JP5463716B2 - Preform compression mold, synthetic resin blow molding container manufacturing method, and preform - Google Patents

Description

  The present invention is a preform compression molding mold for blow molding under suitable conditions with reduced or omitted reheating when continuously preforming a preform, a method for producing a synthetic resin blow molded container, Furthermore, it relates to the preform.

Synthetic resin containers are widely used in daily life as containers for beverages and foods due to their light weight, economy, and excellent physical properties. In particular, containers (pet bottles) molded from polyethylene terephthalate (so-called PET) are in great demand as containers for soft drinks, beverages and foods due to their excellent mechanical properties and transparency. It is heavily used.
As described above, a synthetic resin container represented by polyethylene terephthalate is generally stretch blow molding in which a fluid (such as air) is blown into a preform (preliminarily formed bottomed cylindrical molding material) in a molding die. It is efficiently manufactured by a method (simply called stretch molding or blow molding).

Conventionally, an injection molding method has been used for molding a preform. However, a compression molding machine has been proposed as a molding apparatus that can be downsized and low-temperature molded at a lower cost than an injection molding apparatus. In order to increase mass productivity and improve manufacturing efficiency, a rotary compression molding machine (rotary movable compression molding machine) in which a large number of molding dies are attached to a rotating disk has been developed and adopted.
In the case of compression molding, a preform is sequentially and continuously molded from a synthetic resin by a compression molding machine, and the molded preform is immediately and continuously supplied to a blow molding machine by a conveyance line, and is sequentially and continuously molded into a container in the blow molding machine. The Therefore, the preforms molded by the compression molding machine can continue to blow molding while maintaining a high temperature and there is almost no variation in temperature, and stable bottles. It can be said that it is preferable from the viewpoint of not only obtaining moldability but also maintaining sterility of the filling system.

JP 2007-276493 A

  Patent Document 1 discloses a suitable take-off temperature at which no preform is subjected to external heat treatment with a gas burner or hot air when taking out a preform from a molding die of a compression molding apparatus, and no distortion is formed in the preform. ing.

The temperature of each part immediately after the molding of the preform molded by the compression molding machine depends on the wall thickness. On the other hand, in a system that directly connects preform molding and blow molding, the nozzle part (mouth part) is used when removing the preform from the core (male mold) after preform molding or during high-pressure air sealing during blow molding. In order to avoid deformation due to such stress and mouth deformation due to compressed air itself, the temperature of the nozzle portion is restricted to a certain temperature or lower. On the other hand, in order to lower the temperature of the nozzle part after compression molding, if it is excessively cooled for a long time in the compression molding die, the temperature of the body part and / or the bottom part of the preform is also lowered. When the preform is stretch blow molded immediately after simplifying the heating process, sufficient stretch molding may not be possible. For this reason, in blow molding, a temperature adjustment by partial heating or the like is required at a portion where the preform temperature is low, and a large amount of heat energy is required when the temperature is extremely low.
One object of the present invention has been made in view of such circumstances, and at the time of blow molding of a preform, a preform compression mold that can reduce or omit temperature adjustment by a heating device, and Another object of the present invention is to provide a method for producing a blow molded container made of synthetic resin.

In order to solve the above-mentioned problem, a method for producing a synthetic resin blow-molded container according to a first aspect of the present invention comprises a preform having a mouth, a trunk and a bottom for forming a synthetic resin blow-molded container. A preform compression molding die having a female mold and a male mold that form a space for compression molding, with respect to the space width (t1) that forms the thickness of the upper end of the mouth of the preform, the preform compression molding die at least the body portion of the space width (t2) is to be in the range of 1.18 to 2.11 times of the space width for forming a thickness of up to the bottom of the body portion of the preform in the synthetic resin blow-molded container manufacturing method using, by polyethylene terephthalate which has been heated and melted above the melting temperature of the compression mold, the compression molding step of compression molding the preform, after the compression molding After the mold cooling, and the mold was taken out step of taking the preform from the compression molding die, the preform after the mold was taken out process saw including a blow molding process for forming a container by blow molding, in said compression molding step By performing the clamping time in the range of 3 to 8 seconds, the maximum reached surface temperature of the mouth after molding of the preform is set in the range of 30 ° C to 60 ° C, and the preform after compression molding is successively continued. After being taken out, it was put into a blow molding machine and blow molded.
In order to solve the above problems, a method for producing a synthetic resin blow-molded container according to a second aspect of the present invention comprises a preform having a mouth, a trunk and a bottom for forming a synthetic resin blow-molded container. A preform compression molding die having a female mold and a male mold for forming a space for compression molding, and a space for forming a wall thickness from a lower portion of the preform mouth portion to an upper portion of the neck ring portion. With respect to the width (t3), at least the space width (t2) of the body portion of the space width forming the thickness from the body portion to the bottom portion of the preform is in the range of 1.18 to 2.11 times. In a method for producing a synthetic resin blow-molded container using a preform compression mold, a polyethylene terephthalate heated and melted at a temperature higher than the melting temperature is added to the compression mold. A compression molding process for compression molding into a preform, a mold ejection process for taking out the preform from the compression molding mold after cooling the mold after the compression molding, and a blow molding of the preform after the mold ejection process And a blow molding step for forming a container, and in the compression molding step, by performing the mold clamping time in the range of 3 to 8 seconds, the maximum surface temperature of the mouth after molding the preform is 30 ° C. The preform was subjected to compression molding after it was continuously taken out, and then put into a blow molding machine for blow molding.

