JP2003191624A - Glossy ink jet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide glossy ink jet recording paper excellent in ink jet recording properties such as surface smoothness, glossiness, ink absorbability, printing density or the like and also excellent in the stability of a coating solution and continuous operability. <P>SOLUTION: In the glossy ink jet recording paper wherein an undercoating layer containing a pigment and an adhesive is provided on a support and a glossy layer containing a pigment, an adhesive and a release agent is provided on the undercoating layer, the release agent contains at least polyethylene and the glossy layer contains a methyl vinyl ether/maleic anhydride copolymer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glossy inkjet recording paper, which is excellent in ink jet recording suitability such as surface smoothness, glossiness, ink absorbency, and print density, and stability of coating liquid and continuous operation. The present invention relates to a glossy inkjet recording paper having excellent properties.

[0002]

2. Description of the Related Art Recording by an ink jet printer is used in various fields because it produces little noise, enables high-speed recording, and facilitates multicoloring. As the ink jet recording paper, high-quality paper designed so as to have high ink absorbability, coated paper having a surface coated with a porous pigment, and the like are applied. Since all of these inkjet recording papers are mainly so-called matte inkjet recording papers having a low surface gloss, glossy inkjet recording papers having a high surface gloss and an excellent appearance have been demanded.

Generally, as a recording paper having a high surface gloss, a coated paper having a high gloss coated with a plate-like pigment on the surface and, if necessary, a calender treatment, or a wet coating is used. A so-called cast coated paper, which is obtained by copying a mirror surface by pressing and drying the layer on a heating drum surface having a mirror surface, is known, and is widely used as various printing papers. The cast coated paper has high surface gloss and superior surface smoothness as compared to a normal super calendered coated paper, and an excellent printing effect can be obtained. It is used exclusively for such purposes as above, and has the same glossiness when used as an inkjet recording paper. Among the glossy inkjet recording papers, it is attracting attention as a relatively inexpensive recording medium.

A method for producing a high-quality glossy ink jet recording paper satisfying the above characteristics by a casting method is as follows:
Many have been proposed so far. JP-A-62-95
According to Japanese Patent No. 285, the ink absorbability is good, the ink dryness is excellent, the dimensional change due to moisture absorption and dehumidification during ink jet recording or storage does not easily occur, the dot periphery is sharp, the resolution is high, and the coated surface is smooth. A glossy inkjet recording paper having high properties and gloss is disclosed.
Japanese Patent Application Laid-Open No. 63-264391 discloses a glossy inkjet recording paper which has good ink absorbability, glossiness, water resistance of recorded images, and dimensional stability. Japanese Unexamined Patent Publication (Kokai) No. 2-274587 discloses a glossy inkjet recording paper suitable for multicolor inkjet recording using a water-based ink. Japanese Patent Laid-Open No. 5-5
According to Japanese Patent Publication No. 9694, in addition to excellent ink absorbency, smoothness and gloss of recording paper surface, and water resistance of recording paper, dot density, sharpness, and roundness are excellent, and a high-quality and high-gradation full-color image is obtained. A glossy inkjet recording paper capable of recording an image is disclosed. In JP-A-8-332771, there is disclosed a glossy inkjet recording paper which is excellent in both ink absorption and productivity.
No. 000-212148 discloses a glossy inkjet recording paper that retains high glossiness on the recording surface, glossy smoothness close to that of a photograph, high print density, excellent print water resistance, and excellent ink jet ink fixing properties and absorbability. Each manufacturing method is disclosed.

The above-described method for producing a glossy inkjet recording paper has a drawback in that the peelability between the glossy inkjet recording paper and the metal surface of the drum having the mirror-finished surface is not sufficient, resulting in poor continuous operability. For example, such glossy inkjet recording paper generally has a bulky coating layer structure, and therefore the glossy layer has a lower surface strength than cast coated paper used as a printing paper. Therefore, the gloss layer is pressed against the heated mirror surface drum, and in the process of drying, a part of the gloss layer remains on the mirror surface drum, and the surface of the mirror surface drum becomes cloudy in proportion to the operation time. At the same time, with glossy inkjet recording paper,
There is a problem in that peeling from the mirror surface of the mirror surface becomes difficult, and as a result, the glossiness of the glossy inkjet recording paper is lowered. Therefore, it is necessary to stop the operation once to remove the dirt on the metal surface of the mirror surface drum, which is a problem in terms of operation. In order to solve this problem, it is generally practiced to add a release agent to the gloss layer coating solution to improve the operability. As a release agent for improving operability, it is possible to use a release agent that is used in the production of ordinary coated paper for printing or cast coated paper for printing, but it should be able to withstand recent quality demands. There was no such thing.

[0006]

DISCLOSURE OF THE INVENTION The present invention is excellent in ink jet recording suitability such as surface smoothness, glossiness, ink absorptivity, and print density, and is excellent in stability of coating liquid and continuous operability. A glossy inkjet recording sheet is provided.

[0007]

The present inventors adopt the following constitution in order to solve the above problems. That is, the present invention provides [1] a glossy inkjet ink comprising a support, an undercoat layer containing a pigment and an adhesive, and a gloss layer containing a pigment, an adhesive and a release agent on the undercoat layer. In the recording paper, the release agent contains at least polyethylene,
A glossy inkjet recording paper, wherein the glossy layer contains a methyl vinyl ether-maleic anhydride copolymer.

