JPH08300805A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE: To obtain an ink jet recording sheet prevented from the surface damage caused by the contact with the paper feed roll or device arranged to the feed part of a printer and ensuring ink absorbability. CONSTITUTION: An ink jet recording sheet of which the 75 deg. surface gloss measured by JIS-Z8741 is 20% or more is obtained by applying at least one ink receiving layer to a support. The support is composed of a compsn. based on wood pulp and the penetration measured based on JIS-K2207 after wetting of the recording sheet is 0.5-4.0.

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 sheet for recording by using a water-based ink, and more particularly, by contacting a surface of a recording sheet with a paper feed roll or a device installed in a conveying portion of a printer. The present invention relates to an ink jet recording sheet that prevents damage to the surface of the recording sheet and causes ink absorption.

[0002]

2. Description of the Related Art The ink jet recording system is a system in which minute droplets of ink are ejected by various operating principles to adhere to a recording sheet such as paper to record images, characters, etc., but at high speed and low noise. It has features such as easy multicoloring, great flexibility in recording patterns, and no need for development-fixing. It has rapidly spread in various applications as a recording device for various figures and color images including Chinese characters. There is. Furthermore, the image formed by the multicolor inkjet method is
Compared to multicolor printing by plate making method and printing by color photographic method, it is possible to obtain recording comparable to that. Further, in applications requiring a small number of copies, it is being widely applied to the full-color image recording field because it is cheaper than the photographic technique.

Recording sheets applied to the ink jet recording system include fine papers and coated papers used for lithographic printing, letterpress printing, gravure printing, etc. Has been studied for obtaining a good image quality. However, in order to satisfy these requirements by increasing the speed of inkjet recording, improving the required image quality, expanding the applications, etc.,
It has become difficult to deal only with the recording device and the ink composition.

The following items are given as examples of the properties required of the recording sheet. 1. Ink absorption is fast. When the ink absorbency is lowered, the ink is diffused to areas other than the printed portion, the sharpness is lowered due to the enlarged dot diameter, and the white paper portion is contaminated by the ink called scumming. Further, this phenomenon becomes remarkable in the portion where the inks overlap. 2. Print dots do not spread. Although the dot diameter depends on the recording apparatus, when the ink lands on the recording sheet and then diffuses, the color and sharpness deteriorate, resulting in a blurred image. 3. No change in image quality over time. It is not affected by the environment in which it is used. For example, it has excellent light resistance, water resistance, and ozone resistance.

In response to such demands, some proposals have heretofore been made. In order to improve the ink absorbency and prevent the diffusion of print dots, a method of providing an ink absorbing layer on a support (Japanese Patent Laid-Open Nos. 52-9074 and 58-72495, etc.), ink in the ink absorbing layer Paying attention to the fact that the distribution state of the dye component of
A method using a specific agent that adsorbs a dye component (JP-A-55-1)
No. 44172). Further, in order to improve light resistance, water resistance, and ozone resistance, a basic oligomer should be contained (JP-A-60-11389), and a polyvinylamine copolymer should be added to the coating layer in or on the substrate. It is disclosed that a polymer is used (JP-A-64-8085).

Further, in recent years, in order to improve image quality and print speed, conveyance accuracy in a printing process has become an important characteristic. This is because if the transport accuracy is low,
This is because the ink landing position on the paper becomes unstable and the image quality is degraded. When the portion that ejects ink (ink head) scans and prints in the width direction of the paper, the ejection timing may be controlled by an electrical signal, but in addition to the paper feed direction, It is necessary to keep the paper feed accuracy. For this,
It is necessary to suppress the recording sheet accurately in the conveying section of the recording apparatus, and there is no choice but to bring the recording sheet, the paper feed roll, and the conveying apparatus into contact with each other under a load. This indicates that the surface of the paper is damaged by the force applied from the paper feed roll or the conveyance device, and if the print surface is damaged, the quality of the image is deteriorated.

In order to avoid damage to the surface, it is possible to harden the surface, but since it is difficult to be crushed in the flattening process, the contact area with the paper feed roll and the transport device is reduced, and the paper feed accuracy is reduced. To do. Increasing the planarization process to increase the contact area will reduce ink absorption.

