JP4613810B2 - Glossy inkjet recording paper manufacturing method - Google Patents

Description

  The present invention relates to a method for producing glossy inkjet recording paper.

  The inkjet recording method that forms an image by ejecting water-based ink from fine nozzles is easy to make full color, high-speed recording is possible, and printing cost is lower than other printing devices for printing a small number of copies. For some reason, it is widely used in terminal printers, facsimiles, plotters, and form printing.

In recent years, ink jet printers have been rapidly spread and have high definition and high speed, and accordingly, ink jet recording papers are required to have an improved ink absorption speed than ever before.
Furthermore, there is a strong demand for the realization of high image quality comparable to silver halide photography for recorded images taken with a digital camera.
Further, in order to bring the quality of a printed image closer to that of a silver salt photograph, further improvement in the color density and glossiness of the printed image is desired.

On the other hand, in order to realize image storability equivalent to that of silver salt photographs, improvement of the ink itself has been proposed.
Aqueous dye ink using a highly hydrophilic colorant that occupies the mainstream of conventional ink jet recording inks (hereinafter referred to as dye ink), and a hydrophobic color pigment having excellent water resistance and light resistance as a colorant Ink (hereinafter referred to as “pigment ink”) is also often used.
The colored pigment in the pigment ink tends to stay on the coated surface, and the high gloss inkjet recording paper for the dye ink that has been used so far is inferior in fixability and scratching property of the pigment ink.
For this reason, there is a strong demand for ink jet recording paper capable of printing with high image quality for both dye ink and pigment ink.

  In order to achieve this, technology to obtain higher ink absorption speed and gloss, such as suppressing cracks in the coating film and reproducing the roundness of dots, is essential. The receiving layer is formed to contain fine pigment, and control is performed so that the peak of the pore diameter distribution curve in the plurality of pores formed between the fine pigments is occupied by pores of about 0.1 μm or less. I need.

As a technique for obtaining a high ink absorption rate and gloss, for example, the ink recording layer contains inorganic pigment fine particles which are primary particles composed of simple particles and have an average particle diameter of 20 nm or less, and polyvinyl alcohol as a binder. Inkjet recording papers have been proposed.
This recording paper uses a cross-linking reaction between borax or boric acid and polyvinyl alcohol to gel the coating before the ink recording layer exhibits a reduced drying rate, thereby cracking the coating film. A high coating amount is imparted while suppressing, the roundness of dots is reproduced, and an excellent image quality can be obtained in a dye ink (Patent Document 1).
As a further improvement of the recording paper, an undercoat layer coated with boric acid or a boron compound with a limited coating amount is provided between the support and the ink recording layer, and the content is limited on the surface thereof. An ink recording layer including inorganic pigment fine particles and polyvinyl alcohol has also been proposed.
This recording paper further improves cracks in the coating film (Patent Document 2).
However, in these recording papers, the surface gloss of the surface layer is insufficient, and the ink absorptivity when pigment ink is used is not yet sufficient.

In addition, it is manufactured by applying a first porous layer to a non-water-absorbing support and drying, or by applying a second porous layer before the end of drying, Inkjet recording paper that does not generate bubbles has been proposed. With this recording paper, an ink recording layer free from bubbles and cracks can be formed by the manufacturing method (Patent Document 3).
However, the gloss and ink absorption speed of the ink jet recording paper have not been sufficient yet.

Furthermore, an ink jet recording paper manufacturing method using a water-absorbing base paper as a support has been proposed.
In this recording paper, a borax or boric acid treatment layer and an ink receiving layer containing polyvinyl alcohol are sequentially provided on the glossy surface of the glossy paper, and these are cross-linked to form a bond strength between the base paper and the ink receiving layer. The image quality of the recorded image is improved, and the dimensional stability is excellent (Patent Document 4).
In addition, an improved recording paper has been proposed in which the amount of borax or boric acid applied and the amount of ink-receiving layer applied are limited (Patent Document 5).
However, high gloss and print density are not obtained because wet silica having an average particle diameter of 1 μm or more is used for the ink receiving layer of these recording papers.

As a technique for imparting gloss, for example, a technique has been proposed in which a gloss-expressing layer containing colloidal particles and a polymer latex is provided on an ink recording layer mainly containing a micron order pigment. With this configuration, a certain level of gloss can be obtained (Patent Document 6).
However, in this technique, since the dye in the ink is fixed on the micron-order ink recording layer, the printing density is low and the uniformity of the image is also inferior. In addition, since the peak of the pore diameter distribution curve in the plurality of pores formed in the glossy layer is occupied by pores larger than 0.1 μm, the glossy layer is cracked, the visual gloss is low, and the pigment ink There was a problem that the print density of the ink was also inferior.

In order to further increase the gloss, a method has been proposed in which the glossy layer formed by the coating layer is subjected to a casting process in which the layer is pressed against a heated mirror drum in a wet state, and the mirror surface is copied. By this method, a certain level of gloss can be obtained (Patent Document 7).
However, since the glossy layer has cracks, the uniformity of the image is inferior, and the print density and printability for pigment ink have not been solved.

In addition, while the recording layer provided with two or more recording layers on the base material and the coating layer containing an aggregate pigment having an average particle diameter of 1 μm or less on the surface layer is in a wet state. There has been proposed an attempt to solve problems such as gloss, print density, ink absorbency, etc. by performing a casting process for pressure bonding to a heated mirror drum (Patent Document 8).
However, since the peak of the pore diameter distribution curve in the plurality of pores formed on the outermost layer is not occupied only by pores of 0.1 μm or less, and cracks on the outermost layer are not controlled, The dots were not round, the print density was insufficient, and the image uniformity was low.

