JP2003147065A - Method for producing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester giving a molded article containing little bubbles and fish eyes, having good controllability of crystallization and having excellent transparency without staining the mold in molding. SOLUTION: A polyethylene naphthalate produced by melt polymerization is extruded in the form of a strand, solidified by cooling and cut in the form of chips under a condition satisfying the formula: 0.02<=(V1/S1)×t1×ΔT<=1.00 (Tg, Text and T are the glass transition temperature ( deg.C) of the polyester, the temperature ( deg.C) of the polyester extruded through a die head in the form of strand and the temperature ( deg.C) of the cooling water, respectively; and V1, S1 and T1 are the quantity of the cooling water per unit time (cm<3> /sec) in and before the cutting step of the strand, the surface area (cm<2> /sec) of the strand contacting with the cooling water and the contacting time (sec) of the strand with the cooling water, respectively).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyester used for forming films, sheets, etc., including bottles, and more specifically, it is excellent in heat resistance, aroma retaining property and gas barrier property, and moreover is a molded product. The present invention relates to a method for producing a polyester, in which bubbles and fish eyes are unlikely to occur therein, the crystallization controllability of a molded product is excellent, and mold stains are less likely to occur during molding.

[0002]

BACKGROUND OF THE INVENTION Polyester such as polyethylene terephthalate has high mechanical value and high industrial value because it has excellent mechanical properties and chemical properties.
Widely used as bottles. As a material for containers such as seasonings, oils, beverages, cosmetics, and detergents, various resins are adopted depending on the type of filling contents and the purpose of use, and among these, polyester has mechanical strength and heat resistance. Since it has excellent properties, transparency and gas barrier property, it is particularly used as a material for a beverage filling container such as juice, soft drink, carbonated drink and the like. Such polyester is supplied to a molding machine such as an injection molding machine to mold a preform for a hollow molded body, and the preform is inserted into a mold having a predetermined shape and stretch blow molded, and then, if necessary, a bottle It is general that the body is heat-treated (heat-set) to be molded into a hollow molded container, and further the mouth of the bottle is heat-treated (crystallization of the mouth) if necessary.

However, in recent years, the size and weight of containers have been reduced, and at the same time, it is necessary to withstand the temperature of the container at 60 to 70 ° C. for a long time with an automatic vending machine or a hot warmer. Materials such as containers for foods whose flavor is deteriorated by a small amount of oxygen are required to have properties superior to those of polyethylene terephthalate resin containers in terms of heat resistance and gas barrier properties. It's starting to happen.

In order to meet such demands, it has been considered to use polyethylene naphthalate, which is superior in heat resistance and gas barrier property, to containers and the like as compared with polyethylene terephthalate. JP-A-52-45466 describes a hollow container made of polyethylene naphthalate, which is excellent in heat resistance and gas barrier property. Further, in JP-A-2-217222, the stretching index is 130 cm.
Above, a highly stretched polyethylene naphthalate bottle and a method for producing the same are described. However, in the case of polyethylene naphthalate resin, it is difficult to mold, and a hollow molded body having excellent transparency and a uniform wall thickness distribution has not been obtained.

Further, in JP-A-64-85732, 2,6-naphthalene-dicarboxylic acid components 65 to 98.5 are disclosed.
Polyethylene naphthale containing mol% and other dicarboxylic acid components (terephthalic acid, isophthalic acid, etc.) 35 to 1.5 mol% and ethylene glycol as a main glycol component
A heat resistant bottle made from a Toco-based polymer is described.

However, when the content of the third component is 10 mol% or more, the melt-polymerized resin does not exhibit a melting point, and the crystallization rate is extremely slow, which makes crystallization impossible under practical conditions.
For this reason, it is impossible to carry out a drying treatment or a solid-state polymerization treatment for the purpose of increasing the molecular weight and decreasing the acetaldehyde (AA) content.

Further, when the polyester obtained by the conventional melt polymerization is made into chips, continuous chips such as twins and triplets are generated, a large amount of fine particles (fine polyester powder) are generated, and highly oriented crystals due to shearing. There was a problem such as the occurrence of a ghost area. When injection molding is performed using polyester such as twins or triplets in which continuous chips are mixed, there is a problem that air is trapped and bubbles remain in the preform and the bottle.

Further, if there is a highly crystallized region due to oriented crystallization in the polyester chip, when the preform is melt-molded by injection molding, melting of the highly crystallized region is likely to be incomplete, which causes incompleteness. Crystallization occurs from the melting region as the starting point, the transparency of the preform is reduced, and the crystallization is promoted during stretch blow molding to cause the bottle to become hazy, and the unmelted substance remains as a gel-like foreign substance, There was a problem that the appearance of the bottle was impaired. In addition, the crystallization characteristics of the preform change, the shrinkage amount of the plug portion changes during crystallization of the mouth portion, the dimension of the mouth plug portion after crystallization changes, and problems such as poor capping or poor sealing occur.

In order to completely melt the highly crystalline portion of the polyester chip, melt molding at a higher temperature is required, but under the high temperature melting condition, the polyester is thermally decomposed, resulting in deterioration of bottle strength and poor stretchability. It is not preferable because it causes a decrease in the molecular weight and leads to an increase in by-products such as acetaldehyde, which adversely affects the flavor property.

Further, the conventional polyester contains oligomers such as cyclic trimers, and the oligomers adhered to the inner surface of the mold, the gas exhaust port of the mold, and the exhaust pipe. It was easy for stains to occur.

Such mold stains cause roughening of the surface of the obtained bottle and whitening. If the bottle becomes white, the commercial value of the bottle decreases and it must be discarded. For this reason, the mold stains must be frequently removed, and there is a problem that the productivity of the bottle is reduced.

As a solution to these problems, Japanese Patent Laid-Open No. 10-1
Japanese Patent No. 14819 discloses a method of treating polyester with water.

However, at the stage of water treatment, fines (fine resin powder) adhering to the polyester chips are suspended and settled in the treated water, adhering to the treatment tank wall or the pipe wall to clog the pipe, or the treatment. Problems such as making cleaning of tanks and piping difficult occur.

Further, the fine particles floating on the treated water and settling and adhering to the wall of the treating tank or the pipe wall are reattached to the polyester chips to promote crystallization at the time of molding, resulting in a poorly transparent bottle and a mouth. The problem of capping failure due to the large shrinkage of the spout due to crystallization of the spigot occurred.

[0015]

DISCLOSURE OF THE INVENTION The present invention is excellent in heat resistance, aroma retaining property, gas barrier property and chemical resistance, is less likely to cause bubbles and fisheyes in a molded product, and has excellent crystallization controllability of the molded product. It is an object of the present invention to provide a method for producing a polyester which is excellent in transparency of a molded product such as a bottle and which is less likely to cause mold stains during molding.

[0016]

Means for Solving the Problems In order to achieve the above object, a method for producing a polyester according to the present invention comprises discharging a polyester obtained by melt polymerization in a strand form from a die head, cooling and solidifying and cutting into a chip form. A method for producing a polyester, characterized in that the polyester is cut into chips under the conditions that satisfy the following formula (1). 0.02 ≦ (V1 / S1) × t1 × ΔT ≦ 1.00 (1) Formula where ΔT = (Tg−T) / (Text−T) Tg = polyester glass transition temperature (° C.) ) Text = temperature (° C) when polyester is discharged in a strand form from the die head T = average cooling water temperature (° C) (where T is 20 ≤ T
≦ 95 (° C.) and T <Tg are satisfied. ) V1 = amount of cooling water per unit time in the process until the strand is cut into chips (cm ³ / sec) S1 = cooling per unit time in the process until the strand is cut into chips Surface area of strand in contact with water (cm ² / sec) t1 = time (sec) during which strand is in contact with cooling water in the process until the strand is cut into chips

In this case, after cutting the polyester obtained by melt polymerization into chips, the cut chips can be cooled under the condition that the following formula (2) is satisfied. 0.20 ≦ (V2 / S2) × t2 × ΔT Equation (2) where ΔT = (Tg−T) / (Text−T) V2 = after the strand is cut into chips To the amount of cooling water per unit time in the process from the separation of chips to cooling water (cm ³ / sec) S2 = from the cutting of the strands into chips and the separation of the cooling water from the chips Surface area of the chip (cm ² / se) in contact with cooling water per unit time in the process
c) t2 = the time (sec) during which the chips are in contact with the cooling water in the process from the cutting of the strand into chips and the separation of the chips from the cooling water.

