JPS6251493A - Sheet for overhead projector - Google Patents

Abstract

PURPOSE:To provide a sheet for OHP capable of projecting the reversal image to a manuscript image and easily forming an image, by providing an upper layer comprising a composition having perforation forming capacity on a fiber substrate adsorbing or containing a thermal color forming composition having light transmission. CONSTITUTION:A manuscript 4 is superposed on the upper layer 3 of an OHP sheet 1 so as to face the manuscript surface 5 thereof to said layer 3 and a heat ray irradiation lamp 7 capable of irradiating high intensity energy within a short time is allowed to emit heat rays from the side of the substrate 2 of said sheet 1. At this time, because an image part 6 has a dark color, the heat generated by the emission of heat rays from the lamp 7 is accumulated in the image part 6 and each part 9 in contact with the image part 6 of the upper layer 3 is melted to form perforations 10 by heat shrinkage. Because the substrate 2 contains a thermal color forming composition, color parts 11 are formed on the parts coinciding with the perforations 10. By this method, a perforation image is formed on the upper layer 3 corresponding to the image of the manuscript 4 and, at the same time, a thermally developed color image is formed on the substrate 2 and, if a darken hue is employed as the color of said color image compared to the color possessed by the upper layer 3, a positive image is formed on the OHP sheet 1' having from a visual aspect the image formed thereto corresponding to the manuscript 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sheet used in an overbed projector (OHP), and more particularly to an OHP sheet in which a negative image is formed on an original image by a thermal method. .

(Prior Art) Conventionally, transparent film sheets have been used as OHP sheets. When forming an image on this sheet, particularly when forming an image in small quantities on an arbitrary document, an image forming method based on electrophotography is often used.

The image created by this electrophotographic method has the same format as the original image, that is, a positive copy image is formed for a positive original. Although the positive copy image formed on this transparent film sheet has excellent visual visibility, when it is projected onto a screen using an OHP, the image area is affected by the toner image, which causes the light rays to flow onto the screen. Since the non-image areas are transparent, they constitute bright areas on the screen. Therefore, an image projected using such an OHP sheet mainly consists of bright areas, which are non-image areas, and an image is formed on the screen as a dark area. The reality is that such projected images are generally difficult to view.

In order to solve such problems, when forming an image on an OHP sheet using an electrophotographic method, a method using so-called reversal development in which the bright and dark areas of the original image are reversed may be considered.

However, although such a reversal development method is employed in special image forming apparatuses such as laser printers, it is hardly employed in general copying machines.

Furthermore, even if a negative image could be created by reversal development, the projected image would be only the bright image area, and the projected image would not be aesthetically beautiful.

Therefore, the OHP is designed so that a negative image is projected on the screen.
Even if an image is formed on the sheet, it is OH
From the viewpoint of improving visual visibility when setting the P sheet itself on an OHP, it is desirable to form a positive image.

(Object of the Invention) An object of the present invention is to provide an OHP sheet on which an inverted image can be projected onto a document image and image formation can be easily performed.

Another object of the present invention is to provide an OHP sheet in which the dark areas of a negative image can be projected together with the image as a colored background, and the image can be projected with excellent visibility and visual aesthetics.

Still another object of the present invention is to provide an OHP sheet capable of forming a negative image when projected and a positive image when viewed visually.

(Summary of the Invention) In order to achieve the above-mentioned object, the OHP sheet of the present invention is made of a composition having perforation formation ability on a fiber substrate that has translucency and adsorbs or contains a thermochromic composition. It has a structural feature in that it has an upper layer.

(Contents of the Invention) The OHP sheet of the present invention has been devised based on the principle shown below.

The OHP sheet indicated by the number (1) in Figure 1 has a base (
2) and an upper layer (3) made of a composition having the function of forming perforations by heat absorption provided on one side of the substrate.
).

The substrate (2) is made of fibrous material and has many pores, and when light passes through the pores, the substrate (2) exhibits translucency. And this base (2
) contains a composition that develops color by absorbing heat by means such as adsorption.

The upper layer (3) also has the function of absorbing heat and forming perforations therein. This function is similar to the function employed in stencil paper normally used for heat-sensitive stencils. This upper layer (3) itself is also translucent, but in order to identify the image projected on the screen, it passes through the pores in the base (2) and then through the perforations in the upper N (3). The upper layer (3) itself has certain optical properties such that the wavelengths of light that pass through the pores of the base paper (2) and then through the upper layer (3) itself are different. is also necessary.

