JPH07257536A - Synthetic resin bottle, its manufacturing method and shrink device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a synthetic resin bottle with good accuracy, which has no trace of a receiving rod at the center of the bottom. [Structure] A synthetic resin bottle with no trace of a receiving rod in the center of the bottom 12 is (a) a parison blow-molded into a primary molded body 10.
(B) The pressure rod 7 which is installed outside the bottom 12 of the primary molding 10 and moves at a speed corresponding to the speed at which the primary molding 10 shrinks, and is inserted and lifted from the mouth of the primary molding 10. The primary molded body 10 is once shrunk in a state where the central portion of the bottom portion 12 is sandwiched by the receiving rod 5 that freely projects, and (c)
After that, it is obtained by performing blow molding again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin bottle, a method for producing the same, and an apparatus used for producing the same. The present invention relates to a shrink device used for manufacturing the shrink device.

[0002]

BACKGROUND OF THE INVENTION Biaxially stretched blow molded bottles made of synthetic resin such as polyethylene terephthalate have excellent transparency and surface gloss, are beautiful, and have good gas barrier properties and moisture resistance. It has excellent permeability, resistance to contents, and storage stability. In addition, it has many advantages such as low heat generation during combustion and easy disposal because it does not damage the furnace. Therefore, it is widely used in various beverages, seasonings, bottles for foods such as alcoholic beverages, and the like.

In order to manufacture the above-mentioned synthetic resin bottle, a parison is usually biaxially stretch blow molded in one step,
The final shape of the bottle. However, since there is an unstretched part in the center of the bottom of the bottle thus manufactured, there is a problem in heat resistance and strength. In order to solve this problem, there is known a method in which a parison is first blow-molded to form a primary molded body, the primary molded body is once shrunk, and then blow-molded again. By carrying out by such a method, the unstretched part of the primary molded body can be stretched completely.

FIG. 5 shows an example of an apparatus conventionally used in the above-mentioned shrink method. The shrink device is a mouth part holding device 4 that holds the mouth part 11 of the primary molded body 10.
And a receiving rod 5 projecting vertically from the mouth holding device 4 into the primary molded body 10 and a heating pot 8 for covering the primary molded body 10. In the apparatus, in the state where the mouth 11 of the primary molded body 10 is held by the mouth portion holding device 4, the whole is covered with the heating pot 8 to be heated, and the central portion of the bottom 12 of the primary molded body 10 that shrinks accordingly. Was supported by the receiving rod 5 inserted from the mouth portion 11 to maintain the shape of the primary molded body 10.

However, as described above, the primary molded body 10
In the case of supporting only the receiving rod 5 from the inside of the, a slip occurs between the bottom 12 of the shrinking primary molded body 10 and the receiving rod 5, so that the primary molded body 10 cannot be accurately centered and the bottle There was a drawback that the accuracy of was low. In addition, when the retracting speed of the receiving rod 5 is slower than the shrinking speed of the primary molded body 10, as shown in FIG. 5, the central portion 12 of the bottom portion may be protruded by the receiving rod 5 and the receiving rod trace 12a may be largely attached. there were. Such a receiving rod mark 12a could not be erased even by re-blow molding.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a synthetic resin bottle which is free of traces of receiving rods in the central portion of the bottom and has good precision.

Another object of the present invention is to provide a method for producing a synthetic resin bottle with good accuracy while leaving no trace of a receiving rod at the center of the bottom.

Further, another object of the present invention is to provide a shrink device capable of performing accurate centering with almost no mark of a receiving rod at the center of the bottom.

[0009]

As a result of earnest research for solving the above-mentioned problems, the present inventor obtained the present invention by temporarily shrink-molding a primary molded body produced by blow molding a parison and then blow-molding it again. When manufacturing synthetic resin bottles, primary molding is performed with the center part of the bottom part clamped by a pressure rod that moves at a speed that corresponds to the shrinking speed of the primary molded product and a vertically movable receiving rod that faces it. If you shrink your body, you won't lose its bottom shape,
Further, they have found that centering can be performed accurately, and have completed the present invention.