In this case, the cooling water has a particle size of 1 to 25.
In the case of containing 50000 particles / 10 μm or less and the sodium content, magnesium content, silicon content and calcium content being N, M, S and C, respectively, the following (3) to ( It is possible to use water which satisfies at least one of the equations 6). N ≦ 1.0 (ppm) ··· (3) Formula M ≦ 0.5 (ppm) ··· (4) Formula S ≦ 2.0 (ppm) ···・ ・ ・ Equation (5) C ≦ 1.0 (ppm) ・ ・ ・ Equation (6)

In this case, at least a part of the cooling water can be repeatedly used.

In this case, (1) the melt-polymerized polyester is discharged in a strand form from the die head, and (2)
The strand is cooled with water in the strand guide section, (3) the strand is cut into chips in the presence of cooling water, (4) the cut chips are further water-cooled in a cooling pipe, and (5) by a dehydrator. Cooling water and chips can be separated.

In this case, the polyester can be crystallized and subjected to solid phase polymerization treatment.

In this case, the polyester and the treated water can be supplied to the treatment tank for water treatment of the polyester.

When the polyester is treated with water in the treatment tank, the number of particles having a particle size of 1 to 25 μm existing in the treated water discharged together with the polyester from the treatment tank is X, the sodium content is N, and the magnesium content is magnesium. When the content of is M, the content of calcium is C, and the content of silicon is S,
Water treatment can be performed by satisfying at least one of the following (7) to (11). 1 ≤ X ≤ 50,000 (pieces / 10 ml) ... (7) Formula 0.005 ≤ N ≤ 1.0 (ppm) ... (8) Formula 0.01 ≤ M ≤ 0.5 (ppm) ・ ・-Equation (9) 0.01 ≤ C ≤ 1.0 (ppm) ... (10) Equation 0.01 ≤ S ≤ 2.0 (ppm) ... (11) Equation

In this case, the polyester can be a polyalkylene naphthalate.

In this case, the main repeating unit of the polyester is composed of ethylene naphthalate, and the intrinsic viscosity of the polyester can be 0.45 to 1.6 dl / g.

According to the method for producing polyester of the present invention, bubbles and fish eyes are less likely to be generated in the preform and the bottle, the transparency of the bottle and the crystallization of the plug portion are improved, and the water content of the polyester chip is improved. When the treatment is carried out, the contamination of the treatment tank and the pipe can be reduced, and further, the polyester which is unlikely to cause the die contamination during molding of a bottle or the like can be advantageously produced.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used in the present invention is preferably a polyester whose main repeating unit is composed of ethylene naphthalate, and more preferably a linear polyester containing 85 mol% or more of ethylene naphthalate units. Particularly preferred is a linear polyester containing 95 mol% or more of ethylene naphthalate units.

The dicarboxylic acid used by copolymerization in the polyester is an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid or diphenoxyethanedicarboxylic acid and its functional Derivatives, oxyacids such as p-oxybenzoic acid and oxycaproic acid and functional derivatives thereof, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid and glutaric acid and functional derivatives thereof, and fats such as cyclohexanedicarboxylic acid Examples thereof include cyclic dicarboxylic acids and their functional derivatives.

As glycols used by copolymerizing in the above polyester, aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenol A, Examples thereof include aromatic glycols such as alkylene oxide adducts of bisphenol A.

Further, as the other copolymerization component composed of the polyfunctional compound in the polyester, trimellitic acid, pyromellitic acid and the like can be mentioned as the acid component, and glycerin and pentaerythritol can be mentioned as the glycol component. You can The amount of the above copolymerization component used should be such that the polyester maintains a substantially linear shape.

Further, the intrinsic viscosity of the polyester according to the present invention, particularly the polyester whose main repeating unit is ethylene naphthalate, is 0.45 to 1.60 dl /
g, preferably 0.60 to 1.30 dl / g, and more preferably 0.65 to 0.90 dl / g. When the intrinsic viscosity is less than 0.45 dl / g, the mechanical properties of the obtained molded product and the like are poor. On the other hand, when it exceeds 1.60 dl / g, the resin temperature becomes high during melting by a molding machine or the like, and thermal decomposition becomes severe, and free low-molecular weight compounds that affect aroma retention increase, or the molded product becomes Problems such as yellow coloring occur.

The shape of the polyester chip may be any of cylinder type, square type, flat plate type, etc., and the size thereof is usually 1.5 to 4 mm in length, width and height.
Is the range. For example, in the case of a cylinder type, it is practical that the length is 1.5 to 4 mm and the diameter is about 1.5 to 4 mm.

The acetaldehyde content of the polyester used in the present invention is 20 ppm or less, preferably 1
It is 0 ppm or less, more preferably 5 ppm or less. The method for reducing the acetaldehyde content of the polyester used in the present invention to 20 ppm or less is not particularly limited, but for example, low molecular weight polyester is subjected to solid phase polymerization at a temperature of 170 to 250 ° C. under reduced pressure or in an inert gas atmosphere. You can list the method to do.

Further, the amount of diethylene glycol in the polyester used in the present invention is 1.0 to 1.0 of the glycol component.
The amount is 5.0 mol%, preferably 1.3 to 4.5 mol%, more preferably 1.5 to 4.0 mol%. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the molecular weight is greatly decreased during molding, and the acetaldehyde content is increased, which is not preferable.

The content of the cyclic trimer of the polyester used in the present invention is 0.50% by weight or less, preferably 0.45% by weight or less, more preferably 0.40% by weight.
It is the following. When a heat-resistant hollow molded article or the like is molded from the polyester of the present invention, heat treatment is performed in a heating mold,
When the content of the cyclic trimer is 0.50% by weight or more, the adhesion of the oligomer to the surface of the heating mold rapidly increases, and the transparency of the obtained hollow molded product is extremely deteriorated.

The above polyester can be produced by a conventionally known production method. That is, a direct esterification method in which naphthalenedicarboxylic acid and ethylene glycol and optionally other copolymerization components are directly reacted to distill off water to esterify, and then polycondensate under reduced pressure, or
It is produced by a transesterification method in which dimethyl naphthalenedicarboxylate, ethylene glycol and, if necessary, other copolymerization components are reacted to distill off methyl alcohol for transesterification, and then polycondensation is performed under reduced pressure. Further, solid phase polymerization may be carried out in order to increase the intrinsic viscosity and decrease the acetaldehyde content and the like.

The melt polycondensation reaction may be carried out in a batch reaction apparatus or a continuous reaction apparatus.
In any of these methods, the melt polycondensation reaction may be carried out in one step or may be carried out in multiple steps. The solid phase polymerization reaction can be carried out by a batch type apparatus or a continuous type apparatus as in the melt polycondensation reaction. The melt polycondensation and solid phase polymerization may be carried out continuously or may be carried out separately.

In the case of the direct esterification method, at least one of Ge, Sb, Ti or Al compounds is used as the polycondensation catalyst. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like.

Further, transesterification catalysts by the transesterification method include Zn, Cd, Mg, Mn, Co, Ca and B.
A fatty acid salt such as a, carbonate, Pb, Zn, Sb, Ge oxide or the like is used. The polycondensation reaction uses G as a polycondensation catalyst.
At least one of the compounds of e, Sb, Ti, or Al is used. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like.

As the Ge compound, amorphous germanium dioxide, crystalline germanium dioxide powder or a slurry of ethylene glycol, a solution of crystalline germanium dioxide dissolved in water by heating, or ethylene glycol added thereto and heat treated A solution obtained by heating and dissolving germanium dioxide in water or an ethylene glycol-containing solution is used to obtain the polyester used in the present invention.
It is preferable to use a solution which has been heated by adding a solvent. These polycondensation catalysts can be added during the esterification process. When a Ge compound is used, the amount used is 10 to 150 ppm, preferably 13 to 100 ppm, and more preferably 15 to 70 p, as the Ge residual amount in the produced polymer.
pm.

Examples of the Ti compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate and tetra-n-butyl titanate, and their partial hydrolysis. Examples thereof include titanyl oxalate, titanyl ammonium oxalate, sodium titanyl oxalate, potassium titanyl oxalate, calcium titanyl oxalate, titanyl oxalate compounds such as strontium titanyl oxalate, titanium trimellitate, titanium sulfate, titanium chloride and the like. The Ti compound is a formed polymer.
It is added so that the remaining amount of Ti in it is in the range of 0.1 to 10 ppm.

As the Sb compound, antimony trioxide,
Antimony acetate, antimony tartrate, potassium antimony tartrate, antimony oxychloride, antimony glycolate
, Antimony pentoxide, triphenylantimony, and the like. The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 350 ppm. The residual amount of Sb in the produced polymer is preferably 80-
300 ppm, more preferably 100 ppm-250
Add so that it is in the ppm range. If it is less than the lower limit of the above range, the polycondensation rate becomes slow and not suitable for practical production, and if it exceeds the upper limit, it is not preferable from the viewpoint of hygiene, and the residual antinemon in the produced polymer is crystallized. It may serve as a core material and reduce the transparency of the molded product.

