JPS606221B2 - Method and device for manufacturing hollow plastic bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing a hollow plastic body, and more particularly, to a thin-walled plastic hollow body with improved transparency and strength.
The present invention also relates to a method and apparatus specifically adapted for producing cup-shaped plastic containers with a large height/diameter ratio.

As a method for forming a thin-walled cup-shaped container with excellent transparency and strength by follow-up stretch forming, for example, a plug-assisted pressure forming method has been proposed and put into practical use.

This involves pressing the peripheral edge of a thermoplastic sheet blank and press-fitting the plug into the die cavity at the orientation temperature of the plastic, and simultaneously supplying compressed air or vacuum suction to perform a combination of drawing and stretching. This is a method for forming cup-shaped containers using a method of molding cup-shaped containers, but since it involves overhanging, when the molding depth becomes large, the inner walls, especially the lower corners, become thinner and more likely to break. It is extremely difficult to obtain plastic hollow body containers with walls or bottom ends. Therefore, it is almost impossible to mold a cup-shaped container with a height greater than its diameter using this method. Therefore, there is a desire for a cup-shaped plastic container with a large height/diameter ratio, thin walls, and excellent transparency, strength, and content storage properties that can provide a larger internal volume for the same amount of space. However, it has not been possible to manufacture such containers using conventional methods. The present invention provides a method and apparatus for manufacturing a container, which has been long awaited as described above.

The main object of the invention is to provide a plastic hollow body in the shape of a metal can (such as a cola can) with a thin wall and a high height/diameter ratio.

Another object of the present invention is to provide a plastic hollow body with improved transparency, strength, gas barrier properties, etc. due to molecular orientation. A particular object of the present invention is to provide a plastic hollow body that can be subjected to retort heat sterilization treatment.

The present inventors introduced the part to become the bottom end into the die cavity while separately pressing the blank part to become the flange part and the blank part to become the bottom end of the hollow body, and by pressing It has been found that the above objects can be achieved by forming the barrel wall from an extended material to form a plastic hollow body.

The present invention will be described below with reference to the drawings.

FIG. 1-a, FIG. 1-b, and FIG. 11-c are explanatory diagrams for showing the principle of the present invention.
As shown in Figure A and Figure 2-B, it has an upper cavity la and a lower cavity lb.

The shoulder lc of the lower cavity lb forms the bottom of the upper cavity la. A circumferential groove ld is formed along the outer periphery of the shoulder portion lc.
is engraved on the flange portion 2a of the plastic hollow body 2 that is molded using this die.
If the skirt portion 2b is not required, the circumferential groove ld may not necessarily be provided. Above the shoulder portion lc of the die, a pad 4 has a hollow portion for pressing the peripheral edge of the blank 3 to form a flange portion 2a.
is provided so as to be slidable along the circumferential surface le of the upper cavity la. Further, an upper plunger 5 is provided so as to be slidable along the inner surface of the pad 4. The outer diameter of the upper plunger 5 corresponds to the body wall 2 of the plastic hollow body 2 to be molded.
It is determined to be substantially equal to the inner diameter of c. 1st
As shown in Figure 1-c, the upper plunger 5 enters the lower cavity 1b and forms the body wall 2c of the plastic hollow 2 between it and the lower cavity 1b. Therefore, the inner diameter of the lower cavity lb is set to be substantially equal to the outer diameter of the plastic hollow body 2 to be molded, and its height is set to be greater than the height of the body wall portion 2c of the plastic hollow body 2. A lower plunger 6 is provided slidably along the inner surface of the lower cavity lb and facing the upper plunger 5.
The lower plunger 6 works together to press the center portion of the blank 3 while descending inside the lower cavity lb to form the body wall portion 2c. In the above apparatus, the plastic hollow body 2 is molded as follows.

First, the blank 3 heated to a predetermined temperature is placed on the shoulder lc.

