JP6782938B2 - A polyester resin composition, a method for producing the same, and a molded product comprising the same. - Google Patents

Description

The present invention relates to a polyester resin composition obtained by blending two types of polyester resins, and which can obtain a molded product having excellent color tone, transparency and impact resistance with high productivity. is there.

Polyethylene terephthalate (PET) has excellent mechanical properties, chemical stability, transparency, etc., is inexpensive, and is widely used as various sheets, films, containers, etc. Especially in recent years, carbonated beverages, The growth of hollow container (bottle) applications such as fruit juice beverages, liquid seasonings, cooking oil, liquor, and wine is remarkable. Moreover, since there is less concern about residual monomers and harmful additives as in a hollow molded product made of vinyl chloride resin, and the hygiene and safety are high, replacement of conventional bottles made of vinyl chloride resin or the like is progressing.

Generally, when manufacturing plastic bottles, melt-plasticized resin is used as a die orifice because of its ease of molding, high productivity, and relatively low equipment costs for molding machines and dies. A so-called direct blow molding method is adopted in which a cylindrical parison is formed by extruding it through a mold, sandwiched between molds, and air is blown into the inside. In the case of this direct blow molding, it is necessary to prevent the parison extruded in the molten state from drawing down during blow molding in order to carry out the molding smoothly, and therefore, the resin used is required to have a high melt viscosity. Will be done. Therefore, vinyl chloride resin, polyolefin resin, and the like are widely used in direct blow molding as resins having a high melt viscosity.

Although replacement of vinyl chloride resin with polyester resin has been studied for direct blow molded articles, polyester resin generally does not have a high melt viscosity suitable for direct blow molding. For this reason, there is a problem that the extruded parison draws down during blow molding and blow molding cannot be performed, and since crystallization is likely to occur during blow molding, whitening occurs even if molding is possible, and transparency is improved. There was a problem that it became insufficient.

In order to improve the transparency, a polyester resin obtained by copolymerizing polyethylene terephthalate with another monomer component has been proposed. As a result, crystallization can be suppressed, but the melt viscosity cannot be increased by itself. Therefore, a method has been proposed in which the viscosity is increased by cross-linking with a trifunctional or higher functional polyvalent carboxylic acid / polyhydric alcohol to solve the problem of drawdown (see, for example, Patent Document 1). However, when the viscosity is increased by such a cross-linking means, the moldability is improved, but when the amount of the polyvalent carboxylic acid or the polyhydric alcohol is large, it is easy to gel and the thermal stability is inferior, and the obtained molding There was a problem that the body was inferior in color tone, transparency, and impact resistance.

Japanese Patent No. 3173753

The present invention solves the above problems and can obtain a blow-molded article having excellent color tone, transparency, and impact resistance with good productivity without causing problems of whitening due to drawdown or crystallization during blow molding. It is intended to provide a polyester resin composition which can be produced, and also to provide a molded product made of the resin composition of the present invention.

The present inventor has arrived at the present invention as a result of diligent studies in order to solve the above problems. That is, the gist of the present invention is the following (1) to (3) .
(1) When ethylene terephthalate is the main repeating unit and the total amount of all glycol components is 100 mol%, 1,4-cyclohexanedimethanol is contained in an amount of 1 to 15 mol% as a copolymerization component, and isophthalate is contained in the acid component. When the polyester resin (A) having an ultimate viscosity of 0.5 to 1.3 and ethylene terephthalate as the main repeating unit and the total amount of the total acid components is 100 mol%, isophthalate does not contain an acid as a copolymerization component. A polyester resin (B) having an extreme viscosity of 0.5 to 1.3, which contains 1 to 15 mol% of an acid as a copolymerization component and does not contain 1,4-cyclohexanedimethanol as a copolymerization component in the glycol component. A method for producing a polyester resin composition for a blow-molded product, which is added at a mass ratio of 5/95 to 40/60 and kneaded with an extruder.
(2) Further, an amorphous polyester resin (C) having terephthalic acid and isophthalic acid as an acid component and neopentyl glycol and ethylene glycol as a glycol component in the extruder is mixed with 100 mass of the polyester resin (A). The method for producing a polyester resin composition for a blow-molded body according to ( 1), wherein 0.2 to 25 parts by mass is added to the portion and kneaded .
(3) The method for producing a polyester resin composition for a blow molded article according to (2), wherein the amorphous polyester resin (C) is added to the polyester resin (A), and then the polyester resin (B) is added.