The blow molded container manufacturing method of the present invention comprises a female mold and a male mold that form a space for compression molding a preform having a mouth, a trunk and a bottom for forming a blow molded container made of synthetic resin. A preform compression molding die provided with a space width (t1) for forming a wall thickness of the upper end portion of the mouth of the preform or a wall from a lower portion of the preform mouth to the upper portion of the neck ring. The space width (t2) of at least the body portion of the space width forming the thickness from the body portion to the bottom portion of the preform is 1.18 to 2.11 times the space width (t3) that forms the thickness. in the synthetic resin blow-molded container manufacturing method using a preform compression molding die was in the range, by polyethylene terephthalate which has been heated and melted above the melting temperature of the compression mold, pressure to the preform After forming the compression molding process, cooling the mold after the compression molding, taking out the preform from the compression molding mold, and blow-molding the preform after the mold removing process to form a container look including a blow molding step in said compression molding step, by performing mold clamping time in the range of 3 to 8 seconds, mouth maximum arrival surface temperature range of 30 ° C. to 60 ° C. of the molded preform The preforms after compression molding were taken out sequentially and continuously, then put into a blow molding machine and blow molded, so the preforms compressed using this mold were cooled and removed. After that, the portion from the lower portion of the mouth portion to the upper portion of the neck ring portion is suitably cooled, and the body portion can easily obtain a sufficiently high temperature state. Accordingly, it is possible to prevent deformation due to heat from the lower part of the mouth part to the upper part of the neck ring part, and to reduce or omit the heat treatment during the blow molding process for the body part.

1 is a schematic view of a PET bottle beverage aseptic filling system equipped with a preform compression mold according to an embodiment of the present invention. It is a schematic plan view mainly having the bottle manufacturing part of the PET bottle beverage aseptic filling system of FIG. It is a general | schematic enlarged plan view of the resin molding apparatus in the compression molding apparatus of FIG. 2, and its previous process. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the state which cut | disconnected the preform in embodiment of this invention in the up-down direction, A is sectional drawing of the whole preform, B is an expansion which shows the case where the mouth upper end part of a preform is a sharp shape. Sectional drawing C is an enlarged sectional view showing a case where a tapered surface is formed at the upper end of the mouth. It is sectional drawing of the initial position of the compression molding die of the preform of the compression molding apparatus shown in FIG. It is sectional drawing in the clamping state of the compression molding die of the preform shown in FIG. FIG. 5 is a process diagram showing a work procedure of a preform compression mold, and A is a cross-sectional view of a state in which a gripping member conveys molten resin to a cavity mold at an initial position when molding a preform compression mold, B is a cross-sectional view of a state in which molten resin is supplied to the cavity mold and the core mold and the slide insert mold are lowered, C is a cross-sectional view immediately before mold clamping, and D is the mold clamping of FIG. FIG. 5 is a cross-sectional view of the core mold and the slide insert mold after being detached. The relationship between the compression molding mold mold clamping time (mold cooling time due to mold closing) and the mold thickness required to reach the desired maximum temperature with the preform wall thickness (corresponding to the mold space width). In the diagram shown, it is plotted for each desired maximum temperature.

Hereinafter, a method for manufacturing a preform compression mold and a blow molded container according to an embodiment of the present invention will be described using a PET bottle beverage aseptic filling system A.
As shown in FIG. 1, this PET bottle beverage aseptic filling system A is formed from a polyethylene terephthalate (PET), which is a synthetic resin, to form a preform (hereinafter sometimes abbreviated as PF), and a bottle manufacturing unit C which is a container manufacturing unit. PF supply part B to be supplied to the bottle, the bottle manufacturing part C described above for producing a PET bottle as a main body of the container by biaxial stretching blow from the preform, and a PET bottle filled with beverage or food and sterilized sealed A filling sealing part D for sealing with a “sterilized cap” as a stopper, a cap sterilizing part E for sterilizing the cap as a container sealing member and supplying it to the filling machine, and a cap supply part F for supplying the cap And the drink supply part G which supplies the prepared drink, and the drink heating sterilizer H which heat-sterilizes the prepared drink are comprised. The dotted line portion indicates the clean box I.

