JPH07257534A - Bottlelike container and its production method - Google Patents

Abstract

PURPOSE:To provide a bottlelike container which can be broken after use and disposed by providing a specified shock-resistant and pressure-resistant properties and an extremely small strength against pressing. CONSTITUTION:A parison 10 adjusted in a heating pot so that the surface of the long cylindrical part 15 of the parison 10 is higher than the melting point of PET in the temperature and the inner surface is lower than the transfer temperature to glass is set in the cavity 36 of a metallic mold 28-31 for blow molding. And the external surface is heated to a temperature higher than the melting point while cooling the inside of parison 10 and blow-molded so that the mean elongation rate becomes 10 times or more. A bottle-form vessel molded with PET resin in such a way has 0.25mm or thinner at the body thickness and the strength against pressing is less than 3.0kg. Since the bottle can be easily pressed and broken and folded due to such a low pressing strength, the bottle volume can be reduced and handling volume of trash can be decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottle-shaped container and its manufacturing method, and more particularly to polyethylene terephthalate (PE).
The present invention relates to a bottle-shaped container in which a parison made of an injection-molded article of T) is blow-molded and a method for manufacturing the same.

[0002]

2. Description of the Related Art Stretched bottles made of PET are transparent,
It has excellent impact resistance, hygiene, moderate gas barrier properties such as oxygen and carbon dioxide gas, and pressure resistance. For this reason, it is widely used in packaging containers for various foods, beverages, detergents, cosmetics, etc. .

When manufacturing a hollow bottle-shaped container made of PET, a bottomed cylindrical parison is preformed with PET resin, and this parison is biaxially stretch blow molded to crystallize the resin material. The pressure resistance and the transparency are imparted to the blow-molded bottle-shaped container by generating the property.

On the other hand, in another method for forming a PET hollow bottle, a PET bottle molten parison is enclosed in a predetermined mold and directly blow-molded to have rigidity and a transparent bottle-shaped container. Trying to get.

Since the latter method is blow-molded directly from the molten state as compared with the former method, the orientation of the resin is poor, the crystallinity is low, and the breaking strength is weak. In order to impart the same to the above, the wall thickness must be greater than or equal to a predetermined value, which increases the amount of raw material used and causes a problem in resource saving. For this reason, bottle-shaped containers made of PET resin by the former method have been widely used.

[0006]

A bottle-shaped container made of PET resin is widely used as a filling container for foods, detergents, cosmetics, etc. as described above because of its excellent properties, high productivity and economical efficiency. ing. From the viewpoint of impact resistance and pressure resistance, the wall thickness of the bottle is generally 0.25 mm or more, and the ratio of the internal capacity to the bottle weight is 30 ml / g or less. Therefore, it cannot be easily crushed and deformed, and it cannot be crushed compactly and discarded. For this reason, it is difficult to reduce the volume in the waste disposal and the resource recovery after the container is used, and there is a problem that the amount of waste to be processed is large.

The present invention has been made in view of the above problems, and it is particularly easy to reduce the volume at the time of discarding after use, thereby reducing the amount of waste to be treated. An object of the present invention is to provide a container and a manufacturing method thereof.

[0008]

Means and Actions for Solving the Problems An outline of a bottle-shaped container and a method for manufacturing the same according to the present invention will be described. First, a bottomed parison is formed by injection molding. Then, the parison thus obtained is heated in a heating pot at a high temperature for a certain period of time in the next step, and then subjected to high pressure blow molding to form a bottle-shaped container.

In a general pressure resistant PET bottle,
The bottomed parison obtained by injection molding is completely cooled and solidified, or at least its surface temperature is lowered to 50 ° C. or lower to be solidified by cooling, and in the heating pot, the temperature is adjusted to 80 to 110 ° C. as a proper temperature for stretching. After temperature control, blow molding is performed.

On the other hand, in the production of the bottle-like container made of the thin PET resin of the present invention, the cooling and solidification state of the bottomed parison is not deformed from the injection molding die in consideration of energy saving in the process. It is preferably cooled and solidified to such an extent that it can be released within the range. Although the temperature varies depending on the shape, it is preferably in the range of 80 to 110 ° C. Further, in order to further heat the outer surface of the parison in the heating pot to a high temperature, the inner surface of the heating pot is heated to the melting point of the resin or higher, preferably 290 ° C. or higher, while the inner surface of the parison is in a heat radiation state. This creates a temperature gradient between high and low temperatures on the outer and inner surfaces of the parison, and at least keeps the inner surface of the parison below the melting point, blow-molds it toward the inner wall of the mold, It is drawn at a high speed and solidified.

