JPH11301092A - Ink jet recording medium - Google Patents

Abstract

(57) [Problem] To provide an ink jet recording sheet which has little curl change due to environment, has high gloss, and is suitable for printing a full-color image. SOLUTION: An ink receiving layer containing at least one kind of ink-absorbing resin selected from polyvinylpyrrolidone, polyvinyl alcohols and cellulose derivatives and a plasticizer is provided on a sheet-like support in which both sides of a base paper are coated with a resin. Ink jet recording medium.

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 medium, and more particularly to an ink-jet recording medium in which curl change due to the environment is small and excellent image quality can be obtained.

[0002]

2. Description of the Related Art An ink-jet recording system in which an aqueous ink is ejected from a fine nozzle onto a recording medium to form an image,
Terminal printers, facsimile machines, plotters, form printing, etc., because there is little noise during recording, color printing is easy, high-speed recording is possible, and it is cheaper than other printing devices. Widely used in Until now, high-quality paper and ink-coated paper with a porous pigment applied to the surface have been used as inkjet recording paper, and many of these have a so-called matte tone with low surface gloss. However, with the rapid spread of inkjet printers and high image quality,
Inkjet papers with high surface gloss and photographic image quality have been demanded.

[0003] One side of a paper substrate has an ink-absorbing resin,
Alternatively, a sheet having an ink receiving layer made of various pigments, a water-soluble resin, various latexes, etc., and having a smooth surface by a super calender treatment or the like is used as necessary. However, such an inkjet recording sheet has a problem that high gloss cannot be obtained because the flatness of the paper substrate is poor, or the ink droplets absorb ink droplets during printing and swell to produce irregularities. was there. In order to compensate for the drawbacks of the paper substrate, an ink-receiving layer made of an ink-absorbing resin such as starch, gelatin, a water-soluble cellulose derivative, polyvinyl alcohol, and polyvinylpyrrolidone is formed on a glossy plastic film such as polyethylene terephthalate or polyester. It has been proposed to provide them (JP-A-59-174381, JP-A-60-92949, JP-A-60-132785).
JP, JP-A-60-145879, JP-A-60-145879
-220750, JP-A-60-224578, JP-A-61-32788, U.S. Pat.
111, U.S. Pat. No. 4,592,954). But,
A recording medium in which an ink-absorbing resin layer is provided on a film or paper base is likely to warp (curl) toward the receiving layer due to a change in humidity to low humidity, and not only impairs the appearance of the recording medium,
When recording is performed, there is a problem that the printer head comes into contact with the recording medium and stains the recording medium, and normal feeding and discharging of the recording apparatus becomes impossible.

In order to suppress curling, it is possible to suppress curling to some extent by increasing the rigidity of the sheet-like support to be used, but the completed ink jet recording sheet is thick and impractical. Alternatively, there is a disadvantage such as an increase in cost. In order to solve this problem, the following attempts have been made with an ink jet recording medium using a plastic film or a paper base, but although it is solved to some extent, it is an object without impairing the image quality, glossiness, and moisture resistance. A recording medium with little change in curl due to humidity change cannot be obtained.

JP-A-62-220383 discloses a printing sheet containing a plasticizer in an ink-absorbing polymer resin layer, and JP-A-2-270589 discloses a transparent sheet or paper containing a hydrophilic coating and a plasticizer. JP-A-2-2
No. 08366 discloses a transparent composition comprising a mixture of at least one water-absorbing, hydrophilic polymer substance and at least one hydrophobic polymer substance having acid functionality, and at least one or more polyethylene glycols. In Japanese Patent Application Laid-Open No. Sho 61-162381, a transparent composition for graphic arts having a haze of 15% or less as measured according to 1003-61 is applied to a recording material comprising a substrate and an ink receiving layer by applying a tensile load of 1 g. The difference between the expansion and contraction rate of the substrate and the ink receiving layer when applied is 20 ° C., 65
% RH and 5% under conditions of 20 ° C. and 30% RH, respectively.
A recording material for inkjet recording characterized by the following is disclosed. However, curling adjustment requires a large amount of plasticizer addition, and as a result, there are inconveniences such as stickyness and fogging of the receiving layer and bleeding of printed matter, and the curl adjustment is performed without impairing the image quality. Was difficult.

