JP2006192890A - Manufacturing method of polyester preform and polyester stretched body, and polyester shaped body obtained by manufacturing method of them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high speed manufacturing method of a preform for a hollow shaped body hardly generating aldehydes during shaping, and showing excellent transparency, little variation of transparency and excellent dimensional stability, to provide a manufacturing method of a polyester stretched body using the preform and to provide a polyester shaped body obtained by using the preform. <P>SOLUTION: The manufacturing method of the polyester preform obtained by shaping a polyester composition containing at least two polyesters as major components, these having substantially same composition but having different limiting viscosities, is characterized in that the difference of the limiting viscosities between the polyesters is 0.05 to 0.30 dl/g, the average weight (W) of each polyester chip is 5 to 50 mg, the ratio of the average weight (W) of the chips is 1.00 to 1.30, the difference of the crystallization degree between the polyesters is 10% or less, and dispersion ratio Mz/Mn of molecular weight distribution of the polyester composition is not less than 3.90. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a method for producing a polyester preform suitably used as a preform for a stretched polyester molded body such as a bottle for beverages, a stretched hollow molded body, a stretched sheet, and a stretched film. Using a preform, production of aldehydes such as acetaldehyde at the time of molding is highly suppressed, and a method for producing a stretched polyester molded article with excellent transparency and very little variation in transparency is obtained. The present invention relates to a polyester molded body.

  Polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) are excellent in both mechanical properties and chemical properties, and thus have high industrial value, such as fibers, films, sheets, and bottles. Widely used as such.

  As a material for containers such as seasonings, oils, beverages, cosmetics, and detergents, various resins are employed depending on the type of filling contents and the purpose of use.

  Of these, polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, and is particularly suitable as a material for molded articles such as beverage filling containers such as juices, soft drinks and carbonated drinks. is there.

  For example, such polyester is supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded body, and the preform is inserted into a mold having a predetermined shape and stretched blow molded to cool it. It is made into a hollow molded container for beverages, or it is molded into a heat-resistant or pressure-resistant hollow molded container by heat-treating the preform plug part (crystallization of the plug part) and then stretching blow molding and heat-treating the body part (heat set). It is common.

  However, PET contains acetaldehyde (hereinafter sometimes abbreviated as AA) as a by-product during melt polycondensation. Moreover, PET produced acetaldehyde by thermal decomposition when thermoforming a molded body such as a hollow molded body, and the acetaldehyde content in the material of the obtained molded body was increased, and the hollow molded body was filled. Affects the flavor and odor of beverages.

  In recent years, polyester containers such as polyethylene terephthalate have come to be used as containers for low flavor beverages such as mineral water and oolong tea. In the case of such beverages, these beverages are generally heat-filled or sterilized by heating after filling, but the reduction of the acetaldehyde content in the beverage container is becoming increasingly important. In addition, for beverage metal cans, for the purposes of process simplification, hygiene, pollution prevention, etc., cans are made using a metal plate whose inner surface is coated with a polyester film whose main repeating unit is ethylene terephthalate. The method to do has come to be adopted. In this case as well, it is sterilized by heating at a high temperature after filling the contents. At this time, it is found that the use of a film having a sufficiently low acetaldehyde content is an essential requirement for improving the flavor and odor of the contents. I came.

  For these reasons, various measures have conventionally been taken to reduce the acetaldehyde content in the polyester. As these measures, for example, a method of reducing the AA content by solid-phase polymerization of melt-polycondensed polyester (see, for example, Patent Document 1), AA at the time of molding using a copolyester having a lower melting point A method for reducing the production (for example, see Patent Document 2), a method for adjusting the moisture content of the polyester prepolymer so that the moisture content is 2000 ppm or more, and then performing crystallization and solid-phase polymerization (for example, see Patent Document 3), polyester A method in which particles are treated with hot water at 50 to 200 ° C. and then heat-treated under reduced pressure or in an inert gas flow (for example, see Patent Document 4). Extraction and washing with water or an organic solvent before and after solid-phase polymerization A processing method (for example, see Patent Document 5), a method for reducing the molding temperature as much as possible during thermoforming, and a shear stress during thermoforming as much as possible. Such as how to reduce has been proposed. However, even in a molded body using polyester obtained by these methods, it cannot be said that oligomers and acetaldehyde can be reduced to a problem-free level, and the problem remains unsolved.

  Also, a method for producing a heat-resistant polyester container in which a preform formed from two kinds of PET melt-mixed compositions having different intrinsic viscosities of 0.03 or more is treated with a heat-fixing mold under specific temperature conditions (for example, Patent Document 6). And a heat-resistant polyester container obtained (see, for example, Patent Document 7), having an intrinsic viscosity of 0.60 to 0.70 dl / g, a specific crystallization temperature at the time of temperature increase, and a specific crystallization temperature at the time of temperature decrease Production of a heat resistant polyester container for stretching and blowing a preform from a mixture of polyester and a polyester having an intrinsic viscosity of 0.77 to 0.90 dl / g, a specific crystallization temperature at elevated temperature and a specified crystallization temperature at lowered temperature Methods (see, for example, Patent Document 8) have been proposed. To obtain a molded article having stable transparency and a reduced acetaldehyde content even by these methods. But there is a problem. Further, a blend of solid-phase polymerized PET and copolymerized polyethylene terephthalate (for example, see Patent Document 9) has been proposed, and by using this, the AA content of the hollow molded body can be reduced. Since the copolymer component is present, there is a problem in the heat resistance and pressure resistance of the obtained molded body, which is not satisfactory and a solution is awaited.

  In addition, a method using a polyester composition in which 0.05 parts by weight or more and less than 1 part by weight of a metaxylylene group-containing polyamide resin is added to 100 parts by weight of a polyester resin (see, for example, Patent Document 10) or thermoplastic polyester Polyester containers made of a polyester composition containing a specific polyamide whose terminal amino group concentration is regulated within a certain range have been proposed (for example, see Patent Document 11). Polyester molding obtained by these techniques Even if it is a body, there are problems of insufficient acetaldehyde reduction, crystallization speed fluctuation and cost increase, and a solution is awaited.

  Furthermore, in recent years, thinning of bottles has been attempted, and as a result, attempts have been made to increase the molecular weight in order to increase the strength of the bottle, but by increasing the molecular weight, the melt viscosity during molding increases and the amount of acetaldehyde generated is increased. There was an increasing problem.

JP-A-53-73288 Japanese Patent Laid-Open No. 57-16024 JP-A-2-298512 JP-A-8-120062 Japanese Patent Laid-Open No. 55-13715 Japanese Examined Patent Publication No. 62-43851 Japanese Examined Patent Publication No. 62-58973 Japanese Patent Laid-Open No. 10-287799 JP 58-45254 A Japanese Examined Patent Publication No. 6-6661 Japanese Examined Patent Publication No. 4-71425

  The present invention solves the above-mentioned problems of the prior art, the generation of aldehydes such as acetaldehyde at the time of molding is highly suppressed, the transparency is extremely excellent, and the variation in transparency is very small. An object of the present invention is to provide a production method for efficiently producing a preform for a hollow molded body having excellent properties by high speed molding, a method for producing a stretched polyester molded body comprising the same, and a polyester molded body obtained therefrom.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to achieve the above object. That is, the present invention relates to a polyester obtained by molding a polyester composition containing as a main component at least two types of polyesters having substantially the same composition but different intrinsic viscosities (hereinafter sometimes referred to as IV). A method for producing a preform, wherein the difference in intrinsic viscosity of the polyester is 0.05 to 0.30 deciliter / gram, the ratio of the average weight (W) of each polyester chip and the average weight (W) of each chip. Are 5 to 50 mg and 1.00 to 1.30, the difference in crystallinity between the polyester chips is 10% or less, and the dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is 3.90. It is the manufacturing method of the polyester preform by the above.
Here, “substantially the same” means that the acid component and glycol component in each composition are the same in 95 mol% or more, more preferably 97 mol% or more, particularly 98 mol% or more. It is preferable that

  When diethylene glycol, which is a by-product of ethylene glycol, is present in the copolymer component, the amount of diethylene glycol is within 7 mol%, preferably within 5 mol%, more preferably within 3 mol%, particularly preferably 2 mol. The difference may be within%.

  The difference in intrinsic viscosity of the polyester is preferably 0.06 to 0.27 deciliter / gram, more preferably 0.07 to 0.23 deciliter / gram, particularly preferably 0.10 to 0.20 deciliter / gram. . When the intrinsic viscosity difference is less than 0.05 deciliter / gram, the content of aldehydes such as acetaldehyde in the obtained molded product cannot be reduced, and the flavor retention cannot be improved. Further, when the above-mentioned intrinsic viscosity difference exceeds 0.30 deciliter / gram, a thickness unevenness, a whitened flow pattern, or the like is generated on the obtained molded product, which causes a problem. Here, when the polyester composition according to the present invention is composed of two or more kinds of polyesters, the difference in intrinsic viscosity is the difference in intrinsic viscosity between the largest polyester and the smallest polyester with respect to the intrinsic viscosity.

  The ratio of the average weight (W) of each polyester chip and the average weight (W) of the chip is preferably 7 to 45 mg and 1.00 to 1.28, more preferably 10 to 40 mg and 1.00, respectively. -1.25, most preferably 15-30 mg and 1.00-1.20. When the average weight of the chip exceeds 50 mg, it takes a long time to melt in the molding machine, which causes a problem that the content of aldehydes such as acetaldehyde is extremely increased. The economical problem that it becomes very slow, and the economical problem that the drying time becomes long when the polyester composition having a moisture content of about 2000 ppm or more is dried arise. In addition, in the case of a chip having an average weight of less than 5 mg, fine powder is very easily generated when the chip is handled, and sometimes exceeds 5000 ppm, so that the transparency of the preform is deteriorated as described above. When it is generated or stored in the atmosphere, the moisture absorption rate is fast and becomes 2000 ppm or more in a short time, and it takes a long time to re-dry. In addition, if the ratio of the average weight (W) exceeds 1.30, the production of aldehydes at the time of molding increases, and it is not preferable because the equipment cost becomes high such as using a special nozzle to manufacture the chip. , It becomes difficult to melt at the time of molding, and low temperature molding becomes difficult, which is a problem. In particular, when used for a heat-resistant hollow stretch molded article, if the ratio is out of the range of 1.00 to 1.15, the effect of reducing aldehydes such as acetaldehyde and improving the transparency is deteriorated.

The difference in crystallinity between the polyester chips is 9% or less, more preferably 8% or less. When the difference in crystallinity exceeds 10%, the difference in meltability between polyesters is large and the effect of improving fluidity is deteriorated. As a result, the transparency of the preform is improved and aldehydes such as acetaldehyde are contained. This is not preferable because the effect of reducing the amount is lost, and the blended amount of the polyester tends to occur, causing the transparency of the preform and the content of aldehydes such as acetaldehyde. Here, when the polyester composition according to the present invention is composed of two or more kinds of polyesters, the difference in crystallinity is the difference in crystallinity between the largest polyester and the smallest polyester with respect to the degree of crystallinity. It is. Here, the crystallinity of the chip is calculated from the density of the chip obtained by the following method.
The crystallinity of each polyester chip is 40% to 70%, preferably 45 to 65%, and more preferably 50 to 63%. The crystallinity of the chip is determined by the method described in the following measurement method section.

  Further, the dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is preferably 3.92 or more, more preferably 3.95 or more. If a polyester composition having a molecular weight distribution ratio Mz / Mn of less than 3.90 is used, heat generation during melt molding becomes severe, and the content of aldehydes such as acetaldehyde in the preform increases, and the degree of orientation decreases. For this reason, only a stretched polyester molded body with reduced strength can be obtained. These are presumed to be because the effect of improving the fluidity of molecules due to the low molecular weight component in the molten state in the molding machine is not exhibited. Furthermore, since transesterification occurs between polyesters having different intrinsic viscosities in the melted state, rearrangement of the molecular weight distribution occurs, so in the case of a polyester composition having a molecular weight distribution dispersion ratio Mz / Mn of less than 3.90, it is The dispersion ratio Mz / Mn of the molecular weight distribution of the obtained polyester preform tends to be less than 3.80, and the object cannot be achieved. Further, the upper limit value of the dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is 6.0, and if this value is exceeded, a very high molecular weight polyester is difficult to melt at the time of molding. This is a problem because only a molded body can be obtained.