Although the ink jet recording apparatus has reached the point of obtaining an image comparable to a photograph or a printed matter which is inexpensive and has excellent image reproducibility and color reproducibility such as sharpness and color property, it is fatal that the surface of the paper is damaged. Problem. Although the improvement is being made on the recording apparatus side and the paper side, the present situation is that it is not possible to obtain an ink jet recording sheet which does not damage the surface while ensuring the ink absorbability which is an important characteristic in ink jet recording.

[0009]

SUMMARY OF THE INVENTION An object of the present invention relates to an ink jet recording sheet, and with the recent increase in the recording speed of ink jet recording methods, a paper feed roll and a conveying device suppress the paper with a high load. Another object of the present invention is to obtain an ink jet recording sheet in which damage to the surface of the paper due to contact with the roll and the device which occurs in order to improve the conveyance accuracy is avoided and the ink absorbability, which is an important feature of the ink jet recording sheet, is secured.

[0010]

As a result of intensive studies, the present inventors have come to invent the ink jet recording sheet of the present invention.

That is, in the ink jet recording sheet of the present invention, at least one or more ink receiving layers are coated on the support, and the surface to be printed is JIS Z874 of 20% or more.
An ink jet recording sheet having a 75-degree specular gloss measured according to 1, wherein the support contains wood pulp as a main component, and JIS K2
The penetration of the recording sheet measured based on 207 is 0.
It is characterized by being 5 to 4.0.

Further, the object of the present invention is certain when the support contains 10% or less of the pigment.

The ink jet recording sheet of the present invention will be described in detail below.

The ink jet recording sheet of the present invention comprises a support containing wood pulp as a main component and an ink receiving layer coated on the surface of the support. After the recording sheet is wet to attain the object of the present invention. The feature is that the penetration degree of is within a specific range.

The ink receiving layer according to the present invention is composed of a coating composition containing a pigment and a binder as main components. As the pigment, one or more known white pigments can be used. For example, light calcium carbonate, heavy calcium carbonate, magnesium 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 amorphous silica, colloidal silica, alumina,
White inorganic pigments such as colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, hydrohalloysite, magnesium hydroxide, styrene plastic pigment, acrylic plastic pigment,
Examples include organic pigments such as polyethylene, microcapsules, urea resins, and melamine resins. In particular, a porous pigment is preferable from the viewpoint of ensuring the ink absorption capacity.

Examples of the binder include starch derivatives such as oxidized starch, etherified starch and phosphoric acid esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol or its derivatives; polyvinyl pyrrolidone, Conjugated diene copolymer latex such as maleic anhydride resin, styrene-butadiene copolymer, methylmethacrylate-butadiene copolymer; acrylic polymer such as acrylic acid ester and methacrylic acid ester polymer or copolymer Acrylic polymer latex; vinyl polymer latex such as ethylene-vinyl acetate copolymer; or functional group-modified polymer latex with a functional group-containing monomer such as carboxy group of these various polymers; Water-based adhesives such as thermosetting synthetic resins such as epoxy resins and urea resins; acrylic acid esters such as polymethylmethacrylate; polymer or copolymer resins of methacrylic acid esters; polyurethane resins, unsaturated polyester resins, vinyl chloride-acetic acid Examples thereof include synthetic resin adhesives such as vinyl copolymers, polyvinyl butyral, and alkyd resins. The binder content is 3 to 70 parts by weight with respect to 100 parts by weight of the pigment,
The amount is preferably 5 to 50 parts by weight, and if it is less than 3 parts by weight, the coating strength of the ink receiving layer may be insufficient, and if it exceeds 70 parts by weight, the ink absorbency may be lowered.

Further, in the ink receiving layer, as an additive, a dye fixing agent, a pigment dispersant, a thickener, a fluidity improving agent,
Defoamer, foam suppressor, release agent, foaming agent, penetrant, coloring dye,
Coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, antifungal agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers and the like can be appropriately added.

