JP2007119953A - Substrate for recording material and ink-jet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily obtain a substrate for recording material, good in gloss feeling and markedly reduced in developing wrinkles and/or curls even if coated with an aqueous image recording layer-forming coating liquid; and to provide an ink-jet recording medium having high gloss feeling and high color developability. <P>SOLUTION: The substrate for recording material is obtained by the following procedure: at least one side of a water-absorbing substrate is coated with a coating layer-forming coating liquid containing a resin dispersion to form coating layer followed by pressurizing the coating layer under such conditions that substantially no voids remain in the coating layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a novel support for recording material and an ink jet recording medium.

In order to produce a photographic quality print by the ink jet recording method, a dedicated ink jet recording medium is required. In particular, an ink jet recording medium in which an ink-absorbing layer is formed on a non-water-absorbing resin-coated paper, which is called resin-coated paper, has an ink-absorbing layer on a water-absorbing support such as a paper support. High gloss feeling is obtained compared to the formed one, which is preferable. However, since resin-coated paper is produced with many man-hours, such as coating a polyethylene resin on both sides of a water-absorbent support and forming an undercoat layer for applying an ink-absorbing layer, production efficiency is poor, and production There is a problem of high cost. Further, conventional resin-coated paper is mainly produced for silver salt photographic light-sensitive materials, and is generally used for an ink jet recording medium provided with an ink absorbing layer having a void structure having excellent ink absorbing characteristics. In this case, the glossiness is still low.

On the other hand, a coating liquid containing a water-dispersible latex is applied to the surface of the base paper on which at least the image forming layer is provided, and then dried, and then the surface of the water-dispersible latex-containing coating layer is smoothed. A recording material support characterized by being obtained by processing is disclosed (see Patent Document 1). In this method, it is possible to easily produce a support as compared with the above resin-coated paper, but the support produced by the method disclosed here is certainly improved in smoothness, When an aqueous image recording coating solution was applied thereon, cockling and curling occurred, and as a result, it was found that an ink jet recording medium having sufficient glossiness could not be produced. Further, it has been found that when the support is bent, a defect such as a crack is generated, and an image defect such as a decrease in print density at the location is generated, and improvement is urgently required.
JP 2004-347722 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its purpose is to produce a cockling that can be manufactured by a simple manufacturing method, is excellent in glossiness, and is coated with an aqueous image recording layer forming coating solution. An object of the present invention is to provide a support for recording material in which the occurrence of curling and curling is greatly improved, and an ink jet recording medium having high gloss and high color development.

  The above object of the present invention is achieved by the following configurations.

  1. After forming a coating layer by applying a coating layer forming coating solution containing a resin dispersion on at least one surface side of the water-absorbent support, pressure treatment is performed under the condition that substantially no voids remain in the coating layer. A support for recording material, which is obtained by applying.

  2. 2. The support for recording material as described in 1 above, wherein the pressure in the pressure treatment is 5 MPa or more and 50 MPa or less.

  3. 3. The recording material support according to 1 or 2, wherein the pressure treatment is performed by a calendar machine in a range of a linear pressure of 0.3 kN / cm to 2.0 kN / cm.

  4). Any of the above 1 to 3, wherein the temperature at the time of pressurization in the pressure treatment is Tp, and the glass transition temperature of the resin dispersion is Tg, which satisfies the condition defined by the following formula (1): The support for recording materials according to claim 1.

Formula (1)
Tg <Tp <Tg × 2
5. 5. The recording material support according to any one of 1 to 4, wherein the pressure treatment is performed a plurality of times.

  6). 6. The recording material support according to any one of 1 to 5, wherein a coating liquid for forming a coating layer containing the resin dispersion is applied and then dried at a temperature equal to or higher than Tg of the resin dispersion. body.

  7). 7. The recording material support according to any one of 1 to 6, wherein the coating layer containing the resin dispersion contains a pigment.

  8). 8. The recording material support according to 7, wherein the pigment is at least one selected from kaolin, calcium carbonate, talc, silica, and alumina.

  9. 9. The recording material as described in 7 or 8 above, wherein when the pigment solid content in the coating layer containing the resin dispersion is P and the resin solid content is B, the condition defined by the following formula (2) is satisfied. Support.

Formula (2)
0.13 <P / (P + B) <0.5
10. 10. The recording material support according to any one of 1 to 9, wherein the resin dispersion is polymerized using a water-soluble polymer as a protective colloid.

  11. 11. The recording material support according to any one of 1 to 10, wherein the coating layer forming coating solution containing the resin dispersion has a viscosity of 100 mPa · s or more and 1000 mPa · s or less.

12 12. The recording material support according to any one of 1 to 11, wherein L ^* a ^* b ^{* on the} surface of the coating layer containing the resin dispersion is in the range specified below.

Lightness index L ^* > 90 in CIE color space
Perceived chromaticity index is −7 <a ^* <+ 7, −7 <b ^* <− 7
13. An ink jet recording medium comprising an ink absorbing layer and the recording material support described in any one of 1 to 12 above.

14 The ink absorbing layer containing a polyvalent metal salt compound in an amount of 0.3 g / m ² or more and 2 g / m ² or less in terms of polyvalent metal oxide, and the recording material support according to any one of 1 to 12 above. An ink jet recording medium comprising: a body.

  According to the present invention, a recording material support that can be produced by a simple production method, has excellent gloss, and has greatly improved cockling and curling even when an aqueous image recording layer forming coating solution is applied. And an inkjet recording medium having high gloss and high colorability.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  In the present invention, after forming a coating layer by applying a coating layer-forming coating solution containing a resin dispersion on at least one surface side of the water-absorbent support, a condition that substantially no voids remain in the coating layer It is related with the support for recording materials characterized by being obtained by performing a pressure process.

