JPS60234879A - Inkjet recording sheet - Google Patents

Abstract

PURPOSE:To obtain an image with a clear ink dot by providing a coated film having polyvinyl alcohol mixed with an appropriate amount of a specified crosslinking agent to effectively inhibit the diffusion of ink dots attached to a film coated surface with a higher coated film strength while preventing ink running in the image. CONSTITUTION:A coated film which contains polyvinyl alcohol with the saponification rate of 50-90mol% and a copolymer of 2-4C olefine or stylene and maleic anhydride or an ammonium salt or a sodium salt thereof as crosslinking agent is provided on a film sheet. Unless the saponification rate meet the above- mentioned range, polyvinyl alcohol never allow a desired ink absorbability to be delivered due to the deterioration in the hydrophilic property. Any olefine used as crosslinking agent in which the number of carbon atoms is not in the above- mentioned range can not accomplish the fusion and fixation or glycols as one element of ink components as expected even when the polyvinyl alcohol is mixed with the copolymer produced using maleic anhydride. Thus, it is made impossible to promote dry fixation of ink leading to a greater attaching strength of ink after being dried.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording sheet, and more specifically, an inkjet recording sheet that is colorless and transparent, has good ink receptivity to water-based inks, and is capable of multicolor recording with high printing density and resolution. Regarding sheets for use.

As is well known, recording by the inkjet method is (-
? ) Generates extremely little noise, (b) Recording speed is fast, (c) Colorization is easily achieved, and (d) The quality of the printed image formed by recording is comparable to that of a color photographic image. It has features that are not found in equal location recording methods.

For this reason, the inkjet recording method has been widely used in a wide range of fields for the purpose of producing images as an information processing means, including data processing in electronic computers, by taking advantage of the above-mentioned features. However, although this inkjet method is advantageous because the overall cost required to create some of it is cheaper than other color printing methods, since the main use of this method was originally for printers, This table is rather uneconomical when used for copying such as zeography, which requires a large number of copies. This is because using inkjet recorded images for multiple communications at the same time naturally requires copying a huge number of images.
This is because it is not only inconvenient to create, but also increases costs.

However, on the other hand, there is a need to not only use the inkjet recording method to simply record and preserve images, but also to increase the value of recorded images by rationally and economically using them for information transmission.

However, as a conventional information transmission means, a video system is generally used and is well known. Above all, overhead projector systems (hereinafter referred to as projector systems) have come to be adopted as an auxiliary means that allows anyone to easily transmit necessary information regardless of time and period. (hereinafter referred to as a projector). There are known projectors of a transmission type that are excellent in terms of ease of viewing, ease of use, economy, and safety.

However, since this projector enlarges and projects the image onto the screen using light beams that enter the image from the back side, the image sheet for the projector is created by using a marking ben or color adhesive film on the surface of the transparent film sheet. This is usually done mostly manually using tools such as tools.

Although auxiliary imaging equipment has been developed with the aim of streamlining this manual work and is already on the market, manuscript writing still has to be done manually. Of course, this requires time, skill, and technology, and is always accompanied by troublesome work in creating image sheets.

For this reason, creating image sheets manually using marking pens, color adhesive film, etc. is a natural process, as the images are usually detailed and varied in shape and color tone. There are limitations, so it is inevitable that the image will be roughly expressed to some extent.

For this reason, the present inventor believes that if an inkjet recorded image can be rationally incorporated into the transmission projector system and visualized, the image can be made more precise and transmitted by rapid information means. Moreover, not only can the content of the communication be complete information that complements the above-mentioned disadvantages of both methods, but it can be transmitted to many people at the same time. We have reached the conclusion that it is possible to consistently transmit an image sheet with higher quality, richer color tone, and much more fineness than conventionally known manual image sheets for projector systems.

As a result of conducting research on this point, we found that when water-based ink is injected onto the surface of a commercially available projector film sheet using an inkjet method to perform the desired recording, it adheres to the surface of the sheet because the sheet is hydrophobic. It has been known that the ink dots are not absorbed, but come close to each other due to the action of surface tension, and come into contact and fuse, resulting in so-called ink running, making it impossible to obtain a clear image. In this case, the ink component generally contains glycols as one of its elements, but since these are usually over 9,200°C, the ink dots remain undried even if left to dry for a long time. Of course, there are cases.

