JP2001010207A - Manufacture of ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture an ink jet recording paper which is excellent in an ink absorbing amount, does not have a blow casting and cracks, and is excellent in film strength. SOLUTION: This recording paper has at least one layer of an ink absorbing layer containing an inorganic particle, on a supporting body. In this case, the film surface temperature of the coated film for which a coating liquid is applied, of the ink absorbing layer is dried at 30 deg.C or lower. Also, the drying speed h×ΔT is set to be 500 or higher. In this case, h represents a coefficient of heat transmission (kcal/m2 deg.Chr), and ΔT( deg.C) represents the difference between a blowing air temperature and the film surface temperature of the coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an ink jet recording paper.

[0002]

2. Description of the Related Art With the remarkable technological innovation of ink jet recording in recent years, the print quality is becoming comparable to the print obtained by silver halide photography.

[0003] With the spread of ink jet printers and digital cameras, various color prints have recently been printed by ink jet printers, and the uses of the prints have also become diversified. The ink jet recording paper used in this ink jet recording method has a high density of print dots, a vivid color tone,
It is required that the ink absorbs quickly, the ink does not flow out even when the print dots overlap, there is no bleeding, the spread of the print dots in the horizontal direction is not excessively large, and the periphery is smooth and does not blur. . Especially when ink absorption is slow,
When ink droplets of two or more colors are recorded in an overlapping manner, repelling or unevenness occurs on the ink jet recording paper, or the colors of each other are blurred in the boundary area of different colors to improve the image quality. It is easy to greatly decrease. Therefore, it is necessary that the ink jet recording paper has high ink absorbency, and such ink jet recording paper has been demanded.

The simplest means for improving the image quality by increasing the ink absorption amount is to increase the amount of the ink absorption layer. However, it is known that when the coating amount is increased, various film surface failures occur when the coating liquid for the ink absorbing layer is applied and dried.

In the early stage of drying, the viscosity is low, so that the coating film tends to be disturbed (blown) by the drying wind, and in the latter stage of drying, the stress in the film is concentrated on the surface and cracks are liable to occur. Therefore, for example, Japanese Patent Application Laid-Open No. 11-115308 attempted to achieve the object by curing with a crosslinking agent before drying at a reduced rate. However, in the case of simultaneous application of a liquid containing a crosslinking agent,
It is not easy or practical to solve the cohesion at the interface. In addition, the addition of a crosslinking agent during drying is not sufficient because the reaction does not proceed. JP-A-11-91238 discloses that
Japanese Patent Application Laid-Open No. Hei 8-310114 discloses a method in which air is not blown until a solid content concentration of 5% is reached. In this method, vertical wind speed is 2.5 m / sec or less and horizontal wind speed is 4.0 m / sec or less. Attempts have been made to suppress them, but these production methods are not practical because the drying rate is not sufficient and productivity is reduced.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for efficiently producing an ink jet recording sheet which is excellent in ink absorption, is free of blown and cracks and has excellent coating strength.

[0007]

The above object of the present invention is achieved by the following constitution.

(1) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, the film surface temperature of the coating film coated with the coating liquid for the ink absorbing layer is set at 30. A method for producing ink jet recording paper, characterized by drying at a temperature of not more than ° C.

(2) The method for producing ink jet recording paper as described in (1) above, wherein the drying speed h × ΔT is 500 or more. Here, h is the heat transfer coefficient (kcal / m
² ° C. hr), and ΔT (° C.) represents the difference between the air blowing temperature and the film surface temperature of the coating film.

(3) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, a water content of a coating film coated with a coating liquid of the ink absorbing layer is 200%. A method for producing an ink jet recording paper, wherein the film surface temperature is 30 ° C. or less in a dry region of ３０30%.

(4) The method for producing ink jet recording paper as described in (3) above, wherein the drying speed h × ΔT is 500 or more.

(5) In a method for producing an ink jet recording sheet having an ink absorbing layer containing at least one layer of inorganic fine particles on a support, the water content of the coating film coated with the coating liquid of the ink absorbing layer is 1000%. In a dry region of ~ 500%, the film surface temperature is 20 ° C or less and the film surface wind speed is 30m /
sec. or less, the method for producing ink jet recording paper.

