JP2010125610A - Binder composition for inkjet recording medium, coating composition for inkjet recording medium, inkjet recording medium, and method for manufacturing inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a binder composition for an inkjet recording medium which is excellent in printing density, vividness of printed image, and ink bleeding resistance in addition to in glossiness, ink absorption property, and water resistance. <P>SOLUTION: The binder composition for the inkjet recording medium is formed by polymerizing vinyl unsatulated monomer mixture containing vinyl unsatulated dicarboxylic acid monomer such as itaconic acid in the presence of alcoholic hydroxilated water-soluble high polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a binder composition that gives an ink jet recording medium excellent in print density, sharpness of printed image, and ink bleeding resistance in addition to glossiness, ink absorbability and water resistance, and the above-mentioned binder composition for ink jet recording medium and pigment. The present invention relates to an inkjet recording medium coating composition, an inkjet recording medium having a layer formed by coating the inkjet recording medium coating composition, and a method for producing the inkjet recording medium.

In the ink jet recording method, ink droplets flying from nozzles are attached to a recording medium, and characters, images, and the like are recorded on the recording medium. The recording method is easy to increase in speed and multicolor, does not require processing such as development and fixing, and is rapidly spreading as a recording method for recording devices such as printers and plotters. The recording medium used in the recording method is usually produced by applying an aqueous resin composition onto a support such as paper and drying to form an ink receiving layer.
The first monomer was polymerized in the presence of a nonionic surfactant and an anionic surfactant to give an ink jet recording medium having high gloss, ink absorption and water resistance, and then obtained. A latex for an ink jet recording medium in which an alcoholic hydroxyl group-containing water-soluble polymer compound having a hydrophobic group and a second monomer are added to the latex and the polymerization is continuously produced has been studied (for example, see Patent Document 1). ). In recent years, there has been a demand for a binder composition that provides a recording medium having excellent print density, sharpness of printed images, and ink bleeding resistance in addition to glossiness, ink absorbability, and water resistance. However, such a binder composition for inkjet recording media has not been provided.
JP 2008-213368 A

  The problem to be solved by the present invention is to provide a binder composition that gives a recording medium excellent in print density, sharpness of printed image and ink bleeding resistance in addition to glossiness, ink absorption and water resistance. Another problem to be solved by the present invention is formed by coating the inkjet recording medium coating composition containing the inkjet recording medium binder composition and the pigment, and the inkjet recording medium coating composition. An ink jet recording medium having a layer and a method for producing the ink jet recording medium are provided.

As a result of diligent research, the inventors of the present invention carried out emulsion polymerization of a vinyl unsaturated monomer mixture containing a vinyl unsaturated dicarboxylic acid monomer in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound. It has been found that the resulting composition solves the above problems, and has completed the present invention.
The binder composition for ink jet recording media of the present invention is obtained by polymerizing a vinyl unsaturated monomer mixture containing a vinyl unsaturated dicarboxylic acid monomer in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound. It is done. In a preferred embodiment of the binder composition for an inkjet recording medium of the present invention, the vinyl unsaturated monomer mixture comprises 1 to 20% by mass of the vinyl unsaturated dicarboxylic acid monomer and 80 to 99% by mass. It consists of another vinyl type unsaturated monomer, and 3-45 mass parts of said alcoholic hydroxyl group containing water-soluble polymer compounds are used with respect to 100 mass parts of said vinyl type unsaturated monomer mixture. A preferred vinyl unsaturated dicarboxylic acid monomer is itaconic acid. In another preferred embodiment of the binder composition for inkjet recording media of the present invention, the alcoholic hydroxyl group-containing water-soluble polymer compound has a hydrophobic group of 20% by mass or more based on the alcoholic hydroxyl group-containing water-soluble polymer compound. Including an alcoholic hydroxyl group-containing water-soluble polymer compound.

The coating composition for inkjet recording media of the present invention comprises the binder composition for inkjet recording media and a pigment.
The ink jet recording medium of the present invention has a layer formed by applying the ink jet recording medium coating composition of the present invention. Preferably, the layer formed by applying the coating composition for an inkjet recording medium of the present invention is the outermost layer of the inkjet recording medium of the present invention.
The method for producing an ink jet recording medium of the present invention includes a step of coating the ink jet recording medium coating composition of the present invention to form a coating film, and a step of calendering the coating film under heat and pressure.

