JP2008296465A - Recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording sheet which can record a high quality image excellent in ink absorption, color development, and coating film water resistance, reduces decoloration of the unrecorded area due to aging also even when exhibited in the environment with high temperature and high humidity or outdoors, and further controls generation of formaldehyde. <P>SOLUTION: The recording sheet includes on the base material thereof an ink-accepting layer containing at least an amorphous silica a water-soluble polymer adhesive, an ink recipient layer including a crosslinking agent which crosslinks the hydrophilic groups of a water-insoluble polymer adhesive and the water-soluble polymer adhesive, the crosslinking agent being zirconyl acetate and/or zirconyl chloride. The respective blending amounts of the water-soluble polymer adhesive, the water-insoluble polymer adhesive, and the crosslinking agent are predetermined to achieve the purpose. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording material suitable for an ink jet recording system. More specifically, in the ink jet recording method, high image density with high image density and excellent color developability is possible, and the water resistance of the coating film and the non-recording portion are excellent, and the cause of sick house. The present invention relates to a recording sheet that suppresses the generation of certain formaldehyde.

  In recent years, with the expansion of inkjet printer applications by improving the performance of inkjet printers, especially printing speed, resolution, and saturation, advertisements that mainly use color from monochrome office documents such as conventional documents, especially purchasing and advertising As a widespread use. Unlike offset printing or the like, ink jet recording does not require plate making, and thus has a merit that printing in a small amount is possible and costs are reduced.

  More advanced characteristics such as an improvement in absorption speed and an increase in absorption capacity have been required for recording materials, and a coated paper type recording sheet having an ink receiving layer on its surface has been developed. However, there has been a problem in practical water resistance for advertising for outdoor use. For example, even if a base material with excellent water resistance such as a film is used, when the ink receiving layer is provided on the base material by a conventional method, the surface of the ink receiving layer wet with water droplets is touched with a finger, pen, pencil, etc. If the surface is rubbed, the ink receiving layer is peeled off from the interface with the substrate, resulting in poor water resistance. Also, it is increasingly used for large format POP art and drafting. The inkjet recording method is used for large format posters because of its high sharpness and excellent color, and in full color recording, it is advertised by increasing the whiteness of the recording surface to highlight the dot contrast. Great effect. The application to these is because it is possible to easily obtain an image with excellent image reproducibility and color reproducibility such as sharpness and color at the personal computer level, which is also a reason for using a large number of recording sheets. However, when a cross-linking agent is added in order to obtain water resistance of the ink receiving layer, there is a problem that the non-recording portion is discolored under conditions such as temperature, humidity, and ultraviolet rays and whiteness is inferior.

  As a method for improving the water resistance of a coating film using a water-soluble polymer, a method of combining polyvinyl alcohol and polyethyleneimine (see, for example, Patent Document 1), and polyvinyl alcohol and urea / glyoxal / acrylamide polycondensation There is a combination method (for example, refer to Patent Document 2). Furthermore, there is a method of combining polyvinyl alcohol and titanium bislactate which is a metal compound (for example, see Patent Document 3).

In recent years, the simple inkjet recording method and large-format full-color recording have become possible, and the use of wallpaper in showrooms, exhibition booths, etc. has been expanding. In this case, the process may go through the same process as a conventional wallpaper. In that case, the cross-linking agent added for the purpose of obtaining the water resistance of the ink receiving layer is a source of formaldehyde that causes sick house. For example, there is a combination of modified polyamides as a method for obtaining water resistance of a water-soluble polymer (see, for example, Patent Document 4).
JP 2006-7642 A (paragraphs 0006, 0007, 0024, 0027 of the specification) JP 2003-182208 A (paragraphs 0063 to 0065, 0099 of the specification) JP 2003-285549 A (paragraphs 0008 and 0009 of the specification) JP-A-11-78219 (paragraphs 0010 to 0011, 0020 of the specification)

  However, the technique proposed in Patent Document 1 or 2 has a problem that discoloration significantly occurs depending on environmental conditions such as high temperature and high humidity. In the technique proposed in Patent Document 3, the discoloration due to ultraviolet rays is remarkable, and there is a problem for outdoor use. Furthermore, in the technique proposed in Patent Document 4, the combination with the modified polyamide is relatively good in discoloration under various environmental conditions, but cannot be used in the wallpaper processing process due to formaldehyde released from the modified polyamide. There was a problem. Therefore, in order to solve the above problems, the present invention is capable of high-quality recording with excellent ink absorbability and color developability, excellent in water resistance of the coating film, and exhibited in a high-temperature and high-humidity environment or outdoors. The purpose of the invention is to provide a recording sheet which is less discolored in the non-recording portion with time and suppresses the generation of formaldehyde.

