JP2016011337A - Manufacturing method of recycled polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover high-quality polyester resin from a resin structure comprising a polyester resin layer.SOLUTION: In obtaining a recycled polyester from a resin structure comprising polyester resin and polyamide resin comprising a xylylene diamine-derived constitutional unit, at least a crushing step, a separation step, and a solid phase polymerization step at a specific temperature and a specific degree of vacuum are performed, in order to obtain a high-quality recycled polyester.

Description

  The present invention relates to a method for producing a recycled polyester product, in which a recycled polyester product is obtained from a resin structure containing a polyester resin and a polyamide resin.

  Polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) is formed into a bottle by, for example, blow molding, and this bottle (hereinafter abbreviated as “PET bottle”) is widely used as a container for various liquid beverages. Has been.

  Further, as polyester resins, not only PET but also other polyester resins such as polyethylene naphthalate are widely used, and they are used in various technical fields such as packaging materials as various containers, sheets, films and the like.

PET bottles used for beer, other carbonated beverages, hot beverages, and the like are required to have gas barrier properties such as oxygen gas barrier properties and carbon dioxide gas barrier properties to ensure long-term storage. Further, other polyester resins other than polyethylene terephthalate are also required to have improved gas barrier properties in order to enhance the storage stability and alteration prevention of the contents, as in the case of PET bottles.
However, the gas barrier property cannot be sufficiently supplemented with a polyester resin alone such as PET, and various improvements have been made to improve the gas barrier property.

  For example, as a method for improving gas barrier properties, a method of applying or laminating a barrier resin having a gas barrier performance higher than that of a polyester resin to a molded body or a packaging container made of the polyester resin is also known. As the barrier resin in this method, a polyamide resin, particularly a xylylene group-containing polyamide containing xylylenediamine as a structural unit is preferably used.

  The xylylene group-containing polyamide has a high gas barrier property, and also has a glass transition temperature, a melting point, and crystallinity similar to a polyester resin, particularly a widely used PET resin. Therefore, multi-layer laminates and blends such as multi-layer containers and multi-layer films in which a polyamide resin layer containing a xylylene group-containing polyamide and a polyester layer are combined have gas barrier properties, heat resistance, molding processability, transparency, and durability. Etc., and is widely used.

  By the way, in recent years, the necessity of recycling plastics has been widely recognized from the viewpoint of environmental conservation and resource saving, and efforts and laws have been promoted for recycling in various fields. Since PET bottles are mass-produced and widely used as containers for various liquid beverages, recycling is a particularly important issue in forming a recycling-oriented economic society. Further, not only used PET bottles but also reuse of other polyester resin products is an important issue from the viewpoint of resource saving and production cost reduction.

Polyester recycling can be broadly classified into chemical recycling in which the recovered polyester is decomposed and re-synthesized to the monomer level, and mechanical recycling in which the recovered polyester is returned to a reused form by separation, washing, and granulation. The former is a general recycling method in which the latter is widely used from the viewpoint of a large amount of required energy and cost, although high purity polyester can be obtained.
Particularly in recent years, so-called BtoB in which recycled polyester obtained from beverage bottles is reused in beverage bottles has been desired, and maintaining the quality of recycled polyester has become an important issue. However, polyesters such as polyethylene terephthalate that are frequently used in beverage bottles are re-pelletized for reuse. However, since a part of the process includes a plasticizing step, impurities such as acetaldehyde may be generated. Acetaldehyde may impair the flavor of foods and the like filled in the packaging container, or may impair hygiene. In order to remove impurities such as acetaldehyde from the regenerated resin, there is a method of volatilizing and removing acetaldehyde by subjecting the regenerated resin to a solid phase polymerization process and heat treatment (Patent Document 3). However, it is necessary to spend a lot of energy for solid phase polymerization, which is a problem from the viewpoint of cost and environmental load. Further, even if acetaldehyde is removed from the regenerated polyester, there is a problem that acetaldehyde is generated again when plasticizing again during molding.

On the other hand, as a removal method other than heat treatment, a method is known in which xylylene group-containing polyamide is added to regenerated polyester and acetaldehyde can be captured (Patent Documents 1 and 2). However, when a large amount of the xylylene group-containing polyamide is added, the color tone of the polyester may be affected with the thermal deterioration of the resin (Patent Document 4). In addition, there is a problem that the influence becomes more conspicuous in the recycling process through many heat treatment steps.

JP 2007-031881 A JP 2008-156444 A JP-T-2007-531642 Special table 2010-536971 gazette

  An object of the present invention is to provide a method for producing a high-quality recycled polyester product from a resin structure containing a polyester resin and a polyamide containing a structural unit derived from xylylenediamine.

  The present inventors have conducted intensive research on a method for recovering a high-quality polyester resin from a resin structure containing a polyester resin in a process based on mechanical recycling. As a result, the present inventors have found that the resin structure contains a specific amount of xylylene group-containing polyamide in addition to the polyester resin and includes a solid phase polymerization step under specific conditions, thereby containing acetaldehyde. The inventors have found that a high-quality recycled polyester product having a small amount, suppressing the energy required for processing, and having an excellent appearance can be obtained.

The present invention provides a method for producing a recycled polyester product of the following (1) to (5).
[1] A method for producing a polyester reclaimed product, in which a polyester reclaimed product is obtained from a resin structure comprising a polyester resin (A) and a polyamide resin (B) containing a structural unit derived from xylylenediamine, the production method Includes at least a pulverization step, a separation step, and a solid phase polymerization step, and the solid phase polymerization step satisfies the formulas (1) and (2).
(Mp−55) ≦ M <(mp−5) (1)
V ≦ 1.5 (2)
(M represents the material temperature in solid phase polymerization, mp represents the melting point (° C.) of the polyester resin subjected to solid phase polymerization, and V represents the degree of vacuum (torr) when the material temperature is M in the solid phase polymerization reaction)
[2] The method for producing a recycled polyester product according to [1], wherein the polyester resin (A) includes a structural unit derived from terephthalic acid as a dicarboxylic acid unit and a structural unit derived from ethylene glycol as a diol unit.
[3] The polyamide resin (B) includes a structural unit derived from xylylenediamine as a diamine unit, and a structural unit derived from an α, ω-dicarboxylic acid having 4 to 20 carbon atoms as a dicarboxylic acid unit [1]. A method for producing a recycled polyester product as described in 1.
[4] The polyester recycled product according to any one of [1] to [3], wherein a mass ratio of the polyester resin and the polyamide resin contained in the polyester recycled product is 99.99 to 93: 0.01 to 7. Production method.
[5] The method for producing a recycled polyester product according to any one of [1] to [4], wherein the recycled polyester product satisfies the following formula (3).
AA ≦ 9.0 (3)
(AA indicates the acetaldehyde concentration (ppm) contained in a piece in a 2 mm thick plate made of a recycled polyester product)
[6] The method for producing a recycled polyester product according to any one of [1] to [5], wherein the resin structure is a resin container.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of a high-quality polyester recycled product from the resin structure containing a polyester resin and a xylylene group containing polyamide.

Hereinafter, the present invention will be described in detail using embodiments.
The present invention relates to a resin structure comprising a polyester resin (A) and a polyamide (B) containing a structural unit derived from xylylenediamine (hereinafter also referred to as a xylylene group-containing polyamide), and is solidified under specific conditions. A polyester recycled product is obtained through a phase polymerization step.

Hereinafter, the resins (A) and (B) will be described in detail.
[Polyester resin (A)]
Although the polyester resin (A) used by this invention will not be specifically limited if it is a polyester resin, Usually, it is polyester which comprises the polyester resin contained in the resin structure currently distribute | circulated on the market. Although a polyester resin (A) is not specifically limited, The following are mentioned in detail.

The polyester resin (A) is a polycondensation polymer obtained by polycondensation of a dicarboxylic acid and a diol, and 70 mol% or more of the structural units derived from the dicarboxylic acid (dicarboxylic acid units) are derived from the aromatic dicarboxylic acid. And 70 mol% or more of the structural unit (diol unit) derived from diol is preferably derived from aliphatic diol.
Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, biphenyl dicarboxylic acid, diphenyl ether-dicarboxylic acid, diphenyl sulfone-dicarboxylic acid, diphenyl ketone-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalene Examples thereof include dicarboxylic acid and 2,7-naphthalenedicarboxylic acid, and terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid are preferable, and terephthalic acid is more preferable.
The aliphatic diol has a linear or branched structure such as ethylene glycol, 2-butene-1,4-diol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, methylpentanediol, and diethylene glycol. Aliphatic diols such as cycloaliphatic dimethanol, norbornene dimethanol and tricyclodecane dimethanol. Among these, ethylene glycol, neopentyl glycol, and cyclohexanedimethanol are preferable, and ethylene glycol is more preferable.

A preferred polyester resin (A) contains a constituent unit derived from terephthalic acid as a dicarboxylic acid unit and a constituent unit derived from ethylene glycol as a diol unit. Here, the dicarboxylic acid unit preferably contains 70 mol% or more of a structural unit derived from terephthalic acid, and the diol unit preferably contains 70 mol% or more of a structural unit derived from ethylene glycol. Moreover, in the polyester resin (A), the ratio of the structural unit derived from terephthalic acid in the dicarboxylic acid unit is more preferably 80 to 100 mol%, and still more preferably 90 to 100 mol%. Furthermore, the ratio of the structural unit derived from ethylene glycol in the diol unit is more preferably 80 to 100 mol%, and still more preferably 90 to 100 mol%.
As described above, by setting the proportion of units derived from terephthalic acid to 70 mol% or more, the polyester resin (A) is unlikely to be amorphous. Therefore, when the resin structure is filled with a high-temperature one inside it, It becomes difficult to heat-shrink etc., and heat resistance becomes favorable.

