JP7645677B2 - Inkjet recording medium - Google Patents

Description

The present invention relates to an inkjet recording medium.

Patent document 1 discloses an inkjet recording medium for pigment ink, which is used as a recording medium for inkjet printers and is characterized in that the ink receiving layer has a pigment fixing layer capable of supporting the pigment on top of a solvent absorbing layer capable of absorbing the solvent in the pigment ink.

JP 2000-127613 A

Improved water resistance is required for practical use of inkjet recording media. High water resistance is advantageous for use of inkjet recording media in environments where moisture such as rainwater is present, such as outdoors.

When inkjet printing is performed on an inkjet recording medium in which a base layer, a solvent absorbing layer, and a pigment fixing layer are laminated in that order, as disclosed in Patent Document 1, the pigment in the ink is held in the pigment fixing layer, and the solvent in the ink is absorbed by the solvent absorbing layer.

There is a demand for improving the water resistance of inkjet recording media having the above-mentioned configuration.

Therefore, the present invention aims to provide an inkjet recording medium with high water resistance.

The present inventors have found that the above object can be achieved by the following means:
<<Aspect 1>>
a substrate layer, a porous solvent absorbing layer, and a porous pigment fixing layer are laminated in this order;
the porous solvent absorbing layer contains first inorganic particles and a first binder resin;
the porous pigment fixing layer contains second inorganic particles and a second binder resin, and the second binder resin is a water-insoluble amorphous polyester resin having a sulfonic acid group;
Inkjet recording media.
Aspect 2
2. The inkjet recording medium according to aspect 1, wherein the average primary particle diameter of the second inorganic particles is 0.1 μm to 20.0 μm.
Aspect 3
3. The inkjet recording medium according to aspect 1 or 2, wherein the mass of the second inorganic particles is 20% by mass to 60% by mass with respect to the mass of the porous pigment fixing layer.
Aspect 4
The inkjet recording medium according to any one of Aspects 1 to 3, wherein the porous pigment fixing layer has a thickness of 3.0 μm to 50.0 μm.
Aspect 5
5. The inkjet recording medium according to any one of Aspects 1 to 4, wherein the average primary particle diameter of the first inorganic particles is 3.0 nm to 50.0 nm.
Aspect 6
Aspect 6. The inkjet recording medium according to any one of aspects 1 to 5, wherein the mass of the first inorganic particles is 50% by mass to 95% by mass with respect to the mass of the porous solvent absorbing layer.
Aspect 7
7. The inkjet recording medium according to any one of aspects 1 to 6, wherein the porous solvent absorbing layer has a thickness of 0.1 μm to 20.0 μm.
Aspect 8
8. The inkjet recording medium according to any one of Aspects 1 to 7, wherein the first binder resin is a polyvinyl alcohol-based resin.
Aspect 9
The inkjet recording medium according to any one of Aspects 1 to 8, wherein the first inorganic particles and the second inorganic particles are gel-method silica particles or vapor-phase method silica particles.
Aspect 10
10. The inkjet recording medium according to any one of the preceding aspects, wherein the substrate layer is an opaque substrate layer.

The present invention provides an inkjet recording medium with high water resistance.

FIG. 1 is a schematic diagram showing an inkjet recording medium 1 according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing an inkjet recording medium 2 according to a second embodiment of the present invention.

The following describes in detail the embodiments of the present invention. Note that the present invention is not limited to the following embodiments, and can be modified in various ways within the scope of the disclosure.

The inkjet recording medium of the present invention has a base layer, a porous solvent absorbing layer, and a porous pigment fixing layer laminated in this order, the porous solvent absorbing layer contains first inorganic particles and a first binder resin, the porous pigment fixing layer contains second inorganic particles and a second binder resin, and the second binder resin is a water-insoluble amorphous polyester resin having a sulfonic acid group.

Figure 1 is a schematic diagram showing an inkjet recording medium 1 according to a first embodiment of the present invention.

As shown in FIG. 1, the inkjet recording medium 1 according to the first embodiment of the present invention has a base layer 10, a porous solvent absorbing layer 20, and a porous pigment fixing layer 30 laminated in this order. Here, the porous solvent absorbing layer 20 contains first inorganic particles and a first binder resin. The porous pigment fixing layer 30 contains second inorganic particles and a second binder resin. The second binder resin is a water-insoluble amorphous polyester resin having sulfonic acid groups.

