JP2002293001A - Inkjet recording sheet - Google Patents

Abstract

(57) [Summary] [Problem] To provide a high-quality ink jet recording sheet having no printing unevenness, excellent ink absorbability, and a clear printed image. In an ink jet recording sheet capable of printing on both sides, provided with an ink receiving layer containing a white pigment as a main component on both sides of a sheet-like support filled with calcined kaolin, a specific acetylene glycol derivative is provided on both sides of the ink receiving layer. ,
Alternatively, a specific alkali metal salt of dialkyl sulfosuccinic acid is simultaneously applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet used in an ink jet recording system using an aqueous ink.
More specifically, the present invention relates to a high-quality inkjet recording sheet capable of performing double-sided printing with no offset of printed images and no uneven printing, and excellent in ink absorbency and image clarity.

[0002]

2. Description of the Related Art In recent years, it has become possible to obtain clear images and print quality using plain paper as an ink jet recording sheet by improving the performance of an ink jet printer using an aqueous ink and improving the ink. However, on the other hand, in order to make print quality, saturation, appearance, and images more attractive, inkjet recording sheets having more advanced characteristics are required, and in particular, improvement in printing speed, resolution, saturation, and the like of a printer is required. Ink-jet recording sheets also require advanced printing characteristics such as high ink absorption, high ink absorption capacity, dot roundness, and the like, in which an ink receiving layer is provided on a support such as paper. Paper was developed.

For example, JP-A-55-51583 discloses an ink receiving layer containing non-colloidal silica and a polymer binder on a base paper, or JP-A-58-72495 discloses an average particle size of 0.05 μm or less. It is disclosed that by providing an ink-receiving layer containing a silica-based pigment as a water-soluble polymer binder, an ink jet recording sheet excellent in ink absorbency, dot roundness, and sharpness can be obtained. That is, in order to meet the demands of the market, a coating layer mainly composed of a white pigment excellent in water absorption such as fine particle synthetic silica is provided on the surface of a support such as paper mainly composed of cellulose pulp. In particular, an ink jet recording sheet of a type using a coating layer and paper as a base paper has a good balance of cost, texture and quality, and is expected as a future ink jet recording sheet.

[0004] On the other hand, unlike ink-jet recording, printing does not require plate making, so that small-quantity printing is possible.
There is an advantage of ease. With the expanding use of inkjet printers and plotters, advertising materials mainly for printing from office documents such as documents, especially point-of-purchase advertisements (Poi
nt of PurchaseAdvertisin
g, hereinafter referred to as POP), as well as direct mail, postcards such as general postcards, and business cards. As the applications of POP advertisements, postcards, business cards, and the like have expanded, ink jet recording sheets capable of printing on both sides from ink jet paper for single side printing used for conventional office documents and the like have been demanded and developed. For example, JP-A-56-148584 and JP-A-2-27.
Japanese Patent No. 0588 discloses a recording sheet having an ink receiving layer formed on both sides of a paper substrate.

[0005]

When the effect of the present invention was confirmed by a follow-up experiment, the ink jet recording sheets can be printed on both sides, but when printing on both sides, the ink on one side bleeds on the other side. Putting out (through) is not practical. For POP advertising, postcards, and business card applications, the image printed on one side can be seen and read from the other side (set-off).
Is not practically sufficient. As a countermeasure against the set-off, increase the coating amount of the ink receiving layer, increase the paper thickness, or incorporate titanium dioxide, calcium carbonate, calcined kaolin, etc., which can be used as a filler with high opacity, into a support such as paper. There is a method such as doing. Particularly preferred is calcined kaolin, but calcined kaolin causes uneven printing due to its larger ink absorption capacity than cellulose pulp,
An ink jet recording sheet capable of high-quality double-sided printing cannot be obtained. Accordingly, the object of the present invention is to eliminate offset and print unevenness of a printed image of an ink jet recording sheet using a sheet-like support filled with calcined kaolin, excellent ink absorbency, excellent image clarity, and capable of double-sided printing. An object of the present invention is to provide a high-quality inkjet recording sheet.