  The void referred to in the present invention is a space in which a liquid formed between the surface of the recording material support and the water-absorbing support can permeate, and the liquid adheres to the surface of the recording material support. In this case, the liquid reaches the water-absorbing support through the gap, and as a result, the liquid reaching the water-absorbing support causes problems such as swelling and deformation of the water-absorbing support.

  Such voids in the coating layer are formed in the process of filling the resin particles in the resin dispersion and the solvent in the resin dispersion volatilizing in the drying process. In the present invention, this coating layer is sufficiently processed by applying pressure after formation to a level at which voids do not substantially remain, thereby suppressing problems such as swelling and deformation of the water-absorbent support. It has been found that a recording material support can be provided that has a high glossiness and can maintain the high glossiness even when a recording layer forming coating solution is applied onto the recording material support.

The confirmation of the presence or absence of voids in the present invention can be confirmed by, for example, directly observing with an electron microscope and confirming the presence thereof, and also by a test method according to the water absorption test method (Cobb) method defined in JIS P 8140. it can. In the measurement method according to the water absorption test method (Cobb) method, if the water absorption is less than 5 g / m ² , it is determined that there is no void, and preferably less than 2 g / m ² .

  In the present invention, it was found that there is a preferable pressure condition for performing the pressure treatment without substantially leaving any voids in the coating layer containing the resin dispersion and for further exerting the object effect of the present invention. . That is, when an aqueous coating solution such as an ink absorbing layer is applied on the absorbent support, the occurrence of cockling and curling is further suppressed, and a higher gloss feeling can be obtained.

  In the study that led to the present invention, pressures suitable for two methods of pressurizing in a sheet form and so-called calendering, in which pressurization was performed in a linear or very narrow nip formation were examined.

  First, in the case of planar pressing, it was found that the pressure is preferably in the range of 5 MPa or more and 50 MPa or less. Even if the pressure is less than 5 MPa, the effect of the present invention can be obtained if no voids remain in the coating layer, but it is preferably 5 MPa or more in view of the effect. On the other hand, when a high pressure exceeding 50 MPa is applied, the improvement in glossiness becomes small. Although these reasons are not clear, a certain amount of pressure is required to fill the voids between the resin particles by deforming the resin, but if the pressure is higher than necessary, the water absorbing property present in the water absorbing support is present. It is presumed that resin or the like is embedded in the voids of the support and the amount of resin in the coating layer itself is substantially reduced.

  Next, in the case of calendar treatment, the linear pressure is preferably in the range of 0.3 kN / cm to 2.0 kN / cm. In this case, as in the case of the surface heating, it has been found that there are problems such as occurrence of cockling and curling, and the effect of improving the glossiness is reduced outside the optimum range.

  Moreover, it is preferable to heat as the temperature at the time of pressurization, and the effect of the present invention is achieved by setting the temperature Tp at the time of pressurization to a range of Tg <Tp <Tg × 2 with respect to Tg of the resin dispersion. Was found to be more expressed.

  Therefore, pressurization within the above-mentioned preferable pressure range and a preferable heating temperature range is a more preferable method from the viewpoint of the effect of the present invention.

  In addition, it has been found that it is more effective to continuously perform a plurality of pressurization processes as the pressurization condition from the viewpoint of obtaining the object effect of the present invention. Specifically, the effect of the present invention is more exhibited when performed in the range of 2 to 10 times. In this case, the processing conditions for a plurality of times may be the same or different. In the case of calendar processing, it is particularly preferable to set the number of nips to a plurality.

  Moreover, it is also preferable to provide a drying step after forming the coating layer containing the resin dispersion on at least one surface side of the water-absorbent support and before performing the pressure treatment. The drying process is important in order not to cause defects such as swelling due to moisture remaining during pressurization. It is particularly preferable that the drying temperature is equal to or higher than the Tg of the resin of the resin dispersion used. It is thought that the film formation of the resin proceeds by drying at a temperature equal to or higher than Tg, and therefore, the process of filling the voids in the pressurizing process is easy and the completeness is increased.

  Next, the water absorbing support used in the present invention will be described.

  As the water-absorbing support applicable to the recording material support of the present invention, those composed of natural and synthetic materials can be used, but preferably a paper base material mainly composed of cellulose pulp is used.

  Examples of the raw material for the paper base material mainly composed of cellulose pulp that can be used in the present invention include chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, CGP, RMP, TMP, CTMP, CMP, and PGW, and DIP. It is possible to use wood pulp such as used paper pulp as the main raw material. In addition, various fibrous materials such as synthetic pulp, synthetic fiber, and inorganic fiber can be appropriately used as raw materials as necessary.

  Various conventionally known additives such as a sizing agent, pigment, paper strength enhancer, fixing agent, fluorescent whitening agent, wet paper strength agent, and cationizing agent may be added to the paper base as necessary. it can. Higher fatty acids, alkyl ketene dimers, etc. as sizing agents, calcium carbonate, talc, titanium oxide, etc. as pigments, starch, polyacrylamide, polyvinyl alcohol, etc. as paper strength enhancing agents, sulfate bands, cationics as fixing agents However, the present invention is not limited to this.

  The paper base material can be manufactured by mixing various fibrous materials such as wood pulp and various additives and using various paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine. Further, if necessary, a size press treatment with starch, polyvinyl alcohol, or the like, a various coating treatment, or a calendar treatment can be performed at the paper making stage or after paper making.

The water-absorbing support that can be preferably used in the present invention is preferably a base paper material mainly composed of cellulose pulp and having a so-called basis weight of 50 g / m ² or more and 250 g / m ² or less. If it is less than 50 g / m ² , the waist is weak and the texture of the paper is not preferred. On the other hand, if it exceeds 250 g / m ^2, an effect such as improvement in glossiness by pressurizing treatment is difficult to be obtained, and when an ink jet recording medium is used, failure is likely to occur due to ink jet printer transportability and the like.

