JP2024000866A - Recording medium - Google Patents

Abstract

To provide a recording medium for inkjet recording that comprises a flexible base material while having superior resistance to cracking under bending and superior resistance to outdoor weather.SOLUTION: A recording medium for inkjet recording comprises a substrate composed of multifilament yarn, and an ink reception layer provided on at least one side of the substrate. The ink reception layer comprises an inorganic pigment and a water-insoluble resin. A standard deviation of a thickness of the multifilament yarn is 20 μm or more and 40 μm or less. The water-insoluble resin has a glass transition point of -40°C or higher and 10°C or lower.SELECTED DRAWING: None

Description

The present invention relates to a recording medium.

BACKGROUND ART In recent years, as a recording medium for inkjet recording, an inkjet cloth that uses a lightweight fabric as a base material, which is rich in texture and flexibility, in place of paper or resin film, has been attracting attention. The inkjet cloth is displayed outdoors, for example, as a banner or poster, or inserted into a frame with a backlight. Therefore, cracks may occur in the ink-receiving layer due to flapping in the wind or insertion into the frame, and images may be easily lost. In other words, it cannot be said that the durability of conventional inkjet cloths, such as outdoor weather resistance or folding resistance, is necessarily sufficient, and it is important to have an ink-receiving layer that prevents images from being lost even when posted outdoors or inserted into a frame. is required.

In order to improve durability such as flexibility, for example, inkjet recording in which an ink receiving layer containing amorphous silica and a water-swellable polyurethane resin with a film elongation of 300 to 500% is provided on a fiber base fabric. A fabric has been proposed (Patent Document 1).

Patent No. 4237987

The present inventors have studied the fabric proposed in Patent Document 1 and confirmed that it has a certain degree of resistance to folding and cracking. However, it has been found that the resistance to folding and cracking required when used in a state where it is inserted into a frame or the like is not necessarily sufficient. Furthermore, since the fabric proposed in Patent Document 1 contains a water-swellable polyurethane resin in its ink-receiving layer, it cannot be said that its outdoor weather resistance is necessarily good, and there is room for improvement. .

Therefore, an object of the present invention is to provide a recording medium for inkjet recording which has a flexible base material, has good resistance to folding and cracking, and has excellent outdoor weather resistance.

That is, according to the present invention, there is provided a recording medium for inkjet recording comprising a base material formed of multifilament yarn and an ink receiving layer provided on at least one surface of the base material, The ink receiving layer contains an inorganic pigment and a water-insoluble resin, the standard deviation of the thickness of the multifilament thread is 20 μm or more and 40 μm or less, and the water-insoluble resin has a glass transition point of -40°C or more and 10°C A recording medium is provided which is characterized by the following.

According to the present invention, it is possible to provide a recording medium for inkjet recording that has a flexible base material, has good resistance to folding, and has excellent outdoor weather resistance.

<Recording medium>
Hereinafter, the present invention will be further explained in detail by citing preferred embodiments. Hereinafter, a recording medium for inkjet recording will also be simply referred to as a "recording medium." Physical property values are values at room temperature (25° C.) unless otherwise specified.

The inventors of the present invention have conducted extensive studies in order to find a configuration of a recording medium for inkjet recording that has a flexible base material, has good resistance to folding, and has excellent outdoor weather resistance. As a result, the following configuration was discovered and the present invention was completed. That is, the recording medium of the present invention is a recording medium for inkjet recording that includes a base material formed of multifilament yarn and an ink receiving layer provided on at least one surface of the base material. The ink receiving layer contains an inorganic pigment and a water-insoluble resin. The standard deviation of the thickness of the multifilament yarn is 20 μm or more and 40 μm or less. The glass transition point of the water-insoluble resin is -40°C or higher and 10°C or lower.

