JPH10291363A - Inkjet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink having excellent absorbability, a sharp shape of the ink, excellent color development of the ink, providing a stable high-quality print image, and further having transportability, blocking property, and water resistance. Provided is an ink jet recording sheet having an ink receiving layer excellent in water resistance and moisture resistance. SOLUTION: In an ink jet recording sheet provided with at least one ink receiving layer on one side of a base sheet used for ink jet recording, a resin component constituting the ink receiving layer is a porous hydrophilic polyurethane resin or An ink jet recording sheet comprising a porous hydrophilic polyurea resin or a porous hydrophilic polyurethane-polyurea resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording sheet, and more particularly to a recording sheet for ink-jet recording, which is excellent in absorptivity of aqueous ink, gives a stable high-quality printed image, and is excellent in transportability, blocking property, water resistance and moisture resistance. The present invention relates to an inkjet recording sheet having an ink receiving layer.

[0002]

2. Description of the Related Art An ink jet recording system employs various operating principles, for example, an electrostatic suction system, a system for applying mechanical vibration or displacement to ink by using a piezoelectric element, and heating and bubbling ink to utilize the pressure. It prints images, characters, etc. by flying fine droplets of ink and attaching it to a recording sheet such as paper by a method that performs high-speed printing, low noise generation, high-quality printing, and multicolor printing. It is rapidly spreading to various uses as a recording system that can perform the recording.

[0003] In such a recording sheet used for ink jet recording, the ink adhering to the recording sheet is prevented from bleeding or flowing so as not to deteriorate the print quality.
A substrate sheet such as paper provided with an ink-receiving layer containing various pigments and resins as main components so that ink can be quickly absorbed and clear ink dots are formed, or a porous sheet is provided on the paper itself. A recording sheet or the like containing a pigment has been proposed.

For example, JP-A-57-82085 discloses an ink-receiving layer comprising a water-soluble polymer in which an inorganic pigment and an organic pigment are used together as a pigment.
No. 8682 discloses that an ink receiving layer made of fine powder silica and a polyvinyl alcohol copolymer having a silanol group is provided.

[0005] However, as the performance of the ink jet recording apparatus has been improved and the use thereof has been expanded, such as high-speed, high-definition or full-color apparatus, it is required that the ink jet recording sheet also has the following advanced characteristics. It was started. (1) fast absorption of ink and large absorption capacity; (2) high color developability of the ink; (3) high surface strength of the ink receiving layer; and (4) water resistance of the support. And (5) the ink receiving layer has good image storability such as water resistance and ozone resistance after image printing, and (6) the ink receiving layer changes over time. That it does not.

Conventionally, a porous pigment or a water-soluble polymer having excellent ink absorbency has been used as a component of an ink receiving layer provided on an ink jet recording sheet in order to satisfy these requirements. It has been practiced and studied to use latex for the purpose of improvement, and to use water-resistant synthetic paper or plastic for the support itself.

However, when paper is used for the support or when only the aqueous polymer is used as the ink receiving layer, the water resistance of the ink receiving layer is poor, the printed portion is blurred, and the image clarity is poor. On the other hand, those using synthetic paper or a plastic film for the support or using latex for the resin of the ink receiving layer have problems in the adhesiveness between the ink receiving layer and the support, the ink absorbency and the drying property.

[0008]

The present invention relates to an ink jet recording sheet, and more particularly, to a stable high quality printed image which is excellent in absorptivity of a water-based ink, sharp in the shape of the ink, excellent in a color developing property of the ink. And transportability,
An object of the present invention is to provide an inkjet recording sheet having an ink receiving layer having excellent blocking properties, water resistance and moisture resistance.

[0009]

The above object is achieved by the present invention described below. That is, the present invention relates to an ink jet recording sheet provided with at least one ink receiving layer on one side of a base sheet used for ink jet recording, wherein the resin component constituting the ink receiving layer is a porous hydrophilic polyurethane resin. Alternatively, the present invention provides an inkjet recording sheet comprising a porous hydrophilic polyurea resin or a porous hydrophilic polyurethane-polyurea resin.

In general, the resolution of a printed image on an ink jet recording sheet depends on the amount of ink absorbed. If the ink absorbency is too high, the density of the printed image is reduced, and the sharpness and coloring are reduced. And the resolution becomes inferior. On the other hand, if the ink absorptivity is too low, the print density will be high, but there are drawbacks that the quality of the printed image is deteriorated due to density unevenness or bleeding, and the ink drying time is long.