In particular, a secondary amine which forms an insoluble salt with a sulfonic acid group, a carboxyl group, an amino group, etc. in a water-soluble direct dye or a water-soluble acid dye which is a dye component of an aqueous ink,
When a cationic dye fixing agent composed of a tertiary amine and a quaternary ammonium salt is blended, the dye is captured in the ink receiving layer, so that the color is improved and the ink is dropped by water absorption due to the formation of an insoluble salt. It is preferable because it suppresses the flow and bleeding of water.

The method for applying the ink receiving layer is carried out by various machines such as various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters and size presses on machine or off machine. Can be used. Further, after coating, it is also possible to carry out a flattening finish using a calendar device such as a machine calendar, a TG calendar, a super calendar and a soft calendar. The coating amount of the ink receiving layer is 1 g / m ² or more, although it varies depending on the required characteristics, the type of support and the like.

It is also possible to coat one or more ink receiving layers on the support, and to protect the receiving layer from gloss deterioration in order to impart gloss to the receiving layer and to protect the receiving layer from deterioration due to ultraviolet rays. Further, a coating layer such as an ultraviolet absorbing layer may be further provided. The same method as that for the ink receiving layer is used for coating and flattening.

The support used in the present invention is LB
Chemical pulp such as KP, NBKP, GP, PGW, RM
P, TMP, CTMP, CMP, CGP and other mechanical pulps, DIP and other waste paper pulps and other wood pulps and conventionally known pigments as main components, and binders and sizing agents and fixing agents, retention aids, cationizing agents, Starch, polyvinyl alcohol, and base paper manufactured by various devices such as Fourdrinier paper machine, cylinder paper machine, twin wire paper machine, etc. Base paper with a size press or anchor coat layer on it, art paper with a coat layer on them,
It also includes coated paper such as coated paper and cast coated paper.
Such a base paper and a coated paper may be provided with the coating layer according to the present invention as they are, or a calender device such as a machine calender, a TG calender or a soft calender may be used for the purpose of controlling the flatness. . The basis weight of the support is usually 40 to 300 g / m ² , but is not particularly limited.

The aqueous ink referred to in the present invention is a recording liquid containing the following colorant, liquid medium, and other additives.

The colorant is a water-soluble dye such as a direct dye, an acid dye, a basic dye, a reactive dye or a food dye.

As the solvent of the aqueous 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, tert-butyl alcohol, C1-C4 alkyl alcohols such as isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, polypropylene glycol Polyalkylene glycols such as; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodig Call, hexylene glycol, an alkylene group such as diethylene glycol 2
~ 6 alkylene glycols; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether.

Among many of these 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 preferred.

Other additives include, for example, a pH adjusting agent, a sequestering agent, an antifungal agent, a viscosity adjusting agent, a surface tension adjusting agent, a wetting agent, a surfactant, and a rust preventive agent.

The ink jet recording sheet according to the present invention is not limited to use as an ink jet recording sheet, and may be used as any recording sheet that uses a liquid ink during recording. For example, an ink sheet in which a heat-fusible ink containing a heat-fusible substance, a dye or pigment as a main component is applied on a thin support such as a resin film, high-density paper, or synthetic paper is heated from the back surface of the ink sheet, An image-receiving sheet for thermal transfer recording that melts and transfers, an inkjet recording sheet that heat-melts a heat-melting ink into fine droplets for flight recording, an inkjet recording sheet that uses an ink in which an oil-soluble dye is dissolved in a solvent, photopolymerization An image receiving sheet corresponding to a light and pressure sensitive donor sheet using microcapsules containing a type monomer and colorless or colored dyes and pigments can be mentioned.

The common point of these recording sheets is that the ink is in a liquid state at the time of recording. The liquid ink permeates or spreads in the depth direction or the horizontal direction of the ink receiving layer of the recording sheet before being cured, solidified, or fixed. The various recording sheets described above require absorptivity according to their respective systems, and the inkjet recording sheet of the present invention may be used as the various recording sheets described above.

Further, the ink jet recording sheet of the present invention may be used as a recording sheet for heating and fixing the toner of the electrophotographic recording system which is widely used in copying machines, printers and the like, and an adhesive layer may be provided. It can also be used for labels.