(6) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one layer of inorganic fine particles on a support, the water content of the coating film coated with the coating liquid of the ink absorbing layer is 1000%. A method for producing an ink jet recording sheet, characterized in that a film surface temperature is 20 ° C. or less in a drying region of up to 500% and a slit nozzle is used in a drying device.

(7) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one layer of inorganic fine particles on a support, the water content of a coating film coated with a coating liquid of the ink absorbing layer is 1000%. In the dry area of ~ 500%, the film surface wind speed v (m / sec) and the viscosity μ of the coating film
A method for producing an ink jet recording paper, wherein the ratio v / μ of (P) is 0.5 or less.

(8) Ink jet recording wherein the water content and the film surface temperature of the coating film are determined during the drying step of the coating film coated with the coating liquid for the ink absorbing layer, and the dry-bulb temperature of the blown air is controlled. Paper manufacturing method.

(9) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, the water content of a coating film coated with a coating liquid of the ink absorbing layer is 15%. A method for producing an ink jet recording paper, wherein the tension applied to the web at the time of winding is 100 kgf / m or less.

(10) In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one layer of inorganic fine particles on a support, the water content of a coating film coated with a coating liquid of the ink absorbing layer is 15%. In the following dry areas,
A method for producing an ink jet recording paper, wherein the film surface temperature is 40 ° C. or higher.

(11) The method according to the above (1), wherein the film surface temperature is raised to 40 ° C. or higher by a heat roll or far infrared rays.
0. The method for producing an ink jet recording sheet according to item 0.

Hereinafter, the present invention will be described in detail. The inventor has proposed that in order to eliminate the cracks of the ink jet recording paper, in a drying step in which the water content of the coating film coated with the coating liquid for the ink absorbing layer (hereinafter, also simply referred to as the film water content) is 200% to 30%, The present inventors have found that drying at a low film surface temperature and at a high drying rate is most effective, and made the present invention. In particular, when the film surface temperature is 30 ° C. or less, preferably 26 ° C. or less,
When the drying speed h × ΔT is 500 or more, an excellent ink jet recording paper without cracks can be manufactured.

In the present invention, the water content refers to the weight percentage of water relative to the solid content. Drying of the present invention is a tunnel-shaped drying device, while drying while moving a sample coated with a predetermined coating solution, the drying device is divided into several,
A measuring device is installed in advance so that the moisture content of the film can be measured efficiently by each drying device. Heat transfer coefficient h of the present invention
(Kcal / m ² ° C hr) was calculated from the above average drying ability of each drying device. The film surface wind speed refers to the wind speed near the coating film surface.

In addition, the water content of the film is 1000% to 50%.
This can be prevented by drying at a film surface temperature of 20 ° C. or less and a film surface wind speed of 30 m / sec or less in a 0% drying step. In particular, when the water content of the film is 700% to 500%, no occurrence occurs when the film surface wind speed is 20 m / sec to 30 m / sec and the film surface temperature is 20 ° C. or less. In addition, the blowing depends not only on the film surface wind speed but also on the viscosity of the coating film. Membrane moisture content 1000%
In the drying area of ~ 500%, since the drying has not progressed,
It cannot be said that there is sufficient viscosity, but the dynamic pressure due to the airflow to the coating film surface becomes the driving force, and the film pressure fluctuation increases in inverse proportion to the viscosity. Therefore, the quotient v / μ obtained by dividing the film surface wind velocity v by the viscosity μ
The present invention was found to be effective for suppressing streak unevenness due to blowing, using the index as an index.

Further, in order to improve the ink absorption, it is effective to raise the film surface temperature to 40 ° C. or higher, particularly preferably 50 ° C. or higher, in the drying step at a film water content of 15% or less. Without such treatment, it is considered that when absorbing the ink, the binder (for example, PVA) swells and closes the voids, so that the absorption rate decreases. However, as described above, when the heat treatment is performed, the binder is crystallized, so that the swelling is suppressed. This heat treatment is also effective for convective heat transfer such as flash drying, conductive heat transfer such as a heat roll, radiant heat transfer such as far infrared rays, and microwave drying.

In order to achieve the above configuration, the moisture content of the membrane is predicted by measuring with a moisture meter and a thermometer, and the drying process is controlled.
Inkjet recording paper was manufactured with the above configuration. Examples of the moisture meter include a non-contact infrared absorption type and a microwave transmission type.