Since the polyester resin composition of the present invention is formed by blending two types of polyester resins satisfying a specific composition and viscosity in a specific ratio, there is a problem of whitening due to drawdown or crystallization during direct blow molding. It is possible to obtain a blow-molded article having excellent color tone, transparency, and impact resistance with good productivity.
Since the blow molded article of the present invention is excellent in color tone, transparency, and impact resistance, it can be used for various purposes.

Hereinafter, the present invention will be described in detail.
The polyester resin composition of the present invention is suitable for blow molding. In blow molding, a melt-plasticized resin is passed through a die orifice and extruded to form a cylindrical parison, which is sandwiched between molds. There are a direct blow molding method in which air is blown into the inside, and a stretch blow molding method in which a parison is formed by injection molding and then stretch blow molding is performed. Among them, the direct blow molding method is suitable.

The polyester resin composition of the present invention may include a polyester resin (A) having 1,4-cyclohexanedimethanol (hereinafter sometimes abbreviated as CHDM) as a copolymerization component in a specific amount, and isophthalic acid (hereinafter abbreviated as IPA). ) Is contained as a copolymerization component in an appropriate amount of the polyester resin (B).

The polyester resin (A) will be described.
It contains ethylene terephthalate as a main repeating unit and CHDM as a copolymerization component in an amount of 1 to 15 mol%, and the copolymerization amount of CHDM is preferably 1 to 8 mol%. By containing (copolymerizing) CHDM, the crystallization rate of the polyester resin can be adjusted to one suitable for blow molding, and whitening due to crystallization during blow molding can be prevented. Then, the impact resistance of the obtained blow molded article can be improved.
If the copolymerization amount of CHDM is out of the above range, the crystallization rate cannot be adjusted and the impact resistance of the obtained blow molded article cannot be improved.

The proportion of ethylene glycol in the polyester resin (A) is preferably 70 to 99 mol%, and more preferably 85 to 99 mol%. Glycol components other than ethylene glycol and CHDM include, for example, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylene diol, diethylene glycol, ethylene oxide adduct of bisphenol A, and dimer. Examples include diol.

If the proportion of ethylene glycol as the glycol component is less than 70 mol%, the crystallinity of the resin composition is lowered and the resin composition tends to be amorphous, which is not preferable. If the proportion of ethylene glycol exceeds 99 mol%, the amount of CHDM copolymerization decreases, which makes it difficult to adjust the crystallization rate and improve the impact resistance of the obtained blow molded article. Become.

As the acid component in the polyester resin (A), the proportion of terephthalic acid is preferably 70 mol% or more, and the proportion of terephthalic acid is preferably 80 mol% or more, more preferably 90 mol% or more. If the proportion of terephthalic acid is less than 70 mol%, the crystallinity of the resin is lowered and it tends to be amorphous.

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

The ultimate viscosity of the polyester resin (A) needs to be 0.5 to 1.3, and more preferably 0.8 to 1.2. If the ultimate viscosity is less than 0.5, the ultimate viscosity of the obtained resin composition becomes too low, the drawdown of the parison becomes large during blow molding, and molding becomes difficult. Further, even if a molded product can be obtained, the impact resistance is inferior. On the other hand, if the ultimate viscosity exceeds 1.3, the ultimate viscosity of the obtained resin composition becomes too high, the molding temperature needs to be raised, the color tone and transparency of the obtained molded product deteriorate, and the impact resistance also deteriorates. descend.

Next, the polyester resin (B) will be described.
It contains ethylene terephthalate as a main repeating unit and isophthalic acid as a copolymerization component in an amount of 1 to 15 mol%, and the copolymerization amount of isophthalic acid is preferably 1 to 8 mol%. By containing (copolymerizing) isophthalic acid, the crystallization rate of the polyester resin can be adjusted to one suitable for blow molding, and whitening due to crystallization during blow molding can be prevented. Then, the effect of improving the impact resistance of the polyester resin (A) can be made more excellent.
If the copolymerization amount of isophthalic acid is out of the above range, the crystallization rate cannot be adjusted and the impact resistance improving effect cannot be made more excellent.

The proportion of terephthalic acid in the polyester resin (B) is preferably 60 to 99 mol%, and the proportion of terephthalic acid is preferably 85 to 99 mol%. If the proportion of terephthalic acid is less than 60 mol%, the crystallinity of the resin composition is lowered, and the resin composition tends to be amorphous. On the other hand, if the proportion of terephthalic acid exceeds 99 mol%, the amount of copolymerization of isophthalic acid decreases, so that the crystallization rate cannot be adjusted and the effect of improving impact resistance is further enhanced. I can't.

