WO2004106080A1

WO2004106080A1 - Cast ink-jet recording paper

Info

Publication number: WO2004106080A1
Application number: PCT/JP2003/006685
Authority: WO
Inventors: Mitsuru Kobayashi; Shinichi Asano; Motoko Hiraki
Original assignee: Oji Paper Co., Ltd.
Priority date: 2003-05-28
Filing date: 2003-05-28
Publication date: 2004-12-09
Also published as: CN1771134A; AU2003241838A1

Abstract

A cast ink-jet recording paper such that the gloss of the white paper portion and printing portion where a record image is formed with an aqueous ink is excellent, the density of the image printed in full color is high, the heat resistance and ozone resistance are excellent, and the continuous operating rate is high. An undercoating layer is formed on a base. The undercoating layer contains a pigment, a copolymer of diallyl amine and (meth)acryl amide, a copolymer of diallyl amine, (meth)acryl amide, and a vinyl monomer copolymerizable with them and substantially not containing a carboxyl group, a cationic compound which is at least one kind selected from the group consisting of salts of them, and an adhesive. A cast layer is formed on the undercoating layer. The cast layer contains an adhesive, a fine pigment the mean secondary particle diameter of which is below 1 μm, and a releasing agent which is at least one kind selected from the group consisting of fatty acids having 12 to 18 carbon atoms and their water-soluble salts.

Description

Description Cast inkjet recording paper Technical field

The present invention relates to a photographic ink-jet recording paper having excellent gloss on a blank portion and a printing portion on which a recorded image is formed by using a water-based ink, and in particular, for a full-color image printed on an ink-jet recording paper. The present invention relates to a cast-in jet recording paper which has a high print density, maintains ink absorbency, has excellent heat resistance and ozone resistance, and has excellent continuous operability. Background art

The ink jet recording method, in which water-based ink is ejected from a fine nozzle onto the ink jet recording paper to form an image, has low noise, enables high-speed recording, is easy to colorize, and has other features. Because they are cheaper than printing devices, they are used in a variety of applications, including terminal printers, facsimile machines, plotters, and form printing. As ink jet recording paper, high-quality paper devised to be rich in ink absorbency, and coated paper having a surface coated with a porous pigment are used. However, since all of these inkjet recording papers are mainly ink-jet recording papers with a low surface gloss, so-called matte tone, there is a demand for photographic ink-jet recording papers with high surface gloss and excellent appearance. . In recent years, with the advancement of high-definition and high-speed printer technology and the high image quality of digital cameras, high-gloss inkjet recording paper is also preferred as inkjet recording paper. At the same time, advanced properties are required for inkjet recording paper, such as white paper and print gloss, ink absorption, image recording density, water resistance, light resistance, ozone resistance, heat resistance, etc. There is a strong demand for inkjet recording paper that is excellent in quality and comparable to the silver halide method. By the way, generally, recording paper having a high surface gloss is coated with a plate-like pigment on the surface and, if necessary, subjected to a calender treatment, and is coated with high gloss or wet coating. A so-called cast coated paper obtained by pressing and drying the layer on a heated drum surface having a mirror surface and copying the mirror surface is known, and is widely used as various printing papers.

The cast coated paper has higher surface gloss and better surface smoothness than a normal calender-finished coated paper, so that an excellent printing effect can be obtained. It is used exclusively for high-quality printed materials, etc., and has the same glossiness when used for inkjet recording paper, and is attracting attention as a relatively inexpensive recording medium among photographic ink jet recording papers. . A number of methods have been proposed to produce high-quality glossy ink jet recording paper satisfying the above characteristics by the cast coating method. In JP-A-62-95285, ink absorption is fast, drying is excellent, dimensional changes due to moisture absorption and dehumidification during recording and storage are unlikely to occur, and the area around the dot is A cast ink jet recording paper which is sharp, has a high resolution, and has a high smoothness and gloss on the coated surface is disclosed. Japanese Patent Application Laid-Open No. 63-264391 discloses a good ink absorption. In addition, a cast ink jet recording paper having both glossiness, water resistance of a recorded image, and dimensional stability has been disclosed. Japanese Patent Application Laid-Open No. Hei 2-274758 discloses a multicolor ink jet using a water-based ink. Japanese Patent Application Laid-Open No. 5-9694 discloses a cast ink jet recording paper suitable for printing on ink, which is excellent in ink absorbency, smoothness and glossiness of the recording paper surface, and water resistance of the recording paper. Excellent density, sharpness and roundness, Japanese Patent Application Laid-Open No. 8-332771 discloses a cast ink jet recording paper capable of recording a full-color image with high image quality and high gradation, which is excellent in both ink absorption and productivity. Japanese Patent Application Laid-Open No. 2000-212128 discloses a cast ink jet recording paper having a high glossiness on the recording surface, a glossy smoothness close to that of a photograph, a high print density, excellent print water resistance, and excellent print water resistance. Also disclosed are methods for producing cast ink jet recording paper that maintain the fixability, absorbency, etc. of the ink jet ink.