Blank 3 is made of thermoplastic plastic, and there are no particular restrictions on its material, but it has good stretch formability (molecular tropism).
In order to achieve the object of the present invention, it is particularly preferable that Z be a material with excellent properties. Examples of these oriented thermoplastics include polyolefin resins such as polypropylene, high-density polyethylene, medium-density polyethylene, and low-density polyethylene, linear polyester resins such as polyethylene terephthalate, polycarbonate resins, polyvinyl chloride, nitrile resins, and the like. copolymer,
Blends and laminates or blends of these self-tropic thermoplastics with barrier resins such as ethylene-vinyl alcohol copolymers, polyamides, cellulose resins, polyacrylonitrile, polypinylidene chloride, polyvinyl alcohol, etc. mixture), etc. In particular, a laminate made of polypropylene and ethylene-vinyl alcohol copolymer has excellent gas barrier properties against oxygen, water vapor, etc.
Since the shrinkage rate is extremely small even when heated to 00 qo or higher and it can withstand high temperature sterilization treatment, it is suitable as a hollow body material for storing solid foods, juices, etc. The blank 3 has a substantially equal thickness over its entire area, which thickness is determined based on the total surface area of the product hollow plastic body and its thickness, but typically on sides 1 to 5. be.

The shape is preferably approximately equal to the transverse comb shape of the body wall of the plastic hollow body, that is, if the latter is circular, it is preferably circular, and if the latter is square with rounded corners, it is preferably square, but the two are not necessarily the same. It is not necessary to do so. This is because a hollow body with a square flange and cylindrical walls is also conceivable. Furthermore, since the blank material of the flange portion 2a pressed by the pad 4 also extends outward, the contour of the flange portion coincides with the contour of the circumferential surface le of the upper cavity. Therefore, even if the body wall 2c of the hollow body is cylindrical, if the shape of the blank is square or regular octagonal, it has the advantage of improving the pace of material removal. Nakamura material needs to be kept at a temperature that allows it to be stretched and formed (molecular orientation temperature).
Therefore, the blank 3 is preheated to the above-mentioned temperature and then layered on the shoulder lc, or placed on the shoulder lc and then heated to the above-mentioned temperature. The former is preferable from the viewpoint of work efficiency. In this specification, the stretch-forming temperature (molecular orientation temperature) means that the polymer head of the oriented plastic in the body wall, bottom, and flange of the hollow body obtained by the present invention is higher than that in normal melt molding. It means the temperature at which the material is oriented and, as a result, an improvement in mechanical strength, transparency, etc. is observed. More specifically, it means a temperature at which the two-dimensional orientation coefficient is at least 0.05 as described in, for example, Tokoseki Publication No. 53-21674. Usually, for highly crystalline resins such as polypropylene and polyethylene, it means a temperature that is 3,500 degrees higher than the melting point and a temperature at which molding is possible, and for polyester resins such as polyethylene terephthalate resin, it means a temperature that is above the glass transition temperature and below the crystallization temperature. However, in the case of amorphous polymers such as acrylonitrile resin, it means a temperature that is 35 qo higher than the glass transition temperature or less and is moldable. When the blank is a laminate made of a polyolefin resin and an ethylene-vinyl alcohol copolymer, if x is the vinyl alcohol content of the latter, the temperature is 35°C higher than the melting point of the polyolefin resin or less, and (1. 6 sides 120)℃
It means the temperature above. Furthermore, to explain in detail the relationship between the melting point of an oriented thermoplastic resin and the temperature at which molecular orientation is possible, the melting point of a crystalline or semi-crystalline polymer can be determined using differential thermal analysis, specific heat-temperature curve method, polarized light microscopy, It can be easily determined using methods such as line diffraction and infrared absorption spectroscopy.

On the other hand, crystals of polymeric materials differ from metal crystals in that their structure and size are not uniform and have a distribution, so the melting point must be expressed accurately in a temperature range. However, the most widely used melting point measurement method is differential thermal analysis (
In the case of the differential calorimetry method), the melting point is often expressed as the peak temperature of the melting and absorption curve measured at atmospheric pressure.
Also in this specification, the above-mentioned peak temperature is defined as the melting point.
Therefore, the temperature at which molecular orientation is possible includes a temperature slightly higher than the melting point, as described above. Furthermore, at pressures higher than atmospheric pressure, thermoplastics are compressed and their melting point or glass transition temperature increases, so that melting points measured at pressures higher than atmospheric pressure are higher than melting points measured at atmospheric pressure. It will show the value.