  Next, the resin dispersion according to the present invention will be described.

  As the resin dispersion according to the present invention, a water-dispersible latex that can be used as a latex binder for coated paper can be widely used.

  For example, from SB (styrene butadiene), acrylic, styrene, styrene-acrylic, acrylonitrile-butadiene, vinyl acetate, vinyl acetate-ethylene, vinyl acetate-ethylene-vinyl chloride olefin, urethane, etc. You can choose.

  When the average particle diameter is 0.05 μm or more, the resin particles are suppressed from being buried in the voids of the water-absorbent support during coating, and are likely to contribute to the effect. Moreover, if it is 10 micrometers or less, it is preferable at the point which can suppress that the defect which has a space | gap locally arises, or can eliminate a space | gap by a short time pressure treatment.

  There are no particular restrictions on the ionicity of the resin dispersion. In the case of using an additive such as a pigment in the coating liquid or adding an activator, the liquid can be selected in consideration of the stability of the liquid. Moreover, it can select in consideration of not reducing the stability of the coating liquid apply | coated on the produced water absorbing support body. In these cases, nonionic ones are good and particularly preferred.

  Among nonionic ones, a vinyl acetate latex or an acrylic latex obtained by polymerizing a water-soluble polymer compound as a protective colloid can be particularly preferably used.

As a specific product that can be used as a resin dispersion,
Self-crosslinking molds such as Nipol LX407 series various latexes for styrene butadiene based coated paper manufactured by Nippon Zeon, Nipol V1004, Nipol MH5055, Nipol LX438C, acrylonitrile-butadiene latex (NBR LATEX) Nipol LX874, etc.
Latex for fiber paper processing manufactured by Sumitomo Chemical, vinyl acetate-ethylene, Sumikaflex S-500, 706, 753, etc., vinyl acetate-ethylene-vinyl chloride, S-880, etc.
Asahi Kasei Styrene Butadiene SBR L series (L-1970 etc.),
Polysol EVA series (AD-6 etc.) made by Showa Polymer,
Can be mentioned.

  In addition to the coating layer containing the resin dispersion according to the present invention, pigments, water-soluble binders (eg, starch, casein, soy protein, CMC, PVA, alkali-soluble latex, etc.), dispersants, lubricants, antifoaming Agent, water-proofing agent (wax, insoluble fatty acid, soap, urea, melamine / formalin resin, glyoxal, heavy metal salt, etc.), activator, pH adjuster, fungicide, dye and the like.

  When a pigment is used, it is preferably used in an appropriate amount for adjusting glossiness, white background adjustment and opacity as a support. In particular, a white pigment can be preferably used. Examples of the white pigment include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, and carbonate. Zinc, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, hydrous halloysite, magnesium hydroxide, etc. Organic pigments such as inorganic pigments, styrene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins can be used.

  In particular, it is preferable to use a white pigment selected from light calcium carbonate, heavy calcium carbonate, kaolin, talc, silica, and alumina, and it is also preferable to use titanium oxide together if necessary.

As kaolin, baked kaolin, engineered kaolin, high white kaolin, standard white kaolin, etc. manufactured by Imeris can be used. As calcium carbonate, various synthetic calcium carbonates (Brillant-15, etc.) manufactured by Shiraishi Kogyo Co., Ltd. should be used. When a pigment is added, the effect of the present invention can be further improved by the amount of the pigment added. In this invention, when the pigment solid content in the coating layer containing a resin dispersion is set to P and the resin solid content is set to B, it is preferable to satisfy | fill the conditions prescribed | regulated by the following Formula (2).

Formula (2)
0.13 <P / (P + B) <0.5
If P / (P + B) in the formula (2) is larger than 0.13, the cockling and curl suppressing effects, which are the problems of the present invention, are remarkable, and white background adjustment and opacity improvement are sufficient, which is preferable. Moreover, if P / (P + B) is smaller than 0.5, it is possible to suppress the occurrence of defects in which voids are not completely filled, and the glossiness improving effect is remarkable. In addition, when the recording medium having the ink absorbing layer applied on the support according to the present invention is bent, it is possible to suppress the occurrence of defects such as cracks in the support, and the print density at that location is reduced. This is preferable because there is no risk of causing image defects.

  P / (P + B) defined by Equation (2) is obtained from the total resin amount and the total pigment amount obtained when a plurality of types of resins and pigments are used.

  The viscosity of the coating solution for the coating layer containing the resin dispersion according to the present invention is preferably adjusted to 100 mPa · s or more and 1000 mPa · s or less. This is because it is important to maintain the viscosity required for the coating layer coating liquid so that the coating liquid component does not settle in the voids in the water-absorbent support immediately after coating and in the drying step.

  If the viscosity of the coating layer coating solution is 1000 mPa · s or less, there is no restriction even when the coating film is applied thinly, which is preferable.

In the recording material support of the present invention, the surface of the L ^* a ^* b ^*, so that the conditional range defined below, it is preferable to adjust the white background characteristics.

That is, it is preferable that L ^* > 90 as the lightness index L ^* in the CIE color space, and −7 <a ^* <+ 7, −7 <b ^* <− 7 as the perceptual chromaticity index a ^* and b ^*. .

L ^* , a ^* , b ^* values defined in the present invention are measured according to JIS-Z-8722, 8717, and are displayed according to the color display method defined in JIS-Z-8730. For example, X-rite densitometer (X-Rite 938), Gretag SPM-100 and standard black backing for color measurement, color difference meter (Minolta: CR-100), color analyzer (Murakami Color Co., Ltd. CMS-1200) Etc. can be measured.

By adjusting L ^* , a ^* , and b ^* within the range specified in the present invention, it is preferable that an ink jet recording medium is produced, since the image contrast is increased and a clear and vivid image of pure color is obtained.

