JPH06320857A - Cast-coated paper for ink jet recording and production thereof - Google Patents

Abstract

PURPOSE:To obtain cast-coated paper having excellent blank surface gloss and excellent ink jet recording aptitude (printability). CONSTITUTION:A coated layer based on pigment and an adhesive is provided on base paper and the coated base paper is subjected to cast finish in a wet state to obtain cast-coated paper. The cast-coated paper for ink jet recording has a coated layer containing vinyl acetate latex and a cationic resin and is produced by providing a wet coated layer based on pigment and an adhesive on a support. After the coated supports is once dried, it is again wetted to be brought into contact with the mirror surface of a heating drum under pressure and released from the drum to be finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast coated paper for ink jet recording, and particularly to a cast coated paper having an excellent white paper surface gloss and excellent ink jet recording (printing) suitability and a method for producing the same. Regarding

[0002]

2. Description of the Related Art In recent years, recording by an ink jet printer has been used in many fields because of its low noise, high-speed recording, and easy multicoloring. As the paper used for ink jet recording, there are used high-quality paper designed to be highly ink-absorbent and coated paper with a porous pigment coated on the surface of the base paper. It is a so-called matte ink jet recording paper having a low level. However, recently, with the expansion of applications such as high-speed, high-definition, full-color inkjet recording, there has been a demand for an inkjet recording paper having excellent surface smoothness and high surface gloss and having excellent appearance suitability. .

Generally, as a paper having a high surface gloss, a paper coated with a plate-like pigment on the surface and, if necessary, calendered, or a wet coating layer on a heating drum surface having a mirror surface is used. Cast coated paper obtained by copying its mirror surface by pressure bonding, drying, release, or varnished paper or press coat in which a transparent resin is coated on the coated paper or the surface of the cast coated paper by printing, etc. Examples include paper and laminated paper in which a plastic film such as polyethylene or vinyl chloride is attached to the surface.

By the way, among these, varnished paper, press-coated paper, laminated paper and the like have a property that their surface is covered with a film formed or has a property close to that. Therefore, there are many drawbacks in terms of process complexity and cost push when manufacturing these papers, reusability as waste paper, and environmental protection. There are many disadvantages compared to the coated paper.

According to the present invention, the cast coated paper is used as an ink jet recording paper based on the above situation, but the conventional cast coated paper has various problems as an ink jet recording paper. It was unsuitable. In the following, with respect to cast coated paper, its manufacturing method and problems in using it as an inkjet recording paper will be described.

First, as a method for producing cast coated paper, the following three typical methods are described: (1) After coating a base paper with a pigment composition containing a pigment and an adhesive as main components,
Wet casting method in which the coating layer in a wet state is pressed onto the surface of a heating drum that has been mirror-finished (press contact) and dried to give a gloss finish. (2) The coating layer in a wet state is once dried and then re-coated. Rewet cast method of wet plasticizing with a wetting liquid, press contacting to a mirror-finished heating drum surface, drying and gloss finishing, (3) Making a wet coating layer into a gel state, press-contacting it on a heating drum surface, and drying. Three methods are generally known, namely, a gel cast method of finishing with gloss.

All of these casting finishing methods are common in that the surface of the coating layer in the wet plasticized state is pressed against a heating drum having a mirror surface, dried, and released from the drum surface to copy the mirror surface. Those skilled in the art recognize these as separate technologies. The cast coated paper thus obtained has a more excellent surface gloss and surface smoothness as compared with the ordinary coated paper that has been subjected to a super calender finish, and since an excellent printing effect is obtained,
It is exclusively used for high-quality printed matter.

[0008] In general, cast coated paper has a high gloss because a film-forming substance such as an adhesive in the pigment composition constituting the coated layer copies the mirror drum surface of the cast coater. On the other hand, the presence of the film-forming substance tends to cause the coating layer to lose its porosity, and when it is used as an inkjet recording sheet in this state, the ink absorbability during inkjet recording is extremely reduced, and There is a problem that fixing is insufficient and stable image formation cannot be performed.

