JP2010150488A - Ethylene terephthalate based polyester resin for molding heat-resistant container and preform consisting of the resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin in which monomers such as monohydroxyethyl terephthalate (MHET) and bishydroxyethyl terephthalate (BHET) are reduced to prevent problems from occurring at the time of molding a container. <P>SOLUTION: The polyester resin is characterized in that intrinsic viscosity is in a range of 0.65 to 0.80 dL/g, total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate is less than 0.005 wt.%, acetaldehyde concentration is 2 to 10 ppm, the peak time of crystallization in isothermal crystallization at 210°C is 360 seconds or less and the crystallization energy (ΔH) is 30 J/g or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ethylene terephthalate-based polyester resin, and more specifically, an ethylene terephthalate-based polyester resin for molding a heat-resistant container having a reduced content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate, and the resin. Regarding preform.

Containers made of a polyester resin typified by polyethylene terephthalate are widely used as containers for beverages, oils, seasonings and the like because of their excellent properties such as transparency and mechanical strength.
As a polyester resin used for container molding, a polyester resin obtained by melt polymerization or a polyester resin obtained by solid-phase polymerization after melt polymerization is generally used.
Polyester resins produced by melt polymerization are less expensive than polyester resins of the same intrinsic viscosity obtained through solid phase polymerization, and are monohydroxyethyl terephthalate (hereinafter simply referred to as “MHET”) or bishydroxyethyl. The content of a monomer having a low melting point such as terephthalate (hereinafter simply referred to as “BHET”), an oligomer such as a cyclic trimer, a volatile component such as acetaldehyde, and a low molecular weight component having a molecular weight of 10,000 or less undergoes solid phase polymerization. It has the characteristic that there are many compared with the polyester resin of the equivalent intrinsic viscosity obtained.

  When the container is molded using a polyester resin containing a large amount of such monomers and oligomers, the monomers and oligomers in the polyester resin are precipitated during molding, and the presence of MHET and BHET causes the compression molding. In this case, it becomes difficult to accurately supply the molten resin lump to the cavity by adhering to the surface of the drop conveyance mold, resulting in poor productivity, and in the case of injection molding, the mold Oligomer such as a cyclic trimer adheres to the air vent port and becomes clogged, and frequent cleaning is required. Furthermore, when heat setting is performed to impart heat resistance to the container, the cyclic trimer adheres to the mold surface due to the presence of the MHET and BHET, causing a decrease in transparency due to rough skin. Or there was a problem such as frequent cleaning of the mold.

  As a solution to such a problem, for example, in Patent Document 1 below, a polyester resin composition is brought into contact with water at 50 ° C. or higher and 110 ° C. or lower for 5 minutes or longer and 5 hours or shorter, and 110 ° C. or higher and 180 ° C. or lower. A method for producing a polyester resin composition has been proposed, which is maintained for 3 hours or more in a state where the pressure is reduced to 4 kPa or less at a temperature of 5 ° C.

JP 2001-121273 A

In the above-mentioned Patent Document 1, the catalyst present in the polyester resin is deactivated by hot water treatment, and further heat treatment is required. Therefore, the number of steps is large, and it is not sufficiently satisfactory in terms of economy.
In addition, MHET, BHET, cyclic trimer, acetaldehyde, etc. are reduced in the polyester resin subjected to solid phase polymerization after melt polymerization, but it is expensive and economical in terms of use for general purpose containers. There's a problem. In addition, the polyester resin pellets subjected to solid-phase polymerization have high crystallinity and poor meltability, and therefore, during melt molding, the molded product becomes cloudy due to the presence of unmelted components. In order to prevent this, if the molding temperature is set to a high temperature, a problem that the resin deteriorates is caused. Furthermore, since it has the characteristic that the crystallization speed | rate of resin is slow, it is difficult to perform efficiently the crystallization and heat setting of a mouth part performed in manufacture of a heat resistant container.

Accordingly, an object of the present invention is to provide a polyester resin in which monomers such as MHET and BHET are reduced and the above-mentioned problems that occur during container molding do not occur.
Another object of the present invention is to provide a preform that can efficiently crystallize and heat-set the mouth and can form a heat-resistant container excellent in productivity and economy.
Still another object of the present invention is to provide a preform capable of forming a heat-resistant container having a reduced acetaldehyde concentration and excellent flavor properties.

According to the present invention, the intrinsic viscosity is in the range of 0.65 to 0.80 dL / g, the total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate is less than 0.005% by weight, and the acetaldehyde concentration Is an ethylene terephthalate system for molding heat-resistant containers, characterized in that the crystallization peak time in isothermal crystallization at 210 ° C. is 360 seconds or less and the crystallization energy (ΔH) is 30 J / g or more. A polyester resin is provided.
According to the invention, the intrinsic viscosity is in the range of 0.65 to 0.80 dL / g, the total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate is less than 0.005% by weight, and acetaldehyde An ethylene terephthalate-based polyester resin for forming a heat-resistant container is provided, which has a concentration of 2 to 10 ppm and a molecular weight component of 10,000 or less is 8% or more.
In the polyester resin of the present invention, the total amount of diethylene glycol and isophthalic acid contained as copolymerization components is preferably 1.5% by weight or less.

