JP2000263925A - Inkjet recording paper - Google Patents

Abstract

(57) [Object] To provide an ink jet recording paper excellent in transportability by avoiding a waving phenomenon (cockling) and ink strike-through generated on the surface of a printing part by printing. Kind Code: A1 Abstract: An ink jet recording sheet comprising at least one ink receiving layer coated on a base paper. At least one or more support layers are provided on the opposite side of the ink receiving layer surface via the base paper, and at least one of the support layers is composed of a composition mainly composed of a non-aqueous resin and a white pigment, By setting the surface of the support layer to a specific glossiness, a target ink jet recording paper can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording paper for recording using ink, and more particularly to an ink-jet recording paper in which a printing surface, which is generated after ink-jet recording is wavy, is called cockling and ink strike-through is avoided. It relates to recording paper.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which fine droplets of ink are made to fly and adhere to recording paper such as paper by various operating principles to record images and characters. It has features such as easy multi-coloring, great flexibility in recording patterns, and no need for development-fixing. It has rapidly spread in various uses as a recording device for various figures and color images including Chinese characters. I have. Further, an image formed by the multi-color ink jet system can obtain a record comparable to multi-color printing by a plate making system or printing by a color photographic system. In addition, in applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is less expensive than the photographic technique.

In addition, the cost of the ink jet recording apparatus has been reduced,
Because it is possible to easily obtain an image with excellent image reproducibility and color reproducibility such as sharpness and color at the level of a personal computer, an ink jet recording device can be used from a special recording device used for a specific person to a general-purpose one. In recent years, the recording apparatus has been changed, and in recent years, in particular, the ink jet recording apparatus has been further improved in definition, and the ratio of possession by an individual has been greatly increased due to the appearance of an ink jet recording apparatus that claims photographic quality at a low price. I have.

[0004] Further, with diversification of uses, they are increasingly used for large-sized posters, POP arts, and drafting applications. In these applications, the high sharpness of the ink jet can be utilized and excellent color can be obtained, so that a good image can be obtained, and the advertising effect is large. Application to these is because it is possible to easily obtain an image excellent in image reproducibility and color reproducibility such as sharpness and color at the level of a personal computer, which is a reason why ink jet recording paper is frequently used. .

[0005] Due to the high performance and diversification of applications of these ink jet recording apparatuses, the characteristics and requirements required for the ink jet recording paper have become quite high. In particular, in a recording apparatus that claims high definition of an image or a recording apparatus capable of large-format printing, the amount of ink used to form an image is considerably increased compared to the conventional one, and an ink receiving layer for absorbing the ink is used. Is improving. However, it is difficult to obtain a satisfactory image quality for a recording apparatus having a large amount of ink only by supporting the ink receiving layer as described below.
It is preferable to select a base paper that can also be a layer that absorbs ink. The fact that the base paper absorbs the ink is accompanied by the occurrence of a phenomenon called cockling in which the base paper expands and contracts with respect to the printed ink, the recording paper is distorted, and the surface of the printing portion is wavy.

[0006] With the increase in the amount of ink used for image formation accompanying the improvement in the performance of an ink jet recording apparatus, the ink cannot be absorbed only by the ink receiving layer, and the role of absorbing the ink even to the base paper has come to be taken. I have. As a result, a phenomenon of ink strikethrough occurs. In this phenomenon, the printed ink reaches the vicinity of the back surface of the recording paper, and the printed image is visually recognized from the back surface. In severe cases, the ink completely escapes to the back surface. Due to this phenomenon, even if the image quality is high-quality, the appearance texture is remarkably impaired, which is a major problem, and it is demanded to improve all of the ink absorbency, cockling, and ink strike-through. .

[0007] Further, diversification of uses has also occurred with respect to the appearance of ink jet recording paper, and in addition to the conventional matte or matte paper having a dull or low appearance, art paper, coated paper, cast paper, There is a demand for glossy appearance of photographic paper and the like. This is because ink jet recording can reproduce image quality comparable to printing or photography, and there is a demand for a similar appearance.