As the Al compound, specifically,
Aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, aluminum lactate,
Carboxylates such as aluminum citrate and aluminum salicylate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, polyaluminum chloride,
Inorganic acid salts such as aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, aluminum phosphonate, aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide, aluminum n-butoxide, aluminum t-butoxide, etc. Aluminum chelate compounds such as aluminum alkoxide, aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum and other organoaluminum compounds and their partial hydrolysates. , Aluminum oxide and the like. Among these, carboxylates, inorganic acid salts and chelate compounds are preferable, and among these, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferable. The Al compound is added so that the amount of Al remaining in the produced polymer is in the range of 5 to 200 ppm.

In the case of an Al compound, an alkali metal compound or an alkaline earth metal compound may be used together. Alkali metals and alkaline earth metals include Li,
Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba
Preferably at least one selected from
It is more preferable to use an alkali metal or a compound thereof.
When an alkali metal or its compound is used, especially L
The use of i, Na, K is preferred. Examples of the alkali metal or alkaline earth metal compound include, for example, saturated aliphatic carboxylic acid salts such as formic acid, acetic acid, propionic acid, butyric acid and oxalic acid, and unsaturated aliphatic carboxylic acid salts such as acrylic acid and methacrylic acid. Aromatic carboxylic acid salts such as benzoic acid, halogen-containing carboxylic acid salts such as trichloroacetic acid,
Hydroxycarboxylic acid salts such as lactic acid, citric acid, salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, hydrogen phosphate, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid,
Hydrobromic acid, chloric acid, inorganic acid salts such as bromic acid, 1-propanesulfonic acid, 1-pentanesulfonic acid, organic sulfonic acid salts such as naphthalenesulfonic acid, organic sulfates such as lauryl sulfuric acid, methoxy, ethoxy, n-propoxy,
Examples thereof include alkoxides such as iso-propoxy, n-butoxy and tert-butoxy, chelate compounds with acetylacetonate, hydrides, oxides and hydroxides. The above-mentioned 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 the 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.

Various P compounds can be used as stabilizers. Examples of the P compound used in the present invention include phosphoric acid, phosphorous acid and their derivatives. 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, trimethyl phosphite, triethyl phosphite, tributyl phosphite, 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, which may be used alone or in combination of two or more. You may use together. P compound is 1 to 1 as the residual amount of P in the produced polymer.
It can be added at any stage of the above-mentioned polyester formation reaction step so that it is in the range of 1000 ppm.

As the stabilizer, it is preferable to use phosphoric acid, polyphosphoric acid, phosphoric acid esters such as trimethyl phosphate, and the like. These stabilizers can be added during the esterification reaction step from a slurry preparation tank of naphthalenedicarboxylic acid and ethylene glycol.

In order to control the DEG content in the polyester, a basic compound is used in the esterification step, for example, a tertiary amine such as triethylamine or tri-n-butylamine,
A quaternary ammonium salt such as tetraethylammonium hydroxide can be added.

The melt-polymerized polyester thus obtained is discharged in a strand form from a die head connected to a polycondensation reaction can, cooled and solidified, and then the strand is cut to produce a chip.

However, in the conventional method of forming a melt-polymerized polyester into chips, the formation of continuous chips such as twins and triplets and the generation of fine particles, and the generation of highly oriented crystallization regions due to shear in the fine particles and chips are caused. There was a problem.

When injection molding is performed by using polyester in which continuous chips such as twins and triplets are mixed, there is a problem that air is trapped and bubbles remain in the preform and the bottle.

Further, if there is a highly crystallized region in the polyester chip or finely oriented crystallized, when the preform is melt-molded by injection molding, the high-crystallized region is likely to be incompletely melted, which causes Crystallization occurs from the complete melting region as the starting point, the transparency of the preform is reduced, the crystallization is promoted during stretch blow molding, and the bottle becomes hazy. In some cases, there was a problem that the appearance of the bottle was impaired. In addition, the crystallization characteristics of the preform change, the shrinkage amount of the plug portion changes during crystallization of the mouth portion, the dimension of the mouth plug portion after crystallization changes, and problems such as poor capping or poor sealing occur.

In order to completely melt the highly crystallized polyester, melt molding at a higher temperature and a higher back pressure is required, but under such a condition, the polyester undergoes thermal decomposition, resulting in deterioration of bottle strength and stretching. It is not preferable because it causes a decrease in molecular weight leading to poor sex and an increase in by-products such as acetaldehyde which adversely affects the flavor property.

As a result of extensive studies to solve such problems, the present invention has been achieved. That is, the present invention is a method for producing a polyester in which a polyester obtained by melt polymerization is discharged in a strand form from a die head, cooled and solidified, and then cut into chips, under the condition that the following formula (1) is satisfied. The above-mentioned problems are solved by cutting into a shape. 0.02 ≦ (V1 / S1) × t1 × ΔT ≦ 1.00 (1) Formula where ΔT = (Tg−T) / (Text−T) Tg = polyester glass transition temperature (° C.) ) Text = temperature (° C) when polyester is discharged in a strand form from the die head T = average cooling water temperature (° C) (where T is 20 ≤ T
≦ 95 (° C.) and T <Tg are satisfied. ) V1 = amount of cooling water per unit time in the process until the strand is cut into chips (cm ³ / sec) S1 = cooling per unit time in the process until the strand is cut into chips Surface area of strand in contact with water (cm ² / sec) t1 = time (sec) during which strand is in contact with cooling water in the process until the strand is cut into chips

In the formula (1), if the lower limit is not satisfied, there is a problem such as poor cutting due to insufficient cooling of strands, chip fusion, and if the upper limit is exceeded, fine particles such as fine powder due to overcooling. Is not preferable in terms of the occurrence of the problem, the high orientation of the cut surface, and the energy cost.

Further, in this case, after cutting the polyester obtained by the melt polymerization into chips, it is desirable to cool the chips under conditions satisfying the following formula (2). 0.20 ≦ (V2 / S2) × t2 × ΔT Equation (2) where ΔT = (Tg−T) / (Text−T) V2 = after the strand is cut into chips To the amount of cooling water per unit time in the process from the separation of chips to cooling water (cm ³ / sec) S2 = from the cutting of the strands into chips and the separation of the cooling water from the chips Surface area of the chip (cm ² / se) in contact with cooling water per unit time in the process
c) t2 = the time (sec) during which the chips are in contact with the cooling water in the process from the cutting of the strand into chips and the separation of the chips from the cooling water.

When the value goes below the lower limit in the equation (2), the cut chips tend to be insufficiently cooled, which is not preferable. In formula (2), there is no particular upper limit, but (V2
/ S2) × t2 × ΔT ≦ 35 is not preferable in terms of energy cost and is not very practical.

The discharge temperature (Text) of the melt-polymerized polyester from the die head is Tm + 10≤Text≤Tm + 65 ° C, preferably Tm + 20≤Text≤Tm + 45 (° C), more preferably Tm + 25≤Text≤Tm + 35, with respect to the melting point Tm of the polyester. It is desirable to use the range of (° C). The extrusion temperature Text for the polyester in which the main repeating unit according to the present invention is ethylene naphthalate is preferably 260 to 260.
It is extruded in strands at 320 ° C, more preferably 275-305 ° C.

In general, the strands are cooled by a space provided between the die head and the water cooling device, so that the molten polyester is once air-cooled and then enters the water cooling device. The air cooling time is generally a few seconds or less. A cooling device for water-cooling the strands is cooled by cooling water while the strands move horizontally, vertically, or obliquely downward. The cooling water may be brought into contact with a strand to be cooled in the form of a shower or mist, or may be cooled by immersing the strand in the cooling water stored in the water tank. The strands may be cooled individually or in combination.

Desirably, the method for cooling the strand is
Cooling water that flows along the inclined strand cooling plate installed below the die head (hereinafter referred to as slide water) and cooling water that flows in a shower shape from the direction perpendicular to the plate inclination (hereinafter referred to as shower water) Etc. to cool the strands.

As a method of cutting the cooled strand into chips, a known cutter can be used to cut into chips, but it is desirable to perform the cutting in the presence of cooling water. In the present invention, since it is necessary to cut the strand without overcooling in order to reduce the shear orientation at the time of cutting the strand, it is convenient to prevent the cut chips from adhering to each other.