Therefore, when high pressure is applied to the resin during molding as in the present invention, the melting point of the resin increases and molding is performed at a temperature higher than the melting point measured under atmospheric pressure (i.e., the melting point in this specification). It is also presumed that a molecular orientation effect can be obtained. Stretch molding increases the molecular orientation of the plastic, improving its strength, transparency, gas barrier properties, etc. In order to keep the molded product within the above-mentioned stretch-forming temperature during the molding process, the die 1, pad 4, upper plunger 5, and lower plunger 6 may be equipped with heaters, oil heating pipes, water cooling pipes, etc., as necessary. The temperature is adjusted by means to a temperature at which molecular orientation of the resin is possible or a temperature lower than that. The above adjustment temperature is as low as possible within the range where the material can be maintained at a temperature that allows molecular unevenness during a short molding period.
This is preferable because the container 2 can be easily cooled and solidified upon completion of molding. Blank 3 is placed on shoulder lc, No. 1-
As shown in Figure a, the end surface 6a of the lower plunger 6 is located on the same plane as the shoulder surface and comes into contact with the lower surface of the center of the blank 3 to prevent the center portion of the blank from drooping.

Next, the pad 4 starts pressing the green part around the blank,
The material of this portion extends into the circumferential groove ld and at the same time tends to extend toward the center of the blank. Therefore, when the upper plunger 5 and the lower plunger 6 move down the lower cavity lb while pressing the center part of the blank 3 at the same time, the material on the shoulder part lc will be transferred to the upper part, as shown in FIG. 1-b (left side part). The outer peripheral surface of the plunger 5 and the lower cavity l
It extends in the direction of the arrow into the gap 3 formed by the inner peripheral surface of b. At the same time, material also extends from the central portion of the blank pressed by the upper plunger 5 and the lower plunger 6 in the direction of the arrow to form the trunk wall portion 2c. That is, due to the pressing force and the descent of the plunger into the lower cavity lb, the plank 4 gradually becomes thinner, and the body wall portion 2c is formed in the upper gap by a material corresponding to the reduced thickness. Moreover, the wall portion 2c is formed of a material compressed and expanded at a temperature that allows molecular orientation, so that the molecules are oriented. Further, since the flange portion 2a is pressed during molding, wrinkles do not occur, and since the fluidity of the material during molding is not high, burrs are less likely to occur. During this time, it is necessary to balance the rate of replenishment of material into the gap by pressing and the rate of descent of the plunger. That is, if the descending speed is higher than the replenishing speed, there is a possibility that a particularly thin part or a hollow part will be formed in the Tsukioka wall portion 2c, and a satisfactory molded product will not be obtained. On the other hand, if the descending speed is smaller than the replenishment speed, productivity will decrease. The replenishment rate, that is, the extension rate, is determined by the blank material,
It is necessary to determine the size, heating temperature, pressing force, etc. as factors in advance through experiments, and then determine the descending speed of the plunger based on these values. Further, if the replenishment speed, that is, the replenishment amount changes during the molding process, it is necessary to adjust the descending speed accordingly. Although the pressing force varies depending on the type of material, favorable results are usually obtained by setting it to about 400 to 2000 k9', in which case it is also possible to obtain a plunger lowering speed, that is, a forming speed of about 200 k9/sec.

Further, it is also possible to obtain a thin plastic molded body having a thickness of approximately 0.2 mm at the same wall portion of the ear. As above,
As shown in Fig. 1-c, a plastic hollow body 2 with a substantially uniform wall thickness is formed, but if it is desired to increase the strength against internal pressure (for example, for filling carbonated drinks), the bottom part 2d can be removed from the body. It is also possible to make it thicker than the wall portion 2c, or to form a dome shape convex inward.

By the above method, it is possible to obtain a so-called can-shaped plastic hollow body having a height/diameter ratio of 2 to 3.

After the molding is completed, it is preferable to use a cooling mechanism built into the die etc., such as a water pipe or a prine recirculation pipe (approximately 1:30 p.m.).
After quenching the molded body by operating the -pad 4, upper plunger 5 and lower plunger 6,
Pull out the plastic hollow body 2. After filling the hollow body 2 with the contents, the flange portion is made into a sealed container by heat-sealing or wrapping. Next, the drawings showing the main parts of the apparatus used for carrying out one embodiment of the present invention will be explained.