In order to prevent damage to the surface of the recording sheet, which is an object of the present invention, it is possible to finish by making the ink receiving layer hard, but to ensure transportability in the ink jet recording apparatus. In order to obtain a smooth surface, a flattening treatment is indispensable. However, this treatment reduces the absorption capacity of the ink receiving layer, resulting in unacceptable deterioration of ink absorption.

For this reason, it is conceivable to increase the coating amount of the ink receiving layer, but the increased amount of the layer causes the peeling of the coating layer due to the reduction of the coating layer strength and the reduction of the printing density due to the increase of the light scattering. Moreover, the amount of coating cannot be simply increased.

That is, it has been shown that it is difficult to deal with the surface damage and the ink absorptivity, which have contradictory characteristics, only with the ink receiving layer. However, as shown in the present invention, a support is mainly composed of wood pulp, an ink receiving layer is coated thereon, and an ink jet recording sheet is further prepared so that the penetration is within a specific range. It is possible to achieve both of these contradictory characteristics.

By using wood pulp as the main component of the support, it becomes possible to impart ink absorption characteristics to the support, and it is possible to obtain an ink jet recording sheet having an absorption capacity combined with the ink receiving layer. Become. But,
The support is soft, and when the load generated by the contact between the surface of the inkjet recording sheet and the inkjet recording device is transmitted from the surface and reaches the support, the support is deformed to change the surface shape of the recording sheet. Changing, that is,
Like the damage to the surface, it causes deterioration in appearance.

Further, the deformation of the support is more likely to occur due to the absorption of ink after printing, and the printed surface state is particularly important for determining the quality of image. The surface damage that occurs after printing is caused by the swelling of the wood pulp that is the main component of the support due to the permeation of the ink into the support, and the swelling is caused by the contact with the inkjet recording device. External force hinders
The surface where the external force is applied has a concave shape, and the entire surface of the recording sheet has an uneven shape, which greatly impairs the appearance.

The present inventors pursued the degree of surface damage and found that the surface of the ink jet recording sheet was JIS
75 degree specular gloss measured based on Z8741 is 2
It was found that the degree of surface damage is visually recognized when it is 0% or more. This is because the reflection direction of light on the surface is different due to the damage, and the glossy portion and the non-glossy portion are visually recognized, resulting in deterioration of image quality. The matte or matte ink jet recording sheet having a gloss level of less than 20% is hard to be visually recognized because the surface is damaged and the light reflection amount is small even if the light reflection direction is different. Does not significantly decrease

The degree of damage on this surface is determined by JIS.
It was found that there is a high correlation with the penetration measured according to K2207. Further, pure water was dropped on the printing surface of the ink jet recording sheet, wetted for 5 seconds, and then the penetration measured by this penetration measuring method (hereinafter, abbreviated as penetration).
However, it was found that the object of the present invention is to avoid the damage on the surface and the degree of ink absorption.

That is, only when the penetration is in the range of 0.5 to 4.0, it is possible to obtain an ink jet recording sheet having no surface damage and good ink absorbability. In order to make such an ink jet recording sheet, the composition of the support and the ink receiving layer and the manufacturing method may be appropriately selected from the above so as to fall within the range.

For example, for a support having a high degree of size, fine ink holes are generally formed in the ink receiving layer so that the ink absorbing speed is increased by capillary action because the ink absorbing speed is slow, but this method is simply used. Does not satisfy the object of the present invention, so as to fall within the range of the penetration,
It is necessary to control the coating amount of the receiving layer, coating conditions, calendering conditions and the like.

Further, for the ink receiving layer having a small ink absorption capacity, it is necessary to increase the ink absorption capacity of the support and the ink absorption rate to the support, but in this case as well, the range of the penetration is It is necessary to manipulate the basis weight of the support, the size, the amount of pigment contained, the papermaking conditions, etc.

