JP2007050562A - Inkjet recording paper - Google Patents

Abstract

The present invention provides an ink jet recording paper that satisfies both the prevention of paper feed flaws and good ink absorptivity and satisfies the required characteristics of various ink jet recording papers.
In an ink jet recording paper having an undercoat layer containing at least a pigment and an adhesive and an ink receiving layer containing at least the pigment and an adhesive on a paper substrate, the undercoat layer is a plastic pigment as a pigment. The ink receiving layer contains silica having an average secondary particle size of 2.5 to 11 μm as a pigment, an adhesive, and a cationic ink fixing agent. After forming the ink receiving layer, the ink receiving layer is calendered. An ink jet recording paper characterized by comprising:
[Selection figure] None

Description

  The present invention relates to an inkjet recording paper.

  The ink jet recording system that ejects water-based ink from fine nozzles toward the surface of the recording body and forms an image on the surface of the recording body has low noise during recording, easy formation of full-color images, and high-speed recording The printer is widely used in printers, facsimiles, plotters, form printing, and the like because of the fact that it is possible and the recording cost is lower than other printing apparatuses.

Various basic characteristics such as ink absorptivity, ink fixing property, color development property of the printing portion and storage stability thereof, whiteness of white paper portion and storage stability thereof are required for the recording medium in this ink jet recording system. .
In addition, ink jet recording papers corresponding to dye ink and pigment ink have been developed so far, but ink jet recording satisfying the above-mentioned basic characteristics regardless of whether dye ink or pigment ink is used. There is an increasing demand for paper.

  On the other hand, from the viewpoints of global environmental conservation and forest resource protection, efforts to increase the rate of utilization by increasing the recycling of used paper are also required.

More recently, in order to prevent displacement of the ink jet recording paper (paper blurring) when printing on ink jet recording paper due to higher printing speed, higher image quality, and downsizing of the printing apparatus, the ink jet recording paper is used. The load applied by the paper feed roller for fixing the position of the is increased.
For this reason, there is a tendency for printed matter to have a problem that a trace of conveyance by the paper feed roller (hereinafter referred to as a paper feed flaw) remains, and it is very important to prevent this paper flaw. It has become like this.
As a method for preventing paper feed damage caused by the paper feed roll, a method of using polyvinyl alcohol having a high polymerization degree as an adhesive (Patent Document 1) has been proposed.
JP-A-10-129112

  However, although the ink jet recording paper described in Patent Document 1 shows improvement in the effect of preventing paper feed scratches, the ink absorbability, the color developability of the printing portion and its preservability, the whiteness of the white paper portion and its preservability Was not satisfactory enough.

In order to prevent paper feed damage by the paper feed roller of the ink jet recording paper, it is considered effective to increase the coating film strength of the coating layer of the ink jet recording paper by pressurizing treatment or the like.
However, when the pressure treatment is performed, it is expected that the pigment in the coating layer is crushed, and therefore the ink absorbability of the ink jet recording paper is lowered.

  The present invention has been made in view of the above circumstances, and is compatible with both prevention of paper feed flaws and good ink absorption, and required characteristics of ink jet recording paper such as whiteness of a white paper portion and storage stability thereof. An ink jet recording paper satisfying the above is provided. In particular, the present invention provides an ink jet recording paper that exhibits excellent characteristics even when recycled paper recycled pulp is used as a paper base material.

As a result of intensive studies, the present inventors have found that the above problem can be solved by providing a paper substrate with an undercoat layer containing a plastic pigment and an ink receiving layer, and performing a calendar treatment. It came to complete.
That is, the present invention
(1) In an inkjet recording paper in which an undercoat layer containing at least a pigment and an adhesive and an ink receiving layer containing at least the pigment and an adhesive are provided on a paper substrate, the undercoat layer has a plastic pigment as a pigment. And the ink receiving layer contains silica having an average secondary particle size of 2.5 to 11 μm as a pigment, an adhesive, and a cationic ink fixing agent, and is calendered after forming the ink receiving layer. This is an ink jet recording sheet.
(2) The inkjet recording paper according to (1), which is calendered with a linear pressure of 10 to 110 kg / cm after the ink receiving layer is formed.
(3) The inkjet recording paper according to (1) or (2), wherein the particle diameter of the plastic pigment is 0.1 to 5 μm.
(4) The ink jet recording paper according to any one of (1) to (3), wherein the plastic pigment is a hollow plastic pigment.
(5) The adhesive in the undercoat layer contains at least one emulsion-type adhesive selected from an acrylic polymer, an ethylene-vinyl acetate copolymer and a vinyl acetate polymer (1) to (4) The inkjet recording paper according to any one of the above.
(6) The ink jet recording paper according to any one of (1) to (5), wherein the paper base material includes 10% or more of recycled paper recycled pulp among the pulp constituting the paper base material.

  According to the present invention, it is possible to provide an ink jet recording sheet that satisfies both of the requirements for ink jet recording paper, such as whiteness of a white paper portion and storage stability, as well as prevention of paper feed damage and good ink absorption. Can do. In particular, it is possible to provide an ink jet recording paper that exhibits excellent characteristics even when used paper recycled pulp is used as a paper base material.

<Inkjet recording paper>
(Layer structure)
The present invention is an inkjet recording paper in which an undercoat layer and an ink receiving layer are provided on at least one surface side of a paper substrate.
In the present invention, a similar undercoat layer and ink receiving layer may be provided on the other side of the paper substrate. In this case, the effects of the present invention can be exhibited on both sides of the inkjet recording paper.
Each of the undercoat layer and the ink receiving layer may be composed of a plurality of layers.