According to the present invention, it is also composed of the above-mentioned ethylene terephthalate polyester resin, has an intrinsic viscosity in the range of 0.65 to 0.80 dL / g, and has a total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate of 0. .010% by weight, the acetaldehyde concentration is 15 ppm or less, the peak time of crystallization in isothermal crystallization at 210 ° C. is 60 seconds or less, and the crystallization energy (ΔH) is 20 J / g or more. A preform is provided.
In the preform of the present invention, the total amount of diethylene glycol and isophthalic acid contained as copolymerization components is preferably 2.7% by weight or less.
According to the present invention, the ethylene terephthalate-based polyester resin obtained by melt polymerization is further subjected to a heat treatment at a temperature of 170 to 200 ° C. for 1 hour or more and less than 5 hours. Is provided.

  In the ethylene terephthalate-based polyester resin for molding a heat-resistant container of the present invention, among the oligomer component such as a cyclic trimer and the monomer component serving as a binder for the polymer component, MHET which is considered to cause adhesion particularly at a low melting point and Since BHET has been reduced, problems that have occurred during container molding in the past, that is, resin adheres to the surface of the conveying mold during compression molding, resulting in a decrease in moldability, and mold during injection molding. Resin clogs the mold's air vent and requires frequent cleaning, or cyclic trimer or resin adheres to the mold surface during heat setting, leading to reduced transparency due to rough skin. Or the need to frequently clean the mold does not occur.

Further, in the ethylene terephthalate-based polyester resin for molding heat-resistant containers of the present invention, the peak time of crystallization in isothermal crystallization at 210 ° C. is 360 seconds or less, and the peak time of crystallization of the polyester resin obtained through solid-phase polymerization ( For example, as apparent from the fact that it is shorter than Comparative Examples 7 to 9) to be described later, it is easy to crystallize, and since the crystallization energy (ΔH) is as large as 30 J / g or more, the crystal is likely to grow. The crystallization speed is fast, the mouth crystallization and heat setting necessary for forming the heat-resistant container can be performed efficiently, and the molding can be performed with high productivity and economy.
Note that the crystallization peak time and the crystallization energy isothermal crystallization measurement standard are 210 ° C because the mouth crystallization temperature of the preform made of the polyester resin of the present invention is around 210 ° C. This is because the crystallization characteristics in this temperature range are related to the crystallization time of the preform mouth.
Furthermore, in the ethylene terephthalate polyester resin for molding heat-resistant containers of the present invention, a low molecular weight component having a molecular weight of 10,000 or less is contained in an amount of 8% or more, and the low molecular weight component having a molecular weight of 10,000 or less is used as a crystal nucleating agent. Therefore, the crystallization speed is high, and the mouth crystallization and heat setting can be efficiently performed.

That is, the crystallization time and ultimate crystallinity (χc) of the mouth of the preform made of the polyester resin of the present invention (Example 1) and the preform made of the polyester resin obtained through solid phase polymerization (Comparative Example 7). As is clear from FIG. 1 showing the relationship of), the preform made of the polyester resin of the present invention takes only about 70 seconds to reach a crystallinity of 0.30, whereas it undergoes solid-state polymerization. In the obtained polyester resin, it takes 90 seconds or more for the crystallinity to reach 0.30, and it is clear that the preform made of the polyester resin of the present invention can be efficiently crystallized at the mouth.
Further, since the polyester resin of the present invention is not high in the crystallinity of the pellet as in the polyester resin obtained through solid phase polymerization, the diffusion rate of acetaldehyde from the inner surface to the outer side of the pellet does not slow down, Acetaldehyde can be reduced in a short time even in a treatment at a lower temperature than the polymerization. Furthermore, it has good meltability and its melting point end temperature is lower than that of polyester resin by solid-phase polymerization, so it can be molded at low temperature, and preforms or containers can be molded without increasing MHET, BHET and acetaldehyde. can do.

Furthermore, the polyester resin of the present invention can be blended with a polyester resin other than the polyester resin of the present invention and used for preform molding.
For example, a preform formed using a blend with a polyester resin obtained through solid-phase polymerization (Example 6) or a blend with a melt-polymerized polyester resin (Example 7) is used as the polyester resin of the present invention. Despite the fact that only a small amount is used, it is possible to have the same characteristics as a preform made of only the polyester resin of the present invention, and the polyester resin obtained through solid phase polymerization can be efficiently crystallized. Can be accelerated.
Furthermore, since the acetaldehyde concentration of the polyester resin of the present invention is reduced to 15 ppm or less, a container molded using the polyester resin has excellent flavor properties.
Moreover, in the manufacturing method of the polyester resin of this invention, it becomes possible to manufacture the polyester resin which has the characteristic mentioned above using the general purpose polyester resin by melt polymerization.