Generally, the surface area A ₀ and the thickness t ₀ of the body portion 15 of the parison 10 at the diameter D between the wall thickness centers of the parison 10 as shown in FIG. 1 and the mold as shown in FIG. 5 or 8. Bottle-shaped container 4 with biaxially stretched solidified inner wall
Between the surface area of 0.43 and its surface thickness t, when the volume of the resin is assumed essentially unchanged by blow molding, A ₀ t ₀ = At, and the simplest of average stretching ratio R _a R _a = A / A ₀ , or R _a =
It becomes t ₀ / t.

The bottle-like container made of the thin PET resin according to the present invention is made of another material, for example, a corrugated cardboard case as an exterior body, from the viewpoint of resource saving. The container itself is supplemented with paper or a paper container so that the container itself does not have unnecessarily high rigidity and pressure resistance. This makes it possible to easily separate and collect and reuse after use, and to crush and fold the container at the time of disposal.

In order to impart such characteristics, PET
The average thickness of the portion of the body of the bottle-like container made of resin is lower than 0.25mm, yet to obtain a self-supporting container, the average stretching ratio R _a is preferably within a range of 10 to 25, the average The thickness is preferably in the range of 0.10 to 0.25 mm.

In a self-supporting bottle-shaped container, when the average wall thickness is 0.10 mm or less and the average stretching ratio _Ra is 25 or more, molding exceeding the tensile strength of the PET resin during stretching is possible. It is done, which makes molding very difficult.

The bottle-shaped container of the present invention molded by such a draw ratio has an excellent oxygen barrier property,
The average wall thickness is 0.10 to 0.25 mm, compared with that of a bottle-shaped container of PET resin of 0.25 mm or more.
However, the gas barrier property at 40 ° C is 30 ml / m
The value is less than ² · day · atm.

To measure the stretched crystallinity of the blow-molded product, the density of that portion is measured and converted according to the following formula. Crystallinity (%) = {1.455 × (D-1.355) /
D * (1.455-1.335)} * 100 (%) However, D represents a density (measured value).

In the container of the present invention, its crystallinity is 50% or less, and that of the stretched portion shows a value of 20 to 40%. If the crystallinity exceeds 50%, the impact resistance deteriorates and cracking may occur when dropped.

The most remarkable feature of the container according to the present invention is that
The thickness of the body portion stretched to an average magnification of 10 times or more is 0.25 mm or less, and the crushing strength is 3.5 k.
g or less, and more preferably 2.5 kg or less. With such a low crushing strength, it is possible to crush and fold easily after use. In this case, pinholes do not occur due to the biaxially oriented orientation in which the protrusions and ridges are high when bent,
It is to withstand vibration during transportation.

[0019]

The present invention will be described below in the order of its manufacture according to the illustrated embodiments. FIG. 1 shows a parison 10 formed by injection molding of PET resin. This parison 1
The upper end of 0 is composed of a mouth / neck portion 11. A male screw 12 that is screwed to a cap is formed on the outer peripheral portion of the mouth / neck portion 11, and the lower end of the mouth / neck portion 11 is composed of a neck ring 13. And this neck ring 13
The lower end side of the long cylindrical portion 15 is
The lower end of the parison 10 is composed of a bottom portion 16, and the bottom portion of the parison 10 is closed by the bottom portion 16.

The thermoplastic polyester resin used when molding the parison 10 shown in FIG. 1 is a polyethylene terephthalate (PET) or a copolyester mainly composed of ethylene terephthalate units and other known modifying ester units. May be used as long as it has a molecular weight capable of forming a film. The conditions for plasticization and injection conditions of the parison 10 by injection molding may be those conventionally known.