[0010] In particular, cockling, which is an object of the present invention, is a wavy pattern generated on the surface of a printing portion of an ink jet recording paper. In the glossy recording paper, reflected light is scattered. Cockling is more noticeable than matte paper, and avoiding this is an important issue. In addition, strikethrough of ink is a phenomenon that is not observed in printing paper or photographic paper, and is a problem to be avoided in order to meet a demand for similar appearance.

As a means for avoiding these phenomena, a method of making the base paper sufficiently thick or a method of providing a back coat layer on the side opposite to the ink receiving layer via the base paper to suppress strike-through of ink and expansion and contraction of the base paper are generally used. (Japanese Patent Laid-Open No. 04
-298390). However, although these methods are effective for strike-through of ink, it is difficult to completely avoid cockling in a printing apparatus in which the amount of ink ejected recently has increased. Further, in order to increase the thickness of the base paper and to cope with the rigidity of the base paper, a considerable thickness is required, which greatly exceeds the range of 70 to 250 μm, which is the thickness of the recording paper normally used. As a result, the rigidity of the base paper is increased, the flexibility of the recording paper is lacking, and the base paper is thick, so that the transportability in the ink jet recording apparatus is reduced.

In addition, there is a method of increasing the absorption capacity of the ink receiving layer so that the ink does not reach the base paper. However, in order to increase the absorption capacity of the ink receiving layer, it is necessary to reduce the binder component in the ink receiving layer or increase the coating amount of the ink receiving layer. However, it is difficult to say that this method is a good means because the adhesive strength of the toner and the reproducibility of the image due to the thinning of the dots forming the image occur.

Further, there is a method of providing a barrier layer between the base paper and the ink receiving layer so that the printed ink does not penetrate into the base paper, and a method of providing water resistance so that the base paper does not expand and contract even if the ink penetrates. Conceivable. However, with these methods, the ink absorption capacity of the recording paper is reduced, and ink overflow or bleeding occurs, making it difficult to obtain a good image.

[0012]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide an ink jet recording medium having a printing portion having a wavy surface caused by distortion of the ink jet recording paper due to expansion and contraction of the base paper when the ink is injected into the recording paper. An object of the present invention is to provide an ink jet recording sheet having good transportability by avoiding a phenomenon called cockling and strike-through of ink.

[0013]

According to the ink jet recording paper of the present invention, at least one or more ink-receiving layers are provided on a base paper and at least one or more support layers are provided on the opposite side of the ink-receiving layer via the base paper. In the ink jet recording paper provided, at least one of the support layers is composed of a composition containing a non-aqueous resin and a white pigment as main components, and the ink jet recording medium having the above-mentioned disadvantages improved. It has been found that recording paper can be obtained.

In the ink jet recording paper of the present invention, the opacity specified in JIS P8138 is 85%.
It is preferable that it is above.

In the ink jet recording paper of the present invention, the main component of the white pigment is preferably at least one selected from titanium dioxide, zinc oxide and barium sulfate.

In the ink jet recording paper of the present invention, the outermost surface of the support layer is preferably not more than 70% in terms of a 75 degree specular glossiness specified in JIS P8142.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet recording paper of the present invention will be described below in detail.

The present inventors have found that a large amount of ink is ejected onto the recording paper by printing, so that the base paper provided with the ink receiving layer expands and contracts, causing distortion not only in the base paper but also in the ink receiving layer. It was thought that cockling would occur due to this, and intensive research was conducted on a method for suppressing distortion of the recording paper due to expansion and contraction of the base paper. Further, regarding the strike-through of the ink, a study was made on a method of avoiding strike-through of the ink without affecting the ink absorbency of the recording paper.
As a result, a support layer is provided on the surface opposite to the ink receiving layer via the base paper, and at least one of the support layers is provided with a composition containing a non-aqueous resin and a white pigment as a main component. It has been found that the distortion of the recording paper can be suppressed without any influence, the cockling can be improved, and strike-through of the ink can be avoided.

The improvement of cockling is achieved by the fact that at least one layer of the support layer composed of a non-aqueous resin and a white pigment suppresses expansion and contraction of the base paper, and that the support layer does not expand and contract with ink. Is shown, and avoidance of strike-through of the ink, the white pigment contained in the support layer,
Indicated by increasing the opacity of the layer and blocking ink that escapes to the back of the base paper. It is considered that the influence on the ink jet recording characteristics is because the support layer does not penetrate into the base paper and thus does not affect the characteristics of the base paper treated as the ink absorbing layer.

