JP2006150724A - Inkjet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper which has excellent stable conveyability during printing and high image density. <P>SOLUTION: This inkjet recording paper has at least one porous ink absorption layer which contains an inorganic fine particle, a hydrophilic resin crosslinked by ionizing radiation and a nonionic surfactant or a betaine-type surfactant, formed on a support. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel ink jet recording paper having improved ink absorbability, image density and transportability during printing.

  Ink-jet recording is a method in which micro droplets of ink are ejected according to various operating principles and deposited on a recording sheet such as paper to record images and characters. Has advantages such as being easy.

  With regard to nozzle clogging and maintenance, which has been a problem in the above-described inkjet recording method, improvements have been made from both sides of the ink and the device, and now it is rapidly spreading to various fields such as various printers, facsimiles, computer terminals, etc. is doing.

  In recent years, the quality of printers has been increasing and the photographic image quality has been reached. Therefore, inkjet recording paper is also required to achieve photographic image quality and to reproduce the texture of photographs (gloss, smoothness, stiffness, etc.). ing.

  In general, a water-absorbing support such as paper and a non-water-absorbing support such as a polyester film or a resin-coated paper are known as the support used in the ink jet recording paper. The former has the advantage that the support itself can absorb ink, and thus has the advantage of having a high ink absorption ability, but on the other hand, there is a problem that wrinkles are generated after printing due to the water absorption of the support (also called cockling). However, there are problems such that it is difficult to obtain a high-quality print or that the print head easily rubs between the print head and the print surface due to cockling during printing. On the other hand, when a non-water-absorbing support is used, there is an advantage that a high-quality print can be obtained without the above-described problems.

  On the other hand, as the ink absorbing layer provided on the support, for example, an ink absorbing layer is formed by applying a hydrophilic binder such as gelatin or polyvinyl alcohol (PVA) as the ink absorbing layer on the support having high smoothness. Inkjet recording papers are known. This type of ink jet recording paper absorbs printed ink by utilizing the swelling property of the binder. However, since the binder of the ink absorbing layer is a water-soluble resin, the ink drying property after printing is difficult, and the formed image or film is weak against moisture and has poor water resistance. Furthermore, in recent ink jet printers, the printing speed is fast, so the absorbability due to the swelling of the binder cannot catch up with the ink discharge amount and discharge speed, the ink overflows, the formed image becomes mottled, and the adaptability is lost. There was a problem.

  On the other hand, Japanese Patent Application Laid-Open No. 63-18387 discloses an ink jet recording paper provided with an ink absorbing layer using a modified polyvinyl alcohol and a water-resistant agent. In addition, a recording sheet for water-based ink having an ink absorbing layer made of a hydrophilic binder cross-linked by ionizing radiation is disclosed (for example, see Patent Document 1). By using a cured binder as the ink absorbing layer, the water resistance of the image and the film has been solved, but since the ink is originally absorbed by the swelling ability of the resin, the ink absorption itself has been improved. Absent.

  In contrast to the ink jet recording paper that absorbs ink by utilizing the swelling property of the water-based resin, JP-A-10-119423 discloses a recording in which a porous layer having a minute void structure is provided as an ink absorbing layer. Paper has been proposed, and it is becoming one of the methods that have high ink absorbability and high-speed drying properties, and can obtain the image quality closest to the silver salt photograph image quality.

  This porous layer is mainly formed of a hydrophilic binder and fine particles, and inorganic or organic fine particles are widely used as the fine particles. In general, inorganic fine particles have a smaller particle size. And is preferably used because a highly glossy porous layer can be realized. Further, by using a relatively small amount of a hydrophilic binder with respect to the inorganic fine particles, voids are formed between the inorganic fine particles, and a porous layer having a high porosity can be obtained.

  Since this void portion absorbs ink by capillary action, it has an advantage that even if the binder is cross-linked with a cross-linking agent or the like to improve the water resistance, the absorption speed is not impaired. In particular, in the case of an ink jet recording paper in which such a porous ink absorbing layer is provided on a non-water-absorbing support such as a polyethylene-coated paper in which both surfaces of the paper support are coated with a polyethylene resin, , Because it is necessary to temporarily hold all ink in the ink absorbing layer, the ink absorbing layer must be a porous layer with a high void volume, thus forming a thick coating film with a high porosity. There is a need. Usually, the dry film thickness is preferably 25 to 50 μm, more preferably 30 to 50 μm.

  As described above, the porous ink absorbing layer having such characteristics is mainly composed of inorganic fine particles and is originally a hard coating film. Therefore, the thick porous layer is formed on the non-water-absorbing support. When it is applied to the film, the film strength decreases, and it is easy to induce failures such as cracks when drying.

  In the formation process of the porous ink absorbing layer, a small amount of hydrophilic binder is adsorbed on the surface of the fine particles and entangled between the hydrophilic binders, or the fine particles are retained and protected by interactions such as hydrogen bonding between the hydrophilic binders. Colloid is made to form a porous layer. Thereafter, it is considered that the coating film undergoes rapid shrinkage during the drying process, and the film surface is cracked by the shrinkage stress. In particular, the phenomenon is remarkable near the end point of drying of the film. Therefore, there has been a demand for technical development for obtaining a good coating film that does not cause cracks and the like.

  In order to solve such a problem, an inkjet recording paper having improved film water resistance using boric acid and an isocyanate-based crosslinking agent has been proposed (for example, see Patent Document 2). In addition, an inkjet recording paper using an active energy ray-curable monomer as a binder is disclosed (for example, see Patent Document 3). On the other hand, in an inkjet recording paper provided with an ink absorbing layer and a gloss developing layer in sequence, the gloss developing layer mainly contains colloidal particles and hydrophilic ionizing radiation curing containing two or more ethylenic double bonds in one molecule. A method of curing by irradiation with ionizing radiation has been proposed (for example, see Patent Document 4).

