JP4024671B2 - Method for producing foam-interior hollow molded product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a foam-incorporated hollow molded article comprising a hollow body having one wall and the other wall facing each other at an interval, and a foam body that is embedded in the hollow body without a gap. It is.
[0002]
[Prior art]
An example of a method for producing a hollow molded product in which a conventional foam is incorporated will be described.
[0003]
In this conventional manufacturing method, as shown in FIG. 8 (a), a parison made of polyolefin resin is placed between a pair of split molds 101, 102 that are opened, and then clamped and pressurized by a nozzle 103. The hollow body 104 is blow-molded into a shape along the cavities 101a and 102a by introducing a fluid. After that, as shown in FIG. 8 (b), completely foamed polyolefin resin foam particles 105 are press-fitted into the hollow body 104 through the nozzle 103, and then water vapor is passed through the nozzle 103. It is introduced and fused (see Japanese Patent No. 29003436).
[0004]
[Problems to be solved by the invention]
In the above-described conventional technology, when the foam particles made of a polyolefin resin completely foamed in the blow-molded hollow body are press-fitted and filled, there is a possibility that a portion in which the foam particles are not filled is generated in the hollow body. In particular, when the interval between the opposite one wall and the other wall of the hollow body is narrow, for example, when the interval is 40 mm or less, it becomes difficult to fill the entire hollow body with foam particles. As a result, a space in which the foam particles are not filled is formed in the hollow body, and there is a problem that a foam-incorporated hollow molded article having excellent strength such as rigidity and heat insulation cannot be obtained.
[0005]
The present invention has been made in view of the above-mentioned problems of the prior art, and is capable of producing a foam-incorporated hollow molded product excellent in strength such as rigidity and heat insulation. An object of the present invention is to provide a manufacturing method.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing a foam-incorporated hollow molded product according to a first aspect of the present invention includes a hollow body constituted by one wall and the other wall facing each other at an interval, and the hollow body In a method for manufacturing a foam-incorporated hollow molded article having a foam that is internally mounted, a mold having a cavity for vacuum-forming a portion that becomes the one wall of the hollow body, and the hollow body The other mold provided with a cavity for vacuum forming the other wall, and one heating surface facing the one mold and the other mold in an open state, respectively And using the middle frame having the other heating surface, the one mold and the other mold are opened, and the middle frame is arranged between the two molds, Plastic between the cavity and the one heating surface One of the sheet-shaped parisons disposed, and the other sheet-shaped parison plasticized between the cavity of the other mold and the other heating surface, and the cavity of the one mold A closed space is formed between the one sheet-shaped parison and a portion to be the one wall is vacuum-formed, and a closed space is formed between the cavity of the other mold and the other sheet-shaped parison. Forming and vacuum forming the part that becomes the other wall, and then separating the middle frame from between the one mold and the other mold, and then the part that becomes the one wall and the The foam is disposed between the other wall portion, and then the one mold and the other mold are clamped, and the one sheet-shaped parison and the other sheet-shaped parison are The pin After turning off and welding the inner surface of the part to be the one wall and the inner surface of the part to be the other wall and the outer surface of the foam to form a hollow molded product intermediate, the one mold and the The other mold is opened and the hollow molded product intermediate is taken out and cooled and contracted.
[0007]
A method for producing a foam-incorporated hollow molded article according to a second aspect of the invention includes a hollow body constituted by one wall and the other wall facing each other at an interval, and a foam housed in the hollow body. In the method of manufacturing a foam-incorporated hollow molded article, one mold having a cavity for vacuum forming the part that becomes the one wall of the hollow body and the part that becomes the other wall of the hollow body are vacuum formed. An intermediate frame having one heating surface and the other heating surface that face each other with a gap between the other mold and the other mold in the opened state. The one mold and the other mold are opened, and the middle frame is disposed between the mold and the cavity of the one mold and the one heating surface. One sheet-like parison plasticized between And arranging the other sheet-like parison plasticized between the cavity of the other mold and the other heating surface, and then the cavity of the one mold and the one sheet-like parison Forming a closed space between them and vacuum forming a portion to be the one wall, and forming a closed space between the cavity of the other mold and the other sheet-like parison, And forming a closed space between the one sheet-like parison and the middle frame and between the other sheet-like parison and the middle frame, respectively. A pressurized fluid is introduced, and the portion that becomes the one wall and the portion that becomes the other wall are pressed from the inner frame side by the inner pressure to closely contact the cavity, and then the one molding And the other mold are separated from each other, and then a foam is disposed between the one wall portion and the other wall portion, and then the one molding portion. The mold and the other mold are clamped to pinch off the one sheet-like parison and the other sheet-like parison, and the inner surface of the portion that becomes the one wall and the portion that becomes the other wall After the inner surface and the outer surface of the foam are welded to form a hollow molded product intermediate, the one molding die and the other molding die are opened, and the hollow molded product intermediate is taken out and cooled. It is characterized by making it.
