JP4802391B2 - Plastic foam sheet with improved stiffness - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic foam sheet having improved rigidity, commonly referred to as “waist”. In the present invention, the term “bubble sheet” is used to include a thick product called “bubble board”.
[0002]
[Prior art]
A plastic bubble sheet (hereinafter abbreviated as “bubble sheet”) in which a flat back film is bonded to the bottom of a cap film cap provided with a large number of caps by vacuum forming of a plastic film is mainly used in the field of cushioning packaging materials. And some are widely used in the field of insulation. There is also a so-called plastic bubble board, which is a thick film in a region called a sheet, which is used as a building material.
[0003]
Whether the sheet is thin or thick, the conventional bubble sheet has a circular shape in the planar shape of the cap. One of the reasons for choosing a circle is that it is easy to produce a forming roll that performs continuous vacuum forming, and another reason is that the product has a good aesthetics. An array of circular caps is usually called “staggered arrangement” in which one row of caps is arranged on a line parallel to the axis of the forming roll, and the next row of caps is arranged with a half-pitch shift. This is a structure selected mainly for manufacturing convenience.
[0004]
Although there are some differences depending on the material to be used, the air bubble sheet is generally low in rigidity or self-sustainability except for a case where a particularly thick sheet is used as a material, and is so-called weak. Therefore, it is very inconvenient to handle when unwinding and unwinding, which is a commercial product form. In particular, in the bubble sheet having the caps of the conventional staggered arrangement, there is only a laminated film between the rows of caps arranged in a straight line, so the lines in the three directions shown in FIG. It breaks easily.
[0005]
Thus, as one modification, a bubble sheet having an elliptical cap has been prototyped. As shown in FIG. 2, this product strongly resists bending in the direction along the broken line, but has no power against bending in the direction along the solid line.
[0006]
Some bubble sheets have a three-layer structure in which the top of a cap film is connected and another flat plastic film is bonded as a liner sheet. Of course, a product with this structure is expensive, but it requires more materials, consumes resources, and increases the number of manufacturing processes.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a product that has resistance to bending in all directions in a bubble sheet, that is, a stiff product having rigidity in all directions on the surface.
[0008]
[Means for Solving the Problems]
The bubble sheet of the present invention that achieves the above object is a bubble sheet in which a flat back film (2) is bonded to the bottom surface of a cap film (1) provided with a large number of caps by vacuum forming of a plastic film. 3A and 3B, the planar shape of the cap is a V-shape, and the directions of the caps arranged side by side are (3a, 3b,... And 4a, 4b,. .. Column) It is characterized by the fact that both ends (31, 32) of the V-shaped caps are opposed to each other and enter the inside of the V-shaped caps (4b) of the opposed columns, thereby improving It is a bubble sheet with high rigidity.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
With the above configuration, in FIG. 3A, the line passes through the rising edge of the cap in any of the directions indicated by the lines written in FIGS. 1 and 2. That is, there is no portion on the line where the cap film and the back film are bonded together, and a bubble sheet that is strong in all directions can be obtained.
[0010]
Both ends (31, 32) of the V-shaped cap preferably draw a semicircle as shown in FIG. If you create a part that bends rapidly, in other words, a part that has a very small radius of curvature, it tends to be a weak point. This is also true for the shape of the V-shaped apex (33) of the cap, so that the portion is preferably rounded. The V-shaped apex angle (α) can be 80 to 130 degrees, but is preferably about 100 to 110 degrees.
[0011]
The shape of the V-shaped cap is a semicircular shape with a radius of curvature R at both ends, the width of one side of the V-shape is W, the distance between the center of the semicircle at the end and the intersection of the center lines of both sides is P ₁ , the cap, that is, when the sign (3a, 3b, ···) and (4a, 4b, · · ·) of the distance between the two sides of the center line and _{P 2,} these values, the following relationship It is preferable that
P ₁ > P ₂ 2W ≧ P ₂ > W 5W ≧ 10R ≧ W
[0012]
The air bubble sheet of the present invention gives rigidity to a two-layered cell sheet composed of a cap film and a back film, but the above-mentioned three-layer cell sheet, that is, the top of the cap, Of course, the present invention can also be applied to a bubble sheet obtained by bonding a flat plastic film as a liner sheet.
