JP3192385B2 - Inkjet recording sheet - Google Patents

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 an ink which is excellent in absorptivity of an aqueous ink, gives a stable high-quality printed image, and is excellent in transportability, blocking properties, water resistance and moisture resistance. The present invention relates to an inkjet recording sheet having a 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 its pressure. Ink droplets are made to fly by a method and adhere to a recording sheet such as paper,
It is used for recording characters and the like, is capable of high-speed printing, generates little noise, and is rapidly spreading to various uses as a recording system capable of high-quality printing and multicolor printing.

In a recording sheet used for such an ink jet recording, the ink adsorbed on the recording sheet causes bleeding or flow, and the ink is absorbed by a support such as paper so that the printing quality is not impaired. A sheet provided with an ink receiving layer containing various pigments and resins as main components so that clear ink dots can be formed quickly, or a recording sheet in which a porous pigment is embedded in paper itself. Has been proposed.

For example, Japanese Patent Application Laid-Open No. 57-82085 discloses that an ink receiving layer composed of a water-soluble polymer is provided by using an inorganic pigment and an organic pigment together as a pigment. The publication 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) the ink absorption is fast and the ink absorption capacity is large; (2) the color development of the ink is high; (3) the surface strength of the ink receiving layer is high; and (4) the support has water resistance. (5) good image storability such as water resistance and ozone resistance after printing an image on the ink receiving layer, and (6) the ink receiving layer has It should not change over time.

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 proposed and studied to use latex for improvement, and to use a synthetic paper or plastic having water resistance for the support itself.

However, those using paper as the support or using only a water-soluble polymer as the ink receiving layer have poor water resistance, bleed the printed portion, and are inferior in image clarity. On the other hand, the use of synthetic paper or plastic film for the support or the use of latex for the resin of the ink receiving layer has problems in the adhesiveness between the ink receiving layer and the support, the ink absorbency and the drying property. .

[0008]

SUMMARY OF THE INVENTION The present invention provides a stable, high-quality printed image which is excellent in water-absorbing ink absorbency, sharp in the shape of ink dots, excellent in ink coloring, and further transported. It is an object of the present invention to provide an ink jet recording sheet having an ink receiving layer having excellent properties, blocking properties, water resistance and moisture resistance.

[0009]

The object of the present invention is achieved by the following present invention. That is, the present invention relates to an ink jet recording sheet having at least one ink receiving layer provided on one side of a base sheet used for ink jet recording, wherein a resin component constituting the ink receiving layer has a siloxane segment in the molecule. An ink jet recording sheet comprising a hydrophilic polyurethane resin, a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin or a hydrophilic polyamide resin having the following.

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. However, the resolution of the image 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 prolonged. The present inventors have conducted various studies in order to solve the problems of the conventional ink jet recording sheet as described above, and as a result, have been found to be excellent in water-based ink absorptivity, sharp in the shape of ink dots, It has been found that an ink jet recording sheet having an ink receiving layer which is excellent in coloring properties, gives a stable high-quality printed image, and is excellent in transportability, blocking properties, water resistance and moisture resistance can be obtained.

Although the introduction of a hydrophobic (water-repellent) siloxane segment into a resin structure is not expected to provide good results with respect to the absorption of aqueous inks, the introduction of a siloxane segment from a resin having a low siloxane content is difficult. Film surface
It is known that the siloxane component is completely covered with a siloxane component in a dry state, but immersed in a resin when immersed in water or the like, that is, it has an environmental response. [4] 227 (1991)
other). In other words, the present invention utilizes this phenomenon, and by appropriately controlling the siloxane content in the resin, the surface shows hydrophilicity due to environmental responsiveness when printing with the aqueous ink, and when dried, Alternatively, the surface after drying is covered with a siloxane component, and excellent performance such as surface lubricity, water resistance and printer transportability can be obtained.

[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 has a siloxane segment in the molecule, and the resin is a hydrophilic polyurethane resin having a siloxane segment, and a hydrophilic polyurethane resin having a siloxane segment. Used as a hydrophilic polyurea resin, hydrophilic polyurethane-polyurea resin or hydrophilic polyamide resin.

