JP2013039730A - Method of producing inkjet recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that can stably produce an inkjet recording material which can express meticulous images even at a high printing speed, and more specifically a method of producing an inkjet recording material which uses, as a binder, a PVA-based resin composition exhibiting high binder force even when small amount of the composition is added and having high water resistance, enables high viscosity of a binder water solution when mixing with porous inorganic particulates, does not use water-soluble basic compounds having hazardous properties or having possibilities of adverse effects on other additive medical agents and reduces change in the viscosity of application fluid after mixed.SOLUTION: The method of producing the inkjet recording material includes the steps of: mixing a water solution of a saponified substance of vinyl acetate-diacetone acrylamide copolymer with a crosslinking agent; adding a volatile ketone compound after passage of at least thirty minutes after the mixing to obtain mixture; and applying an ink receiving layer application fluid obtained by mixing the porous inorganic particulates with the obtained mixture to a support body. An ink receiving layer formed on the support body contains the porous inorganic particulate, the saponified substance of vinyl acetate-diacetone acrylamide copolymer and the crosslinking agent.

Description

  The present invention relates to a method for producing an ink jet recording material, and further relates to a method for producing an ink jet recording material which has excellent water resistance and is unlikely to crack during production.

  Inkjet recording is a method in which small droplets of ink are sprayed from nozzles and fixed on the surface of the recording medium to record characters, images, etc. Color printing is easy, running costs are low, and noise during printing It is widely used for printers in homes or offices because of its many advantages, such as being less. Recently, with the spread of digital cameras, it has been established as a recording method to replace silver salt photography, and ink jet recording materials such as printing directly on the surface of optical discs such as CD / DVD / BD are also used depending on the purpose. Various materials have been selected, and the required quality has become more sophisticated and diverse.

  As a constitution of the ink jet recording material, an ink receiving layer is provided on a support such as paper, a plastic sheet or a plastic disk. The ink receiving layer is made of a porous inorganic material such as silica or alumina bound with a hydrophilic resin binder. The porous inorganic material quickly absorbs ink, suppresses bleeding, and forms a perfect circle-like dot. By doing so, a fine image can be expressed. Here, the performance required for the binder resin is required to be (1) high affinity for the ink, (2) high binder power for the inorganic fine particles, and the binder resin is polyvinyl alcohol (hereinafter referred to as PVA). Abbreviated.) System resins are widely used.

  In recent years, ink jet recording systems have been required to have high expressive power, that is, higher definition of images and higher printing speed. In order to achieve such high-definition images, a method of increasing the amount of ink discharged per unit area of the recording material is taken, and the recording material is required to have an ability to absorb a larger amount of ink than before. ing. Therefore, it is necessary to increase the porosity of the ink receiving layer, and development is progressing in the direction of reducing the amount of the binder resin.

  On the other hand, regarding the problem of improving the printing speed, when printing at a high speed, the physical load on the surface of the recording material being conveyed by the printer increases, and a large amount of ink is absorbed in the wet state as described above to absorb a large load. Will take. In other words, in addition to the above (1) and (2), (3) the binder resin exhibits a higher binder strength when added in a small amount, and the ink-receiving layer surface does not crack during drying of the coating solution. (4) In order to ensure the porosity of the inorganic fine particles, it must be a highly viscous aqueous solution that does not easily penetrate into the porous fine particles at the coating liquid stage, and (5) water resistance that can provide high surface strength even when wet. Performance such as being high is further demanded.

  As a binder for the ink receiving layer of such an ink jet recording material, Patent Document 1 discloses a technique using PVA having a polymerization degree of 4000 or more. PVA having such a high degree of polymerization has a high binder strength and a high aqueous solution viscosity. Therefore, even when the amount of the binder is small, cracking during drying hardly occurs and the porosity of fine particles can be secured.

  However, the PVA has insufficient surface strength when wet, and the binder strength and aqueous solution viscosity are not sufficient. Furthermore, PVA with such a high degree of polymerization has a problem that production efficiency is extremely poor. The upper limit of the degree of polymerization of industrially produced PVA is about 4500, and PVA with a higher degree of polymerization is a method using special equipment or a method that sacrifices productivity (low yield). There is a problem that the production cost is extremely high and industrial disadvantageous.

  On the other hand, techniques using PVA and a boron compound are disclosed (for example, Patent Document 2 and Patent Document 3). This increases the viscosity of the PVA aqueous solution by using boric acid and / or borax as a cross-linking agent, and prevents the binder resin from penetrating into the porous inorganic fine particles, thereby ensuring the porosity of the inorganic fine particles, It is considered that even a small amount of use contributes to improvement of the binder strength and improvement of the surface strength when wet.

  Recently, however, boron compounds such as boric acid have been pointed out to be reproductive toxic, and have become difficult to use due to their toxicity and adverse effects on the environment, such as being listed as a candidate of high concern for the European Chemical Regulation (REACH). There is a need for PVA-based resin binders that have a cross-linking system to replace PVA / boron compounds.

  In response to these problems, the present inventors have proposed an ink jet recording material (Patent Document 4) using a saponified diacetone acrylamide-fatty acid vinyl ester copolymer and a hydrazine compound. Patent Document 5 proposes an ink jet recording medium containing an acetoacetate group-containing PVA resin and a polyhydric hydrazide compound.

  A binder obtained by reacting a PVA resin having a keto group with a crosslinking agent such as a hydrazine compound is excellent in water resistance, and an ink jet recording material having a high surface strength when wet is obtained. The porous inorganic fine particles have penetrated, and a large amount of ink is hardly absorbed, and the fineness of the image is not sufficient, and improvement has been desired. Further, since the binder resin itself permeates into the voids of the fine particles, the amount of the binder as a binder between the fine particles is small, and the problem that cracking at the time of drying and the like has not been completely solved.

  Furthermore, as a problem when using such a modified PVA-based resin and a crosslinking agent as a binder, the modified PVA and the crosslinking agent undergo a crosslinking reaction even in an aqueous solution. In particular, in the system of acetoacetate group-containing PVA resin and polyhydric hydrazide compound, the reaction speed of both is high, and therefore there is a problem of pot life that gelation occurs while the coating liquid for the ink receiving layer is applied. there were.