The present invention includes the following aspects. [2] The gloss inkjet recording paper according to [1], wherein the methyl vinyl ether-maleic anhydride copolymer has a weight average molecular weight of 100,000 to 5,000,000. [3] The gloss inkjet recording paper according to [1] or [2], which contains 0.5 to 5.0 parts by mass of the polyethylene with respect to 100 parts by mass of the pigment of the gloss layer. [4] The methyl vinyl ether-maleic anhydride copolymer was added in an amount of 0.
The glossy inkjet recording paper according to any one of [1] to [3], which contains 5 to 5.0 parts by mass. [5] The gloss layer is formed by applying pressure to a heated mirror surface drum and drying it while the layer obtained by applying the coating liquid for the gloss layer is in a wet state [1] to [4] ] The glossy inkjet recording paper according to any one of [1]. [6] 75 ° surface gloss of the gloss layer surface (JIS-Z
Glossiness based on 8741) is 30% or more [1]
~ The glossy inkjet recording paper according to any one of [5].

[0009]

DETAILED DESCRIPTION OF THE INVENTION In recent years, ink jet recording paper has
It is used in a wide range of fields as a medium for inkjet printers, that is, monochrome printers and color printers. Among them, especially for glossy inkjet recording paper, it was excellent in inkjet recording suitability such as surface smoothness, glossiness, ink absorbency, and print density, and was excellent in stability of coating liquid and continuous operability. The establishment of manufacturing technology for providing glossy inkjet recording paper has been awaited. In the gloss inkjet recording paper, the present inventors provide a subbing layer containing a pigment and an adhesive on a support, and a gloss layer containing a pigment, an adhesive and a release agent on the subbing layer. The release agent contains at least polyethylene, and the gloss layer contains a methyl vinyl ether-maleic anhydride copolymer,
It is possible to obtain a glossy inkjet recording paper which is extremely useful in practice because it is excellent in inkjet recording suitability such as surface smoothness, glossiness, ink absorbency, and print density, and is excellent in stability and continuous operability of coating liquid. It was found that the present invention has been completed.

(Support) As the support used in the present invention, a paper base material is preferably used, and is composed mainly of wood pulp and, if necessary, a pigment. Wood pulp
Various chemical pulps, mechanical pulps, recycled pulps and the like can be used, and so-called ECF, TCF pulps and other chlorine-free pulps can also be preferably used. These pulps can be adjusted in beating degree with a beating machine in order to adjust paper strength, papermaking suitability and the like. The beating degree of pulp is not particularly limited, but generally 250 to 550 ml (CSF: JIS-
It is about P-8121). The pigment is added for the purpose of imparting opacity or adjusting the ink absorbability, and calcium carbonate, calcined kaolin, silica, titanium oxide or the like can be used. The addition amount of the pigment is preferably about 1 to 20% by mass. If too much pigment is used, the paper strength may be reduced. As an auxiliary agent, a sizing agent, a fixing agent, a paper strengthening agent, a cationizing agent, a yield improving agent, a dye, an optical brightening agent and the like can be added. Further, in the size press step of a paper machine, starch, polyvinyl alcohol, a cationic compound or the like can be applied and impregnated to adjust the surface strength, the Steckigt sizing degree and the like. Steckigt sizing degree is 1 to 200
Seconds are preferred. If the Steckigt sizing degree is lower than 1 second, wrinkles may occur during coating, which may cause a problem in operation. If the Steckigt sizing degree is higher than 200 seconds, the ink absorbability may decrease. , The curl after printing may be worse.

As the cationic compound to be applied / impregnated in the size pressing step, polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, secondary amine groups, tertiary amine groups and quaternary ammonium groups are used. Having acrylic resin, polyvinylamine, polyvinylamidines, dicyandiamide
-Dicyan-based cationic resin represented by formalin polycondensate, dicyandiamide-polyamine-based cationic resin represented by diethylenetriamine polycondensate, epichlorohydrin-dimethylamine addition polymer, dimethyldiallylammonium chloride copolymer, diallylamine salt copolymerization, Examples thereof include polymers of allylamine salts, quaternary salt polymers of dialkylaminoethyl (meth) acrylate, and acrylamide-diallylamine salt copolymers. The low molecular weight cationic compound is a low molecular weight compound having a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium base, and examples thereof include those having a molecular weight of about 1,000 or less.

(Undercoat layer) An undercoat layer is provided on the support for the purpose of increasing the ink absorption capacity and the ink absorption rate. The undercoat layer provided on the support is mainly composed of a pigment and an adhesive. The pigment in the undercoat layer is kaolin, clay, calcined clay, amorphous silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, Various types of publicly known pigments such as smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment, benzoguanamine plastic pigment, etc. , Can be used alone or in combination. Among these, it is preferable to use amorphous silica, alumina, and zeolite having high ink absorbability as the main components.