  As shown in FIG. 2, the PF supply unit B is provided with a resin supply device 1, and the resin supply device 1 is provided with a cylindrical molten resin extruder 2 and a cutter wheel 8. The extruder 2 heat-melts and kneads a synthetic resin material such as polyethylene terephthalate, and conveys the molten resin to an internal gear pump in order to stably convey the molten resin. The gear pump is connected to a downward extrusion nozzle 4 through a conduit, and the extrusion nozzle 4 forms an extrusion opening at the lower end thereof, is formed into a substantially cylindrical shape from the extrusion opening, and is continuously pushed downward, It is supplied to the wheel 8. The cutter wheel 8 is provided with a gripping member 9 a (A in FIG. 7) that grips the molten resin cut by the cutter provided on the rotating turret 9.

The bottle manufacturing unit C includes a compression molding device 31 and a blow molding machine 52, and the compression molding device 31 includes a rotation support 32 and a plurality of cavity molds 34 disposed on the rotation support 32. Is provided. In the case shown in FIG. 3, the rotary support 32 is driven to rotate in the counterclockwise direction opposite to the cutter wheel 8. A plurality of cavity molds 34 are arranged at equal intervals in the circumferential direction of the rotary support 32.
The cutter wheel 8 is configured such that the tangent line between the rotating track of the molten resin gripping member and the rotating track of the cavity mold 34 is in the same direction, and the peripheral speeds thereof coincide with each other. In the position or section of the rotation trajectory, the molten resin gripping member 9a (A in FIG. 7) is synchronously rotated so as to be positioned immediately above the cavity mold 34 of the compression mold 33 in the compression molding apparatus 31. . Thus, the molten resin is disposed in the cavity mold 34.

Next, the preform compression mold and the preform molded by this compression mold will be described in detail.
First, the preform 5 shown in FIG. 4 will be described.
As shown to A of FIG. 4, the preform 5 is provided with the opening part 5a, the trunk | drum 5b, and the bottom part 5c from the upper part toward the lower part. The mouth portion 5a includes an opening 5d that serves as an injection / pour-out port for beverages and the like when the container is molded, a male screw portion 5e into which a female screw of the cap is screwed, and an annular turnip portion that is disposed below the male screw portion 5e. 5f and a neck ring portion 5g. The body portion 5b of the preform 5 is formed below the neck ring portion 5g. In the present embodiment, a connecting portion 5k that connects the mouth portion 5a and the body portion 5b is provided. In the present embodiment, the connecting portion 5k is formed such that the inner wall of the preform 5 is reduced in diameter downward from the upper end to the lower end of the neck ring portion 5g, and passes through the inclined portion 5h having a shape close to the inclined surface of the truncated cone. The body 5b is connected to the body 5b having a thickness t2 ′ thicker than the upper thickness t1 ′ of the portion 5a. The trunk portion 5b includes a trunk upper portion 5m continuous from the connecting portion 5k, and a trunk lower portion 5n connected via the connecting portion 5p. In the connecting portion 5p, the inner wall of the preform is reduced in diameter toward the lower inner peripheral surface, and an inclined surface 5q close to the inclined surface of the truncated cone is formed. The upper 5 m of the trunk is usually in the range from the bottom of the neck ring to 20 mm, and the thickness of the upper 5 m of the trunk is thinner than the thickness of the lower 5 n of the trunk. May be. In this method, at least from the lower 5 mm of the neck ring portion 5g toward the lower portion, a preferable preform mold take-out temperature can be realized by satisfying a thickness condition described later.

Further, in the present embodiment, the bottom 5c has a substantially hemispherical shape, but at least a portion of the bottom 5c that is continuous with the body 5b is also thicker than the top thickness t1 ′, t3 ′ of the mouth 5a. Has been. The thickness of the bottom 5c itself may be set as appropriate depending on whether the portion is stretched or blow-molded, and is thicker than t1 ′ and t3 ′ when molded, and is equal or thinner when not molded.
In the compression molding die described later, as shown in FIG. 6, a space for forming a thick portion of the preform is formed, and the space widths t1, t2, and t3 are respectively the thicknesses t1 ′, t2 ′, Although it is set to a value close to t3 ′, depending on the resin to be compression-molded, a value slightly larger than t1 ′, t2 ′, and t3 ′ is appropriately set in consideration of the shrinkage rate and the like.

