JP2014008659A - Vessel made of foamed resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vessel including sufficient strength and moderate heat-insulating property which are required as a vessel, and having excellently improved decorativeness of especially the side wall outer surface which mostly attracts people's attention when being used, while aiming at weight reduction and manufacturing cost reduction.SOLUTION: A vessel molding 1 having an upper opening is foam-molded by fusing by heat in a die, raw material particles made of a thermoplastic resin having a low foaming ratio, and molding marks Ma, Mb formed on the surface of the vessel molding 1 by a communication hole communicated with a cavity of the die are disposed in a distribution in which the ratio of formation on each other surface is higher than that on the outer surface 1f of a side wall 1B.

Description

  The present invention relates to an improvement of a container that requires decorative properties such as a heavy box and folding.

  As a container requiring decoration, for example, a container used for selling New Year dishes, generally a wooden container and a synthetic resin molded by injection molding (injection molding) using ABC resin or AS resin. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 11-011483

  In the case of a wooden container, since curving and bending are difficult, there is a problem in that the modeling of the container is limited, and a lot of labor is required for assembly, resulting in a high manufacturing cost.

  In addition, in the case of synthetic resin containers manufactured by injection molding, containers of various forms including curves can be produced in large quantities, but since the amount of resin used per container is large, the weight of the container is increased. There is a problem that causes an increase in manufacturing costs.

  The present invention has been made in view of the above-described actual situation, and its main problems are to provide sufficient strength and appropriate heat insulation required as a container, and to reduce the weight and manufacturing cost. In particular, the present invention is to provide a foamed resin container that can improve the decorativeness on the outer surface of the side wall that is most easily noticeable during use.

  According to a first characteristic configuration of the present invention, raw material particles made of a thermoplastic resin having a low expansion ratio are heat-fused in a mold to form a container molded body having an upper opening, and communicate with the cavity of the mold. The molding marks formed on the surface of the container molded body by the communicating holes are arranged in such a distribution that the proportion formed on each other surface is larger than the outer surface of the side wall.

  According to the above configuration, the raw material particles made of the thermoplastic resin with a low expansion ratio filled in the cavity of the mold are heat-fused, and the container molded body with the upper opening is manufactured by foam molding. It is possible to mass-produce various types of container molded products that contain, and to suppress the appearance of foamed particle patterns (turtle shell patterns) of raw material particles on the surface of the container molded products. Can be obtained.

  Furthermore, since the molding traces of the communication holes formed on the surface of the container molded body are arranged in a distribution that often appears on other surfaces other than the outer surface of the side wall, it is most noticeable when used as a container with an upper opening. Decrease in decorativeness due to appearance of molding marks on the outer surface of the side wall can be suppressed.

  Therefore, by forming a foam-molded container molded body using raw material particles in a low-foamed state, it has sufficient strength and moderate heat insulation required as a container, and it is also possible to reduce the weight and the manufacturing cost. Although it is intended, the decorativeness on the outer surface of the side wall that is most noticeable at the time of use can be improved satisfactorily by suppressing the foamed particle pattern (tortoise pattern) and the molding marks on the outer surface of the side wall.

  The 2nd characteristic structure by this invention exists in the point by which the pattern by an unevenness | corrugation is formed in the outer surface of the side wall of the said container molded object.

  According to the above configuration, the molding marks formed on the outer surface of the side wall are mixed into the uneven pattern formed on the outer surface of the side wall of the container molded body, which makes it difficult to distinguish. It can be remarkably improved.

  According to a third characteristic configuration of the present invention, one of the communication holes is a vent hole, the molding mark of the vent hole formed on the outer surface of the side wall of the container molded body has a needle hole shape, and other than the outer surface of the side wall. The molding marks formed on the surface are each formed in a slit shape having a larger area than the needle hole-shaped molding marks.

  According to the above configuration, the formation mark formed on the surface of the container molded body other than the outer surface of the side wall is formed into a slit shape with a large area, and supply and discharge of steam into the mold cavity during foam molding of the container molded body By making the molding mark of the vent hole formed on the outer surface of the side wall into a needle hole shape while making sure the smoothness etc., the molding mark formed on the outer surface of the side wall becomes more difficult to distinguish. The decorativeness can be improved.