In addition, with recent high-definition and high-speed printers, ink absorbency has been insufficient.
For this reason, when pigment ink is used, a large amount of the color pigment is absorbed in the cracked portion of the coating film, resulting in unevenness in the image and low print density, which is inappropriate.
Furthermore, these recording papers have a problem in that paper dust is likely to be generated when the paper is cut because a recording layer with a reduced binder amount is used to increase the amount of ink absorbed as the ink amount increases. .

On the other hand, as a method for producing an inkjet recording paper, when the ink receiving layer is cast, the coating layer formed by applying the ink receiving layer solution is once dried, and then the rewetting liquid is used as the dry ink. A rewet cast process has been proposed in which a receiving layer is coated and cast.
In this rewet cast process, a gloss imparting agent, a coagulant, and the like can be imparted to the rewetting liquid, so that a desirable gloss can be expressed (Patent Document 9).
However, this recording paper has a problem that the image quality comparable to the photographic image quality cannot be reached because there is no concept of introducing a fine pigment.
In addition, the rewetting cast processing has been proposed as another method in the manufacturing method (Patent Document 7) of the ink jet recording paper including the casting process in which the above-described wet state is pressure-bonded to the mirror drum, but in this manufacturing method, There is no idea of using a crosslinking agent, and there is no concept of crack management.

Japanese Patent Laid-Open No. 11-115308 JP 2001-246832 A JP 2000-301828 A JP-A-5-104848 Japanese Patent Publication No. 7-37175 Japanese Patent Laid-Open No. 7-101142 Japanese Unexamined Patent Publication No. 7-117335 JP 2001-10220 A Japanese Patent Publication No. 7-96331

The present invention has been made in view of the above circumstances, and as a result of intensive studies, the inventors have provided an undercoat layer containing a specific component and a pre-ink receiving layer on a gas-permeable support. And it discovered that these problems could be solved by casting, and completed the present invention.
The technical problem of the present invention is that the ink receiving layer is not cracked and has good recording properties for dye inks, as well as excellent ink absorbability, print density, and print gloss of pigment inks. Another object of the present invention is to provide a method for producing glossy ink jet recording paper, which can share dye ink and pigment ink and further suppress the generation of paper dust.

In order to solve the above problems, a method for producing a glossy inkjet recording paper of the present invention comprises a pigment containing amorphous silica having an average particle size of 10 μm or less, a water-soluble adhesive and a water-dispersible adhesive on a gas-permeable support. An aqueous coating solution having at least one adhesive selected from the agents is applied, dried to form an undercoat layer, and an aqueous coating solution containing a boron-containing compound is formed on the undercoat layer. A gas phase method in which a boron-containing compound coated surface in a coated state or a dried state thereof is formed, and secondary particles having an average particle diameter of 90 to 700 nm are formed on any of the boron-containing compound coated surfaces. shape and silica or wet process silica, polyvinyl alcohol is the degree of polymerization 3500 to 5000 as an adhesive, Pureinku receiving layer by applying an aqueous coating solution containing an ink fixing agent And, it causes gelation by the boron-containing compounds, by drying the Pureinku receiving layer to form a dry Pureinku receiving layer, the drying Pureinku receiving layer, while being rewet the surface with the wetting liquid is heated Further, the glossy ink receiving layer is formed by developing the glossiness of the receiving layer by press-contacting with the mirror surface drum and drying.

According to a preferred configuration aspect of the present invention, the amorphous silica of the undercoat layer is composed of secondary particles obtained by agglomerating primary particles composed of simple silica, and an average particle diameter thereof is 1.0 to 7.0 μm. . Moreover, content of the adhesive agent of the said undercoat layer is 55-100 mass parts with respect to 100 mass parts of said amorphous silica. Furthermore, the undercoat layer has a dry coating amount of 7 to 9 g / m ² .

In the present invention, amorphous silica of the Pureinku receiving layer is made from the secondary particles in which primary particles are aggregated, the mean particle diameter of 90～700Nm. Polyvinyl alcohol of the Pureinku receiving layer, the degree of polymerization of Ru der 3500-5000. Moreover, according to a preferable structure aspect, the content is 10-20 mass parts with respect to 100 mass parts of amorphous silica.
The pre-ink receiving layer has a dry coating amount of 15 to 20 g / m2.

According to still another preferred aspect of the present invention, the boron-containing compound has a dry coating amount of 0.01 to 2.0 g / m ² .

The glossy ink receiving layer of the present invention is a glossy ink receiving layer as a final form by changing the form of the ink receiving layer having the same composition through a series of manufacturing steps.
Therefore, the ink receiving layer forming the coating layer in the manufacturing process is referred to as a pre-ink receiving layer, and the dried state is referred to as a dry pre-ink receiving layer. Is referred to as a glossy ink receiving layer.
In silica, primary particles refer to simple particles, and secondary particles refer to aggregate particles formed by agglomerating primary particles.

  According to the present invention, the glossy ink receiving layer does not crack, and not only has good recording properties for dye inks, but also has excellent ink absorbency, print density, and print gloss of the pigment ink, Glossy ink jet recording paper can be obtained in which dye ink and pigment ink can be shared, and generation of paper dust is suppressed.

