JPH0911607A - Production of cast coated paper for ink jet recording - Google Patents

Abstract

PURPOSE: To suppress the generation of a cockling phenomenon, in a process bringing an ink receiving layer into contact with the surface of a heated mirror surface drum in a wet state under pressure to apply mirror surface gloss finish thereto, by allowing steam to act on the surface of raw paper in specific quantity after the peeling from the mirror surface drum. CONSTITUTION: In a process bringing an ink receiving layer into contact with the surface of a heated mirror surface drum in a wet state under pressure to apply mirror surface gloss finish thereto, steam is allowed to act on the surface of raw paper after the peeling from the mirror surface drum. At this time, the retention time from the point of time of the peeling from the surface of the mirror surface drum is set to 5sec or less and the quantity of applied steam is set to 0.1-1.2g per 1m<2> of paper in terms of water quantity. When water is applied to the surface of the raw paper at the press nip bringing the coating layer into contact with the surface of the mirror surface drum pressure, the coating quantity of water is 5-20g per 1m<2> of paper. By this constitution, a cockling phenomenon can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing cast coated paper for ink jet recording for the purpose of improving the cockling phenomenon (hereinafter sometimes referred to as cockling) during printing by an ink jet printer. Regarding

[0002]

2. Description of the Related Art An ink jet recording system is one in which minute droplets of ink are ejected by various operating principles to be fixed on a recording sheet such as paper to record images, characters, etc., at high speed, low noise, Since it has features such as easy multicoloring, great flexibility in recording patterns, and no need for development and fixing, it has rapidly spread in various applications as a recording method for various figures and color images including Chinese characters. . Especially,
Images formed by the multicolor ink jet method can obtain records that are comparable to those of multicolor printing by the plate making method or printing by the color photographic method. Since it is cheaper than the method using the inkjet recording method, the inkjet recording method has been widely applied to the field of full-color image recording in recent years.

A recording sheet used in this ink jet recording system has a high density of print dots, a bright and vivid image with a color tone is obtained, ink is absorbed quickly, and ink is printed even when print dots overlap each other. It is required that the printed dots do not flow out or bleed, the lateral spread of the print dots is not unnecessarily large, and that the periphery is smooth and does not blur.

On the other hand, as a recording medium having a higher surface gloss than before, cast coated paper having a surface with a high gloss finish is known. Then, a technique in which the technique of the cast coated paper is applied to a recording sheet used in an inkjet recording system is being put to practical use. Specifically, a recording sheet is known in which an ink receiving layer is laminated on a support and the surface of the ink receiving layer is cast.

Direct methods, gelling methods and rewet methods are conceivable as casting methods in the production of ink jet recording sheets using this cast coated paper method. Of these, the direct method is one in which the coating layer applied on the support is still in a wet state, and the coating layer is pressed against the heated mirror-finished drum surface to give a strong gloss finish. Further, the gelling method is a method in which the coating layer applied on the support is brought into contact with a gelling agent bath while the coating layer is still in a wet state, and the coating layer in the gel state is heated to a mirror surface. It has a high gloss finish by pressing it against the drum surface. Further, the rewetting method is a method in which a wet coating layer is once dried and then the coating layer is brought into contact with a rewetting liquid, and then the coating layer is brought into contact with a heating drum for a high gloss finish. is there.

Any of these casting methods can be used for the ink jet recording sheet of the present invention, but the direct method is particularly preferable for obtaining an ink jet recording sheet having high gloss. The surface roughness, surface temperature, diameter, pressure (line pressure) at the time of pressure contact, coating speed, etc. of the mirror-finished roll can be appropriately selected in the same manner as the production conditions of commercially available cast coated paper.

When the above gelling method is used,
Since the coating layer is relatively strong, the coating layer is not destroyed even when it is pressed against a drum heated to a temperature higher than the boiling point, and therefore the speed can be increased, but it is contained in the coating layer. It is necessary to transfer a large amount of water contained in the base paper layer, which is a support, while passing through the nip between the drum and the pressure roll. Otherwise, the moisture contained in the coating layer explosively boils after passing through the nip, so that the gloss developing layer separates from the drum surface and an inkjet paper having the desired gloss cannot be obtained. Therefore, even when this gelling method is used, the operating speed must be reduced, which is disadvantageous in terms of production efficiency. Moreover, there is a problem that the salt or acid used as the gelling agent remains in the coating layer, and the salt or acid reacts with the dye in the ink to deteriorate the color reproducibility.