In order to improve the cracking resistance of a base material formed of a plurality of multifilament yarns, it is necessary to improve the adhesion between the ink receiving layer and the base material. In the case of general inkjet cloths, a base material made of multifilament yarn with a uniform thickness is often used from the viewpoints of manufacturing method, cost, and productivity. When the thickness of the multifilament yarns is uniform, the multifilament yarns do not unravel and are evenly lined up. For this reason, when a coating liquid for an ink-receiving layer is applied to the surface of a base material made of multifilament yarns of uniform thickness, the contact area between the base material and the coating liquid becomes small, and the multifilament yarns and It becomes difficult to improve the adhesion with the resin (binder resin) in the coating liquid. As a result, the base material and the ink-receiving layer tend to separate into layers, and the bending force cannot be alleviated, resulting in a decrease in cracking resistance.

On the other hand, the standard deviation of the thickness of the multifilament yarn forming the base material of the recording medium of the present invention is 20 μm or more and 40 μm or less. When the standard deviation of the thickness of the multifilament yarn is 20 μm or more and 40 μm or less, the multifilament yarn is appropriately unraveled. Therefore, when the coating liquid for the ink-receiving layer is applied to the surface of a base material made of multifilament yarns whose standard deviation of thickness is within the above range, the contact area between the base material and the coating liquid is As the resin (binder resin) increases, it becomes easier for the resin (binder resin) to dig into the inside of the base material. This improves the adhesion between the base material and the ink-receiving layer, and improves the resistance to folding and cracking of the recording medium. Furthermore, if the standard deviation of the thickness of the multifilament yarn is within the above range, even if the ink receiving layer flows out, it will easily get caught on the multifilament yarn, making it less likely to fall off. Therefore, even if a recording medium on which an image is recorded is posted outdoors and exposed to light, heat, rain, etc., the ink-receiving layer is prevented from flowing out or missing, and image deterioration is suppressed. I can do it.

If the standard deviation of the thickness of the multifilament yarn is less than 20 μm, the adhesion between the base material and the ink receiving layer will be insufficient, making it impossible to improve the resistance to folding and cracking. Furthermore, images tend to deteriorate due to outdoor display, etc., and outdoor weather resistance cannot be improved. On the other hand, if the standard deviation of the thickness of the multifilament yarn is more than 40 μm, the multifilament yarn may fray or come off, making it easy for the ink-receiving layer to fall off from the base material, improving outdoor weather resistance. I can't.

The ink receiving layer of the recording medium of the present invention contains a water-insoluble resin as a binder resin. By containing a water-insoluble resin in the ink-receiving layer, the water resistance and weather resistance of the ink-receiving layer can be improved. Further, the glass transition point of this water-insoluble resin is -40°C or more and 10°C or less. A water-insoluble resin whose glass transition point is within the above range easily penetrates between the multifilament threads constituting the base material, thereby improving the adhesion of the formed ink-receiving layer to the base material. If the glass transition point of the water-insoluble resin exceeds 10° C., the permeability into the base material will decrease, making it impossible to improve the folding resistance of the recording medium. On the other hand, if the glass transition point of the water-insoluble resin is less than -40°C, it will be susceptible to heat, making it impossible to improve outdoor weather resistance.

(Base material)
The substrate is formed of multifilament yarns comprised of transitions, including, for example, multifilament warp yarns and multifilament weft yarns. The fibers constituting the multifilament yarn include natural fibers and chemical fibers. Examples of natural fibers include vegetable fibers such as cotton and hemp; animal fibers such as silk, wool, and animal hair; and the like. Chemical fibers include regenerated fibers such as viscose rayon, cuprammonium rayon, polynosic, and purified cellulose; semi-synthetic fibers such as cellulose diacetate and cellulose triacetate; synthetic fibers such as polyester, polyamide, polyacrylonitrile, polyvinyl alcohol, and polyurethane. Fiber; etc. can be mentioned. Moreover, composite fibers made by combining different fibers can also be used. The fibers constituting the multifilament yarn are preferably fibers that are strong in tension and stretch appropriately, considering the case where the recording medium is used as a bulletin board. Specifically, fibers such as polyester, polyamide, and acrylic resin are preferred.