The ink absorbing layer of the ink jet recording paper of the present invention is formed from inorganic fine particles and a small amount of a hydrophilic polymer. Examples of such inorganic fine particles include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide,
White inorganic pigments such as zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, and magnesium hydroxide And the like.

Such inorganic fine particles can be used either as primary particles or in a state where secondary aggregated particles are formed.

In the present invention, from the viewpoint of obtaining a high maximum density and a preferable surface quality during printing, the average particle diameter is 500 n.
It is preferable to use fine particles of m or less, particularly 200 nm or less.

Further, it is necessary to form fine voids from the viewpoint of obtaining a high density when recording by ink-jet recording, and silica or pseudo-boehmite is preferable, and particularly synthesized by a gas phase method having an average particle diameter of 200 nm or less. Silica, colloidal silica and pseudoboehmite are preferred.

The average particle diameter of the inorganic fine particles is determined by observing the cross section or surface of the particles themselves or the void layer with an electron microscope.
The particle size of zero arbitrary particles is obtained, and is obtained as a simple average value (number average). Here, each particle size is represented by a diameter assuming a circle equal to the projected area.

The hydrophilic polymer used in the ink absorbing layer can be appropriately selected from known hydrophilic polymers, and a preferred hydrophilic polymer is polyvinyl alcohol.

The polyvinyl alcohol used in the present invention includes, in addition to general polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Of modified polyvinyl alcohol.

The polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate preferably has an average degree of polymerization of 300 or more, and particularly preferably has an average degree of polymerization of 1,000 to 500.
0 is preferably used.

The degree of saponification is preferably from 70 to 100%, particularly preferably from 80 to 99.5%.

The ink absorbing layer is preferably porous. To make it porous, the ink absorbing layer can be obtained by using a small amount of a hydrophilic binder with respect to the inorganic fine particles. 3 to 10 in ratio
Times, preferably 4 to 8 times.

When the porous layer contains polyvinyl alcohol as a hydrophilic polymer, it is preferable to add a hardener in order to improve the film forming property of the film and to increase the strength of the film.

When polyvinyl alcohol is used as the hydrophilic binder, the hardener is preferably an epoxy hardener or a borate.

The term "borate" refers to an oxyacid having a boron atom as a central atom and its salts, and specifically includes orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid and salts thereof. It is.

The amount of boric acid or a salt thereof can vary widely depending on the amount of the inorganic fine particles and the hydrophilic polymer in the coating solution, but is generally about 1 to 60% by weight, preferably 5 to 40% by weight based on the hydrophilic polymer. %.

Various additives other than those described above can be added to the ink absorbing layer. For example, Japanese Unexamined Patent Publication No. 57-741
Nos. 93, 57-87988 and 62-2
UV absorber described in JP-A-61476;
Nos. 74192, 57-87989, 60-7
Nos. 2785, 61-146591, JP-A-1-95091, and JP-A-3-13376, etc .; anti-fading agents; various anionic, cationic or nonionic surfactants; JP-A-59-42993, JP-A-59-52689, and JP-A-62-28006.
9, JP-A-61-228771 and JP-A-Hei.
Fluorescent brighteners described in -219266 and the like;
Known various additives such as a defoaming agent, a lubricant such as diethylene glycol, a preservative, a thickener, an antistatic agent and a matting agent can also be contained.

The dry film thickness of the porous ink absorbing layer is determined depending on the amount of ink absorbed, and is generally 20 to 70 μm.
m is preferably 30 to 50 μm from the viewpoint that all the ink solvent must be temporarily held. A particularly preferred dry film thickness is 35 to 50 μm.

In the recording paper of the present invention, it is preferable that the static friction coefficient between the front and back sides be 0.8 or less from the viewpoint of continuous conveyance.

If the coefficient of static friction exceeds 0.8, it tends to be difficult to convey or feed a large number of sheets at a time. In particular, the coefficient of static friction is preferably set to 0.7 or less. The lower limit of the static friction coefficient is not particularly limited, but is generally 0.2 or more.

In order to make the front and back static friction coefficient 0.8 or less, the surface characteristics (surface quality, binder slipperiness) of the front and back ink absorbing layers are adjusted.