Although not limited by the principle, the principle by which the inkjet recording medium of the present invention has high water resistance is as follows.

As disclosed in Patent Document 1, conventional inkjet recording media contain inorganic particles and polyvinyl alcohol as a resin binder in the pigment fixing layer.

Inkjet recording media with a pigment fixing layer that uses polyvinyl alcohol as a resin binder have low water resistance. This is thought to be because polyvinyl alcohol, a water-soluble resin, has low water resistance, so in an environment where the inkjet recording media is in contact with water, polyvinyl alcohol does not function well as a binder, and inorganic particles tend to fall off from the pigment fixing layer.

It is thought that the water resistance of the inkjet recording medium can be improved by using a water-insoluble amorphous polyester as the resin binder in the pigment fixing layer.

Typically, the pigment fixing layer can be formed by applying a mixture of inorganic particles and a resin binder, such as a slurry, onto the solvent absorbing layer.

However, even if a mixture of inorganic particles and water-insoluble amorphous polyester is applied onto a solvent absorbing layer, it may not be possible to stably form a water-resistant pigment fixing layer on the solvent absorbing layer. This is thought to be because when the mixture is applied onto the solvent absorbing layer, the water-insoluble amorphous polyester, which acts as a resin binder, is absorbed into the solvent absorbing layer.

However, if a water-insoluble non-crystalline polyester resin having a sulfonic acid group is used among the water-insoluble non-crystalline polyesters, a water-resistant pigment fixing layer can be stably formed on the solvent absorbing layer.

This is believed to be because sulfonic acid groups have a high affinity with the inorganic particles used to form the pigment fixing layer. In other words, in a mixture of inorganic particles and a water-insoluble amorphous polyester resin having sulfonic acid groups, such as a slurry, the water-insoluble amorphous polyester resin having sulfonic acid groups is likely to be adsorbed by the inorganic particles.

As a result, even if a mixture of inorganic particles and a water-insoluble amorphous polyester resin having sulfonic acid groups, for example a slurry, is applied onto the solvent absorbing layer, the water-insoluble amorphous polyester resin having sulfonic acid groups is unlikely to be absorbed into the solvent absorbing layer.

The inkjet recording medium of the present invention can be applied to any object on which inkjet printing is performed. The inkjet recording medium of the present invention may be, for example, printing paper, packaging, signs, stickers, etc. In particular, since the inkjet recording medium of the present invention has high water resistance, it may be used for signs, such as stickers, applied to walls and bulletin boards of buildings, and vehicles such as automobiles and motorcycles.

<<Base layer>>
The substrate layer is a layer serving as a substrate on which a porous solvent absorbing layer and a porous pigment fixing layer are laminated in this order.

The substrate layer may be a layer of any material onto which the ink-receiving layer can be laminated. The substrate layer may be paper, cloth, plastic, or the like. When the substrate layer is plastic, polycarbonate, nylon, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, or the like may be used.

The substrate layer may be an opaque substrate layer. Opaque means, for example, that the total light transmittance is less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, less than 5%, or less than 1%. The haze value may be 50% or more, 60% or more, or 70% or more.

Here, the total light transmittance can be measured in accordance with JIS K 7361. The haze value can be measured in accordance with JIS K7136.

The substrate layer may be a colored substrate layer that is colored in any color. The colored substrate layer may be colored, for example, white, blue, red, yellow, orange, purple, green, pink, brown, silver, gray, black, or any other color. The substrate layer may be printed with any pattern, and an example of such printing may be offset printing.

<Porous Solvent Absorption Layer>
The porous solvent absorbing layer contains first inorganic particles and a first binder resin.

The porous solvent absorbing layer is porous due to voids formed between the first inorganic particles. If desired, the porous solvent absorbing layer may further contain various additives such as a crosslinking agent, a dispersant, and an ink fixing agent.

The thickness of the porous solvent absorbing layer may be 0.1 μm to 20.0 μm.

If the thickness of the porous solvent absorbing layer is 0.1 μm or more, the number of pores in the porous solvent absorbing layer can be increased, making it easier to absorb the solvent in the ink, and therefore achieving particularly high ink drying speed. On the other hand, if the thickness of the porous solvent absorbing layer is 20.0 μm or less, the entire ink recording medium can be made thinner, and in addition, the strength of the porous solvent absorbing layer can be particularly increased.

