JP6560181B2 - Polyester resin composition and blow molded article comprising the same - Google Patents

Description

  The present invention relates to a polyester resin composition capable of obtaining a blow molded product excellent in transparency and impact resistance with good productivity.

  Polyethylene terephthalate (PET) is excellent in mechanical properties, chemical stability, transparency and the like, is inexpensive, and is widely used as various sheets, films, containers and the like. The growth in the use of hollow containers (bottles) for fruit juice drinks, liquid seasonings, edible oils, liquors, wines, etc. is remarkable. Moreover, since there is little concern about residual monomers and harmful additives in hollow molded articles made of vinyl chloride resin, and hygiene and safety are high, replacement from conventional bottles made of vinyl chloride resin and the like is also progressing.

  In general, when plastic bottles are manufactured, melt-plasticized resin is used as die orifices in terms of ease of molding, high productivity, and relatively low equipment costs such as molding machines and molds. A so-called direct blow molding method is employed in which a cylindrical parison is formed through extrusion, and air is blown into the mold by sandwiching the parison between the molds. In the case of this direct blow molding, it is necessary to avoid that the parison extruded in the molten state is drawn down during the blow molding in order to perform the molding smoothly. Therefore, a high melt viscosity is required for the resin used. Is done. Accordingly, vinyl chloride resins, polyolefin resins, and the like are widely used in direct blow molding as resins having a high melt viscosity.

  In direct blow molded products, replacement of vinyl chloride resin with polyester resin has been studied, but polyester resins generally do not have a high melt viscosity suitable for direct blow molding. For this reason, there is a problem that the extruded parison is drawn down during blow molding, and blow molding cannot be performed.

  Attempts have been made to copolymerize various components with PET for direct blow molding. As a typical copolymerization component, a diol component includes 1,4-cyclohexanedimethanol and a diol containing an ethylene oxide adduct of bisphenol A, and an acid component includes isophthalic acid. However, with these copolyesters, the blow-molded products obtained are not satisfactory in terms of impact resistance.

  In order to improve such problems, Patent Document 1 discloses a polyester resin excellent in heat resistance and impact resistance, which is copolymerized with a glycol having a specific structural formula. However, this glycol has a problem that, when the amount of copolymerization is increased, the polymerizability is remarkably lowered. Therefore, if the polymerization time is increased in order to obtain a sufficient degree of polymerization, the color tone and transparency are lowered.

  Further, Patent Document 2 proposes a copolyester characterized by copolymerization using a catalyst having a specific composition in order to eliminate the drawbacks of Patent Document 1. However, none of them can provide a blow molded article having sufficient impact resistance.

JP 58-174419 A JP 2004-2664 A

  The present invention solves the above-mentioned problems, and a polyester resin composition that can obtain a blow molded product excellent in transparency and impact resistance with high productivity without causing a problem of moldability due to drawdown during blow molding Polyester resin composition with excellent recyclability, which is intended to provide products, and can be molded well even if it is used again for blow molding once it has been used as an end material in blow molding It is intended to provide things. Furthermore, the present invention intends to provide a blow molded product formed using the polyester resin composition of the present invention.

The inventors of the present invention have arrived at the present invention as a result of intensive studies in order to solve the above problems.
That is, the gist of the present invention is the following (1 ) and (2) .
(1) A copolymer polyester resin having ethylene terephthalate as a main repeating unit and 2 to 40 mol% of all diol components being at least one of 1,3-propanediol and 2-methyl-1,3-propanediol. A resin composition having a main component and having an intrinsic viscosity of 0
. It is 7-1.4, and is formed using the polyester resin composition whose ratio (weight average molecular weight / number average molecular weight) of weight average molecular weight and number average molecular weight is 1.9-2.5. Blow molded product.
(2) 2-20 mol% of all diol components are 1,3-propanediol, 2-methyl-1
A polyester resin composition according to (1), which is a resin composition mainly comprising a copolyester resin which is at least one of 1,3-propanediol, and has a carboxyl end group concentration of 22 equivalent / t or less. A blow molded product characterized by being formed by using .

The polyester resin composition of the present invention is mainly composed of a copolymerized polyester resin obtained by copolymerizing a specific component, and has an intrinsic viscosity suitable for blow molding, a ratio of weight average molecular weight to number average molecular weight (weight average). (Molecular weight / number average molecular weight), it has excellent thermal stability, does not cause problems of whitening due to drawdown or crystallization during blow molding, has excellent transparency, and has high impact resistance. An excellent blow molded product can be obtained.
Among them, the polyester resin composition of the present invention, in which the copolymerization amount of a specific component is optimized and the carboxyl end group concentration is a specific amount or less, is transparent even if it is once used as an end material in blow molding. Blow molded products with excellent productivity can be obtained with good productivity, and recyclability is also excellent.
And since the blow molded article of this invention is formed using the polyester resin composition of this invention, it is excellent in transparency and impact resistance, and can be used for various uses.

