JP3969798B2 - Touch panel adhesive sheet - Google Patents

Description

×：糸引き量大、使用不可
△：糸引き量小、使用困難
○：糸引きほとんど無し、使用可
◎：糸引き無し、使用可
【００１４】
分子量が２０万以下では粘着剤の糸引きが発生して使用不可であることが想定され、特に１０万以下では使用できない。これに比べ、分子量が５０万以上になると糸引きの影響はなく確実に使用可能となり、特に７０万〜１００万で糸引きは完全になくなり良好であることがわかった。
【００１５】
【発明の効果】
以上説明したように、本発明のタッチパネル用粘着シートによれば、まず、感圧端子の介装空間を形成するために表側セパレートシートを打ち抜いて除去する際、この表側セパレートシートが合成樹脂製なので打ち抜き切断面から紙粉等が落下しない。また、表側セパレートシートの剥離力が裏側セパレートシートの剥離力よりも小さく設定され、さらに、表側粘着層が分子量２５万から１００万と比較的高い高分子系粘着剤で形成されているので、表側セパレートシートを剥がす際の表側粘着層の糸引きが抑制される。これらの結果、感圧端子の介装空間への異物の混入が未然に防止され、通電不良に伴う入力エラーが生じない高品質なタッチパネルを製造することが可能となる。
【図面の簡単な説明】
【図１】 本発明の一実施形態に係るタッチパネル用粘着シートの断面図である。
【図２】 本発明の一実施形態に係るタッチパネル用粘着シートによりタッチパネルを製造する工程１を示す断面図である。
【図３】 同工程２を示す断面図である。
【図４】 同工程３を経て製造されたタッチパネルの断面図である。
【図５】 従来のタッチパネル用粘着シートの一例を示す断面図である。
【図６】 従来のタッチパネル用粘着シートによりタッチパネルを製造する工程１を示す断面図である。
【図７】 同工程２を示す断面図である。
【図８】 同工程３を経て製造されたタッチパネルの断面図である。
【符号の説明】
１…タッチパネル用粘着シート、２…シート基材、３…表側粘着層、
４…裏側粘着層、５…表側セパレートシート、６…裏側セパレートシート、
７…裏側パネル、８…表側パネル、９…タッチパネル、９ａ…介装空間。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure-sensitive adhesive sheet for a touch panel constituting a touch panel.
[0002]
[Prior art]
In recent years, pressure-sensitive touch panels are often used for bank ATMs, copier operation panels, portable information communication device input panels, and the like. In general, the touch panel has a pressure-sensitive terminal sandwiched between the front and back sheets, and the pressure-sensitive terminal is turned on by pressing or touching the front-side sheet, and a circuit corresponding to the terminal is driven. ing. Such a touch panel is conventionally a pressure-sensitive adhesive sheet in which release papers 13 and 14 are adhered to the front and back surfaces of a synthetic resin sheet base material 10 via pressure-sensitive adhesive layers 11 and 12, as shown in FIG. It was manufactured based on. In order to manufacture a touch panel from this pressure-sensitive adhesive sheet, first, as shown in FIG. 6, the release paper 14 on the back side is peeled off, and the remaining part is attached to the surface of the back-side panel 15 via the back-side pressure-sensitive adhesive layer 12. Next, the central portion indicated by a broken line in FIG. 6 is punched and removed while leaving the periphery of the remaining portion and the back panel 15 (FIG. 7). Finally, the front side release paper 13 remaining around is peeled off, the front side panel 16 is stuck on the front side adhesive layer 11, and the touch panel having the pressure sensitive terminal interposing space 17 a between the front and back panels 16, 15. 17 is obtained (FIG. 8). In addition, the sheet base material 10 may be used in which a punched portion is punched in advance, and in that case, the release paper 13 on the front side and the adhesive layers 11 and 12 are punched out.
[0003]
[Problems to be solved by the invention]
By the way, in the above-mentioned conventional pressure-sensitive adhesive sheet, when the central portion is punched and removed in order to form the interposition space 17a of the pressure-sensitive terminal, paper dust or fine paper dust is disposed from the cut surface of the release paper 13 on the front side. There is a case where it falls on the back panel 15 in 17a, and in this state, an input error is caused due to a poor conduction of the pressure sensitive terminal. In addition, when the release papers 13 and 14 are peeled off, the adhesive layers 11 and 12 are too soft, so that the so-called stringing phenomenon in which the adhesive layers 11 and 12 remain attached to the release papers 13 and 14 in a string form is likely to occur. It was. In particular, when stringing occurs from the front side adhesive layer 11, the adhesive drops onto the back panel 15 and an input error may occur as in the case of paper dust or paper waste.