Examples of a method for obtaining a polyester composition having a molecular weight distribution dispersion ratio Mz / Mn of 3.90 or more include, for example, at least two types of solid-phase polymerization having substantially the same composition but different in intrinsic viscosity by at least 0.05 deciliter / gram or more. A method of blending polyester, a method of copolymerizing an appropriate amount of a polyfunctional compound, and polycondensation conditions (for example, in the case of a continuous polycondensation apparatus, the residence time is increased, or the number of polycondensation tanks is adjusted). A method of appropriately adjusting the polycondensation or a method of appropriately combining these methods may be mentioned.
Here, the molecular weight distribution and the dispersion ratio are measured by the methods described in the following measurement method section.

  According to the method for producing a polyester preform of the present invention, the content of aldehydes such as acetaldehyde is low, the color tone, flavor retention and transparency are excellent, and the transparent spots (for example, the whitened flow pattern generated in the molded product) And a polyester pre-molded product having an appropriate crystallization speed and little fluctuation in the crystallization speed.

  The polyester composition used in the present invention has improved mechanical properties such as elastic modulus and tensile strength, as well as improved heat fixability because the fluidity at the time of melting is improved and the orientation at the time of heat stretching is also improved. In addition, it can be used as a stretched hollow container having excellent characteristics.

The present invention also relates to a method for producing a polyester preform comprising molding a polyester composition containing at least two types of polyesters mainly composed of ethylene terephthalate as a main repeating unit, the polyester composition comprising: , Polyester A having an intrinsic viscosity of 0.60 to 0.80 deciliter / gram, 55 to 95 parts by weight, polyester B having an intrinsic viscosity of 0.05 to 0.30 deciliter / gram higher than the polyester A, 45 to 5 weight The dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is 3.90 or more, the crystallinity of each polyester chip is 50 to 66%, the crystallinity of the polyester A chip and the polyester B The difference in crystallinity between the chips is 10% or less, and the average weight (W) of each polyester chip is 5 to 50 m. Is the method for producing a polyester preform, wherein the ratio of the average weight of the chips of average weight (W _A) and the polyester B in the polyester A chip (W _B) is 1.00 to 1.30 .

The intrinsic viscosity of polyester A is preferably 0.62 to 0.78 deciliter / gram, more preferably 0.63 to 0.75 deciliter / gram, particularly preferably 0.65 to 0.73 deciliter / gram, The difference in intrinsic viscosity of polyester A is preferably 0.06 to 0.27 deciliter / gram, more preferably 0.07 to 0.23 deciliter / gram, and particularly preferably 0.10 to 0.20 deciliter / gram. is there.
When the intrinsic viscosity of polyester A is less than 0.60 deciliter / gram, the transparency of the obtained polyester preform is deteriorated. On the other hand, when it exceeds 0.80 deciliter / gram, the effect of reducing aldehydes such as acetaldehyde is almost lost and the object cannot be achieved.

  The polyester having the above-mentioned characteristics and having different intrinsic viscosities used in the present invention is such that the difference in intrinsic viscosity falls within the scope of the present invention in the melt polycondensation reaction step or the subsequent solid phase polymerization reaction step. Polyester produced, or polyester obtained by subjecting these to contact with water under a condition that the intrinsic viscosity does not decrease.

  As other production methods for obtaining polyesters having different intrinsic viscosities, there are a method of hydrolyzing polyester by heat treatment with water at a high temperature, a method of melt treatment with an extruder, and the like. However, since the method by hydrolysis is carried out in a solid state, it is very difficult to control the degree of IV reduction, it is difficult to obtain polyester particles having a narrow IV fluctuation range, and particles after hydrolysis treatment Is prone to generate fine powder due to impact during transportation, etc., so there is a problem that the transparency of the preform and the crystallization speed change greatly when these are used. Gender and its variation become a problem. In addition, the method using the melt treatment has problems such as an influence on flavor retention and coloring due to an increase in aldehydes such as acetaldehyde during the treatment. Therefore, the polyester according to the present invention does not include polyester hydrolyzed by a method such as heat treatment under pressure with water or the like, or polyester melt-treated to reduce IV.

  The crystallinity of the polyester A and polyester B chips is preferably 52 to 65%, more preferably 53 to 64%. When the degree of crystallinity is less than 50%, the amount of aldehydes such as acetaldehyde during the solid phase polymerization is small, and it is impossible to reduce the content to a predetermined aldehyde content such as acetaldehyde. Further, if it exceeds 66%, the transparency of the preform is deteriorated at molding at a lower temperature. Therefore, when the transparency of the preform is regarded as important, the molten resin temperature must exceed 295 ° C. As a result, aldehydes such as acetaldehyde increase and affect flavor retention.

  By the method for producing a polyester preform of the present invention, the content of aldehydes such as acetaldehyde is less, the color tone, flavor retention and transparency are excellent, and there is no occurrence of transparency spots, and an appropriate crystallization rate is achieved. Thus, it is possible to obtain a stretched molded article having excellent heat fixability with less fluctuation in crystallization speed. In particular, in the case of a thick stretched molded product such as a bottle, these effects become significant.

In this case, the crystallization temperature when the temperature of the polyester A is lowered and the crystallization temperature when the temperature of the polyester B is lowered are 160 to 200 ° C., and the crystallization temperature when the temperature of the polyester A is lowered and the crystals when the temperature of the polyester B is lowered. It is preferable that the difference in crystallization temperature is less than 20 ° C.
Moreover, in this case, it is preferable that the crystallization temperature when the polyester A is heated and the crystallization temperature when the polyester B is heated are 140 to 180 ° C.

  In this case, it is preferable that the fine content of the polyester composition is 5000 ppm or less. The fine content of the polyester composition is preferably 3000 ppm or less, more preferably 1000 ppm or less. When the fine content exceeds 5000 ppm, the blend amount variation of the polyester A and the polyester B in the polyester composition is likely to occur. As a result, the intrinsic viscosity variation of the preform becomes large, and the crystallization speed and stretchability vary. In addition, fluctuations in the AA content are undesirable. The lower limit is 1 ppm, and the effect is not clear even if it is reduced below this value. Here, the fine means an aggregate of polyester strips and fine powders that have passed through a sieve having a mesh size of 1.7 mm according to JIS-Z8801, and these contents are measured by the following measuring method. To do.

  In this case, the fine melting point is preferably 265 ° C. or lower. The melting point of the fine contained in the polyester composition is preferably 263 ° C. or lower, more preferably 260 ° C. or lower. When the fine melting point exceeds 265 ° C., the crystals are not completely melted under the usual melt molding conditions and remain as crystal nuclei. When the preformed body plug portion is heated, the crystallization speed is increased, so that the crystallization of the plug portion becomes excessive. As a result, since the amount of shrinkage of the plug portion does not fall within the specified value range, the capping portion of the plug portion becomes defective and the contents may leak. In addition, the preform is whitened during preheating, so that normal stretching is impossible, resulting in uneven thickness or poor transparency.

  Here, the melting point of the fine is measured by the following method using a differential scanning calorimeter (DSC). The melting peak temperature representing the melting point of the fine is one or more melting points. In the present invention, when there is one melting peak, the peak temperature is indicated, and when there are a plurality of melting peaks, the highest one of the plurality of melting peaks. The melting peak temperature on the high temperature side is referred to as “the peak temperature on the highest temperature side of the melting peak temperature of fine”, and in the examples, it is referred to as “the melting point of fine”.

  By the method for producing a polyester preform of the present invention, the content of aldehydes such as acetaldehyde is less, the color tone, flavor retention and transparency are excellent, and there is no occurrence of transparency spots, and appropriate crystallization It is possible to obtain a stretched molded article having high heat resistance that has high speed and excellent heat fixability with less crystallization speed fluctuation. In particular, in the case of stretched molded articles such as bottles suitable for beverages filled at high temperatures, these effects become significant.

  In this case, the polyester composition may include a recovered product of the polyester molded body.

  The acetaldehyde content of the polyester preform obtained by the production method according to any one of claims 2 to 6 is 15 ppm or less, preferably 12 ppm or less, most preferably 10 ppm or less, and the cyclic trimer content is 0.70% by weight or less, preferably 0.50% by weight or less, more preferably 0.40% by weight or less, and haze is 10.0% or less, preferably 7.0% or less, more preferably 5.0%. In the following, the dispersion ratio Mz / Mn of the molecular weight distribution is 3.80 or more, preferably 3.83 or more, more preferably 3.85 or more.

  In the present invention, the polyester preform obtained by any one of the above production methods is stretched in at least one direction, and further, the preform is biaxially stretched or biaxially stretched. By stretch-blow molding and heat-fixing the stretched molded product after stretch molding as necessary, it has low content of aldehydes such as acetaldehyde, excellent flavor retention, mechanical properties such as transparency, elastic modulus and tensile strength A biaxially stretched film or hollow molded body having excellent characteristics, and a stretch molded body having excellent heat fixability can be obtained.

  The acetaldehyde content of the polyester stretch-molded product obtained by the production method of the present invention according to claim 8 or 9 is 15 ppm or less, preferably 12 ppm or less, most preferably 10 ppm or less, and the cyclic trimer content. 0.70% or less, preferably 0.50% by weight or less, more preferably 0.40% by weight or less, haze of 5.0% or less, preferably 3.0% or less, more preferably 1.5% or less, The dispersion ratio Mz / Mn of the molecular weight distribution is 3.80 or more, preferably 3.83 or more, more preferably 3.85 or more.

  According to the present invention, there is provided a method for producing a preform in which the production of aldehydes such as acetaldehyde during molding is highly suppressed, the transparency is extremely excellent, and the variation in transparency is very small. The preformed body is biaxially stretched or biaxially stretched blow-molded, or subsequently heat-set, so that the content of aldehydes such as acetaldehyde is extremely low, and the flavor retention is excellent, and the transparency and elastic modulus It is possible to provide a biaxially stretched film or hollow molded body having excellent mechanical properties such as tensile strength, a method for producing a stretched molded body having excellent heat fixability, and a polyester molded body obtained therefrom.

Hereinafter, the manufacturing method of the polyester preform of the present invention, the manufacturing method of the stretched polyester molding, and the embodiment of the obtained polyester molding will be specifically described.
The polyester according to the present invention is a thermoplastic polyester mainly obtained from an aromatic dicarboxylic acid component and a glycol component, preferably a polyester containing 70 mol% or more of an aromatic dicarboxylic acid unit of the acid component, more preferably A polyester containing 85 mol% or more of an aromatic dicarboxylic acid unit, particularly preferably a polyester containing 95 mol% or more of an aromatic dicarboxylic acid unit of an acid component.

The aromatic dicarboxylic acid component constituting the polyester according to the present invention includes aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and the like. And functional derivatives.
Examples of the glycol component constituting the polyester according to the present invention include aliphatic glycols such as ethylene glycol, 1,3-trimethylene glycol and tetramethylene glycol, and alicyclic glycols such as cyclohexanedimethanol.

  Examples of the dicarboxylic acid used as a copolymerization component when the polyester is a copolymer include isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, Aromatic dicarboxylic acids such as 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenyl ketone dicarboxylic acid and functional derivatives thereof, oxyacids such as p-oxybenzoic acid and oxycaproic acid and functional derivatives thereof, adipine Aliphatic dicarboxylic acids such as acid, sebacic acid, succinic acid, glutaric acid and dimer acid and their functional derivatives, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid and cyclohexanedicarboxylic acid and their functional derivatives Etc.