  As a result of intensive studies to solve the above problems, the present inventors have found that at least amorphous silica, a water-soluble polymer adhesive, a water-insoluble polymer adhesive, and the water-soluble polymer adhesive. By providing an ink-receiving layer containing a crosslinking agent that crosslinks with a hydrophilic group on a substrate, high-quality recording with excellent ink absorbability and color developability is possible, and coating film water resistance is excellent. Even when exhibited in high-temperature and high-humidity environments, outdoors, etc., we succeeded in obtaining a recording sheet with little discoloration of the non-recording area over time and reduced generation of formaldehyde.

  Specifically, the recording sheet according to the present invention includes at least amorphous silica, a water-soluble polymer adhesive, a water-insoluble polymer adhesive, and a crosslinking agent that crosslinks with the hydrophilic group of the water-soluble polymer adhesive. A recording sheet having an ink receiving layer contained on a substrate, wherein the cross-linking agent is one or both of zirconyl acetate and zirconyl chloride, the water-soluble polymer adhesive, and the water-insoluble polymer When the blending amounts of the adhesive and the crosslinking agent are expressed as a, b, and c in the ink receiving layer, respectively, a, b, and c are 5 (mass%) ≦ a ≦ 25 (mass%), respectively. 3 (mass%) ≦ b ≦ 15 (mass%) and 0.5 (mass%) ≦ c ≦ 10 (mass%). In addition, the mass% which is the ratio of a, b, and c is a numerical value in terms of solid content after drying.

  In the recording sheet according to the present invention, it is preferable that the amount of formaldehyde emitted by JIS A 6921: 2003 “wallpaper” is 0.20 mg / L or less. It can prevent sick house and can be used as wallpaper.

  In the recording sheet according to the present invention, the water-soluble polymer adhesive is preferably polyvinyl alcohol. The manufacturing cost can be reduced, and a recording sheet suitable for an ink jet recording method can be obtained.

  In the recording sheet according to the present invention, the polyvinyl alcohol preferably has a saponification degree of 90 mol% or more. The workability of a normal coating apparatus can be improved.

  In the recording sheet according to the present invention, it is preferable that an undercoat layer containing a crosslinking agent is provided on the base material, and the ink receiving layer is formed on the undercoat layer. There are improvements in physical properties such as adhesion, coating uniformity and water resistance between the ink receiving layer and the substrate, and the effect of surface modification can be obtained.

  The recording sheet according to the present invention includes a case where the substrate is a sheet made of a plastic film, synthetic paper, or synthetic fiber. In these cases, the water resistance of the substrate is obtained.

  The recording sheet according to the present invention is capable of high-quality recording with excellent ink absorbability and color development using an ink jet printer with such a configuration, and is excellent in water resistance, high temperature and high humidity. Even when exhibited in the environment or outdoors, there is little discoloration of the non-recorded part over time, and generation of formaldehyde can be suppressed as a countermeasure against sick house for wallpaper use.

  Next, the present invention will be described in detail, but the present invention is not limited to these embodiments.

  In the recording sheet of the present invention, the color development property and water resistance of the ink-receiving layer by the inkjet method, the suitability for discoloration of the non-recorded portion over time in a high-temperature and high-humidity environment and ultraviolet rays, and JIS A 6921: 2003 “Wallpaper” In order to satisfy the formaldehyde emission rate of 0.20 mg / L or less, the selection and blending amount of the main components are important. Amorphous silica, water-soluble polymer adhesive, water-insoluble polymer adhesive In addition, a combination of a zirconyl compound as a crosslinking agent that crosslinks with the hydrophilic group of the water-soluble polymer adhesive satisfies these conditions.

  The recording sheet according to the present embodiment includes at least an amorphous silica, a water-soluble polymer adhesive, a water-insoluble polymer adhesive, and a cross-linking agent that crosslinks a hydrophilic group of the water-soluble polymer adhesive. A recording sheet provided with a layer on a substrate, wherein the crosslinking agent is one or both of zirconyl acetate or zirconyl chloride, the water-soluble polymer adhesive, the water-insoluble polymer adhesive, When the respective blending amounts of the crosslinking agent are expressed as a, b, and c as the proportion of the ink receiving layer, a, b, and c are 5 (mass%) ≦ a ≦ 25 (mass%), 3 (mass), respectively. %) ≦ b ≦ 15 (mass%) and 0.5 (mass%) ≦ c ≦ 10 (mass%).

