JP2013124119A - Easy-to-open plastic container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easy-to-open plastic container that has improved property of unsealing and prevents liquid splashing when the container is opened.SOLUTION: The plastic container has a sealing structure in which an opening is circular, a flange is provided, and a lid sheet is stuck to the flange. In the plastic container, part of the flange is provided with a wider portion. The stuck portion is formed in a shape of a letter V, which projects outward in this part.

Description

  The present invention relates to a round cup-opening plastic container having improved openability and liquid splash at the time of opening.

  The lid of the packaging container is sealed by thermal bonding using an adhesive or a heat seal technique.

  Solid-type packaging containers such as cups and trays require easy opening and liquid splash protection when opened.

  In a bag-like packaged product, the slack portion of the body portion can be picked and opened from the inside, but in the case of solid container packaging, it is difficult to pick the cover portion because the cover material of the flexible material is processed into a flat surface. Therefore, in the case of cup or tray packaging, a method is employed in which a tab is processed on a part of the outer side of the seal of the lid member, and this is picked and opened from the outside. Or the inside is cut using a cutter.

  In opening using a tab, the adhesive surface of the seal needs to be peeled off.

  Opening using a peel seal can be performed without special processing or the like by adjusting the peel length, adhesive strength, adhesive state, and the like. The actual opening is shown in the photograph of FIG.

  However, in the solid container packaging of liquid products, there is a problem that the filling material pops out due to an impact at the time of opening, and the clothes and surroundings are soiled. This defect is listed at the top of the universal design challenge.

  As shown in FIG. 2, peeling of the lid seal of the round cup, which is a representative of solid packaging, proceeds in a horizontal line as shown in FIG. 2 by pulling the tab of the opening tab, and starts from [1] and ends at [5]. [3] is a line where the opening force is minimized.

  Calculate the peel length between the four sections [1]-[2], [2]-[3], [3]-[4], [4]-[5] by the method shown in FIG. If this calculation result is doubled, the length of each peeled line is obtained. Multiplying the length of the peeled line by the adhesive strength of the adhesive surface provides the opening force.

The length of the peeled line at each part can be calculated by the following calculation.
That is, assuming that the opening distance is rpx, rpx is determined from [1] to [5] in FIG. 2 from the radius r1 of the seal portion inner periphery (seal inner circle) and the seal portion outer periphery (seal outer circle) radius r2 of the top surface flange portion of the cup. ], The following inequality holds.
(B) rpx≤ (r2-r1) (Restricted range of [1]-[2])
Between [1] and [2], the length L1 of the peeled line can be obtained by calculating the line segment ba from Δoba.

(ロ) r2≧rpx＞(ｒ2−ｒ1) （［２］−［３］の制限範囲）
この間は△odcの線分dcと△oecの線分ecの差を計算することで剥がれ線の長さを求めることができる。

(B) r2≥rpx> (r2-r1) (Restricted range of [2]-[3])
During this time, the length of the peeled line can be obtained by calculating the difference between the line segment dc of Δodc and the line segment ec of Δoec.

(ハ)（r2＋r1）≧rpx＞(ｒ2) （［３］−［４］の制限範囲）
この間はrpxとr2を入れ替えて、［２］−［３］と同様な計算をすればよいから

(C) (r2 + r1) ≧ rpx> (r2) ([3]-[4] restriction range)
During this time, rpx and r2 are interchanged and the same calculation as [2]-[3] can be performed.

(ニ)（2×r2）≧rpx＞（r2＋r1） （［５］−［６］の制限範囲）
この間はrpxとr2を入れ替えて、［１］−［２］と同様な計算をすればよいから

(D) (2 × r2) ≧ rpx> (r2 + r1) (Restricted range of [5]-[6])
During this time, rpx and r2 are interchanged, and the same calculation as [1]-[2] can be performed.