In the prior art, for example, Japanese Patent Laid-Open No. 59-5.
9995 gazette is not a method for producing a cast coated paper for inkjet recording, but in the method for producing a cast coated paper by the rewet method, water is applied to the back surface of the paper by a press nip in which the coating layer is pressed against the drum surface. A method of making a cast coated paper to work is disclosed. However, the present invention aims to improve the reverse vertical curl (curl centered on the paper width direction with the strong gloss cast finish surface outside and the back surface inside).

Also, for example, Japanese Patent Laid-Open No. 60-94692 is not a method for producing cast coated paper for ink jet recording, but in the method for producing cast coated paper, after peeling from the drum, steam is applied to the cast coated layer surface. Disclosed is a method for producing a cast coated paper which causes the action of. However, this invention also aims to improve the reverse vertical curl.

Since a normal cast coated paper is a single-sided coated paper, as a countermeasure against curling, for example, the above-mentioned JP-A-59 is used.
The treatments described in JP-A-59995 and JP-A-60-94692 are performed. However, in ink jet recording cast coated paper,
Since it causes image unevenness and the like, it is not possible to take the usual measures against curling of cast coated paper.

[0011]

In the method for producing cast coated paper for ink jet recording, there is an improvement in cockling, which is a further important problem in addition to the above curl measures.

Cockling is a phenomenon in which water in ink passes through the image receiving layer and swells the base paper layer, causing waviness on the surface, and can be avoided by preventing ink permeation into the base paper. In addition, since the ink or the water in the ink is not absorbed, there are serious problems such as a decrease in the ink absorption capacity and an increase in image bleeding.

This cockling phenomenon becomes a particularly important problem in the method for producing cast coated paper for ink jet recording. That is, the cast coated paper for inkjet recording tends to have a slow ink absorption speed, and when cockling occurs, the printed surface immediately after printing is likely to come into contact with each part of the printer, and stains often occur. For this reason, it is necessary to take a stricter measure to prevent cockling than with ordinary inkjet recording paper.

As a countermeasure against cockling,
The thickness (coating amount) of the image receiving layer may be increased to prevent water in the ink from migrating to the base paper.
In the case of cast coated paper, the image receiving layer is pressed against the cast drum and dried, so that the coating amount becomes large, and two-layer coating and three-layer coating are performed.
When a layer coating is applied, vapor is hard to escape, drying becomes difficult, and production efficiency is significantly reduced. Moreover, in the manufacturing method of the cast coated paper for inkjet recording, an effective countermeasure against cockling has not yet been found.

Therefore, as a result of intensive studies by the present inventor, if a cast coated paper is produced under a specific condition, a cast coated paper for ink jet recording in which the cockling phenomenon is remarkably suppressed can be produced. The inventors have reached the present invention by finding out what can be done.

The present invention has been made under such circumstances, and according to the present invention, ink jet recording in which the occurrence of cockling phenomenon is remarkably suppressed by using a casting method such as a direct method and a rewet method. Although it is possible to provide a method for producing coated paper for direct use, the direct method is generally preferably used.

[0017]

In order to solve the above problems, in the first method for producing a cast coated paper for ink jet recording of the present invention, at least one ink receiving layer is provided on a support. In a coat type inkjet recording paper, the ink receiving layer is made to have a mirror gloss finish by being brought into pressure contact with a heated mirror surface drum surface while the ink receiving layer is in a wet state. Configured to act with steam,

The second method for producing a cast coated paper for ink jet recording of the present invention is a coat type ink jet recording paper in which at least one ink receiving layer is provided on a support, and the ink receiving layer is wet. While being in a state, it is made into a mirror gloss finish by being brought into pressure contact with a mirror surface drum heated, and after peeling from the mirror surface drum, when applying steam to the cast coating layer surface and the base paper surface,
The retention time from the time of peeling off the mirror surface is 5 seconds or less, and the amount of water vapor applied is 0.1 to 1.2 g per m ^{2 of} paper in terms of water amount,