FIG. 3 shows the state at the end of molding.

That is, in the plastic molded body 2, the flange portion 2a is pressed by the pad 4 and the die 1, the bottom portion 2d is pressed by the respective ends of the upper plunger 5 and the lower plunger 6, and the body wall portion 2c is pressed by the upper plunger 5 and the die 1. It is formed in the gap between There is a cooling pipe 7 inside the die 1.
is built in, and a heater coil 8 surrounds its outer periphery. A cartridge heater 9 is provided inside the upper plunger 5 and the lower plunger 6. Tatissu has a fixed base of one river. The lower plunger 6 passes through a through hole 10a in the base 10 and can be moved up and down by a hydraulic cylinder (not shown) (18 in FIG. 4). The upper plunger 5 is attached to the Z plunger plate 11, and is movable up and down by sliding through the center hole of the pad 4 and the pad plate 12 to which the pad 4 is fixed. The plunger plate 11 is fixed to a Z ram 13 that is moved up and down by a hydraulic cylinder (17 in FIG. 4), not shown, and its end is guided by a guide shaft 14 fixed to the base 10. On the other hand, a coil spring 15 is provided between the upper surface of the pad plate 12 and the lower flange surface 5a of the upper plunger 5.
applies a pressing force to the flange portion 2a. Therefore, even when the upper plunger 5 is pulled out from the hollow body after the molding is completed, the flange portion 2a is pressed by the pad 4.
Extraction is performed smoothly. Pad plate 12
The end portion of the base plate 101 is guided by a guide shaft 16 fixed to the base plate 101. FIG. 4 shows a hydraulic circuit for driving the plunger of the above device. 17 and 18 are hydraulic cylinders for driving the upper plunger 5 and lower plunger 6, respectively.

The circuit consisting of the solenoid valve 19 and the flow regulator 20 is for independently driving the upper plunger 5, and the circuit consisting of the solenoid valve 21 and the flow regulator 22
The circuit consisting of is for independently driving the lower plunger 6, and is for independently raising the upper plunger 5 after the molding is completed, and for independently driving the pad 4.
After the plastic hollow body 2 leaves the flange portion 2a, the lower plunger 6 rises to extract the plastic hollow body 2 from the die 1, followed by the lowering of the upper plunger 5 and accurate positioning of both plungers before the next molding. The operation is performed by operating a limit switch (not shown). A circuit consisting of solenoid valves 23, 24, pressure reducing valve 25, and flow control valves 26, 27 is a circuit for driving upper plunger 5 and lower plunger 6 during molding. High-pressure oil from the hydraulic source 28 passes through the solenoid valve 23 and enters the piston side of the cylinder 17, and when the upper plunger 5 is pushed in the direction of the arrow, the oil comes out from the plunger side, passes through the solenoid valve 23, and then some of the oil enters the piston side of the cylinder 17. flow control. control valve 26
Most of the remaining oil passes through the pressure reducing valve 25 and the solenoid valve 24 and enters the plunger side of the cylinder 18. Therefore, since the amount of oil flowing into the cylinder 18 is smaller than the amount of oil flowing into the cylinder 17, the movement of the lower plunger 6 in the direction of the arrow is delayed by that much than the upper plunger 5. The thickness of the bottom portion 2d is reduced by a distance corresponding to this delay. The flow control valve 27 thus determines the speed of transition of the lower plunge 6.
By controlling the flow control valve 26, which is related to the amount of material extending from the bottom portion 2d, in accordance with the amount of material extending from the pressing portion, the body wall portion 2c has a uniform thickness.
It is possible to mold a plastic hollow body 2 having . The present invention is not limited to the above examples, but for example, as shown in FIG. 5, the area of the stock 3' of molecularly oriented plastics is
It may be smaller than the area of a. In this case, if the lower surfaces of the upper plunger 5 and the pad 4 are aligned on the same plane and both are lowered at the same time to compress the stock 3' which is in a heat-softened state, at a certain compression ratio, as shown in FIG. similar blank 3
(However, the hem portion 2b is formed) is obtained. The same panraku is molded in the same manner as described above. Further, as shown in FIG. 7, the stock 3'' may be a molecularly oriented plastics powder or a blend of a molecularly oriented plastics powder and another resin powder. In this case, the stock 3'' is After heating the plastic in the cavity la to a temperature above the melting point of the plastic (in the case of a blend, above the higher melting point of the melting points of each powder), the upper plunger 5 is heated in the same manner as in the case of FIG. The blank 3 as shown in FIG. 6 can be obtained by simultaneously lowering the pad 4 and the pad 4 to an appropriate height and compression molding the powder stock 3''.The blank 3 shown in FIG. In the case of a plate-shaped blank formed as described above from a blend of alcohol copolymer powder,
The molecular orientation temperature is 35 oo higher than the melting point of the polyolefin resin, and (1.6 x 40)°C.
The temperature will be higher than that.