[0040]

The inkjet recording sheet of the present invention is characterized in that the penetration of the recording sheet measured according to JIS K2207 after wetting is 0.5 to 4.0. If the penetration is less than 0.5, the ink absorbency is poor and stains may occur when the printing section comes into contact with the apparatus in the ink jet recording apparatus, or the mixed color section may have different hues or enlarged dots. As a result, the image quality is greatly deteriorated. Further, when the penetration is more than 4.0, the ink absorbability is excellent, but the surface is damaged and the image quality is good, but the image quality is greatly deteriorated.

It is further preferable that the pigment contained in the support is 10% or less. This is because the pigment inhibits the binding of the wood pulps to each other, and when the ink penetrates into the support, the swelling of the wood pulp is likely to occur, and the support containing a large amount of the pigment is supported. The surface of the body is more likely to be damaged. In particular, when the coating amount of the ink receiving layer is reduced and the ink absorbability to the support is increased, this phenomenon appears when the content exceeds 10%.

[0042]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited to these examples. Also,
Unless otherwise specified, "parts" and "%" shown in the examples mean absolute dry weight parts and absolute dry weight%.

Further, the amount and the penetration of the pigment contained in the support shown in each of Examples and Comparative Examples were determined by the following methods.

<Amount of pigment contained in the support> An absolutely dry weight W0 of the support is weighed, the weighed support is put into a crucible, and the mixture is burned at a temperature of 550 ° C. to obtain the weight W1 of the residue in the crucible.
After weighing, the amount P of the pigment contained in the support was calculated by the following formula 1. The unit is% by weight.

[0045]

## EQU1 ## P = (W1 / W0) × 100

<Penetration> The ink jet recording sheet and pure water were placed under the environment specified in JIS P8111 for 24 hours.
I left it for more than an hour. 10 μl of pure water was dropped on the surface to be printed, and after 5 seconds, the penetration was measured according to JIS K2207. Penetration tester (AN-20
0: manufactured by Nippon Oil Testing Machine Industry Co., Ltd.) was used.

<Specular glossiness> The ink jet recording sheet was left for 24 hours or more in the environment specified in JIS P8111. After that, the measurement is based on the 75-degree specular gloss defined by JIS Z8741 (VGS-1).
001DP: manufactured by Nippon Denshoku Industries Co., Ltd.). The display is%.

The support and the ink receiving layer used in Examples and Comparative Examples were obtained by the following method. <Adjustment of Support> Supports 1 to 4 can be prepared by the following method.

<Support 1> LBKP (freeness 400 mlcsf)
2 parts of heavy calcium carbonate to 100 parts of wood pulp consisting of 80 parts and 20 parts of NBKP (freeness 400 mlcsf)
Talc 2 parts, commercial size 0.01 part, sulfuric acid band 0.
4 parts, 0.2 parts of a commercial yield improver are mixed to form a mixture,
A support 1 having a basis weight of 90 g / m ² was prepared using a Fourdrinier paper machine. The amount of pigment contained in the support was 4.1%.

<Support 2> LBKP (freeness 480 mlcsf)
To 100 parts of wood pulp consisting of 90 parts and 10 parts of NBKP (freeness 450 mlcsf), 10 parts of talc, 0.08 part of commercial sizing agent, 0.3 part of sulfuric acid band, 0.1 part of commercial retention aid To prepare a mixture, and using a Fourdrinier paper machine to prepare a support having a basis weight of 90 g / m ² , and then the oxidized starch (M
S3800: The Japan Food Processing Co., Ltd.) and a size press so that the dry coating amount of 2g / m ^2, was to obtain a support 2. The amount of pigment contained in the support was 9.5%.

<Support 3> LBKP (freeness 400 mlcsf)
8 parts of light calcium carbonate to 100 parts of wood pulp consisting of 80 parts and 20 parts of NBKP (freeness 480 mlcsf),
Talc 8 parts, heavy calcium carbonate 8 parts, commercial size 0.2 parts, sulfuric acid band 0.4 parts, commercial retention aid 0.0
3 parts were blended into a mixture, and a Fourdrinier paper machine was used to prepare a support having a basis weight of 90 g / m ² , and then the oxidized starch (MS3
800: manufactured by Nippon Food Processing Co., Ltd.) was size-pressed to a dry coating amount of 2 g / m ² to obtain a support 3. The amount of pigment contained in the support was 19.2%.

