JP2971185B2 - Method of forming minute concave portion on flange portion of container body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package consisting of a plastic container body having a flange portion and a lid material, which can be easily opened with the lid material of the flange portion of the container body of the sealed package body. The present invention relates to a method for forming a minute recess by ultrasonically treating a sealing surface.

[0002]

2. Description of the Related Art The most common method for easily opening a plastic package, which has been conventionally carried out, is to form a seal layer of a lid material with a compound of various resins, thereby making it possible to form a package with a container. Moderate seal strength (for example, 600 to 10
(00 g / 15 mm), and peels off the interface between the lid member and the container to open the container. However, the sealing strength is easily affected by the sealing conditions, the environmental temperature, the adhesion of the contents, and the like, so that the sealing strength varies up and down. If there is variation below, there is a risk that a seal leakage accident may occur. Conversely, if there is an upward variation, the peeling property is deteriorated, and the package cannot be easily opened. Since a seal leak is a fatal defect, it is common that the seal temperature or pressure is set to a higher value to give a variation upward. For this reason, it was generally difficult to open.

In order to overcome this difficulty, a method of opening the seal layer by delamination between the seal layer and the adjacent layer has been proposed (for example, Japanese Patent Publication No. 50-37598). There was a drawback that the content was not broken and it was difficult to take out the contents.
In the easy-open package of these methods (interlaminar peeling type), a cut line is formed in the seal layer in order to obtain a more stable one, and a resin pool of the resin of the seal layer is formed at the time of heat sealing. Various methods have been proposed.

[0004] As a method for producing these easily-openable packages, Japanese Patent Application Laid-Open No. 63-96061 (a method in which a cut is made linearly on the surface of a seal layer) has been proposed. However, in these methods, it is very difficult to make a cut line at an accurate position, and it is not easy to control the sealing position of the lid material so as not to be caught by these cut lines. It was difficult to obtain a package having easy opening properties.

Therefore, the present inventors have laminated a material layer which does not adhere to the lid material on the innermost layer of the container body made of a multilayer sheet, and ultrasonically treated the upper surface of the flange portion to count the number of broken material layers. After forming the minute concave portions of the above, a heat sealing property and an easy peeling property of the container having both the heat sealing property and the easy peeling property are obtained by heat sealing the adhesive layer and the adjacent layer exposed on the flange portion. Flat one
-337573, Japanese Patent Application No. 2-80968, Japanese Patent Application No. 2
No. 126947, and Japanese Utility Model Application No.
No. 44618, etc. were devised.

More specifically, a flange of a container having a flange formed from a multilayer sheet having a laminate strength of 300 to 2000 g / 25 mm between a sealing layer and an adjacent layer in contact with the sealing layer and a thickness of the sealing layer of 10 to 90 μm. From the innermost circumference to the outer circumference and / or from the outermost circumference to the inner circumference on the surface of the part, the pitch interval is 0.3 to 0.8 mm over the entire circumference with a width of 1 to 3 mm, and the depth d. Form a point-like minute concave portion having a depth of d = 1t to 10t with respect to the thickness t of the sealing layer, and the sealing strength between the flange surface and the lid member is determined by the difference between the sealing layer of the container body and the adjacent layer. The structure is such that the entire surface of the flange is heat-sealed so as to have a seal strength or more. Ultrasonic mechanical vibration is used as means for forming the minute concave portion.

The mechanical vibration of the ultrasonic wave is defined by the frequency of the ultrasonic wave, the amplitude of the ultrasonic horn forming the minute concave portion, the vibration mode, and the generated ultrasonic energy. The formation of the minute concave portion also depends on the material of the ultrasonic horn. If these conditions are not appropriate and the conditions are not appropriate, the depth of the minute concave portion becomes shallower than the desired size, so that sufficient easy-peeling properties cannot be obtained or appearance defects after peeling occur.
Conversely, if it is too deep, the easy peel property is significantly impaired, resulting in poor appearance after sealing the lid material.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been studied diligently, and the state of formation of the minute concave portion is always stably maintained at a desired state, and the ultrasonic vibration which can be processed is generated. An object of the present invention is to provide an ultrasonic generator that can be maintained.