  On the other hand, the saponified diacetone acrylamide-fatty acid vinyl ester copolymer and the hydrazine compound have the same problem, but the diacetone acrylamide copolymer modified PVA proposed by the present inventors is soluble in the water-soluble hydrazine compound. The problem of pot life can be solved by using a method (Patent Document 6) in which an organic organic amine or ammonia coexists. As described in paragraph [0022] of Patent Document 6, in order to suppress a rapid reaction between diacetone acrylamide copolymer-modified PVA and a hydrazine compound, this method is preliminarily dissolved in an aqueous solution of diacetone acrylamide copolymer-modified PVA. The water-soluble hydrazine compound is added after the coexistence of the water-soluble organic amine or ammonia to increase the workable time.

  However, when porous inorganic fine particles are mixed with a mixed aqueous solution of saponified diacetone acrylamide-fatty acid vinyl ester copolymer obtained by this method, a hydrazine compound and a water-soluble organic amine or ammonia, the viscosity of the mixed aqueous solution is low. Therefore, since the binder resin and the cross-linking agent penetrate into the voids of the fine particles, there are problems that the amount of the binder that settles between the fine particles is reduced and the ink absorbability is lowered.

  As a method for solving these problems, the present inventors mixed an aqueous solution of a saponified vinyl acetate-diacetone acrylamide copolymer and a cross-linking agent, allowed to elapse for a certain time, and when the mixed aqueous solution reached a desired viscosity. Proposed a method for producing an ink jet recording material, in which a water-soluble basic compound such as an organic amine was added, and then an ink receiving layer coating liquid mixed with porous inorganic fine particles was coated on a support (Japanese Patent Application No. 2010-261801). .

  According to this method, the binder resin and the cross-linking agent can suppress the penetration of fine particles into the voids, and the ink receiving layer surface does not crack in the drying process, resulting in high productivity. The resulting ink jet recording material absorbs ink. Although adding water-soluble basic compounds increases the pH of the ink-receiving layer coating solution, there is a concern about the impact on the health of workers during production. In addition, the high pH may adversely affect the agents other than the binder and crosslinking agent added to the ink-receiving layer coating solution, and may adversely affect the color development of the ink during printing. There is a demand for a method that solves the above-described problems by a method that does not affect the pH of the layer coating solution.

Japanese Patent Laid-Open No. 7-117334 JP-A-11-20306 Japanese Patent Laid-Open No. 11-192777 JP-A-11-348417 JP 2001-213045 A Japanese Patent Laid-Open No. 10-87936

  An object of the present invention is to provide a method capable of stably producing an ink jet recording material capable of expressing a fine image even when the printing speed is high. More specifically, even when added in a small amount, it exhibits a high binder strength, and a PVA resin composition having high water resistance is used as a binder. When mixed with porous inorganic fine particles, the viscosity of the aqueous binder solution is high, and organic amines are used. It is an object of the present invention to provide a method for producing an inkjet recording material in which the viscosity change of the coating liquid is small even without using a basic compound such as the above.

  As a result of intensive research, the present inventors have found that an ink jet recording material having an ink receiving layer containing porous inorganic fine particles, a saponified vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent on a support. In the production method, an aqueous solution of a saponified product of vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent are mixed, and after mixing for at least 30 minutes, a mixed aqueous solution obtained by adding a volatile ketone compound and porous inorganic fine particles The inventors have found that the above-described problems can be solved at once by applying an ink-receiving layer coating liquid mixed with the above to a support, and have further studied and completed the present invention.

That is, the present invention relates to the following inventions.
[1] A step of mixing an aqueous solution of a saponified product of vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent, a step of obtaining a mixed solution by adding a volatile ketone compound after passing at least 30 minutes after the mixing, And an ink receiving layer coating liquid in which porous inorganic fine particles are mixed with the obtained mixed liquid is applied to a support, and the ink receiving layer formed on the support comprises porous inorganic fine particles, acetic acid A method for producing an ink jet recording material, comprising a saponified vinyl-diacetone acrylamide copolymer and a crosslinking agent.
[2] In a method for producing an ink jet recording material having an ink receiving layer containing porous inorganic fine particles, a saponified vinyl acetate-diacetone acrylamide copolymer and a cross-linking agent on a support, vinyl acetate-diacetone acrylamide A step of mixing an aqueous solution of a copolymer saponified product and a crosslinking agent, and after the resulting mixed solution has thickened, a volatile ketone compound is added to and mixed with the mixed solution, and then porous inorganic fine particles are added. A step of preparing an ink receiving layer coating solution by mixing, volatilization with respect to the viscosity (A) of the mixture solution of the saponified vinyl acetate-diacetone acrylamide copolymer and the crosslinking agent immediately after mixing the crosslinking agent. Viscosity of a mixture of a saponified vinyl acetate-diacetone acrylamide copolymer, a crosslinking agent and a volatile ketone compound ( Ratio) [(B) / (A)] The production method of the ink jet recording material, which is a 1.3 to 10.0.
[3] The inkjet recording according to [1] or [2], wherein the crosslinking agent is a compound having two or more functional groups selected from the group consisting of a hydrazino group, a hydrazide group, and a semicarbazide group. Material manufacturing method.
[4] The inkjet according to any one of [1] to [3], wherein the volatile ketone compound is at least one selected from the group consisting of acetone, methyl ethyl ketone, and methyl isopropyl ketone. Manufacturing method of recording material.
[5] The above-mentioned [1], wherein the addition amount of the volatile ketone compound is 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the saponified product of vinyl acetate-diacetone acrylamide copolymer. -The manufacturing method of the inkjet recording material in any one of [4].
[6] The viscosity of a 4 wt% aqueous solution measured by the method of JIS K-6726 (1994) of the saponified product of vinyl acetate-diacetone acrylamide copolymer is 10 to 100 mPa · s. The manufacturing method of the inkjet recording material in any one of said [1]-[5].

