JP4993714B2 - Method for producing polyester resin container with easy opening at break - Google Patents

Description

  The present invention is a so-called twist-off in which a container main body having an opening and a sealing body that seals the opening of the container main body are integrally formed via a weakly breakable portion formed at the boundary between the two. More particularly, the present invention relates to a method of manufacturing a container that can be easily opened and easily weakened at a weakened portion of a container made of polyester resin.

The container main body having the opening and the sealing body for sealing the opening of the container main body are integrally formed through a weakly fragile portion formed at the boundary between the two, and the sealing body is picked and twisted. Or opening the opening of the container body by breaking the weakened part and severing the sealing body from the container body by pushing down the sealing body, so that the opening of the so-called twist-off container or snap-off container can be easily opened Containers have been conventionally known, for example, as disclosed in the following Patent Document 1 relating to the applicant's application.
JP 2002-321750 A

  By the way, the container with easy break opening as described in the above-mentioned Patent Document 1 relating to the application of the present applicant was developed for a container that gradually uses contents such as a tube container. The main body is manufactured from an olefin resin that is easily plastically deformed so as to have flexibility suitable for squeezing the contents. In such an olefin resin container, an opening due to twist-off or snap-off is provided. Since it is easy and no trace of breakage remains, there is no particular problem in breaking the weakened portion and opening the container.

  Compared to the container of such an olefin resin, in the case of a polyester resin, since it is hard to be plastically deformed, it is sticky, and it is difficult to break even if it forms a weakened part (a part to be broken). Almost no consideration was given to the use of such a container with an easy opening, but the polyester resin had better content resistance than the olefin resin, was inert to the contents, and had no resin odor. Therefore, in recent years, there has been a demand for the appearance of a container made of a polyester resin that can be easily opened by opening as a container for beverages or medicines that uses up the contents at once, instead of a soft squeeze container such as a tube container.

  However, as described above, since the polyester resin is more viscous than the olefin resin, when used in a container that is easy to break open, when the weakened part is broken and the sealed body is separated from the container body, the weakened part May be difficult to break, and may cause a phenomenon of pulling the yarn at the broken portion of the weakened portion.

  An object of the present invention is to solve the above-described problems. Specifically, a container body having an opening and a sealing body that seals the opening of the container body are formed at the boundary between the two. For a container that is easily formed from a polyester resin and is easily opened through a weakened portion that is easily broken, the weakened portion is easily broken so that the container can be easily opened. Is an issue.

In order to solve the above-described problems, the present invention provides a container body having an opening and a sealing body that seals the opening of the container body via a weakly fragile portion that is formed at the boundary between the two. As a method for forming an easily breakable weakened portion at the boundary between the container body and the sealed body, the wall thickness of the weakened portion is set as follows. After forming the thin wall portion by thinning, the laser is irradiated to the thin wall portion, and when the groove is formed in the thin wall portion , the output is 1.0 as a condition for irradiating the laser. ˜100 W, the laser pulse width is 6 to 10 μsec, the laser period is 60 to 100 μsec, the laser spot diameter is 200 to 400 μm, and the container is 0.1 to 0.1 relative to the laser irradiation. 1 By rotating at around 0 rpm, in the groove and portions of the periphery thereof, without changing the density of the resin, it is characterized in that so as to lower the intrinsic viscosity of the resin.

  According to the above-described method for manufacturing a polyester resin container having an easy break opening according to the present invention, a thin wall portion is formed by thinning a wall thickness at a weakened portion, and then laser irradiation is performed. By forming the groove by resin sublimation in the thin wall portion, the groove portion is further thinned by the thin wall portion, the weakened portion is easily broken, and the groove of the thin wall portion Since the intrinsic viscosity of the resin is reduced without changing the density of the resin around the periphery, the portion becomes brittle and the weakened portion is easily broken.

A container body having an opening and a sealing body that seals the opening of the container body are integrally formed through a weakly fragile portion that is formed at the boundary between the two, and an easy break opening made of a polyester resin The purpose of making the weakened part easy to break and making it easy to open the container with respect to such a container, as specifically shown in the following examples as the best mode, As a method for forming a weakened portion that can be easily broken at the boundary, a thin wall portion is formed by thinning the wall thickness of the weakened portion, and then the thin wall portion is irradiated with a laser. When forming the groove in the thin wall portion , the laser irradiation conditions are as follows: the output is 1.0 to 100 W, the laser pulse width is 6 to 10 μsec, the laser period is 60 to 100 μsec, and the laser Spot diameter 200 to 400 μm, and by rotating the container around 0.1 to 100 rpm relative to the laser irradiation , the resin can be changed without changing the resin density in the groove and its peripheral portion. This was achieved by lowering the intrinsic viscosity of.

