JPH11181063A - Polyester resin composition and molded product comprising the same composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin composition capable of carrying out the crystallization treatment of a mouth stopper part in stable quality in a short time even when the amount of a compounded reprocessed polyester fluctuates. SOLUTION: This composition comprises a polyester resin consisting essentially of ethylene terephthalate unit and having 1.5-3.5 mol.% content [DEG] of diethylene glycol unit in the total diol units and 0.70-0.90 dL/g intrinsic viscosity [η]. The crystallization temperature Tca deg.C at the time of heating up a molded product thereof satisfies conditions of formulae I and II and the Tca deg.C and the crystallization temperature Tca deg.C at the time of heating up a molded product prepared by compounding the polyester resin composition with R wt.% of a reprocessed polyester satisfy formulae III and IV. formula I:Tca :155-165 deg.C, formula II:115+40×[η]+2×[DEG]<=Tca <=133+40×[η]+2×[DEG], formula III:0 deg.C<Tca -Tcb <=5 deg.C and formula IV:(Tca -Tcb )/R<=1(0<R<=5 wt.%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin composition and a hollow container using the same. For more information,
The present invention relates to an improvement in a polyester resin composition containing repropolyester. When manufacturing a hollow container using the polyester resin composition of the present invention, even if the blending amount of the repropolyester fluctuates, the crystallization treatment of the plug can be stably performed without variation in crystallinity and dimensions. , Productivity can be improved.

[0002]

2. Description of the Related Art Since a bottle for a content liquid that requires heat filling, such as a fruit juice beverage, is required to have heat resistance, the bottle body is blow-molded in a high-temperature blow mold. 2. Description of the Related Art Conventionally, a method of heat-fixing, while heat-treating and crystallizing a plug portion to impart heat resistance has been used.

[0003] In this case, the crystallization rate of amorphous polyethylene terephthalate such as a plug is the fastest at about 180 ° C, and the crystallization rate becomes slow even if the temperature is too high or too low. It is difficult to shorten the crystallization time by changing the conditions. In order to increase the crystallization speed of the plug part, a method of using a mixture of so-called repropolyester obtained by pulverizing a product once molded into a bottle, a preform, etc., into an unused raw material as a raw material for injection molding has been conventionally used. Has been adopted.

[0004]

However, in this case, the crystallization rate varies depending on the amount of the repropolyester, and the crystallinity after crystallization of the plug portion and the size of the plug portion vary. However, there is a problem in that the loss of the properties is reduced, and the loss of intentionally pulverizing the normally produced bottle or preform once produced is large. An object of the present invention is to provide a polyester resin composition that can perform crystallization treatment of a plug portion with stable quality in a short time even if the amount of repropolyester varies.

[0005]

The present inventors have made intensive studies in view of the above circumstances, and as a result, have found that a polyester resin composition satisfying specific conditions can solve the above-mentioned problems.
The present invention has been completed. That is, the gist of the present invention is: Polyester mainly composed of ethylene terephthalate units and having a ratio of diethylene glycol units [DEG] of 1.5 to 3.5 mol% of all diol units and an intrinsic viscosity [η] of 0.70 to 0.90 dl / g A resin composition, wherein the crystallization temperature T _ca ° C. of the molded article at the time of temperature rise satisfies the conditions of the formulas (1) and (2);
_The crystallization temperature T at the time of temperature rise of a molded article obtained by blending the polyester resin composition with R weight% of repropolyester at _ca ° C.
A polyester resin composition, wherein _cb ° C. satisfies the relational expressions of the formulas (3) and (4).