In a layer other than the support layer composed of a non-aqueous resin and a white pigment, for example, in a conventional back coat layer using an aqueous coating liquid containing a pigment and a binder as main components, a recent recording apparatus having a large ink discharge amount is not used. Cockling cannot be completely avoided. This is thought to be due to the fact that the backcoat layer itself does not have the rigidity to prevent the expansion and contraction of the base paper, and is deformed by the ink penetrating through the base paper because the backcoat layer itself has absorbency. Did not prevent cockling. In addition, when the support layer is set up, the water-based coating liquid of the layer penetrates into the base paper, which may impair the ink absorbency.

As a method of preventing strike-through of the ink, a method of providing a back coat layer using an aqueous coating solution containing a pigment and a binder as main components as described above can be considered. However, also in this case, since the back coat layer itself has absorptivity, it is not possible to completely avoid strike-through of the ink, and the ink penetrates the back coat layer, and spot-like strike-through occurs partially. In some cases. However, a method is conceivable in which after a support layer made of a non-aqueous resin is applied, a water-based coating liquid mainly containing a pigment and a binder is applied on the support layer.

The strike-through of ink is avoided by increasing the opacity of the support layer, thereby increasing the opacity of the ink jet recording paper, and blocking the ink that has escaped to the back of the recording paper. The present inventors studied the opacity of the ink jet recording paper and the effect of blocking the ink strike-through. As a result, it was found that if the opacity specified in JIS P8138 is 85% or more, a sufficient effect of blocking the strike-through of the ink can be obtained.

In the present invention, the main component of the white pigment is preferably at least one selected from titanium dioxide, zinc oxide and barium sulfate. This is because the refractive index of the pigment is higher than other pigments, which is very effective in increasing the opacity when applied to the support layer,
It has been found that the use of the pigment further enhances the effect of blocking the strike-through of the ink, as compared with the case where a pigment other than those described above is used.

Further, it is important to ensure the transportability of the ink jet recording paper by increasing the speed of the ink jet recording. As shown in the present invention, when the outermost surface on the support layer side is 70% or less in terms of 75 degree specular glossiness specified in JIS P8142, good transportability can be obtained. Generally, in an ink jet recording apparatus, the recording sheets are bundled and set, and recording is performed sequentially. For this reason, the slipperiness when the front and back surfaces of the recording paper are brought together greatly affects the transportability. In the present invention, it has been found that by concluding the outermost surface on the support layer side with the above-mentioned specific glossiness irrespective of the surface state of the ink receiving layer surface, that is, the matte surface or the glossy surface, it is effective in improving the transportability. did.

The support layer in the present invention means at least one or more layers provided on the opposite side of the ink receiving layer via the base paper. In particular, it is necessary that at least one of the support layers is composed of a composition mainly composed of a non-aqueous resin and a white pigment.

The non-aqueous resin applied to the support layer is a resin other than a water-soluble resin or a water-dispersed resin, and is preferably a thermoplastic resin. For example, the following substances may be mentioned. High density polyethylene, low density polyethylene,
Polyethylene such as medium-density polyethylene and linear low-density polyethylene, isotactic and syndiotactic
Atactic or a mixture thereof, polypropylene, polypropylene such as random copolymer or block copolymer with ethylene, other poly-3-methylpentene-1, polyethylene glycol terephthalate, polyvinyl chloride, polyvinylidene chloride, ethylene- A vinyl alcohol copolymer, polyisobutylene, ethylene vinyl acetate copolymer or the like can be used alone or in combination.

The white pigment to be added to the non-aqueous resin is not particularly limited.
Inorganic pigments such as carbonates, oxides, hydroxides, sulfates, etc. of zinc, magnesium, barium, titanium, etc., and inorganic pigments including clays such as natural silica, synthetic silica, clay, zeolite, kaolin, calcined kaolin, etc., starch , A styrene resin, a melamine resin, an acrylic resin, an organic pigment containing a copolymer such as a urea resin, or one or more of them. Among them, as described above, by using at least one selected from titanium dioxide, zinc oxide, and barium sulfate,
Good opacity can be obtained. These white pigments vary depending on their properties, but are 5 to 5% based on the resin.
0% used.