Hereinafter, the present invention will be described in detail.
The polyester resin composition of the present invention is suitable for blow molding. Among them, a melt-plasticized resin is extruded through a die orifice to form a cylindrical parison, which is sandwiched between molds and air is put inside. It is suitable for a direct blow molding method for blowing or a stretch blow molding method in which a parison is formed by injection molding and stretch blow molded.

  The polyester resin composition of the present invention has ethylene terephthalate as the main repeating unit, and 2 to 40 mol% of the total diol component is at least one of 1,3-propanediol and 2-methyl-1,3-propanediol. The main component is a certain copolyester resin.

The copolymerized polyester resin according to the present invention has a copolymerization amount of 2 to 40 mol% of either 1,3-propanediol, 2-methyl-1,3-propanediol, or a combination thereof. It is preferably ˜20 mol%.
By copolymerizing an appropriate amount of 1,3-propanediol or 2-methyl-1,3-propanediol, the crystallization speed of the polyester resin can be adjusted to those suitable for blow molding, and crystals at the time of blow molding Whitening due to crystallization can be prevented, and impact resistance can be improved.
Among them, the reason why the copolymerization amount is preferably 2 to 20 mol% is that the polyester resin having a copolymerization amount within this range has crystallinity, and as described later, it is possible to perform solid-phase polymerization, and as a result This is because the carboxyl end group concentration is reduced, the resin is not thermally decomposed during blow molding, and stable molding becomes possible.

  When the copolymerization amount of the above components is less than 2 mol%, the resin crystallization speed is high, and therefore, when blow molding is performed, the molded product crystallizes and whitens, resulting in poor transparency. And it becomes a thing lacking in the effect which improves impact resistance. On the other hand, when the copolymerization amount of the above components exceeds 40 mol%, it takes time to cool and solidify the resin composition at the time of molding, and moldability deteriorates, such as poor mold release from the mold. .

Moreover, it is preferable that the ratio of ethylene glycol is 60 mol% or more among all the diol components in the copolyester resin. Examples of the diol component other than ethylene glycol include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, diethylene glycol, 1,4-cyclohexanedimethanol, dimer diol, An ethylene oxide adduct of bisphenol A or bisphenol S can be used.
On the other hand, it is preferable that 80 mol% or more of the acid component is terephthalic acid.

  Examples of dicarboxylic acid components other than terephthalic acid include isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, sebacic acid, dimer acid, and the like. These acids may be used in combination, or ester-forming derivatives of these acids may be used.

  The polyester resin composition of the present invention has the above-described copolymer polyester resin as a main component and satisfies the characteristic values described in detail below. In order to achieve these characteristic values, it is preferable to contain an additive such as an antioxidant as described later. The content of the copolyester resin in the polyester resin composition is preferably 90% by mass or more, and more preferably 95% by mass or more.

  The polyester resin composition of the present invention needs to have an intrinsic viscosity (IV) of 0.7 to 1.4, especially 0.9 to 1.4 when used for direct blow molding. Preferably there is. The intrinsic viscosity (IV) is measured at a temperature of 20 ° C. using a mixture of equal mass of phenol and ethane tetrachloride as a solvent.

  When the intrinsic viscosity is less than 0.7, since the viscosity of the resin is low, the drawdown of the parison becomes large at the time of blow molding, and the molding itself becomes difficult. In particular, during direct blow molding, the parison drawdown becomes significant, making molding difficult. On the other hand, when the intrinsic viscosity exceeds 1.4, it is necessary to raise the molding temperature, and the color tone and transparency of the obtained molded product are deteriorated. Moreover, since the thermal decomposition of the resin is promoted by increasing the molding temperature, the drawdown of the parison becomes large and molding becomes difficult, and the obtained molded product has uneven thickness. Furthermore, if the milled material is used again as a recycled material for blow molding, the resin is likely to be thermally decomposed during blow molding, making stable production difficult, and the resulting molded product has uneven thickness.

