JPS6365038B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a recording material (recording paper) used in an inkjet recording method, and particularly to a recording material that has high ink absorption and excellent ink color development. . [Prior Art] Recording methods using recording liquid have been common for a long time, such as writing with a fountain pen, but recently, so-called inkjet recording methods have also appeared, and recording liquid is also used here. There is. The inkjet recording method generates small droplets of recording liquid using various operating principles, and performs recording by flying these droplets and adhering them to a recording material such as paper, but it generates little noise and can print at high speed. , is attracting attention as a recording method that allows multicolor printing. Water-based recording liquids are mainly used for inkjet recording in view of safety and printability. As the recording material used in this inkjet recording method, conventional paper has generally been used. However, as the performance of inkjet recording machines improves, such as faster recording and multicolor recording, recording materials for inkjet recording are also required to have more advanced characteristics. In other words, as a recording material for inkjet recording to obtain high resolution and high quality recorded images, 1) it should absorb ink as quickly as possible, and 2) it should not adhere later when ink dots overlap. 3) The diameter of the ink dot should not become larger than necessary; 4) The shape of the ink dot should be close to a perfect circle and the surrounding area should be smooth; 5) The density of the ink dot It is necessary to meet various requirements such as high image quality and no blurring around the dots. Furthermore, in order to obtain a recorded image quality comparable to that of a color photograph using a multicolor inkjet recording method, in addition to the above-mentioned performance requirements, 6) high whiteness, and 7) excellent color development of the coloring components of the ink are required. 8) There are as many ink droplets as there are ink colors.
Since the ink may be deposited in layers on the same spot, additional performance is required, such as particularly excellent ink absorbency. However, the reality is that a recording material that satisfies all of these required performances has not yet been found. For example, the inkjet recording paper described in JP-A-52-74304 absorbs ink quickly, but the dot diameter tends to become large, the periphery of the dots tends to blur, and the dimensional change after recording is large. have. [Object of the Invention] An object of the present invention is to provide a full-color recording material for inkjet recording that satisfies the above-mentioned requirements and has particularly high ink absorption and excellent color development. The above and other objects are achieved by the following invention. [Disclosure of the Invention] That is, the present invention provides a recording material for inkjet recording in which an ink-receiving layer containing filler particles is provided on a support, in which filler particles having a size in the range of 3 to 25 μm are ink-receptive. 10,000 to 100,000 particles are exposed per 1 mm ² on the surface of the layer, and the maximum height per 2.5 mm standard length of surface roughness based on JIS B 0601 of the surface of the ink receiving layer is 10 μm to 35 μm.
This is a recording material for inkjet recording, characterized in that the amount is within the range of . The recording material of the present invention is characterized by the unique surface condition of the ink-receiving layer. That is, based on the surface roughness measurement method of JIS B 0601,
The average maximum height per 2.5 mm standard length of ten arbitrary points extracted from the surface of the ink-receiving layer is 10 μm or less.
This is a value within the range of 35 μm, which means that, for example, amorphous filler with a relatively large particle size, which is the main component of the ink-receiving layer, is placed randomly. This refers to the surface structure that appears on the surface of the ink-receiving layer and has many large voids scattered between the filler particles that function as ink-absorbing pores, typically as shown in Figure 1. It is shown as the state of Of course, these filler particles appearing on the surface are also fixed within the ink-receiving layer by the binder and do not easily separate from the ink-receiving layer. Figure 1 is a scanning electron micrograph of the surface of the ink-receiving layer of the recording material of the present invention at a magnification of approximately 1500 times. is well shown. On the other hand, FIG. 2 is an electron micrograph at the same magnification of the surface of a recording material having a conventional ink receiving layer. The surface of this recording material has a surface structure in which the ink-receiving layer is flattened while having many micropores that serve as ink-absorbing holes, and the maximum height value of the surface roughness is small. It is clearly distinguished from the recording material of As described above, the surface roughness of the ink-receiving layer of the recording material of the present invention is rough, and there are large and numerous voids between filler particles that become ink absorption pores.
When recording with ink is performed, the ink is quickly absorbed into the gaps between the filler particles, and the ink absorption capacity is large. The maximum height value of the surface roughness of the ink receiving layer is
If it is less than 10 μm, the ink absorbency is insufficient, while if the maximum height of the surface roughness exceeds 35 μm, the ink absorbency is good but the resolution of the recorded image is reduced. As the support for the recording material of the present invention, it is appropriate to use paper, but cloth, resin film, synthetic paper, etc. can also be used. On the other hand, the ink receiving layer of the recording material of the present invention is basically composed of filler particles and a binder.