  The ink absorption layer using the hydrophilic polymer cured by such ionizing radiation can increase the strength of the coating film while maintaining high ink absorption ability. However, with an inkjet recording sheet having such an ink absorbing layer, when printing is performed using an inkjet printer, printing is performed when the sheet is cut into a sheet and fed in a stacked state. When the second inkjet recording sheet is transported to the printing position, the second inkjet recording sheet is transported at the same time, so-called misfeed, or the second inkjet recording sheet jumps backward. It turned out to be easy to wake up. In particular, in recent years, L-size or 2L-size inkjet recording sheets are actively used in home-use inkjet printers, and urgent improvement is required.

  As a cause of the above-mentioned misfeed, it is presumed that the frictional state between the front and back surfaces of the ink jet recording paper is affected. In particular, as a method of modifying the surface characteristics on the ink absorbing layer coating surface side, Examples thereof include addition of a slipperiness-imparting substance, adjustment of the surface roughness, and adjustment of the charged column using a surfactant or the like.

  Regarding the application of surfactants to ink jet recording paper, for example, it has an ink absorption layer containing inorganic fine particles dispersed with a betaine surfactant, and the ink absorption, bleeding resistance after printing and drying are improved. Inkjet recording paper is disclosed (see, for example, Patent Document 5). Further, an ink jet recording paper having an ink jet absorbing layer containing inorganic fine particles and a betaine type surfactant, particularly a betaine type fluorosurfactant, and having improved ink absorbability, bleeding resistance, crack resistance and coating failure resistance. (For example, refer to Patent Document 6). In addition, an ink jet recording sheet having an ink absorbing layer containing a water-soluble polyvalent metal salt and a cationic surfactant and improved in moisture resistance and bronzing resistance has been proposed (see, for example, Patent Document 7).

However, the binders described in Patent Documents 5 to 7 are polyvinyl alcohol and the like, and there is no mention of the use of a hydrophilic resin cross-linked by ionizing radiation. Furthermore, a hydrophilic resin cross-linked by ionizing radiation is used. There is no mention about the above-mentioned conveyance failure when used, and there is no specific suggestion about the improvement method.
JP-A-1-286886 JP 2001-146068 A Japanese Unexamined Patent Publication No. 7-40649 Japanese Patent No. 3333338 JP 2000-135854 A JP 2001-246838 A JP 2001-301318 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording paper that is excellent in transportability stability during printing and that can provide a high image density.

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

(Claim 1)
An ink jet recording sheet comprising at least one porous ink absorbing layer containing inorganic fine particles, a hydrophilic resin crosslinked by ionizing radiation, and a nonionic surfactant or a betaine surfactant on a support. .

(Claim 2)
An ink jet recording sheet comprising at least one porous ink absorbing layer containing inorganic fine particles, a hydrophilic resin cross-linked by ionizing radiation, and a fluorine-containing surfactant on a support.

(Claim 3)
The inkjet recording paper according to claim 1, wherein the betaine surfactant is a betaine fluorosurfactant.

(Claim 4)
The inkjet recording paper according to claim 2, wherein the fluorine-containing surfactant is a betaine-type fluorine surfactant.

(Claim 5)
The inkjet recording paper according to any one of claims 1 to 4, comprising a surfactant mainly composed of saponin.

  According to the present invention, it is possible to provide an ink jet recording paper that is excellent in transportability stability at the time of printing and can obtain a high image density.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventors have found that a porous material containing inorganic fine particles, a hydrophilic resin cross-linked by ionizing radiation, and a nonionic surfactant or a betaine surfactant on the support. At least a porous ink absorbing layer containing inorganic fine particles, a hydrophilic resin cross-linked by ionizing radiation, and a fluorine-containing activator on an ink jet recording paper having at least one porous ink absorbing layer or a support As a result of finding the ink jet recording paper characterized by having one layer, an ink jet recording paper having excellent ink absorbability, high image density, and improved transportability during printing can be realized. It is.

  Details of the present invention will be described below.

  The ink jet recording paper of the present invention (hereinafter also simply referred to as recording paper) has an ink absorbing layer on a support, and the ink absorbing layer contains at least inorganic fine particles and a hydrophilic resin crosslinked by ionizing radiation. Is one feature.

  First, the inorganic fine particles according to the present invention will be described.

  Examples of inorganic fine particles that can be used in the recording paper of the present invention include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, and zinc hydroxide. , Zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, silica (eg, synthetic amorphous silica, colloidal silica), alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone And white inorganic pigments such as zeolite and magnesium hydroxide.

  The inorganic fine particles according to the present invention are preferably low refractive index fine particles from the viewpoint of low cost and high reflection density, and more preferably silica or alumina.

  The silica used in the present invention is wet silica or vapor phase silica synthesized by precipitation or gel method using sodium silicate as a raw material. For example, for wet silica, a fine seal made by Tokuyama Co., Ltd. by a precipitation method is commercially available, and as a silica by a gel method, NIPGEL made by Nippon Silica Kogyo Co., Ltd. is commercially available. Precipitated silica is generally characterized as silica particles in which secondary particles are formed from primary particles of approximately 10 to 60 nm, and gel silica is approximately 3 to 10 nm.

