JPH0237648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a top sheet for a flat keyboard used in copying machines and other equipment.

Conventionally, many keyboards for instructing copying machine ON/OFF signals, the number of copies, etc., have individual button-type keys embedded in the keyboard surface. However,
These keys had to be individually molded from plastic and had to fit onto the board, which tended to increase the price. Furthermore, since the key is mounted so that it can be moved up and down, a slight gap is created in the fitting hole on the panel surface, which has the disadvantage that dust can enter through this gap.

In recent years, so-called flat keyboards have come into use in place of such keyboards consisting of individual button-type keys. This flat keyboard has a built-in contact switch called a click switch in the location corresponding to each key, and the switch is pressed with a finger via a plastic top sheet. . As the functions of devices become more advanced, the types of keys on keyboards become more diverse and the number of keys increases.As a result, a simple flat sheet does not provide a feeling of contact with the fingers, making key presses more likely to malfunction.

The present invention was made in view of the above circumstances, and the gist thereof is to print various keys and other desired indications on a flexible acrylic multilayer polymer sheet, and then print the sheet. A method of manufacturing a surface sheet for a flat keyboard, characterized in that a portion corresponding to a key is bulged from the back side by cold pressing.

The present invention will be described below with reference to drawings of examples. Figure 1 is a perspective view of a top sheet for a flat keyboard obtained by the present invention, and Figure 2 is an enlarged sectional view taken along the line of Figure 1. be.

In the figure, 1 is a flexible acrylic multilayer polymer sheet, 2 is a display applied to the sheet, 3 is a matte surface, and 4 is a printed layer. The display 2 applied to the acrylic multilayer structure polymer sheet 1 is determined depending on the model or design, but in the example, a top sheet for a copying machine is shown.
21 is the numeric keypad display, 22 is the start button display, 23 is the paper size display, 24 is ON-OFF
It is a display.

In the top sheet obtained by the present invention, the key-corresponding portion of the acrylic multilayer structure polymer sheet 1 bearing the above-mentioned indication 2 is located on the back surface of the sheet as shown in FIG. It is pressed and shaped by cold pressing from the side and bulges out slightly. As mentioned above, the flat keyboard has a built-in click switch, and by pressing with a finger a key portion printed in correspondence with this switch, an operation signal is sent. The stroke of this click switch is approximately 0.3 to 1 mm at most, and is sensed by the fingertip, but compared to conventional button-type keys, the touch sensation is poor, and there is a risk of malfunction. In the present invention, in order to solve the problem that a flat sheet easily causes malfunction, the sheet corresponding to the keys is pressed and shaped from the back side to slightly bulge out. Note that the height of the bulge is preferably about 0.5 to 2 mm.

The acrylic multilayer structure polymer sheet 1 used in the present invention has a thickness of 0.2 mm with appropriate flexibility.
A sheet of about 1.0 mm is used, and since this sheet 1 can be cold pressed, it has the characteristic that the top sheet can be manufactured efficiently. Furthermore, acrylic multilayer polymers have excellent weather resistance, whitening resistance, etc., and are therefore particularly preferred as sheets for flat keyboards. Here, the acrylic multilayer structure polymer refers to a multistage polymer whose main components are acrylic ester and methacrylic ester. Publication No. 49-46158,
JP 49-46159, JP 52-26901, JP 54-33277, JP 51-129449
Publication No. 52-56150, U.S. Patent No.
Polymers such as those shown in the specification of No. 3,562,235 and the specification of US Pat. No. 4,052,525 can be mentioned.
Among these acrylic multilayer structure polymers, the multilayer polymer for which the present applicant has already applied is particularly excellent in weather resistance, solvent resistance, stress whitening resistance, water whitening resistance, light diffusion property, and transparency. There are structural polymers. This multilayer structure polymer is a copolymer of 80 to 100 parts of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms or an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms (A ₁ ), and 0 to 20 parts. A monomer having a possible double bond (A ₂ ), 0 to 10 parts of a polyfunctional monomer (A ₃ ), 0.1 to 5 parts per 100 parts of the total amount of (A ₁ ) to (A ₃ )
The innermost layer polymer consists of a composition of graft cross-agents of
(A), 80 to 100 parts of an alkyl acrylate (B ₁ ) having an alkyl group having 1 to 8 carbon atoms, 0 to 20 parts of a monomer (B 2 ) having a copolymerizable double bond, 0 to 100 parts of a monomer (B ₂ ) having a copolymerizable double bond; 10 parts of polyfunctional monomer (B ₃ ), 0.1 to 5 parts per 100 parts of the total amount of (B ₁ ) to (B ₃ )
51 to 100 parts of an alkyl methacrylate having 1 to 4 carbon atoms (C ₁ ), and 0 to 49 parts of a monomer having a copolymerizable double bond. The basic structural unit is an outermost layer polymer (C) consisting of a polymer (C ₂ ) having a glass transition temperature of at least 60°C, and an intermediate layer (D ) as 10 to 90 parts of an alkyl acrylate (D ₁ ) having a C 1 to 8 alkyl group, 90 to 10 parts of an alkyl methacrylate (D ₂ ) having a C 1 to 4 alkyl group, 0 to 20 parts A monomer having a copolymerizable double bond (D ₃ ), 0 to 10 parts of a polyfunctional monomer (D ₄ ), and 100 parts of the total amount of (D ₁ ) to (D ₄ ) 0.1~5
At least an intermediate layer (D) consisting of a composition of a graft cross-agent of the structural polymer has a gel content of at least 50% and a residual metal content of 500 ppm or less.

