JPH0255185A - Material to be recorded and ink jet recording method using the same - Google Patents

Abstract

PURPOSE:To obtain a material to be recorded having excellent ink absorptivity, excellent sharpness and resolution of recording image by providing an ink holding layer and an ink transport layer on a base material so that the transport layer contains porous particles with specific porosity. CONSTITUTION:In a material to be recorded having an ink holding layer and an ink transport layer on a base material, the transport layer contains porous particles, and its porosity is ranged from 0.76-0.91. The material to be recorded is applied to an ink jet recording method for recording by a recording type of 10nl/mm<2> or more of maximum ink applying amount in case of 2-color lap printing. Its porosity is, when the apparent volume of the transport layer is v2 and the true volume is v1, called 'the value represented by porosity = (v2-v1)/v2'. Such a porosity is calculated by calculating the apparent volume v2 from the thickness and area of the transport layer, and measuring the true volume v1 of the transport layer with inert solvent for the transport and holding layers.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a recording material suitable for color inkjet recording and an inkjet recording method using the same, and particularly to a recording material suitable for color inkjet recording and an inkjet recording method using the same. The present invention relates to a recording material with excellent ink absorbency and sharpness of recorded images in full-color recording, and an inkjet recording method using the same.

[Prior Art] The ink sheet recording method has been recognized as a recording method that does not generate noise and can perform high-speed printing and multicolor printing.

Various recording materials have been proposed for use in such inkjet recording.

For example, JP-A-55-144172 describes a sheet comprising a porous ink absorption layer provided on a base material.

By using such a sheet, it is possible to increase the ink absorption to some extent, but since the ink absorption layer is porous, the sheet has light diffusing properties, resulting in clear and high image density. The disadvantage is that a glossy image cannot be obtained.

In addition, since the recorded image is observed from the ink recording surface, the recording agent is configured to remain as much as possible on the surface of the ink absorbing layer, which has the disadvantage that the durability and storage stability of the image, such as water resistance and abrasion resistance, are inferior. There is.

As one way to solve these problems,
Japanese Patent No. 136480 discloses a recording material in which at least one ink-receiving layer containing a pigment as a main component is provided on a transparent support, and the formed image is observed from the support side.

When an image is formed using such a recording material, the performance of the image on the image viewing surface (support side), such as water resistance and gloss, is excellent, but since the pigment layer is adjacent to the support,
The dye in the applied ink is hidden by the pigment particles, resulting in a low density image observed from the support side, which has the disadvantage that a high-quality image cannot be obtained.

Furthermore, when a color image is recorded on this recording material, the ink that reaches the interface of the support stays there and spreads laterally across the interface of the support, resulting in poor resolution of the image.

Therefore, in order to eliminate such drawbacks, Japanese Patent Application Laid-Open No. 62-22
No. 2886, No. 62-242575, No. 62
No. 242,576 and No. 63-34176 propose recording materials in which a porous ink transport layer and a non-porous ink retaining layer are provided on a support.

[Problems to be Solved by the Invention] By using the above-mentioned recording material, it is possible to obtain a high-quality image with a high density of an image observed from the support side, thereby solving the above-mentioned problems.

However, in recent years, as recording has become more dense, faster, and full-color, it has become necessary to quickly absorb a large amount of ink applied per unit area of the recording material, and to have excellent image sharpness. However, the above-mentioned recording materials do not fully satisfy such requirements.

Therefore, an object of the present invention is to solve the problems of the prior art, and to provide excellent ink absorption even when a large amount of ink is applied as in full-color recording, and to improve the sharpness and resolution of recorded images. An object of the present invention is to provide an excellent recording material and an inkjet recording method using the same.

[Means and effects for solving the problems] The above objects are achieved by the present invention as described below.

That is, the present invention provides an ink retaining layer and an ink transport Jf on a base material.
A recording material provided with fl, characterized in that the surface ink transport layer contains porous particles and has a porosity in the range of 0.76 to 0.91, and the recording material However, the maximum amount of ink applied when printing two colors overlapping is 1
This is an inkjet recording method that performs recording using 0nb.

The present invention will be explained in detail below.