  Although there is no restriction | limiting in particular regarding the primary particle diameter of wet silica, It is 3 nm or more from a viewpoint of the manufacture stability of a silica particle, and it is preferable that it is 50 nm or less from a viewpoint of the transparency of a film | membrane. In general, wet silica synthesized by the gel method is preferred because the primary particle size tends to be smaller than that of the precipitation method.

  Vapor phase silica is synthesized by combustion using silicon tetrachloride and hydrogen as raw materials. For example, Aerosil series manufactured by Nippon Aerosil Co., Ltd. is commercially available.

In order to obtain a porous layer having a high porosity, the specific surface area measured by the BET method is preferably less than 400 m ² / g, or the ratio of isolated silanol groups before dispersion is 0.5 to 2.0. Preferably, it is 0.5 to 1.5, more preferably 0.5 to 1.1. The lower limit of the specific surface area is preferably 40 m ² / g from the viewpoint of obtaining a gloss similar to that of a silver salt photograph. The BET method referred to in the present invention is a method for measuring the specific surface area by a method for determining the surface area per 1 g from the gas phase adsorption isotherm. Further, in the vapor-phase process silica having a specific surface area in this range, the coefficient of variation in the primary particle size distribution is preferably 0.4 or less from the viewpoint that the porosity can be increased. In wet silica, the primary particles themselves have a pore size, and this is not the case.

  On the other hand, alumina that can be preferably used for the recording paper of the present invention is aluminum oxide and hydrates thereof, which may be crystalline or amorphous, and have an amorphous, spherical, plate-like, or needle-like form. The thing which has is used. In particular, plate-like alumina hydrate and vapor phase method alumina having an aspect ratio of 2 or more and an average primary particle size of 5 to 30 nm are preferable.

  The content of the inorganic fine particles in the water-soluble coating solution is 5 to 40% by mass, and particularly preferably 7 to 30% by mass.

  The hydrophilic resin that is cross-linked by ionizing radiation used in the ink absorbing layer according to the present invention is a water-soluble resin that undergoes a reaction and cross-links by irradiation with ionizing radiation such as ultraviolet rays and electron beams. It is a resin whose water solubility is lower than before the crosslinking reaction. However, the resin preferably maintains a sufficient affinity for the ink even after crosslinking.

  As such a resin, a photo-dimerization type, photo-decomposition type, photo-depolymerization type, photo-denaturation type, photo-polymerization type or the like is allowed to act on polyvinyl alcohol or the like, and crosslinking is caused by light through the modification group. A cross-linked group-modified polymer or a polymer that is directly cross-linked by an electron beam can be used. Among them, a photodimerization type or photopolymerization type compound is preferable.

  As the photodimerization type ionizing radiation crosslinking resin, a diazo type or a compound into which a cinnamoyl group, a stilbazonium group, or a stilquinolium group is introduced is preferable.

  Specifically, a photosensitive resin having a structural unit represented by the following general formula (1) is a compound in which a stilbazonium group is introduced into the polyvinyl alcohol structure described in JP-A-60-129742. be able to.

In the general formula (1), R ₁ represents an alkyl group having 1 to 4 carbon atoms, and A ⁻ represents an anionic group.

  Examples of the photopolymerization type ionizing radiation crosslinking resin include resins having a structural unit represented by the following general formula (2) described in JP-A No. 2000-181062.

In the general formula (2), R ₂ represents a methyl group or a hydrogen atom, Y represents an aromatic ring or a simple bond, and n represents 1 or 2.

  Examples of the aromatic ring include the following.

In the formula, Z ₁ and Z ₂ each represent a methyl group, an ethyl group, or a halogen atom.

  Moreover, what is shown below is mentioned as an example of the structural unit represented by the said General formula (2).

  In the hydrophilic binder according to the present invention, the polymerization degree of PVA as a mother nucleus is preferably 500 or more, and more preferably 1700 or more.

  In the hydrophilic binder according to the present invention, the modification rate of the ionizing radiation reactive crosslinking group with respect to the segment is preferably 4 mol% or less, more preferably 0.01 to 1 mol%.

  Examples of the ionizing radiation in the present invention include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. However, they are dangerous to the human body, easy to handle, and can be used industrially. The prevalent UV light is preferred.

For example, a low pressure, medium pressure, high pressure mercury lamp, metal halide lamp, etc. having an operating pressure of several mmHg to 10 atmospheres are used as the light source. preferable. Moreover, it is preferable to provide a filter that cuts light having a wavelength of 300 nm or less. As the output of the lamp 400W～30kW, as the illuminance ^{10mW / cm 2 ~1kW / cm 2} , preferably from 0.1mJ / cm ² ~150mJ / cm ² as irradiation ^{energy, 1mJ / cm 2 ~50mJ / cm} 2 is More preferred.

When the light source wavelength includes ultraviolet rays of 300 nm or less, or when the irradiation energy exceeds 150 mJ / cm ² , there is a possibility that the core of the ionizing radiation crosslinkable resin, or various coexisting additives may be decomposed by ultraviolet rays, Not only the effect of the present invention cannot be obtained, but also problems such as odor derived from the decomposition products may occur, which is not preferable. When the irradiation energy is less than 0.1 mJ / cm ² , the crosslinking efficiency is insufficient, and the effects of the present invention cannot be obtained sufficiently.

The illuminance upon ultraviolet irradiation is preferably 0.1 mW / cm ² or more and 1 W / cm ² or less. When the illuminance exceeds 1 W / cm ² , the surface curability of the coating is improved, but the deep curability is lowered and a film having only a hard surface is obtained. In that case, the balance of the hardness in the depth direction of the film is lost, and curling or the like occurs, which is not preferable.

