JP2671138B2 - Method and apparatus for manufacturing modified parison for blow molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method and an apparatus for manufacturing a deformed deformed parison used for integrally molding a bottle having an inclined plug portion by blow molding. Regarding

[Conventional technology]

BACKGROUND ART Biaxially stretched blow molded bottles made of a thermoplastic resin such as polyester are widely used as containers for various beverages. Such bottles usually have a mouth coaxial with it at the upper end of the body. However, recently, a bottle having a mouth provided at a slightly inclined position instead of the upper end has been used. The bottle is housed in a paper container having a slope, and the mouth protrudes from the slope.

Conventionally, as such a bottle body, Japanese Utility Model Publication No. 56-150563,
The ones disclosed in Japanese Utility Model Publication Nos. 62-29375 and 62-29376 are known. Each of these bottles has a coaxial coaxial mouth at the upper end of the body that is biaxially stretch blow molded, but since the rudder bellows and other deformable parts are formed at the top of the body, The mouth portion can be tilted when housed in a predetermined paper container.

[Problems to be solved by the invention]

However, in the above-mentioned conventional bottle, since the mouth portion is inclined by the deforming means such as the rudder belly provided on the upper portion of the main body,
Extra irregularities will be present in the bottle body. The contents easily remain on these rudder belly parts and the like, which prevents smooth outflow of the contents. Further, since the surface area of the container is increased, characteristics such as gas barrier properties are reduced. In addition, by providing a deformed portion having a complicated shape such as the rudder belly portion, the manufacturing cost of the entire bottle increases.

Therefore, the present inventor has conducted various studies on a method for producing a synthetic resin bottle body having a slanted plug portion, and as a result, as a result, along the circumference of a radius R contacting the central axis of the parison near the plug portion. By discovering that a bottle with an inclined plug part can be obtained by inserting a stretch rod having the same radius of curvature as the circumference into the plug part of the parison and performing biaxial stretch blow molding, Applied for a patent.

However, in the above-described biaxial stretch blow molding method using a curved stretch rod, there is a problem that the apparatus is complicated because a stretch rod having a curvature has to be used in advance.

Therefore, an object of the present invention is to provide a method for producing a modified parison that can be easily formed into a bottle with a slanted plug portion by blow molding without using a device having a complicated mechanism.

Another object of the invention is to provide an apparatus for manufacturing such a modified parison.

[Means for solving the problem]

As a result of earnest research in view of the above object, the present inventor can easily produce a bottle with a slanted mouth portion by stretch blow molding by giving an appropriate bend to the body of the parison before stretch blow molding. The present invention was completed by discovering that it was possible.

That is, the first method for producing the blow molding modified parison of the present invention has a plug portion and a bottomed cylindrical body, and the center axis of the bottomed cylindrical body is curved. And a method for producing a blow molding deformed parison in which the draw ratio of each part of the bottomed cylindrical body is substantially the same,
(A) A mold having a bottomed cylindrical body forming a parison having a straight central axis, and (b) a mold having a curved groove is used, and in the softened state of the parison, the groove is formed in the mold. The body portion of the parison is slidably brought into contact with the body portion of the parison so that the body portion is bent.

The second method of manufacturing a modified parison for blow molding is
(A) The center axis of the bottomed cylindrical body forms a linear parison, (b) the body of the parison is uniaxially stretched in the longitudinal direction by a stretching rod at a temperature equal to or higher than the softening point, and (c) a bowl Using a mold having a curved groove, in the softened state of the parison, by sliding the body of the parison into sliding contact with the groove of the mold, a lateral force is applied to the body of the uniaxially stretched parison. It is characterized in that the body portion is bent over.

The first device for manufacturing blow-molded modified parison is
As a means for laterally pressing the body part of the parison, a mold having a curved groove is provided, and the body part of the parison is bent by sliding along the groove. .

The second device that produces a modified parison for blow molding is
As a means for laterally pressing the parison body, it has a rod-shaped member that is movable in the lateral direction, and presses the rod-shaped member against the body of the parison while holding the plug portion of the parison. By doing so, the body portion is bent.

