JPS61148019A - Plastic hollow body by bow molding - Google Patents

Abstract

PURPOSE:To offer a plastic hollow body by blow molding which is superior in joining strength, by a method wherein a protection is provided in a protruded state on the backside of an insertion article to be obtained by laying an external fringe part of the same by wrapping up in a plastic wall and a swollen part formed on the tip of the same is laid by wrapping up in the plastic wall. CONSTITUTION:After a fitting bracket 20 has been arranged within a cavity 44, a parison P in a plasticizing state which has been extruded by an extruding machine for thermoplastics is arranged between split type molds 41, 42. Then when the parison P is preblown and the molds 41, 42 are closed, the parison P is welded partly between one side cavity 43 and the fitting bracket 20, the plastics of the confronting parison P is welded unitarily and positioned around the fitting bracket 20. When closure of the molds 41, 42 is made to progress further, the parison P is compressed and the same is made to expand along shapes of the cavities 43, 44 and fitting bracket 20 by introducing a pressurized fluid within the parison.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to blow-molded plastic hollow bodies such as packaging containers, table tops, core materials for automobile seats, and luggage loading pallets.

[Conventional technology]

With the insert placed in the blow molding mold,
A blow-molded plastic hollow body made by expanding a plastic parison and integrally bonding an insert to a blow-molded plastic wall is known as, for example, a packaging container in which a display plate as an insert is bonded to the container wall. . Figure 2 shows a packaging container IA as an example of a conventional blow-molded plastic hollow body, and the display plate 2A is a display board 2A with two display boards installed as inserts in the mold when the packaging container IA is blow-molded. The display board 2 is attached to the plastic wall 4A by expanding the plastic parison.
A is joined together.

[Problem that the invention seeks to solve]

In the conventional packaging container IA as shown in FIG. 2, the bonding strength between the display panel 2A and the plastic wall 4A is poor. For example, if the surface of the parison is cold during blow molding,
The welding between the Balison plastic wall 4A and the display board 2A, which is the insert, was defective, resulting in cracks and cracks at the joints.
It has drawbacks such as gaps and deformation.

[Means for solving problems]

An object of the present invention is to prevent cracks, gaps, deformation, etc. from occurring at the joint between the wall of the plastic hollow body and the insert, even if external stress is applied to the insert from any direction, and to improve the joint strength. To provide an excellent blow-molded plastic hollow body.

The above-mentioned object of the present invention is to wrap the outer peripheral edge of the insert with the wall of the hollow plastic body and embed it therein, and to form a protrusion with a bulged tip on the back surface of the insert so that the bulge can be inserted into the hollow plastic body. This is achieved by encasing it in a wall and burying it. To describe the structure of the present invention more clearly, it is (a) a blow-molded plastic hollow body formed by bonding an insert to the surface of a plastic hollow body, and (b) an outer peripheral edge of the insert to a plastic wall. At the same time, (c) a protrusion is integrally provided on the back side of the insert, a bulge is formed at the tip of the protrusion, and (d) the bulge is wrapped with a plastic wall. This invention relates to a blow-molded plastic hollow body that is buried.

[Effect]

According to the present invention, both the outer peripheral part and the inner part of the insert have a structure in which they are physically fixed to the wall of the hollow plastic body, and the parison that comes into contact with the fixed part of the insert in blow molding is Since the blowing ratio is relatively low, the insert and the plastic wall formed by expanding the parison are welded together. moreover,
The plastic wall formed by expanding the ballisne will shrink slightly when it is cooled after molding, but at this time the insert will be more firmly joined due to the shrinkage of the plastic wall.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.
The figure shows a packaging container as an example of a blow-molded plastic hollow body according to the present invention. 1 is a packaging container according to the present invention, which is constructed by blow molding a thermoplastic such as polyethylene or polypropylene. 2
is a display board that is an insert with printing or engraving on its surface, and the outer peripheral edge 3 of the display board 2 is configured such that the front side is cut out and the tip is located inside a blow-molded plastic wall 4. has been done. A protrusion 5 is integrally formed on the back side of the display panel 2, and a protrusion 6 is formed at the tip of the protrusion. Then, the outer peripheral edge 3 of the display board 2
is wrapped and buried in a plastic wall 4a, and a bulge 6 formed on the back surface of the display board 2 is also wrapped and buried in a plastic wall 4b, and is formed by expanding a special blow-molded ballison. The plastic wall 4 is integrally welded to the display panel 2, which is an insert.

Figures 3 to 5 show the other side of the blow-molded plastic hollow body according to the present invention as a table top, and Figures 6 to 8 show the blow molding process for the top plate. be.