[0006]

T _ca : 155 to 165 ° C. (1) 115 + 40 × [η] + 2 × [DEG] ≦ T _ca ≦ 133 + 40 × [η] + 2 × [DEG] (2) 0 ° C. <T _ca − T _cb ≦ 5 ° C. (3) (T _ca −T _cb ) / R ≦ 1 (where 0 <R ≦ 5% by weight) (4)

[0007] The polyester resin composition described in section 2.1 is injection-molded to form a preform. Then, the plug portion of the preform is heated and crystallized, then biaxially stretch blow-molded and heat-fixed. Characterized in that the hollow container is characterized in that: Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester resin used in the present invention is polyethylene terephthalate mainly composed of ethylene terephthalate units. Here, polyethylene terephthalate (hereinafter referred to as “PET”) means that the ratio of oxyethylene oxyterephthaloyl units (hereinafter referred to as “ET units”) composed of terephthalic acid and ethylene glycol to all constituent repeating units is 80 equivalent% or more. It refers to a certain PET, and the PET in the present invention may contain a constituent repeating unit other than the ET unit in a range of less than 20 equivalent%. PET in the present invention is produced using terephthalic acid or a lower alkyl ester thereof and ethylene glycol as main raw materials, but as described above, other acid components and / or other glycol components may be used as a raw material in combination. .

The acid components other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid,
4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid and structural isomers thereof, malonic acid, succinic acid, adipic acid, etc. Dicarboxylic acid and derivatives thereof, p-hydroxybenzoic acid,
Oxy acids such as glycolic acid and derivatives thereof are listed.

Diol components other than ethylene glycol include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol and neopentyl glycol. Examples thereof include alicyclic glycols such as glycol and cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S.

The raw material containing terephthalic acid or its ester-forming derivative and ethylene glycol as described above is reacted with bis (β-β-ester) by an esterification reaction or a transesterification reaction in the presence of an esterification catalyst or a transesterification catalyst.
(Hydroxyethyl) terephthalate and / or an oligomer thereof are formed, and then subjected to melt polycondensation under high temperature and reduced pressure in the presence of a polycondensation catalyst and a stabilizer to obtain a polymer.

The esterification catalyst does not need to be particularly used because terephthalic acid serves as an autocatalyst for the esterification reaction. Further, the esterification reaction can be carried out in the coexistence of an esterification catalyst and a polycondensation catalyst described later, and can be carried out in the presence of a small amount of an inorganic acid or the like.
As the transesterification catalyst, alkali metal salts such as sodium and lithium, alkaline earth metal salts such as magnesium and calcium, and metal compounds such as zinc and manganese are preferably used, and manganese compounds are particularly preferable from the viewpoint of transparency. .

As the polycondensation catalyst, compounds soluble in the reaction system such as a germanium compound, an antimony compound, a titanium compound, a cobalt compound and a tin compound are used alone or in combination. As the polycondensation catalyst, germanium dioxide is particularly preferred from the viewpoint of color tone and transparency.
Examples of the stabilizer include phosphoric esters such as trimethyl phosphate, triethyl phosphate and triphenyl phosphate; phosphites such as triphenyl phosphite and trisdodecyl phosphite; methyl acid phosphate; dibutyl phosphate; and monobutyl phosphate acidic phosphorus. Phosphorus compounds such as acid esters, phosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid are preferred.

The use ratio of the above-mentioned catalyst is as follows:
Usually 5 to 2000 ppm by weight of metal in the catalyst,
It is preferably in the range of 10 to 500 ppm, and the proportion of the stabilizer used is generally 10 to 1000 ppm, preferably 20 to 100 ppm, as the weight of phosphorus atoms in the stabilizer in all the polymerization raw materials.
It is in the range of 200 ppm. The supply of the catalyst and the stabilizer can be performed at any stage of the esterification reaction or the transesterification reaction in addition to the preparation of the raw material slurry.
Furthermore, it can be supplied at the beginning of the polycondensation reaction step.

The reaction temperature during the esterification or transesterification is usually from 240 to 280 ° C., and the reaction pressure is usually from 0.2 to 3 kg / cm ² G. The reaction temperature during the polycondensation is usually from 250 to 300 ° C., and the reaction pressure is usually from 500 to 0.1 mmHg. Such an esterification or transesterification reaction and a polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. The resulting polyester has an intrinsic viscosity of usually 0.45 to 0.45.
It is 0.70 dl / g, and is formed into chips by a conventional method.
The average particle size of the polyester chips is usually 2.0 to 5.5.
mm, preferably in the range of 2.2 to 4.0 mm.