各開封位置の開封力は、開封距離（rpx）に数値を与えて求めた剥がれ線の長さを２倍にして、接着面の接着強さを乗じることによって、一連の開封力のグラフが得られる。
r1＝35mm、r2＝41mm（シール幅；6mm）の円形カップを一例として、開封距離(rpx)と剥がれ線の長さの関係を計算した結果を図４に示した。開封の剥がれが直径点に到達すると（図２の［３］ライン）、剥がれ幅は（r2-r1＝6mm）となり、剥がれ線の長さは12mm（6mm×2）となる。開封強さの全パターンはこの点を中心にした対称形になっている。例えば接着強さが6Ｎ/15mmとすれば、実際の開封力は、6×剥がれ線の長さ÷15(Ｎ)となる。

The opening force at each opening position is obtained by doubling the length of the peeled line obtained by giving a numerical value to the opening distance (rpx) and multiplying by the adhesive strength of the adhesive surface to obtain a series of opening force graphs. It is done.
FIG. 4 shows the result of calculating the relationship between the opening distance (rpx) and the length of the peeled line, taking a circular cup of r1 = 35 mm and r2 = 41 mm (seal width: 6 mm) as an example. When the opening peel reaches the diameter point ([3] line in FIG. 2), the peel width becomes (r2-r1 = 6 mm), and the length of the peel line becomes 12 mm (6 mm × 2). All patterns of opening strength are symmetrical about this point. For example, if the adhesive strength is 6 N / 15 mm, the actual opening force is 6 × length of peeled line ÷ 15 (N).

  From the observation of FIG. 4, it can be seen that the opening force of the lid of a circular solid packaging such as a cup is increased immediately after the opening and immediately before the opening. In addition, a large change in opening force is recognized immediately after opening and immediately before closing.

  In flexible packaging such as bag packaging, the stress at the two pick points is in the opposite 180 ° direction, but the opening surface of the solid packaging and the stress direction in the operation are 90 ° perpendicular to each other. This shows that the opening direction and the liquid splash direction are the same, and the opening operation is directly linked to the occurrence of liquid splash.

  In the case of solid packaging, since the opening surface and the opening direction are 90 °, the opening operation amount and the peeling length are the same, whereas in the flexible packaging, the opening operation amount and the peeling length are 1: 2. The work rate for both opening is 1 for solid packaging, and 1/2 for flexible packaging, and the opener feels that the flexible packaging is sensually easier.

  The conventional problem is that the mechanism analysis of the opening operation is insufficient, and the accurate analysis / evaluation of the openability of the solid packaging and the liquid splashing mechanism is insufficient.

  As described above, today, solid containers and packaging represented by cups and trays have difficulty in opening the lid, and the liquid content jumps or pops out during the opening operation. Has become a major problem.

  In fact, as shown in FIG. 5, since the liquid splash and spill are scary, the inconvenient usage that stops the opening in the middle is even established by consumers.

  For the evaluation of openability of solid packaging such as the lid seal of cup packaging, JIS Z 023 and ASTM F88 tensile test methods are applied, and evaluation focusing on opening strength is applied. It cannot be applied to the analysis and evaluation of the unsealing characteristics and the cause of liquid splash.

  There is a demand for a rational investigation and response to the mechanism of the opening force and the cause of the impact that is the cause of the liquid splash.

The inventor has invented the following method from the analysis of the geometric structure of the adhesive surface governing the opening force and the impact mechanism generated by the opening operation.
(1) A V-shaped seal composed of a tangent line circumscribing the inner and outer circles of the seal surface is applied near the start and end of opening.
(2) A design method was invented in which the length of the protruding portion of the V-shaped seal at the opening start site was arbitrarily set, and the maximum opening force could be asymptotic to (peeling length) × 2 × (adhesion strength).
(3) Applying a V-shaped seal to the site immediately before the end of opening, and releasing the opening energy accumulated in the bending of the hand by the opening operation by adjusting the height of the triangular adhesive part at the V-shaped tip We have invented a method to prevent the splashing of impact generated by operation.
(4) The inventors have invented a method for setting appropriate sealing conditions for easy opening and liquid splash prevention by selecting heat seal width, heat seal strength (adhesion strength), and V-shape.
Accordingly, the present invention provides a plastic container in which the opening is circular and has a flange portion, and a lid sheet is bonded thereto to form a sealed structure. A wide portion is provided in a part of the flange portion, and the bonding portion is The plastic container and the wide portion are formed in a V-shape protruding outward in the portion, and are provided at two locations facing each other, both of which have an adhesive portion protruding outward in the portion. The above-mentioned plastic container formed in a letter shape is provided.

