JPS62109761A - Easy open cap seal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement in a cap seal used for attaching and fixing a replacement stopper to the crown of a large soft drink bottle, etc. be.

Traditionally, various types of needles, etc. have been commercially available in large bottles containing 1 liter, but in that case, generally after opening the crown, a plastic replacement stopper used in place of the crown is attached to the top of the crown. Fixed.

Generally, the fixing method is as shown in Figure 1.
Place the replacement cap on top of the crown, and from above, insert a cylindrical heat-shrinkable film with a rim at one end (hereinafter referred to as the "cap seal").
) and then heat-shrinked to secure it in place.

To open such a bottle, first grasp the tab on one of the two rims of the Camp Seal, pull it down, and follow the perforations down the sides of the tab. Tear off the cap seal, cut out the strip-shaped part (hereinafter referred to as the "strip-shaped part") from the pod-shaped part (hereinafter referred to as the "pod-shaped part"), remove the cap seal, take out the replacement cap, and then remove the cap. The crown can be opened with a puller.

After pouring the required amount into a glass or the like, the glass is covered with a replacement stopper and stored in a refrigerator or the like.

[Conventional technology]

Conventionally, such camp seals have used heat-shrinkable plastic films mainly made of polyvinyl chloride resin.

However, cap seals made of heat-shrinkable plastic film made mainly of polyvinyl chloride resin are difficult to remove when the tab is pulled down to open the seal, especially if the bottled soft drink has been cooled in a refrigerator, etc. Or, if the tab was pulled quickly, even if perforations were made, the strip was not cut completely to the bottom end, and a portion of it remained.

JP-A No. 55-44852 discloses that a heat-shrinkable film mainly made of polyvinyl chloride resin exhibits extremely excellent tearing directionality in the film flow direction (longitudinal direction) of a film forming device; It has been found that the direction is not affected by the stretching direction, that is, the shrinking direction of the film, and the longitudinal direction of a polyvinyl chloride resin film that has been uniaxially stretched in the transverse direction is the axial direction, and the transverse direction is the circumferential direction. We propose to manufacture cap seals.

On the other hand, Japanese Patent Application Laid-Open No. 58-225146 discloses that a heat-shrinkable film made of a resinous block copolymer mainly composed of styrene hydrocarbons and containing conjugated diene hydrocarbons is suitable for wrapping objects with high rigidity. In this case, thermal contraction tends to be unbalanced and residual stress is not relieved partially, which tends to cause cracks and cracks.The occurrence of cracks and cracks can be prevented by storing the packaged item in a cool place. In order to improve this drawback, a rubbery block copolymer consisting of a conjugated diene hydrocarbon and a styrene hydrocarbon is added to this resinous block polymer. It is suggested that it be added.

In addition, Japanese Patent Application Laid-open No. 60-58387 discloses that in order to improve the drawback of conventional camp seals made of polyvinyl chloride film, etc., that they firmly adhere to the mouth of the container,
We propose to manufacture camp seals from two-wheel stretched styrene resin sheets by differential pressure molding using a female mold.

[Problem that the invention seeks to solve]

Cap seals made of heat-shrinkable plastic film mainly made of polyvinyl chloride resin may cause damage when the tab is pulled down to open the seal, especially if the bottled soft drink has been chilled in a refrigerator, etc. If the tab is pulled too quickly, the strip will often not be cut completely to the bottom edge, even if the perforations are made, and a portion of the camp seal will remain, leaving the replacement stopper unscrewed. If the crown is opened and then capped with a replacement cap and stored in a refrigerator, etc., it not only spoils the aesthetics but is also unhygienic. When the bottles are returned, factories that reuse them require extra manpower to remove the remaining camp stickers.

Therefore, there were expectations for the development of a heat seal that would not break the strips between the perforations even if the tab was cooled in a refrigerator or the like or if the tab was pulled quickly.

Therefore, as described in Japanese Patent Application Laid-Open No. 55-44852, a camp seal manufactured by making the longitudinal direction of a polyvinyl chloride resin film uniaxially stretched in the transverse direction be the axial direction and the transverse direction be the circumferential direction. We tested this, but we were unable to resolve the problem of the strips sandwiched between the perforations breaking when the tab was pulled quickly, especially for items that had been cooled in a refrigerator or the like.

[Means for solving problems]

In order to solve this problem, the present inventors used styrene-butadiene-brosox copolymer as the main raw material, and added a lubricant,
To provide a cap seal characterized in that it is produced from a film obtained by extruding a polymer containing a stabilizer etc. through a goo and stretching only in the transverse direction to the casting direction, with the transverse direction being the circumferential direction. It is something.

As described in JP-A-58-225146, stretched styrene-butadiene block copolymer films may crack or break depending on their composition, especially when stored in a cold place. It has been thought that this is likely to occur. However, unoriented styrene-butadiene block copolymer films are fairly resistant to cracking and cracking.

In addition, heat sealing is applied from above to the refill cap, crown, and bottle neck placed on top of the crown, heat-shrinks in the circumferential direction, and presses and seals the refill cap, crown, and bottle neck from the side. It is fixed.

Therefore, the heat seal needs to be at least circumferentially stretched and not heat set at high temperatures in order to be able to heat shrink in the circumferential direction.

Also, in general, to prevent tabs from being cut off,
It is common knowledge that the strength in the direction in which the tab is pulled, that is, in the axial direction, is increased by means such as stretching, but in the present invention, instead of increasing the tensile strength in the axial direction, first, the same
Alternatively, focusing on the fact that the tear strength between similar plastic films is approximately proportional to the tensile strength in the direction perpendicular to the tear direction, the tabs are marked with 1- in the tear direction (
In order to reduce the tear strength in the circumferential direction (in the axial direction), care should be taken not to make the tensile strength in the circumferential direction unnecessarily high. I tried not to make the strength too high.

