Recording paper

Abstract

Provided is recording paper that has both high smoothness and excellent glossiness, that has a high image density and excellent ink absorbability and drying properties, and that does not require waterproofing and antifouling treatments even in a case where printed matter is exposed outdoors for a long period of time.　The present invention provides recording paper in which a receiving layer containing a styrene-based resin is provided on one of the surfaces of a base material layer composed of a thermoplastic resin film.

Description

[Technical field]

[0001] The present invention relates to a recording paper. [Background technology]

[0002] Inkjet printing can print full-color images created on a computer without creating a plate. Because there is no need to create a plate and images created on a computer can be easily modified, the use of inkjet printing is spreading in various fields. The ink used in inkjet printing is generally water-based ink, as is used in home inkjet printers, but solvent-based ink is also preferred due to its good water resistance and ink fixation properties. Solvent-based ink is now being used even in indoor exhibitions where water-based ink was previously used.

[0003] Recording paper is required to have high absorbency so that the solvent in the solvent-based ink can be dried quickly after recording. In order to achieve such solvent absorbency, various studies have been conducted (for example, see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-234677 A [Patent Document 2] JP 2001-270238 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the receiving layer containing a vinyl chloride copolymer as in Patent Document 1 has problems such as waviness due to solvents, blocking, and poor weather resistance. If these problems are improved by using additives, printability may be adversely affected. In addition, the pigment coat as in Patent Document 2 has problems such as water and dirt easily adhering, low receiving layer strength, low gloss, and low image clarity.

[0006] In view of the problems with the prior art described above, the present invention aims to provide a recording paper which combines high smoothness and excellent glossiness, has high image density, is excellent in absorbency and drying properties for solvent-based inks, and does not require water-resistant or stain-resistant treatment even when printed matter is exposed outdoors for long periods of time. [Means for solving the problem]

[0007] In order to solve these problems, the inventors conducted intensive research and discovered that a recording paper having the desired characteristics can be provided by having a receiving layer containing a styrene-based resin on either side of a base layer made of a thermoplastic resin film, thereby completing the present invention. That is, the present invention is as follows.

[0008] (1) A recording paper having a receiving layer containing a styrene-based resin provided on either side of a base layer made of a thermoplastic resin film. (2) The recording paper according to (1), wherein the receiving layer is stretched in at least one direction. (3) The recording paper according to (1) or (2), wherein the receiving layer has a thickness of 3 μm or more. (4) The recording paper according to any one of (1) to (3), characterized in that the styrene-based resin contains at least one selected from the group consisting of a copolymer of a styrene-based monomer, ethylene, and butadiene; a copolymer of a styrene-based monomer, an α-olefin, and butadiene; and a copolymer of a styrene-based monomer, ethylene, an α-olefin, and butadiene. (5) The recording paper according to any one of (1) to (4), characterized in that the arithmetic average roughness (Ra) of the surface on the base layer side (back layer side) of the recording paper according to JIS B0601:2003 is 0.2 μm or more. (6) The recording paper according to any one of (1) to (5), wherein the static friction coefficient of the receiving layer side surface of the recording paper according to JIS K7125:1999 is 0.10 to 0.70. (7) The surface resistivity of the surface of the base layer side (back layer side) of the recording paper measured in accordance with JIS K6911:2006 is 1×10 8 ~9×10 12 The recording paper according to any one of (1) to (6), characterized in that the hardness is Ω. (8) The recording paper according to any one of (1) to (7), wherein the recording paper has a bending resistance of 0.3 to 10 mN according to JIS L1096:2010 bending rebound A method (Gurley method). Effect of the Invention

[0009] According to the present invention, it is possible to provide a recording paper which has both high smoothness and excellent gloss, high image density, excellent ink absorbency and drying properties, and does not require water resistance or stain resistance treatment even when the printed matter is exposed outdoors for a long period of time. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a recording sheet. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a recording sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The recording paper of the present invention will be described in detail below. The following is an example (representative example) of the present invention, and the present invention is not limited thereto.