A multifilament yarn made of chemical fiber can be produced according to the following method. First, a liquid material of a polymeric compound is extruded through a nozzle and solidified to obtain a long continuous filament. Next, a single multifilament yarn can be produced by converging and twisting the plurality of filaments. Then, by weaving the multifilament yarns (warp and weft) in any method, a base material made of the multifilament yarns can be obtained. By appropriately combining the warp and weft types and weaving method, a base material with a desired texture and thickness can be obtained.

From the viewpoint of improving morphological stability and structure stability, it is preferable to heat set (heat treat) the obtained base material. The heat setting conditions are preferably, for example, from the viewpoint of molecular orientation of polyester, at 160° C. or higher and 220° C. or lower for 1 minute or more and 5 minutes or less. Furthermore, the standard deviation of the thickness of the multifilament yarn can be controlled by the presence or absence of tension when heat-setting the base material.

The standard deviation of the thickness of multifilament yarn can be determined according to the following method. First, the surface of the base material is photographed at a magnification of 50 times using a scanning electron microscope (SEM). Next, the widths of the warp and weft at ten arbitrarily selected locations are measured, and the standard deviations of the widths of the warp and weft are calculated. Then, the average value of the calculated standard deviation of the width of the warp and the standard deviation of the width of the weft can be set as the "standard deviation of the thickness of the multifilament yarn."

The thickness (film thickness) of the base material is preferably 50 μm or more and 800 μm or less, more preferably 200 μm or more and 600 μm or less. The thickness of the substrate can be measured and calculated according to the following method. First, a cross section of a recording medium cut out with a microtome is observed with a scanning electron microscope. Then, the thickness of five or more arbitrary points on the base material is measured, and the average value thereof is taken as the thickness of the base material. Note that the thicknesses of layers (films) other than the base material are also measured and calculated in the same manner.

The basis weight of the base material is preferably 100 g/m ² or more and 600 g/m ² or less, more preferably 150 g/m ² or more and 400 g/m ² or less.

(Ink receiving layer)
The ink receiving layer provided on at least one surface of the base material may be a single layer or a multilayer of two or more layers. The ink-receiving layer may be provided on only one side of the base material, or may be provided on both sides. The thickness (film thickness) of the ink-receiving layer is preferably 100 μm or less, more preferably 40 μm or less, and particularly preferably 30 μm or less from the viewpoint of resistance to folding and cracking. Further, from the viewpoint of image quality, the thickness (film thickness) of the ink receiving layer is preferably 5 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more.

The ink-receiving layer is formed, for example, by applying a coating liquid for an ink-receiving layer containing an inorganic pigment and a water-insoluble resin onto the surface of a substrate and drying it. The coating amount of the entire ink-receiving layer is preferably 40 g/m ² or less from the viewpoint of not impairing the texture of the base material. Further, from the viewpoint of ink color development and ink absorbability, it is preferable that the amount is 10 g/m ² or more.

[Inorganic pigment]
The ink-receiving layer contains an inorganic pigment. It is preferable to use wet silica as the inorganic pigment. Wet silica is typically particles containing _, by dry weight, 93% or more of _SiO2 , 5% or less of _Al2O3 , and 5% or less of _Na2O . Examples of wet silica include so-called white carbon, silica gel, and porous wet silica.

Methods for producing silica are broadly divided into dry methods and wet methods. Dry methods include dry combustion method and heating method. Further, wet methods include a wet precipitation method and a wet gel method. The dry combustion method is a method in which a mixture of vaporized silicon tetrachloride and hydrogen is usually burned in air at 1,600 to 2,000° C., and is also called a gas phase method. The wet precipitation method is a method in which silica (SiO ₂ ) is usually precipitated by reacting sodium silicate with sulfuric acid in an aqueous solution. The specific surface area and primary particle diameter of silica can be adjusted. Furthermore, by appropriately changing the drying conditions and pulverization conditions, the secondary particle diameter and physical properties of the obtained silica can be subtly changed.