Specifically, a method of adding a matting agent to make the surface of the ink absorbing layer on the front and back have a convex portion, or a wax, a silicon-based compound or It can be adjusted relatively easily by adding a slipping agent such as a fluorine compound. A particularly effective means is to use a matting agent.

As the matting agent, inorganic particles (silica, calcium carbonate, talc, etc.) and organic latex (polystyrene, polyethylene, polymethyl methacrylate, etc.) are used, but organic latex is preferred.

Such a matting agent having an average particle size of 5 μm or more is preferable since it has a relatively small effect on gloss and can improve slipperiness. Particularly preferred matting agents have an average particle size of 7 to 30 μm.

The matting agent preferably has a relatively uniform particle size distribution and has little gloss reduction. When the particle size distribution is measured, the degree of dispersion (standard deviation divided by average particle size) is 2.
Hereinafter, those having 1.5 or less are particularly preferable.

The amount of the matting agent used varies depending on the particle size of the matting agent and the dry film thickness of the ink absorbing layer to which the matting agent is added, but is generally 0.01 to 0.5 g per 1 m ^{2 of} recording paper.

In the present invention, as a support for the ink jet recording paper, a paper support, a plastic support, a composite support, etc., which are conventionally known as ink jet recording papers, can be used as appropriate, but in order to obtain a clear image at a higher density. It is preferable to use a hydrophobic support that does not penetrate the ink liquid into the support.

The transparent support is made of, for example, a polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, celluloid and the like. Film and the like.
Those having the property of resisting radiant heat when used as HP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is about 10 to
200 μm is preferred. It is preferable to provide a known undercoat layer on the ink absorbing layer side and the back layer side of the transparent support from the viewpoint of adhesion between the ink absorbing layer and the back layer and the support.

Examples of the support used when it is not necessary to be transparent include resin-coated paper (so-called RC paper) having a polyolefin resin-coated layer obtained by adding a white pigment or the like to at least one of base paper, polyethylene terephthalate A so-called white pet obtained by adding a white pigment to the ink is preferred.

Prior to the application of the ink absorbing layer, for the purpose of increasing the adhesive strength between the support and the ink absorbing layer,
The support is preferably subjected to a corona discharge treatment, an undercoating treatment, or the like. Furthermore, the recording sheet of the present invention is not necessarily colorless, and may be a colored recording sheet.

In the ink jet recording paper of the present invention, the use of a paper support in which both sides of the base paper support are laminated with polyethylene is particularly preferable since the recorded image is close to the photographic quality and a high quality image can be obtained at low cost. preferable.
Such a paper support laminated with polyethylene is described below.

The base paper used for the paper support is made of wood pulp as a main raw material, and if necessary, is made of synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As wood pulp, LBKP, LBSP, NBKP, NBSP, LD
Any of P, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, and LBS containing a large amount of short fibers
It is preferable to use more P, NDP, and LDP.
However, the ratio of LBSP and / or LDP is 10% by weight.
At least 70% by weight is preferred.

As the pulp, a chemical pulp containing a small amount of impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by a bleaching treatment is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, Water retention agents such as polyethylene glycols, dispersants, and softening agents such as quaternary ammonium can be appropriately added.

The freeness of the pulp used for papermaking is preferably 200 to 500 cc according to the specification of CSF, and the fiber length after beating is 24 mesh residual weight% and 42 mesh residual weight specified in JIS-P-8207. 30% by weight
To 70% is preferable. The weight percentage of the remaining 4 mesh
Is preferably 20% by weight or less.

The basis weight of the base paper is preferably 30 to 250 g, particularly preferably 50 to 200 g. Base paper thickness is 4
It is preferably from 0 to 250 μm.

The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / m ² (JIS-P-8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS-P-8143.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agents as those which can be added to the base paper can be used.

The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS-P-8113.

The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can be partially used.

In particular, the polyethylene layer on the ink absorbing layer side is preferably a layer obtained by adding rutile or anatase type titanium oxide to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is approximately 3 to 20% by weight based on polyethylene,
Preferably it is 4 to 13% by weight.

The polyethylene-coated paper may be used as a glossy paper, or when polyethylene is melt-extruded onto a base paper surface and coated, a so-called embossing treatment is performed to obtain a matte surface or silk which can be obtained with ordinary photographic printing paper. Those having an eye surface can also be used in the present invention.