  As a method for adjusting the white background as an ink jet recording medium, there is a method of adding a white pigment such as a fluorescent brightening agent or titanium oxide to the ink absorption layer, but it affects the coating solution stability and coating film performance of the ink absorption layer. In many cases, it is preferable to adjust with a support.

When adjusting with a support, when selecting a water-absorbing support, it may be selected in consideration of a white background, or a fluorescent whitening agent or a white pigment may be added to the coating layer containing the resin dispersion. You may adjust it. In particular, when a white pigment is contained in the coating layer containing the resin dispersion according to the present invention, the selection and addition amount of the white pigment to be used are adjusted, and L ^* , a ^{* on the} surface of the support according to the present invention are adjusted ^. , B ^* are particularly preferred.

  In the production process of the recording material support of the present invention, the raw material prepared by adding pulp, band, white pigment, water-soluble polymer, sizing agent, etc. is made with a long net paper machine, and if necessary, size press treatment It is preferable to apply the coating liquid containing the resin dispersion according to the present invention to the base paper, using a roll coater, an air knife coater, a blade coater, and the like, and then perform a calendar process.

  The support for recording material of the present invention can be used as a support for various image recording materials. Examples thereof include an ink jet recording medium, an electrophotographic image receiving material, a sublimation transfer image receiving material, a heat-sensitive color recording material, a thermal transfer image receiving material, and a silver salt photographic light-sensitive material.

  The support for recording materials of the present invention is suitable for applying an aqueous coating solution, and is particularly suitable as a support for inkjet recording media.

  Hereinafter, an ink jet recording medium using the recording material support of the present invention will be described.

  The support for recording material of the present invention is obtained by applying a coating solution containing a water-based resin dispersion as a main component and then applying a pressure treatment. It has affinity and wettability, and the ink absorbing layer can be applied without any pretreatment such as an undercoat layer. If necessary, it is preferable to perform a corona discharge treatment before coating.

  As the ink absorbing layer, either a void type mainly composed of a filler and a binder or a swellable type mainly composed of a water-soluble binder can be used, and a hybrid structure in which both are combined may be used. In the present invention, it is preferable to use a void type excellent in ink absorbability, bleed resistance, drying property and the like.

  Hereinafter, a void-type inkjet recording medium (hereinafter also simply referred to as a recording medium) will be described.

  The void-type ink absorbing layer is mainly formed from a small amount of a binder and fine particles, but the fine particles used in the present invention are inorganic because they give a higher color density and easily obtain fine particles having a smaller particle size. Fine particles are preferred.

  As the inorganic fine particles, various solid fine particles known in conventional ink jet recording media can be used. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide. , Zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide And white inorganic pigments such as lithopone, zeolite and magnesium hydroxide.

  The fine particles may be used in a state of being uniformly dispersed in the binder as primary particles, or may be added in a state of being dispersed in the binder by forming secondary agglomerated particles. Is more preferable.

  The shape of the inorganic fine particles is not particularly limited in the present invention, and may be spherical, rod-like, needle-like, flat-plate-like, or bead-like. The inorganic fine particles preferably have an average particle size of 3 to 200 nm. When fine particles having an average particle diameter exceeding 200 nm are used, the gloss of the recording medium is lowered, or the maximum density is lowered due to light scattering on the surface, so that it is difficult to obtain a clear image. The lower limit of the average particle diameter is not particularly limited, but is preferably about 3 nm or more and 6 nm or more from the viewpoint of particle production. Particularly preferred inorganic fine particles have an average particle diameter of 10 to 100 nm.

  The average particle size of the inorganic fine particles can be obtained as a simple average value (number average) by observing the particle itself or the cross section or surface of the void layer with an electron microscope and determining the particle size of a large number of arbitrary particles. Here, each particle size is represented by a diameter assuming a circle equal to the projected area.

  As the inorganic fine particles according to the present invention, composite particles composed of inorganic fine particles and a small amount of an organic substance (which may be a low molecular compound or a high molecular compound) are substantially regarded as inorganic fine particles. In this case, the particle diameter of the highest order particle observed in the dry film is defined as the particle diameter of the inorganic fine particle.

  The mass ratio of the organic matter / inorganic fine particle in the composite particle of the inorganic fine particle and a small amount of organic substance is approximately 1/100 to 1/4.

  The inorganic fine particles according to the present invention are preferably fine particles having a low refractive index from the viewpoint of low cost and high reflection density, and silica, particularly silica synthesized by a gas phase method or colloidal silica is more preferable. preferable. Further, cation surface-treated gas phase method silica, cation surface-treated colloidal silica and alumina, colloidal alumina, pseudoboehmite and the like can also be used.

  As the hydrophilic binder, various conventionally known hydrophilic binders can be used. For example, gelatin (preferably acid-treated gelatin), polyvinyl pyrrolidone (average molecular weight is preferably about 200,000 or more), pullulan, polyvinyl alcohol and derivatives thereof. , Polyethylene glycol (average molecular weight is preferably 100,000 or more), hydroxyethyl cellulose, dextran, dextrin, and water-soluble polyvinyl butyral. These hydrophilic binders may be used alone or in combination of two or more. You may do it. A particularly preferred hydrophilic binder is polyvinyl alcohol or a derivative thereof.

  Polyvinyl alcohol or a derivative thereof preferably used is preferable because the average degree of polymerization is in the range of 300 to 5,000, and the fragility of the film from which the average molecular weight is 2000 to 5,000 is particularly good. The saponification degree of polyvinyl alcohol or its derivative is preferably 70 to 100%, particularly preferably 80 to 100%.

  The amount of the hydrophilic binder used is as small as possible so that the ink absorbing layer becomes a void layer and is used in a relatively small amount with respect to the inorganic fine particles, and the film can be stably formed and the adhesion to the support can be sufficiently maintained. It is preferable to use less.