The perspective view of the foam resin container for heavy boxes which shows 1st Embodiment of this invention Bottom view of foamed plastic container Cross section when combined as a heavy box Cross section of molding equipment for foamed resin containers Expanded sectional view of the core vent of the mold Enlarged sectional view of the core vent hole at the side wall molding part of the mold

[First Embodiment]
FIG. 1 to FIG. 3 show a container made of foamed resin for heavy boxes, and raw material particles made of polystyrene synthetic resin having a foaming ratio of 3 times pre-foamed as raw material particles made of thermoplastic resin having a low foaming ratio ( The raw material beads) are filled into the cavity of the mold for forming the container, and heat-sealed with steam to form the container formed body 1 with the upper opening by foaming, and on the outer surface 1f of the side wall 1B of the container formed body 1 A pattern 3 having irregularities such as a wood grain pattern is formed.

  The foamed resin lid, which is detachably attached to the opening of the molded container 1 of the foamed resin container, is also prefoamed foam as raw material particles made of thermoplastic resin having a low foaming ratio, as described above. Raw material particles (raw material beads) made of polystyrene synthetic resin having a magnification of 3 times are filled in a cavity of a lid molding die and heat-sealed with steam to form a lid molded body 2 by foam molding.

  In this embodiment, the expansion ratio of the raw material particles for foam-molding the container molded body 1 and the lid molded body 2 is set to 3 times. The expansion ratio of the raw material particles is 1.5 times to 4.5 times. It may be in the range, preferably in the range of 2 to 4 times.

  And by making the container molded body 1 and the lid molded body 2 of foam molding using such low-foamed raw material particles, it has sufficient strength and appropriate heat insulation required for the container and the lid, In addition, it is possible to obtain a foamed resin container and a foamed resin lid that are highly decorative and that do not show a foamed particle pattern (turtle shell pattern) on the surface, while reducing the weight and manufacturing cost.

  In addition, the unevenness pattern 3 formed on the outer surface 1f of the side wall 1B of the container molded body 1 is difficult to distinguish because the molding mark Ma formed on the outer surface 1f of the side wall 1B is mixed and becomes difficult to distinguish. The decorativeness at 1f can be remarkably improved.

  The container molded body 1 includes a bottom wall 1A having a square shape in plan view and four side walls 1B integrally formed continuously on four sides of the bottom wall 1A. A rectangular annular lower fitting protrusion 1d formed on the lower surface of the side wall 1B of another container molded body 1 stacked from above, or a rectangular annular fitting formed on the periphery of the lower surface 2a of the lid molded body 2 A rectangular annular upper fitting recess 1a is formed that is open to the outside and upward, which can be selectively fitted with the protrusion 2b.

  A rectangular annular upper fitting projection 1b positioned along the inner side of the upper fitting recess 1a is fitted to the lower fitting projection 1d of the other molded container 1 fitted or mounted, or the fitting of the lid molded body 2. It is configured to prevent relative disengagement movement in the horizontal direction by contact with the mating protrusion 2b.

  Further, the inner surface of the lower end portion of the side wall 1B projecting downward from the outer surface 1e of the bottom wall 1A can be fitted with the upper fitting protrusion 1b of another container molded body 1 arranged in the lower layer in the stacking direction. A rectangular annular lower fitting recess 1c that opens toward the lower side and the lower side is formed, and a lower fitting projection 1d is formed along the outer side thereof.

  Molding traces Ma to Md are formed on the surface of the container molded body 1 by various communication holes communicating with the cavity 8 of the mold, and these molding traces Ma to Md are formed on each side wall of the container molded body A. The other surfaces than the outer surface 1f of 1B, that is, the inner surface 1g of the side wall 1B, the inner surface 1h of the bottom wall 1A, and the outer surface 1e are arranged in a distribution that increases.

  As the communication hole communicating with the cavity 8 of the mold, supply and discharge of steam for heating the pre-foamed raw material particles filled in the cavity 8 to the fusion temperature, or when filling the raw material particles, Vents 17 used for discharging compressed air flowing into the chamber, a raw material filling port 23 of the raw material filling device 20 for filling the pre-foamed raw material particles in the cavity 8, and a container molded body in the foam molded cavity 8 There is a mounting hole 46 in which the ejector pin 41 of the ejector 40 that releases the mold 1 after being cooled is removably mounted.

Further, as shown in the lower part of FIG. 5, the vent hole 17 has, for example, a bottomed surface in which a plurality of slits 18 a having a width of about 0.2 to 0.8 mm are formed through the bottom surface facing the cavity 8. For example, a first vent hole (core vent attachment hole) 17A for discharging steam / air of a mold fitted with a cylindrical core vent 18 and a bottom face facing the cavity 8 as shown in FIG. , A bottomed cylindrical core vent 18 having a plurality of slits 18a each having a width of about 0.2 to 0.8 mm is fitted, and the steam supply pipe 31 of the steam supply means 30 is attached to the core vent 18. As shown in FIG. 6, the connected second vent hole 17B for supplying steam and a through hole (core bend hole) having a diameter of about 0.2 to 0.8 mm are formed directly in the mold. 3 with the third vent hole 17C for discharging steam / air Type is present.
The slit of about 0.2 to 0.8 mm of the core vent 18 may be changed to a round hole having a diameter of about 0.2 to 0.8 mm.