The present inventors have conducted various studies in order to solve the problems of the conventional ink jet recording sheet as described above. As a result, the present inventors have found that the ink jet recording sheet has excellent water-absorbency and a sharp ink dot shape. , Excellent color development of ink,
It has been found that an ink jet recording sheet having an ink receiving layer which gives a stable, high-quality printed image and has excellent transportability, blocking properties, water resistance and moisture resistance can be obtained. According to the present invention, by using a porous hydrophilic resin for the ink receiving layer, the water absorption of the aqueous ink is increased by capillary action, and a high-quality printed image is provided,
An ink jet recording sheet having excellent performance such as transportability and blocking property is provided.

[0012]

Next, the present invention will be described in more detail with reference to preferred embodiments. In the ink jet recording sheet of the present invention, the resin component constituting the ink receiving layer is a porous hydrophilic polyurethane resin, a porous hydrophilic polyurea resin, or a porous hydrophilic polyurethane-polyurea resin.

In the present invention, the hydrophilic polyurethane resin or hydrophilic polyurea resin or hydrophilic polyurethane-polyurea resin forming the porous ink receiving layer can be obtained according to a conventionally known method. These preferable ones will be described more specifically. When a hydrophilic polyurethane resin, a hydrophilic polyurea resin and a hydrophilic polyurethane resin are used.
The polyurea resin is obtained by reacting a polyol and / or a polyamine with a polyisocyanate.

In the present invention, preferred polyols and polyamines have a terminal group of a hydroxyl group or an amino group,
It is a hydrophilic compound having a molecular weight of 200 to 8,000. Examples of those having a hydroxyl group at the terminal and having hydrophilicity include polyethylene glycol, polyethylene glycol / polytetramethylene glycol copolymer polyol,
Polyethylene glycol / polypropylene glycol copolymer polyol, polyethylene glycol adipate,
Examples include polyethylene glycol succinate, polyethylene glycol / poly-ε-caprolactone copolymer polyol, and polyethylene glycol / poly-valerolactone copolymer polyol.

Examples of the compound having a terminal amino group and having hydrophilicity include polyethylene oxide diamine, polyethylene oxide propylene oxide diamine, and the like.
Examples include polyethylene oxide triamine and polyethylene oxide propylene oxide triamine.

However, when synthesizing a hydrophilic polyurethane resin, a hydrophilic polyurea resin or a hydrophilic polyurethane-polyurea resin, other polyols having no hydrophilic chain or other polyols to maintain the water resistance of the ink receiving layer to be formed. It is also possible to copolymerize a polyamine, and a silicone polyol or perfluoroalkyl polyol.

As the organic isocyanate to be reacted with the above polyol, any known organic isocyanate can be used.
Alternatively, urethane prepolymers obtained by reacting these organic polyisocyanates with low molecular weight polyols or polyamines so as to be terminal isocyanates can also be used. Examples of the chain extender include any conventionally known low molecular weight diols and low molecular weight amines. The preferred molecular weight of the hydrophilic polyurethane resin or hydrophilic polyurea resin or hydrophilic polyurethane-polyurea resin obtained from the above materials is 10,000 to 500,000, and most preferably 20,000 to 200,000.

In the present invention, as a method for obtaining a porous ink receiving layer, a coating liquid containing the above-mentioned hydrophilic polyurethane resin, hydrophilic polyurea resin or hydrophilic polyurethane-polyurea resin is prepared, and the coating liquid is applied to a substrate. There is a method of forming a film. As a method of preparing a coating liquid containing the above resin and forming an ink receiving layer, the following representative methods can be mentioned.

(1) The above resin is emulsified (O / W or W /
O), a method of coating and forming a film on a base material, (2) giving the resin a partially dissolved portion and a non-dissolved portion in an organic solvent, and forming a resin dispersion by a difference in solubility with the organic solvent. A method of applying and forming a film on a substrate sheet,
(3) a method in which a solution obtained by dissolving the resin in an organic solvent having an affinity for water is applied to a base sheet, and the base sheet is immersed in water to remove the solvent to form a film; A method of preparing a dispersion in which another resin or an additive is dispersed in a resin, applying the dispersion to a base sheet, and selectively removing the other resin or the additive after film formation; A method in which an inorganic filler is dispersed in a resin to form a film, which is stretched to form a porous sheet, which is then adhered to a base sheet. In addition, even if it is a method other than the above, if the porous ink receiving layer can be obtained, the other method can also be applied to the present invention.