The features of these production methods are, in each case, a pigment mainly composed of synthetic silica, High-gloss coating is achieved by applying a recording layer coating liquid mainly composed of an adhesive and a coating to the heated mirror drum while the layer obtained by coating is wet, and then drying it. but it is intended to obtain a cast ink di Etsu preparative recording sheet, the coating amount of the recording layer in these Cass Twink di. Etsu DOO recording paper, in both cases as high as ^{1 5~ 3 0 g / m 2} , the wet coating As in the case of normal cast coated paper production, it is not easy to evaporate and dry a large amount of water in the coating layer from the coating layer side through the paper base material on the non-coated side, resulting in increased productivity. There was a drawback that it was extremely low.

Furthermore, in the method for producing the cast ink jet recording paper obtained by the above method, the cast ink jet recording paper is not sufficiently peelable from the metal surface of the drum having a mirror-finished surface, resulting in poor continuous operability. There was a disadvantage. For example, such a cast inkjet recording paper generally has a bulky coating layer structure, so that the surface strength of the coating layer is lower than that of the cast coating paper used as printing paper. Low. Therefore, when the coating layer is pressed against the heated mirror drum and is dried, a part of the coating layer remains on the mirror drum, and there is a problem that the mirror drum surface becomes cloudy in proportion to the operation time. At the same time, it becomes difficult to separate the cast inkjet recording paper from the mirror surface of the drum, and as a result, the gloss of the cast inkjet recording paper is reduced. Therefore, it was necessary to temporarily stop the operation and remove the dirt on the metal surface of the mirror drum, which was a problem in the operation.

In order to solve this problem, it is common practice to improve the operability by incorporating a release agent into the casting layer coating liquid. As a release agent for improving operability, a release agent used in the production of ordinary coated paper for printing or cast coated paper for printing can be used. In order to improve ozone properties, it is necessary to select an excellent release agent that can withstand these quality requirements.

Further, in recent years, there has been a strong demand for improvement in the preservability of the ink jet recording paper, and JP-A No. 1-77572 discloses an example in which the water resistance and the light resistance are particularly improved. This discloses that storage stability is improved by containing a cationic compound having a specific structure. Disclosure of the invention

The present invention relates to a photographic ink-jet recording paper having excellent glossiness of a blank portion and a printing portion on which a recorded image is formed using a water-based ink, and in particular, an image printed in full color on an ink-jet recording paper. An object of the present invention is to provide a cast ink jet recording paper having a high print density, excellent heat resistance and excellent ozone resistance, and excellent continuous operation.

The present invention employs the following configuration in order to solve the above problems.

That is, the present invention

(1) An undercoat layer containing a pigment, a cationic compound and an adhesive is provided on a base material. The undercoat layer contains an adhesive, a fine pigment having an average secondary particle diameter of less than 1 m, and a release agent. In a cast ink jet recording paper provided with a cast layer, the cationic compound may be a copolymer of diarylamine and (meth) acrylamide, diarylamine and (meth) acrylamide, and another polymer copolymerizable with these. A copolymer with a monomer that does not substantially contain a carboxyl group, or at least one selected from the group consisting of salts thereof, and wherein the release agent has 12 carbon atoms. A cast ink jet recording paper containing at least one selected from the group consisting of a fatty acid and a water-soluble salt thereof.

The present invention includes the following aspects.

(2) The cast inkjet recording paper according to (2), wherein the release agent is at least one selected from the group consisting of stearic acid, oleic acid, a water-soluble salt of stearic acid, and a water-soluble salt of oleic acid.

(3) The cast ink jet recording paper according to (1) or (2), wherein the cationic compound is contained in an amount of 1 to 100 parts by mass with respect to 100 parts by mass of the pigment.

(4) The cast ink jet recording paper as described in any of (1) to (3), wherein the release agent is contained in an amount of 0.1 to 10 parts by mass based on 100 parts by mass of the fine pigment.