  The glycol as a copolymerization component used when the polyester is a copolymer is diethylene glycol, 1,3-trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene. Glycols, 2-ethyl-2-butyl-1,3-propanediol, aliphatic glycols such as neopentyl glycol, dimer glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol 1,4-cyclohexane dimethylol, 2,5-norbornane dimethylol and other alicyclic glycols, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4′-β-hydroxyethoxy) Aromatic glycols such as phenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and alkylene oxide adducts of bisphenol A, polyalkylene glycols such as polyethylene glycol and polybutylene glycol Etc.

  Furthermore, examples of the polyfunctional compound as a copolymer component used when the polyester is a copolymer include trimellitic acid, pyromellitic acid, and the like as an acid component, and glycerin and pentane as glycol components. Mention may be made of erythritol. The amount of copolymerization component used should be such that the polyester remains substantially linear. Monofunctional compounds such as benzoic acid and naphthoic acid may be copolymerized.

A preferred example of the polyester according to the present invention is a polyester whose main structural unit is composed of ethylene terephthalate, more preferably 70 mol% or more of ethylene terephthalate units, and isophthalic acid, 1,4-cyclohexanedi, as a copolymerization component. A copolyester containing methanol or the like, particularly preferably a polyester containing 95 mol% or more of ethylene terephthalate units.
Examples of these polyesters include polyethylene terephthalate (hereinafter abbreviated as PET), poly (ethylene terephthalate-ethylene isophthalate) copolymer, poly (ethylene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, poly ( Examples thereof include an ethylene terephthalate-dioxyethylene terephthalate) copolymer, a poly (ethylene terephthalate-1,3-propylene terephthalate) copolymer, and a poly (ethylene terephthalate-ethylene cyclohexylene dicarboxylate) copolymer.

In addition, another preferable example of the polyester according to the present invention is a polyester in which a main structural unit is composed of 1,3-propylene terephthalate, and more preferably a polyester including 70 mol% or more of 1,3-propylene terephthalate units. Particularly preferred are polyesters containing 95 mol% or more of 1,3-propylene terephthalate units.
Examples of these polyesters include polypropylene terephthalate (PTT), poly (1,3-propylene terephthalate-1,3-propylene isophthalate) copolymer, poly (1,3-propylene terephthalate-1,4-cyclohexanedimethylene). Terephthalate) copolymer and the like.

Further, other preferable examples of the polyester according to the present invention are polyesters in which the main structural unit is composed of butylene terephthalate, more preferably a copolyester containing 70 mol% or more of butylene terephthalate units, and particularly preferable. Is a polyester containing 95 mol% or more of butylene terephthalate units.
Examples of these polyesters include polybutylene terephthalate (PBT), poly (butylene terephthalate-butylene isophthalate) copolymer, poly (butylene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, poly (butylene terephthalate- 1,3-propylene terephthalate) copolymer, poly (butylene terephthalate-butylene cyclohexylene dicarboxylate) copolymer, and the like.

In addition, another preferred example of the polyester according to the present invention is a thermoplastic polyester whose main structural unit is composed of ethylene-2,6-naphthalate, and more preferably 70 mol% of ethylene-2,6-naphthalate units. The thermoplastic polyester containing the above is preferable, and a thermoplastic polyester containing 90 mol% or more of ethylene-2,6-naphthalate units is particularly preferable.
Examples of these thermoplastic polyesters include polyethylene-2,6-naphthalate (PEN), poly (ethylene-2,6-naphthalate-ethylene terephthalate) copolymer, poly (ethylene-2,6-naphthalate-ethylene isophthalate). ) Copolymer, poly (ethylene-2,6-naphthalate-dioxyethylene-2,6-naphthalate) copolymer, and the like.

Furthermore, another preferred example of the polyester according to the present invention is a polyester in which the main structural unit is composed of 1,4-cyclohexanedimethylene terephthalate, and more preferably 70 moles of 1,4-cyclohexanedimethylene terephthalate unit. %, Particularly preferably a polyester containing 90 mol% or more of 1,4-cyclohexanedimethylene terephthalate units.
Examples of these thermoplastic polyesters include poly-1,4-cyclohexanedimethylene terephthalate (PCT), poly (1,4-cyclohexanedimethylene terephthalate-ethylene terephthalate) copolymer, and the like.

  The polyester according to the present invention is a linear polyester containing 85 mol% or more of ethylene terephthalate units, preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 97 mol% or more. It is.

  The polyester used in the present invention can basically be produced by a conventionally known melt polycondensation method or melt polycondensation method-solid phase polymerization method. The melt polycondensation reaction may be performed in one stage or may be performed in multiple stages. These may be comprised from a batch-type reaction apparatus, and may be comprised from the continuous-type reaction apparatus. The melt polycondensation step and the solid phase polymerization step may be operated continuously or may be operated separately. Hereinafter, an example of a preferable continuous production method of the polyester used in the present invention will be described using polyethylene terephthalate (PET) as an example, but the present invention is not limited thereto. That is, a direct esterification method in which terephthalic acid, ethylene glycol, and if necessary, other copolymerization components are directly reacted and esterified while distilling off water, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst, Or transesterification by reacting dimethyl terephthalate with ethylene glycol and other copolymerization components if necessary, and transesterifying while distilling off methyl alcohol, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst Manufactured by. Then, when the intrinsic viscosity is increased or the low acetaldehyde content or the low cyclic trimer content is used, such as a heat-resistant container for low flavor beverages or a film for inner surfaces of metal cans for beverages. The resulting melt polycondensed polyester is subsequently subjected to solid state polymerization.

  First, when a low polymer is produced by an esterification reaction, 1.02 to 2.0 mol, preferably 1.03 to 1.4 mol of ethylene glycol is added to 1 mol of terephthalic acid or an ester derivative thereof. The contained slurry is prepared and continuously supplied to the esterification reaction step.

In the esterification reaction, water or alcohol produced by the reaction is removed out of the system by a rectification column under conditions where ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. While implementing. The temperature of the first stage esterification reaction is 240 to 270 ° C., preferably 245 to 265 ° C., and the pressure is 0.2 to 3 kg / cm ² G, preferably 0.5 to ² kg / cm ² G. The temperature of the esterification reaction in the final stage is usually 250 to 280 ° C, preferably 255 to 275 ° C, and the pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 1.3 kg / cm ² G. . When carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are intermediate conditions between the reaction conditions in the first stage and the reaction conditions in the final stage. The increase in the reaction rate of these esterification reactions is preferably distributed smoothly at each stage. Ultimately, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. By these esterification reactions, low-order condensates having a molecular weight of about 500 to 5,000 are obtained.
When terephthalic acid is used as a raw material, the esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst.

  Also, tertiary amines such as triethylamine, tri-n-butylamine, benzyldimethylamine, quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, trimethylbenzylammonium hydroxide, and lithium carbonate When a small amount of a basic compound such as sodium carbonate, potassium carbonate or sodium acetate is added, the proportion of dioxyethylene terephthalate component units in the main chain of polyethylene terephthalate is relatively low (3% relative to all diol components). Mol% or less).

  Next, in the case of producing a low polymer by transesterification, 1.1 to 2.0 mol, preferably 1.2 to 1.5 mol of ethylene glycol was contained with respect to 1 mol of dimethyl terephthalate. The solution is prepared and continuously fed to the transesterification step.

  The transesterification reaction is carried out while removing methanol generated by the reaction outside the system using a rectification column under the condition that ethylene glycol is distilled back using an apparatus in which 1 to 2 transesterification reactors are connected in series. To do. The temperature of the first stage transesterification is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the transesterification reaction in the final stage is usually 230 to 270 ° C., preferably 240 to 265 ° C., and as the transesterification catalyst, fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca, Ba, carbonates Further, Pb, Zn, Ge oxide or the like is used. A low-order condensate having a molecular weight of about 200 to 500 is obtained by these transesterification reactions.

  Dimethyl terephthalate, terephthalic acid or ethylene glycol, which is the starting material, includes virgin dimethyl terephthalate derived from para-xylene, ethylene glycol derived from terephthalic acid or ethylene, as well as methanol decomposition from used PET bottles. A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered by a chemical recycling method such as decomposition of ethylene glycol or ethylene glycol can also be used as at least part of the starting material. Needless to say, the quality of the recovered raw material must be refined to a purity and quality suitable for the intended use.

  Subsequently, the obtained low-order condensate is supplied to a multistage melt condensation polymerization process. The polycondensation reaction conditions are as follows: the first stage polycondensation reaction temperature is 250 to 290 ° C., preferably 260 to 280 ° C., and the pressure is 500 to 20 Torr, preferably 200 to 30 Torr. The temperature is 265 to 300 ° C., preferably 275 to 295 ° C., and the pressure is 10 to 0.1 Torr, preferably 5 to 0.5 Torr. When carried out in three or more stages, the reaction conditions for the intermediate stage polycondensation reaction are conditions between the reaction conditions for the first stage and the reaction conditions for the last stage. The degree of increase in intrinsic viscosity achieved in each of these polycondensation reaction steps is preferably distributed smoothly. A single-stage polycondensation apparatus may be used for the polycondensation reaction.

  The polycondensation reaction is performed using a polycondensation catalyst. As the polycondensation catalyst, at least one compound selected from Ge, Ti, Sb or Al compounds is preferably used. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries and the like.

  Examples of the Ge compound include amorphous germanium dioxide, crystalline germanium dioxide powder or ethylene glycol slurry, a solution obtained by heating and dissolving crystalline germanium dioxide in water, or a solution obtained by adding ethylene glycol to this and heat treatment. In particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution in which germanium dioxide is dissolved by heating in water, or a solution in which ethylene glycol is added and heated. In addition, compounds such as germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite can also be used. These polycondensation catalysts can be added during the esterification step. When a Ge compound is used, the amount used is preferably 10 to 150 ppm, more preferably 13 to 100 ppm, still more preferably 13 to 50 ppm, and most preferably 15 to 45 ppm as the residual amount of Ge in the polyester.

  Examples of Ti compounds include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyl titanate, and partial hydrolysates thereof, titanium acetate, titanyl oxalate, titanyl oxalate, titanyl oxalate Sodium, titanyl oxalate, titanyl calcium oxalate, titanyl oxalate compounds such as titanium strontium oxalate, titanium trimellitate, titanium sulfate, titanium chloride, titanium halide hydrolyzate, titanium oxalate, titanium fluoride, titanium hexafluoride Titanium with potassium acid, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, hydroxy polyvalent carboxylic acid or nitrogen-containing polyvalent carboxylic acid A phosphorus compound is reacted with a complex compound, a composite oxide composed of titanium and silicon or zirconium, a reaction product of titanium alkoxide and a phosphorus compound, or a reaction product of titanium alkoxide and an aromatic polycarboxylic acid or its anhydride. The reaction product obtained by the above. The Ti compound is added so that the amount of Ti remaining in the produced polymer is 0.1 to 50 ppm, preferably 0.5 to 10 ppm.

  Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony. The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 300 ppm, preferably 50 to 250 ppm, preferably 50 to 200 ppm, and more preferably 50 to 180 ppm.

  Al compounds include aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum carbonate, aluminum phosphate, aluminum phosphonate and other inorganic acid salts, aluminum n-propoxide, aluminum iso-propoxide Aluminum alkoxides such as aluminum n-butoxide and aluminum t-butoxide, aluminum chelate compounds such as aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum, etc. Organic aluminum compounds and partial hydrolysates thereof, aluminum oxide, etc. It is. Of these, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferred. The Al compound is added so that the residual amount of Al in the produced polymer is in the range of 5 to 100 ppm, preferably 10 to 50 ppm.