  In the method for producing an ink jet recording material of the present invention, the coating liquid for producing an ink receiving layer without adding a water-soluble basic compound such as an organic amine has excellent viscosity stability, and the ink in the drying step Since no cracks occur on the surface of the receiving layer, the productivity is high and industrially advantageous. Further, since the ink jet recording material produced by the production method of the present invention is excellent in ink absorbability, strength and water resistance, it is possible to display a fine image even when printing at high speed. Further, since the production method of the present invention does not use a boron compound, reproductive toxicity or the like does not become a problem, and there is a concern about the influence on the health of the production worker by reducing or eliminating the use amount of the basic compound. There is no safety. Furthermore, in the ink jet recording material obtained by the production method of the present invention, there is very little adverse effect on the color development of the ink during printing by reducing or eliminating the use amount of the basic compound.

Viscosity at 20 ° C. of a mixture of 8% by weight of vinyl acetate-diacetone acrylamide copolymer saponified product (DAVES), 0.4% by weight of adipic acid dihydrazide (ADH) and 0.8% by weight of acetone of Synthesis Example 1 below It is a figure which shows the measurement result with time.

  Hereafter, the manufacturing method of the inkjet recording material of this invention is demonstrated in detail.

  The saponified product of vinyl acetate-diacetone acrylamide copolymer used in the present invention (hereinafter abbreviated as DAVES) is obtained by copolymerizing vinyl acetate and diacetone acrylamide, and saponifying the resulting copolymer. It can manufacture by the well-known method of these.

  As the copolymerization method of vinyl acetate and diacetone acrylamide, known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization and the like can be adopted. Among them, solution polymerization using methanol as a solvent is industrial. Is preferable.

  As a saponification method of a polymer obtained by copolymerizing vinyl acetate and diacetone acrylamide, conventionally known alkali saponification and acid saponification can be applied. Among them, a methanol solution of the polymer or methanol and water, acetic acid An industrially preferred method is to add an alkali hydroxide to a mixed solution of methyl, benzene and the like to perform alcoholysis.

  The above-mentioned DAVES is an olefin such as ethylene, propylene, isobutylene, α-octene, α-dodecene, vinylene carbonates, acrylic, etc., which can be copolymerized with vinyl acetate or diacetone acrylamide within a range not inhibiting the effects of the present invention. Acids, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid and other unsaturated acids or salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, acrylamide and methacrylamide Amides such as olefins, olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof, alkyl vinyl ethers, vinyl esters such as vinyl formate, vinyl propionate and vinyl butyrate, N-acrylamide methyl Rutrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, polyoxyethylene (meth) allyl ether, polyoxypropylene (meth) allyl ether, etc. Polyoxyalkylene (meth) acrylates such as polyoxyalkylene (meth) allyl ether, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate, polyoxyethylene (meth) acrylamide, polyoxypropylene (meth) acrylamide, etc. Polyoxyalkylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1-dimethylpropyl) ester Polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, isopropenyl acetate, vinylethylene carbonate, 2,2-dialkyl-4-vinyl- It may be copolymerized with at least one selected from 1,3-dioxolane, glycerin monoallyl ether, 3,4-diacetoxy-1-butene, 1,4-diacetoxy-2-butene and the like. In addition, the obtained DAVES may be post-modified by a reaction such as acetalization, urethanization, etherification, grafting, phosphate esterification, acetoacetylation, cationization, etc., as long as the effects of the present invention are not inhibited. good.

  Although content of the diacetone acrylamide unit in said DAVES does not have a restriction | limiting in particular, The range of 0.5-15 mol% is preferable and the range of 1-10 mol% is more preferable. If the diacetone acrylamide unit content is low, water resistance or moisture resistance may be reduced. If there is a large amount of diacetone acrylamide, the solubility in water will be reduced, so an aqueous coating solution cannot be prepared. There is a problem.

  The saponification degree of the DAVES is not particularly limited, but the saponification degree measured by the method of JIS K-6726 (1994) is preferably 80 mol% or more, and more preferably 85 mol% or more.

  The degree of polymerization of the DAVES is not particularly limited, but is preferably 4500 or less from the viewpoint of enhancing industrial productivity. The viscosity of DAVES is the method of JIS K-6726 (1994) (rotary viscometer method). The viscosity of the 4 wt% aqueous solution measured at is preferably 10 to 100 mPa · s, and more preferably 20 to 80 mPa · s.

The cross-linking agent used in the present invention is not particularly limited as long as the effects of the present invention are not hindered, but is a functional group having reactivity with the ketone group of DAVES, represented by the following formula (1)
—NH—NH ₂ (1)
A hydrazino group represented by the following formula (2):
—CO—NH—NH ₂ (2)
And a hydrazide group represented by the following formula (3)
—NH—CO—NH—NH ₂ (3)
Preferable examples include compounds having two or more functional groups of at least one selected from the group consisting of semicarbazide groups.

  Specific examples of the crosslinking agent include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydride hydride , Hexadecanediohydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4'-bisbenzenedihydrazide, 1,4-cyclohexanedihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetic acid dihydrazide, itaconic acid Dihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, citric acid trihydrazide, butanetricarbohydrazide, 1,2,3-benzene Polyfunctional hydrazine and polyfunctional hydrazide compounds such as hydrazide, 1,4,5,8-naphthoic acid tetrahydrazide, nitriloacetic acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, pyromellitic acid tetrahydrazide, N-aminopolyacrylamide, and N , N'-hexamethylenebissemicarbazide, buretritri, and other semicarbazide compounds, and polyfunctional hydrazine derivatives, polyfunctional hydrazide derivatives, and polyfunctional hydrazides obtained by reacting these compounds with low-boiling ketones such as acetone and methyl ethyl ketone. Functional semicarbazide derivatives and the like are also included.

  Although the addition amount of said crosslinking agent is not specifically limited, 1-20 weight part is preferable with respect to 100 weight part of DAVES, 2-15 weight part is more preferable, 3-10 weight part is further more preferable. If the addition amount of the crosslinking agent is small, not only water resistance and moisture resistance are lowered, but also the viscosity when mixing the mixed aqueous solution containing DAVES and the crosslinking agent and the porous inorganic fine particles is low, and the voids of the fine particles cannot be secured. . Moreover, when there is too much addition amount of a crosslinking agent, it will become difficult to maintain a coating liquid at a fixed viscosity, productivity will fall, and since the crosslinking agent which does not contribute to reaction elutes, there exists a possibility that water resistance may fall.