[0009]

According to the present invention, there is provided (1) a laminate having a laminate strength of 300 to 20 between a sealing layer and an adjacent layer in contact with the sealing layer.
00 g / 25 mm, and the thickness of the sealing layer is 10 to 90 μm
Pitch interval of 0.3 to 0.8 over the entire circumference of the surface of the flange portion of a container having a flange formed from the multilayer sheet
mm, the depth d is d = 1t to 1 with respect to the thickness t of the sealing layer.
In an ultrasonic processing apparatus for forming a point-like minute concave portion having a depth of 0t, an ultrasonic frequency is 18 to 38 KHz, a horn amplitude is 20 to 100 μm, and a vertical vibration is 0.1 to 0.1 μm.
Ultrasonic treatment using a horn having a vibration mode capable of generating a 1.5-times transverse vibration mode, and a method for forming a minute concave portion, and (2) the thermal conductivity of the ultrasonic horn is
1.5 × 10 ^-2 Cal / cm ² / sec / ° C / cm to 30 × 10
This is a method for forming minute concave portions using an ultrasonic treatment apparatus made of a metal within a range of ^-2 Cal / cm ² / sec / ° C./cm.

Hereinafter, the present invention will be described in detail with reference to the drawings. First, the configuration requirements of a container to which the ultrasonic processing apparatus according to the present invention is applied and the shape of a tip of an ultrasonic horn for forming a minute concave portion provided in a container flange portion are described with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 1 is a sectional view of a container obtained by the method of the present invention.
Is a lid material. The container body 1 is composed of a multilayer sheet having a sealing layer 4 and an adjacent layer 5 opposed thereto.

The structure of the multilayer sheet may be, for example, a simple two-layer sheet in which a polyethylene resin is disposed in the sealing layer 4 and a polypropylene resin is disposed in the adjacent layer 5.
Is a barrier layer such as a saponified ethylene-vinyl acetate copolymer or a vinylidene chloride resin, a polypropylene resin,
Metal as a layer or intermediate layer of polyester resin, etc.
A multilayer sheet made of paper, ceramics or the like may be used. The multilayer sheet constituting the container body 1 has a laminate strength between the sealing layer 4 and the adjacent layer 5 of 3.
00-2000g / 25mm (peeling angle 180 ° peeling speed 200mm / mi
n), and the requirement is that the thickness of the sealing layer 4 be in the range of 10 to 90 μm .

[0013] The lamination strength is less than 300g / 25mm ,
If the thickness of the sealing layer is less than 10 μm, sufficient sealing properties cannot be ensured, while the lamination strength is less than 20 μm.
If the thickness exceeds 00 g / 25 mm and the thickness of the seal layer exceeds 90 μm, the peel resistance at the time of opening becomes large, and the smooth peelability is impaired.

The film forming the cover 3 preferably has a sealant layer 6 made of a material which is firmly adhered to the seal layer 4 of the container body. The layer 4 is made of the same resin material. The film of the lid member 3 may be a single layer, but may be a multilayer structure combining a metal foil or a plastic material having good barrier properties.

On the innermost circumferential portion of the seal layer surface of the flange portion 2 of the container body 1, a large number of minute concave portions 7 are formed over the entire circumference with a width of 1 to 3 mm. As shown in FIG. 2 (a perspective view of the container), the minute concave portion 7 is formed on the innermost peripheral side of the flange portion. As shown in FIG. 3, the fine concave portion 7 is provided with a receiving die 9 having a smooth surface width of 1 to 3 mm on the back surface of the flange portion of the container body, and the pitch interval w is 0.3 to 0.8 mm from the sealing layer surface.
The ultrasonic horn head 8 having the point-like minute convex portions is applied to the surface of the flange portion 2 so that the depth d becomes d = 1t to 10t with respect to the thickness t of the seal layer. Is formed. Note that a minute concave portion is formed such that the depth d of the concave portion is d <１ ／ · T with respect to the total thickness T of the flange portion.

FIG. 3 shows the state before the ultrasonic treatment, and FIGS. 4 (a) and 4 (b).
2 shows an enlarged sectional view and an enlarged plan view of the ultrasonic horn head. FIG. 5 is an enlarged view showing a minute concave portion of a flange portion.
Is shown. It is important that the pitch interval w is 0.3 to 0.8 mm, and if the pitch interval is less than 0.3 mm, it is difficult to form an effective depth d of the concave portion because the pitch is too fine, so that a stable peel can be obtained. At the same time, it is not possible to obtain a feeling, and at the same time, it may cause poor appearance after peeling. On the other hand, if the thickness exceeds 0.8 mm, the mesh becomes too coarse, and similarly, when the seal layer is broken, the smoothness of the cut is impaired, and at the same time, the appearance is poor after peeling (stringy whisker is generated).