The basic characteristic of the recording material of the present invention is that the optical density (0,0) of the image on the image observation surface (substrate side) is higher than the optical density (0,0) of the image on the recording surface (ink transport layer side). This is what we have.

The feature of the present invention is that it has the above basic characteristics and that the porosity of the ink transport layer is adjusted to a range of 0.7 δ to 0.91.

In the present invention, the porosity refers to the porosity = (v2 - v
l)/v2.

Specifically, the apparent volume V2 of the ink transport layer is calculated from the thickness and area of the ink transport layer, and then an inert solvent (e.g. water, benzene) is added to the ink transport layer and the ink retaining layer. , ethanol, etc.) by measuring the true volume v1 of the ink transport layer.

The present invention will be explained below based on preferred embodiments.

The recording material of the present invention includes a transparent base material as a support, an ink retention layer formed on the base material that absorbs and traps substantially ink or recording agent, and an ink retention layer formed on the ink retention layer. It is composed of an ink transport layer that directly receives ink and has liquid permeability.

The ink transport layer according to the present invention has liquid permeability and has the function of rapidly absorbing and transmitting ink adhering to its surface.

At this time, the ink transport layer must have a high affinity for the liquid medium in the ink, and at the same time must have a high affinity for the recording agent (colorants such as dyes and pigments and materials with coloring properties). must be of low sex.

Therefore, the ink transport layer must be constructed by selecting a material that has properties such as wetting, penetration, and diffusion for the ink medium, but does not have properties such as adsorption, staining, and reaction for the recording medium. Must be.

A preferred embodiment for improving the liquid permeability of the ink transport layer is one in which the ink transport layer has a porous structure with cracks and communication holes inside.

The ink transport layer that satisfies the above characteristics is mainly composed of porous particles that do not stain the recording material and a binder.

The porous particles used in the present invention have a diameter of 0.01 to 2 μm, preferably 0.05 to 2 μm! More preferably 01 to 05 μm1
Microparticles with a size of μm are aggregated to form particles with a size of 1 to 30 μm, preferably 2 to 20 μm, and more preferably 3 to 10 μm, and this secondary and tertiary agglomerated porosity Particles are not easily dispersed or dispersed.

Such porous particles include organic materials such as polystyrene, polymethacrylate, elastomer, ethylene-vinyl acetate polymer, styrene-acrylic copolymer, polyester, polyacrylic, polyvinyl ether, polyamide, polyolefin, polyester, etc. Silicone, guanamine, polytetrafluoroethylene, 5BR1
Materials such as urea resin, urea-formalin resin, etc. 4. Inorganic materials such as synthetic silica, clay, talc, diatomaceous earth, calcium carbonate, titanium oxide, zinc oxide, calcium sulfate, barium sulfate, zinc sulfide, Porous particles of at least one of materials such as satin white, aluminum silicate, lithopone, aluminum hydroxide, calcium silicate, etc. are used.

Furthermore, the binder used has the function of binding the particles to each other and/or to the ink retaining layer, and like the particles, it is preferable that the binder is non-staining to the recording material.

As a preferable binding material, any conventionally known material can be used as long as it has the above-mentioned functions; for example,
Polyvinyl alcohol, acrylic resin, styrene-acrylic copolymer, polyvinyl acetate, polyurethane, ethylene-vinyl acetate copolymer, starch, polyvinyl acetal, gelatin, casein, ionomer, gum arabic, carboxydimethylcellulose, polyvinylpyrrolidone, polyvinyl acetate Acrylamide, phenol, melamine, epoxy, styrene-butadiene rubber, 1 finger of urea tree, α-
One or more resins such as olefin resin, chlorobrene, and nitrile rubber can be used.

In the present invention, the porosity of the ink transport layer is adjusted to a range of 0.76 to 0.91 by appropriately selecting the type and size of the porous particles and the mixing ratio of the porous particles and the binder. I can do something.

The mixing ratio of the porous particles and the binder varies depending on the type and size of the porous particles, but the weight ratio is preferably in the range of 1071 to 1/2, more preferably 5/1 to +/+. range.