The lower limit temperature in this case is the lower limit temperature (
1.6 umbrellas 120). The reason why it is higher than 0 is thought to be as follows.

In the latter case, the polyolefin resin layer and the ethylene-vinyl alcohol copolymer layer are usually bonded via an adhesive layer as shown in Example 1, but in the former case, the polyolefin resin layer and the ethylene-vinyl alcohol copolymer layer are bonded via such an adhesive layer. Because the molding temperature is lower than the melting point of the ethylene-vinyl alcohol copolymer ((1.6°C x 68°C)), the molding die is lower than the melting point of the ethylene-vinyl alcohol copolymer. Separation occurs at the interface of copolymer particles ~ gas barrier
This is because transparency and transparency will be lost. In the present invention, the plastic hollow body is formed by stretch molding rather than melt molding, so the arm wall can be formed as thin as about 0.2 ribs, and the molded body has molecular orientation, so it is strong despite its thin wall. By appropriately selecting materials, it is possible to obtain a molded article that has excellent properties, good transparency, and high gas barrier properties.

Furthermore, since stretch molding is not involved, it has the advantage that a molded product having a large height/diameter ratio, that is, a juice can shape, can be easily obtained. Therefore, if the material is appropriately selected, the plastic molded article of the present invention can be used in the fields of conventional heat-sterilized food cans, juice cans, etc., or carbonated beverage cans, beer cans, etc., which have high internal pressure. It has the advantage that the contents can be seen through compared to conventional metal cans. Furthermore, the present invention is capable of compressing the container flange portion and the bottom end portion of a blank made of molecularly oriented plastic separately at a temperature that allows molecular orientation, while dicing the bottom end portion into a die. By introducing the material into the cavity, the material extended by compression forms the body wall part and forms a cup-shaped container with a flange.The material extended by compression is transparent because its molecules are oriented. It is possible to obtain a body part with excellent strength and gas barrier properties even if it is thin, and since the flange part is compressed at a temperature near or below the melting point, burrs and wrinkles do not occur. It has the advantage of not being Furthermore, in the case of this type of molding method, the molding speed is regulated by the extrusion speed of the material that is extruded into the gap between the cavity and the upper plunger to form the body wall, but in the case of the present invention, Since the material is extruded from the part that should become the flange, it has the advantage of being able to achieve a higher molding speed.

The thickness of the flange portion of the container is determined by the pressure of the pad described later or the positional relationship between the pad and the shoulder of the cavity, the thickness of the flange portion is determined by the gap between the cavity and the upper plunger, and the thickness of the bottom portion is determined by the positional relationship between the upper plunger and the lower plunger.

In other words, since the thickness of the container is forcibly determined by the geometric dimensions of each part of the device, the thickness distribution is much better than with conventional cup-shaped container forming methods, and the desired thickness can be easily controlled. It has the advantage of Examples will be described below.

