiber or a binder fiber. The quality and strength of the material are improved.

The nonwoven fabric obtained by using the fiber of the present invention may be dry type or wet type, and the basis weight of the nonwoven fabric is not particularly limited. As a method for making a non-woven fabric, when the fiber of the present invention is used as a binder fiber, a low melting point polyester resin (resin of the present invention) constituting the fiber becomes a heat-bonding component and the fibers are integrated by heat-bonding. , The constituent fibers may be three-dimensionally entangled with each other before thermal bonding. When the fiber of the present invention is used as the main fiber, examples of the non-woven fabric include thermal bonded non-woven fabric, needle punch non-woven fabric, air-laid non-woven fabric, spunlace non-woven fabric, and wet non-woven fabric (papermaking). Among them, when the fiber of the present invention is a side-by-side type composite fiber as described above and has a latent crimping property that expresses spiral crimping, fibers such as spunlace non-woven fabric and needle punched non-woven fabric are three-dimensionally used. Suitable for non-woven fabrics to be entangled with. Since such a non-woven fabric has good elasticity, it can be suitably used as a base cloth for medical hygiene materials such as face masks, patches and supporters.

The nonwoven fabric obtained by using the fiber of the present invention may contain a fiber other than the fiber of the present invention. For example, a non-woven fabric using the fiber of the present invention as a binder fiber and a fiber made of a polyester resin having a higher melting point than the resin of the present invention as a main fiber can be mentioned.

An example of a method for manufacturing a dry non-woven fabric will be given. This is an example in which the fiber of the present invention is used as a binder fiber and mixed with other fibers other than the fiber of the present invention to obtain a dry nonwoven fabric. It may be selected, and the ratio of the fiber of the present invention is preferably about 10 to 90% by mass. Both of these fibers (fibers to be constituent fibers) are put into a card machine and defibrated to produce a dry web. The obtained web is subjected to heat bonding treatment at a temperature at which the low melting point polyester resin constituting the fiber of the present invention is melted or softened by a continuous heat treatment machine in which hot air treatment is performed, and the constituent fibers are integrated by heat bonding. Obtain a non-woven fabric.

An example of a method for manufacturing a wet non-woven fabric will be given. Similar to the dry non-woven fabric, this is an example in which the fiber of the present invention is used as a binder fiber and mixed with other fibers other than the fiber of the present invention to obtain a wet non-woven fabric. The fiber may be selected according to the characteristics, and the ratio of the fiber of the present invention is preferably about 10 to 90% by mass. Both of these fibers (fibers to be constituent fibers) are stirred using a pulp disintegrator to perform a defibration step, and then a wet web is produced by a paper machine. The obtained web is subjected to heat bonding treatment at a temperature at which the low melting point polyester resin constituting the fiber of the present invention is melted or softened by a continuous heat treatment machine in which hot air treatment is performed, and the constituent fibers are integrated by heat bonding. Obtain a non-woven fabric.

Next, the present invention will be specifically described with reference to Examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(A) Extreme Viscosity The obtained recycled polyester resin is used and measured at a temperature of 20 ° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.
(B) Composition of Polyester Resin The obtained polyester resin was dissolved in a mixed solvent having a volume ratio of deuterated trifluoroacetic acid and deuterated chloroform of 1/11, and JNM-ECZ400R / S1 type manufactured by JEOL Ltd. 1H-NMR was measured with an NMR apparatus, and the type and content of the copolymerization component were determined from the integrated intensity of the proton peaks of each component in the obtained chart.
(C) Concentration of carboxyl end group 0.1 g of the obtained regenerated polyester resin is dissolved in 10 ml of benzyl alcohol, 10 ml of chloroform is added to this solution, and then titrated with a 1/10 specified potassium hydroxide benzyl alcohol solution to determine the concentration. rice field.

