JP2002249734A - Adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet containing inorganic filler in its adhesive layer, capable of imparting properties such as masking ability thereto without complicated treatment on one or both sides of the substrate and capable of being torn off without leaving the adhesive on a signboard when tearing the adhesive sheet off the signboard. SOLUTION: This adhesive sheet has an adhesive layer on at least one side of a substrate, wherein the adhesive layer comprises at least an adhesive ingredient, inorganic filler and a silane coupling agent.

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 in which an inorganic filler is contained in a pressure-sensitive adhesive layer for imparting performance such as concealing property and conductivity.

[0002]

2. Description of the Related Art Conventionally, a printing sheet used for a display such as an electric signboard has an adhesive layer on one side of a support, and an image is printed on a surface opposite to the side on which the adhesive layer is provided by a silk printing machine or the like. Or printing an image by a method such as ink jet or electrostatic recording, and pasting it on a signboard for display.

[0003] As such a printing sheet, a sheet having a concealing property so that the electrode tube is not transparent during display is preferably used. Therefore, when the support is a plastic film, a material obtained by forming a film by adding an inorganic filler to a plastic to have a hiding property is preferably used. However, there are cases where such a support does not have a sufficient concealing property such as a thin one, and cases where concealing properties are required even if the thickness is not so small.

In such a case, the support is provided with a concealing layer provided on one or both sides of the support, separately from the adhesive layer, by applying a paint containing an inorganic filler, or by vapor deposition or sputtering of a metal. . However, such processing is costly and complicated. In addition, the type coated with paint may affect printability such as laminating an adhesive layer or the adhesiveness of printing ink.The type that deposits or sputters metal uses a metal film. However, there is also a problem that the scratches are easily seen by the light of the illuminated signboard.

[0005] Therefore, it is conceivable to provide an adhesive layer with an opaque property by containing an inorganic filler without performing such treatment. However, when the inorganic filler is contained in the adhesive layer, the cohesive force of the adhesive layer is reduced, and when the adhesive sheet is peeled off from the signboard, cohesive failure occurs in the layer of the adhesive layer, and glue remains on the signboard. There was a problem. Also,
When printing an image with an inkjet printer or the like on the surface opposite to the surface on which the adhesive layer is provided, if strongly pressed by the transport roll of the printer, the adhesive layer has a reduced cohesive force,
There is also a problem that a streak (shading of image density) appears on the printed image as if the locus of the transport roll was drawn.
The cohesive strength of the pressure-sensitive adhesive layer can be reduced by, for example, using a cross-linkable pressure-sensitive adhesive component and adding an excessive amount of a cross-linking agent or the like. As a result, the pressure-sensitive adhesive sheet having desired adhesive performance cannot be obtained.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a pressure-sensitive adhesive sheet containing an inorganic filler in a pressure-sensitive adhesive layer, and has a performance such as a concealing property without a complicated treatment on one or both surfaces of a support. An object of the present invention is to provide a pressure-sensitive adhesive sheet which can be applied and does not leave adhesive on the signboard when the pressure-sensitive adhesive sheet is peeled off from the signboard.

[0007]

The pressure-sensitive adhesive sheet of the present invention for solving the above-mentioned object is a pressure-sensitive adhesive sheet having a support provided with a pressure-sensitive adhesive layer on at least one side of a support, wherein the pressure-sensitive adhesive layer comprises at least a pressure-sensitive adhesive component, an inorganic filler, It is characterized by being formed from a silane coupling agent.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the pressure-sensitive adhesive sheet of the present invention will be described in detail.

The support used in the pressure-sensitive adhesive sheet of the present invention includes paper and a plastic film. Examples of the plastic film include polypropylene, polyethylene, polyester, polycarbonate, triacetyl cellulose, polyvinyl chloride, acrylic, polystyrene, and the like. Examples thereof include polyamide, polyimide, and vinylidene chloride-vinyl chloride copolymer. In addition, these plastic films may be formed into a film by adding an inorganic filler to plastic, and may be provided with functions such as concealing properties, conductivity, and unevenness of the surface shape depending on the application. May be used. In the support used in the present invention, further depending on the purpose, generally used various ultraviolet absorbers, antistatic agents, antioxidants,
Anti-aging agents, slip agents and the like may be used as long as the object of the present invention is not impaired.

Since the thickness of the support varies depending on the use, it cannot be determined unconditionally. For example, when the support is used for a display such as an illuminated signboard, the supply to a printing machine for printing an image, transportation, etc. Those having a size of 10 μm to 250 μm are used. Further, in consideration of the easiness of sticking and peeling of the pressure-sensitive adhesive sheet, the thickness is preferably about 30 μm to 125 μm.