The third method for producing a cast coated paper for ink jet recording of the present invention is a coat type ink jet recording paper in which at least one ink receiving layer is provided on a support, and the ink receiving layer is wet. While being in a state, it is made into a mirror gloss finish by being pressed against the mirror surface drum that is heated, and when applying water to the base paper surface of the paper at the press nip where the coating layer is pressed against the mirror surface. The present invention relates to a method for producing a cast coated paper for inkjet recording, wherein the coating amount of water is 5 to ²⁰ g per m ² of paper.

In any of the first, second and third methods for producing a cast coated paper for ink-jet recording of the present invention (hereinafter, may be abbreviated as any of the methods of the present invention), first, the support is used. At least one ink-receiving layer is coated on top.

In any of the methods of the present invention, a support that can be preferably used is, for example, LBKP or NBK.
Chemical pulp such as P; GP, PGW, RMP, TMP, C
Mechanical pulp such as TMP, CMP, CGP; wood pulp such as waste paper pulp such as DIP, and pigment as main components, binder, and further sizing agent, fixing agent, yield improving agent,
Mixing one or more kinds of various additives such as a cationizing agent and a paper strengthening agent, and using various devices such as a Fourdrinier paper machine, a cylinder paper machine, a twin wire paper machine, a base paper, starch,
Base paper provided with a size press or anchor coat layer using polyvinyl alcohol or the like, or coated paper such as art paper, coated paper, cast coated paper provided with a coat layer on the size press or anchor coat layer. And so on.

In any of the methods of the present invention, these base papers or coated papers may be used as they are, or they may be calendered using an apparatus such as a machine calender, a TG calender or a soft calender and flattened. You may use it in the state which controlled conversion.

The basis weight of the support is usually 40 to 300 g / m ²
The degree is not particularly limited.

In any of the methods of the present invention, at least one ink receiving layer, and more preferably a gloss developing layer is applied in this order on the support as described above.

The ink receiving layer is composed of a coating composition containing a pigment and a binder as main components, and at least one layer is coated on a support.

A white pigment can be preferably used as the pigment. Examples of such white pigments include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, Diatomaceous earth,
Inorganic pigments such as calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, hydrohaloysite, magnesium hydroxide; styrene plastic pigment, acrylic plastic Pigment, polyethylene, microcapsules, urea resins, melamine resins and other organic pigments.

Examples of the binder include starch derivatives such as oxidized starch, etherified starch and phosphoric acid esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol or derivatives thereof; Polyvinyl alcohol with various degrees of saponification or silanol modified products thereof, various derivatives such as carboxylated compounds and cationized compounds; polyvinylpyrrolidone, maleic anhydride resins,
Conjugated diene copolymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer; acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester;
Vinyl-based polymer latexes such as ethylene-vinyl acetate copolymers; or functional group-modified polymer latexes with monomers containing functional groups such as carboxy groups of these various polymers; thermosetting synthesis of melamine resins, urea resins, etc. Water-based adhesive such as resin; acrylic such as polymethylmethacrylate; acid ester; polymer or copolymer resin of methacrylic acid ester;
Examples thereof include polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin, and other synthetic resin adhesives.

The mixing ratio of the pigment and the binder in the coating composition constituting the ink receiving layer is 3 to 70 parts by weight, preferably 5 to 5 parts by weight of the binder with respect to 100 parts by weight of the pigment.
50 parts by weight. When the compounding ratio of the binder is less than 3 parts by weight with respect to 100 parts by weight of the pigment, the coating strength of the ink receiving layer made of such a coating composition may be insufficient. On the other hand, if the mixing ratio exceeds 70 parts by weight,
The ink absorbability of the ink receiving layer made of such a coating composition may decrease.

