JPH1111009A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plain paper type ink jet recording sheet having excellent water resistance of an image, image density and feathering and small discoloring with elapse of time in a printing part. SOLUTION: The plain paper type ink jet recording sheet comprises cationic resin of 0.2 g/m<2> or more of dry coverage adhered to a support in such a manner that 30-sec cup sizing degree of 30 g/m<2> or less and further permeability specified according to JIS P 8117 is 40 sec or less. Further, the sheet also comprises surface sizing agent adhered together with the cationic resin to the support.

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 using a water-soluble ink. More specifically, the present invention relates to a plain paper type ink jet recording sheet, and particularly to an ink jet recording sheet which is excellent in water resistance, image density, and feathering of a recorded image and does not change color of a printed portion with the passage of time.

[0002]

2. Description of the Related Art Ink-jet recording is a method in which minute droplets of ink are made to fly and adhere to a recording sheet 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, and is rapidly spreading in various applications as a recording device for various figures including Chinese characters and color images. Further, the image formed by the multi-color inkjet method is
Compared to multi-color printing by the plate making method or printing by the color photographic method, it is possible to obtain a record comparable to that of the printing by the color photograph method. Further, in applications requiring a small number of copies, since it is cheaper than by photographic technology, it is being widely applied to the field of full-color image recording.

As recording sheets used in the ink jet recording system, efforts have been made in terms of apparatuses and ink compositions in order to use high-quality paper and coated paper used for ordinary printing and writing. However, with the improvement of the performance of ink jet recording apparatuses such as high-speed, high-definition and full-color apparatuses, and expansion of applications, more advanced characteristics are also required for recording sheets.

[0004] That is, the recording sheet has a high density of print dots, a bright and vivid color tone, quick absorption of ink, no ink bleeding or bleeding even when the print dots overlap, In terms of high image reproducibility and preservation, such as that the diffusion in the horizontal direction is not unnecessarily large and the periphery is smooth and not blurred (feathering), the condition of high humidity or the printing area may not be sufficient for some reason. It is required that the ink dye does not flow out when exposed to light (image waterfastness) and that the dye does not discolor or fade even when the printed portion is exposed to light (lightfastness).

[0005] In addition to the above characteristics, there is a phenomenon that the color of the ink changes during the drying process on the surface and inside of the ink jet recording sheet. In particular, the phenomenon in which the color tone changes from black to glossy brown in the process of drying the black ink is called "bronze". It is required that the degree of “bronze” be small, especially for a plain paper type ink jet recording sheet.

As the form of the ink jet recording sheet, an ink receiving layer is provided on a support such as a plain paper type represented by a so-called high quality paper or a bond paper, a paper such as a high quality paper, a synthetic paper or a synthetic resin film. Coated paper type.

[0007] coated paper type, coating amount of the ink-receiving layer is about 1 to 10 g / m ² low coating weight type, 10 to 20 g / m ²
There are various types of ink jet recording sheets of a medium coating amount type and a high coating amount type of 20 g / m ² or more.

In particular, in recent years, plain paper type
It is desirable both in appearance and handling, and has been desired. However, at present, these plain paper type ink jet recording sheets do not satisfy the above-described characteristics such as image water resistance, image density, feathering and bronzing.

Several methods have been proposed for improving the water fastness of dyes, for example, JP-A-55-1503.
No. 96 discloses a water-resistant method for forming a dye and a chelate in a water-soluble ink. Further, in order to simultaneously improve the water fastness and light fastness of the dye, JP-A-59-11752 has been proposed.
JP-A-59-1 discloses an example of an ink jet recording sheet containing cationic colloidal silica.
Japanese Patent No. 37652 discloses an example of an ink jet recording sheet containing a basic polyaluminum hydroxide compound, and JP-A-60-11389 discloses an ink jet recording sheet comprising a basic oligomer. Is shown.

However, even when these methods are used, it is known that if the size of the recording sheet is increased to improve feathering, the water resistance of the image is remarkably deteriorated.