Therefore, in order to add aptitude as an ink jet recording paper, it is important to prevent the ink absorption from decreasing and to make the cast coating layer porous so that the ink can easily absorb the ink. One way to do this is to reduce the amount of film-forming substances, but by reducing the amount of film-forming substances, an effect of improving ink absorption is recognized, but on the other hand, the glossiness of white paper decreases. Not preferable.

On the other hand, as an ink jet recording paper, it has been proposed to add a cationic resin to a coating layer as a conventionally known technique in order to enhance the color developability (ink density) of the ink. If a cationic resin is added to the cast paint, the viscosity of the paint increases significantly, which is a problem in operation. Therefore, in order to suppress thickening and obtain a coating that is stable in operation, it is necessary to limit the amount of the cationic resin added. As a result, a desired sufficient ink color density cannot be obtained.

From the above, when the conventional cast coated paper is applied as an ink jet recording paper, it is extremely difficult to satisfy both the surface gloss peculiar to the cast coated paper and the suitability for ink jet recording (printing) at the same time. The current situation.

[0012]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied to obtain a cast coated paper which maintains the original high gloss and surface smoothness of the cast coated paper and is excellent in ink jet recording (printing) suitability. Layered. As a result, by using a vinyl acetate latex as an adhesive which is a constituent of the cast coating layer, the absorbability of the ink for inkjet recording is enhanced, and when a cationic resin is used in combination, the above conflicts. For the first time, they have found that the problems can be solved and the desired excellent effects can be obtained.

That is, it is possible to suppress an increase in paint viscosity, which was a problem in the case of the conventional cast coated paper, and to perform a stable operation, and to obtain the original high gloss and high surface smoothness of the cast coated paper. Provided is a cast coated paper which is maintained and has extremely excellent suitability for ink jet printing recording, and a method for producing the same.

[0014]

SUMMARY OF THE INVENTION The present invention provides a cast coating obtained by providing a base paper with a coating layer containing a pigment and an adhesive as main components and performing a cast finish while the coating layer is in a wet state. A paper, which is a cast coated paper for inkjet recording characterized by containing a vinyl acetate latex and a cationic resin in a coating layer, and the cast coated paper for inkjet recording by a rewet cast method. Is the way.

[0015]

The present inventors have made extensive studies to solve the above-mentioned drawbacks of the conventional cast coated paper in order to use the cast coated paper as the ink jet recording paper, and as a result, the cast coated layer was obtained. It was found that the use of a specific material as the component of (1) provides the excellent effects desired by the present invention.

That is, when a polyvinyl acetate polymer is used as an adhesive component of the cast coating layer, the ink absorbability is improved, and by using a cationic resin together, both high gloss and ink jet recording suitability are provided. The inventors have found that a cast coated paper can be obtained, and completed the present invention. The present invention will be described in detail below.

First, the present invention relates to a cast-coated paper which is cast-finished by pressing, drying and releasing a heating drum having a mirror surface while the coating layer is in a wet state. Among the above-mentioned casting methods, any of the wet casting method, the gelling casting method and the rewetting casting method can be used as the method for producing the paper. However, among these methods, the rewet casting method, compared with other casting methods, plasticizes only the coating layer of the very surface layer, and keeps the entire coating layer porous for the method of cast finishing. This is a preferred embodiment because it is possible to obtain better inkjet recording suitability.

A feature of the invention is to achieve the desired objective by incorporating specific materials in the cast coating. That is, the desired effect is obtained by using a vinyl acetate latex and a cationic resin as the adhesive. The vinyl acetate-based latex in this case has a stronger hydrophilicity and is more inkjet than other synthetic latexes such as conventional styrene-butadiene copolymer latex, methylmethacrylate-butadiene copolymer latex and styrene-acrylic acid resin. It has the property of easily absorbing the ink. Furthermore, it has been found that even if a cationic resin is added to a coating, it does not thicken the coating because it has excellent compatibility with the cationic resin, so that it can be used freely.

