JPH03289467A - Easy open container and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a container having a pressure resisting sealing performance and easy to open and not requiring a precise matching in position at the time of heat sealing by a method wherein the dot-like small recess parts having a specific pitch and depth are formed on a flange peripherally in two rows at a specific width all around the periphery of the flange from its innermost circumference to the outer peripheral extremity and vice versa. CONSTITUTION:A container 1 has a lamination strength of 300-2000g/25mm between a seal layer 4 and its adjoining layer 5 and circular flange 2 projecting from the seal layer 4 having a thickness of 10-70mum and made up of a multilayer sheet 1. The flange 2 is provided at a width of 1-3mm from its innermost circumference to the outer peripheral extremity and vice versa with dot-like small recess parts 7 formed peripherally in two rows at a pitch of 0.3-0.8mm and having a recess depth d=1t-10t (wherein (d) is recess depth and (t) is the thickness of the seal layer). The entire surface of the flange 2 is heat sealed to a lid in such a manner that seal strength between the flange surface and the lid becomes equal to and exceeds that between the seal layer and the adjoining layer of the container body.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a food packaging container composed of a plastic container having a mouth-shaped flange and a lid, in which the lid can be easily opened. The present invention relates to a packaging container that can be produced and a method for manufacturing the same.

(Prior Art) Plastic packaging containers with a so-called easy-open structure, in which the lid material can be easily opened, are widely used as packaging containers for packaging various foods.

The structure of the easy-open type, the most common type that has been in practical use, is to maintain the sealing strength between the container flange and the lid within an appropriate range by changing the composition of the resin that makes up the sealing layer of the lid. Usually 500-1500g
There is a type (interface peeling type) in which the seal is adjusted to 5 mm) and the seal interface is peeled off to open the seal.

However, with this interfacial peeling type, the seal strength provided is easily affected by sealing conditions, environmental temperature, adhesion of contents, etc., so it is difficult to control to obtain the seal strength within the desired range, and it is often difficult to control the seal strength. This had the disadvantage of causing variations in the results.

If this variation is biased toward the weak side, it will cause seal leakage, and conversely, if it biases toward the strong side, it will impede releasability and impair easy-opening properties. In particular, seal leakage is a fatal defect for sealed containers and packages, so measures are usually taken to set the heat and pressure conditions of the seal to a higher level, even at the expense of peelability.

In order to improve such problems, for example,
As described in Japanese Patent No. 7597, there is known a method of opening the container by delaminating the seal layer on the second lunge side of the container and the layer adjacent thereto (delamination type).

However, if this structure was attempted to be achieved using a conventional sealing method, the sealing layer portion would not break smoothly, making it difficult to remove the contents.

In this case, in order to facilitate the rupture of the release layer and the adjacent layer, a structure in which a cut for starting peeling and a cut for stopping peeling are provided in the flange (JP-A-5B6396060, JP-A-63-96061, etc.) ), but there is a risk of impairing pressure resistance in these structures. In addition, the seal position must be precisely controlled to prevent Rad from being applied to these notches and the heat seal, and if the heat seal head is applied even slightly to these notches, the seal layer will be difficult to cut. In some cases, the lid material and the container body did not separate cleanly, and problems remained in terms of ease of opening.

In addition to this method, a method using a notch in the sealing layer of the lid material has been proposed, but this method requires accurate alignment of the container body and the lid material. There is a problem similar to when a cut is made in the upper flange.

Furthermore, a method has been proposed in which a sealing material with the same shape as the flange is bonded to the flange of the container body to form a sealing layer, and a lid material is sealed on top of this, but this method also requires a step of bonding the sealing layer. There was a problem in that the product came loose and there were also difficulties in positioning, resulting in poor productivity.

(Problems to be Solved by the Invention) The present invention has been developed through intensive studies to solve these problems, and has achieved both pressure-resistant sealability and easy-opening performance, which are considered to be contradictory properties in the conventional technology, and also achieves precision sealing during heat sealing. To provide an easy-to-open container that does not require positioning and a method for manufacturing the same.

That is, the present invention comprises a lid material and a container body in which a large number of minute recesses are formed in two 1 to 3 mm radiuses over the entire circumference of the innermost circumference and the outermost circumference of the flange portion of the container body. The purpose of the present invention is to provide a hermetically sealed packaging container that does not require special control during heat sealing, maintains stable pressure resistance, and can be opened smoothly and easily, and a method for producing the same. There is.