That is, the bottle of the present invention made of synthetic resin, which is obtained by shrink-molding a primary molded body produced by blow molding a parison and then blow molding again, is installed outside the bottom of the primary molded body. A state in which the central portion of the bottom portion is clamped by a pressure rod that moves at a speed corresponding to the speed at which the primary molded body shrinks, and a receiving rod that is inserted from the mouth portion of the primary molded body and projects vertically Then, it is obtained by performing the shrinking.

According to the method of the present invention for producing a synthetic resin bottle as described above, a pressure bar is installed outside the bottom of the primary molded body and moves at a speed corresponding to the shrinking speed of the primary molded body. The shrinking is performed in a state in which the center portion of the bottom portion is sandwiched by the receiving rod that is inserted from the mouth portion of the primary molded body and projects upward and downward.

Further, the shrink device of the present invention used in the above method is a mouth holding device for holding the mouth of the primary molded body, and a receiver projecting vertically from the mouth holding device into the primary molded body. A rod, a pressure rod installed outside the bottom of the primary molded body so as to face the receiving rod, and a heating pot that covers the primary molded body, and the pressure rod is the receiving rod. While holding the central portion of the bottom of the primary molded body, the primary molded body moves at a speed corresponding to the shrinking speed of the primary molded body.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

[A] Configuration of Shrink Device FIG. 1 is a schematic sectional view showing a shrink device according to an embodiment of the present invention. The shrink device 1 includes a rotary table 2
A mouth holding device 4 attached to the
The receiving rod 5 penetrating through the central portion of the mouth holding device 4 and protruding upward and downward, the air cylinder 6 controlling the movement of the receiving rod 5, and the primary molded body installed above the receiving rod 5. A pressure rod 7 that moves at a speed corresponding to the speed at which
The heating pot 8 is installed above the receiving rod 5 so as to be vertically movable. The primary molded body 10 is shown by a chain double-dashed line in FIG.

The mouth holding device 4 has a locking portion 41 at the upper end and is divided into two. A fastener 42 is provided on the side of one of the divided pieces 4a, and by operating the fastener 42, the divided piece 4a slides in the horizontal direction, and the mouth of the primary molded body 10 is moved.
11 can be mounted and held. The fastener 42 penetrates the fastener guide 31 provided on the holding base 3, and one end thereof is fixed to the divided piece 4a. Further, the other end has a knob portion 42a, and the spring 42 is provided between the split piece 4a and the fastener guide 31.
b. The elastic force of the spring 42b causes the fastener 42 to bias the divided piece 4a.

The lower end of the receiving rod 5 is connected to a piston 61 that slides inside the air cylinder 6. The air cylinder 6 is provided with a gas flow path 62 that communicates from above inside to outside and a gas flow path 63 that communicates from below inside to outside. When the piston 61 descends, air flows in from a gas passage 62 provided above the air cylinder and air flows out from a gas passage 63 provided below, but the diameter of each gas passage is small, Since the inflow and outflow resistance of air is large, the movement of the piston 61 is slow. The degree of resistance of the piston 61 can be set by the diameters of the gas passages 62 and 63,
The bottom of the primary molded body 10 can be held together with the pressure bar 7, and the shrinkage of the primary molded body 10 is not hindered. Specifically, it is preferably 1 to 30 cm / min, particularly 3 to
10 cm / min is preferred. In addition, in order to fix the receiving rod 5, the gas passage 62 and / or the gas passage 63 may be sealed.

A cylindrical guide 32 is fixed to the holding base 3 and extends upward with a slight distance from the receiving rod 5. The cylindrical guide 32 has an enlarged diameter portion 32a at a lower portion of the locking portion 41 of the mouth portion holding device 4 so that the end portion of the mouth portion 11 of the primary molded body 10 abuts. The position of the upper end 32b of the cylindrical guide 32 is set in consideration of the size when the primary molded body 10 is shrunk. Support rod 5 and cylindrical guide 32
The gap between and is a gas flow path 33, which communicates with a gas flow path 64 provided in the air cylinder 6. Therefore, when the primary molded body 10 shrinks, the internal air can be exhausted through the gas flow path 64, and the air can be blown during the re-blow molding.