  The binder composition for an ink jet recording medium of the present invention provides an ink jet recording medium having excellent print density, sharpness of printed image, and ink bleeding resistance in addition to glossiness, ink absorbability and water resistance.

  The binder composition for ink jet recording media of the present invention is obtained by polymerizing a vinyl unsaturated monomer mixture containing a vinyl unsaturated dicarboxylic acid monomer in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound. It is done.

  Specific examples of the vinyl unsaturated dicarboxylic acid monomer include fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride and the like. A preferred vinyl unsaturated dicarboxylic acid monomer is itaconic acid. Although the usage-amount of the said vinyl type unsaturated dicarboxylic acid monomer is not limited, The said said usage-amount is 1-20 mass% with respect to the said vinyl type unsaturated monomer mixture.

  Specific examples of other vinyl unsaturated monomers copolymerized with the vinyl unsaturated dicarboxylic acid monomer include olefins such as ethylene, propylene, 1-butene and isobutene; vinyl chloride, vinylidene chloride, fluoride Vinyl halide monomers such as vinyl and vinylidene fluoride; vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, isopropenyl acetate, vinyl versatate, etc .; styrene, α-methylstyrene, monochloro Aromatic vinyl monomers such as styrene, dichlorostyrene, monomethylstyrene, dimethylstyrene, trimethylstyrene, hydroxymethylstyrene, p-styrenesulfonic acid and its sodium salt or potassium salt; (meth) acrylic acid, crotonic acid, etc. Ethylenically unsaturated monocarboxylic acids Derivatives such as esters and amides; ethylenically unsaturated nitrile monomers such as (meth) acrylonitrile; 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene Conjugated dienes such as 2-ethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene; methyl vinyl ether, n-propyl vinyl ether Vinyl ether monomers such as isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether; allyl compounds such as allyl acetate, methallyl acetate, allyl chloride, methallyl chloride; vinyl silane compounds such as vinyl trimethoxysilane Vinyl pyridine, N- Vinyl heterocyclic compounds such as vinylpyrrolidone; One or more of these monomers are used. In the present invention, “(meth) acrylic acid” means “acrylic acid” and / or “methacrylic acid”, and “(meth) acrylonitrile” means “acrylonitrile” and / or “methacrylonitrile”. means.

  Preferred vinyl unsaturated monomers copolymerized with the above vinyl unsaturated dicarboxylic acid monomers are ethylenically unsaturated monocarboxylic acids and derivatives thereof. Specific examples of the ethylenically unsaturated monocarboxylic acid are acrylic acid, methacrylic acid, and crotonic acid. Specific examples of the ester derivative of ethylenically unsaturated monocarboxylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Ethylenically unsaturated monocarboxylic acids such as 2-ethylhexyl, decyl (meth) acrylate, dodecyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and carbon number 1 Esters with ~ 12 alcohols. Specific examples of amide derivatives of ethylenically unsaturated monocarboxylic acids include (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) acrylamide-2-methylpropanesulfonic acid and Its sodium salt.

  The polymerization method of the vinyl unsaturated monomer mixture containing the vinyl unsaturated dicarboxylic acid monomer is not limited to a specific method, but a preferred polymerization method is emulsion polymerization. The method for adding the monomer to the reaction vessel during the emulsion polymerization is not limited to a specific method. Specific examples of the addition method include (a) a method of adding monomers all at once, (b) a method of adding monomers continuously or intermittently according to the progress of emulsion polymerization, and (c) a monomer. Is added to react to a specific conversion rate, and then the remaining monomer is added continuously or intermittently. Any method of (a) to (c) may be employed. When the monomer is added, a monomer emulsion obtained by mixing the monomer with water and an alcoholic hydroxyl group-containing water-soluble polymer compound can be used. When the monomer mixture is added continuously or intermittently, the composition of the mixture may be constant or variable, and each monomer may be mixed and then added to the reaction vessel or added separately to the reaction vessel. May be. Furthermore, the monomer can be emulsion polymerized in the presence of seed particles made of a polymer. The used amount of the seed particles is 1 to 80 parts by mass with respect to 100 parts by mass of the vinyl unsaturated monomer mixture.

