JP2006161019A - Polyester resin for compression molding and method for producing the same and method for producing preform - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin for compression molding in which the deposition of the resin onto a transport means in a synthetic resin feeding device can effectively be prevented and which does not cause a deviation of timing of dropping of a melted resin mass into a compression mold and, at the same time, can increase the amount of the resin delivered from an extruder and further, does not cause any excessive increase in torque of the extruder and can realize molding of a preform by compression molding with high productivity. <P>SOLUTION: The polyester resin has an intrinsic viscosity of 0.70 to 1.00 dL/g, a molecular weight distribution (Mz/Mn) of ≥ 3.0 and a diethylene glycol content of ≤2.3%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyester resin for compression molding, and more specifically, a component that causes resin to adhere to a means for supplying a molten resin mass to a compression molding machine is reduced, and a smooth supply to the compression molding machine is achieved. The present invention relates to a polyester resin for compression molding and a method for producing a preform having excellent productivity.

  As containers for filling beverages and the like, those made of a synthetic resin such as polyethylene terephthalate are widely used, and such containers are prepared by forming a bottomed preform in advance by injection molding of a synthetic resin. A method of preheating to the stretching temperature, pulling and stretching in the axial direction in the blow mold, and blow-stretching in the circumferential direction is employed (for example, see Patent Document 1).

  In addition, as a method for producing such a preform, since the residence time in the molding machine is short and the deterioration of the resin is small, and there is no gate part at the bottom, it is already known that the resin is produced by compression molding. Yes. For example, a step of extruding a thermoplastic resin melt and cutting it into a substantially fixed amount of molten lump, a step of disposing a male mold and a female mold so as to be relatively movable, and supplying the molten lump into the mold, The process consists of a step of compression molding into a molded product having a bottomed body and a mouth while discharging residual air inside, and a step of cooling and solidifying the compression molded product and discharging the molded product out of the mold. A method for manufacturing a reform has been proposed (see Patent Document 2).

  In the preform molding by such compression molding, the synthetic resin is supplied to the female mold means or the male mold means before the male mold means and the female mold means are closed and the mold space is defined between them. For example, the synthetic resin can be supplied by, for example, holding the molten synthetic resin separated from the extrusion opening of the extrusion nozzle as it is and transporting it to the required part of the molding apparatus. A supply device has been proposed (Patent Document 3).

JP-A-4-154535 JP 2000-25729 A JP 2000-280248 A

  However, when a normal polyester resin such as polyethylene terephthalate is supplied to the compression molding machine using the above synthetic resin supply device and a certain amount of time has elapsed after the start of operation, the molten resin lump May not be reliably supplied to the compression molding machine. That is, when a preform made of polyester resin is molded by compression molding, it is melted into holding means (holder) for holding the molten resin mass in the supply device and guide means (throat) that serves as a guide from the holding means to the compression mold. Deposits accumulate due to repeated contact with the resin mass, and when a certain amount of time has passed since the start of the molding machine operation, the molten resin mass is caught by this accumulation, and the timing of the fall of the molten resin mass changes. The timing with the set compression molding machine was not matched, and the molten resin lump could not be reliably supplied to the compression mold.

  As a result of investigating this cause, when a certain amount of time has elapsed since the start of the molding machine operation during continuous molding of a preform by compression molding, the molten resin lump holding means (holder) and the molten resin lump of the synthetic resin supply device are removed. The specific timing of the molten resin lump changes due to the accumulation of certain components on the guiding means (throat) that guides the compression mold, which accumulates and prevents this accumulated resin from falling. I found out that

Accordingly, an object of the present invention is to suppress the formation of accumulations on the conveying means such as the holding means and the guiding means of the synthetic resin supply device, and to perform compression molding that can stably supply molten resin mass to the compression molding device over a long period of time. It is to provide a polyester resin.
Another object of the present invention is to provide a polyester resin for compression molding, which is made of a general-purpose polyester resin and can form a preform by compression molding with good moldability and productivity without causing the above problems, and a method for producing the same. .
Another object of the present invention is to stably supply a molten resin mass to a compression molding machine over a long period of time without forming a deposit on a conveying means such as a holding means and a guiding means in a synthetic resin supply apparatus. It is to provide a production method capable of forming a preform with good performance.

According to the present invention, the intrinsic viscosity is 0.70 to 1.00 dL / g, the molecular weight distribution (Mz / Mn) is 3.0 or more, and the diethylene glycol content is 2.3 mol% or less. A polyester resin for compression molding is provided.
In the polyester resin for compression molding of the present invention,
1. Containing a molecular weight component in excess of the degree of polymerization between the entanglement points in an amount of 20% by weight or more,
2. The low molecular weight component having a weight average molecular weight in the range of 500 to 2000 in the polyester resin is 1.1% by weight or less,
Is preferred.