The amount of inorganic fine particles used in the void-type ink absorbing layer depends largely on the required ink absorption capacity, the void ratio of the void layer, the type of inorganic fine particles, and the type of hydrophilic binder. ^{The amount} per ² is usually 3 to 30 g, preferably 5 to 25 g. The ratio of inorganic fine particles and polyvinyl alcohol used in the void-type ink absorbing layer is usually 2: 1 to 20: 1 by mass ratio, and preferably 3: 1 to 10: 1.

  In the recording medium, a cationic polymer or a polyvalent metal salt can be used as a colorant fixing agent. At this time, if the addition amount of the cationic polymer is large, the ink absorption rate is lowered, which is not preferable.

In the present invention, the addition amount of the polyvalent metal salt compound to the ink absorbing layer is preferably 0.3 g / m ² or more and 2 g / m ² or less in terms of polyvalent metal oxide. When an image printed using a dye ink on an ink jet recording medium produced using the recording material support of the present invention was examined in detail, the polyvalent metal salt compound was converted to 0.3 g in terms of polyvalent metal oxide. / M ² or more and 2 g / m ² or less is particularly preferable because a high black maximum density can be obtained. Furthermore, the inclusion of 0.6 g / m ² or more and 1.5 g / m ² or less is more preferable in that an image having a high maximum density of all colors and a high saturation can be obtained. Although the cause of this is not clear, the recording material support of the present invention has no voids on its surface, but compared to a resin-coated paper prepared by extruding and coating a conventional polyethylene, its gas permeability and support It is speculated that the flatness and optical characteristics of these materials are slightly different, and it is considered that these influences affect the characteristics of inkjet recording media. It is thought that this may have a subtle effect on the void formation process of the ink absorbing layer during the drying process.

  In addition, in order to apply a polyvalent metal or a cation fixing agent to an ink jet recording medium, it is an effective means to apply a polyvalent metal or a cation fixing agent by means of an overcoat or the like after applying an ink absorbing layer. is there. In particular, when recording with a dye ink, if a fixing agent is applied by an overcoat means, the fixing agent is more present in the upper layer portion, so that the dye can be fixed in the upper layer region, and color development is improved. .

The void layer preferably has a capacity of 15 to 50 ml / m ² per unit area of the coating film. The term “capacity” as used herein refers to the volume of bubbles generated when a unit volume of the coating film is put on water, the volume of water that can be absorbed by the coating film, or the recording paper finally obtained. It is defined as the amount of liquid transfer when the contact time is 2 seconds as measured by the liquid absorbency test method (Bristow method) for paper and paperboard specified in TAPPI 51.

  In order to maintain high gloss without deteriorating the brittleness of the film with a high porosity, it is preferable that the binder is hardened with a hardener.

  The hardener is generally a compound having a group capable of reacting with a binder or a compound that promotes the reaction between different groups of the binder, and is appropriately selected depending on the type of the binder.

  Specific examples of the hardener include epoxy hardeners (for example, diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde hardeners (eg formaldehyde, glioxal etc.), active halogen hardeners (eg 2,4-dichloro) -4-hydroxy-1,3,5-s-triazine, etc.), active vinyl compounds (for example, 1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), boric acid and its Salt, aluminum alum etc. That.

  When polyvinyl alcohol and its derivatives are used as a particularly preferred binder, it is preferable to use a hardener selected from boric acid and its salts and an epoxy hardener.

  When using the above hardener, the preferred amount varies depending on the type of binder, the type of hardener, the type of inorganic fine particles, the ratio to the hydrophilic binder, etc., but is generally 5 to 500 mg per 1 g of binder, more preferably 10-400 mg.

  The above hardener may be added in the coating liquid for forming the void layer and / or in the coating liquid for forming another layer adjacent to the void layer when the coating liquid constituting the void layer is applied, or in advance. Apply a coating solution for forming the void layer on a support on which a coating solution containing a hardener is applied, or apply a non-hardening agent-containing coating solution for forming a void layer, and then dry. The hardening agent can be supplied to the void layer by overcoating the hardening agent solution during or after drying.

  Various additives can be added to the water-soluble coating liquid forming the ink absorbing layer. Examples of such additives include surfactants, white background tone modifiers, fluorescent whitening agents, antifungal agents, viscosity modifiers, low boiling point organic solvents, high boiling point organic solvents, latex emulsions, antifading agents, and ultraviolet rays. Examples include absorbents, matting agents, and silicone oil.

  The coating liquid physical properties of the ink absorbing layer can be determined from the thickness of the coating film, the coating method, and the coating speed in the range of a viscosity of 5 mPa · s or more and less than 10,000 mPa · s. In addition, in the case of multilayer coating, in the curtain coating method, the coating property is better when the upper layer is made more viscous, and in the case of multilayer simultaneous coating of a relatively high viscosity coating solution such as extrusion coater coating, the upper layer is A low viscosity is preferable because of good coating properties.

  The surface tension can be determined from a range of 25 mN / m or more and less than 65 mN / m in consideration of wettability and repellency to the support.

  The solid content concentration in the coating solution can be adjusted by diluting or concentrating in the range of 10% or more and less than 50% according to the coating method.

  The coating method used when coating the ink absorbing layer coating liquid on the support can be appropriately selected from known methods. For example, gravure coating method, roll coating method, rod bar coating method, air knife A coating method, a spray coating method, an extrusion coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

  The film thickness when the ink absorbing layer is wet is preferably set to 50 μm or more and less than 250 μm from the solid content of the coating liquid and the solid content of the ink absorbing layer to be formed.

  In addition, after applying the ink absorbing layer, a treatment for increasing the smoothness of the absorbing layer can be performed. After application, the smooth portion can be contacted in a wet state for smoothing treatment, or soft calender treatment can be performed after drying.

  The ink absorbing layer according to the present invention may be a single layer or may be composed of two or more layers. When the ink absorbing layer is composed of two or more layers, the structures of the ink absorbing layers are the same as each other. May be different. Moreover, when it comprises by two or more layers, it is preferable from a viewpoint of productivity improvement that it is the method of apply | coating all the structural layers simultaneously.