Further, the processing depth d is related to the thickness of the seal layer and the pitch d, and in the above case, the processing depth d
Needs to be in the range of d = 1t to 10t with respect to the thickness t of the seal layer. If d is 1t or less, the CSG openness is impaired, and the appearance is poor after peeling. On the other hand, if d exceeds 10 t, the peel feeling will be significantly impaired, and the appearance will be poor after sealing the lid material.

It is necessary that these formed minute recesses have such a size that the resin constituting the sealant layer of the lid material is completely filled at the time of heat sealing. Among these conditions, a particularly desirable range is that the pitch interval w of the point-like minute concave portions is 0.4 to 0.6 mm (the diagonal pitch interval is 0.6 to 0.6 mm).
9 mm), the width to be processed is 1 to 2 mm, and the depth d of the minute concave portion is in the range of 2 to 5 t, which gives a very smooth peel feeling.

In the sealing structure, the flange portion 2 of the container main body having a minute concave portion formed over the width of 1 to 3 mm of the innermost circumferential portion of the seal layer surface of the flange portion and the sealant layer 6 of the lid member 3 are overlapped and heated. It is formed by sealing. The condition in this case is that the seal strength between the seal layer surface and the sealant layer of the lid material is equal to or higher than the laminate strength of the seal layer 4 and the adjacent layer 5 of the container body. .

As described above, the components on the container body side and the shape of the tip of the ultrasonic horn part are in strict conditions. To satisfy these conditions, the components on the ultrasonic processing apparatus side are important. One embodiment of the ultrasonic processing apparatus according to the present invention will be described below in detail with reference to FIG.

FIG. 6A shows the structure of an actuator section for generating mechanical vibration of ultrasonic waves and the vibration distribution of each section. The actuator (10) includes a vibrator (11), a booster (12), and a horn (13).
Consists of Although not shown, the vibrator section (11) is connected to an ultrasonic oscillator for generating high-frequency power by a high-frequency cable (14), and the high-frequency power from the ultrasonic oscillator is transmitted under the ultrasonic frequency. An ultrasonic transducer that converts the vibration into mechanical vibration that can be used. As the ultrasonic transducer used in the present invention, any of an electrostrictive vibrator and a magnetostrictive vibrator can be used, but it corresponds to the ultrasonic frequency. From the viewpoint of energy conversion efficiency for converting high-frequency electric energy into mechanical vibration energy, an electrostrictive vibrator is desirable. In this embodiment, an electrostrictive vibrator will be described.

The vibrator portion (11) includes a plurality of disk-shaped ultrasonic vibration elements (15), a round bar-shaped backing plate (16) for sandwiching the ultrasonic vibration elements (15), and a front plate ( 17) Usually, the center part of the ultrasonic vibrating element (15) is hollow, and a through bolt is passed through this part, and the ultrasonic vibrating element (15) is so-called loose screw tightened with screws provided on the backing plate (16) and the front plate (17). Takes a bolted Langevin type vibrator structure. The material of the ultrasonic vibrating element (15) is a ceramic having electrostrictive ability such as barium titanate and lead zirconate titanate. The number of ultrasonic vibrating elements (15) varies depending on the output to be generated. Approximately six to six sheets are used, and an electrode plate (18) of beryllium copper or the like is provided in a hollow disk shape between these ultrasonic vibration elements (15), and a high-frequency cable (14) is soldered to the electrode plate (18). It connects by attaching, etc., and supplies high frequency power under the ultrasonic frequency. The material of the backing plate (16) and the front plate (17) is preferably a material having tensile strength and toughness capable of withstanding high-speed vibration of ultrasonic frequency. As such materials, aluminum alloy such as duralumin, titanium alloy, stainless steel, etc. Is good.

The length of the vibrator portion (11) satisfies the relational expression c = λ · f between the ultrasonic resonance frequency f used, the sound velocity c of the vibrator portion 11 and the wavelength λ. The length is designed to be half the wavelength (λ) that can be used. Therefore, there is a node (node) where the vibration of the vibrator part (11) in the axial direction (length direction) becomes zero, and a flange (19) is provided in this part, and although not shown, the vibrator part ( It is used as a fixing part for the case 11).