According to the present invention, polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50, and an intrinsic viscosity of 0.80 to 1. Melting and kneading polyester resin B with 30 dL / g and molecular weight distribution (Mz / Mn) of 2.80 to 4.00 so that the difference in intrinsic viscosity between polyester resin A and polyester resin B is 0.15 or more. A method for producing a polyester resin for compression molding is provided.
In the method for producing a polyester resin for compression molding according to the present invention, the polyester resin A and the polyester resin B are preferably used in a weight ratio of 5:95 to 95: 5.

  According to the present invention, the polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50, and an intrinsic viscosity of 0.80 to 1. Melting and kneading polyester resin B with 30 dL / g and molecular weight distribution (Mz / Mn) of 2.80 to 4.00 so that the difference in intrinsic viscosity between polyester resin A and polyester resin B is 0.15 or more. There is provided a method for producing a preform, which comprises compression-molding a molten resin mass of a polyester resin.

According to the polyester resin for compression molding of the present invention, the adhesion of the resin to the conveying means of the synthetic resin supply device used at the time of compression molding is effectively prevented, and the timing of the dropping of the molten resin lump onto the compression mold is prevented. There is no deviation, and the amount of resin discharged from the extruder can be increased, and the torque of the extruder is not excessively increased. Therefore, the preform can be molded by compression molding with high productivity. It becomes possible. Further, since the fluidity of the resin is high, there is no occurrence of wrinkles, haze, molding distortion or the like in the preform as a molded product, and molding can be performed with good moldability.
According to the method for producing a polyester resin for compression molding of the present invention, it is possible to easily prepare a polyester resin for compression molding having the above characteristics.

The polyester resin for compression molding of the present invention has an intrinsic viscosity of 0.70 to 1.00 dL / g, particularly 0.73 to 0.90 dL / g, and a molecular weight distribution (Mz / Mn) of 3.0 or more, particularly 3. It is an important feature that the diethylene glycol content is in the range of 0 to 3.5 and the diethylene glycol content is 2.3 mol% or less, particularly 1.3 to 2.2 mol%.
In the present invention, the intrinsic viscosity is 0.70 to 1.00 dL / g, the molecular weight distribution (Mz / Mn) is 3.0 or more, and the diethylene glycol content is 2.3 mol% or less. The resin is effectively prevented from adhering to the conveying means of the synthetic resin supply device used for molding, and there is no deviation in the timing of dropping the molten resin lump onto the compression mold, and the resin from the extruder In addition to increasing the discharge amount of the extruder, there is no excessive increase in the torque of the extruder. Therefore, the preform can be molded by compression molding with high productivity. Further, since the fluidity of the resin is high, there is no occurrence of wrinkles, haze, molding distortion or the like in the preform as a molded product, and molding can be performed with good moldability.

  As a cause of hindering the smooth fall of the molten resin mass of the polyester resin, the present inventors attached and accumulated high molecular weight components having a degree of polymerization below the entanglement point via the monomer component and oligomer component in the polyester resin on the conveying means. I found out. From this point of view, it is preferable to reduce these components to improve the transportability of the molten resin mass of the polyester resin, but resins containing a large amount of components having a degree of polymerization between the entanglement points are generally melt viscosity. In the present invention, the high molecular weight component is increased while broadening the molecular weight distribution to improve the transportability of the molten resin mass. It has been found that the intrinsic viscosity of the entire polyester resin can be in the range of 0.70 to 1.00 dL / g without loss, and the moldability, productivity and economy can be improved.

  In particular, the molecular weight distribution (Mz / Mn) defined in the present invention directly represents the influence of the distribution of the high molecular weight component in the polyester resin, and the molecular weight distribution (Mz / Mn) is 3.0 or more, particularly 3.0. In the range of 3.5 to 3.5, the polyester resin of the present invention contains a larger amount of a high molecular weight component than the general polyester resin having an intrinsic viscosity in the above range, which is larger than the degree of polymerization between the entanglement points, Since the content of the monomer component, oligomer component, and high molecular weight component having a degree of polymerization below the entanglement point is small, the molten resin lump has excellent transportability.

  In the present invention, it is also important that the amount of diethylene glycol (hereinafter referred to as DEG) is 2.3 mol% or less, particularly 1.3 to 2.2 mol%, and DEG is 2.3 mol%. In the case where the molecular weight distribution is larger than the above range, even when the molecular weight distribution and the intrinsic viscosity are in the above ranges, the transportability of the molten resin mass is inferior. The reason why the DEG content affects the transportability of the molten resin mass is not clear, but because DEG is inferior in thermal stability, the molecular chain is likely to break, and as a result, if the DEG content is high, the low molecular weight component This is considered to be because the melting point of the polyester resin is lowered when the content of DE is increased and the DEG content is increased, and the adhesiveness of the resin at the extrusion temperature of the molten resin mass is increased.