[0008]
In addition, the one heating surface and the other heating surface of the middle frame are formed on the inner surface of the portion that becomes one wall of one sheet-like parison and the other of the other sheet-like parison when forming the hollow molded article intermediate. The temperature is set to keep the one sheet-like parison and the other sheet-like parison so that the inner surface of the wall portion and the outer surface of the foam are welded.
[0009]
Further, when forming the hollow molded article intermediate, air vent holes are perforated in at least one of the part that becomes one wall of one sheet-like parison and the part that becomes the other wall of the other sheet-like parison, Air is removed from the foam through the air vent hole.
[0010]
In addition, the air vent hole is perforated in a protruding portion that protrudes outwardly and is formed in at least one of a portion that becomes one wall of one sheet-like parison and a portion that becomes the other wall of the other sheet-like parison. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
First, an example of a foam-internal hollow molded product manufactured by the method for manufacturing a foam-internal hollow molded product according to the present invention will be described. As shown in FIG. 1, the foam-incorporated hollow molded article of the present example includes a flat plate-like hollow body 1 constituted by one wall 2 and the other wall 3 facing each other at an interval, and the inside of the hollow body 1. The inside of the hollow body 1 and the outer surface of the foam 4 are welded together.
[0012]
In this example, the foam body 4 is divided into two foam bodies 4a and the other foam body 4b along the inclined surface 5 from one wall side at one end in the longitudinal direction to the other wall side at the other end. ing. However, the present invention is not limited to this, and the foam may be an integral one that is not divided.
[0013]
Subsequently, an embodiment of the method for producing a foam-incorporated hollow molded product according to the present invention will be described by taking as an example the case of producing the foam-incorporated hollow molded product shown in FIG.
[0014]
First, the mold used in the present embodiment will be described.
[0015]
As shown in FIG. 2 and FIG. 3, one molding die 21 vacuum-forms a portion 2 a that becomes one wall having a larger shape dimension that matches the cooling shrinkage than the shape dimension of one wall 2 of the hollow body 1. A concave cavity 21a, a plurality of vacuum suction holes (not shown) having one end opened in the cavity 21a and the other end connected to a vacuum generation source, and a pinch-off portion 21b provided in the peripheral edge of the open portion of the cavity 21a And a recess 21c provided outside the pinch-off portion 21b.
[0016]
The other molding die 31 includes a concave cavity 31a for vacuum-forming a portion 3a which is the other wall having a shape larger than the shape of the other wall 3 of the hollow body 1 in accordance with the cooling shrinkage, and one end of the cavity 31a. A plurality of vacuum suction holes (not shown) whose side is open and whose other end is connected to a vacuum generation source, a pinch-off part 31b provided at the peripheral edge of the open part of the cavity 31a, and provided outside the pinch-off part 31b And a recess 31c.
[0017]
When the middle frame 40 is positioned between one mold 21 opened and the other mold 31, the body 41 having heating surfaces 41a and 41b facing the cavities 21a and 31a, respectively, , Heating means (not shown) including a heater or the like installed in the body portion 41, and support portions 42 for supporting the moving frames 43 and 44 facing the recesses 21c and 31c of the both, respectively, The moving frames 43 and 44 are configured to be moved in the axial direction via linear drive means such as a fluid pressure cylinder and an electric cylinder (not shown).
[0018]
(1) As shown in FIG. 2, one mold 21 and the other mold 31 are opened, and the middle frame 40 is moved and arranged at a substantially central portion of the space between the two molds. One sheet-like parison 20 that is plasticized is disposed in a gap between the cavity 21a of the molding die 21 and one heating surface 41a of the barrel 41, and the cavity 31a and barrel 41 of the other molding die 31 are disposed. The other sheet-like parison 30 plasticized is disposed in the gap with the other heating surface 41b.