(D) Average pressure increase rate measured by a pressure tester The obtained recycled polyester resin is melted at 300 ° C. with an extruder, and a stainless steel twill weave filter (nominal size mesh:) is used as a filter at the tip of the extruder. 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 grain size: 12 μm, viscous resistance coefficient (m ^-1 ) : 2.60 x ¹⁰⁷ , inertial resistance coefficient: 5.14 x 10, manufactured by Kamijo Seiki Co., Ltd., and a reinforcing material (steel plain weave wire mesh (nominal size mesh: 40 mesh, nominal size mesh: 40 mesh,) on the back surface (downstream side). Weaving method: Plain weave, Wire diameter: 0.21 mm (manufactured by Kamijo Seiki Co., Ltd.) After laminating, the polymer discharge rate is 29.0 g / min, and the filter pressure is increased by a pressurizing tester; "MES-Y44D type" manufactured by Asahi Gauge. The measurement is performed using a detector. The pressure test using the above pressure tester is continuously performed for 12 hours, and the initial pressure value (MPa) at the time of starting the pressure test (5 to 5 after the polyester resin starts to pass through the filter). The minimum value of the pressure for 10 minutes is taken as the initial pressure.) And the final pressure value (MPa) after 12 hours have passed, the average boosting speed was calculated by the following formula.
Average boost rate (MPa / h) = (final pressure value-initial pressure value) / 12

(E) Melting point Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, measurements were taken in a nitrogen stream at a temperature range of 25 to 280 ° C. and a heating rate of 20 ° C./min.
(F) Glass transition temperature Using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, measurements were taken in a nitrogen stream at a temperature range of 25 to 280 ° C. and a heating rate of 20 ° C./min.

(G) Moldability The thickness of the body of the obtained container (100 samples) was measured, and those having a difference in thickness between the thickest part and the thinnest part up to 0.30 mm were accepted. Based on the number of samples that passed at this time, evaluation was made on a two-point scale as follows.
〇: Number of passed samples is 95 or more ×: Number of passed samples is 94 or less (h) Haze A sample piece (20 pieces) is made by cutting out from the obtained container, and the turbidity is turbidity manufactured by Nippon Denshoku Kogyo Co., Ltd. It was measured with a meter MODEL 1001DP (air: haze 0%) and used as an average value of n number 20. It was judged that the smaller this value is, the better the transparency is, and if it is 6% or less, the transparency is excellent.
(I) Impact resistance (g) Molded products (100 samples) that passed the evaluation of moldability were filled with 340 ml of tap water, and at room temperature, on P tiles, a height of 200 cm. Then, the molded body was dropped once with the bottom surface of the molded body facing downward and the side surfaces facing downward. The impact resistance was evaluated by the number of molded bodies that did not crack at this time. In addition, in the case of 90 or more, it was evaluated that the impact resistance was good.

(J) Operability of staple fiber production (cutting thread)
If the number of cuts during the continuous melt spinning for 24 hours is 3 times / (day / weight) or less, and there is no single yarn adhesion during the drawing process, it is marked as "○", and in other cases, it is marked as "○". It was set as "x".
(K) Non-woven fabric strength A sample of the obtained non-woven fabric was cut out in the MD direction of 150 mm and the CD direction of 50 mm, and the non-woven fabric was subjected to the conditions of a tensile speed of 100 mm / min and a chuck distance of 100 mm using an autograph (AG-50KNI manufactured by Shimadzu Corporation). MD strength was measured. The number of samples was set to n = 5.
The tensile strength of the obtained non-woven fabric was evaluated in the following two stages.
◯: Tensile strength 1500 cN or more
X: Tensile strength less than 1500 cN (l) Shrinkage (staple)
Using the obtained staple fibers (Examples 30 to 32), measurements were made as follows based on the rate of change in dry heat dimension of JIS L1015 8.15b. Create a sample in which both ends of the fiber are attached to the glossy paper one by one with an adhesive (double-sided tape) with a space distance of 25 mm (paper is attached from the top of the double-sided tape and further fixed), and this sample is fixed. The initial sample length (N ₀ ) when a predetermined initial load (initial load = 45 mg x fineness (dtex) value) is applied after attaching to a single fiber elasticity tester with a grip interval of 25 mm and cutting the glossy paper. taking measurement. After measuring the initial sample length, attach the fiber to the heat treatment table, hang it in a hot air dryer set at 170 ° C, leave it for 15 minutes, take it out, cool it to room temperature, and then attach it to the single fiber elasticity tester again for the initial load. The distance between the grips (sample length after heat treatment (N ₁ )) was read, and the heat shrinkage rate was calculated by the following formula.
Heat shrinkage rate (%) = [1- (N ₁ / N ₀ )] × 100
Those having a shrinkage rate of 30% or more were designated as “◯”, and those having a shrinkage rate of less than 30% were designated as “x”.