(Synthesis of polyester resin)
The ethylene terephthalate-based polyester resin of the present invention is subjected to heat treatment described later after melt polymerization, has an intrinsic viscosity in the range of 0.65 to 0.80 dL / g, and a total content of MHET and BHET of 0.005. The molecular weight is less than wt%, the acetaldehyde concentration is 2 to 10 ppm, the peak time of crystallization in isothermal crystallization at 210 ° C. is 360 seconds or less, and the crystallization energy (ΔH) is 30 J / g or more, or 10,000 or less. It can be prepared by a conventionally known polyester resin synthesis method except that the component is 8% or more.
That is, it can be obtained by subjecting a raw material mainly composed of terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative to melt polymerization in the presence of a catalyst.

  The synthesis of the polyester resin is generally performed by a method of directly reacting high-purity terephthalic acid (TPA) and ethylene glycol (EG) to synthesize polyethylene terephthalate (PET), and is usually divided into two steps. A) A step of reacting TPA and EG to synthesize BHET or a low polycondensate thereof, and (B) A step of performing polycondensation by distilling off ethylene glycol from BHET or the low polycondensate thereof. .

The synthesis of BHET or a low polycondensate thereof can be carried out under conditions known per se. For example, the amount of EG with respect to TPA is 1.1 to 1.5 mole times, and the boiling point of EG or higher, for example, 220 to 260 ° C. Esterification is performed while heating to temperature and distilling water out of the system under a pressure of 1 to 5 kg / cm ² . In this case, since TPA itself becomes a catalyst, a catalyst is usually not necessary, but a known esterification catalyst can also be used.

  In the second stage polycondensation step, a known polycondensation catalyst is added to BHET obtained in the first stage or a low polycondensate thereof, and then the pressure is gradually increased while maintaining the reaction system at 260 to 290 ° C. The reaction is allowed to proceed, while stirring under reduced pressure of 1 to 3 mmHg and finally distilling the produced EG out of the system. The molecular weight is detected based on the viscosity of the reaction system. When the molecular weight reaches a predetermined value, it is discharged out of the system to form a chip after cooling. As the polycondensation catalyst, germanium compounds such as germanium dioxide, titanium compounds such as tetraethyl titanate, antimony compounds such as antimony trioxide, etc. are generally used. However, using a titanium compound or an antimony compound can improve the efficiency of the polycondensation reaction. It is preferable in terms of economy.

  In the polyester resin of the present invention, it is a polyester resin mainly composed of ethylene terephthalate units, that is, 50 mol% or more of ester repeating units are composed of ethylene terephthalate units, but most of the ester repeating units are generally 70 mol% or more, Particularly preferred are those in which ethylene terephthalate units occupy 80 mol% or more, glass transition point (Tg) of 50 to 90 ° C., particularly 55 to 85 ° C., melting point (Tm) of 200 to 270 ° C., particularly 220 to 265 ° C. It is preferable that it exists in.

In the polyester resin of the present invention, a small amount of ester units other than ethylene terephthalate units is important in order to have the above-described crystallization characteristics and molecular weight distribution, and particularly when diethylene glycol and isophthalic acid are included as copolymerization components. In addition, the total amount of these is preferably 1.5% by weight or less.
Other copolymer components include dicarboxylic acid components, aromatic dicarboxylic acids such as phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. Or a combination of two or more of the following: As the diol component, propylene glycol, 1,4-butanediol, 1,6-hexylene glycol, cyclohexanedimethanol, ethylene of bisphenol A 1 type, or 2 or more types, such as an oxide adduct, are mentioned.

The heat treatment for crystallizing the polyester resin pelletized after the melt polymerization includes, for example, a method in a fluidized bed or a fixed bed using a heated inert gas such as heated nitrogen gas, and a method in a vacuum heating furnace. Preferably, heat treatment is performed at a crystallization temperature range of 130 to 165 ° C., particularly 140 to 160 ° C., for 130 to 200 minutes, particularly 150 to 180 minutes. Alternatively, crystallization can be performed by latent heat when pelletizing the molten polyester resin.
In the present invention, the crystallized polyester resin pellets are in a vacuum or under an inert gas atmosphere at a temperature of 170 to 200 ° C., particularly 180 to 200 ° C., for 1 hour or more and less than 5 hours, particularly 3 to 4 Heat treatment for hours. When the heating temperature is lower than the above range, MHET and BHET cannot be sufficiently reduced, and when the heating temperature is higher than the above range, the resin gels or the crystallinity of the resin pellets is low. There is a possibility that the meltability may deteriorate due to excessive rise. Further, even if the heating time is 5 hours or longer, the contents of MHET and BHET cannot be effectively reduced any more, and the productivity is lowered by the treatment over a long time.