As the adhesive in the undercoat layer, casein,
Proteins such as soybean protein and synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, silyl modified polyvinyl alcohol, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-
Conventionally known adhesives generally used for coated paper such as butadiene copolymer and conjugated diene polymer latex of methylmethacrylate-butadiene copolymer are used alone or in combination. The mixing ratio of the pigment and the adhesive depends on the kind thereof, but generally 1 to 100 parts by mass of the adhesive, preferably 2 to 50 parts by mass with respect to 100 parts by mass of the pigment.
It is adjusted in the range of parts by mass. In addition, various auxiliaries such as a dispersant, a defoaming agent, an antistatic agent and a preservative used in the production of general coated paper are appropriately added. Fluorescent dyes and colorants can also be added.

A cationic compound may be added to the undercoat layer for the purpose of fixing the dye component in the ink for ink jet recording. However, as will be described later, it is preferable that the ink dye is fixed to the gloss layer provided on the undercoat layer as much as possible because the printing density becomes high. For this purpose, it is preferable to add more cationic compounds in the gloss layer than in the undercoat layer. More preferably,
It is preferable that the cationic compound is added only to the gloss layer, and the cationic compound is substantially absent in the undercoat layer. As for "substantially absent", the addition of a small amount of a cationic surfactant or the like as an auxiliary agent is excluded.
When the cationic compound is blended only in the gloss layer and the cationic compound is substantially absent in the undercoat layer, the gloss when the gloss layer is provided is most easily exhibited.

When a composite of colloidal silica and a polymer resin obtained by polymerizing a monomer having an ethylenically unsaturated bond is added to the undercoat layer, the gloss when the gloss layer is provided is further exhibited. The reason for this is not clear, but it is presumed that the presence of the composite suppresses the penetration of the glossy layer coating liquid into the undercoat layer while maintaining the ink absorbability of the undercoat layer. When the gloss layer is provided by the casting method, the releasability from the mirror surface drum tends to be improved.

As the polymer resin obtained by polymerizing a monomer having an ethylenically unsaturated bond, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, etc. The number of carbon atoms of the alkyl group is 1-18, and the number of carbon atoms of the alkyl group such as acrylic acid ester, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate is 1-18.
Individual methacrylic acid ester, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl propionate, acrylamide, N-methylolacrylamide,
Examples thereof include polymers obtained by polymerizing ethylenic monomers such as ethylene and butadiene. Incidentally, the polymer may be a copolymer in which two or more kinds of ethylenic monomers are used in combination, if necessary, and further, these polymers or a substituted derivative of the copolymer may be used. Incidentally, the substituted derivative, for example, a carboxyl group, or,
The thing which made it alkali-reactive etc. is illustrated.

The compounding with colloidal silica is carried out by polymerizing the above-mentioned monomer having an ethylenically unsaturated bond with a silane coupling agent or the like in the presence of colloidal silica,
Examples thereof include a method of forming a complex by Si—O—R bond (R: polymer component). Tg of polymer component of the above composite
The (glass transition point) is not particularly limited, but Tg of 40 ° C. or higher is preferable, and 50 to 100 ° C. is more preferable.
Although the reason is unknown, when the Tg is 40 ° C. or higher, and when the gloss layer is provided by the casting method, the releasability from the mirror surface drum tends to be further improved. Tg is 40 ° C
If less than, because the film formation proceeds too much during drying,
Ink absorption may be delayed and bleeding may occur. If the Tg is higher than 100 ° C., the adhesive in the coating liquid layer for the glossy layer may not form a film, and the ink absorbability may decrease.

The coating liquid for the undercoat layer composed of the above-mentioned 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 / m ² , preferably on the support. , 5 to 50 g / m ² , and more preferably 10 to
The coating is performed so that the amount becomes about 20 g / m ² . When the coating amount is small, the ink absorbency is poor, or when a gloss layer is provided,
It may not be possible to obtain sufficient gloss, while
When the coating amount is large, the print density may be reduced, the strength of the gloss layer may be reduced, and powder may be easily removed or scratched.

The coating liquid for the undercoat layer is a blade coater,
The coating and drying are performed by various publicly known coating devices such as 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 and a die coater. Further, if necessary, smoothing treatment such as super calendering or brushing can be performed after the undercoat layer is dried.

(Gloss Layer) In the present invention, a gloss layer is further provided on the undercoat layer. The gloss layer contains a pigment and an adhesive as main components. As the pigment, (1) the average primary particle diameter is 3 nm or more and 40 nm or less, and the average secondary particle diameter is 1
It contains 0 to 400 nm of amorphous silica and / or (2) colloidal silica having an average particle diameter of 200 nm or less. By using the amorphous silica of (1), it is possible to obtain an ink having excellent print density, ink absorbency, etc. and a certain degree of glossiness. However, by using the colloidal silica of (2) together, An extremely high glossiness can be obtained without lowering the ink absorbency.