Further, the polyester resin (A) containing a structural unit derived from terephthalic acid as a dicarboxylic acid unit and a structural unit derived from ethylene glycol as a diol unit includes a structural unit derived from a bifunctional compound other than terephthalic acid and ethylene glycol. It may be a thing. Examples of the bifunctional compound include the above-described aromatic dicarboxylic acid and aliphatic diol other than terephthalic acid and ethylene glycol, and bifunctional compounds described later other than the aromatic dicarboxylic acid and aliphatic diol. Under the present circumstances, it is preferable that the structural unit derived from bifunctional compounds other than a terephthalic acid and ethylene glycol is 30 mol% or less with respect to the total mol of all the structural units which comprise a polyester resin (A), and 20 mol % Or less is more preferable, and more preferably 10 mol% or less.
The polyester resin (A) may not contain a structural unit derived from terephthalic acid and / or ethylene glycol, or contains a structural unit derived from a bifunctional compound other than an aromatic dicarboxylic acid or an aliphatic diol. It may be.

Examples of the bifunctional compound other than the aromatic dicarboxylic acid and the aliphatic diol include an aliphatic bifunctional compound other than the aliphatic diol and an aromatic bifunctional compound unit other than the aromatic dicarboxylic acid.
Examples of the aliphatic bifunctional compound other than the aliphatic diol include linear or branched aliphatic bifunctional compounds, and specific examples include malonic acid, succinic acid, adipic acid, azelaic acid, and sebacic acid. Aliphatic dicarboxylic acids; aliphatic hydroxycarboxylic acids such as 10-hydroxyoctadecanoic acid, lactic acid, hydroxyacrylic acid, 2-hydroxy-2-methylpropionic acid and hydroxybutyric acid.
The aliphatic bifunctional compound may be an alicyclic difunctional compound, for example, an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid, norbornenedicarboxylic acid, and tricyclodecanedicarboxylic acid; And alicyclic hydroxycarboxylic acids such as cyclohexane-carboxylic acid, hydroxymethylnorbornene-carboxylic acid and hydroxymethyltricyclodecanecarboxylic acid.
Among these, preferable alicyclic bifunctional compounds include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and the like. Copolymerized polyester resins containing structural units derived from these alicyclic bifunctional compounds are easy to produce, and can improve the drop impact strength and transparency of multilayer laminates such as multilayer containers. Of those mentioned above, 1,4-cyclohexanedicarboxylic acid is preferable because it is easily available and can have high drop impact strength.
The aromatic bifunctional compound other than the aromatic dicarboxylic acid is not particularly limited. Specific examples thereof include hydroxybenzoic acid, hydroxytoluic acid, hydroxynaphthoic acid, 3- (hydroxyphenyl) propionic acid, hydroxy Aromatic hydroxycarboxylic acids such as phenylacetic acid and 3-hydroxy-3-phenylpropionic acid; and aromatic diols such as bisphenol compounds and hydroquinone compounds.

Further, the polyester resin (A) containing a constituent unit derived from terephthalic acid as a dicarboxylic acid unit and a constituent unit derived from ethylene glycol as a diol unit comprises isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and 4,4′-biphenyl. It preferably contains a structural unit derived from an aromatic bifunctional compound selected from dicarboxylic acids. These are low in cost, and a copolyester resin containing one of these is easy to produce.
Among these, particularly preferred aromatic bifunctional compounds include isophthalic acid and naphthalenedicarboxylic acid. A copolymerized polyester resin containing a structural unit derived from isophthalic acid is excellent in that the moldability is excellent and the whitening of the molded product is prevented by slowing the crystallization rate. The proportion of the structural unit derived from isophthalic acid is preferably 1 to 10 mol%, more preferably 1 to 8 mol%, and further preferably 1 to 6 mol% of the dicarboxylic acid unit.
In addition, the copolymer polyester resin containing a structural unit derived from naphthalenedicarboxylic acid increases the glass transition point of the resin, improves heat resistance, and absorbs ultraviolet rays. It is suitably used for production. In the polyester resin (A), the proportion of the structural unit derived from naphthalenedicarboxylic acid is preferably 0.1 to 15 mol%, more preferably 1.0 to 10 mol% of the dicarboxylic acid unit. By setting it as these ratios, it becomes possible to protect appropriately the contents accommodated in a multilayer container from an ultraviolet-ray. As naphthalenedicarboxylic acid, a 2,6-naphthalenedicarboxylic acid component is preferred because it is easy to produce and economical.

  As the aromatic bifunctional compound, aromatic bifunctional compounds other than those described above may be used. Specific examples of the aromatic bifunctional compound include, but are not limited to, 2,2-bis (4- (2-hydroxyethoxyphenyl) propane, 2- (4- (2- (2-hydroxy Ethoxy) ethoxy) phenyl) -2- (4- (2-hydroxyethoxy) phenyl) propane, 2,2-bis (4- (2- (2-hydroxyethoxy) ethoxy) phenyl) propane, bis (4- ( 2-hydroxyethoxy) phenyl) sulfone, (4-((2-hydroxyethoxy) ethoxy) phenyl)-(4- (2-hydroxyethoxy) phenyl) sulfone, 1,1-bis (4- (2-hydroxyethoxy) ) Phenyl) cyclohexane, 1- (4- (2- (2-hydroxyethoxy) ethoxy) ethoxy) phenyl) -1- (4- (2-hydroxyethyl) Xyl) phenyl) cyclohexane, 1,1-bis (4- (2- (2-hydroxyethoxy) ethoxy) phenyl) cyclohexane, 2,2-bis (4- (2-hydroxyethoxy) -2,3,5, 6-tetrabromophenyl) propane, 1,4-bis (2-hydroxyethoxy) benzene, 1- (2-hydroxyethoxy) -4- (2- (2-hydroxyethoxy) ethoxy) benzene or 1,4-bis And diol units derived from (2- (2-hydroxyethoxy) ethoxy) benzene. Further, among these diols, 2,2-bis (4- (2-hydroxyethoxy) phenyl) propane, bis (4- (2-hydroxyethoxy) phenyl) sulfone and 1,4-bis (2-hydroxyethoxy) ) Benzene is preferred because it has excellent melt stability and is easy to produce, and these copolyester resins have excellent color tone and excellent impact resistance.

The polyester resin (A) may contain a structural unit derived from a monofunctional compound such as a monocarboxylic acid, a monoalcohol, or an ester-forming derivative thereof. Specific examples of these compounds include benzoic acid, o-methoxybenzoic acid, m-methoxybenzoic acid, p-methoxybenzoic acid, o-methylbenzoic acid, m-methylbenzoic acid, p-methylbenzoic acid, 2,3 -Dimethylbenzoic acid, 2,4-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, 2,6-dimethylbenzoic acid, 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, 2,4,6 -Trimethylbenzoic acid, 2,4,6-trimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 1-naphthoic acid, 2-naphthoic acid, 2-biphenylcarboxylic acid, 1-naphthalene acetic acid and 2-naphthalene acetic acid Aromatic monofunctional carboxylic acids such as propionic acid, butyric acid, n-octanoic acid, n-nonanoic acid, myristic acid, pentadecanoic acid, stearic acid, oleic acid, linoleic acid Aliphatic monocarboxylic acids such as linolenic acid; ester-forming derivatives of these monocarboxylic acids, aromatic alcohols such as benzyl alcohol, 2,5-dimethylbenzyl alcohol, 2-phenethyl alcohol, phenol, 1-naphthol and 2-naphthol Aliphatic or alicyclic such as butyl alcohol, hexyl alcohol, octyl alcohol, pentadecyl alcohol, stearyl alcohol, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, polytetramethylene glycol monoalkyl ether, oleyl alcohol and cyclododecanol And the formula monoalcohol.
Among these, benzoic acid, 2,4,6-trimethoxybenzoic acid, 2-naphthoic acid, stearic acid, and stearyl alcohol are preferable from the viewpoint of ease of polyester production and production costs thereof. The proportion of the structural unit derived from the monofunctional compound is 5% by mole or less, preferably 3% or less, more preferably 1% or less, based on the total moles of all the structural units of the polyester resin (A). A monofunctional compound functions as an end group of a polyester resin molecular chain or an end group of a branched chain, thereby suppressing excessive crosslinking of the polyester resin (A) and preventing gelation.

Furthermore, the polyester resin (A) may have a polyfunctional compound having at least three groups selected from a carboxyl group, a hydroxy group, and an ester-forming group thereof as a copolymerization component. Examples of the polyfunctional compound include aromatic polycarboxylic acids such as trimesic acid, trimellitic acid, 1,2,3-benzenetricarboxylic acid, pyromellitic acid, and 1,4,5,8-naphthalenetetracarboxylic acid; Alicyclic polycarboxylic acids such as 1,3,5-cyclohexanetricarboxylic acid; aromatic polyhydric alcohols such as 1,3,5-trihydroxybenzene; trimethylolpropane, pentaerythritol, glycerin and 1,3,5- Aliphatic or cycloaliphatic polyhydric alcohols such as cyclohexanetriol; 4-hydroxyisophthalic acid, 3-hydroxyisophthalic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, protocatechuic acid, gallic acid and 2,4-di Aliphatic hydroxycarboxylic acids such as tartaric acid and malic acid; aromatic hydroxycarboxylic acids, such as hydroxyphenyl acetic acid and their esters are mentioned.
It is preferable that the ratio of the structural unit derived from a polyfunctional compound in a polyester resin (A) is less than 0.5 mol% with respect to the total number of moles of all the structural units of polyester.
Among the above-mentioned compounds, preferable polyfunctional compounds include trimellitic acid, pyromellitic acid, trimesic acid, trimethylolpropane, and pentaerythritol from the viewpoint of ease of production of the polyester resin (A) and production cost. .