In the present invention, the polysiloxane compound used for introducing the polysiloxane segment into the resin constituting the ink receiving layer contains one or more reactive groups such as an amino group and an epoxy group in the molecule. , Hydroxyl,
It is a polysiloxane compound having a mercapto group, a carboxyl group and the like. Preferred examples of the polysiloxane compound having a reactive group include the following compounds.

(1) Amino-modified polysiloxane compound

[0015]

(2) Epoxy-modified siloxane compound

(3) Alcohol-modified siloxane compound

[0018]

[0019]

[0020]

(4) Mercapto-modified siloxane compound

(5) Carboxyl-modified siloxane compound

[0023]

The polysiloxane compounds having a reactive organic functional group listed above are examples of preferred compounds used in the present invention, and the present invention is not limited to these exemplified compounds. Therefore, not only the compounds exemplified above, but also other compounds that are currently commercially available and can be easily obtained from the market can be used in the present invention.

The hydrophilic polyurethane resin, hydrophilic polyurea resin, hydrophilic polyurethane-polyurea resin or hydrophilic polyamide resin having the above-mentioned polysiloxane compound as a constituent segment can be obtained according to a conventionally known method. More specifically describing these preferable ones, preferred compounds for reacting with the above polysiloxane compound to obtain a hydrophilic polyurethane resin, a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin or a hydrophilic polyamide resin are: And a terminal group having a hydroxyl group or an amino group and a molecular weight in the range of 200 to 8,000.

Examples of the compound having a hydroxyl group at the terminal and having a hydrophilic property include polyethylene glycol, polyethylene glycol / polytetramethylene glycol copolymer polyol, polyethylene glycol / polypropylene glycol copolymer polyol, polyethylene glycol adipate, polyethylene glycol succinate, and polyethylene. Glycol / poly-ε-caprolactone copolymer polyol, polyethylene glycol / poly-valerolactone copolymer polyol, and the like.

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, in order to maintain water resistance, other polyols or polyamines having no hydrophilic chain can be used in combination during the production of the resin.

As the organic isocyanate to be reacted with the above-mentioned polyol and / or polyamine, any known organic isocyanate can be used, or these organic polyisocyanates can be reacted with low-molecular-weight polyols or polyamines so as to be terminal isocyanates. A urethane prepolymer or the like obtained by the above method can of course be used. As the chain extender, any conventionally known low molecular diol, low molecular amine or the like can be used.

A hydrophilic polyurethane resin having a siloxane segment in the molecule, obtained from the above material;
The preferred molecular weight of the hydrophilic polyurea resin, hydrophilic polyurethane-polyurea resin or hydrophilic polyamide resin is 1
10,000 to 500,000, most preferably a molecular weight of 20,000 to 20,000
100,000. These resins may be prepared without solvent or in an organic solvent. In the process, it is advantageous to prepare the above resin in an organic solvent for forming an ink receiving layer, because the resin solution can be used as it is.

The polysiloxane segment in these resins may be present in either a side chain (pendant) or in the main chain. The content of the polysiloxane segment is 0.1 to 10 parts by weight in 100 parts by weight of the resin. The proportion occupying parts by weight is preferred. When the polysiloxane segment in the resin is less than 0.1 part by weight, the desired properties of the recording sheet, such as water resistance, running property, and transportability, which are the intended objects of the present invention, become insufficient. If the amount exceeds 10 parts by weight, the water repellency of the polysiloxane segment is increased, and the water absorption performance of the aqueous ink and the quality of the printed image are deteriorated.

As the base sheet of the ink jet recording sheet of the present invention, paper, plastic film, glass, cloth, wood, metal and the like 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 in thickness, such as polyester, cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, polyamide, polystyrene, polyethylene, and polymethyl methacrylate. If necessary, a primer layer for imparting adhesiveness to the substrate sheet, 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 resin of the present invention may be used alone. However, the above-mentioned resin is preferably used in order to further impart or adjust hydrophilicity and / or water absorbency depending on the composition of the ink for ink jet recording. May be used in combination with a water-soluble polymer. Examples of the water-soluble polymer used here include polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethylcellulose, CMC, cellulose derivatives, polyvinylpyrrolidone, starch, cationic starch, gelatin, casein, acrylic acid polymers, and the like. .