The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl under low and high humidity conditions after providing the ink absorbing layer and the backing layer. Is in the range of 20 to 40 μm, and the back layer side is in the range of 10 to 30 μm.

The method of applying various hydrophilic layers, which are appropriately provided as necessary, such as a void layer and an undercoat layer, on the support of the recording paper of the present invention can be appropriately selected from known methods. . A preferred method is obtained by applying a coating solution constituting each layer on a support and drying it. in this case,
Two or more layers can be coated simultaneously, and in particular, simultaneous coating is preferable, in which all the hydrophilic binder layers need only be coated once.

Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method and an extrusion coating method using a hopper described in US Pat. No. 2,681,294. It is preferably used.

[0067]

The present invention will be described below with reference to examples of the present invention.
The present invention is not limited to these examples. In addition,
In Examples, "%" indicates absolute dry weight% unless otherwise specified.

Example 1 "Preparation of Titanium Oxide Dispersion-1"
20 kg of titanium oxide of 20 μm, 150 g of sodium tripolyphosphate having a pH of 7.5, 500 g of polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.), and 90 l of an aqueous solution containing 10 g of an antifoaming agent SN381 of Sannobuco Co. After dispersing with a homogenizer (manufactured by Sanwa Kogyo Co., Ltd.), the total amount was finished to 100 l to obtain a uniform titanium oxide dispersion liquid-1.

[Preparation of Silica Dispersion-1] 125 kg of fumed silica (A300, manufactured by Nippon Aerosil Co., Ltd.) having an average primary particle size of about 0.007 μm was jetted from Mitamura Riken Kogyo Co., Ltd. Using a stream inductor mixer TDS, the mixture was suction-dispersed in 620 l of pure water adjusted to pH = 2.5 with nitric acid at room temperature, and the total amount was made up to 694 l with pure water.

[Preparation of Silica Dispersion-2] 1.63 kg of cationic polymer P-1, 2.2 l of ethanol, n-
An aqueous solution containing 1.5 l of propanol (pH = 2.
3) 69.4 l of the silica dispersion-1 was added to 18 l while stirring, and then 260 g of boric acid and 230 g of borax were added.
g of an aqueous solution containing 0.1 g of the above-mentioned antifoaming agent S
1 g of N381 was added.

This mixed solution was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 97 l with pure water to prepare a silica dispersion liquid-2.

[0072]

Embedded image

"Preparation of Fluorescent Whitening Agent Dispersion-1" Oil-soluble fluorescent whitening agent UVITEX-OB manufactured by Ciba-Geigy Co., Ltd.
Was dissolved in 9000 g of diisodecyl phthalate and 12 l of ethyl acetate under heating, and this was added to 3500 g of acid-treated gelatin and 65 l of an aqueous solution containing 6000 ml of a 50% aqueous solution of saponin, mixed and emulsified and dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. After removing ethyl acetate under reduced pressure, the total volume was adjusted to 100 l.

"Preparation of Matting Agent Dispersion-1" A methacrylate ester matting agent MX-15 manufactured by Soken Kagaku Co., Ltd.
156 g of 000H was added to 7 l of pure water containing 3 g of the PVA235, and the mixture was dispersed with a high-speed homogenizer to complete the total amount to 7.8 l.

"Preparation of Coating Solution" Coating solutions for the first, second and third layers were prepared by the following procedure.

Coating solution for first layer: 60 of silica dispersion-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

A 10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml A 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 260 ml Fluorescent brightener dispersion liquid-1: 25 ml Oxidation Titanium Dispersion-1: 33 ml, manufactured by Daiichi Kogyo Co., Ltd .: Latex Emulsion AE-803: 18 ml.

Coating solution for second layer: 65 of silica dispersion-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 270 ml Fluorescent brightener dispersion liquid-1: 35 ml Make up to 1000 ml with water.

Coating solution for third layer: 65 of silica dispersion-2
The following additives were sequentially mixed with 0 ml while stirring at 40 ° C.

10% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203): 0.6 ml 5% aqueous solution of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235): 270 ml Silicone dispersion (Dow Corning Toray Silicone Co., Ltd.) (Manufactured by Company, BY-22-839): 15 ml 50% aqueous solution of saponin: 4 ml Matting agent dispersion liquid-1: 10 ml Make up to 1000 ml with pure water.

