JP2003336017A - Self-adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-adhesive sheet having an uneven self-adhesive layer which permits easy liberation of bubbles and re-sticking when it is stuck on an adherend, readily attains flatness of the surface after being stuck and permits ready release of the self-adhesive from a releasable sheet. <P>SOLUTION: The self-adhesive sheet 1 comprises a sheet-like base material 2, a self-adhesive layer 3, and a releasable sheet 4 laminated in order, where the self-adhesive layer 3 is composed of a basal part 3a on the sheet-like base material 2 side and a projection part 3b on the releasable sheet side and has a shape such that many zones composed of the projection parts 3b are closely arranged. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet having bubbles on the surface of a pressure-sensitive adhesive layer, which makes it difficult to entrap air bubbles when it is attached to an adherend. Further, the present invention relates to a pressure-sensitive adhesive sheet which has such a structure and can adjust the pressure-sensitive adhesive force when it is attached to an adherend.

[0002]

2. Description of the Related Art Since a pressure-sensitive adhesive sheet is a sheet-shaped material to which an adhesive has been applied in advance, each time the sheet-shaped material is attached to an adherend, the time and effort required to apply the adhesive are released. It has the advantage that it is used for various purposes.

However, since a general pressure-sensitive adhesive sheet is formed with a flat pressure-sensitive adhesive layer having a uniform thickness, air bubbles may be trapped unless it is carefully worked when it is attached to an adherend. Moreover, once attached, the reattachment is not effective, and there is a risk of loss including the sheet-like material and the adherend.

The pressure-sensitive adhesive sheet preferably has an adhesive force suitable for the intended use, but it was necessary to prepare pressure-sensitive adhesive compositions having different compositions in order to change the adhesive force.

In order to improve these points, Japanese Unexamined Patent Publication No. 2001-302999 discloses that the surface of the pressure-sensitive adhesive layer has a quadrangular truncated pyramidal convex ridge having a side of 1 mm to 10 mm and a height of 3 μm to 100 μm. A wallpaper is described in which it is attempted to improve the inclusion of air bubbles by providing an interval of 1 mm to 1 mm. If this wallpaper is used, even if bubbles are generated, it is possible to let the bubbles escape to the outside from between the convex ridges, but the part where the adhesive layer is provided and the part where the adhesive layer is not provided are Since it is relatively large, if you look at the adhesive layer as a whole, uneven thickness will be formed,
When the pressure-sensitive adhesive sheet is attached to an adherend, it becomes difficult to obtain flatness of the pressure-sensitive adhesive sheet. Also, since the convex ridges are trapezoidal, even if only the convex ridges are adhered, the area ratio of adhesion is high and peeling is difficult even when trying to re-attach,
Furthermore, when it is attempted to form the convex ridges of the pressure-sensitive adhesive layer due to the unevenness formed on the release paper, the pressure-sensitive adhesive layer is difficult to peel from the relatively large recesses formed on the release paper, and the pressure-sensitive adhesive layer on the release paper is A part may remain and a desired convex ridge may not be obtained.

[0006]

Therefore, in the present invention, in the conventional pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer having irregularities, it is possible to ensure the ease of escape of air bubbles that are likely to intervene when it is attached to an adherend. The problem is that it is difficult to obtain the flatness of the surface of the pressure-sensitive adhesive sheet after being adhered to the adherend, or the small recesses used when manufacturing such a pressure-sensitive adhesive sheet are formed. It is an object of the present invention to solve the problem that the pressure-sensitive adhesive is difficult to peel from the peelable sheet.

[0007]

As a result of various studies on the surface shape of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, the inventor found that by arranging very fine projections on the surface of the pressure-sensitive adhesive layer without gaps, a flow path for bubbles to escape. Can be secured, and the flatness of the pressure-sensitive adhesive sheet can be obtained when it is adhered to the adherend, and the pressure-sensitive adhesive sheet can be prepared by using the release sheet with unevenness and peeled off at the time of use. Also, it was possible to obtain a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive is unlikely to remain on the release sheet side.