  Moreover, in manufacture of the polyester used by this invention, you may use together an alkali metal compound or an alkaline-earth metal compound as needed. The alkali metal or alkaline earth metal is preferably at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, and the use of an alkali metal or a compound thereof is more preferable. preferable. When using an alkali metal or a compound thereof, use of Li, Na, K is particularly preferable. Examples of the alkali metal and alkaline earth metal compounds include saturated aliphatic carboxylates such as formic acid, acetic acid, propionic acid, butyric acid, and succinic acid, and unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid. , Aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, hydroxycarboxylates such as lactic acid, citric acid and salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as acid hydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid and bromic acid, and organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butyl Alkoxides such as alkoxy, chelate compounds and the like acetylacetonate, hydrides, oxides, and hydroxides and the like.

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

  Furthermore, the polyester used in the present invention contains at least one element selected from the group consisting of silicon, manganese, iron, cobalt, zinc, gallium, strontium, zirconium, niobium, molybdenum, indium, tin, hafnium, and thallium. You may contain the metal compound to contain. These metal compounds include saturated aliphatic carboxylates such as acetates of these elements, unsaturated aliphatic carboxylates such as acrylates, aromatic carboxylates such as benzoic acid, and halogens such as trichloroacetic acid. Hydroxycarboxylates such as carboxylates and lactates, inorganic acid salts such as carbonates, organic sulfonates such as 1-propanesulfonate, organic sulfates such as lauryl sulfate, oxides, hydroxides, chlorides Products, alkoxides, acetylacetonates, and the like, and are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like. These metal compounds are added so that the residual amount of elements of these metal compounds per 1 ton of produced polymer is in the range of 0.05 to 3.0 mol. These metal compounds can be added at any stage of the polyester formation reaction step.

  Also, as stabilizers, phosphoric acid, phosphoric acid esters such as polyphosphoric acid and trimethyl phosphate, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, phosphine compounds It is preferable to use at least one phosphorus compound selected from the group consisting of: Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, phosphorous acid trimethyl ester, phosphorous acid triethyl ester, phosphorous acid tributyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid Diphenyl ester and the like. These stabilizers can be added during the esterification reaction step from a slurry preparation tank of terephthalic acid and ethylene glycol. The P compound is added so that the residual amount of P in the produced polymer is preferably in the range of 5 to 100 ppm.

  When an Al compound is used as the polycondensation catalyst, it is preferably used in combination with a phosphorus compound, and is preferably used as a solution or slurry in which an aluminum compound and a phosphorus compound are previously mixed in a solvent. In the case of an Al compound, a more preferable phosphorus compound is at least one selected from the group consisting of phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. It is a phosphorus compound. By using these phosphorus compounds, an effect of improving the catalytic activity is seen, and an effect of improving physical properties such as thermal stability of the polyester is seen. Among these, use of a phosphonic acid compound is preferable because of its great effect of improving physical properties and improving catalytic activity. Among the above-described phosphorus compounds, the use of a compound having an aromatic ring structure is preferable because the physical property improving effect and the catalytic activity improving effect are great.

The melt polycondensation polyester obtained as described above is obtained by, for example, extruding the melt polyester from the die pores into water satisfying at least one of the following (1) to (4) after completion of the melt polycondensation. A method of cutting, or a method of forming chips while cooling with cooling water satisfying at least one of the following (1) to (4) after extruding into the air through the die pores after completion of the melt polycondensation Is made into a chip.
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)
In addition, it is preferable to use water that satisfies all of (1) to (4).

  The sodium content (Na) in the cooling water is preferably Na ≦ 0.5 ppm, more preferably Na ≦ 0.1 ppm. The magnesium content (Mg) in the cooling water is preferably Mg ≦ 0.5 ppm, more preferably Mg ≦ 0.1 ppm. Further, the content (Si) of silicon in the cooling water is preferably Si ≦ 0.5 ppm, more preferably Si ≦ 0.3 ppm. Furthermore, the calcium content (Ca) in the cooling water is preferably Ca ≦ 0.5 ppm, and more preferably Ca ≦ 0.1 ppm.

  Next, the previous melt polycondensed polyester chip is preferably pre-crystallized in a continuous crystallization apparatus having two or more stages in an inert gas atmosphere. For example, in the case of PET, the temperature of 100 to 180 ° C. is 1 minute to 5 hours in the first stage precrystallization, and then the temperature of 160 to 210 ° C. is 1 minute to 3 hours in the second stage precrystallization. In the pre-crystallization of the second and higher stages, it is preferable to perform crystallization step by step at a temperature of 180 to 210 ° C. for 1 minute to 3 hours. The crystallinity of the chip after crystallization is preferably in the range of 30 to 65%, preferably 35 to 63%, and more preferably 40 to 60%. The crystallinity can be obtained from the density of the chip.

  Next, solid phase polymerization is carried out in an inert gas atmosphere or under reduced pressure at an optimum temperature for the prepolymer so that the increase in intrinsic viscosity due to solid phase polymerization is 0.10 deciliter / gram or more. For example, in the case of PET, the upper limit of the solid-state polymerization temperature is preferably 215 ° C. or lower, more preferably 210 ° C. or lower, particularly 208 ° C. or lower, and the lower limit is 200 ° C. or higher, preferably 195 ° C. or higher. is there.

  It is preferable to set the chip temperature to about 70 ° C. or less, preferably 60 ° C. or less, more preferably 50 ° C. or less within about 30 minutes, preferably within 20 minutes, more preferably within 10 minutes after completion of the solid phase polymerization.

  The shape of the polyester chip used in the present invention may be any of a cylinder shape, a square shape, a spherical shape or a flat plate shape.

  The content of dialkylene glycol copolymerized in the polyester according to the present invention is preferably 0.5 to 7.0 mol%, more preferably 1.0 to 6% of the glycol component constituting the polyester. It is 0.0 mol%, More preferably, it is 1.0-5.0 mol%. When the amount of dialkylene glycol exceeds 7.0 mol%, the thermal stability is deteriorated, and the decrease in molecular weight becomes large at the time of molding, and the increase in the content of aldehydes is unfavorable. Further, in order to produce a polyester having a dialkylene glycol content of less than 0.5 mol%, it is necessary to select uneconomical production conditions as transesterification conditions, esterification conditions or polymerization conditions. Do not fit. Here, the dialkylene glycol copolymerized in the polyester, for example, in the case of a polyester whose main structural unit is ethylene terephthalate, is a diethylene glycol by-produced during production from ethylene glycol, which is a glycol. Among them, diethylene glycol (hereinafter abbreviated as DEG) copolymerized with the polyester, and in the case of a polyester having 1,3-propylene terephthalate as a main constituent unit, is glycol 1 Of di (1,3-propylene glycol) (or bis (3-hydroxypropyl) ether) by-produced from 1,3-propylene glycol during production, di (1,3-propylene) copolymerized with the polyester Glycol (hereinafter referred to as DPG).

  In addition, the amount of diethylene glycol copolymerized with the polyester according to the present invention, particularly the polyester in which the main repeating unit is composed of ethylene terephthalate, is 1.0 to 5.0 mol% of the glycol component constituting the polyester. , Preferably 1.5 to 4.0 mol%, more preferably 1.8 to 3.5 mol%, still more preferably 2.0 to 3.0 mol%, particularly preferably 2.0 to 2.8 mol%. %. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the decrease in molecular weight becomes large at the time of molding, and the increase in acetaldehyde content and formaldehyde content becomes large, which is not preferable. Moreover, when diethylene glycol content is less than 1.0 mol%, the transparency of the obtained molded object worsens.

  Further, the content of at least one of the sodium content, calcium content, and silicon content of the polyester used in the present invention is 3 ppm or less, preferably 1 ppm or less, more preferably 0.5 ppm or less, and still more preferably 0.3 ppm. Hereinafter, it is particularly preferable that the content is 0.1 ppm or less. If the content of at least one of the sodium content, calcium content and silicon content exceeds 3 ppm, the transesterification reaction is promoted between the polyesters constituting the polyester composition, or the molecular weight distribution of the preform. The dispersion ratio Mz / Mn is less than 3.80, which is not preferable because the object of the present invention cannot be achieved. The sodium content, calcium content, and silicon content are all preferably 3 ppm or less.

In the method for producing a polyester preform of the present invention, the crystallization temperature when the temperature of polyester A is lowered and the crystallization temperature when the temperature of polyester B is lowered are preferably 162 to 190 ° C, more preferably 165 to 180 ° C. The difference between the crystallization temperature when the temperature of polyester A is lowered and the crystallization temperature when the temperature of polyester B is lowered is preferably less than 18 ° C, more preferably less than 15 ° C.
Furthermore, it is desirable that the crystallization temperature of polyester A when it is raised and the crystallization temperature of polyester B when it is raised are preferably 145 to 177 ° C, more preferably 150 to 175 ° C.
When the crystallization temperature when the temperature of the polyester A is lowered and the crystallization temperature when the temperature of the polyester B is lowered are less than 160 ° C., the effect of improving the crystallization rate of the plug portion is deteriorated. Transparency deteriorates and is a problem. When the difference between the crystallization temperature when the temperature of polyester A is lowered and the crystallization temperature when the temperature of polyester B is lowered exceeds 20 ° C., the transparency of the obtained preform becomes very poor, and the mouthpiece portion is crystallized. This causes a problem that the crystallization speed fluctuation increases and the dimensional accuracy deteriorates.
When the crystallization temperature of Polyester A is raised and the crystallization temperature of Polyester B is less than 140 ° C., the transparency of the preform is deteriorated. The effect of improving the conversion speed is worsened.

  The polyester having the above characteristics can be produced by appropriately controlling the type and amount of polycondensation catalyst, melt polycondensation, solid phase polymerization conditions, and the like. It can also be obtained by a method of giving an impact to the polyester chip thus obtained, and a method of blending a polyolefin resin, particularly polyethylene, polyamide resin, polyoxymethylene resin, etc. as described below.

  Furthermore, the polyester composition according to the present invention preferably contains 0.1 ppb to 50000 ppm of at least one resin selected from the group consisting of polyolefin resins, polyamide resins, and polyacetal resins. The blending ratio of the resin used in the present invention to the polyester is 0.1 ppb to 10000 ppm, preferably 0.3 ppb to 1000 ppm, more preferably 0.5 ppb to 100 ppm, still more preferably 1.0 ppb to 1 ppm, particularly preferably. 1.0 ppb to 45 ppb. When the blending amount is less than 0.1 ppb, the crystallization speed becomes very slow and the crystallization of the plug part of the hollow molded body becomes insufficient. Therefore, if the cycle time is shortened, the shrinkage amount of the plug part is specified. Since it does not fall within the value range, it becomes a problem of capping failure. On the other hand, if it exceeds 50000 ppm, the crystallization speed becomes high, and the crystallization of the plug portion of the hollow molded body becomes excessive, and the shrinkage amount of the plug portion does not fall within the specified value range, resulting in capping failure and the content. Leakage, and the preform for the hollow molded body is whitened, which makes normal stretching impossible. Further, in the case of a sheet-like material, if it exceeds 50000 ppm, the transparency is very poor, the stretchability is also impaired and normal stretching is impossible, and only a stretched film with large thickness spots and poor transparency can be obtained. .

  When the polyester composition according to the present invention is molded, as described above, transesterification occurs between the low IV polyester and the high IV polyester during melt-kneading in the molding machine. Accordingly, it is necessary to adjust the melt kneading conditions such as temperature, residence time, shear rate, screw configuration, etc. so that the dispersion ratio Mz / Mn of the molecular weight distribution of the obtained polyester preform does not fall below 3.80. is there. Specifically, the temperature, residence time, and shear rate should not be increased more than necessary within the range that can be uniformly kneaded, and the screw configuration will ensure plug flow, so do not insert more mixing screws or reverse screws. In addition, it is possible to shorten the melt residence time as much as possible.