  The polyester resin composition of the present invention has a weight average molecular weight to number average molecular weight ratio (weight average molecular weight / number average molecular weight) of 1.9 to 2.5, and a carboxyl end group concentration of 22 equivalents / It is particularly important to satisfy both of being t or less. When the ratio of the weight average molecular weight to the number average molecular weight is within the above range, the composition has a viscosity suitable for blow molding. However, if thermal decomposition of the resin occurs due to heat treatment during blow molding, even if the resin has this property before molding, drawdown occurs during molding, making molding difficult or obtaining a molded product. Even if this occurs, unevenness in thickness occurs. Therefore, in order to prevent the thermal decomposition of the resin due to the heat treatment at the time of molding, the carboxyl end group concentration needs to be 22 equivalent / t or less.

In the polyester resin composition of the present invention, the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) is required to be 1.9 to 2.5. 4 is preferred.
When the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) is less than 1.9, the molecular chain is entangled in the resin and the crosslink density is insufficient. It cannot be assumed. For this reason, the drawdown of a parison becomes large at the time of blow molding, and molding becomes difficult, or the obtained molded product has uneven thickness.

  On the other hand, when the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) exceeds 2.5, the viscosity is high, and it is necessary to increase the molding temperature. Color tone and transparency deteriorate. Moreover, since the thermal decomposition of the resin is promoted by increasing the molding temperature, the drawdown of the parison becomes large and molding becomes difficult, and the obtained molded product has uneven thickness. Furthermore, if the milled material is used again as a recycled material for blow molding, the resin is likely to be thermally decomposed during blow molding, making stable production difficult, and the resulting molded product has uneven thickness.

  In addition, although the means to make the ratio of the weight average molecular weight and the number average molecular weight within the above range is not limited, a method of adding a hindered phenol-based antioxidant described later during the polymerization reaction of the copolymerized polyester resin, Examples thereof include a method of adding a hindered phenol-based antioxidant described later to the copolymerized polyester resin by melt-kneading.

Furthermore, the polyester resin composition of the present invention preferably has a carboxyl end group concentration of 22 equivalent / t or less, and particularly preferably 18 equivalent / t or less. By setting the carboxyl end group concentration of the polyester resin composition to 22 equivalent / t or less, thermal decomposition of the resin does not occur during blow molding, and stable molding becomes possible. In addition, the recyclability is excellent.
When the carboxyl end group concentration exceeds 22 equivalents / t, even if the intrinsic viscosity of the resin composition or the ratio of the weight average molecular weight to the number average molecular weight is in the above range, The heat treatment causes thermal decomposition of the resin, and the resin composition at the time of blow molding is such that these values do not satisfy the above range. For this reason, the drawdown of a parison becomes large, it becomes difficult to mold, and the resulting molded product has uneven thickness.

  Also, since the resulting molded product has an increased carboxyl end group concentration, the end material generated during molding also has a high carboxyl end group concentration. If it uses, thermal decomposition of resin will occur at the time of blow molding, and stable production will be difficult, and the resulting molded product will have thickness unevenness.

Furthermore, the polyester resin composition of the present invention preferably has a cyclic trimer content of 0.6% by mass or less, and more preferably 0.5% by mass or less. By using a polyester resin composition having a cyclic trimer content of 0.6% by mass or less for molding, improvement of contamination of molds and the like is observed. If the content of the cyclic trimer exceeds 0.6% by mass, it adheres to and contaminates devices such as molds and nozzles during molding. Since these contaminations cause surface roughness and whitening of the molded product, it is necessary to frequently clean the mold and nozzle.
In addition, in order to make the carboxyl end group concentration of the polyester resin composition 22 equivalent / t or less, or to make the content of the cyclic trimer 0.6 mass% or less, after the melt polymerization reaction for obtaining the polyester resin, This is possible by performing a solid phase polymerization reaction under specific conditions.

  And it is preferable that antioxidant is added in the polyester resin composition of this invention. Among them, it is preferable that the hindered phenol-based antioxidant is added so as to be 0.01 to 0.5% by mass in the polyester resin composition. By adding an appropriate amount of a hindered phenol antioxidant, it has an effect of suppressing thermal decomposition of the phthalic acid component. Further, the hindered phenol antioxidant preferably contains two or more hindered phenol groups in the molecule. When these antioxidants are added during the polymerization reaction step, a part of the compound is copolymerized in the polyester resin and incorporated in the molecular chain of the polyester, so that the entanglement of the molecular chain and the cross-linked structure are reduced. And the viscosity of the polyester resin composition becomes high. As a result, the ratio between the weight average molecular weight and the number average molecular weight can be within the above range.