The support layer comprising a composition containing a non-aqueous resin and a white pigment as main components can be provided using a laminator such as a general melt extrusion die, a T die, a multilayer simultaneous extrusion die, or a hot melt coater. . Since the amount of the support layer varies depending on the substance to be applied, it is preferably defined by the thickness, and if it is 10 μm or more, the support layer becomes a uniform and defect-free surface. In particular, since the polyolefin resin is melted, extruded by a laminator, and then cooled and set, the resin does not penetrate into the base paper or the ink receiving layer, so that it has little influence on the suitability for ink jet recording and is preferable. The upper limit of the amount of the support layer is determined by the transportability of the ink jet recording paper in each printer.
m.

The transportability in the ink jet recording apparatus is as follows.
It is necessary to control the glossiness of the outermost surface on the support layer side within a specific range, and the glossiness can be adjusted by the following method. For example, by adjusting the amount of white pigment added to a composition containing a non-aqueous resin and a white pigment as a main component, the outermost surface is formed by bonding or bonding a base paper or a matted film, and the non-aqueous resin and After providing a composition containing a white pigment as a main component, a back coat layer containing a pigment and a binder as a main component is applied, and when laminating a non-aqueous resin, the surface of a cooling roll is roughened. Thus, the glossiness of the support layer can be changed. In this way, the glossiness of the support layer is reduced to 70
% Or less, good transportability can be obtained regardless of the surface state of the ink receiving layer.

The ink receiving layer referred to in the present invention refers to properties such as absorbency, image reproducibility and color saturation of dye inks and pigment inks used in commercially available ink jet printers, ink jet plotters and ink jet proofers. And a composition mainly composed of a pigment and a binder provided for the purpose corresponding to the above.

In the present invention, when an ink-receiving layer is provided, the amount of the ink-receiving layer is not particularly limited. The color and sharpness are low, and the ink is diffused in the direction of the surface of the base paper, resulting in deterioration of the dot shape called feathering, which is jagged like a bird's wing, and an image of good quality cannot be obtained. In addition, if the coating amount is too large, the drying load in the drying step after coating or impregnation increases, and not only the productivity decreases due to the decrease in the coating or impregnation speed, but also the drying under high load,
Binder in the coating composition constituting the ink receiving layer,
It moves to the surface of the ink receiving layer together with the solvent to evaporate, and reduces the amount of voids on the surface. Range of coating設量is 1 to 30 g / m ^2, more preferably from 4~20g / m ^2.

The problem that occurs in the ink receiving layer having a large coating amount can be avoided by providing a plurality of ink receiving layers in accordance with the required quality. The coating amount is affected by the concentration of the coating composition and the ability of the drying step, but is preferably 1 to 20 g / m ^2.
More preferably, it is 4 to 15 g / m ² .

Also, as for the ink jet recording paper having gloss, the coating amount may be set in accordance with the required quality, similarly to the above-described ink receiving layer. The glossy inkjet recording paper referred to in the present invention is a material obtained by providing an ink receiving layer on a base paper, calendering or casting with a super calender, soft calender, TG calender, etc. Those coated with colloidal particles or those which have been subjected to calendering or casting, or those in which an ink-receiving layer has been applied in advance on a film or process paper and bonded to base paper or a base paper provided with a coating layer on base paper, etc. Refers to a base paper having a glossy surface layer.

Cockling is a phenomenon in which the recording paper is distorted because the base paper provided with the ink receiving layer expands and contracts due to the printed ink, and the surface of the printing portion is wavy. Therefore, as the gloss value of the surface of the ink receiving layer is higher, the reflected light is scattered by the undulation of the surface and becomes more conspicuous. As a result of the present inventors' investigation on the cockling and the gloss value of the ink receiving layer, it was found that the gloss value of the receiving layer was 40
%, It was confirmed that cockling became conspicuous. Therefore, the present invention is extremely effective for inkjet recording paper having gloss, particularly for recording paper having a gloss value of the ink receiving layer of 40% or more.