  Furthermore, it demonstrates more concretely. The method for producing the polyester preform of the present invention will be briefly described below by taking as an example the case of using a polyester composition containing a polyester having ethylene terephthalate as a main repeating unit as a main component, but is limited thereto. It is not a thing. The polyester composition is a film using a generally used melt molding method after the moisture content is reduced to about 100 ppm or less, preferably 50 ppm or less by heat drying under reduced pressure or heat drying under an inert gas. Sheets, containers, and other molded articles that become other packaging materials can be molded. As conditions relating to the production of the preform, the molten resin temperature is 260 to 295 ° C., preferably 262 to 290 ° C., more preferably 265 by heating a barrel, a die, a hot runner or the like of an injection molding machine or an extrusion molding machine. It is important to set the temperature in a range of ˜285 ° C. Here, the molten resin temperature refers to a temperature obtained by immediately measuring, for example, a thermocouple thermometer with a resin injected or extruded from a nozzle tip or a die outlet of an injection molding machine or the like.

  In addition, the melt residence time in the molding machine can be set by arbitrarily selecting the shape of the extruder screw, L / D, etc. and the amount of extrusion in the case of extrusion molding, and in the case of injection molding, the injection molding machine The cycle time, the metering stroke (screw back amount) and the like are arbitrarily set, and the time is set in the range of 10 to 500 seconds, preferably 20 to 300 seconds, and more preferably 30 to 200 seconds. Here, the melt residence time is a residence time in a state where the resin is melted in the molding machine. Specifically, the melt residence time is a time during which the resin is melted and held in a cylinder in the molding machine and in a hot runner or a die. That is.

In the case of injection molding, if the melt residence time is t, t is given by the following formula (5).
t = W × S / P (5)
Here, W: Weight of molten resin (g) in a cylinder and hot runner of an injection molding machine, etc.
S: Molding cycle time (seconds)
P: Molded product weight (g)

  In the present invention, by controlling the molten resin temperature in the range of 260 to 295 ° C. and setting the melt residence time in the range of 10 to 500 seconds, the polyester composition according to the present invention can be used to obtain acetaldehyde and the like. Has a very low aldehyde content, excellent flavor retention, excellent transparency, and transparent spots (referred to as a whitened flow pattern or partial whitened or wrinkled product formed on the preform) It is possible to obtain a preform such as a preform for a hollow molded body that does not cause the occurrence of the problem and has no problem in the shape of the plug portion after crystallization. In particular, in the case of a wall-thickened molded article such as a bottle, these effects become significant.

  When the temperature of the molten resin is less than 260 ° C., the torque load of an injection molding machine or the like is large and molding becomes difficult, the obtained preform becomes extremely poor in transparency, and the thickness of the sheet-like material varies. growing. Moreover, when the temperature exceeds 285 ° C., the thermal decomposition becomes intense and the content of aldehydes such as acetaldehyde increases, which is a problem. When the melt residence time is less than 10 seconds, the transparency of the preform is deteriorated due to insufficient melting, and when it exceeds 300 seconds, the transparency of the preform is very good, but aldehydes such as acetaldehyde. The content is increased, the molding cycle is prolonged, and the productivity of the preform is reduced.

  Here, the polyester composition containing a polyester having ethylene terephthalate as a main repeating unit as a main component has been described, but the melting resin temperature at the time of producing a preform from the polyester composition according to the present invention is the melting point of the constituting polyester. It is necessary to control the set temperature of the barrel of an injection molding machine or the like or a hot runner so as to be higher by 10 to 45 ° C, preferably 10 ° C to 40 ° C, more preferably 30 ° C.

  The polyester composition according to the present invention can be obtained by uniformly mixing the constituent polyesters at a predetermined ratio by a conventionally known method. For example, the above polyester A and the above polyester B are dry blended with a tumbler, V-type blender, Henschel mixer, static mixer, etc., and the dry blended mixture is 1 with a single screw extruder, twin screw extruder, kneader, etc. For example, a method of melting and mixing more than once. Specifically, it is common that the polyester A and the polyester B are uniformly mixed at a predetermined ratio in the form of chips by the appropriate method, dried, and then subjected to molding.

  When the polyester is to be obtained by dry blending a polyester A chip and a polyester B chip by the above-described method, for example, when the variation in the mixing ratio between the two is large, Variations in intrinsic viscosity, crystallization characteristics, and the like occur, and thus the properties of aldehydes such as acetaldehyde, transparency, thickness, and the like of the obtained preform are fluctuating, which is a big problem. In addition, when the polyester after dry blending is supplied to a dryer or molding machine, or discharged from these devices, or when the polyester is moved in a transfer pipe by a gas, the polyester is moved. The blending ratio of A or polyester B may vary.

  Fluctuation rate of the blend ratio of polyester A and polyester B chips before supply to molding machine and before melt molding is within ± 5%, preferably within ± 3%, more preferably within ± 1% It is.

Also, since the majority of fines are usually more highly crystallized than the chips, the fines contained in the polyester chips remain as unmelted or incomplete melts during molding, and these are stretch molded bodies, especially There is a possibility of whitening or wrinkles in a thick stretched molded product. When the fine content of the polyester composition according to the present invention exceeds 5000 ppm, problems such as deterioration of the transparency of the preform and the stretch-molded product occur in addition to the above-described blending amount fluctuation.
Examples of a method of setting the fine content of the polyester composition to be used to 5000 ppm or less include a method of installing a vibration sieving machine, a fine removing device, and the like after each polyester manufacturing process, in particular, the solid phase polymerization process.

  Further, the difference between the melting point of the fine constituting the polyester composition according to the present invention and the melting point of the chip is 15 ° C. or less, preferably 10 ° C. or less, more preferably 5 ° C. or less. In the case where the difference includes fines exceeding 15 ° C., the crystals are not completely melted under the normally used melt molding conditions and remain as crystal nuclei. For this reason, the above-mentioned problems occur, and only a preformed body and a stretched molded body with poor transparency can be obtained. Further, when a preform having good transparency and stretchability is to be obtained from a polyester composition containing fines having a difference between the melting point of the fine and the melting point of the chip exceeding 15 ° C., it is about 25 from the melting point of the polyester chip. It must be melt molded at temperatures up to -50 ° C or higher. However, at such a high temperature, the thermal decomposition of the polyester becomes severe, and a large amount of by-products such as acetaldehyde and formaldehyde are generated, and this greatly affects the flavor of the contents of the resulting molded body. It becomes.

When the polyester composition according to the present invention is PET, a fine or film-like material having a melting point exceeding 265 ° C. becomes a problem. When the fine melting point exceeds 265 ° C., in order to ensure the transparency of the preform, the melting temperature during molding must be increased to 295 ° C. or higher, and the molecular weight distribution of the preform is dispersed. The ratio Mz / Mn is less than 3.80, and the object of the present invention cannot be achieved.
As a method of setting the melting point of fine in the polyester composition to be used to 265 ° C. or less, for example, a method using the fine removing device as described above, a plug transport method or a bucket type conveyor transport method as a polyester transport method in the manufacturing process is adopted. For example, a method using a screw feeder is used for extracting the chip from the storage tank, and these can be used in appropriate combination.

  In addition, the recovered product of the polyester molded body constituting the polyester composition according to the present invention may not be a product after the polyester is heated and melted by a melt molding machine such as an injection molding machine and then shaped into a molded body or a sheet. It is a polyester molded body that is collected again and mixed with the virgin raw material polyester for use in molding, and is sometimes referred to as a “collected product” hereinafter. Specifically, the recovered product is a product, an intermediate product such as a preform, a product that does not satisfy the product standard, a burr such as a runner generated during molding, and the like. These recovered products need to be cut or pulverized to have a size of about 1 to 10 mm, and a size substantially comparable to the size of the virgin raw material is preferable.

  The dispersion ratio Mz / Mn of the molecular weight distribution of the recovered polyester molded product is 3.80 or more, preferably 3.85 or more, more preferably 3.90 or more, and particularly preferably 4.00 or more. When a recovered product having a molecular weight distribution dispersion ratio Mz / Mn of less than 3.80 is used, the resulting polyester molded article has poor transparency, and the molding temperature must be increased to ensure transparency. Therefore, aldehydes such as acetaldehyde cannot be reduced.

  The content of the recovered polyester molded product in the polyester composition is 0.1 to 20% by weight, preferably 0.5 to 10% by weight, and more preferably 0.5 to 5% by weight. If the content of the polyester recovered product exceeds 20% by weight, the effect of promoting crystallization becomes too great, and the transparency of the preform becomes worse, and the crystallization of the plug part of the hollow molded product becomes excessive. Since the amount of shrinkage of the plug portion does not fall within the specified range, the capping portion of the plug portion becomes defective and the contents may leak.

If the acetaldehyde content of the polyester preform obtained by the production method of the present invention exceeds 15 ppm, the flavor retention of the preform and the stretched product obtained by stretching the preform deteriorates, and particularly low flavor such as mineral water. It is unsuitable as a packaging container for beverages. The formaldehyde content of the polyester preform is 5 ppm or less, preferably 3 ppm or less, more preferably 1 ppm or less, and further preferably 0.5 ppm or less. When the formaldehyde content is 5 ppm or more, the flavor, smell, etc. of the contents of the stretch-molded product molded from this polyester preform are deteriorated.
In order to reduce the acetaldehyde content of the polyester preform to 15 ppm or less, the polyester used for obtaining the polyester preform is subjected to solid-phase polymerization after melt polycondensation, and the dispersion ratio Mz / Mn of the molecular weight distribution. Is obtained by using a polyester having a value greater than 3.90.

Further, when the content of the cyclic trimer of the polyester preform or stretched molded product obtained by the production method of the present invention is 0.70% by weight or more, the oligomer adhesion to the surface of the heating mold is abrupt. The transparency of the obtained stretched hollow molded article and the like is greatly deteriorated. Furthermore, the mold cleaning takes a lot of labor and time, and the economic loss is great. The lower limit of the cyclic trimer content is 0.20% by weight or more, preferably 0.22% by weight or more, and more preferably 0.25% by weight or more from the viewpoint of economical production.
In order to reduce the content of the cyclic trimer in the polyester preform or stretched molded product to 0.70% by weight or less, in addition to melt polycondensation and solid phase polymerization of the polyester, Or after solid-phase polymerization, the obtained polyester polycondensation catalyst is obtained by deactivation treatment.

  Moreover, when the haze of the polyester preform obtained by the production method of the present invention exceeds 10.0%, the transparency of the stretched hollow molded product obtained by stretching the preform is deteriorated, particularly In the stretched hollow molded body heat-fixed, the transparency is very deteriorated.

  Further, when the dispersion ratio Mz / Mn of the molecular weight distribution of the polyester preform obtained by the production method of the present invention is less than 3.80, the transparency of the preform is poor, and the aldehyde such as acetaldehyde of the preform is not good. It is not preferable because it cannot reduce the kind. In addition, only a stretched polyester article having a lower strength can be obtained. Further, when a poor quality product of the obtained preform and a stretched molded product in the future is mixed with virgin PET to form a raw material for molding, a dispersion ratio Mz / Mn of the molecular weight distribution of the obtained preform is obtained. Tends to be less than 3.80, and it becomes very difficult to obtain a preform with good transparency in which the content of aldehydes such as acetaldehyde is reduced.

  The polyester preform of the present invention preferably has an increase in cyclic trimer of 0.40% by weight or less when melted at a temperature of 290 ° C. for 60 minutes. The polyester used for obtaining the body can be produced by deactivating the polycondensation catalyst of the polyester obtained after melt polycondensation or after solid phase polymerization. The increase amount of the cyclic trimer when melted at a temperature of 290 ° C. for 60 minutes is preferably 0.3% by weight or less, more preferably 0.1% by weight or less. When the increase amount exceeds 0.4% by weight, the cyclic trimer increases at the time of molding resin melting, the adhesion of the oligomer to the surface of the heating mold increases rapidly, and the transparency of the obtained hollow molded body is increased. Very worse.

  Examples of the method of deactivating the polyester polycondensation catalyst include a method of contacting the polyester chip with water, water vapor or water vapor-containing gas.