On the other hand, it has been proposed to provide an ink-receiving layer made of an ink-absorbing resin on a base paper coated with a polyolefin resin at least on the side of the base paper coated with the receiving layer (JP-A-4-216990, JP-A-7-25133). , JP-A-7
-179032), there is no decrease in glossiness due to unevenness such as a paper substrate, and an image quality similar to that of an ink jet recording medium using a film as a substrate can be obtained, and the cost is lower than that of a film. Furthermore, the base material coated with polyolefin resin has a sandwich-like multilayer structure in which the base paper is sandwiched between resin laminate layers, and curling can be controlled to some extent by balancing the materials and coating amounts of the front and back laminate layers. It is. In other words, by using the difference in the crystallinity of the polyolefin, the resin density of the polyolefin on the front side and the back side is selected, or by changing the coating amount on the front side and the back side, the curl change in the curl size and humidity change can be reduced. Can operate. However, in an environment with large changes in humidity,
It was difficult to solve the problem only by designing the laminate layer.

In Japanese Patent Application Laid-Open No. 8-269900, paper having natural image pulp as a main component is used as a substrate, and one side of the paper substrate on which an image forming layer is provided is coated with a resin (A) having film forming ability. An image forming support, which is used by being wound into a roll having the opposite side of the paper substrate coated with a polyolefin resin, wherein the side on which the image forming layer of the image forming support is provided is externally wound; It discloses a support for an image material characterized by being stored at a temperature of at least ℃. However, simply storing a sheet-like support coated with a polyolefin resin at a specific temperature and making it curl,
Even in a certain environment, even if a desired curl is obtained, it is difficult to suppress the curl generated by a change in the use environment.

JP-A-6-171206 discloses an ink jet recording sheet having at least one or more ink-receiving layers on the surface of a support and at least one or more backcoat layers on the back surface. Discloses an ink-jet recording sheet comprising a pigment and a binder as main components, and having an average equilibrium water content of the pigment of 1.9 to 5.5%. As the support, wood pulp such as chemical pulp, mechanical pulp, waste paper pulp and the like, and base paper manufactured using a conventionally known pigment as a main component, coated paper provided with a polyolefin resin layer on base paper, and various films are used. The back layer is composed of a pigment and a binder, for example, light calcium carbonate, heavy calcium carbonate, kaolin, various pigments such as talc, and a binder such as polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, carboxymethyl cellulose, It is appropriately selected from various binders such as cellulose derivatives such as hydroxyethyl cellulose. However, the back layer containing a pigment and a binder as main components has a disadvantage that the curl suppressing effect is small, and if a sufficient effect is to be obtained, the coating film needs to be excessively thick.

Japanese Patent Application Laid-Open No. 5-286228 discloses a recording sheet having a dye-adsorbing layer provided on a substrate, and a swellable polymer layer provided on the opposite side of the surface of the substrate on which the dye-adsorbing layer is provided. A provided recording sheet is disclosed. As a substrate,
Polyester resin such as polyethylene terephthalate, polyester diacetate, polycarbonate resin,
Various plastic sheets such as fluorinated resins such as ETFF are used. Examples of the material of the swellable polymer layer include polyvinyl alcohol, polyvinylpyrrolidone, and a blend thereof. However, this method has a disadvantage that manufacturing cost is added, and polyvinyl alcohol and polyvinylpyrrolidone, etc., show adhesiveness when absorbing moisture. Adhesion is easy to occur. Further, there is a problem that the method is not effective when the moisture content is different on both sides of the recording medium, such as receiving heat from one surface.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an ink jet recording medium which can obtain excellent image quality and has less curl change due to environment.

[0011]