The method for preparing the amorphous silica (1) is not particularly limited, but for example, commercially available amorphous silica (for example, the average secondary particle diameter is about several microns). Thing) by mechanical means, giving a strong force,
It can be obtained by reducing the average secondary particle diameter. As this mechanical means, an ultrasonic homogenizer,
Examples thereof include a pressure type homogenizer, a high speed rotation mill, a roller mill, a container driving medium mill, a medium stirring mill, a jet mill and a sand grinder. The amorphous silica thus treated is generally an aqueous dispersion (slurry or colloidal particles) having a solid content concentration of about 5 to 20% by mass.
Obtained as. The average particle diameter as referred to in the present invention is a particle diameter observed with an electron microscope (SEM and TEM). (1
An electron micrograph of 10,000 to 400,000 times taken, and the Martin diameter of particles in a 5 cm square was measured and averaged. P52 of "Particle Handbook", 1991, etc. )

The amorphous silica used in the present invention (substantially 2
The average secondary particle diameter of the primary particles) is 10 nm or more and 40
0 nm or less, preferably 15 nm or more and 150 n
m or less, more preferably 20 nm or more and 100 nm or less. The average secondary particle size of amorphous silica is 40
If it exceeds 0 nm, the transparency of the gloss layer is lowered, the color developability of the dye fixed in the gloss layer is lowered, and the desired print density may not be obtained. The average secondary particle size is
When extremely small amorphous silica is used, the ink absorbency may be lowered, and the desired image quality may not be obtained.

The average primary particle size of the amorphous silica is
It is necessary to adjust to 3 nm or more and 40 nm or less, preferably 5 nm or more and 30 nm or less, more preferably 7 nm
It is 20 nm or less. When the average primary particle size is less than 3 nm, the voids between the primary particles become extremely small, the ink absorbing ability is lowered, and desired image quality may not be obtained. The average primary particle size is 40
When the average particle size exceeds nm, the aggregated secondary particles become large, the transparency of the gloss layer decreases, and the color developability of the dye fixed in the gloss layer decreases, so that the desired print density may not be obtained. is there.

Next, the colloidal silica (2) will be described. Colloidal silica generally refers to colloidal particles obtained by dispersing ultrafine particles of silicic acid anhydride (primary particles) in a dispersion medium such as water. Colloidal silica is usually a single dispersion of primary particles, but the primary particles are 2 to several 1
It may be a dispersion of 0 pieces connected linearly. The average particle size of colloidal silica is generally 1 nm to 100
Although it is referred to as nm, here, those exceeding 100 nm (so-called silica sol) are also included. The colloidal silica is generally in the form of a true sphere, but may be in the form of a chain or a bead and is not particularly limited. The average particle size needs to be 200 nm or less, and preferably,
It is 100 nm or less, more preferably 50 nm or less. If the average particle diameter exceeds 200 nm, the transparency of the gloss layer is reduced, the color developability of the ink dye fixed in the gloss layer is reduced, and the desired print density may not be obtained, and The gloss may decrease. As will be described later, when a cationic compound is added to the glossy layer, it is preferable to use a cationic colloidal silica as the colloidal silica because of excellent miscibility with the cationic compound.

The proportion of amorphous silica and colloidal silica in all pigments in the gloss layer is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or less. If it is less than 5% by mass, the desired gloss may not be obtained.

As the adhesive in the gloss layer, water-soluble resins (for example, polyvinyl alcohols such as polyvinyl alcohol and silyl-modified polyvinyl alcohol, casein, soybean protein, synthetic proteins, starch, carboxymethyl cellulose, and cellulose derivatives such as methyl cellulose). ), A water-dispersible resin such as a conjugated diene polymer latex such as a styrene-butadiene copolymer or a methyl methacrylate-butadiene copolymer, a vinyl copolymer latex such as a styrene-vinyl acetate copolymer, an aqueous acrylic resin , Water-based polyurethane resin, water-based polyester resin, etc.
In addition, various publicly known adhesives generally used in the coated paper field are used alone or in combination. The compounding amount of the adhesive is adjusted within a range of 1 to 200 parts by mass, more preferably 10 to 100 parts by mass, relative to 100 parts by mass of the pigment. Here, when the amount of the adhesive is small, the strength of the glossy layer may be weakened, the surface may be easily scratched, and powder may be dropped. On the other hand, if the amount of the adhesive is large, the ink absorbency is lowered, and the desired inkjet recording suitability may not be obtained.

A cationic compound is preferably blended in the gloss layer for the purpose of fixing the dye component in the ink. The compounding method is to mix and use the amorphous silica,
Amorphous silica is generally anionic and, upon mixing, agglomeration may occur. In this case, when a commercially available amorphous silica (having secondary particles of several microns) is treated by mechanical means with a strong force to make it fine, After mixing the cationic compound together with the amorphous silica and dispersing and pulverizing by mechanical means, or after mixing the cationic compound with the finely divided amorphous silica and aggregating Alternatively, a method of mechanically dispersing and pulverizing again to adjust to a desired aggregate particle diameter can be adopted.

Examples of the cationic compound include a cationic resin and a low molecular weight cationic compound (for example, a cationic surfactant). In order to improve the print density, a cationic resin is preferable and it can be used as a water-soluble resin or an emulsion. Furthermore, it can be used as a cationic organic pigment in the form of particles by insolubilizing the cationic resin by means such as crosslinking. Such a cationic organic pigment is obtained by copolymerizing a polyfunctional monomer to form a crosslinked resin when polymerizing a cationic resin, or by reacting with a hydroxyl group, a carboxyl group, an amino group, and an acetoacetyl group. An example is a cationic resin having a functional group, which is optionally crosslinked with a crosslinking agent and crosslinked by means such as heat and radiation. Cationic compounds, especially cationic resins, may also serve as adhesives.