  Such operational effects of the present invention are apparent from the results of Examples described later. That is, a polyester resin having an intrinsic viscosity of 0.7 to 1.00 dL / g, a molecular weight distribution (Mz / Mn) of 3.0 or more and a diethylene glycol content of 2.3 mol% or less is a holder for a molten resin. While there is no adhesion to the resin, the timing of dropping the molten resin mass does not change even after a certain period of time, and the moldability and productivity are excellent (Examples 1 to 9). When the polyester resin has a viscosity smaller than the above range, the molten resin may be drawn down, and a molten resin lump cannot be efficiently formed (Comparative Examples 2 and 8). However, although it does not adhere to the holder, it is clearly inferior in productivity as compared to the case of the above range, and if the intrinsic viscosity is too large, it is clear that molding distortion occurs. Comparative Example 3,5,7,9,11).

  Further, when the molecular weight distribution (Mz / Mn) is less than 3.0, even when the intrinsic viscosity is in the above range, adhesion of the molten resin to the holder occurs, the drop timing is shifted, and the transportability of the molten resin lump is inferior. It is clear (Comparative Examples 4, 6, and 12) that the polyester resin having a diethylene glycol content of more than 2.3 mol% adheres the molten resin to the holder even when the intrinsic viscosity and molecular weight distribution are in the above ranges. It is clear that the transportability is inferior (Comparative Examples 1, 4, 6, 10, 12).

In addition, in the polyester resin for compression molding of the present invention, as long as the above-described features of the present invention are provided, it is preferable to contain 20% by weight or more of a high molecular weight component having a degree of polymerization between entanglement points. The transportability of the molten resin mass is further improved.
That is, as described above, the accumulated matter that adheres to the holder or throat as a means for conveying the molten resin lump and prevents the molten resin lump from falling smoothly is the monomer component, oligomer component, high molecular weight component contained in the polyester resin. In the change in the falling timing of the molten resin mass, the oligomer component and the high molecular weight component are the direct causes.
It is known that the oligomer component in the polyester resin moves to the heat set mold and accumulates when heat-setting polyester bottles, etc., and this accumulation causes a decrease in gloss on the bottle surface. Then, in order to convey the molten resin, in addition to the oligomer component, the high molecular weight component is also easily transferred.
In view of such facts, the present inventors have conducted extensive research on the high molecular weight component adhering to the holder and the throat. As a result, the high molecular weight component in the accumulation has a weight average molecular weight equal to or less than the degree of polymerization between the entanglement points of the polyester resin used. They found it to be a high molecular weight component.

In general, the viscosity behavior of a polymer liquid changes abruptly when the critical polymerization degree Ne (degree of polymerization between entanglement points) is exceeded, and when the polymerization degree N of the polymer is N <Ne, the melt viscosity η is proportional to the polymerization degree N. On the other hand, when N> Ne, the melt viscosity η is proportional to the cube of the polymerization degree N. This is clear from FIG. 1 showing the relationship between the intrinsic viscosity and the melt viscosity of various polyester resins used in the examples described later, with the critical polymerization degree (intersection of straight lines A and B in FIG. 1) as a boundary. The viscosity increases rapidly.
In the present invention, it is clear from the results of Examples described later that the content of the molecular weight component having a degree of polymerization below the entanglement point can significantly reduce the accumulation of deposits on the holder or the like at 80% by weight as a boundary. is there. That is, in the polyester resin in which the molecular weight in the degree of polymerization between the entanglement points is 1.0 × 10 ⁵ and the intrinsic viscosity is equal, the molecular weight component equal to or higher than the degree of polymerization between the entanglement points is less than 20% by weight. Compared to the case of using a polyester resin within the scope of the invention (Example 9), when using a polyester resin having a molecular weight component of 20% by weight or more of the degree of polymerization between the entanglement points, both in the holder and the throat It can be seen that even after the continuous molding was performed for 2 hours, almost no adhesion occurred, and a more excellent result was obtained (Example 4).

Further, as described above, it is known that the monomer component is present in order for the oligomer component to adhere to the mold surface during heat setting, and the high molecular weight component in the present invention was also eluted in the same manner. It is considered that a high molecular weight component adheres via a monomer component and an oligomer component, and in fact, the oligomer component is also detected in the accumulated material such as a holder. The low molecular weight component having a weight average molecular weight in the range of 500 to 2,000 in the resin is preferably in the range of 1.1% by weight or less.
In this way, by suppressing the amount of the low molecular weight component in a specific range, it is possible not only to suppress the adhesion due to the elution of itself, but also to suppress the adhesion of the high molecular weight component. This makes it possible to stabilize the falling timing of the molten resin mass over a long period of time. That is, when the low molecular weight component having a weight average molecular weight in the range of 500 to 2000 in the polyester resin having an equivalent intrinsic viscosity exceeds 1.1% by weight (Examples 6 and 7), the content of the low molecular weight component is 1. It is also clear from the results of the examples that the effect of suppressing deposits is inferior to that in the case of 1% by weight or less (Examples 1 and 3).