Immediately before cutting the strand with a cutter, cooling water (hereinafter referred to as "conveyor water") is further added to the cutter portion, and the cutting water is sent to the dehydrator as a cooling and moving medium for cooling and discharging. After doing
A method of separating cooling water and chips with a dehydrator is desirable.

That is, in the present invention, the polyester obtained by melt polymerization is discharged from the die head in a strand form, cooled and solidified, and then cut into chips to produce chips. Die head for discharging in a uniform shape, (2) strand guide section for cooling strands, (3) cutter for cutting strands into chips in the presence of cooling water (4)
It is preferable to use a cooling pipe for discharging the cut chips to the dehydrator while further cooling them with water, and (5) a dehydrator for separating the cooling water and the chips.

As a condition for cooling the strands and cutting them into chips, the average temperature T of the cooling water is basically required to be lower than the glass transition temperature Tg of polyester, and 20 ° C. ≦ T ≦ 95. ° C and 25 ° C ≤ Tg-T ≤ 1
It is desirable to always keep constant in the range of 00 ° C, and more preferably 40 ° C ≤ T ≤ 90 ° C, 30 ° C ≤ Tg-T ≤ 80.
It is preferably in the range of ° C.

Further, the glass transition temperature Tg (° C.) of the polyester, the polyester when extruded from the die head, varies depending on the conditions such as the glass transition temperature of the melt-polymerized polyester, the extrusion temperature, the surface area of the strand, the supply amount of cooling water and the cooling time. Temperature Text (° C), average cooling water temperature T
(0 ° C.), ΔT = (Tg−T) / (Text−T), 0.10 ≦ ΔT ≦ 0.35. It is desirable to set 0.15 ≦ ΔT ≦ 0.30.

The glass transition temperature Tg of the polyester and the extrusion temperature Tex of the melt-polymerized polyester from the die head.
When the cooling water temperature T is too high with respect to t, the strands are insufficiently cooled, the tackiness of the strands is increased, and the strands are fused to the blade of the cutter and cannot be cut. After cutting into chips, there is a problem that the chips are fused and formed into a series of twin or triple chips.

On the other hand, the glass transition temperature Tg of polyester
Extrusion Temperature Te of Molten Polyester from Mold and Die Head
When the cooling water temperature T is extremely low with respect to xt,
Not only the energy cost required to lower the cooling water temperature becomes high, but also the surface layer becomes too hard and a lot of fines are generated during cutting.

The fine particles may be highly crystallized and have a higher melting point than ordinary chips in the crystallization step and the solid phase polymerization step after forming the chips into strands. Such fines are less likely to melt than regular chips. When such fines are contained in a large amount in ordinary chips, for example, fines that are difficult to be completely melted during the melt molding of bottle preforms and hollow molded bodies become crystal nucleating agents to increase the crystallization speed of molded products. There is a problem that the molded product is crystallized and becomes turbid in white, and when the preform temperature is raised to a stretchable temperature range during stretch blow, crystallization occurs and the bottle is whitened. In addition, as an unmelted material, it becomes a gel-like defect and deteriorates the appearance.

Further, when the powder is brought into the water treatment tank after the solid-state polymerization, the powder has a large surface area, so that a small amount of an organic substance or an inorganic substance which can be a crystal nucleating agent contained in the treated water is adsorbed and the concentration is high. Concentrate to. When such fines are contained in a large amount in ordinary chips, for example, they act as a crystal nucleating agent during the melt molding of bottle preforms and hollow molded articles to accelerate the crystallization rate of the molded articles and crystallize the molded articles. There is a problem that the bottle becomes cloudy and crystallization occurs when the preform temperature is raised to a stretchable temperature range during stretch-blowing to cause whitening of the bottle.

When the hardened strands are cut with a cutter, shearing of the cut surface increases the degree to which the polyester molecular chains cause crystallization due to orientation. The cut surface in which the oriented crystallization becomes strong is more likely to hinder the thermal crystallization of the polyester molecular chain even when heated, as compared with the other parts of the chip which are amorphous. Therefore, thermal crystallization is hindered in the crystallization process, the crystallization process and the solid-state polymerization process, and the crystallinity of the cut surface tends to be slightly smaller than that of other parts of the chip.

In general, a chip having a low crystallinity tends to be completely melted as compared with a polyester chip having a high crystallinity. However, even if the degree of crystallinity due to thermal crystallization is low, the cut surface of the chip where crystallization due to orientation is progressing is
It is more difficult to melt than other parts. Therefore, when the preform for a hollow molded body is melt-molded, the cut surface of the chip is less likely to be melted than other portions, which causes problems such as a decrease in transparency of the preform due to incomplete melting.

The amount of cooling water for the strand varies depending on conditions such as the glass transition temperature of the melt-polymerized polyester, the extrusion temperature, the average water temperature of cooling water, and the cooling time. The amount of cooling water for cooling the strand (sliding table water, shower water) is Regarding the cooling water supply amount V1 (cm ³ ) with respect to the cooling water contact area S1 (cm 2) of the strand per unit time, 0.2 ≦ (V 1
/S1)≦3.0, preferably 0.5 ≦ (V1 / S
1) It is desirable to use ≦ 2.0.

If the amount of cooling water is less than the above range, the cooling water temperature is likely to rise due to the amount of heat received from the strands, stable cooling cannot be performed, and the strands become more sticky due to insufficient cooling of the strands. Problems tend to occur such that the strands are fused to the blade of the cutter and become uncuttable, or the strands are cut into chips and the chips are fused to each other to form a series of twin or triplet chips.

On the other hand, when the amount of cooling water is larger than the above range, the energy cost required to lower the cooling water temperature becomes high, which is a practical problem.

After cutting the strand into chips with a cutter, the chips are subsequently cooled with water (conveyor water).
As a condition for adding chips to discharge the chips to the cooling / dehydrating machine, the average temperature T of the cooling water is basically required to be lower than the glass transition temperature Tg of polyester.
It is desirable to always keep constant in the range of ℃ ≤ T ≤ 95 ℃ and 35 ℃ ≤ Tg-T ≤ 100 ℃, more preferably 50
It is desirable that the temperature ranges are C ≦ T ≦ 85 ° C. and 45 ° C. ≦ Tg−T ≦ 70 ° C.

Further, the glass transition temperature Tg (° C.) of the polyester and the polyester temperature Text at the time of extrusion from the die head are different depending on the conditions such as the glass transition temperature of the melt-polymerized polyester, the extrusion temperature, the strand surface area, the cooling water amount and the cooling time. (° C), average cooling water temperature T (° C),
When ΔT = (Tg−T) / (Text−T), 0.10 ≦ ΔT ≦ 1.0. Preferably 0.15 ≦
It is desirable that ΔT ≦ 0.75.

Glass transition temperature Tg of polyester and extrusion temperature Tex of melt-polymerized polyester from the die head
If the cooling water temperature T is too high with respect to t, the cooling of the chips becomes insufficient, the adhesiveness of the chips becomes high, and the chips are fused to form a continuous chip such as twins or triplets. Such problems may occur.

On the other hand, the glass transition temperature Tg of polyester
Extrusion Temperature Te of Molten Polyester from Mold and Die Head
When the cooling water temperature T is extremely low with respect to xt, the energy cost required to lower the cooling water temperature becomes high.

The amount of cooling water for the chips varies depending on conditions such as the glass transition temperature of the melt-polymerized polyester, the extrusion temperature, the average water temperature of the cooling water, and the cooling time, but the amount of cooling water for cooling the chips (slide water, shower water, Conveyor water) is the cooling water contact area S2 (cm ² ) of the strand per unit time
Cooling water amount V2 (0.2 ≦ (V2 / S for cm ³
2) ≦ 3.0, preferably 0.5 ≦ (V2 / S2) ≦
It is desirable to use 2.5.

When the amount of cooling water is less than the above range, the cooling water temperature easily rises due to the amount of heat received from the strands and chips, and stable cooling cannot be achieved. Due to insufficient cooling, the chips are fused and twins, triplets It is easy to have problems such as a series of chips like.

On the other hand, when the amount of cooling water is larger than the above range, the energy cost required to lower the cooling water temperature becomes high, which is a practical problem.

With respect to the cooling time, the cooling time t1 for cooling the strand, that is, the time t1 for contacting the strand with cooling water is the glass transition temperature of polyester, the polyester extrusion temperature from the die head, the average temperature of cooling water, the cooling water amount, Depending on the surface area of the strand,
It is suitable that the time is 0.1 to 10 seconds, preferably 0.1 to 5 seconds. Further, the cooling time t2 after cutting the strands into chips, that is, the time for contacting the chips with cooling water also varies depending on conditions such as the polyester glass transition temperature, but is preferably 3 to 120 seconds. It is preferably 5 to 60 seconds. If the cooling time is too short for each of t1 and t2, the strands and chips cannot be sufficiently cooled, and if the cooling time is long, it is not practical because the cooling / cooling device itself needs to be large. Further, especially at t1, the generation of powder due to supercooling,
Problems that cause highly oriented cut surfaces are likely to occur.