Furthermore, the polyester resin (A) may contain a structural unit derived from a metal sulfonate group-containing compound (hereinafter referred to as a metal sulfonate unit).
The structural unit derived from the metal sulfonate group-containing compound can be introduced into the polyester resin (A) by using the metal sulfonate group-containing compound as a copolymer component of the polyester resin (A).
The metal sulfonate group-containing compound is represented by the formula: X—R, X is a dicarboxylic acid or diol, and R is —SO ₃ M. M is represented by a metal in the +1 or +2 state that can be selected from Li, Na, Zn, Sn, K and Ca. Among these, M is preferably Na or Li for ease of production. The metal sulfonate group-containing compound contains two or more functional groups, and R is directly bonded to a side chain such as a diol, an aromatic ring of X which is a dicarboxylic acid, or a methylene group.

X in the formula is not particularly limited. For example, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl-4,4-dicarboxylic acid and other aromatic dicarboxylic acids; oxalic acid, malonic acid , Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and other linear aliphatic dicarboxylic acids; cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids such as 1 Excluded are examples. Among these, isophthalic acid is preferable from the viewpoint of ease of production.
X in the formula is a straight chain such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and diethylene glycol. Examples thereof include those obtained by removing one hydrogen atom from a cycloaliphatic glycol; cyclohexanediol such as 1,3-cyclohexanediol, and alicyclic diol such as cyclohexanedimethanol. Of these, ethylene glycol, diethylene glycol and cyclohexanediol are preferred.
The amount of the metal sulfonate unit (—SO ₃ M) in the polyester resin (A) is 0.05 to 10 mol% with respect to the dicarboxylic acid unit when X is a diol, and when X is a dicarboxylic acid. The range is more preferably 0.1 to 5 mol%, further preferably 0.2 to 4 mol%, and most preferably 0.4 to 2 mol%. The amount of metal sulfonate can be measured by measuring the amounts of sulfur and metal in the polymer and converting them to molar amounts.

  For the production of the polyester resin (A), a direct esterification method or a transesterification method, which are known methods, can be applied. Polycondensation catalysts used in the production of the polyester resin (A) include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. However, the present invention is not limited to these. Further, as another production method, a method of transesterifying different kinds of polyester resins (A) by a method such as a long residence time and / or high temperature extrusion can be mentioned.

  The polyester resin (A) is a dimer of an ethylene glycol component, and may contain a small amount of diethylene glycol by-product units formed in a small amount in the polyester resin production process. In order to maintain good physical properties of the resin structure, the proportion of diethylene glycol units in the polyester resin is preferably as low as possible. The proportion of the structural units derived from diethylene glycol is preferably 3 mol% or less, more preferably 1 to 2 mol%, based on all the structural units of the polyester resin (A).

Preferable polyester resin (A) is not particularly limited, but polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6 -Naphthalene dicarboxylate resin, polyethylene-2,6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyl dicarboxylate resin, poly-1,3-propylene-terephthalate resin, poly Butylene terephthalate resin, polybutylene-2,6-naphthalene dicarboxylate resin, sodium sulfoisophthalate copolymer polyethylene terephthalate resin, sodium sulfoisophthalate copolymer Examples thereof include polymerized polyethylene terephthalate-isophthalate copolymer resin, lithium sulfoisophthalate copolymer polyethylene terephthalate resin, lithium sulfoisophthalate copolymer polyethylene terephthalate-isophthalate copolymer resin, and the like. More preferable polyester resins (A) include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin, and polyethylene-2,6-naphthalene. Examples thereof include dicarboxylate resin, sodium sulfoisophthalate copolymer polyethylene terephthalate resin, and lithium sulfoisophthalate copolymer polyethylene terephthalate resin.
A polyester resin (A) may use 2 or more types of polyester resins together.

  The moisture content of the polyester resin (A) is preferably 200 ppm or less, and more preferably 100 ppm or less. When the moisture content is within the above range, the polyester does not hydrolyze during molding or the like, and the molecular weight does not extremely decrease. The polyester resin may be one whose moisture content has been reduced by drying or the like before being molded into a resin structure.

  The intrinsic viscosity of the polyester resin (A) (phenol / 1,1,2,2, -tetrachloroethane = value measured at 25 ° C. in a mixed solvent of 60/40 mass ratio) is not particularly limited, but is usually 0.00. It is desired to be 5 to 2.0 dl / g, preferably 0.6 to 1.5 dl / g. When the intrinsic viscosity is 0.5 dl / g or more, the molecular weight of the polyester resin (A) is sufficiently high, so that the resin structure can exhibit the mechanical properties necessary for the structure. In addition, intrinsic viscosity is measured by the measuring method mentioned later.

Further, the polyester resin (A) may contain a material derived from recycled polyester, used polyester, or industrial recycled polyester (for example, polyester monomer, catalyst, and oligomer).

[Polyamide resin (B)]
The polyamide resin (B) is a polyamide resin containing a structural unit derived from xylylenediamine. Although a polyamide resin (B) is not specifically limited, For example, the following are mentioned.

The polyamide resin (B) is obtained by polycondensation of a diamine containing xylylenediamine and a dicarboxylic acid. The polyamide resin (B) contains 70 mol% or more of structural units derived from xylylenediamine among the structural units derived from diamine (diamine units), preferably 80 to 100 mol%, more preferably 90 to 100 mol%. contains.
As xylylenediamine, metaxylylenediamine, paraxylylenediamine, or both are preferable, but metaxylylenediamine is more preferable. Moreover, the diamine unit which comprises a polyamide resin (B) contains 70 mol% or more of structural units derived from metaxylylenediamine, preferably 80-100 mol%, more preferably 90 mol% -100 mol%. Polyamide resin (B) can express the outstanding gas barrier property because the metaxylylene diamine unit in a diamine unit is 70 mol% or more.

  The diamine unit in the polyamide resin (B) may be composed only of a structural unit derived from xylylenediamine, but may contain a structural unit derived from diamine other than xylylenediamine. Here, as diamines other than xylylenediamine, tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, Aliphatic diamines having a linear or branched structure such as 2,2,4-trimethyl-hexamethylenediamine and 2,4,4-trimethyl-hexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4 -Bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) Examples include alicyclic diamines such as carin and bis (aminomethyl) tricyclodecane; diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, and bis (aminomethyl) naphthalene. It is not limited to these.

Examples of the compound that can constitute the dicarboxylic acid unit in the polyamide resin (B) include succinic acid, glutaric acid, pimelic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, etc. ~ 20 α, ω-linear aliphatic dicarboxylic acid; alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid; other aliphatic dicarboxylic acid such as dimer acid; terephthalic acid, isophthalic acid, orthophthalic acid, Aromatic dicarboxylic acids such as xylylene dicarboxylic acid and naphthalene dicarboxylic acid can be exemplified, but are not limited thereto. Among these, adipic acid and sebacic acid are preferable, and adipic acid is more preferable from the viewpoint of improving the barrier performance.
It is preferable that a polyamide resin (B) contains 70 mol% or more of structural units derived from adipic acid among dicarboxylic acid units, more preferably 80-100 mol%, still more preferably 90-100 mol%.

  The polyamide resin (B) is particularly preferably a polyamide resin in which 70 mol% or more of the diamine structural unit is derived from metaxylylenediamine and 70 mol% or more of the dicarboxylic acid structural unit is derived from adipic acid. . The polyamide resin having such a monomer composition and constitutional unit has good barrier properties, and also has good processability of the resin structure because the moldability is similar to that of a polyester resin (A) such as polyethylene terephthalate resin. Easy to do. In this polyamide resin, as the compound constituting the dicarboxylic acid unit other than adipic acid, one or more of α, ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms are preferably used.

  Moreover, as preferable polyamide resin (B), 70 mol% or more of diamine structural units are derived from metaxylylenediamine, and 70 to 99 mol% of dicarboxylic acid structural units are derived from adipic acid, and 1 to 30 mols. A polyamide in which% is derived from isophthalic acid can also be exemplified. By adding an isophthalic acid unit as a dicarboxylic acid unit, the melting point can be lowered, and the molding processing temperature can be lowered, so that thermal deterioration during molding can be suppressed, and stretch moldability is improved by delaying the crystallization time. improves.

  Further, as the polyamide resin (B) that can be preferably used in the present invention, a polyamide in which 70 mol% or more of the diamine structural unit is derived from metaxylylenediamine and 70 mol% or more of the dicarboxylic acid structural unit is derived from sebacic acid is also available. It can also be illustrated. When the dicarboxylic acid unit contains 70 mol% or more of sebacic acid units, it is possible to avoid a decrease in gas barrier properties and an excessive decrease in crystallinity, a low melting point, and a reduction in molding processing temperature, resulting in gel formation. Can be suppressed. In this polyamide resin, as a compound that can constitute a dicarboxylic acid unit other than sebacic acid, one or more of α, ω-linear aliphatic dicarboxylic acids having 4 to 20 carbon atoms are preferably used.