  Examples of the water-soluble polymer adhesive used in the recording sheet according to the present embodiment include polyvinyl alcohol, starch, gelatin, casein, polyvinyl pyrrolidone, and various modified products thereof. Polyvinyl alcohol is preferred from the viewpoints of inkjet suitability and price. The so-called partially saponified polyvinyl alcohol with a saponification degree of less than 90 mol% has strong hydrophilicity and inferior coating film water resistance, and is very easy to foam, and it is difficult to obtain a beautiful coating surface continuously with ordinary coating equipment. Polyvinyl alcohol having a saponification degree of 90 mol% or more is preferable. The blending amount of the water-soluble polymer adhesive is 5 to 25% by mass, preferably 8 to 22% by mass, and more preferably 9 to 20% by mass in the ink receiving layer. When the amount is less than 5% by mass, the ink absorbency of printing by the ink jet method is improved, but the coating film strength is remarkably lowered. On the other hand, if it exceeds 25% by mass, the ink absorbability is adversely affected, the printability is poor, and the water resistance of the coating film is insufficient.

  Applicable to water-insoluble polymer adhesives include, for example, conjugated diene polymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer, acrylate polymer or copolymer Acrylic polymer latex such as polymer or methacrylic acid ester polymer or copolymer thereof, vinyl polymer latex such as ethylene-vinyl acetate copolymer, carboxyl group or cationic group of these various polymers There are functional group-containing modified polymer latexes or combinations of these latexes. The blending amount of the water-insoluble polymer adhesive is 3 to 15% by mass, preferably 5 to 12% by mass, and more preferably 6.5 to 10% by mass in the ink receiving layer. If it is less than 3% by mass, the strength of the coating film is insufficient, and if it exceeds 15% by mass, it is water-insoluble, so that it significantly inhibits the absorptivity of water-based inks often used in ink jet systems. .

  The crosslinking agent of the water-soluble polymer adhesive used for the recording sheet according to this embodiment is either one or both of zirconyl acetate and zirconyl chloride. Other examples of the zirconyl compounds include zirconyl nitrate and zirconyl ammonium carbonate, which are inferior in terms of color development of printing and discoloration of non-printed portions due to environmental conditions. In addition to the zirconyl series, titanium compounds, aldehyde series compounds, modified polyamide resins and the like can be cited as crosslinking agents, but in order to combine the strength of the coating film, water resistance, discoloration resistance of non-recorded areas, and suppression of formaldehyde generation. It was insufficient. Accordingly, the crosslinking agent is preferably zirconyl acetate or zirconyl chloride. Moreover, you may use both together. The blending amount of the crosslinking agent is 0.5 to 10% by mass, preferably 1 to 7% by mass, and more preferably 1.5 to 6% by mass in the ink receiving layer. When it is less than 0.5% by mass, it is insufficient to obtain the water resistance of the water-soluble polymer adhesive, and when it exceeds 10% by mass, the pot life of the coating liquid is inferior. Moreover, even if it mixes exceeding 10 mass%, blurring of an image will generate | occur | produce, water resistance will not be obtained more effectively, but only the burden of cost will increase.

  In the recording sheet according to this embodiment, an ink receiving layer is formed on a substrate to obtain a recording sheet, but various physical properties such as adhesion, coating uniformity, and water resistance are improved between the ink receiving layer and the substrate. An undercoat layer is preferably provided for the purpose of surface modification. The base material may be subjected to a specific surface treatment, and such a surface treatment layer may be interposed between the undercoat layer and the base material. In this case, an undercoat layer compatible with the surface treatment layer is preferable. The undercoat layer is a layer mainly composed of resin and particles. Examples of the resin to be included in the undercoat layer include polyvinyl alcohol, starch, polyvinylpyrrolidone or various modified products thereof, or conjugated diene polymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer, Acrylic polymer latex such as acrylic ester polymer or copolymer thereof, methacrylate polymer or copolymer thereof, vinyl polymer latex such as ethylene-vinyl acetate copolymer, or these latexes There is a combination. In addition, inorganic fine particles or organic fine particles can be used as particles to be included in the undercoat layer. Inorganic fine particles include, for example, amorphous silica, kaolin, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, satin white, Aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, magnesium carbonate or magnesium hydroxide. The organic fine particles are, for example, acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene-acryl, styrene-butadiene, polystyrene-acryl, polystyrene, urethane, or polyester. The particles are not limited to these, and fine particles generally used for paper coating can be used depending on required properties.

  The undercoat layer preferably contains a cross-linking agent as necessary. The crosslinking agent is, for example, a zirconium compound. The proportion of the crosslinking agent in the undercoat layer is preferably 1 to 10% by mass. In addition, as needed, an auxiliary agent can be added in the range which does not impair the effect of invention. The auxiliary agent is, for example, a thickener, a fluidity improver, an antifoaming agent, an antifoaming agent, a dispersant, a release agent, an ultraviolet absorber, an antistatic agent, an antioxidant, an antiseptic or a pH adjuster. .