  In addition, about the polyester resin used as the material of the container in the present invention, for example, as an acid component, adipic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4-biphenylcarboxylic acid, succinic acid, succinic acid, glutar It consists of one or more selected from acids, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecadioic acid, trans-1,4-cyclohexanedicarboxylic acid, and isophthalic acid. Selected from methylene glycol (1,3-propanediol), tetramethylene glycol (1,4-butanediol), pentamethylene glycol, hexamethylene glycol, 1,4-hexanedimethanol, bisphenol A, spiroglycol 1 or 2 or more types A polyester resin or a copolymerized polyester, the (preferably 0.8~1.3dl / g) intrinsic viscosity 0.8~1.5dl / g polyester resins suitable for blow molding.

  One example of the method for producing a polyester resin container that can be easily opened by breakage according to the present invention, which is carried out using the polyester resin as described above, will be described below.

  In the production method of this example, as the polyester resin as the material of the container, the acid component is terephthalic acid, and the glycol component is 4 mol of 1,4-cyclohexanedimethanol or bisphenol A with respect to 96 mol% of ethylene glycol. % Added polyester resin. This polyester resin has an intrinsic viscosity of about 1.0 dl / g, does not draw down during direct blow molding, has a melting point of about 235 to 245 ° C., and is 10 to 30 ° C. than a general polyester resin. Since it is low and can be molded at a low temperature, rapid cooling is possible. Furthermore, since the crystallization rate is low, the moldability is good.

  In this embodiment, as described later, a cylindrical parison having a diameter of about 25 mm and a thickness of about 0.8 mm, which is extruded from an extruder, is used for a container that is easily made from such a polyester resin. As shown in FIG. 1 and FIG. 2, the manufactured container 1 with easy opening and breaking is a container main body for storing the contents. 2 and a sealing body 3 that seals the container main body 2 are integrally formed via an easily breakable weakened portion (a portion to be broken) 4 formed at the boundary between the two.

  In the container body 2, a cylindrical body portion 22 is formed upward from a circular plate-shaped bottom portion 21, and has a smaller diameter than the body portion 22 from the upper end of the body portion 22 through a curved shoulder portion 23 (the diameter of the parison). A cylindrical neck portion 24 having substantially the same diameter) is formed, a top plate portion 25 is formed inward from the upper end of the neck portion 24, and a frustoconical mouth portion protrudes upward from the center of the top plate portion 25. 26 is formed, and a weakened portion 4 that is easily broken as a boundary with the sealing body 3 is formed in an annular shape as viewed from above at the upper end formed on the flat horizontal surface of the mouth portion 26.

  In the sealing body 3, a hollow bell-shaped portion 31 that seals the opening of the container body 2 and a flat plate portion 32 that serves as a knob when the container is opened include a flat plate portion 32 having a width substantially the same as the diameter of the parison. It is integrally formed so as to straddle the bell-shaped part 31 from above. The lower end of the bell-shaped part 31 is located slightly below the lower end of the flat plate part 32, and the lower end of the bell-shaped part 31 formed on a flat horizontal surface is easily weakened as a boundary with the container body 2. Part 4 is formed.

  As will be described later, the weakened portion 4 formed at the boundary between the container body 2 and the sealed body 3 is formed into a thin wall portion by reducing the wall thickness after normal direct blow molding. By irradiating the laser, a groove is formed in the thin wall portion, and the intrinsic viscosity of the resin is lowered at the groove and its peripheral portion without changing the resin density, thereby making the portion brittle. In order to be able to irradiate the weakened part 4 formed on the thin wall part with a laser, both sides of the lower end of the flat plate part 32 of the sealing body 3 are at an angle of 45 ° to 60 ° with respect to the axial direction of the container. It has a shape as if it was cut out.

  In the polyester resin container 1 in which the container main body 2 and the sealing body 3 are integrally formed through the weakened portion 4 as described above, the flat plate portion 32 of the sealing body 3 is pinched with a fingertip or twisted, or the sealing body 3 The weakened portion 4 that connects the container main body 2 and the sealing body 3 is broken by pushing down the flat plate portion 32 of the container, and the sealing body 3 is separated from the container main body 2, thereby the bell of the sealing body 3. The mouth portion 26 of the container body 2 that has been closed by the shape portion 31 is opened.

  By the way, the method of the present embodiment for producing the polyester resin container 1 as described above will be described in detail below. In the method of the present embodiment by the direct blow molding method, first, in the parison extrusion step, the melt was performed. The polyester resin is extruded as a hollow cylindrical parison having a diameter of about 25 mm and a thickness of about 0.8 mm from the nozzle of the extruder.