  Then, a molding surface 5a of a mold (cavity mold 5) for molding the outer surface 1f of the side wall 1B of the container molded body 1 and a mold (core mold 6) for molding the upper surface 1i of the sidewall 1B of the container molded body 1 are used. By arranging the third ventilation hole 17C shown in FIG. 6 on the molding surface 6a, the molding mark Ma of the third ventilation hole 17C formed on the outer surface 1f of the side wall 1B of the container molded body 1 appears as a needle hole shape. In addition, since the total area of the molding trace Ma of the third vent hole 17C appearing on the outer surface 1f of each side wall 1B is significantly reduced than the total area of the molding trace Mb formed on each other surface, The molding mark Ma formed on the outer surface 1f of 1B becomes inconspicuous, and the decorativeness on the outer surface 1f of the side wall 1B can be remarkably improved.

  Pattern forming unevenness for forming the uneven pattern 3 on the outer surface 1f of the side wall 1B of the container molded body 1 is formed on the molding surface 5a of the mold (cavity mold 5) for molding the outer surface 1f of the side wall 1B of the container molded body 1. The part is formed.

  Further, on the molding surface of the mold for molding the inner surface 1g of the side wall 1B of the container molded body 1 and the inner surface 1h of the bottom wall 1A, the first vent hole 17A for steam / air discharge shown in FIG. By arranging the second vent hole 17B, a number of molding marks Mb of the first vent hole 17A and the second vent hole 17B formed on the inner surface 1g of the side wall 1B and the inner surface 1h of the bottom wall 1A of the container molded body 1 are obtained. Each appears in a circular shape corresponding to the outer diameter of the core vent 18 as a multi-stage slit shape having a larger area than the molding mark Ma of the third vent hole 17C appearing as a needle hole shape.

  A large number of slit-shaped moldings Mb appearing on the inner surface 1g of the side wall 1B and the inner surface 1h of the bottom wall 1A of the container molded body 1 are hidden by New Year dishes stored therein, and are therefore less likely to be noticed in use. Rather, by providing a large number of slit-shaped molding marks Mb on the inner surface 1g of the side wall 1B and the inner surface 1h of the bottom wall 1A, supply of steam into the mold cavity 8 during foam molding of the container molded body 1 And discharging can be performed smoothly and reliably.

  Furthermore, the molding surface of the mold for molding the outer surface 1e of the bottom wall 1A of the container molded body 1 includes a first vent hole 17A for discharging steam / air and a second vent hole 17B for supplying steam shown in FIG. By arranging the raw material filling port 23 of the raw material filling device 20 and the mounting hole 46 of the ejector pin 41, the bottom wall 1A of the container molded body 1 has a large number of first and second ventilation holes 17A and 17B. In the circular region corresponding to the outer diameter of the core vent 18, each of the molding marks Mb appears as a plurality of slit shapes having a larger area than the molding mark Ma of the third vent hole 17 </ b> C appearing as a needle hole shape. The molding mark Mc of the filling port 23 and the molding mark Md of the mounting hole 46 of the ejector pin 41 appear as a circular shape larger than the outer diameter of the core vent 18.

  Further, a third ventilation hole formed in the upper surface 2c of the lid molded body 2 is provided on the molding surface of the mold for molding the upper surface 2c of the lid molded body 2 by disposing the third ventilation hole 17C shown in FIG. The molding trace Ma of 17C appears as a needle hole shape, and the total area of the molding trace of the third vent hole 17C that appears on the upper surface 2c is much larger than the total area of the molding trace formed on the lower surface 2a of the lid molded body 2. By reducing the thickness of the lid molded body 2, the molding marks formed on the upper surface 2 c of the lid molded body 2 become inconspicuous, and the decorativeness on the upper surface 2 c of the lid molded body 2 can be remarkably improved.