(M) Operability of long fiber manufacturing (cutting thread)
After performing melt spinning and collecting undrawn yarn, and when the cutting rate (number of cuts / number of weights) in the drawing step is 5% or less, it is evaluated as "○", and in other cases, it is evaluated as "×". ..
(N) Shrinkage (long fiber)
The obtained polyester fiber was squeezed by 22.5 m, and the ratio of the yarn lengths before and after being immersed in boiling water at 100 ° C. for 30 minutes was defined as the shrinkage ratio, and was calculated by the following formula. When measuring the yarn length, a load of fineness den × 1.3 times was applied.
Shrinkage rate (%) = [(thread length before treatment with boiling water-thread length after treatment) / thread length before treatment] x 100
Those having a shrinkage rate of 15% or more were designated as “◯”, and those having a shrinkage rate of less than 15% were designated as “x”.

Example 1
[Recycled polyester resin]
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) is supplied to the esterification reactor and reacted under the conditions of a temperature of 250 ° C. and a pressure of 50 hPa for esterification. An ethylene terephthalate oligomer having a reaction rate of 95% (number average degree of polymerization: 5) was obtained.
20.0 parts by mass of the ethylene terephthalate oligomer was charged into the esterification reactor, and then 16 parts by mass of IPA and 9 parts by mass of EG were added to isophthalic acid (IPA) and ethylene glycol (EG) to obtain a mixture E. .. Then, 55 parts by mass of a recycled polyester raw material (a pellet of polyester waste generated in the process of producing the polyester resin) was quantitatively charged over about 2 hours via a rotary valve.
At this time, the recycled polyester raw material was added so that the molar ratio of the total glycol component / total acid component (hereinafter, may be referred to as G / A) was 1.13. Then, the depolymerization reaction was carried out for 1 hour under the heat treatment conditions of 260 ° C.
Then, the obtained depolymerized polymer is pressure-fed to the polycondensation reactor (hereinafter referred to as PC can) by setting a candle filter having an opening of 20 μm between the esterification reactor and the polycondensation reactor, and then oxidizing. 0.5 parts by mass of titanium, 2.0 × 10 ^-4 mol / unit of antimony trioxide as a polymerization catalyst, 0.4 × 10 ^-4 mol / unit of cobalt acetate as a cobalt compound, and 0. Add 6 × 10 ^-4 mol / unit, reduce the pressure of the PC can, and after 60 minutes, carry out a melt polymerization reaction at a final pressure of 0.5 hPa and a temperature of 280 ° C. for 3 hours, and a polyester resin with an ultimate viscosity of 0.7. Got

[Manufacturing of staples]
Using a spinneret with a hole number of 2174H and a hole diameter of 0.35 mm so that polyethylene terephthalate with an intrinsic viscosity of 0.70 is placed in the core and the obtained polyester resin is placed in the sheath, a discharge rate of 1630 g / min and a core-sheath mass ratio. Melt spinning was performed under the conditions of a spinning temperature of 270 ° C. and a spinning speed of 1100 m / min at 50/50.
The obtained undrawn yarn was converged to obtain a tow of 115 ktex, and the yarn was drawn under the conditions of a drawing temperature of 56 ° C. and a drawing ratio of 3.5 times. Then, after mechanically crimping with a push-in crimper, the fiber was cut to a fiber length of 51 mm to obtain a core-sheath type composite fiber having a fineness of 2.2 dtex.

