JPH0329596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a recording sheet suitable for inkjet printers, and more specifically, it has excellent translucency and can be used to transfer recorded images to an overhead projector (hereinafter referred to as OHP). ), etc., and relates to a recording sheet suitable for observation through transmission with an optical instrument such as.

(Conventional technology) Inkjet printers are known for their sharpness of recording,
It has become popular in recent years due to its excellent features such as quietness and easy colorization.

Inkjet printers use ink that does not dry easily in order to prevent clogging of jet nozzles, and the components of this ink generally include binders, dyes, solvents, additives, etc. dissolved in water.

Therefore, when printing and recording with an inkjet printer, the recording sheet must have water absorption properties, and usually paper specially designed to provide sufficient ink absorption performance is used.

On the other hand, as inkjet printers become more color-oriented, there is an increasing demand for recording on transparent recording materials and using them as OHP recording sheets.
However, transparent recording sheets are usually made of plastic film, which is hydrophobic and does not absorb any ink for inkjet printers, so ink recorded directly on it does not dry easily and cannot be easily touched with a finger. If they are rubbed or overlapped, the recording area will get dirty and become unusable.

As a countermeasure for this, in order to improve the receptivity to water-based inks, that is, the absorption of ink, we have developed inks that are mainly made of polyvinyl alcohol, in addition to glycerin, lithium chloride, starch, gelatin, hydroxyethyl cellulose, and carboxymethyl cellulose. It has been proposed to provide an aqueous ink-receiving layer containing a wettable material on a light-transmitting substrate, but even if the conventional ink-receiving layer satisfies the ink absorbency, The surface of these sheets is sticky and blocking occurs when a number of sheets are laminated, and depending on the material, the translucency may be reduced.

(Problems to be Solved by the Invention) In view of the above circumstances, an inkjet that maintains translucency, has sufficient ink absorption, and has excellent clarity of recorded images when used for OHP. The purpose is to provide a record sheet for recording purposes.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and consists of two layers in which polyvinylpyrrolidone and polyvinyl butyral are combined as an ink-receiving layer and their blending ratios are different. More specifically, as shown in the figure, a first ink receiving layer 2 consisting of 80 to 90% by weight of polyvinylpyrrolidone and 1 to 20% by weight of polyvinyl butyral is formed on the surface of a transparent substrate 1. 60-80% by weight of polyvinylpyrrolidone and 20-40% of polyvinyl butyral on the outside.
% by weight of the second ink receiving layer 3.

The light-transmitting substrate 1 constituting the recording sheet of the present invention may be a plastic having excellent light-transmitting properties, such as polyethylene terephthalate, diacetate, triacetate, acrylic polymer, cellophane, celluloid, polyvinyl chloride, polycarbonate, or polyimide. A film or plate made of, a glass plate, etc. can be used, depending on various conditions such as the recording purpose, the use of the recorded image, and whether good adhesion with the ink-receiving layer provided on the film can be obtained. The material is appropriately selected from among the materials.

Next, polyvinylpyrrolidone used in the ink-receiving layer has good ink absorbency and has the function of preserving water-based ink for inkjet, but its water resistance and fixing properties are poor and there are concerns. Further, although polyvinyl butyral has good water resistance and fixing properties, and there is little bleeding of recorded images, its ink absorbency is not very good.

The present invention focuses on this point, and as a result of various studies,
The problems of the prior art described above are solved by providing an ink-receiving layer with a two-layer structure in which the blending ratio of polyvinylpyrrolidone and polyvinyl butyral is changed.

That is, a combination of 80 to 99% by weight of polyvinylpyrrolidone and 1 to 20% by weight of polyvinyl butyral is blended in the first ink-receiving layer 2 on the side in contact with the transparent substrate, and the second ink-receiving layer on the surface thereof layer 3
60 to 80% by weight of polyvinylpyrrolidone and 20 to 40% by weight of polyvinyl butyral are combined to provide sufficient ink absorption on the inner layer side and prevent the absorbed ink from bleeding on the outer layer side. It is designed to make it possible to demonstrate.