According to the present invention, at least one kind of an ink-absorbing resin selected from polyvinylpyrrolidone, polyvinyl alcohols and a cellulose derivative and a plasticizer are coated on a sheet-like support having both sides of a base paper coated with a resin. It is an ink jet recording medium provided with an ink receiving layer to be contained. According to the present invention, an ink-jet recording material that can obtain excellent image quality and has less curl change due to environment can be obtained. Further, when the plasticizer is polyglycol having a molecular weight of 200 or more and 1000 or less, the image quality is further improved. Preferably it has a molecular weight of 200 to 800, more preferably 200 to 600. The present invention discloses the above ink jet recording medium, wherein the ink receiving layer contains 1 to 10 parts by weight of a plasticizer based on 100 parts by weight of the ink absorbing resin. Further, the present invention discloses the above-mentioned ink jet recording medium, wherein the ink receiving layer contains a cationic resin.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The recording medium of the present invention comprises a support which is a resin-coated paper and a receiving layer mainly composed of an ink-absorbing resin. Ink absorbing resins used in the receiving layer include polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol, polyvinyl pyrrolidone (including derivatives and copolymers), carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, and hydroxy. Contains cellulose derivatives such as propylmethylcellulose. Thereby, excellent image quality is obtained. Particularly, polyvinylpyrrolidone (homopolymer), polyvinyl alcohols and hydroxypropylmethylcellulose are preferable. As the ink absorbing resin, a natural resin such as gelatin, casein, starch and cationic starch, a water-soluble resin such as sodium polyacrylate, and a synthetic resin such as polyurethane and polyester can be appropriately added.

The plasticizer mixed with the ink-absorbing resin is an additive that can be mixed with the ink-absorbing resin to improve its flexibility. Examples of such a plasticizer include phosphate esters such as tributyl phosphate, phthalate esters such as dibutyl phthalate, aliphatic esters such as di-2-hexyl adipate, epoxy aliphatic esters, and acetyl tributyl citrate. And polyhydric alcohols such as polyethylene glycol and glycerin, and esters or ethers thereof. Particularly preferred plasticizers contained in the ink receiving layer include polyglycols such as polyethylene glycol, polypropylene glycol and polyoxytetramethylene glycol, and glycerin. The molecular weight of polyglycol is more preferably 200 or more and 1000 or less. If it is less than 200, the printed matter tends to bleed out with time, and if it exceeds 1,000, the receiving layer may become cloudy and the gloss may be poor. The amount of the plasticizer added is preferably 1 to 10 parts by weight, more preferably 2 to 8 parts by weight, based on 100 parts by weight of the ink absorbing resin. If the addition amount is large, there is a possibility that the surface becomes sticky.

In the present invention, it is preferable that a cationic resin which forms an insoluble salt with a sulfone group, a carboxyl group, or the like of the inkjet ink is added to the receiving layer for the purpose of imparting ink fixability. . The type of the cationic resin is not particularly limited, and known polyethyleneimine, polyvinylpyridine, polyvinylamine, a polymer of monoallylamine hydrochloride, a polymer of diallylamine hydrochloride, and a polymer of monoallylamine hydrochloride-diallylamine hydrochloride Examples thereof include copolymers, polymers of (meth) acrylamidoalkyl quaternary ammonium salts, polyalkylenepolyamine / dicyandiamide condensates, secondary amine / epichlorohydrin addition polymers, and compounds such as polyepoxyamine.

The amount of the cationic resin is from 1 to 30 parts by weight, preferably from 1 to 10 parts by weight, per 100 parts by weight of the ink absorbing resin. If the amount is less than 1 part by weight, a sufficient water resistance improving effect cannot be obtained, and if the amount is more than 30 parts by weight, there is a possibility that the ink drying property may deteriorate. In the coating composition constituting the ink receiving layer of the present invention, a polyolefin resin, a urethane resin, an acrylic resin, and a polyester for the purpose of improving the water resistance of the coating film of the receiving layer within a range that does not impair the effects of the invention. Resins, resin emulsions such as vinyl acetate resins and various latexes can also be blended. Further, various inorganic or organic pigments and particles can be added for the purpose of adjusting gloss and transparency of the recording sheet and preventing blocking. Examples of inorganic pigments include silica, clay, talc, calcium carbonate, aluminum silicate, zeolite, and alumina.Examples of organic pigments and particles include various plastic particles such as styrene resin, acrylic resin, and urethane resin, and cellulose fine particles. Examples include powder and starch particles. The amount of addition is not particularly limited, but is about 10 parts by weight or less based on 100 parts by weight of the ink absorbing resin.

Further, in the coating composition constituting the ink receiving layer of the present invention, a dispersant, a crosslinking agent, a thickener, a defoamer,
Various assistants such as a wetting agent, a fluorescent dye, a coloring agent, an antistatic agent, a preservative, and an ultraviolet absorber are appropriately added as needed.