(1) The maximum opening force of the circular seal portion was reduced with the V-shaped configuration of the seal portion immediately after the opening of the opening.
(2) Apply the same V-shaped seal immediately before opening, and adjust the depth of the V-shaped seal (V-shaped depth) to adjust the height of the triangular seal (rx2). Defend.

It is a photograph which shows the place which opened the cup sealed with the lid sheet. It is a top view explaining peeling of the conventional cup. It is a figure explaining peeling of the conventional cup. It is a graph which shows the relationship between the opening distance of the peeling of the conventional cup, and the length of a peeling line. It is a photograph which shows the state which opened and uses the cup sealed with the lid sheet. It is a figure which shows schematic structure of an opening simulator. It is a graph which shows the relationship between the tensile strength and extension of a spring used with the opening simulator. It is a figure explaining peeling of the cup of one Example of this invention. FIG. It is a graph which shows the relationship between the opening distance of the cup of this invention, and the conventional cup, and the length of a peeling line. It is the graph which changed the heat seal width | variety and showed the relationship between the multiple of the width | variety, and the length of a peeling line, respectively. This is illustrated by changing the depth of the V-shape. It is the graph which changed the depth of V character and calculated | required the relationship between heat seal strength and opening force, and compared with the circular seal. It is a top view which shows the example of the lid seal | sticker of this invention.

The heat seal strength (adhesion strength) and the length of the peel-off line of the heat-sealed part dominate the heat-sealing ability of the heat seal. On the circular seal surface, the length of the peel-off line is the heat seal. It changes as the peeling of the part progresses. On the other hand, the heat seal strength and the heat seal width are usually already designed and implemented in any container to which the present invention is applied. In the present invention, a V-shaped portion is provided in the heat seal portion, and furthermore, the heat seal strength and the heat seal width are adjusted as necessary to improve the unsealing property and the liquid splash at the time of opening. As shown in FIG. 4, the length of the peeled line becomes maximum when the peel comes into contact with the inner circle of the heat seal portion, and requires a large opening force, resulting in a problem of deterioration in opening and liquid splash. It was. In the present invention, these problems are solved by reducing the peak of the length of the peeled line by making it V-shaped.
In the present invention, it has been found that the impact source for the occurrence of liquid splash is the elasticity (deflection) of the hand of the picking and unsealing operation. That is, energy proportional to the tensile strength is accumulated in the picked muscle. When the adhesive part disappears at the end of opening, this energy is automatically released at once by restoring the bending of the human hand (spring), so the packaging container moves in the restoring direction at high speed while receiving the action of inertia force by its own weight. . In a liquid in which the filling is easy to move freely, this acceleration causes the material to jump up. It is necessary to confirm the effectiveness of the liquid splash protection by actual opening operation. Modeling is shown in FIG.

Using the opening simulator shown in FIG. 6 (Japanese Patent Application No. 2011-149953) that simulates the opening characteristics of human hands, various conditions related to impact and liquid splash that occur when opening a 5 ml coffee milk container that is light and susceptible to impact. Table 1 shows an example of the investigation.

  The opening force of the adult male was 20 N, and springs having the elastic characteristics of FIG. 7 were attached to the top and bottom of the object as springs that would cause an extension of 5 to 10 mm at this time. The pulling speed was 400 mm / min, and the opening distance of the opening simulator was adjusted so that the generated G value was an integer step from 10 to 60 G, and the spring was displaced. This was released at a stretch to give an impact to the coffee milk container, and the state of the liquid splash was visually observed. For acceleration generated in the container, a minute acceleration sensor was installed at the bottom of the container. Since the acceleration changes depending on the weight of the container and the inertial force of the measurement system weight, the acceleration decreases as the weight increases. The total weight of this measuring system is about 20 g. From this result, it was found that the liquid splash defect can be adjusted as a practical level by limiting the acceleration to 0.1 to 30G. The load was read from the load meter display of the simulator tensile tester. The displacement was read from the tensile distance of the tensile test. Unsealing energy = (load) × (displacement). The relationship between load and displacement is shown in FIG.

  In order to reduce the influence of liquid splash, the vertical impact generated at the time of opening needs to be 0.1 to 30G. From this confirmation experiment, it was found that the stored energy of the spring must be 0.1-2 mJ.