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

Further, inorganic and organic pigments and resin particles are added to the ink receiving layer for the purpose of improving the ink absorbency, fixing property, color developing property, blocking property and water resistance of the ink receiving layer. Can be. Examples of pigments and resin particles used include, for example, kaolin, delamikaolin,
Mineral pigments such as aluminum hydroxide, silica, diatomaceous earth, calcium carbonate, talc, titanium oxide, calcium sulfate, barium sulfate, zinc oxide, alumina, calcium silicate, magnesium silicate, colloidal silica, zeolite, bentonite, sericite, lithopone, Ink jet recording sheet from known pigments and resin particles such as porous pigments, polystyrene resin, urea resin, acryl resin, melamine resin, benzoguanamine resin, polyurethane resin, other fine particles such as organic pigments, porous fine particles and hollow particles, etc. One type or two or more types are appropriately used depending on the quality design. In this case, the amount of the pigment or resin particles used is 0 to 95% by weight, preferably 10% by weight of the total solids of the resin composition.
It is blended in the range of up to 90% by weight.

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 water-proofing agent can be appropriately compounded.

The hydrophilic polyurethane resin, hydrophilic polyurea resin, hydrophilic polyurethane-polyurea resin, or hydrophilic polyamide resin having a siloxane segment in the molecule used in the present invention may be used alone or / and together with other resins in various organic solvents. Dissolved in water, the coating solution prepared using the above pigments and resin particles and various auxiliaries, gravure coat, direct or reverse roll coat, wire bar coat, air knife coat, curtain coat, blade coat, rod coat, Apply with a die coat or the like. Further, after coating, finishing is performed using a calendar such as a machine calendar, a super calendar, and a soft calendar.

The thickness of the ink receiving layer formed is 0.5 to 50 g / m ^{2, more} preferably 3 to 20 g in terms of dry weight.
/ M ² is good. The thickness of the ink receiving layer is 0.5 g / m
^When the thickness is less than ² , the ink absorption by the ink receiving layer becomes insufficient, and when the thickness exceeds 50 g / m ² , the obtained effect is saturated and uneconomical, and further, the ink receiving layer may be broken or curled. It will be easier.

[0038]

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. Reference Example 1 (Synthesis of polyurethane resin) Mixing 8 parts of polydimethylsiloxane polyol (molecular weight 3,200), 142 parts of polyethylene glycol (molecular weight 2,040) and 8 parts of ethylene glycol having the above structure, with 250 parts of methyl ethyl ketone and 145 parts of dimethylformamide A solution of 52 parts of water-added MDI in 100 parts of methyl ethyl ketone was gradually added dropwise while dissolving in a solvent and stirring well at 60 ° C. A resin solution was obtained. This solution is 550d at 35% solids
Pa. s (25 ° C.). The film formed from this solution had a breaking strength of 24.5 MPa, a breaking elongation of 450%, and a softening point of 105 ° C.

Reference Example 2 (Synthesis of polyurea resin) 5 parts of polydimethylsiloxane diamine (molecular weight 3,880) having the above structure, polyethylene oxide diamine (Jeffamine ED; molecular weight 2,000) 14
5 parts and 8 parts of propylenediamine are dissolved in 280 parts of dimethylformamide, and while thoroughly stirring the internal temperature at 0 to -5 ° C, a solution obtained by dissolving 47 parts of water-added MDI in 100 parts of dimethylformamide is gradually dissolved. The reaction was performed dropwise. After completion of the dropwise addition, the internal temperature was gradually raised, and when the temperature reached 50 ° C., the reaction was further continued for 5 hours to obtain a polyurea resin solution of the present invention. This solution has a solid content of 35% and 250 dP
a. s (25 ° C.). The film formed from this solution had a breaking strength of 27.6 MPa, a breaking elongation of 310%, and a softening point of 145 ° C.