  The substrate is not particularly limited, and examples thereof include natural paper, plastic film, synthetic paper, non-woven fabric, cloth, wood, and metal thin film, and are selected according to the application. When the substrate is required to have water resistance depending on the application, the substrate is preferably a plastic paper or a synthetic paper or nonwoven fabric sheet made of synthetic fibers. The plastic film is, for example, a polyester film, a polypropylene film, a polyethylene film, a nylon film, a vinylon film, or an acrylic film. Moreover, the laminated film which bonded these films together can be used. The plastic film is preferably uniaxially or biaxially stretched from the viewpoint of strength. Examples of the non-woven fabric include those formed by spreading polyethylene fibers in a sheet shape and thermocompression bonding to form a sheet shape.

  In the present invention, the plastic film may be a film made opaque by cavities or inorganic pigment particles. The inorganic pigment particles are, for example, silica fine particles, kaolin, talc, calcium carbonate, zeolite, alumina, carbon black, zinc oxide, or titanium oxide.

  The amorphous silica contained in the ink receiving layer generally includes precipitated silica or gel silica, which is porous, has high ink absorbability, and enables clear color development. Amorphous silica has a high oil absorption and a high specific surface area, and its average particle diameter is preferably 1 to 20 μm, more preferably 3 to 15 μm. When the average particle diameter of the amorphous silica is smaller than 1 μm, the strength of the ink receiving layer is greatly reduced, and it is difficult to obtain sufficient voids in the receiving layer, and conversely when the average particle diameter is larger than 20 μm. In addition to causing bleeding called feathering when printing is performed, protrusions are likely to occur on the surface of the ink receiving layer, and depending on the application, the ink receiving layer and the laminate may be laminated when the surface is laminated during processing after printing. This may cause troubles such as gaps between the film and the film. Further, fine particles other than amorphous silica can be used in combination according to the purpose of use of the sheet and the required performance of the printer. Examples of fine particles that can be used in combination include inorganic fine particles and organic fine particles that are generally used for paper coating. Examples of inorganic fine particles include kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, titanium dioxide, satin white, aluminum silicate, diatomaceous earth. Soil, calcium silicate, aluminum hydroxide, magnesium carbonate or magnesium hydroxide. The organic fine particles are, for example, acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene-acrylic, styrene-butadiene, polystyrene-acrylic, polystyrene, urethane, or polyester. Further, these fine particles other than amorphous silica may be used in appropriate combination.

  If necessary, an auxiliary agent can be added to the ink receiving layer as long as the effects of the invention are not impaired. Auxiliary agents include, for example, cationic resins for fixing anionic dye inks, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, dispersants, mold release agents, UV absorbers, antistatic agents, and antioxidants. Agent, preservative, or pH adjuster.

The method for providing the ink receiving layer on the substrate or the undercoat layer is not particularly limited. Conventionally known methods are, for example, gravure coating method, kiss coating method, dip method, spray coating method, curtain coating method, air knife coating method, blade coating method, reverse roll coating method or bar coating method. An ink receiving layer can be provided by a coating machine of such a method. The coating amount of the ink receiving layer is determined depending on the use, and need not be increased unnecessarily as long as ink absorption, recording characteristics, storage stability, opacity, etc. are satisfied, preferably 5 to 35 g / m ² , more Preferably, it is appropriately selected from the range of 8 to 30 g / m ² and used. When the coating amount of the ink receiving layer is less than 5 g / m ² , the ink absorption amount and the ink absorption speed are insufficient, and the image may flow out or the image may be blurred. Further, since ink drying is slow, there is a risk that the ink adheres to the roll of an ink jet printer or printer and becomes dirty. On the other hand, when the coating amount exceeds 35 g / m ² , the ink-receiving layer is thick, so that the adhesion to the substrate is weakened, and an ink-receiving layer is formed between layers, and it is not practical for economic reasons.

  After the ink receiving layer is formed, an aging treatment may be performed for the purpose of promoting the reaction between the hydroxyl group of the water-soluble polymer and the crosslinking agent. By the aging treatment, it is possible to obtain the water resistance of the ink receiving layer in a shorter time. As aging process conditions, it is a 25-60 degreeC environment, Preferably it is a 30-50 degreeC environment. If it is less than 25 degreeC, it does not change with normal temperature environment, and an acceleration effect is not acquired. Further, if the temperature exceeds 60 ° C., the cost burden such as the heat source and the cooling time increases, so it is not practical for economic reasons.

