JPH10195395A - Easily tearable double-coated self-adhesive tape or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an easily tearable tape by applying a self-adhesive to both sides of a plastic film substrate which has minute holes which have specified diameters, of which the sum of areas of openings is in a specified range, and at least a half of which are through holes. SOLUTION: A plastic film (e.g. a polyethylene or polyester film) with a thickness of 10-90μm is perforated, e.g. by a laser, to form minute holes which have diameters of 1,500μm or lower and of which the sum of areas of openings accounts for 5-15% of the surface area of the film. Then, on both sides of the perforated film 1 having minute holes 3 of which at least a half are through holes 3, self-adhesive layers 2a and 2b are formed to give a double-coated self-adhesive tape. A self-adhesive tape formed by laminating a metal foil to at least one side of the perforated film 1 and forming a self-adhesive layer on the foil enables to detect the position of the self-adhesive tape stuck to an adherend with a metal detector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided pressure-sensitive adhesive tape or sheet, and more particularly, to an easily tearable double-sided adhesive tape or sheet which can be easily cut by simply pulling it with a fingertip without using cutting tools such as scissors. It relates to an adhesive tape or sheet.

[0002]

2. Description of the Related Art In a double-sided pressure-sensitive adhesive tape or sheet, a rayon non-woven fabric is mainly used as a base material of the tape or sheet requiring easy tearing.

[0003] When applying a pressure-sensitive adhesive to both sides of this rayon non-woven fabric to form a double-sided pressure-sensitive adhesive tape, the first one-side coating is performed by:
Since the rayon nonwoven fabric substrate is mechanically weak, the indirect coating method is used. That is, the method is to prepare a double-sided release paper separately from the rayon nonwoven base material, apply an adhesive on one surface thereof to form an adhesive layer, and apply the surface of the adhesive layer to a rayon nonwoven base. It is to be laminated on one side of the material to form a laminate comprising a base material, an adhesive layer and double-sided release paper.

In the second coating, that is, when the adhesive is coated on the substrate surface opposite to the first coating surface, the laminate is mechanically reinforced by double-sided release paper. In addition to the indirect coating method, a direct coating method can be used.

In the case where the second coating is also performed by the indirect coating method, a double-sided release paper different from the double-sided release paper used for the first coating is prepared, and an adhesive is coated on one side thereof. , After bonding that surface to the substrate surface to be coated a second time,
One side of the double-sided release paper is peeled off, and the laminate composed of the other double-sided release paper and the double-sided pressure-sensitive adhesive tape is wound on a take-up roll such that the double-sided release paper is on the outside. At this time, the double-sided release paper wound on the take-up roll together with the double-sided adhesive tape serves as an insertion layer necessary to prevent the adhesive surfaces of the double-sided adhesive tape from sticking to each other. No paper is needed.

In the case where the second coating is performed by a direct coating method, an adhesive is directly applied to the substrate surface opposite to the first coating surface, and after drying, the laminate is subjected to the first coating. Is wound on a take-up roll such that the double-sided release paper laminated by the above coating is on the outside. In this case, there is no waste of double-sided release paper,
Since the pressure-sensitive adhesive is directly applied to the base material surface, the pressure-sensitive adhesive soaks into the rayon nonwoven fabric substrate, the amount of coating increases, and furthermore, it takes a long time to dry the pressure-sensitive adhesive, and the coating efficiency is reduced.

When a plastic film is used as a base material of a double-sided pressure-sensitive adhesive tape, it has advantages such as excellent toughness, transparency and durability as compared with a case where a rayon nonwoven fabric is used. Since the adhesive does not penetrate into the substrate, it is possible to apply the adhesive directly to the substrate surface without increasing the coating amount or reducing the coating efficiency. However, the problem is that the base material is not easily tearable.

[0008]

In the production of a double-sided pressure-sensitive adhesive tape that requires easy tearing, the use of a nonwoven fabric as a base material
As described above, there is a problem that the release paper is wasted or the coating efficiency is reduced. In addition, when the tape is cut by hand, the tape near the cut portion is cut while extending, so that there is a disadvantage that the adhesive strength at that portion is reduced.

In a double-sided adhesive tape of a plastic film base, if a film stretched only in a direction perpendicular to the length direction is used as a base material, the tape can be cut by hand. The film stretches and is difficult to cut,
In addition, there is a problem that the adhesive strength of the stretched portion is reduced and the film is cut only in a certain direction. That is, in the prior art, there was no practically satisfactory double-faced adhesive tape with a plastic film substrate.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide the advantages of a double-sided adhesive tape for a plastic film base such as excellent toughness, transparency and durability. Another object of the present invention is to provide a double-sided pressure-sensitive adhesive tape having practically excellent tearability and a double-sided pressure-sensitive adhesive tape having a base material of an easily tearable metal foil laminate obtained by laminating a metal foil on a plastic film.