This heat treatment can be performed in a fluidized bed or a fixed bed using, for example, a heated inert gas such as heated nitrogen gas, as in the above-described polyester resin pellet crystallization step, and is performed in a vacuum heating furnace. be able to. When using a heated inert gas, it is desirable that the oxygen concentration in the heating tank be 15% or less in order to prevent yellowing of the pellets.
By this heat treatment, MHET and BHET causing adhesion to the mold surface and the like can be reduced to less than 0.005% by weight, particularly 0.004% by weight or less, and oligomers such as cyclic trimers, Alternatively, volatile components such as acetaldehyde that cause a reduction in flavor can be reduced.

In the heat treatment in the method for producing a polyester resin of the present invention, the intrinsic viscosity hardly increases as in solid phase polymerization. As a result, the polyester resin of the present invention has an intrinsic viscosity of 0.65 to 0.80 dL / g, particularly in the range of 0.66 to 0.75 dL / g. When the intrinsic viscosity is lower than the above range, problems such as insufficient mechanical strength and impact resistance of the resulting container and a tendency to draw down the molten resin in compression molding and the like occur. On the other hand, if the intrinsic viscosity is higher than the above range, the extrudability of the molten resin is inferior, the moldability is lowered, and wrinkles due to the cutter mark may occur in compression molding or the like. In addition, since the melt viscosity is high and it is easily subjected to shearing of the screw, it is difficult to suppress the acetaldehyde content in the container and the deterioration of the resin due to melt molding to a target value or less.
In addition, the peak time of crystallization in isothermal crystallization at 210 ° C. is 360 seconds or less and the crystallization energy (ΔH) is 30 J / g or more, or the molecular weight component of 1000 or less is 8% or more. It is possible to perform heat fixation at the time of crystallization of the mouth and molding of the heat-resistant container at a low temperature and in a short time, and a preform or the like can be molded with good economic efficiency and productivity.

(preform)
The preform of the present invention can be obtained by crystallizing the mouth portion of a preform molded by a conventionally known compression molding or injection molding method using the above-described ethylene terephthalate polyester resin.
The preform of the present invention has an intrinsic viscosity in the range of 0.65 to 0.80 dL / g, a total content of MHET and BHET of less than 0.010% by weight, and an acetaldehyde concentration of 15 ppm or less. In addition, the crystallization peak time in isothermal crystallization at 210 ° C. is 60 seconds or less and the crystallization energy (ΔH) is 20 J / g or more.
The polyester resin of the present invention used for preform molding has a low acetaldehyde content because it has undergone heat treatment, and since the formation of acetaldehyde can be suppressed by performing low temperature molding, the preform of the present invention also has an acetaldehyde content. It is 15 ppm or less, and a container excellent in flavor properties can be provided.

Further, as described above, the preform of the present invention can be molded using a blend of the polyester resin of the present invention and another polyester resin.
As the polyester resin that can be used by blending with the polyester resin of the present invention, those having an intrinsic viscosity of 0.80 dL / g or more are suitable in terms of adjusting the crystallization speed, and particularly obtained through solid phase polymerization. A polyester resin that has been heat-treated with the obtained polyester resin or a polyester resin obtained by melt polymerization can be suitably used.
The blending ratio of the blend varies depending on the polyester resin to be blended and cannot be specified unconditionally, but the total amount of diethylene glycol and isophthalic acid contained as copolymerization components in the blend is 2.7% by weight or less. It is preferable to blend them.

In the preform molding by compression molding, the melt of the polyester resin of the present invention is continuously extruded by an extruder and the melt is cut by a cutting means (cutter) of a synthetic resin supply device, so that the preform is in a molten state. A molten resin lump (drop), which is a precursor molded body for use, is held by holding means (holder), and is introduced into a cavity mold of a compression molding machine via a guiding means (throat). The preform is molded by compression molding with a core mold and cooled and solidified.
In the preform molding by injection molding, the injection conditions are not particularly limited, but the bottomed preform is generally molded at an injection temperature of 260 to 300 ° C. and an injection pressure of 30 to 60 kg / cm ^2. Can do.

In the preform manufacturing method, the melt extrusion temperature of the molten polyester resin is in the range of Tm + 5 ° C. to Tm + 40 ° C., particularly Tm + 10 ° C. to Tm + 30 ° C., based on the melting point (Tm) of the polyester resin. It is preferable for forming an extrudate and preventing thermal deterioration and drawdown of the resin.
In addition, when kneading the molten resin with an extruder, it is particularly preferable to pull the vent to suppress the formation of MHET, BHET, cyclic trimer, etc., or high molecular weight components having a degree of polymerization below the entanglement point. The adhesion of the molten extrudate can be effectively suppressed, and the adhesion of the resin to the conveying means in the compression molding and the air vent port of the mold can be more effectively prevented.
As described above, since the crystallization speed of the polyester resin to be used is high, crystallization of the mouth portion of the preform can be efficiently performed in a short time.

