JPS6116883A - Manufacture of recording paper - Google Patents

Abstract

PURPOSE:To prevent a color change by the preservation of a record medium and the color change of a recording picture by including a porous inorganic pigment into an ink receiving layer and obviating the inclusion of a lipophilic vehicle into printing ink. CONSTITUTION:When marks and/or rulings, etc. are printed onto the surface and/or back of recording paper with an ink receiving layer containing a porous inorganic pigment by using normal printing ink, printing ink used for the titled manufacture is distinguished from normal printing ink, through which marks, rulings, etc. are printed by employing aqueous printing ink in which printing ink does not contain a lipophilic vehicle, as quick set ink according to classification by drying types, oil ink according to classification by the compositions of the vehicles and aqueous ink, and the ink, which does not contain the lipophilic vehicle, represents aqueous ink. A substance in which the primary grains of synthetic silica or synthetic alumina are agglomerated and changed into dried powered bodies having mean secondary grain size of 0.5-30mum is used as the porous inorganic pigment.

Description

Detailed Description of the Invention (A) Industrial Field of Application The present invention relates to a method for manufacturing a recording medium that is recorded using inkjet ink, and particularly relates to a method for manufacturing a recording medium that is recorded using inkjet ink, and in particular, the present invention relates to a method for manufacturing a recording medium that is recorded using inkjet ink. The present invention relates to a method for producing an inkjet recording medium that has a clear color tone, has excellent ink absorption ability, and is free from image staining due to discoloration of the medium.

The inkjet recording method uses various operating principles to fly minute droplets of ink and attach them to a recording medium such as paper to record images, characters, etc.
It has features such as low noise, easy multicolor printing, great flexibility in recording patterns, and no need for development or fixing, making it suitable for various uses as a recording device for various shapes and color images, including kanji. It is rapidly becoming popular. Furthermore, images formed using the multicolor inkjet method can produce records that are comparable to multicolor printing using the plate making method or printing using the color photographic method, making it suitable for applications that require fewer copies to be produced. Since it is cheaper than photographic technology, it is being widely applied to the field of full-color image recording.

(B) Prior art and the crisis point Efforts have been made in terms of equipment and ink composition to use high-quality paper or coated paper, which is used for ordinary printing and writing, as the recording medium used in this inkjet recording method. It's here. However, as the performance of inkjet recording apparatuses improves and their applications expand, such as higher speeds, higher definitions, and full-color inkjet recording apparatuses, more advanced characteristics are now required of recording media. In other words, the recording medium should have a high ink dot density, a bright and cedar-like color tone, and should absorb ink quickly so that the number of ink dots is 1.
The ink should not flow out or smudge even when the ink dots are damaged, the ink dots should not spread more than necessary, and the periphery should be smooth and not blurred. Furthermore, when the recorded image is exposed to ultraviolet rays, acid accumulation in the air, or water, the resistance of the dye should not be reduced, and the recording medium should not change color due to storage. It is required that there is no discoloration of the image.

In order to solve these problems, several proposals have been made in the past. 11e is JP-A-52-53012
The issue also describes an inkjet recording paper made by moistening a low-size base paper with a coating for surface treatment.
No. 49113 discloses an inkjet recording paper in which a sheet containing a urea-formalin resin powder bed is impregnated with a water-soluble polymer. Although these general paper type ink jet recording papers absorb ink quickly, they have the disadvantage that the periphery of dots tends to become blurred and the dot density is low.

Further, JP-A No. 55-5830 discloses an inkjet recording paper in which an ink-absorbing coating layer is provided on the surface of the support, and JP-A No. 55-51583 discloses a non-glue pigment as a pigment in the coating layer. An example using silica powder is disclosed, and furthermore, JP-A-55-11829 discloses an example of smear paper using a two-layer structure with different ink absorption speeds. These coated paper-type inkjet recording papers are improved over general paper-type inkjet papers in terms of dot diameter, dot shape, dot density, and color tone reproducibility, but they are not as good in terms of absorption capacity. There are many things that are missing. Therefore, if you increase the amount of coating to increase the absorption capacity, the dot diameter will become smaller, and the ink will sink deeper, causing the color to become less uniform, making it difficult to improve the absorption capacity alone. there were.

