JPH0444945A - Di negative pressure can body - Google Patents

Abstract

PURPOSE:To obtain a DI negative pressure can body which can be used for non- carbonic acid drink without depending only on a nitrogen sealing method and a side wall bead processing method by forming a DI can made of a plate material into a shape which is resistant to a determined internal pressure inside the can and wherein a can bottom is deformed toward inside the can when the internal pressure of the can is a specific value. CONSTITUTION:When a can is hot-filled with non-carbonic acid drink such as juice and subjected to retort treatment, an internal pressure inside the can is approximately 3 kg/cm<2>, so that the can body need be resistant to this internal pressure. When the can is cooled to a room temperature, the internal pressure is less than 1kg/cm<2>. The can is formed in a shape that a can bottom is inverted toward inside the can at this time. Thus a negative pressure in the can is changed to a positive pressure to prevent a side wall from being recessed. In addition by regulating the inversion of the bottom to have contents reduced by 8 to 15ml, the internal pressure in the can can be kept at approximately 1.5kg/cm<2>. The above requirement is such that approximately 0.16mm of a side wall thickness is a lower limit, while the side wall thickness is 0.12 to 0.16mm in the case of thinning the can, and recesses and protrusions with sine curves of a pitch of 2 to 5mm are provided. A region comprising the recesses and protrusions is a half or higher of a height of the can.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a DI can body for non-carbonated beverages such as fruit juice and coffee. This relates to a negative pressure can body for non-carbonated water with a pressure (less than 1 kg/cm").

(Prior Art) Beverages filled in cans include carbonated drinks such as beer and cola, and non-carbonated drinks such as fruit juice and coffee.

Since the former contains carbon dioxide gas, DI cans (aluminum or steel ml) with thin can side walls are used as containers, which do not cause dents in the can side walls and feature a lightweight mortar.

On the other hand, the latter does not contain carbon dioxide gas and is filled hot (approximately 90°C), so at room temperature there is a negative pressure (e.g. 0.4k
g/cm+"). For this reason, a three-piece steel can with high rigidity on the can side wall is used as a container.

There are two types of containers mentioned above (two-piece DI cans and three-piece steel cans), and DI cans are manufactured from a plate by drawing and ironing (DI) processing.

Additionally, three-piece cans are manufactured by welding or gluing plates together. These cans have different side wall thicknesses due to differences in their processing methods, such as 0.11 to 0.13mm for the DI can method, and around Q.2rsrm for the 3-piece can method, resulting in a large difference in the weight of each can. However, the DI processing method is advantageous in terms of cost.

(Problems to be Solved by the Invention) In recent years, with the advancement of nitrogen filling technology, DI cans have begun to be used as containers for non-carbonated beverages as well. This technology uses positive pressure (1 kg) inside the can by filling it with nitrogen.
/c+++2 or higher), and can prevent dents in the side wall of the can. This method has primarily been used for sports drink cans, but recently it has been used for other contents (
For example, oolong tea) is also being put to practical use.

However, there are difficulties in terms of equipment and technology to adopt this nitrogen filling technology.
It is hoped that I cans will be adopted.

Due to these circumstances, development other than nitrogen encapsulation technology has been progressing. For example, there is a method of adding beads to the side wall of the can to increase the rigidity of the side wall (Japanese Patent Publications No. 54-14552, 54-14553, JP-A-63-125149, etc.).
.

As mentioned above, there are two methods for adopting DI cans for non-carbonated beverages, namely the nitrogen filling method and the side wall bead processing method. However, it is currently difficult to employ nitrogen filling technology, and the side wall bead processing method has a problem in that coating defects occur on the side wall surface of the can.

It is an object of the present invention to solve the problems of the prior art described above and to provide a DI negative pressure can body that can be used for non-carbonated beverages without relying solely on the nitrogen filling method or side wall bead processing method. It is.

(Means for Solving the Problems) In order to solve the above problems, the present inventor conducted various basic studies. As a result, we obtained the following knowledge.