The preform of the present invention is formed into a stretch-molded container such as a bottle or a wide-mouth cup by stretch blow molding.
In stretch blow molding, a preform molded using the polyester resin of the present invention is heated to a stretching temperature, the preform is stretched in the axial direction, and biaxially stretched blow molded in the circumferential direction to form a biaxially stretched container. Manufacturing.
The preform molding and the stretch blow molding can be applied to a hot parison system in which stretch blow molding is performed without completely cooling the preform, in addition to the cold parison system.
Prior to stretching blow, if necessary, the preform is preheated to an appropriate stretching temperature by means of hot air, an infrared heater, high frequency induction heating or the like. In the case of polyester, the temperature range is 85 to 120 ° C., particularly 95 to 110 ° C.

The preform is supplied into a publicly known stretch blow molding machine, set in a mold, stretched in the axial direction by pushing a stretching rod, and stretched in the circumferential direction by blowing a fluid. In general, the mold temperature is preferably in the range of room temperature to 230 ° C. However, as described later, when heat setting is performed by the one mold method, the mold temperature is preferably set to 120 to 180 ° C.
The draw ratio in the final polyester container is suitably 1.5 to 25 times in terms of area magnification. Among these, the axial draw ratio is 1.2 to 6 times, and the circumferential draw ratio is 1.2 to 4.5. It is preferable to double.

In the polyester resin of the present invention, since the total amount of MHET and BHET is reduced to less than 0.005% by weight, the cyclic trimer or the resin adheres to the mold surface during heat setting and is transparent due to rough skin. It is effectively prevented from causing deterioration of properties or requiring frequent mold cleaning, and can be heat-fixed with high productivity and excellent transparency of the resulting container. .
In the present invention, since the crystallization speed of the polyester resin used is high as described above, it can be heat-set efficiently in a short time. The heat setting can be performed by means known per se, can also be performed by a one-mold method performed in a blow molding die, or two molds performed in a heat fixing die separate from the blow molding die. It can also be done by law. The temperature for heat setting is suitably in the range of 120 to 230 ° C.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The physical property values used in the examples are evaluated and measured in accordance with the following methods.

1. Polymerization of melt-polymerized PET resin A total of 13 kg of high-purity terephthalic acid and isophthalic acid, 4.93 kg of ethylene glycol, and 6.88 g of a 20% aqueous solution of tetraethylammonium hydroxide were charged into an autoclave, nitrogen at a pressure of 1.7 kg / cm ² and 260 ° C. The reaction was carried out with stirring while distilling off the water produced by the reaction out of the system for 6 hours under an atmosphere. Next, 201 g of tetra-n-butyl titanate was added to the reaction system, and after stirring for 20 minutes, 1.26 g of 85% phosphoric acid was added. The temperature was raised to 280 ° C. and the pressure was reduced to 2 torr, followed by reaction for a predetermined time, and ethylene glycol was distilled off. After completion of the reaction, the strand was extracted from the reactor, cooled with water, and pelletized using a pelletizer. The amounts of high-purity terephthalic acid and isophthalic acid charged and the reaction time are summarized in Table 3.

2. Heat Treatment of PET Resin Pellets 15 kg of amorphous melt-polymerized PET resin pellets were heat treated using a stirring vacuum dryer (45 MV, manufactured by Dalton Co.). After crystallizing the PET resin pellets (3 hours under conditions of 4 mmHg and 150 ° C.), the gas introduction valve and the leak valve are opened, and the MHET and BHET are reduced under the specified conditions under a nitrogen flow. It was. The rotation speed of the stirrer was 20 rpm, and the nitrogen gas was passed through silica gel and dried, then heated to the same temperature as the MHET and BHET reduction treatment, and introduced into the stirring type vacuum dryer at a flow rate of 10 L / min.

3. Preform molding The melt-polymerized PET resin pellets after heat treatment were supplied to an injection molding machine to perform preform molding. The solid phase polymerization PET resin was dried at 150 ° C. for 4 hours instead of the above heat treatment, and then supplied to an injection molding machine to perform preform molding. The barrel temperature of the injection molding machine, the temperature of the hot runner was set to 290 ° C., the mold temperature was set to 15 ° C., the molding cycle was 25 seconds, and a preform for a 500 ml bottle weighing 28 g was produced.

4). Mouth crystallization The output of the infrared heater of the mouth crystallization apparatus was set to 1200 W for mouth crystallization. The heating time was from 20 seconds to 160 seconds at 10 second intervals. The preform after heating was rapidly cooled with room temperature water in a bucket.

5). Various measurements (1) Intrinsic viscosity 0.3 g of PET resin pellets and preforms dried at 150 ° C. for 4 hours were weighed. A mixed solvent having a weight ratio of 1,1,2,2-tetrachloroethane and phenol of 50:50 was added thereto to adjust the concentration to 1.00 g / dl, and the mixture was completely dissolved by stirring at 120 ° C. for 20 minutes. It was. The solution after dissolution was cooled to room temperature, the relative viscosity was determined using a relative viscometer (Y501, manufactured by Viscotek) adjusted to 30 ° C., and the intrinsic viscosity was calculated.