A side view of the heating pot 8 and the pressure rod 7 is shown in FIG.
Shown in. The heating pot 8 has a heater (not shown) inside, a driven gear 81 on the outer wall, and a bearing 82.
It is installed to be freely rotatable. The bearing 82 is fixed to the support bracket 9, and an idle gear 85 that meshes with the driven gear 81 and a drive gear 84 that is connected to the drive motor 83 and meshes with the idle gear 85 are rotatable on the support bracket 9. It is installed in. The heating pot 8 is a drive gear
Drive motor via 84, idle gear 85 and driven gear 81
It can be rotated by 83. The support bracket 9 can be raised and lowered, and accordingly, the heating pot 8 can also be raised and lowered, but any driving device thereof can be used.

The support bracket 9 includes an upper support bracket.
Two female screws 71 and a stepping motor 72 are fixed via 91, and a driven gear 73 is rotatably installed between the two female screws 71. The pressure rod 7 has a male screw 7a except for the lower side, and is screwed with the two female screws 71.
The pressure rod 7 and the driven gear 73 can slide integrally, and the driven gear 73 can slide in the axial direction of the pressure rod 7. The driven gear 73 meshes with a drive gear 74 connected to the stepping motor 72, and the rotation of the stepping motor 72 is transmitted to the pressure rod 7 via the drive gear 74 and the driven gear 73. Since the pressure rod 7 is screwed into the fixed female screw 71, the pressure rod 7 moves downward or upward while rotating. The rotation speed of the stepping motor 72 corresponds to the shrinking speed of the primary molded body 10 measured in advance by an experiment etc.
Is set to move.

In the shrink device 1 described above,
The mouth holding device 4, the receiving rod 5, and the air cylinder 6 are fixed to the peripheral edge of the turntable 2 as shown in FIG. On the other hand, the pressure rod 7 and the heating pot 8 are fixed together with the support bracket 9, and by rotating the rotary table 2, the mouth portion holding device 4, the receiving rod 5, and the air cylinder 6 are moved to the pressure rod 7 and the heating pot. It can be installed directly under 8.

A mold 20 having a cavity in the shape of the final bottle is installed adjacent to the pressure rod 7 and the heating pot 8 on the same circumference. The primary molded body 10 thus obtained can be immediately re-blow molded.

[B] Method of Manufacturing Synthetic Resin Bottle A method of manufacturing a synthetic resin bottle using the shrink device described above will be described. The primary molded body 10 can be produced by biaxially stretch blow molding a parison by a conventional method, and usually has a hemispherical bottom 12.

With the mouth 11 of the primary molded body 10 facing downward,
The receiving rod 5 and the cylindrical guide 32 are inserted into 11. By pulling the fastener 42 of the mouth portion holding device 4 in the radial direction, the divided piece 4a is expanded outward, and the end portion of the mouth portion 11 is expanded at the enlarged diameter portion 32 of the cylindrical guide 32.
Contact a. In this state, release the fastener 42, and
The support ring portion 13 of 10 is locked to the locking portion 41 of the mouth portion holding device 4, and the mouth portion 11 is held and fixed. At this time, the piston 61 in the air cylinder 6 is raised so that the upper end of the receiving rod 5 contacts the central portion of the bottom portion 12 of the primary molded body 10.

When the holding and fixing of the mouth portion 11 is completed, the rotary table 2 is rotated and the primary molded body 10 is placed directly below the pressure rod 7 and the heating pot 8. Next, the support bracket 9 is lowered and the primary molded body 10 is covered with the heating pot 8. The pressurizing rod 7 also descends as the support bracket 9 descends, but the lower end is adjusted so as to contact the central portion of the bottom portion 12 of the primary molded body 10.

The heating pot 8 is heated by the heater and the drive motor 83 is driven to rotate the heating pot 8 via the drive gear 84, the idle gear 85 and the driven gear 81. By rotating the heating pot 8 in this way, heat unevenness can be prevented. The heating temperature may be adjusted according to the type of resin constituting the primary molded body, but is preferably about 100 to 450 ° C, and particularly preferably about 250 to 350 ° C.