The case of Table 1 is a case where the opening operation energy accumulated in the spring is released at once.
If this stored energy is reduced linearly (V-shaped) over time and converted into peeling energy, the occurrence of impact can be reduced.
From this result, the V-shaped depth (rx1), the heat seal strength and the heat seal width are set so that the G value is 0.1 to 30 G, preferably 0.1 to 20 G, more preferably 0.1 to 10 G.

  The V-shaped depth (rx1) can be arbitrarily selected. rx1 is a variable of triangle height and base length (Lb) at the tip of the V-shaped seal. The depth of the V shape at the opening start portion is determined from the setting limit of the opening force. The depth of the V shape at the end of opening is determined based on the reduction in the occurrence of impact. It is not necessary to match rx1 of the opening start part and the opening end part. In either case, if rx1 is increased, the expected effect is increased, but the flange dimension of the V-shaped part is increased, so it should be slightly larger than the limit dimension of rx1. (Refer to Table 3 of Implementation Examples)

The relationship between the shape of the V-shaped seal and the length of the peel-off line of the opening will be described with reference to FIGS.
(I) An opening base point and an opening end point are set on the center line of the seal circle of the cup.
(Ii) The shortest distance between the inner circle of the seal and the inner vertex of the V-shaped seal is rx1. This is called the depth of the V shape. rx1 can be set arbitrarily and becomes a variable for determining rx2 and Lb.
(Iii) Draw a tangent CD from the tip point C of rx1 to the circle inside the seal.
(Iv) Draw the tangent line BA of the outer circle of the seal parallel to the tangent line CD. Thus, the seal width (r2-r1) of the V-shaped seal portion is the same as that of the circular portion.
(V) A line segment CB composed of a tangent CD and a tangent BA on an extension line of rx1 is defined as rx2. This is called the height of the triangular seal, and the length of this line is related to the liquid splash adjustment.
(Vi) The line segment HC (Lb) formed perpendicular to the contact point of rx1 and rx2 is the maximum value (maximum opening allowance) of the V-shaped seal peeling length.
(Vii) The actual V-shaped seal is constructed symmetrically about rx1 + rx2 (line segment; EB).

  In order to reduce the maximum opening force at the start of opening, it is first necessary to reduce the maximum value of the length of the above-mentioned peeled line, which is to increase the V-shaped depth (rx1) or heat seal width (r2 This can be achieved by reducing -r1) and designing Lb (segment HC) small.

  In order to reduce the impact on the container being opened, increase the height rx2 of the triangle (HCB) at the tip of the V-shaped seal so as not to release the elongation of the opening operation system (elastic system) at once. To.

The change in the length of the peel line that progresses when the V-shaped seal is opened is divided into three categories.
(A) V-shaped parts rx2 to rx1 to rx3 that peel linearly
(B) rx3 to rx4: V-peeling linear part and the minute part of the connection between the circular part (c) rxn> rx4 is the peeling part of the circular seal
The effect of the V-shaped seal is that the opening force at the time of opening can asymptotically approach the minimum circular value by increasing the distance rx1 from the E point of the inner circle to the valley of the V-shaped seal.

  And by applying the same V-shaped seal shape to the part immediately before the end of opening, the release of the opening force accumulated during the opening operation is linearly reduced, the generation of impact force is reduced, and the liquid splash control Is possible.

Calculation of the dimensions of each part is performed by the following method.
Formula for rx2: Calculate from the similar form of ΔODC and ΔOAB.
r1 and r2 are arbitrarily given, and the line segments CD and BA are tangent lines of the inner circle of the seal and the outer circle of the seal with the points C and B as the base points.
(r1 + rx1) / r1 = [(r1 + rx1) + rx2] / r2
(r1 + rx1) r2 / r1 = (r1 + rx1) + rx2
rx2 = (r1 + rx1) × (r2 / r1−1) (5)

≪Formula for length of peeled line of V-shaped part≫ Calculated from trigonometric function of θ1 of ΔODC
JC // AD
L0 / Lb = sinθ1, cosθ1 = r1 / (r1 + rx1)
Lb = L0 = (r2-r1) / sinθ1 = (r2-r1) / sinθ1 (6)