(Paper substrate)
Pulp used as the main component of the paper base includes chemical pulps such as LBKP (broadwood bleached kraft pulp) and NBKP (softwood bleached kraft pulp), mechanical pulps such as GP (ground pulp) and TMP (sir is also mechanical pulp) And recycled paper recycled pulp. These may be used alone or in combination of two or more. In this, it is preferable to mix | blend LBKP as a main component in a pulp. Moreover, although the beating degree is not particularly limited, it is preferable to beat so that the freeness is about 200 to 500 ml (CSF: JIS-P-8121). If the freeness is small, cockling tends to deteriorate when printed, and if the freeness is large, smoothness tends not to be obtained.

Since the ink jet recording paper of the present invention has an undercoat layer containing a specific material, usually, recycled pulp or mechanical pulp that is avoided use as a pulp for ink jet recording paper is blended with a paper base, An ink jet recording paper excellent in the whiteness of the white paper portion and its preservability can be obtained.
Of the 100% by mass of pulp used for paper-making on a paper base, it is preferable to use 10% by mass or more of recycled paper because it is possible to use resources effectively by using waste paper.
According to the present invention, even when the total amount of pulp, preferably 10 to 100% by mass, is used as recycled paper, the whiteness of the white portion of the ink jet recording paper and its preservability are good.
Examples of the waste paper used as a raw material for recycled paper pulp include newspaper waste paper, magazine waste paper, paperboard waste paper, wrapping paper waste paper, corrugated paper waste, printed waste paper, and the like, as well as loss of quality paper, coated paper, etc. generated during paper manufacture. Paper may be included.
Waste paper recycled pulp is generally used to dispose of waste paper and waste paper using a low-concentration pulper or a high-concentration pulper, a coarse or selective process using a screen or cleaner, a deinking process using a flotation method or a water washing method, chlorine bleaching, It can be obtained by appropriately combining bleaching steps such as chlorine bleaching, sodium hypochlorite bleaching and oxygen bleaching.

In addition to the above pulp, a filler is blended in the paper base material.
The filler is blended for the purpose of adjusting the air permeability of the paper substrate, imparting opacity, etc., or adjusting the ink absorbability.
As the filler, for example, clay, kaolin, calcined kaolin, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, calcium hydroxide, silica, titanium oxide and the like can be used as appropriate. Among them, calcium carbonate is preferable because it becomes a paper base having high whiteness.
It is preferable that a filler contains 1-35 mass parts with respect to 100 mass parts of the said whole pulp. If the amount of the filler is small, not only will the whiteness decrease, but the ink absorbency will tend to decrease. If it is too large, the paper stiffness (stiffness) will tend to decrease and the paper strength will decrease. Mixing causes yellowing of the ink jet recording paper surface.

Various types of anionic, nonionic, cationic or amphoteric steps that have been used in the past can be used in the paper stock containing the pulp and filler as long as the desired effects of the present invention are not impaired. Various internal additives for papermaking, such as a retention improver, a freeness improver, a paper strength enhancer, and an internal sizing agent, can be appropriately selected and used as necessary. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be added as necessary. In the ink jet recording paper of the present invention, when a large amount of fluorescent brightening agent is blended, the storage stability of the white paper portion may deteriorate.
As a papermaking method, it can be produced using a known papermaking machine such as a long net papermaking machine, a circular netting papermaking machine, or a twin wire type papermaking machine.

The paper base material is classified into acidic paper and neutral paper depending on the pH of the papermaking raw material (stock material). As the paper base material used in the present invention, neutral paper is preferable in terms of long-term storage stability.
In addition, starch, polyvinyl alcohol, cationic resin, or the like can be coated and impregnated on the surface by a size press or the like to improve surface smoothness, improve strength, printability, and writing ability.
The basis weight of the paper substrate is not particularly limited, but is about ²⁰ to 400 g / m ² .

(Undercoat layer)
The undercoat layer in the present invention contains a plastic pigment as a pigment.

[Pigment]
As the plastic pigment, existing resin fine powders and emulsions can be used. Examples of this include urea-formalin resin, silicone resin, polystyrene, acrylic-styrene resin, nylon, benzoguaminane resin, tetrafluoroethylene resin, acrylic resin, polymethyl methacrylate, polyethylene, polypropylene, polyamide, cellulose-acetate-butyrate resin. Organic polymer fine particles such as ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, and phenol resin.
The particle diameter of the plastic pigment is preferably 0.1 to 5.0 μm, more preferably 0.3 to 3.0 μm. If the particle size is small, the strength and color developability tend to decrease. If the particle size is large, the sharpness of the image tends to decrease, and a smooth and uniform surface may not be obtained.

There are various types of plastic pigments, such as a solid type and a through-hole type, and any of them can be used. However, since the whiteness and concealability are improved, a hollow shape is used. Is preferred. The hollow plastic pigment is one having a single or a plurality of independent vacancies or vacancies having communication holes with each other inside the particles.
Moreover, you may use the perforated hollow plastic pigment which has the space | gap which connects these internal void | holes (hollow part) and the particle | grain outside in a particle wall.

  In the present invention, by forming an undercoat layer containing a plastic pigment, it is possible to obtain excellent color developability and preservability of a printed portion, whiteness of a white paper portion and preservability thereof. The reason why this effect can be obtained is considered as follows.