According to Japanese Patent Application Laid-Open No. 6-220794, bronzing is a phenomenon that occurs because a part of the dye in the ink aggregates in an oriented form and is not absorbed in the paper layer but precipitates on the paper surface. A method of internally adding a synthetic aluminum silicate or kaolin mineral that adsorbs ammonia or ammonium ions caused by a nitrogen compound serving as a dissolution aid of a dye in an ink is disclosed. However, even with these methods, it is very difficult to balance image density, degree of discoloration, and feathering.

[0012]

As described above, in the case of a plain paper type ink jet recording sheet, at present, sufficient image water resistance, image density, feathering and discoloration are not satisfied.

An object of the present invention is to satisfy the following problems in a plain paper type ink jet recording sheet. 1. Image water resistance that prevents ink from bleeding even in a highly humid atmosphere or when water droplets adhere. 2. High image density. 3. Good character quality (feathering). 4. The degree of discoloration (bronze) should be small.

[0014]

Means for Solving the Problems The present inventors have made intensive studies in view of the above, and as a result, have invented an ink jet recording sheet having good water resistance, image density and feathering of a recorded image and little discoloration. Reached.

That is, in the ink jet recording sheet of the present invention, the cationic resin is added to the support in a dry adhesion amount of 0.1%.
2 g / m ² or more, and the cob size degree for 30 seconds is 30 g / m ² or less, and the air permeability specified in JIS P8117 is 40 seconds or less. .

Furthermore, the present invention is characterized in that a surface sizing agent is adhered to a support together with a cationic resin.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an ink jet recording sheet of the present invention will be described in detail.

In order to improve the image water resistance of a water-soluble ink containing a direct dye or an acid dye used in an ink jet recording system, the dye is fixed by a reaction between an anionic part of the dye and a cationic substance, and a water-resistant treatment is performed. Is self-evident. From the viewpoint of improving the image density and feathering, it is desirable to increase the size of the recording sheet. However, if the size is extremely increased, the ink overflows without being absorbed by the recording sheet. Will not be able to withstand use. Further, it has been found that even when the sizing property is applied to such an extent that no ink overflow occurs, the water resistance of the image deteriorates with the improvement of the sizing property. With the improvement in size, the cause of the deterioration of image water resistance is that the dye in the printed ink is more likely to stay on the paper surface, not inside the paper layer, and the water used for the image water resistance evaluation is absorbed. It is considered that the water is exposed to the print site for a long time.

That is, in the prior art, in order to obtain sufficient image water resistance in a plain paper type ink jet recording sheet, it was necessary to reduce the size of the sheet. As a result, the image density and feathering are reduced.

As described above, the mechanism of bronzing is that a part of the dye in the ink is aggregated in an oriented form and is not absorbed in the paper layer, but precipitates on the paper surface.
In particular, it is considered that the black printed portion looks brown.

Therefore, when the size is increased to satisfy the image density and feathering, not only the water resistance of the image but also the bronzing deteriorates. In order to suppress bronzing, it is necessary to increase the absorbability of the ink in the paper layer.

The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, by adjusting the amount of the cationic resin adhered, the degree of cobb size and the air permeability of the paper to specific ranges, the cationic surface sizing agent was further improved. It has been found that the combination of the above makes it possible to achieve both of the above characteristics.

It is considered that means for achieving an appropriate size of the ink jet recording sheet, in other words, an appropriate ink absorption, can be roughly divided into two methods. One method is to change the amount of the internal sizing agent used for the ink jet recording sheet or the amount of the surface sizing agent attached. In this method, the permeability of the ink is controlled by the wettability between the ink for ink jet recording and pulp fibers mainly constituting the ink jet recording sheet.

The method of controlling the wettability between the ink and the pulp fiber depends on the change in the amount of the internal sizing agent or the surface sizing agent as described above. For example, even when the sizing degree of the completed recording sheets is the same, The balance of the ink jet characteristics is better when the surface sizing agent is used in combination than when only the internal sizing agent is used.