Next, the polymer obtained by melt polycondensation as described above is usually subjected to solid-state polymerization. The polymer chip to be subjected to solid-phase polymerization may be subjected to preliminary crystallization by previously heating to a temperature lower than the temperature at which solid-state polymerization is performed, and then subjected to solid-phase polymerization. Such pre-crystallization is performed by (a) heating the dried polymer chips at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. for 1 minute to 4 hours, and (b) drying the polymer chips. Under a steam or an inert gas atmosphere containing steam, usually 120 to 200
(C) a method of heating a polymer chip that has been humidified and conditioned in an atmosphere of water, water vapor or an inert gas containing water vapor at a temperature of usually 120 to 200 ° C. for 1 minute or more. Can be done by The humidity control of the polymer chip is usually performed when the water content is 100 to 100.
It is carried out so as to be in the range of 00 ppm, preferably 1000 to 5000 ppm. By subjecting the conditioned polymer chip to crystallization or solid-phase polymerization, it is possible to further reduce the amount of acetaldehyde contained in PET and the amount of impurities contained in a trace amount.

The solid phase polymerization step comprises at least one step, usually at 190 to 230 ° C., preferably at 195 to 225.
C., a polymerization temperature of usually 1 kg / cm ² G to 10 mmHg,
It is preferably carried out under a polymerization pressure of 0.5 kg / cm ² G to 100 mmHg under a flow of an inert gas such as nitrogen, argon or carbon dioxide. The solid-state polymerization time may be shorter as the temperature is higher, but is usually 1 to 50 hours, preferably 5 to 30 hours, and more preferably 10 to 25 hours. The intrinsic viscosity of the polymer obtained by solid-state polymerization is usually in the range of 0.70 to 0.90 dl / g.

In the present invention, the content of diethylene glycol (hereinafter abbreviated as "DEG") constituting the polyester resin finally obtained by the above method is 1.5 to 3 with respect to all diol units constituting the polyester. .
It is 5 mol%, preferably 1.7 to 3.0 mol%. D
If the EG amount is too small, the transparency of the bottle body after molding deteriorates, and if it is too large, the heat resistance decreases,
Further, the crystallization promoting effect is reduced. DEG within the above range
As a method of adjusting the amount, in addition to using DEG as a polymerization raw material, DEG is partially produced as a by-product from ethylene glycol used as a main raw material. Therefore, by appropriately selecting reaction conditions, additives, and the like, the amount of by-product can be reduced. Can be adjusted.

Examples of the above-mentioned additives include tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine, and hydroxides such as tetraethylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide. Basic compounds such as quaternary ammonium, lithium carbonate, sodium carbonate, potassium carbonate, and sodium acetate are exemplified. By adding these small amounts, the generation of DEG can be suppressed. On the other hand, if a small amount of an inorganic acid such as sulfuric acid or an organic acid such as benzoic acid is added to the raw material for polymerization, the production of DEG can be promoted and the content thereof can be increased. The above-mentioned additives for controlling the amount of DEG produced are usually added as necessary.
0.001 to 10% by weight of the total polymerization raw material, preferably 0.1 to 10% by weight.
It is used in the range of 005 to 1% by weight.

The cyclic trimer (hereinafter abbreviated as “CT”) content in the finally obtained polyester resin is as follows:
It is at most 0.5% by weight, preferably at most 0.4% by weight, more preferably at most 0.35% by weight. When the content exceeds 0.5% by weight, contamination of a mold or the like is remarkably observed, and the body of the molded body is easily whitened. The CT amount can be reduced by increasing the solid-state polymerization temperature and further increasing the polymerization time.