(2) Total content of MHET and BHET 0.5 g of PET resin pellets and preform were weighed, and the weight ratio of 1,1,1,3,3,3-hexafluoro-2-isopropanol / chloroform was 50 : 30 ml of 50 mixed solvent was added and completely dissolved. After adding 20 ml of chloroform to this solution, 300 ml of tetrahydrofuran was gradually added and left for 4 hours to precipitate a PET polymer. This suspension was filtered with a filter paper, and the filtrate was concentrated with an evaporator until just before drying. 5 ml of dimethylformamide (DMF) was added to the concentrated solution and allowed to stand overnight, then DMF was added to make up to 10 ml in a measuring flask, and again left overnight. This solution was filtered through a membrane filter having a pore diameter of 0.45 μm, and the filtrate was measured by high performance liquid chromatography. At the same time, a standard solution of cyclic trimer was also measured, and based on the obtained calibration curve, the total content of MHET and BHET in the pellet and preform was calculated in terms of cyclic trimer.

(3) Acetaldehyde concentration 1.0 g of PET resin pellets and preform crushed samples crushed by a freeze pulverizer were weighed into a glass bottle, and 5.0 ml of pure water was added and sealed. The suspension was heated in an oven adjusted to a temperature of 120 ° C. for 60 minutes and then cooled in ice water for 10 minutes. 3.0 ml of the supernatant of the suspension was collected, and 0.6 ml of a 0.1% strength 2,4-dinitrophenylhydrazine / phosphoric acid solution was added to the suspension, which was allowed to stand for 30 minutes. The supernatant after standing was filtered through a membrane filter having a pore diameter of 0.45 μm, and the filtrate was measured by high performance liquid chromatography. At the same time, a calibration curve was also measured using a standard solution of acetaldehyde (Acetaldehyde-DNPH, Sigma-Aldrich Japan Co., Ltd.), and the acetaldehyde concentration in the pellet and preform was calculated based on the obtained calibration curve.

(4) Crystallinity of the mouth of the preform After cutting into a 4 mm square from the neck ring part of the preform crystallized by the mouth, the density was measured, and the crystallinity was determined by the density method of the following formula.
Crystallinity χc = {[ρc × (ρ−ρa)] / [ρ × (ρc−ρa)]}
ρ: measured density (g / cm ³ )
ρa: amorphous density (1.335 g / cm ³ )
ρc: Crystal density (1.455 g / cm ³ )
Density measurement was performed under the condition of 20 ° C. using a calcium nitrate solution-based density gradient tube (manufactured by Ikeda Rika Co., Ltd.).

(5) Differential scanning calorimetry (DSC)
The crystallization peak time and crystallization energy at 210 ° C. of the PET resin pellet and preform were measured using a differential scanning calorimeter (Diamond DSC, manufactured by PerkinElmer). 8 mg of PET resin pellets and preforms were weighed and used as samples.
The measurement conditions are as follows.
PET resin pellet (1) Hold at 20 ° C. for 3 minutes (2) Increase from 300 ° C./min from 20 ° C. to 290 ° C. (3) Hold at 290 ° C. for 3 minutes (4) 300 ° C./from 290 ° C. to 210 ° C. Decrease in temperature (5) Hold at 210 ° C for 30 minutes

Preform (1) Hold at 20 ° C. for 3 minutes (2) Temperature rise from 20 ° C. to 210 ° C. at 300 ° C./min (3) Hold at 210 ° C. for 3 minutes PET resin pellet is (5), preform is (3 The crystallization peak time was determined from the isothermal crystallization curve in the scan of), and the crystallization energy was determined from the peak area.

(6) Measurement of copolymer component content PET resin pellets and preforms dried at 150 ° C. for 4 hours were dissolved in a mixed solvent having a weight ratio of deuterated trifluoroacetic acid / deuterated chloroform of 50:50, and an NMR apparatus (EX270 : JEOL Datum Co., Ltd.) 1H-NMR spectrum was measured, and from the ratio of integral values of proton peaks derived from the diethylene glycol (DEG) site, isophthalic acid (IPA) site and terephthalic acid site, the values of DEG and IPA The content rate was calculated. The content did not change by heat treatment and preform molding, and when blended with PET resin pellets, the content was determined by weighted average.

(7) Measurement of molecular weight component content of 10000 or less 5 mg of a PET resin piece in 5 ml of a mixed solvent having a weight ratio of 1,1,1,3,3,3-hexafluoro-2-isopropanol and chloroform of 50:50 After complete dissolution, gel permeation chromatography (GPC; Integrated System For GPC / SEC: Asahi Techneion Co., Ltd.), equipped with a light scattering detector, differential refractometer, and differential pressure viscosity detector as a detector. An integral curve of molecular weight distribution was obtained using Detector Module TriSEC Model 302 (manufactured by Viscotek), and the content of molecular weight components of 10,000 or less was calculated.