Example 1 Density at 20 qo was 0.91 ta', differential thermal analysis (
The outermost layer is isotactic polypropylene (A) with a melting point of 16,000 by the DTA method, with an ethylene content of 45 mol% and a vinyl alcohol content of 55 mol%.
, the melting point according to the PTA method is 15400, the temperature is 370,
Oxygen permeability coefficient (Po2) at 0% relative humidity is 2.3×1
The middle layer is made of ethylene-vinyl alcohol copolymer (B) of 0-13cc, skin/sec, Hg suppression, and the density is 0.9.
The maleic anhydride-modified polypropylene (C) with a melting point of 159q0 was used as the adhesive layer between the outermost layer and the middle layer. An extruder for the outermost layer with a built-in screw, a full-flight type with a diameter of 4 holes and an effective length of 880 mm.An extruder for the adhesive layer with a built-in screw and a full-flight type with a diameter of 4 mm and an effective length of 880 mm. Using a combination of an extruder for the intermediate layer with a built-in die screw, a multi-layer 5-layer feed block adapter, a single-manield T-die, and a sheet take-up machine, we can produce 50 mills in operation and 3 types with a thickness of 3.0. A 5-layer sheet was molded.

The number of rotations of each extruder was adjusted so that the composition ratio of the outermost layer to the adhesive layer to the intermediate layer of the obtained sheet was as close as possible to 100:2:4 in terms of thickness ratio. Next, the sheet was cut out onto a disc (blank) with a diameter of 6W and heated to exactly 159°C using an infrared heater.

This heating blank is placed in the upper cavity la shown in Fig. 2-a, and is pressed with a pressure of about 1000 kg' by the pad 4 shown in Fig. 3, and at the same time, the upper plunger 5 and lower plunger 6 shown in Fig. 3 are inserted into the lower cavity. The kites were lowered by 10 mn at descending speeds of approximately 4 mn/sec and 5 mn/sec, respectively. At this time, the die 1 in FIG. 3 was preheated to about 70 oo by a heater coil 8, and the upper plunger 5 and lower plunger 6 were heated to about 70 oo by a cartridge heater inside the plunger. After forming the cup, the surface temperature of the cup is approximately 8000.
However, since the surfaces of the upper plunger, lower plunger, and lower cavity were coated with silicone-based lubricant in advance, the cup could be easily removed from the molding machine without the need for cooling. In addition, the dimensional stability of the molded cup extracted over time after molding was also sufficient. The resulting cylindrical cup has a flange outer diameter of 6 and a thickness of 0.
．． No burrs or wrinkles were observed on the third side. 8. The outer diameter of the same part was 5 mm, the height was 101 mm, and the thickness of the trunk wall and bottom end was 0.335 mm and 0.03 mm.

As a comparative example, an attempt was made to mold a cup having the same shape at the same molding temperature using the same sheet as above using the plug-assisted pressure forming method.

As a result of various conditions in which the lowering amount of the plug and the molding pressure were varied, the bottom end was not sufficiently stretched, which is a drawback of the plug-assisted pressure forming method. The connection part is extremely thin (0.05 to 0.11
r) An impractical cup was obtained. Example 2 In exactly the same manner as in Example 1, a blank was molded from a sheet of the same material composition and thickness, and then a cup of the same shape was molded.

In this example, the heating temperature of the blank before cup forming was 13030°C, 150°C, 159°C, 1690°C, 19°C.
Six types of cups were molded with settings of pi ○ and 20 pi 0.
The difference from Example 1 is that in addition to the above-mentioned molding temperature, about 10 qo of cooling water was poured into the cooling pipe 7 in FIG. 3 after cup molding was completed, and after the molded cup was sufficiently cooled, it was taken out from the molding machine.
Transparency of the arm wall and bottom end of these six types of cups (
degree), retort resistance, orientation coefficient (1, m, n) determined by fluorescence method of the same wall part and bottom end part of the ear, Japanese Patent Publication No. 52-112
Oxygen permeability (Qo) according to the method described in Publication No. 63
2) was measured. These results are shown in Table 1. As is clear from this example, the method and apparatus of the present invention make it possible to form containers with a large container height/container diameter ratio, which was impossible with stretch forming based on the conventional plug-assisted pressure forming method. Moreover, the influence of molding temperature on the physical properties of the molded container, such as its transparency, retort resistance, and gas barrier properties, is clear. Ship's rumors, dormitory fee, cod, kigurashi, crane, ayu, four N, total hawk, age, sea, four rounds, thunder, cloud, crane, K' guest, armor, rudder, dust, small boat, cod x fishing, Q.