As the glycol component in the polyester resin (B), the proportion of ethylene glycol is preferably 70 mol% or more, and the proportion of ethylene glycol is preferably 80 mol% or more, more preferably 90 mol% or more. If the proportion of ethylene glycol is less than 80 mol%, the crystallinity of the resin is lowered, and the resin tends to be amorphous.

Examples of glycol components other than ethylene glycol include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylene diol, diethylene glycol, ethylene oxide adduct of bisphenol A, and dimer diol. Can be mentioned.

The ultimate viscosity of the polyester resin (B) needs to be 0.5 to 1.3, and more preferably 0.8 to 1.2. If the ultimate viscosity is less than 0.5, the ultimate viscosity of the obtained resin composition becomes too low, the drawdown of the parison becomes large during blow molding, and molding becomes difficult. Further, even if a molded product can be obtained, the impact resistance is inferior. On the other hand, if the ultimate viscosity exceeds 1.3, the ultimate viscosity of the obtained resin composition becomes too high, the molding temperature needs to be raised, the color tone and transparency of the obtained molded product deteriorate, and the impact resistance also deteriorates. descend.

The polyester resin composition of the present invention needs to have a mass ratio (A / B) of the polyester resin (A) and the polyester resin (B) of 5/95 to 40/60, and among them, 7/93 to 30. It is preferably / 70. When the proportion of the polyester resin (A) is less than the above range, the effect of improving the impact resistance cannot be achieved by adding the polyester resin (A). On the other hand, when the ratio of the polyester resin (A) is larger than the above range, it becomes difficult to uniformly mix the polyester resin (A) and the polyester resin (B), and the moldability deteriorates. For example, when blow molding is performed using this resin composition, a blow molded product having thickness unevenness is obtained.

In the polyester resin composition of the present invention, it is preferable that the polyester resin (B) having a large mass ratio is used as the base resin and the polyester resin (A) is used as a masterbatch to which a pigment or other additives are added.

Pigments and other additives contained in the polyester resin (A) include monoazo, disazo, condensed azo, naphthol, anthraquinone, quinacridone, perylene, perinone, isoindolinone, and phthalocyanine. Examples thereof include organic pigments based on dioxazine and titanium oxide, inorganic pigments such as titanium oxide, titanium yellow, red iron oxide, ultramarine blue, chromium oxide and molybdenum red, and carbon black. In addition, dispersion aids such as zinc stearate, magnesium stearate, calcium stearate, aluminum stearate, zinc laurate and the like can be mentioned, and a plurality of types thereof can be used in combination.

Next, the polyester resin composition of the present invention preferably contains an amorphous polyester resin (C) having terephthalic acid and isophthalic acid as acid components and neopentyl glycol and ethylene glycol as glycol components. By containing such an amorphous polyester resin (C), the dispersibility of the pigment and various additives as described above can be improved.

Hereinafter, the amorphous polyester resin (C) will be described.
The amorphous polyester resin (C) has terephthalic acid and isophthalic acid as an acid component, and neopentyl glycol and ethylene glycol as a glycol component. The molar ratio of terephthalic acid to isophthalic acid in the acid component is preferably 30/70 to 70/30. The molar ratio of ethylene glycol to neopentyl glycol in the glycol component is preferably 30/70 to 70/30.

The content of the amorphous polyester resin (C) in the polyester resin composition of the present invention is 0.2 to 25 parts by mass with respect to 100 parts by mass of the polyester resin (A), particularly 1 to 15 parts by mass. It is preferable to have.
When the content of the amorphous polyester resin (C) is less than 0.2 parts by mass, the effect of improving the dispersibility when a pigment, various additives, or the like is added to the resin composition is poor. On the other hand, if it exceeds 25 parts by mass, drawdown tends to occur during blow molding, and the moldability tends to be inferior.

Further, the polyester resin composition of the present invention contains the polyester resin (A) and the polyester resin (B) as main components as described above, and the ratio of both resins in the resin composition is 80% by mass or more. It is preferable that the content is 90% by mass or more.

The polyester resin composition of the present invention preferably contains a hindered phenolic antioxidant in an amount of 0.05 to 1.0% by mass, and more preferably 0.1 to 0.8% by mass.
The hindered phenolic antioxidant is preferably added during the polymerization reaction step of the polyester resin. By adding it during the polymerization reaction step, a part of the compound is copolymerized in the polyester resin. As a result, it is assumed that molecular chains are entangled in the polyester resin and a state similar to cross-linking occurs, and the melt viscosity of the polyester resin can be increased.