  The recording sheet of this embodiment contains at least amorphous silica, a water-soluble polymer adhesive and a water-insoluble polymer adhesive on a substrate, and zirconyl acetate as a crosslinking agent for the water-soluble polymer adhesive. By providing an ink receptive layer containing either or both of zirconyl chloride, the ink receptive layer has excellent color developability and water resistance due to the ink jet method, and when it is displayed in a high-temperature and high-humidity environment or outdoors. There is little discoloration of the non-recorded portion with time due to ultraviolet rays, and furthermore, the amount of formaldehyde emitted by JIS A 6921: 2003 “wallpaper” can be suppressed to 0.20 mg / L or less. In addition, it is preferable to avoid the use of a chemical agent that generates formaldehyde for the base material, the water-soluble polymer adhesive, and the water-insoluble polymer adhesive.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this invention is not limited by this. In the following, “parts” and “%” mean “parts by mass” and “mass%”, and “parts by mass” and “mass%” in Examples and Comparative Examples all indicate numerical values in terms of solid content after drying. And

Example 1
An ink-receiving layer having the following composition was coated on a hollow and titanium oxide-containing polypropylene film (PI-80 manufactured by Nanya) substrate so as to have a dry mass of 20 g / m ² and dried to obtain a recording sheet. This was produced as Example 1.
Amorphous silica (Grace Devison 74 × 5500 / Grace Devison P-412 = 7/3) 65% by mass
Polyvinyl alcohol (Exeval RS2117 made by Kuraray) 15% by mass
10% by mass of ethylene-vinyl acetate copolymer (Polysol AD-10, Showa High Polymer Co., Ltd.)
Zirconyl acetate (Zircozole ZA-30, first rare element) 5% by mass
Cationic resin (Senka CP-103) 5% by mass

(Example 2)
Example 2 is the same as Example 1 except that an ink receiving layer having the following composition was applied to the substrate so as to form a dry mass of 20 g / m ² and dried. A recording sheet was obtained.
Amorphous silica (Grace Devison 74 × 5500 / Grace Devison P-412 = 7/3) 65% by mass
Polyvinyl alcohol (Exeval RS2117 made by Kuraray) 15% by mass
10% by mass of ethylene-vinyl acetate copolymer (Polysol AD-10, Showa High Polymer Co., Ltd.)
Zirconyl chloride (Origatix ZB-126 manufactured by Matsumoto Kosho) 5% by mass
Cationic resin (Senka CP-103) 5% by mass

(Example 3)
The same procedure as in Example 1 was conducted except that the substrate was a paper substrate having a wet tensile strength of 0.65 kN / m (MD) according to JIS P 8135: 1998 “Paper and paperboard—wet tensile strength test method”. The recording sheet of Example 3 was obtained.

Example 4
A recording sheet of Example 4 was obtained in the same manner as in Example 1 except that 0.5% by mass of zirconyl acetate and 14.5% by mass of ethylene-vinyl acetate copolymer were used.

(Example 5)
A recording sheet of Example 5 was obtained in the same manner as Example 1 except that 5% by mass of ethylene-vinyl acetate copolymer and 10% by mass of zirconyl acetate were used.

(Example 6)
A recording sheet of Example 6 was obtained in the same manner as in Example 1 except that 70% by mass of amorphous silica, 5% by mass of polyvinyl alcohol, and 15% by mass of ethylene-vinyl acetate copolymer were used.

(Example 7)
A recording sheet of Example 7 was obtained in the same manner as in Example 1 except that 60% by mass of amorphous silica, 25% by mass of polyvinyl alcohol, and 5% by mass of ethylene-vinyl acetate copolymer were used.

(Example 8)
A recording sheet of Example 8 was obtained in the same manner as in Example 5 except that polyvinyl alcohol was 17% by mass and ethylene-vinyl acetate copolymer was 3% by mass.

Example 9
A recording sheet of Example 9 was obtained in the same manner as in Example 1 except that polyvinyl alcohol was changed to 10% by mass and ethylene-vinyl acetate copolymer was changed to 15% by mass.

(Example 10)
A recording sheet of Example 10 was obtained in the same manner as Example 1 except that a white polyethylene terephthalate film (Toyobo Co., Ltd .: K2323) was used as the substrate.

(Example 11)
A recording sheet of Example 11 was obtained in the same manner as in Example 1 except that a nonwoven fabric made of polyethylene fiber (AR1082 manufactured by Asahi DuPont) was used as the base material.