Specific examples of the above vinyl acetate latex include vinyl acetate polymer latex, vinyl acetate-ethylene copolymer latex, vinyl acetate-
Examples thereof include acrylic acid copolymer latex and vinyl acetate-maleic acid ester copolymer latex. The amount of the vinyl acetate-based latex used is adjusted in the range of 5 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the pigment. Of course, in addition to the vinyl acetate-based latex, proteins such as casein, soybean protein and synthetic protein, starches such as starch and oxidized starch, and cellulose derivatives such as polyvinyl alcohol, carboxymethyl cellulose and methyl cellulose are appropriately used.

Incidentally, synthetic resin latexes such as styrene-butadiene copolymer latex, methylmethacrylate-butadiene copolymer latex, styrene-acrylic acid resin, acrylic acid emulsion, etc., which have been conventionally used for coated paper, are generally cations. There is a concern that the viscosity of the coating composition may be increased by using it in combination with a water-soluble resin, and it is not preferable to use it in combination. However, a small amount, for example, about 1 to 5 parts by weight can be used together for the purpose of improving the water resistance of the coated layer.

Next, another specific material, a cationic resin, will be described. In the conventional inkjet paper, a cationic resin has been usually added to the coating layer for the purpose of improving water resistance. On the other hand, in the casting method, adding a cationic resin to a cast paint increases the viscosity of the paint, making it difficult to add a cationic resin sufficient to obtain the desired effect.

On the other hand, the cationic resin has a function of fixing the dye component in the ink used for ink jet recording, and the color density can be increased by distributing the dye as much as possible on the paper surface. In the present invention, by using a cationic resin in combination with a vinyl acetate-based latex, it becomes possible to add a larger amount of the cationic resin to the coating material, which makes it possible to increase the ink density, and to complete the present invention. I arrived.

As the cationic resin in this case, for example, a conventionally known monomer, oligomer or polymer which disintegrates and exhibits a cationic property when dissolved in water can be appropriately used, more preferably a tertiary amino group or Fourth
Those having a quaternary ammonium group, and more preferably, a copolymer of an acrylic resin having a quaternary ammonium group, a diacrylamine, or (meth) acrylamide with a vinyl monomer which does not contain a carboxyl group and is copolymerizable therewith. . The amount of these cationic resins used in the coating composition is adjusted in the range of 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the pigment.

As the pigment for the cast coating layer,
For example, kaolin, clay, calcined clay, amorphous silica,
Zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, aluminum silicate, magnesium silicate,
Various publicly known and publicly used pigments conventionally used in the coated paper manufacturing field such as satin white, magnesium carbonate, diatomaceous earth, styrene plastic pigment, urea resin plastic pigment, and benzoguanamine plastic pigment can be used.

Further, various auxiliaries are appropriately added to the paint so that the cast coating (operability) can be smoothly carried out. For example, a release agent is added as necessary so that the coating layer can be released from the cast drum smoothly. Examples of such a releasing agent include fatty acids such as stearic acid, oleic acid and palmitic acid and salts thereof such as calcium, zinc, sodium and ammonium, stearic acid amide, ethylenebisstearic acid amide and methylenebisstearic acid amide. , Hydrocarbons such as microcrystalline wax, paraffin wax and polyethylene emulsion, higher alcohols such as cetyl alcohol and stearyl alcohol, oils and fats such as funnel oil and lecithin, and various surfactants such as fluorine-containing surfactants Examples thereof include fluoropolymers such as tetrafluoroethylene polymer and ethylene-tetrafluoroethylene polymer.

For the purpose of making the coating layer more porous (porous), it is desirable to add at least one metal salt of aluminum, zinc, calcium, magnesium or the like to the coating liquid. Specific examples of such metal salts include chlorides such as zinc chloride and magnesium chloride, and sulfates such as zinc sulfate, magnesium sulfate and calcium sulfate. Other examples include organic acid salts such as formates and acetates, and these auxiliary agents are generally pigment 1
It is adjusted in the range of 0.2 to 10 parts by weight with respect to 00 parts by weight.