As hindered phenolic antioxidants, 2,6-di-t-butyl-4-methylphenol and n-octadecyl-3- (3', 5'-di-t-butyl-4'-hydroxy) Phenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 4,4'-Butylidenebis- (3-methyl-6-t-butylphenol), triethylene glycol-bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], 3,9- Bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1'-dimethylethyl} -2,4,8,10-tetraoxaspiro [5, 5] Undecane and the like are used, but since a state similar to cross-linking is likely to occur and it is advantageous in terms of cost, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl)) Propionate] Methyl is preferred.

Further, by containing a hindered phenol-based antioxidant in the resin composition of the present invention, the thermal stability of the resin composition is improved, and the obtained molded product is excellent in color tone and transparency. Become.

If the content of the hindered phenolic antioxidant is less than 0.05% by mass, the resin composition does not have the above-mentioned entanglement of molecular chains, so that it becomes difficult to increase the melt viscosity of the resin composition. , It is not possible to prevent the drawdown of the parison during blow molding. Further, the thermal stability of the resin composition is not improved, and the obtained molded product is inferior in heat resistance, color tone and transparency.

On the other hand, if the content exceeds 1.0% by mass, the expansion of the resin composition at the outlet of the extrusion die becomes too large during molding, and the surface of the obtained molded product becomes rough and the glossiness is impaired. Further, the melt viscosity of the resin composition becomes too high, it is necessary to raise the molding temperature at the time of molding, and the color tone of the obtained molded product deteriorates. Further, the effect of improving the thermal stability is saturated, which is disadvantageous in terms of cost.

The polyester resin composition of the present invention preferably has an ultimate viscosity of 0.7 to 1.5, particularly preferably 0.75 to 1.3, and is used for direct blow molding. Is preferably 0.9 to 1.3. The ultimate viscosity is measured at a temperature of 20 ° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.

When the ultimate viscosity is less than 0.7, the viscosity of the resin composition is low, so that the drawdown of the parison becomes large during blow molding, which makes molding difficult. On the other hand, when the ultimate viscosity exceeds 1.3, it is necessary to raise the molding temperature, and the color tone and transparency of the obtained molded product deteriorate. Further, it is not preferable because the expansion of the resin composition at the outlet of the extrusion die tends to be large during blow molding.

Further, the polyester resin composition of the present invention preferably has a carboxyl terminal group concentration of 32 equivalents / t or less, and more preferably 26 equivalents / t or less. By setting the carboxyl terminal group concentration of the polyester resin composition to 32 equivalents / t or less, the resin composition does not undergo thermal decomposition during blow molding, and stable molding becomes possible. In addition, it is also excellent in recyclability.

When the carboxyl terminal group concentration exceeds 32 equivalents / t, the heat treatment during blow molding causes thermal decomposition of the resin, which increases the drawdown of the parison, making molding difficult or obtaining a molded product. It tends to be uneven in thickness.

Further, since the obtained molded product also has an increased carboxyl end group concentration, the offcuts generated during molding also have a high carboxyl end group concentration. For this reason, when the end material is used as a recycled material for blow molding again, thermal decomposition of the resin composition occurs during blow molding, which makes stable production difficult, and the obtained molded product has uneven thickness.

Next, the polyester resin composition of the present invention preferably contains 5 × 10 ⁻⁵ mol to 3.0 × 10 ^-4 mol of the germanium compound with respect to 1 mol of the acid component of the polyester resin. Above all, it is preferably contained in an amount of 6 × 10 ^-5 mol to 2.0 × 10 ^-4 mol.
The germanium compound is used as a polymerization catalyst when obtaining a polyester resin, and if the content of the germanium compound is less than 5 × ^10-5 mol, the polyester resin having a target degree of polymerization cannot be obtained, or In the polymerization reaction, the polymerization time becomes long, and as a result, the color tone of the obtained polyester resin deteriorates. On the other hand, even if it exceeds 3.0 × 10 ^-4 mol, the effect as a polymerization catalyst is saturated, which is disadvantageous in terms of cost.

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

Next, a method for producing the polyester resin composition of the present invention will be described. After obtaining the polyester resin (A) and the polyester resin (B), respectively, a method of blending these polyester resins will be described.
These polyester resins in the present invention are preferably obtained through an esterification reaction, a melt polymerization reaction and a solid phase polymerization reaction step. It tends to be difficult to obtain a polyester resin having a target ultimate 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 obtained polyester resin composition has a poor color tone.