Reference Example 3 (Synthesis of Polyurethane-Polyurea Resin) Polydimethylsiloxane diamine (molecular weight: 3,880) 5 of Reference Example 2
Part, polyethylene glycol (molecular weight 2,040) 14
Dissolve 5 parts and 8 parts of 1,3-butylene glycol in 74 parts of a mixed solvent of toluene and 197 parts of methyl ethyl ketone, and dissolve 42 parts of water-added MDI in 100 parts of methyl ethyl ketone while stirring well at 60 ° C. The resulting mixture was gradually added dropwise, and after completion of the addition, the mixture was reacted at 80 ° C. for 6 hours to obtain a polyurethane-polyurea resin solution of the present invention. This solution had a solids content of 35% and was 200 dPa. s (25 ° C.). The film formed from this solution had a breaking strength of 14.7 MPa, a breaking elongation of 450%, and a softening point of 90 ° C.

REFERENCE EXAMPLE 4 (Synthesis of polyamide resin) In a solution of 14.6 parts of adipic acid in 200 ml of anhydrous ethanol, 11.6 parts of polydimethylsiloxanediamine of Reference Example 2 and 194 parts of polyethylene oxide diamine (molecular weight: 2,000) were added. A solution of 100 ml of absolute ethanol containing is added at room temperature. After cooling, nylon salt precipitates. After filtration and drying, 160 parts of this nylon salt is dissolved in 40 parts of water, placed in an autoclave, replaced with nitrogen gas, and the valve is closed. Internal temperature is 2
When the temperature reaches 20 ° C. and the pressure reaches 1.5 MPa, the valve is opened to release steam, and heating is continued while maintaining this pressure.
The polycondensation is performed for 4 hours, and then the pressure is gradually reduced to normal pressure. After cooling, the product was taken out and dissolved in N-methyl-2-pyrrolidone. The solution had a solids content of 30% and was 50 dPa. s (2
5 ° C.). The film formed from this solution has a breaking strength of 7.8 MPa, a breaking elongation of 150%,
And the softening point was 140 ° C.

Reference Example 5 A polyurethane resin solution was obtained by using the same materials and the same formulation as in Reference Example 1 except that the polydimethylsiloxane polyol was not used in the formulation of Reference Example 1. This solution has a solids content of 35% and 50%.
0 dPa. s (25 ° C.). The film formed from this solution had a breaking strength of 26.5 MPa, a breaking elongation of 400%, and a softening point of 106 ° C.

REFERENCE EXAMPLE 6 A polyurea resin solution was obtained by using the same material and formulation as in Reference Example 2 except that polydimethylsiloxanediamine was not used in the recipe of Reference Example 2. This solution is 300d at 35% solids
Pa. s (25 ° C.). The film formed from this solution had a breaking strength of 28.0 MPa, a breaking elongation of 300%, and a softening point of 147 ° C.

REFERENCE EXAMPLE 7 A polyurethane-polyurea resin solution was obtained by using the same materials and formulation as in Reference Example 3 except that polydimethylsiloxane diamine was not used in the recipe of Reference Example 3. This solution has a solids content of 3.
220 dPa. At 5%. s (25 ° C.). The breaking strength of the film formed from this solution is 15.
0 MPa, elongation at break was 430%, and softening point was 88 ° C.

REFERENCE EXAMPLE 8 A polyamide resin solution was obtained in the same manner as in Reference Example 4 except that polydimethylsiloxane diamine was not used in the recipe of Reference Example 4. This solution has a solid content of 30% and 55 dP
a. s (25 ° C.). The film formed from this solution had a breaking strength of 8.0 MPa, a breaking elongation of 130%, and a softening point of 138 ° C.

Examples 1 to 40 40 parts of the resin obtained in Reference Examples 1 to 4, 100 parts of fine-particle synthetic amorphous silica (BET specific surface area: 300 m ² / g, manufactured by Mizusawa Chemical Industry) and a dispersant (sodium polypyrophosphate) ) 0.
Two parts were dispersed and mixed with a mixed solvent of methyl ethyl ketone / toluene, and the solid content was adjusted to 15% to obtain a coating liquid. The coating liquid is applied to a high-quality paper having a basis weight of 35 g / m ^{2 with} an air knife coater so that the coating amount is 10 g / m ² , and dried,
Super calendering was performed at a linear pressure of 200 kg / cm to form an ink receiving layer, which was used as a recording sheet of the present invention.