{The cast ink jet recording paper according to any one of <1> to <4>, wherein at least one of the undercoat layer and the cast layer contains an organic compound. (4) The cast ink jet recording paper according to any one of (1) to (5), wherein the cast layer surface has a 75 ° surface glossiness (glossiness based on JIS-Z8741) of 50% or more. BEST MODE FOR CARRYING OUT THE INVENTION The present inventors provided an undercoat layer containing a pigment, a cationic compound and an adhesive on a base material, and provided an adhesive and an average secondary particle on the undercoat layer. In an ink jet recording paper provided with a fine pigment having a diameter of less than 1 μm and a casting layer containing a release agent, the cationic compound is a copolymer of diarylamine and (meth) acrylamide, diarylamine. And a copolymer of (meth) acrylamide and another vinyl monomer copolymerizable therewith and substantially not containing a carboxyl group, or a salt thereof. Use at least one selected from the group consisting of fatty acids having 12 to 18 carbon atoms and water-soluble salts thereof as a mold release agent for the cast layer. More, the printing density of the image rather high, while maintaining ink absorbency excellent heat resistance Ya ozone resistance, was found to further cast Inkjet recording sheet excellent in continuous operation can be obtained. The continuous operability here means that there is no pick-shaped coating defect on the surface of the cast ink jet recording paper, and the mirror drum is not so dirty that the operation must be interrupted. is there.

Base material:

The substrate used in the present invention is not particularly limited, and is a paper substrate such as acidic paper or neutral paper used for general coated paper, or a resin film having air permeability. Can be used.

The paper base is composed mainly of wood pulp and, if necessary, pigment. As the wood pulp, various chemical pulp, mechanical pulp, recycled pulp and the like can be used, and the degree of beating of these pulp can be adjusted by a beating machine in order to adjust paper strength, papermaking suitability, and the like. The degree of freeness (freeness) of the pulp is not particularly limited, but is generally 250 to 5 It is about 50 ml (CSF: JIS -P- 8 1 2 1). Also, chlorine-free pulp such as so-called ECF and TCF pulp can be preferably used. If necessary, the pigment is blended for the purpose of imparting opacity or the like, or adjusting the ink absorbency, and calcium carbonate, calcined kaolin, silica, titanium oxide, or the like can be used. In this case, the amount is preferably about 1 to 20% by mass, and if it exceeds 20% by mass, the paper strength may be reduced. As auxiliaries, a sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a retention improver, a dye, a fluorescent whitening agent and the like can be added. Furthermore, in the size press process of a paper machine, starch, polybutyl alcohol, a cationic compound, and the like can be applied and impregnated to adjust the surface strength, degree of steak size, and the like. In particular, in order to obtain a sufficient brightness, it is preferable to size-press the cationic compound. The degree of steak size is preferably about 1 to 200 seconds. If the stick size is less than 1 second, there may be operational problems such as wrinkles during coating.If it is more than 200 seconds, the ink absorbency will decrease or ink strike-through will occur. Curling and cockling after printing may be significant. The basis weight of the base material is not particularly limited, but is about ²⁰ to 400 gZm ² .

Undercoat layer:

In the present invention, an undercoat layer containing a pigment, a cationic compound and an adhesive is provided on a substrate.

Examples of the cationic compound contained in the undercoat layer include a copolymer of diarylamine and (meth) acrylamide, diarylamine and (meth) acrylamide, and other vinyl monomers copolymerizable with these. By containing at least one kind of cationic compound selected from the group consisting of a copolymer containing no carboxyl group or a salt of any of these, storage stability such as gas resistance is improved. More — layers can be improved. Among the monomer units constituting the copolymer, the molar fraction of diarylamine is in the range of 0.1 to 0.99, preferably in the range of 0.15 to 0.95, and (meth) acrylamide The molar fraction is in the range of 0.01 to 0.9, preferably in the range of 0.05 to 0.85, and other vinyl monomers which are copolymerizable therewith, Molar fraction of those containing substantially no carboxyl groups Ranges from 0 to 0.3. A salt of a copolymer containing diarylamine as a part of the monomer is also included, and either an inorganic acid salt or an organic acid salt may be used. If diarylamine is used in the form of a salt, a polymer in the form of a salt can be obtained.

The cationic compound may be used in the undercoat layer in an amount of preferably from 1 to 100 parts by mass, more preferably from 5 to 50 parts by mass, based on 100 parts by mass of the pigment. If the amount is less than 1 part by mass, not only the desired print density, heat resistance and ozone resistance effect cannot be obtained, but also the water resistance of the print may be impaired. On the contrary, not only the print density is reduced, but also the image may be blurred.