Specifically, for example, it can be produced by the following method.
The polyester resin (A) is prepared by charging terephthalic acid or an ester-forming derivative thereof as an acid component and ethylene glycol and CHDM as glycol components in a predetermined ratio into an esterification reactor, performing an esterification reaction, and then using the polymerization reactor. It is transferred, a polymerization catalyst and an additive are added, and a melt polymerization reaction is carried out to obtain a prepolymer. A solid phase polymerization reaction is carried out using the obtained prepolymer to obtain a polyester resin (A) copolymerized with CHDM having a target maximum viscosity.

The polyester resin (B) is prepared by charging terephthalic acid and isophthalic acid or an ester-forming derivative thereof as an acid component and ethylene glycol as a glycol component in a predetermined ratio into an esterification reactor and performing an esterification reaction at a predetermined temperature. , Transfer to a polymerization reactor, add a polymerization catalyst and additives, and carry out a melt polymerization reaction at a predetermined temperature to obtain a prepolymer. A solid-phase polymerization reaction is carried out using the obtained prepolymer to obtain a polyester resin (B) copolymerized with isophthalic acid having a target maximum viscosity.

The method of blending the two types of polyester resins obtained as described above is carried out by kneading with a single-screw or twin-screw extruder at a temperature in the range of 250 to 300 ° C.

When the polyester resin composition of the present invention contains an amorphous polyester resin (C), the amorphous polyester resin (C) is added to the polyester resin (A), and then the polyester resin (B) is added. The manufacturing method is preferable.

At this time, pigments and various additives may be added to the polyester resin (A), and when used as a masterbatch, the pigments and various additives are 5 to 60% by mass. It is preferable that it is added to, and the addition amount is preferably 10 to 50% by mass. Then, by adding the amorphous polyester resin (C) to the polyester resin (A), the dispersibility of the pigments and various additives in the polyester resin (A) is improved. Further, a masterbatch containing the polyester resin (A) and the amorphous polyester resin (C) is added to the polyester resin (B) as the base resin. At this time, the amorphous polyester resin (C) disperses the pigments and various additives in the polyester resin (A) with good dispersibility even in the polyester resin (B).

As described above, the polyester resin composition of the present invention is suitable for blow molding, but the polyester resin composition of the present invention can also be used in terms of color tone, transparency, and by adopting an injection molding or stretching method. It is possible to obtain a molded product such as an injection molded product, a sheet, or a film having excellent impact resistance.

When the molded product of the present invention is a blow molded product, it can be manufactured by using a general-purpose direct blow molding machine or a stretch blow molding machine, and the temperature of each cylinder part and nozzle of the molding machine is 230 to. The temperature is preferably in the range of 280 ° C.

Next, the present invention will be specifically described with reference to Examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(A) Extreme viscosity The measurement was carried out in the same manner as described above.
(B) Copolymerization amount of copolymerization component, content of hindered phenol-based antioxidant The obtained resin composition is mixed with a volume ratio of deuterated hexafluoroisopropanol and deuterated chloroform at 1/20. It was dissolved in a solvent, 1H-NMR was measured with an LA-400 type NMR apparatus manufactured by JEOL Ltd., and the copolymerization amount and content were determined from the integrated intensity of the proton peaks of each component in the obtained chart.

(C) Direct blow moldability The thickness of the body of the obtained hollow container 1 (100 samples) was measured, and the thickness difference between the thickest part and the thinnest part was up to 0.30 mm. The number of passing samples is shown. Those with 90 or more passed samples were marked with ◯, and those with less than 90 were marked with x.
(D) Recyclability of Direct Blow Molded Product 50 parts by mass of a crushed product obtained by crushing the obtained hollow container 1 with a crusher and 50 parts by mass of the polyester resin composition obtained in each example are blended into a dehumidifying dryer. After being charged and dried, direct blow molding was performed in the same manner as in Example 1 to obtain a hollow container 2. The moldability of the obtained hollow container 2 (100 samples) was evaluated in the same manner as in (c).