  Specific examples of the alcoholic hydroxyl group-containing water-soluble polymer compound include: vinyl alcohol polymers such as polyvinyl alcohol and various modified products thereof; saponified copolymers of acrylic acid, methacrylic acid or maleic anhydride and vinyl acetate; Cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, alkylhydroxyalkyl cellulose; starch derivatives such as alkyl starch, carboxymethyl starch, oxidized starch; gum arabic, tragacanth rubber; polyalkylene glycol and the like. One or more of these are used. Among these, from the viewpoint of quality stability and availability, a preferred alcoholic hydroxyl group-containing water-soluble polymer compound is a vinyl alcohol polymer. Specific examples of vinyl alcohol polymers include polyvinyl alcohol obtained by hydrolysis of polyvinyl acetate, polyvinyl alcohol having a hydrophobic group at the molecular end, cation-modified polyvinyl alcohol having a molecular end that is cation-modified, and a molecular end having anion-modified. Anion-modified polyvinyl alcohol and the like. One or more of these polyvinyl alcohols are used. In the present invention, the hydrophobic group means a hydrocarbon group having 5 or more carbon atoms (aliphatic group, alicyclic group, aromatic group).

  The amount of the alcoholic hydroxyl group-containing water-soluble polymer compound used is not limited to a specific range. The said preferable usage-amount is 3-45 mass parts with respect to 100 mass parts of said vinyl type unsaturated monomer mixtures. Preferably, the alcoholic hydroxyl group-containing water-soluble polymer compound includes an alcoholic hydroxyl group-containing water-soluble polymer compound having a hydrophobic group of 20% by mass or more based on the alcoholic hydroxyl group-containing water-soluble polymer compound. The weight average molecular weight of the alcoholic hydroxyl group-containing water-soluble polymer compound is not particularly limited, but is usually 1,000 to 500,000, preferably 2,000 to 300,000. When the molecular weight is less than 1,000, the dispersion stabilizing effect during polymerization is lowered. When the molecular weight is larger than 500,000, the viscosity of the reaction system becomes high and there is a possibility that the polymerization becomes difficult.

  The polymerization initiator used in the emulsion polymerization is not limited to a specific polymerization initiator. Specific examples of the polymerization initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthane hydro Peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t- Organic peroxides such as butyl peroxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate. A preferred polymerization initiator is an inorganic peroxide. These polymerization initiators can be used alone or in combination of two or more. Redox polymerization initiators in which these polymerization initiators are combined with a reducing agent such as sodium sulfite can also be used.

  The usage-amount of a polymerization initiator is 0.1-5 mass normally with respect to 100 mass parts of monomer mixtures used for emulsion polymerization, Preferably it is 0.5-3 mass. When emulsion polymerization is performed in multiple stages, even if the total amount of polymerization initiator to be used is added in the first stage, a part of the polymerization initiator to be used is added in the first stage, and the remainder is added in the second and subsequent stages. May be. The addition method of the polymerization initiator in each stage may be batch addition, continuous addition, or divided addition.

  Secondary materials such as molecular weight regulators, dispersants, chelating agents and the like that are usually used in emulsion polymerization can be added during the emulsion polymerization. The type and amount of the secondary material are not limited. When the emulsion polymerization is performed in a plurality of stages, the addition timing and addition method of the auxiliary material to be used are not limited as necessary.

  Specific examples of the molecular weight modifier include: α-methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, methylene bromide; tetraethylthiuram Sulfur-containing compounds such as disulfide, dipentamethylene thiuram disulfide and diisopropylxanthogen disulfide. These molecular weight modifiers can be used alone or in combination of two or more.

  The polymerization temperature at each stage during the emulsion polymerization is not limited to a specific range. The said polymerization temperature is 5-95 degreeC normally, Preferably it is 50-95 degreeC. The polymerization temperature at each stage may be different, and the polymerization temperature during the emulsion polymerization at each stage may change.

  Preferably, the pH of the binder composition for inkjet recording media of the present invention is adjusted to a range of 2.0 to 7.0. The method for adjusting the pH is not particularly limited, and is performed by adding a basic compound or an acidic compound to the binder composition. The basic compound is not particularly limited, but preferred basic compounds are ammonia and amine. Specific examples of the amine are trimethylamine, triethylamine, triethanolamine, dimethylethanolamine, diethylethanolamine, triisopropanolamine, butyldiethanolamine and the like. One or more of these basic compounds are used. Specific examples of other basic compounds are alkali metal hydroxides such as potassium hydroxide, sodium hydroxide and lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide. Specific examples of the acidic compound that lowers the pH of the binder composition are carbon dioxide, hydrochloric acid, nitric acid, sulfuric acid and the like. The usage-amount of the said basic compound and an acidic compound is selected so that pH can be set to the said range, and is not specifically limited.