Here, the content of polyvinylpyrrolidone in the first ink receiving layer 2 is set to 80 to 99% by weight.
If it is less than 80% by weight, ink absorption will be insufficient and it will be difficult to obtain a clear image. If it exceeds 99% by weight, the amount of polyvinyl butyral will be too small, resulting in insufficient water resistance and fixing properties, and the recorded image will be difficult to obtain. This is to cause bleeding. Furthermore, the content of polyvinylpyrrolidone in the second ink receiving layer 3 is set to 60 to 80% by weight in order to transfer ink absorption from the outside to the inside and achieve sufficient ink absorption. This is to ensure water resistance and fixability by increasing the amount of polyvinyl butyral in the receptor layer 2, and to prevent bleeding of recorded images.

In addition, in the ink receiving layer of the present invention, regardless of whether it is the first or second receiving layer, in order to improve water resistance and prevent ink from bleeding for inkjet printers,
It is preferable to incorporate a water resistant agent such as melamine formaldehyde resin, urea formaldehyde resin, glyoxal, and zirconium ammonium carbonate.

In addition, in order to further enhance the recording properties of the recording sheet and improve the blocking resistance, additives such as silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, and sulfuric acid may be added to an extent that does not impair the transparency of the recording sheet. Fillers such as barium, aluminum silicate, synthetic zeolite, alumina, zinc oxide, lithopone, satin white, and the like may be dispersed in the ink-receiving layer.

Furthermore, various additives such as dispersants, fluorescent dyes, PH regulators, antifoaming agents, lubricants, preservatives, etc. may be mixed in to further improve the productivity, recording characteristics, or storage stability of the recording sheet. You can also do it. These additives are also added to an extent that does not impair the transparency of the recording sheet.

To provide an ink-receiving layer on a base material, a coating solution prepared by dissolving or dispersing the material for forming the ink-receiving layer in an appropriate solvent is applied by roll coating, blade coating, spray coating, or air knife coating. The ink-receiving layer may be coated by a method such as the ink-receiving layer, a rod coating method, etc., and then dried, or a uniform mixture of the materials capable of forming the ink-receiving layer may be hot-coated on the light-transmitting substrate. A method of forming an ink-receiving layer by laminating layers by a melt coating method, a laminate coating method, etc. can be applied.

The thickness of the ink-receiving layer provided in the recording sheet of the present invention is preferably about 5 to 10 μm for the first ink-receiving layer, and 5 μm or less for the second ink-receiving layer.
If the thickness of the ink-receiving layer is too thick, the light transmittance (in-line transmittance) will decrease, and if it is too thin, the ink absorbency will decrease, which is not preferable.

Furthermore, since the recording sheet of the present invention has excellent translucency, its uses are not limited to OHP only.
Those used for projection observation of recorded images onto screens etc. using optical equipment other than OHP such as slides, color separation plates when creating positive plates for color printing, CMF used for color displays such as liquid crystals, etc.
It is also applicable to uses other than conventional surface image observation.

Furthermore, even for OHP, recording methods other than inkjet printers, such as electrophotography, may be used.
PPC plate making, handwriting, etc. are also included in the application of the present invention.

(Examples) The present invention will be described in detail below with reference to Examples. Note that parts in the text indicate parts by weight.

Example 1 Coating liquids for the first and second ink-receiving layers having the following compositions were coated on one side of a translucent base material made of a polyethylene terephthalate film having a thickness of 100 μm.