In the present invention, a polyester resin having the above-described properties is obtained by combining a polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50 with an intrinsic viscosity. Is 0.80 to 1.30 dL / g and the molecular weight distribution (Mz / Mn) is 2.80 to 4.00. The difference in intrinsic viscosity between the polyester resin A and the polyester resin B is 0.15 or more. It can manufacture by combining and melt-kneading so that it may become.
As described above, the polyester resin of the present invention has an intrinsic viscosity of 0.70 to 1.00 dL / g, a molecular weight distribution (Mz / Mn) of 3.0 or more, and a diethylene glycol content of 2.3 mol% or less. Satisfying all of the above is important in terms of the transportability, moldability, productivity, etc. of the molten resin mass, but has a low intrinsic viscosity and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50. By using polyester resin A in combination with polyester resin B having a high intrinsic viscosity and a molecular weight distribution (Mz / Mn) of 2.80 to 4.00, a polyester resin having a low intrinsic viscosity and a high content of high molecular weight components can be obtained. It can be easily prepared.

  In the method for producing a polyester resin of the present invention, it is important to use the polyester resin A and the polyester resin B in a combination in which the difference in intrinsic viscosity is 0.15 or more, whereby the intrinsic viscosity and the molecular weight distribution are in the above range. This makes it possible to prepare the polyester resin in In general, the intrinsic viscosity has a corresponding relationship with the molecular weight. Therefore, when a polyester resin in the range of 0.70 to 1.00 dL / g specified in the present invention is prepared by an ordinary polyester resin synthesis method, it is specified in the present invention. Although it is not easy to adjust the molecular weight distribution (Mz / Mn) to 3.0 or more, according to this method, a polyester resin having the intrinsic viscosity and molecular weight distribution specified in the present invention can be easily prepared. It becomes possible.

This is also clear from the results of Examples described later. That is, even when the intrinsic viscosity is in the above range, when the difference in intrinsic viscosity between the polyester resin A and the polyester resin B is less than 0.15, the molecular weight distribution of the obtained polyester resin is adjusted within the range of the present invention. (Comparative Examples 6 and 12).
Polyester resin A and polyester resin B have different blending ratios depending on the intrinsic viscosity and molecular weight distribution of the polyester resin to be used, and cannot be generally specified, but are preferably used in a weight ratio of 5:95 to 95: 5.

(Preparation of polyester resin)
Polyester resin for compression molding according to the present invention having an intrinsic viscosity of 0.70 to 1.00 dL / g, a molecular weight distribution (Mz / Mn) of 3.0 or more and a diethylene glycol content of 2.3 mol% or less. Although not limited to this, polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50, and an intrinsic viscosity of 0 Polyester resin B having a molecular weight distribution (Mz / Mn) of 2.80 to 1.30 dL / g and a molecular weight distribution (Mz / Mn) of 0.18 or more so that the difference in intrinsic viscosity between polyester resin A and polyester resin B is 0.15 or more. It can manufacture suitably by combining and melt-kneading.
The degree of polymerization between the entangled points is determined by the chemical structure of the polyester resin and cannot be specified in general. However, in the case of homopolyethylene terephthalate, the viscosity rapidly increases with a weight average molecular weight of 1.0 × 10 ^5. Therefore, in the polyester resin of the present invention, it is preferable to contain at least 20% by weight of a high molecular weight component having a weight average molecular weight of 1.0 × 10 ⁵ or more in the polyester resin.
The polyester resin of the present invention is not limited to this, but a liquid phase polymerization of raw materials mainly comprising terephthalic acid or an ester-forming derivative thereof and ethylene glycol or an ester-forming derivative thereof in the presence of a catalyst. And those obtained by solid phase polymerization.
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) reacting TPA and EG to synthesize bis-β-hydroxyethyl terephthalate (BHET) or a low polycondensate thereof; (B) removing ethylene glycol from BHET or a low polycondensate thereof; It consists of a process of polycondensation.

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, a germanium compound, a titanium compound, an antimony compound, or the like is used, but using a germanium compound such as germanium dioxide, germanium tetraethoxide, germanium tetrabutoxide, the crystallization temperature range is within the above-described range. It is preferable in keeping.

  In order to reduce the DEG content in the polyester resin of the present invention, it is necessary to reduce the DEG content in the polyester resin A and the polyester resin B. In order to reduce the DEG content, it is necessary to control by appropriately selecting reaction conditions, additives and the like. In this case, the additives include tertiary amines such as triethylamine and tri-n-butylamine, Examples include quaternary ammonium such as tetraethylammonium hydroxide and tetrabutylammonium hydroxide, and basic compounds such as lithium carbonate and sodium carbonate, and the addition amount is in the range of 0.005 to 1% by weight. It is preferable.