The filler particles include, for example, silica, clay,
Talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, zinc oxide,
White inorganic pigments such as Sachin White, aluminum silicate, lithopone, alumina, and zeolite;
Examples include organic powders such as ion exchange resin powders and plastic pigments, and one or more of these may be used. The amorphous shape of the filler particles appears like scattered rubble on the surface of the ink-receiving layer, and the surface roughness of the ink-receiving layer takes a certain maximum height value depending on the filler particles used. Particle size is 1 to
It is desirable that the thickness be about 30 μm, more preferably about 3 to 20 μm. If the particle size of the filler particles is too large, the roundness of the ink dots will be impaired and the resolution of the recorded image will be reduced, which is not preferable. The higher the dye adsorption ability of the filler particles, the more preferable they are, and it is more preferable that they have a porous structure. This is because the color development is better when the pigment in the ink absorbed into the gaps between the filler particles is captured in the outermost layer of the ink-receiving layer. On the other hand, the binder includes water-soluble polymers such as starch, gelatin, casein, gum arabic, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, and polyacrylamide; synthetic resins such as synthetic rubber latex. Examples include organic solvent-soluble resins such as latex, polyvinyl butyral, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polymethyl methacrylate, polyvinyl formal, melamine resin, polyamide resin, phenolic resin, polyurethane resin, and alkyd resin. Further, various additives such as a dispersant, a fluorescent dye, a PH adjuster, an antifoaming agent, a lubricant, a preservative, and a surfactant can be mixed in the ink-receiving layer. The recording material of the present invention is prepared by dispersing these ink-receiving layer components in a medium such as water, and applying a coating solution to a support by a roll coating method, a rod bar coating method, a spray coating method, an air knife coating method, etc. It can be manufactured by coating it on top and then drying it as soon as possible. The mixing ratio of filler particles and binder in the coating liquid is as follows:
Generally, 10 parts by weight of binder is added to 100 parts by weight of filler particles.
A suitable amount is from 100 parts by weight, and when the average particle size of the filler particles is large, good results are obtained by using as little binder as possible. The amount of the ink-receiving layer on the support is usually about 1 to 50 g/m ² (dry coating amount). Also,
Preferably, the coating amount is about 2 to 30 g/m ² (dry coating amount). [Effects of the present invention] The recording material of the present invention, in which an ink receiving layer having a specific surface roughness is provided on a support in this way, has extremely high ink absorbency, and a recording liquid of a different color can be absorbed for a short period of time. Even if the recording liquid adheres to the same location in duplicate, there is no outflow or oozing phenomenon of the recording liquid, and a clear image with high resolution can be obtained. Furthermore, it exhibits excellent color development properties and is suitable as a recording material for inkjet recording when performing full-color recording. [Example] Hereinafter, the present invention will be described in more detail with reference to Examples. Example 1 Silica (Syroid 620, trade name, manufactured by Fuji Davison Chemical Co., Ltd., average particle diameter:
20μm) and calcium carbonate (average particle size: 2μm)
and polyvinyl alcohol as a binder.
An ink-receiving layer coating composition was prepared using SBR latex based on the following composition. Silica 100 parts by weight Calcium carbonate 15 〃 Polyvinyl alcohol 25 〃 SBR latex 5 〃 Water 300 〃 On the other hand, general high-quality paper (basis weight 65 g/m ² ) with a sizing degree of 35 seconds based on JIS P8122 was used as the support. The above-mentioned coating composition was coated onto this support by a blade coater method in a dry coating amount of 10 g/m ² and dried by a conventional method to obtain a recording material.