The support used in the present invention has a thickness of the base paper.
Is not particularly limited, but should be 30 μm to 500 μm
Is preferred. Thinner than 30μm for inkjet recording
The rigidity of the seat is low and the feel and texture when picked up
Or inconvenience such as a decrease in opacity. Also 5
If it is thicker than 00 μm, it becomes rigid and difficult to handle.
May cause trouble during paper feeding.
You. A more preferred range is 50 μm to 300 μm. Ma
The weight of the base paper is not particularly limited, but is 30 g / m. ^Two~ 5
00g / m^TwoIs preferably within the range. Base paper is wood
It is a pulp sheet composed mainly of pulp.
As wood pulp, chemical powders such as LBKP and NBKP
Loop, GP, PGW, RMP, TMP, CTMP, CM
Mechanical pulp such as P and CGP, waste paper pulp such as DIP
And various pulp. In addition, as needed
Various known papermaking additives can also be blended.
You. As papermaking additives, various papermaking pigments, binders
ー, sizing agent, fixing agent, yield improver, cationization
Agent, dry paper strength agent, wet paper strength agent, pH adjuster,
Examples include an electric agent, a dye, and the like.
Two or more types can be blended. As a paper machine,
Well-known Fourdrinier paper machine, cylindrical paper machine, twin wire paper machine
Which can be used. In addition, acid, neutral, alkaline
Paper making with this may be used.

The base paper can be subjected to a tab size or size press with starch or polyvinyl alcohol or a surface smoothness treatment such as a machine calender, a heat calender, a soft calender or a super calender, following the paper making. The resin coating layer is formed by melt-coating a resin composition containing a polyolefin resin or the like as a main component and a white pigment and various additives as necessary (resin laminate layer). As polyolefin resin,
Homopolymers and copolymers such as ethylene and propylene are exemplified, and one or more of these can be used as a mixture. Among them, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene are preferable because of good workability and easy availability. Although the physical properties of the polyolefin resin are not particularly limited, from the viewpoint of processing suitability and curling suitability,
Molecular weight 20,000-200,000, density 0.9
15 to 0.950 g / m3, melt index is 2
It is preferably in the range of 40 g / 10 min (JIS
K-6760).

Further, a white pigment and various additives can be blended in the polyolefin resin coating layer. Above all, it is preferable to mix a white pigment in the polyolefin resin coating layer on the front side in order to increase whiteness and opacity. Examples of the white pigment include anatase-type white titanium, rutile-type titanium dioxide, zinc oxide, calcium carbonate, talc and the like, and one type or a mixture of two types can be used. The blending amount of the white pigment is 0.1 to 30 parts by weight based on 100 parts by weight of the polyolefin resin. When the amount is less than 0.1 part by weight, the effect of increasing whiteness and opacity is small, and exceeds 30 parts by weight. And dispersion in the olefin resin becomes difficult. The preferred range is 1 part by weight to 1 part by weight.
5 parts by weight. Examples of the additives include white pigments, colored pigments, dyes, optical brighteners, antioxidants, plasticizers, and dispersants. Mixing of polyolefin resin and white pigments and additives, extruder for kneading,
This is performed using a heating roll kneader, a Banbury mixer, a pressure kneader, or the like.

The polyolefin resin coating layer is formed by a melt extrusion coating method. That is, the polyolefin resin composition is cast on a running base paper from a slit die into a film by using a melt extruder and coated. At that time, the temperature of the molten film varies depending on the type of the resin, but is generally from 200C to 350C. As the slit die, a flat die is preferable for a T-type die, an L-type die, and a fish-type die, and the opening diameter of the slit is 0.1.
It is desirably about 2 mm. Further, using a cooling roll having a highly smooth surface such as a mirror-finished surface as a cooling roll for cooling the front side molten resin film is effective for increasing the gloss of the inkjet recording sheet. It is preferable to use a cooling roll having a roughened surface as a cooling roll for cooling the molten resin film on the back side.

The coating amount of the polyolefin resin coating layer is 5 g / m ^{2 to} 50 g on each of the front and back surfaces of the substrate.
/ M ² . If the amount is less than 5 g / m ² , the adhesion to the base paper may be insufficient. If the amount is more than 50 g / m ² , the sheet-like support becomes thick and disadvantages such as unnecessarily raising the cost arise. The preferred range is 10 g / m ^{2 to} 30 g.
/ M ² . The selection of the type and the amount of the polyolefin resin to coat the surface of the base paper is an important factor for preventing curling from occurring not only in a standard environment but also in an environment having a relatively low humidity. In the case of resin-coated paper, instead of a substrate having a single-layer structure such as a film or paper, curling of the substrate can be controlled to some extent by balancing the materials of the front and back laminate layers and the amount of coating. In other words, using the difference in the crystallinity of polyolefin, the resin density of the polyolefin on the front side and the back side is selected, or the curl change in the humidity change to low humidity is controlled by increasing the thickness of the laminate layer on the back side. it can.