[0011]

The object of the present invention is to provide a plastic film as a base material of a double-sided pressure-sensitive adhesive tape and to provide fine holes over the entire surface of the base material, and more preferably to use a plastic film having a thickness of 10 to 90 μm. As a base material,
Micropores are provided over the entire surface of the substrate, and the diameter of the opening of the micropores on the surface of the substrate is 1500 μm or less,
This can be achieved by making the total area of the openings 5 to 15% of the area of the surface.

With the above construction, the problem of waste of the release paper in the manufacturing process and the reduction of the coating efficiency are solved, the advantages of the double-sided adhesive tape on the plastic film base are maintained, and the elongation of the tape when the tape is cut. And a double-sided pressure-sensitive adhesive tape which is small in size, does not lower the adhesive strength due to elongation, and has good tearability can be obtained.

In the following description, a double-sided pressure-sensitive adhesive tape will be described. However, in general, a double-sided pressure-sensitive adhesive sheet is obtained by cutting a wide double-sided pressure-sensitive adhesive tape into an appropriate length. Will not be lost.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a double-sided pressure-sensitive adhesive tape according to an embodiment of the present invention.

FIG. 1 is a schematic sectional view showing a part of a double-sided pressure-sensitive adhesive tape according to the present invention. 1 has a thickness of 10 which is made of any of polyethylene, polypropylene and polyester.
An acrylic pressure-sensitive adhesive layer 2a and 2b is formed on both surfaces of the film 1 with a 90-μm plastic film. Reference numeral 3 denotes micropores provided over the entire surface of the film 1. The diameter of the openings of the micropores 3 on the surface of the film 1 is 1500 μm or less, and the total area of the openings is 5 to 15% of the surface area. Within the range. If the total proportion of the opening area to the surface area is greater than 5%, the film 1, and thus the entire double-sided pressure-sensitive adhesive tape, becomes easily tearable, but the proportion is greater than 15%. Then, the mechanical strength of the film 1 is reduced, and the mechanical strength of the entire double-sided pressure-sensitive adhesive tape is equal to or less than the mechanical strength of the conventional double-sided pressure-sensitive adhesive tape of rayon nonwoven fabric. If the proportion is less than 5%, the film 1, and hence the entire double-sided pressure-sensitive adhesive tape, is not easily tearable. The fine holes 3 may be either through-holes or non-through holes, but if all of them are non-through holes, the tearability is reduced. Therefore, more than half of the fine holes 3 may be through holes. desirable. The shape of the fine holes 3 does not need to be cylindrical, and may be conical, spherical, or other shapes.

The fine holes 3 may be perforated by a laser, or diamond particles may be uniformly electrodeposited on one surface of a pair of two rollers pressed against each other, and the film 1 passes between the rollers. Alternatively, it may be formed.

FIG. 2 is a schematic sectional view showing a part of another double-sided pressure-sensitive adhesive tape according to the present invention. 1 is a thickness 1 made of any of polyethylene, polypropylene and polyester
It is a plastic film of 0 to 50 μm, and on the entire surface of the film 1, fine holes 3 similar to FIG. A metal foil 4 is laminated on one surface 1s of the film 1 and acrylic pressure-sensitive adhesive layers 2a and 2b are provided on the surface of the film 1 on the side opposite to the surface 1s and on the surface of the metal foil 4, respectively. , Is formed. Since both the film 1 and the metal foil 4 are easily tearable, the entire double-sided adhesive tape is also easily tearable. It should be noted that, even when a metal foil laminated on both sides of the film 1 is used as the base material, an easily tearable double-sided pressure-sensitive adhesive tape can be produced in the same manner. The main purpose of using the metal foil as a part of the base material is to enable a metal detector to detect the position where the adhesive tape is used.

An example of the embodiment of the present invention (hereinafter simply referred to as an embodiment) will be described below, and the plastic film substrate easily tearable double-sided pressure-sensitive adhesive tape of the present invention will be described more specifically.