FIG. 1 shows a scanning electron micrograph of the surface of the ink-receiving layer of the obtained recording material at a magnification of about 1500 times. The maximum height value of the surface roughness of this recording material was 22 μm. Note that the surface roughness is TALYSURF4 (TAYLOR−
(manufactured by HOBSON), measure the maximum height per 2.5 mm reference length of ten arbitrary points extracted from the surface of the ink-receiving layer based on the surface roughness measurement method of JIS B 0601, and calculate the average value. It was taken as the measured value. Example 2 Diatomaceous earth (average particle size:
An ink-receiving layer coating composition was prepared based on the following composition using polyvinyl alcohol and SBR latex as a binder. Diatomaceous earth 100 parts by weight Polyvinyl alcohol 20 〃 SBR latex 10 〃 Water 300 〃 On the other hand, the same general high-quality paper as in Example 1 was used as a support, and the above coating composition was dried and coated on this support. It was coated by a bar coater method at a rate of 15 g/m ² and dried by a conventional method to obtain a recording material. The maximum height value of the surface roughness of this recording material is
It was 19μm. Example 3 Clay as filler particles (average particle size: 1 μm)
and calcium carbonate (average particle size: 20 μm),
A coating composition was prepared based on the following composition using starch and ethylene vinyl acetate emulsion as a binder. Clay 80 parts by weight Calcium carbonate 20 Starch 15 Ethylene-vinyl acetate emulsion 5 Water 200 On the other hand, the same general high-quality paper as in Example 1 was used as the support, and the above coating composition was applied to the support. The material was coated using a blade coater method at a dry coating weight of 20 g/m ² and dried by a conventional method to obtain a recording material. The maximum height value of the surface roughness of this recording material was 32 μm. Comparative Example 1 A scanning electron micrograph of the surface of the ink-receiving layer of commercially available art-coated paper (trade name: SK Coat, manufactured by Sanyo Kokusaku Pulp Co., Ltd.) used as a recording material at a magnification of approximately 1500 times is shown in Figure 2. It was something. The maximum height value of the surface roughness of this recording material was 5 μm. Comparative Example 2 A coating composition was prepared based on the following composition using calcium carbonate (average particle size: 50 μm) and plastic pigment (average particle size: 50 μm) as filler particles and polyvinyl alcohol as a binder. . Calcium carbonate 100 parts by weight Plastic pigment 10 〃 Polyvinyl alcohol 2 〃 Water 50 〃 On the other hand, the same general high-quality paper as in Example 1 was used as a support, and the above coating composition was dried and coated on this support. It was coated at a rate of 25 g/m ² by a bar coater method and dried by a conventional method to obtain a recording material. The maximum height value of the surface roughness of this recording material is
It was 44μm. Reference Example Color inkjet recording was performed using the following four colors of ink on the five recording materials shown in the above Examples and Comparative Examples, and the recording characteristics were evaluated. Yellow ink (composition) CI acid yellow 23 2 parts by weight Diethylene glycol 30 〃 Water 70 〃 Agenta ink (composition) CI acid red 92 2 parts by weight Diethylene glycol 30 parts by weight Water 70 〃 Cyan ink (composition) CI Direct Blue 86 2 parts by weight Diethylene glycol 30 〃 Water 70 〃 Black ink (composition) CI Direct Black 19 2 parts by weight Diethylene glycol 30 〃 Water 70 〃 Table 1 shows the evaluation results of the recording characteristics of each recording material. Note that the recording characteristics were evaluated based on the following criteria. 1) Dot density is determined by measuring the printed dots using Sakura Microdensidometer PDM-5 (Konishi Roku Photo Industry Co., Ltd.)
(manufactured by). 2) The shape of the dots was determined by observing the printed dots with a stereomicroscope, and marking the dots almost circular as ○, those with a slightly distorted circular shape as △, and the irregularly shaped dots as ×. 3) The degree of bleeding was determined by measuring the diameter of the printed dot using a stereomicroscope, and was expressed as how many times larger the diameter of the printed dot was than that of the ink droplet. 4) Color clarity is determined by visually comparing the color clarity of the inkjet recorded images, with the best one being ◎ and the worst being ×, ◎, 〇, △, ×.
We ranked them by rank. 5) Regarding ink absorbency, when four colors of ink were layered and recorded, the case where the ink did not run out and the image was clear was rated as ○, and the other cases were rated as ×. In Table 1, the color of the ink used in the evaluation is shown within the brackets in the evaluation column for each recording characteristic. 【table】

[Brief explanation of drawings]

FIG. 1 is a drawing-substituting photograph of the surface of the ink-receiving layer of the recording material of the present invention taken with a scanning electron microscope at a magnification of about 1500 times, and FIG. This photo is a substitute for a drawing.

Claims (1)

[Claims] 1. In a recording material for inkjet recording in which a support is provided with an ink receiving layer containing filler particles, 10,000 filler particles having a size in the range of 3 to 25 μm are present per 1 mm ² on the surface of the ink receiving layer. ~100,000 pieces are exposed, and JIS on the surface of the ink receiving layer
A recording material for inkjet recording, characterized in that the maximum height per 2.5 mm standard length of surface roughness based on B 0601 is within the range of 10 μm to 35 μm.