The wet gel method is usually a method in which sodium silicate and sulfuric acid are added simultaneously and reacted. In the case of silica particles, for example, dehydration condensation of silanol groups progresses, and silica having a three-dimensional hydrogel structure can be obtained. Silica having a three-dimensional hydrogel structure has relatively small primary particles and can form secondary particles with a large specific surface area. By changing the reaction conditions etc., the primary particle diameter can be adjusted and secondary particles with different oil absorption amounts can be formed.

The term "average particle size" as used herein refers to the volume average particle size measured and calculated using a laser diffraction type particle size distribution measurement device (for example, "SALD-2300" manufactured by Shimadzu Corporation). . When wet silica is used as an inorganic pigment, wet silica exists as secondary particles formed by association of primary particles, so the "average particle diameter" of wet silica means "volume average secondary particle diameter."

The average particle diameter of the inorganic pigment is preferably 2.0 μm or more, more preferably 4.0 μm or more, from the viewpoint of image color development. The average particle diameter of the inorganic particles is preferably 14.0 μm or less, more preferably 12.0 μm or less, from the viewpoint of the strength of the ink-receiving layer and ink bleeding.

[Water-insoluble resin]
The water-insoluble resin is a material that functions as a so-called binder that can bind together inorganic pigments, which are inorganic particles, to form an ink-receiving layer. The term "water-insoluble resin" as used herein means a resin in which 95% by mass or more remains when immersed in warm water at 80°C for 2 hours. The glass transition point of the water-insoluble resin is -40°C or higher and 10°C or lower, preferably -25°C or higher and 10°C or lower. The glass transition point of the water-insoluble resin can be measured by differential scanning calorimetry (DSC method).

The value of the ratio (M2/M1) of the tensile elongation (M2 (%)) of the water-insoluble resin to the tensile elongation (M1 (%)) of the base material is 2.6 or more and 7.5 or less. preferable. By setting the value of the above ratio to 2.6 or more and 7.5 or less, the water-insoluble resin can better follow the bending of the base material, so that the folding and cracking resistance of the recording medium can be further improved. The tensile elongation is the elongation at break measured by a method based on JIS K 6251:2010. The shape of the test piece used when measuring the elongation at break is a size 3 dumbbell, and the tensile speed is 50 mm/min. The thickness of the water-insoluble resin to be measured is 2.0 mm. Regarding the base material, the base material itself is the measurement target.

The tensile elongation (M2 (%)) of the water-insoluble resin is preferably 500% or more and 1,500% or less. By using a water-insoluble resin having a tensile elongation within the above range, the water-insoluble resin can better follow the bending of the base material, so that the folding and cracking resistance of the recording medium can be further improved.

From the viewpoint of ink absorption, the content of the water-insoluble resin in the ink-receiving layer per 100 parts by mass of inorganic particles is preferably 100 parts by mass or less, and more preferably 70 parts by mass or less. Further, from the viewpoint of binding property of the ink-receiving layer, the content of the water-insoluble resin in the ink-receiving layer per 100 parts by mass of inorganic particles is preferably 30 parts by mass or more, and preferably 50 parts by mass or more. More preferred.

From the viewpoint of water resistance, the water-insoluble resin is preferably at least one selected from the group consisting of acrylic resin, polycarbonate-modified urethane resin, and polyether-modified urethane resin, and more preferably acrylic resin.

(1) Acrylic resin "Acrylic resin" in this specification means a polymer of (meth)acrylic acid ester. As long as it uses (meth)acrylic acid ester as a monomer, it may be a monopolymer or a copolymer with other monomers.

Examples of acrylic esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-dimethylaminoethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl acrylate. Examples include hydroxybutyl, isobutyl acrylate, octyl acrylate, lauryl acrylate, and stearyl acrylate. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-dimethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 2-methacrylate. Examples include hydroxybutyl, isobutyl methacrylate, octyl methacrylate, lauryl methacrylate, and stearyl methacrylate.