[0019]
(2) After the above (1), by projecting one moving frame 43 toward one mold 21 and sandwiching one sheet-like parison 20 between its tip surface 43a and the recess 21c A closed space is formed between one cavity 21a and one sheet-like parison 20. At the same time, the other moving frame 44 is protruded toward the other mold 31 and the other sheet-like parison 30 is sandwiched between the front end surface 44a and the recess 31c. A closed space is formed between the other sheet-like parison 30.
[0020]
(3) After (2) above, a portion that becomes one wall from one sheet-like parison 20 by vacuum-sucking the closed space between the cavity 21a of one mold 21 and one sheet-like parison 20 2a (shown in FIG. 3) is vacuum formed, and the closed wall between the cavity 31a of the other mold 31 and the other sheet-like parison 30 is vacuum-sucked so that the other wall from the other sheet-like parison 30 is sucked. The portion 3a (shown in FIG. 3) to be is vacuum formed.
[0021]
(4) After (3) above, the mold 21 and the mold 31 are closed and the one moving frame 43 and the other moving frame 44 are retracted as shown in FIG. By making contact with both side surfaces of the support portion 42 of the frame 40, a closed space is formed between the intermediate frame 40 and the portion 2a serving as one wall and the portion 3a serving as the other wall that are vacuum formed. The pressurized fluid is introduced into the closed space through the blowing means provided in the middle frame 40, and the internal pressure pressurizes the portion 2a serving as one wall and the portion 3a serving as the other wall from the middle frame side. In close contact with the cavities 21a and 31a.
[0022]
As a modification, in the above step (3), when the portion 2a serving as one wall and the portion 3a serving as the other wall can be vacuum formed with high accuracy, this step is omitted, You may transfer to the step (5).
[0023]
(5) After the above (4), the mold 21 of the one mold 21 and the mold 31 of the other mold are opened, and the middle frame 40 is completely separated from between the two, as shown in FIG. One foam 4a is attached to the inner surface of the portion 2a that becomes the wall of the other, and the other foam 4b is attached to the inner surface of the portion 3a that becomes the other wall.
[0024]
(6) After the above (5), as shown in FIG. 5, the one mold 21 and the other mold 31 are clamped to pinch off the one sheet parison 20 and the other sheet parison 30. At the same time, the hollow molded product intermediate body is molded by welding the inner surface of the hollow body and the outer surface of the foam molded into a large shape and dimension suitable for the cooling shrinkage.
[0025]
(7) After the above (6), mold opening is performed to take out the hollow molded product intermediate, and cooling shrinkage is performed to obtain a foam-embedded hollow molded product.
[0026]
Next, another embodiment of the method for producing a foam-incorporated hollow molded product according to the present invention will be described. In the present embodiment, the present embodiment and the above-described one embodiment are such that, in this embodiment, at least one of the one wall 2 and the other wall 3 of the hollow body 1 has an air vent hole 2c (3c) (FIGS. 6 and 6). 7), and a step of bleeding air between the hollow body 1 and the foam 4a (4b) through the air vent hole 2c (3c) is different. Other steps are the same as those of the above-described embodiment, so that the description thereof will be omitted, and only different points will be described below.
[0027]
In the present embodiment, the convex portion forming concave portion 22 (32) provided in at least one of the cavity 21a of one molding die 21 and the cavity 31a of the other molding die 31, and the convex portion forming concave portion 22 (32). ) And an air vent passage 25 (35) having one end opened at the bottom surface 22a (32a) and the other end opened to the outside of the mold, and a needle 24 (inserted and retracted into the air vent passage 25 (35)). 34) and a molding die having a suction passage 23 (33) having one end opened at the bottom surface 22a (32a) of the convex portion forming concave portion 22 (32) and the other end connected to a vacuum generation source.
[0028]
As in the above-described embodiment, after the steps (1) and (2), in the step (3), the tip of the needle 24 (34) is used to form a convex portion as shown in FIG. In a state where the recess 22 (32) protrudes inward from the bottom surface 22a (32a), vacuum suction is performed through the suction passage 23 (33), so that the portion 2a that becomes one wall of one sheet-like parison 20 and the other The convex part 2b (3b) is formed in at least one of the part 3a used as the other wall of this sheet-like parison 30, and the air vent hole 2c (3c) is drilled simultaneously.