Silica is generally known as a pigment used in ink jet recording paper.
Silica has the advantage of superior ink absorption compared to other pigments, but on the other hand, because it has high light, water, and gas permeability, for example, direct ink acceptance on a paper substrate using recycled paper. When the layer is formed, only low whiteness can be obtained, and there is a problem that the color developability of the printing portion is lowered due to low whiteness.
Therefore, even if such an undercoat layer mainly composed of silica is further formed between the paper substrate and the ink receiving layer, sufficient whiteness cannot be obtained.

  On the other hand, the plastic pigment has high concealability and does not cause oxidation of the cationic ink fixing agent, which is estimated as one of the causes of yellowing of the inkjet recording paper surface. Therefore, by forming an undercoat layer using a plastic pigment as a pigment, the whiteness of a white paper portion and its storability in an ink jet recording paper are improved, and excellent color development and storability of a printing portion can be obtained. It is considered a thing.

[adhesive]
The undercoat layer in the present invention contains an adhesive.
Although it does not specifically limit as an adhesive agent, It is using combining at least 1 sort (s) of emulsion type adhesives chosen from an acrylic polymer, an ethylene-vinyl acetate type copolymer, and a vinyl acetate type polymer. preferable.

Examples of the acrylic polymer used in the emulsion type adhesive include polymers containing (meth) acrylic units such as acrylic acid, methacrylic acid, acrylic ester, and methacrylic ester. The acrylic polymer may be a homopolymer of (meth) acrylic units, a copolymer, or a copolymer containing other structural units. Examples of the acrylic polymer include polymethyl (meth) acrylate.
As an ethylene-vinyl acetate copolymer, ethylene and vinyl acetate are the main components, and as other monomers, for example, (meth) acrylic esters such as 2-ethylhexyl acrylate, vinyl acetate such as vinyl versatate Examples thereof include those obtained by copolymerizing monomers containing a functional group such as vinyl acid and acrylic acid.
The vinyl acetate polymer may be any polymer containing vinyl acetate units, and polyvinyl acetate is preferred.

  In general, emulsion type adhesives and water-soluble adhesives other than those described above are known as adhesives, but when conjugated diene resins such as styrene-butadiene resin and methyl methacrylate-butadiene copolymer are used for the undercoat layer, The color developability of the printed portion cannot be obtained, and the yellowing of the blank paper portion occurs with time. Also, when using a water-soluble adhesive such as starch or polyvinyl alcohol, when preparing a coating solution for the undercoat layer, it cannot be prepared to a high concentration coating solution. The whiteness of the blank paper portion, its storage stability, and the print density cannot be achieved.

  The blending ratio of the pigment and the adhesive is about 2 to 30 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the pigment. When the amount of the adhesive is small, the coating strength of the undercoat layer is lowered. On the other hand, when the amount of the adhesive is large, the ink absorption amount is lowered, the color developability of the printed portion is deteriorated and the whiteness tends to be lowered. .

[Other ingredients]
For the undercoat layer, for example, calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, as long as the effects of the present invention are not impaired. Inorganic pigments such as magnesium silicate, aluminum hydroxide, alumina, pseudoboehmite, lithopone, zeolite, hydrous halloysite, magnesium carbonate, and magnesium hydroxide can be blended.

  Further, the undercoat layer is not limited to the effects of the present invention, for example, proteins such as casein, soy protein, synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohol and derivatives thereof, carboxymethylcellulose, Conventionally known adhesives generally used for inkjet recording, such as cellulose derivatives such as methylcellulose, styrene-butadiene resins, and conjugated diene resins of methyl methacrylate-butadiene copolymers can be used in combination.

  Furthermore, in the undercoat layer, a thickener, an antifoaming agent, a wetting agent, a colorant, a fluorescent dye, a fluorescent pigment, an antistatic agent, which are used in general coated paper production, as long as the effects of the present invention are not impaired. Various auxiliary agents such as a light resistance auxiliary agent, an ultraviolet absorber, an antioxidant and a preservative are appropriately added.

The undercoat layer can be formed by applying an undercoat layer coating solution containing the above pigment, adhesive, and, if desired, an inorganic pigment to the surface of the paper substrate and drying it.
The coating amount (solid content) of the undercoat layer is about 3 to 20 g / m ² , preferably 5 to 15 g / m ² , more preferably 7 to 13 g / m ² . If the coating amount is too small, high whiteness cannot be obtained, and yellowing tends to occur. If the coating amount is excessive, the effect is saturated and the interlayer strength tends to be weakened.

Examples of the coating apparatus for forming the undercoat layer include various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater. Can be mentioned.
In addition, you may finish using calendars, such as a machine calendar, a TG calendar, a super calendar, and a soft calendar, after coating.

(Ink receiving layer)
The ink receiving layer in the present invention contains silica having a specific particle diameter as a pigment, an adhesive, and a cationic ink fixing agent.

[Pigment]
Silica is used as the pigment, and amorphous silica is preferably used.
The method for producing silica is not particularly limited, and may be produced by any method of electric arc method and dry method (for example, precipitation method, gel method), but wet method silica is an inkjet recording paper for pigment ink. It is preferable because it is suitable for any ink jet recording paper for dye ink.