Further, in the ink receiving layer, for example, a dye fixing agent, a pigment dispersant, a thickener, a fluidity improving agent, a defoaming agent,
Foam suppressor, release agent, foaming agent, penetrant, coloring dye, coloring pigment, fluorescent whitening agent, ultraviolet absorber, antioxidant, preservative,
Various additives such as a mildewproofing agent, a water resistant agent, a wet paper strength enhancer, and a dry paper strength enhancer can be appropriately blended. Especially,
A cation consisting of a secondary amine, a tertiary amine, and a quaternary ammonium salt that forms an insoluble salt with a sulfonic acid group, a carboxyl group, an amino group, etc. in a water-soluble direct dye or a water-soluble acidic dye which is a dye component of an aqueous ink. When a water-soluble dye fixing agent is added, the dye is captured in the ink receiving layer, so that the color is improved and an insoluble salt is formed, which causes the ink to flow out when water is dropped or when moisture is absorbed. Bleeding is suppressed.

The coating amount of the ink receiving layer cannot be generally stated because it varies depending on the required gloss, ink absorbency, kind of support, etc., but it is usually 1 g / m ² or more. Further, the ink receiving layer may be applied by dividing a certain fixed amount of coating twice. When the coating is performed twice, the gloss is improved as compared with the case where the same coating amount is applied once.

Coating of the ink receiving layer can be carried out by various machines such as various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters and size presses on machine or off machine. Can be done using. After the ink receiving layer is applied, the ink receiving layer may be flattened by using a calendering machine such as a machine calendar, a TG calendar, and a soft calendar.

The number of ink receiving layers can be appropriately determined as needed. In any of the methods of the present invention, the gloss-developing layer coated on the ink-receiving layer as a more preferred embodiment is composed of a coating composition containing a pigment and a binder as main components.

Examples of the pigment contained in the gloss-developing layer include the same pigments as those contained in the ink-receiving layer.

In any of the methods of the present invention, the binder contained in the glossy layer provided as a more preferable embodiment is, for example, casein, gelatin, soybean protein, etherified starch, phosphoric esterified starch and the like. Starch derivatives; natural polymers such as carboxyl derivatives such as carboxyl cellulose and hydroxyethyl cellulose, derivatives thereof, and polyvinyl alcohols having various degrees of saponification or derivatives thereof such as silanol modified products, carboxyl modified products, cation modified products; polyethylene oxide, polyethylene glycol. , Polyacrylamide, polyvinylpyrrolidone, melamine resins, urea resins, polyurea polyamide resins and other water-soluble synthetic polymers and their derivatives such as carboxyl modified products, amide modified products and cation modified products;
In addition, synthetic polymer emulsions such as styrene-butadiene type, acrylic acid ester and methacrylic acid ester type, ethylene vinyl acetate type, polyurethane type, etc., modified derivatives such as latex and its carboxyl, amide, cation modified products based on various amine groups, etc. Can be mentioned.

The binder content in the gloss-developing layer is usually 5 to 70 parts by weight, based on 100 parts by weight of the pigment.
Preferably it is 5 to 50 parts by weight. When the compounding ratio of the binder to the pigment 100 parts by weight is less than 5 parts by weight,
The coating strength of the gloss development layer may be insufficient. On the other hand, if the above-mentioned mixing ratio exceeds 70 parts by weight, the ink absorbency may be deteriorated and good image quality may not be obtained.

For coating the glossy layer, for example, various blade coaters, roll coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters,
Various devices such as a size press can be used.

The coating amount of the gloss-developing layer varies depending on the smoothness and size of the ink receiving layer, the required smoothness, and the like, so it is difficult to unconditionally determine, but usually 2 g /
m ² or more is sufficient. Further, calendar processing using a machine calendar, a TG calendar, a super calendar, a soft calendar or the like may be performed.

In any of the methods of the present invention, the ink receiving layer and the gloss developing layer provided as a more preferred embodiment of the present invention are dried. Drying of the ink receiving layer and the gloss-developing layer may be carried out according to a conventional method using various drying devices such as a hot air dryer, an air foil dryer, an air cap dryer, a cylinder dryer and an infrared dryer.