  In addition to the diamine and dicarboxylic acid, as a component constituting the polyamide resin (B), lactams such as ε-caprolactam and laurolactam, aminocaproic acid, aminoundecanoic acid and the like are included as long as the effects of the present invention are not impaired. Aliphatic aminocarboxylic acids; aromatic aminocarboxylic acids such as p-aminomethylbenzoic acid can also be used as copolymerization components.

  The polyamide resin (B) is preferably produced by a polycondensation reaction in a molten state (hereinafter sometimes referred to as “melt polycondensation”). For example, a nylon salt composed of a diamine component constituting a diamine unit and a dicarboxylic acid anomaly constituting a dicarboxylic acid unit is heated in a pressure method in the presence of water, and in a molten state while removing added water and condensed water. It is preferable to produce by a polymerization method. Moreover, you may manufacture by the method of adding a diamine component directly to the dicarboxylic acid component of a molten state, and carrying out the polycondensation under a normal pressure. In this case, in order to keep the reaction system in a uniform liquid state, the diamine component is continuously added to the dicarboxylic acid component, and during that time, the reaction system is increased so that the reaction temperature does not fall below the melting point of the generated oligoamide and polyamide. It is preferable to proceed polycondensation while warming. In addition, about a polyamide resin (B), molecular weight can also be raised by further solid-phase-polymerizing what was obtained by melt polycondensation as needed.

The polyamide resin (B) may be polycondensed in the presence of a phosphorus atom-containing compound. When the polyamide resin (B) is polycondensed in the presence of a phosphorus atom-containing compound, the processing stability at the time of melt molding is enhanced, and coloring is easily prevented.
Preferable specific examples of the phosphorus atom-containing compound include a hypophosphorous acid compound (also referred to as a phosphinic acid compound or a phosphonic acid compound), a phosphorous acid compound (also referred to as a phosphonic acid compound), and the like. Is not to be done. The phosphorus atom-containing compound may be an organic metal salt or an alkali metal salt.
Specific examples of hypophosphorous acid compounds include hypophosphorous acid; hypophosphorous acid metal salts such as sodium hypophosphite, potassium hypophosphite, lithium hypophosphite; ethyl hypophosphite, dimethylphosphine Hypophosphorous acid compounds such as acid, phenylmethylphosphinic acid, phenylphosphonous acid, and phenylphosphonous acid ethyl; metal phenylphosphonous acid salts such as sodium phenylphosphonous acid, potassium phenylphosphonous acid, and lithium phenylphosphonous acid Etc.
Specific examples of the phosphite compound include phosphorous acid, pyrophosphorous acid; metal phosphites such as sodium hydrogen phosphite and sodium phosphite; triethyl phosphite, triphenyl phosphite, ethylphosphone Phosphorous acid compounds such as acid, phenylphosphonic acid, diethyl phenylphosphonate; phenylphosphonic acid metal salts such as sodium ethylphosphonate, potassium ethylphosphonate, sodium phenylphosphonate, potassium phenylphosphonate, lithium phenylphosphonate, etc. Can be mentioned.
One type of phosphorus atom-containing compound may be used, or two or more types may be used in combination. Among these, metal hypophosphite such as sodium hypophosphite, potassium hypophosphite, lithium hypophosphite and the like from the viewpoint of the effect of promoting the polymerization reaction of the polyamide resin (B) and the anti-coloring effect. Salts are preferred, and sodium hypophosphite is more preferred.

The polycondensation of the polyamide resin (B) is preferably performed in the presence of a phosphorus atom-containing compound and an alkali metal compound. In order to prevent the polyamide resin (B) from being colored during the polycondensation, a sufficient amount of the phosphorus atom-containing compound must be present. However, if the amount of the phosphorus atom-containing compound used is too large, the amidation reaction rate is accelerated. This is likely to cause gelation of the polyamide resin (B). Therefore, it is preferable to coexist an alkali metal compound from the viewpoint of adjusting the amidation reaction rate.
Although it does not specifically limit as an alkali metal compound, An alkali metal hydroxide and an alkali metal acetate can be mentioned as a preferable specific example. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Examples of the alkali metal acetate include lithium acetate, sodium acetate, potassium acetate, and acetic acid. Examples include rubidium and cesium acetate.
When an alkali metal compound is used when polycondensing the polyamide resin (B), the amount of the alkali metal compound used is determined from the number of moles of the alkali metal compound from the viewpoint of suppressing the formation of gel. The value divided by is preferably 0.5 to 1, more preferably 0.55 to 0.95, and still more preferably 0.6 to 0.9.

  The number average molecular weight of the polyamide resin (B) is appropriately selected depending on the use of the resin structure and the molding method, but is usually about 10,000 to 40,000 from the viewpoint of moldability and strength of the resin structure. From the above viewpoint, the number average molecular weight of the polyamide resin (B) is more preferably about 11000 to 25000, and still more preferably about 13,000 to 18000.

The number average molecular weight of the polyamide resin (B) is calculated from the following formula (X).
Number average molecular weight = 2 × 1000000 / ([COOH] + [NH2]) (X)
(In the formula, [COOH] represents the terminal carboxyl group concentration (μmol / g) in the polyamide resin (B), and [NH ₂ ] represents the terminal amino group concentration (μmol / g) in the polyamide resin (B). .)
Here, the terminal amino group concentration was obtained by neutralizing and titrating a solution of polyamide dissolved in a phenol / ethanol mixed solution with a dilute hydrochloric acid aqueous solution, and the terminal carboxyl group concentration was determined by dissolving polyamide in benzyl alcohol. The value calculated by neutralization titration with an aqueous sodium hydroxide solution is used.

The moisture content of the polyamide resin (B) is preferably 0.15% by mass or less, more preferably 0.1% by mass or less. When the moisture content is 0.15% by mass or less, hydrolysis of the polyester resin (B) caused by moisture generated from the polyamide resin (B) during molding can be suppressed.
The polyamide resin (B) may be dried before being molded into a resin structure, and drying can be performed by a known method. For example, a method in which polyamide resin is charged in a heatable tumbler (rotary vacuum tank) equipped with a vacuum pump or in a vacuum dryer, and heated at a temperature below the melting point of the polymer, preferably below 160 ° C., and dried under reduced pressure. Examples of the method include, but are not limited to, a method of removing moisture in the polymer by reducing the pressure of the vent hole when the polyamide resin is melt-extruded by an extruder with a vent.

[Resin structure]
Next, the resin structure will be described. The resin structure used in the present invention contains a polyester resin (A) and a polyamide resin (B). As the resin structure, a multilayer laminate having at least one polyester resin layer containing a polyester resin (A) and at least one polyamide resin layer containing a polyamide resin (B), or a polyester resin (A) and a polyamide resin (B) And blends having at least one layer composed of a resin composition obtained by melt-kneading the above.

The resin structure used in the present invention is preferably a used product. Here, the “used product” includes a product obtained by collecting a resin structure once distributed as a beverage container or the like in the form of a bottle or the like. Further, the “used product” in the present invention is not limited to the recovered product used in the beverage container or the like, and is, for example, a defective preform (parison) at the time of blow molding, at the time of manufacturing a film or a sheet It may be a defective product or various regrinds in the molding process, such as a cut product at the end of the material. That is, the resin structure that is a raw material used in the present invention includes not only a used resin structure that has been distributed in the market and used as a beverage container or the like, but also a defective product and a recycle product that are generated in the molding process. Grinds may be included.

<Blend>
Examples of the blend that is the resin structure of the present invention include a monolayer or a multilayer having at least one layer composed of a resin composition obtained by melt-kneading a polyamide resin (B) in a polyester resin (A). In the layer composed of the resin composition, the polyamide resin (B) is preferably finely dispersed uniformly in the polyester resin (A). Examples of the shape of the blend include containers (for example, bottles), films, sheets, pipes and the like. Among these, a storage container that can store various articles is preferable, and a liquid beverage container is more preferable.

<Multilayer laminate>
The multilayer laminate as the resin structure of the present invention has a structure having at least one polyester resin layer containing a polyester resin (A) and at least one polyamide resin layer containing a polyamide resin (B). The shape of the multilayer laminate is not particularly limited, and examples thereof include multilayer containers (for example, multilayer bottles), multilayer films, multilayer sheets, multilayer pipes, and other multilayer laminates. Among these, it is preferable that it is a multilayer container used as a storage container which can store various articles | goods, and a liquid drink container is more preferable.

<Configuration of multilayer laminate>
The layer structure of the multilayer laminate is not particularly limited, and the number and type of the layer (A) and the polyester layer (B) made of the polyester resin (A) are not particularly limited. For example, (A) / (B) configuration composed of one polyester resin layer and one polyamide resin layer, (B) / (A) configuration may be used, and one polyamide resin layer and two layers A three-layer structure of (A) / (B) / (A) made of a polyester resin layer may be used. Further, it may have a five-layer structure of (A) / (B) / (A) / (B) / (A) composed of two polyamide resin layers and three polyester resin layers. Moreover, in the case of a multilayer container, it is preferable that an adhesive layer is not interposed between the polyester resin layer and the polyamide resin layer from the viewpoint of heat resistance and molding processability. In addition, a resin layer that is difficult to separate from the polyester resin is preferably not contained in the multilayer laminate from the viewpoint of efficiently recovering the polyester resin.

<Method for molding resin structure>
Examples of the shape of the multilayer structure of the present invention include the shapes of bottles, sheets, sheets, and tubes as described above. The bottle is preferably a blow molded container or a preform thereof. More preferably, the multi-layer bottle is a co-extruded multi-layer preform (multi-layer parison) formed by direct blow, and the blend bottle is a preform obtained by melt blending (parison) formed by direct blow, Examples include a preform formed by stretch blow.
The sheet and film can be produced by a coextrusion method, a dry lamination method, an extrusion lamination method, or the like. In order to produce a stretched multilayer film, the stretched multilayer film can be produced by a stretching method of the multilayer film, a lamination method of the stretched films, or the like. The multilayer sheet and the multilayer film can also be produced by an inflation method. The multilayer pipe can be manufactured by a coextrusion method.