(Example 12)
A recording sheet of Example 12 was obtained in the same manner as Example 1 except that ² g / m ^{2 of} an undercoat layer having the following composition was provided between the substrate and the ink receiving layer as the mass after drying.
Amorphous silica (Grace Devison 74x5500) 10% by mass
Polyvinyl alcohol (Kuraray Exebar RS2117) 35% by mass
45% by mass of ethylene-vinyl acetate copolymer (Polysol AD-10, Showa Polymer Co., Ltd.)
Zirconyl acetate (Zircozole ZA-30, first rare element) 3% by mass
Auxiliary agent (fluorescent dye (Nippon Kayaku Kayahole PAS Q Liquid) 1.5% by mass Auxiliary agent (Thickener (Adeka 541 VF)) 5.5% by mass

(Example 13)
A recording sheet of Example 13 was obtained in the same manner as in Example 1 except that an undercoat layer having the following composition was provided between the base material and the ink receiving layer in an amount of 1 g / m ² after drying.
Organic particle benzoguanamine resin (Eposter MS, manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) 30% by mass
Polyvinyl alcohol (Exeval RS2117 manufactured by Kuraray) 20% by mass
Ethylene-vinyl acetate copolymer (Polysol AD-10, Showa Polymer Co., Ltd.) 40% by mass
Zirconyl acetate (Zircozole ZA-30, first rare element) 3% by mass
Auxiliary agent (fluorescent dye (Nippon Kayaku Kayahole PAS Q Liquid) 1.5% by mass Auxiliary agent (Thickener (Adeka 541 VF)) 5.5% by mass

(Example 14)
A recording sheet of Example 14 was obtained in the same manner as in Example 1 except that an undercoat layer having the following composition was provided between the base material and the ink receiving layer in an amount of 1 g / m ² after drying.
Water-absorbing modified polyester resin (CW-11, made by Gokoku Dye) 30% by mass
Polyvinyl alcohol (Exeval RS2117 manufactured by Kuraray) 20% by mass
Ethylene-vinyl acetate copolymer (Polysol AD-10, Showa Polymer Co., Ltd.) 40% by mass
Zirconyl acetate (Zircozole ZA-30, first rare element) 3% by mass
Auxiliary agent (fluorescent dye (Nippon Kayaku Kayahole PAS Q Liquid) 1.5% by mass Auxiliary agent (Thickener (Adeka 541 VF)) 5.5% by mass

(Example 15)
Instead of adding 5% by mass of zirconyl acetate, the recording sheet of Example 15 was prepared in the same manner as in Example 1 except that 2.5% by mass of zirconyl acetate and 2.5% by mass of zirconyl chloride were added in combination. Obtained.

(Comparative Example 1)
A recording sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that polyvinyl alcohol was 20% by mass and no zirconyl acetate was added.

(Comparative Example 2)
A recording sheet of Comparative Example 2 was obtained in the same manner as in Example 2 except that 5% by mass of polyvinyl alcohol and 15% by mass of zirconyl chloride were used.

(Comparative Example 3)
A recording sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that the ink receiving layer was changed to the following composition.
Amorphous silica (Grace Devison 74 × 5500 / Grace Devison P-412 = 7/3) 65% by mass
15% by mass of ethylene-vinyl acetate copolymer (Polysol AD-10, Showa Polymer Co., Ltd.)
Zirconyl acetate (Zircozole ZA-30, first rare element) 10% by mass
Cationic resin (Senka CP-103) 10% by mass

(Comparative Example 4)
A recording sheet of Comparative Example 4 was obtained in the same manner as in Example 1 except that 50% by mass of amorphous silica and 30% by mass of polyvinyl alcohol were used.

(Comparative Example 5)
A recording sheet of Comparative Example 5 was obtained in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer was not added and the polyvinyl alcohol was 25% by mass.

(Comparative Example 6)
A recording sheet of Comparative Example 6 was obtained in the same manner as in Example 1 except that 55% by mass of amorphous silica and 20% by mass of ethylene-vinyl acetate copolymer were used.

(Comparative Example 7)
A recording sheet of Comparative Example 7 was obtained in the same manner as in Example 5 except that zirconyl acetate was changed to zirconyl ammonium carbonate (Zircosol AZ-20 manufactured by First Rare Element).

(Comparative Example 8)
A recording sheet of Comparative Example 8 was obtained in the same manner as in Example 5 except that zirconyl acetate was changed to zirconyl nitrate (Zircozole ZN, a first rare element).

(Comparative Example 9)
A recording sheet of Comparative Example 9 was obtained in the same manner as in Example 5, except that zirconyl acetate was changed to polyethyleneimine (CP-8994 manufactured by Starlight PMC).

(Comparative Example 10)
A recording sheet of Comparative Example 10 was obtained in the same manner as in Example 5 except that zirconyl acetate was changed to urea / glyoxal / acrylamide polycondensate (Sumitomo Chemical 5004).

(Comparative Example 11)
A recording sheet of Comparative Example 11 was obtained in the same manner as in Example 5 except that zirconyl acetate was changed to titanium bislactate (Orgatechs TC-310 manufactured by Matsumoto Kyosho).

(Comparative Example 12)
A recording sheet of Comparative Example 12 was obtained in the same manner as in Example 5 except that zirconyl acetate was glyoxal (manufactured by Nippon Synthetic Chemical Co., Ltd., Glyoxal GX).