[0029]
Thereafter, after the steps (4) and (5) as in the above-described embodiment, in the step (6), as shown in FIG. By opening the hole 2c (3c) and communicating with the air vent passage 25 (35), it is interposed between the foam 4 and at least one of the part 2a serving as one wall and the part 3a serving as the other wall. The air to be discharged is exhausted out of the mold sequentially through the convex portion 2b (3b), the air vent hole 2c (3c), and the air vent passage 25 (35).
[0030]
After that, the foam-internal hollow molded product is obtained through the step (7) as in the embodiment described above.
[0031]
According to the present embodiment, the foam-incorporated hollow molded product having a large area with respect to the thickness, such that air may remain between the hollow body and the foam body in the hollow body. Can also be manufactured with good yield.
[0032]
In the present invention, polyethylene, polypropylene, polystyrene, polyamide, polyethylene terephthalate, ABS resin or the like is used as the thermoplastic resin constituting the sheet-like parison.
[0033]
In addition, as the foam to be installed, foamed polyethylene, foamed polypropylene, foamed polystyrene, or the like can be used. However, when the same thermoplastic resin constituting the sheet-like parison is used, recycling becomes easy.
[0034]
Furthermore, as a sheet-like parison, a decorative film layer having various patterns such as a glossy surface, a texture pattern, a wood grain pattern, a marble pattern, and a stone pattern is laminated as a sheet-like parison depending on the application. For example, a laminate in which different types of thermoplastic resin layers are laminated, such as a laminate in which a polyolefin resin layer (inner layer) and a polyethylene terephthalate layer (outer layer) having different surface hardnesses are laminated, is used. Can do.
[0035]
【The invention's effect】
Since this invention is comprised as mentioned above, there exists an effect as described below.
[0036]
A hollow body constituted by one wall and the other wall which are opposed to each other with an interval is welded to a foam body provided in the hollow body. In addition, in the conventional method for producing a hollow molded product with an internal foam, it takes a long time for cooling in the mold and tends to increase the molding cycle time. By welding the inner surface of the body, the hollow body is not inadvertently deformed even if the mold is released in a short cooling state. Furthermore, regardless of the size of the space between the opposite one wall and the other wall of the hollow body, the foam can be embedded without gaps.
[0037]
As a result, the molding cycle time is shortened and productivity is improved. Moreover, the foam-interior hollow molded article excellent in strength such as rigidity and heat insulation can be produced.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an example of a foam-incorporated hollow molded product produced by the method for producing a foam-incorporated hollow molded product according to the present invention, with a part of the hollow body cut away.
FIG. 2 shows an embodiment of a method for producing a foam-incorporated hollow molded product, in which one molding die and the other molding die are opened and an inner frame is disposed between the two molding cavities, and the cavity of one molding die It is explanatory drawing which shows the process of arrange | positioning a sheet-like parison between each and a middle frame and between the cavity and middle frame of the other shaping | molding die.
FIG. 3 is a step after the step shown in FIG. 2, in which after one sheet-like parison and the other sheet-like parison, one wall portion and the other wall portion are vacuum formed, respectively. FIG. 5 is an explanatory view showing a process of closing the mold and forming a closed space portion between the two and the middle frame.
FIG. 4 is a step after the step shown in FIG. 3, and in a state where the mold is opened, one foam is disposed on the inner surface of the portion that becomes one wall in close contact with the cavity of one mold. And it is explanatory drawing which shows the process of arrange | positioning the other foam inside the part used as the other wall closely_contact | adhered to the other cavity.
FIG. 5 is an explanatory view showing a step of pinching off one sheet-like parison and the other sheet-like parison after the step shown in FIG. 4;
FIG. 6 is an explanatory view showing a step of punching an air vent hole in at least one of one sheet-like parison and the other sheet-like parison in another embodiment of the method for producing a foam-incorporated hollow molded product.
7 is an explanatory view showing a step of bleeding air through an air vent hole after the step shown in FIG. 6; FIG.