  The mass ratio of the polyester resin (A) and the polyamide resin (B) in the resin structure is usually in the range of 99.5: 0.5 to 55:45. This mass ratio can be appropriately determined depending on the shape of the resin structure and the purpose of use. In the resin structure for the purpose of improving the gas barrier property by the polyamide resin layer, this mass ratio is preferably 99: 1 to 80:20, more preferably from the viewpoint of balancing gas barrier property, mechanical strength, heat resistance and the like. Is in the range of 98.5: 1.5 to 90:10. However, the present invention can also be applied to storage containers that are outside the range of these mass ratios.

  When the resin structure is a multilayer laminate, the thickness of the polyester resin layer (total thickness in the case of a plurality of layers) is determined by making the polyester resin (A) and the polyamide resin (B) within a desired mass ratio range. The ratio to the thickness of the polyamide resin layer (total thickness in the case of a plurality of layers) can be arbitrarily set, but the thickness of the polyamide resin layer is preferably thinner than the thickness of the polyester resin layer. The ratio of (polyester resin layer thickness / polyamide resin layer thickness) in the multilayer laminate is 2 or more, more preferably 4 or more. When the polyamide resin layer is thinner than the polyester resin layer, a difference occurs in the specific gravity of each layer, and the polyester resin (A) is easily separated from the polyamide resin (B).

The thickness of the resin structure is usually 70 μm to 7 mm, preferably 100 μm to 5 mm, more preferably 150 μm to 3 mm. When the resin structure is a multilayer laminate, the thickness of the polyester resin (total thickness in the case of a plurality of layers) is usually 30 μm to 6.9 mm, more preferably 50 μm to 4.5 mm, and still more preferably 100 μm to 2.5 mm. The thickness of the polyamide resin layer (the total thickness in the case of a plurality of layers) is usually 0.5 to 500 μm, preferably 1 to 200 μm.
Moreover, when a resin structure is a multilayer laminated body, the total layer thickness is 100 micrometers-5 mm normally, Preferably it is 150 micrometers-3 mm, More preferably, it exists in the range of 300 micrometers-2 mm. Moreover, the thickness (total thickness in the case of a plurality of layers) of the polyester resin layer is usually 50 μm to 4.5 mm, preferably 100 μm to 2.5 mm, more preferably 150 μm to 1 mm. The thickness of the polyamide resin layer (the total thickness in the case of a plurality of layers) is usually 1 to 200 μm, preferably 3 to 100 μm.

Moreover, in the trunk | drum of a multilayer container, although the polyamide resin layer may be provided over the perimeter, it may be provided partially in the circumferential direction.
When the polyamide resin layer is partially provided in the circumferential direction, for example, the polyamide resin layer is preferably subdivided into stripes and laminated between the polyester resin layers. As a multilayer container in which the polyamide resin layer is subdivided into stripes, the polyamide resin layer of the polyester resin layer is subdivided into a plurality in the circumferential direction by a plurality of longitudinal belt-like intervals extending along the axial direction (For example, see Patent Document 4953178). In the multilayer container having such a structure, since the polyester resin layer enters into the longitudinal belt interval, the subdivided polyamide resin layer is constrained from both sides by the polyester resin layer that has entered between them, whereby the polyester resin layer And the delamination resistance between the polyamide resin layer and the polyamide resin layer are enhanced.

Moreover, the polyester resin (A) and the polyamide resin (B) may contain various additive components. Examples of the additive component include a colorant, a heat stabilizer, a light stabilizer, a moisture proofing agent, a waterproofing agent, a lubricant, a reheat agent, and a deodorizing agent.
Various oxygen absorbents may be added for the purpose of imparting oxygen absorbability to the resin structure. For example, for polyester resin (A), butadiene copolymer polyester, cyclodiene copolymer polyester, or heavy metals such as iron powder and copper, and for polyamide resin (B), butadiene copolymer polymer, cobalt, Heavy metal salts such as manganese are preferably used. Any oxygen absorbent is preferably used for the blend.
Each of the polyester resin layer and the polyamide resin layer may contain a resin component other than the polyester resin (A) and the polyamide resin (B) within a range not departing from the object of the present invention. For example, the polyamide resin layer may contain a polyamide other than the above-described polyamide resin (B). Examples of such polyamides include low-elastic modulus polyamides having a lower elastic modulus than that of the polyamide resin (B). Specifically, nylon 6, nylon 66, nylon 46, nylon 610, nylon 612, nylon 11, nylon 12, caprolactam-hexamethylene adipamide copolymer (nylon 666) and the like.

[Production method of recycled polyester]
The method for producing a recycled polyester product of the present invention includes a step of obtaining a high-quality polyester recycled product from the pulverized product through a pulverizing step of pulverizing the above-described resin structure.
Hereinafter, each of these steps will be described in more detail.

<Crushing process>
The resin structure can be pulverized using a pulverizer such as a single-screw pulverizer, a biaxial pulverizer, a triaxial pulverizer, or a cutter mill. Specifically, a rotor having a plurality of rotating blades attached to a peripheral portion in a housing having a plurality of fixed blades accommodated therein is accommodated, and the tip of each rotating blade rotating by the rotation of the rotor. The solid material is crushed by cutting between the tips of the fixed blades. Among the pulverized materials, those that have passed through a screen of a predetermined mesh are obtained as pulverized products. Further, the storage container may be subjected to pulverization as it is, but may be used after having been reduced in volume by a compression process in advance.
Further, the pulverized product obtained by pulverization (primary pulverization) with each of the pulverizers may be further pulverized (secondary pulverization) with a freeze pulverizer or the like to further reduce the size. The freeze pulverizer further pulverizes the one frozen with liquid nitrogen or the like.
However, the pulverization method is not limited to these, and any known method can be used as long as the pulverized product is pulverized so as to have a predetermined size described later.
The resin structure to be subjected to the pulverization step is not limited as long as it is the above-described resin structure, but it is preferable to put a plurality of resin structures into a pulverizer at a time, more preferably a plurality of recovered used More preferably, the resin structure is put into a pulverizer at once.

The pulverized product obtained by pulverization in the pulverization step and used in the separation step described later is, for example, flakes, powders, or lumps, but preferably includes flakes. The pulverized product having a flake shape refers to a flake shape or a flat shape.
The particle size distribution of the pulverized product is preferably 90% by mass or more with respect to the entire pulverized product, and 95% by mass passes through the sieve having a hole diameter of 8 mm. More preferably, it is 99 mass% or more.
The particle size distribution of the pulverized product is preferably 10% by mass or less based on the entire pulverized product through the sieve having a hole diameter of 0.8 mm. Preferably, the particle size distribution of the pulverized product is more preferably 5% by mass or less, more preferably 1% by mass or less, through a sieve having a circular hole having a hole diameter of 0.8 mm. .
However, the pulverized product may be a finely pulverized product in which the amount passing through a sieve having a circular hole having a hole diameter of 0.8 mm is greater than 10% by mass with respect to the entire pulverized product. The finely pulverized product is usually a powdered pulverized product. The powdered pulverized product has a smaller diameter than the pulverized product of the above-mentioned coarsely pulverized product, and has a substantially spherical shape or a shape close thereto. More specifically, the powdered pulverized product preferably has an equivalent circle diameter of 300 to 3000 μm, and more preferably 500 to 2000 μm. The equivalent circle diameter includes a method of measuring the volume distribution with a laser diffraction scattering particle size measurement device (Microtrack; manufactured by Nikkiso Co., Ltd.) and calculating the equivalent circle diameter as an arithmetic average diameter.

  The resin structure of the present invention is usually a coarsely pulverized product by the primary pulverization described above. Usually, since the resin structure is a thin one having a thickness of several mm or less, most of the coarsely pulverized product is usually a flaky pulverized product. In addition, when the pulverized product includes a product obtained by pulverizing a bottle-shaped resin structure, in addition to the flaky pulverized product, a pulverized pulverized product is often included. This is because the pulverized product of the trunk portion is generally a flake-like pulverized product, but the product obtained by pulverizing the neck and bottom becomes a crushed pulverized product. Further, the coarsely pulverized product can be made into a powdery finely pulverized product by further secondary pulverization as described above.

When the resin structure is a multilayer structure, the polyamide resin layer and the polyester resin layer are not bonded to each other, but are integrated on the structure. The integrated resin layer may be separated as a separate body by pulverization in the pulverization step and then subjected to a separation step described later. As described above, when the polyamide resin and the polyester resin are separated as much as possible in the pulverized product, the polyester resin can be easily recovered with high purity in the separation step described later, but on the other hand, a large amount of acetaldehyde may remain.
For example, in a multilayer structure, a container in which the peel resistance between a polyamide resin layer and a polyester resin layer is not reinforced (hereinafter also referred to as a normal container) is being crushed by the above-described primary pulverization. The flakes are peeled off from the polyester resin layer. Therefore, in the coarsely pulverized product, the polyester resin and the polyamide resin tend to exist as separate bodies.