(8) Evaluation of heat-resistant blow mold surface contamination Using the preform crystallized at the mouth by the above-mentioned method, biaxial stretch blow molding by a single-stage blow molding method is performed, and then at 150 ° C. for 2 seconds. And heat-set to produce a heat-resistant PET bottle. After the bottle molding was repeated 5000 times, the surface of the heat-resistant blow mold was observed, and the case where it could be used continuously was evaluated as “◯”, and the case where the surface was extremely dirty and could not be used was evaluated as “x”.

Example 1
An amorphous melt having an intrinsic viscosity of 0.68 dL / g, a total content of MHET and BHET of 0.0101 wt%, an acetaldehyde concentration of 44.3 ppm, and a copolymerization content of DEG of 1.3 wt% Polymerized PET resin pellets were used to crystallize the pellets, and then MHET and BHET were reduced at 170 ° C. for 4 hours. After the heat treatment, the intrinsic viscosity of the pellet, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Example 2)
The pellet intrinsic viscosity, isothermal crystallization peak time at 210 ° C. and isothermal crystallization energy, MHET and the like, except that MHET and BHET were reduced at 180 ° C. after the pellet was crystallized. The total content of BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Example 3)
Inherent viscosity of pellets, isothermal crystallization peak time at 210 ° C. and isothermal crystallization energy, MHET and MHET and BHET were reduced at 200 ° C. after crystallizing the pellets, as in Example 1. The total content of BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

Example 4
An amorphous melt having an intrinsic viscosity of 0.79 dL / g, a total content of MHET and BHET of 0.0053 wt%, an acetaldehyde concentration of 28.0 ppm, and a copolymerization content of DEG of 1.0 wt% Except for using polymerized PET resin pellets, the intrinsic viscosity of the pellets, isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., total content of MHET and BHET, acetaldehyde concentration, and molecular weight of 10,000 or less, as in Example 1. The component content was measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Example 5)
Inherent viscosity of pellet, isothermal crystallization peak time at 210 ° C. and isothermal crystallization energy as in Example 4 except that MHET and BHET were reduced at 200 ° C. for 1 hour after the pellet was crystallized. The total content of MHET and BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 1)
Inherent viscosity of pellet, isothermal crystallization peak time at 210 ° C., isothermal crystallization energy, MHET and MHET and BHET were reduced at 160 ° C. after the pellet was crystallized. The total content of BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 2)
Inherent viscosity of pellet, isothermal crystallization peak time at 210 ° C. and isothermal crystallization energy, total content of MHET and BHET, as in Example 1, except that MHET and BHET were not reduced after crystallization of the pellet Rate, acetaldehyde concentration, and molecular weight component content of 10,000 or less. A preform was prepared from the heat-treated PET resin pellets, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 3)
An amorphous state having an intrinsic viscosity of 0.74 dL / g, a total content of MHET and BHET of 0.0059 wt%, an acetaldehyde concentration of 25.0 ppm, and a content of copolymerized components of DEG and IPA of 1.7 wt% Except for using the melt-polymerized PET resin pellets, the intrinsic viscosity of the pellets, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, the acetaldehyde concentration, and 10,000 or less, as in Example 2. The molecular weight component content of was measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 4)
An amorphous state having an intrinsic viscosity of 0.64 dL / g, a total content of MHET and BHET of 0.0088 wt%, an acetaldehyde concentration of 35.0 ppm, and a content of copolymerized components of DEG and IPA of 2.5 wt% Except for using the melt-polymerized PET resin pellets, the intrinsic viscosity of the pellets, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, the acetaldehyde concentration, and 10,000 or less, as in Example 2. The molecular weight component amount of was measured. A preform was prepared from the heat-treated PET resin pellets, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 5)
An amorphous state having an intrinsic viscosity of 0.76 dL / g, a total content of MHET and BHET of 0.0054% by weight, an acetaldehyde concentration of 26.5 ppm, and a content of copolymerized components of DEG and IPA of 2.4% by weight Except for using the melt-polymerized PET resin pellets, the intrinsic viscosity of the pellets, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, the acetaldehyde concentration, and 10,000 or less, as in Example 2. The molecular weight component content of was measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 6)
An amorphous state having an intrinsic viscosity of 0.86 dL / g, a total content of MHET and BHET of 0.0052 wt%, an acetaldehyde concentration of 45.0 ppm, and a copolymer component content of DEG and IPA of 3.0 wt% Except for using the melt-polymerized PET resin pellets, the intrinsic viscosity of the pellets, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, the acetaldehyde concentration, and 10,000 or less, as in Example 2. The molecular weight component content of was measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 7)
Solid-phase polymerization was performed with an intrinsic viscosity of 0.73 dL / g, a total content of MHET and BHET of 0.0043 wt%, an acetaldehyde concentration of 0.5 ppm, and a copolymerization component content of DEG of 1.2 wt%. Using PET resin pellet RT543CTHP (manufactured by Nippon Unipet Co., Ltd.), the pellet intrinsic viscosity and isothermal crystallization peak time at 210 ° C. are the same as in Example 1 except that the preform is molded after the drying step at 150 ° C. for 4 hours. And isothermal crystallization energy, total content of MHET and BHET, acetaldehyde concentration, and molecular weight component content of 10,000 or less. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 8)
Solid phase polymerization with an intrinsic viscosity of 0.83 dL / g, a total content of MHET and BHET of 0.0021 wt%, an acetaldehyde concentration of 0.7 ppm, and a copolymer component content of DEG and IPA of 2.8 wt% PET pellet BK6180B (manufactured by Nihon Unipet Co., Ltd.) was used, and the pellet intrinsic viscosity and isothermal crystal at 210 ° C. were the same as in Example 1 except that a preform was formed after the drying step at 150 ° C. for 4 hours. The crystallization peak time and isothermal crystallization energy, the total content of MHET and BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Comparative Example 9)
Solid phase polymerization with an intrinsic viscosity of 0.70 dL / g, a total content of MHET and BHET of 0.0041 wt%, an acetaldehyde concentration of 0.7 ppm, and a content of copolymerized components of DEG and IPA of 1.7 wt% PET resin pellet RT523C (manufactured by Nippon Unipet Co., Ltd.) was used, and the pellet intrinsic viscosity and isothermal crystal at 210 ° C. were the same as in Example 1 except that a preform was formed after the drying step at 150 ° C. for 4 hours. The crystallization peak time and isothermal crystallization energy, the total content of MHET and BHET, the acetaldehyde concentration, and the molecular weight component content of 10,000 or less were measured. A preform was prepared from the heat-treated PET resin pellet, and the inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Example 6)
The melt-polymerized PET resin pellets of Example 2 subjected to the reduction treatment of MHET and BHET and the solid-phase polymerized PET resin pellets of Comparative Example 8 were dry blended at a ratio of 30:70, and the preform was subjected to a drying process at 150 ° C. for 4 hours. Molded. The inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