  As shown in FIG. 3, the mold for molding the extruded parison includes a split lower mold 7 in which the outer surface shape of the bottom, body, shoulder and neck of the container body is formed inside, and the parison. The parison 6 that is extruded from the extruder 5 with respect to each of the molds 7 and 8 that are connected in series with each other is formed of a split auxiliary mold 8 having an inner surface shape that is in contact with the outer surface of each mold 6. It is pushed out while it is split into 7 and 8.

  When the tip of the extruded parison 6 is pushed out beyond the lower end (bottom) of the lower molding die 7, the lower molding die 7 and the auxiliary die 8 are simultaneously closed as shown in FIG. 4 in the mold closing process. By closing the lower end of the lower mold 7, the tip (lower end) of the hollow cylindrical parison 6 is sealed to form the bottom, and the cutter 9 immediately above the auxiliary mold 8 operates immediately. Thus, the upper part of the parison 6 is separated from the extruder 5.

  The molds 7 and 8 in a state where the parison 6 separated from the extruder 5 is accommodated and closed are transferred to a blow process, and in the blow process, as shown in FIG. 5, a lid 10 having a conduit 10a is provided. A pressurized fluid, such as compressed air of about 10 atm, is put on the auxiliary mold 8 and aseptically blown into the inside of the parison from the conduit 10a. The bottom part 21, the body part 22, the shoulder part 23, and the neck part 24 are formed.

  Next, the molds 7 and 8 containing the parison molded at the lower part are moved to the contents filling step with the lid 10 removed. In the contents filling step, as shown in FIG. The filling nozzle 11 is inserted, and contents such as a functional beverage or a liquid medicine are filled into the molded container body at the lower part of the parison. When the filling of the contents is completed, the filling nozzle 11 is extracted, the auxiliary mold 8 is opened, and the lower mold 7 containing the parison in which the lower part is molded into the container body and filled with the contents is Then, the process proceeds to a sealing body forming step.

  In the sealing body forming step, as shown in FIG. 7, the split outer molding die 12 in which the outer surface shapes of the top plate portion 25 and the mouth portion 26 of the container body 2 are formed inside, and the bell-shaped portion of the sealing body 3. 31 and a split inner molding die 13 in which the outer surface shape of the flat plate portion 32 is formed on the inside are installed in a state in which the inner molding die 13 is incorporated inside the outer molding die 12. The top part 25 and the mouth part 26 of the container body 2 are formed by sandwiching the unmolded upper part between the molds 12 and 13 and closing the molds 12 and 13. The bell-shaped portion 31 and the flat plate portion 32 are formed, and the container filled with the contents is completely sealed.

  The outer mold 12 and the inner mold 13 for molding the upper part of the parison are such that the inner mold 13 is about 0.3 to 1 mm in the axial direction (vertical direction) of the container with respect to the outer mold 12. If it is installed so that the distance can be moved and the process of forming the sealed body is completed and the process immediately proceeds to the weakened part forming process, in the weakened part forming process, as shown in FIG. Then, the inner mold 13 is slightly moved downward (0.5 mm in this embodiment), so that the tip of the inner mold 13 becomes the container body 2 (mouth portion 26) and the sealing body 3 (bell shape). The thin wall portion that bites into the portion that becomes the boundary of the portion 31) and that becomes thinner than the wall thickness obtained by normal blow molding is formed in the portion that becomes the weakened portion 4.

  When the molding of the container is completed as described above, the outer molding die 12, the inner molding die 13, and the lower molding die 7 are opened and moved while the inner molding die 13 is moved upward. In the case of the present embodiment, each of the steps of the parison extrusion process, the mold closing process, the blowing process, the content filling process, the sealed body forming process, and the weakened part forming process is performed aseptic booth. Since it is performed in the inside, the sterilization process of the container is omitted.

  In the container formed through the respective steps as described above, in the method of this embodiment, the thin wall portion formed in the weakened portion 4 is further separated from the laser gun 14 as shown in FIG. A laser (a carbon dioxide laser in this embodiment) is irradiated under specific conditions. In the method of the present embodiment, the thin wall portion formed in the weakened portion 4 is sunk inward from the upper surface of the mouth portion 26, so that the laser to be irradiated is in the axial direction (vertical direction) of the container. In contrast, the laser beam is irradiated at an angle of 45 ° to 60 °. The tilt angle of the laser is any angle as long as the laser reaches the thin wall portion of the weakened portion 4. Is also good.