  On the molding surface of the mold for molding the lower surface 2a of the lid molded body 2, the first vent hole 17A for steam / air discharge and the second vent hole 17B for steam supply shown in FIG. By disposing the raw material filling port 23 and the mounting hole 46 of the ejector pin 41, each of the numerous molding marks Mb of the first ventilation hole 17A and the second ventilation hole 17B is formed on the lower surface 2a of the lid molded body 2. In the circular region corresponding to the outer diameter of the core vent 18, it appears as a multi-stage slit shape having a larger area than the molding mark of the third vent hole 17 A appearing as a needle hole shape, and the molding mark Mc of the raw material filling port 23 and A molding mark Md of the mounting hole 46 of the ejector pin 41 appears as a circular shape larger than the outer diameter of the core vent 18.

Next, the foaming resin container molding apparatus shown in FIGS. 4 to 6 will be described.
This molding apparatus includes a cavity mold 5 and a core mold 6 as a pair of molds that can be freely opened and closed, a raw material tank 7 for storing pre-foamed raw material particles, and raw material particles in the raw material tank 7. Is charged in the cavity 8 formed between the molding surface 5a of the cavity mold 5 and the molding surface 6a of the core mold 6, and the raw material particles filled in the cavity 8 are heated to the fusion temperature. Steam supply means 30 for supplying steam for the purpose, and an ejector 40 for releasing the molded container 1 in the foamed cavity 8 after cooling are provided as main components.

  The cavity mold 5 is attached to the fixed frame 10 in a state where the first chamber 9 is formed between the cavity mold 5 and the back surface thereof, and the core mold 6 is also formed in the second chamber 11 between the back surface thereof. And is attached to the movable frame 12.

  The first discharge port portion 10b formed in the bottom portion 10a of the fixed frame 10 and the second discharge port portion 12b formed in the bottom portion 12a of the movable frame 12 have a cavity through the first and second chambers 9 and 11. 8 are connected to vacuum pipes 14A and 14B of a vacuum pump 13 for depressurizing or evacuating the inside, and drain water generated in the first and second chambers 11 is collected in the middle of the vacuum pipes 14A and 14B. Drain pipes 15A and 15B are connected.

  When filling the cavity 8 with the raw material particles, the vacuum 8 is evacuated or depressurized by the vacuum pump 13 so that a predetermined amount of low-foam and heavy raw material particles can be rapidly and efficiently put into the cavity 8 with a pressure difference. Can be filled.

  The raw material filler 20 is composed of a filling pipe part 21 and a plunger part 22 through which pre-foamed raw material particles pass, and the tip of the filling pipe part 21 passes through the first chamber 9 and is formed in the cavity mold 5. It is connected to the filling attachment port 5b.

  The filling pipe portion 21 is formed with a filling air supply passage 24 for ejecting compressed air for filling the raw material particles toward the raw material filling port 23 on the distal end side thereof, and a base end portion of the filling air supply passage 24. A charging air supply pipe 25 is connected to the.

  The raw material inlet portion 27 of the filling pipe portion 21 and the raw material tank 7 are connected by a raw material supply hose 28, and the plunger portion 22 has a forward position for sealing the raw material filling port 23 of the filling pipe portion 21 and a raw material inlet portion. A plunger rod 26 having a piston 26 </ b> A capable of reciprocating over a retracted position that opens a passage from 27 to the raw material filling port 23 is provided.

When the cavity 8 is filled with the raw material particles by the compressed air injected from the filling air supply path 24, the plunger rod 26 is moved to the forward position, and the raw material filling port 23 is closed by the piston 26A.
Even in this state, if the compressed air continues to be injected from the filled air supply path 24, the compressed air makes a U-turn and flows backward in the filled pipe portion 21, and the raw material particles remaining in the filled pipe portion 21 flow into the airflow. As a result, blowback is performed in which the raw material particles in the raw material supply hose 28 are returned to the raw material tank 7.

  The ejector 40 has an ejector pin 41 provided with a pressing plate portion 41a at the tip, and the ejector pin 41 protrudes toward the cavity 8 side from the storage position that constitutes a part of the molding surface 5a of the cavity mold 5 with the pressing plate portion 41a. A sliding guide cylinder 42 that slidably guides to the release position and a coil spring 43 that urges the ejector pin 41 back to the retracted position are provided.

  At the time of mold release, the ejector pin 41 is pressed against the return biasing force of the coil spring 43 by a driving means (not shown), and foaming is performed by the pressing plate portion 41a of the ejector pin 41 switched from the retracted position to the released position. The molded container 1 in the cavity 8 cooled after molding is released.

  The sliding guide cylinder 42 has a small-diameter sliding guide cylindrical body 42a that slidably guides the shaft portion 41b of the ejector pin 41, and a large-diameter storage cylinder that slidably stores the pressing plate portion 41a of the ejector pin 41. Part 42b.