The coating solution obtained as described above was filtered with the following filter.

First layer and second layer: two steps with TCP10 manufactured by Toyo Filter Paper Co., Ltd. third layer: two steps with TCP30 manufactured by Toyo Filter Paper Co., Ltd. Then, a paper support in which both sides of a 170 g / m ² base paper were coated with polyethylene ( Thickness 220 μm, about 35 on the recording side
The recording surface side (the 75-degree glossiness of the support is 32%, on the back side, which contains 9% by weight of anatase-type titanium dioxide in a polyethylene layer having a thickness of about 30 μm).
Already Coating as gelatin about 0.1 g / m ² subbing layer)
The first layer (50 μm), the second layer (100 μm), the third layer
Each layer was applied in the order of layers (50 μm). The figures in parentheses indicate the respective wet film thicknesses. Each coating liquid was simultaneously applied to the first to third layers by a three-layer slide hopper. The drying speed and the film surface temperature were changed as shown in Table 1 to prepare recording papers 11 to 19, and the cracks were evaluated. The results are shown in Table 1.

Criteria for evaluation of cracks ×× Cracks exceeding 2.0 mm × Cracks of 0.5 to 2.0 mm ○ Cracks of less than 0.5 mm (range in which there is no practical problem) ◎ No cracks are observed at all

[0085]

[Table 1]

From the results shown in Table 1, it is understood that the sample of the present invention was excellent without cracking.

Example 2 In the same manner as in Example 1, coating was performed with a three-layer slide hopper, and the recording paper 21 was dried at a film moisture content of 200% to 30% and the film surface temperature was changed as shown in Table 2. ~ 29,
The cracks were evaluated and the results are shown in Table 2.

[0088]

[Table 2]

From Table 2, it can be seen that the occurrence of cracks was due to the film moisture content of 200
% To 30%, which mainly occurs from the late stage of constant rate drying to the early stage of decreasing rate drying. It can be seen that lowering the film surface temperature has the effect of improving the film strength and preventing the occurrence of cracks.

Example 3 In the same manner as in Example 1, coating was performed using a three-layer slide hopper, and the film surface temperature and the film surface wind speed were changed as shown in Table 3 in the region of the film water content of 1000% to 500%. Recording papers 31 to 38
Was prepared and the unevenness of the lines was evaluated. The results are shown in Table 3.

Evaluation Standard for Streak Unevenness The obtained recording paper was printed in black solid and visually evaluated for streak unevenness in the width direction. XX Strong streaks were observed. X Streaks were observed. No problem ◎ No unevenness is seen

[0092]

[Table 3]

From Table 3, it can be seen that no line unevenness was observed under the drying conditions of the present invention. The punch plate is a drying device for a perforated plate having a specific pattern in a blowing port, and the slit nozzle is a drying device for blowing air uniformly in the width direction of the web.

Example 4 In the same manner as in Example 3, coating was performed with a three-layer slide hopper, and the film surface temperature and film surface wind speed in the region of the water content of 1000% to 500% were changed as shown in Table 4. Recording paper 41 to 47
Was prepared and the unevenness of the stripes was evaluated. The results are shown in Table 4.

The viscosity was measured off-line using a B-type rotary viscometer (manufactured by TOKIME, VISCOMTER) to measure the temperature dependency at each water content of the film, graphed, and the viscosity was calculated from the film surface temperature. Show.

[0096]

[Table 4]

From Table 4, it can be seen that when v / μ is 0.5 or less, the line unevenness becomes good.

Example 5 A moisture meter (non-contact infrared moisture meter manufactured by Nippon Tobacco Inc.) and a thermometer capable of online measurement were installed in the coating and drying process, and a desired film surface was prepared according to the change in the water content of the film. The heater was controlled by computer to reach the temperature. Table 5 shows cracks when the drying temperature (DB) is not controlled and when the drying temperature is controlled by feeding back the data of the moisture meter and the thermometer.

[0099]

[Table 5]

The effect of the feedback control can be clearly seen.

Example 6 In the same manner as in Example 1, coating was carried out using a three-layer slide hopper, and the recording paper 61 to 61 was obtained by changing the winding tension as shown in Table 6 with a substantially dry film moisture content of 15% or less. No. 65 was prepared and the unevenness of the lines was evaluated. The results are shown in Table 6.

