JP2002052634A - Plastic foam sheet with low adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive foam sheet with low adhesion with such advantages that the adhesion is easily adjusted and the destructive burst of the foam sheet is avoided even when the sheet is released after it is bonded, in the foam sheet with an adhesive applied in a specific pattern to the surface so as to improve the handling ease of the plastic foam sheet. SOLUTION: An adhesive with low adhesion is applied in a linear fashion per block arranged at a specified pitch, on the flat area of the plastic foam sheet with numerous formed closed cell air chambers, obtained by laminating a cap film having numerous recessed parts formed of a plastic film by vacuum molding and a flat back film together at the bottom area of a cap. The adhesion of each of the blocks is adjusted by increasing/decreasing the ratio of an area where the adhesive is applied in a linear fashion to the total area of the block. This application of the adhesive in a linear fashion contributes to lessening the risk that the foam sheet might be broken when the sheet is released. It is desirable that the foam sheet be perforated for tearing and the position of the perforation aptly meet the arranged block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic foam sheet (hereinafter referred to as "bubble sheet") provided with a weak tackiness by partially applying a weak tackiness adhesive.

[0002] In the present invention, a "bubble sheet" refers to a closed air chamber formed by laminating a cap film in which a number of dents are formed by vacuum molding of a plastic film and a flat back film on the bottom surface of the cap. It refers to a processed product provided in large numbers. Connect the top of the cap,
There is also a foam sheet having a three-layer structure in which one flat liner film is laminated, and this is also included in the foam sheet of the present invention.

[0003]

2. Description of the Related Art In the main use of a bubble sheet, that is, in a cushioning package, when an air bubble sheet is directly fixed to an object to be packaged, or when the ends of a bubble sheet wound around an object to be packaged are fixed, usually an adhesive tape is used. Is used. Although such an adhesive tape depends on its type and usage, it is not very aesthetically pleasing and is not very convenient to use. If sticking is performed without using an adhesive tape, there is nothing better than that. Even if ultimately relying on an adhesive tape, there is a case where temporary fixing is desired for the time being, and it is desirable to be able to perform temporary fixing, especially when a large packaged object is to be packed alone.

Therefore, an attempt has been made to apply an adhesive to the foam sheet. However, if the adhesive strength is too strong, unintended adhesion caused by inadvertent contact severely hinders operations such as packing and the like, and the foam sheet cannot be used. It has been experienced to cause damage.

Attempts have been made to solve this problem by selecting an adhesive with low adhesion, but it has not been successful. Attempts have been made to apply the adhesive in a specific pattern rather than the entire surface of the foam sheet, but delicate control is required to achieve appropriate adhesive strength. The most troublesome thing is that if the sticking is performed to the extent that the sticking is effective, the back film of the bubble sheet often breaks when the bubble sheet is peeled off to correct the sticking position, or the cap of the cap film is It may be crushed and lose its performance as a bubble sheet.

In general, the cap film of the bubble sheet is extruded relatively thickly (30 to 70 μm for ordinary products), but the cap portion is stretched and thinned, and the back film is extruded thinly (also 15 to 35 μm). However, it does not withstand peeling after applying a somewhat strong adhesive. Increasing the thickness of the film that makes up the foam sheet can address this problem to some extent, but it means extra material consumption, which is uneconomical and wastes resources.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems associated with the use of an adhesive for enhancing the usability of a bubble sheet, and to provide an adhesive application in which a specific pattern is selected. It is an object of the present invention to provide a low-adhesive pressure-sensitive adhesive foam sheet in which force can be easily adjusted and the foam sheet can be prevented from being catastrophically torn even when peeled after adhesion.

[0008]

The weak adhesive plastic foam sheet of the present invention comprises a foam sheet, that is, a cap film in which a number of depressions are formed by vacuum forming a plastic film, and a flat back film on the bottom surface of the cap. Each of the blocks is formed by applying a weakly-adhesive adhesive in a linear pattern to each of the blocks arranged at a predetermined pitch on a flat surface of a molded product having a large number of sealed air chambers attached to each other. Is adjusted by increasing or decreasing the ratio of the area where the pressure-sensitive adhesive is linearly applied in the entire area of the block.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a weak tacky adhesive, a composition containing a rubber component, a tackifier and a liquid component is suitable.

As the rubber component, a natural rubber or a synthetic rubber can be used, but a material classified as a thermoplastic elastomer, more specifically, a material such as ethylene-propylene rubber is more suitable. EVA resin can also be used as this component.