In addition, in addition to the above-mentioned cationic compound, the undercoat layer may contain polyalkylene polyamines such as polyethylene polyamine / polypropylene pyrene polyamine used in conventional ink jet recording paper, or derivatives thereof, and tertiary amino groups.カチオン A cationic compound such as acryl resin or diacrylamine having a quaternary ammonium group can be used for the purpose of improving the water resistance of the printed image within a range that does not impair the heat resistance and ozone resistance. it can. .

When the weight-average molecular weight of the cationic compound is about tens of thousands or less, it is generally easy to be eluted in water, and the printing water resistance of a printing portion with a large amount of ink such as mixed color black is inferior. In addition, cationic compounds having a weight-average molecular weight of 100,000 or more are generally hardly eluted in water and, for example, inhibit ink permeation like polybutyl alcohol and the like, and may reduce ink absorption. There is.

When the weight average molecular weight of the cationic compound is 100,000 or more, the printing density of colors such as cyan, magenta, and yellow tends to be high, and when the weight average molecular weight is 50,000 or less, the printing density of the black tends to be high. .

Pigments in the undercoat layer include kaolin, clay, calcined clay, amorphous silica (also called amorphous silica), zinc oxide, aluminum oxide, aluminum hydroxide, carbonated calcium, sachin white, aluminum silicate, alumina, and colloidal silica. , Zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene Pigments known in the general coated paper manufacturing field, such as plastic pigment, hydrotalcite, urea resin-based plastic pigment, and benzoguanamine-based plastic pigment, can be used alone or in combination.

Among these, it is preferable to use amorphous silica, alumina, and zeolite having high ink absorbability as main components.

Examples of the adhesive for the undercoat layer include proteins such as casein, soybean protein, and synthetic protein, various starches such as starch and oxidized starch, polybutyl alcohol, cationic polyvinyl alcohol, and silyl-modified polyvinyl alcohol. Polybutyl alcohols, cenorellose derivatives such as carboxymethylcellulose / methinolecellulose, styrene-butadiene copolymer, conjugated gen-based polymer latex of methyl methacrylate-butadiene copolymer, latex of acryl-based polymer, Conventionally known adhesives generally used for coated paper, such as a butyl polymer latex such as a butyl acetate copolymer, are used alone or in combination. Among them, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, and silyl-modified polyvinyl alcohol are preferably used to improve the surface strength of the undercoat layer. .

The mixing ratio of the pigment and the adhesive in the undercoat layer depends on the type thereof, but is generally 1 to 100 parts by mass, preferably 2 to 50 parts by mass with respect to 100 parts by mass of the pigment. It is adjusted within the range.

In addition, various auxiliaries such as dispersants, thickeners, antifoaming agents, antistatic agents, preservatives, fluorescent dyes, and coloring agents used in the production of general coated paper are appropriately added to the undercoat layer. . The undercoat layer paint composed of the above materials is generally adjusted to have a solid content concentration of about 5 to 50% by mass, and has a dry mass of 2 to 100 g Zm ² , preferably 5 ~ 5 0 g Z m ² approximately, more preferably you applied so that about 5~ ² 0 g / m 2.

When the coating amount is small, the ink absorption is poor, and the bleeding of the recorded image or the gloss after coating the cast layer may be reduced. Further, in the case of a paper base material, the amount of ink absorbed by the paper base material increases, so that the paper after recording has a wavy or G), the press marks (spur marks) due to the printer spurs (paper rolls and gears after recording) may be noticeable.

When the coating amount is large, the ink easily penetrates and is distributed not only on the cast layer side but also on the substrate side, so that the print density may be reduced. In addition, the strength of the undercoat layer may be reduced, and the powder may fall off or the surface may be easily damaged.

The coating for the undercoat layer is applied by various well-known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a brush coater, a champlex coater, a no coater, a lip coater 1, a gravure coater, and a curtain coater. It is dried. Further, if necessary, the recording layer may be subjected to a smoothing process such as super calendering or brushing after drying.

Cast layer:

The cast layer of the present invention comprises an adhesive, a fine pigment having an average secondary particle diameter of 1 μm or less, and a release agent.

The adhesive in the cast layer includes, for example, polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, and other polyvinyl alcohol, casein, soy protein, synthetic protein, starch, and the like. Senorelose derivatives such as carboxylmethyl cellulose methinoresenolylose, vinylinole acetate polymer emulsion, styrene-butadiene copolymer emulsion, ethylene acetate butyl copolymer emulsion, acrylyl copolymer emulsion, styrene Acrylic copolymer emulsions, aqueous acryl resins, aqueous polyurethane resins, aqueous polyester resins, and other generally known adhesives in the coated paper field can be used alone or in combination.