Silica having an average secondary particle size of 2.5 to 11 μm is used, but 4 to 10 μm is more preferable.
When the average particle diameter of silica is less than 2.5 μm, when the ink is used for ink jet recording paper and printing is performed with dye ink, the dye ink absorbability decreases and the light transmittance becomes higher. Since the light resistance of the printing part by ink falls and light transmittance becomes higher, the light resistance of the printing part by dye ink falls and coating-film intensity | strength falls. In addition, when printing is performed with pigment ink using the ink jet recording paper, adverse effects such as deterioration of the fixing property of the pigment ink are caused.
On the other hand, when the average particle diameter of silica exceeds 11 μm, both when using dye ink for printing and when using pigment ink, image sharpness decreases due to low print density and surface roughness is conspicuous. Problems such as uneven printing are likely to occur.
Furthermore, it is preferable that the oil absorption amount according to JIS K-5101 of silica is 210-250 cm < ³ > / 100g from the point which is excellent in the color development property of the printing part at the time of recording with dye ink and pigment ink.

In the present invention, as the silica contained in the ink receiving layer, it is preferable to use silica (surface-treated silica) whose surface is treated with a surfactant on at least a part thereof. That is, all of the silica may be surface-treated silica, or both surface-treated silica and untreated silica.
As the untreated silica, the silica used in the above-described invention can be used as it is. As the silica whose surface is treated with a surfactant, the same silica as described above is used.

Examples of the surfactant that treats the surface of silica include nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants. Among these, nonionic surfactants are exemplified. Agents are preferred.
Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene copolymer, polyoxyethylene polyoxypropylene alkyl ether, and the like. Among them, the HLB value (hydrophilic-lipophilic balance value) is preferably 8.0 to 15.0, and more preferably 10.0 to 12.0. If the HLB value is less than 8.0, a sufficient ink absorption rate tends to be difficult to obtain, and if the HLB value exceeds 15.0, bleeding tends to occur.

As a method for treating the surface of the silica with a surfactant, for example, a method described in JP-A-9-25440 can be employed. That is, it is possible to employ a dry mixing method in which silica, for example, wet method silica, and a surfactant, for example, a snake-chain type nonionic surfactant, are mixed with a mixer such as a high-speed flow mixer. In this case, the surfactant may be directly added to and mixed with silica, or the surfactant may be added and mixed with a surfactant diluted with a production solvent such as ethanol.
It is also possible to employ a wet processing method in which a predetermined amount of a surfactant, for example, a nonionic surfactant, is added to and mixed with an emulsified slurry of silica, for example, wet method silica, followed by spray drying. it can. In the case of the wet processing method, if the surfactant is poorly soluble in water, it should be strongly dispersed in advance to form an emulsion, and this emulsion is added to the pigment emulsified slurry liquid and thoroughly stirred and mixed before drying. Is preferred.
Silica whose surface is treated with a surfactant by such a method is considered to be in a state where the surface is coated with the surfactant.

  The amount of surfactant added to silica is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass per 100 parts by mass of silica. Preferably, when silica coated with a surfactant in such a range is blended, the color developability of the printed portion is improved and a clear image can be obtained.

[adhesive]
The adhesive is not particularly limited, and is a water-soluble adhesive such as starch or polyvinyl alcohol, an acrylic polymer, an ethylene-vinyl acetate copolymer, a vinyl acetate polymer, a urethane polymer, or styrene. -Conventionally known adhesives generally used for ink jet recording, such as butadiene copolymers or emulsion type adhesives thereof. These may use only 1 type and may use 2 or more types of adhesives together.

Among the above adhesives, acrylic polymer emulsion adhesives are preferred.
Examples of the acrylic polymer include polymers containing (meth) acrylic units such as acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester.
The acrylic polymer may be a homopolymer of (meth) acrylic units, a copolymer, or a copolymer containing other structural units. Examples of the acrylic polymer include polymethyl (meth) acrylate.

In addition, it is preferable to use polyvinyl alcohol together with an acrylic polymer emulsion-type adhesive because of good adhesion to the pigment.
As the polyvinyl alcohol, polyvinyl alcohol derivatives such as silanol-modified polyvinyl alcohol and cationized polyvinyl alcohol can also be used as appropriate.
In addition, when using together an acrylic polymer and polyvinyl alcohol or its derivative (s), it is preferable to use together by the ratio of 1: 10-2: 1, and it is more preferable to use together by the ratio of 1: 5 to 1: 1.
As content of an acrylic polymer, it is preferable that it is 1-50 mass parts with respect to 100 mass parts of silica, and it is more preferable that it is 5-40 mass parts.

In general, many adhesives such as emulsion type adhesives and water-soluble adhesives are known as adhesives. However, as a result of intensive studies, when acrylic polymer emulsion type adhesives are used, printing can be performed using either dye ink or pigment ink. However, the present inventors have found that a clear image can be obtained and that the preservability of the white paper portion is also excellent.
Incidentally, all of the typical emulsion-type adhesives used in ink jet recording paper are ethylene-vinyl acetate copolymer, vinyl acetate polymer, urethane polymer, styrene-butadiene copolymer, etc. It is inferior to an acrylic polymer in terms of color developability of the printed part, and a urethane polymer and a styrene-butadiene copolymer tend to yellow the blank paper part and are inferior in storage stability of the blank paper part. There is a problem.
In addition, when only water-soluble adhesives such as starch and polyvinyl alcohol are used, sufficient coating strength cannot be obtained, and when preparing a coating solution for the ink receiving layer, a high concentration coating solution is used. There is a problem in that it cannot be prepared and when coated, the coating amount is small and a clear image cannot be obtained.