[Making dry non-woven fabric]
Unitika's regular polyester fiber <121> 1.7T 51 mm is mixed with 70% by mass, and the obtained core-sheath type composite fiber (used as a binder fiber) is mixed with 30% by mass, and the texture of the non-woven fabric after heat treatment is obtained. Fibers are put into a card machine (SC-500DI3HC manufactured by Daiwa-Kiko Co., Ltd.) so as to be 50 g / m2, and a web is produced. Then, using a continuous heat treatment machine (NFD-500E2 manufactured by Tsujii Dyeing Machinery Co., Ltd.), heat treatment was performed under the conditions of an air volume of 57 m ³ / min and 130 ° C. × 1 min to prepare a dry non-woven fabric.

Examples 2 to 11 and Comparative Examples 1 to 5
[Recycled polyester resin]
The same as in Example 1 except that the addition amounts of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid and recycled polyester raw materials, G / A and heat treatment temperature added during the depolymerization reaction were changed to those shown in Table 1. A depolymerization reaction was carried out.
Further, a polyester resin was produced in the same manner as in Example 1 except that the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 1.
[Manufacturing of staples]
A heat-adhesive core-sheath type composite fiber was obtained in the same manner as in Example 1 except that the obtained polyester resin (Examples 2 to 11, Comparative Examples 2, 4, and 5) was used for the sheath portion.
[Making dry non-woven fabric]
A dry non-woven fabric was produced in the same manner as in Example 1 except that the obtained heat-adhesive core-sheath type composite fiber was used.

Table 1 shows the characteristic values of the polyester resins obtained in Examples 1 to 11 and Comparative Examples 1 to 5. Table 2 shows the evaluation of operability when the staple fibers were produced in Examples 1 to 11 and Comparative Examples 2, 4 and 5, and the values of the nonwoven fabric strength obtained by using the staple fibers.

Example 12
[Recycled polyester resin]
The same as in Example 1 except that the addition amounts of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid and recycled polyester raw materials, G / A and heat treatment temperature added during the depolymerization reaction were changed to those shown in Table 1. A depolymerization reaction was carried out.
In addition, the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 1, and tetrakis [methylene-3- (methylene-3- (methylene-3- (methylene-3-)) was used as a hindered phenolic antioxidant instead of titanium oxide. 3,5-Di-t-butyl-4-hydroxyphenyl) propionate] A polyester resin was produced in the same manner as in Example 1 except that 0.18 parts by mass of methane (BASF: Irganox 1010) was added. ..
Subsequently, the obtained polyester resin is continuously supplied to a crystallization device, crystallized at 150 ° C., supplied to a dryer, dried at 130 ° C. for 10 hours, and then sent to a preheater to heat up to 180 ° C. After that, it was supplied to the solid phase polymerization machine. Then, the solid phase polymerization reaction was carried out at 190 ° C. for 50 hours under nitrogen gas to obtain a polyester resin having an ultimate viscosity of 1.1.

[Blow molded product]
The obtained recycled polyester resin is made into chips and dried, and then the resin is extruded at an extrusion temperature of 260 ° C. to form a cylindrical parison using a direct blow molding machine (manufactured by Tahara), while the parison is in a softened state. The bottom was formed by sandwiching it with a mold, and this was blown to form a bottle. At this time, the bottom was formed when the parison diameter was 3 cm and the length was 25 cm, and blow molding was performed to obtain a 350 ml hollow container (direct blow molded product).