[0006]

As a result of extensive studies and experiments, the present inventor has found that an ink receiving layer containing a white pigment as a main component is provided on both sides of a sheet-like support containing calcined kaolin. In an ink jet recording sheet capable of double-sided printing, an acetylene glycol derivative represented by the following general formula (1) or the following general formula (2) is provided on both sides of the ink receiving layer.
The present invention has been made based on the finding that the object can be achieved by simultaneously applying the alkali metal salt of dialkyl sulfosuccinic acid represented by the formula (1).

[0007]

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In the general formula (1), R _{1 to} R _{4 each} have _{1 to 4} carbon atoms.
Represents an alkyl group. m + n = 3 to 30 moles of ethylene oxide added.

[0009]

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In the general formula (2), R ₅ and R _{6 each} have 4 to 1 carbon atoms.
2 represents an alkyl group. M represents an alkali metal salt of lithium, sodium or potassium. ]

That is, by simultaneously applying the acetylene glycol derivative or sodium dialkyl sulfosuccinate of the present invention to both surfaces of the ink receiving layer, there is no printing unevenness, the ink absorbency is greatly improved, and a high image free bleeding is achieved. A quality image was obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the acetylene glycol derivative represented by the above general formula (1) used in the present invention include the following.

[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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As the alkali metal dialkylsulfosuccinate represented by the general formula (2) used in the present invention, a sodium salt is generally commercially available, and examples thereof include the following.

[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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The acetylene glycol derivative represented by the general formula (1) and the alkali metal salt of dialkyl sulfosuccinic acid represented by the general formula (2) used in the present invention are each formed into an aqueous solution, and are used in a bill blade coater, a gate roll, and the like. Coater, transfer roll coater, both sides of the ink receiving layer by a coating method such as size press, the amount of coating on both sides is 0.1 to 0.1
4 g / m ² (dry weight solids), particularly preferably 0.2
２2 g / m ² to obtain an ink jet recording sheet which can be printed on both sides by coating and drying. Although the ink receiving layer of the present invention has a highly smooth surface quality, it is preferable to perform treatment with a smoothing device such as a super calender or a soft calender in order to obtain a more excellent recorded image.

As the sheet-like support used in the present invention, an acid paper, a neutral paper, or the like for general coated paper is appropriately used. The sheet-shaped support is mainly composed of wood pulp, and is filled with calcined kaolin to improve opacity. Wood pulp is various chemical pulp, mechanical pulp, recycled pulp, etc., and these pulp are beaten with a beater to maintain the suitability for ink-jet recording such as papermaking suitability, coating suitability, ink absorption and recording surface quality. Adjust the degree (freeness). The degree of beating of the pulp varies depending on the type of pulp and is not particularly limited, but is generally 300 to 500 ml [Canadian Standard Freeness (hereinafter referred to as CSF):
JIS P-8121] is preferable. The calcined kaolin used in the present invention has a whiteness of 90 to 92%, a particle diameter of 2 μm or less 90%, an oil absorption of 90 to 110 g / 100 g, a specific surface area of 18 to 19 m ² / g, and a filling ratio of 100 parts by weight of pulp. 5 to 30 parts by weight, preferably 10 to
20 parts by weight.

A sizing agent, a paper strength enhancer, a retention enhancer, and the like are added as auxiliaries, and a water-soluble polymer such as starch is further applied and impregnated in a size press process of a paper machine to obtain surface strength, sizing degree, etc. To adjust. The basis weight of the sheet-like support to be formed is 40 to 350 g / m ² , and the size varies depending on the basis weight.
When the sizing degree is low, there is a problem in operation due to paper breakage or wrinkles at the time of coating, and when the sizing degree is high, the absorbability is poor and bleeding occurs.