[Cationic ink fixing agent]
The cationic ink fixing agent is not particularly limited,
1) Polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof,
2) an acrylic polymer having a secondary amino group, a tertiary amino group or a quaternary ammonium group,
3) polyvinylamine, polyvinylamidine, five-membered ring amidines,
4) Dicyan cationic resin represented by dicyandiamide-formalin copolymer,
5) Polyamine cationic resin represented by dicyandiamide-polyethyleneamine copolymer,
6) Dimethylamine-epichlorohydrin copolymer,
7) Diallyldimethylammonium-SO ₂ copolymer,
8) diallylamine salt-SO ₂ copolymer,
9) Dimethyl diallylammonium chloride polymer,
10) Polymer of allylamine salt,
11) Dialkylaminoethyl (meth) acrylate quaternary salt copolymer,
12) Acrylamide-diallylamine salt copolymer,
13) Aluminum salts such as polyaluminum chloride and polyaluminum acetate,
14) Commonly commercially available materials such as water-soluble metals such as zinc sulfate can be used, and they can be used alone or in combination of two or more.

  Among these, it is preferable to use a dicyandiamide-polyethyleneamine copolymer and an acrylamide-diallylamine copolymer in combination. It is preferable to use these in combination because the color developability of the print portion when recorded with pigment ink, the color developability of the print portion when recorded with dye ink, and the storage stability thereof are excellent. Furthermore, the combined use of zinc sulfate is more preferable because the color developability of the printed portion when printed with pigment ink is greatly improved.

  As a compounding quantity of a cationic ink fixing agent, 5-60 mass parts is preferable with respect to 100 mass parts of silica, More preferably, it adjusts in the range of 20-50 mass parts. If the cationic ink fixing agent is less than 5 parts by mass, the color developability of the printed part and the storage stability of the printed part are liable to occur. Therefore, the sharpness of the image is likely to deteriorate.

For the ink-receiving layer, thickeners, antifoaming agents, wetting agents, surfactants, colorants, antistatic agents, light fastness aids, UV absorbers, antioxidants used in general coated paper production Various auxiliary agents such as preservatives and preservatives are appropriately added.
In the ink jet recording paper of the present invention, a high whiteness can be realized without substantially including a fluorescent brightening agent in the ink receiving layer, so that a good storage stability of the white paper portion can be obtained.

The coating amount of the ink receiving layer is not particularly limited, but is preferably ² to 30 g / m ^{2 and} more preferably 5 to ²⁰ g / m ² .
If the coating amount is less than the above lower limit, the ink absorbency, image sharpness, and storability of the printed part are likely to be lowered.If the coating amount is larger than the upper limit, the coating strength and the image sharpness are lowered. easy.
As described above, the ink receiving layer may be composed of a plurality of layers, and in this case, the ink receiving layer composition may be different between the layers.

  The ink receiving layer can be formed by various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater.

(Calendar processing)
The inkjet recording paper of the present invention has been subjected to a calendar process.
Thereby, when feeding ink jet recording paper by the ink jet recording method, it is possible to prevent a paper feed flaw that is a conveyance trace by the paper feed roller. This is considered to be due to the fact that the coating film strength of the coating layer is increased by the calendering process, so that it is difficult to damage the paper feed.
The ink-jet recording paper of the present invention does not lose ink absorbency despite being subjected to a calendar process. This is because a layer containing a plastic pigment is provided as an undercoat layer, so that even if pressure is applied by calendering, the silica of the ink receiving layer is not easily crushed due to the cushioning property of the plastic pigment, and voids (pore volume) are generated. This is considered to be maintained.
As a method of the calendar process, a pressurizing device such as a machine calendar, a super calendar, a soft calendar is used.

The linear pressure in the calendar process is preferably 10 to 110 kg / cm, and more preferably 20 to 70 kg / cm.
By setting the linear pressure of the calendar process to 10 kg / cm or more, the coating film strength of the coating layer is increased, and paper feed damage can be prevented.
By setting the linear pressure of the calendar process to 110 kg / cm or less, better ink absorbability can be obtained. Further, it is possible to suppress the gloss of the high density printed portion that is easily developed when printing with the pigment ink and to prevent the deterioration of the texture.

<Printed matter>
The printed matter of the present invention can be produced by printing on the inkjet recording paper of the present invention with a dye ink or pigment ink using a printer such as a printer.
At this time, paper feed scratches caused by the paper feed roller when feeding the ink jet recording paper by the ink jet recording method are prevented, and good ink absorbability and sufficient color development of the printed part can be achieved using either dye ink or pigment ink. Sex is achieved.
Furthermore, regardless of whether dye ink or pigment ink is used, the storability of the printed part (for example, light resistance, ozone resistance, water resistance) and the storability of the blank paper part (for example, heat resistance, light resistance, ozone resistance) ) Is obtained, and this printed material is suitable for a wide range of applications, for example, for outdoor display.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are solid content except water, and show a mass part and mass%, respectively. Hereinafter, “secondary particle diameter” means an average secondary particle diameter.

Example 1
[Paper Base A]
20 parts of light calcium carbonate, hardwood bleached kraft pulp (freeness 400mlCSF) 1
Add to 00 parts of slurry, add 1 part of cationic starch and 0.2 part of alkenyl succinic anhydride neutral sizing agent, mix well to make papermaking raw material, using a long mesh multi-cylinder paper machine 1 moisture
It was dried to 0%, and a 7% solution of oxidized starch was applied at 4 g / m ² on both sides with a size press, dried, and dried to a moisture content of 7% to produce a paper base A having a weight of 200 g / m ² .