FIG. 8 is an explanatory view showing an example of a conventional method for producing a foam-incorporated hollow molded product.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hollow body 2 One wall 2a One wall 2b (3b) Convex part 2c (3c) Air vent 3 Other wall 3a The other wall 4 Foam 4a One foam 4b The other foam Body 20 One sheet-like parison 21 One mold 21a, 31a Cavity 21b, 31b Pinch-off portion 21c, 31c Recess 22 (32) Convex-forming recess 23 (33) Suction passage 24 (34) Needle 25 (35) Air vent passage 30 The other sheet-like parison 31 The other mold 40 The middle frame 41 The body 41a The one heating surface 41b The other heating surface 42 The support portions 43 and 44 Moving frame

Claims (5)

In the method for producing a foam-incorporated hollow molded article comprising a hollow body constituted by one wall and the other wall facing each other at an interval, and a foam housed in the hollow body,
One mold provided with a cavity for vacuum forming the part to be the one wall of the hollow body, and the other mold having a cavity for vacuum forming the part to be the other wall of the hollow body; Using a middle frame having one heating surface and the other heating surface facing each other at an interval to the one mold in the opened state and the other mold,
The one mold and the other mold are opened, and the middle frame is disposed between the two molds, and plasticization is performed between the cavity of the one mold and the one heating surface. After placing one sheet-like parison made and the other sheet-like parison plasticized between the cavity of the other mold and the other heating surface,
A closed space is formed between the cavity of the one mold and the one sheet-like parison to vacuum form a portion that becomes the one wall, and the cavity of the other mold and the other sheet-like form Forming a closed space between the parison and vacuum forming the part that becomes the other wall,
Next, after the middle frame is detached from between the one mold and the other mold, a foam is disposed between the portion serving as the one wall and the portion serving as the other wall. ,
Next, the one mold and the other mold are clamped to pinch off the one sheet-like parison and the other sheet-like parison, and the inner surface of the portion serving as the one wall and the other After forming the hollow molded product intermediate by welding the inner surface of the portion to be the wall and the outer surface of the foam,
A process for producing a foam-incorporated hollow molded product, wherein the one mold and the other mold are opened to take out the hollow molded product intermediate and cool and shrink. In the method for producing a foam-incorporated hollow molded article comprising a hollow body constituted by one wall and the other wall facing each other at an interval, and a foam housed in the hollow body,
One mold provided with a cavity for vacuum forming the part to be the one wall of the hollow body, and the other mold having a cavity for vacuum forming the part to be the other wall of the hollow body; Using a middle frame having one heating surface and the other heating surface facing each other at an interval to the one mold in the opened state and the other mold,
The one mold and the other mold are opened, and the middle frame is disposed between the two molds, and plasticization is performed between the cavity of the one mold and the one heating surface. After placing one sheet-like parison made and the other sheet-like parison plasticized between the cavity of the other mold and the other heating surface,
A closed space is formed between the cavity of the one mold and the one sheet-like parison to vacuum form a portion that becomes the one wall, and the cavity of the other mold and the other sheet-like form Forming a closed space between the parison and vacuum forming the part that becomes the other wall,
Thereafter, a closed space is formed between the one sheet-like parison and the middle frame and between the other sheet-like parison and the middle frame, and a pressurized fluid is introduced into these closed spaces. Pressing the part that becomes the one wall and the part that becomes the other wall from the inner pressure from the inner frame side to closely contact the cavity,
Next, after the middle frame is detached from between the one mold and the other mold, a foam is disposed between the portion serving as the one wall and the portion serving as the other wall. ,
Next, the one mold and the other mold are clamped to pinch off the one sheet-like parison and the other sheet-like parison, and the inner surface of the portion serving as the one wall and the other After forming the hollow molded product intermediate by welding the inner surface of the portion to be the wall and the outer surface of the foam,
A process for producing a foam-incorporated hollow molded product, wherein the one mold and the other mold are opened to take out the hollow molded product intermediate and cool and shrink. One heating surface and the other heating surface of the middle frame are formed on the inner surface of the portion that becomes one wall of one sheet-like parison and the other wall of the other sheet-like parison when forming the hollow molded article intermediate. The foamed body according to claim 1 or 2, wherein the temperature is set at a temperature at which the one sheet-like parison and the other sheet-like parison are kept warm so that the inner surface of the portion and the outer surface of the foam are welded to each other. A method for producing a hollow molded article. When forming the hollow molded product intermediate, an air vent hole is perforated in at least one of a portion that becomes one wall of one sheet-like parison and a portion that becomes the other wall of the other sheet-like parison. The method for producing a foam-incorporated hollow molded article according to any one of claims 1 to 3, wherein air is removed from the foam through the holes. The air vent hole is perforated in a convex portion projecting outwardly formed in at least one of a portion that becomes one wall of one sheet-like parison and a portion that becomes the other wall of the other sheet-like parison. The method for producing a foam-incorporated hollow molded article according to claim 4.

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