The thickness of the porous solvent absorbing layer may be 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, or 5.0 μm or more, and may be 20.0 μm or less, 15.0 μm or less, 10.0 μm or less, or 5.0 μm or less.

It is particularly preferable that the thickness of the porous solvent absorbing layer is 1.0 μm to 15.0 μm.

Note that the "thickness" of the porous solvent absorbing layer refers to the average thickness.

<First Inorganic Particles>
The first inorganic particles can be any inorganic particles that can form voids in the porous solvent absorbing layer and allow the voids to receive, for example, absorb and/or retain, the solvent in the ink.

The first inorganic particles may be, for example, silica, talc, kaolin, clay, alumina white, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, and mixtures thereof. The silica may be gel-processed silica particles or vapor-phase-processed silica particles. It is particularly preferable that the first inorganic particles are vapor-phase-processed silica particles.

The average primary particle diameter of the first inorganic particles is preferably smaller than the average primary particle diameter of the pigment in the ink. If the average primary particle diameter of the first inorganic particles is smaller than the average primary particle diameter of the pigment in the ink, the pigment is less likely to be absorbed into the porous solvent absorption layer during inkjet printing, i.e., the pigment is more likely to be retained in the porous pigment fixing layer.

The average primary particle diameter of the first inorganic particles is preferably 3.0 nm to 50.0 nm.

The average primary particle diameter of the first inorganic particles may be 3.0 nm or more, 5.0 nm or more, 10.0 nm or more, or 15.0 nm or more, and may be 50.0 nm or less, 40.0 nm or less, 30.0 nm or less, or 20.0 nm or less. It is particularly preferable that the average primary particle diameter of the first inorganic particles is 3.0 nm to 30.0 nm.

The mass of the first inorganic particles relative to the mass of the porous solvent absorption layer is preferably 50% by mass to 95% by mass.

When the mass of the first inorganic particles relative to the mass of the porous solvent absorbing layer is 50% by mass or more, the amount of voids in the porous solvent absorbing layer can be appropriately increased. Therefore, particularly high ink drying speed can be obtained. On the other hand, when the mass of the first inorganic particles relative to the mass of the porous solvent absorbing layer is 95% by mass or less, the strength of the porous solvent absorbing layer can be particularly increased.

The mass of the first inorganic particles relative to the mass of the porous solvent absorbing layer may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more, and may be 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less. It is particularly preferable that the mass of the first inorganic particles relative to the mass of the porous solvent absorbing layer is 70% by mass to 90% by mass.

<First Binder Resin>
The first binder resin can be any binder resin capable of holding the first inorganic particles in the porous solvent absorbing layer.

The first binder resin may be a polyvinyl alcohol-based resin.

Here, "polyvinyl alcohol resin" refers to polyvinyl alcohol or a derivative of polyvinyl alcohol, such as polyvinyl acetal obtained by reacting polyvinyl alcohol with an aldehyde to form an acetal.

The polyvinyl alcohol resin may be a partially benzacetalized polyvinyl alcohol.

<Porous pigment fixing layer>
The porous pigment-fixing layer contains second inorganic particles and a second binder resin.

The porous pigment fixing layer is porous due to voids formed between the second inorganic particles. If desired, the porous pigment fixing layer may further contain various additives such as a crosslinking agent, a dispersant, and an ink fixing agent.

The thickness of the porous pigment fixing layer may be 3.0 μm to 50.0 μm.

If the thickness of the porous pigment fixing layer is 3.0 μm or more, the amount of voids in the porous pigment fixing layer can be increased, making it easier to absorb the solvent in the ink, and therefore achieving particularly high ink drying speed. On the other hand, if the thickness of the porous pigment fixing layer is 50.0 μm or less, the entire ink recording medium can be made thinner, and in addition, the strength of the porous pigment fixing layer can be particularly increased.

The thickness of the porous pigment fixing layer may be 3.0 μm or more, 4.0 μm or more, 5.0 μm or more, or 10.0 μm or more, and may be 50.0 μm or less, 45.0 μm or less, 40.0 μm or less, or 30.0 μm or less.

It is particularly preferable that the thickness of the porous pigment fixing layer is 5.0 μm to 30.0 μm.

