JPS60204390A - Ink jet recording paper - Google Patents

Abstract

PURPOSE:To provide the titled recording paper for multicolor recording, high in density of images and characters and having clear color tones, by using an ink- receiving layer comprising synthetic ultrafine silica obtained by a vapor phase method, in an ink jet recording paper comprising one or more ink-receiving layers on a base. CONSTITUTION:One or more ink-receiving layers comprising synthetic ultrafine silica (e.g., silica having a specific surface area according to the BET meahod of not lower than 100m<2>/g) obtained by a vapor phase method in an amount of, e.g., 0.5-20g/m<2>, preferably, 1-10g/m<2>, are provided on the base through an aqueous adhesive, followed by applying a pigment when necessary, to obtain the desired recording paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording sheet written using ink, and in particular, the images and characters recorded on the sheet have a high density (and a clear color tone, and the ink absorption speed is high). The present invention relates to an inkjet recording sheet that is suitable for multicolor recording and that has a high speed and improved gloss.

In recent years, the inkjet recording method is characterized by high speed, low noise, easy multicolor printing, great flexibility in recording patterns, and no need for development or fixing. It is rapidly becoming popular in various applications including copying devices. Furthermore, the images formed by the multicolor inkjet method are comparable to those produced by normal multicolor printing, and when the number of copies to be produced is small, the inkjet recording method is preferred for multicolor printing because it is cheaper than the normal plate making method. Attempts are being made to apply it to the field of color photography and printing.

The so-called baryta paper, which is used as a base for high-quality paper and coated paper used for general printing and photographic paper, has extremely poor ink absorption, so when used for inkjet recording, the ink remains on the surface for a long time. If the ink remains on the recording surface and is touched by a part of the device, by a vacuum cleaner, or if consecutively ejected sheets overlap, the recording surface is rubbed and the image is smeared with the residual ink. In addition, if two to four color ink droplets overlap in the same place in high-density image areas or multicolor recording, there may be problems such as the amount of ink being large and the ink mixing without being absorbed or flowing out. , there is no practical use.

In other words, the recording sheet can produce images with high density and clear tones, and not only absorbs ink quickly and does not run out, but also does not smudge even if touched immediately after printing. In addition, it is also required to suppress the lateral diffusion of ink dots on the surface of the recording sheet and to obtain a high-resolution image without bleeding.

Several proposals have been made to solve these problems. For example, IJ JP-A No. 52-53012 discloses an inkjet recording paper made by moistening a low-sized base paper with a paint for surface treatment. Also,
No. 4911.3/1983 discloses an inkjet recording paper in which a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer. Further, JP-A-55-5830 discloses an inkjet recording paper in which an ink-absorbing coating layer is provided on the surface of the support.
In JP-A No. 55-51583, #1 of 1k + 11 layers
An example using non-colloidal silica powder as the material has been disclosed, and JP-A-55-146786 discloses an inkjet recording paper provided with a water-soluble polymer coating layer. Furthermore, JP-A-55-11829 has a layer structure of two or more layers,
The ink absorption of the outermost layer is 1.5 to 5.5 mm/min, and the ink absorption of the second layer is 5.5 to 60.0 mm/min.
A method is disclosed for adjusting the spread of ink dots and the absorption speed by setting the ink dots to millimeters per minute.

However, the technical idea typified by JP-A-52-53012 is to obtain resolution at the expense of some ink absorbency, and JP-A-53-4
Although the technical concept represented by No. 9113 provides a certain degree of ink absorption and resolution, it has the drawback that ink penetrates deep into the paper layer, making it difficult to achieve ink density. The paper is unsatisfactory.

Therefore, as a method to improve these drawbacks, inkjet recording paper coated with non-colloidal silica powder was introduced by fS in 1985.
5,51583, and Japanese Patent Publication No. 53-790 discloses an optically readable barcode printing paper coated with finely powdered silicic acid.

By providing a layer of such synthetic silica or other white fine powder on the surface, resolution, color property, color density, absorption, roundness, etc. can be improved by a factor of 11, but these non-porous silica Powdered silicic acid is also called synthetic amorphous silica, and there are large differences in absorption capacity, color density, and color 11) suitability for inkjet, depending on the manufacturing method and manufacturing conditions. I understand.

As a result of intensive research into the relationship between the physical properties of synthetic amorphous silica and its suitability for inkjet printing, the present inventors found that among synthetic amorphous silica, silicon tetrachloride is burned together with hydrogen and oxygen using a dry method or gas phase method. The surface area oOtr measured by the BET method is
The inventors have discovered that inks of t7y and above are particularly excellent in color density and color reproducibility of ink images, and have accomplished the present invention.