When the empty 11!2 ratio of the ink transport layer is less than 0.76,
The resolution of the image decreases, and if it exceeds 091, the sharpness of the image and the strength of the ink transport layer decrease, which is not preferable.

In the present invention, the porosity of the ink transport layer is preferably in the range of 078 to 088.

When single particles called primary particles are used instead of porous particles, it is difficult to adjust the porosity of the ink transport layer to the above range, and even if the porosity of the ink transport layer can be adjusted to within the above range. Even so, the strength of the ink transport layer as a layer becomes weak and it becomes impractical.

In the present invention, various additives such as surfactants, penetrants, fluorescent dyes, colored dyes, crosslinking agents, etc. may be added as necessary to further improve the function of the ink transport layer. .

The thickness of the ink transport layer is preferably in the range of 5 to 150 μm, more preferably in the range of 10 to 50 μm.

Next, the ink retaining layer needs to have a stronger ink absorption ability than the ink transport layer in order to stably absorb and capture the ink temporarily absorbed by the ink transport layer. Therefore, the ink retaining layer must have high affinity for the recording agent as well as for the ink medium.

When the absorption power of the ink retention layer is weaker than the absorption strength of the ink transportation layer, when the ink applied to the surface of the ink transportation layer passes through the ink transportation layer and reaches the ink retention layer,
When the ink stays in the ink transport layer, the ink permeates and diffuses in the ink transport layer in the lateral direction more than necessary at the interface between the ink transport layer and the ink retention layer.

As a result, the resolution of the recorded image decreases, making it impossible to form a high-quality recorded image.

Further, since the recorded image is observed from the side opposite to the recording surface as described above, it is preferable that the ink retaining layer is light-transmissive.

The ink retaining layer that satisfies the above requirements is preferably composed mainly of a light-transmitting resin that adsorbs the recording agent and/or a light-transmitting resin that is soluble and swellable for the ink.

For example, when a water-based ink containing an acid dye or a direct dye is used as a recording material, the ink-retaining layer is made of a resin that has adsorption properties for the dye, such as a water-soluble resin that has swelling properties for the water-based ink. Preferably, it is made of a wood-philic polymer.

Examples of such water-soluble or hydrophilic polymers include albumin, gelatin, casein, starch, cationic starch, gum arabic, natural resins such as sodium alginate, carboxydimethylcellulose, hydroxyethylcellulose, polyamide, polyacrylamide, polyethyleneimine, Synthetic resins such as polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, polyvinylpyricillium halide, melamine, phenol, alkyd, polyurethane, polyvinyl acetal, boranovinyl alcohol, ion-modified polyvinyl alcohol, polyester, polysodium acrylate, etc., preferably Examples include hydrophilic polymers made by crosslinking these polymers to make them water-insoluble, hydrophilic and water-insoluble polymer complexes made of two or more types of polymers, and hydrophilic and water-insoluble polymers having a tree-philic segment.

The film thickness when forming the ink retaining layer using the above material is preferably 1 to 30 μm, more preferably 3 to 10 μm.
m range.

As the translucent substrate used in the present invention, any conventionally known substrate can be used, and specific examples thereof include resin films such as polyester, glass plates, and the like.

In the present invention, it is preferable that the base material has translucency, but when the ink transport layer is made transparent by heating, pressure, etc. after recording and the image is observed from the recording surface, the base material is transparent. It may be opaque. As a method for forming an ink retaining layer and an ink transport layer on the above-mentioned substrate, the above-mentioned new materials are dissolved or dispersed in a suitable solvent to adjust the coating strength, and this coating liquid is applied to a roll, for example. It is preferable to coat the substrate by a known method such as a coating method, rod bar coating method, or air knife coating method, and then dry it immediately. A method such as forming a sheet and then laminating the sheet to an il material may also be used.

However, when providing the ink retaining layer on the base material, it is preferable to strengthen the adhesion between the base material and the ink retaining layer by, for example, forming an anchor coat layer and to eliminate spaces.

If a space exists between the base material and the ink retaining layer, the surface of the recorded image will reflect diffusely, which will substantially lower the optical density of the image, which is not preferable.