Next, the adhesive layer is formed from at least an adhesive component, an inorganic filler, and a silane coupling agent. As the adhesive component, a natural resin adhesive, a synthetic resin adhesive, or the like is used, and a synthetic resin adhesive such as an acrylic adhesive, a silicone adhesive, or a urethane adhesive is preferably used. Among them, a cross-linked pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive is particularly preferably used.

[0012] As the inorganic filler, the content to be contained varies depending on the application, and cannot be said unconditionally. For example, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, titanium oxide, silica, kaolin, perlite, calcium sulfate, sulfuric acid Examples thereof include barium, calcined alumina, calcium silicate, talc, mica, aluminum, zinc, zinc oxide, tin oxide, and carbon. These may be used alone or in combination of two or more.

Examples of the silane coupling agent include epoxy-based, vinyl-based, and amino-based silane coupling agents, and epoxy-based silane coupling agents are particularly preferred. By including the silane coupling agent in the adhesive layer, the inorganic filler and the adhesive component, which usually have low adhesiveness, are firmly bonded to each other and exhibit strong adhesiveness. This prevents the cohesive force of the adhesive layer from decreasing, prevents cohesive failure in the adhesive layer when peeling the adhesive sheet from the signboard, and prevents adhesive residue when peeling the adhesive sheet from the adherend. it can. In addition, since the cohesive force of the adhesive layer is prevented from lowering, when an image is printed on the surface opposite to the surface on which the adhesive layer is provided by an inkjet printer or the like, a streak (image density Does not occur. When a support containing an inorganic filler is used, the adhesion between the support and the adhesive layer can be improved.

The adhesive layer may contain additives such as an organic pigment, a crosslinking agent, an antistatic agent, an antifoaming agent, a leveling agent, and a light stabilizer, in addition to the inorganic filler and the silane coupling agent. However, the amount of these additives is desirably within a range that does not impair the effect of the adhesive layer.

The pressure-sensitive adhesive sheet of the present invention comprises a coating solution obtained by dissolving or dispersing the above-mentioned pressure-sensitive adhesive component constituting the pressure-sensitive adhesive layer, an inorganic filler, a silane coupling agent, and additives added as necessary in a solvent. It can be formed by coating and drying on at least one surface of the support by a coating method such as a bar coating method, a spray coating method, and a roll coating method. The thickness of the pressure-sensitive adhesive layer is not particularly limited because it varies depending on the application, but is usually 0.1 μm to
It is preferably about 100 μm, more preferably 1 μm to
It is about 50 μm.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments. In this embodiment, “parts” and “%”
Are by weight unless otherwise indicated.

Example 1 An adhesive layer coating solution having the following formulation was applied to the treated surface of a release film (Diafoil MRF, 25 μm: Mitsubishi Chemical Polyester Film Co., Ltd.) and dried to form an adhesive layer having a thickness of about 25 μm. This was laminated on one side of a calcium carbonate-containing polypropylene film (Yupo FPG-80, 80 μm: Oji Yuka Synthetic Paper). After leaving this film in a room temperature (about 25 ° C.) environment for 7 days, the release film was peeled off and removed to produce the pressure-sensitive adhesive sheet of the present invention.

<Formulation of Coating Solution for Adhesive Layer> Acrylic adhesive (solid content: 42%) 100.0 parts (Olivine BPS-4905: Toyo Ink Manufacturing Co., Ltd.) Aluminum paste 2.0 parts (O100T: Toyo Aluminum Co., Ltd.) Silane Coupling agent (solid content 100%) 0.1 part (KBM-403: Shin-Etsu Chemical Co., Ltd.) Crosslinking agent (solid content 37.5%) 3.0 parts (Olivine BPS-8515: Toyo Ink Manufacturing Co., Ltd.) Ethyl acetate 25.0 parts Toluene 25.0 parts

Example 2 An adhesive layer coating solution having the following formulation was
Silica-containing polyester film (E20, 100μ
m: Toray Industries, Inc.), and dried to form an adhesive layer having a thickness of about 25 μm, and the release film of Example 1 was laminated. Next, the film was heated at room temperature (about 25 ° C.)
After being left for one day, the release film was peeled off and removed to prepare the pressure-sensitive adhesive sheet of the present invention.

