In-mold labeled container and molding process thereof

Abstract

The objects of this invention are to set a predetermined height position for the portion of parison or preform that is the first to come in contact with body molding planes of a split mold and to prevent air from being trapped between in-mold labels and the container which is blow molded from the parison or the preform. In-mold labels are fixed to the entire outer surface of body of main container. An annular thinnest wall portion is formed in the wall of the body so that the thinnest wall portion is the first to come in contact with the body molding planes of a split mold. Under this construction, no bulge of air is formed between the body and the in-mold labels fixed to the entire surface of the body.

Claims

1. A process for blow-molding an in-mold labeled container comprising a main container having in-mold labels fixed to an outer peripheral surface of a body in a manner extending around the body over a whole circumferential length, the body having a thinnest wall portion formed annularly in a middle part of the body as viewed in a height direction, the process comprising: a first process that comprises extrusion molding a parison so as to give the parison an annular thin-wall portion by means of wall thickness control, the parison being later blow-molded into the main container, a second process that comprises pinching the parison with both halves of a split mold, while setting the thin-wall portion at a position opposed to body molding planes of the split mold when the pair of halves of the split mold is clamped with each in-mold label being held by a corresponding body molding plane, and a third process that comprises blow molding the parison into the main container to expand and deform the thin-wall portion into the thinnest wall portion of the container, wherein the thin-wall portion first contacts with the in-mold labels during a period when the perison is being blow-molded in order to create the body that has an inner peripheral body surface with a wall thickness thereof gradually growing thick toward upper and lower ends of the body starting from the thinnest wall portion and the outer peripheral surface that extends along one plane such that the outer peripheral surface is flat.

2. The process for molding an in-mold labeled container according to claim 1 wherein the parison is pinched with both halves of the split mold after the in-mold labels have been held in place at positions opposed to the thin wall portion.

3. The process for molding an in-mold labeled container according to claim 1 wherein the in-mold labels are held in place in the split mold by vacuuming all edges of the in-mold labels in the circumferential direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a front elevational view of the container in the first embodiment of this invention, with right half being illustrated in a vertical section.

(2) FIG. 2 is an enlarged cross-sectional plan view of the container of FIG. 1, taken from line A-A.

(3) FIG. 3 is an exploded perspective view of the container in the second embodiment of this invention.

(4) FIG. 4 is a front elevational view of the container in the second embodiment of this invention shown in FIG. 3, with right half being illustrated in a vertical section.

(5) FIG. 5 is a front elevational view of the container in the third embodiment of this invention, with right half being illustrated in a vertical section.

(6) FIG. 6 is a front elevational view of the container in the fourth embodiment of this invention, with right half being illustrated in a vertical section.

(7) FIG. 7 is a vertical section showing an exemplified structure of the split mold for molding the container of this invention.

(8) FIG. 8 is a development showing an exemplified structure of the body molding plane for use in the split mold shown in FIG. 7.

(9) FIG. 9 is an explanatory diagram showing blow molding behavior displayed in the molding process of this invention.

EXPLANATION OF CODES

(10) 1. Main container 2. Neck 3. Shoulder 4. Cylindrical body 4a. Thinnest wall portion 5. Peripheral raised rib 6. Bottom 7. In-mold label 7a. Butting edge 7b. Gap 8. Cap 9. Fitting cylinder 10. Top plate 11. Hinge 12. Lid 13. Split mold 14. Body molding plane 15. Vacuum hole 16. Nested block 17. Vacuum channel 18. Pinch-off section 19. Blow jig P. Parison P1. Thin wall portion

PREFERRED EMBODIMENTS OF THE INVENTION

(11) This invention is further described with respect to preferred embodiments, now referring to the drawings.

(12) FIG. 1 is a front elevational view of the container in the first embodiment of this invention, with the right half shown in a vertical section. This container comprises a main container 1, which is a blow molded product made of a synthetic resin, and in-mold labels 7 clad around, and fixed to, outer surface of a body 4 of the main container 1. This main container 1 comprises the cylindrical body 4 in the shape of a straight cylinder, a bottom 6 dented slightly inward in a spherical arc to close the body 4, a shoulder 3 which is an inward step from upper end of the body 4, and a cylindrical neck 2 having a diameter shorter than that of the body 4 and also having a screw thread notched around the outer surface.

