JP2005289447A - Bottle body made of polyethylene terephthalate resin and method for heat-treating opening cylindrical part of preform - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bottle body made of a polyethylene terephthalate (PET) resin having an opening cylindrical part with a high heat resistance capable of corresponding to a high temperature to the extent of retort treatment by solving a technical problem that a method for heat crystallization treatment of the opening cylindrical part is to be created to suppress deformation at a high temperature treatment to the extent of the retort treatment. <P>SOLUTION: A preform formed by inserting a cylindrical core having an outer diameter forming a gap of 0.02-0.2 mm to the inner peripheral face immediately after the heat crystallization treatment at a prescribed temperature for a prescribed time, is used to prepare the bottle body made of the PET resin by biaxially oriented blow molding. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a secondary stretch blow-molded casing made of polyethylene terephthalate (hereinafter referred to as PET) -based resin in which a mouthpiece portion is subjected to thermal crystallization treatment, and a method for thermal crystallization of a preform mouthpiece portion.

  Patent Document 1 describes a PET resin biaxially stretched blow molded casing used for products requiring heat treatment such as filling at high temperature or sterilization, such as tea and fruit juice beverages. Thus, in a PET resin casing for products with a high temperature (about 80 to 90 ° C.) or heat treatment process such as tea and fruit juice beverages, the so-called heat resistance is improved by heat crystallization treatment. A mouth tube is used.

Patent Document 2 describes a method for increasing the dimensional accuracy of the tube portion by inserting a core for restricting shrinkage into the tube portion and performing a thermal crystallization process.
Japanese Patent Laid-Open No. 10-058527 Shoko 61-24170

  In recent years, the use of the PET resin casing for retort foods requiring high-temperature sterilization at about 130 ° C. has been studied, and the mouthpiece at a temperature as high as about 130 ° C. In order to suppress the deformation, it is necessary to carry out the thermal crystallization process of the mouthpiece part at a high temperature of about 180 ° C. at the surface temperature of the mouthpiece part. As the amount increases, irregular deformation such as an elliptical shape of the mouth tube portion becomes prominent, and problems such as appearance problems and poor sealing performance due to the cap occur.

  Here, in order to suppress the distorted deformation such as an elliptical shape, a method of performing heat treatment while inserting the above-mentioned core and restricting the deformation mode is effective. In the case where the cylinder part is processed at a high temperature of about 180 ° C. with the core inserted, and the casing is manufactured by biaxial stretch blow molding, the food is filled, and the retort process is performed after capping, the diameter of the cylinder part is Problems such as considerable diameter reduction and loss of sealing function cannot be solved.

  Therefore, the present invention was devised in order to solve the above-described problems in the prior art, and technically the creation of a thermal crystallization treatment method for the mouth tube portion for suppressing deformation in high-temperature treatment such as retort treatment. It is an object of the present invention to provide a PET resin casing having a mouth tube portion having high heat resistance that can cope with a high temperature as high as a retort treatment.

The means of the invention according to claim 1 for solving the technical problem is as follows:
In a PET-based resin casing formed by biaxial stretch blow molding using a preform having a mouth portion subjected to thermal crystallization treatment,
Immediately after the mouth tube portion is subjected to the thermal crystallization treatment at a predetermined temperature for a predetermined time, a cylindrical core having an outer diameter that forms a gap of 0.02 to 0.2 mm with respect to the inner peripheral surface is inserted. It has been formed.

  While the inventors of the present application are studying the improvement of a PET resin casing for use in retort processing, if the mouth tube portion is thermally crystallized at a high temperature of about 180 ° C., the crystallization is caused by crystallization. Since the amount of shrinkage is large, distorted deformation is suppressed by the regulation by the core after cooling as a result, but shrinkage deformation is suppressed and large strain remains inside, and this residual strain is in a high temperature state during retort processing. When opened, large shrinkage occurs. On the other hand, when the core is naturally shrunk without inserting the core, the mouth tube part is deformed in an irregular shape, but the residual strain is small, and the post-shrinkage by retort processing Has been found to be able to be suppressed, and the present invention has been achieved.

  According to the configuration of the first aspect, in the thermal crystallization process at a predetermined temperature for a predetermined time, the mouth tube portion can be naturally contracted, the occurrence of residual strain can be suppressed, and the heat can be generated in the mouth tube portion. Immediately after the crystallization treatment, the diameter is reduced by post-shrinkage due to cooling, and the mouth tube part comes to circumscribe the core outer peripheral surface, and the shape after cooling is regulated by the inserted core, so there is no distorted shape. And it can be set as the mouth tube part thermally crystallized in the state with a small residual strain. As a result, deformation of the mouth tube portion can be suppressed to a very small level even in sterilization processing under severe conditions at high temperatures such as retort processing.