  The volume average particle diameter of the particles contained in the ink jet recording medium binder composition of the present invention is usually 10 to 150 nm, preferably 30 to 130 nm.

  The coating composition for inkjet recording media of the present invention comprises the above-described binder composition for inkjet recording media and a pigment.

  Specific examples of the pigment include silica, alumina, calcium carbonate, magnesium carbonate, kaolin, talc, titanium oxide, zinc oxide, aluminum oxide, barium sulfate, calcium sulfate, magnesium silicate, aluminum silicate, diatomaceous earth, zeolite, and aluminum hydroxide. Inorganic pigments such as magnesium hydroxide; organic pigments such as hollow particles, styrene plastic pigments, and acrylic plastic pigments. A preferred pigment is an inorganic pigment, and a particularly preferred pigment is silica. The blending amount of the pigment is preferably in the range of 100 to 2,000 parts by mass, more preferably 200 to 1,500 parts by mass with respect to 100 parts by mass of the solid content of the binder composition for inkjet recording media.

  In addition to pigments, the coating composition for inkjet recording media of the present invention includes pigment dispersants, dyes, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, and penetrating agents. Additives such as fluorescent brighteners, UV absorbers, antioxidants, preservatives, antifungal agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, dye fixing agents, etc. . The usage-amount of the said additive is not limited to a specific range.

  The preparation method of the coating composition for inkjet recording media of the present invention is not particularly limited. In general, using a disperser, the binder composition for an inkjet recording medium and the pigment of the present invention, and other additives and water blended as necessary are mixed. The total solid content concentration of the coating composition for inkjet recording media of the present invention is usually 5 to 50% by mass, preferably 10 to 40% by mass.

  The ink jet recording medium of the present invention has a layer (coating film) formed by coating the above-mentioned ink jet recording medium coating composition on at least one surface of a support. The ink jet recording medium of the present invention may be configured such that a single ink-receiving layer is formed on a support by coating the ink jet recording medium coating composition of the present invention directly on the support. It is good also as a structure which formed the several layer containing a receiving layer. An anchor layer can be formed below the ink receiving layer, and a glossy layer can be formed on the ink receiving layer. Preferably, the coating film formed from the coating composition for inkjet recording media of the present invention is formed on the outermost surface of the inkjet recording medium of the present invention.

  The support constituting the inkjet recording medium is not particularly limited, and is appropriately selected according to the purpose of use of the inkjet recording medium and the recording apparatus. Specific examples of the support include base paper such as newspaper base paper, high-quality base paper, and medium base paper; coated paper in which polyvinyl alcohol, starch, etc. are coated on the base paper; a coating layer mainly composed of a pigment is provided. Coated paper such as coated paper, art paper, cast paper; synthetic paper (polypropylene resin-based multilayer film, paper coated with polyethylene on both sides of the paper); resin film such as polyester film and PVC film; A support made of glass or ceramic; Preferred supports are base paper, coated paper, and synthetic paper.

The method for applying the coating composition for an inkjet recording medium of the present invention on a support is not particularly limited. Specific examples of the coater used in the coating method include a roll coater, an air knife coater, a blade coater, a rod blade coater, a curtain coater, a bar coater, a die coater, and a gravure coater. After coating the coating composition for inkjet recording media on a support, it is usually heated at a temperature in the range of 50 to 150 ° C. and dried. The coating amount (after drying) of the coating composition for an inkjet recording medium of the present invention is not particularly limited, but is usually 1 to 50 g / m ² , preferably 3 to 30 g / m ² . The thickness (after drying) of the coating film is usually 10 to 40 μm.

  It is preferable that the coating film formed of the coating composition for an inkjet recording medium of the present invention is calendered under heat and pressure. The calendar process gives smoothness and gloss to the surface of the ink jet recording medium of the present invention.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to only these examples. In the following examples and comparative examples, parts and% are based on mass unless otherwise specified.
The measuring methods of various physical properties measured in the following examples and comparative examples are as follows.

(1) pH of binder composition
The pH of the binder composition was measured at 20 ° C. using a pH meter (pH METER M-12, manufactured by Horiba, Ltd.).