Therefore, the present inventor proposed a coat-type structure in which an ink-receiving layer containing a porous inorganic pigment is provided in JP-A No. 58-110287, which increases the absorption rate and has a large absorption valley. Porous inorganic pigments have a highly active surface and a high ability to absorb ink, but they also have the ability to adsorb various organic substances and microparticles that are diffused in the air.

At this time, it is possible that the adsorbed organic matter may react with the porous inorganic pigment or other non-additive materials in the ink-receiving layer, resulting in coloring or discoloration. It was found that the recording medium changed color. These recording papers are sometimes used with marks or ruled lines printed on the ink-receiving layer side, or marks are printed in flame color on the back side to make it easier to distinguish between the front and back sides. Printed recording paper tends to become a special type of recording paper during storage, and the recording paper sometimes becomes discolored, especially with light discoloration.

After intensive study on these discolorations, we found a combination with a printing ink that does not cause discoloration, and have completed the present invention.

(Objective of the invention, that is, the present invention is to print marks and/or ruled lines on the front and/or back sides of recording paper having an ink-receiving layer containing a porous inorganic pigment by using printing ink with a normal printing device. A method for producing recording paper, characterized in that the printing ink does not contain a lipophilic vehicle, that is, marks, ruled lines, etc. are printed using water-based printing ink. It is not certain whether the use of water-based printing ink will not cause discoloration of the recording medium, but as mentioned above, porous inorganic pigments have high surface activity and have the ability to adsorb organic substances to their surfaces.In that case, It is conceivable that the concentration of various adsorbed substances on the pigment surface is high, and that the catalytic action of the pigment surface itself is also involved, causing a phenomenon in which the adsorbed organic matter becomes discolored. sexless f
A recording paper having an ink-receiving layer containing fl pigment is
When it comes into contact with the lipophilic vehicle in oil-based ink or the organic solvent remaining in the adhesive of adhesive tape manufactured using oil-based or solvent, directly or through a transparent film, etc.
It is thought that a phenomenon of discoloration occurs.

The ordinary printing apparatus referred to in the present invention includes, for example, a letterpress, an intaglio, a lithography, a stencil, etc. when classified by plate type.

Letterpress-related printing includes letterpress printing, flexographic printing, primary color printing, etc., and intaglio-related printing includes engraving intaglio printing, gravure printing, etc.
A typical example of lithographic printing is offset printing, while stencil printing includes toshihan printing, and others include collotype printing.

In the present invention, normal printing ink refers to ink used in the various printing methods mentioned above, but for example, in classification by drying type, quick set ink, heat set ink,
Moisture set ink, cold set ink, U
V ink, IR ink, 1B ink, etc. can be considered. Further, in classification according to vehicle composition, inks are divided into oil inks, solvent inks, and water-based inks. In the present invention, inks that do not contain a parent vehicle refer to water-based inks among these classifications.

Water-based printing inks generally consist of the following components.

Starch, dextrin, alginates, cellulose esters, cellulose ethers, polyvinyl alcohol, polyvinyl methyl ether, polyacrylamide, polyethylene oxytone, water-soluble resins such as natural or synthetic additives such as polyacrylates, shellac, styrenated shellac, styrene Maleic acid resin, rosin maleic acid resin, casein and its derivatives, colloidal disbarge coating or water bathing resin such as acrylic copolymer, and acrylic resin,
Vinyl acetate resin, styrene resin, vinyl chloride resin, 8BR, NBR, etc., and emulsions such as polyurethane and polyester, as well as water solubilizers such as ammonia water, pigments and/or dyes, co-solvents such as alcohols, etc. If necessary, foaming agents, anti-friction agents, anti-mold agents, 0T hardeners, rust inhibitors, etc. are added. Printing inks other than water-based printing inks contain vegetable oil, mineral oil, and oil-extinguishing fat as vehicles, and also contain lipophilic solvents such as hydrocarbons and esters. The pigment is dispersed in an aqueous vehicle consisting mainly of water, an aqueous resin, and an alcohol.