  It should be noted that the upper end of the mouth portion 5a may have a sharp corner as shown in FIG. 4B, or is chamfered to reduce the corner slightly as shown in FIG. 4C? Alternatively, it may be rounded. In the case where some corners are dropped, in determining t1, as shown in FIG. 4C, the inner diameter Do of the mold 5a (corresponding to the outer diameter do of the preform product) forming the upper end of the outer diameter portion of the mouth 5a. (Diameter) and a mold outer diameter di (diameter corresponding to the inner diameter Di in the preform product) forming the upper end of the inner diameter portion are determined, and t1 = (Do-di) / 2. If it is difficult to inspect and measure the outer diameter or inner diameter at the upper end of the inner / outer diameter part, the upper end of the inner / outer diameter part is close to the upper end of the inner / outer diameter part. The t1 may be set / manufactured by determining the dimensions of a portion that is easy to inspect, such as 0.7 mm or 2.5 mm below the top surface of the mouth 5a.

5 and 6 show the compression mold, FIG. 5 is a cross-sectional view of the state where the compression mold is opened, and FIG. 6 is a cross-sectional view of the state where the compression mold is closed.
The compression molding mold 33 includes a cavity mold 34 that is a female mold, a core mold 35 that is a male mold, a slide insert mold 36 that is a split mold, and a guide ring 37 that is disposed around the cavity mold 34. It has. A core mold 35 is disposed above the vertical direction, a slide insert mold 36 is disposed below the core mold 35, and a cavity mold 34 is disposed below these core molds 35.

The cavity mold 34 has a substantially cylindrical shape, and forms a cavity 38 having a circular opening 34a on the upper side inside the center portion, and the cavity 38 is formed so as to extend almost directly downward from the opening 34a. The inner peripheral surface of the cavity 38 forms the outer peripheral surface of the preform.
The core mold 35 is provided with a support portion 35a at the top, and a substantially cylindrical core main body 35b extending downward from the center of the lower surface of the support portion 35a is provided at the bottom of the support portion 35a. The outer peripheral surface of the core body 35b forms the inner surface of the preform. And in the part which the core main body 35b forms the inner wall of the connection part 5k which is a boundary part of the opening | mouth part 5a and the trunk | drum 5b, the reduced diameter part 35d diameter-reduced radially inward toward the lower side is formed, A portion of the inclined portion 5h of the preform 5 described above is formed.
An annular recess 35c disposed concentrically with the core body 35b is formed on the lower surface of the support portion 35a so as to be recessed upward.
The slide insert mold 36 is divided into right and left parts and is a semicircular ring symmetrical with respect to the vertical plane, and both are formed into an annular shape. The slide insert mold 36 is formed with a nozzle forming hole 36a that vertically penetrates the center in a state where the split mold is assembled. The nozzle forming hole 36a forms the outer peripheral surface of the mouth part (also referred to as a nozzle part) 5a of the preform 5 and the upper part of the mouth part 5a, and forms a male screw 5e, a fogger part 5f, a neck ring part 5g, and the like. It becomes a forming part.

The cylindrical guide ring 37 is disposed on the outer peripheral surface 34e of the cavity mold 34, and can slide on the outer peripheral surface 34e in the vertical direction. At the upper end of the guide ring 37, a tapered inner truncated cone surface 41a is formed that expands radially outward toward the upper side. When the preform compression molding die 33 is clamped, the inner frustoconical surface 41a slightly slides on the outer frustoconical surface 41b of the slide insert die 36, and then forms an initial fitting portion 41 (FIG. 6) that abuts. .
As shown in FIG. 6, when the preform compression molding die 33 is clamped, the same space as the preform 5 shown in FIG. 4 is formed, and the preform 35 is inserted between the core body 35b and the insert die 36. A gap t1 having the same size as the mouth portion upper wall thickness t1 ′ of the reform 5 is formed, and between the core body 35b and the cavity mold 34, from the lower portion 5f of the preform 5 to the upper portion of the neck ring portion 5g. A gap having substantially the same size as the wall thickness is formed to form the wall thickness t3 ′, the body thickness t2 ′, and the bottom thickness.
Although not described, the core die 35 and the slide insert die 36 are provided with moving means for moving them up and down, and the slide insert die 36 is provided with a slide mechanism for opening and closing the left and right sides.

A rotary preform take-out mechanism 50 (FIGS. 2 and 3) is disposed downstream of the compression molding apparatus 31, and the preform 5 is transferred from the compression molding apparatus 31 to the blow molding machine 52. The blow molding machine 52 forms a PET bottle by stretching the preform with high-pressure air.
A WBZ (Wet Blocking Zone) 54 (FIG. 1) is provided as a sterilized partition between the bottle manufacturing unit C and the filling and sealing unit D of the downstream continuous line. The WBZ 54 prevents a part of the beverage from splashing into the bottle manufacturing unit C and deteriorating the sterility level of the molded PET bottle.