Among the above emulsions, a styrene-acrylic copolymer emulsion is particularly preferred from the viewpoints of clearness and glossiness of a recorded image.

The weight average molecular weight of the emulsion used as an adhesive in the cast layer is preferably from 100,000 to 100,000, and more preferably from 500,000 to 500,000. If the molecular weight is lower than 100,000, the strength of the coating film tends to be insufficient, and if the molecular weight is higher than 100,000, the stability of the emulsion tends to be insufficient. The average particle diameter of the emulsion is preferably in the range of 0.02 to 0.15 μm. If the average particle size of the emulsion is less than 0.02 μm, the ink absorbency will decrease.On the other hand, if the average particle size exceeds 0.15 μπι, the surface gloss and the sharpness of the color development of the recorded image will decrease. .

A copolymer emulsion having a glass transition temperature of the copolymer in the range of 50 to 150 ° C. is preferred.

If the glass transition point of the copolymer is lower than 50 ° C, the film of the cast layer will advance too much during drying, and the porosity of the surface will decrease, resulting in a decrease in the ink absorption rate. There is. Conversely, if the glass transition point of the copolymer is higher than 150 ° C., film formation may be insufficient during drying, and the gloss may be insufficient. On the other hand, if the drying temperature is too high, the film formation proceeds too much, and the porosity of the surface decreases, so that the ink absorption rate decreases. Conversely, if the drying temperature is too low, gloss tends to decrease.

Examples of the fine pigment having an average secondary particle diameter of 1 μπι or less in the cast layer include kaolin, clay, calcined clay, amorphous silica (also referred to as amorphous silica), zinc oxide, and oxide. Aluminum, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, Various pigments known and used in the general coated paper manufacturing field, such as styrene-based plastic pigments, hydrotalcite, urea resin-based plastic pigments, and benzoguanamine-based plastic pigments, can be used alone or in combination.

Among these, it is preferable to use amorphous silica, alumina, colloidal silica, or zeolite having high ink absorbability as a main component. More preferred is colloidal silica, and even more preferred is anionic colloidal silica. The anionic colloidal silica has an average particle size of 0.01 to 0.15 / im, preferably 0.01 to 0.12 μm, and more preferably 0.01 to 0.12 μm. 2 to 0.10 μm. If the average particle size is less than 0.01 μm, the ink absorption may decrease.If it exceeds 0.15 μιη, gloss and The sharpness of coloring of a recorded image may be reduced.

The composition ratio (solid content mass ratio) of the adhesive and the fine pigment in the cast layer is preferably

It is in the range of 60/40 to 3/97, more preferably in the range of 50/50 to 5/95, and still more preferably in the range of 40/60 to 7/93.

When the ratio of the adhesive exceeds 60% by mass, the sharpness of the color development of the recorded image tends to decrease, and when the ratio is less than 3% by mass, the gloss tends to decrease.

As the release agent used in the cast layer, at least one selected from the group consisting of fatty acids having 12 to 18 carbon atoms and water-soluble salts thereof is preferably used to obtain the effects of the present invention. When the number of carbon atoms is 19 or more, the dispersibility may be poor, and when the number of carbon atoms is less than 12, the releasability may not be sufficient.

Specific examples of fatty acids having 12 to 18 carbon atoms include lauric acid (12 carbon atoms), myristic acid (13 carbon atoms), palmitic acid (15 carbon atoms), stearic acid (18 carbon atoms) ), Oleic acid (18 carbon atoms), linoleic acid (18 carbon atoms), linolenic acid (18 carbon atoms), arachidonic acid (18 carbon atoms), and the like. Examples thereof include a sodium salt, a potassium salt, and an ammonium salt of the fatty acid. Of these fatty acids and water-soluble salts thereof, stearic acid or a water-soluble salt thereof, oleic acid or a water-soluble salt thereof are preferable in terms of heat resistance and releasability of recording paper, and among these, stearic acid and oleic acid are further preferable. , Ammonium stearate, and ammonium oleate are particularly excellent.

It is considered that the reason why the heat resistance and the release property are good is that the release agent is not easily oxidized in terms of the chemical structure, and the release property from the mirror drum is good. Further, in addition to the release agent, it is possible to use a release agent used in the production of ordinary coated paper for printing or cast paper for printing as long as the effects of the present invention are not impaired. .