[0102]

[Table 6]

As shown in Table 6, when the winding tension is increased,
Pressure is applied to the surface due to fluctuations in the thickness of the coating film due to unevenness or blowing of the base paper, and the voids are crushed, resulting in longitudinal unevenness.

Example 7 In the same manner as in Example 6, coating was performed using a three-layer slide hopper, and the film surface temperature was changed as shown in Table 7 by changing the temperature of the drying air at a substantially dry film moisture content of 15% or less and changing the drying air temperature. Change recording paper 71
To 79 were prepared, and the absorption rate of the ink was measured. The results are shown in Table 7.

Method for Measuring Ink Absorption Rate A predetermined amount of liquid droplets (PMICIC, dark magenta color, 2 μm, manufactured by EPSON) was applied to the obtained ink jet recording paper using a contact angle measuring device DAT1100Mk manufactured by FIBRO.
l) The solution was dropped and the time required for the liquid volume remaining on the surface to reach 0.5 μl was measured.

[0106]

[Table 7]

When the volume of the liquid remaining on the surface becomes 0.5 μl, the lateral bleeding of dots that land adjacently is reduced, and the lateral bleeding is substantially eliminated. From Table 7, it can be seen that Samples 71 and 72 which have been dried at low temperatures require more than 3 seconds to clear this value. On the other hand, the samples 73 to 75 in which the temperature of the drying air of the present invention was changed to increase the film surface temperature were 2 seconds or less, and the absorption speed was improved. Further, samples 76 and 77 using heat rolls for heat treatment and samples 78 and 79 using far-infrared rays also exhibited the same effect.

[0108]

According to the present invention, the ink absorption amount is excellent,
An ink jet recording paper which is not blown and has no cracks and excellent coating strength can be obtained.

Claims (11)

[Claims] In a method for producing an ink jet recording paper having an ink absorbing layer containing at least one layer of inorganic fine particles on a support, the film surface temperature of a coating film coated with a coating liquid of the ink absorbing layer is 30 ° C. A method for producing an ink jet recording paper, characterized by drying below. 2. The method according to claim 1, wherein the drying speed h × ΔT is 500 or more. Here, h is a heat transfer coefficient (kcal / m ² ° C).
hr), and ΔT (° C.) represents the difference between the air blowing temperature and the film surface temperature of the coating film. 3. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein the water content of the coating film coated with the coating liquid of the ink absorbing layer is 200% to 200%. A method for producing an ink jet recording paper, wherein the film surface temperature is 30 ° C. or less in a 30% dry area. 4. The method according to claim 3, wherein the drying speed h × ΔT is 500 or more. 5. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein the water content of the coating film coated with the coating liquid of the ink absorbing layer is 1000% or more. In a dry region of 500%, the film surface temperature is 20 ° C. or less and the film surface wind speed is 30 m / sec.
c. A method for producing an ink jet recording paper, characterized by being not more than c. 6. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein the water content of the coating film coated with the coating liquid of the ink absorbing layer is 1000% or more. A method for manufacturing an ink jet recording paper, wherein a film surface temperature is 20 ° C. or less in a drying region of 500% and a slit nozzle is used in a drying device. 7. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein the water content of the coating film coated with the coating liquid of the ink absorbing layer is 1000% or more. In the dry region of 500%, the film surface wind speed v (m / sec) and the viscosity μ (P) of the coating film
Wherein the ratio v / μ is 0.5 or less. 8. An ink-jet recording sheet, wherein a water content and a film surface temperature of a coating film are obtained during a drying step of the coating film coated with the coating liquid of the ink absorbing layer, and a dry-bulb temperature of the blown air is controlled. Manufacturing method. 9. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein a water content of a coating film applied with a coating liquid of the ink absorbing layer is 15% or less. Wherein the tension applied to the web during winding is 100 kgf / m or less. 10. A method for producing an ink jet recording paper having an ink absorbing layer containing at least one or more inorganic fine particles on a support, wherein a water content of a coating film applied with a coating liquid of the ink absorbing layer is 15% or less. Wherein the film surface temperature is 40 ° C. or higher in the dry region of (1). 11. The method according to claim 10, wherein the film surface temperature is set to 40 ° C. or higher by a heat roll or far infrared rays.