<Support 4> A commercially available white PET (polyethylene terephthalate) sheet was used as Support 4.

<Adjustment of Ink Receiving Layer> Ink receiving layers 1 to
The coating composition of No. 4 could be prepared by the following method.

<Coating composition for ink receiving layer 1> 70 parts of amorphous silica (Fineseal X37B: manufactured by Tokuyama) as a pigment, 30 parts of organic pigment (Movinyl 970: manufactured by Hoechst Synthetic), and polyvinyl alcohol as a binder. 30 parts of (PVA117: manufactured by Kuraray Co., Ltd.) and 20 parts of a commercially available polyvinylamine-based polymer as a dye fixing agent were mixed and adjusted to a solid content concentration of 16% to obtain a coating composition for the ink receiving layer 1.

<Coating Composition of Ink Receiving Layer 2> The ink receiving layer 2 comprises a lower layer coated on a support and an upper layer further laminated on the lower layer. The coating composition for the lower layer is amorphous silica (Mizukasil P78D: manufactured by Mizusawa Chemical Co., Ltd.) as a pigment.
100 parts, polyvinyl alcohol (P
VA117: manufactured by Kuraray Co., Ltd.) and 20 parts of a commercially available polyvinylamine-based polymer as a dye fixing agent were mixed to obtain a solid content concentration of 18%.

The coating composition for the upper layer was colloidal particles (Snowtex XL, manufactured by Nissan Chemical Industries, Ltd.) 90 as a pigment.
Part, acrylic organic pigment (Movinyl 790: Hoechst Synthetic) 10 parts, acrylic emulsion as a binder (Movinyl 8020: Hoechst Synthetic) 20
Part, and 0.3 part of commercially available potassium oleate as a release agent were mixed and adjusted to a solid content concentration of 35% to obtain a coating composition for the ink receiving layer 2.

<Ink Receiving Layer 3> The ink receiving layer 3 is composed of a lower layer coated on a support and an upper layer further laminated on the lower layer. The coating composition of the lower layer is amorphous silica (Fineseal X37B: manufactured by Tokuyama Corporation) 100 as a pigment.
Parts, polyvinyl alcohol (PVA1 as a binder
17: manufactured by Kuraray Co., Ltd.), and 20 parts of a commercially available polyvinylamine-based polymer as a dye fixing agent are mixed, and the solid content concentration is 1
It was obtained by adjusting to 5%.

The coating composition for the upper layer was colloidal particles (Snowtex XL, manufactured by Nissan Chemical Industries, Ltd.) 50 as a pigment.
Part, acrylic organic pigment (Movinyl 790: Hoechst Synthetic) 50 parts, acrylic emulsion as a binder (Movinyl 8020: Hoechst Synthetic) 15
Parts were mixed and adjusted to a solid content concentration of 40% to obtain a coating composition for the ink receiving layer 3.

<Ink Receiving Layer 4> The ink receiving layer 4 comprises a lower layer coated on the support and an upper layer further laminated on the lower layer. The coating composition of the lower layer is amorphous silica (Fineseal X37B: manufactured by Tokuyama Corporation) 100 as a pigment.
Parts, polyvinyl alcohol (PVA1 as a binder
17: manufactured by Kuraray Co., Ltd.) and 20 parts of a commercially available polyvinylamine-based polymer as a dye fixing agent were mixed to obtain a solid content concentration of 15%.

The coating composition for the upper layer was an acrylic organic pigment (Movinyl 790: Hoechst Synthetic Co., Ltd.) as a pigment.
00 parts and 15 parts of an acrylic emulsion (Movinyl 8020: Hoechst Synthetic Co., Ltd.) as a binder were mixed and adjusted to a solid content concentration of 40% to obtain a coating composition for the ink receiving layer 4.

Example 1 The ink receiving layer 1 was applied on the surface of the support 3. The receiving layer was coated with an air knife coater so as to have a dry coating amount of 10 g / m ² and dried, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 1. The penetration and specular gloss of the recording sheet are 3.
9 and 31%.