(13) In the first embodiment of this invention, the body 4 of the main container 1 is disposed between the shoulder 3 and the bottom 6, and comprises a thinnest wall portion 4a and other portions. The thinnest wall portion 4a is the first to come in contact with the body molding planes 14 of a split mold 13, which is a blow mold. For other wall portions having thicker wall, contact comes later, starting from areas closest to the thinnest wall portion 4a, and spreading to remote areas.

(14) The in-mold labels 7 to be fixed to an outer peripheral surface of this body 4 are made of a synthetic resin film in the same series of the synthetic resin used to mold the main container 1. These labels are fixed to the body 4 over the entire height range thereof, excluding the upper end portion connected to the shoulder 3 and the lower end portion connected to the bottom 6, and also in a manner extending around the body 4 over the whole circumferential length. The in-mold labels 7 are a combination of two in-mold labels having the same height and the same peripheral length.

(15) When the in-mold labels 7 comprising a pair of in-mold labels are fixed to the outer surface of the body 4, the two labels make an end-to-end contact at a butting edge portion 7a on one side, while on the other side, a slight gap 7b in the range of 0.5 to 1 mm is left between two vertical edges so that both edges face each other beyond this gap.

(16) Thus, the gap 7b is prepared between two vertical edges of the two in-mold labels 7 on the other side of the connection between two in-mold labels 7. This gap serves to prevent the vertical edges from being overlapped with each other. The circumferential length of the two in-mold labels 7 is set so as to have a length shorter than the counterpart of the body molding plane 14 (See FIG. 7) of the split mold 13 by a value corresponding to a maximum level (about 0.5 mm) of metrication error that is likely to occur. Though the gap 7b may remain, it ensures that the vertical edges of the in-mold labels 7 are protected against overlapping.

(17) If overlapping occurred between the two edges of the two in-mold labels 7 on one side of the connection, the edge portion on top of the other edge would tend to be peeled easily. Once this occurs, it is very likely that this peeling develops further until this in-mold label 7 would peel from the body 4.

(18) As illustrated by FIG. 1, the thinnest wall portion 4a is annularly formed in a middle part of the body 4 adjacent to the in-mold labels 7 as viewed in a height direction, the body 4 has an inner peripheral body surface with a wall thickness gradually growing thick toward upper and lower ends of the body 4 starting from the thinnest wall portion 4a to positions 4b, 4c of the body 4 fixed with the in-mold labels 7 that are adjacent to the top end 7c and the bottom end 7d of the in-mold labels 7, and the outer peripheral surface of the body 4 extends along one plane such that the outer peripheral surface is flat at a position of the body 4 adjacent to the in-mold labels 7 between the top end 7c and the bottom end 7d of the in-mold labels 7.

(19) FIG. 3 is an exploded perspective view of the container in the second embodiment of this invention, to which a cap 8 is to be fitted so that the container can be utilized as a caster to shake the contents out of the container. As shown in FIG. 4, the main container 1 has the same construction as the first embodiment, except that portions having the largest outer diameter are disposed at upper and lower ends of the body 4 and that peripheral raised ribs are disposed in those upper and lower portions so that upper and lower edges of the in-mold labels 7 can rest at the bases of these ribs.

(20) In this second embodiment, the container has a stable shape-retaining ability because the peripheral raised ribs 5 serve as reinforcing ribs. The peripheral raised ribs 5 have the largest outer diameter, as compared to other portions of the main container 1, and stabilize the container posture when many containers stand side by side. As a result, the containers can be handled in good conditions during storage or transportation. During the time when the containers are handled, the ribs protect the in-mold labels 7 fixed to outer surface of the body so that the labels 7 may not by accident come in contact with other containers or objects.

(21) The cap 8 is fitted to the container in the second embodiment of this invention so that the container is utilized as a caster. This cap 8 comprises a fitting cylinder 9 which is fitted around the neck 2 by screw engagement, a top plate 10 disposed at the upper end of the fitting cylinder 9 to close roughly a half of the upper opening, and a lid 12 in a semi-circular shape, which is connected to a straight edge of the top plate 10 on the opening side of the fitting cylinder 9 by way of a hinge in a swingable manner and is provided with a skirt segment hanging from the lid 12 along its semi-circular edge.

(22) The cap fitted to the main container 1 is not limited to the illustrated one for caster use, but any desired cap, such as an ordinary removable cap or a dischargeable cap, can be fitted.