The third device that produces a modified parison for blow molding is
A roller is provided as a means for laterally pressing the body of the parison, and the body of the parison is bent by pressing the body of the parison against the roller while holding the spigot of the parison. It is characterized by

The fourth device for manufacturing blow-molded modified parison is
A means for gripping the bottom of the parison, and by moving the means for gripping the bottom relative to the parison in a lateral direction while holding the spigot of the parison, the body of the parison Characterized by bending the section.

(Operation)

By bending the body of the parison before blow molding, it is possible to easily manufacture a stretch blow-molded product having an inclined plug portion with a substantially uniform wall thickness. This is because the parison's body is deformed in a curved shape, so in a blow molding mold that has a cavity with a shape in which the mouth plug is inclined, place the parison in the center of the bottom of the mold. It is believed that the parison body can be positioned and therefore the parison body is stretched at a substantially uniform magnification. By previously deforming the parison into a predetermined curved shape, the wall thickness of the bottle can be made substantially uniform even in the case of free blow without requiring a complicated mechanism.

〔Example〕

 The present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a modified parison manufactured according to an embodiment of the present invention. The parison 1 is composed of a plug portion 1a, a flange 1b and a bottomed cylindrical body portion 1c.

The curved state of the body 1c is determined according to the desired shape of the bottle to be molded. Generally, when manufacturing a bottle with a long body, the curved portion may be present near the spigot portion, and the body portion on the bottom side (tip portion) may be substantially linear. Further, the body portion may be curved with the same curvature, or may be partially curved with different curvatures.

In the present invention, the important requirements for determining the curved state of the parison body are: (a) the tip of the parison is located substantially in the center of the bottom of the mold cavity in the blow mold, and (B) The stretching ratio of each part of the parison body should be substantially the same. It is not limited to a particular bent state as long as the above requirements are met.

The modified parison manufactured by the method of the present invention may or may not be uniaxially stretched in the central axis direction in advance.

The deformed parison that has been uniaxially stretched in advance preferably has a length such that its tip reaches the bottom of the blow molding die. As a result, even if molding is performed by free blowing without using a stretch rod, the tip of the parison does not shake, and the thickness of the bottle can be accurately controlled to be uniform.

On the other hand, even in the case of a deformed parison that has not been uniaxially stretched in advance, since the tip of the parison faces the bottom of the mold, the tip can be brought into contact with the bottom of the mold even if it is free blown. However, in order to completely eliminate the risk of rash on the tip, it is preferable to use a stretch rod. In this case, a bent rod can be used in advance as the stretch rod, but it is also possible to use a stretch rod in which only the distal end portion of the stretch rod that penetrates into the parison is deformed into a bend. As the stretch rod whose only tip is bent, for example, a spring or a flexible tube having a predetermined bent shape is used, and a wire is connected to the tip and the spring or flexible tube is pulled when the wire is pulled. Although it contracts to form a straight line, it can be bent in a predetermined curved shape when loosened.

The thermoplastic resin used in the modified parison produced by the method of the present invention is preferably a polyester resin containing a saturated dicarboxylic acid and a saturated dihydric alcohol. Saturated dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenylcarboxylic acids, diphenoxyethanediethanedicarboxylic acids And the like, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid, and the like, and aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid and the like can be used. Further, as the saturated dihydric alcohol, ethylene glycol,
Propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol,
Aliphatic glycols such as dodecamethylene glycol, neopentyl glycol, cycloaliphatic glycols such as cyclohexanedimethanol, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane, and other aromatic diols are used. can do. A preferred polyester is polyethylene terephthalate consisting of terephthalic acid and ethylene glycol.

The polyester resin used in the present invention has an intrinsic viscosity of 0.5
It has a value in the range of 1.51.5, preferably 0.55 to 0.85. Such polyesters are also produced by melt polymerization,
Those subjected to a reduced pressure treatment or a heat treatment in an inert gas atmosphere at a temperature of 0 to 250 ° C., or those obtained by solid phase polymerization to reduce the content of oligomers and acetaldehyde, which are low molecular weight polymers, are preferable.