When the illuminance is lower than 0.1 mW / cm ^{2, the} crosslinking does not proceed sufficiently due to scattering in the film and the effect of the present invention cannot be obtained, which is not preferable.

When giving the same integrated light quantity (mJ / cm ² ), the preferable range of illuminance is due to the change in the light transmittance. When the concentration distribution of the generated cross-linking reactive species is different due to the transmittance of ultraviolet rays, and the ultraviolet illuminance is high, a high concentration of cross-linking reactive species is generated on the surface layer, and a hard and dense film is formed on the surface of the coating film.

  When the illuminance is in a preferable range, the degree of cross-linking of the surface layer is low and light permeability in the deep direction is high, so that gentle cross-linking is uniformly formed in the deep direction.

  If the illuminance is too low, it takes a long time to give the necessary integrated illuminance, which is not only disadvantageous in terms of equipment introduction, but also because the amount of absolute light due to scattering of ultraviolet rays by the coating film is insufficient. Absent.

  In the present invention, it is also preferable to add a photoinitiator or a sensitizer. These compounds may be dissolved or dispersed in a solvent, or may be chemically bonded to the photosensitive resin.

  There is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A conventionally well-known thing can be used.

  Although there is no restriction | limiting in particular about the photoinitiator and photosensitizer which are applied, A water-soluble thing is preferable from a viewpoint of mixability and reaction efficiency. For example, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK), thioxanthone ammonium salt (QTX), and benzophenone ammonium salt (ABQ) are preferable from the viewpoint of mixing with an aqueous solvent, In particular, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (HMPK) is more preferable from the viewpoints of stability and reaction efficiency. Further, as an example, benzophenones such as benzophenone, hydroxybenzophenone, bis-N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone. Thioxanthones such as thioxatone, 2,4-diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and isopropoxychlorothioxanthone. Anthraquinones such as ethyl anthraquinone, benzanthraquinone, aminoanthraquinone and chloroanthraquinone. Acetophenones. Benzoin ethers such as benzoin methyl ether. 2,4,6-trihalomethyltriazines, 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di ( m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-phenylimidazole dimer, 2- (P-methoxyphenyl) -4,5-diphenylimidazole dimer, 2, -di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5 -2,4,5-triarylimidazole dimer of diphenylimidazole dimer, benzyldimethyl ketal, 2-benzyl-2-dimethyl Amino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-hydroxy-2-methyl-1- Phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, phenanthrenequinone, 9,10-phenanthrenequinone Benzoins such as methylbenzoin and ethylbenzoin, 9-phenylacridine, acridine derivatives such as 1,7-bis (9,9′-acridinyl) heptane, bisacylphosphine oxide, and mixtures thereof are preferably used. The above may be used alone or in combination.

  In addition to these initiators, accelerators and the like can also be added. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like.

  In the present invention, a conventionally known hydrophilic resin may be used in combination with the hydrophilic resin cross-linked by the ionizing radiation according to the present invention within a range not impairing the object effect of the present invention.

  In the ink absorbing layer according to the invention, the ratio of the inorganic fine particles to the hydrophilic resin crosslinked by ionizing radiation is preferably 2 to 50 times in terms of mass ratio. If the mass ratio is 2 times or more, the ink absorption layer has a good porosity, it is easy to obtain a sufficient void volume, and the hydrophilic resin that is crosslinked by excess ionizing radiation swells during ink jet recording to close the voids. You can avoid that. On the other hand, if this ratio is 50 times or less, it is preferable that cracks are not likely to occur when the ink absorbing layer is applied as a thick film. The ratio of the silica fine particles to the hydrophilic resin that is crosslinked by ionizing radiation is particularly preferably 2.5 to 20 times. Moreover, 5 to 15 times is preferable from a viewpoint of the fracture resistance of a dry coating film.

The void of the porous ink absorbing layer according to the present invention preferably has a capacity of 15 to 40 ml / m ² per unit area of the coating film. The term “capacity” as used herein refers to the volume of bubbles generated when a unit volume of the coating film is applied to water, the volume of water that can be absorbed by the coating film, or the recording paper finally obtained. It is defined as the amount of liquid transfer when the contact time is 2 seconds as measured by the liquid absorbency test method (Bristow method) for paper and paperboard specified in TAPPI 51.

  In the recording paper of the present invention, the ink absorbing layer having the above-described configuration contains a nonionic surfactant or a betaine surfactant.

  The nonionic surfactant applicable to the present invention is not particularly limited, and various compounds can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene aryl ether, ester polyoxyethylene alkyl phenyl ether Polyoxyethylene naphthyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, pentaerythritol fatty acid partial ester, propylene glycol mono fatty acid Esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene Recall fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene-polyoxypropylene blocks of ethylenediamine Copolymer adducts, fatty acid diethanolamides, N, N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides and the like can be mentioned. Nonionic surfactants having a repeating structure having 3 or more oxyethylene units are preferred. For example, as polyoxyethylene lauryl ether in the Emulgen series manufactured by Kao Corporation, as Emulgen 103, Emulgen 104P, Emulgen 105, Emulgen 106, Emulgen 108, Emulgen 109P, Emulgen 120, Emulgen 123P, Polyoxyethylene stearyl ether Emulgen 306P and polyoxyethylene oleyl ether include Emulgen 404, Emulgen 409P, Emulgen 420, Emulgen 430 and the like, but the present invention is not limited thereto.