Example 2 The ink receiving layer 1 was applied on the surface of the support 1. The receiving layer was coated with an air knife coater to a dry coating amount of 10 g / m ² and dried, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 2. The penetration and specular gloss of the recording sheet are 1.
3 and 28%.

Example 3 An ink receiving layer 3 was coated on the surface of the support 2. Regarding the receiving layer, the lower layer is first coated with an air knife coater so as to have a dry coating amount of 10 g / m ² and dried, and then the upper layer is dried with a coating amount of 12 g / m ^2.
It was coated with an air knife coater so as to be m ² and dried.
Then, a super calender treatment was performed at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 3. The penetration and specular gloss of the recording sheet are 1.6 and 6
It was 1%.

Example 4 The ink receiving layer 2 was coated on the surface of the support 3. The lower layer of the receiving layer was first coated with an air knife coater so that the dry coating amount was 10 g / m ^2, and then the upper layer was dry coating amount of 10 g / m ^2.
After coating with m ² surface temperature 1 while upper layer is wet
An ink jet recording sheet of Example 4 was obtained by press-contacting a mirror surface roll heated to 00 ° C. and drying. The penetration and specular gloss of the recording sheet were 2.8 and 88%.

Example 5 An ink receiving layer 2 was coated on the surface of the support 1. The lower layer of the receiving layer was first coated with an air knife coater so that the dry coating amount was 10 g / m ^2, and then the upper layer was dry coating amount of 10 g / m ^2.
After coating at g / m ² , while the upper layer was in a wet state, it was pressed against a mirror-finished roll heated to a surface temperature of 100 ° C. and dried to obtain an inkjet recording sheet of Example 5. The penetration and specular gloss of the recording sheet were 0.5 and 81%.

Example 6 The ink receiving layer 1 was applied on the surface of the support 2. The receiving layer was coated with an air knife coater so as to have a dry coating amount of 10 g / m ² and dried, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 6. The penetration and specular gloss of the recording sheet are 1.
9 and 30%.

Example 7 An ink receiving layer 2 was coated on the surface of the support 2. The lower layer of the receiving layer was first coated with an air knife coater so that the dry coating amount was 10 g / m ^2, and then the upper layer was dry coating amount of 10 g / m ^2.
After coating at g / m ² , while the upper layer was in a wet state, it was pressed against a mirror-finished roll heated to a surface temperature of 100 ° C. and dried to obtain an inkjet recording sheet of Example 7. The penetration and specular gloss of the recording sheet were 0.6 and 87%.

Example 8 Polyvinyl alcohol (P with a concentration of 3% was added to the surface of the support 1).
VA117: manufactured by Kuraray Co., Ltd.) was coated with an air knife coater so that the dry coating amount was 2 g / m ² and dried, and then the ink receiving layer 1 was coated. The receiving layer has a dry coating amount of 10 g / m2
After coating and drying with an air knife coater so that
Super calendering was performed at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Example 8. The penetration and specular gloss of the recording sheet were 0.9 and 28%.

Comparative Example 1 An ink receiving layer 4 was coated on the surface of the support 2. The receiving layer was coated with an air knife coater so as to have a dry coating amount of 12 g / m ² and dried, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Comparative Example 1. The penetration and specular gloss of the recording sheet are 4.
6 and 69%.

Comparative Example 2 An ink receiving layer 3 was coated on the surface of a support 4. The receiving layer was coated with an air knife coater so as to have a dry coating amount of 15 g / m ² and dried, and then supercalendered at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Comparative Example 2. The penetration and specular gloss of the recording sheet are 0.
6 and 64%.

Comparative Example 3 Polyvinyl alcohol (P
(VA117: manufactured by Kuraray Co., Ltd.) A solution was coated by an air knife coater so that the dry coating amount was 5 g / m ² and dried, and then the ink receiving layer 1 was coated. The receiving layer has a dry coating amount of 10 g / m ²
After coating and drying with an air knife coater so that
Super calendering was performed at a linear pressure of 100 kg / cm to obtain an inkjet recording sheet of Comparative Example 3. The penetration and specular gloss of the recording sheet were 0.2 and 26%.