The filling and sealing unit D includes a filling machine 56 that fills a PET bottle with a predetermined amount of beverage, and a winding machine 58 that seals the PET bottle supplied from the cap sterilization unit E. The filling machine 56 is supplied with the beverage prepared by the beverage supply unit G and sterilized by the beverage heating sterilizer 60.
The cap sterilization unit E includes a cap sterilizer 59 that sterilizes the screw-type cap supplied by the cap supply unit F. The compression molding device 31, the blow molding machine 52, the filling machine 56, the winding machine 58, and the cap The sterilizer 59 is disposed in the clean box I.
The clean box I is one of the means for cleaning the machine installation environment that keeps the inside clean and positive pressure by substantially blocking the inside from the general environment and introducing purified air into the inside. This cleaned air is generated by passing air from the general environment through a HEPA filter or ULPA filter.

Next, a preform molding procedure using the preform compression molding die 33 will be described.
Referring to FIGS. 3 and 7A, the cavity mold 34 is moved on a circular path by the rotary support 32. On the other hand, the gripping member 9 a that grips the molten resin 43 provided on the cutter wheel 8 rotates on a circular orbit separate from the cavity mold 34. 7A shows one of a plurality of compression molding dies 33 of the compression molding apparatus 31. FIG. In the initial state, the cavity mold 34, the slide insert mold 36, and the core mold 35 are arranged apart from each other in the vertical direction. The circular orbits of the gripping member 9a and the cavity mold 34 are configured to supply a molten resin 43 (drop) to the bottom of the cavity 38 of the cavity mold 34 with one contact (tangential line) in common in the vertical direction. .

When the molten resin 43 is supplied to the cavity mold 34, the gripping member 9a leaves the track of the cavity mold 34, and the core mold 35 and the slide insert mold 36 are lowered as shown in FIG. 7B. Next, the slide insert mold 36 that is open to the left and right is advanced toward the core mold 35 to close the slide insert mold 36 into an annular shape. The core body 35b of the core mold 35 is in a state of penetrating the nozzle forming hole 36a.
As shown in FIG. 7C, when the core mold 35 is further lowered, the tip end portion of the core body 35b enters the cavity 38, and the slide insert mold 36 contacts the guide ring 37. That is, after the outer frustoconical surface 41b of the outer convex portion 36d on the lower outer peripheral portion of the slide insert mold 36 temporarily contacts the inner frustoconical surface 41a of the upper inner peripheral surface of the guide ring 37, these surfaces are The guide ring 37 and the slide insert mold 36 are in contact with each other while being fitted and slid. In addition, the slide insert mold 36 is configured such that the annular protrusion 36b is fitted and abutted with the annular recess 35c at the upper portion to form a fitting portion 42. At the lower part of the slide insert mold 36, the outer convex part 36 d is fitted and abutted on the guide ring 37.

When the core mold 35 is further lowered from the state of C in FIG. 7, the core body 35 b starts to compress the molten resin 43. When the core mold 35 is lowered, the slide insert mold 36 and the cavity mold 34 come into contact with each other at the fitting portion 40 and the fitting portion 39. When the core mold 35 is lowered to the lowermost position, as shown in FIG. 6, the cavity mold 34, the core mold 35, and the slide insert mold 36 form a gap in which the molten resin 43 has a preform shape. The molten resin 43 fills the gap and the mold is clamped.
Since the slide insert mold 36, the core mold 35, and the cavity mold 34 are cooled to 15 ° C. by circulation of cooling water (not shown), the molten resin 43 is also cooled in the state shown in FIG. If the mold clamping time is long, the surface temperature of the mouth 5a is lowered. In the present embodiment, since the thickness of the mouth portion 5a of the preform 5 is thin, not only the surface of the mouth portion 5a but also the inside of the thickness portion is cooled relatively quickly. However, the body portion 5b and the bottom portion 5c are more than the mouth portion 5a. Since the wall thickness is thick, even if the surface starts to cool slightly, the temperature inside the wall is still high. When the molten resin 43 is cooled and reaches the temperature for taking out from the molding die, the compression molding die 33 is opened, and both the core die 35 and the slide insert die 36 are raised. Since the nozzle 5 is sandwiched between the core molds 35, the preform 5 rises together with the core body 35b.

Next, as shown in FIG. 7D, the core mold 35 and the slide insert mold 36 are released, and the preform 5 is pulled out from the core body 35b. The preform 5 is removed from the slide insert mold 36 by opening the slide insert mold 36 to the left and right.
When the preform 5 is released from the compression mold 33, the internal temperature of the preform 5 is high, so that heat is transferred from the inside to the outside, and the surface temperature rises. Although depending on the thickness of the preform and the cooling conditions of the mold, the temperature of the preform surface usually reaches a temperature close to the maximum temperature in 2 to 10 seconds after the preform 5 is removed from the mold. The temperature difference from the interior of the reform is reduced to the preferred range for blow molding.