That is, when the surface sizing agent is used in combination, the sizing property on the surface of the sheet is higher and the sizing property inside the sheet is relatively low, so that the ink printed on the sheet surface does not bleed in the horizontal direction and is excellent. This is because the ink exhibiting excellent feathering characteristics and remaining on the sheet surface is quickly absorbed into the inside of the low-size sheet after a very short elapsed time.

Another method is to change the void structure of the paper. The Lucas-Washburn equation is well known as a model equation of liquid permeation into a capillary, in which the liquid penetration depth is
It has been shown to be proportional to the square root of time and capillary radius and inversely proportional to the square root of the viscosity of a liquid.

As described above, the porous structure of the paper has a great influence on the penetration of the liquid, and one measure of the degree of the porous structure of the paper is air permeability. The present inventors have studied the relationship between the size of the paper, the air permeability and the above-mentioned properties, which is a problem, and as a result, the higher the air permeability, the better the image water resistance, the better the bronzing, and the image density, It has been found that even with paper having an appropriate degree of sizing with good feathering, the higher the air permeability, the better the image water resistance and bronzing.

By improving the air permeability in this way, the penetration of the ink into the ink jet recording sheet at the beginning of printing is promoted. By promoting the penetration of the ink in the thickness direction, a certain amount of ink ejected from the nozzles of the inkjet printer can be brought into contact with a wider pulp fiber surface or pigment surface in the paper layer of the inkjet recording sheet. It is considered that the precipitation of the dye during the drying process of the ink can be reduced. Similarly, by promoting the penetration of the ink, the chance of contact with the cationic resin in the paper layer increases, so that it is considered that the water resistance of the image is also improved.

Means for increasing the air permeability of the ink jet recording sheet include increasing the freeness of the pulp used when making the ink jet recording sheet;
This can be achieved by means of a single or a combination of means such as setting a low linear pressure in a wet press and suppressing the amount of liquid adhered in a size press to such an extent that printability is not impaired.

The 30-second cobb size is preferably as small as 30 g / m ² or less in order to obtain good image density and feathering. However, considering the balance between image water resistance and bronzing, it is 10 to 25 g. / m ² is preferred.

The dry adhesion amount of the cationic resin is 0.2 g
/ M ² or more, but preferably 0.5 to 2.0 g /
a m ^2. If it is less than 0.2 g / m ² , sufficient image water resistance cannot be obtained, and it may be more than 2.0 g / m ^2. It cannot be obtained, which is not preferable in terms of cost.

The cationic resin used in the present invention is a monomer, oligomer or polymer of a primary to tertiary amine or quaternary ammonium salt which dissociates and dissociates when dissolved in water, and is preferably an oligomer or a polymer. It is a polymer. Specifically, dimethylamine / epichlorohydrin polycondensate, acrylamide / diallylamine copolymer, polyvinylamine copolymer, dicyandiamide, dimethyl / diallyl / ammonium chloride and the like can be exemplified, but it is limited to these examples. Not a thing.

As a method for adhering the cationic resin, a size press, a gate roll coater, a blade coater, a rod coater, an air knife coater,
Although it is possible to apply by using a coating machine such as a curtain coater, it is preferable from the viewpoint of cost that the coating be performed by a size press or a gate roll coater installed in the paper machine and finished on-machine.

The surface sizing agent is appropriately used to control the permeability of the ink, and its main components are styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, acrylonitrile / vinyl formal /
Acrylic ester copolymer, styrene / maleic acid copolymer, olefin / maleic acid copolymer, AKD
System, rosin-based surface sizing agents, etc.,
For use with a cationic resin, a cationic surface sizing agent is preferred.

As the support of the ink jet recording sheet of the present invention, a paper-like substance such as a paper mainly composed of wood fibers or a non-woven fabric mainly composed of wood fibers or synthetic fibers can be used. Is NBKP, L
In addition to BKP, NBSP, LBSP, GP, TMP, etc., used paper pulp is used, and used alone or in combination as needed.