Examples of the cationic resin include the following. Specifically, 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, 2) acrylic resin having secondary amine group, tertiary amine group or quaternary ammonium group, 3) polyvinyl amine , Polyvinylamidines,
4) Dicyan-based cationic resin represented by dicyandiamide-formalin polycondensate, 5) Polyamine-based cationic resin represented by dicyandiamide-diethylenetriamine polycondensate, 6) Epichlorohydrin-dimethylamine addition polymer, 7) Dimethyldiallylammonium chloride -SO ₂ copolymer, 8) diallylamine salt -SO
Cation of ₂ copolymer, 9) dimethyldiallylammonium chloride polymer, 10) polymer of allylamine salt, 11) quaternary salt of dialkylaminoethyl (meth) acrylate, 12) acrylamide-diallylamine salt copolymer, etc. And the like.

The cationic compound also has the effect of improving the water resistance of the printed image. The amount of the cationic compound blended in the gloss layer is not particularly limited, but is preferably 1 to 100 parts by mass, and more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the pigment. If the blending amount is small, the printing density may not be improved so much. On the contrary, if the blending amount is large, the printing density may be lowered or image blurring may occur.

The glossy inkjet recording paper of the present invention comprises
The gloss layer contains polyethylene as a release agent. Examples of the release agent include calcium stearate, zinc stearate, potassium oleate, ammonium oleate and other higher fatty acid alkali salts, lecithin, silicone oil, silicone compounds such as silicone wax, and fluorine compounds such as polytetrafluoroethylene. However, in both cases, the releasability from the surface of the mirror surface drum is insufficient, the gloss of the obtained gloss layer is insufficient, or uneven gloss occurs, and in an extreme case, it is released from the mirror surface drum. There were problems such as being disabled. As a result of studying a material for improving the releasing property of the gloss layer, the present inventors have found that polyethylene has a remarkable effect on the smoothness of the gloss inkjet recording paper surface and the manifestation of gloss, and further suppresses image blurring. It was also found to have an effect.

The polyethylene contained in the gloss layer is preferably a waxy polyethylene wax because of its ease of use. The amount of polyethylene wax contained in the gloss layer is preferably 0.5 to 5.0 parts by mass, and more preferably 1.0 to 3.0 parts by mass with respect to 100 parts by mass of the pigment.
If the amount is less than 0.5 parts by mass, the wet state coating liquid may not adhere well to the mirror surface drum, high gloss may not be obtained, the releasability may be poor, and the surface smoothness may be deteriorated. There is a case. When it exceeds 5.0 parts by mass, the transparency of the coating liquid for the glossy layer is lowered, so that the problem that the printing density is lowered may occur.

The glossy inkjet recording paper of the present invention is characterized by containing a methyl vinyl ether-maleic anhydride copolymer as a thickening agent in the glossy layer. As the thickener, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, gum arabic, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer alkali salt, ethylene-acrylic acid copolymer Water-soluble polymers such as alkali salts and alkali salts of styrene-acrylic acid copolymers, and water-dispersed polymers such as styrene-butadiene latex, acrylic latex, urethane latex, etc. There is a problem that the coating liquid gels, the ink absorbency after printing and the print density decrease, and stable operation cannot be performed. As a result of studying materials having excellent coating liquid stability and printing quality, the present inventors have found that a methyl vinyl ether-maleic anhydride copolymer has a remarkable effect. By using polyethylene and methyl vinyl ether-maleic anhydride copolymer together in the gloss layer, the stability of the coating liquid is excellent, continuous operation during manufacturing is possible, and the surface smoothness, gloss, and ink absorption It is possible to obtain a glossy inkjet recording paper which is excellent in ink jet recording suitability such as properties and printing density.

The weight average molecular weight of the methyl vinyl ether-maleic anhydride copolymer is preferably 100,000 to 5,000,000, more preferably 200,000 to 700,000. When the weight average molecular weight is less than 100,000, the target viscosity of the coating liquid for the gloss layer cannot be obtained, and the coating liquid for the gloss layer is excessively absorbed by the undercoat layer, resulting in a decrease in print density. . On the other hand, when the weight average molecular weight exceeds 5,000,000, the gloss layer coating liquid is likely to thicken, and the gloss layer coating liquid is hardly absorbed by the undercoat layer, resulting in poor ink drying property.

The amount of the methyl vinyl ether maleic anhydride copolymer contained in the gloss layer is preferably 0.5 to 5.0 parts by weight, and 0.7 to 5.0 parts by weight based on 100 parts by weight of the pigment.
3.0 parts by mass is more preferable. If the amount is less than 0.5 mass, the water retention of the coating liquid for the gloss layer may decrease, the releasability from the mirror drum surface may become insufficient, and the surface smoothness may deteriorate. When it exceeds 5.0 parts by mass, the cationic resin in the gloss layer coating solution is much eluted, and the viscosity and gelation phenomenon of the gloss layer coating solution tend to occur. It may solidify.

In the present invention, the casting method means that the glossy layer has a smooth mirror-finished drum (drum of mirror-finished metal, plastic, glass, etc.), mirror-finished metal plate, smooth plastic sheet or film, glass plate. It is a method of obtaining a smooth and glossy gloss layer surface by drying on a flat surface and copying the smooth surface onto the gloss layer. As the smooth surface, for example, surface roughness (JIS-B0601) Ra =
0.5 μm or less, more preferably Ra = 0.05 μm or less.