Further, in order to enhance the effect of reducing CT, the concentration of terminal carboxyl groups in the polymer after the melt polycondensation subjected to solid-state polymerization is preferably in the range of 10 to 30 eq / ton. It is particularly preferred to be in the range of 25 eq / ton. When the concentration of the terminal carboxyl group is less than the above range, it is necessary to take a long time to increase the intrinsic viscosity due to poor solid phase polymerizability. In some cases, the effect of reducing oligomers such as CT when subjected to polymerization is small.

When the polyester resin as described above comes into contact with polyethylene (hereinafter abbreviated as “PE”) when the temperature of the polymer chip is in the temperature range of 120 to 150 ° C. after the solid-phase polymerization, the molded article is formed. It is possible to obtain a polyester resin whose crystallization speed is stable and moderately high, and whose crystallization speed hardly changes depending on the repropolyester content. Further, the crystallization rate can be controlled by changing the frequency of contact with PE.

The repropolyester to be blended with the polyester resin is obtained by pulverizing a molded product obtained by once molding a polyester resin composition into a preform or a bottle. In a specific example, for example, a preform obtained by injection molding is crystallized in a plug portion, and after reheating, a bottle is formed by blow molding in a blow mold adjusted to a temperature of 130 ° C.
The bottle was made with a diameter of 4 by VC-360 manufactured by Horai Iron Works.
It is obtained by crushing to a size that passes through a wire mesh having a hole of mm.

The amount of the repropolyester is more than 0 and not more than 5% by weight, preferably 1 to 3% by weight, based on the polyester resin. Even if the content exceeds 5% by weight, the effect of increasing the crystallization rate of the plug portion tends to be saturated, which is not economical. The polyester resin used for injection molding is not particularly limited, and may be in contact with PE as described above or not.

The polyester resin composition of the present invention comprises 28
The crystallization temperature (hereinafter abbreviated as “Tc”) at the time of temperature rise when the molded product obtained by injection molding at a molding temperature of 0 ° C. is measured by a differential scanning calorimeter is in the range of 155 to 165 ° C. It is necessary to be. When Tc is less than the above range, when the body of the preform obtained by molding is heated for blow molding, whitening due to crystallization is likely to occur and a preform temperature for imparting sufficient heat resistance is obtained. Heating may not be sufficient, and the heat resistance may be insufficient, or the shoulder and the trunk may be whitened and the transparency may be impaired. On the other hand, when Tc exceeds the above range, heating is required for a long time in order to heat and crystallize the plug portion to the desired degree of crystallinity, so that the productivity decreases and the plug portion crystallization equipment has to be enlarged. Will be. By satisfying the above condition of Tc, the crystallinity and transparency of the molded article and the heat resistance imparted to the bottle can all be satisfied at the same time.

The polyester resin composition of the present invention can be formed into a bottle by employing a commonly used melt molding method. Specifically, for example, a parison is once formed by injection molding or extrusion molding, and after being processed as it is or after the plug portion and the bottom portion are reheated, a stretch blow molding method such as a hot parison method or a cold parison method is applied. I do. In this case, the molding temperature (specifically, the temperature of each part of the cylinder of the molding machine and the nozzle) is usually 260 to 300 ° C, and the stretching temperature is usually 70 to 120 ° C. The stretching ratio is usually 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction.

Although the obtained bottle can be used as it is, especially in the case of a content liquid which requires hot filling such as fruit juice drink, oolong tea, etc., it is generally heat-fixed in a heated blow mold and further heat-resistant. To be used. Heat setting is
Normally, the mold temperature is set to 100 to 200 under tension caused by compressed air or the like.
C. for several seconds to several minutes. Alternatively, a method is also employed in which a bottle larger than the final shape is formed, and the body is crystallized by being shrunk by heating, followed by blow molding in a mold having the final shape to obtain a product bottle.

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples without departing from the scope of the invention. The methods for measuring various physical properties of the polyester resin and the molded article are as follows. (1) Intrinsic viscosity (hereinafter referred to as "IV") A sample was prepared by mixing phenol / tetrachloroethane (weight ratio 1 /
Dissolve in the mixed solvent of 1) at a concentration of 1 g / 100 ml,
At a temperature of 30 ° C., the solution viscosity is measured using an Ubbelohde capillary viscometer, then the mixed solvent is gradually added, the solution viscosity on the low concentration side is measured, and the IV is determined by extrapolating to 0% concentration. Was.