Such a parison is introduced into the heating pot 20 shown in FIG. 2 for heating to a high temperature, and heating is performed. The heating pot 20 has a lip cavity 2 at its upper end.
1, the lip cavity 21 holds the parison 10. And the heating pot 20
A heater 22 is embedded therein, and a recess 23 for receiving the parison 10 is formed in the center thereof. A space 24 is formed between the parison 10 and the inner surface of the recess 23 when it is introduced into the recess 23. Instead of the heater 23, it is also possible to heat by high frequency heating from the outside.

The parison 1 introduced into the heating pot 20.
0 is heated through a gap 24 between the pot 20 and the recess 23. The void 24 is the long cylindrical portion 15 of the parison 10.
The surface may be in a range where it does not contact the inner surface of the recess 23 of the heating pot 20.

In order to carry out the biaxial high stretch blow molding according to the present embodiment, the inner surface of the heating pot 20 is maintained at a temperature higher than the melting point of the PET resin and actually 280 to 330 ° C. Then, the long tubular portion 15 of the parison 10 is put in the heating pot 20 while being held by the lip cavity 21 for 7 to 13 seconds.

On the other hand, the inner surface of the long cylindrical portion 15 of the parison 10 has a glass transition point higher than that of the PET resin and a PE
To maintain below the melting point of T, the lip cavity 21
Open the upper part of the to dissipate heat. This is parison 1
A temperature gradient is generated between the inner surface and the outer surface of the long tubular portion 15 of zero.

The parison 10 thus heated is introduced into the blow molding die shown in FIG. This mold includes a left mold 28, a right mold 29, a bottom mold 30,
The upper die 31 and the upper die 31 form a predetermined cavity 36. The parison 10 heated by the upper mold 31 is introduced into the mold. Then, the mandrel 32 having the drawing rod 33 is inserted from the mouth of the upper die 31. The stretching rod 33 is movable in the vertical direction. A blowing fluid passage 34 is provided between the stretching rod 33 and the mandrel 32.

A cooling passage 35 is formed in advance in each of the molds 28 to 31 to obtain a desired mold temperature.
The temperature is adjusted by passing the cooling medium through this. The left and right dies 28, 2
9 is opened and closed in the horizontal direction, and the die 30 at the bottom is moved in the vertical direction.

In the biaxial high stretch blow molding method of this embodiment, the long cylindrical portion 15 of the parison 10 is heated by the heating pot 20.
The surface of the parison 10 whose melting point temperature is higher than that of PET and the inner surface of which is adjusted to the glass transition temperature or lower is the cavity 36 of the blow molding dies 28 to 31 which is adjusted to the glass transition temperature of the PET resin or lower. Set inside. While extending the axial direction while applying the tip of the extension rod 33 to the inside of the bottom 16 of the long tubular portion 15 of the parison 10, the long tubular portion 15 of the parison 10 is passed through the fluid passage 34 at the same time.
Low pressure compressed air is blown into the interior of the parison 10 at the same time when the stretching rod 33 reaches the lowest point, and at the same time high pressure secondary compressed air is supplied into the parison 10 through the fluid passage 34 as well. 15 is expanded and stretched to the outer peripheral side in the radial direction.

In this way, a substantially rectangular molded product as shown in FIGS. 4 to 6 or a circular molded product as shown in FIGS. 7 to 9 is obtained. The shapes of such molded products 40 and 43 depend on the shape of the cavity 36 of the molds 28 to 31.

In such biaxial high stretch blow molding, the primary compressed air is, for example, 10 kgf / cm ² , and the secondary compressed air is blown within 1 second after the primary compressed air is blown. air pressure 20 kgf / cm ² or more, preferably, from 25~30kgf / cm ^2.

The switching of such compressed air pressure and its timing are preset. The primary compressed air prevents vertical movement of the stretching rod 33, that is, contact between the stretching rod 33 and the bottom portion 16 of the long tubular portion 15 of the parison 10 during longitudinal stretching. In addition, before the start of the radially outer peripheral side expansion by the secondary compressed air, the formation of a skin layer on the inner surface of the long tubular portion 15 of the parison 10 is promoted, and the secondary compressed air radial outer peripheral side is formed. Promotes high stretching. However, it is necessary to adjust the amount of the primary compressed air so that the eccentricity of the vertical extension of the parison 10 does not occur. In addition, the drawing rod 33
It is preferable that the stretching in the longitudinal direction by (2) is a value twice or more the original length H ₀ of the long tubular portion 15 shown in FIG.