  Examples of the hot water treatment method include a method in which the polyester according to the present invention or a polyester composition containing these as a main component is immersed in water, a method in which water is applied to these chips in a shower, and the like. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180 ° C., preferably 40 to 150 ° C., more preferably 50 to 120 ° C.

  When the polyester chip is contacted with water vapor or water vapor containing gas, the water vapor or water vapor containing gas or water containing air at a temperature of 50 to 150 ° C., preferably 50 to 110 ° C., is preferably used per 1 kg of the granular polyester. The water vapor is supplied as water vapor in an amount of 0.5 g or more, or is present to bring the granular polyester into contact with water vapor. The contact between the polyester chip and water vapor is usually performed for 10 minutes to 2 days, preferably 20 minutes to 10 hours. The processing method may be either a continuous method or a batch method.

  The water used in the hot water treatment method is preferably water that satisfies at least one of the above (1) to (4). Of course, it is most preferable to use water that satisfies all of (1) to (4).

  Further, as another means for deactivating the polycondensation catalyst, there is a method in which a phosphorus compound is blended with the polyester and mixed and reacted in a molten state such as during molding to deactivate the polycondensation catalyst.

  As a method of blending a phosphorous compound with polyester, a predetermined amount of phosphorous compound is polyester by a method of dry blending the phosphorous compound with the polyester or a method of mixing a polyester masterbatch chip in which a phosphorous compound is melt-kneaded and blended with a polyester chip. And a method of inactivating the polycondensation catalyst by melting in an extruder or a molding machine, a method of immersing chips in a phosphorus compound solution, particularly a phosphoric acid aqueous solution, and a method of adding as a master batch. These phosphorus compounds may be copolymerized with polyester.

  Examples of the phosphorus compound used include phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof. Specific examples thereof are the compounds described above, and these may be used alone or in combination of two or more.

  In addition, using at least one polyester according to the present invention or a polyester composition in which all the polyester catalysts are deactivated so that transesterification hardly occurs reduces transesterification during melt molding and reduces molding conditions. This is also preferable in that it is possible to suppress variations in quality of the preform due to fluctuations.

  It is also preferable to add or copolymerize a phosphorous compound that has lost the catalyst to one polyester during blending. At this time, a phosphorus compound is added to a polyester polycondensed with a catalyst (for example, Ge, Sb) whose catalytic activity is not greatly reduced with a phosphorus compound, and is then overlapped with a catalyst (for example, Ti, Al) whose catalytic activity is decreased with a phosphorus compound. It is also preferable to use a blend with a condensed polyester.

Moreover, when the acetaldehyde content of the polyester stretch molded article obtained by the production method of the present invention exceeds 15 ppm, the flavor retention of the stretch molded article deteriorates, and particularly as a packaging container for low flavor beverages such as mineral water. Inappropriate.
In order to make the content of acetaldehyde in the stretched polyester molded article 15 ppm or less, it can be achieved by using a polyester preform having an acetaldehyde content of 15 ppm or less.

Moreover, when the haze of the polyester stretch-molded product obtained by the production method of the present invention exceeds 5.0%, the commercial value of a colorless and transparent soft drink container such as mineral water becomes low.
In order to obtain such a stretched molded product having a haze of 5.0% or less, it is desirable to use a preform having a haze of 10.0% or less.

  The polyester preform of the present invention can be formed into a film shape, a sheet shape, a hollow molded body shape, or the like by a melt molding method using a generally used extrusion molding machine, injection molding machine, or the like. It can be obtained in the form of a preform obtained by compression molding the molten mass obtained in this way. Moreover, the polyester preform can be formed into a polyester stretch-molded body using any stretching method among uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching. Further, it can be formed into a cup shape or a tray shape by pressure forming or vacuum forming.

  Moreover, it is possible to improve mechanical strength by extending | stretching the sheet-like material which consists of a polyester composition based on this invention at least to a uniaxial direction. The stretched film comprising the polyester composition according to the present invention is a sheet-like material obtained by injection molding or extrusion molding, and is usually selected from uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching used for PET stretching. The stretching method is used. Further, it can be formed into a cup shape or a tray shape by pressure forming or vacuum forming.

Below, the concrete manufacturing method about the various uses in the case of PET is demonstrated easily.
A sheet-like material, which is a typical example of a PET polyester preform, can be obtained by melt extrusion molding at a temperature of 270 to 295 ° C. with a single screw extruder or a twin screw extruder. The thickness of the sheet is about 50 to 3000 microns.

In producing a stretched film, the stretching temperature is usually 80 to 130 ° C. Stretching may be uniaxial or biaxial, but biaxial stretching is preferred from the viewpoint of film physical properties. In the case of uniaxial stretching, the stretching ratio is usually 1.1 to 10 times, preferably 1.5 to 8 times. In the case of biaxial stretching, the longitudinal and transverse directions are usually 1.1 to 8 times, respectively. Preferably, it may be performed in a range of 1.5 to 5 times. The vertical / horizontal magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film can be further heat-set to improve heat resistance and mechanical strength. The heat setting is usually performed under tension at 120 to 240 ° C., preferably 150 to 230 ° C., usually for several seconds to several hours, preferably several tens of seconds to several minutes. The stretched film has a thickness of about 5 to 100 microns.

  Moreover, when manufacturing a stretched hollow molded body, the polyester preform of the present invention is stretch blow molded, and an apparatus conventionally used in blow molding of PET can be used. Specifically, for example, once a preform is formed by injection molding or extrusion molding, the plug part and the bottom part are processed as it is, and then reheated, and then biaxial stretch blow molding such as hot parison method or cold parison method The law applies. The molding temperature in this case, specifically, the temperature of each part of the cylinder of the molding machine and the nozzle is usually in the range of 260 to 295 ° C. The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction. The obtained stretched hollow molded body can be used as it is, but in particular in the case of beverages that require heat filling such as fruit juice beverages, oolong tea, etc., generally, heat setting treatment is further performed in a blow mold, Used with heat resistance. The heat setting is usually performed at 100 to 200 ° C., preferably 120 to 180 ° C. for several seconds to several hours, preferably several seconds to several minutes, under tension by compressed air or the like.

  In addition, in order to impart heat resistance to the plug part, the plug part of the polyester preform obtained by injection molding or extrusion molding is crystallized in a far infrared or near infrared heater installation oven, or bottle molding Later, the plug is crystallized with the heater.

The polyester preform of the present invention can also be used for the production of heat-resistant bottles by a two-stage blow molding method comprising a primary blow molding process and a secondary blow molding process.
In the case of the two-stage blow molding method of PET, a preform obtained by crystallizing the plug portion as described above in the primary blow molding step is 1.0 to 1.0 to the final product volume at the same stretching temperature as described above. The biaxially stretched blow molding is performed about twice, and then the obtained primary molded body is heated at about 100 to 250 ° C. and then subjected to secondary blowing in a mold of about 80 to 200 ° C. in the secondary blow molding step.

  In addition, a stretched hollow molded body can be obtained by a so-called compression molding method in which a preform obtained by compression molding a molten mass cut after the polyester according to the present invention is melt-extruded is stretch blow molded.

  For the polyester according to the present invention, known ultraviolet absorbers, antioxidants, oxygen scavengers, lubricants added from the outside, lubricants precipitated internally during the reaction, mold release agents, nucleating agents, stabilizers as necessary In addition, various additives such as an antistatic agent, a bluing agent, a dye and a pigment, and a polyamide resin from metaxylylenediamine and adipic acid may be added to improve oxygen permeability.

  In addition, when the polyester stretch-molded product obtained from the polyester preform of the present invention is a stretched film, calcium carbonate, magnesium carbonate, carbonic acid, or carbonic acid is used to improve handling properties such as slipperiness, rollability, and blocking resistance. Inorganic particles such as barium, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, organic salt particles such as calcium oxalate, calcium, barium, zinc, manganese, magnesium, terephthalate, divinylbenzene, styrene, Inactive particles such as crosslinked polymer particles such as acrylic acid, methacrylic acid, acrylic monomers or vinyl monomers of methacrylic acid or copolymers thereof can be contained.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
The main characteristic value measurement methods will be described below.
(1) Intrinsic viscosity of polyester (IV)
It calculated | required from the solution viscosity at 30 degreeC in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent. The IV of the polyester composition was a weighted average value calculated from the IV of the constituent polyester.

(2) Polyethylene glycol content of polyester (hereinafter referred to as [DEG content])
Decomposition with methanol, the amount of DEG was quantified by gas chromatography, and expressed as a ratio (mol%) to the total glycol components.
(3) Polyester cyclic trimer content (hereinafter referred to as “CT content”)
300 mg of the frozen and ground sample is dissolved in 3 ml of a hexafluoroisopropanol / chloroform mixed solution (volume ratio = 2/3), and further diluted with 30 ml of chloroform. To this is added 15 ml of methanol to precipitate the polymer, followed by filtration. The filtrate was evaporated to dryness, brought to a constant volume with 10 ml of dimethylformamide, and the cyclic trimer was quantified by high performance liquid chromatography.

(4) Increasing amount of cyclic trimer at the time of melting polyester (△ CT amount)
After cutting out a small piece of about 1 to 3 mm in size from the mouth of the preform formed in (17) and then drying it, 3 g of this polyester sample was placed in a glass test tube and heated at 290 ° C. under a nitrogen atmosphere. Immerse in an oil bath for 60 minutes to melt. The amount of increase in cyclic trimer at the time of melting is determined by the following equation.
Increase in cyclic trimer during melting (wt%) =
Cyclic trimer content after melting (wt%)-cyclic trimer content of preform before melting (wt%)

(5) Acetaldehyde content of polyester (hereinafter referred to as “AA content”)
Sample / distilled water = 1 g / 2 cc of glass ampoule substituted with nitrogen was sealed and subjected to extraction treatment at 160 ° C for 2 hours. After cooling, acetaldehyde in the extract was measured by high-sensitivity gas chromatography. The concentration was expressed in ppm. In the case of the chip, the sample is used as it is, and the preform or the hollow molded body is a sample collected to a size of about 2 mm from the plug portion. The AA content of the polyester composition was obtained by calculating a weighted average value of the AA content of the polyester constituting the polyester composition. Further, the variation value of the acetaldehyde content of the molded product was measured for 10 samples, and the difference between the maximum value and the minimum value was obtained.

(6) Sodium content and calcium content of polyester About 5 to 10 g of a sample is put in a platinum crucible and ashed at about 550 ° C., then dissolved in 6N hydrochloric acid and evaporated to dryness, and the residue is dissolved in 1N hydrochloric acid. This solution was measured by atomic absorption spectrometry.

(7) Silicon content of polyester About 5 to 10 g of a sample is put in a platinum crucible and incinerated at about 550 ° C., then sodium carbonate is added and dissolved by heating, and dissolved in 1N hydrochloric acid. This solution was measured with an inductively coupled plasma optical emission spectrometer manufactured by Shimadzu Corporation.

(8) Sodium content, Magnesium content, Calcium content and Silicon content of chip cooling water or treated water Chip cooling water is collected and filtered through a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd., and the filtrate is manufactured by Shimadzu Corporation. Measurement was performed with an inductively coupled plasma emission spectrometer.

(9) Fine content measurement About 0.1 kg of resin is placed on a sieve (diameter 20 cm) with an open wire mesh that does not allow regular-sized chips to pass through, and fines are separated while flowing ion-exchanged water. And collected. This operation was repeated for a total of 20 kg. However, when the fine content is small, the amount of the sample is appropriately changed.
The separated fines were collected by filtration with a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd. using a vacuum filtration device. These were dried together with a glass filter in a dryer at 100 ° C. for 2 hours, then cooled and weighed. Again, the same operations of washing and drying with ion-exchanged water were repeated to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to obtain the fine weight. The fine content is the fine weight / the total resin weight that has been sieved.
In the case of the following examples, a sieve (A) with a wire mesh having a nominal size of 1.7 mm according to JIS-Z8801 was used.