Table 1 shows the evaluation results of Examples 1 to 7 and Comparative Examples 1 to 3. The evaluation of ink absorbency in Table 1 was performed based on the following two methods.

<Ink Absorbency 1> Using a commercially available ink jet printer (Design jet650C: manufactured by Hewlett-Packard Co.), double-color printing composed of cyan ink and magenta ink was performed, and after 10 seconds from printing, a blank sheet was printed on the printing surface. The state of transfer to a blank sheet was visually evaluated by the following criteria. If the transfer occurs, stains are generated during transportation. The A evaluation is not a problem in practical use. A: No ink transfer was observed on the white paper. C: Ink transfer is observed on white paper.

<Ink Absorbency 2> Using the above-mentioned ink jet printer, images composed of cyan ink and magenta ink were made to be adjacent to each other, and a straight line of an overlapping portion was evaluated according to the following criteria. Linearity is related to ink absorbency, and low linearity results in poor color and sharpness. The A or B evaluation is not a problem in practical use. A: Excellent linearity. B: A whisker-like spread is slightly seen in the order of several tens of μm in the adjacent portion, but there is no problem. C: A beard-like spread occurs on the order of several mm, which affects the image quality.

<Surface Damage State> Using the above-mentioned ink jet printer, a heavy-colored step wedge (gray level: 5% to 10%) composed of cyan ink and magenta ink is used.
0%; 5% step unit) was printed on the recording sheet, and the damage on the printing surface by the blade-shaped roll installed in the printer conveyance portion was visually evaluated. The higher the gradation level (the greater the amount of ejected ink), the greater the damage to the printed surface. However, if the gradation level at which the damage is visually observed is 70% or more, the surface quality that causes a problem in image quality will be a practical problem. Does not cause damage.

[0076]

[Table 1]

As shown in Examples 1 to 8 and Comparative Examples 1 to 3, the ink jet recording sheets specified by the present invention and having a penetration of 0.5 to 4.0 have ink absorbability. It can be seen that the state of damage on the surface is good and the inkjet recording sheet aimed at by the present invention can be obtained. In Comparative Example 1 in which the penetration is more than 4.0, the ink absorbability is good, but the surface damage is large, and the penetration is 0.5.
In Comparative Examples 2 and 3 which do not satisfy the requirement, the surface condition is good, but it is found that unacceptable deterioration of ink absorption occurs.

In particular, in Comparative Example 2 in which the support is a non-absorbent body containing no wood pulp as a main component, both the ink absorptivity 1 and 2 which are evaluation items are poor, and it is shown that it is not practical. Further, in Comparative Example 3, the ink drying property is better than the ink absorption property 1, but the ink absorption speed within a relatively short period of time is slow. However, when the dots are overlapped, the dot diameter is enlarged and the color is deteriorated in different inks. This is because the film-forming polyvinyl alcohol was anchor-coated on the support,
As is clear from Example 8 in which the amount of the anchor coat is small, it is possible to control the penetration degree by adjusting the type and amount of the anchor coat, and it is understood that the object of the present invention is achieved.

Further, as is clear from Examples 6 and 7, when the amount of the pigment contained in the support is 10% or less, the penetrability is small and the state of surface damage is good. I understand.

[0080]

According to the present invention, by making an ink jet recording sheet so that the penetrability of the surface in a wet state falls within a specific range, the ink jet recording device and the conveying section in the device are brought into contact with each other. It is possible to obtain an inkjet recording sheet that avoids the surface damage caused by the above and secures ink absorbability.

Claims (2)

[Claims] 1. A JIS in which at least one or more ink receiving layers are coated on a support and the surface to be printed is 20% or more.
An ink jet recording sheet having a 75-degree specular gloss measured according to Z8741, wherein the support contains wood pulp as a main component, and J
An ink jet recording sheet having a penetration of 0.5 to 4.0 measured according to IS K2207. 2. The ink jet recording sheet according to claim 1, wherein the support contains 10% or less of a pigment.