  In addition, the betaine surfactant applicable to the present invention is not particularly limited, and various compounds can be used. For example, carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, imidazolines And the like. Moreover, it can obtain easily also as a commercial item, for example, the Levon LD-36 by Sanyo Kasei Co., Ltd. etc. can be mentioned as a hydrocarbon-type alkylbetaine type surfactant.

  In the ink jet recording paper of the present invention, at least one of the porous ink absorbing layers is characterized by containing a fluorine-containing surfactant.

  The fluorine-containing surfactant according to the present invention may be any of anionic, cationic, nonionic, and betaine types, and may be a low molecule or a polymer. For example, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkenyl sulfonate, perfluoroalkenyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkenyl polyoxyethylene ether, perfluoroalkyl fourth Examples include quaternary ammonium salts, perfluoroalkenyl quaternary ammonium salts, perfluoroalkylaminosulfonates, perfluoroalkenyl betaines, perfluoroalkyl group-containing oligomers, perfluoroalkyl phosphate esters, etc., selected as appropriate or mixed Can be used.

  In the present invention, among the above-mentioned fluorine-containing surfactants, it is preferable to use a cationic fluorine-based surfactant, a nonionic fluorine-based surfactant, or a betaine-type fluorine-based surfactant. It is preferable to use a system surfactant.

  As the cationic fluorosurfactant used in the present invention, a compound represented by the following general formula [FK] is preferably used.

Formula [FK]
Rf'-G-J ⁺ L ^-
In the general formula [FK], Rf ′ is a hydrocarbon group having 1 to 20 carbon atoms, and at least one hydrogen atom is substituted with a fluorine atom. G represents a chemical bond or a divalent linking group. J ⁺ represents a cationic group, and L ⁻ represents a counter anion.

Examples of _{Rf ', -C k F 2k +} 1 (k = 1~20, in particular _{3~12), - C q HF 2q} , -C q F 2q + 1 (q = 2~20, especially 3 12) can be cited, as examples of G _{is, -SO 2 N (R 1)} (CH 2) p -, - CON (R 1) (CH 2) p -, - OASO 2 N (R 1) _{(CH 2) p -, -} OACON (R 1) (CH 2) p -, - OAO (CH 2) p -, - OA (CH 2) p -, - O (CH 2 CH 2 O) q (CH _{2) p -, - O (} CH 2) p -, - N (R 1) (CH 2) p -, - SO 2 N (R 1) (CH 2) p O (CH 2) r -, - CON _{(R 1) (CH 2)} p O (CH 2) r -, - OASO 2 N (R 1) (CHR 1) p OA -, - (CH 2) p (CHOH) s (CH 2) r - , etc. Can be mentioned. Here, R ₁ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms (which may have a substituent), A represents an alkylene group or an arylene group, and p, r and s each represents 0 to 6 , Q is an integer of 1-20.

Examples of J ⁺ include -N ⁺ (R ₁ ) ₃ , -N ⁺ (CH ₂ CH ₂ OCH ₃ ) ₃ , -N ⁺ C ₄ H ₈ O (R ₁ ), -N ⁺ (R ₁ ) ( _{R 2) (CH 2 CH 2} OCH 3), - N + C 5 H 5, -N + (R 1) (R 2) (CH 2) p C 6 H 5, -N + (R 1) (R ₂ ) (R ₂ ) and the like. Here, R ₂ has the same meaning as R ₁ described above.

Furthermore, examples of L ⁻ include I ⁻ , Cl ⁻ , Br ⁻ , CH ₃ SO ₃ ⁻ , CH ₃ —C ₆ H ₄ —SO ₃ ^{—, and the} like.

  Specific examples of the cationic fluorosurfactant preferably used in the present invention are listed below, but are not limited thereto.

  As a nonionic fluorine-type nonionic surfactant used for this invention, the compound represented by the following general formula [FN] is preferable.

General formula [FN]
_{Rf- (G 1) n1 - (} E) m H
In the formula, Rf represents an alkyl group or an aryl group having 3 to 20 carbon atoms and substituted with at least one fluorine atom, G ₁ represents a divalent linking group, E represents an ethylene oxide group, and n1 represents 1 or 2 is represented, and m represents an integer of 1 to 20.

  Specific examples of nonionic fluorosurfactants that can be preferably used in the present invention will be given below, but the present invention is not limited to these.

  In the present invention, the betaine type fluorosurfactants particularly preferably used include a carboxybetaine type and a sulfobetaine type, and a carboxybetaine type fluorosurfactant is preferable.

  Specific examples of the betaine type fluorosurfactant preferably used in the present invention are shown below, but the present invention is not limited to these.

  In the ink jet recording paper of the present invention, the fluorine-containing surfactant preferably has a carbon-carbon unsaturated bond in the molecule.

  In the present invention, the structure is not particularly limited as long as it is a fluorine-containing surfactant having a carbon-carbon unsaturated bond in the hydrophobic portion, and any compound may be used, but an ionic group ( For example, those having a cation, an anion, or a betaine group are preferable, and those having a betaine group are more preferable. The total number of carbon atoms is preferably 10 or more, more preferably 15 or more, and particularly preferably 20 or more. In the surfactant according to the present invention, the unsaturated bond is not an aromatic ring.

  Specific examples of the surfactant having a carbon-carbon unsaturated bond in the molecule according to the present invention are shown below, but the present invention is not limited thereto.

  Each fluorine-containing surfactant according to the present invention forms a porous ink absorption layer that is farthest from the support when a plurality of porous ink absorption layer forming coating liquids are applied on the support. It is preferably added to the coating solution to be used, and the amount used thereof can be used in the range of 0.005 to 50 g, preferably 0.05 to 5 g, per 1 kg of the coating solution.