A matte surface 3 is normally formed on the front surface of the acrylic multilayer structure polymer sheet 1 . The matte surface 3 is preferably a non-directional fine rough surface, that is, a satin surface. Note that the printed layer 4 can be provided without any change from a general method.

To explain the manufacturing process of the present invention, the flexible acrylic multilayer structure polymer sheet 1 used is the one described above, but when it is necessary to apply a matte finish, a transparent sheet with a satin finish formed on one side in advance is used. It is recommended to use a suitable sheet. And sheet 1 like this
A desired display is printed on the smooth surface of. This printing method is no different from the general method, but first, two parts of each display are printed in white, blue, red, etc., and then a black base coating is applied. Then, if necessary, an adhesive layer is formed on the printing surface, and release paper is laminated. Thereafter, this sheet 1 is subjected to cold pressing from the back side to slightly bulge out the portion corresponding to the key. This cold press processing can be performed at room temperature, so it is very easy to work with, and it is also efficient because it can be performed even after being treated with an adhesive.

Specific examples will be described below, and all parts and percentages of substances used in these examples are by weight.

(1) Manufacture of multilayer polymer: 250 parts of ion-exchanged water in a polymerization container equipped with a cooler.
2 parts of ester soda salt of sulfosuccinic acid, sodium formaldehyde sulfoxylate
After charging 0.05 parts and stirring under nitrogen, 1.6 parts of methyl methacrylate (MMA), 8 parts of butyl acrylate (BuA), 0.4 parts of 1.3-butylene dimethacrylate (BD), and allyl methacrylate (AMA).
A mixture consisting of 0.1 part and 0.04 part of quement hydroperoxide (CHP) was charged. 70
After raising the temperature to ℃, the reaction was continued for 60 minutes to form the innermost layer polymer.
(A) The body was salted using 5 parts of calcium chloride per 100 parts of the body, thoroughly washed, dehydrated, and dried to obtain a dry powder.

Next, this dry powder was extruded at 230°C using an extruder having a screw with a diameter of 40 mm, and cut into pellets.

(2) Manufacture of transparent sheet After thoroughly drying the obtained pellets,
A T-die is installed in an extruder having a screw of the same diameter, and a rubber roll with a satin finish on the surface of the roll and a metal roll with a similar finish are installed in the vicinity of the die, and the temperature of the extruder is set at 220-230.
℃, a die temperature of 240℃, and a metal roll temperature (cooling water outlet temperature) of 40℃ to obtain a transparent sheet with a thickness of 0.25 mm. The characteristics of the obtained sheet were as follows.

Total light transmittance (ASTM-D-1003) 92.0% Haze value (ASTM-D-1003) 4.5% 60 degree reflectance (ASTM-D-523) Metal roll surface
7.2 Rubber roll surface 7.8 Tensile strength at break (ASTM-D-882) 230Kg/ ^cm2 Tensile modulus (ASTM-D-882) 9200Kg/ ^cm2 Tensile elongation at break (ASTM-D-882) 24% (3) Printing and Adhesive Treatment A display as shown in FIG. 1 was printed on the side surface of the rubber roll of the transparent sheet using a screen printing method. Acrylic resin-based printing ink was used for five-color printing. Adhesive treatment was applied from above the printed layer, and release paper was further laminated.

(4) Cold Pressing The adhesive-treated sheet obtained in (3) above was loaded into a foot-operated press, and pressed at room temperature using a mold in which only the numeric keypad portion protruded.

The bulge height of the numeric keypad portion of the sheet thus obtained was approximately 0.5 mm.

(5) Attachment to keyboard The release paper of the top sheet of the present invention obtained in (4) above was removed, and the sheet was adhered onto a flat keyboard.

When we tested the tactile sensation of the keyboard obtained in this way, it was found that a clear tactile sensation was obtained despite the bulge height of approximately 0.5 mm, and it was an excellent keyboard with no unnecessary discomfort or deterioration of appearance. Ta.

Since the present invention has the above-described structure, the surface sheet obtained by the present invention has a good tactile sensation because the key-corresponding portions are pressed and shaped by cold pressing and are slightly bulged. Malfunctions can be prevented from occurring, and since this bulging part is formed by plastic deformation of the sheet itself, it is durable, weather resistant, and anti-whitening, unlike those that come into contact with other objects. It has the advantage of being able to maintain a beautiful appearance for a long period of time because of its excellent surface properties, as well as being able to efficiently manufacture such an excellent surface sheet.

[Brief explanation of drawings]

The drawings show examples of the topsheet obtained by the present invention, and FIG. 1 is a perspective view of the topsheet, and FIG. 2 is a sectional view taken along the line of FIG. 1. 1... Acrylic multilayer structure polymer sheet, 2...
...Display, 3...Matte surface.

Claims (1)

[Claims] 1. Various keys and other desired indications are printed on a flexible acrylic multilayer polymer sheet, and then the key-corresponding portions of the sheet are cold-pressed from the back side. A method for manufacturing a surface sheet for a flat keyboard, which is characterized by slightly bulging. 2. The method for producing a top sheet for a flat keyboard according to claim 1, wherein the front surface is matte-finished.