  By the way, from the viewpoint of preventing deformation of the mouth portion 5a of the preform 5 when taking out the preform from the male die (core die) after compression molding or sealing compressed air (nozzle seal) in blow molding. The temperature of the part 5a is preferably low. On the other hand, in order to perform blow molding, if the temperature of the body part 5b is low, it is necessary to apply heat by an infrared heater such as near infrared, hot air, radiant heat or the like. The surface temperature condition for blow molding of the body portion 5b and the bottom portion 5c is, for example, a PET resin having a glass transition temperature of about 78 ° C., and the preferred lower limit of the surface temperature is 80 ° C. exceeding the glass transition temperature of the preform. The upper limit is limited to 120 ° C. in order to prevent whitening or uneven thickness during blow molding and to obtain stable moldability. The wall thickness distribution of the bottle after molding may be adjusted. If the surface temperature is slightly below the lower limit (about 70 ° C.), the temperature near the inside of the preform is higher than the surface, so blow molding may be possible without heating, and the temperature distribution in the preform If it is necessary to apply, the corresponding portion is heated in a short time by a heating device such as an infrared heater, so that blow molding is possible without using a large amount of heating device. In addition, when the surface temperature of the preform exceeds the upper limit (for example, about 130 ° C.) or when the temperature distribution is given to the preform in the lowering direction, the corresponding portion of the preform surface is slightly changed between compression molding and blow molding. Good blow moldability can be obtained by air cooling.

If the mold clamping time is long in the compression molding, the cooling time of the preform becomes long, and the risk of deformation of the mouth portion 5a is reduced, but it is necessary to heat the preform to a temperature necessary for blow molding. When the mold clamping time is short, the temperature necessary for blow molding is reached, but the mouth portion 5a is deformed. Therefore, it is difficult to control the cooling of the mouth portion 5a and the temperature for blow molding the body portion 5b at the same time, and if the temperature of the mouth portion 5a is adjusted low to prevent the deformation of the mouth portion 5a, the body portion The temperature of 5b also became low and required a lot of incidental facilities such as a heating device.
In the present embodiment, the upper wall thickness t1 ′ of the preform mouth portion 5a, the lower thickness of the turntable or the neck ring upper wall thickness t3 ′ are reduced, and the wall thickness 5b of the body portion 5b is increased (the above-mentioned in the mold). Since t1 and t3 are narrow and t2 is wide), the mouth portion 5a is cooled quickly, and the temperature of the trunk portion 5b and the bottom portion 5c is kept high. Therefore, the use of a heating device such as an infrared heater can be reduced and further eliminated.

In addition, since it is important to ensure dimensional stability in order to ensure the sealing performance of the contents by fitting with the cap, the upper part of the mouth part 5a forms the upper wall thickness t1 ′ of the mouth part 5a. The space width t1 of the mold was used as a reference for the space width t2 of the mold that forms the thickness t2 ′ of the body portion 5b. In addition, of the mouth portion 5a, the problem is the thickness of the tip (upper) end portion of the mouth portion 5a. During blow molding, a load of about 1000 N is applied to the tip of the mouth portion for sealing (sealing) of high pressure air. For this reason, the end of the mouth is designed to withstand the load.
Further, if the thickness under the turnip is close to the thickness of the body portion, this portion is also deformed by blow molding pressure (compressed air pressure; about 3 MPa) during blow molding, so that a thickness t3 ′ under the turnip is formed. The space width t3 of the mold was also used as a reference for t2.
Further, from the viewpoint of sterilization, the higher the take-out temperature of the preform, the better for the “heat sterilized state” of the preform. In the present embodiment, the sterilized state of the preform 5 is maintained by setting the minimum temperature location on the surface of the preform 5 to at least 60 ° C. or higher.

As shown in FIG. 1, on the downstream side in the rotation direction of the compression molding device 31, a take-out mechanism 50 for taking out the preform 5 molded from the cavity mold 34 is arranged, and as shown in D of FIG. The preform 5 removed from the slide insert mold 36 is rotated and conveyed to a downstream blow molding machine by a take-out mechanism 50 (not shown).
The molded preform 5 is transferred to the take-out mechanism 50. In this take-out mechanism 50, when the temperature is low during the conveyance of the preform, it is necessary to heat the preform 5 with an infrared heater or the like. However, in this embodiment, the temperature of the body portion 5b and the bottom portion 5c is high. Heating by the heater can be omitted or reduced.
That is, the preforms after compression molding are sequentially and continuously taken out from the compression mold 33 and put into the blow molding machine 52, so that the molding speed of the blow molding machine 52 is equal to or higher than the molding speed of the compression mold 33. If so, the compression-molded preform does not have a waiting time until blow molding, and can be blow-molded immediately. The preform 5 conveyed from the take-out mechanism 50 to the blow molding machine is set in a blow molding die, injected with high-pressure air, and stretched in the vertical and horizontal directions to be molded into a container. The compression molding device 31, the take-out mechanism 50, and the blow molding machine 52 are mechanically connected by gears or the like, or are electrically synchronized by a servo motor, so that the compression molded preform has a constant time until blow molding. In this case, variations in individual preform temperatures immediately before blow molding can be suppressed, so that stable blow molding is possible.