  In the present invention, known surfactants other than fluorine-containing surfactants can be used together with the above-mentioned fluorine-containing surfactants. For example, hydrocarbon nonionic surfactants, sugar esters such as saponins, etc. It is preferable to use in combination, and particularly when a surfactant mainly composed of saponin is used in combination, it is preferable in that the effect of the present invention is further exhibited. In general, saponin is a natural product and is often provided in a state where a plurality of compounds are mixed. The term “based on saponin” as used in the present invention means a surfactant containing 50% or more of a saponin component. Means.

  The saponins used in the present invention are steroidal or triterpene glycosides distributed in the plant kingdom, and are known compounds that have been known as coating aids or wetting agents for a long time in the photographic industry. The types of saponins used in the present invention can be used without any particular limitation, and preferably include quillaja saponins extracted from the quilla bark, muclodi saponins extracted from the skins of disease-free children (Murukuji), and the like. It can be easily obtained as a commercial product.

  In the ink jet recording paper of the present invention, in addition to the above-described configuration, various additives can be added within a range that does not impair the object effects of the present invention. Examples of such additives include a cationic mordant, a crosslinking agent, a white color tone adjusting agent, a fluorescent whitening agent, an antifungal agent, a viscosity adjusting agent, a low boiling point organic, a high boiling point organic, a latex emulsion, an anti-fading agent, Examples include ultraviolet absorbers, polyvalent metal compounds (water-soluble or water-insoluble), photopolymerization initiators, photosensitizers, polymerization accelerators, matting agents, and silicone oil.

  As the cationic mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium base is used, but there is little discoloration or deterioration of light resistance during long-term storage, and mordanting ability of the colorant. Is sufficiently high, a polymer mordant having a quaternary ammonium base is preferred.

  A preferred polymer mordant is obtained as a homopolymer of a monomer having the quaternary ammonium base, a copolymer with another monomer, or a condensation polymer.

As the polyvalent metal compound, for example, sulfates such as Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Zr ²⁺ , Ni ²⁺ , Al ³⁺ , chlorides, nitrates, acetates, etc. are preferably used. . In addition, inorganic polymer compounds such as basic polyaluminum hydroxide and zirconyl acetate are also included as examples of preferable water-soluble polyvalent metal compounds. In general, many of these water-soluble compounds have functions of improving light resistance and improving bleeding resistance and water resistance.

  As the support used for the recording paper of the present invention, an ink water-absorbing support (for example, paper) or an ink non-water-absorbing support can be used. From the viewpoint of obtaining a higher-quality print, the ink non-water-absorbing support can be used. A support is preferred.

  Examples of the ink non-water-absorbing support that are preferably used include, for example, polyester films, diacetate films, triatesate films, polyolefin films, acrylic films, polycarbonate films, polyvinyl chloride films, polyimide films, cellophane, Examples thereof include a transparent or opaque film made of a material such as celluloid, or a resin-coated paper in which both surfaces of a base paper are coated with a polyolefin resin or the like, so-called RC paper.

  When the ink absorbing layer according to the present invention is applied on the support, the surface of the support is subjected to corona discharge treatment or subbing for the purpose of increasing the adhesive strength between the support surface and the coating layer. It is preferable to perform processing or the like. Further, the recording paper of the present invention may be a colored support.

  The support preferably used in the present invention is a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support in which both sides of paper are laminated with a polyolefin resin.

  Hereinafter, an ink non-water-absorbing paper support laminated with polyethylene, which is the most preferred polyolefin resin, will be described.

  The base paper used for the paper support is made from wood pulp as a main raw material, and if necessary, synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester is added to the wood pulp.

The basis weight of the base paper is preferably 30 to 250 g, particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by subjecting it to a calendar process at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / cm ³ (according to the method defined in JIS-P-8118).

  Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS-P-8143. A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agents that can be added to the base paper can be used. The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS-P-8113.

  The polyethylene that covers the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) or high-density polyethylene (HDPE), but other LLDPE, polypropylene, and the like can also be used in part.

  In addition, the polyethylene layer on the side where the ink absorbing layer is applied is an improved opacity and whiteness by adding rutile or anatase-type titanium oxide into polyethylene as is widely done in photographic paper. Is preferred. 1-20 mass% is preferable with respect to polyethylene, and, as for titanium oxide content, 2-15 mass% is more preferable.

  Polyethylene-coated paper can be used as glossy paper. Also, when polyethylene is melt-extruded onto the surface of the base paper and coated, so-called typing treatment is used to produce matte surfaces, silks, etc. What formed the fine surface can also be used by this invention.

  The film thickness of the polyethylene on the front and back of the base paper is preferably 20 to 40 μm on the surface on which the ink absorbing layer is applied, and 10 to 30 μm on the surface on which the back layer is applied.

  Furthermore, the polyethylene-coated paper support preferably has the following characteristics.

1) Tensile strength: strength specified by JIS-P-8113, preferably 20-300N in the vertical direction and 10-200N in the horizontal direction 2) Tear strength: as defined by JIS-P-8116 The longitudinal direction is preferably 0.1 to 2N and the lateral direction is preferably 0.2 to 2N. 3) Compression elastic modulus: ≧ 1030 N / cm ²
4) Surface Beck smoothness: 500 seconds or more is preferable as a glossy surface under the conditions specified in JIS-P-8119, but it may be less than this for so-called molded products. 5) Back surface Beck smoothness: JIS- 100 to 800 seconds are preferable under the conditions specified in P-8119. 6) Opacity: Under the measurement conditions of linear light incidence / diffuse light transmission conditions, the transmittance for light in the visible range is 20% or less, particularly 15%. 7) Whiteness: Hunter whiteness as defined in JIS-P-8123, preferably 90% or more. Further, when measured by JIS-Z-8722 (non-fluorescent) and JIS-Z-8717 (containing fluorescent agent) and displayed by the color display method defined in JIS-Z-8730, L ^* = 90 to 98, a ^* = − 5 to +5, b ^* = − 10 to +5 are preferable.