Note that the "thickness" of the porous pigment fixing layer refers to the average thickness.

<Second Inorganic Particles>
The second inorganic particles can be any inorganic particles that can form voids in the porous pigment fixing layer and allow the voids to receive, for example, absorb and/or hold, the pigment in the ink.

The second inorganic particles may be, for example, silica, talc, kaolin, clay, alumina white, calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, and mixtures thereof. The silica may be gel-process silica particles or vapor-phase silica particles. It is particularly preferable that the second inorganic particles are gel-process silica particles.

The average primary particle size of the second inorganic particles is preferably 0.1 μm to 20.0 μm.

The average primary particle diameter of the second inorganic particles may be 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, or 1.5 μm or more, and may be 20.0 μm or less, 10.0 μm or less, 5.0 μm or less, or 3.0 μm or less. It is particularly preferable that the average primary particle diameter of the second inorganic particles is 0.1 μm to 5.0 μm.

The mass of the second inorganic particles relative to the mass of the porous pigment fixing layer is preferably 20% by mass to 60% by mass.

When the mass of the second inorganic particles relative to the mass of the porous pigment fixing layer is 20% by mass or more, the amount of voids in the porous pigment fixing layer can be appropriately increased. Therefore, particularly high ink drying speed can be obtained. On the other hand, when the mass of the second inorganic particles relative to the mass of the porous pigment fixing layer is 60% by mass or less, the strength of the porous pigment fixing layer can be particularly increased.

The mass of the second inorganic particles relative to the mass of the porous pigment fixing layer may be 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more, and may be 60% by mass or less, 55% by mass or less, 50% by mass or less, or 45% by mass or less. It is particularly preferable that the mass of the second inorganic particles relative to the mass of the porous pigment fixing layer is 25% by mass to 55% by mass.

<Second Binder Resin>
The second binder resin is a water-insoluble amorphous polyester resin having a sulfonic acid group.

In this invention, "amorphous" means that there is no clear melting peak when the temperature is raised from -100°C to 300°C at a rate of 20°C/min using a differential scanning calorimeter (DSC).

As the amorphous polyester resin, for example, amorphous polyethylene terephthalate (PET) into which sulfonic acid groups have been introduced can be used. Such amorphous polyester resins may have sulfonic acid groups in their side chains. In addition, some of the sulfonic acid groups may be sodium sulfonate groups.

The hydroxyl value of the second binder resin may be 3 KOHmg/g to 10 KOHmg/g. The hydroxyl value of the second binder resin may be 3 KOHmg/g or more, 4 KOHmg/g or more, 5 KOHmg/g or more, or 6 KOHmg/g or more, and may be 10 KOHmg/g or less, 9 KOHmg/g or less, 8 KOHmg/g or less, or 7 KOHmg/g or less. The hydroxyl value can be measured in accordance with JIS K 0070-1992.

The molecular weight of the second binder resin may be 10,000 to 30,000.

The molecular weight of the second binder resin may be 10,000 or more, 13,000 or more, 15,000 or more, or 17,000 or more, and may be 30,000 or less, 27,000 or less, 24,000 or less, or 21,000 or less.

Adhesive layer
In the inkjet recording medium of the present invention, an adhesive layer may be laminated on the side opposite to the side on which the porous solvent absorbing layer and the porous pigment fixing layer are laminated.

The adhesive layer is a layer for attaching the inkjet recording medium of the present invention to another object.

The adhesive layer may be, for example, an acrylic adhesive resin.

The adhesive layer may contain, for example, an ultraviolet absorber to prevent deterioration of adhesiveness over time.

Figure 2 is a schematic diagram showing an inkjet recording medium 2 according to a second embodiment of the present invention.

As shown in FIG. 2, the inkjet recording medium 2 according to the second embodiment of the present invention is similar to that shown in FIG. 1, except that an adhesive layer 40 is laminated on the side of the substrate layer 10 opposite to the side on which the porous solvent absorbing layer 20 and the porous pigment fixing layer 30 are laminated.