(10) Melting point of fine Measured using a differential scanning calorimeter (DSC) manufactured by Seiko Denshi Kogyo Co., Ltd., RDC-220. In (7), the fine collected from 20 kg of polyester was dried under reduced pressure at 25 ° C. for 3 days, and then DSC measurement was performed at a heating rate of 20 ° C./min using 4 mg of sample for one measurement. The melting peak temperature on the highest temperature side of the peak temperature is determined. The measurement is performed on a maximum of 10 samples, and the average value of the melting peak temperatures on the highest temperature side is obtained. If there is a single melting peak, the temperature is determined.

(11) Density (ρ) and crystallinity (CR) of polyester chip
The density (ρ) of the chip at 30 ° C. was measured with a density gradient tube of calcium nitrate / water solution.
In the case of PET, the crystallinity was calculated from the following formula.
CR = 100ρ _c (ρ−ρ _a ) / ρ (ρ _c −ρ _a )
Where ρ is the density of the chip
ρ _a : amorphous density (1.335 g / cm ³ )
ρ _c : crystal density (1.455 g / cm ³ )

(12) Average weight (W) of polyester chip and ratio of average weight (W _A / W _B )
After removing fines with ion-exchanged water, the weight of 100 dried polyester chips was measured, and the average value was defined as the average weight (W). When the polyester composition is a mixture of two kinds of polyesters, the ratio of the average weights of the two kinds of polyester chips (W _A / W _B ) is the average weight of the polyester chips having a larger average weight among the two kinds. and W _a, the average weight of the average weight of small polyester chips as W _B, was calculated W _a / W _B. When the two types of polyester chips have the same average weight, W _A / W _B is 1.00. Moreover, when it consists of 2 or more types of polyester, it calculates as mentioned above for 2 types of polyester with many mixing ratios.

(13) Crystallization temperature (Tc1) when the molded body is heated and crystallization temperature (Tc2) when the temperature is lowered
Measured with a differential thermal analyzer (DSC), RDC-220, manufactured by Seiko Electronics Industry Co., Ltd. A 10 mg sample from the center of a 2 mm thick plate of the molded plate of (16) below is used. In the case of a preform, a sample was taken from the trunk.
The temperature was raised at a rate of temperature rise of 20 ° C./minute and held at 290 ° C. for 3 minutes, then the temperature was lowered from 290 ° C. to 240 ° C. at 10 ° C./minute, and further from 240 ° C. to 130 ° C. at 7 ° C./minute. The temperature dropped. The peak temperature of the crystallization peak observed at the time of temperature rise is defined as the crystallization temperature (Tc1) at the time of temperature increase, and the peak temperature of the crystallization peak observed at the time of temperature decrease is defined as the crystallization temperature (Tc2).

(14) Measurement of number average molecular weight (Mn), Z average molecular weight (Mz) and dispersion ratio Average molecular weight and molecular weight fraction were determined by GPC method.
(Preparation of sample) 1 mg of a sample was dissolved in 0.2 ml of chloroform / hexafluoroisopropanol = 3/2 (vol%), and then diluted with 3.8 ml of chloroform to prepare a sample solution. In the case of a chip, it was frozen and ground to obtain a sample.
(Eluent) Chloroform / hexafluoroisopropanol = 98/2 (vol%)
(Apparatus) TOSOH HLC-8220GPC manufactured by Tosoh Corporation was used.
(Column) TSKgel SuperHM-H × 2 + manufactured by Tosoh Corporation
TSKgel SuperH2000
(Standard polystyrene) TSK standard polystyrene manufactured by Tosoh Corporation was used.
(Measurement conditions) Measurement temperature 40 ° C., flow rate 0.6 ml / min (detector) UV detector 254 nm
(Molecular weight conversion) Calculation was performed in terms of standard styrene.
(Integration range) The peak start was set to 700 with standard polystyrene, and the peak end was set to 700 with standard polystyrene.
The dispersion ratio was determined from the following.
Dispersion ratio = Mz / Mn
In the case of a preform molded by the above method, a sample was taken from the mouth.

(15) Haze (Fraction%)
For the preformed body, a sample was cut from the preformed body (thickness 3.7 mm) of the following (17-1), and for the stretched molded body, a sample was cut from the bottle body of the following (17-2). It measured with the color Co., Ltd. haze meter and modelNDH2000. However, the preform was measured by filling the cell with liquid paraffin.

(16) Molding of Stepped Molding Plate The polyester dried under reduced pressure at 140 ° C. for about 16 hours using a vacuum dryer DP61 type manufactured by Yamato Kagaku Co., Ltd. with an injection molding machine M-150C-DM type injection molding machine manufactured by Meiki Seisakusho 2 having a gate part (G) as shown in FIG. 2 (thickness of A part = 2 mm, thickness of B part = 3 mm, thickness of C part = 4 mm, thickness of D part = 5 mm, E part of A stepped molded plate having a thickness of 10 mm and a thickness of F portion of 11 mm was injection molded.
In order to prevent moisture absorption during molding, the inside of the molding material hopper was purged with a dry inert gas (nitrogen gas). The plasticizing conditions of the M-150C-DM injection molding machine are: feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, cylinder temperature 45 ° C., 250 ° C. from the bottom of the hopper in order, nozzle The temperature was set at 290 ° C. The injection conditions are 20% for injection speed and holding pressure, and the injection pressure and holding pressure are adjusted so that the weight of the molded product is 146 ± 0.2g. In this case, the holding pressure is 0.5MPa lower than the injection pressure. It was adjusted.
The upper limit of the injection time and pressure holding time is set to 10 seconds and 7 seconds, respectively, and the cooling time is set to 50 seconds. The total cycle time including the time for taking out the molded product is about 75 seconds.

Although the temperature of the mold is always controlled by introducing cooling water having a water temperature of 10 ° C., the mold surface temperature at the time of stable molding is around 22 ° C.
The test plate for evaluating the molded product characteristics was arbitrarily selected from the 11th to 18th shots of the stable molded product after the molding material was introduced and the resin was replaced.
A 2 mm-thick plate (part A in FIG. 1) is used for measuring the crystallization temperature (Tc1) at the time of temperature increase and the crystallization temperature (Tc2) at the time of temperature decrease.

(17) Molding of hollow molded body 1) Molding of preform In order to prevent moisture absorption of the chip during molding using a polyester chip dried in advance using a vacuum dryer DP63 model manufactured by Yamato Scientific, Was purged with a dry inert gas (nitrogen gas).
The plasticizing conditions of the M-150C-DM injection molding machine manufactured by Meiki Seisakusho include feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, weighing position 50 mm, and cylinder temperature in order from directly under the hopper. The temperature was set to 45 ° C., 250 ° C., and thereafter 280 ° C. including the nozzle. The injection conditions were such that the injection speed and holding pressure were 10%, and the injection pressure and holding pressure were adjusted so that the weight of the molded product was 58.6 ± 0.2 g. Adjusted to 5 MPa lower. The cooling time is set to 20 seconds, and the total cycle time including the molded product take-out time is approximately 42 seconds. The preform has an outer diameter of 29.4 mm, a length of 145.5 mm, and a wall thickness of about 3.7 mm.
The mold is always controlled by introducing cooling water having a water temperature of 18 ° C., but the mold surface temperature at the time of molding stability is around 29 ° C. The preform for property evaluation was arbitrarily selected from stable molded products 20 to 50 shots after the start of molding after introducing the molding material and replacing the resin. Take a sample from the mouth of the preform, measure the intrinsic viscosity, acetaldehyde content (AA content), cyclic trimer content (CT content), number average molecular weight (Mn), Z average molecular weight (Mz) and dispersion Used for ratio measurement.

2) Molding of stretched hollow molded body (bottle) The plug portion of the preform was heated and crystallized with a home-made plug portion crystallization apparatus. Next, this preform was biaxially stretched and blown at a magnification of about 2.5 times in the longitudinal direction and about 3.8 times in the circumferential direction on a LB-01E molding machine manufactured by CORPOPLAST, and subsequently set at about 145 ° C. It was heat-set in the mold for 7 seconds to mold a 1500 cc container (trunk thickness 0.45 mm). The stretching temperature was controlled at 100 ° C., and any one of 10 to 30 shots of a stable molded product from the start of molding was arbitrarily selected.

(18) Strength measurement of bottle body (bottle strength evaluation with biaxially stretched container)
The body of the bottle molded by the above method is cut into a large size with a cutter, punched with a super dumbbell cutter model SDMK-1000D manufactured by Dumbbell Co., Ltd. (according to JISK-7162-5A), and a tensile tester SS-207D-U ( The strength was measured using Toyo Baldwin Co., Ltd.

(19) Appearance of Hollow Molded Body Twenty hollow molded bodies from the tenth molding start of (17) were visually observed and evaluated as follows.
◎: Transparent and no appearance problem △: There is a little whitened flow pattern or whitened product in the hollow molded body ×: White flowed pattern or whitened product in the hollow molded body

(20) Shape and dimensions of the plug portion of the preform for the hollow molded body The shape and size of the preform plug portion crystallized in (17) were visually observed and evaluated as follows.
A: Extremely stable dimensional accuracy was obtained.
○: Stable dimensional accuracy was obtained.
X: Insufficient crystallization, poor shape, or excessive crystallization, poor dimensionality.

(Polyester 1 (Pes1))
High purity terephthalic acid and ethyl glycol are continuously supplied to the first esterification reactor containing the reactants in advance, and the average residence time is 3 hours at about 250 ° C. and 0.5 kg / cm ² G with stirring. Reaction was performed. Moreover, crystalline germanium dioxide was dissolved in water by heating, and a catalyst solution in which ethylene glycol was added and heat-treated thereto and an ethylene glycol solution of phosphoric acid were continuously supplied separately to the first esterification reactor. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 0.05 kg / cm ² G to a predetermined reactivity. The esterification reaction product is continuously sent to the first polymerization reactor under stirring at about 265 ° C. and 25 torr for 1 hour, then in the second polymerization reactor under stirring at about 265 ° C. and 3 torr for 1 hour, and further Polymerization was conducted at about 275 ° C. and 0.5 to 1 torr with stirring in the third polymerization reactor. The obtained PET resin had an intrinsic viscosity (IV) of 0.53 deciliter / gram and a DEG content of 2.5 mol%.
The cooling water at the time of chip formation is ion-exchanged water having a sodium content of 0.1 ppm, a calcium content of about 0.1 ppm, a magnesium content of about 0.04 ppm, and a silicon content of about 0.6 ppm. Using.

After fine removal of this resin, it was subsequently crystallized at about 155 ° C. under a nitrogen atmosphere, further preheated to about 200 ° C. under a nitrogen atmosphere, and then sent to a continuous solid-phase polymerization reactor for solid phase polymerization at about 208 ° C. under a nitrogen atmosphere. . After the solid-phase polymerization, the fine particles were removed by continuous treatment in the sieving step and the fine removal step.
The obtained PET has an intrinsic viscosity of 0.70 deciliter / gram, an acetaldehyde (AA) content of 3.4 ppm, a cyclic trimer content of 0.34% by weight, a chip shape of an elliptic cylinder, and an average chip weight. (W) 24.7 mg, chip crystallinity 55.5%, sodium content 0.03 ppm, calcium content 0.05 ppm, silicon content 0.6 ppm, fine content about 50 ppm, fine content The melting point was 250 ° C. The properties of the obtained PET are shown in Table-1.

(Polyester 2 (Pes2), 3 (Pes3))
Polyesters 2 and 3 were obtained by reacting in the same manner as polyester 1 except that the amount of polycondensation catalyst added and the solid phase polymerization time were changed. The properties of the obtained PET are shown in Table-1. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 4 (Pes4))
The reaction is carried out in the same manner as Pes1 except that the amount of polycondensation catalyst added is reduced and the final polycondensation time is shortened to obtain a melt polycondensation prepolymer with IV = 0.47. Chips were made using water with 10.0 ppm, a calcium content of about 12.3 ppm, a magnesium content of about 5.9 ppm, and a silicon content of 12.0 ppm. Polyester 4 was obtained by solid phase polymerization in the same manner as polyester 1 except that the solid phase polymerization time was shortened and the fine removal step was omitted.
The properties of the obtained PET are shown in Table-1. The fine content was about 700 ppm, the sodium content was 5.0 ppm, the calcium content was 5.6 ppm, and the silicon content was 6.7 ppm.