The ink-receiving layer referred to in the present invention refers to a layered coating layer having an ink-absorbing ability, which is composed of a porous inorganic pigment and, if necessary, other pore-constituting materials and an adhesive on a suitable support. The porous inorganic pigment mentioned above is a dry powder made by aggregating primary particles of synthetic silica or synthetic alumina and having an average secondary particle size of 0.5 μm to 30 μm.These synthetic silica or synthetic alumina are water-soluble. When synthesized from aqueous raw materials in an aqueous solution, the secondary particles have a size of several microns to several hundred microns and have self-cohesive properties, so
A porous inorganic pigment can be obtained by drying, then pulverizing and classifying, or by adjusting the particle size to the desired size using a spray dryer or the like during drying.

In addition, if synthetic silica or synthetic alumina is a fine powder of 1 μm or less, it can be dispersed in water, added with a binder or adhesive, dried, crushed, and classified, or dried with a spray dryer. By spray drying, it is also possible to obtain a porous inorganic pigment having an average secondary particle diameter of 0.5 μm to 30 μm.

Furthermore, in order to form fine water-dispersed substances such as colloidal silica and colloidal alumina into particles of 0.5 μm or more, it is necessary to use a fine particle suspension as disclosed in No. 1, Ty, S, p-3,855,172. By producing a urea-formalin resin or the like in turbid water and adjusting the production conditions, a porous inorganic pigment granulated to a desired secondary particle size can be obtained.

In the present invention, the above porous inorganic pigment can also be used in combination with the following inorganic or organic pigments. In this case, the porous inorganic pigment is 20% by weight or more of the total pigment, preferably 4ON
Use % or more. Examples of inorganic pigments that can be used in combination include light calcium carbonate, heavy calcium carbonate, and kaolin (
white clay), talc, calcium sulfate, barium sulfate, titanium oxide, lead oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, aluminum hydroxide , alumina, lithopone, and other white pigments and organic pigments include styrene plastic pigments, acrylic plastic pigments, microcapsules,
There are urea resin pigments, etc.

In order to form an ink-receiving layer by coating these pigments on a support, an adhesive is required to adhere the void-forming material to the support. Examples of adhesives include oxidized starch, etherified starch, cellulose fat conductors such as carboxymethylcellulose and hydroxyethylcellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its derivatives, maleic anhydride resin, and ordinary styrene-butadiene. Copolymers, conjugated diene monomer latexes such as methyl methacrylate-butadiene copolymers, acrylic polymer latexes such as polymers or copolymers of acrylic esters and methacrylic esters, ethylene vinyl acetate copolymers, etc. Water-based adhesives such as vinyl polymer latex, functional group-modified polymer latex using monomers containing functional groups such as carboxyl groups, and thermosetting synthetic resins such as melamine resin and urea resin. , and polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer,
Synthetic resin adhesives such as polyvinyl butyral and alkyd resins can be used alone or in combination. These adhesives are used in an amount of 2 to 100 parts, preferably 5 to 30 parts, per 100 parts of the pigment, but the ratio is not particularly limited as long as the child is skilled in binding the pigment. . However, if 100 parts or more of adhesive is used, the pore structure is reduced or the pores are made extremely small due to film formation of the adhesive, which is not preferable.

In addition, when the ink used is a water-based ink, it is preferable that the image does not wash away in water after being formed on the ink-receiving layer. Surfactants, cation-modified inorganic particles, etc. can also be added.

In addition, if necessary, pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, mold release agents, foaming agents, penetrants, color dyes, layer color fillers, fluorescent whitening agents, ultraviolet rays. Absorbents, antioxidants, preservatives, anti-spill agents, waterproofing agents, etc. can also be blended as appropriate.

As the support, a sheet material such as paper or thermoplastic resin film is used. In the case of paper, it is paper with no sizing agent added or with appropriate sizing, and may or may not contain filler. Good too.

In addition, in the case of thermoplastic films, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate,
A transparent film made of cellulose acetate, polyethylene, polycarbonate, etc., or a white opaque film filled with white pigment or made by fine foaming is used. Examples of white pigments to be filled include titanium oxide, calcium sulfate,
Calcium carbonate, silica, clay, talc, lead oxide, and many others are used.

It is also possible to use so-called laminated paper, which is obtained by pasting these resin films on the surface of paper or by processing it with molten resin. The surface of these resins and the ink receiving layer may be subjected to undercoat or corona discharge machining to form several liquid reservoirs.