In the polyester resin for compression molding of the present invention, it is preferable that most of the ester repeating units, generally 70 mol% or more, particularly 80 mol% or more occupy the ethylene terephthalate unit, and the glass transition point (Tg) is 50 to 90 ° C. In particular, thermoplastic polyesters having a melting point (Tm) of 200 to 275 ° C., particularly 220 to 270 ° C. at 55 to 80 ° C. are preferred.
Homopolyethylene terephthalate is preferred in terms of heat and pressure resistance, but a copolyester containing a small amount of ester units other than ethylene terephthalate units can also be used. Dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. 1 type or combination of 2 or more types of diol components other than ethylene glycol include propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexane di 1 type, or 2 or more types, such as methanol and the ethylene oxide adduct of bisphenol A, are mentioned.

  As the polyester resin is crystallized, low molecular weight components such as cyclic trimers contained inside protrude outside and the content of low molecular weight components decreases. This crystallization temperature has an optimum range with respect to a decrease in the content of low molecular weight components. Generally, in the case of homopolyethylene terephthalate, a range of 100 to 150 ° C., particularly 120 to 140 ° C. is appropriate, and the treatment time is 1 Up to 24 hours, especially 2 to 20 hours are suitable. The heat treatment for crystallization of the polyester resin pellets can be performed in a fluidized bed or a fixed bed using a heated inert gas such as heated nitrogen gas, or can be performed in a vacuum heating furnace.

The polyester resin B used in the method for producing a polyester resin of the present invention has a higher intrinsic viscosity than the polyester resin A, and the intrinsic viscosity is in the range of 0.80 to 1.30 dL / g. In order to obtain a desired intrinsic viscosity, the crystallized polyester resin pellets can be obtained by solid phase polymerization.
In this solid phase polymerization, unlike the case of melt polymerization, as the intrinsic viscosity increases, the low molecular weight component and the molecular weight component below the degree of polymerization between the entanglement points are reduced. In general, as the solid-phase polymerization temperature increases, the content of the low molecular weight component and the molecular weight component below the degree of entanglement decreases, and as the polymerization time increases, the content of the low molecular weight component and the degree of polymerization below the entanglement point decreases. The content of the molecular weight component is lowered, and the molecular weight distribution (Mz / Mn) can be in the range of 3.0 to 3.5.
The solid phase polymerization is generally preferably carried out at a temperature of 160 to 260 ° C., particularly 180 to 200 ° C. for 2 to 10 hours, particularly 4 to 6 hours. Heating at the time of solid phase polymerization may be the same as in the case of crystallization except that the temperature is changed. The crystallization of the polyester resin proceeds to some extent also during the solid phase polymerization.

The polyester resins A and B thus obtained are preferably blended at a weight ratio of A: B = 5: 95 to 95: 5, particularly 10:90 to 90:10, and melt-kneaded. A polyester resin having an intrinsic viscosity of 0.70 to 1.00 dL / g, a molecular weight distribution (Mz / Mn) of 3.0 or more, and a diethylene glycol content of 2.3 mol% or less can be obtained.
In general, the melt kneading of the polyester resin A and the polyester resin B is desirably performed at a temperature of 200 to 300 ° C. for 1 to 10 minutes, and is preferably performed by pulling a vent in order to prevent decomposition of the resin.

In the polyester resin for compression molding of the present invention, in addition to the method of preparing the polyester resins A and B described above in combination immediately before compression molding, or the method of supplying the prepared pellets again to the compression molding extruder, ordinary polymerization Directly, a polyester resin having an intrinsic viscosity in the range of 0.70 to 1.00 and a molecular weight distribution (Mz / Mn) of 3.0 or more may be prepared.
In general, a condensation polymer such as a polyester resin always undergoes a transesterification reaction at a melting temperature, and therefore the molecular weight distribution takes a certain optimum value. For this reason, in order to make this molecular weight distribution (Mz / Mn) as wide as 3.0 or more, it is desirable to use means such as a method of copolymerizing polyol.

(Preform manufacturing method)
In the preform production method of the present invention, as described above, the molten resin mass supplied to the compression molding machine has an intrinsic viscosity of 0.70 to 1.00 dL / g and a molecular weight distribution (Mz / Mn) of 3.0. In addition to the above, it can be molded by a conventionally known compression molding method except that it is molded using a polyester resin having a diethylene glycol content of 2.3 mol% or less.
By using the polyester resin, there is no accumulation of deposits in the molten resin lump conveying means such as the holder and throat in the molten resin lump supply device to the compression molding machine even if the continuous operation is performed for a long time, and the conveying means Therefore, it is possible to manufacture the preform with high production efficiency.
In addition, since this polyester resin has an intrinsic viscosity in the range of 0.70 to 1.00 dL / g, the resin has good fluidity, the amount of resin discharged from the extruder can be increased, and the torque of the extruder can be increased. Since it does not rise excessively, a preform can be produced with high productivity. In addition, when compression molding is performed in the compression mold, it smoothly flows in the mold, so that the generation of wrinkles, haze, or molding distortion can be effectively suppressed, and compression molding can be performed with good moldability. There is an advantage that you can.