Examples of the white pigment of the ink receiving layer used in the present invention include talc, kaolin, calcined kaolin, acid clay, activated clay, calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, sulfide. Zinc, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, aluminum hydroxide, synthetic amorphous silica, colloidal silica, colloidal alumina, alumina, lithopone,
Inorganic white pigments such as zeolite and hydrohaloysite; plastic pigments such as polyethylene, polystyrene and polyacrylate; and organic white pigments such as urea resin and melamine resin. One type or a mixture of two or more types is used. Particularly preferred is synthetic amorphous silica. The dispersant for the synthetic amorphous silica used in the present invention includes sodium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, sodium polyacrylate, sodium hydroxide, sodium silicate, and the like, and preferably sodium polyacrylate. , Sodium hydroxide and sodium silicate.

In the present invention, an adhesive is contained in order to adhere the white pigment to the sheet-like support. Examples of the adhesive used in the present invention include natural or semi-synthetic water-soluble polymers such as starch, casein, soybean protein, gelatin, carboxymethylcellulose, and hydroxyethylcellulose; Water-soluble polymer; conjugated diene-based polymer latex such as styrene-butadiene copolymer and methyl methacrylate butadiene copolymer; vinyl-based polymer latex such as ethylene-vinyl acetate copolymer; Mix and use.

In the present invention, the ink receiving layer contains a cationic ink fixing agent in order to improve the weather resistance of the printed image. Examples of the cationic ink fixing agent used in the present invention include a copolymer of dimethyldiallylammonium chloride and acrylamide, a polymer of alkyl (meth) acrylate or a quaternary ammonium compound of alkyl (meth) amide, or a quaternary polymer. 50 ammonium chloride
Mol% or more of copolymer, acrylamide / acrylonitrile / N-vinylacrylamidine hydrochloride / N-
Vinyl acrylamide / vinylamine hydrochloride / N-vinylformamide copolymer, dimethylamine / epichlorohydrin polycondensate, polyethylene polyamine / dimethylamine / epichlorohydrin polycondensate, acrylamide / diallylamine copolymer, etc. .

In the present invention, a fluorescent whitening agent and a dot adjusting agent are mixed in the ink receiving layer in order to further improve the sharpness of a printed image and obtain a high-quality image. Examples of the optical brightener include pyrene derivatives, coumarin derivatives, aminocoumarin derivatives, carpostyryl derivatives, dibenzoxazolyl derivatives, thiazole derivatives, imidazole derivatives, benzimidazole derivatives, imidazoline derivatives, pyrazoline derivatives, benzidine derivatives, stilbene derivatives, Distilbene derivatives, disulfonic acid derivatives, naphthalimide derivatives, distyrylbiphenyl derivatives and the like,
Particularly preferred are disulfonic acid derivatives, and specifically, fluorescent-85, fluorescent-86, fluorescent-90, 4,4′-bis [2-sodiumsulfanyl-4-di (hydroxyethyl ) Amino-
1,3,5-triazinyl- (6) -amino] stilbene-2,2'-disulfonate.

Examples of the dot adjusting agent include a reinforced rosin sizing agent, a petroleum resin sizing agent, an emulsion sizing agent, a reactive sizing agent such as alkenyl succinic anhydride, a self-fixing cationic resin sizing agent, a wax emulsion, and silicones. Or various latexes used in adhesives. Further, in the present invention, if necessary, a preservative such as benzimidazolyl carbamic acid methyl ester and allyl methanol mono (poly) hemifomal is appropriately added to form a coating liquid for an ink receiving layer, and a blade coater, an air knife coater, a curtain coater, Bar coater,
After coating / drying the sheet-like support with a coating method such as a gravure coater or a roll coater so that the coating amount on one side is 3 to 30 g / m ² (dry weight solid content), the other side is further coated. 3-30 g / m ² (dry weight solids) on the surface
After coating and drying, ink receiving layers were provided on both sides.

[0036]

The preferred embodiments of the present invention and the excellent effects thereof will be specifically described below with reference to the most typical examples. In the following, all parts are parts by weight, and all percentages are by weight.
It is.