Examples 13-21, Comparative Examples 6-14
[Recycled polyester resin]
The same as in Example 12 except that the addition amounts of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid and recycled polyester raw materials, G / A and heat treatment temperature added during the depolymerization reaction were changed to those shown in Table 1. A depolymerization reaction was carried out.
Further, a polyester resin was produced in the same manner as in Example 12 except that the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 1.
Subsequently, the obtained polyester resin was subjected to a solid phase polymerization reaction in the same manner as in Example 12 to obtain a polyester resin having an ultimate viscosity of 1.1 (Comparative Example 7 is 1.2).
[Blow molded product]
Using the obtained polyester resin (Examples 13 to 21, Comparative Examples 6, 7, 9 to 12), blow molding was performed in the same manner as in Example 12 to obtain a blow molded product.

Table 1 shows the characteristic values of the polyester resins obtained in Examples 12 to 21 and Comparative Examples 6 to 14. Table 3 shows the evaluation results of the moldability, haze, and impact resistance of the blow-molded products obtained in Examples 12 to 21, Comparative Examples 6, 7, and 9 to 12.

As is clear from Tables 1 to 3, the regenerated polyester resins obtained in Examples 1 to 21 had a carboxyl terminal group content, a diethylene glycol content, and an average step-up rate within the ranges specified in the present invention. .. Therefore, it was possible to obtain a dry non-woven fabric having excellent operability when obtaining short fibers and having excellent non-woven fabric strength. In addition, it was possible to obtain a blow-molded product having excellent moldability during blow molding and excellent haze and impact resistance.

On the other hand, in the polyester obtained in Comparative Example 1, the content of isophthalic acid exceeded the upper limit, so that a non-woven fabric could not be obtained. In the polyester obtained in Comparative Example 2, the depolymerization temperature exceeded the upper limit, so that the content of diethylene glycol and the amount of the carboxyl-terminal group exceeded the upper limit, and the operability for obtaining staple fibers deteriorated. In Comparative Example 3, the polyester resin could not be obtained with good productivity because the filtration particle size was less than the lower limit. Since the polyester obtained in Comparative Example 4 exceeded the upper limit of the filtration particle size, the pressurizing speed was high and the operability for obtaining short fibers was deteriorated. In the polyester obtained in Comparative Example 5, since the G / A at the time of depolymerization exceeded the upper limit, the content of diethylene glycol was high, the pressurization rate was high, and the operability for obtaining short fibers was deteriorated. In the polyester obtained in Comparative Example 6, the content of isophthalic acid was less than the lower limit, so that the polyester obtained whitened during blow molding and caused an appearance defect. In the polyester obtained in Comparative Example 7, since the depolymerization temperature exceeded the upper limit, the content of diethylene glycol and the amount of the carboxyl terminal were large, and the impact resistance was lowered.

In Comparative Example 8, since the filtration particle size was less than the lower limit, the polyester resin could not be obtained with good productivity. Since the polyester obtained in Comparative Example 9 exceeded the upper limit of the filtration particle size, the step-up speed was high, and the obtained blow-molded product was inferior in impact resistance. In the polyester obtained in Comparative Example 10, since the G / A at the time of polymerization was less than the lower limit, the amount of carboxyl-terminal groups was high, the step-up speed was high, and the impact resistance of the blow molded product was inferior. In the polyester obtained in Comparative Example 11, since the G / A at the time of polymerization was less than the lower limit, the amount of carboxyl-terminal groups was high, the step-up speed was high, and the obtained blow-molded product was inferior in impact resistance. rice field. In the polyester obtained in Comparative Example 12, the G / A at the time of depolymerization exceeded the upper limit, so that the content of diethylene glycol was high, the pressurization rate was high, and the obtained blow molded product was inferior in impact resistance. there were. In Comparative Example 13, since the depolymerization temperature was less than the lower limit, the raw material was solidified and polyester could not be obtained. In Comparative Example 14, since the polycondensation temperature was less than the lower limit, the condensation reaction did not proceed and the polyester resin could not be obtained.

