JPH0420728Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a heat-resistant container such as a bottle made of synthetic resin such as polyethylene terephthalate.

[Prior art] Containers such as free-standing bottles made by stretching a polyethylene terephthalate preform in the axial direction and molding it by air blowing have superior durability compared to blow-molded containers, but they require heating and filling. When used as a container for contents, it is necessary to heat treat it to prevent thermal deformation during filling.

[Problem to be solved by the invention] This heat treatment is for removing internal distortion during stretch blow molding, and is extremely effective for the body and bottom peripheral wall that have been sufficiently biaxially stretched. The effect is weak for bottom walls with insufficient parts,
In most cases, heat resistance is impaired due to thermal deformation of the bottom wall.

This improvement in the heat resistance of the bottom wall can be achieved by sufficiently biaxially stretching the bottom wall, but it is not possible to sufficiently stretch the bottom structure of the bottle to the center, where the stretching ratio is limited. It is difficult, and even if stretching is possible, in the case of a freestanding bottle, it must be strong enough to withstand the load of the contents.
When the bottom wall becomes thin due to stretching, the bottom wall, which is recessed in the bottom, swells outward under the load, impairing the self-supporting nature of the bottle.

Conventionally, ribs or the like have been provided to prevent the bottom wall from bulging due to thermal deformation, but this is still insufficient and further improvements are desired.

This invention was conceived in view of the above circumstances, and its purpose is to provide a synthetic resin container such as a bottle that has both heat resistance and rigidity.

[Means for Solving the Problems] The features of this invention for the above-mentioned purpose include a thin grounding periphery connected to the circumferential side wall integral with the fuselage, and a thick recess successively extending from the middle of the bottom center and the grounding periphery to the top. The bottom of the container is formed from the dome-shaped bottom wall inside the grounding periphery, which is bent inward and outward at regular intervals in the circumferential direction, so that the lower part of the thin bottom wall connected to the grounding periphery is A radial concave part and a convex part are formed in a flat manner by a bent part existing vertically with respect to the bottom surface, and the bottom wall is bent concentrically in three stages to form the above bent part and the bent part of each step part. A reinforcing portion is formed by the intersection with the top portion, and the thick portion of the top portion is formed into an extended protrusion projecting outward.

[Function] In the above structure, the surface area increases due to the bending of the bottom wall, and the stretching ratio of the bottom wall increases accordingly.
Furthermore, even if the lower part of the bottom wall is formed thin due to stretching, the rigidity is increased by reinforcement by the intersection of the radial bent portions in the vertical direction and the bent portions of each step, and thermal deformation of the top portion is further prevented by stretching.

[Example] In the figure, 1 is a bottle made of biaxially stretched polyethylene terephthalate molded using stretch blow molding. The bottom of the bottle body 1 has a thin grounding periphery 3 connected to the circumferential side wall 2 which is integral with the body and fully biaxially stretched, and a dome-shaped recess formed inside the grounding periphery 3. It is composed of a bottom wall 4.

Although the lower part of the bottom wall 4 in contact with the grounding periphery 3 is thinned by stretching, the wall thickness is gradually increased from the middle of the bottom center and the grounding periphery to the top.

The bottom wall 4 is bent inward and outward at regular intervals in the circumferential direction, excluding the top, and is formed into concave portions 4a and convex portions 4b that are alternately located radially.

In the upper part of the thick bottom wall, only the outer surface of the concave part 4a and the convex part 4b is flat, as shown in FIG. As shown in FIG. 4, a bent portion 4c is formed that extends vertically to the bottom surface, and the bent portion 4c partitions the whole into a flat section, and is supported by the bent portion 4c.
It is becoming difficult to bend. Further, the alternating flat cross-sectional shapes become narrower toward the top, and gradually change to the cross-sectional shapes shown in FIG. 3, and the rigidity is increased by the concave surface portions 4a and convex surface portions 4b.

Furthermore, the bottom wall 4 is bent in three concentric stages at regular intervals, and the bent portions 4d of each step are
The entire bottom wall except the top portion is reinforced by a reinforcing portion formed by the intersection of the curved portion 4c and the bent portion 4c. The thickest top portion of the bottom wall 4 is extended by extruding the central portion outward, and the extruded portion protrudes outward as a protrusion 5.

[Effects of the invention] As described above, this invention has a thin grounding edge 3 connected to the peripheral side wall 2 that is integral with the body, and a thick recess formed in sequence from the middle of the bottom center and the grounding edge to the top. The bottom of the container is formed from the dome-shaped bottom wall 4 inside the grounding periphery, and the bottom wall is bent inward and outward at regular intervals in the circumferential direction, so that the lower part of the thin bottom wall connected to the grounding periphery 3 forms the bottom. Since a radial concave surface portion 4a and a convex surface portion 4b are formed that are flatly divided by a bent portion 4c existing vertically, and the bottom wall 4 is bent concentrically in three steps, the surface area of the bottom wall 4 is increased. Stretching occurs by that amount, and heat resistance improves.

Furthermore, even if the lower part of the bottom wall 4 is sufficiently stretched and formed thin, the bent portion 4c existing vertically with respect to the bottom acts as reinforcement against bending, so the bending strength inside the ground contact periphery increases, It sufficiently withstands not only loads but also impact strength, and unlike in the past, the bottom wall 4 does not bulge out beyond the connection with the grounding periphery and lose its independence.

Furthermore, a reinforcing portion is formed in the bottom wall 4 by the intersection of the bent portion 4c and the bent portion 4d of each step, and the thick portion at the top is formed into a protrusion 5 extending outward. As a result, the reinforcement extends to the entire area and further improves the strength, and also improves the thermal deformation that tends to occur in unstretched tops and thick parts, and the weakness against impact forces when dropped, so that it can withstand temperatures of about 85℃. It has features such as being able to withstand heating and filling of the contents.

[Brief explanation of the drawing]

The drawings show the bottom structure of the heat-resistant synthetic resin container according to this invention. Fig. 1 is a vertical side view, Fig. 2 is a bottom view, Fig. 3 is a cross-sectional view taken along the line shown in Fig. 1, and Fig. 4. is a sectional view taken along the line in FIG. DESCRIPTION OF SYMBOLS 1... Bottle body, 2... Circumferential wall, 3... Grounded periphery, 4... Bottom wall, 4a... Concave surface part, 4b... Convex surface part, 4c... Bent part, 4d... Bent part of step part. , 5...protrusion.

Claims (1)

[Scope of utility model registration request] The bottom of the container is connected to a thin grounding periphery connected to the peripheral side wall that is integral with the body, and a dome-shaped bottom wall inside the grounding periphery, which is recessed from the middle of the bottom center and the grounding periphery to the top. A radial concave surface whose bottom wall is bent inward and outward at regular intervals in the circumferential direction, and the lower part of the thin bottom wall connected to the grounding periphery is flatly partitioned by a bent part that extends vertically with respect to the bottom surface. At the same time, the bottom wall is bent concentrically in three stages, a reinforcing part is formed by the intersection of the above-mentioned bent part and the bent part of each step, and the thick part at the top is formed into a convex part. A heat-resistant synthetic resin container characterized by being formed into an outwardly extending protrusion.