(Example 7)
The melt-polymerized PET resin pellets of Example 2 subjected to the reduction treatment of MHET and BHET and the melt-polymerization PET resin pellets of Comparative Example 6 subjected to the reduction treatment of MHET and BHET were dry-blended in a ratio of 20:80 at 150 ° C. The preform was molded after a time drying step. The inherent viscosity of the preform, the isothermal crystallization peak time and isothermal crystallization energy at 210 ° C., the total content of MHET and BHET, and the acetaldehyde concentration were measured. Moreover, mouth crystallization was performed using the produced preform, and the time when the crystallinity χc exceeded 0.30 was determined, and the heat-resistant blow mold surface contamination was evaluated.

  Tables 1 and 2 show the results of the above-described examples and comparative examples.

  Table 3 shows the amount of terephthalic acid and isophthalic acid charged in the above-described melt-polymerized PET resin and the reaction time.

The crystallization time and ultimate crystallinity (χc) of the mouth of the preform (Example 1) made of the polyester resin of the present invention and the preform (Comparative Example 7) made of the polyester resin obtained through solid phase polymerization are compared. It is a graph which shows a relationship.

Claims (6)

  The intrinsic viscosity is in the range of 0.65 to 0.80 dL / g, the total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate is less than 0.005% by weight, and the acetaldehyde concentration is 2 to 10 ppm. An ethylene terephthalate-based polyester resin for heat-resistant container molding, characterized in that the peak time of crystallization in isothermal crystallization at 210 ° C. is 360 seconds or less and the crystallization energy (ΔH) is 30 J / g or more.   The intrinsic viscosity is in the range of 0.65 to 0.80 dL / g, the total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate is less than 0.005% by weight, and the acetaldehyde concentration is 2 to 10 ppm. And an ethylene terephthalate-based polyester resin for forming a heat-resistant container, wherein a molecular weight component of 10,000 or less is 8% or more.   The ethylene terephthalate-based polyester resin for heat-resistant container molding according to claim 1 or 2, wherein the total amount of diethylene glycol and isophthalic acid contained as copolymerization components is 1.5% by weight or less.   The ethylene terephthalate-based polyester resin according to any one of claims 1 to 3, having an intrinsic viscosity in the range of 0.65 to 0.80 dL / g, and a total content of monohydroxyethyl terephthalate and bishydroxyethyl terephthalate The amount is less than 0.010% by weight, the acetaldehyde concentration is 15 ppm or less, the peak time of crystallization in isothermal crystallization at 210 ° C. is 60 seconds or less, and the crystallization energy (ΔH) is 20 J / g or more. Preform characterized by that.   The preform according to claim 4, wherein the total amount of diethylene glycol and isophthalic acid contained as copolymerization components is 2.7% by weight or less.   The ethylene terephthalate polyester resin according to any one of claims 1 to 3, wherein the ethylene terephthalate polyester resin obtained by melt polymerization is subjected to heat treatment at a temperature of 170 to 200 ° C for 1 hour or more and less than 5 hours. Manufacturing method.

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