(2) Volume average particle diameter of particles in binder composition The volume average particle diameter of particles in the binder composition is measured using a light scattering diffraction particle size measuring device (LS-230, manufactured by Coulter, Inc.) of the binder composition. Based on the volume-based particle size distribution, the average particle size was calculated by arithmetic averaging.

(3) Solid content concentration of binder composition About 3 g of the binder composition was precisely weighed in an aluminum dish and then dried in a dryer at 105 ° C for 24 hours to volatilize water. The mass of the obtained dried product was measured, and the solid content concentration of the binder composition was calculated from the mass ratio.

(4) Viscosity of binder composition The viscosity of the binder composition was measured at 25 ° C using a B-type viscometer (Tokyo Keiki Co., Ltd.).

(5) Surface acid group amount and water phase acid group amount of the copolymer constituting the particles in the binder composition 50 g of the binder composition adjusted to a solid content concentration of 2% was washed with distilled water. Placed in a glass container. The said glass container was set to the solution conductivity meter (Kyoto Electronics Industry Co., Ltd. product CM-117, use cell type: K-121), and the said binder composition was stirred. Stirring was continued until the addition of hydrochloric acid was completed. 0.1N sodium hydroxide (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) is added to the binder composition so that the electrical conductivity of the binder composition is 2.5 to 3.0 mS. After the elapse of 6 minutes, the electrical conductivity of the binder composition (the electrical conductivity at the start) was measured. Next, 0.5 ml of 0.1 N hydrochloric acid (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added to the binder composition, and the electrical conductivity was measured after 30 seconds. This operation was repeated at 30 second intervals until the electrical conductivity of the binder composition was equal to or higher than the initial electrical conductivity.

The electric conductivity (mS) was plotted on the vertical axis, and the cumulative amount (mmol) of added hydrochloric acid was plotted on the vertical axis, and a graph having three inflection points shown in FIG. 1 was obtained. The values on the horizontal axis at the three inflection points were P ₁ , P ₂ , and P _{3 in} order from the smallest, and the value on the horizontal axis when the addition of hydrochloric acid was completed was P4. From the data of the approximate curve L1 is 0-P ₁ segment, from the data of the approximate curve L2 is P ₁ -P ₂ classification, approximation curve L3 from the data of the P ₂ -P ₃ division, the approximate curve L4 is P ₃ -P ₄ Each was obtained from the category data by the method of least squares. The horizontal coordinate of the intersection of L1 and L2 was A ₁ (mmol), the horizontal coordinate of the intersection of L2 and L3 was A ₂ (mmol), and the horizontal coordinate of the intersection of L3 and L4 was A ₃ (mmol). The surface acid group amount and water phase acid group amount per 1 g of the copolymer constituting the fine particles contained in the latex were determined by the following formula.
Surface acid group amount per 1 g of copolymer (mmol / g) = A ₂ −A ₁
Water phase acid group amount per 1 g of copolymer (mmol / g) = A ₃ −A ₂

(6) Gloss Incidence of the light reflectance (%) of the surface of the inkjet recording sheet and the printed portion using a variable angle gloss meter (GM-3D type manufactured by Murakami Color Research Laboratory Co., Ltd.) based on JIS Z8741. Measurement was performed under conditions of an angle of 60 and 75 degrees and a reflection angle of 60 and 75 degrees. The larger the value, the better the gloss.

(7) Print density Each ink of black (K), magenta (M), cyan (C), and yellow (Y) is applied to an ink jet recording sheet using an ink jet printer (PM-870C manufactured by Seiko Epson Corporation). Solid-printed. The print density of the solid part of each ink in the printed matter was measured using a Macbeth ink densitometer (D19C manufactured by Gretagmacbeth), and the print density for each ink was simply averaged. The higher the value, the darker the print density.

(8) Water resistance The characters of the black ink were printed using an inkjet printer (PM-870C manufactured by Seiko Epson Corporation), and water at 30 ° C. was dropped onto the printed portion and left for 1 hour. Thereafter, when water droplets remained, they were blotted with a waste cloth, and the printing state such as the surface state and bleeding was visually observed, and the water resistance was evaluated according to the following criteria.
A: Bleeding, almost no change in color density and surface condition is observed.
B: Smearing, color density and surface condition are observed to be reduced, but at a practical level.
C: Smearing, a decrease in color density and surface condition are observed, which is not a practical level.