In the method for producing the preform of the present invention, 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 a uniform melt-extruded product 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, thereby suppressing the elution of oligomer components and molecular weight components below the degree of polymerization between the entanglement points, and suppressing the adhesion of the molten extrudate. Therefore, it is possible to prevent adhesion to the holder and the throat.

2 and 3 are explanatory views showing a molding apparatus used when a preform is molded using the polyester resin for compression molding of the present invention, and FIG. 2 is a diagram showing the entire molding system. FIG. 3 is a cross-sectional view taken along a portion X in FIG. 2 and is a partial cross-sectional view showing a state in which the cutting / holding means sandwiches the molten resin lump in order to drop the molten resin lump.
The compression molding apparatus generally indicated by 1 includes a relatively large-diameter rotating disk 38 that is driven to rotate in the direction indicated by an arrow A, and a plurality of circumferentially spaced circumferential edges of the rotating disk 38 are arranged at a plurality of intervals. A mold 40 is provided. Each of the molds 40 includes a female mold 48 and a male mold 50. When the mold 40 is located at the molten resin lump supply position, the male mold rises to the open position, and the rigid resin supply device 20 is placed in the female mold 48. The molten resin mass 34 is supplied from the cutting / holding mechanism 22. When the molding die 40 is located in the molding region, the male die 50 is lowered to the closed position, and the molten resin mass 34 is compression-molded into a preform having a required shape by the cooperation of the female die 48 and the male die 50. When the mold 40 reaches the carry-out position, the male mold 50 is raised to the open position, and the molded preform is taken out.

  More specifically, the molten resin mass 34 formed by cutting the strand extruded from the extruder by the cutting means 28 is held by the cutting / holding means including the holder 30 and the pusher 32. When the mold 40 reaches the supply position, the pusher 32 moves and the molten resin mass 34 falls downward. The female mold 48 is provided with a throat 56, and the molten resin mass 34 is stably supplied into the female mold 48 through the throat 56. In the present invention, since the adhesion of the oligomer component and the high molecular weight component from the molten resin lump to the holder and the throat is particularly suppressed, the timing of dropping of the molten resin lump is constant, and the molten resin lump is stably placed in the mold. Can be supplied over a long period of time.

  The preform molded using the polyester resin for compression molding of the present invention has an intrinsic viscosity of 0.65 to 0.80 dL / g and a molecular weight distribution (Mz / Mn), as will be apparent from Examples described later. In addition to being 3.0 or more, the DEG content is in the range of 2.3% by weight or less, and a molecular weight component having a degree of polymerization between the entanglement points or more is contained in an amount of 5% by weight or more.

The preform molded using the polyester resin for compression molding of the present invention is molded into a stretch-molded container such as a bottle or a wide-mouthed cup by stretch blow molding.
In stretch blow molding, a preform molded using the polyester resin for compression molding of the present invention is heated to a stretching temperature, and the preform is stretched in the axial direction and biaxially stretched blow molded in the circumferential direction. An axial stretch container is manufactured.
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.

This 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 fluid. . In general, the mold temperature is preferably in the range of room temperature to 190 ° 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.

The polyester container of the present invention can be heat-set by a means known per se. The heat setting can be performed by a one-mold method performed in a blow molding die, or can be performed by a two-mold method performed in a heat fixing die separate from the blow molding die. The temperature for heat setting is suitably in the range of 120 to 180 ° C.
As another stretch blow molding method, as illustrated in Japanese Patent No. 29178851 of the present applicant, a preform is subjected to primary blow molding having a size larger than that of a final molded product using a primary blow mold. A two-stage blow molding method may be employed in which the primary blow molded body is heated and shrunk, and then stretch blow molding is performed using a secondary blow mold to obtain a final molded product.

I. Measurement 1. Intrinsic viscosity Polyethylene terephthalate resin pellets dried at 150 ° C. for 4 hours, a blend of polyester A and polyester B in a predetermined ratio, or 0.20 g of a sample cut from a molded preform, weighed 1,1,2 , 2-tetrachloroethane / phenol (1/1) (weight ratio) using 20 ml, the mixture is stirred at 120 ° C. for 20 minutes for complete dissolution. After dissolution, the solution was cooled to room temperature, and the intrinsic viscosity was determined using an Ubbelohde viscometer (manufactured by Kusano Kagaku Kikai Co., Ltd.) whose temperature was adjusted to 30 ° C. through a glass filter.

2. DEG amount A sample is cut out from a pellet of polyethylene terephthalate resin dried at 150 ° C. for 4 hours, a blend of polyester A and polyester B at a predetermined ratio, or a molded preform, and deuterated with trifluoroacetic acid / deuterated chloroform (1/1 ) (Weight ratio) was dissolved in a mixed solvent, and a 1H-NMR spectrum was measured with an NMR apparatus (EX270: JEOL Datum Co., Ltd.). Of the obtained spectrum, the content ratio of DEG was calculated from the ratio of the integrated values of the peaks derived from the DEG site (4.27 ppm) and the terephthalic acid site (8.22 ppm).

