JP4489606B2 - Blow molding method for plastic bottles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a portable plastic bottle that contains drinking water such as mineral water and that is used as a drinking water supply tank by installing the drinking water on a support base with a cock, and particularly relates to a blow molding method for the plastic bottle. It is.

In general, this type of plastic bottle is as shown in FIGS. 1 and 2, reference numeral 1 denotes a plastic bottle (gallon bottle) in which a resin such as polycarbonate is blow-molded. A small-diameter mouth 3 is formed at the upper end of a hexagonal barrel 2 having a capacity of about 12 liters. A recess 2a that is recessed in the axial direction is formed on one side of the body 2, and a rod-like handle 4 is integrally fixed to the outer end of the recess 2a.

The plastic bottle is provided with a primary molded product with a small diameter molded into a bottomed cylindrical shape, the mouth of the primary molded product is connected to the air blowing part of the mold, and the entire area excluding the mouth of the primary molded product is molded. After heating to a temperature, the outer peripheral portion of the primary molded product is surrounded by a molding portion of the mold, and a rod-like handle 4 is arranged on one side of the primary molded product corresponding to the handle portion, and then the air blowing portion Compressed air is supplied to expand the outer peripheral portion of the primary molded product along the inner surface of the molding portion of the mold, and as shown in FIGS. 1 and 2, the handle 4 is implanted (fixed) on the upper and lower walls of the recess 2a. A plastic bottle 1 (gallon bottle) is obtained.

As shown in FIG. 9, the conventional plastic bottle 1 has upper and lower walls of the recess 2 a, that is, the handle holding portions 2 b and 2 b extend larger than other peripheral walls, and the handle holding portions 2 b and 2 b Since the end portion is wrapped and held, the thickness of the grip holding portions 2b and 2b is reduced, and the strength is lowered. For this reason, when the conventional plastic bottle 1 contains drinking water and carries the handle 4, cracks are likely to occur in the handle holding portions 2 b and 2 b, and the durability is poor.

By the way, there has been Patent Document 1 as a means for forming a reinforcing thick portion on the peripheral wall of a plastic bottle. That is, the part corresponding to the body part after molding of the parison (preform) before inserting the mold is formed into a streak that is divided in the horizontal direction in a range higher than the mold temperature at the time of stretch blow molding. The temperature is adjusted so as to have a portion, the parison is inserted into a mold having a smooth surface, and then blown by blowing compressed air, thereby setting the low-temperature portion on the inner surface of the bottle. There was a thing which made it thicker than the part set to the high temperature part.

In the above-mentioned Patent Document 1, a mold into which a parison is inserted is divided into a large number of upper and lower parts (axial direction), and the temperature of each divided mold (temperature control block) is adjusted to form a high temperature part and a low temperature part. Therefore, it is difficult to adapt to molding a deformed plastic bottle having a recess recessed in the axial direction on one side and a handle in the recess.
JP-A-5-84813

The present invention provides a novel plastic bottle blow molding method capable of molding a durable plastic bottle even if it has a concave portion recessed in the axial direction on one side and a deformed shape having a handle in the concave portion. With the goal.

The present invention is configured as follows to achieve the above object. That is, the invention according to claim 1 is provided with a primary molded product molded into a bottomed cylindrical shape, and the mouth of the primary molded product is connected to an air blowing portion of a mold, and the mouth of the primary molded product is After the whole area is heated to the molding temperature, the cooling body is brought into contact with the peripheral wall of the primary molded product that becomes the grip holding part of the product, the peripheral wall is lowered in temperature by a predetermined amount, and the concave part is projected in the axial direction to one side. And a peripheral wall of a primary molded product in which the concave mold part is fitted to the primary molded product, and the concave molded part is lowered in temperature. The first molded product is inflated by facing each other and then supplying compressed air from the air blowing section.
According to the second aspect of the present invention, when the compressed air is supplied to inflate the primary molded product, the axially projecting end portion of the concave molding portion of the molding die is heated.

When the cooling body is brought into contact with the peripheral wall serving as the grip holding portion of the primary molded product heated to the molding temperature, the temperature of the peripheral wall decreases locally, and the stretchability of this portion is lower than that of other portions. In this state, when the primary molded product is surrounded by the mold of the mold and the concave molding portion is faced to the peripheral wall of the primary molded product with the temperature lowered, and the primary molded product is expanded, the primary molded product is The extension of the peripheral wall corresponding to the handle holding portion is delayed more than other portions, and thinning is prevented. As a result, the molded plastic bottle has a handle holding portion having a predetermined thickness, and a sufficient strength against the handle load is ensured.
In addition, when the primary molded product is inflated, the axially protruding end portion of the concave molding portion of the mold is heated, so that the peripheral wall of the primary molded product corresponding to this portion is smoothly stretched and molded. Sometimes, the material corresponding to both ends of the handle is not drawn, and the thickness of the handle holding portion is stably secured to a predetermined thickness.

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view of a plastic bottle targeted by the present invention, FIG. 2 is a plan view of FIG. 1, FIGS. 3 to 7 show molding steps of the plastic bottle according to the present invention, and FIG. 3 is a primary molded product. 4 is a side view of a state where the primary molded product is connected to the air blowing portion of the mold, FIG. 5 is a side view showing a heating state of the primary molded product, and FIG. 6 is a cooling body on the heated primary molded product. FIG. 7 is a side cross-sectional view showing a blow-molded state of the primary molded product.

