JPH0699965A - Multi-layer blow mold bottle of synthetic resin - Google Patents

Abstract

PURPOSE:To prevent color of inner layer from being seen as appearance of a bottle at a joint part which is formed by pinch-off of a multi-layer blow mold bottle of synthetic resin. CONSTITUTION:A joint part 6 formed by pinch off is substantially shaped in a laterally protruding trapezoid, which is designed to have a size in accordance with the thickness of a parison. By this, at the joint part 6, a dark color of an inner layer 8 is not seen from outside of a bottle through a light color of an outer layer 9. Thus, degradation of appearance of the bottle 1 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin multi-layer blow molding bottle that is blow molded from a multi-layered parison.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 53-15432 is known as a prior art of a synthetic resin multi-layer blow molding bottle. In this conventional technology, the joints formed by pinch-offs on the bottom of the bottle body blow-molded from the multi-layered tubular parison are tapered protrusions that project outward, so that each layer is joined at the joints. It is designed to be substantially continuous.

[0003]

However, in the above-mentioned prior art, it is possible to make the inner layer and the outer layer continuous with each other and to cover the outer side of the inner layer with the outer layer at the joint portion. The outer layer that covers the continuous inner layer is extremely thin. Therefore, the inner layer has a dark color such as opaque black for the purpose of shielding the contents, and the outer layer has a light color such as opaque white to improve the product image. In such a case, there is a problem that the dark color of the inner layer is visually recognized as a line on the protruding end surface of the joint portion, and the appearance of the bottle as a product is significantly deteriorated.

Therefore, the present invention was devised to solve the above-mentioned problems in the prior art, and it is necessary to position the inner layer sufficiently inward with respect to the outer layer at the joint formed by pinch-off. An object of the present invention is to prevent deterioration of the appearance due to the dark color of the inner layer being visible on the outer surface formed by the light color of the outer layer at the protruding tip of the joint.

[0005]

The means of the present invention for solving the above technical problems is a bottle body blow-molded from a tubular parison in which an inner layer has an opaque dark color and an outer layer has an opaque bright color. The pinch-off of this bottle forms a ridge on the outer surface of the bottom as a ridge with a substantially trapezoidal cross section, and the trapezoidal shape of this joint indicates the height and width of the parison. Be approximately equal to the wall thickness, make the thickness of the tip part approximately half the thickness of the parison, make the base end thickness approximately two-thirds of the wall thickness of the parison, There is a certain clearance angle within a range of approximately 8 to 15 °.

[0006]

The joint formed on the outer surface of the bottom of the bottle in the shape of a ridge by pinch-off has a thickness of approximately two-thirds or less of the thickness of the parison, that is, a flat crushed state. Since it is set to about 1/3 or less of the thickness of the parison,
At the time of forming the joint, approximately two-thirds of the softening resin material of the parison formed in the joint is extruded from the portion formed in the joint.

As described above, in the joint portion which is pressed and formed in the shape of a ridge by pinch-off, approximately two-thirds of the softening resin material of the parison portion formed in this joint portion is formed in the adjacent portion other than the joint portion. Although it is extruded, the front and rear surfaces of the joint have a cross-sectional shape that widens to the base end side at a relief angle of approximately 8 to 15 °, so the relief direction of the softening resin material generated by pressing, that is, flow displacement The direction is restricted to the proximal side of the joint.

Since the flow displacement of the softened resin material during the press molding of the joint portion is caused by the pressing of the cooled mold, the resin material portion contacting the surface of the mold, that is, the outer layer portion, is molded by the mold. Due to the decrease in fluidity due to the temperature decrease due to contact with the die and the contact resistance of the die, the fluid displacement is difficult, and on the contrary, the resin material portion located inside, that is, the inner layer portion, maintains high fluidity. You will receive the pushing force in the state.

Therefore, in the joint portion, almost all of the inner layer is extruded toward the base end side of the joint portion, and the inner layer is positioned largely inward from the tip surface of the joint portion.

The clearance angles of the front and rear surfaces of the joint are set to 8 to 15 ° because if the clearance angle is 8 ° or less, sufficient flow transfer force by pressing against the softening resin material cannot be given. If the clearance angle is 15 ° or more, it is not possible to obtain a sufficient flow movement distance by pressing the softening resin material.