3. Measurement of weight average molecular weight and molecular weight distribution A polyester resin sample (5 mg) was precisely weighed, and a weight ratio of 50:50 chloroform (for high performance liquid chromatograph: manufactured by Kishida Chemical Co., Ltd.)-1,1,1,3,3 Using a solution dissolved in a mixed solvent of 3, -hexafluoro-2-propanol (manufactured by Central Glass Co., Ltd.), gel permeation chromatography (system: Integrated System For GPC / SEC, manufactured by Asahi Techneion Co., Ltd.), column: The weight average molecular weight Mw was determined by TSK G5000HHR + 4000HHR, detector: Triple Detector Module TriSEC Model 302 manufactured by VISCOTEC, eluent: chloroform, injection amount: 100 μL).
Moreover, molecular weight distribution (Mz / Mn) was calculated | required from the number average molecular weight Mn and z average molecular weight Mz obtained similarly.
Here, the z average molecular weight Mz is an average molecular weight given by ΣWiMi ² / WiMi, Wi represents the weight of the molecular species, and Mi represents the molecular weight.

4). Molecular weight component content less than or equal to molecular weight between entanglement points (1) First, intrinsic viscosity of four types of polyethylene terephthalate resins having the same composition but different molecular weights was measured by the above method. Next, the melt viscosity at a strain rate of 608 (1 / sec.) And a temperature of 270 ° C. was measured using a capillograph (manufactured by Toyo Seiki Co., Ltd.). The obtained melt viscosity was plotted against the intrinsic viscosity (FIG. 1), and the intrinsic viscosity at which entanglement began was determined from the point at which the slope changed.
(2) 1,1,1,3,3,3, -hexafluoro-2-propanol and chloroform mixed solvent having a weight ratio of 50:50, 3 mg of polyethylene terephthalate resin pellet pieces were completely dissolved Later, Gel Permeation Chromatography (GPC: Integrated System For GPC / SEC: manufactured by Asahi Techneion Co., Ltd., Triple Detector Module TriSEC Model 302: Viscotek) equipped with light scattering, differential refractometer, and differential pressure viscosity detector as detectors Calibration curve of intrinsic viscosity-molecular weight was obtained.
(3) The molecular weight at which entanglement begins in the polyethylene terephthalate resin, that is, the molecular weight between entanglement points, was calculated from the intrinsic viscosity at which entanglement began in (1) above and the calibration curve of intrinsic viscosity-molecular weight obtained at (2).
(4) Using the same gel permeation chromatography as in (2) above, an integral curve of the molecular weight distribution of the polyethylene terephthalate resin sample used for molding was determined, and the content of components below the molecular weight between the entanglement points was calculated.

5. Component content of molecular weight of 500 to 2000 The content of components having a weight average molecular weight of 500 to 2000 was determined from the integral curve of the molecular weight distribution measured using the gel permeation chromatography.

II. Evaluation 1. Adhesion to Holder / Throat PET resin pellets dried at 150 ° C. for 4 hours or more were extruded at 270 ° C. and continuously compression-molded. Two hours after the start of molding, the holder and throat of the synthetic resin supply device were removed, and the adhering material was collected by washing twice with 10 ml of the mixed solvent. This solution was evaporated, dried and solidified, made up to 2.5 ml with the same mixed solvent, and the presence or absence of a high molecular weight component and a low molecular weight component was confirmed by the gel permeation chromatography. The criteria for evaluation are as follows.
○: Although a high molecular weight component and a low molecular weight component existed as a very small amount of deposits, there was no effect on timing changes.
Δ: Although a high molecular weight component and a low molecular weight component were present as a small amount of deposits, there was no effect on timing changes.
X: A high molecular weight component and a low molecular weight component existed as deposits, and a timing change occurred.

2. Changes in the fall timing of the molten resin mass When the amount of adhering component increases, the molten resin mass becomes difficult to be separated from the holder, and it becomes difficult to be stored in the cavity while maintaining its posture. The pellets of PET resin dried at 150 ° C. for 4 hours or more were extruded at 270 ° C. and continuously compression molded. Two hours after the start of molding, this was visually observed to evaluate the presence or absence of timing changes. The criteria for evaluation are as follows.
○: No timing change.
Δ: Although there was some timing change, the molten resin mass was stored in the cavity.
X: There was a change in timing, and the molten resin mass was not stored in the cavity.

3. Drawdown The pellets of PET resin dried at 150 ° C. for 4 hours or more were extruded at 270 ° C. and continuously compression-molded. Two hours after the start of molding, this was visually observed to evaluate the influence on the timing change.
○: No draw down.
Δ: There is some drawdown, but there is no effect on timing changes.
X: There is a drawdown and the influence on the timing change is large.

4). Evaluation of Shapeability PET resin pellets dried at 150 ° C. for 4 hours or more were extruded at 270 ° C. and continuously compression molded. Two hours after the start of molding, the formability of the preform was visually evaluated. The criteria for evaluation are as follows.
○: The preform has no wrinkles or haze.
[Delta]: Wrinkles and haze are observed carefully on the preform appearance.
X: Wrinkles and haze are noticeable in the preform appearance.