The booster section (12) has a circular cross section and has a lower end face (2) of a front plate (17) of the vibrator section (11).
0) has the role of expanding the vibration amplitude in the axial direction, and the axial length of the booster section (12) is the same as that of the vibrator section (11). Is designed to be 1/2 of The diameters of the upper end face (21) and the lower end face (22) of the booster section (12) are smaller at the lower end face (22) than at the upper end face (21), and the cross-sectional area of the upper end face (21) and the lower end face ( The vibration amplitude in the axial direction of the lower end surface portion (22) is increased substantially in proportion to the ratio of the cross-sectional area of (22). The upper end surface of the booster section (12) (2
The connection between 1) and the lower end surface part (20) of the front plate (17) of the vibrator part (11) is usually screwed. A substantially central position of the axial length of the booster portion (12) becomes a node (node) where the axial vibration amplitude becomes zero, and a flange (23) is provided in this portion to serve as a holding portion for the entire actuator (10). To have. The material of the booster section (12) preferably has a tensile strength capable of withstanding mechanical high-speed vibration of ultrasonic waves, and is preferably an amyl alloy such as duralumin.

The horn section (13) is an overall view of the ultrasonic horn head (8) shown in FIG. 3 functioning as a working section. The length of the horn section (13) in the axial direction is About 1 of the wavelength (λ) of the ultrasonic wave propagating in the portion (13)
/ 2 length. Upper end surface (24) of horn (13)
And the lower end surface part (22) of the booster part (12) is preferably screwed.

Next, the vibration mode of the ultrasonic processing apparatus according to the present invention will be described with reference to FIGS. 6 (b) and 6 (c). FIG. 6B is a pattern diagram of the vibration amplitude of the actuator (10) in the axial direction, that is, in the vertical direction, and FIG.
Shows pattern diagrams of vibration amplitude in the direction perpendicular to the axis of the actuator (10), that is, in the lateral direction. As described above, in the ultrasonic processing apparatus according to the present invention, the vibrator section (11), the booster section (12), and the horn section (13) are each λλ.
(Wavelength) equivalent length, and the vibration mode of the vibrator part (11) is such that the upper end face part (16) and the lower end face part (20) of the vibrator part (11) have antinodes (25), (26) of the longitudinal vibration amplitude. At the same time, the vibration modes of the booster section (12) are adjusted to the nodes (27) and (28) of the lateral vibration amplitude, and the upper end face (21) and the lower end face (2) of the booster section (12) are set.
2) makes the abdomen (26) (29) of the longitudinal vibration amplitude and coincides with the nodes (28) (30) of the lateral vibration amplitude, and the vibration mode of the horn (13) is (24) and the lower end face, that is, the ultrasonic horn head section (8) are the abdominal parts (29) and (31) of the longitudinal vibration amplitude, and the upper end face part (24) is the node (30) in the transverse vibration amplitude.
And the node (3) of the longitudinal vibration amplitude of the horn (13)
The position corresponding to 2) is located at the first abdomen (3
3) and a vibration mode in which the ultrasonic horn head (8) forms the second abdomen (34).

That is, one of the features of the ultrasonic processing apparatus according to the present invention is that the ultrasonic horn head (8) has a longitudinal vibration amplitude U
₁ and the transverse vibration amplitude U ₂ , thereby facilitating the configuration of the minute concave portion provided in the container flange portion. If the ratio of U ₂ to U ₁ is less than 0.1, the minute concave portion becomes small. structure without exerting an effect of, when it exceeds 1.5, a possibility that the lateral vibration amplitude U ₂ is too large, the internal cracks in the horn portion (13) takes unreasonable vibration to the horn unit (13) is generated There are, the ratio of U ₂ and U ₁ is 0.1 to 1.5, preferably, 0.3 to 1 is suitable. To maintain such a vibration mode, the horn (13) has a square cross section,
It is difficult to generate in a rectangular shape such as a rectangle, and an ellipse or a circle, preferably a circle is good. In addition, the upper end surface (24) of the horn (13) and the lower end surface (2) of the booster (12).
2) is important, and this ratio is 3 to 50 times,
Desirably, by setting it to be 7 to 30 times, a lateral vibration amplitude can be generated.