The present invention will be explained in detail below. In the present invention, the ink-receiving layer refers to the ink-receiving layer when a sheet made from wood pulp and synthetic amorphous silica is used as a recording medium as it is, and the ink-receiving layer may be the entire sheet, or paper with a size When a sheet is used as a recording medium, in which a coating layer made of synthetic amorphous silica and an adhesive is provided on a support of a synthetic resin film, the coating layer serves as the ink-receiving layer. In other words, when inkjet recording is performed on a layer having voids that receive and absorb ink liquid, the surface thereof is called an ink-receiving layer.

The synthetic amorphous silica referred to in the present invention is 5i0 on a dry basis.
29:396 or more, A I 2 oa about 5% or less, Na
It refers to finely powdered silica produced by a wet process containing about 5% or less of 2O, so-called white carbon or silica gel, and ultrafine powdered silica produced by a dry process.

In other words, by metathesis of sodium silicate with acid, silica sol obtained through an ion-exchange resin layer, or colloidal silica or silica sol obtained by heating and aging this silica sol, gelling is performed and the production conditions are changed to produce a few millimicrons. Silica gel, which is a three-dimensional secondary ↑1f particle in which primary particles of about 10 millimicrons are bonded with siloxane, and furthermore, silica sol, silicic acid triuno, etc.
There are synthetic silicon compounds mainly composed of silicic acid, such as those produced by heating sodium aluminate, and so-called dry process silica, which is produced by burning silicon tetrachloride with hydrogen and oxygen.

The ultrafine particulate silica synthesized by the gas phase method used in the present invention refers to dry method silica among the various manufacturing methods described above, and Aerosil (Deguza) is a commercially available product. The content of the dry method-synthesized ultrafine silica in the ink receiving layer is 0.5 to 20y/ηr, preferably 1 to 1o.
It is y7n'.

The BET method referred to in the present invention is a method for measuring the surface area of powder using a one-phase adsorption method, and is a method of calculating the total surface area of a single sample, that is, the specific surface h1, from the adsorption isotherm. . Generally, nitrogen gas is often used as the adsorbed gas, and the most commonly used method is to measure the adsorbed amount from changes in the pressure or volume of the adsorbed gas. The most prominent expression of equimixture in multimolecular adsorption is f34wnnu<le,
This is the TL Tumul equation, which is called the BET equation, and is widely used to determine the surface area. Based on the BET formula, calculate the amount of adsorption and multiply by the area occupied by one adsorbed molecule on the surface.
Surface area is obtained.

The support used in the present invention is a sheet material such as paper or a thermoplastic resin film. There are no particular restrictions on the material (paper with appropriate sizing or films of polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polyethylene, polycarbonate, etc. can be used. These papers do not contain fillers. Alternatively, the thermoplastic resin film may be a transparent film containing no solid pigment, or a white film filled with white pigment or finely foamed. Titanium, calcium sulfate, calcium carbonate, silica,
Many materials such as clay, talc, zinc oxide, etc. can be used. There are no particular limitations on the thickness of these supports, but those of 10 μm to 300 μm are usually used.

There may also be a layer to improve adhesion between the film and the ink-receiving layer.

The formation of the ink-receiving layer on these supports consists of the above-mentioned dry process silica, an aqueous adhesive for adhering it to the support and, if necessary, a commonly used white pigment.

Commonly used white pigments that can be used in combination with dry process silica include calcium carbonate, kaolin (white clay), talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, and water. Aluminum oxide, diatomaceous earth, wet process silicic acid,
There are inorganic pigments such as calcium silicate, magnesium silicate, alumina, and lithopone, and organic pigments called plastic pigments made from urea resin and polystyrene resin.

Examples of adhesives include oxidized starch, etherified starch,
Starches such as esterified starch and dextrin, cellulose derivatives such as carboxydimethylcellulose and hydroxyethylcellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its derivatives, maleic anhydride resin, ordinary styrene-butadiene copolymer, methyl Conjugated diene polymer latex such as methacrylate-butadiene copolymer, acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester, vinyl polymer latex such as ethylene vinyl acetate copolymer , or functional group-modified polymer latex with monomers containing functional groups such as carboxyl groups of these various polymers, water-based adhesives such as thermosetting synthetic resins such as melamine resins and urea resins, and polymethyl methacrylate and polyurethane. Synthetic resin adhesives such as resin, unsaturated polyester resin, vinyl chloride-vinyl acetate 1 polymer, polyvinyl butyral, and alkyd resin are used. These adhesives are used in an amount of 2 parts to 50 parts, preferably 5 parts to 100 parts of pigment.
Although 30 parts are used, the ratio is not particularly limited as long as it is sufficient to bind the pigment. However, if 100 parts or more of adhesive is used, the peak of the pore distribution curve of the present invention may be shifted due to film formation of the adhesive, which is not very preferable.

Furthermore, if necessary, pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, molding agents, foaming agents, coloring agents, etc. may be added as appropriate. When forming the ink-receiving layer provided on the body by applying a pigment coating liquid, etc., use commonly used coating machines such as a blade coater, air knife coater, roll coater, flash coater, curtain coater, and bar coater. Coater, gravure coater, spray etc. can all be used for jI!fi.Furthermore, if the support is paper, size press on paper machine,
It is also possible to use gate rolls, devices, etc.