Further, as described above, the resin structure is currently formed from a multilayer laminate including a polyamide resin layer and a polyester resin layer, or a blend (single layer) including a resin composition composed of a polyamide resin and a polyester resin. Many storage containers made of polyester resin that do not contain the polyamide resin (B) such as those formed from a single body and multilayer body) and polyester resin layers are also in circulation. Therefore, what is used for a grinding | pulverization process may contain things other than the resin structure prescribed | regulated by this invention.
In addition to the multilayer laminates and blends containing the polyester resin (A) and polyamide resin (B) described above, the resin structures recovered from the market include containers containing vinyl chloride, colored containers, and storage containers. Some of them contain various impurities that may affect the deterioration of the quality of the recycled polyester product, such as a sticking label, but these are preferably removed before the pulverization step by machine sorting or manual work.

<Separation process>
In the separation step, among the crushed material provided, the crushed material with the label and adhesive residue attached, and the pulverized material with a high polyamide resin content are separated and removed from the pulverized material with a high polyester resin content, This is a step of separating and recovering a pulverized product having a high polyester resin content.
In the separation process, using the friction that occurs naturally or the attractive force caused by the charge generated on the surface by the charging process described later, the method of separating and sorting the pulverized material by electrostatic separation process and the difference in specific gravity of various materials are used. Specific gravity sorting method. By performing the sorting, the separation efficiency of the polyester resin can be increased. Specific gravity sorting includes, specifically, wind sorting in which pulverized material is sorted by wind, a method of separating by immersing in a liquid such as water, and separating by the specific gravity difference of the pulverized material relative to the liquid, giving a certain vibration to the pulverized material, Examples include a method of separating and separating different pulverized products. For example, in the rotator device for generating airflow, the crushed material applied to the airflow generated by the rotator has a specific gravity or a bulk specific gravity that is large and drops naturally due to its own weight, and a specific gravity or bulk specific gravity. However, any device may be used as long as it is a known device.

The wind sorting may be performed before pulverization or after pulverization, but is preferably performed before granulation described later. This is because the resin is easily wound up by the air current before granulation.
In addition, when the resin structure is pulverized into powder, sorting by wind force may be difficult or inefficient. Therefore, when electrostatically separating a powdered pulverized product, it is desirable to perform wind sorting before pulverization. For example, it may be performed between the primary pulverization and the secondary pulverization in the pulverization step.
In the wind sorting, for example, a part of the polyamide resin (B) may be removed in addition to separating and removing the label attached to the multilayer container or the like. The pulverized product having a high content of the polyester resin (A) usually has a high specific gravity and bulk specific gravity. Therefore, in this step, the material that naturally falls by its own weight is usually recovered and used for the next step.
The specific gravity sorting step is usually performed after the resin structure is pulverized, but may be performed before pulverization.

  As another specific gravity selection apparatus, for example, a material that moves an inclined plate with a vibration device moves upward when the specific gravity or bulk specific gravity is small, and moves downward when the specific gravity or bulk specific gravity is large. However, other known devices may be used. Further, the above-described wind sorting and other specific gravity sorting may be used in combination.

By the separation step, the pulverized product having a high polyamide resin content is separated and removed from the pulverized product having a high polyester resin content, and the pulverized product having a high polyester resin content is separated and recovered. The pulverized product obtained after the separation step is further processed in a washing step, a crystallization step, a solid phase polymerization step, etc., which will be described later, but the polyamide content in the recycled polyester product as the final product is almost determined in the separation step. . The polyamide content (B) in the pulverized product after the separation step is preferably 99.9 to 93: 0.1 to 7, more preferably the mass ratio of the polyester resin (A) and the polyamide resin (B). The mass ratio is 99.8 to 95: 0.2 to 5% by mass. By setting the polyamide content in the pulverized product after the separation step within the above range, the obtained polyester regenerated product has excellent color tone.

<Washing process>
Furthermore, when the resin structure is a used container or the like, the method of the present invention may include a washing step of washing the resin structure in order to remove the contents attached to the container or the like. The washing is preferably performed by rinsing with a liquid, and washing with water, washing with an alkaline aqueous solution, or both may be performed. In washing with an alkaline aqueous solution, a surfactant may be included in the solution. Washing may be sprayed in the form of a shower, or the container or its pulverized product may be immersed in a liquid. The cleaning liquid may be in a heated state.
The washing may be performed before the resin structure is pulverized into a pulverized product, or may be performed after pulverization. When it is performed after pulverization, it may be performed before the separation step or after the separation step, but is preferably performed before any one of granulation, crystallization, and solid phase polymerization.
The washing step may be performed before the pulverization step, or may be performed simultaneously with the pulverization step by a pulverizer that performs washing and pulverization at the same time called a wet pulverizer.

<Drying process>
When the cleaning process is performed, the drying process may be performed after the cleaning process. By performing the drying step, it is possible to reduce the moisture content of the polyester regenerated product obtained by this method, so that it is possible to provide a high-quality polyester regenerated product with high thermal stability and the like. A drying process can be performed using the ventilation or hot air by a dryer, for example.

<Sieving process>
Moreover, the method of this invention may include the sieving process which sifts a ground material with the sieve which has a predetermined mesh, and removes fine powder. The sieving step is preferably performed before the separation step. The mesh diameter of the sieve is preferably 0.8 to 10 mm, more preferably 1 to 8 mm as a circular diameter. By sieving the pulverized product, it is possible to reduce the non-uniformity of the thermal history that the pulverized product receives in the subsequent process.
The sieving step is preferably performed at the same time as the above-described washing step or prior to the washing step. For example, the pulverized product is sprayed on the sieve, and the pulverized product remaining on the sieve is immersed in a liquid, or on the sieve. The remaining pulverized product may be washed with a liquid.
Moreover, the removal of fine powder by sieving may be performed together in the above-described specific gravity selection step.

<Solid-state polymerization process>
The method for producing a recycled polyester product of the present invention includes a solid phase polymerization step for the purpose of removing volatile impurities contained in the used polyester and improving the moldability of the bottle by increasing the molecular weight of the used polyester. . By including this step, the quality of the obtained recycled polyester is improved, and the polyester resin can be reused as BtoB. Further, by including a solid phase polymerization step, the molecular weight of the regenerated polyester is improved and the molding processability is improved, and a container using the regenerated polyester can obtain sufficient strength.
In solid-phase polymerization, the polyester resin is held for a long time at high temperatures, so the presence of non-volatile impurities such as polyolefin or paper derived from labels and caps, adhesives, coating agents, residual contents, and residual alkaline cleaning liquids. Etc. may be greatly deteriorated. Therefore, it is desirable that the solid phase polymerization step is usually performed after the separation step and the washing step. Those subjected to the separation step and the washing step have a low impurity content, so that they do not easily deteriorate even when heated by solid-phase polymerization, and a high-quality polyester recycled product is easily obtained.
The solid phase polymerization may be performed on the pelletized product in the granulation step described later, and when the pulverized product is a coarsely pulverized product such as a flake shape, You may do it for. When solid phase polymerization is performed in the form of a coarsely pulverized product such as a flake shape, the granulated process described later has not been performed, that is, the coarsely pulverized product and impurities are not melt-kneaded, so that the impurities deteriorated in color after the solid phase polymerization. It is also possible to remove the ground crushed material mixed with a color sorting device or the like. On the other hand, when solid phase polymerization is performed in the form of a coarsely pulverized product such as a flake shape, it is necessary to perform a granulation step with a thermal history after solid phase polymerization. There is a risk of reoccurrence of ionic impurities.

The solid-phase polymerization is preferably carried out by keeping the material temperature at a temperature of (melting point of polyester resin−55 ° C.) or higher and lower than that of polyester resin (melting point of polyester resin−5 ° C.) for a certain time. The material temperature as used herein refers to a temperature sensed by a thermocouple or a temperature sensor that can be in direct contact with the material during solid phase polymerization or indirectly through a structural material having high thermal conductivity. By setting the upper limit temperature of the material during solid-phase polymerization to (the melting point of the polyester resin -5 ° C), the polyester resin is prevented from melting, and the polyester resin is prevented from adhering to the surface of the apparatus to reduce work efficiency. To do. In addition, by setting the lower limit temperature of the material for solid-phase polymerization to (melting point of polyester resin −55 ° C.) or higher, a sufficient polymerization rate can be obtained, and removal of impurities represented by acetaldehyde can be efficiently removed. Desired physical properties are easily obtained.
The lower limit temperature of the solid phase polymerization is preferably (melting point of the polyester resin-35 ° C.) or more. Further, the upper limit temperature of the solid phase polymerization is preferably (melting point of polyester resin−10 ° C.) or less.

The solid phase polymerization is preferably carried out at a vacuum degree of 1.5 torr or less. More preferably, 0.6 torr or less is further desirable, and 0.2 torr or less is particularly desirable. Note that the degree of vacuum referred to here is at least the time from when the material temperature reaches a predetermined temperature until the material temperature is maintained for a certain period of time and then the internal temperature becomes less than (melting point of polyester resin −55 ° C.) by cooling. The pressure value in the apparatus which did not become higher than the above is shown.
In the solid phase polymerization step, it is desirable to reduce the oxygen concentration remaining in the solid phase polymerization apparatus. This is because the lower the oxygen concentration in the system, the better the physical properties of the resulting polyester resin. From the viewpoint of various physical properties of the obtained polyester resin, the oxygen concentration in the system is preferably 400 ppm or less, more preferably 170 ppm or less. By setting the oxygen concentration in the system to 400 ppm or less, appearance defects such as yellowing can be reduced.
Although it is difficult to detect the trace oxygen concentration in the solid-phase polymerization under vacuum, the oxygen concentration assumed to remain in the system is that the fraction of oxygen concentration in the air is 20.9 in volume ratio. % Can be approximated by the following calculation formula.
X = (Y / 760) × (20.9 / 100)
(X represents a converted value of trace oxygen concentration in the system in solid phase polymerization under vacuum, and Y represents the degree of vacuum (torr) in the system.)
Moreover, after substituting the inside of the system with an inert gas such as nitrogen in advance and then performing solid phase polymerization under reduced pressure, the oxygen concentration can be further lowered from the above formula.