A method for producing a glossy ink jet recording paper according to the present invention will be described in detail based on the following embodiments.
The method for producing a glossy ink jet recording paper according to the present embodiment is a method for producing a glossy ink jet recording paper having a coating layer comprising an undercoat layer and a glossy ink receiving layer whose surface is cast on a support.
Hereinafter, the support, the undercoat layer, and the pre-ink receiving layer used in the production method of the present embodiment will be described in detail.

<Support>
In the method for producing the glossy ink jet recording paper of the present embodiment, a support having air permeability is used.
As this air-permeable support, a commonly used known paper base material can be used. For example, fine paper, art paper, coated paper, cast coated paper, kraft paper, baryta paper, paperboard, impregnated paper In addition, acid paper, neutral paper, and the like used for vapor-deposited paper and general coated paper are appropriately used.
The paper base material contains wood pulp as a main component, and fillers, various auxiliaries and the like are added as necessary.

The outline | summary of these paper base materials is demonstrated.
As the wood pulp, various chemical pulps, mechanical pulps, recycled pulps and the like can be used.
These pulps can be adjusted in beating degree (freeness), and the freeness is preferably 250 to 550 ml (CSF: JIS-P-8121), more preferably 300 to 500 ml.

As the filler added to the paper substrate, for example, calcium carbonate, calcined kaolin, silica, titanium oxide and the like are preferably used. Among these, calcium carbonate is preferable because a paper base material with high whiteness is obtained and glossiness of the ink jet recording paper is enhanced.
As for the content rate (ash content) of the filler in a paper base material, about 1-20 mass% is preferable, More preferably, it is 3-20 mass%.
Within this range, smoothness, air permeability, and paper strength are balanced, and it becomes easy to obtain a glossy inkjet recording paper excellent in glossiness and image sharpness.

Examples of the auxiliary agent added to the paper substrate include a sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improver, a dye, and a fluorescent brightening agent.
The Stechitto sizing degree of the paper base (100 g / m ² paper) is preferably about 1 to 200 seconds, and more preferably 4 to 150 seconds.
The basis weight of the paper substrate is not particularly limited, but is preferably about ²⁰ to 400 g / m ² .
The Oken type air permeability of the paper substrate is preferably 10 to 350 seconds. 10 to 200 seconds are more preferable, and 20 to 100 seconds are more preferable.
If the air permeability is less than 10 seconds, the coating solution for the undercoat layer excessively penetrates into the support made of the paper base material, and the steam on the cast drum is formed on the paper base material during the casting process. This is not preferable because it concentrates on the thin portion of the sheet and the surface tends to be uneven. On the other hand, if the air permeability exceeds 350 seconds, it is not preferable because the operability is lowered when press-finishing the cast drum.

<Undercoat layer>
In the method for producing the glossy ink jet recording paper of the present embodiment, an undercoat layer is provided on the support.
The undercoat layer contains amorphous silica of secondary particles having an average particle size of 10 μm or less as a pigment, and an adhesive containing at least one selected from a water-soluble adhesive and a water-dispersible adhesive as a binder.
By providing this undercoat layer on the support, the glossy ink jet recording paper produced according to the present embodiment has excellent ink absorbability, excellent print density, print bleeding, solid uniformity, and the like. Become.

[Pigment]
The average particle diameter of the secondary particles in the amorphous silica of the present embodiment is a particle diameter obtained by observing the silica particles in the silica aqueous dispersion with an electron microscope (SEM, TEM), and the Martin diameter of the silica dispersed particles. Is measured and averaged. (See "Particle Handbook", Asakura Shoten, p. 52, 1991)).
The average particle diameter of the amorphous silica is required to be 10 μm or less, and the amorphous silica is particularly preferably secondary particles having an average particle diameter of 1 to 7 μm. When the average particle size is less than 1 μm, the ink absorption rate decreases and the strength of the undercoat layer also decreases. When the average particle size exceeds 7 μm, the glossiness and ink absorption when the ink receiving layer surface is cast finished. Sex is not enough.

In the undercoat layer, not only the above-mentioned amorphous silica but also known pigments that are usually used can be used in combination as long as the effects of the present invention are not impaired.
Examples of these pigments include kaolin, clay, calcined clay, zinc oxide, aluminum oxide, titanium oxide, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, Examples thereof include styrene plastic pigments, hydrotalcite, urea resin plastic pigments, and benzoguanamine plastic pigments. The pigments used in combination selected from these may be used alone or in combination of two or more.

〔adhesive〕
For the undercoat layer, a known adhesive containing at least one selected from a commonly used water-soluble adhesive and water-dispersible adhesive is used as a binder.
Examples of the adhesive include, for example, proteins such as casein, soybean protein, and synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohol, cationic polyvinyl alcohol, and modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol. Alcohols, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, water-soluble adhesives such as aqueous polyurethane resins and aqueous polyester resins, styrene-butadiene copolymers, conjugated diene polymer latexes of methyl methacrylate-butadiene copolymers, acrylics And water-dispersible adhesives such as vinyl polymer latexes such as ethylene polymer latex and ethylene-vinyl acetate copolymer.
The adhesive selected and used from these may be used alone or in combination of two or more.

  The adhesive for the undercoat layer is preferably 55 to 100 parts by mass, more preferably 60 to 90 parts by mass with respect to 100 parts by mass of the amorphous silica. If the amount is less than 55 parts by mass, the generation of paper dust cannot be sufficiently suppressed.

In addition to the components described above, various auxiliary agents such as dispersants, thickeners, antifoaming agents, antistatic agents, preservatives and the like that are used in general recording paper production can be appropriately added to the undercoat layer.
In addition, fluorescent dyes, colorants and the like can be added.