[0012] In the following description, the term "(meth)acrylic" refers to both acrylic and methacrylic.

[0013] [Recording paper] Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the recording paper of this embodiment. The recording paper 100 shown in Fig. 1 has at least a receiving layer 10 containing a styrene-based resin on either side of a base layer 20 made of a thermoplastic resin film. As shown in Fig. 2, the base layer 20 may have a two-layer structure of a core layer 21 and a back layer 22. That is, the recording paper 100 of this embodiment may have the receiving layer 10, the core layer 21, and the back layer 22 in this order. The inkjet printing layer is provided on the surface on the receiving layer 10 side in Figs. 1 and 2.

[0014] (Receptive layer) The receiving layer is provided on the base layer and is located on the outermost surface of the recording paper of the present embodiment. The receiving layer receives the solvent-based ink.

[0015] <Styrene-based resin> The receiving layer contains a styrene-based resin, which can improve the absorbency and drying property of the solvent-based ink.

[0016] A styrene-based resin is a polymer that mainly contains structural units derived from styrene, and is a homopolymer of a styrene-based monomer or a copolymer with other monomer components. From the viewpoint of suppressing bleeding during solvent inkjet printing, the receiving layer may be composed of only a homopolymer of a styrene monomer and a copolymer of a styrene monomer and another monomer as the styrene resin, whereas from the viewpoint of interlayer strength with the base layer, the receiving layer preferably contains a homopolymer of a styrene monomer and a copolymer of a styrene monomer and another monomer as the styrene resin. The styrene-based resin used in the receiving layer may be one type or a combination of two or more types. Examples of styrene monomers include styrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, vinyltoluene, vinylxylene, and vinylnaphthalene.

[0017] As the other monomer in the copolymer, an olefin is preferably used. Examples of the olefin include α-olefins, diene monomers, and other monomers such as ethylene, propylene, and cyclohexene. Specific examples of the α-olefins include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene. Examples of the diene monomers include butadiene, isoprene, and chloroprene. The copolymer may be a binary or ternary or higher multi-component copolymer, and may be a random copolymer or a block copolymer. Other monomer components that may be used in the copolymer include, for example, (meth)acrylic acid, (meth)acrylic acid esters, maleic anhydride, vinyl acetate, and acrylonitrile.

[0018] Examples of styrene-based resins include styrene homopolymers, styrene-ethylene copolymers, styrene-propylene copolymers, styrene-butadiene copolymers, styrene-butadiene-styrene copolymers, styrene-isoprene copolymers, styrene-isoprene-styrene copolymers, styrene-ethylene-butylene copolymers, styrene-ethylene-propylene copolymers, styrene-ethylene-butadiene copolymers, styrene-butadiene-butylene copolymers, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene-acrylic acid ester copolymers, methacrylic acid ester-butadiene-styrene copolymers, styrene-ethylene-butylene-butadiene copolymers, and styrene-ethylene-butadiene-styrene copolymers. The copolymers may be random copolymers or block copolymers. The styrene-based resins may be hydrogenated.

[0019] In particular, the styrene-based resin preferably contains a copolymer of a styrene-based monomer and butadiene, and more preferably contains at least one selected from the group consisting of a copolymer of a styrene-based monomer, ethylene, and butadiene; a copolymer of a styrene-based monomer, an α-olefin, and butadiene; and a copolymer of a styrene-based monomer, ethylene, an α-olefin, and butadiene.