In FIG. 3, reference numeral 10 denotes a primary molded product, which is formed by injection molding a thermoplastic resin such as polycarbonate to form an elongated bottomed cylindrical shape, and the outer diameter of the mouth portion 10b is small in a step shape with respect to the body portion 10a. In addition, an annular rib 10c for reinforcement is formed on the outer periphery thereof.

The primary molded product 10 is inverted and its mouth portion 10 b is connected to the air blowing portion 13 of the mold 12 as shown in FIG. 4. Next, as shown in FIG. 5, the bottomed cylindrical heating pot 14 in which a heater is installed is placed on the primary molded product 10, and the heating pot 14 is energized to form the body 10 a of the primary molded product 10 at a molding temperature, In this example, heating is performed at 280 ° C to 350 ° C.

Next, after the heating pot 14 is detached from the primary molded product 10, as shown in FIG. 6, the cooling body 15 is brought into contact with the peripheral wall 10 d of the primary molded product 10 serving as a handle holding portion of the product, and the peripheral wall 10 d is The temperature is lowered by a predetermined amount, in this example, 50 ° C. to 60 ° C.

Next, the molding die 16 is fitted to the primary molded product 10 to surround the outer periphery thereof. The mold 16 is a split mold that can be divided into two parts with respect to a vertical plane, and has a concave molding part 16a that protrudes in the axial direction (rightward) at the upper and lower intermediate parts in FIG. A heater 17 for heating is housed in the axially protruding end portion (right end portion) of 16a. A rod-like handle 4 is erected up and down at the base of the recess forming portion 16a to be detachably locked. The handle 4 is locked by a split mating surface portion of the mold 16, and its upper and lower ends project a predetermined amount upward and downward from the recess molding portion 16a.

In this state, the heater 17 is energized to heat the axially projecting end portion of the recessed portion molding portion 16a, and the compressed air is supplied from the air blowing portion 13 into the primary molded product 10 so that the primary molded product 10 is illustrated. 7 swells (transfers) along the shape of the inner surface of the mold 16 to obtain a plastic bottle 1 as shown in FIGS.

According to the above embodiment, since the peripheral wall 10d serving as the grip holding portion of the primary molded product 10 heated to the molding temperature is locally lowered, and then the primary molded product 10 is expanded to the product shape. When it expands, the stretchability of this part will be lower than that of other parts, and the molded plastic bottle 1 has a grip holding part 2b, 2b that wraps the upper and lower ends of the handle 4, as shown in FIG. The wall thickness is ensured to a predetermined thickness, and can sufficiently withstand the load of the handle 4. Further, when the primary molded product 10 is inflated, the axially projecting end of the concave molding portion 16a of the molding die 16 is heated by the heater 17, so that the peripheral wall of the primary molded product 10 corresponding to this portion is formed. It extends smoothly, and the thickness of the bottom wall of this portion, that is, the concave portion 2a of the product does not become thicker than necessary, and the material that wraps both ends of the handle 4 at the time of molding is not pulled, and the handle holding portion 2b, The thickness of 2b is stably secured to a predetermined thickness.

It is a side view of the plastic bottle which this invention makes object. It is a top view of FIG. It is a side view of a primary molded product. It is a side view of the state which connected the primary molded product to the air blowing part of a metal mold | die. It is a side view which shows the heating state of a primary molded product. It is a side view of the state which made the cooling body contact the heated primary molded product. It is side surface sectional drawing which shows the blow molding state of a primary molded product. It is sectional drawing of the handle part of the plastic bottle by this invention. It is sectional drawing of the plastic bottle by the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plastic bottle 2 trunk | drum 2a recessed part 2b handle holding part 3 mouth part 4 handle 10 primary molded product 10a trunk | drum 10b mouth part 10c annular rib 10d peripheral wall 12 of the primary molded product used as a handle holding part die 13 air blowing part 14 heating Pot 15 Cooling body 16 Mold 16a Recessed portion 17 Heater

Claims (1)

Primary molded product with a bottomed cylindrical shape (
1 0), the mouth part (1 0 b) of the primary molded product (1 0) is connected to the air blowing part (1 3) of the mold, and the mouth part (1 0) of the primary molded product (1 0) 0 b
) Is heated to the molding temperature, and then the cooling body (15) is brought into contact with the peripheral wall (10d) of the primary molded product (10) that becomes the grip holding portion (2b) of the product. Wall (
1 0 d) was dropped by a predetermined amount, and a concave formed part (16 a) projecting in the axial direction on one side and a rod-shaped handle (4) were arranged at the base of the concave formed part (1 6 a) Mold (
1 6), the mold (1 6) is fitted into the primary molded product (1 0), and the concave molded portion (1 6 a) is lowered in temperature to form a primary molded product (
1 0) facing the peripheral wall, and then supplying compressed air from the air blowing portion (1 3) to inflate the primary molded product (10). Further, the air blowing portion (
When the compressed air is supplied from 1 3) to inflate the primary molded product (10), the axially projecting end portion of the recessed molding portion (1 6 a) of the mold (1 6) is heated. A blow molding method for plastic bottles.

Images