As a method for providing the glossy layer, a manufacturing method using a heated mirror surface drum can be used. The surface temperature of the mirror surface drum is not particularly limited, but is 40 ° C to 150 ° C due to the operability such as drying conditions and the glossiness of the gloss layer surface.
Is preferable, 70 to 120 ° C. is more preferable, and 80 to 1
10 ° C. is particularly preferred. The surface temperature of the mirror surface drum is 40
When the temperature is lower than ℃, it is difficult to form an adhesive for the gloss layer, and the surface strength of the gloss inkjet recording paper may be lowered. When the temperature is higher than 150 ° C, the adhesive is formed in the gloss layer. Therefore, there is a risk that the ink absorbency will decrease.

A method of applying the above coating solution for a gloss layer onto an undercoat layer, and pressing the heated mirror surface drum to dry the gloss layer while the gloss layer is in a wet state, and finishing it (wet cast Method), or a method in which the material is once dried and then re-wetted, and then pressure-contacted with a heated mirror surface drum and dried to finish (rewet casting method). In general, the wet cast method tends to be excellent in glossiness and ink absorbency, and the rewet cast method is likely to be excellent in productivity. Also, on the heated mirror drum,
It is also possible to employ a method (precast method) of directly applying the coating liquid for the gloss layer and then pressing and drying it on the surface of the undercoat layer on the support provided with the undercoat layer.

Further, the gloss layer coating liquid is applied onto the undercoat layer to dry the gloss layer to a certain extent, and while being in a semi-dry state, it is pressed against a heated mirror surface drum and dried. When finished, a uniform gloss layer is easily formed, a printing density is high, and a gloss layer having excellent gloss is easily obtained, which is particularly preferable. Here, semi-dry means that the fluidity of the gloss layer is almost gone, but it contains a lot of water,
That is, 20 parts by weight per 100 parts by mass of the dry layer of the gloss layer
It is preferable that the content of water is up to 400 parts by mass,
More preferably, it is adjusted in the range of 50 to 200 parts by mass. If the amount of water is small, the surface of the mirror surface drum will not be sufficiently transferred when it is pressed against the mirror surface drum, and it will be difficult to exhibit sufficient gloss.
The gloss layer is crushed, a uniform and sufficient coating amount of the gloss layer cannot be obtained, and the print density and gloss tend to be insufficient. Further, a part or all of the gloss layer may be transferred or adhered to the mirror surface drum to reduce the gloss, or the mirror surface drum may become dirty, which may cause a problem in continuous operation.

When the coating liquid for the gloss layer is applied onto the undercoat layer and is pressed against a heated mirror surface drum while the undercoat layer is in a wet state and dried to finish, the gloss of a uniform and sufficient coating amount is obtained. For the purpose of obtaining a layer, a method of accelerating the immobilization of the gloss layer coating liquid can be adopted. As this method, for example,
(1) In the undercoat layer, a gelling agent that promotes immobilization of the gloss layer coating liquid is blended in advance. (2) On the undercoat layer,
The surface is coated and impregnated with a gelling agent that promotes immobilization of the gloss layer coating solution. (3) Immobilization of the gloss layer coating solution after applying the gloss layer coating solution The surface is coated and impregnated with a gelling agent that promotes (4) a coating solution for the gloss layer that contains a gelling agent that promotes immobilization during the drying process of the coating solution. It can be mentioned. Examples of such a gelling agent include boric acid, which is a cross-linking agent for the adhesive in the coating liquid for the gloss layer, formic acid, etc. and their salts, aldehyde compounds,
Epoxy compounds and the like can be mentioned. A coating liquid similar to the coating liquid for the gloss layer is coated on the support or the undercoat layer, dried or semi-dried, and then the coating liquid for the gloss layer is further coated on the coating layer. It can also be dried on a mirror drum.

In order to adjust the whiteness, viscosity, fluidity and the like, the coating liquid for the glossy layer contains pigments, antifoaming agents, coloring agents used in general printing coating paper and ink jet recording paper. Various auxiliaries such as agents, optical brighteners, antistatic agents, preservatives, dispersants, and thickeners are appropriately added.

When the coating liquid for the gloss layer is applied on the undercoat layer
Blade coater, air knife coater, low
Le coater, brush coater, champlex coater
ー, bar coater, gravure coater, die coater, etc.
Various known coating devices can be used. Gloss layer coating amount
Is 1 to 30 g / m 2 in dry solid content²Is preferred, and 1.5
~ 20 g / m²Is more preferred and 3 to 15 g / m²Garasara
Is preferred. Coating amount is 1g / m ²Below, print density and
The gloss may not be sufficient, and the coating amount is 30g.
/ M²If it exceeds, the print density and gloss effect will be saturated and the
There is a risk that dryness will be a burden and operability will be reduced. light
After establishing the Sawa layer by the cast method,
A smoothing process can also be performed by a render or the like.