  How much the size of the gap is to be reduced can be determined as appropriate while conducting a test or the like, such as increasing the diameter of the tube portion and decreasing the diameter as the temperature of the thermal crystallization treatment increases. The range is preferably 0.02 mm to 0.2 mm.

  That is, when the gap is less than 0.02 mm, the core cannot be smoothly inserted.

  In addition, when the thickness exceeds 0.2 mm, the effect of the deformation restriction by the core in the post-shrinkage after the thermal crystallization treatment is not sufficient, and the mouth portion of the preform after the thermal crystallization treatment is an irregular shape such as an ellipse. End up.

  According to a second aspect of the present invention, in the first aspect of the invention, the temperature of the inserted core is adjusted to 90 to 130 ° C.

  According to the configuration of claim 2, the temperature range of 90 to 130 ° C. is a temperature range above the softening point of the PET-based resin and a temperature range that is low for thermal crystallization to proceed, and the mouthpiece portion With the core circumscribing the core, the vicinity of the inner peripheral surface of the mouth tube portion can be kept in a softened state in which the progress of crystallization is suppressed and is relatively easy to deform above the softening temperature. Can be sufficiently exerted, accumulation of internal strain due to post-shrinkage can be suppressed, and residual strain in the cooled and solidified state can be more effectively suppressed.

  The means of the invention described in claim 3 resides in that the invention according to claim 1 or 2 is used for food applications that require retort treatment.

  Conventionally, it has been difficult to use a PET-based resin casing for retort due to the problem of deformation of the mouth tube portion. However, the structure according to claim 3 has a practical problem that the deformation is small even under retort processing conditions. It is possible to provide a housing having a mouth tube portion without any gap.

  As the polyethylene terephthalate resin used in the present invention, PET is mainly used. However, as long as the essence of the PET resin is not impaired, a copolymer polyester mainly containing ethylene terephthalate units and containing other polyester units is also used. In addition, for example, in order to improve heat resistance, a resin such as nylon resin and polyethylene terephthalate resin can be blended and used. Examples of the component for forming the copolyester include dicarboxylic acid components such as isophthalic acid, naphthalene 2,6 dicarboxylic acid, and adipic acid, propylene glycol, 1,4 butanediol, tetramethylene glycol, neopentyl glycol, cyclohexanedimethanol, Mention may be made of glycol components such as diethylene glycol.

  Furthermore, as long as the essence as a PET resin casing is not impaired, the PET resin casing of the present invention is, for example, PET resin / nylon resin / PET resin for improving heat resistance and gas barrier properties. It may have an intermediate layer such as nylon resin.

  The method of the invention of claim 4 is characterized in that immediately after the mouth portion of the PET resin preform is subjected to thermal crystallization treatment at a predetermined temperature for a predetermined time, the inner peripheral surface is 0.02 to 0.2 mm. A method of thermal crystallization of a preform mouth tube portion, wherein a cylindrical core having an outer diameter forming a gap is inserted.

  According to the method of claim 4, in the thermal crystallization process at a predetermined temperature for a predetermined time, the mouth tube portion can be naturally contracted, and the occurrence of residual strain can be suppressed. Immediately after the thermal crystallization treatment, the diameter shrinks due to post-shrinkage due to cooling, and the mouth tube part comes to circumscribe the outer peripheral surface of the core, and the shape after cooling is regulated by the inserted core. There can be a mouth tube portion that is thermally crystallized with little residual strain.

  How much the size of the gap is to be reduced can be determined as appropriate while conducting a test or the like, such as increasing the diameter of the tube portion and decreasing the diameter as the temperature of the thermal crystallization treatment increases. The range is preferably 0.02 mm to 0.2 mm.

  That is, when the gap is less than 0.02 mm, the core cannot be smoothly inserted.

  In addition, when the thickness exceeds 0.2 mm, the effect of the deformation restriction by the core in the post-shrinkage after the thermal crystallization treatment is not sufficient, and the mouth portion of the preform after the thermal crystallization treatment is an irregular shape such as an ellipse. End up.

  According to a fifth aspect of the present invention, there is provided the method according to the fourth aspect, wherein the temperature of the inserted core is adjusted to 90 to 130 ° C.