Further, by making the height width of the joint substantially equal to the thickness of the parison, the thickness of the joint within the clearance angles on the front and rear surfaces of the joint described above and the thickness of the joint relative to the thickness of the parison. Within the ratio range, the amount of backward movement of the inner layer due to pressing can be set to a sufficient value.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a bottle 1 according to the present invention. The bottle 1 has a bottom portion 3 connected to a lower end of a tubular body 2 having a mouth tube integrally connected to an upper end thereof. The bottom part 3 is configured so that the bottom part 3 is recessed inward of the body part 2
And a leg wall 5 that forms a "seat" around the bottom wall 4, and a joint portion 6 formed by pinch-off in the shape of a horizontal ridge at the center of the outer surface (lower surface) of the bottom wall 4. Has been done.

The bottle body 1 has a multilayer structure (see FIG. 2) whose walls are an inner layer 8 and an outer layer 9, and the inner layer 8 is an inner surface formed of a virgin PP material colored in opaque black. The inner layer 8a is composed of an inner layer 8a and a middle inner layer 8b formed of recycled opaque black colored PP material, and the outer layer 9 is
An outer surface outer layer 9a formed of a transparent PP material for exhibiting excellent gloss on the surface of the bottle body 1, and an inner and outer layer 9b formed of an opaque white colored PP material. There is.

Of the layers, the thickness of the middle and outer layers 9b is 0.584.
mm is the largest, and the outer surface outer layer 9a has a layer thickness of the middle outer layer 9b.
Is less than half of 0.27 mm, and the layer thickness of the inner layer 8 is a value that can sufficiently shield the contents (specifically 62%).
9mm), and the parison has a wall thickness of 1.483.
It is mm.

With respect to the dimension of the thickness of each layer, the dimension of each part of the joint portion 6 is such that the height width h is slightly larger than the thickness of the parison of 1.5 mm, and the tip end thickness w1 is the thickness of the parison. Of less than 0.7 mm, the base end thickness w2 is 0.9 mm, and the clearance angle θ is 10 °.

As is apparent from FIG. 4, in the joint portion 6, the protruding end of the inner layer 8 toward the outside is a sufficient value from the tip of the joint portion 6 to the inner side (approximately the same as the tip portion thickness w1 of the joint portion 6). Value), the black color of the inner layer 8 does not penetrate the white color of the outer layer 9 and is not visible from the outside of the bottle 1 at the joint portion 6.

As shown in FIGS. 2 and 3, the leg wall 5 portion located on the extension of the joint portion 6 is removed and the escape groove 7 is formed.
Was molded because the height width h of the joint 6 was
This is so that they can be formed equally over the entire length of the.

[0018]

Since the present invention has the above-mentioned structure, it has the following effects. Since the inner layer at the joint can be located sufficiently inside, the dark color of this inner layer does not permeate through the outer layer and is not visible at the tip surface of the joint, which allows the color of the inner layer to be the outer surface of the bottle. The visual appearance makes it possible to eliminate the deterioration of the appearance.

Since the flow displacement of the inner layer at the joint is inevitably achieved by the pinch-off in the ordinary blow molding, the conventional molding method can be accurately and surely achieved without using a special molding method. can do.

[Brief description of drawings]

FIG. 1 is an overall front view showing an embodiment of the present invention.

FIG. 2 is a bottom side view of the embodiment shown in FIG.

3 is a bottom view of the embodiment shown in FIG.

FIG. 4 is an enlarged vertical side view of a joint portion in the embodiment shown in FIG.

[Explanation of symbols]

1; Bottle 2; Body 3
; Bottom part 4; bottom wall 5; leg wall 6
Joined part w1; Tip thickness w2; Base end thickness h
Height width θ; Relief angle 7; Relief groove 8
Inner layer 8a; inner surface inner layer 8b; middle inner layer 9
Outer layer 9a; outer surface outer layer 9b; middle outer layer

Claims (1)

[Claims] 1. A bottle body (1) blow-molded from a tubular parison in which the inner layer (8) has an opaque dark color and the outer layer (9) has an opaque light color, and the outer surface of the bottom portion (3) is pinched off. The height (width) (h) of the joint (6) shaped like a ridge
Is approximately equal to the wall thickness of the parison, the tip thickness (w1) is approximately half of the parison thickness, and the base thickness (w2) is approximately two-thirds of the parison thickness, and A synthetic resin multi-layer blow molding bottle having a protrusion having a trapezoidal cross-section with a clearance angle (θ), which is an inclination angle of the front and rear surfaces, of approximately 8 to 15 °.