JPS62242578A - Transparent sheet for ink jet recording - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is a transparent sheet for an inkjet printer using water-based ink,
Jbr: nφiiI鵞soll-纺弔HANO・7KA25〒...Relates to inkjet recording sheets for transparent image sheets used in overhead projectors etc. created by nod printers, and adheres to the sheet surface. The ink absorption speed and absorption capacity are high, it dries virtually in a short time, the spread and smearing of ink dots is small, the color of the ink is vivid, and the dot shape is circular and can produce images and prints with sharp edges. The present invention relates to a transparent sheet for inkjet printers that can be provided.

[Conventional technology]

The technology of inkjet color printers that create color images at high speed using an inkjet recording method is progressing, and this technology can be used to create color images on transparent film and use them with overhead projectors, etc. It has been proposed to use it as a trans-ear range. Therefore, it has been proposed to provide a transparent water-absorbing resin layer on a transparent film base material.

However, there is a problem in these proposals that quick-drying properties and water resistance of images are not compatible with each other. Water absorption and quick-drying properties can be improved by increasing the amount of coating or increasing the number of hydrophilic groups in the polymer, but the problem of water resistance can be improved by improving water-based ink absorption and resolution. Improvement has been difficult since it is necessary to increase the number of hydrophilic groups as much as possible.

[Problem that the invention seeks to solve]

The present invention is an inkjet recording method using water-based ink, which has a high absorption speed and absorption capacity for ink adhering to the surface of a transparent recording sheet, has a small spread of ink dots and small K smudges, has a bright ink color, and has an ink dot shape. An inkjet recording sheet capable of giving an image with a circular shape and sharp edges, thus making it possible to print high-resolution characters and images at high speed, and furthermore having good transparency, the above-mentioned prior art An object of the present invention is to provide an inkjet recording sheet used as a transbearing range for an overhead projector that can eliminate the drawbacks of the above.

[Means for solving problems]

In order to solve the above-mentioned problems of the prior art, the present inventors have made various studies and have discovered a polyvinyl alcohol copolymer having a cationic group, a polymer that can be crosslinked by radiation such as ultraviolet rays, By laminating and crosslinking a coating layer containing preferably a polyvinyl alcohol copolymer as a main component on a transparent sheet base material, it is possible to rapidly dry with an inkjet printer and to produce clear and transparent images. It has been found that an excellent inkjet recording sheet can be obtained that allows the creation of a trans-irradiation range.

The present invention provides an inkjet recording sheet in which a coating material containing a polyvinyl alcohol copolymer containing a cationic group and a polymer containing an ultraviolet crosslinkable group as main components is coated on a transparent sheet-like support. 1. A sheet for inkjet printers, characterized in that it has a coating layer cross-linked with ultraviolet rays.

It is.

The cationic polymer used as one component of the coating layer of the present invention consists of a polyvinyl alcohol copolymer. As the polyvinyl alcohol copolymer having a cationic group, for example, a polyvinyl alcohol copolymer containing 5 to 30% by weight of an acrylic monomer containing a quaternary ammonium salt or a tertiary amine as a functional group is suitable. In particular, monomers with tertiary amine groups as comonomers,
Monomers with grade ammonium bases show excellent effects.

Polymers with ultraviolet crosslinkable groups used as other components of the coating layer include polyvinyl alcohol copolymers or acrylic copolymers containing 1 to 10% by weight of epoxy groups as comonomers such as glycidyl acrylate and glycidyl methacrylate. A combination of materials, polyester, etc. can be used. Particularly, polyvinyl alcohol copolymers exhibit excellent effects, perhaps because of their good miscibility.

The polymer having a cationic group and the polymer having an ultraviolet crosslinkable group are used in such a ratio that the former is /1)()-4,101%. If it is less than 10% by weight, sufficient effects will not be exhibited. 50% by weight of polymer with cationic groups
If it is less than that, the water absorbency will be insufficient, which is not desirable.

The effects of ultraviolet crosslinkable polymers can be expected by using either a method in which a radical crosslinkable group is combined with an ultraviolet crosslinking initiator, or a method in which the polymer is provided with a group that can be crosslinked by ultraviolet light alone. The ultraviolet crosslinking initiator in this case is selected from a wide range of initiators, such as ketones and triazoles, taking into consideration the degree of polymerization of the polymer used, the reactivity of crosslinking, the odor of the initiator, safety, etc. .

Depending on the UV-crosslinkable group, coating by mixing a solution of the cationic copolymer with the UV-crosslinking copolymer, cross-linking, and then drying will result in a better coating film than the cross-linked dry film. may have excellent transparency and water resistance. Therefore, by carrying out crosslinking before or after drying accordingly, the entire coating should exhibit sufficient water resistance and adhesive strength.

Both polymers can be used in either emulsion or solution form, but coating as a solution provides better transparency and
It also has excellent crosslinking properties and is therefore preferred.

Natural or processed adhesives such as waste powder, starch derivatives and cellulose derivatives, and binders with high self-speed brightness such as polyvinyl alcohol-based and polyvinyl acetate-based adhesives can be used in combination.

The coating layer is provided at a ratio of 5 g/m2 or more. This thickness is the amount necessary to sufficiently absorb the amount of aqueous ink used in ordinary inkjet printers.