According to a first aspect of the invention, a pressure-sensitive adhesive layer is laminated on the surface of a sheet-shaped base material, and the surface of the pressure-sensitive adhesive layer opposite to the sheet-shaped base material side has a large number of convex portions. The present invention relates to a pressure-sensitive adhesive sheet, which has a shape in which areas are arranged without gaps. A second invention relates to the pressure-sensitive adhesive sheet according to the first invention, wherein the height h of the convex portion is 3 μm to 50 μm. 3rd invention is a 1st or 2nd invention, A peelable sheet is laminated | stacked on the opposite side to which the said sheet-shaped base material of the said adhesive layer was laminated | stacked, The said peelable sheet of The present invention relates to a pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer side has an inverted shape of the convex portion of the pressure-sensitive adhesive layer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As illustrated in FIG. 1, a pressure-sensitive adhesive sheet 1 of the present invention comprises a sheet-shaped base material 2 on which a pressure-sensitive adhesive layer 3 is laminated, and further a pressure-sensitive adhesive layer 3 on which a releasable sheet 4 is formed. The releasable side of the releasable sheet 4 is laminated so that the side having releasability is the side of the pressure-sensitive adhesive layer 3 and has the convex portion 3b on the surface of the releasable sheet 4 side of the pressure-sensitive adhesive layer 3. Adhesive layer 3 on the surface
It has a concave portion corresponding to the convex portion 3b. That is,
The release sheet side of the pressure-sensitive adhesive layer 3 and the pressure-sensitive adhesive layer 3 side of the release sheet have mutually opposite shapes.

The pressure-sensitive adhesive layer 4 has a base 3a on the side of the sheet-shaped substrate 2 and a base 3 as shown in FIG.
The convex section 3b has a horizontal cross-sectional area that decreases from the bottom side, that is, from the base section 3a side to the tip of the convex section 3b. That is, it has a shape of an upper constriction.

FIG. 3 is a diagram illustrating the shape and arrangement of the convex portions 3b. As shown in FIG. 3A, each convex portion 3
b has a part of a spherical shape, and one convex portion 3b is a hemisphere having a radius r (the outline of which is indicated by a dashed circle in FIG. 3B which is a plan view) is viewed from above. The outer shape is 2 ^1/2 per side
It can be regarded as a shape in which the periphery is cut so that it becomes a square of r, and the area composed of convex portions having a square horizontal cross section based on the hemisphere, as shown in FIG. They are densely arranged without gaps. Therefore, there is no flat portion where the base portion 3a is exposed between the convex portions 3b.

In addition to the hemispherical shape as illustrated, the convex portion 3b is based on a shape such as a rugby ball having an elliptical bottom surface which is divided in half in the major axis direction or the minor axis direction. , A cone or a pyramid, or a pyramid from the bottom to the middle and a cone near the top. Among these shapes, for those based on pyramids, the angular part that is the boundary between adjacent side surfaces is
It may be smoothed by cutting off the corners.

It is to be noted that, when the convex portions 3b are in contact with a surface parallel to the pressure-sensitive adhesive sheet 1 (a surface assuming an adherend), the tops of the respective convex portions 3b have a shape capable of point contact. When it is lightly pressure-bonded to an adherend, it exhibits a very low adhesive force, which is preferable, but it may be based on various shapes as described above, and the top may be flattened.

The convex portions 3b may or may not be uniform in size, and the convex portions 3b may be arranged in a grid pattern or in a zigzag pattern in which adjacent rows or columns have different phases. Although it may be any of a rectangular array or a random array having no regularity, in any array, a flat portion where the base 3a is exposed is provided between the convex portions 3b. It's something you don't touch.

The height h of each protrusion 3b from the base 3a is 3
It is preferably from 50 to 50 μm. Height h is 3 μm
If it is less than the above range, it is not possible to secure a sufficient flow path through which bubbles generated during application to the adherend escape, and there is a drawback that bubbles tend to remain.
Further, when the height h is less than 3 μm, even when the adhesive layer 3 is applied to an adherend, even the base 3a of the pressure-sensitive adhesive layer 3 contributes to the adhesion without increasing the force, and the adhesive force increases. Since it is easy, it does not peel off when re-adhesion such as adjusting the position where the pressure-sensitive adhesive sheet 1 is applied.