[Method for producing undercoat layer]
The dry coating amount of the undercoat layer is 7 to 9 g / m ² .
When the dry coating amount is less than 7 g / m ² , the ink absorbability is not sufficient, and when it exceeds 9 g / m ² , a sufficient print gloss cannot be obtained.

The undercoat layer is produced by applying an undercoat layer coating solution comprising the above-described components onto the support and drying it. The solid content concentration of the undercoat layer coating solution is preferably 5 to 50% by mass.
As a coating method for the coating solution for the undercoat layer, various known methods such as a blade coater, an air knife coater, a roll coater, a brush coater, a Chanplex coater, a bar coater, a lip coater, a gravure coater, a curtain coater, a slot die coater, a slide coater, etc. A coating method using any of the coating apparatuses can be used.
Further, the coated undercoat layer may be subjected to a smoothing process such as super calendering or brushing as necessary.

The surface of the undercoat layer contains an ink fixing agent and is cross-linked with an adhesive contained in the pre-ink receiving layer to prevent cracking of the pre-ink receiving layer described later provided for fixing an ink image. A cross-linking agent is applied.
The crosslinking agent is applied on the undercoat layer as an aqueous coating solution dissolved in water.
As this crosslinking agent, there are various known gelling agents that crosslink the adhesive and gel as well as the known crosslinking agent having crosslinkability to the adhesive. In this embodiment, the crosslinking with the adhesive is performed. Boron-containing compounds such as boric acid and borax, which are gelled and rapidly thicken or gelled, are used.

Here, the boron-containing compound is an oxygen acid having a boron atom as a central atom and a salt thereof. Specific examples include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid, and sodium, potassium and ammonium salts thereof. Among these, orthoboric acid and disodium tetraborate are preferably used because they have an effect of increasing the viscosity of the coating solution to an appropriate degree.
The compounding amount of the boron-containing compound depends on the type of the boron-containing compound and the degree of polymerization of the polyvinyl alcohol, and is determined in consideration of these. However, the boron-containing compound on the undercoat layer is 0 by dry coating amount. It is preferable that 0.01-2.0 g / m ^{2 is} applied.
When the coating amount of the boron-containing compound is less than 0.01 g / m ² , the crosslinking property with the hydrophilic adhesive and the gelation of the coating solution are not sufficient, and the coating layer is cracked. Further, if it exceeds 2.0 g / m ² , it is not preferable because the ink absorbability is lowered and the coating layer cracks easily occur during printer conveyance.

As the cross-linking agent, a known cross-linking agent having cross-linkability with respect to the adhesive and a known gelling agent for gelling the adhesive can be used in combination with the boron-containing compound.
These crosslinking agents or gelling agents include, for example, aldehyde-based crosslinking agents such as glyoxal, epoxy-based crosslinking agents such as ethylene glycol diglycidyl ether, and bisvinylsulfonylmethyl ether. Examples of the gelling agent include a vinyl compound such as a zirconium compound, an aluminum compound, and a chromium compound.

<Ink receiving layer>
In the glossy ink jet recording paper of the present embodiment, a pre-ink receiving layer is provided on the boron-containing compound-coated surface coated on the undercoat layer.
This pre-ink-receiving layer is formed by coating a water-based coating liquid on the boron-containing compound-coated surface in a state where a water-based coating liquid containing a boron-containing compound is coated on the undercoat layer or in a state where it is further dried. Formed.
The pre-ink-receiving layer contains, as a pigment, amorphous silica having an average particle diameter of 90 to 700 nm as a secondary particle, polyvinyl alcohol having a polymerization degree of 3500 to 5000 as an adhesive, and an ink fixing agent. And a dry coating amount of 15 to 20 g / m ² .
This pre-ink-receiving layer is changed to a glossy ink-receiving layer through a process described later. The glossy ink jet recording paper of this embodiment having this glossy ink-receiving layer is less likely to generate paper dust and is used as a dye ink. On the other hand, the printing density is high and the water resistance of the ink is excellent. For pigment ink, the printing density is high and the glossiness is high.

[Pigment]
The amorphous silica used in the pre-ink receiving layer is required to have an average particle size of 700 nm or less, and preferably secondary particles having a particle size of 90 to 700 nm. When the average particle diameter is less than 90 nm, the ink absorbency is not sufficient, and when it exceeds 700 nm, the print density and the glossiness of the surface are lowered.
As the amorphous silica, wet method silica and gas phase method silica are used.

  In addition to the above-described amorphous silica, commonly used commonly used pigments such as alumina and colloidal silica can be used in combination with the pre-ink-receiving layer as long as the effects of the present invention are not impaired. These pigments used in combination may be used alone or in combination of two or more.

〔adhesive〕
The polyvinyl alcohol used in the pre-ink-receiving layer needs to have a polymerization degree of 3500 or more, preferably 3500 to 5000. If the degree of polymerization is less than 3500, the strength of the ink receiving layer is weak and cracking is likely to occur, and a sufficient printing density cannot be obtained particularly in a pigment printer. If the degree of polymerization exceeds 5000, sufficient ink is obtained. Absorbability cannot be obtained, and handling in preparation of the coating liquid becomes difficult.