[Undercoat layer coating liquid A]
As a pigment, hollow plastic pigment (styrene-acrylic copolymer particles, manufactured by Rohm and Haas, trade name: Ropeke HP-91, average particle size 1 μm), 100 parts, and as an adhesive, an acrylic polymer (Rohm and Haas) Co., Ltd., trade name: Primal P-376, emulsion type adhesive) 10 parts and oxidized starch (made by Oji Cornstarch Co., Ltd., trade name: Ace A, water-soluble adhesive) 5 parts, dispersed in water, undercoat coating Liquid A was obtained.

[Ink-receiving layer coating solution A]
Wet silica (trade name: Fine Seal X-60, secondary particle diameter 6.2 μm) 100 parts as pigment, silyl-modified polyvinyl alcohol (trade name: R-1130) 20 as adhesive Parts and acrylic resin (Rohm and Haas, product name: Primal P-376), 15 parts of acrylamide-diallylamine copolymer (product name: SR1001) as an ink fixing agent, and dicyandiamide-polyethylene 15 parts of an amine copolymer (manufactured by Nikka Chemical Co., Ltd., trade name: Neofix IJ-117) was dispersed in water to obtain an ink-receiving layer coating solution A.

[Preparation of inkjet recording paper]
After coating and drying the undercoat layer coating solution A on the paper substrate A so that the coating amount is 10 g / m ² , the ink receiving layer coating solution A is applied with a coating amount of 10 g / m ² . After coating and drying, a calendar process was performed at a linear pressure of 50 kg / cm to prepare an ink jet recording paper. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 2
[Paper Base B]
20 parts of light calcium carbonate, hardwood bleached kraft pulp (freeness 400mlCSF) 7
Add 0 parts and 30 parts of deinked pulp (freeness 250 ml CSF) of the deinked pulp, add 1 part of cationic starch and 0.2 part of alkenyl succinic anhydride neutral sizing agent, The paper is made into a papermaking raw material, dried to a 10% moisture content using a long-mesh multi-cylinder paper machine, coated with a 7% solution of oxidized starch at 4 g / m ² on both sides with a size press, dried, and dried with a moisture content of 7%. The paper base B having a weight of 200 g / m ² was produced.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 1 except that the paper base A in Example 1 was changed to the paper base B. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 3
[Paper Base C]
20 parts of light calcium carbonate, 70 parts of hardwood bleached kraft pulp (freeness 400 ml CSF) and old colored paper (colored old paper: high-quality printed paper including art paper) (pulp freeness 250 ml CSF) Add to 30 parts of mixed slurry, add 1 part of cationic starch, 0.2 part of alkenyl succinic anhydride neutral sizing agent, mix well to make papermaking raw material, using a long mesh multi-cylinder paper machine Dry to 10%, apply 7g solution of oxidized starch with 4g / m ² on both sides with a size press, dry, and dry to 7% to produce paper base C with 200g / m ² did.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 1 except that the paper base A in Example 1 was changed to the paper base C. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 4
[Undercoat layer coating solution B]
As a pigment, hollow plastic pigment (styrene-acrylic copolymer particles, manufactured by Rohm and Haas Co., Ltd., trade name: Ropeke OP-84J, average particle size 0.5 μm), 100 parts, acrylic polymer (Rohm as an adhesive) Andhers, trade name: Primal P-376, emulsion type adhesive) 10 parts and oxidized starch (Oji Cornstarch, trade name: Ace A, water-soluble adhesive) 5 parts, dispersed in water, undercoat layer A coating liquid B was obtained.

[Preparation of inkjet recording paper]
An ink jet recording sheet was prepared in the same manner as in Example 2 except that the undercoat layer coating solution A was changed to the undercoat layer coating solution B. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 5
[Undercoat layer coating solution C]
As pigment, 100 parts of plastic pigment (styrene-acrylic copolymer particles, manufactured by Rohm and Haas, trade name: Ropeke HP-91, average particle size: 1.0 μm), ethylene-vinyl acetate copolymer as an adhesive ( Showa Polymer Co., Ltd., trade name: Polysol AM-3000, emulsion type adhesive) 10 parts and oxidized starch (Oji Cornstarch, trade name: Ace A, water-soluble adhesive) 5 parts, dispersed in water, undercoat A layer coating solution C was obtained.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the undercoat layer coating solution A was changed to the undercoat layer coating solution C. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 6
[Undercoat layer coating solution D]
As pigment, 100 parts of plastic pigment (styrene-acrylic copolymer particles, manufactured by Rohm and Haas Co., Ltd., trade name: Ropeke HP-91, average particle size: 1.0 μm), vinyl acetate polymer (Nisshin) as an adhesive Chemical Industry Co., Ltd., trade name: Vini Blanc 1080, emulsion type adhesive) 10 parts and oxidized starch (Oji Cornstarch Co., Ltd., trade name: Ace A, water-soluble adhesive) 5 parts, dispersed in water, undercoat coating Liquid D was obtained.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the undercoat layer coating solution A was changed to the undercoat layer coating solution C. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 7
[Undercoat layer coating solution E]
As a pigment, 100 parts of a plastic pigment (Rohm and Haas, trade name: HP-91, average particle size: 1.0 μm), as an adhesive, SBR (JSR, trade name: 0589, Tg: 0 ° C., emulsion 10 parts of a mold adhesive) and 5 parts of oxidized starch (manufactured by Oji Cornstarch Co., Ltd., trade name: Ace A, water-soluble adhesive) were dispersed in water to obtain an undercoat layer coating solution F.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the undercoat layer coating solution A was changed to the undercoat layer coating solution E. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 8
[Production of surface-treated silica]
900 g of wet silica (trade name: Fine Seal X-60, manufactured by Tokuyama Co., Ltd.) is suspended in water and slurried (about 10 to 15%), and a surfactant (polyoxyethylene lauryl ether, Daiichi Kogyo) is suspended in this slurry. 100 g of an aqueous suspension was added, and the mixture was stirred and mixed for 1 hour, manufactured by Pharmaceutical Co., Ltd., trade name: Neugen ET-102, HLB: 10.8). Subsequently, it was spray-dried and pulverized and classified to obtain surface-treated silica. The average secondary particle diameter of the obtained surface-treated silica was 6 μm.