  In the production of the ink jet recording medium of the present invention, the drying method may be drying by a known method such as heating with an oven or a heater, or drying by blowing warm air like a dryer. The film surface may be roughened by boiling, or the support may be deformed by heat. On the other hand, if the film surface temperature is too low, it takes a long time to dry and the production efficiency is lowered. Accordingly, the film surface temperature is preferably in the range of 10 to 80 ° C.

  When high gloss is required as an ink jet recording medium, the inorganic fine particle diameter in the ink absorbing layer, binder type, binder amount, selection of additives, coating method, gloss improvement treatment after coating and drying, etc. are devised, and 60 ° It is preferable to set the mirror gloss to 40 or more and less than 80. Also, the image clarity that affects the glossiness is preferably set to 60 or more and less than 100.

  As a form of the ink jet recording medium, in addition to the recording medium having the ink absorbing layer on one side described above, a double-sided recording medium having an ink absorbing layer on both sides can be manufactured. In this case, a support for both sides can be produced by applying a coating liquid containing the resin dispersion according to the present invention to both sides of the water-absorbing support and subjecting both sides to pressure treatment.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Preparation of support for recording material >>
[Preparation of recording material support by surface pressure method (P method)]
(Preparation of Support 1: Comparative Example)
<Preparation of coating liquid 1 containing resin dispersion>
A coating liquid 1 was prepared by diluting resin L1 (styrene butadiene series, average particle size 0.15 μm, Tg 50 ° C., ionic: anionic) to a solid concentration of 40%.

<Application of coating liquid 1 containing resin dispersion>
Rolled base paper A having a width of 230 mm (100 parts of wood pulp, 15 parts of filler (ratio of calcium carbonate 3: talc 1), 0.07 part of sizing agent, 0.8 part of sulfuric acid band, 1.00 part of starch) Using a papermaking material, a paper substrate having a basis weight of 160 g / m ² was obtained with a long paper machine, and then super calendering was performed at a linear pressure of 0.8 kN / cm.) Then, the coating solution 1 was applied so as to have an amount of 30 ml / m ² . After the application, it was dried with hot air of 55 ° C. in a continuous drying process.

  This sample was mirror-finished and then processed by applying a pressure of 4 MPa with a stainless steel plate that had been subjected to a releasability-imparting treatment with a silicone-based material to produce a support 1. At this time, the heating press was heated and kept at 56 ° C.

(Production of supports 2 to 23)
In the production of the support 1, the support 2 was similarly prepared except that the type of the substrate, the composition of the coating liquid containing the resin dispersion, the drying temperature and the pressure treatment conditions were changed to the conditions shown in Table 1. ~ 23 were made.

  In addition, details of the additives and items described in abbreviations in Table 1 are as follows.

<Base material>
Base material B: Using a papermaking material consisting of 100 parts of wood pulp, 15 parts of filler (calcium carbonate), sizing agent 0.07 part, sulfuric acid band 0.8 part, and starch 2.0 parts, using a long paper machine After obtaining a paper substrate having a basis weight of 160 g / m ² , supercalendering was performed at a linear pressure of 0.8 kN / cm.

<resin>
Resin L2: acrylic ester copolymer system, average particle size 0.20 μm, Tg 36 ° C., ionicity: anionic resin L3: acrylic ester copolymer system, average particle size 0.25 μm, Tg 45 ° C., ionicity: nonionic, polymerization Polyvinyl alcohol having a degree of 1700 is used as a protective colloid Resin L4: acrylic ester copolymer system, average particle size 0.20 μm, Tg 62 ° C., ionicity: nonionic, polyvinyl alcohol having a polymerization degree of 1700 is used as a protective colloid <Pigment>
P1: Kaolin (High white kaolin manufactured by Imeris)
P2: Kaolin (Highly white kaolin manufactured by Imeris) / Titanium oxide (A-220 manufactured by Ishihara Sangyo Co., Ltd.) = 3/1 (mass ratio)
P3: Calcium carbonate (Shiraishi Industry Co., Ltd., Brilliant-15)
P4: Calcium carbonate (Brillant-15, Shiraishi Kogyo Co., Ltd.) / Titanium oxide (A-220, manufactured by Ishihara Sangyo Co., Ltd.) = 3/1 (mass ratio)
<Items in Table 1>
* B: Resin solid content (g / L)
* P: Pigment solid content (g / L)
* V: Viscosity of coating liquid containing resin dispersion (mPa · s)
* C: Application amount of coating solution containing resin dispersion (ml / m ² )
[Preparation of support for recording material by calendar machine (C method)]
(Preparation of support 24)
<Preparation of coating liquid 24 containing resin dispersion>
A coating liquid 24 was prepared by diluting resin L5 (styrene butadiene series, average particle size 0.3 μm, Tg 40 ° C., ionic: anionic) to a solid content concentration of 45%.

<Application of coating liquid 24 including resin dispersion>
Roll paper base C having a width of 200 mm (using a papermaking material consisting of 100 parts of wood pulp, 15 parts of filler (calcium carbonate), 0.07 part of sizing agent, 0.8 part of sulfuric acid band and 1.00 part of starch) After obtaining a paper base material having a basis weight of 160 g / m ^{2 with} a net paper machine, it was super calendered with a linear pressure of 0.8 kN / cm.) was coated so that the amount per of 40 ml / m ^2. After the application, it was dried with warm air at 70 ° C. in a continuous drying process.

  This sample was measured with a super calender consisting of a steel roll (hard polished hard chrome hardness 87 °) / elastic roll (cotton roll), linear pressure 0.2 kN / cm, roll surface temperature 65 ° C., press speed 6 m / min. The support 24 was produced by performing pressure treatment under the conditions described above.