Further, when the height h of the convex portion 3b exceeds 50 μm, the above problem when the h is small does not occur, but since the unevenness of the pressure-sensitive adhesive layer 3 becomes large, the pressure-sensitive adhesive sheet 1
The adhesive layer 3 of the sheet-like base material 2 when attached to an adherend
Irregularities are likely to occur on the side where the is not laminated. Further, such unevenness of the pressure-sensitive adhesive layer 3 is obtained as an inverse shape of the unevenness formed on the peelable sheet,
When the height h is high, the shape of the peelable surface of the peelable sheet is an inverted shape between the convex portions 3b of the pressure-sensitive adhesive layer 3, that is, relatively pointed or thin. Since a high-height portion will be formed, it is difficult to obtain a predetermined shape when forming irregularities on the peelable sheet, and
The unevenness formed on the peelable sheet is weak against external force, and in the end,
This is because it becomes difficult to obtain the protrusion 3b of the pressure-sensitive adhesive layer 3 having a predetermined shape. The term "inverse shape" refers to the relationship between the shape of the mold surface and a copy obtained by reproducing the shape of the mold surface from the mold surface. For example, the shape of the mold surface is a flat surface. If the reference surface is a concave portion having the shape of the letter A, it means the relationship with the shape of the duplicated object having the flat surface as the reference surface and the convex portion having the shape of the letter A.

The sheet-shaped base material 2 of the pressure-sensitive adhesive sheet 1 of the present invention is prepared in advance separately from the adherend, and an adhesive or a pressure-sensitive adhesive is applied to the sheet-shaped base material 2 to be stuck on the adherend. Any sheet can be used as long as it needs to be attached. The sheet-shaped substrate 2 is industrially
It is preferable that it can be supplied in a roll shape and can be handled, and in general, it is a sheet such as paper, a plastic sheet, or a metal foil. Besides this,
Nonwoven fabric, cloth, other fibrous sheets, or sheets such as veneer obtained by thinly slicing wood can be used. Of the above, the plastic sheet may be colorless and transparent, colored and transparent, or opaque. These various sheets may be used alone or may be used as a composite sheet in which any combination is attached to each other, and a part or all of them are reinforced by coating or resin impregnation. Good. The thickness of the sheet-shaped substrate 2 is
The thickness is about 5 μm to 500 μm, more preferably about 20 to 300 μm, though it varies depending on the material and application. Further, when flexibility is not required, the upper limit can be further increased and is several mm, for example, about 5 mm or less.

Since the pressure-sensitive adhesive sheet 1 is used for coating the surface of an adherend and / or for determining the appearance of the adherend, it depends on the application of the adherend. Is sometimes called for aesthetics. In such a case, as the sheet-shaped base material 2, it is preferable to use a cosmetic film or a cosmetic sheet which is provided with a color, a pattern, or unevenness, if necessary.

Similarly, since the pressure-sensitive adhesive sheet 1 is used for the purpose of improving the physical properties or chemical properties of the surface of the adherend, the adhesive sheet 1 has necessary properties suitable for the application of the adherend. It may be preferable to have one provided.
As such a property, there are various properties such as scratch resistance, antifouling property, antifogging property, heat insulating property, antireflection property, antistatic property, electromagnetic wave shielding property, etc., in familiar areas.
It may have various properties such as magnetism, fluorescence emission property, moisture absorption / release property, infrared ray or ultraviolet ray reflection or absorption property, antibacterial property, and antifungal property. To impart these properties, a material having any one or two or more of those properties is selected as the sheet-shaped substrate 2, or a resin layer in which a substance having these properties is kneaded is coated or the like. It may be performed by a method such as stacking.

As the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer 3, known compounds such as rubber-based ones, acrylic-based ones starting from acrylic acid or acrylic ester, or silicone resin-based ones are used. it can. The pressure-sensitive adhesive composition can be applied by a known method such as roll coating or knife coating. As for the thickness of the pressure-sensitive adhesive layer 3, the total thickness of the base portion 3a and the convex portions 3b is
In the stage after being dried, the thickness is preferably 10 μm to 100 μm, and when it is less than 10 μm, the adhesive force when the pressure-sensitive adhesive sheet 1 is stuck to an adherend is insufficient, and 100 μm
When it exceeds, the improvement of the adhesive strength with the increase of the thickness of the pressure-sensitive adhesive layer is not observed. In the present invention, the convex portion 3 of the adhesive layer 3
Although the height h of b is defined as 3 μm to 50 μm, the height h of the convex portion 3b is the same as the height of the base 3a of the adhesive layer 3 and the convex portion 3.
It is preferably 30% to 50% of the total thickness of b.