[0020] Examples of the styrene-based resin include styrene-ethylene-butadiene copolymer, styrene-1-butene-butadiene copolymer, styrene-1-pentene-butadiene copolymer, styrene-1-hexene-butadiene copolymer, styrene-4-methyl-1-pentene-butadiene copolymer, styrene-1-heptene-butadiene copolymer, styrene-1-octene-butadiene copolymer, styrene-1-nonene-butadiene copolymer, styrene-1-decene-butadiene copolymer, styrene-ethylene-1-butene-butadiene copolymer, styrene-ethylene-1-pentene-butadiene copolymer, styrene-ethylene-1-hexene-butadiene copolymer, styrene-ethylene-4-methyl-1-pentene-butadiene copolymer, styrene-ethylene-1-heptene-butadiene copolymer, styrene-ethylene-1-octene-butadiene copolymer, styrene-ethylene-1-nonene-butadiene copolymer, and styrene-ethylene-1-decene-butadiene copolymer.

[0021] The content of the styrene-based resin in the receiving layer is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of improving the absorbency and drying property of the solvent-based ink and suppressing waviness after printing. On the other hand, the content of the styrene-based resin is preferably 100% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, from the viewpoint of interlayer strength between the core layer and the receiving layer. In addition, when the styrene-based resin contains a homopolymer of a styrene-based monomer and a copolymer of a styrene-based monomer and another monomer, the content of the copolymer is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total amount of the styrene-based resin, from the viewpoint of interlayer strength with the base layer. In addition, the content of the copolymer is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on the total amount of the styrene-based resin, from the viewpoint of smoothness.

[0022] The receiving layer may be a resin film using only a styrene-based resin, or may contain a thermoplastic resin other than a styrene-based resin within a range that does not impair the effects of the present invention. The thermoplastic resin other than a styrene-based resin may be a resin compatible with the styrene-based resin from the viewpoint of image clarity, or may be a resin incompatible with the styrene-based resin from the viewpoint of drying. Here, the term "resin compatible with a styrene-based resin" refers to a resin that forms a single phase when mixed with a styrene-based resin in a 1:1 mass ratio and heated at 230°C. When the thermoplastic resin in the receiving layer is composed of only a styrene-based resin, or when the thermoplastic resin contains a styrene-based resin and a resin compatible with the styrene-based resin, bleeding during solvent inkjet printing tends to be suppressed. In addition, when the thermoplastic resin in the receiving layer contains a styrene-based resin and a resin incompatible with the styrene-based resin, the solvent tends to penetrate through the gaps generated between the resins, and the drying property of the solvent-based ink tends to be improved. Examples of the thermoplastic resin that can be used in combination include polyolefin resins such as polyethylene resins, polypropylene resins, and ethylene-cyclic olefin copolymers; polyamide resins such as nylon-6, nylon-6,6, nylon-6,10, and nylon-6,12; thermoplastic polyester resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, and aliphatic polyester; and polycarbonate resins such as aromatic polycarbonates and aliphatic polycarbonates. Among these, polyolefin resins are preferred as the thermoplastic resin that can be used in combination from the viewpoint of suppressing a decrease in interlaminar strength with the adjacent base layer when the adjacent base layer contains a polyolefin resin.

[0023] <Filler> The receiving layer may contain a filler. Examples of fillers that can be used include inorganic fillers and organic fillers. When the base layer contains a resin with high solvent resistance, such as a polyolefin resin, the base layer may follow the shrinkage of the receiving layer due to dissolution of the styrene resin during printing, causing curling on the printed surface side. However, by containing a filler in the receiving layer, shrinkage of the receiving layer can be suppressed even if the styrene resin dissolves, and curling can be reduced. In addition, when the receiving layer contains a filler, gaps are likely to be generated between the receiving layer and the surrounding thermoplastic resin, such as the styrene resin, and the drying property of the solvent-based ink tends to be improved. When the receiving layer is a stretched layer stretched in at least one direction, pores are formed inside the receiving layer due to the inclusion of a filler, and the receiving layer is likely to become a stretched porous layer. When the receiving layer is a stretched porous layer, the absorption and drying property of the solvent-based ink are further improved.