In addition to the polyvinyl alcohol, a known adhesive that is usually used can be used in combination with the pre-ink receiving layer as long as the effects of the present invention are not impaired.
As these adhesives, for example, polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, polyvinyl acetal, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, casein, soybean protein, synthetic proteins, starch, polypropylene oxide, with different degrees of polymerization Examples include polyethylene glycol, polyvinyl ether, polyvinyl acrylamide, polyvinyl pyrrolidone, styrene-butadiene copolymer, methyl methacrylate, and styrene-vinyl acetate copolymer. These adhesives used in combination may be used alone or in combination of two or more.

[Ink fixing agent]
Examples of the fixing agent added to the ink receiving layer include polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, and acrylic polymers having secondary or tertiary amino groups or quaternary ammonium groups. Or copolymers of these acrylamides, polyvinylamines and polyvinylamidines, dicyandication compounds typified by dicyandiamide / formalin copolymers, polyamine cation compounds typified by dicyandiamide / polyethyleneamine copolymers, epichlorohydrin dimethylamine copolymer, diallyldimethylammonium -SO ₂ double condensates, diallylamine salt -SO ₂ double condensates, diallyl dimethyl ammonium chloride polymer, diallyl dimethyl ammonium chloride Acrylamide copolymer, allylamine salt copolymer, dialkylaminoethyl (meth) acrylate quaternary salt copolymer, acrylamide-diallylamine copolymer, dimethylaminopropyl acrylamide polymer, and cationic having 5-membered ring amidine structure Substances and the like.
In this embodiment, since fine amorphous silica having a secondary particle diameter of 90 to 700 nm is used, a tendency to crack is observed. Therefore, as the fixing agent, in order to prevent this, the recording suitability and crack prevention are prevented. The cationic substance having the 5-membered ring amidine structure capable of satisfying both of these requirements is particularly preferred.

By using such a cationic substance having a 5-membered ring amidine structure, cracking is suppressed and sufficient pigment ink suitability is obtained. In addition, the water resistance when dye ink is used is good.
In the pre-ink-receiving layer, the above-mentioned commonly used fixing agent is used alone or in combination of two or more kinds in the cationic substance having the 5-membered ring amidine structure as long as the effects of the present invention are not impaired. You can also.

The polyvinyl alcohol having a polymerization degree of 3500 to 5000 in the pre-ink receiving layer is 10 to 20 parts by mass with respect to 100 parts by mass of the amorphous silica from the viewpoint of maintaining a balance between ink absorbability, coating film strength and crack suppression. Is preferable, it is more preferable that it is 12-16 mass parts, and it is still more preferable that it is 14-15 mass parts.
If the blending amount of the polyvinyl alcohol is less than 10 parts by mass, cracks may occur in the ink receiving layer, and there is a risk of paper dust being generated during cutting due to a decrease in the layer strength. Exceeding the portion is not preferable because the ink absorbability is lowered.

  In addition to the above-mentioned components, the pre-ink receiving layer includes a dispersant, a crosslinking agent, a thickener, an antifoaming agent, an antistatic agent, an antiseptic, an ultraviolet absorber, and a storage stability improving agent used in general recording paper production Various additives such as a fluorescent brightening agent and a coloring agent can be appropriately added.

[Preparation method of pre-ink receiving layer]
The dry coating amount of the pre-ink receiving layer is preferably 15 to 20 g / m ² .
When the dry coating amount is less than 15 g / m ² , excellent gloss and ink absorbability cannot be obtained, and when it exceeds 20 g / m ² , cracks in the coating layer are likely to occur, and the dot perfect circle In addition, the print density of the pigment ink and the dye ink is insufficient.
The pre-ink-receiving layer is produced by applying a pre-ink-receiving layer coating solution comprising the above-described components on the undercoat layer. The solid content concentration of the coating liquid for the pre-ink receiving layer is preferably 5 to 50% by mass, and more preferably 5 to 20% by mass. When the solid content concentration is less than 5% by mass, the drying efficiency of the pre-ink receiving layer is low, and when it exceeds 50% by mass, the coating layer is liable to crack.
Examples of the coating method for the pre-ink receiving layer coating solution include blade coaters, air knife coaters, roll coaters, brush coaters, Champlex coaters, bar coaters, lip coaters, gravure coaters, curtain coaters, slot die coaters, slide coaters, sprays, etc. A coating method in which coating is performed using any of various publicly known coating apparatuses can be used.
The coated pre-ink receiving layer is dried to form a dry pre-ink receiving layer.

[Cast finish]
The pre-ink receiving layer in the present embodiment is dried to form a dry pre-ink receiving layer, and further, a wetting liquid is applied to the surface, and the surface is cast finished to form a glossy ink receiving layer having excellent gloss.
Here, casting the surface of the pre-ink receiving layer means that the pre-ink receiving layer to which the wetting liquid is applied is pressed against the cast drum in a wet state to transfer the smooth drum surface to the surface of the pre-ink receiving layer. That means.
Cast finish in this embodiment, have a row of slightly dried after coating the Pureinku receiving layer coating solution, or to form a dry Pureinku receiving layer dried rows Do I, the surface of these dry Pureinku receptive layer A method of applying a wetting liquid to the cast drum and press-contacting the cast drum is used.
Such a method of applying a wetting liquid to the dry pre-ink receiving layer and performing a cast finish is particularly referred to as a rewet cast process.