When the ink jet recording paper of the present invention is obtained, either the ink receiving layer or the support layer may be applied on the base paper first, but after the ink receiving layer is applied, the non-aqueous resin is applied. It is preferable to set up a composition containing a pigment as a main component. When the ink receiving layer is applied after setting the composition on the base paper, air existing in the gaps of the base paper when the coating liquid of the coating composition of the ink receiving layer is applied to the base paper. The ink cannot be removed from the support layer side, and air bubbles emerge on the coating surface.Therefore, air bubble marks are generated on the surface of the obtained ink receiving layer, which not only impairs the quality of the ink jet recording paper, but also causes the ink jet recording. May also affect properties.

The base paper referred to in the present invention is composed mainly of wood pulp and pigment. For wood pulp, LB
Chemical pulp such as KP, NBKP, GP, PGW, RM
Mechanical pulp such as P, TMP, CTMP, CMP, and CGP; waste paper pulp such as DIP; and non-wood pulp such as kenaf, bacas, bamboo, and cotton can also be used. Pigments, binders, sizing agents, fixing agents, retention agents, cationizing agents, and various additives such as paper strength enhancers are mixed using at least one of them, and the fourdrinier, round net, and twin wire paper machines are used. The base paper can be produced by various devices such as the above, and it can be made into an acidic, neutral or alkaline paper. Further, an ink receiving layer may be provided on the base paper as it is, or a multi-layer ink receiving layer in which a size press using starch, polyvinyl alcohol or the like or an ink receiving layer is provided after an anchor coat layer is provided.

Further, the base paper may be subjected to on-machine processing by a calender comprising a metal roll and a synthetic resin roll. At that time, off-machine processing may be performed, and after processing, flatness may be controlled by further performing calendar processing using a machine calendar, a super calendar, or the like.

One or more known white pigments can be used in the base paper and ink receiving layer used in the present invention.
For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic non-crystalline White inorganic pigments such as crystalline silica, colloidal silica, colloidal alumina, pseudo-boehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohaloysite, magnesium carbonate, magnesium hydroxide, styrene-based plastic pigments,
Organic pigments such as acrylic plastic pigments, polyethylene, microcapsules, urea resins, melamine resins, and the like. Among the above, as the white pigment contained as the main component in the ink receiving layer, a porous inorganic pigment is preferable, and a porous synthetic amorphous silica, a porous magnesium carbonate, a porous alumina, and the like, and particularly, a pore volume Large porous synthetic amorphous silica is preferred.

Examples of the binder include polyvinyl alcohol, polyvinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soybean protein, silyl-modified polyvinyl alcohol, and the like;
Conjugated diene-based copolymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer; polymer or copolymer of acrylate and methacrylate; polymer or copolymer of acrylic acid and methacrylic acid Acrylic polymer latex such as coalesce; Vinyl polymer latex such as ethylene-vinyl acetate copolymer; or functional group-modified polymer latex by functional group-containing monomer such as carboxyl group of these various polymers; Melamine resin , Urea resin and other thermosetting synthetic resin-based aqueous adhesives; polymethyl methacrylate, polyurethane resin,
Synthetic resin-based adhesives such as unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and alkyd resin can be used, and one or more kinds are used.

Further, other additives include a pigment dispersant, a thickener, a flow improver, an antifoaming agent, a foam inhibitor, a release agent,
Foaming agents, penetrants, coloring dyes, coloring pigments, cationic dye fixing agents, fluorescent brighteners, ultraviolet absorbers, antioxidants, preservatives, anti-binders, waterproofing agents, wet paper strength agents, dry paper A force enhancer and the like can be appropriately compounded.

The method for coating and impregnating the base paper with the ink receiving layer according to the present invention includes various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, short dwell coaters, curtain coaters, size presses, and the like. Can be used on-machine or off-machine. After coating or impregnation, finishing may be performed using a calendar such as a machine calendar, a TG calendar, a super calendar, or a soft calendar.

In the present invention, a back coat layer may be provided on the support layer. The same pigment and binder as those used in the ink receiving layer can be used for the back coat layer. Also, the method of applying the back coat layer can be the same as the method of applying the ink receiving layer.

The ink used in the present invention includes the following colorants:
This is a recording liquid composed of a liquid medium and other additives.