[0024] <<Inorganic filler>> Examples of inorganic fillers that can be used include inorganic particles such as calcium carbonate, calcined clay, silica, diatomaceous earth, white clay, talc, titanium oxide, barium sulfate, barium titanate, alumina, zeolite, mica, sericite, bentonite, sepiolite, vermiculite, dolomite, wollastonite, and glass fiber. The average particle size of the inorganic filler measured with a particle size distribution meter using laser diffraction is usually 0.01 to 15 μm, and preferably 0.1 to 5 μm.

[0025] <<Organic filler>> As the organic filler, for example, organic particles such as polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, melamine resin, polyethylene sulfite, polyimide, polyethyl ether ketone, or polyphenylene sulfite can be used.

[0026] As the filler, the above-mentioned inorganic fillers and organic fillers can be used alone or in combination. The content of the filler in the receiving layer (when an inorganic filler and an organic filler are used in combination, the total amount of the fillers) can be, for example, 65% by mass or less, or 55% by mass or less. From the viewpoint of obtaining gloss or smoothness, the content of the filler in the receiving layer is preferably 20% by mass or less, and more preferably 10% by mass or less. From the viewpoint of obtaining absorbency and drying property of a solvent-based ink as a porous layer, the content of the filler in the receiving layer is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more.

[0027] <Other ingredients> The receiving layer may further contain, as necessary, a curing agent, an ink setting agent, an ultraviolet absorbing agent, a surfactant, etc. These may be contained within a range that does not impair the effects of the present invention.

[0028] The receiving layer may be a non-stretched film or a stretched film. From the viewpoint of easily controlling the amount of solvent absorbed and the solvent absorption rate, the receiving layer is preferably a stretched film stretched in at least one direction.

[0029] The surface of the receiving layer may be subjected to an oxidation treatment. The oxidation treatment tends to adjust the wettability of the surface and suppress bleeding of the print. In addition, the oxidation treatment tends to adjust the polarity ratio of the surface, easily obtain a chemical bonding force with the solvent-based ink, and improve the adhesion between the recording paper and the inkjet printing layer. Examples of the oxidation treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment, etc., and these treatments can be combined. Among these, the oxidation treatment is preferably corona discharge treatment or flame treatment, and more preferably corona discharge treatment.

[0030] <Characteristics of the receiving layer> <<Solvent absorption amount>> The solvent absorption of the receiving layer is 5 ml / m 2 More than 10ml / m is preferable. 2 More preferably, 15 ml / m or more 2 On the other hand, the solvent absorption of the receiving layer is preferably 100 ml / m 2 Less than 90ml / m is preferable. 2 Less than 80ml / m is more preferable. 2 If the solvent absorption amount of the receiving layer is within the above range, the drying property of the solvent-based ink is excellent, and therefore, there is a tendency that transfer of the solvent-based ink can be reduced when the recording paper after solvent inkjet printing is stored stacked on other papers. The specific method for measuring the amount of solvent absorbed in the receiving layer will be described in the Examples section.

[0031] <<Solvent absorption rate>> The solvent absorption rate of the receiving layer is 10 ml / m 2 s or more is preferable, 20ml / m 2 s or more is more preferable, 30ml / m 2On the other hand, the solvent absorption rate of the receiving layer is preferably 100 ml / m or more. 2 ·s or less is preferable, 90ml / m 2 ·s or less is more preferable, 80ml / m 2 If the solvent absorption rate of the receiving layer is within the above range, the solvent-based ink will quickly penetrate into the receiving layer, and therefore the solvent-based inks will not mix even when multiple colors of solvent-based inks are overlaid, and bleeding during multi-color printing tends to be reduced. The specific method for measuring the solvent absorption rate of the receiving layer will be described in the Examples section.

[0032] <<Layer strength>> The layer strength of the receiving layer is preferably 0.9 kgf / cm or more, more preferably 1.0 kgf / cm or more, and even more preferably 1.1 kgf / cm or more. On the other hand, the layer strength of the receiving layer is preferably 2.0 kgf / cm or less, more preferably 1.9 kgf / cm or less, and even more preferably 1.8 kgf / cm or less. If the layer strength of the receiving layer is within the above range, when the recording paper is displayed outdoors, the receiving layer is less likely to be scraped off by sand or the like, and the weather resistance is high, so that the printed pattern tends to be maintained for a long period of time. A specific method for measuring the layer strength of the receiving layer will be described in the Examples section.