(E) Color tone of direct blow molded article A sample piece (20 pieces) was prepared by cutting out from the obtained hollow container 1 and the hollow container 2 obtained in (d), respectively, and a color difference meter ND manufactured by Nippon Denshoku Kogyo Co., Ltd. The color tone of the sample piece was measured using the −Σ80 type. The color tone was determined by a hunter's Lab colorimeter, and the b value was measured and used as the average value of n number 20. A b value of 2.0 or less was determined to have a good color tone.
(F) Haze of direct blow molded article A sample piece (20 pieces) was prepared by cutting out from the obtained hollow container 1 and the hollow container 2 obtained in (d), respectively, and the turbidity was determined by Nippon Denshoku Kogyo Co., Ltd. It was measured with a turbidity meter MODEL 1001DP (air: haze 0%) and used as an average value of n number 20. It was judged that the smaller this value is, the better the transparency is, and if it is 5% or less, the transparency is excellent.
(G) Impact resistance of the direct blow molded product (c) The hollow container 1 (100 samples) that passed the evaluation of the moldability and the hollow container 2 obtained in (d). (C) The hollow container 2 (100 samples) that passed the evaluation of moldability was filled with 340 ml of tap water, and at room temperature, on the P tile, from a height of 200 cm, of the molded product. The molded product was dropped once with the bottom surface facing down and the side surfaces facing down. The impact resistance was evaluated by the number of molded bodies that did not crack at this time. In addition, it was judged that the number of molded bodies that did not break was 95 or more.

(H) Stretch blow moldability
The thickness of the body of the obtained hollow container 3 (100 samples) was measured, and those with a thickness difference between the thickest part and the thinnest part up to 0.30 mm were accepted, and the number of passed samples was determined. Indicated. Those with 90 or more passed samples were marked with ◯, and those with less than 90 were marked with x.
(I) Recyclability of stretched blow molded article 50 parts by mass of a crushed product obtained by crushing the obtained hollow container 3 with a crusher and 50 parts by mass of the polyester resin composition obtained in each example are blended into a dehumidifying dryer. After being charged and dried, stretch blow molding was performed in the same manner as in Example 1 to obtain a hollow container 4. The moldability of the obtained hollow container 4 (100 samples) was evaluated in the same manner as in (c).

(J) Color tone of stretched blow molded article Sample pieces (20 pieces) were prepared by cutting out from the obtained hollow container 3 and the hollow container 4 obtained in (i), respectively, and a color difference meter ND manufactured by Nippon Denshoku Kogyo Co., Ltd. The color tone of the sample piece was measured using the −Σ80 type. The color tone was determined by a hunter's Lab colorimeter, and the b value was measured and used as the average value of n number 20. A b value of 2.0 or less was determined to have a good color tone.
(K) Haze of stretched blow molded article Sample pieces (20 pieces) were prepared by cutting out from the obtained hollow container 3 and the hollow container 4 obtained in (i), respectively, and the turbidity was determined by Nippon Denshoku Kogyo Co., Ltd. It was measured with a turbidity meter MODEL 1001DP (air: haze 0%) and used as an average value of n number 20. It was judged that the smaller this value is, the better the transparency is, and if it is 5% or less, the transparency is excellent.
(L) Impact resistance of the stretched blow molded product The hollow container 3 (100 samples) that passed the evaluation of the moldability of (h) and the hollow container 4 obtained in (i). , (I), the hollow container 4 (100 samples) that passed the evaluation of moldability was filled with 340 ml of tap water, and molded from a height of 200 cm on a P tile at room temperature. The molded product was dropped once with the bottom surface of the body facing downward and the side surfaces facing downward. The impact resistance was evaluated by the number of molded bodies that did not crack at this time. In addition, it was judged that the number of molded bodies that did not break was 95 or more.

Example 1
[Polyester resin (A)]
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) is supplied to the esterification reactor and reacted at a temperature of 250 ° C. and a pressure of 50 hPa for esterification. A reaction product having a reaction rate of 95% (number average degree of polymerization: 5) was obtained.
90.2 parts by mass of the reaction product of TPA and EG was charged into the polymerization reactor, followed by 4.22 parts by mass of CHDM, 0.018 parts by mass of germanium dioxide as a polymerization catalyst, and a hindered phenolic antioxidant [manufactured by ADEKA]. "Adecastab AO-60": Tetraquis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane)] 0.09 parts by mass were added respectively, and the reactor was depressurized. After 60 minutes, a melt polymerization reaction was carried out at a final pressure of 0.9 hPa and a temperature of 280 ° C. for 4 hours to obtain a prepolymer of a copolymerized polyester.
The ultimate viscosity of this prepolymer was 0.72. This prepolymer was pre-dried at 150 ° C. for 5 hours and then solid-phase polymerized at 210 ° C. for 15 hours in a nitrogen stream to obtain a polyester resin (A) having the composition and extreme viscosity shown in Table 1.