For this reason, film sheets for projectors (commercially available products) cannot be used for recording using the inkjet method, so in order to perform the desired recording on the surface of the transparent film sheet using the inkjet method, it is necessary to improve the image quality and workability. A special transparent film sheet is immediately required,
It is important to have the following characteristics.

(1) It absorbs a certain amount of ink and has drying properties, and with a little effort, it is possible to obtain the desired record on the film sheet surface. (2) It is possible to create clear images using ink dots.
(3) Enlarged projection using the transmission method allows sufficient color density to appear on the screen; (4) Recorded images have good storage stability and the image surface is free from friction. (5) There is no stickiness on the surface of the film sheet, and there is no problem in handling the sheet. Herein, the present inventor has made a method to satisfy the above conditions at the same time. In order to make a hydrophobic transparent film sheet, which has conventionally been used as a support, non-hydrophobic, ink is absorbed on the surface of the sheet,
Also, from the viewpoint that it is necessary to provide a hydrophilic coating film that enables drying, polyvinyl alcohol having a specific degree of saponification (described later) is applied to one or both sides of the hydrophobic transparent film sheet. It was discovered that the film can be made to have a highly hydrophilic surface while being transparent, and to have an insufficient absorption capacity. However, in this case, simply applying polyvinyl alcohol having such a degree of saponification to the surface of the film sheet will not work.
At the same time, it was confirmed that the ink dots adhering to the sheet surface diffused over time and fused upon contact, causing ink running and making it difficult to obtain a clear image.

Based on the above findings, the inventors of the present invention continued to study further and found that by mixing an appropriate amount of a specific crosslinking agent (described later) with the polyvinyl alcohol, the strength of the coating film can be improved and the ink dots attached to the coating surface can be reduced. effectively suppress the spread,
In addition, the inventors have experimentally discovered that it is possible to prevent ink from running and to obtain images with clear ink dots, thereby completing the present invention.

That is, the present invention provides polyvinyl alcohol with a degree of saponification of 50 to 90 mol % and a copolymer of olefin or styrene and maleic anhydride having 2 to 4 carbon atoms as a crosslinking agent, or It consists of providing a coating film containing the ammonium salt or sodium salt.

The polyvinyl alcohol used here has a saponification degree of 50.
It is important that the saponification degree is ~90 mol χ, and the degree of saponification is 50
less than mol%, or its degree of saponification is 90 mol%
In this case, the polyvinyl alcohol becomes unsuitable for practical use because it cannot exhibit the desired ink absorption ability even if applied to the hydrophobic film sheet surface due to deterioration in hydrophilicity (Examples (including Comparative Examples)). )reference).

Also, olefins used as crosslinking agents (see examples)
It is important that it has 2 to 4 carbon atoms, and if it deviates from this range, a copolymer of this and maleic anhydride (or its ammonium salt or sodium salt may be used) is used. Even if it is mixed with polyvinyl alcohol, it is not suitable because it fuses and fixes glycols, which are one of the ink components, and promotes ink absorption and dry fixation, so that it cannot be expected to improve the ink's hardness after drying. In the above, styrene can also be used instead of the olefins having 2 to 4 carbon atoms.

Therefore, the amount of the crosslinking agent (specific olefin or copolymer of styrene and maleic anhydride, etc.) added to polyvinyl alcohol is 5 to 50% by weight, preferably 10 to 300% by weight.
~30% by weight If the amount added is less than 5% by weight, the desired effect described above cannot be obtained, and if the amount added is more than 50% by weight, even if the desired effect is obtained, the use of the upper limit (50% by weight) The upper limit was set at 50% by weight, since this would simply increase the cost.