  If the hindered phenolic antioxidant in the polyester resin composition is less than 0.01% by mass, it is difficult to achieve the above effects. On the other hand, if it exceeds 0.5 mass%, the viscosity becomes high, and the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight / number average molecular weight) often exceeds 2.5, and the color tone of the obtained molded product And transparency tends to deteriorate. Moreover, recyclability is also reduced.

  Examples of hindered phenol antioxidants include 2,6-di-t-butyl-4-methylphenol and n-octadecyl-3- (3 ′, 5′-di-t-butyl-4 ′. -Hydroxyphenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanate Nurate, 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], 3, 9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1'-dimethylethyl}- , 4,8,10-tetraoxaspiro [5,5] undecane, etc. are used, but tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) is effective and cost-effective. ) Propionate] methane is preferred.

  Further, in the polyester resin composition of the present invention, in addition to the above-described antioxidants, examples of coloring inhibitors include phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite. Phosphorus compounds such as trimethyl phosphate, tridecyl phosphate and triphenyl phosphate can be used, and these phosphorus compounds may be used alone or in combination of two or more. In addition, additives such as cobalt compounds such as cobalt acetate, manganese compounds such as manganese acetate, anthraquinone dye compounds, and copper phthalocyanine compounds may be contained in order to suppress coloring due to thermal decomposition of the polyester resin.

The polyester resin composition of the present invention may contain a foaming agent as shown below, and the blow molded product of the present invention may be made into a foam blow molded product by foam blow molding.
Examples of the foaming agent include pyrolysis-type organic compounds containing decomposable groups such as azo, N-nitroso, heterocyclic nitrogen and sulfonyl hydrazide groups, and inorganic compounds such as ammonium carbonate and sodium hydrogen carbonate. Can be mentioned. Specific examples thereof include azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, diazoaminobenzene, dinitrosopentamethylenetetramine, N, N′-dimethyl-N, N′-dinitrosotephthalamide, benzenesulfonyl Hydrazide, 4,4′-oxy-bis (benzenesulfonyl) hydrazide, diphenylsulfone-3,3′-disulfonylhydrazide, 4-toluenesulfonyl hydrazide, 4,4′-oxy-bis (benzenesulfonyl) semicarbazide, 4- Examples include toluenesulfonyl semicarbazide, barium azodicarboxylate, 5-phenyltetrazole, trihydrazinotriazine, 4-toluenesulfonyl azide, 4,4′-diphenyldisulfonyl azide, and the like.

  In addition, as the foaming agent, gaseous materials such as gaseous fluorocarbon, nitrogen, carbon dioxide, air, helium and argon, and liquid materials at ordinary temperatures such as liquid fluorocarbon and pentane can be used.

  The polyester resin composition of the present invention can be used by mixing (blending) polyester resins containing other thermoplastic resins or other copolymerization components. And the molded object obtained using the resin composition which mixed other resin in this way may be able to improve impact resistance further.

  Next, the manufacturing method of the polyester resin composition of this invention is demonstrated. The polyester resin composition in the present invention is preferably obtained through an esterification reaction, a melt polymerization reaction, and a solid phase polymerization reaction step. It is difficult to obtain a polyester resin composition having a target intrinsic viscosity only by the esterification reaction and the melt polymerization reaction. Even if it is obtained, the reaction time of the melt polymerization reaction becomes long, and the resulting polyester resin composition has a poor color tone.

Specifically, for example, it can be produced by the following method.
Terephthalic acid or its ester-forming derivative as an acid component, ethylene glycol as a glycol component in a predetermined ratio are charged into an esterification reactor, and subjected to an esterification reaction at a temperature of 160 to 280 ° C. under pressure. Is transferred to a polymerization reactor, and 1,3-propanediol and / or 2-methyl-1,3-propanediol, a polycondensation catalyst, and additives such as antioxidants and anti-coloring agents as necessary are added. Usually, the melt polymerization reaction is performed at a temperature of 240 to 290 ° C., preferably 250 to 280 ° C. under a reduced pressure of 1 hPa or less. The intrinsic viscosity of the copolymerized polyester (prepolymer) obtained here is preferably in the range of 0.5 to 0.8.

As the polycondensation catalyst, one or more known compounds generally used for PET, for example, germanium, antimony, titanium, and cobalt compounds can be used, but germanium or antimony compounds are preferably used. Further, when the transparency of the resulting polyester resin is very important, it is preferable to use a germanium compound. Examples of germanium or antimony compounds include oxides, inorganic acid salts, organic acid salts, halides, and sulfides thereof. These polycondensation catalysts are used in the range of 5 × 10 ⁻⁵ mol to 3.0 × 10 ⁻⁴ mol, particularly 6 × 10 ⁻⁵ mol to 2.0 × 10, with respect to 1 mol of the acid component of the polyester resin to be produced. It is preferably used in such an amount that it is within the range of ^-4 mol.