[Polyester resin (B)]
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) is supplied to the esterification reactor and reacted at a temperature of 250 ° C. and a pressure of 50 hPa for esterification. A reaction product having a reaction rate of 95% (number average degree of polymerization: 5) was obtained.
A slurry (IPA / EG molar ratio = 1 / 3.1) composed of isophthalic acid (IPA) and ethylene glycol was charged into another esterification reaction can, and an esterification reaction was carried out at a temperature of 200 ° C. for 3 hours to carry out an esterification reaction. And ethylene glycol reaction solution was obtained.
86.2 parts by mass of the reaction product of TPA and EG was charged into the polymerization reactor, followed by 9.2 parts by mass of the reaction solution of isophthalic acid and ethylene glycol, 0.018 parts by mass of germanium dioxide as a polymerization catalyst, and hindered phenol. Antioxidant [ADEKA "Adecastab AO-60": Tetraquis [Methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane)] 0.18 parts by mass, respectively In addition, the reactor was depressurized and 60 minutes later, a melt polymerization reaction was carried out at a final pressure of 0.9 hPa and a temperature of 280 ° C. for 4 hours to obtain a prepolymer of copolymerized polyester.
The ultimate viscosity of this prepolymer was 0.72. This prepolymer was pre-dried at 150 ° C. for 5 hours and then solid-state polymerized at 210 ° C. for 15 hours in a nitrogen stream to obtain a polyester resin (B) having the composition and extreme viscosity shown in Table 1.

[Polyester resin composition]
After drying the above two types of polyester resins, they were put into a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd .: TEM26SS) at a mass ratio (A / B) = 10/90 and kneaded at a temperature of 280 ° C. A polyester resin composition was obtained.
[Blow molded article]
Then, the polyester resin composition obtained above is used, dried, and then molded using a direct blow molding machine (manufactured by Tahara) at an extrusion temperature of 270 ° C., a parison diameter of 3 cm, and a length of 25 cm. Then, a 350 cc hollow container 1 (direct blow molded article) was obtained.
Further, the polyester resin composition obtained above is used, dried, and then used by an injection molding machine (ASB-50TH type manufactured by Nissei ASB) to set the temperature of each part of the cylinder and the nozzle to 260 ° C. and the screw rotation speed. The preform was molded by setting 100 rpm, an injection time of 10 seconds, a cooling time of 10 seconds, and a mold temperature of 15 ° C. Next, this preform was stretch-blow molded at a blow pressure of 2 MPa in an atmosphere of 100 ° C., and a cylindrical bottle having an average wall thickness of 300 μm, an inner diameter of 3.5 cm, and a height of 15 cm (hollow container 3 having an internal volume of 150 cc; Stretch blow molded article) was obtained.

Examples 2-6, Comparative Examples 1-3
A polyester resin composition was obtained in the same manner as in Example 1 except that the mass ratio (A / B) of the polyester resin (A) to the polyester resin (B) was changed to that shown in Table 1.
Then, using the obtained polyester resin composition, direct blow molding and stretch blow molding were performed in the same manner as in Example 1 to obtain a hollow container 1 and a hollow container 3.

Examples 7-10
The polymerization reaction was carried out in the same manner as in Example 1 except that the amount of CHDM copolymerization of the polyester resin (A) or the amount of copolymerization of isophthalic acid of the polyester resin (B) was changed to those shown in Table 1, respectively. Polyester resins (A) and (B) having the ultimate viscosity shown in Table 1 were obtained. Next, a polyester resin composition was obtained in the same manner as in Example 1 except that the mass ratio (A / B) of the polyester resin (A) and the polyester resin (B) was changed to that shown in Table 1.
Then, using the obtained polyester resin composition, direct blow molding and stretch blow molding were performed in the same manner as in Example 1 to obtain a hollow container 1 and a hollow container 3.