(1) When a DI can is hot-filled with contents and cooled to room temperature, dents occur preferentially on the side wall of the can. However, if the can side walls are thickened, the can bottom will deform inward. However, in this case, it is necessary to make the side wall of the can considerably thicker, and in the case of an aluminum can, the side wall thickness is 0.25 ml or more.

(2) If the shape of the can bottom is made easily deformable, the can bottom will be preferentially deformed during room temperature cooling after hot filling, and no dents will be formed on the side wall. However, if you touch the side wall with your hand, the can will deform as the contents move.

(3) If the amount of deformation of the can bottom (change in contents) is made permanent and controlled within a certain range, the side wall of the can is rigid even if you touch it with your hand, so you can use normal DI cans (carbonated (for beverages).

Based on the above findings, we conducted more detailed experimental research to develop a DI negative pressure can body that deforms the bottom of a can inward, and the present invention (
This invention is based on the present invention 1). This DI negative pressure can body is
Compared to the two conventional methods for employing DI cans, this method is ideal in that it does not require nitrogen filling.

However, since the can side wall thickness is thick, which is disadvantageous in terms of the cost of the can, intensive research has been carried out to make the can side wall even thinner. As a result, we were able to obtain the following knowledge.

(4) When the can side wall is made thinner, when hot filling is performed and the can is cooled to room temperature, the side wall of one can preferentially forms a dent. However, if the can side wall is provided with appropriate irregularities, dents are less likely to occur even when the can side wall is made thinner, and the can bottom is deformed inward.

(5) Furthermore, if the shape of the can bottom is made easily deformable as in the first aspect of the invention, the can bottom will preferentially be easily deformed during room temperature cooling after hot filling, and no dents will occur in the side wall. Therefore, the can side wall can be made thinner.

(6) If the amount of deformation (change in internal volume) of the can bottom is made permanent and controlled within a certain range, the side wall of the can will remain rigid even if you touch it with your hand, so you can use regular DI cans (carbonated cans). (for beverages).

Based on the above new findings, the present invention (present invention 2), which can reduce the thickness of the side wall of a can, has been made.

In other words, the DI negative pressure can body according to the first aspect of the present invention has a can bottom shape that can withstand an internal pressure of 3 kg/crn'', and when the can internal pressure becomes less than 1 kg/cm'', the can bottom moves inside the can. It deforms and the internal pressure of the can becomes positive pressure (1kg/cn+2
The shape of the can bottom is such that it can withstand an internal pressure of 3 k/cm2, and when the internal pressure of the can becomes less than 1 kg/cm2, the can bottom deforms inside the can. By reducing the internal volume of the can by 8 to 15 m12, the internal pressure of the can becomes positive (1 kg/cm” or more).
It is characterized by having a shape that becomes .

Further, the DI negative pressure can body according to the second invention has a pressure of 0.12 to 0.
16+1111 thick can wall with sine curve pitch 2-5
In addition to forming unevenness with a depth of 0.20 to 0.70 mm, the shape of the can bottom has an internal pressure of 3 kg /
cm” and can withstand pressure of 1 kg/c+*”
The can bottom is deformed to the inside of the can when the pressure becomes less than 1 kg/cm2. Pitch 2~5+am with sine curve, depth 0.20~
The unevenness of 0.70+++m is formed over 1/2 or more of the can height, and the shape of the bottom of one can can withstand an internal pressure of 3 kg/c+*, and the internal pressure of the can is 1 kg.
/cm, the bottom of the can deforms into the inside of the can,
It is characterized by having a shape in which the internal volume of the can is reduced by 8 to 15 IIQ, so that the internal pressure becomes positive (1 kg/cm2 or more).

The present invention will be explained in more detail below.

(Function) Non-carbonated beverages such as fruit juice and coffee are hot filled (90℃)
After that, retort treatment (120° C.) may be performed as a sterilization treatment. In this case, the internal pressure of the can becomes approximately 3 kg/cm'' due to the increase in liquid and temperature. Therefore, the can body must be able to withstand this internal pressure.