(Means for Solving the Problems) The present invention provides the following features: (1) the lamination strength of the seal layer and the adjacent layer in contact therewith is 300 to 2000 g/25 mm;
A container having a mouth-shaped flange formed from a multilayer sheet with a sealing layer having a thickness of 10 to 70 μm, the surface of the flange having a thickness of 1 to 3 μm from the innermost circumference to the outer circumference.
mm width and 1 to 3 mm inward from the outermost periphery
The pitch interval is 0.3 to 0.8 + nm over the entire circumference, and the depth d is d-It-1 with respect to the thickness of the sealing layer.
Two dot-like minute recesses with a depth of 0t are formed, and the entire surface of the 7-run sieve is sealed so that the sealing strength between the flange surface and the lid material is greater than the sealing strength between the sealing layer of the container body and the adjacent layer. It is an easy-to-open container having a heat-sealing structure, and (2) the lamination strength of the sealing layer and the adjacent layer in contact therewith is 300 to 2000 g/25 mm,
A container having a mouth-shaped flange formed from a multilayer sheet with a sealing layer thickness of 10 to 70 μm has two stripes along the innermost side wall of the container and the outer side wall of the flange on the back side of the flange part. A receiving mold with a smooth surface width of 1 to 3 mm is fitted, and an ultrasonic horn having minute protrusions in the form of dots with a pitch of 0.3 to 0-8 mm from the surface sealing layer side of the flange part is used. The depth d on the surface of the flange part is d-1t to 10t with respect to the thickness of the sealing layer,
And ultrasonic treatment is performed under conditions such that d<115T with respect to the total thickness T of the flange part, and two dot-shaped minute recesses are formed on the innermost circumference side and the outermost circumference side of the flange part. and a method for manufacturing an easy-to-open container, characterized in that the entire surface of the flange is heat-sealed so that the sealing strength between the flange surface and the lid material is greater than the lamination strength between the sealing layer of the container body and the adjacent layer. be.

Hereinafter, the present invention will be explained in detail along with the drawings.

FIG. 1 is a sectional view showing an easy-to-open container of the present invention.
A container body includes a flange portion 2 having a mouth shape, and 3 is a lid material. The container body 1 is made of a multilayer sheet having a sealing layer 4 and an adjacent layer 5 opposite thereto, and has a drop 10 at the outermost circumference of the flange.

The structure of the multilayer sheet may be, for example, a simple two-layer sheet in which the sealing layer 4 is made of polyethylene resin and the adjacent layer 5 is made of polypropylene resin, and this adjacent layer 5 is made of saponified ethylene vinyl acetate copolymer or vinylidene chloride resin. It may be a multilayer sheet formed by laminating metal, paper, ceramics, etc. as a barrier layer of resin, a layer of polypropylene resin, polyester resin, etc., or an intermediate layer.

These multilayer sheets constituting the container body 1 have a sealing layer 4
The lamination strength between the layer 5 and the adjacent layer 5 is 300 to 2000 g.
/mm (peeling angle 180" peeling speed 200III
/m1n), and the thickness of the sealing layer 4 is required to be in the range of lO to 70μ.

If the lamination strength is less than 300g/25mm and the thickness of the sealing layer is less than lOμ, sufficient sealing performance cannot be ensured.On the other hand, if the lamination strength is less than 2000g
This is because if the thickness of the seal layer exceeds /25+++m and the thickness of the seal layer exceeds 70 μm, peeling resistance upon opening becomes large and smooth beer quality is impaired. It is desirable that the film forming the lid material 3 has a sealant layer 6 made of a material that tightly adheres to the sealing layer 4 of the container body, and in the most preferred embodiment, the sealant layer 6 of the lid material is bonded to the sealing layer 4 of the container body. They should be made of the same resin material. The film of the lid material 3 may be a single layer, but it may also have a multilayer structure in which metal foil or plastic materials with good barrier properties are combined.

At the innermost and outermost circumferential parts of the sealing layer surface of the mouth-shaped flange part 2 of the container body l, two microscopic recesses 7 with a width of 1 to 3 mm are formed over the entire circumference. . As shown in FIG. 2 (perspective view of the container), the minute recesses 7 are formed on the outermost circumferential side and the outermost circumferential side of the flange portion. As shown in FIG. 3, the minute recess 7 is formed by placing a receiving mold 8 with a smooth surface having a width of 1 to 3 mm on the back surface of the flange portion of the container body.
Pitch interval W from the seal layer surface is 0.3 to 0, 8 lI
Apply the ultrasonic horn head 9 having point-like minute protrusions Im to the surface of the flange s2 to form a large number of holes such that the depth d is d=lt-10t with respect to the thickness of the sealing layer. Forms point-like minute recesses. Note that a minute recess is formed such that the depth d of the recess satisfies d<115T with respect to the total thickness T of the flange portion. FIG. 3 shows an enlarged cross-sectional view and an enlarged plan view of the ultrasonic horn head before ultrasonic treatment, and FIG. 4 (aXb) shows an enlarged cross-sectional view and an enlarged plan view of the ultrasonic horn head.