The raw materials for waste paper pulp referred to in the present invention include: top white, ruled white, cream white, card, and the like shown in the waste paper standard quality standard table of the Waste Paper Recycling Promotion Center.
Special white, medium white, imitation, fair white, Kent, white art, special top cut,
Another example is newspaper, magazine, etc. Further specific examples include information-related papers such as uncoated computer papers, thermal papers, printer papers such as pressure-sensitive papers, and OA waste papers such as PPC papers, art papers, coated papers, lightly coated papers, matte papers and the like. Coated paper or high quality paper, high quality color, notebook, stationery, wrapping paper, fancy paper, medium quality paper, newsprint,
Waste paper of paper and paperboard, such as uncoated paper such as blank paper, super wrapping paper, imitation paper, pure white roll paper, milk carton, and chemical pulp paper, high yield pulp containing paper, etc. are used.
There is no particular limitation on printing, copying, printing and non-printing.

As the internal filler used for the support, conventionally known pigments are used as white pigments, and they can be used alone or in combination. Examples thereof include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, and the like. Calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, water White inorganic pigments such as magnesium oxide, styrene-based plastic pigments,
Organic pigments such as acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

Further, as the internal sizing agent used for forming the support of the present invention, a rosin sizing agent, an alkenyl succinic anhydride, an alkyl ketene dimer, a petroleum resin sizing agent and the like can be used.

Further, when using a cationic resin,
At the same time, a binder is generally used, and oxidized starch, phosphated starch, self-modified starch, cationized starch or various modified starches, polyethylene oxide, polyacrylamide, sodium polyacrylate, sodium alginate, hydroxymethylcellulose, methylcellulose , Polyvinyl alcohol or derivatives thereof can be used alone or in combination, but in combination with a cationic resin, cationized starch is preferred because it is easy to use.

In the present invention, other additives such as a pigment dispersant, a thickener, a flow improver, an antifoaming agent, a foam inhibitor, a release agent, a foaming agent, a penetrant, Coloring dyes, coloring pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, anti-binders, water-proofing agents, wet paper strength agents, dry paper strength agents, etc. Within the range that does not impair
They can be appropriately blended.

In the papermaking method of the present invention, a paper machine known in the papermaking industry, such as a fourdrinier paper machine, a twin wire paper machine, a combination paper machine, a round mesh paper machine, a Yankee paper machine, can be used as appropriate.

The ink for ink jet recording according to the present invention is a recording liquid comprising the following colorant, 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.

Examples of the solvent for the aqueous ink include 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, and the like. Alkyl alcohols having 1 to 4 carbon atoms 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 and 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
And 6 alkylene glycols; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol and monomethyl ether.

Of 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 preferred.

Other additives include, for example, a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust inhibitor.

The ink-jet recording sheet of the present invention can be used not only as an ink-jet recording sheet but also as any recording sheet using a liquid ink during recording. For example, a heat-fusible substance, a heat-fusible ink containing a dye or a pigment as a main component, is coated on a thin support such as a resin film, high-density paper, or synthetic paper, and heated from the back surface of the ink sheet. Heat transfer recording image-receiving sheet for melting and transferring ink, heat-melting ink for heating and melting into fine droplets, ink jet recording sheet for flight recording, ink jet recording sheet using ink in which oil-soluble dye is dissolved in solvent, light Examples include an image-receiving sheet corresponding to a photosensitive pressure-sensitive donor sheet using microcapsules containing a polymerizable monomer and a colorless or colored dye / pigment.

The common feature 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 until it is cured, solidified or fixed. The above-mentioned various recording sheets require absorptivity according to each system, and there is no limitation even if the inkjet recording sheet of the present invention is used as the above-mentioned various recording sheets.

Further, the ink jet recording sheet of the present invention can be used as a recording sheet for heating and fixing an electrophotographic toner widely used in copying machines and printers.

Further, as an application that has been increasing in recent years, there is a method in which common information is subjected to offset printing in advance and only variable information is inkjet-printed. In these applications, the inkjet recording sheet of the present invention is used. It is also possible.

[0050]

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
Unless indicated otherwise, parts by weight and% by weight are indicated.