Furthermore, during cooling to room temperature, the internal pressure of one can gradually decreases to negative pressure (1 kg/cJ ~ 1lII). What is important at this time is the deformation of the can bottom when the pressure changes to negative. In the present invention, the change in the bottom of the can at the moment of negative pressure (
The shape of the can bottom is such that the bottom of the can is inverted to the inside of the can. By having such a can bottom shape, negative pressure within the can can be converted to positive pressure, and denting of the can side wall can be prevented. For example, as illustrated in FIG. 1, such a can bottom shape bulges out in a concave shape continuously from the center of the can bottom toward both ends, and protrudes like a leg near both ends of the can bottom. One example is a so-called caldera-like shape. Needless to say, other shapes are within the scope of the present invention as long as they allow the bottom of one can to be turned over to the inside of the can.

Furthermore, during cooling to room temperature, the internal pressure decreases and the temperature decreases to 1k.
When the pressure becomes negative from around g/cm2, a dent appears when the side wall of the can is touched by hand. Therefore, it is important to maintain a constant positive pressure inside the can even after cooling to room temperature. In the present invention, the inversion of the can bottom into the can is controlled by the amount of decrease in the internal volume.

The internal pressure of the can is about 1.5 kg/c+*''. If the amount of decrease in the content of the can is less than 8 m12, the internal pressure of the can cannot be maintained at 1.5 kg/cm2, and
If it exceeds 15 rmQ, the negative pressure required to turn the can bottom into the can becomes large, and it becomes difficult to turn the can bottom once the negative pressure is reached.

The above requirements are possible when the can side wall thickness is relatively thick, and the lower limit is about 0.16a++*. If the side wall is thinner than that, the can side wall will preferentially form a dent.
It becomes difficult to deform the bottom of the can.

In the case of reducing the thickness of the side wall of the can, the side wall may be provided with unevenness under the following conditions.

In other words, can side wall pressure is a factor that greatly influences negative pressure strength, punt resistance, and buckling strength.
If it is less than 2+wm, these required characteristics will not be satisfied, and 0
, a thickness exceeding 16 mm satisfies the required characteristics, but there is a problem in terms of can cost competitiveness. Therefore, the can side wall thickness is set to 0.12 to 0.16 mm.

The shape of the unevenness particularly affects the negative pressure strength and buckling strength, and if the unevenness is not smooth, the inflection point becomes the starting point of the can collapse. For this reason, it is best that the unevenness of the side wall of the can be smooth and, in particular, have a sine curve.

The depth and pitch of the unevenness affect the negative pressure strength, Punto resistance and buckling strength. Firstly, if the depth is less than 0°20 mm, the negative pressure strength and Punto resistance are insufficient;
If it exceeds 70 mm, there is a problem with buckling strength. Therefore, the depth should be in the range of 0°20 to 0.70 mm. Next, if the pitch is less than 2■, the above depth cannot be obtained, the negative pressure strength is not satisfied, and 5 +mlIm
If the value exceeds , either property becomes unsatisfactory. Therefore, the pitch is in the range of 2 to 5 mm.

If the ratio of the uneven area to the can height is less than 1/2, none of the characteristics will be satisfied. Therefore, the ratio of the uneven area to the can height is preferably 1/2 or more.

(Example) Next, examples of the present invention will be shown.

A can of 66 mmφ x 72 mmb (200 cc) was manufactured by applying DI processing to a hard plate material (0.34 mm) of 3004 alloy on a miscellaneous board. The wall thickness was 0.16 m+-, and the bottom shape of one can was as shown in FIG. Pour 90℃ hot water into this can,
After winding and tightening, heat treatment was performed at 120°C, and immediately thereafter cooling was performed with water.

As a result, the bottom of the can was deformed inward during the cooling process. This is because, as can be seen from FIG. 1, the bottom shape of the can is such that it facilitates inversion to the inside of the can.

(5) 0 Gloss In the same manner as in Example 1, cans were manufactured in which the amount of inversion of the can bottom can be varied as shown in Table 1. The amount of inversion was adjusted by changing the shape of the bottom of the can.