Furthermore, we focused on the fact that plastic films are difficult to stretch and cut (stretch cutting), but easy to tear (shear), as everyone experiences on a daily basis. , it has been observed that the tabs of conventional camp seals break when the temperature is low, rather than being pulled and broken, so the tensile strength in the axial direction is
The elongation in the axial direction was made as high as possible without being increased by stretching.

Furthermore, since the cap seal according to the present invention is manufactured from a film obtained by stretching only in the transverse direction to the casting direction, with the transverse direction being the circumferential direction, This is completely different from the cap seal which is made from a biaxially stretched styrene resin sheet by a differential pressure molding method using a female mold as described in the above publication.

[Effect]

In the present invention, the styrene-butadiene-block copolymer film constituting the camp seal is stretched only in the transverse direction, with the transverse direction being the circumferential direction, to produce a cap seal and increase the tensile strength in the axial direction. Instead, in order to reduce the tear strength in the direction in which the tabs are torn (axial direction) as much as possible, care should be taken not to increase the tensile strength in the circumferential direction unnecessarily, and in the circumferential direction, sufficient heat is applied by stretching. Shrinkability is obtained, but since the tensile strength is not made too high, the tear strength when tearing the tab is not high.

Furthermore, the cap seal according to the present invention is not stretched in the axial direction, and in particular, in the case of the styrene-butadiene-block copolymer film according to the present invention, the cap seal is not stretched in the axial direction even by heating the cap seal. Since it has a characteristic that the elongation does not decrease much, it has a high elongation in the axial direction even after the cap seal is attached.

Furthermore, in the case of styrene-butadiene-block copolymers, as described in JP-A-58-225146, cracks and cracks tend to occur more easily as the residual stress is relaxed. This appears to create a potential crack between the perforations that can be easily torn off when the tab is pulled.

〔Example〕

(11) A commercially available styrene-butadiene block copolymer containing lubricants, stabilizers, etc. was melted and extruded through a T-die to form an unstretched film, which was then stretched 5.0 times in the transverse direction at 103°C until the thickness A 70μ film was obtained.The properties of this stretched film (A) and a conventional commercially available polyvinyl chloride film for sealing (C) were as shown in Table 1.

Table 1 Note (11 test methods are based on JIS.

Note (2) Measurement temperature: 5°C.

Note (3) Tear strength is based on the right angle tear test method.
The tear strength in the lateral direction of the longitudinal test piece is shown in the horizontal column, and the tear strength in the longitudinal direction of the lateral test piece is shown in the vertical column.

Note +4) The numerical value is the average of each 5 measured values.

As shown in Table 1, although the film for camp seals (Δ) according to the present invention is stretched at a high magnification in the transverse direction, it is different from the conventional commercially available polyvinyl chloride film for cap seals (C ) has lower tensile strength in the transverse direction and tear strength in the longitudinal direction. Furthermore, even at 5° C., it has sufficient elongation in the longitudinal direction, and it can be seen that embrittlement due to low temperatures has not occurred.

(21 (A composition similar to 11 was extruded from a T-die to form an unstretched film, and the film was stretched 4.0 times in the transverse direction at 103°C to obtain a film with a thickness of 70μ. (B), a conventional commercially available polyvinyl chloride film for heat sealing (C), and a polyvinyl chloride film for heat sealing (D) manufactured based on the description of JP-A-55-44852, in the lateral direction. The tensile strength and elongation in the machine direction were measured after heat shrinking by 20% or 40%.The results are shown in Table 2.

Table 2 Note (1) Test method is based on JIS.

Note (2) Measurement temperature, 5°C0 Note (3) Values are the average of three measurements each.

As shown in Table 2, the cap sealing film (B) according to the present invention is similar to other films (C) and (D).
Despite the fact that the elongation has decreased due to heat shrinkage, no decrease in elongation due to heat shrinkage is observed.

(3) Make 24 of each of the cap seals according to the present invention and the conventional gap seals made of polyvinyl chloride film, and use each cap seal to make a 48-piece IIl bottle filled with orange need and stoppered at camp. ''Second, I put a replacement stopper on it and attached it with heat shrink.

The dish with this replacement stopper was cooled to 5℃, and randomly
Six monitors were asked to open the cap seal.

As a result, bottles using conventional camp seals contain 1
For the 0 piece, a torn piece was found on the band-shaped part between the perforations below the tab, but for the 111 piece (which used the cap seal according to the present invention), there were no pieces where the tab or the band-like part was torn. There wasn't.

〔Effect of the invention〕

Since the cap seal according to the present invention has the structure as described above, it is used for attaching a replacement stopper to a soft drink bottle, and even if it is cooled in a refrigerator etc., when the camp seal is opened, the tab will be removed. There is no occurrence of torn or torn strips.

Therefore, even if you store it in the refrigerator after opening, it will be clean and
Hygienic. Furthermore, even if the empty bottle is returned to a factory or the like, there is no need for manpower to remove the remaining cap seal.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the top of the bottle with a refill attached with a cap seal. In this figure, 1 is a bottle, 2 is a replacement cap, and 3 is a cap seal.

Claims (1)

[Claims] The main raw material is styrene-butadiene-block copolymer, and the polymer containing lubricants, stabilizers, etc. is extruded through a die.
A cap seal characterized in that it is manufactured from a film obtained by stretching only in the transverse direction with respect to the casting direction, with the transverse direction being the circumferential direction.