JPH028751Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a laminated sheet used for manufacturing membrane switches used in keyboard switches mainly used in electronic devices such as calculators, facsimiles, and word processors. .

Technical background of the invention and its problems Membrane switches are mainly made of polyurethane sheets and have a good texture and excellent wear resistance, so they can be used in calculators, facsimile machines, word processors, etc. It is beginning to be used in electronic devices such as Setsa. This membrane switch conventionally involves pasting release paper on the surface of a transparent or translucent polyurethane sheet, printing letters or symbols in multiple colors on the back side of the polyurethane sheet in several steps, and then printing the release paper on the back side of the polyurethane sheet. It has been manufactured by exfoliating.

However, after these polyurethane sheets are attached to electronic devices, they are exposed to sunlight,
If it is left in a high temperature room, it may shrink or expand semi-permanently, resulting in a serious problem of dimensional deviation from the main body of the electronic device. In addition, when printing characters or symbols in multiple colors on a polyurethane sheet in multiple steps, the sheet may shrink due to the ink solvent, which may cause misalignment in the printing location of the second and subsequent colors. This causes misregistration, resulting in a high number of defective products.

These problems become more noticeable when trying to reduce the thickness of the polyurethane sheet, so despite the demand for thin membrane switches, membrane switches are not made from thin polyurethane sheets. It was extremely difficult to do so.

Moreover, in the past, opaque release paper was pasted onto the polyurethane sheet, so it was not possible to check the printing status on the back side of the polyurethane sheet from the actual surface through the release paper, and the printing process was completed several times. The printing condition could not be checked unless the release paper was peeled off after printing. For this reason, even if a deviation occurs during the printing process, printing must be continued to the end, resulting in problems such as wastage of ink or urethane sheet.

Purpose of the invention The present invention attempts to solve the problems associated with the prior art as described above, and has the following objects.

(a) To provide a laminated sheet suitable for forming a membrane switch, etc., which shows no shrinkage or elongation even when exposed to sunlight or high temperatures, and has an excellent texture.

(b) When manufacturing multicolor printed sheets such as membrane switches, the sheet does not shrink even if multicolor printing is performed on the sheet in multiple steps, and therefore, there is little printing misalignment, which is excellent performance. To provide a laminated sheet suitable for forming a multicolor printing sheet having the following properties.

(c) To provide a laminated sheet suitable for forming a membrane switch or the like that allows the printing state to be visually confirmed from the practical surface even during the multicolor printing process.

Summary of the invention A laminated sheet suitable for forming a membrane switch or the like according to the invention consists of a first transparent or translucent plastic sheet, a transparent or translucent polyurethane sheet laminated on this sheet, and a polyurethane sheet laminated on this sheet. It is characterized by comprising a transparent or translucent plastic second sheet that can be peeled off from a polyurethane sheet provided on the sheet.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to embodiments shown in the drawings.

A laminated sheet 1 suitable for forming a membrane switch or the like according to the present invention, as shown in FIG. It is composed of a transparent or translucent polyurethane sheet 3 provided on the polyurethane sheet 3, and a transparent or translucent plastic second sheet 4 that can be peeled off from the polyurethane sheet provided on the polyurethane sheet 3.

Further, as shown in FIG. 2, a laminated sheet 1 suitable for forming a membrane switch according to the present invention.
After applying multicolor printing 5 on the transparent or translucent plastic first sheet 2 and peeling off the peelable transparent or translucent plastic second sheet 4 from the polyurethane sheet 3, the polyurethane sheet 3 is applied to the pressing surface. calculator, facsimile,
It is used by being attached to a keyboard switch 6 of an electronic device such as a word processor.

The plastic first sheet 2 is transparent or translucent, and does not shrink or expand even when exposed to sunlight or high temperatures, and has excellent solvent resistance without shrinkage due to ink solvents during multicolor printing. Specifically, polycarbonate sheets, polyester sheets, polyamide sheets, polyvinyl chloride sheets, etc. are used. Among these, polycarbonate sheets are particularly preferred. The reason for this is as follows. In other words, the polycarbonate sheet has excellent thermal adhesion with the polyurethane sheet, so the lamination process described below is easy, and since the polycarbonate sheet has a coefficient of thermal expansion relatively similar to that of the polyurethane sheet 3, when heated, This is because stress strain is less likely to occur between both sheets.

The thickness of this first plastic sheet 2 is 10μm
~150 μm, preferably 30 μm to 100 μm.

The polyurethane sheet 3 becomes the pressing surface of the membrane switch when the laminated sheet 1 according to the present invention is used as a membrane switch, and therefore provides a good feel to the switch surface and also provides excellent wear resistance. I can do it.

The thickness of this polyurethane sheet 3 is 10~
It is desirable that the thickness be 300 μm, preferably 50 to 200 μm.

Further, the total thickness of the first plastic sheet 2 and the polyurethane sheet 3 is preferably 20 to 450 .mu.m, preferably 80 to 300 .mu.m.

By creating a structure in which the polyurethane sheet 3 and the plastic first sheet 2 are laminated, compared to the case where the polyurethane sheet has a single structure,
Even if exposed to sunlight or high temperatures,
Almost no contraction or elongation is observed.
Further, during the printing process, the sheet is prevented from shrinking due to the ink solvent, and printing misalignment is less likely to occur.