The ink receiving layer of the present invention can be applied directly on a sheet-like base material. However, in order to improve the adhesion to the sheet-like base material, the surface of the ink-receiving layer is subjected to a corona discharge treatment or a flame treatment. An activation treatment may be performed or an undercoat layer may be provided. The coating composition for an ink receiving layer composed of the above materials is prepared by various known coating methods.
For example, it is coated and dried on a support by various known and publicly-known coating apparatuses such as a bar coater, a blade coater, an air knife coater, a roll coater, a gravure coater, a curtain coater, and a die coater.

The coating amount of the ink receiving layer is determined by the desired printability (for example, ink absorption, ink drying, dye coloring,
There is no limitation as long as it can obtain bleeding, print density, sharpness, etc., but the dry weight is preferably ² to 50 g / m ² , more preferably 5 to 30 g / m ² . When the amount is less than 2 g / m ² , the ink absorption tends to be insufficient, and the ink tends to bleed or dry slowly. If it exceeds 50 g / m ² , not only the obtained effect is saturated, but also disadvantages such as disadvantageous in cost and difficulty in controlling curl occur. The surface gloss is preferably 70% or more, more preferably 80% or more, and most preferably 85% or more from the viewpoint of image quality, appearance, and the like.

[0024]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. Example 1 Production of base paper Softwood bleached kraft pulp (NBKP, Canadian Standard Freeness (JIS P-8121) 250 m)
l) and hardwood bleached kraft pulp (LBKP, Canadian Standard Freeness 280 ml) in a weight ratio of 2:
The mixture was mixed at a ratio of 8 to prepare a pulp slurry having a concentration of 0.5%. The following papermaking additives are added to this pulp slurry,
The following addition amount was blended with the absolute dry weight of the pulp, and the mixture was sufficiently stirred and dispersed. The pH was adjusted to 7.5 by adding 2.0% of cationized starch, 0.4% of alkyl ketene dimer, 0.1% of anionized polyacrylamide resin, 0.7% of polyamide polyamine epichlorohydrin resin and aqueous sodium hydroxide solution. .

The pulp slurry having the above composition is machined with a fourdrinier machine.
Paper making, dryer, size press, machine calendar
Through, the basis weight 180g / m^Two, Tension 1.0g / cm^Three,
A pulp paper having a water content of 7.5% was produced and used as a substrate.
The composition of the size press liquid is as follows. Carboxy
2 parts by weight of modified polyvinyl alcohol, sodium chloride
1 part by weight. The size press solution concentration was adjusted to 5% and this
The liquid is applied to both sides of the paper at a coating amount of 25 g / m ^TwoApply to become
did.

Coating of Polyolefin Resin Coating Layer After applying corona discharge treatment to both front and back surfaces of the pulp paper, the following polyolefin resin coating layer composition 1 mixed and dispersed by a Banbury mixer is added to the pulp paper on the wire side. The olefin resin composition 2 was coated on the felt side (front side) with a coating amount of 25 g / m ² so that the coating amount was 30 g / m ² on the (back side). Coating was performed with an extruder (melting temperature: 280 ° C.). Polyolefin resin coating layer 1 65 parts by weight of high density polyethylene resin (density 0.945, melt index 20 g / 10 min), 35 parts by weight of low density polyethylene resin (density 0.914, melt index 4 g / 10 min). Polyolefin resin composition 2 35 parts by weight of a linear low-density polyethylene resin (density 0.926, melt index 20 g / 10 min),
50 parts by weight of low-density polyethylene resin (density 0.919, melt index 2 g / 10 min), anatase type titanium dioxide (trade name: A-220, manufactured by Ishihara Sangyo)
10 parts by weight, zinc stearate 0.1 part by weight, an antioxidant (trade name: Irganox 101, manufactured by Ciba-Geigy)
0) 0.03 parts by weight, ultramarine (manufactured by Daiichi Kasei, trademark: Aoguchi ultramarine No. 2000) 0.09 parts by weight, fluorescent whitening agent (manufactured by Ciba Geigy, trademark: UVITEX OB)
3 parts by weight. In the lamination coating on the front side (the side coated with the polyolefin resin composition 2), a cooling roll having a chrome-plated mirror-finished surface was used.