Further, when the value U ₂ of the longitudinal vibration amplitude of the ultrasonic horn head (8) at the time of giving the horizontal vibration amplitude and the vertical vibration amplitude to be equal to _{each other} is less than 20 μm, the small concave portion of the container flange portion may be formed. On the other hand, the upper limit value of U ₂ varies depending on the material of the horn, but even in the case of the titanium alloy horn having the highest strength, if it exceeds 100 μm, both in the vertical and horizontal directions in the horn portion (13). Since excessive vibration may occur and cracks may occur, the appropriate amplitude value U
₂ is 20 to 100 μm, more preferably 30 to 50 μm
Is good.

The thermal conductivity of the horn portion (13) that vibrates at a high speed with ultrasonic waves is an important factor for forming a minute concave portion in the flange portion of the container (1) made of a thermoplastic resin. In the case of a metal having a high thermal conductivity, the frictional heat generated in the flange portion of the container (1) and the ultrasonic horn head (8) is taken away by the ultrasonic vibration, so that the melting effect is reduced and the processing is performed. Speed also slows. Conversely, if the thermal conductivity is too low, the frictional heat is excessively stored, the minute recesses become too deep or the homogeneity is impaired, and the flange itself of the container (1) is highly likely to be deformed. Suitable heat conduction ranges from 1.5 × 10 ^-2 to 30 × 10 ^-2 Cal / cm ² / sec /
C./cm is good. As a suitable metal, an aluminum alloy such as a titanium alloy or duralumin is desirable, and a titanium alloy composed of 6% aluminum, 4% vanadium and 90% titanium is more desirable.

The lower the ultrasonic frequency to be generated, the larger the value U ₁ of the vibration amplitude in the longitudinal direction can be. However, if it is less than 18 KHz, it will be heard by human ears, and if it is too high, the above-mentioned suitability will be obtained. Since a vertical amplitude value cannot be generated, it is preferably 18 to 38 KHz, more preferably 18 to 24 KHz.
KHz is good.

[0031]

According to the method of the present invention, it is possible to extremely easily and stably form a minute concave portion on the flange layer surface of the container body in a short time with high precision. The sealed container with the lid material heat-sealed on the flange part has a very stable and smooth peel feeling, and it is also very easy to heat-seal compared to the conventional one. A container having a stable peel feeling can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an easily-openable container obtained by the method of the present invention.

FIG. 2 is a perspective view of a container showing a state where a lid is half-opened.

FIG. 3 is a schematic view showing a step of ultrasonically treating a flange portion of a container body.

FIG. 4 is an enlarged sectional view (a) and an enlarged plan view (b) of the ultrasonic horn head.

FIG. 5 is an enlarged sectional view of a flange portion of the container body subjected to ultrasonic treatment.

FIG. 6 is a diagram (a) illustrating a configuration of an actuator unit of the ultrasonic processing apparatus of the present invention, a vertical vibration amplitude pattern (b), and a horizontal vibration amplitude pattern (c).

[Explanation of symbols]

 In the figure, 1: container body 2: container flange 3: lid material 4: seal layer 5: adjacent layer 6: sealant layer 7: minute concave portion 8: ultrasonic horn head 9: receiving die 10: actuator 11: vibrator portion 12: Booster section 13: Horn section 14: High-frequency cable 15: Ultrasonic vibration element

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 59/00-59/18 B65B 7/00-7/28 B65D 77/00-77/40

Claims (2)

(57) [Claims] 1. A container body having a flange formed from a multilayer sheet having a laminate strength of 300 to 2000 g / 25 mm between a sealing layer and an adjacent layer in contact with the sealing layer and a thickness of the sealing layer of 10 to 90 μm. Method of forming point-like minute concave portions having a pitch d of 0.3 to 0.8 mm over the entire circumference of the part surface and a depth d having a depth of d = 1 t to 10 t with respect to the thickness t of the seal layer. In the ultrasonic frequency 18 to 3
Ultrasonic treatment using a horn having a vibration mode of 8 KHz, a longitudinal amplitude of the horn of 20 to 100 μm, and a transverse vibration amplitude of 0.1 to 1.5 times the longitudinal vibration amplitude. A method for forming a minute concave portion on a flange portion of a container body. 2. The ultrasonic horn has a thermal conductivity of 1.5 × 10 <sup>−2.
2. The</sup> method according to claim 1, wherein the metal is in the range of from about 30.times.10.sup.- ² Cal / cm.sup.2 / sec / .degree. C./cm.