Example 1 and Comparative Examples 1 and 2
Example 1
(Formation of Porous Solvent Absorption Layer)
A dispersion medium was prepared by adding 1.7 parts by weight of a cationic polymer (solid content 52.3 wt%) as a dispersant to 50 parts by weight of ion-exchanged water, followed by 35 parts by weight of 2-propanol. While stirring the dispersion medium with a homogenizer (product name: Biomixer BM-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at a rotation condition of 3000 rpm, 15 parts by weight of vapor-phase silica (average primary particle diameter 7 nm) as the first inorganic particles was added little by little to prepare a silica dispersion liquid with a solid content of 15.6 wt%.

Next, 70 parts by weight of the silica dispersion was mixed with 31 parts by weight of a water/2-propanol solution of partially benzacetalized polyvinyl alcohol (degree of polymerization: 3500, degree of benzacetalization: 8 mol%) as the first binder resin, so that the solids ratio of resin/silica was 25/75.

Next, 0.1 parts by weight of a hexamethylene diisocyanate-based curing agent was added and stirred to prepare a coating liquid for the porous solvent absorbing layer.

Next, using a tabletop coater (product name: Control Coater 7000 model, manufactured by Imoto Manufacturing Co., Ltd.), the coating liquid was applied onto a polyethylene terephthalate (PET)-based synthetic paper substrate, which was then dried in an oven at 100°C for 2 minutes and then aged at 60°C for 1 day to form a 10 μm-thick porous solvent-absorbing layer on the substrate.

(Formation of Porous Pigment Fixing Layer)
To a mixed liquid of 42 parts by weight of methyl ethyl ketone and 42 parts by weight of cyclohexanone, 1.5 parts by weight of polyether phosphate ester was added, and 15 parts by weight of gel-process silica (average particle size 1.7 μm) as second inorganic particles was added thereto, followed by dispersion using a homogenizer (product name: Biomixer BM-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.) to prepare a silica dispersion liquid.

Next, an amorphous polyester resin having a sulfonic acid group in the molecular chain (molecular weight: 18×10 ³ , hydroxyl value: 6 KOH mg/g) was dissolved in a solvent having a 1:1 ratio of methyl ethyl ketone/cyclohexanone to prepare a solution of an amorphous polyester resin having a resin content of 40% by mass.

39 parts by weight of this amorphous polyester resin solution and 60 parts by weight of the silica dispersion were mixed and stirred, and 0.5 parts by weight of a hexamethylene diisocyanate-based curing agent was added and stirred to prepare a coating liquid.

Next, the coating liquid was applied to the surface of the porous solvent absorbing layer using a bar coater, and then it was dried in an oven at 100°C for 2 minutes, and then aged at 60°C for 3 days to form a 15 μm thick porous pigment fixing layer on the porous solvent absorbing layer.

In this manner, the inkjet recording medium of Example 1 was prepared. The composition of the inkjet recording medium of Example 1 is shown in Table 1 below.

Comparative Example 1
An inkjet recording medium of Comparative Example 1 was prepared in the same manner as in Example 1, except for the following points.

(Formation of Porous Pigment Fixing Layer)
To a mixed liquid of 51 parts by weight of water and 34 parts by weight of 2-propanol, 15 parts by weight of gel-process silica (average particle size 1.7 μm) as second inorganic particles was added, and the mixture was dispersed using a homogenizer (product name: Biomixer BM-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.) to prepare a silica dispersion.

Next, 63 parts by weight of a water/2-propanol solution of partially benzacetalized polyvinyl alcohol (degree of polymerization: 3500, degree of benzacetalization: 8 mol%) as a second binder resin was mixed and stirred with 37 parts by weight of the silica dispersion, and 0.1 parts by weight of a hexamethylene diisocyanate-based hardener was added and stirred to prepare a coating liquid.

Next, the coating liquid was applied to the surface of the porous solvent absorbing layer using a bar coater, and then it was dried in an oven at 100°C for 2 minutes, and then aged at 60°C for 3 days to form a porous pigment fixing layer with a thickness of 15 μm.

The composition of the inkjet recording medium for Comparative Example 1 is shown in Table 1 below.

Comparative Example 2
An inkjet recording medium of Comparative Example 2 was prepared in the same manner as in Example 1, except that the second binder resin used in the porous pigment fixing layer was an amorphous polyester resin (molecular weight: 16× ¹⁰ , hydroxyl value: 7 KOHmg/g) having no sulfonic acid group in the molecular chain.

The composition of the inkjet recording medium for Comparative Example 2 is shown in Table 1 below.