[0027] incidentally coating of the ink receiving layer, after subjected to a surface activation treatment by corona treatment on the surface of the front polyolefin resin coating layer, the coating amount after drying of the ink receiving layer coating solution having the following composition is 12 g / m ²
And dried with a bar coater. Coating solution for ink receiving layer: aqueous solution having a coating solution concentration of 15% Polyvinyl pyrrolidone (K-9)
0, ISP) 80 parts by weight, polyvinyl alcohol (P
VA105, manufactured by Kuraray Co., Ltd.), 20 parts by weight, monoallylamine hydrochloride-diallylamine hydrochloride copolymer (trade name: PAA-D11, manufactured by Nitto Bo) as a cationic resin, 3 parts by weight, polyethylene glycol having a molecular weight of 400 as a plasticizer 5 parts by weight, amorphous silica (trade name: Mizukasil P78F, manufactured by Mizusawa Chemicals) 1 as a blocking inhibitor
Department.

Example 2 Production of base paper A base paper was produced in the same manner as in Example 1 except that the basis weight was changed to 105 g / m ² . The coating amount of the polyolefin resin coating layer is 15 g / m ^{2 on} the front side, and 18 g / m ^{2 on} the back side.
A polyolefin resin coating layer was provided in the same manner as in Example 1 except that the thickness was changed to m ² . Coating of ink receiving layer In the coating liquid for the ink receiving layer of Example 1, 100 parts by weight of the ink absorbing resin was polyvinyl alcohol (PVA420, manufactured by Kuraray), and the cationic resin was an acrylamide diallylamine copolymer (Sumireze resin 1001, An ink jet recording material was obtained in the same manner as in Example 1 except that 5 parts by weight of Sumitomo Chemical Industries, Ltd.) and 1.5 parts by weight of the plasticizer were used.

Example 3 In the ink receiving layer coating liquid of Example 1, the ink-absorbing resin was hydroxypropylcellulose (60SH15,
An ink jet recording material was obtained in the same manner as in Example 1, except that 100 parts by weight of Shin-Etsu Chemical Co., Ltd., 9 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries) and 18 g / m ² of the coating amount were used. Was. Example 4 In the coating liquid for an ink receiving layer of Example 1, the cationic resin was replaced with a secondary amine / epichlorohydrin addition polymer (PA).
(L-2, manufactured by Senka) An ink jet recording material was obtained in the same manner as in Example 1, except that 1 part by weight of the plasticizer was replaced with triethylene glycol (molecular weight: 150, manufactured by Wako Pure Chemical Industries, Ltd.).

Example 5 In the ink receiving layer coating liquid of Example 1, the ink-absorbing resin was hydroxypropylmethylcellulose (60SH).
50, manufactured by Shin-Etsu Chemical Co., Ltd.), and an ink jet recording material was obtained in the same manner as in Example 1 except that the plasticizer was replaced by polyethylene glycol having a molecular weight of 1,000 (manufactured by Wako Pure Chemical Industries).

Comparative Example 1 An ink jet recording material was obtained in the same manner as in Example 1 except that the substrate of Example 1 was changed to a polyethylene terephthalate film. Comparative Example 2 The base material of Example 1 was a polyethylene terephthalate film, and the compounding part of the plasticizer was 1 in the ink receiving layer coating liquid.
An ink jet recording material was obtained in the same manner as in Example 1 except that the weight was changed to 5 parts.

Comparative Example 3 The base material of Example 1 was a polyethylene terephthalate film, and a plasticizer was used as a plasticizer in the ink receiving layer coating liquid.
An ink jet recording material was obtained in the same manner as in Example 1, except that the polyethylene glycol (Wako Pure Chemical Industries, Ltd.) was changed to 14 parts by weight. Comparative Example 4 Ink coating resin (polyvinyl pyrrolidone and polyvinyl alcohol) in the coating liquid for the ink receiving layer of Example 1.
Is modified polyester resin (NS-63P, manufactured by Takamatsu Yushi)
An ink jet recording material was obtained in the same manner as in Example 1 except that the amount was changed to 100 parts by weight.