<< Calculation formula of rx3, rx4 >>: Calculated from the trigonometric function of ΔODC and ΔOAB θ1
(r1−rx3) / r2 = cosθ1
rx3 = r1− (r2 × cos θ1) = r1− [r2 × r1 / (r1 + rx1)] = r1 [1-r2 / (r1 + rx1)] (7)
(r1−rx4) / r1 = cos θ1
rx4 = r1− (r1 × cos θ1) = r1− [r1 × r1 / (r1 + rx1)] = r1 [1-r1 / (r1 + rx1)] (8)
As mentioned above, although the case where the adhesion part was formed by heat sealing was described, it cannot be overemphasized that this invention is applicable also to the case where a lid sheet is adhere | attached using an adhesive material.

(1) Confirming the optimum shape of the V-shaped seal Under the common conditions of r1 = 35mm, r2 = 41mm, (seal width = 6mm) in the opening force simulation formulas (5) to (8), rx1 = 7mm and 10mm FIG. 10 shows an example of a calculation result of the opening force pattern in which a V-shaped seal is applied to the opening start site and the opening completion site. The maximum peel line length of the circular seal was 43 mm, while that of the V-shaped seal was 19 mm when rx1 was 7 mm; 22 mm and 10 mm. It was found that the selection of the V-shaped seal rx1 can control the decrease in the length of the peeled line immediately after the opening and immediately before the opening (decreasing the opening force).

(2) Confirmation of optimum shape of V-shaped seal depth (rx1)
Heat seal width of r1 = 35mm; 3,5,7mm, heat seal width of r1 = 15mm; To evaluate the calculated results of peeled line length Lb in two cases of 2,3,4mm in common for each condition When rx1 / heat seal width is indexed, it is as shown in FIG.
The results are summarized as follows.
<1> When the seal circle becomes larger, the opening force increases.
<2> The opening force increases as the seal width increases.
<3> When rx1 increases, the opening force decreases and gradually approaches (seal width × 2) of the circular portion.

  It can be seen that when rx1 is increased, the length of the peeled line becomes asymptotic to the seal width × 2. However, even if rx1 is increased unnecessarily, the effect is not proportional, and the V-shaped seal becomes larger and the product shape becomes unnatural. Therefore, in practice, it is recommended to select a heat seal width of 0.75 to 2. .

Generally, the tensile strength of JIS Z 0238 is applied as the adhesive strength. In this method, the adhesive strength of 15 mm width is defined, and accordingly, the opening force is confirmed by [(length of peeled line) / 15 mm] × (heat seal strength).
For easy opening by hand, a combination of three elements: seal width, V-shaped depth and heat seal strength so that the maximum strength is 4-15N, preferably 4-10N Determine each of them.

  The heat seal strength can be adjusted within a range smaller than the material specific cohesive bond strength by adjusting the welding surface temperature. (Reference: Japanese Patent No. 3457441)

(3) Confirmation of best shape of V-shaped seal for liquid splash control To minimize the occurrence of liquid splash, it is necessary to set the vertical acceleration generated by the manual opening speed to 0.1-30G. Check if the shape of the V-shaped seal has a liquid splash prevention function.

  The V-shaped sealing surface applied to the unsealing end portion is composed of a triangle at the tip and a band-shaped adhesive surface. When this part is modeled, it becomes a combination of a quadrilateral and a triangle with the maximum peeling length of the V-shaped seal as one side. (See Figure 12)

Since [(maximum peeling length) / 15] × heat seal strength = opening force, [(opening force) × (extension length) = impact energy source] of the opening elastic system is obtained.
The extension amount of the spring corresponding to the opening force is read from a simulation model (see FIG. 7) of a human opening system. If the peeling allowance (rx2)> (spring extension allowance) larger than the spring allowance is set, the residual energy is not released at a stretch, but can be converted into the peel energy linearly, and the impact applied to the container can be reduced.

  As a model, a model of a V-shaped seal with 2Lb = 15 mm, rx2 = 3, 10, 15 mm, and adhesive strength (7 N / 15 mm) is shown in FIG. Applying the opening simulator shown in Fig. 6, applying a peeling speed of 400mm / min (6.7mm / s), applying a spring constant of 5mm / 10N, peeling strength (opening force) in progress, container acceleration (0.5 The acceleration test of g) was carried out and a peeling test was conducted. Table 2 shows the measurement results of the generated impact and the residual force at the time of release.