(23) FIG. 5 shows the container in the third embodiment of this invention. In this embodiment, the in-mold labels are fixed to only a middle area of the body, in a position somewhat closer to the shoulder than to the bottom, but are under the same construction as in the first embodiment for other portions.

(24) In the case of the third embodiment, the thinnest wall portion 4a is in the position opposed to the in-mold labels 7. A combination of the main container 1 and the in-mold labels 7 creates a decorative effect on the container.

(25) FIG. 6 shows the container in the fourth embodiment of this invention, in which the in-mold labels 7 are fixed to the body 4, excluding the upper end portion connected to the shoulder 3 and the lower end portion connected to the bottom 6, but are disposed separately in an upper area and a lower area of the body 4 with no labeled area in between. Other than this configuration, the container has the same construction as the first embodiment.

(26) In this fourth embodiment, the thinnest wall portion 4a of the body 4 is disposed in a space between a portion opposed to upper in-mold labels 7 and a portion opposed to lower in-mold labels 7. Under this construction, the behavior of parison P (See FIG. 9) in the blow molding operation would have a uniform effect on the two pairs of in-mold labels 7. Since two pairs of upper and lower in-mold labels 7 are used to display the container, it is possible to make the container display fresh and varied.

(27) FIG. 7 is a vertical section of an important part of a pair of halves of the split mold 13 used to mold the container in the second embodiment of this invention. The split mold 13 has a pinch-off section 18 under the container cavity, and nested blocks 16 are combined with the split mold 13 and are used as the body molding planes 14. FIG. 8 is a development of a body molding plane. As shown, a slit-like endless vacuum hole 15 in a square shape is open along the four sides of each body molding plane. Vacuum channels 17 are also disposed in the split mold 13.

(28) Under this construction, the in-mold labels 7 can be held by vacuum in tight contact with the body molding planes 14 because the in-mold labels 7 are held in place by vacuum the labels 7 along their entire circumference. Since vacuum holes 15 are formed along the vertical edges of each body molding plane, the in-mold labels 7 are naturally held in place in a precisely positioned state.

(29) When the container is blow molded in the split mold 13 shown in FIG. 7, the in-mold labels 7 are positioned by means of a robot and the like in the open split mold 13, and are held in contact with the body molding planes 14 by vacuuming the body molding planes through the vacuum holes 15.

(30) The parison P is extrusion molded by an extruder (not shown) and is pinched by both halves of the split mold 13. Since an annular thin wall portion P1 has been molded in a part of the parison under the wall thickness control at the time of extrusion molding, the parison P is pinched at right timing when this thin wall portion P1 has come to face a desired position of the body molding planes 14 (See the parison in solid lines in FIG. 9).

(31) After the parison P has been pinched with both halves of the split mold 13 and cut off at the pinch-off section, a blow jig 19 is fitted to the split mold 13, and the pinched parison P is blow molded into the main container 1, following an ordinary blow molding procedure.

(32) When the parison P is blow molded into the main container 1, the thin wall portion P1 of the parison is the first to widen and expand, as shown by chain two-dashed lines, because P1 is easier to expand than the rest of the parison. Thus, the thin wall portion P1 quickly comes in contact with the in-mold labels 7 that are held in place, and is molded into the thinnest wall portion 4a of the body 4.

(33) As the blow molding of the parison P goes on in this state, portions of the parison P, other than the thin wall portion, come in contact with the in-mold labels 7, starting from the areas closest to the thin wall portion and spreading to remote areas, and are molded into other portions of the body 4.

(34) For the portions of the parison P that are molded into other portions of the body 4, contact with the in-mold labels 7 comes later, starting from the areas closest to the thin wall portion P1 and spreading to remote areas. Since at the time of contact, bulges of air trapped between the in-mold labels 7 and the parison P are pushed out, no bulge of air is formed between the in-mold labels 7 and the body 4 molded from the parison P.

(35) The in-mold labels 7 can be fixed to the body 4 of the blow molded container at the same time as the blow molding of the main container 1, by a thermal adhesion means utilizing the heat of parison P or by a pressure adhesion means utilizing a blow molding pressure.

(36) In the foregoing description of this invention, blow molding was used as an example. However, means of carrying out this invention is not limited to blow molding, but can be applied also to biaxial drawing and blow molding.