  According to the method of claim 5, the temperature range of 90 to 130 ° C. is a temperature range above the softening point of the PET-based resin and a temperature range that is low for thermal crystallization to proceed, and the mouthpiece portion With the core circumscribing the core, the vicinity of the inner peripheral surface of the mouth tube portion can be kept in a softened state in which the progress of crystallization is suppressed and is relatively easy to deform above the softening temperature. Can be sufficiently exerted, accumulation of internal strain due to post-shrinkage can be suppressed, and residual strain in the cooled and solidified state can be more effectively suppressed.

The present invention has the above-described configuration, and has the following effects.
In the first aspect of the invention, an outer diameter that forms a gap of 0.02 to 0.2 mm with respect to the inner peripheral surface immediately after the thermal crystallization treatment of the mouth tube portion at a predetermined temperature for a predetermined time. By inserting and forming the cylindrical core which has this, the PET-type resin housing which has the mouth tube part which has heat resistance which is not in the past can be provided.

  In the invention according to claim 2, the temperature of the inserted core is adjusted to the range of 90 to 130 ° C., thereby making the product made of a PET resin having a mouth tube portion having high heat resistance without distortion. A housing can be provided.

  In the invention according to claim 3, it is possible to provide a casing having a mouth tube portion which is small in deformation and has no practical problem even under retort processing conditions.

  In the invention according to claim 4, a cylindrical shape having an outer diameter that forms a gap of 0.02 to 0.2 mm with respect to the inner peripheral surface immediately after the thermal crystallization treatment at a predetermined temperature for a predetermined time. By the method of inserting the core, it is possible to provide a PET resin preform having a mouth tube portion having unprecedented heat resistance.

  In the invention according to claim 5, the temperature of the inserted core is controlled in the range of 90 to 130 ° C., so that it is made of a PET resin having a mouth tube portion having high heat resistance without distortion. A preform can be provided.

Embodiments of the present invention will be described below.
FIG. 1 is an explanatory view showing an example of an apparatus for thermally crystallizing the mouthpiece portion 2 in the preform 1 in order to obtain the PET resin casing of the present invention. The injection-molded preform 1 is inserted into a holder 4, and the mouth tube portion 2 including the neck ring 3 is heated by an infrared heater 5 to perform a thermal crystallization process. At this time, heating is performed while rotating the holder 4 in order to make the heating uniform in the circumferential direction. Biaxial stretch blow molding is performed using the preform 1 in which the mouth tube portion 2 is thermally crystallized in this manner to obtain a PET-based resin casing.

  The above-mentioned conditions for the thermal crystallization treatment are generally performed at a temperature of 150 to 220 ° C. for 1 to 3 minutes, and this condition is selected in consideration of the heat resistance (such as sterilization treatment temperature) required for the casing 1. The higher the required heat resistance, the higher the heating temperature must be. For example, general fruit juice beverages are filled at a high temperature of 80 to 90 ° C., but the heat treatment condition is 150 ° C. for about 2 minutes at the surface temperature of the mouth tube portion. At a surface temperature of about 180 ° C. for about 2 minutes.

  Since the thermal crystallization treatment at a predetermined temperature for a predetermined time is performed without inserting the core 6, when thermal crystallization proceeds by heating with the infrared heater 5, the mouthpiece portion is not restricted due to volume shrinkage accompanying crystallization. Shrink in a free state.

  FIG. 2 is an explanatory view showing a method for obtaining the housing of the present invention, and shows a state where the core 6 is inserted into the mouth tube portion 2 of the preform 1. (A) is a state in which the core 6 is inserted immediately after the thermal crystallization treatment at a predetermined temperature for a predetermined time, and (b) is a state in which the diameter of the mouth tube portion 2 is reduced by post-contraction due to cooling and circumscribed to the core 6 after insertion. It is explanatory drawing which shows. In the state (a), a gap t is formed between the inner peripheral surface of the mouth tube portion 2 and the outer peripheral surface of the core 6. Here, the temperature of the core 6 is cooled and adjusted so that the temperature is in the range of 90 to 130 ° C. even in the state inscribed in the high-temperature mouth tube portion 2.

  In the state of FIG. 2A, the extent of the gap t including the range is determined in consideration of conditions such as the diameter of the mouthpiece 2 and the temperature of the thermal crystallization treatment. Specifically, a preliminary test was conducted to evaluate the variation between preforms, the variation due to the location of the inner diameter of the mouth portion of one preform, the variation in thermal shrinkage due to thermal crystallization treatment, etc. By determining the outer diameter of 6, it can be appropriately determined within the range of 0.02 mm to 0.2 mm.