Specific examples include polyolefin waxes such as polyethylene wax and polypropylene wax, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene. The release agent is used in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the fine pigment. Preferably, 0.2 to 8 parts by mass is added. If the addition amount is less than 0.1 part by mass, continuous operability may be poor. If the addition amount exceeds 10 parts by mass, the print density may be reduced and the image quality may be reduced.

Further, in the cast ink jet recording paper of the present invention, when at least one of the undercoat layer and the cast layer contains an organic compound containing an organic compound, the image storability is improved. Examples of the organic compound containing thioether include thioether compounds, thiourea compounds, disulfide compounds, mercapto compounds, sulfin oxide compounds, thiosulfonic acid compounds, and thiosulfinic acid compounds. Among them, thioether compounds are preferable, and in particular, the inclusion of 1,2-bis (2-hydroxyxethylthio) ethane or 1,4-bis (2-hydroxyxethylthio) butane makes the image resistant to ozone. Cast ink jet recording paper with improved performance can be obtained. In particular, it has extremely excellent storability with respect to ink using a phthalocyanine dye as a cyan dye. Another major feature is that since the compound generated by oxidizing the compound is colorless, there is no problem such as yellowing of the cast ink jet recording paper.

The content of cast Inkjet recording during paper compound, 0. 1~ 4 g / m 2 approximately, preferably 0. 2~ ² g Z m 2 approximately. By the way, if it is less than 0.1 lg / m ^{2, the} effect of improving storage stability such as ozone resistance becomes insufficient, and if it is more than 4 g / m ² , the image quality deteriorates, which is not preferable. The compound exhibits an effect when contained in either the undercoat layer or the cast layer.

The coating liquid for the cast layer contains an antifoaming agent, a coloring agent, and a defoaming agent used for general printing coated paper and ink jet recording paper in order to adjust whiteness, viscosity, fluidity, and the like. Various auxiliaries such as a fluorescent whitening agent, an antistatic agent, a preservative and a dispersant, and a thickener are appropriately added. It is also possible to add a cationic compound to impart ink dye fixability.

The method of providing a cast layer in the present invention includes the steps of forming a coating liquid layer for a cast layer by using a mirror-finished drum (a drum of mirror-finished metal, plastic, glass, or the like), a mirror-finished metal plate, a plastic sheet, or the like. Dry on film, glass plate, etc. And transferring the smooth surface onto the coating layer, and obtaining a smooth and glossy cast coating layer surface by this method.

As a method of providing a cast layer, the above-mentioned coating solution for a cast layer is applied on an undercoat layer, and the coated layer is pressed against a heated mirror-surface drum while the coating layer is in a wet state, and dried. Examples of the method include a finishing method (wet casting method) and a method of once drying, re-wetting, pressing against a heated mirror drum, drying and finishing (rewet casting method), and the like. In addition, a method in which the coating liquid for the cast layer is applied directly to the heated mirror-surface drum, followed by pressing and drying the undercoat layer surface of the base material provided with the undercoat layer (pre-cast method) should also be adopted. Can be.

The preferred range of the temperature of the heated mirror drum is 50 to 150 ° C, more preferably 70 to 120 ° C.

In the case of applying the coating liquid for a cast layer, various known coating apparatuses such as a blade coater, an air knife coater, a rhono recorder, a brush coater, a chaplex coater, a bar coater, and a Daravia coater can be used.

The coating amount of the cast layer is preferably 1~ 3 0 g Z m ² by dry weight, more preferably rather is 2~2 0 g / m ^2, more preferably, 3~ 1 5 g Zm ² . Here, it is less than 1 g Z m ^2, may print density and gloss is not sufficient, 3 0 when g / m ² a exceeds effect is saturated and workability load is imposed on the drying may be reduced .

After providing the cast layer, if necessary, a smoothing process can be further performed by using a super calender or the like. At this time, the calender can be heated.