  The storage tube portion 42b of the slide guide tube 42 is attached in close contact with the mounting recess 5A in which the cavity mold 5 is formed, and the slide guide tube 42 of the slide guide tube 42 penetrating the fixed frame 10 is attached. The base end side of the body 42a is fixed to the fixed frame 10 by tightening a screw member 45 screwed thereto.

  Since the sliding guide cylinder 42 is attached over the cavity mold 5 and the fixed frame 10, the sliding guide cylinder 42 is attached to the cavity mold 5 in a state in which the sliding processing accuracy between the sliding guide cylinder 42 and the ejector pin 41 is maintained in advance. Therefore, the clearance between the inner peripheral surface of the storage cylinder portion 42b that becomes the mounting hole 46 of the ejector pin 41 and the outer peripheral surface of the pressing plate portion 41a of the ejector pin 41 becomes extremely small, and the mounting hole 46 of the ejector pin 41 Generation of burrs at the molding mark Md can be suppressed.

[Other Embodiments]
(1) In the first embodiment described above, the molding mark Ma of the third vent hole 17C formed on the outer surface 1f of the side wall 1B of the container molded body 1 and the third surface formed on the upper surface 2c of the lid molded body 2. Although the molding mark Ma of the vent hole 17C has a needle hole shape, the molding mark Ma of the third vent hole 17C may be formed in a shape other than the needle hole shape.

(2) In the first embodiment described above, the total area of the molding trace Ma of the third vent hole 17C that appears on the outer surface 1f of each side wall 1B of the container molded body 1 is the same as that of the molding trace Mb formed on each other surface. Although the total area is reduced, the limit of the distribution in which the ratio formed on each surface other than the outer surface of the side wall is increased is to prevent the formation of communication holes from forming on the outer surface 1f of the side wall 1B. That is, the communication hole communicating with the cavity 8 is not disposed on the molding surface of the mold that forms the outer surface 1f of the side wall 1B.
Moreover, although the total area of the molding trace of the 3rd ventilation hole 17C which appears on the upper surface 2c of the lid forming body 2 was reduced from the total area of the molding trace formed on the lower surface 2a of the lid molding 2, the upper surface 2c In addition, the limit of the distribution in which the ratio formed on the lower surface 2a increases is to prevent the formation of communication holes from the upper surface 2c, that is, the mold 8 formed on the upper surface 2c has a cavity 8 on the molding surface. A communication hole that communicates with the communication hole is not disposed.

(3) In the first embodiment described above, the container molded body 1 and the lid molded body 2 are formed in a square (rectangular shape) in plan view, but may be formed in a hexagonal shape, an octagonal shape, a circular shape, a triangular shape, or the like.
In short, the usage, shape, thickness, etc. of the container molded body 1 and the lid molded body 2 are not particularly limited.

  (4) In the first embodiment described above, the polystyrene resin has been described as an example of the low expansion ratio thermoplastic resin. However, the present invention is not limited to this and may be a foamed polyethylene resin, a foamed polypropylene resin, or the like. .

  As described above, the outer wall surface of the side wall that is most easily noticeable during use, while providing sufficient strength and moderate heat insulation required as a container, and reducing the weight and manufacturing cost. It is possible to provide a foamed resin container capable of satisfactorily improving the decorativeness of the container.

Ma molding trace Mb molding trace Mc molding trace Md molding trace 1 container molded body 3 pattern 8 cavity 17 vent hole (communication hole)
17A 1st vent (vent)
17B Second vent (vent)
17C 3rd vent (vent)
23 Raw material filling port (communication hole)
46 Mounting hole (communication hole)

Claims (3)

  Raw material particles made of a thermoplastic resin with a low expansion ratio are heat-fused in a mold to form an upper opening container molded body, and the surface of the container molded body is formed by a communication hole communicating with the cavity of the mold. The foamed resin container is provided with a distribution in which the molding marks formed in the above are formed in a proportion that is formed on each surface other than the outer surface of the side wall.   The foamed resin container according to claim 1, wherein an uneven pattern is formed on the outer surface of the side wall of the container molded body.   One of the communication holes is a vent hole, the molding mark of the vent hole formed on the outer surface of the side wall of the container molded body has a needle hole shape, and the molding mark formed on the surface other than the outer surface of the side wall is a needle hole. The foamed resin container according to claim 1 or 2, wherein each of the foamed resin containers is formed into a slit shape having a larger area than the shape-formed trace.

Images