Example 22
[Recycled polyester resin]
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) is supplied to the esterification reactor and reacted under the conditions of a temperature of 250 ° C. and a pressure of 50 hPa for esterification. An ethylene terephthalate oligomer having a reaction rate of 95% (number average degree of polymerization: 5) was obtained.
37.0 parts by mass of ethylene terephthalate oligomer was charged into the esterification reactor, followed by 3.1 parts by mass of isophthalic acid (IPA), ethylene oxide adduct of bisphenol A (BAEO), and ethylene glycol (EG). 6.6 parts by mass of BAEO and 3.3 parts by mass of EG were added to obtain a mixture E. Then, 50 parts by mass of a recycled polyester raw material (a pellet of polyester waste generated in the process of producing the polyester resin) was quantitatively charged over about 2 hours via a rotary valve.
At this time, the recycled polyester raw material was added so that the molar ratio of the total glycol component / total acid component (hereinafter, may be referred to as G / A) was 1.17. Then, the depolymerization reaction was carried out for 1 hour under the heat treatment conditions of 260 ° C.
Then, the obtained depolymerized product is pressure-fed to the polycondensation reactor (hereinafter referred to as PC can) by setting a candle filter having an opening of 20 μm between the esterification reactor and the polycondensation reactor, and then polymerizing. Antimon trioxide as a catalyst 2.0 × 10 ^-4 mol / unit, cobalt acetate as a cobalt compound 0.4 × 10 ^-4 mol / unit, triphenyl phosphate 0.6 × 10 ^-4 mol / unit, Add titanium oxide to 0.4 parts by mass, reduce the pressure of the PC can, and after 60 minutes, carry out a melt polymerization reaction at a final pressure of 0.5 hPa and a temperature of 280 ° C. for 3 hours to obtain a polyester resin having an ultimate viscosity of 0.64. Got

[Manufacturing of long fibers]
The obtained polyester resin was melt-spun using a spinneret having a hole number of 12H and a hole diameter of 0.3 mm under the conditions of a discharge rate of 13 g / min, a spinning temperature of 290 ° C., and a spinning speed of 1395 m / min. The obtained undrawn yarn was drawn under the conditions of a heat setting temperature of 117 ° C. and a draw ratio of 3.0 times to obtain a polyester fiber having a fineness of 33 dtex / 12f.

Examples 23 to 29, Comparative Examples 15 to 23
[Recycled polyester resin]
Except for changing the amount of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid, ethylene oxide adduct of bisphenol A and recycled polyester raw material added during the depolymerization reaction, G / A and heat treatment temperature to those shown in Table 4. The depolymerization reaction was carried out in the same manner as in Example 22. Further, a polyester resin was produced in the same manner as in Example 22 except that the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 4.
[Manufacturing of long fibers]
Using the obtained polyester resin, polyester fibers were produced in the same manner as in Example 22.

Table 4 shows the characteristic values of the polyester resins obtained in Examples 22 to 29 and Comparative Examples 15 to 23, the evaluation of the operability when the fibers were manufactured, and the shrinkage of the obtained fibers.

As is clear from Table 4, the polyester resins obtained in Examples 22 to 29 had a carboxyl terminal group content, a diethylene glycol content, and an average step-up rate within the ranges specified in the present invention. Therefore, it was possible to obtain a polyester fiber having excellent operability and shrinkage when obtaining the fiber.

Example 30
[Recycled polyester resin]
Except for changing the amount of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid, ethylene oxide adduct of bisphenol A and recycled polyester raw material added during the depolymerization reaction, G / A and heat treatment temperature to those shown in Table 4. The depolymerization reaction was carried out in the same manner as in Example 22. Further, a polyester resin was produced in the same manner as in Example 22 except that the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 4.
[Manufacturing of staple fibers (composite fibers)]
Using polyethylene terephthalate with an ultimate viscosity of 0.70 and the obtained recycled polyester resin, a composite melt spinning device with a composite mass ratio of 1: 1 was used to spin from a round cross-section base hole with 1038 holes at a spinning temperature of 300 ° C. A composite fiber in which both polyester resins were bonded in a side-by-side manner was spun at a take-up speed of 900 m / min and a discharge rate of 386 g / min. The obtained undrawn yarn was drawn at a drawing temperature of 73 ° C. and a draw ratio of 3.60 times, then subjected to tension heat treatment at 140 ° C., and mechanically crimped (12 crimps / 25 mm) in a stuffing box. After that, a finishing oil was applied and the fiber was cut to a fiber length of 44 mm to obtain a composite fiber having a single yarn fineness of 1.3 dtex.