Embodiment The diameter of the opening of the micropore on the surface of the film is 50-1.
50 μm, and on both sides of a 20 μm-thick easily tearable polypropylene film provided with micropores throughout the film so that the total area of the openings is 8% of the surface area, Acrylic adhesive on one side, thickness 5
The coating was performed so as to have a thickness of 0 μm to prepare a double-sided pressure-sensitive adhesive tape having a thickness of 120 μm. In this case, the indirect coating method was used for the first coating and the direct coating method was used for the second coating. However, since the plastic film substrate is tough, the first coating is applied directly. It can also be performed by a construction method. When applying the adhesive by the direct coating method, the adhesive is
Although it penetrates into the micropores having a relatively large opening diameter, the amount is significantly smaller than the amount of the pressure-sensitive adhesive penetrating into the base material when a rayon nonwoven base material is used. Does not occur.

The double-sided pressure-sensitive adhesive tape of a plastic film substrate produced in this manner has the same or higher tearability as a double-sided pressure-sensitive adhesive tape of a rayon nonwoven substrate, and has a small elongation when cut by hand. It can be used in a state where the adhesive strength is not reduced and good adhesive strength is maintained over the entire surface of the tape.

In order to compare the performance of the above embodiment with the performance of the easily tearable double-sided pressure-sensitive adhesive tape of the prior art, the following comparative example was prepared by the conventional technology.

Comparative Example An acrylic pressure-sensitive adhesive was applied to both sides of a 45 μm thick rayon nonwoven fabric so as to have a thickness of 50 μm on one side, and a double-sided pressure-sensitive adhesive tape having a total thickness of 120 μm after drying was prepared. In this case, both the first coating and the second coating were performed by the indirect coating method.

Using the double-sided pressure-sensitive adhesive tapes described in the above embodiment and comparative examples as samples, physical properties and pressure-sensitive properties of the samples were evaluated by the following test methods.

Test method Adhesive strength: JIS-Z-0237 Tack: JIS-Z-0237 (inclined ball tack method, using 1/32 to 32/32 inch diameter steel balls, indicated by ball number) Force: JIS-Z-0237 (However, load at 40 ° C
Tensile strength: JIS-Z-0237 Elongation: JIS-Z-0237 Tear strength: JIS-P-8116 The evaluation results of physical properties and adhesive properties obtained for the above samples are shown in Table 1. .

[0025]

[Table 1]

As is clear from Table 1, the double-sided adhesive tape of the plastic film base obtained by the practice of the present invention has almost the same adhesive strength and tackiness as the double-sided adhesive tape of the rayon nonwoven base obtained by the prior art. It can be seen that it has properties, slightly superior holding power, excellent mechanical strength (large tensile strength and small elongation), and excellent tearability (small tear strength).

The tensile strength of the sample was measured in the same manner as described above, using the rayon nonwoven fabric substrate and the plastic film substrate before the application of the pressure-sensitive adhesive and the plastic film substrate before the fine holes were provided. As a result, the tensile strengths of the rayon nonwoven fabric substrate, the microporous plastic film substrate, and the plastic film substrate without micropores are 0.65, 1.54, and 3.11, respectively, expressed in kgf / 15 mm. understood. From this result, the total area of the micropore openings is the total area of the plastic film substrate.
From 0% to 8%, it can be seen that the tensile strength of the substrate is almost halved. Further, if the above ratio is increased by 8% to 16%, the tensile strength of the substrate is considered to be further reduced by half to about 0.77. Nevertheless, the tensile strength is still higher than that of the rayon nonwoven fabric substrate. Greater than the value (0.65). Furthermore, if the above-mentioned micropore opening area ratio is reduced from 16% to 15%, the tensile strength of the plastic film substrate is further increased.
Even if the amount of the adhesive that penetrates into the micropores increases with the increase in the ratio of the opening area of the micropores described above, the absolute amount is the base of the adhesive when the adhesive is directly applied to the rayon nonwoven fabric base material. Since it is extremely small in comparison with the amount of permeation into the material, the direct application method can be used for the application of the pressure-sensitive adhesive without any trouble, and there is no inconvenience in the application process.

As is clear from Table 1, the tearability in the embodiment is remarkably superior to that of the comparative example.
That is, when compared with the tear strength considered to be an amount inversely proportional to the tearability, the value in the embodiment is 43 g, which is significantly smaller than 160 g in the comparative example. The tear strength increases as the above-mentioned ratio of the opening area of the fine holes decreases. Although the increase is largely estimated, even when the tear strength is inversely proportional to the micropore opening area ratio, the tear strength of the embodiment when the micropore opening area ratio is reduced from 8% to 5% is from 43 g to 69 g. Is calculated. The value after the increase (69 g) is also half or less of the value (160 g) in the comparative example, and the double-sided pressure-sensitive adhesive tape according to the present invention further has a fine pore opening area ratio of 5% of the plastic film substrate, It can be seen that even if half of the fine holes are not through holes, they have sufficient practical tearability.