Example A preform 1 made of PET resin and having a nominal diameter of 28 mm was formed by injection molding, and this preform 1 was formed with the apparatus shown in FIG. 1 at a surface temperature of the mouthpiece of 180 ° C. for 2 minutes. A thermal crystallization process is performed, and immediately after this process, the outer diameter core 6 having a gap t of 0.04 to 0.15 mm is controlled while the temperature is controlled to 100 to 120 ° C. Inserted into part 2 and cooled. Then, the preform 1 in which the mouth tube part 2 was thermally crystallized under the above conditions was biaxially stretched and blow molded by a conventional method to obtain a casing of an example having an internal volume of 500 ml. In the present example, the density of the mouthpiece portion 2 was 1.398 g / cm ³ .

Comparative Example Using the same preform 1 as in the example, the core 6 was inserted into the mouth tube part 2 of the preform 1 in a sliding state, and then thermal crystallization treatment was performed under the same conditions as in the example. The preform 1 was biaxially stretched and blow molded by a conventional method to obtain a comparative casing having an internal volume of 500 ml. In this comparative example, the density of the mouthpiece portion 2 was 1.384 g / cm ³ .

  The casings of the above examples and comparative examples are filled with water, subjected to retort treatment with pressurized water under conditions of 124 ° C. for 20 minutes, and then the change in the diameter (inner diameter and outer diameter) before and after the retort treatment at room temperature is measured. did.

  In the examples, the outer diameter change of the mouth tube portion 2 was −0.14 mm, and the inner diameter change was −0.18 mm. In the comparative example, the outer diameter change of the mouth tube portion 2 was −0.41 mm, and the inner diameter change was −0.42 mm. Here, the number of test pieces is 5, and the above values are average values, and minus indicates that the diameter is reduced.

  As can be seen from the above results, the diameter of the caliber is reduced in any case by the retort treatment, but the degree of the case of the example is about 1/2 to 1/3 compared to the case of the comparative example. The deformation (reduction in diameter) was within a range where there was no practical problem such as screwing and unscrewing of the cap and sealability. On the other hand, the casing of the comparative example has a problem in sealing performance by the cap after retort processing.

  In the above embodiment, the embodiment of the invention of the present application and its operation and effects have been described mainly using a case for retort as an example. However, the present invention is not limited to the above embodiment, and the operation and effect of the present invention is Is generally exhibited in applications that require heat treatment at an unprecedented high temperature such as 100 ° C. or higher.

  As described above, the PET-based resin casing of the present invention can suppress deformation of the mouth tube portion even in high-temperature processing such as retort sterilization, and is expected to be widely used for retort food applications. .

It is explanatory drawing which shows an example of the apparatus for the thermal crystallization process of a preform mouthpiece part. FIG. 2 shows a state of inserting a core into a mouthpiece portion of a preform in the thermal crystallization process of the present invention, (a) shows a state in which a core is inserted immediately after thermal crystallization treatment at a predetermined temperature for a predetermined time, and (b) shows a mouth. It is explanatory drawing which shows the state which the cylinder part shrunk | retracted and circumscribed the core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Preform 2; Mouth part 3; Neck ring 4; Holder 5; Infrared heater 6; Core t;

Claims (5)

In a polyethylene terephthalate-based resin casing formed by biaxial stretching blow molding using a preform having a thermally-crystallized mouth tube portion, the mouth tube portion has the heat crystal at a predetermined temperature for a predetermined time. Made of polyethylene terephthalate resin, characterized in that it is formed in a state in which a cylindrical core having an outer diameter that forms a gap of 0.02 to 0.2 mm is inserted into the inner peripheral surface immediately after the conversion treatment Body. The polyethylene terephthalate-based resin casing according to claim 1, wherein the temperature of the inserted core is adjusted to 90 to 130 ° C. The polyethylene terephthalate-based resin casing according to claim 1 or 2, which is used for food applications that require retort treatment. Immediately after the thermal crystallization treatment of the polyethylene terephthalate-based resin preform at a predetermined temperature for a predetermined time, the outer diameter formed a gap of 0.02 to 0.2 mm with respect to the inner peripheral surface. A method for thermal crystallization of a preform mouthpiece, wherein a cylindrical core is inserted. The method for thermal crystallization of a preform mouthpiece portion according to claim 4, wherein the temperature of the inserted core is adjusted to 90 to 130 ° C.

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