  Here, the remaining opening force is an actual value (extracted from a recorder) of the load remaining at the end of opening. The release of this remaining load becomes the energy for generating the impact. In order to reduce this to 0, in order to minimize the energy stored in the spring, it is necessary to peel off at an extremely low speed.

  From this result, when the height (rx2) of the triangular part smaller than (4mm) equivalent to the deformation allowance (deflection) of the human hand is 3mm, 6.7N close to the previous accumulated load is released at a stretch and a 30G impact occurs. . 10mm covers accumulated deformation (4mm), but a residual load of 1.8N remains, resulting in an 18G impact. At 15mm, almost all residual energy is digested. Since the impact is 18G at 10mm and 9G at 15mm, it can be seen that the design method of the V-shaped seal is functioning.

  From the above results, the inner depth of the V-shaped seal is set to 0.7 to 2.0 times the seal width for easy opening. Preferably it is 1.0 to 2.0 times.

  To prevent splashing at the end of opening, the height (rx2) of the triangular seal at the tip of the V-shaped seal is set to be greater than the elastic allowance.

  The opening energy that is retained depends only on the opening force [(stripping line length) x (heat seal strength)], so if the container's own weight (including the contents) increases, the inertia force increases. Since the acceleration generated in the container decreases, the setting of (the height of the triangular seal portion)> (the elongation margin of the elastic system) works well to achieve the purpose if the container becomes heavy.

(4) Confirmation of the relationship between the relational variables and the parameters The relationship between the elements related to easy opening and splash protection was confirmed.
<1> The triangle height rx2 at the tip of the V-shaped seal is calculated using equation (5), with rx1 as a variable.
<2> The maximum value Lb of the length of the peeled line is calculated using Equation (6) with the inner circle, outer circle and rx1 of the seal circle as variables.
<3> The opening force is calculated by multiplying the maximum value Lb of the peeled line length by the adhesive strength / heat seal strength applied.
<4> For the deformation of the hand, the displacement due to the opening force is read with reference to the elasticity characteristics of the simulation model shown in FIG.
<5> The liquid splash prevention condition finds the establishment range of the relationship of (the height of the triangular seal portion; rx2)> (elastic system elongation).
<6> The appropriateness of the opening force refers to the opening force, and determines whether or not it is necessary to apply a V-shaped seal with an upper limit of 15N.
<7> With reference to the opening force, each condition set to 2 to 10 N of an easy opening force is verified.

Table 3 shows the calculation results of an example where r1 = 35 mm, r2 = 38 mm, and heat seal strength = 7 N / 15 mm.
In this example, rx1 = 0 is when the circular seal remains. Since the opening force at this time is 14 N, it is possible to open the hand manually, and it can be seen that the V-shaped seal at the opening start portion is not necessarily required. On the other hand, the liquid splash protection condition at the end of opening is rx2 less than 3.48 mm when the elastic extension is less than 3.4 mm. Therefore, a V-shaped seal with rx1 of 5.5mm or more is required.
Aiming for easier opening, if the opening force at the start of opening is 10N, rx1 can be achieved by applying a 1.5mm V-shaped seal on the opening side. If this table is collected and applied at the time of design, failure of proper easy opening and liquid splash protection can be eliminated.

The size of the opening of the container, the heat seal width, and the heat seal strength dominate the easy-opening and liquid splash protection. r1 = 35mm, r2 = 38mm, heat seal strength; rx1, necessary for adjustment, with heat seal strength as a variable under the conditions of 4,5,6,7,8,9,10N / 15mm FIG. 13 shows the relationship between the circular opening force and the maximum opening force of the V-shaped seal for preventing splashing.
When the heat seal strength exceeds 7N, the circular opening force exceeds 14N, but the opening force at the end of opening is controlled to be less than 6N even when the heat seal strength is 10N by the V-shaped seal.
The depth of the V-shape is ≒ 10mm when the heat seal strength is 10N.