[0013]
As mentioned at the outset, the improved rigid foam sheet of the present invention is particularly suitable when applied to cap and back films and, if present, thin products having a maximum liner film thickness of 100 μm or less. The significance is great. In this case, each film can be thinned to the extent that it can be manufactured or to the extent that the required strength is obtained. On the other hand, when applied to a cap film and a back film, and a thick product having a minimum liner film thickness of more than 100 μm, if present, an extremely strong air bubble sheet can be obtained against buckling in all directions. In terms, it is still useful.
[0014]
【Example】
The cap-shaped double-layered cell sheet shown in FIG. 3 was manufactured using polyethylene as a material with the following dimensions.
Cap film thickness: 35 μm Back film thickness: 15 μm
P ₁ : 17 mm P ₂ : 12 mm W: 10 mm Cap height: 4 mm
[0015]
For comparison, a conventional circular cap bubble sheet was produced with the following dimensions using the same material, the same film thickness.
Cap diameter: 10mm Cap height: 4mm
Pitch: 11.5mm staggered arrangement [0016]
The rigidity of these two types of bubble sheets was measured by a cantilever type test method. The results were as follows. (Unit kgf · mm)
Example V-shaped cap: 320 Comparative example circular cap: 110
[0017]
【The invention's effect】
The bubble sheet of the present invention is a V-shaped cap that has never been used in the past, so that the opposite rows face each other, and both ends of the V-shaped cap are inside the V-shape of the counterpart V-shaped cap. As a result of the arrangement, the cap exists on a straight line in every direction and resists bending, resulting in high rigidity.
[0018]
Therefore, even if the air bubble sheet of the present invention is composed of a thin film as much as possible, it has sufficient rigidity in all directions and is easy to handle. In this way, the most effective use of resources is possible, and there is a benefit that the impact on the environment can be minimized upon disposal after use. On the other hand, if it is formed of a thick sheet, it is possible to achieve high strength with isotropic property, which is difficult to buckle against stress in all directions, and therefore it is advantageous to use a bubble sheet as a structural material.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of arrangement of caps for explaining a lack of rigidity of a typical product of a conventional bubble sheet.
FIG. 2 is a plan view similar to FIG. 1 for explaining the rigidity of a conventional change mode of a bubble sheet.
FIGS. 3A and 3B are diagrams showing the shape and arrangement of a cap for an example of the bubble sheet of the present invention, in which A is a plan view corresponding to FIGS. 1 and 2, and B is a cross-sectional view taken along line II in FIG.
4 is an explanatory view showing a preferable relationship between dimensions of each part of the bubble sheet of FIG. 3;
[Explanation of symbols]
1 Cap film 2 Back film 3a, 3b, 3c Cap (one row)
31, 32 Both ends 33 Vertex 4a, 4b Cap (the other row)
R The radius of curvature W of the end of the V-shaped cap W The width P of _one side of the V-shape P ₁ The distance between the center of the semicircle at _one end and the intersection of the center lines of both sides P ₂ The distance α between the center lines of the two sides of the opposing cap V-shaped vertical angle

Claims (5)

A plastic bubble sheet in which a flat back film is bonded to the bottom surface of a cap film cap which is provided with a large number of caps by vacuum forming of a plastic film. A plastic bubble sheet having improved rigidity, wherein the orientations of the two are opposite to each other in a row, and both ends of the V-shape enter the inside of the opposing V-shape. Both ends of the V-shaped cap are semicircular with a radius of curvature R, the width of one side of the V-shape is W, the distance between the center of the semicircle at the end and the intersection of the center lines of both sides is P ₁ , and the opposing caps when the distance between the two sides of the center line and P _2, these values, a plastic bubble sheet according to claim 1 satisfies the following relationship.
P ₁ > P ₂ 2W ≧ P ₂ > W 5W ≧ 10R ≧ W The plastic foam sheet according to claim 1 or 2, wherein the top of the cap is connected and another flat plastic film is bonded as a liner sheet to form a three-layer structure. Cap film and the back film, also a plastic bubble sheet according to any one of claims 1 to 3 case is thin plastic bubble wrap maximum thickness less 100μm liner film present. The plastic foam sheet according to any one of claims 1 to 3, which is a thick plastic foam board having a minimum thickness of a cap film and a back film and, if present, a liner film exceeding 100 µm.

Images