[0033] <<Porosity>> When the receiving layer has pores inside, the porosity is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. On the other hand, the porosity is preferably 70% or less. When the porosity is 5% or more, the amount of solvent absorbed increases, and the ink drying property tends to improve. Also, when the porosity is 70% or less, the smoothness and glossiness tend to improve.

[0034] <<Thickness>> From the viewpoint of sufficient absorption of the solvent, the thickness of the receiving layer is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 5 μm or more, while from the viewpoint of curl balance, the thickness of the receiving layer is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less.

[0035] (base material layer) The substrate layer is a resin film containing a thermoplastic resin, and is provided as a support for the recording paper. The substrate layer may have a single-layer structure, or a multi-layer structure of two or more layers. Since a receiving layer is laminated on at least one surface of the substrate layer, the substrate layer may be corona discharge-treated to improve adhesion with the receiving layer.

[0036] As the thermoplastic resin, the thermoplastic resins exemplified for the receiving layer can be used. Among them, from the viewpoint of mechanical strength, polyolefin-based resins are preferable as the thermoplastic resin.

[0037] <Polyolefin resin> Specific examples of polyolefin resins include polypropylene resins, polyethylene resins, and polymethyl-1-pentene.

[0038] The polypropylene resin is not particularly limited as long as propylene is used as the main monomer. Examples of the polypropylene resin include isotactic polymers and syndiotactic polymers obtained by homopolymerizing propylene. In addition, the polypropylene resin may be a propylene-α-olefin copolymer, which is a copolymer of propylene as the main component and α-olefins such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene. The copolymer may be a binary or ternary or more multiple monomer system, and may be a random or block copolymer. In addition, a propylene homopolymer and a propylene copolymer may be used in combination.

[0039] The polyethylene resin has a density of, for example, 0.940 to 0.965 g / cm 3 High density polyethylene, density is 0.920~0.935g / cm 3 of medium density polyethylene, with a density of 0.900 g / cm 3 More than 0.920g / cm 3 Examples of such copolymers include linear low-density polyethylene having a molecular weight of less than 1000, copolymers mainly composed of ethylene and copolymerized with α-olefins such as propylene, butene, hexene, heptene, octene, and 4-methylpentene-1, maleic acid modified ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, ethylene-methacrylic acid alkyl ester copolymer, metal salts of ethylene-methacrylic acid copolymer (metals are zinc, aluminum, lithium, sodium, potassium, etc.), ethylene-cyclic olefin copolymer, and maleic acid modified polyethylene.

[0040] As the polyolefin resin, a graft-modified product thereof may also be used as necessary from the viewpoint of improving the adhesiveness or moldability of the resin film. A known method can be used for the graft modification. Specifically, a graft modification using an unsaturated carboxylic acid or a derivative thereof as a graft monomer can be mentioned. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid. Examples of the derivatives of the unsaturated carboxylic acid include anhydrides, esters, amides, imides, and metal salts of the unsaturated carboxylic acids.

[0041] Specific examples of the graft monomer include maleic anhydride, itaconic anhydride, citraconic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, glycidyl (meth)acrylate, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, (meth)acrylamide, maleic acid monoamide, maleic acid diamide, maleic acid monomethyl ester, maleic acid diethyl ester ... Examples of such maleic acid-N-monoethylamide, maleic acid-N,N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N,N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric acid-N,N-diethylamide, fumaric acid-N-monobutylamide, fumaric acid-N,N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium (meth)acrylate, and potassium (meth)acrylate.

[0042] The graft monomer can be used in an amount of usually 0.005 to 10% by mass, preferably 0.01 to 5% by mass, based on the polyolefin resin.