Other monomers that can be copolymerized with the (meth)acrylic ester include vinyl monomers. Examples of vinyl monomers include styrenes and their derivatives such as styrene, vinyltoluene, vinylbenzoic acid, α-methylstyrene, p-hydroxymethylstyrene, and styrene sulfonic acid; methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether, and N-vinyl Examples include vinyl ethers such as pyrrolidone, 2-vinyloxazone, and vinylsulfonic acid, and derivatives thereof.

As the acrylic resin, polyacrylic esters, polymethacrylic esters, and copolymers of acrylic esters and methacrylic esters are preferred. Among these, copolymers of methacrylic esters and acrylic esters are preferred because the glass transition point of the resulting acrylic resin can be controlled by designing the copolymerization ratio of methacrylic esters and acrylic esters.

(2) Urethane resin "Urethane resin" as used herein means a resin having urethane bonds in its structure. As the urethane resin, at least one of a polycarbonate-modified urethane resin and a polyether-modified urethane resin is used. Hereinafter, the polycarbonate-modified urethane resin and the polyether-modified urethane resin will also be collectively referred to simply as "urethane resin."

A urethane resin can be obtained by reacting a polyisocyanate, a polyol, and a chain extender. Examples of polyisocyanates include aromatic isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, toridine diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and isophorone diisocyanate. Examples include aliphatic isocyanates and alicyclic isocyanates.

Examples of the polyol include polyether polyols such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol; and polycarbonate polyols such as polyhexamethylene carbonate. As the chain extender, compounds having active hydrogen atoms such as low molecular weight glycols such as ethylene glycol, low molecular diamines, and low molecular amino alcohols can be used. These components can be used alone or in combination of two or more.

[Water-soluble resin]
The ink receiving layer may further contain a water-soluble resin. Examples of water-soluble resins include polyvinyl alcohol, polyvinylpyrrolidone, and water-soluble cellulose. From the viewpoint of water resistance, the ink receiving layer preferably (i) does not contain a water-soluble resin; or (ii) contains a water-soluble resin in an amount of 14% by mass or less based on the water-insoluble resin.

[Surfactant]
The ink-receiving layer may contain a surfactant from the viewpoint of increasing permeability into the base material. As the surfactant, a nonionic surfactant is preferable from the viewpoint of compatibility with the coating liquid for the ink receiving layer. Furthermore, as the nonionic surfactant, silicone surfactants and acetylene surfactants are preferred. Silicone surfactants are preferred because they have good compatibility with wet silica. Furthermore, acetylene surfactants are preferable because they have good compatibility with polyvinyl alcohol, which is sometimes used as a binder resin.

Examples of the silicone surfactant include the following trade names: BYK346, BYK347, BYK348 (all manufactured by BYK Chemie Japan). Examples of the acetylene surfactant include the following trade names such as Surfynol 420 and Surfynol 440 (both manufactured by Air Products).

[Other additives]
The ink-receiving layer may contain additives other than the various components described above. Other additives include pH adjusters, thickeners, fluidity improvers, antifoaming agents, foam inhibitors, mold release agents, penetrants, colored pigments, colored dyes, optical brighteners, ultraviolet absorbers, Antioxidants, preservatives, antifungal agents, waterproofing agents, dye fixing agents, hardening agents, weather-resistant materials, and the like can be mentioned.

<Method for manufacturing recording medium>
The method for manufacturing the above-mentioned recording medium is not particularly limited. For example, a step of preparing a coating solution for the ink-receiving layer (1) and a coating solution for the ink-receiving layer (2) (coating solution preparation step), and applying the prepared coating solution to the substrate. It is preferable to manufacture the recording medium by a manufacturing method including a step (coating step).

The base material formed from multifilament yarn can be produced by a general weaving method. Specifically, the desired base material, greige fabric, can be produced through a rough warping process, a gluing process, a beaming process, a twilling process, a drawing process, a weaving process, and the like. Further, by heat-setting the gray fabric, the standard deviation of the thickness of the multifilament yarn can be set within a desired range, and the dimensional stability of the base material can be improved.