[Preparation of Support] LBKP (CSF 350 ml) 90 parts NBKP (CSF 350 ml) 10 parts Calcined kaolin (whiteness 92%, particle diameter 2 μm or less 90%, oil absorption 110 g / 10 0 g) 20 parts 50% rosin size emulsion 3.4 parts 50% sulfuric acid band aqueous solution 4.2 parts Polyacrylamide solution 0.005 parts Amphoteric starch 2 parts

After forming a 1% slurry of the above composition,
A size press is performed with an aqueous solution of oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .: MS-3800) so as to have an adherence amount of 0.5 g / m ² (dry weight solid content) on both sides to obtain a support having a basis weight of 200 g / m ^2. Was.

[Preparation of Ink-Receiving Layer] 40 parts of a 40% aqueous solution of sodium polyacrylate (manufactured by Toagosei Chemical Industry Co., Ltd .: T-40) 1.5 parts Amorphous synthetic silica powder (manufactured by Tokuyama: Fine Seal X-37B, average particles) Diameter 3.7 μm) 70 parts Amorphous synthetic silica powder (Mizukasil P-78D, manufactured by Mizusawa Chemical Industries, average particle size 7.5 μm) 30 parts Water for silica dispersion 454 parts 25% fluorescen-90 aqueous solution 10 parts 10% Silanol-modified polyvinyl alcohol aqueous solution (Kuraray: R-1130, degree of polymerization 1700, degree of saponification 98.5 mol%) 280 parts acrylamide / acrylonitrile / N-vinylacrylamidine hydrochloride / N-vinylacrylamide / vinylamine hydrochloride / N -30% aqueous solution of vinylformamide copolymer 70 parts 55% ethylene / acetic acid vinyl Nyl copolymer emulsion (Sumitomo Chemical: Sumikaflex S400) 18 parts

The above composition was used as a coating liquid for an ink receiving layer.
Next, the basis weight of 200 g / m obtained above ^TwoOn one side of the support
The coating amount of the coating liquid was 7.5 g /
m^Two(Dry weight solids) after coating and drying
The other side has a coating amount of 7.5 g / m.^Two(Dry weight solid
Coating and drying so that it becomes the shape component) and ink receiving layer on both sides
Was provided.

Example 1 A 1% aqueous solution of the compound of the formula (5) (m + n = number of moles of ethylene oxide added: 10 mol) was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 2 A 1% aqueous solution of the compound of the above formula (m + n = 10 moles of ethylene oxide added) was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 3 A 1% aqueous solution of the compound of the above formula (m + n = 3 moles of ethylene oxide added) was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solids), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 4 A 1% aqueous solution of the compound of the above formula (m + n = the number of moles of ethylene oxide added: 30 mol) was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 5 A 1% aqueous solution of the compound of formula 10 was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 6 A 1% aqueous solution of the compound of formula 14 was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Example 7 A 1% aqueous solution of the compound of formula 18 was prepared. Next, the aqueous solution was coated and dried on both sides of the ink receiving layer obtained above using a gate roll coater so that the coating amount on both sides was 1.5 g / m ² (dry weight solid content), and then supercalendered. An ink jet recording sheet capable of double-sided printing was obtained.

Comparative Example 1 The sheet of Example 1 having only the ink receiving layers on both sides was subjected to a supercalender treatment to obtain an ink jet recording sheet capable of printing on both sides.

Comparative Example 2 An ink jet recording sheet capable of double-sided printing was obtained in the same manner as in Example 1 except that the aqueous 1% compound of formula 5 was replaced with water.

Comparative Example 3 [Production of Support] LBKP (CSF 350 ml) 90 parts NBKP (CSF 350 ml) 10 parts Talc (whiteness 88%, average particle diameter 11 to 46 μm, oil absorption 39 g / 100 g) 20 parts 50% rosin size Emulsion 4 parts 50% sulfuric acid band aqueous solution 5 parts Amphoteric starch 2 parts

After making a 1% slurry of the above composition,
A size press is performed with an aqueous solution of oxidized starch (manufactured by Nippon Shokuhin Kako Co., Ltd .: MS-3800) so as to have an adherence amount of 0.5 g / m ² (dry weight solid content) on both sides to obtain a support having a basis weight of 200 g / m ^2. Was. [Preparation of Ink Receiving Layer] Then, the coating amount for the ink receiving layer obtained in Example 1 was applied to one side of the talc-containing support having a basis weight of 200 g / m ² obtained above using an air knife coater. Coating to 7.5 g / m ² (dry weight solids)
After drying, the coating amount on the other side is 7.5 g / m.
After coating and drying to obtain a solid content of ² (dry weight solid content), a super calendar treatment was performed to obtain an ink jet recording sheet capable of printing on both sides.