When the primary molded body 10 starts shrinking,
The stepping motor 72 is driven to lower the pressure rod 7. As set in advance, the pressure rod 7 is the primary molded body 10
Descends at the same speed that it shrinks. Pressure rod 7
As the receiving rod 5 is lowered, the receiving rod 5 is pressed against the bottom portion 12, and the piston 61 fixed to the lower end of the receiving rod 5 slides downward. As described above, the piston 61 slides while having a predetermined resistance, so that the receiving rod 5 holds the bottom portion 12 together with the pressing rod 7 as shown in FIG. By sandwiching the bottom portion 12 in this way, the receiving rod 5 does not slip and the centering can be performed accurately. In addition, the centering referred to here is
It refers to the determination of the position where the stretch rod abuts during re-blow molding, which position corresponds to the position where the catch rod abuts the bottom of the primary compact. The centering position is important for obtaining a highly accurate bottle, and the centering position is the bottom position.
Twelve cores are preferred.

Further, since the receiving rod 5 descends at the same speed as the shrink speed of the primary molded body 10, it is possible to maintain the hemispherical shape of the bottom 12 without projecting only the central portion of the bottom 12. It should be noted that although traces of the receiving rod and / or the pressure rod may be slightly left on the bottom of the primary molded body, it can be erased in the next step (re-blow molding).

After the shrinking of the primary molded body 10 is completed,
The rotary table 2 is rotated, the primary molded body 10 is set in the cavity of the mold 20, and biaxial stretch blow molding is performed by a conventional method. Specifically, pressurized air is blown into the primary molded body 10 from the gas flow paths 64 and 33, the piston 61 is raised, and the bottom 12 is pushed up by the receiving rod 5. Primary compact 10
Is heated and softened by the shrink, so that the shape of the cavity easily changes. The pressurized air and the mold may be heated depending on the case.

As described above, since the centering is accurately performed at the time of shrinking, it is possible to obtain a highly accurate bottle in this re-blow molding.

[C] Bottle Material The synthetic resin forming the bottle is not particularly limited as long as it is a thermoplastic resin capable of biaxially stretch blow molding, but a polyester type is preferable.

As the polyester resin, a thermoplastic resin composed of saturated dicarboxylic acid and saturated dihydric alcohol can be used. As the saturated dicarboxylic acid, terephthalic acid,
Aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyldicarboxylic acids, diphenoxyethanediethanedicarboxylic acids, adipic acid , Sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, and the like can be used. As the saturated dihydric alcohol, aliphatic glycols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol and neopentyl glycol are used. Glycols, alicyclic glycols such as cyclohexanedimethanol, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane, and other aromatic diols can be used. As the polyester resin composed of such a saturated dicarboxylic acid and a saturated dihydric alcohol, it is preferable to use polyethylene terephthalate composed of terephthalic acid and ethylene glycol.

The above polyester resin has an intrinsic viscosity of 0.5.
It has a value in the range from .about.1.5, preferably 0.55 to 0.8. Also, such polyesters are produced by melt polymerization, 1
Those that have been subjected to reduced pressure treatment or heat treatment in an inert gas atmosphere at a temperature of 80 to 250 ° C., or those that have reduced the content of oligomers and acetaldehyde, which are low molecular weight polymers by solid-state polymerization, are suitable.

A mixture of the polyester resin with a barrier resin or the like can be used. further,
The pressure resistant self-supporting bottle may not be a single layer of a polyester resin or a mixed resin of a polyester resin and a barrier resin or the like, but may be a multilayer using a barrier resin or the like and a polyester resin.

In the polyester resin used in the present invention, stabilizers, pigments, and
Additives such as antioxidants, heat deterioration preventing agents, ultraviolet deterioration preventing agents, antistatic agents, antibacterial agents, and other resins can be added in appropriate amounts.

The present invention has been described in detail above with reference to the drawings. However, the present invention is not limited to this, and various modifications can be made without departing from the idea of the present invention.
For example, the fastener included in the mouth holding device may be a screw type fastener, or a conveyor may be used instead of the rotary table.