Accordingly, the present invention provides a touch panel for manufacturing a high quality touch panel in which foreign matter such as paper dust, paper scraps or adhesive is prevented from being mixed in the space where pressure sensitive terminals are provided in the touch panel manufacturing process. The purpose is to provide an adhesive sheet.
[0004]
[Means for Solving the Problems]
The pressure-sensitive adhesive sheet for a touch panel of the present invention is obtained by attaching a front-side separate sheet and a back-side separate sheet to a front surface and a back surface of a sheet base material via a front-side adhesive layer and a back-side adhesive layer, respectively, and the back-side separate sheet is peeled off. After being attached to the back side panel by the back side adhesive layer, a part of the front side part is punched out from the back side panel to form an interstitial space for the pressure sensitive terminal, and then the front side panel is attached to the front side adhesive layer In the pressure-sensitive adhesive sheet for a touch panel, at least the front-side separate sheet of each of the separate sheets is made of a synthetic resin, and the peeling force of the front-side separate sheet with respect to the front-side adhesive layer is peeled off from the back-side separate sheet with respect to the back-side adhesive layer. It is smaller than the force and 150 to 500 gf / 10 mm .
According to this pressure-sensitive adhesive sheet for a touch panel, when the front-side separate sheet is punched and removed to form an interposition space for pressure-sensitive terminals, the front-side separate sheet is made of synthetic resin, so as in the case of conventional release paper In addition, foreign matters such as paper dust and paper scraps do not fall on the back panel from the cut surface. That is, no foreign matter is mixed in the intervening space, so that an input error due to a poor conduction does not occur in the manufactured touch panel.
[0005]
Now, after punching out the front-side separate sheet, when peeling off the front-side separate sheet remaining for adhering the front-side panel from the front-side adhesive layer, the adhesive of the front-side adhesive layer adheres to the front-side separate sheet as described above. There was a problem that caused pulling. The present inventor has reached an inference that the cause of this stringing phenomenon is due to the viscosity (hardness) of the adhesive layer, and that the stringing may be suppressed if the adhesive layer is relatively hard. Therefore, the inventor paid attention to the molecular weight of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, and conducted a peeling test with various molecular weights set. As a result, stringing was effectively suppressed in the range of molecular weight of 250,000 to 1,000,000. Further, it has been found that a preferable peeling property is exhibited when it is 500,000 to 1,000,000.
That is, in the present invention, the molecular weight of the polymer-based pressure-sensitive adhesive that forms at least the front-side pressure-sensitive adhesive layer of the front-side pressure-sensitive adhesive layer and the back-side pressure-sensitive adhesive layer is set in a range of 250,000 to 1,000,000. And more preferably around 500,000 to 1,000,000.
[0006]
Moreover, the front side separate sheet punched out to form the interposition space for the pressure-sensitive terminal is often punched out at the center and remains in a thin frame shape in many cases. Therefore, the peeling force is difficult to be transmitted and difficult to peel off. However, in the present invention, the peeling force of the front side separate sheet is smaller than that of the back side separate sheet, so the dissatisfaction that it is difficult to peel off is eliminated.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a cross section of a pressure-sensitive adhesive sheet for touch panel (hereinafter abbreviated as pressure-sensitive adhesive sheet) 1 according to an embodiment, and reference numeral 2 in the figure denotes a sheet base material. The sheet substrate 2 is made of a synthetic resin such as PET (polyethylene terephthalate), and has a thickness of, for example, 10 to 100 μm, preferably about 25 to 50 μm. On the front surface and back surface (upper surface and lower surface in FIG. 1) of the sheet base material 2, an adhesive is applied to a certain thickness (for example, 30 μm), and a front-side adhesive layer 3 and a back-side adhesive layer 4 are respectively formed. . Here, as the pressure-sensitive adhesive forming each of the pressure-sensitive adhesive layers 3 and 4, an acrylic-based polymer pressure-sensitive adhesive having a relatively high molecular weight is used. The molecular weight is preferably in the range of 250,000 to 1,000,000, and more preferably in the range of 500,000 to 1,000,000.