  Examples of the coloring inhibitor include phosphorus compounds such as phosphorous acid, phosphoric acid, trimethyl phosphite, triphenyl phosphite, tridecyl phosphite, trimethyl phosphate, tridecyl phosphate, and triphenyl phosphate. Further, cobalt compounds such as cobalt acetate, manganese compounds such as manganese acetate, anthraquinone dye compounds, and copper phthalocyanine compounds may be used.

  Subsequently, the prepolymer obtained by the above-described melt polymerization reaction is used as a chip having an arbitrary shape such as a die or a column, and the polyester chip is continuously supplied to a crystallization apparatus and crystallized at a temperature of 150 to 180 ° C. After being made into a solid, it is supplied to a dryer, dried at a temperature of 180 ° C. or less for 4 to 10 hours, sent to a preheater and heated to the following solid phase polymerization temperature for 2 to 5 hours, and then solidified. A polyester resin composition having a target intrinsic viscosity is obtained by continuously supplying to a phase polymerization machine and performing a solid phase polymerization reaction. The solid phase polymerization is preferably performed under an inert gas such as nitrogen gas. The solid phase polymerization is usually preferably carried out at a temperature in the range of 170 to 230 ° C, more preferably in the range of 180 to 220 ° C. The polymerization time is in the range of 20 to 60 hours, and the reaction is carried out in a solid phase polymerization machine.

  As described above, the polyester resin composition of the present invention is suitable for blow molding. However, even if an injection molding or stretching method is adopted, the molded product has excellent color tone, transparency, and impact resistance. (Injection molded body, sheet, film, etc.) can be obtained.

  Next, the blow molded product of the present invention is formed using the polyester resin composition of the present invention. The blow molded product of the present invention can be manufactured using a general-purpose direct blow molding machine or stretch blow molding machine, and the temperature of each part of the cylinder and the nozzle of the molding machine is in the range of 230 to 280 ° C. Is preferred.

  The blow molded article of the present invention may be a blow molded article having a single layer structure formed using only the polyester resin composition of the present invention, or the polyester resin composition of the present invention at least partially. It may be a blow molded article having a multilayer structure used.

Next, the present invention will be specifically described using examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(A) Intrinsic viscosity It was measured by the same method as described above.
(B) Composition of copolymer polyester resin The obtained polyester resin composition was dissolved in a mixed solvent having a volume ratio of deuterated hexafluoroisopropanol and deuterated chloroform of 1/20, and LA-manufactured by JEOL Ltd. 1H-NMR was measured with a 400-type NMR apparatus, and the type and content of the copolymerization component were determined from the integrated intensity of the proton peak of each component of the obtained chart.
(C) Ratio of weight average molecular weight and number average molecular weight The obtained polyester resin composition was measured for polystyrene-reduced number average molecular weight and weight average molecular weight under the following conditions using gel permeation chromatography (GPC). The weight average molecular weight / number average molecular weight was calculated.
Liquid feeding device: Isocratic HPLC Pump 1515 manufactured by Waters
Detector: Waters RefractiveIndexDetector 2414
Column: Mixed-D
Solvent: hexafluoroisopropanol / chloroform = 5/95 (mass ratio)
Flow rate: 1 ml / min Measurement temperature: 40 ° C

(D) Carboxyl end group concentration 0.1 g of the obtained polyester resin composition was dissolved in 10 ml of benzyl alcohol, 10 ml of chloroform was added to this solution, and then titrated with 1/10 N potassium hydroxide benzyl alcohol solution. Asked.
(E) Cyclic trimer content 100 mg of the obtained polyester resin composition was dissolved in a mixed solvent having a volume ratio of hexafluoroisopropanol and chloroform of 1/20, and acetonitrile was added for extraction, followed by liquid chromatography. It was measured under the following conditions, and the amount of cyclic trimer was calculated.
Column: Waters micro bonder sphere
Filler: Si-C18 5 microns 100A
Detector: Waters 2996 type PDA detector (light source wavelength 254 nm)
Measurement flow rate: 1 ml / min Mobile phase solvent: acetonitrile / water = 7/3 and acetonitrile