The pressure-sensitive adhesive sheet 1 of the present invention having irregularities in the pressure-sensitive adhesive layer 3 can be manufactured by uniformly laminating the pressure-sensitive adhesive on the sheet-shaped substrate 2 and then embossing with a predetermined mold.
Preferably, as described above, the peelable sheet to be laminated on the pressure-sensitive adhesive layer 3 can be manufactured by a method of forming the roughness on the pressure-sensitive adhesive layer 3 by using a sheet having predetermined irregularities. preferable.

Examples of the peelable sheet 4 include those obtained by laminating a peelable layer composed mainly of a silicone resin on the surface of an appropriate substrate such as a plastic film or paper, or a polyolefin resin film such as polyethylene film or polyethylene. A film such as a terephthalate resin film can be used.

In order to form a predetermined unevenness on the peelable surface of the peelable sheet, it is preferable to use a die made in the shape of a roller for embossing or a resin composition which is fluid with the die made in the shape of a roller. It is preferable to use a material to form irregularities made of resin on the surface of a plastic film or the like.

The mold may be manufactured by any method, but the convex portion 3 of the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 of the present invention has a cross-sectional shape that is convex upward when the sheet-shaped substrate 2 is on the lower side. Since it has a property of easily forming recesses on the surface by hitting, for example, a surface of copper or the like is sprayed with beads or sand of a predetermined fine particle size, and gold having a large number of recesses such as hemispheres formed. You can get the mold. At this time, by giving sufficient time to spray beads and sand,
It is possible to obtain a mold having no gap between the recesses. Alternatively, for example, a method of forming a dent on a copper surface or the like by using a metal fitting having a tip having the shape of the convex portion 3b described above at a predetermined pitch, and the tip described above Convex 3
It is also possible to manufacture a mold having no gap between the recesses by a method such as making a hole using a rotary blade having a shape of b.

The mold obtained as described above may be used as it is, but when copper is used as the material, chromium plating is applied to improve the surface hardness, or the mold shape is copied by plating. Then, a metal mold made of a metal having a high hardness can be manufactured by plating different metals, and finally, a metal mold having a mold surface having the shape of the convex portion 3b of the pressure-sensitive adhesive layer 3 described above. To manufacture.

Using a mold having a mold surface having the shape of the convex portion 3b of the pressure-sensitive adhesive layer 3, the peelable surface of the peelable sheet 4 is heated and pressed as needed to press the mold surface of the mold. It is possible to obtain a peelable sheet 4 having a reverse shape to that of 1, that is, having a large number of recesses formed on the peelable surface. Alternatively, a photocurable resin having fluidity is filled between a sheet such as a plastic film and a mold having the shape of the convex portion 3b, and the resin is cured by irradiating light such as ultraviolet rays to cure the resin. It is possible to obtain the peelable sheet 4 in which a large number of concave portions are formed on the peelable surface composed of the above.

A pressure sensitive adhesive is applied to the peelable surface of the obtained peelable sheet 4 to form a pressure sensitive adhesive layer 3. The adhesive and the method of applying the adhesive are the same as those described above. Next, the peelable sheet 4 coated with the pressure-sensitive adhesive layer 3 is placed on the sheet-shaped base material 2 which is the base material of the pressure-sensitive adhesive sheet 1, and the two are bonded to each other, whereby the pressure-sensitive adhesive sheet 1 can be obtained. When the pressure-sensitive adhesive sheet 1 is manufactured using the peelable sheet 4 as described above, if the peelable sheet 4 is laminated as it is, the general function of protecting the pressure-sensitive adhesive layer by the peelable sheet 4 is exerted. In addition to this, there is an advantage that the shape of the convex portion of the pressure-sensitive adhesive can be easily maintained.