[0036]

As described above in detail, in the bottle of the present invention, the shape of the bottom portion does not collapse during shrinking and the centering is performed accurately, so that there is no trace of the receiving rod and the accuracy is high. .

Further, in the method of the present invention, the central portion of the bottom portion is clamped by the pressure rod moving at a speed corresponding to the shrinking speed of the primary molded body and the vertically movable receiving rod facing the pressure rod. Since the primary molded body is shrunk, the shape of the bottom portion is not broken and the centering can be performed accurately.

Further, in the apparatus of the present invention, a pressure rod which is installed outside the bottom of the primary compact and moves at a speed corresponding to the shrinking speed of the primary compact, and is inserted from the mouth of the primary compact. In addition, since it has a receiving rod that projects so as to be able to move up and down, the above method can be easily performed.

The synthetic resin bottle of the present invention is suitable for containers of various foods and drinks such as carbonated drinks.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a shrink device according to an embodiment of the present invention.

FIG. 2 is a side view showing a pressure bar and a heating pot in FIG.

FIG. 3 is a schematic top view showing a shrink device according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a step of shrinking a primary compact by the method of the present invention.

FIG. 5 is a schematic cross-sectional view showing a step of shrinking a primary molded body by a conventional method.

[Explanation of symbols]

 1 ... Shrink device 10 ... Primary molding 11 ... Mouth 12 ... Bottom 12a ... Receiving rod mark 13 ... Support ring 2 ... Rotating table 20 ... Mold 3・ ・ ・ Holding base 31 ・ ・ ・ Fastener guide 32 ・ ・ ・ Cylindrical guide 32a ・ ・ ・ Expanded part 32b ・ ・ ・ Upper end 33, 62, 63, 64 ・ ・ ・ Gas flow path 4 ・ ・ ・ Mouth part Holding device 4a ・ ・ ・ Divided piece 41 ・ ・ ・ Locking part 42 ・ ・ ・ Fastener 42a ・ ・ ・ Knob 42b ・ ・ ・ Spring 5 ・ ・ ・ Receiving rod 6 ・ ・ ・ Air cylinder 61 ・ ・ ・ Piston 7・ ・ ・ Pressure rod 7a ・ ・ ・ Male screw 71 ・ ・ ・ Female screw 72 ・ ・ ・ Stepping motor 73, 81 ・ ・ ・ Drive gear 74, 84 ・ ・ ・ Drive gear 8 ・ ・ ・ Heating pot 82 ・ ・ ・ Bearing 83・ ・ ・ Drive motor 85 ・ ・ ・ Idle gear 9 ・ ・ ・ Support bracket 91 ・ ・ ・ Upper support bracket

Claims (3)

[Claims] 1. A synthetic resin bottle obtained by shrink-molding a primary molded body produced by blow molding a parison, and then blow-molding the parison again. The bottle is placed outside the bottom of the primary molded body. In a state in which the central portion of the bottom portion is sandwiched by a pressure rod that moves at a speed corresponding to the speed at which the molded body shrinks, and a receiving rod that is inserted from the mouth of the primary molded body and that projects upward and downward, A synthetic resin bottle characterized by being obtained by shrinking. 2. A method for producing a synthetic resin bottle obtained by subjecting a primary molded body produced by blow molding a parison to shrink once and then blow molding again.
A pressure rod installed outside the bottom of the primary molded body and moving at a speed corresponding to the speed at which the primary molded body shrinks; and a receiving rod that is inserted from the mouth of the primary molded body and projects vertically. A method of performing the shrinking while sandwiching the central portion of the bottom portion by the. 3. A device for shrinking a primary molded body produced by blow molding a parison, comprising: a mouth holding device for holding a mouth of the primary molded body; and an ascending / descending unit from the mouth holding device into the primary molded body. An apparatus having a receiving rod that freely projects, a pressure rod installed outside the bottom of the primary molded body so as to face the receiving rod, and a heating pot that covers the primary molded body, An apparatus, wherein the pressure rod moves at a speed corresponding to a speed at which the primary molded body shrinks, while sandwiching a central portion of a bottom portion of the primary molded body with the receiving rod.