As the base material of the ink jet recording sheet of the present invention, paper, plastic film, glass, cloth,
Wood, metal, etc. are used. Examples of the paper include high quality paper, medium quality paper, coated paper, cast coated paper, and the like. Examples of the plastic film include sheets of 50 to 250 μm such as polyester, cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, polyamide, polystyrene, polyethylene, and polymethyl methacrylate.
Further, if necessary, a primer layer for imparting adhesiveness to the substrate, or a curl preventing layer or a lubricating layer for improving the coefficient of friction may be provided on the back surface of the substrate sheet on the non-accepting layer side.

As the resin component constituting the ink receiving layer, the above-mentioned resin alone may be used. However, depending on the composition of the inkjet ink, a water-soluble resin is used in order to further impart or adjust hydrophilicity and / or water absorbency. Polymers may be used in combination. Examples of the water-soluble polymer used here include polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, CMC,
Examples include cellulose derivatives, polyvinylpyrrolidone, starch, cationic starch, gelatin, casein, acrylic acid-based polymers, and the like.

For the purpose of further imparting water resistance and durability to the ink receiving layer and the printed image, the above resin may be used in combination with a hydrophobic polymer. As the hydrophobic polymer used here, polyester resin, polyvinyl chloride resin, polystyrene resin, polymethyl methacrylate resin, polycarbonate resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, acrylonitrile-styrene copolymer resin, Commonly used synthetic resins such as polyvinyl butyral resin, polyamide resin, epoxy resin, urea resin, melamine resin and the like can be mentioned.

Further, inorganic or organic pigments or resin particles can be added for the purpose of improving the ink absorbency, fixing property, color developing property, blocking property and water resistance of the ink receiving layer. Examples of pigments and resin particles used include, for example, kaolin, delamikaolin, aluminum hydroxide, silica, diatomaceous earth, calcium carbonate, talc, titanium oxide, calcium sulfate, barium sulfate, zinc oxide, alumina, calcium silicate, magnesium silicate, Mineral pigments such as colloidal silica, zeolite, bentonite, sericite, lithopone, porous pigments and polystyrene resins,
Urea resin, acrylic resin, melamine resin, benzoguanamine resin, polyurethane resin, other organic pigments and other fine particles, porous fine particles, and known pigments and resin particles such as hollow particles, according to the quality design of the inkjet recording sheet One or two or more kinds are appropriately used. in this case,
These pigments and resin particles are used in an amount of 0 to 95% by weight, preferably 10 to 90% by weight of the total solids of the resin composition.

Further, if necessary, a thickener, a releasing agent, a penetrating agent, a wetting agent, a thermal gelling agent, a sizing agent, a defoaming agent, a defoaming agent may be contained in the ink receiving layer in addition to the resin and the pigment. Agents, foaming agents, coloring agents, optical brighteners, ultraviolet absorbers, antioxidants, quencher agents, preservatives, antistatic agents, crosslinkers, dispersants, lubricants,
Various auxiliaries such as a plasticizer, a pH adjuster, a fluidity improver, a solidification accelerator, and a waterproofing agent can be appropriately compounded.

The ink jet recording sheet of the present invention comprises:
Depending on the method for forming the porous ink receiving layer, the porous ink receiving layer can be obtained by coating or laminating the substrate. The thickness of the formed porous ink layer is preferably from 1 to 2,000 μm. If the thickness is less than 1 μm, the ink absorption becomes insufficient, and a high-quality printed image cannot be obtained. If the thickness is 2,000 μm or more, the density may decrease due to the thickness, and the ink receiving layer may be broken or curled. Problems are more likely to occur.

[0026]

Next, the present invention will be described more specifically with reference to examples and comparative examples. It should be noted that “part” or “%” in the text is based on weight. Example 1 (Method by emulsification: O / W type) 70 parts of polytetramethylene glycol (molecular weight: 1,970), 230 parts of polyethylene glycol (molecular weight: 2,040) and 76 parts of water-added MDI to 2 parts of trimethylolpropane And add
The reaction was performed at 90 ° C. for 5 hours to obtain a prepolymer of terminal isocyanate. When the free isocyanate groups of the obtained product were quantified, the theoretical value was 2.65%, whereas the measured value was 2.44%.