<Formulation of Coating Solution for Adhesive Layer> Acrylic adhesive (solid content: 42%) 100.0 parts (Olivine BPS-4905: Toyo Ink Manufacturing Co., Ltd.) 1.8 parts carbon paste (Multiluck A903Black: Toyo Ink Manufacturing) Titanium oxide paste 0.2 part (Multiluck S161White: Toyo Ink Manufacturing Co., Ltd.) Silane coupling agent (solid content 100%) 0.1 part (KBM-403: Shin-Etsu Chemical Co., Ltd.) Crosslinking agent (solid content 37. 3.0 parts (Olivine BPS-8515: Toyo Ink Mfg. Co., Ltd.) Ethyl acetate 25.0 parts Toluene 25.0 parts

Comparative Example 1 The adhesive layer coating solution of Example 1 was
Example 1 except that no silane coupling agent was added
In the same manner as in Example 1, an adhesive sheet of Comparative Example 1 was produced.

Comparative Example 2 The adhesive layer coating solution of Example 1 was
No silane coupling agent was added and the amount of crosslinking agent added was 2
A pressure-sensitive adhesive sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the pressure was doubled.

First, about these adhesive sheets,
The adhesive strength was measured to evaluate the adhesiveness. At the same time, the adhesive residue on the melamine coated steel sheet was also evaluated. These adhesive sheets are cut into a size of width x length = 25 mm x 100 mm, and attached to a melamine coated steel plate as an adherend,
After leaving in an environment of 20 ° C. and 65% RH for 30 days,
Peeling was performed at a peeling speed of 300 mm / min and an angle of 180 °, and evaluated. The evaluation criteria for the adhesiveness are as follows: adhesive strength is 1000 g / 25.
What was about mm was "○", adhesive strength was 500g / 2
What was about 5 mm was marked "x". The criteria for the evaluation of the adhesive residue were “O” when the adhesive layer had no adhesive residue on the melamine coated steel sheet, and “X” when the adhesive layer had any adhesive residue. Table 1 shows the results.

Next, these pressure-sensitive adhesive sheets were subjected to an image printing test. During the production of these pressure-sensitive adhesive sheets, before peeling and removing the release film, an ink receiving layer was provided on the surface where the pressure-sensitive adhesive layer was not provided, and then an ink jet printer (Mimaki JV2-130: Mimaki Engineering Co., Ltd.) The image was printed and the printed image was evaluated. The evaluation criteria were as follows: "O" when no streaks (shading of image density) depicting the trajectory of the conveying roll after image printing were observed, and "X" when observed. Table 1 shows the results.

[0025]

[Table 1]

Since the pressure-sensitive adhesive sheets of Examples 1 and 2 contained a silane coupling agent in the pressure-sensitive adhesive layer, the bonding strength between the inorganic filler and the pressure-sensitive component in the pressure-sensitive adhesive layer was improved, and The cohesive force was prevented from lowering, no cohesive failure occurred in the adhesive layer, and no adhesive residue was observed. In addition, since the silane coupling agent was also bonded to the inorganic filler contained in the support, the adhesion between the adhesive layer and the support was also improved, and the adhesive layer was not transferred from the support to the melamine-coated steel sheet at all. . Also in the printed image, since a decrease in the cohesive force of the adhesive layer was prevented, no streak (shading in image density) depicting the trajectory of the transport roll was observed.

On the other hand, since the pressure-sensitive adhesive sheet of Comparative Example 1 does not contain a silane coupling agent, the bonding strength between the inorganic filler and the pressure-sensitive component in the pressure-sensitive adhesive layer is not improved, and the cohesive force of the pressure-sensitive adhesive layer is reduced. Cohesive failure occurred in the adhesive layer, leaving glue. Also, as for the printed image, since the cohesive force of the pressure-sensitive adhesive layer is reduced, streaks (shading of image density) appearing as if the locus of the transport roll were drawn.

The pressure-sensitive adhesive sheet of Comparative Example 2 did not contain a silane coupling agent, but had a large amount of a crosslinking agent added.
A decrease in the cohesive force of the adhesive layer was prevented, and no adhesive residue due to cohesive failure in the adhesive layer was observed. Also, for the printed image, since the cohesive force of the adhesive layer is prevented from lowering,
No streak (shading in image density) depicting the trajectory of the transport roll was observed. However, with respect to the adhesiveness, a large amount of the cross-linking agent was added, resulting in a decrease in the adhesive strength, and sufficient adhesiveness to the melamine-coated steel sheet was not obtained, so that it could not be used.

[0029]

According to the present invention, it is possible to impart performance such as concealing properties to one or both sides of a support without complicated processing, and to remove adhesive from the sign when peeling the adhesive sheet from the sign. A sheet is obtained.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on at least one surface of a support, wherein the pressure-sensitive adhesive layer is formed of at least a pressure-sensitive adhesive component, an inorganic filler, and a silane coupling agent. .