The intended recording medium can be obtained by applying the prepared ink-receiving layer coating liquid to a substrate to form a coating layer, and then drying the formed coating layer. To apply the coating liquid to the base material, a curtain coater, an extrusion type coater, a slide hopper type coater, an air knife, a bar coater, etc. can be used. The coating liquid applied to the substrate may be heated. To dry the coating layer, use a hot air dryer such as a straight tunnel dryer, arch dryer, air loop dryer, sine curve air float dryer, or a dryer that uses infrared rays, heated dryers, microwaves, etc. I can do it.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples in any way unless it exceeds the gist thereof. Regarding component amounts, "parts" and "%" are based on mass unless otherwise specified.

<Manufacture of base material>
Base materials 1 to 5 were manufactured using polyester multifilament yarns of the types shown in Table 1 and according to the conditions shown in Table 1 (heat setting temperature and presence or absence of tension during heat setting). The surface of the manufactured base material was observed with a SEM (50x magnification), and the standard deviation of the thickness of the warp and weft at 10 randomly extracted locations was measured and calculated. Then, the average value of the calculated standard deviations was calculated and defined as the "standard deviation (μm) of the thickness of the multifilament yarn."

<Preparation of inorganic particle dispersion>
(Inorganic particle dispersion liquid 1)
As an inorganic pigment (inorganic particles), wet silica powder (trade name "Silysia 660", manufactured by Fuji Silysia Chemical, average particle diameter: 5.7 μm) was prepared. After adding the wet silica powder to water, the mixture was stirred for 30 minutes using a mixer to obtain an inorganic particle dispersion 1 (content of inorganic particles: 20%). The average particle size of the inorganic particles was measured using a laser diffraction type particle size distribution measuring device (trade name "SALD-2300", manufactured by Shimadzu Corporation).

(Inorganic particle dispersion 2)
As an inorganic pigment (inorganic particles), alumina powder (trade name "Disperal HP30", manufactured by Sasol, average particle diameter: 0.4 μm) was prepared. Further, 1.5 parts of methanesulfonic acid as peptizing acid was added to 98.5 parts of water to obtain an aqueous methanesulfonic acid solution. After adding alumina powder to the obtained aqueous methanesulfonic acid solution, the mixture was stirred for 30 minutes using a mixer to obtain an inorganic particle dispersion 2 (content of inorganic particles: 23%).

<Preparation of binder resin>
The following types of binder resins were prepared. Among the binder resins shown below, "Pateracol IJ-70" and "PVA235" are water-soluble resins, and the others are water-insoluble resins.
・Movinyl 7820 (acrylic resin, made by Japan Coating Resin, glass transition point: 4℃, tensile elongation: 1,550%)
・Movinyl 6951 (acrylic resin, made by Japan Coating Resin, glass transition point: -25℃, tensile elongation: 550%)
・Sumikaflex S-3950 (ethylene/vinyl acetate copolymer resin, manufactured by Sumika Chemtex, glass transition point: -50°C, tensile elongation: 400%)
・Acronal YJ3031Dap (acrylic resin, manufactured by BASF, glass transition point: 12°C, tensile elongation: 500%)
・Sumikaflex 401HQ (ethylene/vinyl acetate copolymer resin, manufactured by Sumika Chemtex, glass transition point: -18°C, tensile elongation: 850%)
・Sumikaflex 752 (ethylene/vinyl acetate copolymer resin, manufactured by Sumika Chemtex, glass transition point: 15°C, tensile elongation: 360%)
・Pateracol IJ-70 (urethane resin, manufactured by DIC, glass transition point: 0°C, tensile elongation: 380%)
・PVA235 (polyvinyl alcohol resin, manufactured by Kuraray, glass transition point: 58°C, tensile elongation: 220%)

<Preparation of coating liquid for ink receiving layer>
(Coating liquid A)
A mixture was obtained by mixing Movinyl 7820 and Movinyl 6951 at a mass ratio of 1:1. The glass transition point of the resin in the resulting mixture was -10°C, and the tensile elongation was 1,050%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid A. Obtained.