As the cooling water used for cooling the strand, a new cooling water may be used at all times, or a method of circulating a small amount of the cooling water may be used. Generally, natural water (industrial water) is used because of the large amount of water used for treatment.
Often, at least a part of the above is used by recycling.
Usually, this natural water is taken from river water, groundwater, etc., and is said to have undergone treatment such as sterilization and removal of foreign substances without changing the shape of water (liquid).

Natural water generally used for industrial use contains a large amount of metal-containing substances such as sodium, magnesium, calcium and silicon. When water treatment is carried out using natural water, it adheres to and permeates the polyester chips to form crystal nuclei, and the transparency of the hollow molded container using such polyester chips becomes extremely poor. Therefore, it is desirable to treat these natural waters with an ion exchange device or the like to use water having a reduced content of the metal-containing substance.

When the quality of the cooling water used in the step of forming chips immediately after the melt polycondensation of polyester is poor as described above, only molded articles such as bottles having poor transparency can be obtained.

In the present invention, in the chip forming step after melt polycondensation, particles having a particle size of 1 to 25 μm are 50,000 particles / 10 m.
It is desirable to water-treat the chipped polyester while cooling with water containing 1 or less. Particle size in cooling water 1
The number of particles of up to 25 μm is preferably 10,000 particles / 1
It is 0 ml or less, more preferably 1000 pieces / 10 ml or less. The number of particles having a particle size of more than 25 μm in the treated water is not particularly specified, but preferably 2000 particles / 1
0 ml or less, more preferably 500 pieces / 10 ml or less,
It is more preferably 100 pieces / 10 ml, and particularly preferably 10 pieces / 10 ml or less.

The particles having a particle size of less than 1 μm in the treated water are not particularly specified in the present invention, but the smaller amount is preferable in order to obtain a transparent resin or a resin having an appropriate crystallization rate. The number of particles having a particle size of less than 1 μm is preferably 100,000 particles / 10 ml or less, more preferably 50,000 particles / 10 ml or less, and further preferably 200.
00 pieces / 10 ml or less, particularly preferably 10,000 pieces /
It is 10 ml or less. As a method for removing and controlling particles having a size of 1 μm or less from water, a microfiltration method or an ultrafiltration method using a membrane such as a ceramic membrane or an organic membrane can be used.

As a method for reducing the number of particles in water to 50,000 particles / 10 ml or less, an apparatus for removing particles is installed at at least one place until natural water such as industrial water is supplied to the chip forming step. Preferably, a device for removing particles is installed from the natural water sampling port to the chipping step, and the content of particles having a particle size of 1 to 25 μm in the water supplied to the chipping step is 50,000. / 10 ml
The following is preferable.

Examples of the device for removing particles include a filter filtration device, a membrane filtration device, a settling tank, a centrifuge, and a foam entrainment processor. For example, in the case of a filter filtration device, examples thereof include a belt filter system, a bag filter system, a cartridge filter system, a centrifugal filtration system and the like.

Among them, the belt filter type, centrifugal filtration type and bag filter type filtration devices are suitable for continuous operation. Further, in the case of a belt filter type filtering device, examples of the filter material include paper, metal, cloth and the like. Further, the size of the mesh of the filter is from 5 to 100 μm, preferably from 10 to 10 in order to efficiently remove the particles and to flow the treated water.
70 μm, and more preferably 15 to 40 μm.

When the sodium content, the magnesium content, the silicon content and the calcium content in the cooling water in the chip forming process are N, M, S and C, respectively,
The above problem is solved by satisfying at least one, and preferably all of the following expressions (4) to (7). N ≦ 1.0 (ppm) ・ ・ ・ Equation (4) M ≦ 0.5 (ppm) ・ ・ ・ Equation (5) S ≦ 2.0 ( ppm) ・ ・ ・ ・ ・ ・ ・ ・ Equation (6) C ≦ 1.0 (ppm) ・ ・ ・ ・ ・ ・ ・ ・ Equation (7)

By setting the contents of sodium, magnesium, calcium, and silicon in the chip cooling water in the above range, the chips adhere to and permeate the polyester chips, promote crystallization during molding, and have poor transparency. Can be prevented.

Chips obtained by cooling and cutting the strands from the melt-polymerized polyester as described above are crystallized and solid-phase polymerized by a known method, if necessary, to increase the molecular weight of the polyester and reduce acetaldehyde. And reduction of oligomers may be performed.

In particular, regarding the polyester obtained by using at least a Ge catalyst as the polycondensation catalyst, oligomers such as cyclic trimers are attached to the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. In order to prevent the die from becoming dirty, the chips after melt polymerization obtained as described above,
Further, the chips after crystallization or the chips after solid phase polymerization may be further subjected to contact treatment with water.

As a method of contact treatment with water, a method of immersing in water can be mentioned. The time for contact treatment with water is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the temperature of water is 20 to 180 ° C., preferably 40 to 150. C., more preferably 50 to 120.degree.

The treatment method may be either a continuous system or a batch system, but the continuous system is preferred for industrial use.

Regardless of whether the water treatment method is continuous or batchwise, if all or most of the treated water discharged from the treatment tank is treated as industrial wastewater, a large amount of new water will be required. Not only that, but there is concern that the increase in the amount of wastewater will affect the environment.

That is, by returning at least a part of the treated water discharged from the treatment tank to the water treatment tank and reusing it,
The amount of water required can be reduced, the impact on the environment due to an increase in the amount of wastewater can be reduced, and if the temperature of the wastewater returned to the water treatment tank maintains a certain level, the heating amount of the treated water can be reduced. The treated water discharged from the treatment layer is preferably returned to the water treatment layer for reuse. Further, by reusing the water, the flow rate of the treated water in the treated layer can be increased, and as a result, the fines adhering to the polyester chips can be washed away, so that a fines removing effect is produced.

When the polyester chips are continuously treated with water, the polyester chips are continuously or intermittently received from the upper portion in a tower-type treatment tank, and water is continuously supplied in a parallel or countercurrent water treatment. Can be made. The treated polyester chips are continuously or intermittently extracted from the lower part of the treated layer.

When the polyester chips are subjected to water treatment in a batch system, a silo type treatment tank can be used. That is, the polyester chips are received in silos in a batch system and treated with water. Alternatively, the polyester chips may be received in a rotating tubular processing tank, and water treatment may be performed while rotating to make the contact with water more efficient.

In this case, the whole amount of the polyester chips is charged and filled in the treatment tank and filled with the treated water, and the treated water circulates continuously or intermittently (may be collectively referred to as continuous) as necessary, In addition, a part of the treated water will be discharged continuously or intermittently and new treated water will be additionally supplied. After the water treatment, the entire amount of polyester chips is extracted from the treated layer.

Whether the water treatment method is continuous or batchwise, the number of particles having a particle size of 1 to 25 μm existing in the water introduced from outside the system is X,
The content of sodium is N, the content of magnesium is M,
When the content C of calcium is S, and the content of silicon is S, at least one, preferably all of the following formulas (8) to (12) are satisfied, and the water treatment is performed. 1 ≤ X ≤ 50000 (pieces / 10 ml) ... (8) formula 0.005 ≤ N ≤ 1.0 (ppm) ... (9) formula 0.01 ≤ M ≤ 0.5 (ppm) -(10) Formula 0.01 ≤ C ≤ 1.0 (ppm) ... (11) Formula 0.01 ≤ S ≤ 2.0 (ppm) ... (12) Formula

By setting any of the number of particles in the water introduced into the water treatment tank and the content of sodium, magnesium, calcium, or silicon within the above range, a metal-containing substance such as an oxide or hydroxide called scale. May float in the treated water, precipitate, or adhere to the walls of the processing tank or piping, which may adhere to and permeate the polyester chips, promoting crystallization during molding, resulting in a poorly transparent bottle. Can be prevented.

Particle sizes of 1 to 25 μm used for water treatment below
The method for obtaining water containing 1 to 50000 particles / 10 ml of the above is exemplified.