Incidentally, in the polyester resin used in the present invention, additives such as stabilizers, pigments, antioxidants, heat deterioration inhibitors, ultraviolet deterioration inhibitors, antistatic agents, antibacterial agents, etc. within the range not impairing the object of the present invention. And other resins can be added in appropriate amounts.

Next, a method and apparatus for manufacturing the modified parison of the present invention will be described.

FIG. 2 is a cross-sectional view showing a state where a bottomed cylindrical parison is uniaxially stretched in the longitudinal direction by a stretching rod. The straight stretch rod 2 is inserted from the plug portion of the parison 3,
It is pulled out after uniaxial stretching of the body 3C.

The uniaxial stretching ratio can be set arbitrarily, but when the parison is deformed and placed in the blow mold, the parison is stretched so that the tip of the parison is located approximately in the center of the bottom of the mold cavity. Preferably. As a result, blurring of the parison is prevented, and a blow-molded bottle body having a substantially uniform thickness can be obtained.

FIG. 3 is a vertical cross-sectional view showing an example of a device for deforming a parison body by applying a pressing force to the parison body from the lateral direction to bend it.
The drawing is a sectional view taken along the line AA of FIG. This device is a mold 4 in which a groove 5 having a curved and smooth surface is formed, and the groove 5 has a substantially semicircular cross section as shown in FIG. The curved state of the groove 5 can be variously set according to the desired curved state of the modified parison. Generally, in the case of blow molding a bottle with an inclined plug portion, the difference in the draw ratio during blow molding can be minimized as a whole by maximizing the curvature of the parison body near the plug portion. Therefore, it is preferable to form the groove 5 in a curved state corresponding to it. In such a case, the curvature of the upper portion 5a of the groove 5 is relatively large, and the curvature of the lower portion 5b is relatively small.
However, the shape of the groove 5 is not limited to such a shape, and can be an arbitrary curved state, for example, the groove 5 curved with a constant curvature.
It may be.

In addition, a heater 6 is embedded in the mold 4 inside the groove 5 in order to keep the deformed parison in a softened state.

5 to 8 are schematic cross-sectional views showing a series of steps for manufacturing a modified parison by deforming a straight parison body into a curved shape by using the apparatus shown in FIG.

As shown in FIG. 5, the parison 7 is first softened.
The stopper 7a is fixed on the mold 4 while being held by the holder 8. At this time, the tip of the parison 7 is positioned so as to contact the upper end of the groove 5 of the mold 4.

Next, as shown in FIG. 6, when the mold 4 is slowly lifted, the body portion 7C of the parison is brought into sliding contact with the groove 5 and is deformed into a curved shape in accordance with the shape of the groove 5. The sliding contact state between the parison body 7C and the groove 5 is as shown in FIG. When the mold 4 is further raised and the flange 7b of the parison comes into contact with the mold 4, the rise of the mold 4 is stopped and the deformation of the parison body is completed (FIG. 7). After the deformation is completed, the mold 4 is lowered and the deformed parison 7 is taken out (Fig. 8).

In this method, the parison may be uniaxially stretched or not uniaxially stretched, but a relatively long parison is suitable for deformation of the uniaxially stretched parison in the sense that it can be accurately bent. .

Next, another apparatus for manufacturing a bent deformed parison by applying a pressing force from the lateral direction to the body of a cylindrical parison with a bottom will be described with reference to FIGS.

FIG. 9 is a schematic view showing a device having a rod member 14 which is movable in the lateral direction. In this device, parison 12
While holding the mouth plug 12a of the parison 12 with the holder 13 (a), the rod-shaped member 14 contacts and presses the body 12C of the parison 12 (b). At this time, since the parison 12 is in its softened state, the body portion 12C is easily deformed by the pressing force of the rod-shaped member 14. The region where the rod-shaped member 14 presses the parison 12 can be appropriately selected according to the desired curved state of the parison body 12C.