Example 1 <Preparation of Support> LBKP (freeness 450 mlcsf) 100 parts Light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo KK) 7 parts Aluminum sulfate 1.0 part Amphoteric starch (trade name) : Cato3210, manufactured by NSC Japan Ltd.) 1.0 part Neutral rosin sizing agent (trade name: NeuSize M-10, manufactured by Harima Chemicals) 0.3 part Yield improver (trade name: NR-11LS, manufactured by Hymo) 0.02 parts A 0.3% slurry having the above composition was formed on a fourdrinier paper machine under the condition that the total linear pressure in a wet press section was 220 kgf / cm, to produce a support having a basis weight of 62 g / m ² .

The support prepared as described above was dried with 1.5 g / m ² of cationized starch (trade name: CATOSIZE270, manufactured by NSC Japan) and cationic resin (trade name: Polyfix 601; Showa High School) (Manufactured by Nippon Kagaku Co., Ltd.) in an amount of 0.
Example 1 was applied by using an on-machine size press device so as to be 8 g / m ² and subjected to machine calendering.
Was prepared.

Example 2 An ink jet recording sheet of Example 2 was prepared in the same manner as in Example 1 except that the dry adhesion amount of the cationic resin of Example 1 was changed to 0.2 g / m ² .

Example 3 Example 1 was repeated except that the total linear pressure in the wet press was changed to 260 kgf / cm in the preparation of the support of Example 1.
In the same manner as in the above, an ink jet recording sheet of Example 3 was produced.

Example 4 An ink jet recording sheet of Example 4 was prepared in the same manner as in Example 1, except that the freeness of LBKP was changed to 490 ml.

Example 5 An ink jet recording sheet of Example 5 was produced in the same manner as in Example 1 except that the freeness of LBKP was changed to 400 ml in the production of the support of Example 1.

Example 6 The procedure of Example 1 was repeated, except that the freeness of LBKP was changed to 490 ml and the neutral rosin size was changed to 0.4 part. Inkjet recording sheet No. 6 was produced.

Example 7 In the preparation of the support of Example 1, 0.2 parts of a neutral rosin sizing agent was added to a cationized starch and a cationic resin, and a surface sizing agent (trade name: ABSOFLAST 265D, BAS)
Example 7 was prepared in the same manner as in Example 1 except that 0.03 g / m ² of the dry adhesion amount (manufactured by Company F) was adhered.

Example 8 In the preparation of the support of Example 1, the freeness of LBKP was set to 490 ml, the neutral rosin sizing agent was set to 0.2 part, and the surface sizing agent was added to the cationized starch and the cationic resin. An ink jet recording sheet of Example 8 was produced in the same manner as in Example 1 except that 0.09 g / m ² of a dry adhesion amount (trade name: ABSOFLAST 265D, manufactured by BASF) was applied.

Example 9 The size press device of Example 1 was changed to a gate roll coater device, and the amount of cationized starch dried was 2.0 g / m ² ,
An ink jet recording sheet of Example 9 was produced in the same manner as in Example 1, except that the dry adhesion amount of the cationic resin was changed to 1.0 g / m ² .

Example 10 Example 1 was repeated except that the cationic resin of Example 1 was changed (trade name: Sumireze Resin 1001, manufactured by Sumitomo Chemical Co., Ltd.).
In the same manner as in the above, an ink jet recording sheet of Example 10 was produced.

Example 11 An ink jet recording sheet of Example 11 was prepared in the same manner as in Example 1 except that the cationic resin of Example 1 was changed (trade name: Himax SC-700, manufactured by Hymo). did.

Comparative Example 1 Except that the cationic resin of Example 1 was not adhered,
In the same manner as in Example 1, an inkjet recording sheet of Comparative Example 1 was produced.

Comparative Example 2 An ink jet recording sheet of Comparative Example 2 was prepared in the same manner as in Example 1, except that the dry adhesion amount of the cationic resin of Example 1 was changed to 0.1 g / m ² .

Comparative Example 3 An ink jet recording sheet of Comparative Example 3 was prepared in the same manner as in Example 1 except that the neutral rosin sizing agent was changed to 0.2 part in the preparation of the support of Example 1.