As a method for reducing the number of particles in water to 50,000 particles / 10 ml or less, an apparatus for removing particles is installed at least at one or more steps in the process of supplying natural water such as industrial water to a treatment tank. Preferably, from the natural water sampling port to the treatment tank described above, a pipe for returning the water drained from the treatment tank to the treatment tank again, a fine removal device, and the like, to a treatment device including incidental equipment necessary for water treatment. A device for removing particles is installed, and the particle size of 1 to 2 in water supplied to the processing device
The content of 5 μm particles is preferably 1 to 50,000 particles / 10 ml. As the device for removing the particles of the treated water in the treatment tank, the above-mentioned fines removing device in water can be used.

As the device for removing sodium, magnesium, calcium, silicon and the like, an ion exchange device and the like can be mentioned.

Further, in the treated water discharged from the treatment tank in the water treatment, fines already attached to the polyester chips at the stage of receiving the polyester chips in the treatment tank, the polyester chips themselves during the water treatment, or the walls of the treatment tank. Contains polyester fines generated by friction.

Therefore, when the treated water discharged from the treatment tank is returned to the treatment tank and reused, the amount of fines contained in the treated water in the treatment tank gradually increases. Therefore, the fines contained in the treated water may adhere to the walls of the treatment tank or the piping wall and clog the piping.

Fine contained in the treated water adheres to the polyester chip again, and after that, the fine adheres to the polyester chip due to the electrostatic effect in the step of drying and removing water, so that the fine content of polyester is very high. Will increase.

Fines generated in the polyester manufacturing process have a crystallization promoting effect, but it was found from the polyester chips that have undergone the water treatment process that the fines generated in the above processes have a very high crystallization promoting effect. .

Such fineness promotes the crystallinity of the polyester, resulting in poor transparency of the obtained bottle, and excessive crystallinity at the time of crystallization of the bottle cap portion, resulting in a dimension of the cap portion. Will not meet the specifications, which will result in poor capping of the spout and therefore leakage of the contents.

In the present invention, in the case of the continuous water treatment method for polyester chips, the amount of fine powder of treated water drained together with the polyester chips from the treatment tank is 0.5% by weight or less,
Preferably 0.3% by weight or less, more preferably 0.0
It is desirable that a part of the treated water discharged from the treatment tank is returned to the treatment tank and repeatedly used while maintaining the content at 5% by weight or less. Further, in the case of a batch type water treatment method, the amount of fine powder in water at the end of the water treatment is 0.5% by weight or less, preferably 0.
At least part of the treated water discharged from the treatment tank is returned to the treatment tank so as to be 3% by weight or less, more preferably 0.05% by weight or less, and is repeatedly used. Here, the amount of fine powder is obtained by the following measuring method.

In order to suppress an increase in the amount of fine powder in the treated water in the treatment tank, a device for removing fines is installed at at least one place in the process until the treated water discharged from the treatment tank is returned to the treatment tank again. Examples of the device for removing fines include a filter filtration device, a membrane filtration device, a precipitation tank, a centrifuge, and a foam entrainment processor.

For example, in the case of a filter filtration device, examples thereof include a belt filter system, a bag filter system, a cartridge filter system, and a centrifugal filtration system. Among them, a belt filter type, a centrifugal filtration type, and a bag filter type filtration device are suitable for continuous operation. Further, in the case of a belt filter type filtering device, examples of the filter material include paper, metal, cloth and the like. In addition, in order to remove fines and efficiently process water,
The mesh size of the filter is 5 to 100 μm, preferably 10 to 70 μm, and more preferably 15 to 40 μm.

The water-treated polyester chips are drained by a draining device such as a vibrating screener or Simon Carter, and transferred to a drying step. As a matter of course, the water separated from the polyester chips by the water draining device is sent to the above fine removing device and can be used again for water treatment.

For drying the polyester chips, a commonly used polyester chip drying treatment can be used. As a continuous drying method, a hopper-type aeration dryer in which polyester chips are supplied from the upper part and a dry gas is aerated from the lower part is usually used.

As a method for reducing the amount of dry gas and efficiently drying, a rotary disk type continuous dryer is selected, and heating steam or a heating medium is applied to the rotary disk or the outer jacket while ventilating a small amount of dry gas. It is possible to indirectly dry the granular polyester chips supplied with the above.

A double-cone type rotary dryer is used as a dryer for batch-type drying, and can be dried under vacuum or under vacuum while a small amount of dry gas is passed through. Alternatively, it may be dried under atmospheric pressure while aerating a dry gas.

Although atmospheric air may be used as the dry gas, dry nitrogen and dehumidified air are preferable from the viewpoint of preventing a decrease in molecular weight due to hydrolysis or thermal oxidative decomposition of the polyester.

[0119]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. In addition, the measuring method of the main characteristic value in this specification is demonstrated below.

(1) Intrinsic viscosity (IV) of polyester It was determined from the solution viscosity at 30 ° C. in a mixed solvent of 1,1,2,2-tetrachloroethane / P-chlorophenol (1/3 weight ratio).

(2) Density The density was measured using a calcium nitrate / mixed solvent density gradient tube.

(3) Content of cyclic trimer of polyester A sample is dissolved in a hexafluoroisopropanol / chloroform mixture, and chloroform is further added to dilute it. Methanol is added to this to precipitate the polyester, which is then filtered. After the filtrate was evaporated to dryness, the volume was made constant with dimethylformamide, and the cyclic trimer composed of ethylene naphthalate units was quantified by liquid chromatography.

(4) Fine amount About 0.5 kg of resin is a sieve (A) with a wire mesh having a nominal size of 5.6 mm according to JIS-Z8801, and a nominal size of 1.7.
A sieve (diameter 20 cm) (B) having a metal mesh of mm was placed on the sieve in which the two stages were combined, and sieved with a rocking type sieving tow machine SNF-7 manufactured by Terraoka at 1800 rpm for 1 minute. This operation was repeated, and a total of 20 kg of the resin was sieved. If, in addition to the film-like material, two or more chips fused to each other or a chip-like material cut into a size larger than the normal shape are captured on the sieve (A), these The rest of the film-like material from which the powder had been removed and the fines sieved off under the sieve (B) were separately washed with ion-exchanged water and filtered through a G1 glass filter manufactured by Iwaki Glass Co., Ltd. to be collected. These are put together with the glass filter in a dryer at 100 ° C.
After drying for 2 hours, it was cooled and weighed. The same operation of washing with ion-exchanged water and drying was repeated again to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to determine the fine weight and the weight of the film-like material.
The fine content or the film-like material content is the fine weight or the film-like material weight / the total resin weight that has been sieved. The total content is calculated from these values. In the case of melt polycondensation polymer Low: Fine content or film-like material content is less than 3% by weight High: Fine content or film-like material content is 3% by weight or more In case of solid-state polymerized polymer Low: Fine content or The film content is
Less than 0.5% by weight: Fine content or film-like material content
0.5% by weight or more

(5) Twin / Triple Chip Generation Status Twin / triplet chips are selected for about 0.5 kg of resin,
I confirmed its existence.

(6) Amount of fine powder (ppm) in treated water 1000 cc of treated water passed through a filter of JIS standard 20 mesh was collected from the outlet of treated water in the treatment tank,
100% after filtering with 1G1 glass filter manufactured by Iwaki Glass Co., Ltd.
After drying at ℃ for 2 hours and cooling at room temperature, the weight is measured and calculated.

(7) Particle Size and Number of Particles in Water Light-shielding Particle Measuring Instrument HIAC / ROYCO. Manufactured by Pacific Scientific Company. Counter 4
The measurement was performed using a 100 type and a sampler 3000 type.

(8) Glass transition temperature Tg of polyester
And melting point Tm For a sample obtained by cutting a strand into a chip, a robot DSC device (RDC-220) manufactured by Seiko Denshi Kogyo
Was used to evaluate the glass transition temperature Tg and the melting point Tm of the polyester chip at a heating rate of 20 ° C./min.

(9) Chemical oxygen demand (COD) (mg / l) of the introduced water introduced into the chip forming step The introduced water filtered with a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd. is in accordance with the method of JIS-K0101. To measure.

(10) Molding of molded plate Using an M-150C (DM) injection molding machine manufactured by Miki Co., Ltd., the feed screw rotation speed = 40 rpm, screw rotation speed 120 rpm, molding temperature 300 ° C., mold cooling water temperature 40. A molding plate having a weight of 146 g and a thickness varying from 2 mm to 11 mm per 1 mm was molded at a temperature of 75 ° C. and a cycle time of about 75 seconds.