Water is used for the wetting liquid, but if necessary, synthetic resin latex such as styrene-butadiene latex and methyl methacrylate-butadiene copolymer latex, proteins such as casein, soy protein, synthetic protein, starch and oxidized Various starches such as starch, cellulose derivatives such as polyvinyl alcohol, carboxymethylcellulose and methylcellulose, various thickeners such as polycarboxylic acid, polyacrylic acid, acrylic emulsion, polyamide, polyester, alkali thickener and nonionic surfactant Agent, fluid modifier, sodium chloride, ammonium chloride, zinc chloride, magnesium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, zinc sulfate, magnesium sulfate, ferrous sulfate, sodium nitrate, ammonium nitrate, monobasic sodium phosphate, phosphorus Ammonium, calcium phosphate, sodium polyphosphate, sodium hexametaphosphate, sodium formate, ammonium formate, sodium acetate, potassium acetate, sodium monochloroacetate, sodium malonate, sodium tartrate, potassium tartrate, potassium citrate, sodium lactate, sodium gluconate , Ammonium salts and metal salts of inorganic and organic acids such as sodium adipate, sodium dioctylsulfosuccinate and sodium aluminate, as well as methylamine, diethanolamine, diethylenetriamine, diisopropylamine, triethanolamine, ethanolamine, ethanolamine, etc. Amines, phosphates, polyoxyethylene alkylphenol ether phosphates, polyoxyethylene ethers Phosphate esters such as acid ester salt, alkylphenol ether phosphate ester salt, polyoxyethylene, alkyl ether, polyoxyethylene and ammonia water, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycyl ether, polypropylene Contains various additives such as polyfunctional epoxy compounds such as glycol diglycidyl ether and adipic acid diglycidyl ester, various water-proofing agents such as urea-formaldehyde, polyamide-epichlorohydrin, and glyoxal, and printing suitability improvers Can be made.
Various additives are added to the wetting liquid in an amount of 0.05 to 10% by mass, preferably 0.1 to 5% by mass.
Furthermore, various auxiliary agents such as a dispersant, an antifoaming agent, a colorant, a fluorescent dye, an antistatic agent, and an antiseptic can be added as appropriate to the wetting liquid.
In addition, pigments such as alumina, colloidal silica, fine silica, clay, and calcium carbonate can also be added as auxiliary agents.

When the dry pre-ink receiving layer surface is cast-finished, it is preferable to use a release agent in order to smoothly peel the dry pre-ink receiving layer from the cast drum.
The release agent is preferably used by any one of a method of adding to the pre-ink receiving layer coating solution, a method of applying to the cast drum surface, and a method of adding to the wetting solution.
Examples of the mold release agent include higher fatty acid amides such as stearic acid amide and oleic acid amide, polyolefin waxes such as polyethylene wax, polyethylene oxide wax, and polypropylene wax, calcium stearate, zinc stearate, potassium oleate, and ammonium oleate. Higher fatty acid alkali salts, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene. Among these, a cationic release agent is particularly preferably used.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. Further, “parts” and “%” are solid contents excluding water unless otherwise specified, and indicate mass parts and mass%, respectively.

The outline of the manufacturing method of each ink jet recording paper is as follows.
First, a support is prepared, and then a coating layer composed of an undercoat layer and a glossy ink receiving layer is formed.
First, an undercoat layer coating solution is prepared, and this coating solution is applied onto a support to produce an undercoat layer. Thereafter, an aqueous borax solution and a separately prepared pre-ink receiving layer coating solution are sequentially applied onto the undercoat layer, cast finish is performed, and a glossy ink receiving layer is formed to produce a glossy inkjet recording paper.
The average particle size of the amorphous silica of the secondary particles was prepared by preparing 200 g of a 3% silica water dispersion, followed by stirring and dispersing with a high-speed flow collision type homogenizer at 1000 rpm for 30 minutes, and then immediately using an electron microscope (SEM and (TEM) and observed.

Example 1
<Production of support>
Wood pulp (LBKP: freeness 440 ml CSF) 100 parts, filler (calcium carbonate 3: talc 1 ratio) 15 parts, commercially available sizing agent (trade name: Fibran 81K, manufactured by NSC Japan) 0.05 part , Using a papermaking material consisting of 0.45 parts of sulfuric acid band, 0.45 parts of starch, 0.4 parts of polyamide / epichlorohydrin resin (paper strength enhancer) and a little yield improver, and basis weight on a long net paper machine After obtaining a paper substrate of 188 g / m ^2, a supercalender treatment was performed at a linear pressure of 150 kg / cm to prepare a support. The obtained support had a thickness of 210 μm and an air permeability of 30 seconds.

<Preparation of undercoat layer>
The undercoat layer coating solution shown below was applied onto the support with an air knife coater and dried so that the dry coating amount was 8 g / m ² to prepare an undercoat layer.
(Preparation of coating solution for undercoat layer)
Synthetic amorphous silica as amorphous silica (trade name: Fine Seal X-45, manufactured by Tokuyama Corporation, secondary particles with an average particle size of 4.5 μm), silyl-modified polyvinyl alcohol (trade name: R1130, polyvinyl alcohol) Kuraray Co., Ltd.) 80 parts, fluorescent dye (trade name: Whiteex BPS (H), manufactured by Sumitomo Chemical Co., Ltd.), 2 parts, cationic compound comprising diallyldimethylammonium chloride polymer (trade name: Unisense CP-102, Senka Company) Manufactured, ink fixing agent) 5 parts were mixed to prepare an undercoat layer coating solution having a solid content of 15%.