The remarkable effects of the present invention are the cationic surface structure and hydrophilicity of the coating layer formed by mixing an ultraviolet crosslinkable polymer and a cationic polyvinyl alcohol copolymer, the water resistance due to ultraviolet crosslinking, and the sheet It is thought that this is due to the uneven distribution of cationic functional groups on the surface of the inkjet ink, which causes a unique interaction with the dye component, but the details are not clear. Presumably, the water-absorbing layer made of a mixture of these cross-linked copolymers and cationic polyvinyl alcohol copolymer has a uniform gel network consisting of ultraviolet cross-linking groups inside the water-absorbing layer containing cationic groups as an active ingredient. This is thought to be due to the fact that it is present in the water-based ink and reinforces the water-absorbing and drying effects of the water-based ink.

As the transparent sheet-like base material used in the present invention, a plastic film sheet made of polypropylene, polyethylene, polyester, etc. is used.

The thickness is determined by transformer alignment and workability with a printer, but is usually preferably 40 to 200 μm, and of course preferably has good transparency.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Actual weight and parts indicate parts by weight of solid content.

The polymers used in the examples are as follows.

Polymer-1 Polyvinyl alcohol-# copolymer (C-506, manufactured by Kuraray) containing one unit of a monomer having a quaternary ammonium salt as a side chain as a cationic group Polymer-2 Ultraviolet crosslinkable polyvinyl alcohol glycidyl acrylate Polymer-2 was obtained by radical polymerizing 10 parts of vinyl acetate and 40 parts of vinyl acetate, and using vinyl alcohol as the vinyl alcohol unit, which was saponified under the same conditions as those normally used for producing polyvinyl alcohol.

Polymer-3 Ultraviolet crosslinkable acrylic copolymer 30 parts of butyl acrylate, 30 parts of ethyl acrylate, 10 parts of glycidyl acrylate, and 30 parts of acrylic acid were heated in a mixed solvent of water:impropanol=1:1 to undergo radical polymerization. A solution of Polymer-3 having a concentration of 20% by weight was obtained.

Example 1 The following paint was applied on a 50 μm thick polyester film.
1 in terms of solid content 12. Coating so that it becomes j//yrL2,
It was dried, formed into a film, and crosslinked by irradiation with ultraviolet light. A transparent film for inkjet printers (trans-4 allency) was obtained.

Paint-1 Polymer-170 parts Polymer-230 parts Water: Isopropanol: Methyl ethyl; 2:1
: A solution having a concentration of 20% in a mixed solvent of 1 was designated as Paint-1.

Example 2 The following paint was applied on a 50 μm thick polyester film.
2 was coated to a solid content of 12/m2, crosslinked by irradiation with ultraviolet rays, dried, and formed into a film to obtain a transparent film.

Paint-2 Polymer - 170 parts Polymer - 330 parts An aqueous solution with a concentration of 20% was designated as Paint-2.

Comparative Example 1 The following paint-3 was applied on a polyester film with a thickness of 50 μm at a solid content of 12. ! i'/yrL'', dried, and formed into a transparent film.

Paint-3 Polymer - 1100 parts An aqueous solution with a concentration of 20% was designated as Paint-3.

Comparative Example 2: On a polyester film with a thickness of 50 μm, the following coating material-4 was coated to a solid content of 1297 m'', dried, formed into a film, and crosslinked by irradiation with ultraviolet rays to obtain a transparent film. Ta.

Paint-4 Polymer-3100 parts water: inopropanol dimethylethyl=2:1
: A solution having a concentration of 20% in a mixed solvent of 1 was designated as Paint-4.

Each coated film in these cases (Transia range)
) evaluation results are shown in the table.

The inkjet characteristics of each of the above-mentioned transveer ranges were determined using a commercially available inkjet printer at 20°C and 60°C.
Ink absorption, drying performance, and color vividness were evaluated using the following methods in an atmosphere of 5% RH.

Ink absorbency was evaluated by sensory evaluation of stickiness and offset of the image area after a certain period of time (1 minute, 30 minutes). Those that were dry and not sticky were designated as Ol, those that were significantly sticky were designated as ×1, and the intermediate value was designated as Δ.

The ink drying property was sensory evaluated by drying after a certain period of time (24 hours). A dry and non-sticky one was rated as ○, a markedly sticky one was rated as X, and an intermediate value of Δ was given.

The vividness of the color development was visually evaluated for the color development of single and two-color inks of yellow, magenta, and cyan, red, green, and blue. A clear color was defined as 01, a markedly faded color was defined as x1, and the intermediate value was defined as Δ.

Water Resistance C The upper image area was dipped in water and evaluated sensually. 01 for images that remain; × for images that have completely disappeared;
We set Δ to be in between.

Effects of the Invention The transparent inkjet recording sheet of the present invention has excellent ink absorption, drying properties, and brightness of color, and is also water resistant, eliminating the drawbacks of conventional methods. This enables high-resolution, high-speed inkjet full-color overhead projector transveer range.

Claims (1)

[Claims] 1. Containing a cationic group on a transparent sheet-like support,
Copolymer whose main constituent unit is vinyl alcohol 50~
Copolymer 50 containing 90% by weight and a group capable of ultraviolet crosslinking
1. An inkjet recording sheet, characterized in that a coating layer is formed by coating a coating material whose main component is 10% by weight at a rate of 5g/m^2 or more and crosslinking with ultraviolet rays. 2. The inkjet recording sheet according to claim 1, wherein the copolymer containing a group capable of crosslinking with ultraviolet rays has vinyl alcohol as a main constituent unit.