Further, when a general coated paper or cast coated paper is manufactured, a dispersant, a defoaming agent, a coloring agent, a fluorescent dye, an antistatic agent, an antiseptic agent or the like used in a coating liquid is used. Various auxiliaries can be added as appropriate.

The cast coating composition (paint) composed of the above-mentioned materials is generally prepared in the same manner as in the case of ordinary coated paper production so that the solid content concentration is about 1 to 65% by weight. It is prepared by the method, and the weight of the rice is about 35 to 400 g /
0.1 to 50 g / m ² dry weight on various supports such as about m ² of base paper, art paper, coated paper, print coated paper such as cast coated paper and slightly coated paper, and porous film More preferably, the coating is applied so that the amount is about 0.5 to 10 g / m ² , and then cast finish.

The base paper for cast coated paper is not particularly limited, and acid paper or neutral paper generally used in the field of cast coated paper is applied. Needless to say, various pigment coating compositions may be pre-coated on one or both sides of the base paper, if necessary, and the coating amount in this case is 5 to 3 dry weight per one side.
About 0 g / m ² is desirable. Further, if necessary, this pre-coated paper may be subjected to smoothing treatment such as super calendering, brushing and cast finishing in advance.

In the production method of the present invention, various known compositions such as a blade coater, an air knife coater, a roll coater, a brush coater, a chanplex coater, a bar coater and a gravure coater are used as the above-mentioned composition for cast coating layer. The above-mentioned various supports are coated by a coating device and cast-finished by any of the above three casting methods. However, as described above, the rewet cast method is more preferable.

[0031]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and% are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 70 parts of precipitated calcium carbonate and 20 kaolin as pigments
Parts and 10 parts of amorphous silica, casein 1 as an adhesive
Each of 0 parts and 10 parts of polyvinyl acetate, 8 parts of a quaternary ammonium salt-containing acrylic resin as a cationic resin, 0.5 parts of calcium stearate as a release agent, and 0.2 parts of tributyl phosphate as a defoaming agent. The materials were mixed and stirred in water to prepare an aqueous coating material for cast coating layer having a solid content concentration of 45%. 70 g / m2 of this paint
As the dry weight on the ^second quality base paper is 25 g / m ^2, coated with an air knife coater, dried, as rewetting solution containing 1% stearate emulsion in rewetting solution having a solid concentration of 9% Re-wet, immediately surface temperature 100
After pressure contact with a mirror-finished drum having a diameter of 3000 mm and a temperature of 3000 ° C. and drying, the cast-coated paper was obtained by releasing from the mirror-finished drum.

Example 2 60 parts of amorphous silica and 40 parts of light calcium carbonate as a pigment, 30 parts of casein and 30 parts of polyvinyl acetate as an adhesive, 5 parts of a quaternary ammonium salt-containing acrylic resin as a cationic resin, and mold release 0.5 parts of ammonium oleate as an agent and 0.5 parts of tributyl phosphate as an antifoaming agent were mixed and stirred in water to prepare an aqueous paint for cast coating layer having a solid content concentration of 40%. . A cast coated paper was obtained in the same manner as in Example 1 except that this coating material was used.

Example 3 70 parts of precipitated calcium carbonate and 20 kaolin as pigments
Parts and 10 parts of amorphous silica, casein 1 as an adhesive
0 parts and ethylene-vinyl acetate copolymer latex 1
0 part, 4 parts of zinc sulfate as a metal salt, 5 parts of a quaternary ammonium salt-containing acrylic resin as a cationic resin, 0.5 part of ammonium oleate as a release agent, and 0.3 part of tributyl phosphate as a defoaming agent. Each of the above materials was mixed and stirred in water to prepare an aqueous coating material for cast coating layer having a solid content concentration of 48%. A cast coated paper was obtained in the same manner as in Example 1 except that this coating material was used.