The first method for producing a cast coated paper for ink jet recording of the present invention is a coat type ink jet recording paper in which at least one ink receiving layer is provided on a support, and the ink receiving layer is wet. A cast coating for ink jet recording, characterized in that it is brought into pressure-contact with a heated mirror surface drum while it is in a state of being finished to have a mirror gloss finish, and after peeling from the mirror surface drum, water vapor is applied to the base paper surface. The present invention relates to a method for manufacturing paper.

An important point in the first method for producing a cast coated paper for ink jet recording of the present invention is the time from the time when the web is separated from the mirror drum surface to the time when steam is applied to the base paper surface (retention time). ) Is the amount of water vapor reacted. The retention time is usually 2 seconds or less, preferably 1 second or less, and more preferably 0.
5 seconds or less. If this retention time is too long, the temperature of the paper will drop, and moisture will remain in the paper, reducing the cockling prevention effect.

The amount of water vapor applied cannot be unconditionally determined from the relationship with the retention time, but is usually in the range of 0.3 to 2.0 g per m ^{2 of} paper in terms of water content. If the amount of water vapor applied is too small, the cockling prevention effect is small, and if it is too large, image unevenness increases.

Although the mechanism of the excellent effect of the present invention is not clear, cockling occurs because the dimensional stability of the paper against water is increased by adding water to the base paper and drying with the residual heat of the paper. The phenomenon is expected to decrease.

Immediately after the web is separated from the mirror drum surface,
Applying steam to the surface of the coated layer is more effective in preventing cockling. Also in this case, the amount of water vapor to be applied is 0.1 to 2.0 g per m ^{2 of} paper in terms of water amount, although it cannot be determined unconditionally depending on the basis weight of the paper, the quality of the paper, and the like.

Thus, the cast coated paper for ink jet recording produced by the first method of the present invention can prevent cockling well, but more preferably, it has an average particle diameter of 300 nm or less on the ink receiving layer. And a gloss-developing layer comprising a coating composition containing the colloidal particles as a main component.

The colloidal particles constituting the gloss developing layer are those which are suspended and dispersed in water and indicate inorganic particles or organic particles having an average particle size of 300 nm or less measured by a dynamic scattering method. Specifically, colloidal silica, boehmite, alumina sol such as pseudo-boehmite, colloidal alumina, cationic alumina oxide or a hydrate thereof,
Further, inorganic particles such as particles obtained by coating the surface of colloidal silica particles with alumina as disclosed in JP-B-47-26959; polystyrene, methyl methacrylate, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer. , Acrylic acid and methacrylic acid ester copolymers, microcapsules, urea resins, organic particles such as melamine, and the like. These may be used alone or in combination of two or more.

The average particle size of the colloidal particles contained in the gloss developing layer is 300 nm or less, preferably 200 nm or less. When the average particle size of the colloidal particles exceeds 300 nm, the cockling suppressing effect becomes poor, and sometimes the image quality of the inkjet recording cast coated paper having such a gloss developing layer deteriorates.

As the binder which is a main component of the gloss developing layer together with the colloidal particles, the same binders as exemplified in the description of the ink receiving layer in the first method can be preferably used. The mixing ratio of the colloidal particles and the binder is 5 to 50 parts by weight, preferably 10 parts by weight of the binder based on 100 parts by weight of the colloidal particles.
４０40 parts by weight. When the compounding ratio of the binder is less than 5 parts by weight with respect to 100 parts by weight of the colloidal particles, sufficient gloss may not be exhibited. On the other hand, colloid particles 1
If the blending ratio of the binder with respect to 00 parts by weight exceeds 50 parts by weight, the content ratio of the colloidal particles in the coating composition relatively decreases, and the promotion of the wetting effect by the colloidal particles may not be sufficient. Further, the ink absorbability is deteriorated, and the ink remains on the surface of the gloss development layer without drying for a long time after printing, so that the ink is rubbed and the image is stained.

In the first method of the present invention, the gloss-developing layer may contain one or more white pigments together with the colloidal particles. In that case, however, the pigment generally has a large particle size and causes opacity. Although it depends on the particle size of the pigment, the weight ratio of the colloidal particles and the pigment is 80/20 or more, preferably 90/10 or more, in the ratio of (colloidal particles) / (white pigment).