Examples of the coloring agent include water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes, and food dyes.
Color pigments such as organic pigments such as carbon black and phthalocyanine and inorganic pigments such as iron oxide and zinc white are exemplified.

As the solvent for the ink, water and various water-soluble organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol,
C1-C4 alkyl alcohols such as tert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; acetone;
Ketones or ketone alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane;
Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol;
Alkylene glycols having 2 to 6 alkylene groups such as propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin, ethylene glycol methyl ether, diethylene glycol And lower alkyl ethers of polyhydric alcohols such as methyl (or ethyl) ether and triethylene glycol monomethyl ether. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferable. Other additives include, for example, P
Examples include an H regulator, a metal sequestering agent, a fungicide, a viscosity modifier, a surface tension modifier, a wetting agent, a surfactant, and a rust inhibitor.

The ink-jet recording paper of the present invention is not limited to use as ink-jet recording paper.
Any type of recording paper using liquid ink at the time of recording may be used. For example, hot-melt substances,
Thermal transfer recording, in which a heat-meltable ink mainly composed of dyes and pigments is applied on a thin support such as resin film, high-density paper, synthetic paper, etc. Image receiving paper, ink-jet recording paper that heats and melts hot-melt ink to form fine droplets, and performs flight recording; ink-jet recording paper that uses ink in which an oil-soluble dye is dissolved in a solvent; photopolymerizable monomer and colorless or colored An image receiving paper corresponding to a photosensitive pressure-sensitive donor paper using a microcapsule containing a dye or pigment may be used.

The common feature of these recording papers is that the ink is in a liquid state at the time of recording. Liquid ink is cured,
By solidification or fixing, the ink permeates or spreads in the depth direction or horizontal direction of the ink receiving layer of the recording paper. The above-mentioned various recording papers require absorptivity according to each system, and the inkjet recording paper of the present invention may be used as the above-mentioned various recording papers. Further, the ink jet recording paper of the present invention may be used as the recording paper for heating and fixing the electrophotographic recording toner widely used in copiers and printers.

The ink jet recording paper of the present invention may be provided not only in the form of a cut sheet but also in the form of a roll. The support layer may be provided with an adhesive and used for sealing, labeling and tacking. is there.

[0049]

EXAMPLES The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples.
Further, "parts" and "%" shown in Examples are parts by weight and% by weight unless otherwise specified.

<Preparation of base paper> 70 parts of LBKP having a freeness of 450 ml CSF and NBKP3 having a freeness of 450 ml CSF
In 100 parts of wood pulp consisting of 0 parts, the ratio of light calcium carbonate / heavy calcium carbonate / talc is 30/35 /
35 parts of pigment 35, commercially available alkyl ketene dimer 0.1
Part, commercial cationic acrylamide 0.03 part, commercial cationic starch 1.0 part, sulfate band 0.5 part
A paper is machined at a basis weight of 80 g / m ² using a fourdrinier paper machine, and a commercially available oxidized starch is dried at 5 g / m ^{2 in a} solid size press.
And dried to obtain a base paper.

<Ink receiving layer> The ink receiving layer applied on the above-mentioned base paper was obtained as follows. A matte ink receiving layer having a low gloss was used as an ink receiving layer A, and an ink receiving layer having a glossy surface was used as an ink receiving layer B.

(Ink Receiving Layer A) The coating composition of the ink receiving layer A is a synthetic amorphous silica (fine seal X37).
B: using 100 parts of Tokuyama Corporation, 30 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.), and 20 parts of cationic dye fixing agent (Sumireze Resin 1001: manufactured by Sumitomo Chemical Co., Ltd.), and solid content concentration. Adjusted to 13%. Next, the composition was coated on a base paper by an air knife coater so as to have a dry coating amount of 9 g / m ² ,
This was subjected to a super calendar treatment to obtain an ink receiving layer A.

(Ink Receiving Layer B) The ink receiving layer B is composed of two layers. The following ink receiving layer was further laminated on the ink receiving layer A side of the ink receiving layer A in order to impart gloss. The coating composition of the ink receiving layer is colloidal silica (Snowtex XL: manufactured by Nissan Chemical Co., Ltd.)
00 parts, modified acrylic emulsion (Movinyl 802)
0: 15 parts of Hoechst Synthetic Co., Ltd.) and 10 parts of casein (New Zealand) dissolved in alkali to obtain a solid content concentration of 20%. The coating composition was dried on the ink receiving layer A using an air knife coater to a dry coating amount of 6 g / m ^2.
After coating, ink-receiving layer B was obtained by pressure contact with a heated mirror-finished roll and casting.