As a result, as shown in Table 1, the content of the can was 8 to 15
In the examples of the present invention in which the mQ was within the range, it was easy to turn over when the pressure became negative, and no dents were formed in the side wall of the can even after cooling to room temperature.

A can of 66mmφX 72+n+h (200cc) was manufactured by performing DI processing on a hard plate material (Q, 35mm) of Kantanekeigou 3004 alloy. After baking (200° C. x 20 ml) assuming paint printing, the side wall thickness was varied, and then unevenness was formed on the can side wall using a roll forming machine. A schematic diagram of the can is shown in Fig. 2, including the shape of the can bottom.

Next, hot water at 90° C. was poured into various cans shown in Table 2, and after the cans were rolled up, heat treatment was performed at 120° C., and immediately thereafter, the cans were cooled with water.

As a result, as shown in Table 2, in Inventive Example Nα1, the can bottom was easily turned over to the inside of the can despite the thin can side wall, and no dents were formed at room temperature.

Note that the present invention example of Nα8 is similar to Example 1, and has a drawback of increased cost due to increased can weight.

[Blank below] (Effect of the invention) As explained above, the DI negative pressure can body according to the present invention can replace the conventional three-piece can with a two-piece (DI) can. In addition to significantly reducing the weight of cans, aluminum cans can also be recycled to save resources.

In addition, the side walls of DI cans can be made thinner, making it possible to further reduce the cost of 5 cans, making them inexpensive, easy to apply to non-carbonated beverages, and aluminum cans having the advantage of being odorless. , recyclability) can be fully utilized.

[Brief explanation of drawings]

Figure 1 is a diagram illustrating the shape of the can bottom and the inversion situation in Example 1, Figure 2 is a diagram illustrating the shape of the can in Example 3, and (a) is a sectional view showing the overall shape of the can. , (b) are diagrams illustrating depth. Patent applicant Hisashi Nakamura, Patent attorney representing Kobe Steel, Ltd. Figure 2 (C1) Figure (b)

Claims (4)

[Claims] (1) In DI cans manufactured from plate materials, the shape of the can bottom is such that it can withstand an internal pressure of 3 kg/cm^2, and when the can internal pressure becomes less than 1 kg/cm^2, the can bottom deforms to the inside of the can. A DI negative pressure can body characterized in that the can body is shaped so that the can internal pressure is positive pressure (1 kg/cm^2 or more). (2) In DI cans manufactured from plate materials, the shape of the can bottom is such that it can withstand an internal pressure of 3 kg/cm^2, and when the can internal pressure becomes less than 1 kg/cm^2, the can bottom deforms to the inside of the can. A DI negative pressure can body characterized in that the internal volume of the can is reduced by 8 to 15 ml, so that the internal pressure becomes positive pressure (1 kg/cm^2 or more). (3) In DI cans manufactured from plate materials, from 0.12 to
Pitch 2-5m with sine curve on 0.16mm thick can wall.
m, unevenness with a depth of 0.20 to 0.70 mm is formed, and the shape of the can bottom has an internal pressure of 3 kg/cm^
2, and the can internal pressure becomes less than 1 kg/cm^2, the can bottom deforms inside the can, and the can internal pressure becomes positive pressure (1 kg/cm^2).
A DI negative pressure can body characterized in that it has a shape that provides a pressure of 2 g/cm^2 or more. (4) In DI cans manufactured from plate materials, from 0.12 to
Pitch 2-5m with sine curve on 0.16mm thick can wall.
m, the unevenness with a depth of 0.20 to 0.70 mm is 1/ of the can height.
The shape of the can bottom is such that it can withstand an internal pressure of 3 kg/cm^2, and when the can internal pressure becomes less than 1 kg/cm^2, the can bottom deforms inside the can. A DI negative pressure can body characterized by having a shape in which the internal pressure of the can becomes positive pressure (1 kg/cm^2 or more) by reducing the internal volume of the can by 8 to 15 ml.