Example 31
[Recycled polyester resin]
Except for changing the amount of ethylene terephthalate oligomer, ethylene glycol, isophthalic acid, ethylene oxide adduct of bisphenol A and recycled polyester raw material added during the depolymerization reaction, G / A and heat treatment temperature to those shown in Table 4. The depolymerization reaction was carried out in the same manner as in Example 22. Further, a polyester resin was produced in the same manner as in Example 22 except that the filtration particle size of the filter in the step of recovering the filtrate and the heat treatment temperature in the polymerization reaction step were changed to those shown in Table 4.
[Manufacturing of staples]
Using polyethylene terephthalate with an ultimate viscosity of 0.70 and the obtained recycled polyester resin, using a spinneret with 706 holes and a hole diameter of 0.30 mm, a discharge rate of 312 g / min and a mass ratio of both polyester resins of 50 / min. A side-by-side type composite fiber was obtained under the conditions of a spinning temperature of 272 ° C. and a spinning speed of 1100 m / min. The obtained undrawn yarn was drawn at a drawing temperature of 73 ° C. and a draw ratio of 3.40 times, then subjected to tension heat treatment at 140 ° C., and mechanically crimped (12 crimps / 25 mm) in a stuffing box. After that, a finishing oil was applied and the fiber was cut to a fiber length of 44 mm to obtain a composite fiber having a single yarn fineness of 1.1 dtex.

Example 32
[Manufacturing of staples]
Polyester in which polyethylene terephthalate having an ultimate viscosity of 0.70 is used as a base polymer and a masterbatch kneaded with iron oxide (red, yellow) and carbon black is mixed so that the concentration of colored pigment in the base polymer is 0.2% by mass. A composite fiber having a single yarn fineness of 1.3 dtex was obtained in the same manner as in Example 30 except that terephthalate and the regenerated polyester resin obtained in Example 30 were used.

Example 33
[Manufacturing of staples]
Using a spinneret with a hole number of 1014 and a hole diameter of 0.35 mm so that the polyethylene terephthalate having an ultimate viscosity of 0.70 is placed in the core and the polyester resin obtained in Example 5 is placed in the sheath, a discharge rate of 563 g / min. The mass ratio of the core portion to the sheath portion was set to 50/50, and melt spinning was performed under the conditions of a spinning temperature of 272 ° C. and a spinning speed of 1120 m / min. The obtained undrawn yarn was converged and drawn under the conditions of a drawing temperature of 54 ° C. and a drawing ratio of 3.4 times. Next, after applying the oil agent, the drawn yarn was squeezed to a moisture content of about 18% by mass and cut to a length of 5 mm with a drum type cutter to obtain a core-sheath type composite fiber having a single yarn fineness of 1.7 dtex. ..
[Preparation of wet non-woven fabric]
Next, the obtained core-sheath type composite fiber was used as a binder fiber, and a shortcut fiber made of polyethylene terephthalate having a single yarn fineness of 1.6 dtex and a length of 5 mm was used as the main fiber (Unitika <N801> 1.6T5). Was dispersed in water with binder fiber / main fiber (mass ratio) = 40/60, and a papermaking machine was used to obtain a papermaking web. Then, using a continuous heat treatment machine (manufactured by Tsujii Dyeing Machinery Co., Ltd., NFD-500E2), heat treatment was performed under the conditions of an air volume of 57 m ³ / min and 130 ° C. × 1 min to prepare a wet nonwoven fabric.