(Production of supports 25 to 28)
Supports 25 to 28 were prepared in the same manner as in the preparation of the support 24 except that the linear pressure conditions during the supercalender treatment were changed as shown in Table 1.

(Preparation of supports 30, 31)
Supports 30 and 31 were prepared in the same manner as in the preparation of the support 24 except that the supercalender treatment was performed twice continuously under the conditions shown in Table 1.

  In addition, as for each pressure unit described in the pressurization conditions described in Table 1, the P method is MPa, and the C method is expressed as a linear pressure in kN / cm.

<Evaluation of support>
Each characteristic material was evaluated and measured according to the following method for each of the recording material supports thus prepared.

[White characteristics: measurement of L ^* a ^* b ^* ]
L ^* a ^* b ^* on the surface side coated with the coating liquid containing the resin dispersion of each recording material support was measured using an X-Rite 938 Spectrodensitometer manufactured by X-Rite.

[Confirmation of gaps]
The following two methods were used to confirm the presence or absence of voids in each of the recording material supports prepared above.

  1) Using a scanning electron microscope (SEM), the surface on which the coating liquid containing the resin dispersion of each support was coated was observed to observe the presence or absence of voids.

Observation conditions: magnification 50000 times 5 points (sample) of 10 μm × 10 μm were selected from a 10 cm × 10 cm support sample, and the presence or absence of voids in the 5 samples was observed.

2) Evaluation was performed by a test method according to the water absorption test method (Cobb) method defined in JIS P8140. When the water absorption was 5 g / m ² or less, it was determined that there was no void.

Evaluation sample area: 100 cm ²
Contact time with water: 120 seconds [Evaluation of support properties after application of ink absorbing layer]
(Ink absorption layer coating)
An ink absorbing layer coating solution having the following composition was applied to the surface of each recording material support on which the coating solution containing the resin dispersion was coated, to prepare samples for evaluation.

  The ink additive layer coating solution was prepared by sequentially mixing the following additives and water.

Gas phase method silica (A-300, primary average particle size 7 nm, manufactured by Nippon Aerosil Industry Co., Ltd.)
10% as solid content
Polyvinyl alcohol (PVA235, manufactured by Kuraray Co., Ltd.) 2% as solid content
Cationic polymer (P-1) 0.2% as solid content
Water-soluble polyaluminum chloride 0.15% as solid content in terms of aluminum oxide
Water was added to finish 100% by mass.

Next, the ink absorbing layer coating solution is applied on a surface coated with a coating solution containing the resin dispersion of each support with a coater under the condition that the silica solid content is 18.0 g / m ^2. After refrigeration setting, it dried with the continuous drying line, and produced for each evaluation.

<Evaluation of cockling resistance>
About each support body which coated the ink absorption layer produced above, the occurrence of cockling (wrinkle) was visually observed, and cockling resistance was evaluated according to the following criteria.

3: The occurrence of cockling is not observed at all. 2: The occurrence of cockling is observed slightly, but it is a quality acceptable for practical use. 1: A strong cockling is generated, and the quality is not practical. Evaluation of curling resistance>
About each support body which coated the ink absorption layer produced above, the occurrence state of curl was visually observed, and the curl resistance was evaluated according to the following criteria.

4: No curling is observed 3: Very weak curling is observed 2: Although weak curling is observed, the curling is removed when left in a laminated state 1: Strong curling occurs and the laminated state However, curling may not be resolved and printer conveyance may be hindered. <Evaluation of glossiness: measurement of specular gloss (60 °), image sharpness (reflection angle 60 °)>
About each support body which coated the ink absorption layer produced above, specular gloss (60 degrees) and image sharpness (reflection angle 60 degrees) were measured according to the following method, and glossiness was evaluated according to the following criteria.

  Specular Gloss (60 °): An incident and reflection angle was measured at 60 ° using a variable angle gloss meter (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd.

  Image sharpness (reflection angle 60 °): The image sharpness specified by JIS K 7105 is measured with a image clarity measuring device ICM-1DP (manufactured by Suga Test Instruments Co., Ltd.) at a reflection of 60 ° and an optical comb of 2 mm (C Value%).

5: Specular gloss is 75 or more and less than 100, image sharpness is 75 or more and less than 99 4: Specular gloss is 75 or more and less than 100, and image clarity is 65 or more and less than 75 3: Specular gloss Is 60 or more and less than 74, and image clarity is 56 or more and less than 65 2: Mirror gloss is 60 or more and less than 74, and image clarity is 45 or more and less than 55 1: Specular gloss is 30 or more, Table 2 shows the results obtained when the image clarity was less than 60 and the image clarity was 20 or more and less than 45.

  As is clear from the results shown in Table 2, the support having the structure defined in the present invention has preferable white background characteristics compared to the comparative example, and in the coating layer formed by the coating liquid containing the resin dispersion. There is no void, and as a result, even if a water-based ink absorbing layer coating solution is applied to the upper part, it prevents the penetration of water components into the water-absorbent support and has excellent cockling resistance, curl resistance and glossiness. You can see that

Example 2
<< Preparation of inkjet recording medium >>
[Production of recording medium 1: comparison]
(Preparation of inkjet recording layer coating solution 1)
The following additives and water were sequentially mixed to prepare an inkjet recording layer coating solution 1.

Gas phase method silica (A-300, primary average particle size 7 nm, manufactured by Nippon Aerosil Industry Co., Ltd.)
10% as solid content
Polyvinyl alcohol (PVA235, manufactured by Kuraray Co., Ltd.) 2% as solid content
Cationic polymer (P-1) 0.2% as solid content
Water-soluble polyaluminum chloride 0.15% as solid content in terms of aluminum oxide
Water was added to finish 100% by mass.