(2) Crystallization temperature As a sample, a molded product obtained by injection molding a polyester resin composition at a molding temperature of 280 ° C. is used. In this case, a preform before crystallization of a plug portion is used. 10 mg was used around the screw thread start position on the top surface of the plug section. The sample was cut into slices with a cutter knife and cut out without applying shear stress. The sample pan used was an aluminum open pan (normal pressure type). The measurement is
Differential scanning calorimeter (“DSC22” manufactured by Seiko Denshi Co., Ltd.)
0C ") at room temperature from room temperature to 285
The apex temperature of an exothermic peak due to crystallization observed while the temperature was raised to ° C. was defined as a crystallization temperature during temperature increase (Tc).

(3) DEG Amount 4N-KOH methanol solution 50 was added to 5.0 g of PET sample.
Then, the mixture was heated under reflux with stirring to hydrolyze. The diol component produced by the operation was quantified by gas chromatography. (4) CT amount 200 mg of a PET sample was dissolved in 2 ml of a mixed solution of chloroform / hexafluoroisopropanol (volume ratio: 3/2), and further diluted with 20 ml of chloroform. A sample was reprecipitated by adding 10 ml of methanol thereto, and then filtered to obtain a filtrate. After the filtrate was dried, the residue was dissolved in 25 ml of dimethylformamide and analyzed and quantified by liquid chromatography.

(5) Crystallization of the plug part The raw material PET is dried by a vacuum dryer at 130 ° C. for 12 hours, then transferred to a hopper dryer having an air temperature set at 130 ° C., and supplied to an injection molding machine. Temperature of each part of cylinder and nozzle head is 280 ° C, screw rotation speed is 120r
pm, an injection time of 12 seconds, a cooling time of 18 seconds, a primary pressure time of 1.0 second, a back pressure of 5 kg / cm ² , and a mold cooling water temperature of 20 ° C. (stock)
FE-80S) with a product weight of 60g (length 165m)
m, a plug part inner diameter of 22 mm, a plug part thickness of 2 mm, and a body part thickness of 3.7 mm) are molded into a preform for a 1.5 L bottle, and the temperature near the plug part of the preform is made with a near-infrared quartz heater. The temperature was adjusted to 180 ° C., and the preform was heated for 90 seconds while rotating the preform by a plug crystallization apparatus. Then, a mold pin having an outer diameter of 21.8 mm was inserted under the fogger to plug and crystallize the plug. Then, the density of the thread start position on the top surface of the plug and the height from the top surface to the support ring were evaluated.

(6) Density measurement A density gradient tube in which sodium bromide is dissolved in a mixed solution of water / ethanol (weight ratio: 8/1) (density range: 1.33 to 1.3).
41) was prepared and measured at a value of 3 hours after charging at a temperature of 25 ° C. (7) Heat resistance of the bottle The preform crystallized at the plug is heated for 75 seconds in a preheating furnace using a near-infrared quartz heater, and then left to cool for 25 seconds without heating to reduce the preform surface and inner surface temperature to 95%. ° C
And stretched twice in the height direction by a stretching rod in a blow mold. Before the stretching in the height direction is completed, 7 kg /
for one second blow-molding the primary blow pressure of cm ^2, was then performed for 15 seconds blow molding in the secondary blow pressure of 30kg / cm ^2. Mold temperature is 130 at the start of primary blow
At 5 ° C., the cooling of the blow mold was started 5 seconds after the start of the secondary blow, and at the end of the secondary blow, the mold temperature was set to 100 ° C. so that the average body thickness was 0.4 mm and the internal volume was 1.5 liters. The bottle was molded, filled with hot water at 85 ° C. at a rate of 2.5 L / min, allowed to stand for 5 minutes, cooled in 10 ° C. water for 30 minutes, and visually checked for deformation.