[0043] The polyolefin resin used for the base layer may be one of the above alone or two or more of them in combination. From the viewpoint of moldability, mechanical strength, cost, etc., the base layer is preferably a resin film of a polypropylene resin or a polyethylene resin, and more preferably a resin film of a polypropylene resin. Among them, propylene homopolymer is easy to handle as the main raw material of the base layer and is preferable.

[0044] From the viewpoint of film formability, the polypropylene-based resin film can be used in combination with a resin having a melting point equal to or lower than that of the propylene homopolymer. Such a resin can be a polyethylene-based resin, specifically a high-density or low-density polyethylene. The content of the polyethylene-based resin can be, for example, 2 to 25% by mass.

[0045] The base layer may be a resin film using only a polyolefin-based resin as a thermoplastic resin, or may contain a thermoplastic resin other than a polyolefin-based resin as long as the effects of the present invention are not impaired.

[0046] <Filler> The substrate layer may contain a filler. When the substrate layer contains a filler, when the substrate layer is a stretched film, pores originating from the filler are formed by stretching to form a porous layer. When the substrate layer is a porous layer, the substrate layer and the recording paper can be made lighter. Furthermore, when the substrate layer is a porous layer, a white film having the texture of paper can be easily obtained. Therefore, the whiteness or opacity of the film can be easily adjusted depending on whether or not the substrate layer contains a filler.

[0047] The filler that can be used in the base layer can be the same as that exemplified in the receiving layer. As the filler, an inorganic filler and an organic filler can be used alone or in combination. The content of the filler in the base layer (when an inorganic filler and an organic filler are used in combination, the total amount of the fillers) is preferably 0 to 60% by mass, and more preferably 0 to 50% by mass.

[0048] <Other ingredients> The substrate layer may further contain a heat stabilizer (antioxidant), a light stabilizer, a dispersant, a lubricant, a nucleating agent, or the like, as necessary. As the heat stabilizer, for example, a sterically hindered phenol-based antioxidant, a phosphorus-based antioxidant, or an amine-based antioxidant can be used usually within the range of 0.001 to 1% by mass. As the light stabilizer, for example, a sterically hindered amine light stabilizer, a benzotriazole light stabilizer, or a benzophenone light stabilizer can be used usually within the range of 0.001 to 1% by mass. Examples of dispersants or lubricants include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, and salts thereof, etc. These can be used in an amount of usually 0.01 to 4% by mass for the purpose of dispersing the filler, for example.

[0049] The base layer may be a non-stretched film or a stretched film. From the viewpoint of increasing the strength of the recording paper, the base layer is preferably a stretched film that is stretched in at least one direction. When the base layer has a multi-layer structure, it preferably contains a stretched film stretched in at least one direction, and more preferably contains a porous stretched film having internal pores. A base layer containing a stretched film has high mechanical strength and excellent thickness uniformity, and therefore a recording paper with excellent post-processability can be obtained. When the base material layer has a multilayer structure, the number of stretching axes of each layer may be uniaxial / uniaxial, uniaxial / biaxial, biaxial / uniaxial, uniaxial / uniaxial / biaxial, uniaxial / biaxial / uniaxial, biaxial / uniaxial / uniaxial, uniaxial / biaxial / biaxial, biaxial / biaxial / uniaxial, or biaxial / biaxial / biaxial.

[0050] <Characteristics of the base layer> <<Porosity>> The base layer preferably has a large number of pores inside the film. That is, the base layer is preferably a porous layer. The porosity calculated by the following formula (1) is preferably 5 to 60%, more preferably 10 to 45%. The presence of pores improves the light diffusion rate, making it possible to obtain a base layer with high opacity. Furthermore, the presence of pores tends to suppress dimensional changes caused by swelling in the solvent in the solvent-based ink, and suppress waviness of the recording paper after solvent inkjet printing.

[0051]

number

[0052] <<Thickness>> The thickness of the substrate layer is preferably 40 to 200 μm, more preferably 50 to 150 μm. If the thickness of the substrate layer is within the above range, the Gurley bending resistance is high and the curl balance is excellent.

