JPS6331785A - Transparent sheet for dot impact recording - Google Patents

Abstract

PURPOSE:To obtain a sheet which makes it possible to directly form a manuscript by dot impact printing and to project sharp images on a screen by an OHP, by providing on the surface of a transparent base a coated film of a thermoplastic polyurethane having a thickness of at least 2 mum and comprising porous silica having an average particle diameter of not more than 5 mum, as required, while maintaining a ray transmittance of at least 60%. CONSTITUTION:A coated film of thermoplastic polyurethane at least 2 mum in thickness is provided on the surface of a transparent base. Since the coated film has an ink absorptivity suitable for dot impact recording inks, printing with favorable penetration and drying of the inks can be performed. Further, porous silica having an average particle diameter of notmore than 5 mum can be incorporated in the coated film, as required, whereby sharpness of printed images can be enhanced. The amount of porous silica incorporated into the coated film and the thickness of the film are suitably selected to maintain a ray transmittance of at least 60%. With a sheet thus obtained, sharp images can be projected on a screen by an OHP.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a transparent sheet for an overhead projector (OHP), and particularly to a transparent sheet for use in an overhead projector (OHP), and particularly for transmitting dot impact images, characters, figures, graphs, etc. recorded on the transparent sheet. O'HP
It has become popular to project and display images on a screen to facilitate classes, research presentations, conferences, etc.

Conventionally, 0) IP manuscripts have been created by handwriting with an OHP marking machine made of tracing paper or plastic transparent film such as acetate, acrylic, polyester, etc., or by copying with an electrostatic copying machine. .

On the other hand, in recent years, so-called 0Afi devices such as personal computers and word processors have become widespread, and the data processed by these OA devices is directly printed on 0R (P sheet) using printers as printing devices. It is strongly desired to form a manuscript.

However, since printers were originally developed for the purpose of printing on paper, they are not suitable for printing on OHP panels made of plastic film. The dot impact printer, which is the most widely used printer due to its excellent performance, is no exception and has no suitability for printing on OHP sheets.

(Problems to be Solved by the Invention) In dot impact printers, the ink retained on the ink ribbon or ink-impregnated platen must be non-drying in order to maintain good printing performance over a long period of time. A non-drying vehicle such as a fatty acid such as phthalic acid or nisster phosphate is mixed with an oil-based dye or pigment as a coloring material.

This type of ink is a penetrating drying type in which the ink itself does not dry, but is absorbed into the printing paper to give an appearance of dryness, so it is not suitable for media such as OHP sheets that have no ink absorbency. Practical printing could not be performed because the ink could not be dried.

In view of the above-mentioned current situation, the present invention provides a dot-impact printer using non-drying ink that has good printability and excellent light transmittance.
This was created as a result of intensive research to develop the P-sheet.

(Means for Solving the Problems) That is, the present invention provides a thermoplastic polyurethane coating of 2 μm on the surface of a transparent substrate, maintaining a light transmittance of 60% or more and containing porous silica with an average particle size of 5 μm or less as necessary. This is a transparent sort for dot impact recording characterized by the above-mentioned wave overlapping.

(Function) The thermoplastic polyurethane coating coated on the surface of the transparent substrate with a thickness of 2μ or more has appropriate ink absorbency for dot impact recording ink, so printing with good ink penetration and drying is achieved. be able to.

Furthermore, if necessary, it is possible to improve the print clarity by incorporating porous glue with an average particle size of 5μ or less into the thermoplastic polyurethane coating, and moreover, by incorporating porous glue into the coating. By appropriately selecting the amount and film thickness and keeping the light transmittance at 60% or more, it is possible to project a clear image on the OHP screen.

(Example) Example 1 Thermoplastic polyurethane solution (Sunbren LQ-3510
A thermoplastic polyurethane film having a thickness of 10 μm was formed on a polyester film having a thickness of 50 μm using a polyester film (SANYO KASEI).

After sufficiently drying the coating, printing was performed using a dot impact printer. The ink dried quickly and good printing was performed. Also, when the surface printing sheet was projected onto a screen using an OHP, the image was clear. there were.

Example 2 Thermoplastic polyurethane solution (Sunbren LQ-3510
, Sanyo Chemical) and porous glue (Syroid 978, Fuji Davison) with an average particle size of 4μ to 3vt% of the resin content.
Using the blended resin, a thermoplastic polyurethane film containing a fine warp powder having a thickness of 5 μm was formed on a polyester film having a thickness of 50 μm.

After sufficiently drying the film, printing was performed using a dot impact printer.The results showed that the ink drying properties were good and the print clarity was also excellent, and when this printing sheet was projected on an OHP screen, it was clear. A great image was obtained.

Example 3 Thermoplastic polyurethane solution (Sunbren LQ-3510
, Sanyo Chemical), porous silica with an average particle size of 4μ, (Syroid 978, Fuji Davison Chemical) to the resin content
A film having a thickness of 5 μm was formed on an acrylic film having a thickness of 50 μm using a mixture containing 5 wt % of the composition.

After sufficiently drying the coating, printing was performed using a dot impact printer. As a result, the printing was clear and had good ink drying properties, and the image projected on the screen by OHP was clear.