(9) Ink absorbability After 5, 10, 15, 20, 25, and 30 seconds immediately after printing, a high quality paper is bonded to the print surface, and the transfer of the ink to the high quality paper is visually observed. Evaluation based on the criteria.
A: Transfer does not occur within 5 seconds.
B: Transfer does not occur within 5 seconds to 10 seconds.
C: Transfer does not occur within 10 seconds to 30 seconds.

(10) Sharpness of printed image Printing on an ink jet recording sheet is performed using an ink jet printer (PM-870C manufactured by Seiko Epson Corporation) under the conditions of 23 ° C. and relative humidity of 65%. The properties were evaluated visually according to the following criteria.
A: The printed image is very clear and the contrast is clear.
B: The printed image is clear but the contrast is not clear and blurred.
C: Printed image is not clear and blurred.

(11) Ink bleeding resistance Printing on an ink jet recording sheet is performed under conditions of 23 ° C. and relative humidity 65% using an ink jet printer (PM-870C manufactured by Seiko Epson Corporation). Evaluation based on the criteria.
A: Slight bleeding is observed with an optical microscope, but the bleeding does not affect the image quality.
B: A slight oozing is visually observed.
C: Bleeding is visually observed over the entire image, and the image quality is inferior.

Example 1
Production of Inkjet Recording Medium Binder Composition 115.0 parts of ion exchange water, 1.6 parts of sodium alkyldiphenyl ether sulfonate, 0.06 parts of sodium bicarbonate and 0.02 part of sodium ethylenediaminetetraacetate are added to a pressure resistant reactor. While stirring these, 0.06 part of 2,4-dinitrochlorobenzene, 0.06 part of t-dodecyl mercaptan, 15.2 parts of styrene and 0.8 part of methacrylic acid were added to the reaction system. Next, the inside of the reaction vessel was replaced with nitrogen, and 24.0 parts of 1,3-butadiene was added and emulsified. Thereafter, while stirring the reaction system, the temperature was raised to 52 ° C., and 0.12 part of potassium persulfate was added to start emulsion polymerization. The reaction was continued for another 3 hours from the time when the polymerization conversion reached 85%, and the reaction was terminated when the polymerization conversion reached 98%. Thereafter, unreacted monomers were removed under reduced pressure to obtain a polymer latex seed. The solid content concentration of the latex seed was 25.6%, and the volume average particle size of the particles in the latex seed was 54.5 nm.
203.0 parts of ion-exchanged water, polyvinyl alcohol (PVA-MP102 manufactured by Kuraray Co., Ltd.) having a hydrophobic group (C12 hydrocarbon group) at one end (hereinafter referred to as “PVA having a hydrophobic group”) 10 0.0 part, 27.5 parts of methyl methacrylate and 27.5 parts of butyl acrylate were added to another reaction vessel and stirred to obtain a monomer emulsion.

  After adding 10.3 parts of ion-exchanged water to the above latex seed and heating to 80 ° C. with stirring, 5.0 parts of itaconic acid was added and dissolved, and then 0.6 parts of potassium persulfate was ionized. An aqueous solution dissolved in 14.0 parts of exchange water and the monomer emulsion were added to start emulsion polymerization. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. The polymerization conversion rate of the obtained composition was 98%. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media. The physical properties are shown in Table 1.

Production of Coating Composition for Ink Receiving Layer 100 parts of wet silica (Fine Seal X-45 manufactured by Tokuyama Corporation) and 0.5 part of sodium polyphosphate were dispersed in ion-exchanged water. Next, 40 parts of polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd., degree of saponification of about 98.0 to 99.0 mol%, degree of polymerization of 1700) as a 10% aqueous solution is added to the dispersion for 30 minutes. By mixing, a coating composition for an ink receiving layer having a solid content concentration of 17% was obtained.

Manufacture of coating composition for inkjet recording medium 90 parts of acidic colloidal silica (Nissan Chemical Industries Co., Ltd. Snowtex O-40, solid content concentration 40%, particle size 25 nm, pH 3.9, viscosity 7.5 mPa · s) (In terms of solid content), alkaline colloidal silica Nissan Chemical Co., Ltd. Snowtex 50, solid content concentration 48%, pH 9.18, viscosity 27 mPa · s) 10 parts (in terms of solid content) and solid content 15 parts. An amount of the above-mentioned binder composition for an ink jet recording medium was added to a disperser and dispersed, and ion-exchanged water was added so that the solid content concentration was 33.6% to produce a coating composition for an ink jet recording medium. . The viscosity of the coating composition for inkjet recording media was 23 mPa · s.