(Coating liquid B)
A mixture was obtained by mixing Movinyl 7820 and Acronal YJ3031Dap at a mass ratio of 3:7. The glass transition point of the resin in the resulting mixture was 10°C, and the tensile elongation was 1,025%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio (solid content equivalent) of 60 parts of inorganic particles to 35 parts of resin, and then stirred for 30 minutes using a mixer to form coating liquid B. Obtained.

(Coating liquid C)
A mixture was obtained by mixing Movinyl 6951 and Sumikaflex S-3950 at a mass ratio of 2:3. The glass transition point of the resin in the resulting mixture was -40°C, and the tensile elongation was 460%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid C. Obtained.

(Coating liquid D)
Inorganic particle dispersion 1 and Movinyl 6951 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to obtain coating liquid D. .

(Coating liquid E)
A mixture was obtained by mixing Movinyl 7820 and Movinyl 6951 at a mass ratio of 7:3. The glass transition point of the resin in the resulting mixture was -4°C, and the tensile elongation was 1,250%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio (solid content equivalent) of 60 parts of inorganic particles to 35 parts of resin, and then stirred for 30 minutes using a mixer to form coating liquid E. Obtained.

(Coating liquid F)
A mixture was obtained by mixing Movinyl 6951 and Sumikaflex S-3950 at a mass ratio of 9:1. The glass transition point of the resin in the resulting mixture was -27°C, and the tensile elongation was 535%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio (solid content equivalent) of 60 parts of inorganic particles to 35 parts of resin, and then stirred for 30 minutes using a mixer to form coating liquid F. Obtained.

(Coating liquid G)
Inorganic particle dispersion 1 and Movinyl 7820 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to obtain coating liquid G. .

(Coating liquid H)
A mixture was obtained by mixing Sumikaflex S-3950 and Acronal YJ3031Dap at a mass ratio of 1:9. The glass transition point of the resin in the resulting mixture was 8° C., and the tensile elongation was 490%. Inorganic particle dispersion 1 and the resulting mixture were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid H. Obtained.

(Coating liquid I)
Inorganic particle dispersion 1 and Sumikaflex 401HQ were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to obtain coating liquid I. Ta.

(Coating fluid J)
A mixture was obtained by mixing Movinyl 7820 and Movinyl 6951 at a mass ratio of 1:1. The glass transition point of the resin in the resulting mixture was -10°C, and the tensile elongation was 1,050%. Inorganic particle dispersion 2 and the resulting mixture were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid J. Obtained.

(Coating liquid K)
Inorganic particle dispersion 1 and Sumikaflex S-3950 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid K. I got it.

(Coating liquid L)
Inorganic particle dispersion 1 and Sumikaflex 752 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to obtain coating liquid L. Ta.

(Coating liquid M)
Inorganic particle dispersion 1 and Pateracol IJ-70 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to form coating liquid M. Obtained.

(Coating liquid N)
Inorganic particle dispersion 1 and PVA235 were mixed at a ratio of 60 parts of inorganic particles to 35 parts of resin (in terms of solid content), and then stirred for 30 minutes using a mixer to obtain coating liquid N.

Details of coating solutions A to N are shown in Table 2.

<Manufacture of recording media>
(Example 1)
Coating liquid A was applied to the surface of base material 1 to form a coating layer using a Mayer bar so that the coating amount after drying was 25 g/m ² . The formed coating layer was dried at 100° C. to form an ink receiving layer, and recording medium 1 was obtained.

(Examples 2 to 13, Comparative Examples 1 to 6)
Recording media 2 to 19 were obtained in the same manner as in Example 1 above, except that the combinations of base materials and coating liquids shown in Table 3 were used.

<Evaluation>
In the evaluation criteria for each item shown below, "4", "3", and "2" were defined as preferable levels, and "1" was defined as unacceptable level. The evaluation results are shown in Table 4.