The high stretch blow molding according to the present invention is shown in FIG.
The surface area A ₀ of the center of the thickness t ₀ of the long tubular portion 15 of the parison 10 shown, stretched molded excluding neck 11 of Figure 5 or bottle-like container 40, 43 is formed is shown in FIG. 8 and the surface area a of the container, between its average wall thickness t _a, PET
When the volume change of the resin is ignored in the blow molding process, A ₀ × t ₀ = A × t, and as _a simple expression of the average draw ratio Ra, _Ra = A / A ₀ = t ₀ / a t _a. In such a definition, a bottle-shaped container according to the present embodiment, the average stretching ratio R _a is 10 or more.

Next, a bottle-shaped container made of PET resin having a capacity of 5000 ml and a shape shown in FIGS. 4 to 6 was blow-molded. Specific examples are shown in the following table.

[Table 1] The inner buckling strength of the data shown in the above table was measured as shown in FIG. That is, the molded bottle-shaped container 40 is placed on the test stand 18, and the pressing plate 49 is attached to the pressing head 5.
No. 0 compresses at a speed of 300 mm / min, and the compression strength is measured by a strograph.

The bottle-shaped container made of the PET resin molded in this manner has an average draw ratio of 10 or more as defined above, and an average thickness of stretch blow-molded molded articles of 0.25 mm or less. The crystallinity is 50% or less, which is a self-supporting container, which can be easily folded and has a small weight of P while maintaining the excellent properties of PET resin.
ET can be used to form large volume containers. This makes it possible to provide a useful resource-saving packaging container. Therefore, its application is extremely useful as an adhesive for various industrial purposes as well as a packaging container for chemicals, in addition to food and drink, seasonings, detergents, cosmetics.

[0034]

The first aspect of the present invention relates to a bottle-shaped container having a body portion having a wall thickness of 0.25 mm or less and a crushing strength of 3.0 kg or less. Therefore, according to such a container, the container can be easily crushed, and thereby the volume of the container can be reduced. In particular, the volume can be reduced when the used container is disposed of, and the amount of waste treated can be greatly reduced.

A second aspect of the invention is such that while the inside of the parison is allowed to cool, the outer surface is heated to a temperature above its melting point and blow molded at an average draw ratio of 10 or more. Therefore, it becomes possible to provide a bottle-shaped container having low crushing strength and having desired impact resistance and pressure resistance.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a parison for molding a bottle-shaped container.

FIG. 2 is a vertical sectional view of a heating pot for heating a parison.

FIG. 3 is a cross-sectional view of a blow molding die.

FIG. 4 is a plan view of a blow-molded bottle-shaped container.

FIG. 5 is a vertical sectional view of the container.

FIG. 6 is a bottom view of the same container.

FIG. 7 is a plan view of another blow-molded bottle-shaped container.

FIG. 8 is a vertical sectional view of the container.

FIG. 9 is a bottom view of the same container.

FIG. 10 is a front view showing an apparatus for measuring buckling strength.

[Explanation of symbols]

 10 Parison 11 Mouth and neck part 12 Male screw 13 Neck ring 15 Long tube part 16 Bottom part 20 Heating pot 21 Lip cavity 22 Heater 23 Recessed part 24 Gap 28 Mold (left) 29 Mold (right) 30 Mold (bottom) 31 Mold (Upper) 32 Mandrel 33 Stretching rod 34 Blow molding passage 35 Cooling passage 36 Cavity 40 Bottle-shaped container 41 Thick part (center of bottom) 43 Bottle-shaped container 44 Thick part (center of bottom) 48 Test stand 49 Pressing Board 50 pressure head

Claims (2)

[Claims] 1. A bottle-shaped container obtained by blow-molding a parison made of polyethylene terephthalate injection-molded body, wherein the thickness of the body portion is 0.25 mm or less and the crushing strength is 3.0 kg or less. A bottle-shaped container characterized by being present. 2. A parison is formed by injection molding with polyethylene terephthalate, and while the inside of the parison is allowed to cool, the outer surface of the parison is heated to a temperature equal to or higher than the melting point, and blow molding is performed so that the average draw ratio is 10 times or more. A method for manufacturing a bottle-shaped container.