The solid-phase equipment for performing solid-phase polymerization is a tumbler-type batch equipment equipped with a heating jacket, a dry silo type equipped with an inert gas flow facility, and a crystallization system equipped with a stirring blade and a discharge screw inside. Examples thereof include an apparatus and a reactor, and any apparatus can be used as long as it is known.
In solid phase polymerization, it is desirable to keep heat transfer uniform while constantly stirring or mixing the pulverized product or pellets.
The heating time for solid phase polymerization is determined in a timely manner in consideration of the apparatus and other conditions, but may be any time as long as the polyester obtains sufficient physical properties. Specifically, it is desirable to continue until the intrinsic viscosity (IV) of the polyester is 0.67 to 1.00, more desirably 0.71 to 0.90, and even more desirably 0.75 to 0.85. is there.
In particular, the inventors of the present invention have found that the rate of increase in the intrinsic viscosity of the polyester resin is increased by solid-phase polymerization of the polyester resin in the presence of a small amount of polyamide resin. As a result, the heating time of the solid phase polymerization can be suppressed to a shorter time, and the regenerated polyester obtained has a sufficient intrinsic viscosity and the amount of acetaldehyde is suppressed to a low level.

<Granulation process>
The method of the present invention preferably includes a step of granulating the pulverized product in order to obtain a product form that can be easily molded. The granulation step may be performed before or after solid-phase polymerization, and may be performed so long as the final form becomes a pellet.
As the granulation method, it is desirable to plasticize and granulate the pulverized product by melt blending. Examples of the granulator include a single screw extruder, a twin screw extruder, a multi-screw extruder, and the like, and any known one can be used. The granulation form is preferably a columnar shape, a pillow shape, a spherical shape, or an elliptical spherical shape.

<Crystalling process>
When performing solid phase polymerization, it is preferable to perform a crystallization step before solid phase polymerization in order to avoid fusion of pulverized products and adhesion to the inner surface of the apparatus. Moreover, when performing a granulation process, you may perform a crystallization process after a granulation process.
In the crystallization process, it is particularly important to crystallize the surface of the pulverized product in order to prevent fusion and adhesion. For this purpose, the pulverized product of the polyester resin recycled product resin structure can be held under constant heating. Desirably, specifically, it is desirable to heat at 100 to 230 ° C. Further, heat treatment may be performed after adding a certain amount of water in order to promote crystallization of the surface. Moreover, in order to prevent deterioration of resin, you may implement in inert gas stream, such as nitrogen gas.

The method of the present invention includes the steps shown in any of the following 1) to 4), and these steps are preferably performed in the order described, but the pulverization step, separation step and solid phase polymerization step are performed. If it contains, it will not specifically limit. Moreover, although a sieving process is not described, it may be performed immediately before each cleaning process or simultaneously with the cleaning process, or may be performed simultaneously with the grinding process. In addition, operations such as sorting by container appearance, removal of labels, caps and cap rings, and washing of contents and deposits may be performed in the state of the resin container prior to the following order.
1) Grinding step, separation step, washing step, drying step, granulation step, crystallization step, solid phase polymerization step 2) Grinding step, washing step, drying step, separation step, granulation step, crystallization step, solid phase Polymerization step 3) Grinding step, separation step, washing step, crystallization step, solid phase polymerization step, granulation step, crystallization step 4) Grinding step, washing step, drying step, separation step, crystallization step, solid phase polymerization Process, granulation process, crystallization process

[Recycled polyester]
The polyester recycled product is obtained by the above production method and has a polyester resin as a main component. The recycled polyester product may contain a certain amount of polyamide resin as a component because it undergoes the solid phase polymerization conditions of the present invention.
The content of the polyamide resin that can be contained in the recycled polyester product is such that the mass ratio of the polyester resin and the polyamide resin is preferably 99.99 to 3: 0.01 to 7, more preferably 99.8 to 95: 0.2. ~ 5. If the polyamide resin content in the recycled polyester product is within the above range, a high-quality polyester can be obtained without significantly deteriorating the appearance. In addition, content of a polyamide resin is measured by the method as described in an Example.

  The recycled polyester product may have the same shape as the pulverized product such as flakes, powders, etc., but is preferably formed into a pellet shape by the granulation process described above, and further, a plate shape for simple evaluation of appearance and the like. It may be molded into other shapes such as a bottle shape.

  In the present invention, the recycled polyester product desirably has a color tone (b *) of a 2 mm thick plate of 5 or less, more preferably 4 or less, and even more preferably 3 or less, with respect to a polyester recycled product that does not substantially contain polyamide. . When the color tone (b *) is 5 or less, the molded product obtained from the recycled polyester product has an excellent appearance.

  Further, it is desirable that the intrinsic viscosity of the recycled polyester product is 1.0 or less, more preferably 0, with respect to the intrinsic viscosity of the polyester recycled product which does not substantially contain polyamide subjected to solid phase polymerization under the same conditions. .9 or less, more preferably 0.7 or less. By being 1.0 or less, a molded product obtained from a recycled polyester product can obtain stable moldability and mechanical properties even when polyamide is contained. In addition, the intrinsic viscosity said here points out the value obtained by measuring by the method described in the Example.

  Further, the amount of acetaldehyde in the recycled polyester product is desirably 9.0 ppm or less, more preferably 8.0 ppm or less, and still more preferably 7.0 ppm or less. By being 9.0 ppm or less, the container for liquid beverages obtained from the recycled polyester product can maintain the quality of the contents well over a long period of time.

Polyester recycled products can be reused as molding resin raw materials for various molded products as they are through the regeneration process including the solid phase polymerization process of the present invention, but if appropriately diluted with a new polyester resin, Quality deterioration such as yellowing can be reduced. This diluted product can also be used as a molding resin material for various molded products.
The recycled polyester product is preferably used as a raw material for a molded product of the same type as the resin structure provided in the production method of the present invention. The resin structure provided in the production method is a resin container, and polyester. More preferably, the recycled product is used as a raw material for the resin container. In addition, the resin structure provided in the present production method is a used liquid beverage storage container (PET bottle), and the recycled polyester is also used as a raw material for the liquid beverage storage container (PET bottle). preferable.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited at all by the following examples.

Measurement methods such as various physical properties and evaluation methods of the present invention are as follows.
(1) Method for measuring the amount of polyamide (Method A)
Using a trace total nitrogen analyzer TN-2100H (manufactured by Mitsubishi Analytech), a calibration curve is prepared using a pyridine / toluene mixed solution prepared to a predetermined concentration as a standard concentration, and a polyester regenerated product or a multilayer laminate 4 to 8 mg Was used to measure the nitrogen content. The measurement was repeated 3 times, and the average value was calculated. The average value of the obtained nitrogen content was converted into the amount of contained polyamide by the following formula.
α = β × (MW [polyamide] / MW [nitrogen atom])
(Α: contained polyamide amount, β: average value of nitrogen content, MW [polyamide]; molecular weight per unit of polyamide, MW [nitrogen]; molecular weight of nitrogen atom × number of nitrogen contained per unit unit of polyamide)
(Method B)
In the case of over-range (the nitrogen content is 5000 ppm or more) by the method by the method A, the quantification was carried out by this method. After dissolving the polyamide in heavy formic acid, using a 400 MHz NMR apparatus (manufactured by JEOL), comparing the peak area intensity derived from the dicarboxylic acid component of the polyester and the diamine component of the polyamide by ¹ H-NMR measurement The amount was determined.
(2) Method for measuring color tone of pellets In accordance with JIS K7105, measurement was performed by a reflection method using a SE2000 type spectrocolorimeter (a halogen lamp was used as a light source) manufactured by Nippon Denshoku Industries Co., Ltd.
(3) Color tone measurement method of plate Based on JIS Z8722, it measured by the transmission method with the COM-400 type color difference and turbidity measuring device (a halogen lamp is used as a light source) by Nippon Denshoku Industries Co., Ltd.
(4) Measurement of Intrinsic Viscosity The polyester resin to be measured is dissolved in a phenol / 1,1,2,2-tetrachloroethane (= 6/4 weight ratio) mixed solvent to obtain 0.2, 0.4, 0.00. A 6 g / dL solution was prepared, and the intrinsic viscosity was measured at 25 ° C. using an automatic viscosity measuring apparatus (Malvern, Viscotek).
(5) Measurement of the amount of acetaldehyde The preform was cut into about 1 cm square and pulverized with a freeze pulverizer, and 1.0 g of the pulverized sample that passed through the mesh of 750 μm pores was weighed into a glass bottle, and 6.0 ml of pure water was added. In addition, it was sealed. The suspension was heated in an oven adjusted to a temperature of 120 ° C. for 60 minutes and then cooled in ice water. 2.0 ml of the supernatant of the suspension was collected, 0.4 ml of a 0.1% strength 2,4-dinitrophenylhydrazine / phosphoric acid solution was added thereto, and the mixture was allowed to stand at room temperature for 30 minutes. The supernatant after standing was filtered through a PTFE membrane filter having a pore diameter of 0.45 μm, and the filtrate was subjected to high performance liquid chromatography (apparatus; LC system manufactured by Hitachi, Ltd., UV detector; L-7400 (360 nm) manufactured by Hitachi, Ltd.), column Inertsil ODS-3 φ4.6 mm × 150 mm, manufactured by GL Science, eluent: water / acetonitrile mixed solution (gradient gradient), flow rate: 1.0 mL / min, column temperature: 40 ° C., injection amount: 10.0 μL) It was measured. At the same time, a standard solution of acetaldehyde was also measured, and the acetaldehyde content in the preform was calculated based on the obtained calibration curve.