FIG. 5 shows an enlarged view of the flange portion with minute recesses formed therein. It is important that the pitch interval W is 0.3 to 0.8 m+a; if the pitch interval is less than 0.3+am, it will be too fine and it will be difficult to form the effective depth d of the recess, which will result in stable beer production. Not only will it not be possible to obtain a good taste, but it will also cause a poor appearance after beer. Also, if it exceeds 0.8+++m, the grain will become too coarse,
Similarly, when the seal layer breaks, the smoothness of the cut is impaired, and at the same time, the appearance after beer is poor (the appearance of thread-like whiskers).
becomes.

In addition, the radius W of the micro recesses formed by ultrasonic treatment is 1 to
It is necessary to set it to 3mm, and if it is 1mm or less,
There is a risk that the receiving mold will dig into the back surface of the flange during ultrasonic treatment, resulting in poor appearance of the flange, which may cause the flange to chip during distribution. Further, depending on the relationship with the pitch interval W, variations occur in the easy openability.

If the width W is 3 mm or more, there is a risk that over 70% of the contents during filling will enter the formed minute recesses, resulting in poor adhesion and poor appearance.

Further, the processing depth d is related to the thickness of the sealing layer and the pitch interval d, and in the above case, the processing depth d is in the range of d-It-10t with respect to the thickness of the sealing layer. If d is less than 1, the easy opening property will be impaired and the appearance after beer will be poor. Also, d is 10
If it exceeds t, the beer taste will be significantly impaired and the appearance will be poor after sealing the lid material.

These formed minute recesses need to be large enough to be completely filled with the resin constituting the sealant layer of the lid material during heat sealing.

Among these conditions, a particularly desirable range is that the pitch interval W of the dot-like minute recesses is 0.4 to 0.6 mrn (diagonal pitch interval 0.6 to 0.9 mm), and the width to be processed is A range of 1 to b gives a beer with a very smooth beer feel.

The seal structure of the present invention is made by superimposing the flange part 2 of the container body, which has a minute recess formed in the innermost circumferential part of the seal layer surface of the flange part to 3 mm, and the sealant layer 6 of the lid material 3, and heats the sealant layer 6 of the lid material 3. It is formed by sealing, but in this case, the condition is that the sealing strength between the sealing layer surface and the sealant layer of the lid material is greater than the lamination strength of the sealing layer 4 and the adjacent layer 5 of the container body. be.

(Function) As shown in FIG. 6, the sealing structure according to the present invention described above is such that the sealant layer of the lid member 3 and the sealing layer of the flange portion 2 are tightly bonded and integrated, and the innermost part of the flange portion The resin of the sealant layer is filled in the dot-like minute recesses 7 formed around the circumference. Therefore, the combined sealing layer has a unique structure in which the thickness of the layer and the strength of the sealing strength are distributed around the innermost circumference. This seal structure provides stable pressure resistance against internal and external pressure when sealed, and when the seal is opened, the seal layer first ruptures with a slight force at the minute depression formed on the outermost circumference, and then peels off between the eyebrows. On the other hand, at the innermost circumferential portion, the sealing layer is easily broken and separated at the point where the minute recess is formed, and the sealing layer is opened smoothly and completely.

(Example) - The thickness of the entire example was 750μ, a high-density polyethylene layer was 40μ as a sealing layer, a multilayer sheet made of polypropylene was vacuum formed as an adjacent layer, the inner diameter was 65 mm, the outer diameter of the flange was 75 mm, A container body with a height of 25 mm was obtained. The lamination strength between the seal layer and the adjacent layer of this container body was 1500 g/25 mm.

Then, using an ultrasonic horn head having a large number of minute protrusions with a pitch of 0.6 mm on the innermost circumference and outermost circumference of the sealing layer surface of the mouth-shaped flange part, the sealing layer surface of the mouth-shaped flange part was minutely etched to a width of L5 mm. Two concave bands were formed.