  As a method for adding a crosslinking agent to the DAVES of the present invention, an aqueous solution of a crosslinking agent is usually added to an aqueous solution of DAVES prepared in advance. As a method for preparing a DAVES aqueous solution, a DAVES resin is previously dispersed in room temperature water, heated to 80 ° C. or higher with stirring, completely dissolved, and then cooled by a conventionally known PVA resin dissolution method. Can do. On the other hand, the cross-linking agent may be added to the DAVES aqueous solution as a solid, but in order to react more uniformly, a method of preparing an aqueous solution of the cross-linking agent in advance and adding the aqueous solution to the DAVES aqueous solution is preferable.

  The volatile ketone compound used in the present invention will be described. In the mixed aqueous solution of DAVES and the crosslinking agent, the reaction between DAVES and the crosslinking agent proceeds in the solution, and the viscosity of the solution increases with time. In view of this point, in the present invention, the viscosity increase in the process of mixing the porous inorganic fine particles added after mixing DAVES and the crosslinking agent and the mixed aqueous solution and the process of coating on the substrate, and the coating liquid In order to prevent gelation, a volatile ketone compound is added. The crosslinking agent has reactivity with the ketone group in DAVES and the ketone group in the volatile ketone compound, but it is considered that the reactivity with the volatile ketone compound having little steric hindrance and high mobility is higher. Therefore, when both DAVES and a volatile ketone compound coexist, it preferentially reacts with the volatile ketone compound, and the hydrazino group, hydrazide group or semicarbazide group in the crosslinking agent is blocked, and the crosslinking reaction with DAVES is suppressed. When the volatile ketone compound is present, the viscosity of the ink receiving layer coating solution is considered to be stable. The volatile ketone compound reacted with the cross-linking agent is desorbed and volatilized in the subsequent reaction step, so that DAVES and the cross-linking agent eventually react and do not adversely affect the physical properties and water resistance of the ink jet recording material.

  The volatile ketone compound used in the present invention is a compound having a boiling point of 150 ° C. or lower and having at least one ketone group in the molecule. For example, acetone (2-propanone), methyl ethyl ketone (2-butanone) , Methyl isopropyl ketone (3-methyl-2-butanone), methyl vinyl ketone (3-buten-2-one), diethyl ketone (3-pentanone), methyl-n-propyl ketone (2-pentanone), methyl isobutyl ketone (2-methyl-4-pentanone), methyl-n-butyl ketone (2-hexanone), di-n-propyl ketone, ethyl-n-butyl ketone, methyl-n-amyl ketone, ethyl-2-hydroxypropyl ketone and the like. However, it is not limited to these. Among volatile ketone compounds, acetone, methyl ethyl ketone, and methyl isopropyl ketone are suitable for use in the present invention because of their low boiling point and good miscibility with water. In this invention, a volatile ketone compound can be used 1 type or in combination of 2 or more types.

  The usage-amount of the volatile ketone compound used by this invention is 1-100 weight part with respect to 100 weight part of DAVES, Preferably it is 2-70 weight part, More preferably, it is 3-50 weight part. When the amount of the volatile ketone compound used is less than 1 part by weight relative to 100 parts by weight of DAVES, the crosslinking reaction between DAVES and the crosslinking agent is not sufficiently suppressed, and the ink receiving layer coating liquid is being prepared, stored or applied. There is a risk that it will not thicken. In addition, when the amount exceeds 100 parts by weight with respect to 100 parts by weight of DAVES, since DAVES does not dissolve in the ketone compound, when the volatile ketone compound is added to the mixed aqueous solution containing DAVES and the crosslinking agent, DAVES is precipitated and applied. There is a risk of problems in construction.

  The porous inorganic fine particles used in the present invention are not particularly limited. For example, wet synthetic silica, colloidal silica, gas phase method silica, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate. , Titanium dioxide, zinc oxide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, tin oxide sol, cerium oxide sol, lanthanum oxide sol, titanium oxide sol, neodymium oxide sol, yttrium oxide sol, colloidal alumina, pseudo White inorganic pigments or inorganic sols such as boehmite alumina, vapor phase method alumina, aluminum hydroxide, alumina, lithobon, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, etc. can be used. It can be used in combination of two or more.

  The particle diameter of the porous inorganic fine particles used in the present invention is not particularly limited as long as the effects of the present invention are not hindered, and is selected according to the type of inorganic fine particles used. For example, in the case of wet synthetic silica, those having an average particle diameter of 1 to 12 μm are preferable, in the case of colloidal silica, those having an average particle diameter of 5 to 100 nm are preferable, and in the case of vapor-phase method alumina and pseudoboehmite alumina, the average particles The diameter is preferably 30 nm or less. The average particle diameter is a particle diameter observed with an electron microscope (taken 10,000 to 400,000 magnifications of an electron microscope, for example, measured and averaged the diameter of a 5 cm square particle, “fine particle handbook”, (See Asakura Shoten, p52, 1991).

  The use ratio of the porous inorganic fine particles and DAVES is set according to the type and purpose of the porous inorganic fine particles, but the weight ratio of DAVES / porous inorganic fine particles is preferably 1/100 to 100/100, and 3 / 100-50 / 100 is more preferable.

  In the present invention, when preparing an ink receiving layer coating solution containing DAVES, a crosslinking agent, a volatile ketone compound, porous inorganic fine particles and water, the order and timing of mixing the components are important. The present inventors investigated the time-dependent changes in the viscosity of a mixed aqueous solution of DAVES and a crosslinking agent and when the volatile ketone compound was added at different timings. FIG. 1 shows the results of measuring the viscosity at 20 ° C. over time of a mixture of DAVES 8 wt%, adipic acid dihydrazide (ADH) 0.4 wt%, and acetone 0.8 wt%.