Example 4 70 parts of precipitated calcium carbonate as pigment, 20 kaolin
Parts, and 10 parts of amorphous silica, casein as an adhesive
With 10 parts and 15 parts of polyvinyl acetate, cationic resin
Then dimethyl diallyl ammonium chloride and acryl
Lamide copolymer 5 parts, stearic acid as a release agent
0.5 parts of lucium and tributylphosphate as an antifoaming agent
Mix and stir each material consisting of 0.2 parts of sulfate in water
Then, prepare a water-based paint for cast coating layer with a solid content concentration of 55%.
I made it. 60g / m2 of this paint ²Dry on high quality base paper
Dry weight is 20g / m²With a roll coater
Immediately after coating, the mirror has a surface temperature of 80 ° C and a diameter of 3000 mm.
After pressure contact with the surface drum, drying, and release, a cast coated paper is obtained.
It was

Comparative Example 1 50 parts of precipitated calcium carbonate and 50 parts of kaolin as pigments, 10 parts of casein and styrene as adhesives
15 parts of butadiene copolymer latex, 0.5 part of calcium stearate as a release agent, and 0.2 part of tributyl phosphate as an antifoaming agent were mixed and stirred in water, and cast coating with a solid content concentration of 55%. A water-based coating material for layers was prepared. Example 1 except that this paint was used
A cast coated paper was obtained in the same manner as.

Comparative Example 2 A cast coated paper was obtained in the same manner as in Example 1 except that styrene-butadiene copolymer latex was used instead of polyvinyl acetate.

Comparative Example 3 A cast coated paper was obtained in the same manner as in Example 1 except that the cationic resin in the paint was not added.

Comparative Example 4 Cast coating was carried out in the same manner as in Example 4 except that 15 parts of styrene-butadiene copolymer latex was used in place of polyvinyl acetate and no cationic resin was added. Got the paper.

The cast coated paper thus obtained had a white gloss, an ink jet printer recording aptitude (ink drying property,
The ink density) and the results of the workability of the coated paper are shown in Table 1.

The above evaluation was carried out by the following method.

[Glossiness of blank sheet] The glossiness was measured according to JIS-P8142.

[Recordability of Inkjet Printer] (Ink Dryability) Printing was performed with Color Image Jet IO-735X manufactured by Sharp Corporation, and the dryness of the ink was visually evaluated. ⊚: No stain at all when touched with a finger immediately after printing. ◯: Slightly soiled when touched with a finger immediately after printing, but almost dry. Δ: The ink portion is slightly shiny immediately after printing, but there is no problem in practical use. X: Ink cannot be satisfactorily recorded due to poor drying of ink during printing.

(Ink Color Density) Printing was performed with a color image jet IO-735X manufactured by Sharp Corporation, and the ink density was visually evaluated. ◯: Good color density. Δ: The concentration is slightly low, but there is no practical problem. X: The density is low and the sharpness is poor.

[Operability during production of cast coated paper] ○: Continuous operation was possible without problems. ×: Due to thickening of the paint, satisfactory operation could not be performed.

[0046]

[Table 1]

[0047]

As is clear from the results shown in Table 1, the cast coated paper of the present invention was excellent in surface gloss and suitability for ink jet printer printing and recording, and could be efficiently produced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Nojima 4-3-1 Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill

Claims (2)

[Claims] 1. A cast coated paper obtained by forming a coating layer comprising a pigment and an adhesive as a main component on a base paper and performing a cast finish while the coating layer is in a wet state. A cast coated paper for inkjet recording, characterized in that the layer contains a vinyl acetate-based latex and a cationic resin. 2. A method for producing a cast coated paper for ink jet recording according to claim 1, wherein the coating layer is once dried, then re-wetted and pressed onto the heated mirror surface drum surface and released to finish. Manufacturing method of paper.