<Preparation of glossy ink receiving layer>
A 3% by mass borax aqueous solution as a boron compound was applied onto the undercoat layer so that the dry coating amount was 1.5 g / m ^2, and it was not dried, and then was 17 g / m ^{2 in} an absolutely dry mass. The following pre-ink receptive layer coating solution was applied with a die coater, dried with hot air at 150 ° C. so that the equilibrium moisture content was 8%, and then wetted with water to obtain a surface temperature. A wet ink jet recording sheet having a glossy ink receiving layer was manufactured by press-contacting a cast drum at 100 ° C. with a linear pressure of 200 kg / cm to carry out rewet casting.
[Preparation of coating liquid for pre-ink receiving layer]
A commercially available gas phase method silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, primary particles having an average particle diameter of 9 nm, specific surface area of 300 m ² / g) is used as amorphous silica, and is pulverized and dispersed with a high-speed flow collision type homogenizer. Was repeated to obtain secondary particles, and after classification, a 10% silica dispersion having an average particle diameter of 200 nm was prepared.
A cationic substance having a five-membered ring amidine structure as an ink fixing agent (trade name: Himax SC-700M, manufactured by Hymo Co., Ltd., molecular weight 30,000) on 100 parts of the vapor phase silica in terms of solid content of the silica dispersion. ) 10 parts, 15 parts polyvinyl alcohol (trade name: PVA145, manufactured by Kuraray Co., Ltd., polymerization degree 4500), 1 part polyethylene wax (trade name: Pertol N856, manufactured by Modern Chemical Industry, cationic) as a release agent, A coating liquid for a pre-ink receiving layer was prepared.

(Example 2)
After preparing the undercoat layer of Example 1, a 3% by mass borax aqueous solution was applied onto the undercoat layer so that the dry coating amount was 1.5 g / m ^2, and then equilibrated with hot air at 100 ° C. A glossy ink jet recording paper was produced in the same manner as in Example 1 except that drying was performed so that the water content was 8%.

(Example 3)
A glossy ink jet recording paper was produced in the same manner as in Example 1 except that the average particle diameter after classification of vapor-phase process silica used in the pre-ink-receiving layer coating liquid of Example 1 was 600 nm.

Example 4
Except for replacing polyvinyl alcohol used in the coating liquid for the pre-ink-receiving layer of Example 1 with 15 parts of polyvinyl alcohol having a low polymerization degree (trade name: PVA135H, manufactured by Kuraray Co., Ltd., polymerization degree 3500), the same as in Example 1 Thus, a glossy ink jet recording paper was produced.

(Example 5)
Example 1 except that 1% of polyethylene wax (trade name: Pertol N856, manufactured by Modern Chemical Industries, Ltd., cationic) is included in the wetting liquid when performing the rewet casting process of Example 1. Similarly, glossy inkjet recording paper was produced.

(Example 6)
The undercoat layer coating solution of Example 1 was made of amorphous silica as amorphous silica (trade name: Silojet 703A, Grace Devison, secondary particles having an average particle size of 300 nm), 100 parts of polyvinyl alcohol (trade name). : PVA145 Kuraray 80 parts, fluorescent dye (trade name: Whitetex BPS (H), manufactured by Sumitomo Chemical Co., Ltd.) 2 parts, cationic compound composed of diallyldimethylammonium chloride polymer as an ink fixing agent (trade name: Unisense CP102) Gloss inkjet recording paper was produced in the same manner as in Example 1 except that 5 parts were prepared by mixing, and the undercoat layer coating solution having a solid content of 15% was prepared and used.

(Example 7)
Polyethylene wax (trade name: Pertol N856, manufactured by Modern Chemical Industry, cationic) as a release agent in the wetting liquid when carrying out the rewet casting process of Example 1 and polyvinyl alcohol (trade name: PVA117) Glossy ink jet recording paper was produced in the same manner as in Example 1 except that 1% of Kuraray Co., Ltd. was included.

(Example 8)
A glossy ink jet recording paper was produced in the same manner as in Example 1 except that 15 parts of polyvinyl alcohol (trade name: PVA124, manufactured by Kuraray Co., Ltd., polymerization degree 2400) used for the pre-ink receiving layer was added.

(Comparative Example 1)
After coating the undercoat layer in Example 1, after coating a 17 g / m ² in coating liquid solid content Pureinku receiving layer coating liquid, immediately pressed against the casting drum having a surface strength 80 ° C. (direct method) A glossy ink jet recording paper was produced.

(Comparative Example 2)
Instead of the rewet casting process of Example 1, the coating liquid for the pre-ink receiving layer was again applied at a coating liquid solid content of 1 g / m ^{2 and} applied to a cast drum having a surface temperature of 100 ° C. at a linear pressure of 200 kg / cm. The glossy ink jet recording paper was manufactured by press-contacting and casting.

(Comparative Example 3)
Gloss as in Example 1 except that the amorphous silica used in the undercoat layer is 100 parts of synthetic amorphous silica (trade name: Fine Seal X-15, secondary particles with an average particle size of 11 μm, manufactured by Tokuyama Corporation). Inkjet recording paper was produced.

(Comparative Example 4)
As the amorphous silica of the coating liquid for the pre-ink-receiving layer, commercially available gas phase method silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, primary particles having an average particle diameter of 9 nm, specific surface area of 300 m ² / g) is used. Glossy ink jet recording paper was produced in the same manner as in Example 1 except that secondary particles were repeatedly pulverized and dispersed with a high-speed collision type homogenizer, and after classification, a 10% silica dispersion having an average particle diameter of 900 nm was used.

<Evaluation method and evaluation criteria>
About the glossy inkjet recording paper manufactured by the said Example and the comparative example, the printability in inkjet recording and the physical property of a coating layer were evaluated by the following method.