The conditions for irradiating the laser, the method of the present embodiment, the output and 1.0～100W, the laser pulse width is 6～10Myu sec, and the laser frequency as 60～100Myu sec, the laser spot diameter While being 200-400 micrometers, it is made to rotate a container about 0.1-100 rpm relatively with respect to laser irradiation.

Specifically, as the most preferable laser irradiation conditions, relative to its output 30 W, the laser pulse width 8 micron sec, the laser cycle 80 [mu] sec, while the laser spot diameter is 300 [mu] m, the irradiation of the laser In particular, the container is rotated at about 1 rpm. In such a case, after the laser irradiation, it was not necessary to collect and cool the resin in order to avoid crystallization of the resin.

  As for rotating the container relative to the laser irradiation, for example, the laser is irradiated in a fixed direction from a fixed laser gun and the container is rotated (rotated) around its axis. Alternatively, an appropriate method is possible, such as moving the laser gun around the fixed container and always directing the irradiation direction of the laser gun toward the container. Is.

By irradiating the thin wall portion of the weakened portion with a laser under specific conditions as described above, in the portion irradiated with the laser of the thin wall portion that becomes the weakened portion 4, the resin is sublimated by laser irradiation, The remaining thickness is about 50% of the thickness of the original thin wall portion, and a groove having a remaining thickness of about 0.25 mm is formed. In addition, the intrinsic viscosity of the resin is about 15% lower than the original intrinsic viscosity, and the original intrinsic viscosity is about 1.0 dl / g, which is about 0.85 dl / g. The density of the resin is hardly changed from the value before laser irradiation, and exhibits a non-crystallized state value of 1.38 g / cm ³ or less.

  According to such a polyester resin container that is easy to break open and manufactured by the method of this embodiment, a groove is formed at the portion irradiated with the laser of the thin wall portion that becomes the weakened portion 4, and the wall thickness is extremely high. Since the resin is thin and the resin density remains the same, the intrinsic viscosity of the resin is reduced, and the resin is brittle, so it can be twisted off or snapped off with a small force of 70 to 80 N · cm. Thus, the container can be easily opened with a weak force.

  As mentioned above, although one Example of the manufacturing method of the polyester resin container with easy breaking opening of this invention was described, the method of this invention is not limited only to the above Examples, For example, a weakening part In the above embodiment, the inner molding die 13 for molding the sealing body 3 is moved downward, and the tip (lower end) of the inner molding die 13 is moved to the container body 2 (mouth portion). 26) and the blocking body 3 (bell-shaped portion 31) are bitten into a portion to reduce the wall thickness of the portion to form a thin wall portion. However, the present invention is not limited to such a method. , By moving the inner molding die 13 for molding the sealing body 3 upward and stretching the portion that becomes the boundary between the container body 2 (mouth portion 26) and the sealing body 3 (bell shaped portion 31), For example, the wall thickness of the part may be reduced to form a thin wall part. It is needless to say that those that can be changed to.

The front view which shows an example of the container made from a polyester resin with the easy opening break by the manufacturing method of this invention. The side view of the container shown in FIG. Cross-sectional explanatory drawing which shows the parison extrusion process in one Example of the manufacturing method of this invention. Cross-sectional explanatory drawing which shows the mold closing process in one Example of the manufacturing method of this invention. Cross-sectional explanatory drawing which shows the blow process in one Example of the manufacturing method of this invention. Cross-sectional explanatory drawing which shows the content filling process in one Example of the manufacturing method of this invention. Cross-sectional explanatory drawing which shows the sealing body shaping | molding process in one Example of the manufacturing method of this invention. Cross-sectional explanatory drawing which shows the weakening part shaping | molding process in one Example of the manufacturing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyester resin container with easy break opening 2 Container body 3 Sealed body 4 Weakened part 14 Laser gun

Claims (1)

A container body having an opening and a sealing body that seals the opening of the container body are integrally formed through a weakly fragile portion that is formed at the boundary between the two, and an easy break opening made of a polyester resin As a method for forming a weakened portion that can be easily broken at the boundary between the container main body and the sealed body, a thin wall portion is formed by reducing the wall thickness of the weakened portion, and this thin wall When the groove is formed in the thin wall part by irradiating the laser with the laser, the conditions for irradiating the laser are that the output is 1.0 to 100 W, the laser pulse width is 6 to 10 μsec, laser period as the 60～100Myusec, while the laser spot diameter and 200 to 400, by rotating relatively vessel before and after 0.1~100rpm to the irradiation of the laser, the groove In portions of the periphery thereof, without changing the density of the resin, breaking open easy process for producing a polyester resin container, characterized in that so as to lower the intrinsic viscosity of the resin.

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