He S Revealing Reed Mother 'Do Q Chicken' role - A carp Y mirror lees armor increase axis Ren turtle 轡胏菏 きりき - Beyama parallel period'Keran's house bonito skin Mizuya Mae Yamajin ``Mother Ayu Pen'' Mourning) Q Minoru weight, crucian carp back, rumor ``\A, group bonito fishing spiritually, weight, cloud groove profit, and S continue to fake zero return, normal turtle edge, bonito, carp, 13~mu≦ The sea lion's cloud, the battle-lips, the reef on the shore, day 9 to 1, Yamasekiguchi R, kasu size g, the holy '+ rule pot, the poisonous snake, Naniwa, the bedroom, the coarse bone, the snow, the sea bream, the cloud deer preside over [N's size** * * Example 3 Phenol/tetrachloroethane weight ratio is 50/50
A polyethylene terephthalate beret with a logarithmic viscosity of 0.11 m/m at 303C in a mixed solvent of A disk-shaped plank having a thickness of 3 ribs and a diameter of 60 ribs was molded by a known injection molding method.

When the density of this molded blank was measured using a density gradient tube using a mixture of n-heptane/carbon tetrachloride at 20°C, the density ranged from 1.335 to 1.338 m/m at any point on the blank. It was there. Next, the sheet was heated with an infrared heater on both sides of the sheet to a temperature of 100 mm with a spacing of approximately 35 mm, and then a cut Z cup having the same shape was molded using the same molding machine and under the same molding conditions as in Example 1. However, the die, upper plunger, and lower plunger were preheated to about 45 qo. The thickness of the body wall and bottom end of the cup obtained was 0.03±0.
．． 03 side and a cup with an extremely small wall thickness distribution was obtained. The thickness of the flange portion was also on the 0.03-0.03 side, and no burrs or wrinkles were observed in the flange portion.
Also, the density of the Tsukioka wall and bottom end is in the range of 1.348 to 1.364 m/m, especially 1.348 to 1.364 m/m.
．． The area in the range of 348 to 1.355 mm was observed only in a very small area where the flange and the body wall were connected. This can be said, for example, to a stretch-molded polyethylene terephthalate container which has extremely small post-molding shrinkage, as described in Japanese Patent Application No. 53-35473. On the other hand, as a comparative example, the same disc-shaped blank was similarly heated to exactly 100 oo, and then a cup having the same shape was attempted to be formed by a known plug-assisted pressure forming method.

As in Example 1, in the case of plug-assisted pressure forming, it is difficult to reduce the thickness of the bottom end to the desired thickness.
The connection between the wall portion and the body wall portion and the bottom end portion became extremely thin, and a satisfactory cup could not be obtained. Example 4 Using the isotactic polypropylene (A) used in Example 1 as the outermost layer and the maleic anhydride-modified polypropylene (C) used in Example 1 as the adhesive, a barrier layer was formed as the intermediate layer. Ethylene content 30 as a layer
mol%, vinyl alcohol content 70 mol%, the above DT
Melting point by method A is 183℃, oxygen permeability coefficient (temperature 370℃)
, relative humidity 0%) is 7.0×10-14cc. suppression/land/
Using the ethylene-vinyl alcohol copolymer (8) of Sec. and the same sheet molding machine as in Example 1, a three-type, five-layer sheet having the same thickness and the same composition ratio as in Example 1 was molded.

Next, this sheet was molded into a cup having the same shape as in Example 1 using the same cup molding machine as in Example 1. In this example, the heating temperature of the blank before cup forming was set to 130°C.
qo, 135℃, 140℃, 160q0, 195℃, 2
Six types of cups were molded at a temperature of 00°C.

Transparency of the body wall and bottom end of these six types of cups (
Haze) and oxygen permeability were measured as described in Example 2. These results are shown in Table 2. Notes to Table 2: (1) Same measurement method as Example 2. As is clear from Table 2, the melting point used in this example was 1.
A suitable molding temperature for a multilayer cup of 60 qo polypropylene and ethylene-vinyl alcohol copolymer with a melting point of 183 °C (vinyl alcohol content 70 mol%) is 135
It is clear that it is between 195 qo and 195 qo.