Coating liquid for the first ink-receiving layer Polyvinylpyrrolidone 10% solution (manufactured by Gokyo Sangyo Co., Ltd., K-90) ...90 parts Polyvinyl butyral 10% solution (manufactured by Sekisui Chemical Co., Ltd., Esletsu BM-
5) ...10 parts n-butanol ...40 parts Coating liquid for second ink-receiving layer Polyvinylpyrrolidone 10% solution (manufactured by Gokyo Sangyo Co., Ltd., K-90) ...70 parts polyvinyl butyral 10% solution (manufactured by Sekisui Chemical Co., Ltd.) , ESLETSUKU BM-
5) ...30 parts n-butanol ...40 parts When coating, the film thickness after drying the above coating liquid is
The recording sheets of the present invention were obtained by sequentially coating with a blade coater to give a thickness of 5 μm and 3 μm, followed by heat treatment at 80° C. for 20 minutes and drying.

The above recording sheet was applied to an on-demand inkjet recording device (inkjet color image printer model 10-0700, manufactured by Sharp Corporation), and color recording was performed using four types of ink: horizontal, red, blue, and black. Summer.

As a result, even after several minutes of recording, the ink did not adhere to the finger, confirming that the ink-receiving layer of the recording sheet of the present invention had excellent ink-absorbing properties.

Next, the color-recorded recording sheet of the present invention was set in a commercially available OHP device (Ricoh OHP Wide, manufactured by Ricoh Co., Ltd.), and a screen image was projected, and a clear color image was projected.

Furthermore, when 100 recording sheets of the present invention were stacked, a load of 600 g was placed on top of the stack, and the stack was left in an atmosphere of 30° C. and 95% RH for 24 hours, no blocking was observed between the sheets.

Example 2 A recording sheet of the present invention was obtained in the same manner as in Example 1, except that a coating liquid having the following composition was used as the second ink-receiving layer coating liquid.

Polyvinylpyrrolidone 10% solution (manufactured by Gokyo Sangyo Co., Ltd., K-90) ...70 parts Polyvinyl butyral 10% solution (manufactured by Sekisui Chemical Co., Ltd., Esletsu BM-
5)...30 parts silica (manufactured by Tokuyama Soda Co., Ltd., Fine Seal X-
37) ...0.7 parts n-butanol ...40 parts When the above recording sheet was evaluated in the same manner as in Example 1, it was found that the ink absorbency, OHP
It was recognized that the projected image had excellent clarity. It was also confirmed that there was no problem with blocking and that it could withstand practical use.

Comparative Example 1 Using only the second ink-receiving layer coating solution in Example 1, the film was coated to a dry film thickness of 8 μm, heat-treated at 80°C for 20 minutes, and dried to create a comparative record. Got a sheet. When this recording sheet was subjected to ink jet recording in the same manner as in Example 1, the ink absorption was poor and a clear recorded image could not be obtained.

Comparative Example 2 A comparative recording sheet was obtained in the same manner as in Comparative Example 1 using only the first ink-receiving layer coating liquid in Example 1. Example 1
When similar inkjet recording was performed, although the ink absorption was excellent, the water resistance and fixing properties were poor, and the ink could not be used in long-term practical use.

(Effects of the Invention) Since the present invention has the above-described configuration, there is no ink bleeding in images recorded by an inkjet printer, and the ink fixation properties are good, so even if you touch the recorded area with your finger, the ink does not stick to your finger. It does not stick to the recording sheet of the present invention, and has good water resistance, so even if it is touched with wet hands or water, tea, etc. is spilled on the recording sheet according to the present invention, the recorded image will not become unclear.
There is no risk of it coming off.

[Brief explanation of drawings]

The figure is a sectional view showing an example of the recording sheet of the present invention. 1... Transparent base material, 2... First ink receiving layer, 3... Second ink receiving layer.

Claims (1)

[Claims] 1 Polyvinylpyrrolidone on one side of the translucent base material
80-99% by weight of polyvinyl butyral, 1-20% by weight of polyvinyl butyral; and 60-80% by weight of polyvinylpyrrolidone, 20% by weight of polyvinyl butyral.
A recording sheet characterized in that a second ink-receiving layer consisting of ~40% by weight is sequentially provided.