The filling machine 56 fills the PET bottle with a predetermined amount of beverage through a filling line (liquid feeding line) that has been heat sterilized with high-temperature sterile water in advance. The winding machine 58 winds and seals the sterilized screw cap supplied from the cap sterilizing unit E around the mouth of the beverage-filled PET bottle. In the cap sterilization part E, for example, an EB (electron beam) irradiation device, a UV (ultraviolet light) irradiation device, or a peracetic acid rinser can be used.
As described above, in this embodiment, each device is substantially blocked from the inside and the outside by the clean box I, so that the sterilization effect can be enhanced and the beverage can be filled in the PET bottle. The interior of the clean box I is periodically sterilized and thus periodically reset to the initial sterility level.

Examples of the present invention will be described below.
FIG. 8 shows a mold corresponding to the thickness of the preform after taking out a preform made of PET (polyethylene terephthalate) resin having a glass transition temperature of about 78 ° C. in a mold set at 15 ° C. It is a diagram which shows the relationship of the clamping time (mold cooling time by mold closing) of a compression molding die required to reach a desired maximum temperature with respect to (space width). The vertical axis represents the mold cooling time (seconds), and the horizontal axis represents the thickness of the preform (corresponding mold space width) (mm).
From FIG. 8, when the desired maximum temperature and the mold cooling time are determined, the thickness of the preform can also be obtained. For example, the desired maximum temperature is 60 ° C. and the cooling time is 4 seconds. In this case, the preform thickness (corresponding to the mold space width) is 1.70 mm, and 1.82 mm when the cooling time is 5 seconds. (Since it is difficult to read in the diagram, an accurate numerical value is shown.) If the wall thickness (corresponding mold space width) is less than 1.40 mm, it is difficult to perform compression molding of the preform, so the diagram is drawn. Absent.

As described above, a suitable surface temperature immediately after molding of a preform for performing blow molding is equal to or higher than the glass transition temperature (about 78 ° C.) of the preform, and is generally 80 ° C. to 120 ° C. Within this temperature range, the preform body 5b is blown with a temperature distribution to adjust the thickness distribution of the bottle after molding. In the case where the sterilizing effect is not required for the container, the temperature of the mouth portion 5a is preferably low, and may be 60 ° C. or lower in order to suppress deformation of the mouth portion (nozzle portion) 5a of the preform.
On the other hand, as a condition for blow molding, the body portion 5b needs to be in the range of 80 to 120 ° C. as described above, and there is a temperature difference with the temperature of the mouth portion 5a. In order to solve this temperature difference, the thickness of the mouth portion 5a (corresponding to the mold space width) is made thinner than the thickness of the body portion 5b (corresponding to the mold space width), and the mouth portion 5a is cooled. To make it faster.
Therefore, the conditions for performing blow molding are the upper wall thickness (corresponding to the mold space width) t1 of the mouth part 5a or the wall thickness below the capra or neck ring (corresponding mold space width) t3, The ratio (t2 / t1) or (t2 / t3) to the thickness (corresponding to the mold space width) t2 of the body portion 5b was obtained with reference to the diagram of FIG.

Table 1 shows the upper limit 30 ° C. and 60 ° C. of the maximum ultimate surface temperature after molding of the preform for each mold clamping time in the left two rows and the left three rows in the left one row. The thickness (corresponding to the mold space width) of the mouth portion 5a for this purpose is obtained from FIG. Further, the thickness (corresponding to the mold space width) of the body portion 5b for satisfying the lower limit temperature 80 ° C. and the upper limit temperature 120 ° C. of the blow molding conditions after preform molding in the left 4 rows and the left 5 rows is shown in FIG. Seeking from.
In the left 6 columns to the left 8 columns, the upper wall thickness (corresponding to the mold space width) t1 of the mouth portion 5a obtained from the left 2 rows and the left 3 rows, which is the object of the present embodiment, or under the neck and the neck. Thickness (corresponding to mold space width) of thickness (corresponding to mold space width) t2 of the wall thickness 5b of each temperature obtained in the left 4 rows and left 5 rows (the corresponding mold space width) t3 on the ring (T2 / t1) or (t2 / t3) was determined.
As a result, when the nozzle temperature is 30 ° C. to 60 ° C., the wall thickness (corresponding mold space width) ratio is 1.18 to 2.11 times when the clamping time is in the range of 3 to 8 seconds. If it is within the range, the blow molding condition is satisfied. When the nozzle temperature is set to 60 ° C., the wall thickness (corresponding mold space width) ratio is within the range of 1.18 to 1.56 times when the mold clamping time is within the range of 3 to 8 seconds. If so, the conditions for blow molding are satisfied.