<Support Layers> The following eight types of support layers A, B, C, and C are provided on the opposite surface of the ink receiving layer via the base paper.
D, E, F, G, H and a back coat layer I were provided.

(Support layer A) The base paper surface is subjected to corona discharge treatment, 100 parts of low-density polyethylene and 15 parts of commercially available first-class kaolin are kneaded, and provided with a melt extrusion die to a thickness of 15 μm. Was pressed against a cooling roll having a rough surface and cooled to obtain a support layer A.

(Support layer B) The surface of the base paper was subjected to corona discharge treatment, and 100 parts of low density polyethylene and 15 parts of commercially available heavy calcium carbonate were kneaded.
The support layer B was obtained by being pressed so as to have a thickness of 15 μm and being pressed against a cooling roll having a mirror-finished surface.

(Support Layer C) The base paper surface is subjected to corona discharge treatment, 100 parts of low-density polyethylene and 15 parts of commercially available titanium dioxide are kneaded, and provided with a melt extrusion die so as to have a thickness of 15 μm. The support layer C was obtained by being pressed against a cooling roll having a slightly rough surface and cooled.

(Support Layer D) The base paper surface was subjected to corona discharge treatment, and 100 parts of low density polyethylene and commercially available zinc oxide 1
5 parts were kneaded and the thickness was adjusted to 15
The support layer D was obtained by being pressed against a cooling roller having a rough surface and cooling.

(Support layer E) The base paper surface is subjected to corona discharge treatment, 100 parts of low-density polyethylene and 15 parts of commercially available barium sulfate are kneaded, and provided with a melt extrusion die so as to have a thickness of 15 μm. The support layer E was obtained by being pressed against a cooling roller having a slightly rough surface and cooled.

(Support Layer F) The surface of the base paper was subjected to corona discharge treatment, and 100 parts of low-density polyethylene, 10 parts of commercially available primary kaolin, and 10 parts of commercially available titanium dioxide were kneaded, and the thickness was reduced using a melt extrusion die. Provided to be 15 μm,
The support layer F was obtained by being pressed against a cooling roll having a rough surface and cooled.

(Support layer G) The base paper surface is subjected to corona discharge treatment, low-density polyethylene is provided to a thickness of 15 μm using a melt-extrusion die, and is pressed against a cooling roll having a rough surface to cool the support. Layer G was obtained.

(Support layer H) The surface of the base paper is subjected to corona discharge treatment, low-density polyethylene is provided to a thickness of 15 μm using a melt-extrusion die, and the surface is pressed against a cooling roll having a mirror surface to cool the support layer. H was obtained.

(Backcoat layer I) 100 parts of commercially available primary kaolin, commercially available styrene-butadiene latex 1
A coating composition obtained by adjusting 0 parts and 5 parts of commercially available oxidized starch at a solid concentration of 50% was applied and dried using an air knife coater to a dry coating amount of 10 g / m ² , A super calender treatment was performed to obtain a back coat layer I.

Examples 1 to 7 and Comparative Examples 1 to 5 As shown in Table 1, Examples 1 to 7 each comprising a combination of base paper, ink receiving layers A and B, support layers A to H, and back coat layer I 7 and Comparative Examples 1 to 5 were obtained.

Table 1 shows the evaluation results of Examples 1 to 7 and Comparative Examples 1 to 5. The cockling and transportability shown in Table 1 were evaluated by the following methods.

<Evaluation of Cockling> A commercially available ink jet printer (MJ830C: manufactured by Epson Corporation)
Using a 1 in the center of the sample cut to A4 size
After performing solid printing with black ink in a size of 5 cm square,
The degree of undulation on the printed surface and the back surface was visually evaluated, and judged based on the following criteria. There are no problematic levels of A and B, and in C or D, degradation of image quality is visually recognized due to occurrence of cockling, which poses a problem. A: No cockling occurs. B: Cockling is slightly visually recognized at the boundary between the solid printing portion and the non-printing portion. C: Cockling is visible in the entire printing area. D: The cockling is visually recognized in a state in which the cockling is greatly swollen over the entire printing portion.