Comparative Examples 1 to 4 40 parts of the resin obtained in Reference Examples 5 to 8, 100 parts of fine-particle synthetic amorphous silica (BET specific surface area: 300 m ² / g, manufactured by Mizusawa Chemical Industries) and a dispersant (sodium polypyrophosphate) ) 0.
Two parts were dispersed and mixed with a mixed solvent of methyl ethyl ketone / toluene, and the solid content was adjusted to 15% to obtain a coating liquid. The coating liquid is applied to a high-quality paper having a basis weight of 35 g / m ^{2 with} an air knife coater so that the coating amount is 10 g / m ² , and dried,
Super calendering was performed at a linear pressure of 200 kg / cm to form an ink receiving layer, which was used as a recording sheet of a comparative example.

The eight types of sheets obtained as described above were printed and recorded by using an ink jet printer for printing and recording with a water-soluble dye ink using four colors of yellow, magenta, cyan and black. The items were evaluated. "Ink Absorption" The ink absorption was evaluated by measuring the number of seconds until the printed ink dries. ：: 5 seconds or less △: 6 to 10 seconds ×: 11 seconds or more

"Color Visibility" The color vividness was determined by visually observing the color vividness of the obtained color image after printing the color image with the above printer. ：: good Δ: normal ×: bad “bleeding” was visually observed for the degree of bleeding and run-out of the ink at the overlapping printing boundary portion between magenta and cyan. ○: good △: normal ×: bad

[Water Resistance of Receptive Layer] Water was applied to the ink receiving layer, and the state of peeling of the receiving layer when water was wiped off at a constant finger pressure was evaluated. ○: No change △: Slight change ×: Peeling After printing with the “water resistance of printed image” printer, the recording sheet was immersed in water (10 minutes), and then dried at room temperature and then bleeding and coloring of the recorded image Was visually observed. ：: No change △: Slight discoloration ×: Discoloration

The coating liquids obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were applied to a 100 μm PET film so that the thickness after drying became 20 μm, and a transparent sheet was prepared.
Similarly, printing and recording were performed by an ink jet printer, and the following items were evaluated. "Blocking" Untreated PE on resin coated surface
A T film was loaded at a load of 0.29 MPa and a temperature of 40 ° C.
After standing for a day, the blocking property was evaluated. ：: No blocking property Δ: Slight blocking property X: Blocking property “Printer transportability” The printer transportability at the time of printing and recording with an inkjet printer was evaluated. ：: Good transportability △: Slight noise generation ×: Poor transportability

[0052]

[Table 1]

[0053]

As described above, the hydrophilic polyurethane resin having a siloxane segment in the molecule, the hydrophilic polyurea resin, the hydrophilic polyurethane-polyurea resin and / or
Or, a recording sheet for inkjet using a hydrophilic polyamide resin as a resin component constituting the ink receiving layer is excellent in ink absorbency, color development, gives a stable high-quality printed image, furthermore, the ink receiving layer and Excels in transporting stamp images, blocking, water resistance and moisture resistance.

Continued on the front page (72) Inventor Katsutoshi Torii 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Inside Dainippon Seika Kogyo Co., Ltd. (72) Inventor Ken Kawaguchi 1-7-6 Nihonbashi Bakurocho, Chuo-ku, Tokyo Dainichisei Katsuyuki Fukui (72) Inventor Katsuyuki Fukui 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Daini Seika Kogyo Co., Ltd. (72) Inventor Motoaki Umezu 1-7-6 Nihonbashi Bakurocho, Chuo-ku, Tokyo Dainichisei (56) References JP-A-7-164731 (JP, A) JP-A-6-40146 (JP, A) JP-A-63-118286 (JP, A) JP-A-3-295682 (JP) , A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (2)

(57) [Claims] 1. An ink jet recording sheet having at least one ink receiving layer provided on at least one surface of a base sheet, wherein a resin component constituting the ink receiving layer is a hydrophilic polyurethane resin having a siloxane segment in a molecule. And a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin or a hydrophilic polyamide resin. 2. The ink jet recording sheet according to claim 1, wherein the siloxane segment accounts for 0.1 to 10 parts by weight based on 100 parts by weight of the resin.