75 ° on the surface of glossy inkjet recording paper
Gloss (glossiness based on JIS-Z8741) is 30
% Or more is preferable, whereby excellent image quality and photographic-like high-quality recording can be obtained. The glossiness is more preferably 40
% Or more, more preferably 50% or more, and most preferably 60% or more.

[0044]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

Example 1 (Preparation of paper base material) Wood pulp (LBKP; Freeness 450)
ml CSF) 100 parts, calcined kaolin (manufactured by Engelhard Mineral Co., Ltd., trade name: Ansilex) 10 parts, commercially available sizing agent (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: Size Pine E)
-50) 0.05 part, sulfuric acid band (manufactured by Hokuriku Kasei) 1.
5 parts, wet paper strength agent (manufactured by Arakawa Chemical Industry Co., Ltd., trade name: KW-
356) 0.5 parts of starch and 0.75 parts of starch (manufactured by Oji Corn Starch Co., Ltd., trade name: Ryosei KH-1000) are used, and a basis weight of 150 g / m ^{2 is} measured by a Fourdrinier paper machine.
A paper substrate was manufactured. The Steckigt sizing degree of this paper substrate was 10 seconds. This paper base material was used in all the examples and comparative examples of the present invention.

(Undercoat layer) As a coating solution for the undercoat layer, amorphous silica (trade name: Fineseal X manufactured by Tokuyama Corporation)
-60 :) 100 parts, zeolite (Tosoh, trade name: Toyo Builder) 5 parts, silyl-modified polyvinyl alcohol (Kuraray Co., trade name: R-1130) 25 parts, fluorescent dye (Sumitomo Chemical Co., trade name) : WhitexBPS)
0.8 part was added to prepare an undercoat and undercoat coating liquid having a solid content concentration of 18%. This undercoat layer coating liquid was applied onto the above-mentioned paper substrate with an air knife coater so that the dry weight was 9 g / m ² , and was dried.

(Gloss layer) (Parts indicate parts by mass of solid content) As a coating liquid for the gloss layer, a mixture of styrene acrylic polymer and colloidal silica (amorphous silica) (Lion Co., trade name: Elsard 740) 100 Part, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Cretex PN-144) 2.0 parts, methyl vinyl ether-maleic anhydride copolymer having a weight average molecular weight of 1,000,000 (manufactured by Toho Chemical Co., Ltd., trade name : Bismar YK-1S)
A gloss layer coating solution having a solid content concentration of 30% was prepared, which was 2.0 parts. The coating solution for a gloss layer was applied onto the undercoat layer using a roll coater, and immediately thereafter, it was pressed against a mirror surface drum having a surface temperature of 90 ° C., dried, and then released to give a gloss inkjet recording paper. Obtained. The coating amount at this time was 8 g / m ² in dry mass.

Example 2 In the coating liquid for the gloss layer, a weight average molecular weight of 1,000,000 was used instead of the methyl vinyl ether anhydride-maleic acid copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S). A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 100,000 methyl vinyl ether-maleic anhydride copolymer was used.

Example 3 In the coating liquid for the gloss layer, a weight average molecular weight of 1,000,000 was used instead of the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S). A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 5,000,000 of methyl vinyl ether-maleic anhydride copolymer was used.

Example 4 In the coating liquid for glossy layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 4) was changed from 2.0 parts to 0.3 parts.

Example 5 Example 5 except that the polyethylene wax (manufactured by Nisshin Chemical Co., Inc., trade name: Kretex PN-144) was changed from 2.0 parts to 0.5 parts in the gloss layer coating liquid. A glossy inkjet recording paper was obtained in the same manner as in 1.

Example 6 In the coating liquid for glossy layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 4) was changed from 2.0 parts to 5.0 parts.

Example 7 In the coating liquid for the gloss layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 4) was changed from 2.0 parts to 6.0 parts.

Example 8 In the coating liquid for the gloss layer, the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S) was changed from 2.0 parts to 0.3 parts. A glossy inkjet recording paper was obtained in the same manner as in Example 1 except for the above.

Example 9 In the gloss layer coating liquid, the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S) was changed from 2.0 parts to 0.5 parts. A glossy inkjet recording paper was obtained in the same manner as in Example 1 except for the above.

Example 10 In the gloss layer coating liquid, the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Kagaku Co., trade name: Bismar YK-1S) was changed from 2.0 parts to 5.0 parts. A glossy inkjet recording paper was obtained in the same manner as in Example 1 except for the above.

Example 11 In the coating liquid for the gloss layer, the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Kagaku Co., trade name: Bismar YK-1S) was changed from 2.0 parts to 6.0 parts. A glossy inkjet recording paper was obtained in the same manner as in Example 1 except for the above.

Example 12 In the coating liquid for gloss layer, a weight average molecular weight of 1,000,000 was used instead of the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S). A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 50,000 methyl vinyl ether-maleic anhydride copolymer was used.

Example 13 In the coating liquid for the gloss layer, a weight average molecular weight of 1,000,000 was used instead of the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S). A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 6 million methyl vinyl ether-maleic anhydride copolymer was used.

Comparative Example 1 In the coating liquid for the gloss layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that 4) was not added.

Comparative Example 2 Same as Example 1 except that the coating liquid for gloss layer did not contain methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S). A glossy inkjet recording paper was obtained.