Production of Inkjet Recording Sheet The above ink-receiving layer coating composition was coated on a high-quality base paper having a basis weight of 130 g / m ² using a wire bar so that the dry mass was 15 g / m ^{2 on} one side, and dried with hot air The coated paper A was obtained by drying at 120 ° C. for 60 seconds using a machine. Next, the above-mentioned coating composition for inkjet recording medium was coated on coated paper A using a wire bar so that the dry mass was 17.5 g / m ^{2 on} one side, and the temperature was 45 ° C. at 120 ° C. with a hot air dryer. The coated paper B was obtained by drying for 2 seconds. The coated paper B was conditioned overnight under an atmosphere of 23 ° C. and a relative humidity of 65%. Thereafter, the coated paper B whose humidity was adjusted was calendered twice using a mini calender under the conditions of 80 ° C. and 75 kg / cm to produce an ink jet recording sheet, and its performance was evaluated. The results are shown in Table 2.

Example 2
The same operation as in Example 1 was performed except that the production method of the binder composition for inkjet recording media was changed as follows, and the coating amount of the coating composition for inkjet recording media was changed as shown in Table 2. It was.
250.0 parts of ion-exchanged water, 10.0 parts of PVA having a hydrophobic group, 10.0 parts of polyvinyl alcohol having no hydrophobic group (PVA105 manufactured by Kuraray Co., Ltd.) (hereinafter referred to as “PVA having no hydrophobic group”) Then, 50.0 parts of methyl methacrylate and 45.0 parts of 2-ethylhexyl acrylate were added to the reaction vessel and stirred to obtain a monomer emulsion. While stirring the monomer emulsion, the temperature was raised to 80 ° C., 5.0 parts of itaconic acid was added and dissolved, and then 0.6 parts of potassium persulfate was dissolved in 20.0 parts of ion-exchanged water. The aqueous solution and the monomer emulsion were added to initiate emulsion polymerization. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media.

Example 3
The same operation as in Example 1 was performed except that the production method of the binder composition for inkjet recording media was changed as follows, and the coating amount of the coating composition for inkjet recording media was changed as shown in Table 2. It was.

A polymer latex seed was obtained by the same method as the method for producing the polymer latex seed obtained in Example 1.
Separately, 203.0 parts of ion-exchanged water, 10.0 parts of PVA having a hydrophobic group, 2.5 parts of itaconic acid, 18.6 parts of methyl methacrylate, 250.0 parts of ethyl acrylate and 6.4 parts of methyl acrylate The mixture was added to the reaction vessel and stirred to obtain a monomer emulsion.
After adding 10.3 parts of ion-exchanged water to the latex seed and heating to 80 ° C. while stirring, 7.5 parts of itaconic acid was added and dissolved, and then 0.6 parts of potassium persulfate was ionized. An aqueous solution dissolved in 14.0 parts of exchange water and the monomer emulsion were added to start emulsion polymerization. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. The polymerization conversion rate of the obtained composition was 98%. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media.

Comparative Example 1
The same operation as in Example 1 was performed except that the production method of the binder composition for inkjet recording media was changed as follows, and the coating amount of the coating composition for inkjet recording media was changed as shown in Table 2. It was.
Add 120.0 parts of deionized water, 0.7 parts of sodium lauryl sulfate, 2.0 parts of itaconic acid, 50.0 parts of methyl methacrylate and 45.0 parts of butyl acrylate to the reaction vessel, stir and A mass emulsion was obtained. Itaconic acid (3.0 parts) and sodium lauryl sulfate (0.3 parts) were added with 180.0 parts of ion-exchanged water, and the temperature was raised to 80 ° C. while stirring. The aqueous solution dissolved in the above and the monomer emulsion were added to initiate emulsion polymerization. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media.