  [1] in FIG. 1 shows the change in viscosity over time when a volatile ketone compound is not added to the mixed aqueous solution of DAVES and ADH, but as can be seen from the figure, the crosslinking reaction immediately after the addition of ADH. Occurs, and the viscosity of the mixed aqueous solution increases rapidly. [2] in FIG. 1 is a change in viscosity with time when ADH is added to a mixed aqueous solution of DAVES and acetone. Acetone temporarily reacts with ADH, so that the crosslinking reaction between DAVES and ADH occurs. It is suppressed and the viscosity of the mixed aqueous solution is stable at a low level. On the other hand, [3] in FIG. 1 is a change with time in viscosity when acetone is added 5 hours after adding ADH to DAVES, but [1] in FIG. 1 is added until acetone is added. ] Shows the same viscosity change, but after adding acetone, it becomes stable at the viscosity at the time of acetone addition.

  As shown in [1] in FIG. 1, when a coating liquid for an inkjet receiving layer is prepared, the viscosity rises in a short time unless a volatile ketone compound is added. It is difficult to mix the aqueous solution, the viscosity changes greatly during mixing or coating of the coating solution, and in the worst case, coating may become impossible during the process. In addition, as shown in [2] in FIG. 1, when a crosslinking agent is added after preparing a mixed aqueous solution of DAVES and a volatile ketone compound, since the viscosity of the aqueous binder solution is low, when mixed with porous inorganic fine particles, Since the binder resin and the cross-linking agent penetrate into the voids of the fine particles, the amount of the binder that settles between the fine particles decreases, and the ink absorbability decreases.

  Therefore, as shown in [3] in FIG. 1, when a crosslinking agent is added to the DAVES aqueous solution and allowed to stand for a certain period of time, and the volatile ketone compound is added when the mixed aqueous solution reaches a desired viscosity, the viscosity increases. Even if mixed with porous inorganic fine particles for a long time, the penetration of fine particles of the binder resin and the crosslinking agent into the voids can be suppressed, and there is no problem in the work of thickening during mixing or coating. This is the gist of the present invention.

  That is, the order of mixing the components used in the ink receiving layer coating liquid of the present invention must be the order of the DAVES aqueous solution, the crosslinking agent, followed by the volatile ketone compound, and finally the porous inorganic fine particles. If the order is damaged, the effect of the present invention is not exhibited.

  Moreover, when preparing the ink receiving layer coating liquid of the present invention, there is no particular limitation on the time from the preparation of the DAVES aqueous solution to the addition of the crosslinking agent, but after the addition of the crosslinking agent, the volatile ketone compound is added. The timing of addition is important. That is, the volatile ketone compound must be added when the viscosity of the mixed aqueous solution of DAVES and the crosslinking agent increases and reaches a desired viscosity. Since the speed of thickening of the mixed aqueous solution of DAVES and cross-linking agent varies depending on the concentration of the aqueous solution, the amount of cross-linking agent, temperature, etc., whether the time to reach the desired viscosity can be calculated from the results of changes in viscosity measured in advance. It is desirable to add the volatile ketone compound when the desired viscosity is obtained from the torque and current value of the stirrer when stirring the mixed aqueous solution of DAVES and the crosslinking agent.

  The time from mixing the DAVES aqueous solution and the crosslinking agent to adding the volatile ketone compound depends on the conditions such as the concentration of the aqueous solution, the amount of the crosslinking agent, and the temperature as described above, but it must be at least 30 minutes or more. is there. If this time is less than 30 minutes, the mixed aqueous solution does not reach the desired viscosity, or if the desired viscosity is reached in less than 30 minutes, the viscosity increase rate is not sufficiently reduced even when a volatile ketone compound is added. However, there is a risk of problems in the subsequent mixing and coating process. On the other hand, as for increasing the time from mixing the DAVES aqueous solution and the crosslinking agent to adding the volatile ketone compound, it is only necessary to take care that the mixed aqueous solution does not exceed the desired viscosity, but it is too long. In this case, since productivity is lowered, it is better to set the conditions such as the aqueous solution concentration, the amount of the crosslinking agent, and the temperature so that it is usually within 48 hours, preferably within 12 hours, more preferably within 6 hours.

  In the method of the present invention, an aqueous solution of DAVES and a crosslinking agent are mixed, and after the mixed aqueous solution is thickened, a volatile ketone compound and porous inorganic fine particles are added and mixed to prepare an ink receiving layer coating solution. However, immediately after adding and mixing the volatile ketone compound to the viscosity (A) of the mixed aqueous solution comprising DAVES and the crosslinking agent immediately after mixing the crosslinking agent (before adding the volatile ketone compound) (adding porous inorganic fine particles) It is preferable that the ratio [(B) / (A)] of the mixed aqueous solution composed of DAVES, the crosslinking agent, and the volatile ketone compound in the previous) is 1.3 to 10.0, and 1.5 More preferably, it is -8.0. When the viscosity ratio [(B) / (A)] is less than 1.3, the ink absorbability of the ink receiving layer is low because the viscosity of the aqueous binder solution when mixing the porous inorganic fine particles is low. It is disadvantageous in terms. When the viscosity ratio [(B) / (A)] exceeds 10.0, the viscosity of the aqueous binder solution becomes too high, and it becomes difficult to mix with the porous inorganic fine particles and apply to the support. It is disadvantageous.

  Between mixing the DAVES aqueous solution and the crosslinking agent and adding the volatile ketone compound, the mixed aqueous solution of DAVES and the crosslinking agent may be left standing or stirred. Moreover, although there is no restriction | limiting in particular also in the temperature at that time, Usually, it is 10 to 80 degreeC, and 15 to 60 degreeC is preferable.

  There is no particular limitation on the time from the addition and mixing of the volatile ketone compound to the mixed aqueous solution of DAVES and the crosslinking agent to the addition of the porous inorganic fine particles. Also, there is no limitation on the mixing method of the mixed aqueous solution containing DAVES, the crosslinking agent and the volatile ketone compound and the porous inorganic fine particles. However, the porous inorganic fine particles are dispersed as uniformly as possible in the mixed aqueous solution. By using a known mixing apparatus and method such as a homogenizer, an ink receiving layer coating solution can be prepared. The optimum pH of the obtained ink-receiving layer coating solution varies depending on the other chemicals added to the ink-receiving layer coating solution and the type of ink used in the ink jet printer, but is generally preferably 5.0 to 9.0. More preferably, it is 5.5 to 8.5.