[Brief explanation of the drawing]

Figures 11a, 11b, and 11c are explanatory diagrams of the principle of the present invention, and Figure 2-a is a vertical cross-sectional view of the die in Figure 1.
-B is a plan view thereof, FIG. 3 is an embodiment of the device of the present invention, FIG. 4 is a hydraulic circuit for driving the device of FIG. 3, and FIG. 5 is a method of forming a blank of the present invention. FIG. 6 is an explanatory longitudinal sectional view of one example of the blank formed by the method shown in FIG. 5, and FIG. An explanatory longitudinal cross-sectional view is shown. 1...Dice, la...Upper cavity (first cavity), lb...Lower cavity (second cavity), lc...Shoulder, 2 ……
Plastic hollow body, 2a...flange part, 2c.
...8 Same wall part, 2d...Bottom end, 3...
... Blank, 4... Pad, 5... Upper plunger (first plunger), 6... Lower plunger (second plunger). Many diagrams - o Figures - Figures 2 - 2' Figures 2 Figures 9 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A method for manufacturing a plastic hollow body consisting of a flange portion, a body wall portion and a bottom end portion from a thermoplastic plastic blank having a substantially uniform thickness, the inner diameter and height of which are respectively a first cavity whose inner diameter is greater than or equal to the inner diameter and thickness of the blank; and a first cavity whose inner diameter is substantially equal to the outer diameter of the body wall and whose height is greater than or equal to the height of the body wall; The second cavity is connected to the shoulder via the shoulder.
The part of the blank that is to become the flange is placed on the shoulder of the die having a second cavity, the part that is to become the flange is pressed with a pad, and the part of the blank located in the second cavity is pressed. while pressing the portion between a first plunger having an outer diameter substantially equal to the inner diameter of the barrel wall portion and a second plunger having an outer diameter substantially equal to the inner diameter of the second cavity. simultaneously introducing a first plunger and a second plunger into the second cavity;
Thereby, the thickness of the part to become the flange is reduced to the thickness of the flange of the plastic hollow body, and the thickness of the blank part located above the second cavity is reduced to the bottom end of the plastic hollow body. The thickness of the thermoplastic plastic is reduced to a thickness of 100 mm, and at the same time a body wall portion is formed in the gap between the second cavity and the first plunger, and the temperature of the thermoplastic plastic at the time of the above pressing is the molecular orientation temperature of the plastic. A method for producing a hollow plastic body characterized by: 2. The method for producing a hollow plastic body according to claim 1, wherein the thermoplastic blank is made of an oriented polyolefin resin. 3. The method for producing a hollow plastic body according to claim 1, wherein the thermoplastic blank is a laminate mainly composed of an oriented polyolefin resin and an ethylene-vinyl alcohol copolymer. 4. The method for producing a hollow plastic body according to claim 1, wherein the thermoplastic blank is made of an oriented polyester resin. 5 The shape of the blank is a square or a regular polygon,
2. The method of manufacturing a hollow plastic body according to claim 1, wherein the body wall portion is cylindrical. 6. An apparatus for manufacturing a plastic hollow body consisting of a flange part, a body wall part and a bottom end part from a thermoplastic blank of substantially uniform thickness, the apparatus comprising:
a first cavity whose inner diameter is equal to the outer diameter of the flange portion and whose height is greater than or equal to the thickness of the blank; a die having a second cavity that is greater than or equal to the height of the body wall portion and that is connected to the first cavity via a shoulder portion;
a pad having a hollow portion for pressing a portion of the blank on the shoulder to form the flange, having an outer diameter substantially equal to the inner diameter of the body wall and sliding through the hollow portion of the pad; a first plunger insertable into the second cavity, the first plunger having an outer diameter substantially equal to the inner diameter of the second cavity and sliding within the second cavity opposite the first plunger; a movable second plunger; and a movable second plunger that compresses the first plunger and the second plunger while compressing and reducing the thickness of the portion of the blank that lies between opposing surfaces of the first plunger and the second plunger. and a driving means for simultaneously introducing the plastic hollow body into the second cavity.