The dimensions of the opening of the container were set to r1 = 35 mm, r2 = 38,41 mm, r1 = 15 mm, r2 = 17,18 mm, and changes in the size of the opening, the V-shaped seal and the circular opening force were examined.
Table 4 lists only the maximum opening force of rx1 that satisfies the maximum opening force of the circular shape of each dimension and when the liquid splash control is possible (the height of the triangular seal; rx2)> (elastic system elongation). did.

この表から円径、シール幅サイズとヒートシール強さが液跳ね防御の適否に大きく関与していることが分かった。開封力を小さくするためにはヒートシール強さを小さくすればよいが、物流中の振動や落下衝撃でシール面の破損、安定したヒートシール強さを維持するためにはヒートシール強さは4N／15mm以上が好ましい。
r1＝35mm、r2=41mmの条件ではヒートシール強さ4N/15mmの場合でも開封力が10Nを超えており、この条件では開封性も液跳ね調節も難しいことを示している。
好適なシールには、シール幅が6mmより小さくて、ヒートシール強さが8〜4N/15mmの制限選択が好ましい。

From this table, it was found that the circle diameter, the seal width size and the heat seal strength are greatly related to the suitability of the liquid splash protection. In order to reduce the opening force, the heat seal strength should be reduced. However, to maintain stable heat seal strength, the heat seal strength is 4N to maintain the stable heat seal strength due to vibration and drop impact during logistics. / 15 mm or more is preferable.
Under the conditions of r1 = 35mm and r2 = 41mm, even when the heat seal strength is 4N / 15mm, the opening force exceeds 10N, which indicates that it is difficult to adjust the opening and liquid splash.
A suitable seal is preferably selected with a seal width of less than 6 mm and a heat seal strength of 8-4 N / 15 mm.

  From these results, the parameters of seal width, heat seal strength, and rx1 could clarify the relationship between easy opening and liquid splash prevention function, and an accurate selection method (design method) of three elements was presented.

  In this example, the analysis was performed with the manual opening elasticity of 5 mm / 10 N. It is within the scope of the present invention to change this reference value in accordance with the purpose.

A tab is indispensable at the opening start site, but a tab is not necessary at the opening end site.
On the end side, the lid material may be cut at the limit of the seal line. And it is good not to make a mistake in the opening location. An example is shown in FIG.

  Since the restriction of the opening force at the start of opening is smaller than the opening end portion, the V-shaped seal at the opening start portion may be unnecessary. In this case, apply a V-shaped seal only at the end of opening. (See FIG. 14 (B)) A part of the outer side of the V-shape at the start of opening may be cut from the viewpoint of design. (See Fig. 14 (C))

  Since the present invention provides a plastic container that can be opened smoothly and does not splash, it can be widely applied to plastic containers that are sealed with a lid.

r1 Seal inner circle radius
r2 Seal outer circle radius
r2-r1 seal width; [L0]
rx1 V-shaped depth
rx2 triangle seal height
rx3 From the inner circle of the seal up to the intersection of the horizontal line and the center line of the tangent of the outer circle of the seal
distance
rx4 Distance from seal inner circle to intersection of horizontal line and center line of tangent line of inner circle of seal
rpx opening distance
Symbolization of L0 r2-r1
L1 Peeling line length
L2 Length of peeling line when peeling progresses beyond the tangent to the circle inside the seal
L3 Length of extension line of peeling line when peeling progresses beyond the tangent to the circle inside the seal
Maximum length of Lb peel line θ1 Angle between tangent line of peel line (Lb) and outer circle of seal

Opening force = Adhesive strength x Peeling length Peeling width = Peeling length / 2
Adhesive strength = heat seal strength

Claims (4)

  In a plastic container in which the opening is circular and has a flange portion, and a lid sheet is bonded to the sealed structure, a wide portion is provided in a part of the flange portion, and the adhesive portion is outside in the portion. Plastic container characterized by being formed in a V-shape projecting toward the side   2. The plastic container according to claim 1, wherein the wide portion is provided at two locations facing each other, and the adhesive portion is formed in a V shape protruding outward at the portion.   3. A plastic container in which the inner depth of one of the V-shaped adhesive portions according to claim 1 is 0.75 to 2 times the adhesive width.   The plastic container in which the height of the triangular adhesive portion at the tip of one of the V-shaped adhesive portions according to claim 1 or 2 is larger than the elastic extension.

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