(11) Molding of bottles M-150C (DM) injection molding machine manufactured by Miki Co., Ltd.
Injection molding temperature 300 ° C, feed screw speed 40
%, Screw rotation speed 160 rpm, mold cooling water temperature 4
8 ° C, cycle time = approx. 45 seconds, body thickness approx. 3.8
A preform of a bottle having a size of mm and a weight of about 57 g was formed.
Next, this pre-formed body is LB- manufactured by CORPOPLAST.
Using an 01E molding machine, the film was biaxially stretch blown at a ratio of about 2.3 times in the longitudinal direction and about 3.8 times in the circumferential direction, and then about 160 times.
Heat-set for about 6.5 seconds in the mold set to ℃, the capacity is 1
A 500 cc container was molded. The stretching temperature was controlled at 145 ° C.

(12) Haze (% haze) A sample cut out from the body (wall thickness of about 0.45 mm) of a hollow molding container or a 5 mm thick sample cut from a molded plate of 2 to 11 mm thick was colored by Nippon Denshoku. It was measured with a haze meter (NDH2000 type) manufactured by Co., Ltd.

(13) From the start of forming a preformed body of a number of shaped plates or bottles in which air bubbles are generated in the molded product 11
The number of molded articles in which air bubbles were mixed into 250 consecutive pieces from the first piece to the 260th piece.

Examples 1 to 4 and Comparative Examples 1 to 2 A slurry of dimethyl naphthalenedicarboxylate (NDC) and ethylene glycol (EG) was charged into a transesterification reaction vessel equipped with a rectification column and a stirrer, A manganese acetate compound was added, and the transesterification reaction was performed while gradually elevating the temperature to 260 ° C. under normal pressure while discharging the distilled methanol out of the system. The oligomer obtained by the transesterification reaction is sent to a polycondensation reactor as a polycondensation catalyst,
Antimony trioxide, cobalt acetate, trimethyl phosphate (TMPA) as a stabilizer and triethylamine as a DEG generation inhibitor were added, and the temperature was raised under reduced pressure for polycondensation.

The intrinsic viscosity obtained by melt polymerization is 0.6.
Molten polycondensed polyethylene naphthalate having 0 dl / g, Tg of 120 ° C. and Tm of 268 ° C. was discharged in a strand form from the die head (1) and introduced into the cooling tank (2). The strands flowed down along with the cooling water (9) along the strand guide section (3) in the cooling tank (2), and were cooled by spraying the cooling water (10) toward the guide plate. Immediately before cutting the strands into chips, conveyor water (11) was added, and the strands were cut into chips with a cutter (4) in the presence of cooling water. Using a device in which the chips are conveyed to the dehydrator (6) while being further cooled by running water in a cooling pipe (5), the intrinsic viscosity is 0.
A melt polycondensation PEN chip having 60 dl / g, Tg of 120 ° C. and Tm of 268 ° C. was obtained.

At this time, the polyester temperature Text when discharging from the die head (1), the average cooling water temperature T, and the cooling water supply amount V1 (cm ³ ) per unit time in the process until each strand is cut into chips. , The contact surface area S1 (c) of the strand to the cooling water per unit time
m ² ) and the time t1 during which the strand is in contact with the cooling water
(sec) and the amount of cooling water V2 (cm ³ ) per unit time until the chips are separated from the cooling water after the strand is cut into chips, and the contact surface area S2 of the strand to the cooling water per unit time (Cm ² ) and the time t2 during which the chip was in contact with the cooling water were carried out under the conditions shown in Table 1.

Industrial water (derived from river bottom water) was treated with an ion exchange apparatus, COD was 0.8 g / ml, and particle size was 1
˜25 μm particles about 2550 particles / 10 ml, sodium content 0.05 ppm, magnesium content 0.1.
Cooling water containing 03 ppm, a calcium content of 0.03 ppm, and a silicon content of 0.13 ppm was used.

The fine polycondensation PEN chips thus obtained were checked for fine content, twins, and triplets by the above-mentioned method. Further, the melt polycondensation PEN chip was dried under reduced pressure at 105 ° C. for 48 hours to obtain M-1 manufactured by Meiki Seisakusho.
A 50 C (DM) injection molding machine was used to mold a molded plate having a thickness of 2 to 9 mm, and the haze of the molded plate and the presence or absence of bubble generation were confirmed. Table 1 shows the evaluation results of the chips and the molded plate.

[0138]

[Table 1]

Examples 5 to 7 and Comparative Examples 3 to 4 A slurry of dimethyl naphthalenedicarboxylate (NDC) and ethylene glycol (EG) was charged into a transesterification reaction vessel equipped with a rectification column and a stirrer, A manganese acetate compound was added, and the transesterification reaction was performed while gradually elevating the temperature to 260 ° C. under normal pressure while discharging the distilled methanol out of the system. The oligomer obtained by the transesterification reaction is sent to a polycondensation reactor as a polycondensation catalyst,
Antimony trioxide, cobalt acetate, trimethyl phosphate (TMPA) as a stabilizer and triethylamine as a DEG generation inhibitor were added, and the temperature was raised under reduced pressure for polycondensation.

Intrinsic viscosity obtained by melt polycondensation IV = 0.
60 dl / g, glass transition temperature Tg = 120 ° C., melting point T
A polyethylene naphthalate having m = 268 ° C. was formed into chips under the conditions shown in Table 2 in the same manner as in Examples 1 to 4. In addition, industrial water (derived from river underflow water) was treated with an ion exchange device, COD was 0.8 mg / l, and particle size was 1 to 25.
Approximately 2550 particles / 10 μm, sodium content 0.05 ppm, magnesium content 0.03 p
Cooling water having pm, a calcium content of 0.03 ppm and a silicon content of 0.13 ppm was used.

This resin was continuously kept under a nitrogen atmosphere for about 1
Primary crystallization was performed at 65 ° C., and crystallization was aged at about 180 ° C. to obtain crystallized PEN having a density of 1.348 g / cm ³ . Further, it is sent to the solid-state polymerization reactor under a nitrogen atmosphere for about 23
Solid state polymerization was carried out at 5 ° C. After the solid phase polymerization, fines were removed by continuous treatment in a sieving step and a fines removing step. The obtained PEN resin has an intrinsic viscosity of 0.79 to 0.81 dl.
/ G, the content of cyclic trimer is 0.40 to 0.45% by weight,
The density was 1.352 to 1.355 g / cm3.

Regarding the obtained solid-state polymerization PEN chip,
The fine content, twins, and triplets were confirmed by the above method. Also, 1 solid-state polymerization PEN chip
Dry under reduced pressure at 40 ° C for 16 hours, and use M-150 manufactured by Meiki Seisakusho.
A C (DM) injection molding machine was used to mold a molded plate having a thickness of 2 to 11 mm, and the haze of the molded plate and the presence or absence of bubble generation were confirmed. In addition, a preform having a weight of 57 g / piece was molded using an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho, and then the LB01E blow molding machine was used to obtain a capacity of 1.5.
An L biaxially stretched blow bottle was molded, and it was confirmed whether haze and bubbles were generated. Table 2 shows the evaluation results of the chip, the molded plate and the blow bottle.

Comparative Example 5 In Example 6, as industrial water, COD was 3.9 m.
g / l, about 598300 particles with a particle size of 1-25 μm
Table 2 shows the results when the cooling water was changed to 10 ml, the sodium content was 0.10 ppm, the magnesium content was 0.08 ppm, the calcium content was 0.09 ppm, and the silicon content was 0.25 ppm.

[0144]

[Table 2]

Example 8 A slurry of dimethyl naphthalenedicarboxylate (NDC) and ethylene glycol (EG) was placed in a transesterification reaction vessel equipped with a rectification column and a stirrer, and a manganese acetate compound was added, While gradually raising the temperature to 260 ° C. under normal pressure, the transesterification reaction was carried out while discharging the distilled methanol out of the system. The oligomer obtained by the transesterification reaction is sent to a polycondensation reactor as a polycondensation catalyst,
Germanium dioxide, cobalt acetate, trimethyl phosphate (TMPA) as a stabilizer, and triethylamine as a DEG generation inhibitor were added, and the temperature was raised under reduced pressure to cause polycondensation.

In the same manner as in Example 6, the intrinsic viscosity was 0.5.
Melt polymerization P with 9 dl / g and density of 1.327 g / cm ^3.
After obtaining EN chips, the intrinsic viscosity was 0.81 dl / g and the content of cyclic trimer was 0.4 by crystallization and solid-state polymerization treatment.
Solid-state PE with 0 wt% and density of 1.352 g / cm ^3.
N resin was obtained.