In the present invention, the second plastic sheet 4 is peeled off from the polyurethane sheet 3 after characters or symbols are printed on the laminated sheet. That is, this second plastic sheet 4 plays the role of a release sheet. The reason for providing this second plastic sheet is as follows. First of all, as mentioned above, the surface of the polyurethane sheet 3 becomes the switch pressing surface, so in some cases it is desired that it be a frosted surface like frosted glass, but in such cases, a release sheet may be provided. This is because fine irregularities can be formed on the surface of the polyurethane sheet to give it a matte surface.

Second, the second plastic sheet 4 serves as a protective sheet to prevent scratches or stains on the surface of the polyurethane sheet during printing, punching, and other processes, thereby improving the quality of the final product. This is because it can be done.

Third, when printing characters or symbols on the laminated sheet according to the present invention, providing the second plastic sheet facilitates sheet feeding.

Since this second plastic sheet 4 plays the role of a release sheet as mentioned above, it needs to be made of a polymer that can be peeled from the polyurethane sheet and does not adhere to it, and specifically, it is made of polyethylene. , polypropylene, polyester, or the like.

Among these, polypropylene is the most preferable from the viewpoint of peeling force from the polyurethane sheet (100 g/15 mm or less), heat resistance, and cost. It is also possible to add inorganic fillers to these polymers within a range that does not impair their transparency, and this is effective in forming fine irregularities on the surface of the polyurethane sheet.

Preferably, the second plastic sheet 4 is transparent or translucent. The reason is as follows. That is, characters or symbols are printed on the laminated sheet 1 according to the present invention, and the printing is done on the bottom surface of the first plastic sheet 2. At this time, if the plastic second sheet 4 is opaque, the printing state cannot be checked during printing, and even if a shift occurs during printing, printing must be carried out to the end. However, if the plastic second sheet 4 is transparent or semi-transparent, the printing condition can be visually checked, and the printing can be observed to ensure that there is no misalignment, and if misalignment occurs, printing can be stopped. This is because the deviation can be corrected immediately.

Furthermore, when the plastic second sheet 4 is made of a polymer film such as polyethylene or polypropylene, water absorption is prevented and the printing process is facilitated compared to the case of a conventional release sheet such as paper. This prevents the laminated sheet 1 from curling at times.

As mentioned above, the laminated sheet 1 according to the present invention is preferably used particularly as a sheet for forming membrane switches, but is not limited to this use, and can be widely used as a sheet on which multicolor printing is performed. be able to.

Next, a method for manufacturing a laminated sheet according to the present invention will be described.

The most preferred method for manufacturing a laminated sheet according to the present invention is to simultaneously extrude two layers of a polyurethane sheet 3 and a second plastic sheet 4 on a first plastic sheet 2 to form a laminated layer.
In this method, laminated sheets of various configurations can be formed by changing the first plastic sheet 2 according to the application and required performance, and the final product can be obtained in one step, which is advantageous in terms of manufacturing cost. In this case, a practically sufficient adhesive strength can be obtained by laminating the first plastic sheet 2 and the polyurethane sheet 3 with an adhesive, but when a polycarbonate sheet is used as the first plastic sheet 2, As mentioned above, polycarbonate and polyurethane have thermal adhesive properties, so just by extruding two layers of polyurethane sheet 3 and plastic second sheet 4 at the same time onto a polycarbonate sheet, they are thermally fused and a highly transparent laminated sheet is created. can get.

Another manufacturing method is to simultaneously extrude three layers of the first plastic sheet 2, the polyurethane sheet 3 and the second plastic sheet 4. In some cases, the first plastic sheet 2 and the polyurethane sheet 3 may be laminated with an adhesive, and then the second plastic sheet 4 may be attached.

Effects of the invention The laminated sheet suitable for forming the membrane switch according to the invention has a laminated structure of a first plastic sheet, a polyurethane sheet, and a second plastic sheet, so that the following curing is possible. can get.

(a) Almost no shrinkage or elongation is observed even when exposed to sunlight or high temperatures;
Moreover, it has excellent texture and durability.

(b) When printing characters, symbols, etc., shrinkage due to ink solvent does not occur, so printing misalignment is less likely to occur.

(c) The printing condition can be visually confirmed even at an intermediate stage during the multicolor printing process.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a laminated sheet according to the present invention, and FIG. 2 is a cross-sectional view of the laminated sheet according to the present invention used as a membrane switch after multicolor printing. 1... Laminated sheet, 2... Plastic first sheet, 3... Polyurethane sheet, 4... Plastic second sheet, 5... Multicolor printing, 6... Keyboard switch.

Claims (1)

[Scope of utility model registration request] A plastic first sheet made of transparent or translucent polycarbonate, polyester, polyamide, or polyvinyl chloride; a transparent or translucent polyurethane sheet provided on the first sheet; and a polyurethane sheet provided on the polyurethane sheet. A laminated sheet consisting of a second sheet of transparent or translucent plastic that can be peeled off from the first sheet.