(F) Direct blow moldability The thickness of the body of the obtained direct blow molded product (100 samples) was measured, and the difference between the thickness of the thickest part and the thinnest part was up to 0.30 mm. The sample was accepted and the number of samples accepted was shown. A sample having 90 or more acceptable samples was evaluated as “◯”, and a sample having less than 90 samples as “×”.
(G) Direct blow molding recyclability 50 parts by mass of a pulverized product obtained by pulverizing the obtained direct blow molded product with a pulverizer and 50 parts by mass of the polyester resin composition obtained in each example were blended and put into a dehumidifying dryer. After drying, direct blow molding was performed in the same manner as in Example 1 to obtain a molded product. About the obtained molded product (100 samples), the moldability was evaluated in the same manner as (f).
(H) Transparency of Direct Blow Molded Product In each of the obtained direct blow molded product and the direct blow molded product obtained in (g), a test piece (100 mm in size: thickness 2 mm × length 5 cm × width 5 cm) The turbidity of the test piece was measured with a turbidimeter MODEL 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. (air: haze 0%), and the average value of n number 100 was obtained. The smaller this value is, the better the transparency is, and if it is 5% or less, it is judged that the transparency is excellent.
(I) Impact resistance of direct blow molded product The obtained direct blow molded product (100 samples) and the direct blow molded product (100 samples) obtained in (g) were filled with 500 ml of tap water. At room temperature, the molded product was dropped once on a P tile from a height of 100 cm with the bottom of the molded product facing down and the side facing down. At this time, the impact resistance was evaluated by the number of molded products that were not broken. The number of molded products that were not cracked was determined to be 95 or more.

(J) Stretch blow moldability The thickness of the body of the obtained stretch blow molded product (100 samples) is measured, and the difference between the thickness of the thickest part and the thinnest part is up to 30 μm. , Showed the number of samples passed. A sample having 90 or more acceptable samples was evaluated as “◯”, and a sample having less than 90 samples as “×”.
(K) Stretch blow molding recyclability 50 parts by mass of a pulverized product obtained by pulverizing the obtained stretch blow molded product with a pulverizer and 50 parts by mass of the polyester resin composition obtained in each example were blended and put into a dehumidifying dryer. After drying, stretch blow molding was performed in the same manner as in Example 1 to obtain a molded product. About the obtained molded article (100 samples), the moldability was evaluated in the same manner as (j).
(L) Transparency of stretch blow-molded product In each of the obtained stretch blow-molded product and the stretch blow-molded product obtained in (k), a test piece of size: thickness 300 μm × length 5 cm × width 5 cm (100 The turbidity of the test piece was measured with a turbidimeter MODEL 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. (air: haze 0%), and the average value of n number 100 was obtained. The smaller this value, the better the transparency, and if it was 3% or less, it was judged that the transparency was excellent.
(M) Impact resistance of stretch blow molded product The obtained stretch blow molded product (100 samples) and the stretch blow molded product (100 samples) obtained in (k) were filled with 150 ml of tap water. At room temperature, the molded product was dropped once on a P tile from a height of 300 cm with the bottom surface of the molded product facing down and the side surface facing down. At this time, the impact resistance was evaluated by the number of molded products that were not broken. The number of molded products that were not cracked was determined to be 95 or more.

Example 1
The esterification reactor is fed with a slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) and reacted under the conditions of a temperature of 250 ° C. and a pressure of 50 hPa for esterification. A reaction product (number average degree of polymerization: 5) having a reaction rate of 95% was obtained.
50.3 parts by mass of a reaction product of TPA and EG was charged into a polymerization reactor, followed by 1.7 parts by mass of 1,3-propanediol, 0.008 parts by mass of germanium dioxide as a polymerization catalyst, and 0.004 of cobalt acetate. 0.12 parts by mass of hindered phenol antioxidant (manufactured by ADEKA: ADK STAB AO-60) were added respectively, and the reactor was evacuated, and after 60 minutes, the final pressure was 0.9 hPa and the temperature was 280 ° C. A melt polymerization reaction was performed for a time to obtain a prepolymer of a copolyester. This prepolymer had an intrinsic viscosity of 0.67.
Subsequently, the prepolymer was continuously supplied to a crystallization apparatus and crystallized at 150 ° C., then supplied to a dryer, dried at 160 ° C. for 8 hours, then sent to a preheater and heated to 190 ° C. The solid phase polymerization machine was supplied to a solid phase polymerization machine, and a solid phase polymerization reaction was carried out at 190 ° C. for 50 hours under nitrogen gas. The ultimate clay of the obtained polyester resin composition was 1.12, the ratio of the weight average molecular weight to the number average molecular weight was 2.09, and the carboxyl end group amount was 20.4.
After the obtained polyester resin composition is chipped and dried, a direct blow molding machine (Tahara Co., Ltd.) is used to extrude the resin at an extrusion temperature of 260 ° C. to form a cylindrical parison, and the parison is in a softened state. Inside, it was sandwiched between molds, the bottom was formed, and this was blown to form a bottle. At this time, when the parison diameter was 2 cm and the length was 25 cm, the bottom was formed and blow-molded to obtain a 500 cc hollow container (direct blow-molded product).
Moreover, after drying using this polyester resin composition, each part of the cylinder and the nozzle temperature were set to 260 ° C., screw rotation speed 100 rpm, injection time 10 seconds, cooling time 10 seconds, mold temperature 15 ° C. A preform was molded using (Nissei ASB Co., ASB-50TH type). Next, this preform was stretch blow molded at a blow pressure of 2 MPa in an atmosphere of 100 ° C., and a cylindrical bottle (a hollow container having an internal volume of 150 cc; stretched; an average thickness of 300 μm, an inner diameter of 3.5 cm, and a height of 15 cm) A blow molded product) was obtained.