The gloss-developing layer may contain the above-mentioned various additives in addition to the colloidal particles and the binder, and the white pigment added if desired.

In the first method of the present invention, as the colloidal particles, those having a porous structure composed of amorphous silica / alumina or those containing cationic colloidal particles as a main component are particularly preferable. used.

The gloss developing layer is preferably provided similarly in the second and third methods of the present invention.

According to the second method of the present invention, in a coat type ink jet recording paper in which at least one ink receiving layer is provided on a support, the mirror surface heated while the ink receiving layer is in a wet state. The mirror surface is brought into pressure contact with the drum surface to give a mirror gloss finish, and when the cast coating layer surface and the base paper surface are steamed after peeling from the mirror surface drum, the retention time from the mirror surface drum surface peeling time is 5 Casting for ink jet recording, which is less than a second and the amount of water vapor applied is 0.1 to 1.2 g per m ^{2 of} paper in terms of water amount, so that cockling is significantly suppressed. A coated paper is obtained.

According to the third method of the present invention, a coated type ink jet recording paper in which at least one ink receiving layer is provided on a support, the mirror surface heated while the ink receiving layer is in a wet state. It is made into a mirror gloss finish by pressing against the drum surface, and when applying water to the base paper surface of the paper with the press nip where the coating layer is pressed against the mirror surface of the mirror surface, the amount of water applied is 1 m ² of paper. By having a composition of 5 to 20 g per unit, it is possible to obtain a cast coated paper for inkjet recording in which the occurrence of cockling is significantly suppressed.

Further, in any of the methods of the present invention,
Immediately after the web is separated from the mirror drum surface, steam can be applied to the coated layer surface.

Furthermore, by combining the second method and the third method of the present invention, it is possible to obtain a cast coated paper for ink-jet recording in which cockling is further significantly suppressed.

Furthermore, by combining the first method and the third method of the present invention, it is possible to obtain a cast coated paper for ink jet recording in which cockling is further significantly suppressed.

In the present invention, when steam is applied to the web, after peeling from the mirror drum surface, it is sprayed by a nozzle or the like, or steam is applied from a horizontal flute having a large number of pores. Just do it.

When water is applied to the base paper surface of the paper by a press nip in which the coating layer is pressed against the surface of the mirror surface drum, water is applied to the roll to be applied to the base paper surface from a color pan through a liquid raising roll. It suffices to transfer and give water. At this time, the roll may be forward or reverse.

[0059]

EXAMPLES Examples of the present invention will now be described to more specifically describe the present invention. Unless otherwise specified, "parts" and "%" in the examples and comparative examples represent absolute dry weight parts and absolute dry weight%, respectively. In addition, the particle diameters shown in Examples and Comparative Examples are average particle diameters obtained by the dynamic scattering method.

Examples 1 to 5 1) Preparation of support 80 parts of LBKP (freeness of water 400 mlcsf) and NBKP
Pigment 25 having a ratio of light calcium carbonate, heavy calcium carbonate and talc of 10/10/10 to 100 parts of wood pulp consisting of 20 parts (freeness 400 mlcsf)
Parts, commercially available alkyl ketene dimer 0.10 parts, commercially available cationic (meth) acrylamide 0.03 parts, commercially available cationized starch 0.80 parts, and sulfuric acid band 0.40 parts as a mixture to prepare a fourdrinier paper machine. It was used to make a support with a basis weight of 90 g / m ² .

2) Coating of ink receiving layer A coating composition having the following composition was prepared at a solid content concentration of 16% on the surface of the support of the above 1), and this coating solution was dried and coated by an air knife coater. It was coated and dried so that the amount was 12 g / m ² . <Ink receiving layer coating composition> Synthetic amorphous silica (Mizukasil P75D: manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) 25 parts Colloidal silica (Snowtex-O: manufactured by Nissan Chemical Industries, Ltd.) 30 parts Cationic dye fixing agent (Polyfix 601: Showa Polymer Co., Ltd.) 25 parts