The conditions for the ultrasonic treatment were an output of 2 kW (energy used: 225 j), a pressing force of 338 pa, and a time of 0.3 seconds to form dot-like minute recesses with a depth of 120 μm.

The lid material used was a sealant layer made of high-density polyethylene (thickness: 50 μm), which is the same as the sealing layer of the container, and dry laminated with stretched polyamide (thickness: 30 μm).

A sealant layer of the lid material was layered on the sealing layer surface of the container flange portion and heat-sealed twice under the conditions of a surface pressure of 2 kg/cm2, a temperature of 190°, and a time of 1.0 seconds to obtain an easily openable container of the present invention. .

When the lids of the obtained 50 sealed containers were opened, all the containers had a stable beer taste and opened smoothly, and the condition of the opened surface was also very good.

・On the 7-rung surface of the container body obtained in Comparative Example Example, two stripes with a depth of 50 μm were placed at the l++v position along the innermost circumference of the 7-rung part and at a position 1 mun inside from the outermost circumference. The notch was made all the way around.

This container body and the lid material of the example were heat-sealed under the same conditions to obtain a sealed container.

Of the 50 sealed containers obtained, approximately 3 had poor beer taste due to misalignment during machining of the notch, misalignment of the heat seal, etc. when the lid was opened.
0% occurred. In addition, most of these defective products had string-like stubble in the openings and had a poor appearance.

(Effects of the Invention) According to the present invention, the lid material is heat-sealed to the 7 rung portion of the container body in which dot-shaped minute recesses are formed by ultrasonic treatment on the innermost circumference of the seal layer surface of the container body. This sealed container has a very stable and smooth beer taste, and it is much easier to heat seal than conventional containers, so it does not require precise positioning, and it has a stable beer taste. Containers can be manufactured efficiently.

[Brief explanation of drawings]

@ Figure 1 is a cross-sectional view of the easy-to-open container of the present invention, Figure 2 is a perspective view of the container with the lid half-opened, and Figure 3 shows the process of ultrasonically treating the 7 rungs of the container body. Schematic diagram, 4th
The figure shows an enlarged sectional view (a) and an enlarged plan view (b) of the ultrasonic horn head, and Fig.
An enlarged cross-sectional view of the rung portion and FIG. 6 are enlarged cross-sectional views of the seven rung portion showing the sealed state and the unsealed state of the lid member. In the figure: 1 Container body, 2 Mouth-shaped 7 rungs 3 Lid material, 4 Seal layer, 5 Adjacent layer, 6 Sealant layer, 7 Minute recess,

Claims (2)

[Claims] (1) Molded from a multilayer sheet in which the lamination strength of the sealing layer and the adjacent layer in contact with it is 300 to 2000g/25mm, and the thickness of the sealing layer is 10 to 70μ.
A container having a shaped flange, which has a width of 1 to 3 mm from the innermost circumference toward the outer circumference on the surface of the flange portion and a width of 1 to 3 mm from the outermost circumference toward the inner circumference over the entire circumference. The pitch interval is 0.3 to 0.8 mm, and the depth d
forms two dot-shaped minute micro recesses with a depth of d = 1t to 10t relative to the thickness of the sealing layer, and the sealing strength between the flange surface and the lid material is close to that of the sealing layer of the container body. An easy-to-open container that has a structure in which the entire surface of the flange is heat-sealed so that the sealing strength is greater than the sealing strength between the layers. (2) Molded from a multilayer sheet in which the lamination strength of the sealing layer and the adjacent layer in contact with it is 300 to 2000g/25mm, and the thickness of the sealing layer is 10 to 70μ.
A receiving mold having two smooth surfaces with a width of 1 to 3 mm is fitted along the innermost side wall of the container and the outer side wall of the flange drop side on the back side of the flange part of a container having a flange shape, and the flange is Using an ultrasonic horn having minute convexities in the form of dots with a pitch interval of 0.3 to 0.8 mm from the surface seal layer side of the flange part, the depth d is equal to the thickness of the seal layer on the surface of the flange part. Ultrasonic treatment is performed under conditions such that d=1t to 10t and d<1/5T with respect to the total thickness T of the flange part, and the innermost circumferential part side and the outermost circumferential part side of the flange part are treated with ultrasonic waves. Two dot-like minute recesses are formed in the container, and the entire surface of the flange is heat-sealed so that the sealing strength between the flange surface and the lid material is greater than the lamination strength between the sealing layer of the container body and the adjacent layer. A method for producing a characteristically easy-to-open container.