(Formation of inkjet recording layer)
Example 1 The inkjet recording layer coating solution 1 was coated on the prepared support 1 with a coater under the condition that the silica solid content was 18.0 g / m ² , refrigerated after coating, and then a continuous drying line. The recording medium 1 was produced. This recording medium 1 contains 0.27 g / m ² of polyaluminum chloride in terms of alumina oxide.

[Preparation of recording medium 2]
A recording medium 2 was produced in the same manner as in the production of the recording medium 1 except that the support 10 produced in Example 1 was used instead of the support 1.

[Preparation of recording medium 3]
On the recording medium 2 produced above, a water-soluble polyaluminum chloride aqueous solution (overcoat solution) having a solid content concentration of 0.005% when converted to aluminum oxide is overcoated corresponding to 10 ml / m ² , dried and recorded. Medium 3 was produced. This recording medium 3 contains 0.32 g / m ^{2 in} terms of alumina oxide as the total amount of polyaluminum chloride.

[Preparation of recording media 4 to 8]
In the production of the recording medium 3, the concentration of the water-soluble polyaluminum chloride aqueous solution to be overcoated was changed as shown in Table 3, and the recording medium 4 was similarly prepared except that the overcoating was equivalent to 10 ml / m ^2. ~ 8 were made.

[Preparation of recording media 9, 10]
In the production of the recording media 2 and 4, the recording media 9 and 10 were produced in the same manner except that the support 14 produced in Example 1 was used instead of the support 10.

<Evaluation of recording medium>
For each of the recording media prepared above, the maximum density was measured and the glossiness was evaluated according to the following method.

  Using each recording medium produced above, a wedge image and a solid black image of each color were printed in a photographic paper mode with a commercially available inkjet printer (PM-G800: manufactured by Seiko Epson Corporation).

[Measurement of maximum density Dmax]
The maximum density of black and magenta in the created wedge image was measured with a reflection densitometer, and the average value was obtained.

[Evaluation of glossiness]
The produced black solid image was measured for specular gloss (60 °) and image sharpness (reflection angle 60 °) according to the following method, and glossiness was evaluated according to the following criteria.

  Specular Gloss (60 °): An incident and reflection angle was measured at 60 ° using a variable angle gloss meter (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd.

  Image sharpness (reflection angle 60 °): The image sharpness specified by JIS K 7105 is measured with a image clarity measuring device ICM-1DP (manufactured by Suga Test Instruments Co., Ltd.) at a reflection of 60 ° and an optical comb of 2 mm (C Value%).

5: Specular gloss is 41 or more and less than 55, image sharpness is 75 or more and less than 99 4: Mirror gloss is 41 or more and less than 55, and image clarity is 65 or more and less than 75 3: Specular gloss Is 31 or more and less than 40, and image clarity is 56 or more and less than 65 2: Mirror gloss is 31 or more and less than 40, and image clarity is 45 or more and less than 55 1: Specular gloss is 20 or more, Table 3 shows the evaluation results obtained when the image clarity was less than 30 and the image clarity was 20 or more and less than 45.

As is apparent from the results shown in Table 3, the recording medium produced using the recording material support of the present invention has a higher image density and superior glossiness than the comparative example. I understand. In the present invention, the content of the polyvalent metal salt compound in the ink absorbing layer is contained in the range of 0.3 g / m ² or more and 2 g / m ² or less in terms of polyvalent metal oxide, It turns out that the said effect is exhibited more.

Claims (14)

After forming a coating layer by applying a coating layer forming coating solution containing a resin dispersion on at least one surface side of the water-absorbent support, pressure treatment is performed under the condition that substantially no voids remain in the coating layer. A support for recording material, which is obtained by applying. 2. The recording material support according to claim 1, wherein a pressure in the pressure treatment is 5 MPa or more and 50 MPa or less. The recording material support according to claim 1 or 2, wherein the pressure treatment is performed by a calendar machine in a range of a linear pressure of 0.3 kN / cm to 2.0 kN / cm. The temperature at the time of pressurization in the pressure treatment is Tp, and the glass transition temperature of the resin dispersion is Tg. The condition defined by the following formula (1) is satisfied: The support for recording materials according to any one of the above.
Formula (1)
Tg <Tp <Tg × 2 The recording material support according to any one of claims 1 to 4, wherein the pressure treatment is performed a plurality of times. 6. The recording material according to claim 1, wherein a coating liquid for forming a coating layer containing the resin dispersion is applied and then dried at a temperature equal to or higher than Tg of the resin dispersion. Support. The recording material support according to any one of claims 1 to 6, wherein the coating layer containing the resin dispersion contains a pigment. 8. The support for recording material according to claim 7, wherein the pigment is at least one selected from kaolin, calcium carbonate, talc, silica, and alumina. The recording according to claim 7 or 8, wherein when the solid content of the pigment in the coating layer containing the resin dispersion is P and the solid content of the resin is B, the condition defined by the following formula (2) is satisfied. Material support.
Formula (2)
0.13 <P / (P + B) <0.5 The recording material support according to any one of claims 1 to 9, wherein the resin dispersion is polymerized using a water-soluble polymer as a protective colloid. The support for a recording material according to any one of claims 1 to 10, wherein the viscosity of the coating layer forming coating solution containing the resin dispersion is 100 mPa · s or more and 1000 mPa · s or less. . The support for recording material according to any one of claims 1 to 11, wherein L ^* a ^* b ^{* on the} surface of the coating layer containing the resin dispersion is in the range specified below.
Lightness index L ^* > 90 in CIE color space
Perceived chromaticity index is −7 <a ^* <+ 7, −7 <b ^* <− 7 An ink jet recording medium comprising an ink absorbing layer and the support for recording material according to any one of claims 1 to 12. The ink absorbing layer containing a polyvalent metal salt compound in an amount of 0.3 g / m ² or more and 2 g / m ² or less in terms of polyvalent metal oxide, and the recording material according to claim 1. An ink jet recording medium comprising a support.