(Polyester 5 (Pes5), 6 (Pes6))
Polyesters 5 and 6 were obtained in the same manner as Polyester 1 except that the average chip weight (W) was changed as shown in Table 1 and the solid phase polymerization time was changed.
In both cases, the particle size was increased, so that the solid phase polymerization time was about 1.7 times longer than in Example 1. The properties of the obtained PET are shown in Table-1. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 7 (Pes7))
A prepolymer was obtained by melt polycondensation in the same manner as polyester 1 except that the amount of polycondensation catalyst added was changed.
The resulting prepolymer was finely removed and then charged into a rotary vacuum solid-phase polymerization apparatus, and crystallized at 70 to 160 ° C. under reduced pressure while rotating, followed by solid-phase polymerization at 213 ° C. After solid-phase polymerization, fines were removed in the sieving step. The properties of the obtained PET are shown in Table-1. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 8 (Pes8), 9 (Pes9))
The amount of polycondensation catalyst added was changed, and water with a sodium content of about 11.9 ppm, a calcium content of about 10.3 ppm, and a silicon content of 15.0 ppm was used as cooling water during chip formation. Polyesters 8 and 9 were obtained by melt polycondensation and solid phase polymerization in the same manner as polyester 1 or polyester 2 except that the removing step was omitted. The properties of the obtained PET are shown in Table-1. The sodium content, calcium content, and silicon content were the same as or higher than those of polyester 4.

(Polyester 10 (Pes10), 11 (Pes11))
As a polycondensation catalyst, the same procedure as for polyester 1 or polyester 2 except that an ethylene glycol solution of basic aluminum acetate, Irganox 1222 (manufactured by Ciba Specialty Chemicals) and an ethylene glycol solution in which ethylene glycol is preheated is used. By reacting, polyesters 10 and 11 were obtained.
The properties of the obtained PET are shown in Table-1. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 12 (Pes12), 13 (Pes13))
As a polycondensation catalyst, polyesters 12 and 13 were obtained by reacting in the same manner as polyester 1 or polyester 2, except that an ethylene glycol solution of titanium tetrabutoxide and an ethylene glycol solution of magnesium acetate tetrahydrate were used.
The properties of the obtained PET are shown in Table-1. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 14 (Pes14))
The polyester 1 is water-treated by continuously feeding it from the supply port (1) at the upper part of the treatment tank to the following water treatment tank controlled at a treatment water temperature of 95 ° C. at a rate of 50 kg / hour. A PET chip was continuously extracted from the discharge port (3) with treated water at a rate of 50 kg / hour. The introduced water collected in front of the ion exchange water inlet (9) of the water treatment apparatus has a particle content of about 1000 particles / 10 ml, a sodium content of 0.04 ppm, and a magnesium content of 0.1. 05 ppm, calcium content is 0.05 ppm, silicon content is 0.12 ppm, and the number of particles having a particle diameter of 1 to 40 μm of recycled water after treatment in the filtration device (5) and the adsorption tower (8) is about 10,000. Pieces / 10 ml. After the water treatment, fines and the like were removed in the same manner as in Example 1.

For water treatment of the polyester chip, the apparatus shown in FIG. 3 is used. The raw material chip supply port (1) at the upper part of the treatment tank, the overflow discharge port (2) located at the upper limit level of the treatment water in the treatment tank, and the lower part of the treatment tank Discharge port (3) for the mixture of polyester chip and treated water, treated water discharged from this overflow discharge port, treated water discharged from the treatment tank, and draining device (4 ) Through which the treated water is sent again to the water treatment tank via the fine powder removing device (5) whose filter medium is a paper-made continuous filter, and the introduction of the treated water after removal of the fine powder. A tower-type treatment tank having an internal capacity of about 50 m ³ equipped with a mouth (7), an adsorption tower (8) for adsorbing acetaldehyde in treated water after fine powder removal, and a new ion-exchange water inlet (9) was used. .
The properties of the obtained PET are the same as the properties of polyester 1 described in Table 1 except that the cyclic trimer increase amount (ΔCT amount) upon melting is 0.15% by weight. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

(Polyester 15 (Pes15))
Polyester 2 was treated with water in the same manner as described above to obtain polyester 15.
The properties of the obtained PET are the same as those of the polyester 2 described in Table 1, except that the cyclic trimer increase amount (ΔCT amount) at the time of melting is 0.15% by weight. Sodium content, calcium content, and silicon content were similar to those of polyester 1.

Example 1
A polyester mixture obtained by blending the above polyester 1 and polyester 2 pellets in a ratio of 7: 3 was obtained by molding at 290 ° C. by the method (16) and by injection molding by the method (17). Evaluations were performed on preforms and hollow molded containers. The results are shown in Table 2.
The AA content of the preform is 8.7 ppm, its fluctuation value is 0.3 ppm, and haze is 2.2%, which is a satisfactory value, and the shape and size after crystallization of the preformed body plug part are satisfactory. Also, there was no problem with the appearance and haze of the stretched hollow molded body.

(Example 2)
The polyester composition of Example 2 was evaluated in the same manner as in Example 1 with the composition shown in Table 2 using a mixture of water-treated PET. The results are shown in Table 2. All the evaluated characteristics were as good as in Example 1. Further, the amount of increase in cyclic trimer (ΔCT amount) at the time of melting was as small as 0.14% by weight.

(Comparative Example 1)
As shown in Table 2, the polyester 3 of Comparative Example 1 was evaluated in the same manner as in Example 1. Obviously, the AA content of the preform and its fluctuation value and haze value are high when compared with the examples, and the shape and dimensions of the preformed body plug after crystallization are insufficiently crystallized and poorly shaped. The appearance and haze of the stretched hollow molded article were also poor. The results are shown in Table 2.

(Comparative Example 2)
As shown in Table 2, the polyester composition of Comparative Example 2 was evaluated. Obviously, the haze value of the preformed body was high, the shape and dimensions of the preformed body plug portion after crystallization were poor, and the appearance and haze of the stretched hollow molded body were also poor as compared with the examples. The results are shown in Table 2.

(Comparative Example 3)
As shown in Table 2, the polyester composition of Comparative Example 3 was evaluated. Obviously, the AA content of the preform, its fluctuation value, and the haze value are high, and the shape and dimensions after crystallization of the preformed plug portion are poor, as compared with the examples. Appearance and haze were also poor. The results are shown in Table 2.

(Comparative Example 4)
As shown in Table 2, the polyester composition of Comparative Example 4 was evaluated. Obviously, the AA content of the preform, its fluctuation value, and the haze value are high, and the shape and dimensions after crystallization of the preformed plug portion are poor, as compared with the examples. Appearance haze was also bad. The results are shown in Table 2.

(Comparative Example 5)
As shown in Table 2, the polyester composition of Comparative Example 5 was evaluated. Obviously, the AA content of the preform, its fluctuation value, and the haze value are high, and the shape and dimensions after crystallization of the preformed plug portion are poor, as compared with the examples. Appearance and haze were also poor. The results are shown in Table 2.

(Example 3)
According to the composition shown in Table 2, the polyester composition of Example 3 was evaluated in the same manner as in Example 1. The results are shown in Table 3. All the evaluated characteristics were as good as in Example 1.

Example 4
According to the composition shown in Table 2, the polyester composition of Example 5 was evaluated in the same manner as in Example 1. The results are shown in Table 2. All the evaluated characteristics were as good as in Example 1.

  According to the present invention, there is provided a method for producing a preform in which the production of aldehydes such as acetaldehyde during molding is highly suppressed, the transparency is extremely excellent, and the variation in transparency is very small. The preformed body is biaxially stretched or biaxially stretched blow-molded, or subsequently heat-set, so that the content of aldehydes such as acetaldehyde is extremely low, and the flavor retention is excellent, and the transparency and elastic modulus It is possible to provide a biaxially stretched film or hollow molded body having excellent mechanical properties such as tensile strength, a method for producing a stretched molded body having excellent heat fixability, and a polyester molded body obtained therefrom.

Plan view of stepped plate Side view of stepped plate It is the schematic of the water treatment apparatus used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material chip supply port 2 Overflow discharge port 3 Drain port of polyester chip and treated water 4 Drainage device 5 Fine removal device 6 Pipe 7 Recycled water and / or ion exchange water introduction port 8 Adsorption tower 9 Ion exchange water introduction port

Claims (11)

  A method for producing a polyester preform by molding a polyester composition comprising at least two polyesters having substantially the same composition and different intrinsic viscosities as main components, the difference in intrinsic viscosities of the polyesters 0.05 to 0.30 deciliter / gram, and the ratio of the average weight (W) of each polyester chip and the average weight (W) of each polyester is 5 to 50 mg and 1.00 to 1.30, respectively. A method for producing a polyester preform, wherein the difference in crystallinity of polyester chips is 10% or less, and the dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is 3.90 or more. A method for producing a polyester preform comprising molding a polyester composition containing at least two kinds of polyesters mainly composed of ethylene terephthalate as a main repeating unit, wherein the polyester composition has an intrinsic viscosity of 0.00. 60 to 0.80 deciliter / gram of polyester A, 55 to 95 parts by weight, and polyester B having an intrinsic viscosity 0.05 to 0.30 deciliter / gram higher than the polyester A, 45 to 5 parts by weight, The dispersion ratio Mz / Mn of the molecular weight distribution of the polyester composition is 3.90 or more, the crystallinity of each polyester chip is 50 to 66%, the crystallinity of the polyester A chip and the crystallinity of the polyester B chip Difference is 10% or less, average weight (W) of each polyester chip is 5 to 50 mg, polyester Process for producing a polyester preform, wherein the ratio of the average weight of the chips (W _A) and the average weight of the polyester B chip (W _B) is 1.00 to 1.30.   The crystallization temperature when the temperature of the polyester A is lowered and the crystallization temperature when the temperature of the polyester B is lowered are 160 to 200 ° C., and the difference between the crystallization temperature when the polyester A is lowered and the crystallization temperature when the polyester B is lowered The method for producing a polyester preform according to claim 2, wherein the temperature is less than 20 ° C.   4. The polyester preform according to claim 2, wherein the polyester A has a crystallization temperature when the temperature is raised and a crystallization temperature when the temperature of the polyester B is raised is 140 to 180 ° C. 5. Production method.   The fine content of the said polyester composition is 5000 ppm or less, The manufacturing method of the polyester preform in any one of Claims 1-4 characterized by the above-mentioned.   The method for producing a polyester preform according to claim 5, wherein the fine has a melting point of 265 ° C. or less.   The method for producing a polyester preform according to any one of claims 1 to 6, wherein the polyester composition includes a recovered product of a polyester molded body.   A method for producing a polyester stretch-molded product, wherein the polyester preform obtained by the production method according to claim 1 is stretched in at least one direction.   A polyester preform obtained by biaxially stretch-blow molding the polyester preform obtained by the production method according to any one of claims 1 to 7, and heat-fixing the stretch-molded body after stretch molding as necessary. A method for producing a hollow molded body.   The acetaldehyde content obtained by the production method according to claim 2 is 15 ppm or less, the cyclic trimer content is 0.70% or less, the haze is 10.0% or less, and the molecular weight distribution is dispersed. A polyester preform having a ratio Mz / Mn of 3.80 or more.   The acetaldehyde content of 15 ppm or less, cyclic trimer content of 0.70% or less, haze of 5.0% or less, and dispersion of molecular weight distribution obtained by the production method according to claim 8 or 9. Ratio polyester Mz / Mn is 3.80 or more.

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