In order to improve the printability of OHP sheets with dot impact printers, it is necessary to impart penetrating drying properties to the sorting surface for ink using a non-drying vehicle used in dot impact printers.

For this purpose, first, apply a resin solution as shown in Table 1 below to a thickness of 5
0μ polyester film (Lumira T-60, Toshi)
It was coated on top and sufficiently dried to form various resin films with a film thickness of 6 μm.

Table 1 In addition, the blending amount is shown in parts by weight.

Next, printing was performed using a dot impact printer on the sheets having various resin coatings formed on the surfaces shown in Table 1, and the results of examining the printing properties are shown in Table 2.

Table 2 Ink 1 Oleic acid 85wt% Ink 3 DOP 85wt% Oil black 15wt% Ink drying property O large Δ medium × small side As is clear from Table 2, ink permeability depends on the type of resin film formed on the surface of the film. Differences in printability were observed due to the difference in printing properties.

Among these, thermoplastic polyurethane had appropriate permeability to ink of any type of vehicle and showed excellent printability.

In the case of sheets coated with other resin films, the ink permeability was insufficient and the drying properties of the ink were poor, and even with polyurethane, the isocyanate crosslinked type did not show good printing performance.

Furthermore, we investigated additives to be added to the thermoplastic polyurethane coating in order to improve the clarity of printing.

If additives are added to the coating formed on the surface of the transparent film, the light transmittance of the film may decrease and the clarity of the image projected on the OHP screen may decrease, so the light transmittance should be reduced by 40%. As mentioned above, it is necessary to maintain it preferably at 60% or more.

Taking into account the above points, additives for thermoplastic polyurethane include inorganic pigments such as silica, calcium carbonate, and alumina, starch, polyethylene, polypropylene,
We investigated organic resin fine powder such as guanamine and found that it is preferable to use porous silica fine powder.

The results of examining the particle size and amount of porous silica fine powder blended into thermoplastic polyurethane are shown in Table 3 below.
As shown.

Table 3 Very good Good Poor The conditions for preparing the sample are as follows.

Thermoplastic polyurethane solution Sunbren L Q-351
0 Porous silica Thyroid 978 Average particle size 4 Thyroid 162 Average particle size 9 Film thickness 6μ Base material Polyester film (50μ) First,
According to the results of examining the particle size of porous silica fine powder, if a powder with a large average particle size is blended, the coating surface will become rough and the printing clarity will decrease, so this should be 5μ or less. It is preferable to set it as approximately.

Next, as the amount increases, the print clarity improves, but the light transmittance decreases, so it is necessary to keep the light transmittance at about 60%, and the average particle size is about 5μ or less. In this case, it is preferable that the amount is about 5vt% or less based on the resin content.

Finally, we examined the relationship between the thickness and ink drying properties, print clarity, clarity of OHP projected images, etc. when coated with a thermoplastic polyurethane film containing porous silica, and the results are shown in Table 4 below. show.

Table 4 ◎Very good ○Good Slightly poor X Poor The preparation conditions for the above samples are as follows.

Base material polyester film (50μ) Thermoplastic polyurethane sunburen LQ-3510 Porous Nlica Thyroid 978 (4μ) 3wt% According to the results of the study, the thinner the film, the poorer the ink drying performance and print clarity; As the thickness increases, the light transmittance decreases, resulting in a decrease in the clarity of the OHP projected image.

The acceptable film thickness cannot be determined unconditionally, as it is affected by the particle size and amount of porous silica blended into the thermoplastic polyurethane, but in order to improve printing performance, at least 2
μ or more is necessary, and in order to maintain the clarity of the projected image by OHP, it is not preferable to exceed 10 μ.

To summarize the results of the various studies described above, coating a transparent base film with a thermoplastic polyurethane film imparts penetrating drying properties to ink for dot impact printers, improves printability, and improves printability as needed. By blending fine porous silica powder with an average particle diameter of about 5 μm or less in the coating and coating it with a light transmittance of 2 μm or more while maintaining a light transmittance of 60% or more, the ink drying properties and print clarity are excellent, and the clarity of the projected image is maintained. A sheet is formed.

It should be noted that the transparent film that serves as the base material for coating the surface with the thermoplastic polyurethane coating described above may be of any type as long as it can withstand being hit by a printing wire during printing with a dot impact printer. Examples include plastic films such as polyester, acetate, acrylic, and polycarbonate.

Further, the appropriate thickness of the plastic film is generally about 25 to 100 mm.

(Effects) The present invention has the above-mentioned configuration and operation, and its effects are that a document can be created directly by dot impact printing using OA equipment that has recently become popular, and a clear image can be printed on the screen by OHP. The objective is to provide a sheet on which images can be projected.

Patent applicant: Kimoto Co., Ltd. Janome Sewing Machine Industry Co., Ltd.

Claims (1)

[Claims] A transparent sheet for dot impact recording, characterized in that the surface of a transparent substrate is coated with a thermoplastic polyurethane film of 2 μm or more, maintaining a light transmittance of 60% or more and containing porous silica with an average particle size of 5 μm or less, if necessary.