Examples 2, 3, 7, 13, 14 and Comparative Examples 1, 3
Except for changing the composition so that the copolymerization amount of 1,3-propanediol or 2-methyl-1,3-propanediol and the content of the hindered phenol-based antioxidant are the values in Table 1, In the same manner as in Example 1, a copolyester prepolymer was obtained. And using the obtained prepolymer, the solid-state polymerization reaction was performed like Example 1, and the polyester resin composition was obtained.
Further, using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1.

Examples 4, 5, 8, 9, 11
The esterification reaction and melting were conducted in the same manner as in Example 1 except that the composition was changed so that the copolymerization amount of 1,3-propanediol or 2-methyl-1,3-propanediol became the value shown in Table 1. A polymerization reaction was performed to obtain a prepolymer of copolyester. Subsequently, the prepolymer is continuously supplied to a crystallizer and crystallized at 150 ° C., then supplied to a dryer, dried at 160 ° C. for 8 hours, and then sent to a pre-heater to increase the temperature to 180 ° C. The temperature was changed to 180 ° C. in the solid state polymerization machine.
Further, using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1.

Examples 6 and 10
An esterification reaction and a melt polymerization reaction were carried out in the same manner as in Example 1 to obtain a copolymerized polyester prepolymer. The prepolymer was supplied to a dryer and dried at 70 ° C. for 20 hours.
Using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1.

Example 12
An esterification reaction and a melt polymerization reaction were carried out in the same manner as in Example 1 to obtain a copolymerized polyester prepolymer. Then, using the obtained prepolymer, a solid phase polymerization reaction was performed in the same manner as in Example 1 except that the solid phase polymerization reaction time was 38 hours to obtain a polyester resin composition.
Further, using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1.

Example 15
An esterification reaction and a melt polymerization reaction were carried out in the same manner as in Example 1 to obtain a copolymerized polyester prepolymer. Then, using the obtained prepolymer, a solid phase polymerization reaction was performed in the same manner as in Example 1 except that the solid phase polymerization reaction time was changed to 60 hours to obtain a polyester resin composition.
Further, using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1.

Comparative Examples 2 and 4
A copolyester prepolymer was obtained in the same manner as in Example 1 except that the composition was changed so that the copolymerization amount of 1,3-propanediol or methylpropanediol was the value shown in Table 1. The obtained prepolymer was continuously supplied to the crystallization apparatus in the same manner as in Example 1. However, crystallization could not be performed because of fixing.
Therefore, a prepolymer of a copolyester obtained by performing an esterification reaction and a melt polymerization reaction without performing solid phase polymerization was used as a polyester resin composition, and subjected to direct blow molding and stretch blow molding in the same manner as in Example 1. .

Comparative Example 5
An esterification reaction and a melt polymerization reaction were performed in the same manner as in Example 1 to obtain a prepolymer of the obtained copolymer polyester. Then, using the obtained prepolymer, a solid phase polymerization reaction was carried out in the same manner as in Example 1 except that the solid phase polymerization reaction time was 80 hours to obtain a polyester resin composition.
Furthermore, using the obtained polyester resin composition, a direct blow molded product and a stretch blow molded product were obtained in the same manner as in Example 1 except that the extrusion temperature in the direct blow molding machine was 290 ° C.