In the pressure-sensitive adhesive sheet 1 of the present invention, since the pressure-sensitive adhesive layer 3 has the convex portion 3b having the upper recess, when it is attached to an adherend,
Air can be escaped from the gap between the upper portions of the protrusions 3b, and when the adherend is attached to the adherend with a light pressure, the protrusions 3b
Since only the tip part of b is involved in adhesion, the area ratio of adhesion is low, and therefore the adhesive strength is weak. Therefore, when the position to be adhered or the type of the adhesive sheet to be adhered is wrong, the adhesive sheet 1 Easy to peel off. Also, after confirming the position to stick and the type of sticky sheet to stick,
By applying a strong pressure to the adherend, the concavities and convexities 3b are deformed, and the area ratio of the adhered areas is increased, and therefore the adhesive strength is increased, so that a predetermined strong adhesive strength can be exerted. become able to. In particular, in the present invention, since the convex portions 3b are arranged without a gap, the convex portions 3b are deformed so that the gap between the upper portions of the convex portions 3b is likely to be very small or the gap is likely to be eliminated. It is easy to obtain strong adhesion. Further, when the release sheet is accompanied, the convex portions 3b of the pressure-sensitive adhesive layer are in contact with each other at the bottoms of the convex portions 3b, so that the sheet-shaped substrate 2 and the pressure-sensitive adhesive layer 3 are peeled from the peelable sheet. At this time, the convex portion 3b is the adhesive layer 3
The adhesive sheet 3 does not easily come off, and since the height of the convex portion 3b of the pressure-sensitive adhesive layer 3 is extremely small, even if the shape of the convex portion 3b remains even after the pressure-sensitive adhesive sheet 1 is attached to the adherend, the pressure-sensitive adhesive sheet The flatness of the surface on the side opposite to the adherend 1 is not impaired.

[0029]

According to the invention of claim 1, air can be released when it is attached to an adherend, and it can be reattached when it is lightly pressure-bonded to the adherend, and it is strong. By crimping, it is possible to easily improve the adhesive strength,
It is possible to provide a pressure-sensitive adhesive sheet in which the flatness is not impaired. According to the invention of claim 2, in addition to the effect of the invention of claim 1, it is possible to provide a pressure-sensitive adhesive sheet in which flatness is hardly impaired even when it is attached to an adherend.
In addition to the effect of the invention of claim 1 or claim 2, since the releasable sheet having a predetermined shape on the releasable surface is used, it is easy to form the convex portion of the adhesive and maintain the shape. Therefore, it is possible to provide a pressure-sensitive adhesive sheet that can prevent a part of the pressure-sensitive adhesive layer from falling off when peeling from the peelable sheet.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an adhesive sheet of the present invention.

FIG. 2 is a sectional view showing a detailed structure of an adhesive layer.

FIG. 3 is a diagram showing the shape and arrangement of the convex portions of the adhesive layer.

[Explanation of symbols]

1 Adhesive sheet 2 Sheet-shaped substrate 3 Adhesive layer (3a; base part, 3b; convex part) 4 Peelable sheet

Continued front page    F term (reference) 4F100 AK04 AK25G AK42 AT00A                       BA02 BA03 BA07 BA10B                       BA10C DD01B DD01C DG10                       JL13B JL14C YY00B                 4J004 AA05 AA10 AA11 AB01 CC02                       CE02 DA02 DA03 DA04 DB03                       FA08                 4J040 CA001 DF011 DF041 EK031                       JA09 JB09 LA06

Claims (3)

[Claims] 1. A pressure-sensitive adhesive layer is laminated on a surface of a sheet-shaped base material, and a surface of the pressure-sensitive adhesive layer opposite to the sheet-shaped base material side is provided with a large number of convex portions without gaps. A pressure-sensitive adhesive sheet having an arrayed shape. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the height h of the convex portion is 3 μm to 50 μm. 3. A release sheet is laminated on the side of the pressure-sensitive adhesive layer opposite to the side on which the sheet-shaped substrate is laminated, and the pressure-sensitive adhesive layer side of the release sheet is the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive sheet has an inverted shape of the convex portion.