Example 34
[Manufacturing of staples]
Using only the polyester resin obtained in Example 5, a spinneret having a hole number of 720 and a hole diameter of 0.25 mm was used to perform melt spinning under the conditions of a discharge rate of 350 g / min, a spinning temperature of 275 ° C., and a spinning speed of 730 m / min. gone.
The obtained undrawn yarn is converged to make a tow of 50 ktex, then after applying an oil agent, the tow is squeezed so that the water content of the tow is about 18% by mass, cut to a length of 5 mm with a drum cutter, and fineness. A heat-adhesive short fiber of 6.6 dtex was obtained.
[Preparation of wet non-woven fabric]
A wet nonwoven fabric was produced in the same manner as in Example 33, except that the obtained heat-adhesive short fibers were used as binder fibers.

Example 35
[Manufacturing of staple fibers, manufacturing of wet non-woven fabric]
Heat-adhesive staple fibers having a fineness of 6.6 dtex were obtained in the same manner as in Example 34, except that the polyester resin obtained in Example 4 was used.
A wet nonwoven fabric was produced in the same manner as in Example 33, except that the obtained heat-adhesive short fibers were used as binder fibers.

As is clear from Table 5, the side-by-side type composite fibers obtained in Examples 30 to 32 have excellent shrinkage and operability.
Both the core-sheath type and the single type heat-adhesive composite fibers obtained in Examples 33 to 35 can be obtained with good operability, and the wet non-woven fabric obtained by using this fiber as a binder fiber has strong non-woven fabric. It was excellent.

Claims (5)

It is a polyester resin containing a component derived from at least one recycled polyester raw material of a) used polyester product and b) unadopted polyester generated in the process of manufacturing the polyester product, and is the following (1) to (4). Recycled polyester resin characterized by satisfying all of.
(1) When the total amount of all acid components constituting the polyester is 100 mol%, 50 to 98 mol% is terephthalic acid and 2 to 50 mol% is isophthalic acid.
(2) When the total amount of all glycol components is 100 mol%, ethylene glycol is 70 mol% or more and diethylene glycol is 4 mol% or less.
(3) The carboxyl terminal group concentration is 40 equivalents / t or less, and the concentration is 40 equivalents / t or less.
(4) The average boosting speed is 0.6 MPa / h or less (however, the average boosted speed is a value calculated by the following procedure: using a booster tester including an extruder and a pressure sensor, the extruder Stainless steel filter at the tip (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 grain size : 12 μm) is set, the polyester resin is melted at 300 ° C. with an extruder, and the extruding is started as the pressure value applied to the filter when the melt is extruded at a discharge rate of 29.0 g / min from the filter. When the pressure value at the time is "initial pressure value (MPa)" and the pressure value at the time of continuous extrusion for 12 hours is "final pressure value (MPa)", the following calculation is performed based on those pressure values. The above average boosting speed is calculated by the formula A:
Average boost rate (MPa / h) = (final pressure value-initial pressure value) / 12) ... A) The regenerated polyester resin according to claim 1, wherein the glycol component in (2) is 1 to 10 mol% of an ethylene oxide adduct of bisphenol A. A molded product containing the recycled polyester resin according to claim 1 or 2. A fiber containing the recycled polyester resin according to claim 1 or 2. It is a method of manufacturing a recycled polyester resin using at least one recycled polyester raw material of a) used polyester product and b) unadopted polyester generated in the process of manufacturing the polyester product, and is described in the following (1) to (1) to ( A method for producing a recycled polyester resin, which comprises the step of 3).
(1) The recycled polyester raw material is added to a mixture containing ethylene terephthalate oligomer, ethylene glycol and isophthalic acid so that the molar ratio of total glycol component / total acid component is 1.05 to 1.28, and 245 to 1. Step of obtaining a reaction product containing a depolymerized product by performing depolymerization under heat treatment conditions of 280 ° C. (2) A step of passing the reaction product through a filter having a filtration particle size of 10 to 25 μm and recovering the filtrate (3). ) A step of adding a polymerization catalyst to the filtrate and performing a polycondensation reaction of the depolymerized product under a reduced pressure of 250 ° C. or higher and 1.0 hPa or lower.