3) Coating of gloss developing layer The gloss developing layer was obtained by coating the surface of the ink receiving layer and then casting. The casting treatment was carried out by a direct method in which the coating composition for the gloss developing layer was coated on the surface of the ink receiving layer, and after 2 seconds, it was pressed against a mirror-finished roll heated to a surface temperature of 90 ° C. and dried. The coating composition for the glossy layer has 100 parts of colloidal silica (PST-3: manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 300 nm as colloidal particles.
As an adhesive, 20 parts of styrene-butadiene-based latex (average particle size 135 nm: manufactured by Japan Synthetic Rubber Co., Ltd.), 30 parts of a cationic dye fixing agent (Polyfix 601: Showa High Polymer Co., Ltd.), solid content concentration 20% As a result, these were prepared. Each of the examples (1 to 5) in which this coating solution was applied by a roll coater to the dry coating amount of 3 g / m 2 on the ink receiving layer surface by the above-mentioned cast treatment method and treated by the direct method
A cast coated paper for inkjet recording was obtained.

Example 1 supports the first method of the present invention (claims 1, 2 and 3) and is one in which the retention time and the amount of water added are variously changed (sample. Numbers 1-6). Example 2 supports the second method of the present invention (Claim 4),
The retention time and the amount of water applied were variously changed (Sample Nos. 7 to 10). Further, Example 3
Supports the third method (claim 5) of the present invention (Sample No. 11). Furthermore, Example 4 is a combination of the third method and the first method of the present invention, in which the amount of water added is varied (Sample No. 1).
2-13). Similarly, Example 5 is a combination of the third method and the second method of the present invention (Sample No. 1).
4). Then, Example 6 is the second method of the present invention performed by the rewetting method (Sample No. 15).

In the rewet method, the base paper obtained as described above is provided with an ink receiving layer and a gloss developing layer, and is provided with a pressure roller having a diameter of 300 mm and a mirror surface drum having a diameter of 1250 mm, and further, A cast coated paper for inkjet recording of Example 6 was obtained which was treated by the rewet method under the following conditions using an apparatus in which a nozzle was provided on the nip. However, except that 100 parts of cationic colloidal silica having an average particle diameter of 80 nm (Snowtex AK-ZL: manufactured by Nissan Chemical Industries, Ltd.) is used as colloidal particles in the coating composition for the gloss developing layer. It was carried out using the same coating composition for the gloss-developing layer in the direct method. <Rewet casting conditions> Rewetting liquid used: hot water Rewetting liquid temperature: 95 ° C Mirror surface temperature: 95 ° C Press nip pressure: 150 kg / cm ² Wetting time: 20 mm / sec

In order to confirm the excellent effect of the present invention, one without steam treatment (Comparative Example 1) and one with steam applied only to the coated surface immediately after peeling from the mirror-finished drum surface (Comparative Example 2) ), The retention time after peeling from the mirror surface is too long (Comparative Example 3),
After being peeled off from the mirror-finished drum surface, an amount of water vapor applied too much (Comparative Example 4) was used as a comparative example.

The results of cockling and image unevenness of the ink jet recording cast coated papers obtained in the respective Examples and Comparative Examples prepared as described above are shown in Table 1.
Shown in

In the present invention, cockling and image unevenness of the cast coated paper for ink jet recording were evaluated as follows.

-Evaluation Method- <Cockling> Solid printing with black 100% gradation (10 cm x 10 cm) was carried out with a desk writer HP560C manufactured by Hewlett-Packard Company, and the degree of waviness was visually evaluated and displayed in 5 levels. Rank 1: Little cockling can be detected. Rank 2: Fine cockling is slightly seen. Rank 3: Only small ripples, almost no large ripples. Rank 4: Large waviness is seen on a part of the printed surface. Rank 5: A large wavy pattern with a period of 1 to 2 cm was generated over the entire printed surface. * Rank 4 or higher causes problems such as dirt in practice.

<Image unevenness> With a desk writer HP560C manufactured by Hewlett Packard Co., solid printing with a gradation of 60% cyan (10 cm × 10 cm) was performed, and the degree of unevenness was visually evaluated and displayed in three levels. Rank 1: Absolutely no unevenness Rank 2: Slight unevenness Rank 3: Tight unevenness

[0070]

[Table 1]

-Examination of Results- As is clear from the results in Table 1, the ink jet cast coated papers produced by the direct method of Examples 1 to 5 obtained by the method of the present invention, and Example 6 It can be seen that the inkjet cast coated papers produced by the rewetting method described above are excellent in both cockling and image unevenness.