Comparative Example 4 In the preparation of the support of Example 1, the freeness of LBKP was set to 300 ml, and the total linear pressure of the wet press was set to 26.
An ink jet recording sheet of Comparative Example 4 was produced in the same manner as in Example 1 except that the pressure was 0 kgf / cm.

Comparative Example 5 In the preparation of the support of Example 1, the freeness of LBKP was set to 400 ml, the size press was changed to a gate roll coater, and the dry adhesion amount of the cationized starch was 2.0.
g / m ^2, except that the dry adhering amount of the cationic resin was 1.0 g / m ^2, in the same manner as in Example 1 to prepare an ink jet recording sheet of Comparative Example 5.

With respect to the ink jet recording sheets of Examples 1 to 11 and Comparative Examples 1 to 5 prepared above,
The 0 second cobb size and air permeability were measured.

<30 seconds cobb size degree> 20 ° C., 65%
After conditioning for 24 hours in an environment of RH, the degree of cobb size was measured according to JIS P8140. Measurement solvent (water)
The contact time between the sample and the measurement sample (paper) was 30 seconds, and the measured water absorption was "30 seconds Cobb size degree".

<Air permeability> The humidity was controlled in an environment of 20 ° C. and 65% RH for 24 hours, and measured using a Gurley densometer manufactured by Toyo Seiki Co., Ltd. in accordance with JIS P8117.

Regarding the suitability for inkjet, the inkjet printer BJ-220JS manufactured by Canon Inc. was used.
Was used to print an evaluation image, which was evaluated by the following evaluation method. The results are shown in Table 1.

<Water resistance to image> One drop of distilled water was dropped on the portion where the characters and ruled lines were printed, and after standing to dry, the degree of bleeding was visually determined. As evaluation criteria, A shows good characteristics, B shows good results in practically acceptable range, C shows practical problems, and D shows poor characteristics.

<Image Density> The image density was measured on a solid printed portion using a reflection densitometer (trade name: Macbeth RD-918, manufactured by Macbeth). A higher value indicates better characteristics, and a value of 1.30 or more indicates no problem at all.

<Feathering> The degree of bleeding (the degree of jaggedness) of ink in the portion where characters and ruled lines were printed was visually determined. As evaluation criteria, A has good characteristics and B has good characteristics.
Is good as long as there is no practical problem, C is practically problematic, and D
Indicates poor characteristics.

<Bronzing> For bronzing, the solid printed portion was measured for L ^* a ^* b ^* using a colorimeter (trade name: CR-200, manufactured by Minolta Co., Ltd.). The degree of bronzing was represented by a chromaticness index a ^* . Normal,
At a glance, discoloration (redness) is felt when a ^* is 2.5 or more. That is, less than 2.5 indicates that there is no practical problem.

[0076]

[Table 1]

As is clear from the above results, it is understood that a cationic resin having a dry adhesion amount of 0.2 g / m ² or more is required to obtain good image water resistance. It is also found that when the cob size degree for 30 seconds is 30 g / m ² or less and the air permeability satisfies the condition for 40 seconds or less, each characteristic becomes good.

Further, when the surface sizing agent is used in combination with the cationic resin, it is apparent that each characteristic becomes the best.

[0079]

From the above results, the ink jet recording sheet of the present invention has a specific condition, that is, the dry adhesion amount of the cationic resin is 0.2 g / m ² or more, and the cob size degree for 30 seconds is 30 g / m ^2. Hereinafter, by achieving an air permeability of 40 seconds or less, and further by using a surface sizing agent together with a cationic resin, excellent image water resistance, image density, feathering, and little discoloration due to aging are obtained. It has inkjet suitability.

Claims (2)

[Claims] Claims: 1. A cationic resin is adhered to a support in an amount of 0.2 g / m ² or more as a dry adhesion amount, and a 30-second cobb size degree is 30 g / m ² or less.
7. A plain paper type ink jet recording sheet, wherein the air permeability specified in 7 is 40 seconds or less. 2. The plain paper type ink jet recording sheet according to claim 1, wherein a surface sizing agent is adhered to a support together with a cationic resin.