When forming an ink-receiving layer on these supports by coating a pigment coating liquid, etc., a blade coater, an air knife coater, a roll coater-1 brush island coater, or a curtain coater, which are generally used as coating machines, can be used. ,
Bar coaters, gravure coaters, and spray equipment are commonly used.

Furthermore, when the support is paper, it is also possible to apply a size press on a paper machine, a gate roll, a spray, 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 be heated with a super calender, cross calender, etc. and/or passed between roll nips under pressure to improve the surface smoothness. In this case, excessive processing by supercalendering will reduce the g! The degree of processing may be limited because the ink absorption due to the gaps will be reduced.

Measurements of various physical property values used in the present invention were carried out in the following manner.
cyan (0), magenta (ro) using
, yellow (Y), and black (B)), the density was measured using a Macbeth densitometer RD514.

The dot diameter is determined by measuring the area of a single dot in the black ink area of the same inkjet printer using a dot area meter, converting it to the area assuming a perfect circle, and calculating the i! The value calculated as the diameter was used. In addition, the ink absorption speed is determined by using the same color image printer and contacting the paper presser roll immediately after peta printing (about 1 second) with red printing (mc magenta + yellow).
Judgment was made based on whether dirt appeared or not. Furthermore, the ink absorption ability was determined by the degree of bleeding at the boundary of the solid printed area using the same inkjet printer.

Printing discoloration was determined by the degree of yellowing of the ink-receiving layer when flexographic printing was performed on the back side of recording paper using various inks and the paper was stored in a cardboard box for one month.

(H) Examples Examples of the present invention will be described below, but the invention is not limited to these examples. Incidentally, parts and percentages shown in the examples mean xi parts and weight percentages.

Example I F water layer 370 shoulder 1 LBKP 80 parts of esf, reactor water level 4
From a slurry consisting of 20 parts of 00 agent NRKP, 13 parts of heavy calcium carbonate, 1 part of cationic starch, 0.12 parts of an alkyl ketene dimer sizing agent, and 0.4 parts of polyalkylene polyamine epichlorohydrin resin, the basis weight was determined using a Fourdrinier paper machine. A coated base paper was produced by making a 6B17 m'' base paper, and adhering 15117 m' of oxidized starch using a size press during paper making.

As a porous inorganic pigment, synthetic silica (Syroid 74, manufactured by Fuji Davison) with an average secondary particle diameter of 7 μm, which is a micron-sized xerogel obtained by gelation of silicic acid, and polyvinyl alcohol (Kuraray) as an adhesive. A coating liquid consisting of 30 parts of PVA117) manufactured by Co., Ltd. was prepared.This coating liquid was coated on the coated base paper with an air knife coater to a dry solid content of 18 g/g.Next, the nip pressure was 50 using a super calender. 9/l
'I+! A recording paper was prepared by passing the paper through 4 nips at a speed of 40-7 m.

The recording paper of Example 1 was prepared by printing a mark on the back side of this recording paper by flexographic printing using water-based letterpress chart paper ink (gray color) diluted with alcohol and water.

As a result of evaluating this recording paper, its inkjet suitability was good and there were no political changes. Comparative Example 1 For printing on the back side of the recording paper used in Example 1, oil-based ink for letterpress chart paper (gray color) was used as an auxiliary agent, and it was placed on a stand. A recording paper of Comparative Example 1 was obtained by diluting the paper with oil and resiner (mineral oil) and printing marks by flexographic printing.

As a result of evaluation of this recording paper, its inkjet suitability was the same as in Example 1, but it was observed that the ink-receiving layer in the area where the mark was printed had turned dark brown.

Comparative Example 2 Commercially available single-sided art paper (pigments are kaolin and heavy charcoal)
The same printing as in Comparative Example 1 was carried out on the back side of the paper to obtain a recording sheet of Comparative Example 2. As a result of evaluation of this recording paper, it was found that absorbency was completely poor among inkjet suitability, but no discoloration of the coating layer was observed.

(F) Effects of the invention

Claims (1)

[Claims] In a method of printing marks and/or ruled lines on the front and/or back sides of recording paper having an ink-receiving layer using printing ink using a normal printing device, the ink-receiving layer contains a porous inorganic pigment. , and the printing ink is an ink that does not contain a lipophilic vehicle.