  In such a coating solution, other water-soluble resins, water-dispersible resins, or inorganic fillers, plasticizers, ink fixing agents, surfactants, etc. are used in combination as long as the effects of the present invention are not impaired. It can also be used. Examples of other water-soluble resins or water-dispersible resins that can be used in combination include cellulose derivatives such as albumin, gelatin, casein, starch, gum arabic, methylcellulose, and hydroxyethylcellulose, polyamide resins, melamine resins, PVA, vinylpyrrolidone-modified PVA, N-substituted or unsubstituted (meth) acrylamide-modified PVA, silanol-modified PVA, sulfonic acid-modified PVA, poly (meth) acrylate sodium, anion-modified PVA, sodium alginate, water-soluble polyester and other anionic water-soluble resins, polyethyleneimine , Polyvinylamine, polyallylamine, polyallylamine sulfone copolymer or ammonium salts thereof, cationized starch, cationized poly (meth) acrylamide, cation-modified PVA, cation Water dispersion of cationic water-soluble resins such as fluorinated polyamide resin, SBR latex, NBR latex, vinyl acetate resin emulsion, ethylene / vinyl acetate copolymer emulsion, (meth) acrylic ester resin emulsion, vinyl chloride resin emulsion Resin.

  In addition, in such a coating solution, when the influence of the water-soluble basic compound on the health of the worker is small, or when the adverse effect on additives other than the binder resin and the crosslinking agent and the color development of the ink during printing is small. Alternatively, a water-soluble basic compound and a volatile ketone compound may be used in combination to stabilize the coating solution. Since the inhibition mechanism of the crosslinking reaction by the water-soluble basic compound and the inhibition mechanism of the crosslinking reaction by the volatile ketone compound are different, the combined effect of the mixed aqueous solution in which DAVES and the crosslinking agent coexist is enhanced by using both. In other words, the amount of water-soluble basic compound added can be reduced by using a volatile ketone compound as a reaction inhibitor.

  Examples of the water-soluble basic compound used in the present invention include water-soluble organic amines, alkali metal hydroxides such as ammonia, sodium hydroxide and potassium hydroxide, and alkaline earth metal such as calcium hydroxide. Examples of water-soluble organic amines include monoethanolamine, aminoethylethanolamine, monoisopropanolamine, N- (2-hydroxypropyl) -ethylenediamine, 2-amino-1-butanol, and 2 -Amino-2-methyl-1-propanol, 3-amino-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, tris (Hydroxyethyl) -primary alkanolamines such as aminomethane; diethanolamine, methyl Secondary alkanolamines such as tanolamine, butylmethanolamine, N-acetylethanolamine, diisopropanolamine; tertiary such as triethanolamine, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, triisopropanolamine Alkanolamines; primary alkylamines such as methylamine, ethylamine, isobutylamine, t-butylamine, cyclohexylamine; secondary alkylamines such as dimethylamine, diethylamine, diisopropylamine; tertiary alkylamines such as trimethylamine Can be mentioned. These may be used alone or in combination of two or more.

  In the method for producing an ink jet recording material of the present invention, an ink receiving layer coating solution comprising DAVES, a crosslinking agent, a volatile ketone compound, porous inorganic fine particles and water obtained by the above method is applied onto a support, An ink receiving layer is formed.

  Such a support is not particularly limited. For example, paper (paperboard such as manila balls, white balls, liners, etc., general high quality paper, medium quality paper, gravure paper and other printing paper, high grade paper / intermediate paper / lower grade paper, Newspaper, release paper, carbon paper, non-carbon paper, glassine paper, etc.), resin-coated paper, synthetic paper, non-woven fabric, cloth, metal foil, polyethylene, polypropylene, PET, polycarbonate, polyvinyl chloride, ethylene-propylene copolymer Films, sheets and molded products made of thermoplastic resins such as these are used.

  Coating methods of the coating liquid for providing the ink receiving layer on the support include air knife coater, curtain coater, slide lip coater, die coater, blade coater, gate roll coater, bar coater, rod coater, bill blade coater A known method using an apparatus such as a short dwell blade coater or a size press is used.

  The solid content in the coating solution is not particularly limited, but is preferably 5 to 60% by weight, more preferably 8 to 50% by weight, and still more preferably 10 to 30% by weight of the entire coating solution. If the amount of solids in the coating solution is small, not only will the drying load increase, but the uniformity of the coating layer thickness may be reduced. Conversely, if the amount of solids is large, the coating solution will have a high viscosity. Therefore, workability may be reduced, such as difficulty in high-speed coating.

  The drying method after coating the coating solution on the support is not particularly limited, but it is preferable from the viewpoint of productivity to use heat drying such as a method of blowing hot air or a method of irradiating infrared rays. The drying conditions in that case are not particularly limited, and may be usually dried at 90 to 120 ° C. for about 1 to 30 minutes.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples at all, and many variations are within the technical idea of the present invention. This is possible by those with ordinary knowledge. In the examples, “%” and “parts” are based on weight unless otherwise specified.

  DAVES was synthesized by the following method. The saponification degree and 4% aqueous solution viscosity were measured according to JIS K-6726 (1994). In addition, the diacetone acrylamide content (denaturation degree) was determined from the results of nitrogen analysis of a sample in which DAVES was sufficiently washed with methanol.

A synthesis example of DAVES is shown below.
[Synthesis Example 1]
A flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser was charged with 680 parts of vinyl acetate, 5 parts of diacetone acrylamide, and 172 parts of methanol, and after substituting nitrogen in the system, the internal temperature was raised. The temperature was raised to 60 ° C. To this system, a solution of 1 part of 2,2-azobisisobutyronitrile dissolved in 50 parts of methanol was added to initiate polymerization. A solution obtained by dissolving 50 parts of diacetone acrylamide in 43 parts of methanol was dropped at a constant rate over 5 hours after the start of polymerization, and 6 hours later, m-dinitrobenzene was added as a polymerization inhibitor to stop the polymerization. The polymerization yield was 78%. The remaining vinyl acetate was distilled while adding methanol vapor to the resulting reaction mixture to obtain a 50% methanol solution of a vinyl acetate polymer containing a diacetone acrylamide copolymer component. To 500 parts by weight of this mixture, 50 parts by weight of methanol and 10 parts by weight of a 4% methanol solution of sodium hydroxide were added and mixed well, and a saponification reaction was carried out at 40 ° C. The obtained gel-like material was pulverized, washed thoroughly with methanol and then dried to obtain a saponified product of vinyl acetate-diacetone acrylamide copolymer. The content rate of the diacetone acrylamide unit in this resin was 5.0 mol%. This resin had a 4% aqueous solution viscosity at 2O 0 C of 26.8 mPa · s and a saponification degree of 98.4 mol%.