(Comparative Example 13)
A recording sheet of Comparative Example 13 was obtained in the same manner as in Example 5, except that zirconyl acetate was used as a melamine resin (M-3, manufactured by Dainippon Ink).

(Comparative Example 14)
A recording sheet of Comparative Example 14 was obtained in the same manner as in Example 5 except that zirconyl acetate was used as a modified polyamide resin (SI-6400 manufactured by Starlight PMC).

About the recording sheet of each Example and each comparative example, the physical property shown below was evaluated and the result was put together in Table 1.
(1) Color developability Using a printer using water-based pigment ink (Hi-Fi Jet-Pro FJ-400, manufactured by Roland), black, cyan, magenta, and yellow images are output to the resulting recording sheet, and color developability is achieved. Evaluated. Those excellent in color developability are indicated by ◎, those that do not cause problems in actual use are indicated by ○, those that are low in color developability and cannot be actually used are indicated by Δ, and those that are extremely low in color developability and cannot be actually used are indicated by ×.

(2) Absorbency Using the Hi-Fi Jet-Pro FJ-400 printer manufactured by Roland, a white character image was output on the obtained recording sheet, and the ink absorptivity was evaluated. ◎ clear, excellent ink-absorbing, without crushed white letters, ◯ with no problems in actual use, △ those that cannot be used, △, poorly absorbed and severely crushed white letters, cannot be used Things are shown as x.

(3) Water resistance of coating film Using the Hi-Fi Jet-Pro FJ-400 printer manufactured by Roland, the obtained recording sheet is output with a solid black image, immersed in water for 5 minutes, and then the surface of the coating layer is pointed It rubbed and evaluated whether the coating layer peeled off. The coating layer hardly peels off and has excellent water resistance ◎, the coating layer peels off slightly, but there are no practical problems ○ The thing was shown by x.

(4) Discoloration (moisture resistance)
The obtained recording sheet was left for 96 hours in an environment of a temperature of 30 ° C. and a relative humidity of 80%. The color before and after leaving the recording sheet was measured with a Konica Minolta color difference meter CR-300, and the color difference ΔE * ab before and after being left was determined. The color difference is shown below based on the result of measuring the color of the sample before and after being left in accordance with the L * a * b * color system (CIE 1976) of JIS Z 8730: 2002 “Color Display Method—Color Difference of Object Color”. It can be defined by Equation 1. The larger the color difference is, the more severe the color change is. The color difference ΔE * ab is 2.0 or less, and it can be determined that there is no practical problem.

(Equation 1)
ΔE * ab = {(ΔL *) ² + (Δa *) ² + (Δb *) ² } ^1/2
Here, ΔE * ab is a color difference, and ΔL *, Δa *, and Δb * are differences between L *, a *, and b * before and after being left unattended.

(5) Discoloration (heat resistance)
The obtained recording sheet was allowed to stand for 96 hours at a temperature of 60 ° C. The color before and after leaving the recording sheet was measured with a Konica Minolta color difference meter CR-300, and the color difference ΔE * ab before and after being left was determined. The color difference is expressed by Equation 1 based on the result of measuring the color of the sample before and after being left in accordance with the L * a * b * color system (CIE 1976) of JIS Z 8730: 2002 “Color Display Method—Color Difference of Object Color”. Can be prescribed. The larger the color difference is, the more severe the color change is. The color difference ΔE * ab is 2.0 or less, and it can be determined that there is no practical problem.

(6) Discoloration (light resistance)
The obtained recording sheet was subjected to a xenon lamp at 340 nm 0.5 W / m ² under a black panel temperature of 40 ° C. and a relative humidity of 50% using a weatherometer Ci4000 manufactured by Atlas (domestic distributor Toyo Seiki Seisakusho). For 24 hours. The color before and after light irradiation was measured with a Konica Minolta color difference meter CR-300, and the color difference ΔE * ab before and after light irradiation was determined. The color difference is based on the result of measuring the color of the sample before and after light irradiation according to the L * a * b * color system (CIE 1976) of JIS Z 8730: 2002 “Color Display Method—Color Difference of Object Color”. It can be specified by. The larger the color difference is, the more severe the color change is. The color difference ΔE * ab is 2.0 or less, and it can be determined that there is no practical problem.

(7) Formaldehyde emission amount The obtained recording sheet was subjected to a test according to JIS A 6921: 2003 “Wallpaper” to measure the emission amount of formaldehyde. If it is 0.20 mg / L or less, the standard of JIS A 6921: 2003 “wallpaper” is satisfied.