FIG. 10 is a schematic view showing a blow molding die provided with a rod-shaped member 15 which is movable in the lateral direction. The parison 16 is set at a predetermined position in the mold 17 (a), and the parison is fixed by clamping the mold. Then, the rod-shaped member 15 projects toward the body portion 16C of the parison 16 and presses it (b). This transforms the parison body 16C into a curved shape. After the deformation, the rod member 15 is drawn into the mold 17 (c). With this device, blow molding can be performed as it is after the deformation of the parison.

FIG. 11 shows a parison 19 using a roller 17 placed horizontally.
It is the schematic which shows the apparatus which deform | transforms. In this device, the roller 18 of the parison 19 holding the plug portion 19a is moved relatively (a), the body portion 19C of the parison is brought into contact with the roller 18, and the body portion 19C is bent (b). . At this time, in order to keep the friction low, it is preferable that the roller 18 be rotatable.

Further, in the present invention, holding the spout and the tip of the parison,
It is also possible to bend the parison body by moving it laterally relatively. FIG. 12 shows an example of an apparatus for carrying out this method. In this device, the front end 20d of the parison 20 is gripped by the gripper 21 (a), and the parison 20 and the gripper 21 are relatively moved laterally (b) while holding the spout 20a.

The modified parison produced by the method of the present invention can be used to produce a bottle having a slanted plug portion by blow molding.

FIG. 13 shows an example in which a modified parison 22 that is uniaxially stretched is used to perform free blow molding. Deformation parison to mold 23
With the 22 installed, the tip 22d of the modified parison
Is in contact with substantially the center of the bottom portion 24a of the mold cavity 24.
When heated and pressurized air is blown from a blow mandrel (not shown) with this device, the body 22 of the deformed parison 22 in the softened state is blown.
C is stretched in the lateral direction and molded into the shape of the mold cavity 24. At this time, the central axis 25 of the body 22C of the modified parison 22
Is located approximately in the center of the mold cavity 24, so
The stretch ratio of C becomes almost uniform. As a result, the mouth plug portion 22a
Even a bottle with a slanted surface can be molded to have a substantially uniform wall thickness. Further, since the parison tip portion 22d is located substantially in the center of the bottom portion 24a of the mold cavity 24, the navel of the obtained bottle (the thick portion derived from the parison tip portion) comes to the center of the bottom portion, There is no problem in appearance.

The present invention will be described in more detail with reference to the following specific examples.

Example 1 First, a parison having a cylindrical shape with a bottom and a straight body was made of polyethylene terephthalate. The thickness of this trunk was 3.2 mm. The parison was heated to 95 to 120 ° C. to be in a softened state, and as shown in FIG. 2, it was uniaxially stretched in the longitudinal direction with a stretching rod. The wall thickness of the body of the uniaxially stretched parison thus obtained is 2.1 mm.
Met. This uniaxially stretched parison is shown in Figs.
Using the mold shown in the figure, deformation was performed by the steps shown in FIGS. The mold 4 was kept at about 90 ° C.

The body of the modified parison obtained in this way was smoothly curved, and its cross section maintained a substantially circular shape.

Further, the modified parison was placed in the stretch blow molding die shown in FIG. At this time, the tip of the parison was in contact with almost the center of the bottom of the mold cavity. Free blow molding was performed in this state. The mold temperature at this time was about 50 ° C., and the blow air was 20 ° C. and 28 atm.

The body of the bottle obtained in this way has a substantially uniform thickness (about 0.35 mm) as a whole, and the navel (the thick part originating from the parison tip) is almost at the center of the bottom of the bottle. Was in

〔The invention's effect〕

As described in detail above, by preliminarily deforming the body of the parison into a curved shape, it is possible to easily manufacture a bottle with an inclined plug portion by blow molding without using a complicated device. . Further, due to the bending of the parison body, the thickness of the bottle body after blow molding can be made substantially uniform as a whole.