[Printability in inkjet recording]
The evaluation of printability was evaluated by using each type of printer of dye ink and pigment ink according to each item of print density, ink absorbency, and glossiness of the printed portion.

Evaluation printer Printer A: Commercially available dye ink type ink jet printer (trade name: PM-G800, manufactured by Seiko Epson Corporation)
Printer B: Commercially available pigment ink type ink jet printer (trade name: PM-G900, manufactured by Seiko Epson Corporation)

(Print density)
Black solid printing was performed using printer A (dye ink type) and printer B (pigment ink type), and the printing density was measured with an X-light reflection densitometer (938 spectrodensitometer).

(Ink absorption)
Using printer A (dye ink type), printing is performed with black, cyan, magenta, yellow, red, green, and blue solid colors arranged in a grid pattern so as to touch each other. The ink bleeding was evaluated visually according to the following criteria.
(Double-circle): The blur of printing is not recognized at all and it is an excellent level.
○: Slight bleeding is observed, but there is no practical problem.
Δ: Slightly blurring of printing and slightly problematic in practical use.
X: The level at which printing blur is remarkable and becomes a serious problem in practical use.

(Glossiness of printed part)
Printing of photographic images (high-definition color digital standard image (XYZ / SCID) data compliant with JIS X 9204, image identification code: N1, image name: glass and female) using printer A (dye ink type) The uniformity of the printed part was visually evaluated according to the following criteria.
A: Excellent level with no unevenness in printed gloss on the entire image.
○: The print glossiness is slightly lower at the dark print color development, but it does not cause a problem overall.
×: Level at which printing gloss partially disappears and becomes a serious problem in practical use.

[Physical properties of coating layer]
The physical properties of the coating layer were evaluated based on the glossiness, strength, and cracking items of the coating layer.
(Glossy)
Glossiness was evaluated by visually observing glossiness and smoothness from the lateral direction with respect to the surface of the blank recording paper according to the following criteria.
A: Extremely high gloss.
○: Glossy.
X: The glossiness is inferior.

(Layer strength)
After printing on the entire surface with printer A (black), after storing in an environment of 23 ° C. and 50% RH for 24 hours, when cutting the paper from the recording surface side with an NT cutter knife (A-300) Check the cut surface visually. The direction when cutting with a cutter knife is the same.
○: No peeling of the coat layer. It remains colored to the cut end.
X: The coat layer peeled off, and the color fell along the cut edge.

(Layer crack)
After printing on the entire surface with printer B (black), it is stored for 24 hours in an environment of 23 ° C. and 50% RH, and then white spots of the print are visually evaluated. As the number of cracks increases, the pigment ink falls between the cracks and white spots increase.
A: There are no white spots. (No cracks and no problems.)
○: There are almost no white spots. (There are almost no cracks and practically no problem)
Δ: Sparse white spots. (Cracks occur and there is a problem level.)
X: White spots have occurred on one side. (Highly cracked and problematic level)

  The evaluation results are shown in Table 1.

As shown in Table 1, it can be seen that Examples 1 to 8 are at or above levels at which there is no practical problem in each evaluation item, and are excellent in printability in ink jet recording and physical properties of the coating layer. .
On the other hand, all of Comparative Examples 1 to 4 are evaluated to a problem level in any of the evaluation items and are clearly inferior to the Examples.

Claims (7)

An aqueous coating solution having a pigment containing amorphous silica having an average particle diameter of 10 μm or less on an air-permeable support and an adhesive containing at least one selected from a water-soluble adhesive and a water-dispersible adhesive. Apply and dry to form an undercoat layer,
On the undercoat layer, a boron-containing compound-coated surface in a state where a water-based coating solution containing a boron-containing compound is applied or in a state where it is further dried is formed,
Gas phase method silica or wet method silica, which are secondary particles having an average particle diameter of 90 to 700 nm , polyvinyl alcohol having a polymerization degree of 3500 to 5000 as an adhesive , and ink A pre-ink-receiving layer is formed by applying an aqueous coating solution containing a fixing agent,
With gelling by the boron-containing compound, to form a dry Pureinku receiving layer by drying the above Pureinku receiving layer,
The dry pre-ink-receiving layer is dried by being pressed against a heated mirror drum while the surface is rewet with a wetting liquid to form a glossy ink-receiving layer.
A method for producing a glossy ink jet recording paper. The amorphous silica of the undercoat layer is composed of secondary particles obtained by agglomerating primary particles composed of simple silica, and the average particle diameter thereof is 1 to 7 μm.
The method for producing a glossy ink jet recording paper according to claim 1. The content of the adhesive in the undercoat layer is 55 to 100 parts by mass with respect to 100 parts by mass of the amorphous silica.
The method for producing a glossy ink jet recording paper according to claim 1 or 2. The undercoat layer has a dry coating amount of 7 to 9 g / m ² .
The method for producing a glossy ink jet recording paper according to any one of claims 1 to 3. The pre-ink receiving layer has an adhesive content of 10 to 20 parts by mass with respect to 100 parts by mass of amorphous silica.
The method for producing a glossy ink jet recording paper according to any one of claims 1 to 4 . The pre-ink receiving layer has a dry coating amount of 15 to 20 g / m ² .
The method for producing a glossy ink jet recording paper according to any one of claims 1 to 5 . The boron-containing compound has a dry coating amount of 0.01 to 2.0 g / m ² .
The method for producing a glossy inkjet recording paper according to any one of claims 1 to 6 .