The principle of image formation on an OHP sheet having such characteristics will be explained.

The original (4) is placed on the upper layer (3) of the OHP sheet (1) with its original surface (5) facing each other (FIG. 2-a).

The document used has an image area (6) formed as a dark color area such as black or dark blue that has excellent heat absorption ability. For example, it is a copy or a printed matter having a toner image.

Next, a heat ray irradiation lamp (7) such as a xenon flash lamp or an infrared lamp capable of irradiating high-intensity energy in a short period of time is caused to emit light from the base (2) side of the OHP sheet (1) (FIG. 2-b). At this time, since the image area (6) is dark in color and has better heat absorption ability than the non-image area (8), the heat generated by the light emitted from the lamp (7) is accumulated in the image area (6). In the part (9) of upper N (3) that is in contact with the image part (6), the part (9) is melted by the heat accumulated in the image part (6), and a perforation ( 10) is formed (Figure 2-○).

Further, while the perforations (10) are formed, since the substrate (2) contains a thermochromic composition, the image area (6)
The substrate (2) undergoes perforation (10) due to the heat accumulated in the
) The thermochromic composition develops color to form a colored part (11) (FIG. 2-C).

Thus, the OHP sheet (1) corresponds to the image of the original (4).
), a perforation image is simultaneously formed on the upper layer (3), and a thermochromic image is simultaneously formed on the substrate (2).

If the thermally developed color is darker than the color of the upper layer (3), the OHP sheet (1') on which the image has been formed will visually correspond to the original (4) and have a positive image. was formed.

Next, when this OHP sheet (1') is used as a projection document, the difference between the light emitted from the OHP main body that has passed through the perforations in the upper layer (3) and the light that has passed through the upper layer (3) itself. An image is formed to be projected onto the screen in response to the difference in wavelength. At this time, the light passing through the hole passes through the substrate (2
), but since the color development only causes the fibers that make up the substrate (2) to develop color, the light passing through the pores between the fibers (image light ) allows the colored light of the light source of the OHP body to reach the screen without being affected by this color development.

On the other hand, in the non-image, the light emitted from the light source passes through the pores between the fibers that are also present in the uncolored area (12) of the substrate (2), and then passes through the upper layer (3) itself. A specific wavelength is cut off by the filter effect of the composition constituting the upper layer (3) and reaches the screen as colored light (non-image light).

Thus, by using the above-described OHP sheet (1'), it is possible to project a negative image having a colored non-image area and an uncolored image area onto the screen.

OHP sheet The OHP sheet of the present invention is a laminated structure including a base (2) and an upper layer (3) based on the above-mentioned principle.

As the substrate (2), based on the above-mentioned principle, a fiber sheet with a large number of pores is used, since it needs to satisfy the light transmission ability (translucency) and also have the ability to adsorb or contain the thermochromic composition. used.

Such fiber sheets are not limited to these, but include, for example, heat-sensitive stencil paper before wax coating, 3
A sheet such as a nylon sheet, woven fabric, or silk screen sheet with a mesh size of 00 to 500 can be used. The pores of this sheet are 1 to 500 μm from the viewpoint of translucency.
Preferably, the size is 10 to 200 μm. In addition, the thickness of the sheet is desired to be thin in order to improve the propagation of heat during image formation in terms of the image quality of the perforated image of the upper layer (3), which will be described later, such as clarity and sharpness. A certain degree of strength is required from the viewpoint of holding capacity and durability as an OHP sheet. From this point of view, the thickness is 50 to 500μm, preferably 50 to 20゛.
It is preferable to use a sheet with a thickness of 0 μm.

As the thermochromic composition to be adsorbed or contained in the substrate (2), a known composition used in the fields of thermal copying paper and thermal recording paper can be used.

For example, a combination of a pair of thermoreactive compounds, an electron acceptor and an electron donor, is used.