<Evaluation of Ink Penetration> Using a commercially available photo ink jet printer (BJC-420J, manufactured by Canon Inc.), the center portion of a sample cut into A4 size was blue (cyan + magenta) with a size of 10 cm square. )
After performing multicolor printing, a commercially available reflection densitometer (Macbeth R
(D918: Macbeth)), the image density of the back side of the printed portion and the back side of the non-printed portion were measured, the density ratio of the non-printed portion / printed portion was calculated, and the removal of ink on the back side was determined according to the following criteria.
A and B are practically acceptable levels. A: Non-printed portion / printed portion density ratio is 1 to 0.9 B: Non-printed portion / printed portion density ratio is 0.89 to 0.75 C: Non-printed portion / printed portion density ratio is 0.74 to 0 .5D: Non-printed area / printed area density ratio is less than 0.5

<Opacity> The opacity of the ink jet recording paper was measured using a commercially available reflectometer (Digital Hunter reflectometer: manufactured by Toyo Seiki Seisaku-sho, Ltd.) in accordance with JIS P8138.

<Evaluation of Conveyance> Using the ink jet printer used for cockling evaluation, 20 sheets of A4 size ink jet recording paper were set as one set, and the conveyability at the end of 5 sets was evaluated according to the following criteria. The evaluation was performed by counting the number of untransports and the number of double feeds and calculating the number of occurrences. A and B are practically acceptable levels. A: Number of occurrences is zero B: Number of occurrences is 5 or less C: Number of occurrences is 6 to 10 D: Number of occurrences is 11 or more

<Gloss> The gloss of the ink receiving layer surface and the support layer surface was measured using a commercially available gloss meter (digital gloss meter GM-260D type: manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS P8142. , 75 degree specular gloss was measured.

[0071]

[Table 1]

As is evident from Table 1, in Examples 1 to 7 in which at least one of the support layers was composed of a composition mainly composed of a non-aqueous resin and a white pigment, cockling and ink strike-through of the printed portion were not observed. If the gloss value of the support layer is 70% or less, good transportability can be obtained. on the other hand,
In Comparative Examples 1 to 3, a composition mainly composed of a non-aqueous resin was provided in the support layer. However, since the support layer did not contain a white pigment, the opacity was low, and strikethrough of the ink was visually recognized. In Comparative Examples 4 and 5, a back coat layer mainly composed of a pigment was provided, but both cockling and ink strike-through were at a poor level.

[0073]

According to the present invention, at least one layer of a composition mainly composed of a non-aqueous resin and a white pigment is provided as a support layer on the surface opposite to the surface of the ink receiving layer with the base paper interposed therebetween. It is possible to provide an ink jet recording paper in which waviness (cockling) and ink strike-through on the printing section surface are avoided, and the support layer has a glossiness of 70% or less, and the transportability is also ensured. .

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Noguchi 3-4-2, Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills F-term (reference) 2C056 FC06 2H086 BA15 BA24 BA33 BA36 BA41 4F100 AA07C AA07H AA20B AA20H AA21C AA21H AA25C AA25H AK01C AK06C AK21B AK25B AR00B AT00A BA03 BA07 BA10B BA10C CA13C CC00B DG10A GB90 HB00C HB00H JD14B JL10C JL10H JN02 JN21C YY00 YY00C

Claims (4)

[Claims] 1. An ink jet recording sheet comprising at least one ink receiving layer on a base paper and at least one support layer on the opposite side of the ink receiving layer via the base paper. Wherein at least one layer comprises a composition comprising a non-aqueous resin and a white pigment as main components. 2. The ink jet recording paper according to claim 1, wherein the opacity specified in JIS P8138 is 85% or more. 3. The ink jet recording paper according to claim 1, wherein a main component of the white pigment is at least one selected from titanium dioxide, zinc oxide and barium sulfate. 4. The surface of the support layer is JIS P814
4. The ink jet recording paper according to claim 1, wherein the 75-degree specular glossiness specified in 2 is 70% or less.