[0008]
A front-side separate sheet 5 and a back-side separate sheet 6 are attached to the front and back surfaces of the sheet substrate 2 via the respective adhesive layers 3 and 4. These separate sheets 5 and 6 are made of a synthetic resin such as the above-described PET as in the case of the sheet base 2 and have a thickness of, for example, about 10 to 125 μm, preferably about 30 to 100 μm. These separate sheets 5 and 6 are peeled off from the sheet base material 2 when the pressure-sensitive adhesive sheet 1 is used, and the peeling force for each of the pressure-sensitive adhesive layers 3 and 4 is, for example, 3 for the front-side separate sheet 5. When the peeling force of the front side separate sheet 5 is set smaller than that of the back side separate sheet 6 such that the back side separate sheet 6 is 9 to 12 g / inch, the workability is improved and the stringing is improved. It is preferable in terms of prevention. Thus, in order to make a difference in peel force between the separate sheets 5 and 6 on the front side and the back side, the degree of activation treatment applied to the adhesive surfaces 3 and 4 of the separate sheets 5 and 6 can be changed, Means such as adjusting the composition of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layers 3 and 4 are employed. Further, in this case, when the separate sheets 5 and 6 are peeled off, the adhesive layers 3 and 4 need to remain on the sheet base 2 side. Therefore, the sheets to which the adhesive layers 3 and 4 are applied are applied. The front and back surfaces of the base material 2 are subjected to an adhesion strengthening process by corona discharge or the like.
[0009]
The above is the adhesive sheet which concerns on one Embodiment, Then, the procedure which manufactures a touchscreen based on this adhesive sheet 1 is demonstrated.
First, as shown in FIG. 2, the back side separate sheet 6 is peeled off, and the remaining part is attached to the surface of the back side panel 7 of the touch panel via the back side adhesive layer 4. Next, leaving the periphery of the remaining portion and the back panel 7 and punching out and removing the central portion indicated by the broken line in FIG. 2, an interstitial space 9a for pressure sensitive terminals is formed, and the intermediate material shown in FIG. obtain. Then, after peeling off the front side separate sheet 5 remaining around, the front side panel 8 of the touch panel is stuck on the front side adhesive layer 3 as shown in FIG. Here, since the front-side separate sheet 5 remains in a frame shape with a narrow width by punching, it has been difficult to peel off conventionally, but in this embodiment, the peeling force of the front-side separate sheet 5 is smaller than that of the back-side separate sheet 6. Dissatisfaction that it is hard to peel off. In this way, the touch panel 9 having the pressure sensitive terminal interposed space 9a between the front and back panels 8 and 7 as shown in FIG. 4 is obtained. In addition, the sheet | seat base material 2 may use what the punching part was punched previously, and in that case, the front side separate sheet 5 and each adhesion layer 3 and 4 are punched.
[0010]
According to the pressure-sensitive adhesive sheet 1 of the above-described embodiment, the front-side separate sheet 5 to be punched when the central portion is punched and removed in order to form the interposition space 9a of the pressure-sensitive terminal is made of a synthetic resin. As in the case of pattern paper, foreign matter such as paper dust and paper waste does not fall on the back panel 7 from the punched and cut surface. Furthermore, since the front side separate sheet 5 is excellent in physical strength as compared with the release paper, there is no possibility of breaking when peeling and removing, and productivity is improved. In addition, the front side adhesive layer 3 (as well as the back side adhesive layer 4) is made of a high molecular weight adhesive having a relatively high molecular weight of 250,000 to 1,000,000. Since the peeling force of the front-side separate sheet 5 is set to be smaller than that of the back-side separate sheet 6, the stringing phenomenon of the front-side adhesive layer 3 that occurs when the front-side separate sheet 5 is peeled is suppressed. As a result, it is possible to prevent a foreign matter such as paper dust, paper waste, or adhesive from entering the intervening space 9a of the pressure sensitive terminal, and to manufacture a high-quality touch panel that does not cause an input error due to poor conduction. Is possible.
[0011]
In addition, although said front side and back side separate sheet | seats 5 and 6 said that they were made of synthetic resins, such as PET, this invention prevents the foreign material generation | occurrence | production from the cut surface of the front side separate sheet | seat 5 at the time of punching. Since it is aimed, at least the front side separate sheet 5 should just be a product made from a synthetic resin. As the synthetic resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylic resin, phenol resin, melanin resin and the like are used in addition to the polyester such as PET. Among these, PET can be said to be the most preferable material in terms of cost and moldability. Moreover, since the present invention aims to suppress the stringing of the adhesive of the front side adhesive layer 3 when the front side separate sheet 5 is peeled from the front side adhesive layer 3, the front side adhesive layer 3 and the back side adhesive layer 4 Of these, at least the front pressure-sensitive adhesive layer 3 is preferably formed of a polymer pressure-sensitive adhesive having a molecular weight of 250,000 to 1,000,000. Such molecular weight is measured by gel permeation chromatography. As the polymer adhesive, cellulose, alkyd, acrylic ester, polyamide or the like is used in addition to the acrylic. In addition, as the adhesive strength of such a polymer-based pressure-sensitive adhesive, in terms of 180 ° peel adhesive strength measured according to “JIS C2107”, those having about 150 to 500 gf / 10 mm are less likely to cause stringing, It is preferable because of its good adhesive force.