Also, by using a uniaxially stretched deformed parison,
Since the tip of the parison can be located almost in the center of the bottom of the cavity of the blow mold, the so-called navel can be located in the center of the bottom of the bottle even with free blow, and the wall thickness of the bottle body Uniformity can be ensured. Further, even in a deformed parison that is not uniaxially stretched, the tip portion is curved so as to face the bottom of the cavity, so that it is possible to prevent the thickness of the bottle from being largely non-uniform.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a modified parison manufactured according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a state in which a bottomed cylindrical parison is uniaxially stretched in the longitudinal direction, and FIG. FIG. 4 is a vertical sectional view showing a modified parison manufacturing apparatus according to an embodiment of the present invention, FIG. 4 is a sectional view taken along the line AA of FIG. 3, and FIGS. 5-8 are the apparatus shown in FIG. FIG. 9 is a cross-sectional view showing a series of steps for bending the body of a bottomed cylindrical parison by using FIG. 9, and FIG. 9 is a schematic cross-sectional view showing a modified parison manufacturing apparatus according to another embodiment of the present invention. 10 to 12 are schematic cross-sectional views each showing a modified parison manufacturing apparatus according to still another embodiment, and FIG. 13 is a cross-sectional view showing an example in which the uniaxially stretched modified parison of the present invention is installed in a blow molding die. It is a figure. 1,22 …… Deformed parison 1a …… Deformed parison plug 1b …… Deformed parison flange 1c …… Deformed parison body 2 …… Uniaxially stretched rod 3 …… Uniaxially stretched parison 4 …… Deformed die 5 …… Deformed Sliding contact groove 14,15 …… Pressing rod member 18 …… Pressing roller 21 …… Parison tip gripping tool 23 …… Blow molding die

Claims (7)

(57) [Claims] 1. A plugged portion and a bottomed cylindrical body portion, wherein the central axis of the bottomed cylindrical body portion is curved, and each part of the bottomed cylindrical body portion is extended. A method for producing a blow molding deformed parison having substantially the same magnification, comprising: (a) a mold having a bottomed cylindrical body having a straight central axis and (b) a curved groove. In the softened state of the parison, by sliding the body of the parison into sliding contact with the groove of the mold, lateral force is applied to the body of the parison to bend the body. How to characterize. 2. A plugged portion and a bottomed cylindrical body portion, wherein the central axis of the bottomed cylindrical body portion is curved, and each part of the bottomed cylindrical body portion is extended. In a method for producing a blow-molded deformed parison having substantially the same magnification, (a) a central parison of a cylindrical body having a bottom is formed into a straight line, and (b) a stretching rod is used at a temperature equal to or higher than a softening point. The body of the parison is uniaxially stretched in the longitudinal direction, and (c) a mold having a curved groove is used, and the body of the parison is brought into sliding contact with the groove of the mold in the softened state of the parison. Thus, a lateral force is applied to the body portion of the uniaxially stretched parison to bend the body portion. 3. An apparatus for manufacturing a blow molding deformed parison having a plug portion and a bottomed cylindrical body portion, wherein the center axis of the bottomed cylindrical body portion is curved. A device having a die having a curved groove as a means for laterally pressing the body of the parison, and bending the parison by sliding the body of the parison along the groove. 4. An apparatus for producing a blow molding deformed parison having a plug portion and a cylindrical body with a bottom, wherein the center axis of the cylindrical body with a bottom is curved, wherein the parison is the parison. Having a rod-shaped member movable in the lateral direction as a means for laterally pressing the body part of the parison, and pressing the bar-shaped member against the body part of the parison while holding the plug part of the parison. The device is characterized in that the body is bent. 5. The apparatus according to claim 4, wherein the rod-shaped member is provided in a blow molding die. 6. An apparatus for producing a modified parison for blow molding, comprising: a spigot portion and a bottomed cylindrical body portion, wherein the center axis of the bottomed cylindrical body portion is bent, wherein the parison is formed. A roller as a means for laterally pressing the body of the parison, and by bending the body of the parison against the roller while holding the spigot of the parison, the body is bent. Characterized device. 7. An apparatus for manufacturing a blow molding deformed parison having a plug portion and a bottomed cylindrical body portion, wherein the center axis of the bottomed cylindrical body portion is bent, wherein the parison is provided. Of the parison by moving the means for gripping the bottom relative to the parison while holding the spout of the parison. A device characterized by bending.