In the present invention, an image is formed using the above recording material, but in full color recording, when printing in two colors, the maximum amount of ink applied per unit area of the recording material is 1.
The effect of the present invention becomes remarkable by using a recording method with a recording rate of 0 nl/mm2 or more.

[Examples] The present invention will be specifically described below based on Examples. still,
In the text, percentages or parts are based on weight.

Examples 1 to 3, Comparative Example 1.2 A polyethylene terephthalate film (thickness 75 μm 1 Lumirror Q-80, manufactured by Toshi) was used as a translucent base material, and the following composition A was applied on this base material to a dry film thickness. The ink retaining layer was coated with a bar coater to a thickness of 5 μm, and dried in a drying oven at N0° C. for 8 minutes to form an ink retaining layer.

Composition A Cation-modified polyvinyl alcohol XH part (PVA-
C-318-2A, manufactured by Kuraray) Blocked isocyanate 3 parts (Elastron BN-5 manufactured by Dai-Kogyo Seiyaku) Catalyst (small amount) Furthermore, apply the following composition B on the ink retaining layer using a bar coater so that the dry film thickness is 35 μm. The ink transport layer was then dried at 140° C. for 5 minutes in a drying oven to form recording materials of the present invention and for comparison as shown in Table 1.

Composition B Urea-formalin resin particles X% (primary particle size 0.3 μm, secondary particle size 5 μm) Polyvinyl butyral Y% 10% ethyl cellosol 11 Container 11 Fluorescent brightener 0.2% Ethyl cellosolve 54% 1st
Table *Porosity was calculated based on the description in the specification.

The maximum amount of ink applied per unit area of the recording material is 12n1 when performing two-color solid printing on the recording material mentioned above.
/lu[112 and printer A is 18nl/mm2
Recording was performed using Printer B.

The recorded matter thus obtained was evaluated in accordance with the following method to determine whether it was sufficiently suitable for the purpose of the present invention. The results are shown in Table 2.

1) The recorded image density (0.0.) is obtained by printing black i color on the recording material and recording surface a (ink import layer side).
and the image density of image observation surface b (substrate side) using Machess RD-
Measured using 918.

2) Ink absorption was measured by printing yellow ink and magenta ink in a solid layer, leaving the recorded matter at room temperature, and measuring the time until the ink no longer adhered to the finger even if the recorded area was touched with the finger. .

3) The sharpness of the image is determined by observing a recorded material in which yellow ink and magenta ink are printed overlappingly to form a red band-like pattern from the substrate surface, and if the edge of the image is clear, it is marked as ○, or blurry. Let X be the one that is.

4) The resolution of the image was determined by comparing the recorded matter of 3) with a recorded matter in which yellow ink, magenta ink, and cyan ink were printed overlappingly to form a non-striped pattern similar to the pattern of 3). For comparison, those with the same pattern width on the recorded matter were marked as ○, and those with a difference b were marked as X.

5) Powder shedding: When the surface of the ink transport layer was rubbed with a finger, a case where powder fell off was rated as an X, and a case where no powder fell off was rated as a ○.

6) Color suitability is determined by forming appropriate full-color images using printers a and b, visually comparing the recorded images from the substrate surface, and marking the most preferable one as ◎ and the worst one as ×. ◎, ○, △, [Effects] As mentioned above, the recording material of the present invention is fully compatible with color inkjet recording where a large amount of ink is applied per unit area, and has excellent ink absorption, sharpness and resolution of recorded images. ni(2re,
This provides high-quality, full-color images.

Claims (2)

[Claims] (1) In a recording material having an ink holding layer and an ink transport layer on a base material, the ink transport layer contains porous particles and has a porosity in the range of 0.76 to 0.91. A recording material characterized by: (2) An inkjet recording method using a recording method in which the maximum amount of ink applied per unit area when two colors are overprinted on a recording material is 10 nl/mm^2 or more,
The recording material has an ink holding layer and an ink transport layer, and the ink transport layer contains porous particles and has a porosity of 0.
An inkjet recording method characterized in that the inkjet recording method is in a range of 76 to 0.91.