Reference numeral 10 designates the top plate of the table, which has a hollow double-walled structure by blow molding thermoplastics such as polyethylene, polypropylene, ABS resin, and polycarbonate.

30 is a leg of the table, 31 is a flange extending from one end of the leg 30, and the flange 31 is connected to the top plate 10.
The mounting bracket 20 is an insert fixed to the
and bolts 32. 11 and 12 are plastic upper and lower walls, and 13 is a hollow portion formed between the upper wall 11 and the lower wall 12. The mounting bracket 20 made of metal or hard plastic consists of a plate-shaped body 21 and four protrusions 25 that protrude from the plate-shaped body 21 into the top plate 10, and a bulge 26 is formed near the tip of the protrusion 25. Further, a hole 22 passing through in the axial direction is formed inside the projection 25, and a female thread is formed in the hole 22. The outer peripheral edge 23 of the plate-shaped body 21 is located near the surface of the lower wall 12, and is formed on the base end wall 14 of the support wall 14 extending inward from the plastic lower wall 12.
The first fitting part A is formed by being wrapped and buried in the first fitting part A.

Further, the bulging portion 2 of the protrusion 25 integrally protrudes from the plate-shaped body 21.
The upper end wall 14 of the support wall 14 also extends inward from the lower wall 7.
b, and is embedded inside the top plate 10, forming a second fitting part B. The mounting bracket 20 and the plastic lower wall 12 are welded together during blow molding, and the support wall 14 extending from the lower wall 12 and the upper wall 11 opposing it are also welded together during blow molding.

Further, the plate-shaped body 21 of the mounting bracket 20 is located slightly inward from the surface of the lower wall 12, thereby forming a recess 15 in which the flange 31 of the leg portion 30 is positioned. When attaching the legs 30, the legs 30 are attached to the top plate 10 by positioning the flange 31 in the recess 15 and screwing the bolts 32 into the female threads of the projections 25.

Next, to explain the blow molding process of the top plate 10 according to FIGS. 6 to 8, 41.42 is a split type blow molding mold, 43.44 is a cavity, and 45 is a mounting bracket which is an insert member. 20 in the cavity 44, and a convex portion 46 of the holding portion 45 is inserted into the hole 22 of the mounting bracket 20.

After the mounting bracket 20 is placed in the cavity 44 as described above, a thermoplastic such as polyethylene is melted and kneaded in an extruder (not shown) and the extruded parison P in a plasticized state is shown in FIG. As shown, it is placed between split molds 41 and 42.

Next, by pre-blowing the parison P and closing the molds 41 and 42, the parison P is heated as shown in FIG.
is partially welded between the cavity 43 on one side and the mounting bracket 20, and the plastic of the opposing Balison P is welded together, and the Parison P is attached to the mounting bracket 20.
located around.

Next, as the molds 41 and 42 are closed, the parison P between the cavity 43 and the mounting bracket 20 is compressed, and pressurized fluid is introduced into the parison P to move the parison P into the cavity 43 as shown in FIG. .44 and the shape of the mounting bracket throat 20. At this time, the parison P is welded together so as to wrap around the bulging part 26 and the outer peripheral edge part 23 of the mounting bracket 20, and the upper wall 1 of the top plate 1o
1. The lower wall 12 and the support wall 14 are molded. After cooling the molded product, the molds 41 and 42 are opened and the molded product is taken out.
A top plate 1o as shown in FIG. 3 is obtained.

〔Effect of the invention〕

Since the blow-molded plastic hollow body according to the present invention has a structure in which both the outer peripheral part and the inner part of the insert are fixed to the plastic wall, no matter which direction external stress acts on the insert, In addition, even if the hollow body shrinks after blow molding, cracks, gaps, deformation, etc. will not occur at the joint between the insert and the plastic wall.
Excellent adhesion strength.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a packaging container which is an embodiment of the blow-molded plastic hollow body according to the present invention, FIG. 2 is a partially cutaway front view of a conventional packaging container, and FIG. 3 is a partially cutaway front view of a conventional packaging container. Fig. 4 is an enlarged view of the upper part of the table top plate, which is the other side of the blow-molded hollow body, Fig. 5 is a 1-1 sectional view of Fig. 4, and Figs. FIG. 8 is a sectional view of the main part of the mold showing the blow molding process of the top plate.

Claims (1)

[Claims] This is a blow-molded hollow body made by joining an insert to the surface of a hollow plastic body.The outer periphery of the insert is wrapped and buried in a plastic wall, and a protrusion is integrally protruded from the back of the insert. A blow-molded plastic hollow body, characterized in that a bulge is formed at the tip of the protrusion, and the bulge is surrounded and embedded in a plastic wall.