That is, according to the present invention, water vapor is applied to the raw paper surface after peeling from the mirror-finished drum surface, water vapor is applied to both the raw paper surface and the coating layer surface after peeling from the mirror-finished drum surface, and a press nip is used. The water-repellent coating on the base paper has both cockling and image unevenness.
It turns out to be excellent.

When examined in more detail, it is particularly effective that water vapor is applied to the raw paper surface after peeling from the mirror-finished drum surface under specific conditions. It can be seen that it is more effective if water is applied to the surface of the base paper and water vapor is made to act on the base paper surface under specific conditions after peeling from the mirror surface.

Further, the test was conducted under the conditions other than the specific conditions supported in claim 2 of the present invention, in which water vapor was applied to both the base paper surface and the coating layer surface after peeling from the mirror surface (Comparative Example 3 4), cockling and unevenness of the image were not satisfactory.

[0075]

As is clear from the above description, the method for producing an ink jet cast coated paper of the present invention is an ink jet cast coated paper produced by the direct method and an ink jet produced by the rewet method. It can be seen that both the cast coated papers are excellent in terms of quality such as cockling and image unevenness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Suzuki 34-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills, Ltd.

Claims (9)

[Claims] 1. A coat type ink jet recording paper having at least one ink receiving layer provided on a support, and the mirror surface is pressed against a mirror surface drum surface heated while the ink receiving layer is in a wet state. A method for producing a cast coated paper for inkjet recording, characterized in that the cast coated layer surface is subjected to gloss finish, and after the cast coated layer surface is peeled from a mirror surface drum, steam is applied to the base paper surface. 2. The method for producing cast coated paper for inkjet recording according to claim 1, wherein the retention time from the mirror surface drum is 2 seconds or less when steam is applied to the surface of the raw paper after peeling from the mirror surface drum. 3. After peeling from the mirror surface drum, when the water vapor is applied to the surface of the raw paper, the amount of water vapor applied is in terms of water amount,
The method for producing cast coated paper for inkjet recording according to claim 1 or 2, wherein the amount is 0.3 to 2.0 g per 1 m ^{2 of} paper. 4. A coat type ink jet recording paper having at least one ink-receiving layer provided on a support, which is pressed against a mirror-finished drum surface which is heated while the ink-receiving layer is in a wet state. It has a gloss finish, and when the cast coating layer surface is peeled from the mirror surface drum and then steam is applied to the cast coating layer surface and the base paper surface, the retention time from the mirror surface drum surface peeling time is 5 seconds or less. The method for producing cast coated paper for inkjet recording, wherein the amount of water vapor applied is 0.1 to 1.2 g per m ^{2 of} paper in terms of water amount. 5. A coated type ink jet recording paper having at least one ink receiving layer provided on a support, and the mirror surface is pressed against a mirror surface drum surface heated while the ink receiving layer is in a wet state. When the base paper surface is water-coated with a press nip in which the surface of the cast coating layer is pressed against the surface of the mirror surface drum, the amount of water applied is 5 to ²⁰ g per 1 m ² of paper. A method for producing a cast coated paper for inkjet recording, which comprises: 6. The method for producing a cast coated paper for ink jet recording according to claim 1, 4 or 5, wherein steam is applied to the cast coated layer surface immediately after peeling from the mirror surface drum. 7. An average particle size of 300 on the ink receiving layer.
The method for producing cast coated paper for inkjet recording according to claim 1, 2, 3, 4, 5, or 6, wherein a gloss-developing layer comprising a coating composition containing colloidal particles having a size of not more than 10 nm as a main component is provided. 8. The method for producing cast coated paper for inkjet recording according to claim 7, wherein the colloidal particles are those having a porous structure composed of amorphous silica-alumina. 9. The method for producing cast coated paper for ink jet recording according to claim 7, wherein the colloidal particles are mainly composed of cationic colloidal particles.