Then, an underwater particle removing device (22), which is a GAF filter bag PE-1P2S (polyester felt, filtration accuracy: 1 μm) manufactured by ISP, is installed.
Inlet (2) for ion-exchanged water via this device (22)
1), a raw material chip supply port (14) in the upper part of the treatment tank, an overflow discharge port (15) located at the upper limit level of the treated water in the treatment tank, a discharge port (16) of a mixture of polyester chips and treated water in the lower part of the treatment tank, The treated water discharged from the overflow outlet and the treated water that passed through the polyester chip drainer (continuous centrifuge) (17) discharged from the outlet at the bottom of the treatment tank had a filter medium made of paper. Thirty
A pipe (19) for sending to the water treatment tank again via a filtration device (18) which is a belt filter of μm, an inlet (20) for these fine-removed treated water, and acetaldehyde and glyco in the fine-removed treated water. -PE using the processing tank shown in FIG. 2 of a tower type having an internal capacity of 500 liters equipped with an adsorption tower (23) for adsorbing
N chips were water treated. The content of particles having a particle size of 1 to 25 μm in the water sampled through the ion-exchanged water inlet (21) of the water treatment device was about 2500 (10/10 ml), and the COD was 0.9.
It was mg / l.

Continuous feeding of PEN chips into the water treatment tank controlled to a treatment water temperature of 95 ° C. was started from the upper part (14) of the treatment tank at a rate of 50 kg / hour. After 5 hours from the start of feeding, the PET chips were removed from the lower part (16) of the water treatment tank while continuing to feed the PET chips to the water treatment tank.
The extraction of the treated water together with the treated water is started at a rate of 0 kg / hour, and the treated water that has passed through the continuous centrifugal dehydration device (17) that uses wind power is returned to the water treatment tank through the filtration device (18) and repeated. Started to use. The amount of fine powder in the treated water discharged from the treatment tank was about 0.15% by weight.

Water-treated PEN after 100 hours of continuous operation
Chips (fine content: about 0.04% by weight) were dried under reduced pressure, and a preform of a bottle was molded by an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho. Injection molding temperature is 30
The temperature was 5 ° C. Next, this preform is subjected to CORPOPLAS.
Using a LB-01E molding machine manufactured by T Co., a biaxial stretching blow was performed at a ratio of about 2.5 times in the longitudinal direction and about 5 times in the circumferential direction, and then about 1
The container was heat-set in a mold set at 60 ° C. for about 6.5 seconds to mold a container having a capacity of 1.5 L. The stretching temperature was controlled at 145 ° C.

Comparative Example 6 The water treatment was carried out in the same manner as in Example 6 except that the industrial water was used as it was as the introduction water to the water treatment apparatus without using the ion exchange apparatus used in Example 8. Particle size 1 to 25 contained in industrial water used as introduction water for water treatment
Particles of μm are about 492,300 particles / 10 ml, sodium content is 7.5 ppm, magnesium content is 2.0 p.
pm, the calcium content was 6.5 ppm, the silicon content was 12.0 ppm, and the COD was 3.8 g / ml.

[0151]

[Table 3]

[0152]

INDUSTRIAL APPLICABILITY According to the present invention, a polyester obtained by melt polymerization whose main repeating unit is ethylene naphthalate is 0.02 ≦ (V1 / S1) × t1 × ΔT ≦ 1.
By cutting into chips in the condition of 00 ... (1), heat resistance, aroma retention, gas barrier property, and chemical resistance are excellent.
Bubbles and fish eyes do not easily occur in the molded product, the molded product has good crystallization controllability and excellent transparency, and when water treatment of the polyester chips is performed, the treatment tank and piping are less contaminated, It is possible to advantageously manufacture a polyester that does not easily generate mold stains when molding a bottle or the like.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of an apparatus used in the method for producing polyester of the present invention.

FIG. 2 is a schematic view of an example of an apparatus used in the polyester production method of the present invention.

[Explanation of symbols]

1 die head 2 cooling tanks 3 Strand guide section 4 cutter 5 cooling pipes 6 dehydrator 7 Filter 8 heat exchanger 9 slide water 10 shower water 11 Conveyor water 12 strands 13 Treated water introduction section 14 Raw material chip supply port 15 Overflow outlet 16 Discharge port for polyester chips and treated water 17 Continuous centrifugal dehydrator 18 Fine removal filtration device 19 plumbing 20 Treated water inlet 21 Ion exchange water inlet 22 Particle remover 23 Adsorption tower

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J029 AA03 AB04 AC01 AC02 BA03                       CC05 KE12 KF03 KF04 KH03                       KH06 KH08 LB04 LB05

Claims (9)

[Claims] 1. A method for producing a polyester, the main repeating unit of which is ethylene naphthalate, wherein the polyester obtained by melt polymerization is discharged in a strand form from a die head, cooled and solidified, and then cut into chips. A method for producing polyester, which comprises cutting into chips under conditions satisfying the following formula (1). 0.02 ≦ (V1 / S1) × t1 × ΔT ≦ 1.00 (1) Formula Here, ΔT = (Tg−T) / (Text−T) Tg = polyester glass transition temperature (° C.) Text = polyester Temperature (° C.) when discharging in a strand form from the die head T = cooling water temperature (° C.) (where T is 20 ≦ T ≦ 95 (° C.)
Moreover, T <Tg is satisfied. ) V1 = amount of cooling water per unit time in the process until the strand is cut into chips (cm ³ / sec) S1 = cooling per unit time in the process until the strand is cut into chips Surface area of strand in contact with water (cm ² / sec) t1 = time (sec) during which strand is in contact with cooling water in the process until the strand is cut into chips 2. The main repeating unit is ethylene naphthalate.
Polyester obtained by melt polymerization
Formed polyester into chips under the conditions of claim 1.
After cutting, cut under the condition that the following formula (2) is satisfied.
For producing polyester characterized by cooling the cup
Law.           0.20 ≦ (V2 / S2) × t2 × ΔT Equation (2) here, ΔT = (Tg−T) / (Text−T) V2 = After the strand is cut into chips, click
Unit time in the process until the cooling water and the cooling water are separated
Cooling water volume (cm)³/ Sec) S2 = After the strand is cut into chips, click
Unit time in the process until the cooling water and the cooling water are separated
Surface area of the chip (cm) ²/ Se
c) t2 = after the strand is cut into chips,
Chip and cooling in the process until the cooling water and the cooling water are separated.
Indicates the time (sec) in contact with the waste water. 3. The method for producing a polyester according to claim 1 or 2, wherein the particle size present in water is 1 to 25 μm.
When the number of particles of m is 50,000 / 10 ml or less and the content of sodium, the content of magnesium, the content of silicon and the content of calcium are N, M, S and C, respectively, the following (3) to ( A method for producing a polyester, characterized in that water satisfying at least one of formulas (6) is used as cooling water. N ≦ 1.0 (ppm) ··· (3) M ≦ 0.5 (ppm) ··· (4) S ≦ 2.0 (ppm) ···・ (5) C ≦ 1.0 (ppm) ・ ・ ・ ・ ・ ・ (6) 4. A method for producing a polyester, characterized in that, when the polyester is produced by the method according to any one of claims 1 to 3, at least a part of cooling water used is repeatedly used. 5. The method for producing a polyester according to any one of claims 1 to 4, wherein (1) the melt-polymerized polyester is discharged in a strand form from a die head, and (2)
The strand is cooled with water in the strand guide section, (3) the strand is cut into chips in the presence of cooling water, (4) the cut chips are further water-cooled in a cooling pipe, and (5) by a dehydrator. A method for producing polyester, characterized in that cooling water and chips are separated. 6. A method for producing a polyester, which comprises subjecting the polyester obtained by the method according to any one of claims 1 to 5 to crystallization and solid phase polymerization treatment. 7. A method for producing a polyester, wherein the polyester obtained by the method according to any one of claims 1 to 6 and treated water are supplied to a treatment tank to treat the polyester with water. 8. The number of particles having a particle size of 1 to 25 μm existing in the treated water discharged together with the polyester from the treatment tank is X, the sodium content is N, the magnesium content is M, and the calcium content C is C. The method for producing polyester according to claim 7, wherein the water treatment is carried out by satisfying at least one of the following (7) to (11), where S is the content of silicon. 1 ≤ X ≤ 50000 (pieces / 10 ml) (7) 0.005 ≤ N ≤ 1.0 (ppm) ・ ・ ・ ・ ・ (8) 0.01 ≤ M ≤ 0.5 (ppm) (9) 0.01 ≤ C ≤ 1.0 (ppm) ・ ・ ・ ・ ・ (10) 0.01 ≤ S ≤ 2.0 (ppm) ・ ・ ・ ・ ・ (11) 9. The polyester according to claim 1, wherein the main repeating unit of the polyester is composed of ethylene naphthalate, and the intrinsic viscosity of the polyester is 0.45 to 1.6 dl / g. Method for producing polyester.