[Ink-receiving layer coating solution B]
Wet silica (trade name: Fine Seal X-60, secondary particle size 6.2 μm) 80 parts as a pigment, 20 parts of the surface-treated silica obtained above, and silyl-modified polyvinyl alcohol (Kuraray Co., Ltd.) as an adhesive Product name: R-1130) 20 parts and acrylic resin (Rohm and Haas, product name: Primal P-376) 20 parts, acrylamide-diallylamine copolymer (product of Sumitomo Chemical Co., Ltd., product) Name: SR1001) 15 parts and 15 parts of dicyandiamide-polyethyleneamine copolymer (manufactured by Nikka Chemical Co., Ltd., trade name: Neofix IJ-117) were dispersed in water to obtain an ink receiving layer coating solution B.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the ink receiving layer coating liquid A in Example 2 was changed to the ink receiving layer coating liquid B. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained inkjet recording paper was 4%.

Example 9
[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the linear pressure of the calendar process in Example 2 was changed to 30 kg / cm. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 10
[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the linear pressure of the calendar process in Example 2 was changed to 100 kg / cm. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Example 11
[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the linear pressure of the calendar process in Example 2 was changed to 150 kg / cm. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained inkjet recording paper was 4%.

Comparative Example 1
[Preparation of inkjet recording paper]
On the paper substrate B, the ink receiving layer coating solution A is applied and dried so that the coating amount is 10 g / m ^2, and then calendered at a linear pressure of 50 kg / cm to provide an undercoat layer. Inkjet recording paper was prepared. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Comparative Example 2
[Undercoat layer coating solution F]
Wet silica (trade name: Fine Seal X-60, secondary particle size 6.2 μm) 100 parts as pigment, acrylic polymer (Rohm and Haas, trade name: Primal P-) as adhesive 376, emulsion type adhesive) 10 parts and oxidized starch (product name: Ace A, water-soluble adhesive) manufactured by Oji Cornstarch Co., Ltd. were dispersed in water to obtain an undercoat layer coating solution F.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the undercoat layer coating solution A was changed to the undercoat layer coating solution F. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Comparative Example 3
[Ink-receiving layer coating solution C]
Wet silica (trade name: Fine Seal F80, secondary particle diameter 1.8 μm) 100 parts as pigment, 20 parts of silyl-modified polyvinyl alcohol (trade name: R-1130), and acrylic as adhesive -Based resin (Rohm and Haas, trade name: Primal P-376), 15 parts of acrylamide-diallylamine copolymer (Sumitomo Chemical, trade name: SR1001) as an ink fixing agent and dicyandiamide-polyethyleneamine copolymer 15 parts of a product (manufactured by Nikka Chemical Co., Ltd., trade name: Neofix IJ-117) was dispersed in water to obtain an ink-receiving layer coating solution C.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the ink receiving layer coating liquid A in Example 2 was changed to the ink receiving layer coating liquid C. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained inkjet recording paper was 4%.

Comparative Example 4
[Ink-receiving layer coating solution D]
Wet silica as a pigment (manufactured by Mizusawa Chemical Co., Ltd., trade name: Mizukasil P-78F, secondary particle size 12.5 μm) 100 parts, silyl-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: R-1130) 20 parts as an adhesive And 20 parts of an acrylic resin (Rohm and Haas, trade name: Primal P-376), 15 parts of an acrylamide-diallylamine copolymer (trade name: SR1001) as an ink fixing agent, and dicyandiamide-polyethyleneamine. 15 parts of a copolymer (trade name: Neofix IJ-117, manufactured by Nikka Chemical Co., Ltd.) was dispersed in water to obtain an ink receiving layer coating solution D.

[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the ink receiving layer coating liquid A of Example 2 was changed to the ink receiving layer coating D. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

Comparative Example 5
[Preparation of inkjet recording paper]
An ink jet recording paper was prepared in the same manner as in Example 2 except that the calendar process in Example 2 was changed to that in which the calendar was not processed. The 60 ° specular glossiness defined by JIS-Z8741 of the blank surface portion of the ink receiving layer of the obtained ink jet recording paper was 3%.

[Evaluation]
Whiteness of ink jet recording paper obtained in each example and comparative example, storage stability of white paper portion (prevention of thermal yellowing, prevention of light yellowing, prevention of ozone yellowing), print density, ink absorption, ink fixing property, The glossiness of the printed part and the paper feed damage were evaluated by the following methods.
In the evaluation, printing on inkjet recording paper was performed using commercially available dye inkjet printer A (manufactured by Canon, trademark: PIXUS 950i, printing mode: matte photo paper / clean), commercially available pigment inkjet printer B (manufactured by EPSON, Trademark: PM-4000PX, ink: mat black used, print mode: photo matte paper / high definition), commercially available pigment inkjet printer C (manufactured by EPSON, trade name: PX-6000, print mode: photomat paper / clean) , And commercially available inkjet printer D (manufactured by HP, trademark: DJ-5551, print mode: other inkjet dedicated paper / clean).