Comparative Example 3 In the coating liquid for the gloss layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
Example 1 except that lecithin was used instead of 4).
A glossy inkjet recording paper was obtained in the same manner as in.

Comparative Example 4 In the coating liquid for the gloss layer, instead of the methyl vinyl ether-maleic anhydride copolymer (manufactured by Toho Kagaku Co., trade name: Bismar YK-1S), acrylonitrile-acryl having a weight average molecular weight of 1,000,000 was used. A glossy inkjet recording paper was obtained in the same manner as in Example 1 except that an acid copolymer (manufactured by BASF Japan Ltd., trade name: Sterochol SL) was used.

Comparative Example 5 In the coating liquid for the gloss layer, polyethylene wax (manufactured by Nisshin Chemical Laboratory Co., Ltd., trade name: Kretex PN-14) was used.
Luster inkjet recording in the same manner as in Example 1 except that lecithin was used in place of 4) and methyl vinyl ether-maleic anhydride (manufactured by Toho Chemical Co., Ltd., trade name: Bismar YK-1S) was not added. I got the paper.

(Evaluation Method) Surface smoothness of glossy inkjet recording papers obtained in Examples and Comparative Examples, 75 ° surface glossiness, inkjet recording suitability, print density, stability of coating liquid for glossy layer, and continuous operation. Table 1 shows the results of sex evaluation
It was shown to. Each evaluation was performed by the following method.

[Surface smoothness] The smoothness of the surface of the glossy inkjet recording paper was visually evaluated. ◯: The surface is mirror-like and has extremely high smoothness. Δ: Smoothness is slightly inferior, but at a level where there is no practical problem. X: Surface is rough and gloss is low.

[75 ° Surface Glossiness] The surface of glossy inkjet recording paper was measured for 75 ° surface glossiness according to JIS-P8142.

[Inkjet recording suitability] (inkjet recording ink absorbency) Printing was performed with a color inkjet printer (trade name: BJF-870) manufactured by Canon Inc., and the drying property of the ink was visually evaluated. ○: Immediately after printing, there is no stain even if touched with a finger. B: Immediately after printing, it is slightly soiled when touched with a finger, but there is no practical problem. X: Due to poor drying of the ink, the ink flows during printing and cannot be used practically.

[Printing Density] Solid black printing is performed with a color ink jet printer (BJF-870, manufactured by Canon Inc.), and the printing density of that portion is measured by a Macbeth reflection densitometer RD-914 (Macbeth PROCESS).
It was measured by MEASURMENT).

[Stability of Coating Solution for Gloss Layer] ◯: Stable coating is possible. Δ: The viscosity of the coating liquid is high, but coating is possible. X: The coating liquid gelled and coating was impossible.

[Continuous operability] For each Example and Comparative Example, a 2000 m trial was made, and the cloudiness of the mirror surface drum was visually observed and evaluated according to the following criteria. ⊚: No fog is observed on the mirror drum surface. ◯: A slight amount of fogging is recognized on the mirror drum surface, but there is no problem in long-term continuous operability. Δ: Fogging is observed on the mirror drum surface, which causes a problem in long-term continuous operation. ×: The surface of the mirror surface drum is clouded and continuous operation is impossible.

[0072]

[Table 1]

[0073]

The glossy ink jet recording paper of the present invention is excellent in ink jet recording suitability such as surface smoothness, glossiness, ink absorptivity and print density, and is excellent in stability of coating liquid and continuous operability. , Practically very useful.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 FC06                 2H086 BA01 BA16 BA33 BA36 BA41                 4D075 AE03 BB24Z CA07 CA35                       CA48 CB04 DA04 DB18 DC27                       EA10 EA37 EB07 EB12 EB13                       EB14 EB15 EB19 EB20 EB22                       EB35 EB37 EB38 EB42 EB52                       EB56 EC01 EC07 EC13 EC33                       EC54 EC60

Claims (6)

[Claims] 1. A gloss ink jet recording paper comprising a support, an undercoat layer containing a pigment and an adhesive, and a gloss layer containing a pigment, an adhesive and a release agent on the undercoat layer. A glossy inkjet recording paper, wherein the release agent contains at least polyethylene and the gloss layer contains a methyl vinyl ether-maleic anhydride copolymer. 2. The glossy inkjet recording paper according to claim 1, wherein the methyl vinyl ether-maleic anhydride copolymer has a weight average molecular weight of 100,000 to 5,000,000. 3. A pigment 1 for the gloss layer, comprising the polyethylene.
The glossy inkjet recording paper according to claim 1, which is contained in an amount of 0.5 to 5.0 parts by mass with respect to 00 parts by mass. 4. The methyl vinyl ether-maleic anhydride copolymer is contained in an amount of 0.5 to 5.0 parts by mass based on 100 parts by mass of the pigment of the gloss layer. Glossy inkjet recording paper. 5. The gloss layer is formed by press-contacting with a heated mirror surface drum and drying the layer while the layer obtained by applying the coating solution for the gloss layer is in a wet state. 4. The glossy inkjet recording paper according to any one of 4 above. 6. A surface gloss of 75 ° on the surface of a gloss layer (JIS-
The gloss inkjet recording paper according to claim 1, having a glossiness based on Z8741) of 30% or more.