Ί5 ° surface gloss (JIS-Z8741) of the recording surface of the cast inkjet recording paper is preferably 50 to obtain excellent image quality and high-quality photographic recording. % Or more, more preferably 60% or more.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but it is needless to say that the present invention is not limited thereto. In addition, parts and percentages in the examples indicate mass parts and mass%, respectively, unless otherwise specified. · Example 1

Amorphous silica as pigment (trade name: Fine Seal X-45, average primary particle diameter: 10 nm, average secondary particle diameter: 4.5 μm), 50 parts, Zeolite (manufactured by Tosoh Corporation) , Trade name: Toyobuilder, average particle size 1.5 μm) 50 parts, Silicone-modified polybutyl alcohol (Kuraray Co., trade name: PVA R-11 30) as adhesive 30 parts, as cationic compound 25 parts of diarylamine hydrochloride / acrylamide copolymer resin (Sumitomo Chemical Co., Ltd., trade name: Sumireze Resin 100ί), 0.5 part of sodium polyphosphate as a dispersant, and a solid content concentration of 18 parts % Of a coating solution for an undercoat layer was prepared. The subbing layer coating solution on one surface of the basis weight 1 0 0 g / m ² paper substrate, such that 1 0 g Zm ² by dry weight, the coating with an air knife coater, and dried. Next, a mixture of 80 parts of anionic colloidal silica having an average particle diameter of 0.05 μπι and 20 parts of styrene'acrylic copolymer emaldione (Lion Corporation, trade name: Elsard 740), a viscous dispersant A coating liquid for a cast layer having a solid content concentration of 30% was prepared, comprising 5 parts of an alkyl bier ether / maleic acid derivative resin and 3 parts of a stearic acid aqueous dispersion (solid content ratio) as a release agent.

This coating solution for a cast layer is applied onto the above-mentioned undercoat layer using a roll coater, immediately pressed against a mirror drum having a surface temperature of 80 ° C, dried, released, and then cast. Inkjet recording paper was obtained. The coating amount of the cast layer at this time was 12 g / m ² in terms of solid content mass.

Example 2 '

A cast ink jet recording paper was obtained in the same manner as in Example 1, except that 3 parts of aqueous stearic acid dispersion was added as a release agent in place of 3 parts of aqueous stearic acid. Was.

Example 3

A cast ink jet recording paper was obtained in the same manner as in Example 1, except that 3 parts of ammonium oleate was added as the release agent instead of 3 parts of the aqueous dispersion of stearic acid as a release agent. .

Example 4 A cast ink jet recording paper was obtained in the same manner as in Example 1 except that 50 parts of the cationic compound 25 was changed to 50 parts.

Example 5

A cast ink jet recording paper was obtained in the same manner as in Example 1, except that 5 parts of the cationic compound 25 was changed to 5 parts.

Example 6

A cast ink jet recording paper was obtained in the same manner as in Example 1, except that 80 parts of the following fine silica was used in place of the anionic colloidal silica as the fine pigment of the cast layer.

Fine force:

An aqueous silica dispersion having an average secondary particle diameter of 4.5 μιη (available from Tokuyama Corporation, trade name: Fine Seal X-45, average primary particle diameter 10 nm) was mixed with a pressure homogenizer (SMT). The pulverization treatment was repeated with a pressurized condition of 200 kg / m ^{2 using an} ultra-high pressure homogenizer (GM-1 type, manufactured by the company) to obtain fine silica having an average secondary particle diameter of 0.8 μπι.

Example 7

A cast ink jet recording paper was obtained in the same manner as in Example 1, except that 10 parts of 1,2-bis (2-hydroxyxethylthio) ethane was added to the coating liquid for the undercoat layer. Was.

Comparative Example 1

In Example 1, dicyandiamide-based resin (manufactured by Nikka Chemical Co., trade name: Neofix E-117) was used in place of 5 parts of diarylamine hydrochloride / acrylamide copolymer resin as the cationic compound. A cast ink jet recording paper was obtained in the same manner as in Example 1 except that five copies were used.

Comparative Example 2

A cast ink jet recording paper was obtained in the same manner as in Example 1 except that 3 parts of an aqueous dispersion of lecithin was used instead of 3 parts of an aqueous dispersion of stearic acid as a release agent. Was. Comparative Example 3

A cast was prepared in the same manner as in Example 1 except that 3 parts of an aqueous dispersion of arachidic acid (C ₂ ) was used as a release agent instead of 3 parts of an aqueous dispersion of stearic acid. Inkjet recording paper was obtained.

Comparative Example 4

In Example 1, a cast ink was prepared in the same manner as in Example 1, except that 3 parts of an aqueous dispersion of undecylic acid (Cu) was used as a release agent instead of 3 parts of an aqueous dispersion of stearic acid. A recording paper was obtained.

The cast ink jet recording paper obtained in the examples and comparative examples was printed using an Epson inkjet printer PM-800C, and the evaluation results are shown in Table 1.

(Print density)

The printing density of the black solid printing portion 24 hours after printing was measured using a Macbeth densitometer (trade name: RD_914) manufactured by Macbeth.