Example 1 (See Table 1 for detailed physical properties) 130.0 kg of terephthalic acid and ethylene glycol 5
8.2 kg of a slurry was prepared, and 3.0 kg of bis (2-hydroxyethyl) terephthalate was previously added thereto and supplied to the esterification tank maintained at a temperature of 250 ° C. in order over 4 hours. After completion of the supply, the esterification reaction was allowed to proceed for 1 hour, and then half of the mixture was transferred to a polycondensation tank, and 9.1 g of phosphoric acid was added.
(Relative to polymer 120 ppm), germanium dioxide 9.
2 g (relative to the polymer of 120 ppm) was charged, the temperature was gradually increased from 250 ° C. to 278 ° C., and the pressure was gradually reduced from normal pressure, and the pressure was maintained at 0.5 mmHg.

After the reaction was carried out for 3 hours, the produced polymer was discharged in a strand form from a discharge port provided at the bottom of the polycondensation tank, cooled with water, and then cut into chips. Next, the above-mentioned polymer chip surface was crystallized at 190 ° C. by a stirring crystallization machine (Bepex's formula), and then transferred to a stationary solid-state polymerization tower under a nitrogen flow of 20 L / kg · hr. 1
After drying at 40 ° C. for 3 hours, solid phase polymerization was performed at 210 ° C. for 20 hours to obtain a solid phase polymerization chip.

After the solid-phase polymerization, the chip is heated at a chip temperature of 140.
When the temperature is around ℃, it is made of PE (“UE320” made by Nippon Polychem)
After contacting through piping, cool to room temperature and
did. The above raw material chip alone and the above raw material chip
Raw polyester mixed with 3% by weight dry blend
And injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.)
The preform was molded by "FE-80S"). here
In the preform formed from raw material chips,
Temperature is T_caThe raw material chips are repropolyester
Of preforms formed from raw materials
The crystallization temperature is T_cbIt is. At this time, T_ca= 16
1.5 ° C, T_ca-T_cb= 0.9 ° C, (T_ca-T _cb) / R
= 0.3.

As a result of heating and crystallizing 20 plug portions of the preform using the raw material chips with a crystallizer manufactured in-house and measuring the density and dimensions, the density was sufficiently high and the variation in the dimensions was small and stable. The plug portion could be crystallized. Similarly, using a preform that has been heated and crystallized, the body average thickness was 0.4 m at a mold temperature of 130 ° C. using an in-house stretch blow machine.
m, a heat-resistant bottle having an inner volume of 1.5 L was molded, and the appearance of the bottle was observed.
In addition, observation after filling with hot water of 85 ° C. and cooling with the plug tightly revealed no deformation or liquid leakage in the plug, shoulder, trunk, and the like. Further, 1,000 bottles were continuously molded, but no stain was observed in the blow mold.

Example 2 Polymerization, molding and evaluation were carried out in the same manner as in Example 1 except that the blending amount of the repropolyester was changed to 5% by weight. The whitening of the bottle and the stain on the mold were satisfactory without any problem. At this time, T
_ca = 161.7 ° C., T _ca −T _cb = 2.0 ° C., (T _ca −T
_cb ) /R=0.4. Example 3 In Example 1, an addition was made so that the amount of DEG in the product was 3.5 mol% of all diol units, and the IV was 0.90 dl /
g, and polymerization, molding and evaluation were carried out in the same manner as in Example 1 except that the solid phase polymerization time was 40 hours and the blending amount of repropolyester was 1% by weight. The treatment, heat resistance, whitening of the bottle, and stain on the mold were satisfactory without any problem. At this time, T _ca = 163.2 ° C., T _ca −T
_cb = 0.8 ° C., (T _ca −T _cb ) /R=0.8.