[0012]
【Example】
Next, an example in which the degree of stringing from the front-side separate sheet 5 is evaluated by changing the molecular weight of the polymer-based pressure-sensitive adhesive forming the front-side pressure-sensitive adhesive layer 3 based on the one embodiment will be described. An acrylic pressure-sensitive adhesive having a molecular weight of 100,000, 200,000, 500,000, 700,000, and 1 million is applied to the surface of the sheet substrate 2 with a thickness of 30 μm to form the front-side pressure-sensitive adhesive layer 3. Table 1 shows the results of evaluation of the degree of stringing after the front-side separate sheet 5 made of PET and having a thickness of 38 μm and a peel strength of 3 g / inch was adhered to the layer 3 and then the front-side separate sheet 5 was peeled off.
[0013]
[Table 1]

×: Threading amount large, unusable △: Threading amount small, difficult to use ○: Almost no threading, usable ◎: No threading, usable
If the molecular weight is 200,000 or less, it is assumed that stringing of the pressure-sensitive adhesive occurs and cannot be used. Compared with this, it was found that when the molecular weight was 500,000 or more, there was no influence of stringing and it was possible to use it reliably, and it was found that the stringing was completely eliminated particularly at 700,000 to 1,000,000.
[0015]
【The invention's effect】
As described above, according to the pressure-sensitive adhesive sheet for a touch panel of the present invention, when the front side separate sheet is first punched and removed to form an interposition space for the pressure sensitive terminal, the front side separate sheet is made of a synthetic resin. Paper dust does not fall from the punched cut surface. Further, the peel strength of the front side separate sheet is set to be smaller than the peel strength of the back side separate sheet, and the front side adhesive layer is formed of a relatively high polymer pressure sensitive adhesive with a molecular weight of 250,000 to 1,000,000. Stringing of the front adhesive layer when peeling the separate sheet is suppressed. As a result, it is possible to manufacture a high-quality touch panel in which foreign matter is prevented from entering the interposition space of the pressure-sensitive terminal, and no input error due to poor conduction occurs.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an adhesive sheet for a touch panel according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a process 1 for manufacturing a touch panel using a pressure-sensitive adhesive sheet for a touch panel according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing same process 2;
FIG. 4 is a cross-sectional view of the touch panel manufactured through the same process 3;
FIG. 5 is a cross-sectional view showing an example of a conventional touch panel pressure-sensitive adhesive sheet.
FIG. 6 is a cross-sectional view showing step 1 of manufacturing a touch panel using a conventional pressure-sensitive adhesive sheet for touch panel.
FIG. 7 is a cross-sectional view showing the same step 2;
8 is a cross-sectional view of the touch panel manufactured through the step 3. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet for touchscreens, 2 ... Sheet base material, 3 ... Front side adhesive layer,
4 ... Back side adhesive layer, 5 ... Front side separate sheet, 6 ... Back side separate sheet,
7 ... Back panel, 8 ... Front panel, 9 ... Touch panel, 9a ... Intervening space.

Claims (2)

A front-side separate sheet and a back-side separate sheet are bonded to the front and back surfaces of the sheet base material via a front-side adhesive layer and a back-side adhesive layer, respectively, and the back-side separate sheet is peeled off and the back-side panel is separated by the back-side adhesive layer. In the pressure-sensitive adhesive sheet for a touch panel in which a part of the front side part is punched out from the back side panel and an interstitial space for the pressure-sensitive terminal is formed, and then the front side panel is attached to the front side adhesive layer. ,
Wherein Ri least front separate sheet, synthetic resin der out of the separate sheet,
The pressure-sensitive adhesive sheet for a touch panel , wherein a peel force of the front-side separate sheet with respect to the front-side pressure-sensitive adhesive layer is smaller than a peel strength of the back-side separate sheet with respect to the back-side pressure-sensitive adhesive layer and is 150 to 500 gf / 10 mm . At least the front-side adhesive layer of the front-side adhesive layer and the back-side adhesive layer is formed by applying a polymeric adhesive having a molecular weight of 250,000 to 1,000,000 to the surface of the sheet base material. The pressure-sensitive adhesive sheet for a touch panel according to claim 1 .

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