In the present invention having such a configuration, it is not yet theoretically clear that the desired effect can be obtained, and it must depend on experimental results, but according to the experiments of the present inventor, When a coating liquid mainly composed of polyvinyl alcohol with a degree of saponification of 50 to 90 mol% is applied to the surface of a hydrophobic transparent film sheet, the coating film covers the surface of the hydrophobic sheet.
When a water-based ink is applied to this surface, the ink is effectively absorbed into the coating, while the crosslinking agent mixed with polyvinyl alcohol (an olefin having 2 to 4 carbon atoms or a combination of styrene and maleic anhydride) Polymers, etc.) have the property of being water-soluble and soluble in glycols, which melts and fixes the glycols, which are one of the ink components, and promotes ink absorption and dry fixation, and the ink after drying. It is thought that this increases the adhesion strength.

However, in the above, a coating liquid consisting of polyvinyl alcohol (saponification degree 50 to 90 mol%) and the crosslinking agent can be easily obtained by mixing an aqueous solution of both of them by a conventional method. Water-soluble solvents such as methanol, ethanol, isopropyl alcohol, methyl cellosolve, and ethyl acetate, or surfactants, modified sodium polyacrylate, etc. are mixed and used to improve coating properties and the quality and characteristics of the resulting recording sheets. You can also.

The coating liquid thus obtained is applied to the surface of the film sheet, and the coating amount is preferably 2 (1/G (same as 2 or less in terms of solid content) or more on one side) or more.

If this coating amount is less than 2g/7Il, in printing with a large amount of ink, such as two-color mixed printing or solid mixed printing,
The ink absorption and fixing effect in the printed area is poor, and a large amount of unfixed ink remains on the surface layer, causing contact fusion during the drying process and making it impossible to obtain a clear image, which is unsuitable.

The film sheet (support) is a transparent sheet made of polyester, polyethylene, polyvinyl chloride, polyvinyl alcohol, etc., and has a thickness of about 30 to 100 μm.
It is preferable that the surface has been subjected to corona treatment. To apply the coating liquid to the film sheet, use a known air knife coater, bar coater, doctor coater, or a combination thereof, and apply it once or several times to one or both sides of the sheet using a conventional method, and then dry. . In this way, a desired inkjet recording sheet is obtained.

As explained above, the present invention includes polyvinyl alcohol with a saponification degree of 50 to 90 mol%, an olefin or styrene having 2 to 4 carbon atoms as a crosslinking agent, and maleic anhydride on one or both sides of a film sheet. Since the coating film containing the copolymer or its ammonium salt or sodium salt is provided, the following effects can be exhibited, and the practical benefits of this are significant.

(1) An inkjet recording sheet for multicolor recording that is transparent and capable of fixing water-based ink and has high print density and resolution can be obtained, making it possible to use it in a transmission projector system. In addition to increasing its value as an information means of a recording system, the burden of creating the sheet for the projector can be greatly reduced.

(2) Furthermore, since images recorded by the inkjet recording method can be visualized by rationally incorporating them into the projector system, it is possible to quickly transmit information to a large number of people.

(3) Especially when using fine ink dots with the inkjet method, it is possible to increase the image value and consistently convey images with rich tones that are far more precise and sophisticated than conventional image sheets for project systems. can.

The present invention will be explained in more detail below with reference to Examples.

Example 1 Saponification degree 86.5-89 mol% (polymerization degree 1000-1
500) polyvinyl alcohol (GM-14 (trade name): (manufactured by Nippon Gosei Kagaku Co., Ltd.) 7% by weight Ammonium salt of an olefin with 4 carbon atoms and maleic anhydride copolymer (isopane (trade name): Clareisoprene Chemical An aqueous solution containing 2% by weight of cross-linking agent) and 30% by weight of methanol was prepared by a conventional method, and coated on one side of a polyester film sheet (thickness: 30 μm) using a bar coater, after drying, the amount of coating was 4 g/ A desired inkjet recording sheet was obtained by coating the inkjet recording sheet.

Example 2 Saponification r! 171-75 mol% (degree of polymerization 1000-1
500) polyvinyl alcohol (P-08 (trade name) manufactured by Nippon Gosei Kagaku Co., Ltd.) 6% by weight Ammonium salt of an olefin with 4 carbon atoms and maleic anhydride copolymer (isopan-104 (trade name): Kuraray An aqueous solution containing 1.5% by weight (crosslinking agent manufactured by Isoprene Chemical Co., Ltd.) and 20% by weight of ethanol was prepared by a conventional method, and this was applied to a polyester film sheet (thickness 50 μm) using a bar coater after drying. The inkjet recording sheet was coated twice with an amount of 8 g/-rIL on one side and once on the other side with an amount of 4 g/in.