Comparative Example 1 Polymerization, molding, and evaluation were performed in the same manner as in Example 1 except that the PE pipe was changed to stainless steel. Was not seen,
The density after the crystallization of the plug portion is large, and the dimensional change is also large, so that there is no problem with the heat resistance of the body portion when the heat resistance is evaluated, but there were bottles that leaked from the plug portion.
At this time, T _ca = 172.5 ° C., T _ca −T _cb = 8.1 ° C.
It was (T _ca -T _cb) /R=2.7.

Comparative Example 2 Polymerization, molding and evaluation were carried out in the same manner as in Example 1 except that the amount of DEG in the product was 5.0 mol% in all diol units. However, there were no problems with the crystallization treatment of the plug, the whitening of the bottle, and the stain on the mold, but the heat resistance was poor and deformation of the bottle body cooled after filling with hot water was observed. At this time, T _ca = 163.2 ° C., T _ca −T _cb =
3.6 ° C., (T _ca −T _cb ) /R=1.2.

Comparative Example 3 In Example 1, antimony trioxide was added in place of germanium dioxide in an amount of 200 ppm based on the polymer, and the amount of phosphoric acid was changed to 125 ppm based on the polymer.
Polymerization, molding, and evaluation were performed in the same manner as in Example 1. Although there was no problem with the plug portion crystallization treatment and mold contamination, whitening occurred during heating of the preform body, and the same conditions as in Example 1 were used. Bottle molding failed. The heat resistance was evaluated under the condition that the transparent bottle can be molded by lowering the output of the heater.
After filling with hot water, deformation of the cooled bottle body was observed.
At this time, T _ca = 145.0 ° C., T _ca −T _cb = 0.9 ° C.
It was (T _ca -T _cb) /R=0.3.

Comparative Example 4 In Example 1, the temperature of the solid phase polymerization was 215 ° C., and the time was 1
Except for 4 hours, polymerization, molding,
Although evaluation was performed, there was no problem in the crystallization treatment of the plug portion, the heat resistance, and the whitening of the bottle. At this time, T _ca = 161.9 ° C., T _ca −T _cb =
1.5 ° C., (T _ca −T _cb ) /R=0.5.

[0042]

[Table 1]

Heat resistance test: ：: Filled with hot water and the bottle after cooling is free from deformation and leakage ×: Filled with hot water and deformed and leaked after cooling Bottle appearance:…: Deformed and turbid Good: no turbidity ×: turbidity in the body part Mold stains: ○: No change on the mold surface before and after 1000 moldings ×: Adhesion on the mold surface after 1000 moldings

[0044]

According to the present invention, it is possible to provide a polyester resin composition capable of performing the plug crystallization treatment with a stable quality in a short time even if the amount of the repropolyester varies.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 67/02 C08L 67/02 // B29K 67:00 B29L 22:00

Claims (4)

[Claims] 1. A composition mainly comprising ethylene terephthalate units, the proportion of diethylene glycol units [DEG] is 1.5 to 3.5 mol% of all diol units, and the intrinsic viscosity [η] is 0.70 to 0.90 dl. / G of a polyester resin, wherein the molded product has a crystallization temperature T _ca ° C. at the time of temperature rise satisfying the conditions of the formulas (1) and (2), and the T _c ° C. A polyester resin characterized in that the molded product obtained by blending R weight% of repropolyester with the resin composition and the crystallization temperature T _cb ° C at the time of heating satisfies the relational expressions (3) and (4). Composition. T _ca : 155 to 165 ° C. (1) 115 + 40 × [η] + 2 × [DEG] ≦ T _ca ≦ 133 + 40 × [η] + 2 × [DEG] (2) 0 ° C. <T _ca − T _cb ≦ 5 ° C. (3) (T _ca −T _cb ) / R ≦ 1 (where 0 <R ≦ 5% by weight) (4) 2. The polyester resin composition according to claim 1, wherein the content of the cyclic trimer is 0.5% by weight or less. 3. A preform formed by injection molding of the polyester resin composition according to claim 1. 4. A hollow container, wherein the plug portion of the preform according to claim 3 is heated and crystallized, and then biaxially stretch blow-molded and thermally fixed.