[0011] The tackifier is a main component that imparts adhesive strength to the composition, and is made of petroleum and has 5 to 7 carbon atoms.
Among those obtained by low-temperature polymerization of unsaturated hydrocarbons,
You will find something appropriate. In some cases, a natural glue line tackifier may be useful.

The liquid component is an aliphatic or aromatic hydrocarbon and has a molecular weight similar to that of the antistatic agent or the lubricant. This component functions to adjust the adhesiveness of the weak adhesive and also adjust the viscosity of the composition to facilitate application.

The weak pressure-sensitive adhesive is used by mixing the above-mentioned components in an appropriate ratio to achieve a desired tackiness and to have a viscosity within a range suitable for application. One or two applications
This is performed using an applicator having at least one nozzle and, if necessary, heating means. In terms of production efficiency, in-line work where a weak adhesive is applied prior to winding the product when manufacturing the foam sheet is preferable, but it is of course possible for offline work where the rolled foam sheet product is spread and applied again. It is.

The feature of the weak-adhesive plastic foam sheet of the present invention is that, for each block to which the weak-adhesive pressure-sensitive adhesive is applied, the pressure-sensitive adhesive is linearly applied, and, as described above, in the entire area of the block. The purpose of the present invention is to adjust the adhesive force by increasing or decreasing the ratio of the area where the adhesive is linearly applied.
It is of course important to control the adhesive strength of the adhesive itself, but this requires a high degree of know-how and requires some trial and error. According to the present invention, even if the same pressure-sensitive adhesive is used, the adhesive force of the block to which the pressure-sensitive adhesive has been applied can be changed within a certain range by changing the density of the linear application to micro.

A more important significance of the linear application of the pressure-sensitive adhesive is that the breakage of the foam sheet, which tends to occur when the adhesive is applied in a planar manner, is clearly reduced. From this viewpoint, it is necessary to avoid, for example, a circle having a diameter slightly smaller than the diameter of the cap as the line pattern of the adhesive. Although weakly tacky, if the circle of pressure sensitive adhesive appears in a position synchronized with the cap, the likelihood of the cap breaking when peeled increases.

With the above considerations, the linear pattern to be coated with the adhesive can be arbitrarily selected.
The simplest pattern is, of course, a plurality of parallel straight lines, as shown in FIG. 3A. This is easily realized by allowing the pressure-sensitive adhesive to flow out of the nozzles arranged above the flowing bubble sheet for a certain time and closing the nozzles for the remaining time.
If the block to which the pressure-sensitive adhesive is applied is in the form of a belt that is continuous in the longitudinal direction, the pressure-sensitive adhesive is applied by continuously flowing the pressure-sensitive adhesive.

Next simple are a plurality of parallel and bent straight lines, for example sawtooth lines as shown in FIG. 3B.
This is realized by reciprocating the nozzle within a certain range in the width direction of the bubble sheet. As factors for controlling the amount of the pressure-sensitive adhesive applied, only the flow velocity of the bubble sheet and the amount of the pressure-sensitive adhesive composition flowing out of the nozzle per unit time can be used. In the case of in-line coating operation, the former is a given condition. Under such conditions, if one attempts to increase the outflow, the line of one pressure-sensitive adhesive becomes thick. If the pressure-sensitive adhesive line is too thick, the adhesive strength becomes locally too strong, and the cap and the film are likely to be broken when the adhered bubble sheet is peeled off, which is not preferable.

In the case of a parallel straight line, there is a limit to the control of the amount of the adhesive applied. However, by making the nozzle reciprocate in the width direction to form a plurality of parallel bent lines, one adhesive It is possible to apply a relatively large amount of the pressure-sensitive adhesive in a certain block without thickening the line of the agent.

The linear pressure-sensitive adhesive application may of course be a parallel curve. For example, by a special reciprocating movement of the pressure-sensitive adhesive application nozzle, application according to a sine curve or a cycloid curve shown in FIG. 3C is possible. If the nozzle is rotated, the adhesive can even be applied in a partially overlapping and developing spiral shape, as shown in an example in FIG. 3D.

The pitch at which the blocks coated with the low-adhesive pressure-sensitive adhesive are arranged should be appropriately selected according to the desired adhesiveness of the product and the variety of usage. In the width direction, the width of the long plastic foam sheet is n (n = 2 to 2).
10) An equal interval is appropriate. It is usually convenient for the longitudinal direction to be equal to this widthwise interval,
Depending on the application of the product, it may be preferable to select a longer or shorter pitch.

The inventors have proposed that tearing perforations are provided at predetermined intervals in a long bubble sheet in a wound shape. It is also preferable to apply the present invention to such a bubble sheet. Therefore, as shown in FIG. 1, there is a tear perforation (4) and a weakly tacky adhesive (2) applied in the form of a block (3). The low-adhesive plastic foam sheet (1) in which the interval and the pitch of the pressure-sensitive adhesive application block are synchronized is one preferred embodiment of the present invention.