Example 11
[Amorphous polyester resin (C)]
A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (TPA / EG molar ratio = 1 / 1.6) is supplied to the esterification reactor and reacted at a temperature of 250 ° C. and a pressure of 50 hPa for esterification. A reaction product having a reaction rate of 95% (number average degree of polymerization: 5) was obtained.
A slurry (IPA / EG molar ratio = 1 / 3.1) composed of isophthalic acid (IPA) and ethylene glycol was charged into another esterification reaction can, and an esterification reaction was carried out at a temperature of 200 ° C. for 3 hours to carry out an esterification reaction. And ethylene glycol reaction solution was obtained.
38.6 parts by mass of the reaction product of TPA and EG was charged into the polymerization reactor, followed by polymerization of 32.3 parts by mass of the reaction solution of isophthalic acid and ethylene glycol and 23.5 parts by mass of neopentyl glycol (NPG). 0.026 parts by mass of tetrabutyl titanate was added as a catalyst, the reactor was depressurized, and 60 minutes later, a melt polymerization reaction was carried out at a final pressure of 0.5 hPa and a temperature of 240 ° C. for 3 hours to obtain a prepolymer of a copolymerized polyester. After that, 3.6 parts by mass of neopentyl glycol was added, and the B reaction was carried out at a temperature of 240 ° C. for 1 hour to obtain an amorphous polyester resin (C) having the composition shown in Table 1 and an ultimate viscosity of 0.53.
[Polyester resin composition]
Using this amorphous polyester resin (C), 3.0 parts by mass was charged into 100 parts by mass of the polyester resin (A) obtained in Example 1 with a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd .: TEM26SS). , Kneaded at a temperature of 280 ° C. to obtain a polyester resin (A + C).
Further, the obtained polyester resin (A + C) was kneaded into the same polyester resin (B) as in Example 1 at a mass ratio of (A + C) / (B) = 10/90 in the same manner as in Example 1.
Then, using the obtained polyester resin composition, direct blow molding and stretch blow molding were performed in the same manner as in Example 1 to obtain a hollow container 1 and a hollow container 3.

Evaluation of composition, ultimate viscosity, moldability / recyclability of polyester resin compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 3, color tone of molded product (hollow container 1, 2, 3, 4), haze Table 1 shows the evaluation results of impact resistance.

As is clear from Table 1, the polyester resin compositions obtained in Examples 1 to 11 contained a specific amount of two types of polyester resins satisfying a specific composition and an extreme viscosity, and thus were thermally stable. It was possible to perform direct blow molding and stretch blow molding with good operability without causing the problem of whitening due to crystallization. The obtained direct blow molded product (hollow container 1) and stretch blow molded product (hollow container 3) have a uniform thickness without thickness unevenness, are not colored, have excellent color tone, and have transparency. It was a good one, and also had excellent impact resistance.
Further, it is excellent in moldability when the hollow container 1 and the hollow container 3 are crushed and recycled and used together with the unmolded polyester resin composition, and the thickness unevenness is comparable to that of the hollow containers 1 and 3. It was possible to obtain a molded product (hollow containers 2 and 4) having excellent color tone, transparency, and impact resistance.

On the other hand, the polyester resin compositions obtained in Comparative Examples 1 and 2 were inferior in impact resistance because the content of the polyester resin (A) was small. In the polyester resin composition obtained in Comparative Example 3, the content of the polyester resin (A) was too large, so that the polyester resin (A) and the polyester resin (B) could not be uniformly mixed, and molding was performed. The properties deteriorated, and the obtained molded product (hollow container 1, 2, 3, 4) had thickness unevenness.

Claims (3)

When ethylene terephthalate is the main repeating unit and the total amount of all glycol components is 100 mol%, 1,4-cyclohexanedimethanol is contained as a copolymerization component in an amount of 1 to 15 mol% , and isophthalic acid is co- containing in the acid component. When the polyester resin (A) having an ultimate viscosity of 0.5 to 1.3, which is not included as a polymerization component , and ethylene terephthalate are the main repeating units and the total amount of the total acid components is 100 mol%, isophthalic acid is co-produced. 5/95 of a polyester resin (B) having an ultimate viscosity of 0.5 to 1.3, which contains 1 to 15 mol% as a polymerization component and does not contain 1,4-cyclohexanedimethanol as a copolymerization component in the glycol component. A method for producing a polyester resin composition for a blow-molded product, which comprises adding at a mass ratio of about 40/60 and kneading with an extruder. Further, an amorphous polyester resin (C) having terephthalic acid and isophthalic acid as acid components and neopentyl glycol and ethylene glycol as glycol components was added to 100 parts by mass of the polyester resin (A) in the extruder. The method for producing a polyester resin composition for a blow-molded body according to claim 1, wherein 0.2 to 25 parts by mass is added and kneaded . The method for producing a polyester resin composition for a blow-molded article according to claim 2, wherein the amorphous polyester resin (C) is added to the polyester resin (A), and then the polyester resin (B) is added.