According to the above measurement experiments and considerations, when the above-mentioned micropore opening area ratio is 5% or more and 15% or less, excellent tearability, toughness, transparency,
It can be seen that a durable double-sided pressure-sensitive adhesive tape can be produced.

The size of the micropores provided in the plastic film substrate is expressed as the size of the irregularity of the cut portion of the double-sided pressure-sensitive adhesive tape, so that the irregularity does not cause practical inconvenience. In order to achieve this, the opening diameter of the fine holes is desirably 1500 μm or less.

The thickness of the plastic film substrate is 10
If it is not more than μm, the tensile strength of the double-sided pressure-sensitive adhesive tape may be smaller than that in the case of using a rayon nonwoven fabric substrate. For example, when the thickness of the base material is changed without changing the opening area ratio of the fine holes, if the tensile strength of the double-sided pressure-sensitive adhesive tape is proportional to the thickness of the base material, the base material in the above embodiment When the thickness is changed from 20 μm to 10 μm, the above tensile strength is calculated as 2.64 to 1.32 in kgf / 25 mm, and this value (1.32) is the value (1.58) in the comparative example. Slightly smaller than. When the thickness of the plastic film substrate is 90 μm or more, the double-sided pressure-sensitive adhesive tape produced using the substrate becomes difficult to cut by hand. For example, when the thickness of the substrate is changed without changing the opening ratio of the micropores, if the tear strength of the double-sided pressure-sensitive adhesive tape is proportional to the thickness of the substrate, the substrate according to the above embodiment When the thickness of the film is changed from 20 μm to 90 μm, the above tear strength is
It is calculated to be 194g from 43g, but this value (194g)
Is slightly larger than the value (160 g) in the above comparative example.

[0032]

As described above, by using a plastic film in which micropores are provided over the entire surface of the film as the base material of the double-sided adhesive tape, the conventional laser can be used.
The problems in the production process of the double-sided adhesive tape of the nonwoven nonwoven fabric substrate, that is, the problems of waste of the release paper and the reduction of the coating efficiency, are solved and compared with the conventional double-sided adhesive tape of the rayon nonwoven fabric substrate. It is possible to produce a double-sided adhesive tape of a plastic substrate having substantially the same adhesiveness, better toughness, transparency, durability, and easy tearability.

Incidentally, Japanese Utility Model No. 3021059 discloses a single-sided adhesive tape based on a plastic film provided with conical micropores. This tape is a single-sided adhesive tape and has a hole shape. The point that it is limited to a conical shape, the opening diameter of the micropore on the adhesive applied surface of the base material is 15μ
m or less to prevent penetration of the pressure-sensitive adhesive into the fine holes, and the ratio of the fine-hole opening area on the pressure-sensitive adhesive-coated surface (in the present invention, 5 to 15% is appropriate).
It is different from the double-sided pressure-sensitive adhesive tape according to the present invention in that the content is 0.53% or less, and does not suggest the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a double-sided pressure-sensitive adhesive tape according to the present invention.

FIG. 2 is a schematic sectional view showing another example of the double-sided pressure-sensitive adhesive tape according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plastic film, 1s ... One side surface of a plastic film, 2a and 2b ... Adhesive layer, 3 ... Micropore, 4
... metal foil.

Claims (4)

[Claims] An easily tearable double-sided pressure-sensitive adhesive tape or sheet obtained by applying a pressure-sensitive adhesive to both sides of a plastic film substrate having micropores provided on the entire surface. 2. An easily tearable double-sided pressure-sensitive adhesive tape or sheet obtained by applying a pressure-sensitive adhesive to both surfaces of a laminated base material in which a metal foil is laminated on one or both surfaces of a plastic film having micropores formed on the entire surface. 3. The surface of the plastic film has a diameter of an opening of the micropores of 1500 μm or less, a total area of the openings is 5 to 15% of an area of the surface, and a half of the micropores. The easily tearable double-sided pressure-sensitive adhesive tape or sheet according to claim 1 or 2, wherein the above is a through hole. 4. A plastic film having a thickness of 10 to 10.
3. The structure according to claim 1, wherein the thickness is 90 μm.
2. The easily tearable double-sided pressure-sensitive adhesive tape or sheet according to 1.).