To 100 parts of the obtained prepolymer, 30 parts of toluene and 2 parts of a surfactant (Emulgen, manufactured by Kao) were added and uniformly dissolved, and then 3.4 parts of isophoronediamine was dissolved in 30 parts of water. The aqueous solution is slowly added at room temperature (24 ° C.) while the solution is being rapidly stirred at about 6,000 rpm. After completion of the addition, water 370
Milky white polyurethane having an average molecular weight of about 120,000
A polyurea resin dispersion was obtained.

A dispersion obtained by adding 1 part of an anionic foam stabilizer (manufactured by San Nopco) to 100 parts of this dispersion and stirring with a homomixer to form uniform air bubbles was synthesized to a thickness of 80 μm. Paper (trade name; YUPO FPG-80)
/ Oji Yuka Synthetic Paper Co., Ltd.) on a solid content of 30 g / m
^The resultant was dried by coating with a bar coater so as to obtain No. ^2, and an inkjet recording sheet of the present invention having a uniform porous ink receiving layer was obtained.

Example 2 (Method by emulsification: W / O type) 50 parts of polytetramethylene glycol (molecular weight: 1,020), 150 parts of polyethylene glycol (molecular weight 2,040) and 6 parts of ethylene glycol were mixed with 350 parts of methyl ethyl ketone. , And add 54 parts of diphenylmethane diisocyanate with good stirring at 70 ° C. After the addition was completed, 257 parts of methyl ethyl ketone was further added and reacted at 80 ° C. for 6 hours to obtain a polyurethane resin solution having an average molecular weight of 98,000 and a solid content of 30%.

Next, 16 parts of a urethane emulsifier and 172 parts of toluene were added, and water
90 parts were added to obtain a milky white polyurethane resin dispersion. This dispersion was coated on a synthetic paper having a thickness of 80 μm (trade name; YUPO FPG-80 / Oji Yuka Synthetic Paper Co., Ltd.) using a bar coater so as to have a solid content of 30 g / m ² . First, drying was performed at 60 ° C. and then at 130 ° C. to obtain an inkjet recording sheet of the present invention having a uniform porous ink receiving layer.

Example 3 (Method based on difference in solubility) 200 parts of polyethylene glycol (molecular weight 2,040) and 15 parts of 1,4-butanediol were mixed with 250 parts of toluene and 250 parts of methyl ethyl ketone.
And 66 parts of diphenylmethane diisocyanate is added with good stirring at 70 ° C. After the addition is completed, 340 parts of methyl ethyl ketone are further added, and the mixture is reacted at 80 ° C. for 6 hours. As the reaction proceeds, the solution becomes milky white.
Thereafter, the mixture was cooled to room temperature with stirring to obtain a milky white polyurethane resin solution in which fine particles of 1 to 3 μm having a solid content of 25% were uniformly dispersed. This solution was applied and dried at a solid content of 30 g / m ^{2 in the same} manner as in Example 1 to obtain an inkjet recording sheet of the present invention having a uniform porous ink receiving layer.

Example 4 (Method by immersion in water) Polyethylene oxide (Texaco Chemical, Jeffamine ED; molecular weight 2,000)
0) Dissolve 200 parts and 10 parts of propylenediamine in 350 parts of dimethylformamide, and slowly melt 61 parts of water-added MDI in 280 parts of dimethylformamide while thoroughly stirring at an internal temperature of 0 to 5 ° C. The reaction was performed dropwise. After the completion of dropping, gradually raise the internal temperature to 50
When the temperature reached ° C, the mixture was further reacted for 5 hours to obtain a pale yellow transparent polyurea resin solution having an average molecular weight of 120,000 and a solid content of 30%. This solution was coated on a synthetic paper with a bar coater at a solid content of 30 g / m ^{2 in the same} manner as in Example 1 and dimethylformamide / water (= 1/40) at 40 ° C.
After dipping in the bath of 1) and drying, an ink jet recording sheet of the present invention having a uniform porous ink receiving layer was obtained.