[Synthesis Examples 2-3]
DAVES 2 to 3 shown in Table 1 were obtained in the same manner as in Synthesis Example 1 except that the charged composition was changed as shown in Table 1 and the amount of sodium hydroxide in the saponification reaction was changed.

[Example 1]
92 parts of pure water was added to 8 parts of DAVES1 obtained in Synthesis Example 1, and the mixture was heated with stirring, dissolved at 90 ° C. for 2 hours, and then cooled to 20 ° C. to obtain an 8% aqueous solution. To 100 parts of this aqueous solution, 4 parts of a 10% aqueous solution of adipic acid dihydrazide as a cross-linking agent was added, mixed rapidly, and after 4 hours with slow stirring at 20 ° C., 0.8 parts of acetone as a volatile ketone compound. Was added and mixed. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 288 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone after 4 hours was 620 mPa · s. It was. Table 2 shows the conditions for preparing the mixed solution.
To 50 parts of the above mixed aqueous solution, 35 parts of amorphous silica [trade name: Fine Seal X-45, average particle diameter 4.5 μm] manufactured by Tokuyama Co., Ltd. is gradually added while being dispersed. 5 parts of diallyldimethylammonium chloride [manufactured by Nittobo Co., Ltd., trade name: PAS-H-5L, 28% aqueous solution] and 160 parts of pure water were added and stirred at 5000 rpm for 10 minutes using a homogenizer, and the solid content was 15%. An ink receiving layer coating solution was prepared. This coating solution is applied to high-quality paper with a basis weight of 64 g / m ² using an air knife coater so that the solid content is 13 g / m ² and dried at 105 ° C. for 10 minutes to produce an ink jet recording material. did.

[Example 2]
After heating to 50 ° C. to 100 parts of 8% aqueous solution of DAVES1 obtained in Synthesis Example 1, 4 parts of 10% aqueous solution of hexamethylene semicarbazide [Hardener SC manufactured by Asahi Kasei Chemicals Corporation] as a crosslinking agent was added. After quick mixing, after 3 hours with slow stirring at 50 ° C., 1.2 parts of methyl ethyl ketone as a volatile ketone compound was added and mixed. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 212 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone compound after 3 hours was 544 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Example 3]
To 100 parts of the 8% aqueous solution of DAVES2 obtained in Synthesis Example 2, 5 parts of a 10% aqueous solution of N-aminopolyacrylamide [APA-L manufactured by Otsuka Chemical Co., Ltd.] as a cross-linking agent was added and quickly mixed. After 2 hours with slow stirring at 20 ° C., 1.6 parts of methyl isopropyl ketone as a volatile ketone compound was added and mixed. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 92 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone compound after 2 hours was 498 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Example 4]
To 100 parts of the 8% aqueous solution of DAVES3 obtained in Synthesis Example 3, 5 parts of a 10% aqueous solution of carbohydrazide as a cross-linking agent was added, mixed rapidly, and after 1 hour with slow stirring at 20 ° C., volatile As a ketone compound, 2.4 parts of acetone was added and mixed. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 766 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone compound after 1 hour was 1090 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Example 5]
A mixed aqueous solution was prepared in the same manner as in Example 1 except that the time from the addition of the crosslinking agent to the addition of the volatile ketone compound was changed from 4 hours to 6 hours. The viscosity (A) of the aqueous solution immediately after addition and mixing of the crosslinking agent was 284 mPa · s, but the viscosity (B) of the aqueous solution after addition and mixing of the volatile ketone compound after 6 hours was 1660 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Example 6]
A mixed aqueous solution was prepared in the same manner as in Example 2 except that the time from the addition of the crosslinking agent to the addition of the volatile ketone compound was changed from 3 hours to 40 minutes. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 212 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone compound after 40 minutes was 285 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Example 7]
A mixed aqueous solution was prepared in the same manner as in Example 1 except that the addition amount of acetone as a volatile ketone compound was changed from 0.8 part to 0.24 part. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 288 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone after 4 hours was 635 mPa · s. It was. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Comparative Example 1]
A mixed aqueous solution was prepared in the same manner as in Example 1 except that the time from the addition of the crosslinking agent to the addition of the volatile ketone compound was changed from 4 hours to 15 minutes. The viscosity (A) of the aqueous solution immediately after the addition and mixing of the crosslinking agent was 285 mPa · s, but the viscosity (B) of the aqueous solution after addition and mixing of the water-soluble basic compound after 15 minutes was 302 mPa · s. s. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Comparative Example 2]
Except for using unmodified PVA [JP-18 manufactured by Nippon Vinegar Poval Co., saponification degree 88.0 mol%, 4% aqueous solution viscosity 24.1 mPa · s] replaced with DAVES obtained in Synthesis Example 1. Prepared a mixed aqueous solution in the same manner as in Example 1. The viscosity (A) of the aqueous solution immediately after adding and mixing the cross-linking agent was 272 mPa · s, but the viscosity (B) of the aqueous solution after adding and mixing the volatile ketone compound after 4 hours was 270 mPa · s. there were. Table 2 shows the conditions for preparing the mixed solution. An ink jet recording material was prepared in the same manner as in Example 1 using the above mixed aqueous solution.

[Comparative Example 3]
A mixed aqueous solution was prepared in the same manner as in Example 1 except that no crosslinking agent was added, and an inkjet recording material was prepared in the same manner as in Example 1. Table 2 shows the conditions for preparing the mixed solution.

[Comparative Example 4]
After adding 4 parts of 10% aqueous solution of adipic acid dihydrazide as a crosslinking agent to 100 parts of 8% aqueous solution of DAVES obtained in Synthesis Example 1, after 4 hours with slow stirring at 20 ° C., For the mixed aqueous solution to which no volatile ketone compound was added, an ink-receiving layer coating solution was prepared in the same manner as in Example 1, and an attempt was made to apply it to fine paper. Coating could not be continued and an ink jet recording material could not be obtained. Table 2 shows the conditions for preparing the mixed solution.