Comparative Examples 6 and 7
A polyester resin composition was obtained in the same manner as in Comparative Example 7 except that the content of the hindered phenol-based antioxidant was changed to the values shown in Table 1.
And using the obtained polyester resin composition, it carried out similarly to Example 1, and obtained the direct blow molded product and the stretch blow molded product. In Comparative Example 7, the extrusion temperature in the direct blow molding machine and the stretch blow molding machine was 290 ° C.

Table 1 shows the characteristic values and evaluations of the polyester resin compositions and molded articles obtained in Examples 1 to 15 and Comparative Examples 1 to 7.

As is clear from Table 1, the polyester resin compositions obtained in Examples 1 to 15 were 1,3-propanediol and / or 2-methyl-1,3-propanediol, intrinsic viscosity, weight average molecular weight / Number average molecular weight, carboxyl end group weight, cyclic trimer weight is within the range specified in the present invention, and because it was excellent in thermal stability, without causing the problem of whitening due to crystallization and drawdown, Direct blow molding and stretch blow molding could be performed with good operability. And the obtained blow molded product (container) had no thickness unevenness and was excellent in transparency. Furthermore, it is excellent in recyclability, and can be blow-molded with good operability even when mixed with a recycled polyester resin composition, and the resulting blow-molded product (container) has no uneven thickness. It was excellent in transparency.
In addition, since the intrinsic viscosity of the polyester resin composition obtained in Examples 6 and 10 was low, the drawdown during direct blow molding was increased, and a direct blow molded product could not be obtained. However, stretch blow molding can be performed with good operability as in the other examples, and the obtained molded product has no thickness unevenness and is excellent in transparency. It was also excellent in recyclability.

  On the other hand, since the polyester resin composition obtained in Comparative Example 1 and Comparative Example 3 had a small amount of 1,3-propanediol or 2-methyl-1,3-propanediol copolymerization, The molded product crystallized and whitened, resulting in poor transparency. Moreover, since the crystallization speed of the polyester resin became too fast, the moldability deteriorated and the number of molded products with uneven thickness increased. In Comparative Example 2 and Comparative Example 4, since the copolymerization amount of 1,3-propanediol and 2-methyl-1,3-propanediol was large, it was amorphous and was not subjected to a solid phase polymerization reaction. The intrinsic viscosity of the polyester resin composition was low, and direct blow molding could not be performed. Regarding stretch blow molding, the polymer was thermally decomposed due to a large amount of copolymerization, and the moldability, particularly the recyclability, was poor.

  Since the intrinsic viscosity of the polyester resin composition obtained in Comparative Example 5 was too high, the polyester resin was thermally decomposed during molding because the molding temperature was raised, resulting in poor moldability and thickness. The number of molded products with unevenness increased. Further, when the end material was used again as a recycled material and again subjected to direct blow molding, the resin was thermally decomposed, resulting in uneven thickness and low recyclability. About stretch blow molding, since the intrinsic viscosity was too high, a stretch blow molded product could not be obtained.

Since the polyester resin composition obtained in Comparative Example 6 has a low content of hindered phenolic antioxidant and the ratio of the weight average molecular weight to the number average molecular weight is less than 1.9, the parison at the time of direct blow molding As a result, the molded product became uneven in thickness. Moreover, since there is little content of a hindered phenolic antioxidant, the thermal stability of the polyester resin composition was bad, and both direct blow molding and stretch blow molding were inferior in recyclability. The polyester resin composition obtained in Comparative Example 7 has a high content of hindered phenolic antioxidants, and the ratio of the weight average molecular weight to the number average molecular weight exceeds 2.5. As a result, the polyester resin was thermally decomposed at the time of molding, and as a result, the moldability deteriorated and the number of molded products with uneven thickness increased. In addition, when the milled material was used as a recycled material and again subjected to blow molding, the resin was thermally decomposed, resulting in uneven thickness and low recyclability.

Claims (2)

The main component is a copolymerized polyester resin having ethylene terephthalate as a main repeating unit and 2 to 40 mol% of all diol components being at least one of 1,3-propanediol and 2-methyl-1,3-propanediol. a to the resin composition, an intrinsic viscosity of 0.7 to 1.4, the ratio of the weight average molecular weight to number average molecular weight (weight average molecular weight / number average molecular weight) is 1.9 to 2.5 polyester A blow molded article formed by using a resin composition. A resin composition comprising as a main component a copolymer polyester resin in which 2 to 20 mol% of all diol components are at least one of 1,3-propanediol and 2-methyl-1,3-propanediol, A blow molded article formed by using the polyester resin composition according to claim 1, wherein the carboxyl end group concentration is 22 equivalent / t or less.