(Ink absorption)

The ink absorbency was evaluated visually from the boundary of the mixed color black (80%) printed portion. ：: The boundary is clear and there is no bleeding.

X: The boundary is not clear and there are two blemishes.

(Heat-resistant)

The cast ink jet recording paper prepared in each example and each comparative example was stored in a thermostat at 80 ° C. for 7 days without printing, and the degree of yellowing of the recording paper was visually evaluated. Evaluation criteria :

◎: Excellent heat resistance.

〇: The recording paper slightly yellows, but there is no practical problem.

X: The recording paper turned yellow and needs improvement.

(Ozone resistance)

Ozone resistance, which has a high correlation with long-term storage, was evaluated. Solid printing of mixed black and cyan ink with one color mixture of cyan, magenta and yellow, and ISO-4 The printed image of 0 was left in a container having an ozone concentration of 10 ppm for 12 hours. In the case of solid printing, the print density after the test was measured. On the other hand, in the case of an image, the degree of discoloration was visually observed and evaluated.

The reduction in print density and the result of visual observation were combined and evaluated according to the following evaluation criteria.

Evaluation criteria:

A: No discoloration is observed.

〇: Discoloration is slightly observed, but there is no practical problem.

X: Discoloration is remarkable, and there is a problem in practical use.

(Continuous operability)

During the coating of the cast layer of each of the examples and comparative examples, the degree of contamination on the mirror drum during operation was visually evaluated.

Evaluation criteria:

：: Mirror surface drum does not fog, and continuous operation is good.

〇: Slight fogging of the mirror drum occurs, but practically there is no problem with continuous operation.

Δ: The mirror surface drum is stained, and the glossiness of the recording paper is reduced, which causes a practical problem.

: The paint on the mirror drum remains, making continuous operation impossible. Mottle occurs on the recording paper due to the degree of glossiness.

(75 degree surface gloss)

The glossiness of the obtained cast ink jet recording paper was measured using a gloss meter (trade name: GM-26D, manufactured by Murakami Color Research Laboratory Co., Ltd.) described in JIS-Z8741. The outline of JIS-Z8741 is as follows. A non-polarizing light source was used. A light beam with a specified opening angle was incident on the sample surface at a specified incident angle, and a light beam with a specified opening angle reflected in a mirror-reflecting direction was measured by a light receiver. The optical axes of the incident side and the light receiving side intersect at the sample surface. The unit of gloss is based on the specular gloss at the specified incident angle Θ on the glass surface whose refractive index is a constant value of 1.567 over the entire visible wavelength range. Expressed as%. table 1

* Comparative Example 4 was stuck on the mirror drum and could not be created.Industrial applicability As is evident from Table 1, the cast ink jet recording paper of the present invention has a high image print density and high ink absorbency. It is not only good, but also excellent in heat resistance and ozone resistance, excellent in continuous operation, and high in glossy cast ink jet recording paper. It is extremely practical.

Claims

The scope of the claims

1. An undercoat layer containing a pigment, a cationic compound and an adhesive is provided on a substrate, and an adhesive, a fine pigment having an average secondary particle diameter of less than 1 μm, and a release agent are provided on the undercoat layer. In a cast ink jet recording paper provided with a cast layer, the cationic compound can be copolymerized with diarylamine and (meth) acrylamide, or copolymerized with diarylamine and (meth) acrylamide. At least one selected from the group consisting of a copolymer with another vinyl monomer which does not substantially contain a carboxyl group, or a salt of any of these, and as the release agent, A cast ink jet recording paper containing at least one selected from the group consisting of fatty acids having 12 to 18 carbon atoms and water-soluble salts thereof.

2. The cast ink jet recording paper according to claim 1, wherein

A cast ink jet recording sheet, wherein the release agent is at least one selected from the group consisting of stearic acid, oleic acid, a water-soluble salt of stearic acid, and a water-soluble salt of oleic acid.

3. The cast ink jet recording sheet according to claim 1, wherein the cationic compound is contained in an amount of 1 to 100 parts by mass with respect to 100 parts by mass of the pigment.

3. The cast ink jet recording sheet according to claim 1 or 2, wherein the release agent is contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the fine pigment. Recording sheet.

5.The cast ink jet recording sheet according to claim 1, wherein at least one of the undercoat layer and the cast layer contains an organic compound containing an organic compound. Cast inkjet recording paper containing.

6. The cast ink jet recording paper according to claim 1 or 2, wherein the cast layer surface has a surface gloss of 75 ° (gloss based on JIS-Z8741) of 50% or more. Inkjet recording paper.