Example 6 An ink jet recording material was obtained in the same manner as in Example 1 except that the compounding part of the plasticizer was changed to 12 parts by weight in the coating liquid for the ink receiving layer of Example 1.

[Evaluation] The ink jet recording sheets of the respective examples and comparative examples produced in the above steps were evaluated by the following methods. (1) Curl The finished ink jet recording sheet is cut into A4 size sheets, placed on a flat table, and placed in the following environment for 5 minutes each.
After adjusting the humidity for 4 hours, measure the lifting height of the four corners and measure
The average of the corners was calculated to be a curl. The convex shape with the receiving layer surface facing upward is called a back curl, and the concave shape is called a top curl. The curl is good in the range of the top 1 mm to the back 10 mm. Environment: normal temperature and normal humidity 20 ° C 60% RH, low temperature and low humidity 10 ° C
20% RH, high temperature and high humidity 40 ° C 85% RH

(2) Gloss The gloss (75-degree gloss) of the surface of the receiving layer of the completed ink jet recording sheet was measured according to JIS-P8142. (3) Bleed Ink-jet plotter NOVAJET. PRO (E
Printing was performed using GA ink (manufactured by NCAD), and the clarity of the solid printed boundary between yellow and red was visually determined. ：: Excellent level without bleeding. ^-- : Good level with almost no bleeding. Δ: Slight bleeding, but not practically problematic. X: A level at which bleeding is conspicuous and poses a practical problem.

(4) Stickiness The surface of the receiving layer of the completed ink jet recording medium is 30
It was left for 24 hours in an atmosphere at a temperature of 80 ° C. and a relative humidity of 80%, and the printed portion was judged by touching with a finger. ：: No sticky feeling. ^-- : There is almost no sticky feeling. Δ: Slightly sticky. X: Stickiness is strong and there is a problem in practical use. Table 1 shows the measurement results.

[0037]

[Table 1]

As can be seen from Table 1, the curl of the ink jet recording medium of the present invention is the top one not only in a normal humidity environment but also in a low humidity environment or a high humidity environment.
mm to a back of 10 mm, which was a good range. In addition, the glossiness showed a good value of 90% or more, and good ink jet recording media for printing a full-color image were obtained (Examples 1 to 6). In particular, Examples 1 and 2 using polyethylene glycol having a molecular weight of 400 were excellent in both curl and image quality. On the other hand, when the polyethylene terephthalate film is used as the base material, the curl suppressing effect is insufficient, and in a low humidity environment, the curl is reduced to a top curl of 30.
mm, the appearance was poor, and the paper feed running during printing was a cause of failure (Comparative Example 1). Alternatively, when a large amount of a plasticizer was contained, the curl was barely usable, but the stickiness and bleeding deteriorated (Comparative Example 2), and the glossiness decreased (Comparative Example 3). Was not. In Comparative Example 4 using an ink-absorbing resin other than polyvinylpyrrolidone, polyvinyl alcohol and a cellulose derivative, the ink bleeding was insufficient, so that the printing bleeding deteriorated and satisfactory image quality was not obtained.

[0039]

As described above, the curl is small, the appearance and the paper feeding / discharging properties of the printer can be improved not only in a normal humidity and normal temperature environment but also in a low humidity environment and a high humidity environment. An inkjet recording medium suitable for printing a full-color image with high glossiness could be submitted. In the present invention, even if the environment changes, curl is not caused, the appearance is not deteriorated, or printing does not become inconvenient when printing, and a high gloss and high quality ink jet recording sheet can be obtained.

Claims (4)

[Claims] 1. An ink receiving layer containing at least one ink-absorbing resin selected from polyvinylpyrrolidone, polyvinyl alcohols and a cellulose derivative and a plasticizer are provided on a sheet-like support in which both sides of a base paper are coated with a resin. Inkjet recording. 2. The ink receiving layer according to claim 1, wherein the ink absorbing layer comprises
The ink jet recording material according to claim 1, wherein the plasticizer is contained in an amount of 1 part by weight or more and 10 parts by weight or less based on 0 part by weight. 3. The ink jet recording material according to claim 1, wherein the plasticizer is a polyglycol having a molecular weight of 200 to 1,000. 4. The ink jet recording material according to claim 1, wherein the ink receiving layer contains a cationic resin.