The present invention has been described in detail based on the embodiments with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and other modifications can be made without departing from the scope of the present invention. Or it can be changed.
For example, if the mold space width t2 forming the preform body 5b satisfies the conditions of the present invention, the width may be changed within the condition range. In addition, the mold space widths of the bottom 5c and the connecting portion 5k may satisfy the conditions of the present invention, or may not be satisfied in the direction of narrowing. This is because, for example, in the case of a container that does not require the bottom portion to be sufficiently stretched, there is no problem even if the vicinity of the center of the preform bottom portion is relatively thin and set to a cooling condition. The same applies to the connecting portion 5k.
Moreover, you may provide the connection part 5k or 5p by changing the diameter of the metal mold | die which forms the preform outer surface side.
Further, the connecting portion 5k including the truncated cone-shaped inclined portion 5h may be omitted, and the mouth portion 5a and the trunk portion 5b may be connected stepwise on the inner surface side (so that the portion 5h is horizontal). .
Moreover, as long as the compression molding die satisfies the conditions of the present invention even if it is a cavity (die space), a known one may be used regardless of the division assembly position and mechanism.
In addition, the compression molding apparatus and blow molding apparatus are also configured to be capable of being quickly blow molded by a blow molding machine (through a simple temperature adjusting device added as necessary) after the preform is compression molded. The layout is not particularly limited.
Furthermore, the present invention is not limited to operations on preform molding, bottle molding, and beverage filling systems in an aseptic environment, and may be used in continuous molding from preform compression molding to bottle molding in a normal environment. .

  Since the preform taken out from the mold after compression molding has a high temperature, the present invention can be suitably used for a container manufacturing / content filling system in which sterility is desired.

2 Extruder 5 Preform 5a Mouth (nozzle)
5b Body 5c Bottom 5f Cabra 5g Neck ring 5h Inclined 8 Cutter wheel 31 Compression molding device 33 Compression mold 34 Cavity mold 35 Core mold 36 Slide insert mold 52 Blow molding machine A PET bottle aseptic filling system C bottle manufacturing department

Claims (2)

A preform compression molding die comprising a female mold and a male mold for forming a space for compression molding a preform having a mouth portion, a trunk portion and a bottom portion for forming a synthetic resin blow molded container. The space width (t1) that forms the wall thickness from the body part to the bottom part of the preform with respect to the space width (t1) that forms the wall thickness of the upper end part of the mouth of the preform. In the method for producing a blow molded container made of a synthetic resin using a preform compression molding die that is in the range of 1.18 to 2.11 times ,
A compression molding step of compressing and molding polyethylene terephthalate heated and melted above the melting temperature into a preform by the compression molding die;
After the mold cooling after the compression molding, a mold removing step for removing the preform from the compression molding mold,
The preform after the mold was taken out process saw including a blow molding process for forming a container by blow molding,
In the compression molding step, by performing the mold clamping time in the range of 3 to 8 seconds, the maximum surface temperature of the mouth after molding the preform is set in the range of 30 ° C to 60 ° C, and the compression molding is finished. A method for producing a synthetic resin blow-molded container, wherein the reforms are successively taken out successively and then put into a blow molding machine for blow molding . A preform compression molding die comprising a female mold and a male mold for forming a space for compression molding a preform having a mouth portion, a trunk portion and a bottom portion for forming a synthetic resin blow molded container. The space width (t3) that forms the thickness from the lower portion of the preform portion to the upper portion of the neck ring portion, at least the space width that forms the thickness from the trunk portion to the bottom portion of the preform. In the synthetic resin blow molding container manufacturing method using the preform compression molding die using the preform compression molding die whose space width (t2) of the body portion is in the range of 1.18 to 2.11 times ,
A compression molding step of compressing and molding polyethylene terephthalate heated and melted above the melting temperature into a preform by the compression molding die;
After the mold cooling after the compression molding, a mold removing step for removing the preform from the compression molding mold,
Including a blow molding process for forming a container by blow molding the preform after the mold removal process,
In the compression molding step, by performing the mold clamping time in the range of 3 to 8 seconds, the maximum surface temperature of the mouth after molding the preform is set in the range of 30 ° C to 60 ° C, and the compression molding is finished. A method for producing a synthetic resin blow-molded container, wherein the reforms are successively taken out successively and then put into a blow molding machine for blow molding.

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