[Whiteness]
The whiteness of the white paper portion on the ink receiving layer side of the ink jet recording paper was measured according to the method defined in JIS-P8123.

[Preservation of blank paper part (thermal yellowing)]
The ink jet recording paper was allowed to stand for 1 week in an environment of 80 ° C. and 50%. The degree of yellowing of the white paper portion on the ink receiving layer side of the paper before and after standing was determined visually according to the following criteria.
○: Almost no yellowing.
Δ: Level with no problem in practical use although yellowing occurs.
X: It is very yellowing.

[Preservation of blank paper part (light yellowing)]
The inkjet recording paper was irradiated with a xenon lamp (100,000 lux) for 3 days in an environment of 60 ° C. and 50%. The degree of yellowing of the white paper portion on the ink receiving layer side of the paper before and after irradiation was judged visually according to the following criteria.
○: Almost no yellowing.
Δ: Level with no problem in practical use although yellowing occurs.
X: It is very yellowing.

[Preservation of blank paper part (ozone yellowing)]
The ink jet recording paper was left in an atmosphere of ozone concentration of 10 ppm for 24 hours in an environment of 24 ° C. and 60%. The degree of yellowing of the white paper portion on the ink receiving layer side of the paper before and after being left was evaluated visually according to the following criteria.
○: Almost no yellowing.
Δ: Level with no problem in practical use although yellowing occurs.
X: It is very yellowing.

[Print density]
Print the image ("High-definition color digital standard image XYZ / JIS-SCID", identification symbol: S6, image name: color chart) issued by the Japanese Standards Association with the above four models, The print density was measured with RD-914 manufactured by GretagMacbeth.

[Ink absorbency]
Among the print density evaluations, the highest black tone portion of the recorded matter printed with a commercially available dye ink jet printer A (CANON, trademark: PIXUS950i, print mode: matte photo paper / clean) was observed.
○: No ink overflow, blurring or unevenness.
Δ: Ink overflow, blurring, and unevenness are slightly occurring, but there is no practical problem.
X: Ink overflows and unevenness occurs.

[Ink fixability]
Among those evaluated for the printing density, commercially available pigment inkjet printer B (manufactured by EPSON, trade name: PM-4000PX, ink: matte black used, printing mode:
The highest black tone portion of the recorded matter printed with photo matte paper (high definition) was rubbed with a finger one day after printing.
○: The printed part is not changed even when rubbed with a finger, and the ink fixing property is excellent.
X: When rubbed with a finger, the printed part is peeled off and the ink fixing property is inferior.

[Glossiness of printed part]
Commercially available pigment inkjet printer (manufactured by EPSON, trade name: PM-4000PX
, Ink: matte black used, print mode: photo matte paper / clean), and the glossiness at 85 ° defined by JIS-Z8741 of the black maximum density portion printed was measured.
○: Glossiness is less than 20% △: Glossiness is 20% or more and less than 25% ×: Glossiness is 25% or more

[Paper damage]
Among the print density evaluations described above, the black maximum tone portion of the recorded matter printed with a commercially available pigment inkjet printer C (manufactured by EPSON, trade name: PX-6000, print mode: photomat paper / clean) The presence or absence of paper feed flaws generated by the paper feed roller was observed.
○: Paper feed scratches by the paper feed roller are not recognized in the printing section.
Δ: Slight paper feed flaws by the paper feed roller are observed in the printing section.
X: Paper feed damage by the paper feed roller is observed in the printing section.

According to the present invention, paper feed scratches are difficult to occur when feeding a printer, both pigment ink and dye ink are excellent in ink jet recording suitability (color development), can print high-definition images clearly, and are particularly excellent in storage stability of a blank paper portion. Further, in order to effectively use limited resources, it is possible to provide an ink jet recording paper having a high whiteness on the paper surface, particularly a mat type ink jet recording paper with a small coating amount, while using waste paper.

Claims (6)

In an ink jet recording paper provided with an undercoat layer containing at least a pigment and an adhesive and an ink receiving layer containing at least the pigment and an adhesive on a paper substrate, the undercoat layer contains a plastic pigment as a pigment, The ink receiving layer contains silica having an average secondary particle size of 2.5 to 11 μm as a pigment, an adhesive, and a cationic ink fixing agent, and is formed by calendering after forming the ink receiving layer. Inkjet recording paper. 2. The ink jet recording paper according to claim 1, wherein the ink receiving layer is calendered at a linear pressure of 10 to 110 kg / cm after the ink receiving layer is formed. 3. The ink jet recording paper according to claim 1, wherein the particle diameter of the plastic pigment is 0.1 to 5 [mu] m. The inkjet recording paper according to any one of claims 1 to 3, wherein the plastic pigment is a hollow plastic pigment. The adhesive in the undercoat layer contains at least one emulsion-type adhesive selected from an acrylic polymer, an ethylene-vinyl acetate copolymer and a vinyl acetate polymer. The inkjet recording paper as described in any one of these. The inkjet recording paper as described in any one of Claims 1-5 in which a paper base material contains a recycled paper recycled pulp 10% or more among the pulp components which comprise a paper base material.