An undercoat layer can be provided on the surface of the support on which the ink absorbing layer is applied for the purpose of improving the adhesion to the ink absorbing layer. The binder for the undercoat layer is preferably a hydrophilic polymer such as gelatin or polyvinyl alcohol, or a latex polymer having a Tg of −30 to 60 ° C. The coating amount of these binders is preferably 0.001 to ² g per 1 m ^{2 of} recording paper. In the undercoat layer, a small amount of a conventionally known antistatic agent such as a cationic polymer can be contained for the purpose of antistatic.

  A back layer is preferably provided on the surface of the support opposite to the surface on which the ink absorbing layer is applied for the purpose of improving slipperiness and charging characteristics. The binder for the back layer is preferably a hydrophilic polymer such as gelatin or polyvinyl alcohol, a latex polymer having a Tg of −30 to 60 ° C., an antistatic agent such as a cationic polymer, various surfactants, A matting agent having an average particle diameter of about 0.5 to 20 μm can also be added. The thickness of the back layer is preferably 0.1 to 1 μm, but when the back layer is provided to prevent curling, it is preferably 1 to 20 μm, although it depends on the thickness of the ink absorbing layer. Further, the back layer may be composed of two or more layers.

  In the production of the recording paper of the present invention, the coating method for coating the ink absorbing layer on the support is not particularly limited, and can be appropriately selected from known methods, for example, gravure coating method, roll coating The rod bar coating method, the air knife coating method, the spray coating method, the extrusion coating method, the curtain coating method, or the extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used. .

  The ink absorption layer may be a single layer or may be composed of two or more layers. When the ink absorption layer is composed of two or more layers, their configurations may be the same or different from each other. Moreover, when comprising by two or more layers, the method of apply | coating all the structural layers simultaneously is preferable from a viewpoint of productivity.

  When recording (printing) an image using the recording paper of the present invention, it is preferable to use an inkjet ink.

  The inkjet ink is a water-based ink having a colorant, a liquid medium, and other additives. The ink is preferably one that is not absorbed by the support used in the present invention.

  As the colorant, water-soluble dyes or water-dispersible pigments such as direct dyes, acid dyes, basic dyes, reactive dyes or food dyes known in ink jet can be used. The use of is particularly preferred from the viewpoint of improving the color developability when the configuration according to the present invention is adopted.

  The liquid medium is preferably composed mainly of water and various water-soluble organic solvents. The organic solvent is not particularly limited as long as it is not absorbed by the support used in the present invention. For example, alcohols such as methyl alcohol, isopropyl alcohol, butyl alcohol, tert-butyl alcohol, isobutyl alcohol; dimethylformamide Amides such as dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, Triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, glycerin, tri Polyhydric alcohols such as tanolamine; lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monobutyl ether, etc. Polyhydric alcohols such as ethanolamine and glycerin, lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether are preferably used.

  Examples of the other additives include pH adjusters, metal sequestering agents, antifungal agents, viscosity modifiers, surface tension adjusters, wetting agents, surfactants, and rust preventive agents. And preferably used.

  As the water-based ink, in order to improve the wettability with respect to the ink absorbing layer, the surface tension at 20 ° C. is preferably 0.025 to 0.06 N / m, and more preferably 0.03 to 0.05 N / m. Moreover, what adjusted the pH of the said water-based ink to 5-10 is preferable, and what is 6-9 is more preferable.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Preparation of inorganic fine particle dispersion >>
Silica dispersion B (pH 2.6, ethanol 0.6%) containing 30% of vapor phase silica (Nippon Aerosil Co., Ltd .; Aerosil 300) having an average primary particle size of about 0.007 μm, which is uniformly dispersed in advance. 5%) and aqueous solution C (pH 2.5, San Nopco antifoam SN-381) containing 1200 g of cationic polymer dispersant P-1 and 10% n-propanol and 2% ethanol. Was added with stirring at 3000 rpm at room temperature.

Subsequently, it disperse | distributed with the pressure of ³ kN / cm < ² > with the high pressure homogenizer by the Sanwa Kogyo Co., Ltd., the whole quantity was finished with the pure water, and the substantially transparent silica dispersion liquid with a silica content of 25% was obtained.

<Preparation of recording paper 101>
UV-crosslinked polyvinyl alcohol derivative aqueous solution (compound-1) represented by the general formula (1) prepared with reference to Example of JP 2000-181062 A adjusted to 10% in 3000 g of the obtained silica dispersion. : 960 g of main chain PVA polymerization degree 3000, saponification degree 88%, crosslinkable group modification rate 1 mol%) and 1.5 g of photoinitiator (Nippon Kayaku Kayacure QTX) were gradually added with stirring, pure water The ink absorbing layer coating solution 1 was prepared.

  The obtained ink absorbing layer coating liquid 1 was filtered using a TCP-10 type filter manufactured by Advantex Toyo.