<Production Example 1 (Production of polyamide resin (B))>
15000 g (102.6 mol) of adipic acid weighed precisely in a reaction vessel having an internal volume of 50 liters equipped with a stirrer, a partial condenser, a total condenser, a thermometer, a dropping funnel, a nitrogen introduction tube, and a strand die, hypophosphorous acid Sodium phosphate monohydrate (NaH ₂ PO ₂ .H ₂ O) 12.98 g (122.5 mmol, 150 ppm as the phosphorus atom concentration in the polyamide), sodium acetate 7.029 mg (85.75 mmol, sodium hypophosphite mono The molar ratio to the hydrate was 0.70), and after sufficient nitrogen substitution, the system was heated to 170 ° C. with stirring in a small amount of nitrogen stream. To this, 13896 g (102.0 mol) of metaxylylenediamine was added dropwise with stirring, and the inside of the system was continuously heated while removing the generated condensed water. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was 260 ° C. and the reaction was continued for 40 minutes. Thereafter, the inside of the system was pressurized with nitrogen, and the polymer was taken out from the strand die and pelletized to obtain about 24 kg of polyamide.
Next, the polyamide is charged into a tumble dryer with a jacket provided with a nitrogen gas introduction tube, a vacuum line, a vacuum pump, and a thermocouple for measuring the internal temperature, and the purity inside the tumble dryer is 99% by volume while rotating at a constant speed. After sufficiently replacing with the above nitrogen gas, the tumble dryer was heated under the same nitrogen gas stream, and the pellet temperature was raised to 150 ° C. over about 150 minutes. When the pellet temperature reached 150 ° C., the pressure in the system was reduced to 1 torr or less. The temperature was further raised, and the pellet temperature was raised to 200 ° C. over about 70 minutes, and then held at 200 ° C. for 30 to 45 minutes. Next, nitrogen gas having a purity of 99% by volume or more was introduced into the system, and the tumble dryer was rotated and cooled to obtain a polyamide resin (B).

<Polyester resin (A)>
In the examples, the following polyester resin (A) was used.
Product name. BK-2180, manufactured by Nippon Unipet Co., Ltd., intrinsic viscosity: 0.83 dl / g, polyethylene terephthalate-isophthalate copolymer resin (isophthalic acid content 1.5 mol%), melting point 247 ° C.

Example 1
<Pseudo regeneration process of resin structure>
In the present invention, the process from the resin structure as the raw material to the polyester recycled product through various regeneration processes is given to each of the polyester resin and the polyamide resin by giving an equivalent thermal history by the following method. evaluated. Specifically, the thermal history that the resin structure receives in the molding step and the granulation step is regarded as equivalent to the thermal history that the polyester resin and the polyamide resin receive in the extrusion pelletizing step. In addition, the heat history that the resin structure that is the raw material undergoes in the pulverization, washing, and separation processes is negligible compared to the heat history that is received in the molding process and granulation process, so it is not considered as the heat history. It was supposed to be.
That is, using a single screw extruder (caliber: 35 mmφ, full flight screw) with an extruder equipped with a strand die provided with a 100 mesh filter, the polyester resin was heated to a heater temperature of 290 ° C. and a discharge rate of 20 kg / hour. It was made into a strand shape, cut with a pelletizer while being cooled in a water tank, and pelletized.
Moreover, it replaced with the polyester resin and pelletized by the same method except having used the same operation also with the heater temperature of 280 degreeC also with the polyamide resin.
The obtained polyester pellets and polyamide pellets were dried in a hot air dryer at 150 ° C. for 4 hours, and then the polyester dry pellets and polyamide dry pellets were dry blended at the compounding ratio shown in Table 1 to obtain a heater. It pelletized using the single screw extruder similarly to the above except having set the temperature to 280 degreeC. The obtained resin composition pellets are considered to have received a thermal history equivalent to that obtained by pulverizing and granulating a multilayer structure.

<Crystalling process>
Pelletized resin composition pellets are put into a flask of a rotary 20L flask evaporator equipped with a vacuum pump with a leak valve, a cooling trap, an oil bath, a rotor, and a continuous temperature / internal pressure logger. Was repeated three times, and then the flask was rotated at 20 rpm under a nitrogen flow of 10 L / min. While maintaining that state, the flask is brought into contact with an oil bath preheated to about 160 ° C. to 180 ° C. until the internal temperature read from the thermocouple provided to directly contact the resin composition pellets reaches 160 ° C. The temperature was raised, and then the rotation was continued for 2 hours at 160 ° C.

<Solid-state polymerization process>
After the crystallization step, the oil bath is continuously heated to about 210 ° C. to 230 ° C., the pressure inside the flask is reduced to a predetermined pressure or lower, and then the temperature of the material is increased to 205 ° C. Rotation was continued for 7 hours after reaching. The degree of vacuum at this time was 0.4 torr. The flask was lifted from the oil bath, and when the internal temperature became 150 ° C. or lower, the pressure was restored with nitrogen gas, and then naturally cooled until the internal temperature became 60 ° C. or lower. The intrinsic viscosity of the recycled pellets was measured and the results are shown in Table 1.

<Plate>
The recycled pellets were injection molded using an injection molding apparatus (model SE130DU-HP, manufactured by Sumitomo Heavy Industries, Ltd.) to obtain a recycled plate having a thickness of 2 mm. The color tone (b *) in the thickness direction of this plate and the amount of acetaldehyde were measured. The results are shown in Table 1.
In addition, a polyester resin (A) that does not contain the polyamide resin (B) is subjected to solid state polymerization under the same conditions, and a 2 mm thick recycled plate is prepared for the polyester recycled product, and the same measurement is performed. The difference (* b) from the b value of the regenerated plate was measured.

<Bottled>
Using the recycled pellets, preform molding and blow molding were performed to obtain a single layer bottle. The bottle was filled with sterilized distilled water and stored at 40 ° C. for 4 weeks, and then the flavor of distilled water was evaluated as a sensory test by five people. The results are shown in Table 1.

[Examples 2 to 11, Comparative Examples 1 to 4]
The same procedure as in Example 1 was performed except that the polyamide content, the temperature in solid phase polymerization, the holding time, and the degree of vacuum were changed. The degree of vacuum was set by adjusting the opening of the leak valve.

As shown in the above examples, by performing solid-phase polymerization under a constant temperature condition and a vacuum condition, the color reproduction and intrinsic viscosity are generally good in the obtained polyester recycled product (recycled pellets and recycled plate). It was.
On the other hand, the polyester regenerated product obtained in Comparative Example 1 which was subjected to solid phase polymerization under conditions of poor vacuum was poor in color tone. In Comparative Example 2 in which the material temperature in the solid-phase polymerization is too low and in Comparative Example 4 using a raw material not containing a polyamide resin, the amount of acetaldehyde generated increased, and the resulting regenerated bottle reduced the flavor of the contents.
Further, in Comparative Example 3 in which the solid-state polymerization temperature was too high, fusion between pellets occurred, and a preform could not be formed. The intrinsic viscosity was measured by partially pulverizing the fused pellets.

  INDUSTRIAL APPLICATION This invention can be utilized for the use which reuses various resin structures, such as resin containers, such as a bottle, and a film, a sheet | seat, a pipe, especially the usage which reuses storage containers, such as a used PET bottle.

Claims (6)

A method for producing a polyester recycled product, which obtains a polyester recycled product from a resin structure comprising a polyester resin (A) and a polyamide resin (B) containing a structural unit derived from xylylenediamine,
The method for producing a recycled polyester product, wherein the production method includes at least a pulverization step, a separation step, and a solid phase polymerization step, and the solid phase polymerization step satisfies formulas (1) and (2).
(Mp−55) ≦ M <(mp−5) (1)
V ≦ 1.5 (2)
(M represents the material temperature in solid phase polymerization, mp represents the melting point (° C.) of the polyester resin subjected to solid phase polymerization, and V represents the degree of vacuum (torr) when the material temperature is M in the solid phase polymerization reaction)   The method for producing a recycled polyester product according to claim 1, wherein the polyester resin (A) includes a terephthalic acid-derived structural unit as a dicarboxylic acid unit and a diol unit as a structural unit derived from ethylene glycol.   The polyester according to claim 1, wherein the polyamide resin (B) contains a structural unit derived from xylylenediamine as a diamine unit, and a structural unit derived from α, ω-dicarboxylic acid having 4 to 20 carbon atoms as a dicarboxylic acid unit. A method for manufacturing recycled products.   The manufacturing method of the polyester reproduction | regeneration goods in any one of Claims 1-3 whose mass ratio of the polyester resin and polyamide resin contained in the said polyester reproduction | regeneration goods is 99.99-93: 0.01-7. The manufacturing method of the polyester reproduction | regeneration goods in any one of Claims 1-4 with which the said polyester reproduction | regeneration goods satisfy | fill following formula (3).
AA ≦ 9.0 (3)
(AA indicates the acetaldehyde concentration (ppm) contained in a piece in a 2 mm thick plate made of a recycled polyester product)   The method for producing a recycled polyester product according to any one of claims 1 to 5, wherein the resin structure is a resin container.