Example 3 Saponification degree 71-75 mol% (polymerization degree 1000-150
0) polyvinyl alcohol (KP-08 (product name):
(manufactured by Nippon Gosei Kagaku Co., Ltd.) 6m1% Ammonium salt of styrene-maleic acid monoester copolymer (0 to S-Discoat N-14 (trade name): crosslinking agent manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5% by weight An aqueous solution containing 20% by weight of ethanol was prepared by a conventional method, and this was applied twice to a polyester film sheet (thickness: 80μ) using a bar coater so that the coating amount after drying was 80/m. A desired inkjet recording sheet was obtained.

Comparative Example 1 An inkjet recording sheet was obtained in the same manner as in Example 2 except that the crosslinking agent (olefin having 4 carbon atoms and maleic anhydride copolymer) was not used.

Comparative Example 2 In Example 1, instead of 7% by weight of polyvinyl alcohol with a saponification degree of 86.5 to 89 mol%, saponification degree of 98 to 99 was used.
Mol% (degree of polymerization 1750) polyvinyl alcohol/L
An inkjet recording sheet was obtained in the same manner as in Example 1, except that 4% by weight of PVA-117 (trade name, manufactured by Kuraray Co., Ltd.) was used and an aqueous solution containing no crosslinking agent and methanol was applied.

Comparative Example 3 Saponification degree of 98 to 99 was used instead of polyvinyl alcohol 7% by weight having a saponification degree of 86.5 to 89 mol% in Example 1.
Mol% (degree of polymerization 1750) of polyvinyl alcohol (
An inkjet recording sheet was obtained in the same manner as in Example 1 except that 6% by weight of Pv^-117) was used.

Comparative Example 4 In Example 1, the coating amount of the coating liquid was changed from 4 (1/rd to 1
An inkjet recording sheet was obtained in the same manner as in Example 1 except that the amount was reduced to 5 (+/ml).

The inkjet recording sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were tested to determine the transparency of the film sheet and the print image quality by inkjet recording using an inkjet image printer IQ-0700 (manufactured by Sharp Corporation). We conducted an evaluation. However, all evaluations were based on visual perception based on the criteria described below.

Evaluation needs (1) Transparency ○: There is no turbidity in the film sheet.

Δ: The same receipt is slightly cloudy.

X: Indicates that the sheet has strong turbidity.

(2) Ink drying property' ◎: Text side printing part dries within 3 minutes.

O: Dry in the same printing section for 3 to 15 minutes.

Δ: Dry in the same printing section for 15 to 30 minutes.

X: Indicates that the same printing section requires 30 minutes or more.

(3) Ink adhesion strength (ink film strength) However, this evaluation was based on scratching with the fingernails of the same person.

○: Ink dye does not come off.

△: The same dye crumbles.

×: Indicates that the same dye comes off.

(4) Ink flow When magnifying and projecting with a projector by the image appearing on the screen I judged it.

O: There is almost no ink running in the solid mixed color printing area.

Δ: There is slight ink running on the same side of the printing section.

×: Indicates that there is a lot of ink running in the same printing section.

(5) Color density When magnifying and projecting with a projector by the image appearing on the screen I judged it.

○: Solid mixed color printing area is good.

△: The ipsilateral printing area is slightly lighter.

×: Indicates that the same printing part is quite light.

The above judgment results are summarized in the following table.

(Table) As is clear from the above table, Examples 1 to 3 are known to have shown excellent results in terms of transparency, ink drying performance, ink adhesion strength, ink running, and color density, and are suitable for use in projector systems. It was confirmed that a special and excellent usable inkjet recording sheet could be obtained.

Claims (1)

[Claims] Saponification degree 50-9 on one or both sides of the film sheet
It is characterized by providing a coating film containing 0 mol% polyvinyl alcohol and a copolymer of olefin having 2 to 4 carbon atoms or styrene and maleic anhydride, or an ammonium salt or sodium salt thereof as a crosslinking agent. Inkjet recording sheet.