Next, the ink-absorbing layer coating liquid 1 prepared above was coated with polyethylene on both sides of a base paper having a thickness of 170 g / m ² (containing 8% by mass of anatase-type titanium oxide in the polyethylene on the ink-absorbing layer side). and also it has a gelatin subbing layer of 0.05 g / m ² in the ink absorbing layer side, a back layer on the other side a Tg of a 0.2 g / m ² containing latex polymer of from about 80 ° C.) In addition, it was applied using a curtain coater so that the amount of silica applied was 26 g / m ^2, and then a metal halide lamp having a dominant wavelength at 365 nm was used with ultraviolet light having an illuminance at a wavelength of 365 nm of 60 mW / cm ^2. An amount of 30 mJ / cm ² of ultraviolet rays was irradiated. Thereafter, the ink jet recording paper 101 was obtained by drying with hot air at 80 ° C.

<< Preparation of recording sheets 102-109 >>
In the production of the recording paper 101, recording papers 102 to 108 were produced in the same manner except that the surfactants shown in Table 1 were added to the ink absorbing layer coating liquid 1 in the amounts shown in Table 1. The amount of each surfactant added was indicated as the amount added per 1 m ^{2 of} recording paper.

  Next, the prepared recording papers 101 to 109 were cut into an L size by an automatic cutting machine, and stored in a 40 ° C. environment for 3 days in a state where 100 sheets were stacked, and stabilized.

  The details of the surfactants listed in Table 1 used for the production of the recording papers 102 to 109 are as follows.

Emulgen 109: Nonionic surfactant, manufactured by Kao Corp. Levon LD-36: Betaine surfactant, Sanyo Kasei Co., Ltd. Megafax F-144D: Nonionic fluorosurfactant, manufactured by Dainippon Ink & Chemicals, Inc. F-150: Cationic fluorosurfactant, manufactured by Dainippon Ink & Chemicals, Inc. Footent 400S: Betaine fluorosurfactant, manufactured by Neos << Evaluation of characteristics of recording paper >>
With respect to the L-size recording sheets 101 to 109 produced as described above, the following overlap conveyance property was evaluated.

(Evaluation of stacking transportability)
Twenty sheets of recording paper are left in an environment of 30 ° C. and 80% RH for 5 hours in a stacked state, and then, one of the short sides of the recording paper is lightly sprinkled, A total number of ink jet printers PM-950C manufactured by Seiko Epson Corporation was set with the paper support removed. Subsequently, 20 continuous prints were performed so that a 7 cm × 10 cm rectangular gray solid image having a reflection density of about 1.0 was printed at the center of the recording paper. The printer driver settings at this time were “PM photo paper” as the paper type and “recommended setting / clean” as the mode.

<Measurement of number of unprintable sheets>
At the time of continuous printing by the above operation, the number of sheets that could not be printed due to two sheets of recording paper being conveyed in a stacked manner or the paper jumping out backward due to the reaction of the paper feeding operation was counted.

<Evaluation of straight conveyance performance>
After measuring the distance (mm) from the nearest long side for each of the four vertices of the rectangular gray solid image created as described above, the difference (Δmm) between the maximum distance and the minimum distance is calculated, and the average A value (Dev) was obtained and used as a measure of the straightness of conveyance of the recording paper.

  In the above evaluation, the smaller the number of sheets that could not be printed and the smaller the Dev value, the higher the stability in the overlap conveyance.

  The results obtained as described above are shown in Table 1.

  As is clear from the results shown in Table 1, the recording paper containing the surfactant according to the present invention has a smaller number of unprintable sheets, a higher straightness of conveyance, and stability of overlap conveyance compared to the comparative example. I understand that it is expensive.

Example 2
<Characteristic evaluation of recording paper>
For the recording papers 101 to 109 prepared in Example 1, the same method as in Example 1 was applied except that the ink jet printer was changed to an ink jet printer PM-4000PX using pigment ink manufactured by Seiko Epson Corporation. Then, the evaluation of the stacking conveyance property and the coloring property were performed according to the following methods.

(Color development evaluation)
Image data ((R, G, B) = (122, 122, 122)) with Photoshop 7.0 (manufactured by Adobe) so that the gray patch is reproduced at 2.54 cm (1 inch) square on the print. A print was created with the printer driver settings set to "PM photo paper" and the mode set to "recommended setting / clean".

  The gray patch of the obtained print was measured with an X-rite 810 densitometer (manufactured by X-Rite) to determine the status A reflection density. Next, an average value of the obtained blue reflection density, green reflection density, and red reflection density was calculated, and this value was used as an index of color development. Higher values indicate better color developability.

  The results obtained as described above are shown in Table 2.

  As is clear from the results shown in Table 2, it can be seen that the recording paper of the present invention has a smaller number of unprintable sheets, higher straightness of transport, and higher overlap transport stability than the comparative example. In addition, it can be seen that the recording paper 109 using saponin is a particularly preferable embodiment because of excellent color developability when a pigment type ink jet printer is used.

Claims (5)

An ink jet recording sheet comprising at least one porous ink absorbing layer containing inorganic fine particles, a hydrophilic resin crosslinked by ionizing radiation, and a nonionic surfactant or a betaine surfactant on a support. . An ink jet recording sheet comprising at least one porous ink absorbing layer containing inorganic fine particles, a hydrophilic resin cross-linked by ionizing radiation, and a fluorine-containing surfactant on a support. The inkjet recording paper according to claim 1, wherein the betaine surfactant is a betaine fluorosurfactant. The inkjet recording paper according to claim 2, wherein the fluorine-containing surfactant is a betaine-type fluorine surfactant. The inkjet recording paper according to any one of claims 1 to 4, comprising a surfactant mainly composed of saponin.