The simpler and easier-to-implement form of the pressure-sensitive adhesive application block is, as shown in FIG. 2, a shape of several bands continuously provided in the longitudinal direction of a long bubble sheet.

[0023]

EXAMPLE A slightly tacky pressure-sensitive adhesive composition was prepared in the following mixing ratio (parts by weight). Rubber component: Ethylene propylene rubber 40 parts Tackifier: 30 parts Liquid substance: 30 parts

The pressure-sensitive adhesive composition was applied to the back film surface of a general-purpose foam sheet in a pattern as shown in FIG. 1 in a linear shape as shown in FIG. 3D. The foam sheet is made of low-density polyethylene, the caps are staggered with a diameter of 10 mm, a height of 4 mm, and a pitch of 11.5 mm. The thickness of the cap film is 50 μm, and the thickness of the back film is 30 μm. 1m width
In the width direction and the longitudinal direction, tear perforations are provided at a pitch of 50 cm.

This weakly adhesive cell sheet is 50 cm square, 5 cm
By tearing it to a size of 0 cm × 1 m or 1 m square and combining them in a required number, they could be conveniently used for packing small to large articles. Of course, the adhesiveness of the foam sheets is easy, the adhesive properties are low, and there is no "trace", so that the foam sheets can be directly adhered to the articles to be packed.

[0026]

The weak adhesive plastic foam sheet of the present invention has a weak adhesive adhesive applied to a flat surface of the foam sheet for each block according to a specific pattern, and the application is thin. Since the coating is performed linearly, the application density of the pressure-sensitive adhesive in the block can be adjusted as the density of the line, and the control of the adhesive force can be performed much more easily than when the coating is applied to a solid. Therefore, even if the same pressure-sensitive adhesive is used, a weakly-adhesive foam sheet having an optimum adhesive strength can be obtained depending on the specifications of the foam sheet and the use of the foam sheet.

When the state of adhesion is observed microscopically, the adhesive is present linearly in each block, and the adhesion of the adhesive lines is not so strong when viewed individually. Even if the sheet is once adhered and then peeled, the bubble sheet is less likely to be broken, and can be easily re-applied. On the other hand, since the adhesive strength of one block is the sum of the adhesive strengths of the linear adhesives, it can be considerably increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a preferred embodiment of a weakly-adhesive plastic foam sheet of the present invention, partially expanded from winding.

FIG. 2 is a perspective view similar to FIG. 1, showing another embodiment of the low-adhesive plastic foam sheet of the present invention.

FIGS. 3A, 3B, 3C, and 3D are enlarged plan views showing various modes of applying a pressure-sensitive adhesive to the weakly-adhesive plastic foam sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bubble sheet 2 Adhesive 3 Block with adhesive applied 4 Perforation for tearing

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3E066 AA22 CA01 FA12 KA05 4F100 AK01A AK01B AK01D AK06 AK64 AL05C AN00C AT00B AT00D BA03 BA04 BA07 BA10A BA10C BA10D BA13 CA16C DC22C DD03 DD03A EH46 A13A04A GBA JA13A AB01 CA04 CB00 CC06 CE03 FA04 GA01

Claims (5)

[Claims] 1. A flat surface of a plastic foam sheet,
A weakly tacky adhesive is applied in a linear pattern to each block arranged at a predetermined pitch, and the adhesive force of each block is determined by an area where the adhesive is applied linearly in the entire area of the block. A weakly-adhesive plastic foam sheet, characterized by being adjusted by increasing or decreasing the ratio of 2. The low-adhesive plastic foam sheet according to claim 1, wherein a composition comprising a rubber component, a tackifier and a liquid component is used as the low-pressure adhesive. 3. A linear pattern coated with a weakly-adhesive pressure-sensitive adhesive comprises a parallel straight line, a parallel bent straight line,
The low tack plastic foam sheet of claim 1 which is either a parallel curve or a partially overlapping helical shape. 4. A block coated with a weakly-adhesive pressure-sensitive adhesive adjusts the width of a long plastic foam sheet to n (n = 2 to 2).
10) The low-adhesive plastic foam sheet according to claim 1, which is arranged in the width direction and the longitudinal direction at equal pitches. 5. A long plastic foam sheet is provided with tearing perforations at predetermined intervals, and
5. The low-adhesive plastic foam sheet according to claim 4, wherein the perforation interval and the pitch at which the blocks coated with the low-pressure adhesive are arranged are synchronized.