A sheet simply provided with an ink-receiving layer on a support can be used as it is as a recording sheet according to the present invention, but it may also be passed through a roll nip under heat and pressure using a super calender, gloss calender, etc. to impart surface smoothness. It is possible.

The present invention will be described below with reference to examples, but it is not limited to these examples. Note that parts and percentages shown in the examples mean parts by weight and percentages by weight.

The inkjet suitability in Examples was determined by the following measurement method.

(1) Ink absorption speed Contact the red printing part (cyan yellow) of an inkjet printer (Sharp Color Image Printer IO-0700) with the paper presser roll immediately after solid printing (after about 1 second) to check for stains. Determine whether it appears or not.

(2) Ink absorption capacity Determined by the degree of bleeding at the boundary of the solid print area of the same inkjet printer.

(3) Determine the area of black ink dots of a printer with the same dot diameter,
Assuming that it was a perfect circle, a value calculated as its diameter was used.
(μmφ) (4) Color density color inkjet printer (Sharp, LO-7
00), solid printing was performed in four colors of magenta, cyan, yellow, and black, and the color density was measured using a Macbeth densitometer RD514.

Example 1 90 parts of L B K P of 380 shoulder l of Japanese bark, 4 pieces of Japanese bark
To a pulp slurry consisting of 10d of NBKP IQ parts, 10 parts of talc was added as a sizing agent, and 0 parts of rosin sizing agent was added.
．． Add 3 parts and 2.2 parts of the band and make paper using a fourdrinier machine,
To a coated base paper manufactured by adhering 2.8 Pld of oxidized starch in solid content using a size press machine, 13 parts of polyvinyl alcohol as an adhesive was added to a slurry consisting of 80 parts of wet-process synthetic silica as a pigment and 20 parts of heavy calcium carbonate. A base paper was prepared by applying a paint to which a foaming agent, a flow modifier, a preservative, a hardening agent, etc. had been appropriately added using an air knife coater to a solid content of 10 g/b.

Concentration of polyvinyl alcohol 496 and vapor phase synthesis ultram
Particulate silica (Aerosil 200 manufactured by Nippon Aerosil Co., Ltd.
Prepare a coating solution consisting of 496 (surface area: 200g/fl),
The coating layer of the base paper was coated with an air knife coater to a solid content of 5 y/d and dried. Next, it was lightly supercalendered to obtain the recording paper of Example 1.

For comparison, the above vapor phase synthesized ultrafine particulate silica was replaced with wet process synthesized silica (Nip Seal E2 manufactured by Nippon Silica Co., Ltd.).
Comparative Example 1 was prepared in exactly the same manner as in Example 1, except that 2OA (surface area: 130 tl/P) was used, and no synthetic silica was used, and only polyvinyl alcohol was used on the base paper with a solid content of 2.5 P. The recording paper of Comparative Example 2 was prepared by smearing the paper so as to give a color of /rye.

Examples 2 to 5 100 parts of synthetic amorphous silica (Syroid 404, manufactured by Fuji Davison Co., Ltd.) and dry method synthetic ultrafine particulate crystals (Aerosil MOX, manufactured by Nippon Aerosil Co., Ltd.) were coated on a coated base paper of tsubo ff 163 P/vl and Steckigt size 22 seconds. 170 parts, 30 parts, 60 parts, 150 parts, respectively
Furthermore, 30 parts of an adhesive (PVA117 manufactured by Kuraray Co., Ltd.) was dispersed at a concentration of 1896, an antifoaming agent was added, and the mixture was thoroughly stirred to prepare a coating liquid.

This was coated on one side to a solid content of 159/lrt, dried, and then supercalendered to smooth the surface. The recording paper of Example 6 was prepared in exactly the same manner except that 100 parts of /y) was added.

A recording sheet of Comparative Example 3 was prepared in the same manner as in the example except that the ultrafine particulate silica synthesized by the dry process was not added at all.

Table 1 shows the results of evaluating the inkjet suitability of these recording papers.

15- As shown in Table 1, Examples 1 to 6 containing vapor phase ultrafine particulate silica have extremely superior color density compared to comparative examples containing only silica other than vapor phase process. Is recognized. In addition, the surface area is 100rr using vapor phase ultrafine particulate silica.
It can be seen that Example 6, which is less than t/fl, is inferior to Examples 4 and 5, and requires a larger amount to be added in order to exhibit the same effect.

16-

Claims (1)

[Scope of Claims] 1. An inkjet recording paper comprising one or more ink-receiving layers provided on a support, at least synthetic ultrafine particulate silica formed by the gas II method in the ink-receiving layer. An inkjet recording paper characterized by containing: 2. The surface area of synthetic ultrafine particulate silica according to the BET method is 1
00 rn''/P or more, the inkjet recording paper according to claim 1.