Comparative Example 4 Water was applied to both sides of the ink receiving layer obtained in Comparative Example 3 by means of a gate roll coater and dried, and then subjected to a super calender treatment to obtain an ink jet recording sheet capable of printing on both sides.

The ink jet recording sheets capable of performing double-sided printing obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were measured and evaluated by the following methods.

Evaluation method << Print unevenness >> 100% cyan + magenta 10 on both sides of sheet by card printer (Canon P400CII)
The printing unevenness state at the time of 0% multicolor solid printing was visually judged.印: High quality with no printing unevenness on both sides. Δ: The printing unevenness is slight on both sides, but at a level that does not cause any problem in practical use. X mark: printing unevenness on both sides, not practical. << Opacity >> One sheet to be measured is placed on a standard black plate of a Hunter-type colorimeter, and the reflectance of white light is determined from the sheet side, which is defined as _R0 . Next, one sheet to be measured was placed on a standard white plate, and the reflectance of white light was determined from the sheet side, R was defined, and the opacity C was determined from the following equation. The higher the numerical value, the higher the opacity.

[0055]

(Equation 1)

<Offset of Printed Image> After the offset evaluation pattern was printed on one side of the sheet, the degree of the offset of the printed image was visually determined from the other side.印: Both sides have no set-off of the printed image and are excellent. X: Printed image looks pale on both sides and lacks practicality. << Ink Absorbency >> The number of seconds required for the ink printed with 100% cyan + 100% magenta solid-color solid ink to penetrate into the ink receiving layer and seemingly dry when both sides of the sheet were printed with a card printer (Canon P400CII) was measured.印: Both sides are dried almost simultaneously with printing. X: It takes 10 seconds or more for both sides to dry after printing, which is not practical. << Print Density >> The optical density of a black solid image printed on both sides of the sheet with a card printer (Canon P400CII) was measured with a Macbeth densitometer RD918. The larger the value, the higher the concentration and the better.

<< Bleeding of Printed Image >> The bleeding evaluation pattern printed on both sides of the sheet with a card printer (Canon P400CII) was visually judged.印: Very good without bleeding on both sides. X: Bleeding occurs on both sides, which is not practical.

The above evaluation results are summarized in Tables 1 and 2. The comprehensive evaluation means the following.印: Both sides are practically excellent. X: Both sides are not practical.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

As is clear from the above examples, according to the present invention, there was no printing unevenness, the ink absorbency was greatly improved, and a high-quality image free from image bleeding was obtained.

Claims (2)

[Claims] 1. A double-sided printable ink jet recording sheet comprising a sheet-like support containing calcined kaolin and an ink receiving layer containing a white pigment as a main component on both sides.
An ink jet recording sheet capable of double-sided printing, comprising simultaneously coating an acetylene glycol derivative represented by the following general formula (1) on both sides of an ink receiving layer. Embedded image [In the general formula (1), R _{1 to} R ₄ represent an alkyl group having 1 to ₄ carbon atoms. m + n = 3 to 3 moles of ethylene oxide added
Represents 0. ] 2. A double-sided ink jet recording sheet comprising a sheet-like support containing calcined kaolin and an ink receiving layer containing a white pigment as a main component on both sides,
An ink jet recording sheet capable of double-sided printing, comprising simultaneously coating an alkali metal salt of dialkyl sulfosuccinic acid represented by the following general formula (2) on both sides of the ink receiving layer. Embedded image [In the general formula (2), R ₅ and R ₆ represent an alkyl group having 4 to 12 carbon atoms. M represents an alkali metal salt of lithium, sodium or potassium. ]