Example 5 Polytetramethylene glycol (molecular weight; 1,020)
40 parts, polyethylene glycol (molecular weight 2,040)
160 parts, 1,4-butanediol 8 parts and diphenylmethane diisocyanate 52 parts were bulk-polymerized. 35 parts of the obtained thermoplastic polyurethane resin having a molecular weight of 78,000 and 65 parts of stearyl alcohol were combined with 35 m in diameter (Φ).
m while extruding at 190 ° C continuously with a width of 400 m.
The sheet was extruded from a T die having a die gap of 1 mm and a die gap of 1 mm to obtain a sheet having a thickness of 80 μm. The obtained sheet is immersed in a mixed solution of water / dimethylformamide (= 3/7) to remove the stearyl alcohol in the sheet, and then to a synthetic paper with a polyester-based adhesive (Polyester; Nippon Synthetic Chemical). By performing a one-sided heat treatment with a heating roller having a bonding surface temperature of 130 ° C., an inkjet recording sheet of the present invention having a uniform porous ink receiving layer having a thickness of 30 μm was obtained.

Comparative Example 1 A polyurethane-polyurea resin dispersion obtained in the same manner as in Example 1 was applied on synthetic paper without forming air bubbles, dried at 130 ° C. for 2 minutes, and dried to receive a transparent ink. An ink jet recording sheet having a layer formed thereon was obtained.

Comparative Example 2 A pale yellow transparent polyurethane resin solution was obtained in the same manner as in Example 3, except that methyl ethyl ketone as a solvent was replaced with dimethylformamide. This solution was applied on a synthetic paper and dried to obtain an ink jet recording sheet having a transparent ink receiving layer formed thereon.

COMPARATIVE EXAMPLE 3 The polyurea resin solution of Example 4 was applied on synthetic paper, and then dried at 130 ° C. for 3 minutes without immersion in a dimethylformamide / water bath to form an ink jet having a transparent ink receiving layer. A recording sheet was obtained.

COMPARATIVE EXAMPLE 4 The thermoplastic polyurethane resin obtained by bulk polymerization in Example 5 was treated with T without adding stearyl alcohol.
The sheet obtained by the die processing was bonded to synthetic paper to obtain an ink jet recording sheet having a transparent ink receiving layer formed thereon.

The nine types of sheets obtained as described above were printed and recorded using an ink jet printer that records and prints with a water-soluble dye ink using four colors of yellow, magenta, cyan and black. The items were evaluated. "Blocking property" An untreated polyethylene terephthalate film was left on the ink receiving layer at a load of 0.29 MPa and a temperature of 40 ° C for 1 day, and then the blocking property was evaluated. ：: No blocking property △: Slight blocking property ×: Blocking property

"Printer transportability" The printer transportability at the time of printing and recording with an ink jet printer was evaluated. ：: Good transportability △: Slight noise generation ×: Poor transportability

"Ink Absorbency" The evaluation of ink absorbency is as follows.
The number of seconds until the printed ink dries was measured. ：: 5 seconds or less △: 6 to 10 seconds ×: 11 seconds or more

"Color clarity" The color clarity was determined by visually observing the color clarity of the obtained color image after printing a color image with the above printer. ○: good △: normal ×: bad

"Bleeding" Bleeding was visually observed for the degree of bleeding and run-off of ink at the overlapping printing boundary between magenta and cyan. ○: good △: normal ×: bad

"Water resistance of ink receiving layer" Water was applied to the ink receiving layer, and the peeling state of the ink receiving layer when water was wiped off at a constant finger pressure was evaluated. ○: No change △: Slight change ×: Peel off

[0044]

[Table 1]

[0045]

As described above, the resin component constituting the ink receiving layer is made of a porous hydrophilic polyurethane resin, a porous hydrophilic polyurea resin, or a porous hydrophilic polyurethane resin.
The ink jet recording sheet made of polyurea resin is excellent in ink absorbency and coloring property, gives a stable high-quality printed image, and further has transportability, blocking property, water resistance and moisture resistance of the ink receiving layer and the printed image. Excellent.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Ken Kawaguchi 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Inside Dai-Niseika Chemical Industry Co., Ltd. (72) Inventor Katsuyuki 1-7-6 Nihonbashi Bakurocho, Chuo-ku, Tokyo (72) Inventor Motoaki Umezu 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Inside Dai-Nichisei Chemical Co., Ltd.

Claims (1)

[Claims] 1. An ink jet recording sheet having at least one ink receiving layer provided on at least one surface of a substrate sheet, wherein the resin component constituting the ink receiving layer is a porous hydrophilic polyurethane resin or a porous hydrophilic resin. An ink jet recording sheet comprising a polyurea resin or a porous hydrophilic polyurethane-polyurea resin.