(In the table, each abbreviation has the following meaning.
ADH: adipic acid dihydrazide, SC: hexamethylene semicarbazide (Hardener SC), APA: N-aminopolyacrylamide (APA-L), CDH: carbohydrazide, ATN: acetone, MEK: methyl ethyl ketone, MIPK: methyl isopropyl ketone The pH of each of the ink receiving layer coating liquids of Examples 1 to 7 and Comparative Examples 1 to 4 was 6.0 to 6.5. )

  The following tests were conducted on the ink jet recording materials of Examples and Comparative Examples produced as described above. The results are shown in Table 3.

<Observation of crack>
The surface of the ink receiving layer of the produced ink jet recording material was observed with a microscope having a magnification of 100 times, and the degree of cracking on the surface of the ink receiving layer was evaluated according to the following criteria.
○: No surface cracks observed and no problem △: Multiple surface cracks observed and difficult to use ×: Very many cracks observed and impractical

<Surface strength>
A mending tape (width 18 mm) manufactured by Sumitomo 3M Co., Ltd. was applied to the surface of the ink-receiving layer of the ink-jet recording material produced, and the state of the coating layer transferred to the mending tape when peeled was visually observed. The surface strength was evaluated according to the following criteria.
○: Almost no coating layer is transferred, and there is no problem in practical use. △: A part of the coating layer is transferred, and there is a slightly problematic level. X: A considerable part of the coating layer is transferred, practically Problem level

<Ink absorbability>
Set the prepared inkjet recording material on the printer “PX-V630” manufactured by Seiko Epson Corporation, perform solid printing with black ink, and rub the printed part on the recording sheet with your finger at regular intervals after printing. The time until ceased to change was measured. The shorter the time, the greater the ink absorption rate.

<Water resistance>
Whether water was applied to the printed portion of the ink jet recording material and it was rubbed with a finger was used to determine whether the printed portion was dissolved or smudged according to the following criteria.
○: There is no blur and the original shape remains.
×: Smear is large and the original shape is not retained.

  As is apparent from Table 3, it was confirmed that the ink jet recording materials of Examples 1 to 7 produced by the production method of the present invention showed high surface strength without cracks on the surface of the ink receiving layer. Further, since the ink jet recording material of the present invention has high ink absorbability and high water resistance, it is possible to display a fine image even when printing at high speed. As described above, the ink jet recording material produced by the production method of the present invention has a high binder strength even when the ink receiving layer has a high porosity and a small amount of the binder resin in order to improve the ink absorbability. The ink receiving layer has an excellent effect that no cracks occur on the surface.

  Comparative Example 1 is a binder resin because in the production method of the present invention, the time from the addition of the crosslinking agent to the addition of the volatile ketone compound is short and the crosslinking reaction is not sufficiently advanced. Since the amount of the binder is reduced by penetrating into the voids of the porous inorganic fine particles, it is considered that the strength is lowered and the ink absorbency is also lowered.

  Comparative Examples 2 and 3 do not use a saponified product of vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent, respectively, and therefore all evaluation items of surface strength, ink absorbency and water resistance without causing a crosslinking reaction. It seems that there was a problem.

  Since Comparative Example 4 does not use the volatile ketone compound in the constituent elements of the present invention, the cross-linking reaction proceeds too much in the process of preparing the ink-receiving layer coating solution and the process of coating the ink-receiving layer. It is thought that the material could not be manufactured.

  According to the method for producing an ink jet recording material of the present invention, a coating solution for producing an ink receiving layer without using a water-soluble basic compound that is harmful and may adversely affect other additive agents. Is excellent in viscosity stability, and the ink receiving layer surface is not cracked in the drying process, so that the productivity is high. Further, since the ink jet recording material produced by the production method of the present invention is excellent in ink absorbability, strength and water resistance, it is possible to display a fine image even when printing at high speed.

Claims (6)

  A step of mixing an aqueous solution of a saponified product of vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent, a step of obtaining a mixed solution by adding a volatile ketone compound after at least 30 minutes have elapsed after the mixing, and An ink receiving layer coating liquid in which porous inorganic fine particles are mixed with the mixed liquid obtained, and a step of applying the ink receiving layer coating liquid on the support. A method for producing an ink jet recording material, comprising a saponified product of an acetone acrylamide copolymer and a crosslinking agent.   In a method for producing an ink-jet recording material having a porous inorganic fine particle, a saponified vinyl acetate-diacetone acrylamide copolymer and a crosslinking agent on a support, a vinyl acetate-diacetone acrylamide copolymer A step of mixing an aqueous solution of a saponified product and a cross-linking agent, and after the resulting mixed solution has thickened, a volatile ketone compound is added to and mixed with the mixed solution, and then porous inorganic fine particles are added and mixed. A step of preparing an ink-receiving layer coating solution, and a volatile ketone for the viscosity (A) of the mixture solution of the saponified vinyl acetate-diacetone acrylamide copolymer and the crosslinking agent immediately after mixing the crosslinking agent. Viscosity (B) ratio of the mixture of saponified vinyl acetate-diacetone acrylamide copolymer immediately after mixing, crosslinker and volatile ketone compound [( ) / (A)] The production method of the ink jet recording material, which is a 1.3 to 10.0.   3. The method for producing an ink jet recording material according to claim 1, wherein the crosslinking agent is a compound having two or more functional groups selected from the group consisting of a hydrazino group, a hydrazide group and a semicarbazide group.   The method for producing an ink jet recording material according to claim 1, wherein the volatile ketone compound is at least one selected from the group consisting of acetone, methyl ethyl ketone, and methyl isopropyl ketone.   The addition amount of a volatile ketone compound is 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of a saponified product of vinyl acetate-diacetone acrylamide copolymer. A method for producing an ink jet recording material according to claim 1.   The viscosity of a 4 wt% aqueous solution measured by the method of JIS K-6726 (1994) of a saponified product of vinyl acetate-diacetone acrylamide copolymer is 10 to 100 mPa · s. A method for producing an inkjet recording material according to any one of the above.