An example of this is iron stearate (■) as an electron acceptor.
; Nickel stearate, copper stearate (■), silver behenate, lead myristate are used, and organic reducing agents such as phenols, metal sulfides, organic chelating agents, organic sulfur compounds, etc. are used as electron donors. , metal compound systems in which colored substances such as metals, metal sulfides and metal oxides are formed by heating, and dye coloring systems in which oxazine dyes are formed through thermochemical reactions between resorcinol and nitroso compounds. Crystal violet lactone (
CVL), a thermochromic reaction system of colorless dyes consisting of a combination of colorless dyes such as fluoran and spirones, and phenolic compounds such as bisphenol A, and organic and inorganic acids, or indole derivatives, pyrroline derivatives, dithiocarbamate metal salts, etc. Single thermal dyes etc. can be used. Among these, thermal coloring systems using metal compounds or colorless dyes granulate one or both components and develop color by thermally melting them. It is necessary to use a system in which fine particles of the substance are dispersed in a binder.

Among these thermocoloring compositions, from the viewpoint of economy and the like, it is desirable to use a colorless dye that causes a coloring reaction accompanying thermal melting of the CVL and bisphenol A fine particle dispersion system. Regarding the use of this system, as a binder material, leuco dye particles represented by CVL are used in a polymer binding ratio of 30 to 70 wt%, especially 40 to 60 wt%, such as organic carboxylic acid partially esterified starch or hydroxymethyl starch.
t%, organic acidic substance particles represented by bisphenol A (100 to 400 wt%, especially 150 to 350 wt%)
% and adsorbed or contained in the substrate.

As mentioned above, in the upper layer (3), the non-image area is projected onto the screen as a colored background, and the image area is formed by forming perforations using a heat-sensitive method, and the projection that passes through the perforations. This layer has the function of projecting light onto a screen as a bright area.

This coloring composition layer (3) satisfies the above-mentioned functions, so that it can be applied to waxes such as polyethylene wax, fatty acid amide, fats and oils at a concentration of 0.1% per 100 parts by weight of wax.
It consists of a composition in which dyes are dispersed or dissolved in a quantitative ratio of 20 to 20.

The dye used as a coloring agent needs to have the function of coloring the wax or film material described above in order to make the background any desired color such as blue, red, or yellow when projecting on an OHP sheet. and a colored composition material layer (3)
Although the dye itself does not have the same translucency as the image area (the bright area on the screen), it requires the ability to project the non-image area as a colored background, so this dye also has a certain degree of transparency after dyeing. Requires transparency.

Such dyes include phthalocyanine blue, Guianpuru blue dye, perylene red, eosin, rose bengal red dye, oil Yellow 5-7 (
Orient Yellow
In addition to yellow dyes such as GG (manufactured by Orient Chemical Co., Ltd.), dyes having various colors such as monoazo, anthraquinone, leucomalachite green, and violanthrone chloride can be used.

In this case, from the viewpoint of visual visibility of the OHP sheet, it is desirable that the dye used in the non-image area be lighter in color than the color-forming substance used in the image area, or a different color.

When producing an OHP sheet, when using a wax-dye coloring composition layer on a substrate adsorbed or containing the above-mentioned thermal coloring composition, wax, wax, It can be produced by applying a composition in which dyes are dissolved or dispersed in the above-mentioned quantitative ratios in a layer thickness of 1 to 40 μm using a coating method known per se, such as barcoding, roll coating, or knife coating.

(Effects) The OHP sheet according to the present invention described above can create an OHP projection original using a simple method similar to the conventional electrophotographic method, and when viewing the OHP projection original, it is possible to create an OHP projection original using a simple method. , a positive image in which the image area is colored in a dark color is formed, and when projected, a negative image is formed in which the image area is a bright area with the colored non-image diagram as the background.

As a result, it is possible to create an OHP sheet with excellent visibility and visual aesthetics both visually and as a projected image.

Further, by selecting the thermochromic composition, various visual images such as black, blue, and red can be formed, and the color of the non-image area can be arbitrarily selected by selecting the dye used in the upper layer.

Therefore, you can select the type of manuscript, such as blue for a graph diagram, green for a list diagram, or red for a manuscript that is particularly important to the user and that you want to appeal to. The OHP sheet of the present invention also has particularly excellent effects in terms of visual recognition.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of the OHP sheet of the present invention, and FIG. 2 is an image creation process diagram showing the principle of the OHP sheet of the present invention.゛In the figure, clear numbers indicate the following contents. 1.1'... OHP sheet 2... Substrate 3... Upper layer 4... Original 6... Image area 8... Non-image area 10... Perforation 11... Coloring area 12.・Uncolored area

Claims (1)

[Claims] (1) A sheet for an overhead projector, characterized in that a composition layer having perforation forming ability is provided on a fiber substrate that is transparent and adsorbs or contains a thermochromic substance.