(Break resistance)
The recording medium was set in a shopper folding tester, and the folding test was repeated 200 times. After the test, the ink-receiving layer of the recording medium was observed under an optical microscope under 5 times magnification, and the recording medium was evaluated for folding resistance according to the evaluation criteria shown below.
4: There was no chipping of the ink-receiving layer and no cracks.
3: There was no loss of the ink-receiving layer, but there were some cracks.
2: There was no loss of the ink-receiving layer, but there were cracks.
1: The ink-receiving layer was missing and the base material was exposed in some places.

(Outdoor weather resistance)
An inkjet recording device (trade name: "imagePROGRAF iPF6400", manufactured by Canon) was prepared. Using the prepared inkjet recording device, patches with RGB values (255, 255, 160) were recorded on a recording medium in the standard printing mode (synthetic paper (no glue)), and then dried for 24 hours. The optical density of the recorded patch was measured using an optical reflection densitometer (trade name "500 Spectrodensitometer", manufactured by X-Rite). Further, the optical density was measured again after the recording medium on which the patches were recorded was exposed for 200 hours using a xenon weather meter (trade name "Ci4000", manufactured by Atlas Co., Ltd.). Note that the xenon weather meter was operated under conditions of irradiation with light having a wavelength of 340 nm at an irradiation intensity of 0.39 W/m ² , a tank internal temperature of 50° C., a relative humidity of 70%, and a rack temperature of 63° C. Then, the optical density residual rate was calculated from the following formula (1), and the weather resistance of the ink receiving layer was evaluated according to the evaluation criteria shown below.
Optical density residual rate = {(optical density after exposure)/(optical density before exposure)}×100...(1)
4: The optical density residual rate was 80% or more.
3: The optical density residual rate was 70% or more and less than 80%.
2: The optical density residual rate was 60% or more and less than 70%.
1: The optical density residual rate was less than 60%.

Note that the disclosure of this embodiment includes the following configurations.
(Structure 1) A recording medium for inkjet recording, comprising a base material formed of multifilament yarn, and an ink receiving layer provided on at least one surface of the base material,
The ink receiving layer contains an inorganic pigment and a water-insoluble resin,
The standard deviation of the thickness of the multifilament yarn is 20 μm or more and 40 μm or less,
A recording medium characterized in that the water-insoluble resin has a glass transition point of -40°C or more and 10°C or less.
(Structure 2) The value of the ratio (M2/M1) of the tensile elongation (M2 (%)) of the water-insoluble resin to the tensile elongation (M1 (%)) of the base material is 2.6 or more.7. 5 or less, the recording medium according to configuration 1.
(Structure 3) The recording medium according to Structure 1 or 2, wherein the water-insoluble resin has a glass transition point of -25°C or more and 10°C or less.
(Structure 4) The inkjet recording medium according to any one of Structures 1 to 3, wherein the water-insoluble resin has a tensile elongation (M2 (%)) of 500% or more and 1,500% or less.

(Structure 5) The recording medium according to any one of claims 1 to 4, wherein the inorganic pigment is wet silica.

Claims (5)

A recording medium for inkjet recording, comprising a base material formed of multifilament yarn, and an ink receiving layer provided on at least one surface of the base material,
The ink receiving layer contains an inorganic pigment and a water-insoluble resin,
The standard deviation of the thickness of the multifilament yarn is 20 μm or more and 40 μm or less,
A recording medium characterized in that the water-insoluble resin has a glass transition point of -40°C or more and 10°C or less. The ratio (M2/M1) of the tensile elongation (M2 (%)) of the water-insoluble resin to the tensile elongation (M1 (%)) of the base material is 2.6 or more and 7.5 or less. The recording medium according to claim 1. The recording medium according to claim 1 or 2, wherein the water-insoluble resin has a glass transition point of -25°C or more and 10°C or less. The recording medium according to claim 1 or 2, wherein the water-insoluble resin has a tensile elongation (M2 (%)) of 500% or more and 1,500% or less. The recording medium according to claim 1 or 2, wherein the inorganic pigment is wet silica.