<evaluation>
(Film-forming properties)
The surface of the ink jet recording medium of each example on which the porous pigment fixing layer was formed was rubbed with a finger to evaluate whether a coating film was formed.

If no transfer of gel-method silica is observed on the finger, it means that a porous pigment fixing layer has been formed. Also, if transfer of gel-method silica is observed on the finger, it means that a porous pigment fixing layer has not been formed.

In Table 1 below, the cases where no transfer of gel-method silica was observed on the finger are marked as "good," and the cases where transfer of gel-method silica was observed on the finger are marked as "poor."

(Quick-drying ink)
On the inkjet recording medium of each example, 100-point characters were printed with an aqueous pigment ink using an inkjet printer (product name: PIXUS TR703, manufactured by Canon Inc.), and the state of the characters was evaluated when the characters were rubbed with gauze 5 seconds after being discharged.

If there is no trailing when rubbed with gauze, it means that the ink dries quickly. If there is trailing when rubbed with gauze, it means that the ink dries quickly.

In Table 1 below, products that did not leave a trail when rubbed with gauze are marked as "good," and products that did leave a trail when rubbed with gauze are marked as "poor." Note that "-" indicates that no evaluation was performed.

(water resistance)
The surface of the ink jet recording medium of each example on which the porous pigment fixing layer was formed was strongly rubbed 200 times with gauze containing water, and peeling of the porous pigment fixing layer was evaluated.

Those in which the porous pigment fixing layer did not peel off indicate that they had high water resistance. On the other hand, those in which the porous pigment fixing layer peeled off indicate that they had low water resistance.

In Table 1 below, samples in which the porous pigment fixing layer did not peel off are marked "good," and samples in which the porous pigment fixing layer peeled off are marked "poor." Note that "-" indicates that no evaluation was performed.

<result>
The configuration and evaluation results of each example are shown in Table 1 below.

As shown in Table 1, in Example 1, in which the second binder resin used in the porous pigment fixing layer was an amorphous polyester resin having sulfonic acid groups in the molecular chain, good results were obtained in terms of film-forming properties, ink quick-drying properties, and water resistance.

In contrast, in Comparative Example 1, in which the second binder resin used in the porous pigment fixing layer was a polyvinyl alcohol-based resin, the film-forming properties and ink quick-drying properties were good, but the water resistance was low.

In addition, in Comparative Example 2, in which the second binder resin used in the porous pigment fixing layer was an amorphous polyester resin that did not have a sulfonic acid group in the molecular chain, it was not possible to form a porous pigment fixing layer in the first place. Therefore, the ink quick-drying property and water resistance were not evaluated.

Reference Signs List 1 and 2 Inkjet recording medium 10 Base layer 20 Porous solvent absorbing layer 30 Porous pigment fixing layer 40 Adhesive layer

Claims (8)

a substrate layer, a porous solvent absorbing layer, and a porous pigment fixing layer are laminated in this order;
the porous solvent absorbing layer contains fumed silica particles and a first binder resin;
the porous pigment fixing layer contains gel-processed silica particles and a second binder resin, and the second binder resin is a water-insoluble amorphous polyester resin having a sulfonic acid group;
The average primary particle diameter of the gel method silica particles is 0.5 μm to 20.0 μm.
Inkjet recording media. 2. The inkjet recording medium according to claim 1 , wherein the mass of said gel method silica particles is 20% by mass to 60% by mass with respect to the mass of said porous pigment fixing layer. 3. The inkjet recording medium according to claim 1 , wherein the porous pigment fixing layer has a thickness of 3.0 μm to 50.0 μm. The inkjet recording medium according to any one of claims 1 to 3 , wherein the average primary particle diameter of the fumed silica particles is from 3.0 nm to 50.0 nm. 5. The inkjet recording medium according to claim 1 , wherein a mass of the fumed silica particles is from 50% by mass to 95% by mass of the porous solvent absorbing layer. The inkjet recording medium according to any one of claims 1 to 5 , wherein the porous solvent absorbing layer has a thickness of 0.1 µm to 20.0 µm. 7. The ink jet recording medium according to claim 1, wherein the first binder resin is a polyvinyl alcohol resin. The inkjet recording medium according to any one of claims 1 to 7 , wherein the substrate layer is an opaque substrate layer.

Images