Example 1
PET resin A with an intrinsic viscosity of 0.62 dL / g and molecular weight distribution (Mz / Mn) 3.17 and PET resin B with an intrinsic viscosity of 1.16 dL / g and molecular weight distribution (Mz / Mn) 2.93 at 150 ° C. for 4 hours After drying, a blend resin obtained by dry blending PET resin A and PET resin B at 70:30 is melt kneaded with a twin screw extruder, melt extruded at an extrusion temperature of 270 ° C., and the molten resin shown in FIGS. 2 and 3 Using a supply device, 25 g of molten resin lump is supplied to the compression molding machine at a rate of 200 pieces / min, preforms are continuously molded for 2 hours, and are attached to the holder / throat and the molten resin lump falls. Change, drawdown, and shaping were observed.
For each of the blend resin and the preform, the intrinsic viscosity, the molecular weight distribution (Mz / Mn), the DEG content, the content of the molecular weight component more than the degree of polymerization between the entanglement points (% by weight), and the component having a molecular weight of 500 to 2000 The content (% by weight) was determined. The results are shown in Tables 1 and 2.

(Examples 2 to 7)
Except that the polyester resins A and B used or the blend ratios thereof were changed, the preform was molded in the same manner as in Example 1, and the intrinsic viscosity of each of the blend resin and the preform was determined in the same manner as in Example 1. The molecular weight distribution (Mz / Mn), the DEG content, the content (% by weight) of the molecular weight component equal to or higher than the degree of polymerization between the entanglement points, and the content (% by weight) of the component having a molecular weight of 500 to 2,000 were determined. The results are shown in Tables 1 and 2.

(Comparative Examples 1-3)
A preform was molded in the same manner as in Example 1 except that the resin alone shown in Table 1 was used as the polyester resin to be used, and the intrinsic viscosity and molecular weight distribution (Mz) of the resin and the preform were the same as in Example 1. / Mn), DEG content, content (% by weight) of a molecular weight component equal to or higher than the degree of polymerization between entanglement points, and content (% by weight) of a component having a molecular weight of 500 to 2,000. The results are shown in Tables 1 and 2.

(Comparative Examples 4-12)
Except that the inherent viscosity, molecular weight distribution and blend ratio of the polyester resins A and B used were changed, a preform was formed in the same manner as in Example 1, and in the same manner as in Example 1, for the blend resin and the preform, Intrinsic viscosity, molecular weight distribution (Mz / Mn), DEG content, content (% by weight) of a molecular weight component equal to or higher than the degree of polymerization between entanglement points, and content (% by weight) of a component having a molecular weight of 500 to 2000 were determined. The results are shown in Tables 1 and 2.

It is a figure which shows the relationship between the intrinsic viscosity and melt viscosity in a polyester resin. It is explanatory drawing which shows the shaping | molding apparatus used for the manufacturing method of the preform of this invention, and is a figure which shows the whole shaping | molding system. FIG. 3 is a cross-sectional view taken along a portion X in FIG. 2 and is a partial cross-sectional view showing a state in which the cutting / holding means holds the molten resin mass in order to drop the molten resin mass.

Claims (6)

  Polyester for compression molding having an intrinsic viscosity of 0.70 to 1.00 dL / g, a molecular weight distribution (Mz / Mn) of 3.0 or more and a diethylene glycol content of 2.3 mol% or less resin.   2. The polyester resin for compression molding according to claim 1, wherein a molecular weight component having a degree of polymerization between entanglement points or more is contained in an amount of 20% by weight or more.   The polyester resin for compression molding according to claim 1 or 2, wherein a low molecular weight component having a weight average molecular weight in the range of 500 to 2,000 in the polyester resin is 1.1% by weight or less.   Polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50, an intrinsic viscosity of 0.80 to 1.30 dL / g and a molecular weight distribution ( Compression characterized by melting and kneading polyester resin B having Mz / Mn) of 2.80 to 4.00 in combination so that the difference in intrinsic viscosity between polyester resin A and polyester resin B is 0.15 or more. A method for producing a molding polyester resin.   The method for producing a polyester resin for compression molding according to claim 4, wherein the polyester resin A and the polyester resin B are used in a weight ratio of 5:95 to 95: 5.   Polyester resin A having an intrinsic viscosity of 0.60 to 0.79 dL / g and a molecular weight distribution (Mz / Mn) of 2.50 to 3.50, an intrinsic viscosity of 0.80 to 1.30 dL / g and a molecular weight distribution ( Mz / Mn) Polyester resin B having a polyester resin B of 2.80 to 4.00 is melt-kneaded in such a manner that the difference in intrinsic viscosity between polyester resin A and polyester resin B is 0.15 or more. A method for producing a preform, characterized by compression molding.

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