(8) Stability of coating liquid The coating liquids used in Examples and Comparative Examples were allowed to stand for 12 hours in a temperature of 30 ° C. environment, and the stability of the coating liquid was sensory evaluated. Even when left untreated, the viscosity is not increased or colored, ○, the viscosity is increased or colored, Δ is not practically used, the viscosity is increased, coloring or wrinkle is clearly seen, and on the substrate Those that could not be coated were marked with ×.

  Below, each evaluation result of the recording sheet of Example 1 is demonstrated. As a result of the color developability, the color developability was excellent. As a result of the absorptivity, the outline characters were not crushed and the ink was clear and excellent in ink absorptivity. As for the results regarding the water resistance of the coating film, although the coating layer was slightly peeled off, there was no practical problem. The result of discoloration (moisture resistance) was ΔE * ab = 0.40, which could be judged as a practically acceptable level. The result about discoloration (heat resistance) was ΔE * ab = 0.65, which could be judged as a practically acceptable level. The result about discoloration (light resistance) was ΔE * ab = 1.40, which could be judged as a practically acceptable level. The result of formaldehyde emission was below the lower limit of detection and met the criteria of JIS A 6921: 2003 “Wallpaper”. As a result of the stability of the coating liquid, there was no increase in viscosity or coloration after standing.

  As can be seen from Table 1, the recording sheets obtained in Examples 2 to 15 have good color developability, absorptivity, and water resistance of the coating film as in Example 1. The recording sheet had little discoloration and suppressed generation of formaldehyde.

  On the other hand, the recording sheet of Comparative Example 1 in which no cross-linking agent was used in the ink receiving layer, although there was little discoloration, was severely peeled off as a result of the water resistance of the coating film and could not be used. The recording sheet of Comparative Example 2 containing a large amount of a crosslinking agent in the ink receiving layer had low color developability and could not be actually used. The recording sheet of Comparative Example 3, which did not use a water-soluble polymer adhesive in the ink receiving layer, had low color developability, was uneasy for actual use, and could not be used for absorbency. According to the comparison between Comparative Example 4 and Example 1, the recording sheet of Comparative Example 4 containing a large amount of the water-soluble polymer adhesive in the ink receiving layer has low color developability, is uneasy for actual use, and has an absorptivity. Inferior white characters were severely crushed and could not be used in practice, and the coating layer was peeled off and could not be used in practice. According to a comparison between Comparative Example 5 and Example 7, the recording sheet of Comparative Example 5 in which the water-insoluble polymer adhesive was not used for the ink receiving layer could not be actually used because the coating layer was peeled off. According to a comparison between Comparative Example 6 and Example 1, the recording sheet of Comparative Example 6 containing a large amount of water-insoluble polymer adhesive in the ink receiving layer has low color developability, is uneasy for actual use, and absorbability. However, the white characters were severely crushed and could not be used. In addition, the recording sheet of Example 15 using both zirconyl acetate and zirconyl chloride as the cross-linking agent for the ink receiving layer has good color developability, absorbability, and water resistance of the coating film, and is subjected to high temperature and high humidity conditions and with time due to ultraviolet rays. There was little discoloration in and the generation of formaldehyde was suppressed. On the other hand, the recording sheets of Comparative Examples 7 to 14 using materials other than zirconyl acetate and zirconyl chloride as the crosslinking agent for the ink receiving layer are inferior in color developability, water resistance and discoloration, and satisfy the suppression of formaldehyde generation. I couldn't.

Claims (6)

Recording in which an ink receiving layer containing at least amorphous silica, a water-soluble polymer adhesive, a water-insoluble polymer adhesive, and a crosslinking agent that crosslinks with the hydrophilic group of the water-soluble polymer adhesive is provided on a substrate. A sheet,
The cross-linking agent is either one or both of zirconyl acetate and zirconyl chloride, and the ink-receiving layer occupies each blending amount of the water-soluble polymer adhesive, the water-insoluble polymer adhesive, and the cross-linking agent. When expressed as a, b, and c as ratios, a, b, and c are each 5 (mass%) ≦ a ≦ 25 (mass%),
3 (mass%) ≦ b ≦ 15 (mass%) and 0.5 (mass%) ≦ c ≦ 10 (mass%)
A recording sheet having the following relationship:   The recording sheet according to claim 1, wherein the amount of formaldehyde emitted by JIS A 6921: 2003 “wallpaper” is 0.20 mg / L or less.   The recording sheet according to claim 1, wherein the water-soluble polymer adhesive is polyvinyl alcohol.   The recording sheet according to claim 3, wherein the degree of saponification of the polyvinyl alcohol is 90 mol% or more.   The recording sheet according to claim 1, wherein an undercoat layer containing a crosslinking agent is provided on the substrate, and the ink receiving layer is formed on the undercoat layer.   6. The recording sheet according to claim 1, wherein the substrate is a sheet made of a plastic film, synthetic paper, or synthetic fiber.