Comparative Example 2
The same operation as in Example 1 was performed except that the production method of the binder composition for inkjet recording media was changed as follows, and the coating amount of the coating composition for inkjet recording media was changed as shown in Table 2. It was.
Add 196.0 parts of ion exchange water, 20.0 parts of PVA having no hydrophobic group, 52.0 parts of methyl methacrylate, 45.0 parts of butyl acrylate and 3.0 parts of methacrylic acid to the reaction vessel, and stir. A monomer emulsion was obtained. The temperature of 220.0 parts of ion-exchanged water is raised to 80 ° C., an aqueous solution in which 0.2 part of potassium persulfate is dissolved in 10.0 parts of ion-exchanged water and the monomer emulsion are added, and emulsion polymerization is started. It was. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media.

Comparative Example 3
The same operation as in Example 1 was performed except that the production method of the binder composition for inkjet recording media was changed as follows, and the coating amount of the coating composition for inkjet recording media was changed as shown in Table 2. It was.
170.0 parts of ion exchange water, 10.0 parts of PVA having a hydrophobic group, 10.0 parts of PVA having no hydrophobic group, 55.0 parts of methyl methacrylate and 45.0 parts of butyl acrylate are added to a reaction vessel, and stirred. Thus, a monomer emulsion was obtained. The temperature of 220.0 parts of ion-exchanged water is raised to 80 ° C., an aqueous solution in which 0.4 part of potassium persulfate is dissolved in 10.0 parts of ion-exchanged water and the above monomer emulsion are added to initiate emulsion polymerization. It was. The continuous addition of the monomer emulsion was completed over 150 minutes. After completion of the addition of the monomer emulsion, emulsion polymerization was performed for 120 minutes, and the reaction was terminated by cooling. Unreacted monomers were removed from the composition under reduced pressure, and the solid content concentration was adjusted to 24% to obtain a binder composition for inkjet recording media.

  The ink jet recording sheets obtained using the binder compositions for ink jet recording media of Examples 1 to 3 have excellent gloss, ink absorbability, water resistance, print density, print image sharpness and ink bleeding resistance. Was. Inkjet recording sheets obtained by using a binder composition for inkjet recording media produced by emulsion polymerization of a vinyl unsaturated monomer mixture in the presence of sodium lauryl sulfate have low white paper gloss and print gloss, and the ink bleeds. The resistance, the sharpness of the printed image, the water resistance and the ink absorption were also considerably low. Inkjet recording sheets obtained by using a binder composition for inkjet recording media produced by emulsion polymerization of a vinyl unsaturated monomer mixture that does not contain itaconic acid have low blank paper gloss and print gloss, and ink bleeding resistance. The sharpness, water resistance and ink absorption of the printed image were also low.

  The ink jet recording medium of the present invention is particularly useful as a recording medium using an ink jet recording method, but is also used as a sheet for water-based ink printing such as offset printing and flexographic printing.

Graph for determining surface acid group amount and water phase acid group amount

Claims (8)

A binder composition for ink jet recording media obtained by polymerizing a vinyl unsaturated monomer mixture containing a vinyl unsaturated dicarboxylic acid monomer in the presence of an alcoholic hydroxyl group-containing water-soluble polymer compound. The vinyl unsaturated monomer mixture comprises 1 to 20% by mass of the vinyl unsaturated dicarboxylic acid monomer and 80 to 99% by mass of other vinyl unsaturated monomers,
The binder composition for inkjet recording media according to claim 1, wherein 3 to 45 parts by mass of the alcoholic hydroxyl group-containing water-soluble polymer compound is used with respect to 100 parts by mass of the vinyl unsaturated monomer mixture. The binder composition for inkjet recording media according to claim 1 or 2, wherein the vinyl unsaturated dicarboxylic acid monomer is itaconic acid. The alcoholic hydroxyl group-containing water-soluble polymer compound contains an alcoholic hydroxyl group-containing water-soluble polymer compound having a hydrophobic group of 20% by mass or more based on the alcoholic hydroxyl group-containing water-soluble polymer compound. The binder composition for inkjet recording media described in any one of the above. The coating composition for inkjet recording media containing the binder composition for inkjet recording media as described in any one of Claims 1-4, and a pigment. An inkjet recording medium having a layer formed by coating the coating composition for an inkjet recording medium according to claim 5. The inkjet recording medium according to claim 6, wherein the outermost surface has a layer formed by coating the coating composition for an inkjet recording medium according to claim 5. Applying the ink jet recording medium coating composition according to claim 5 to form a coating film;
A method for producing an ink jet recording medium, comprising: a step of calendering the coating film under heat and pressure.

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