[0053] <Core layer and back layer> The substrate layer may be a single layer structure as described above, or may be a multi-layer structure of two or more layers. A multi-layer structure is preferable because each layer can have different characteristics and exhibit various functions. In particular, the substrate layer 20 preferably has a core layer 21 and a back layer 22 as shown in FIG. 2.

[0054] <Core layer> The core layer is a resin film containing a thermoplastic resin, and is provided as a support for the recording paper. The composition of the core layer is the same as that of the base layer.

[0055] The thickness of the core layer can be appropriately determined depending on the thickness of the back layer described below. From the viewpoint of obtaining sufficient stiffness, the thickness of the core layer is preferably 40 to 200 μm, and more preferably 50 to 150 μm.

[0056] The porosity of the core layer is preferably 5 to 60%, and more preferably 10 to 45%. The presence of pores improves light diffusion coefficient, making it possible to obtain a core layer with high opacity.

[0057] <Back layer> The back layer is provided on the surface of the core layer opposite to the receiving layer. The back layer mainly functions to promote the evaporation of the solvent from the receiving layer after printing when the recording paper is stacked and stored, and to suppress waviness of the paper surface caused by the solvent. In addition, unlike the receiving layer which has smoothness, the surface of the back layer has a suitable surface roughness. By having the back layer surface have a suitable surface roughness, it is possible to prevent the occurrence of blocking when the recording paper is stacked and stored.

[0058] In addition, the back layer imparts antistatic properties to the recording paper, thereby making it difficult for problems to occur during the printing process and improving the handling properties. Because the back layer has antistatic properties, even if the recording paper has an internal charge, the surface of the back layer has a low electrostatic adsorption force, making it less likely to cause problems such as sticking to rolls or blocking between sheets during the printing process.

[0059] <Composition of back layer> The back surface layer can be made of the same material as the base material layer, but the content of the filler in the back surface layer (when an inorganic filler and an organic filler are used in combination, the total amount of the fillers) is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, from the viewpoints of surface roughness and static friction coefficient.

[0060] The thickness of the back layer can be appropriately determined depending on the thickness of the core layer described above. From the viewpoint of realizing an appropriate surface roughness, the thickness of the back layer is preferably 1 to 50 μm, more preferably 1 to 20 μm, and further preferably 2 to 10 μm.

[0061] The porosity of the back surface layer is preferably 5 to 60%, more preferably 5 to 50%, and still more preferably 10 to 40%. The presence of pores tends to make it possible to control the surface roughness of the back surface layer within a predetermined range.

[0062] A coating layer can be further provided on the surface of the back layer. The coating layer can contain an anchoring agent and a polymer-type antistatic agent. When an inkjet printing layer is provided on the coating layer, the coating layer containing the anchoring agent tends to improve the adhesion between the coating layer and the inkjet printing layer. In addition, the coating layer containing the antistatic agent tends to improve the antistatic performance on the back layer side. Examples of the anchoring agent include polyimine polymers and ethyleneimine adducts of polyamine polyamides. Examples of the polymer-type antistatic agent include those having an ammonium salt structure or a phosphonium salt structure. When the anchoring agent and the antistatic agent are used in combination, from the viewpoint of fully exhibiting the performance of each component, the solid content ratio of the antistatic agent is preferably 0 to 200 parts by mass, more preferably 20 to 150 parts by mass, and even more preferably 30 to 100 parts by mass, per 100 parts by mass of the anchoring agent.

[0063] [Characteristics of recording paper] (bending resistance) The recording paper is also suitable for use as a notice such as a poster, and in the case of use as a notice, it is preferable that the recording paper has a certain degree of rigidity from the viewpoint of ease of handling when pasting. The bending resistance of the recording paper is preferably 0.3 mN or more, more preferably 0.4 mN or more, and even more preferably 0.5 mN or more. On the other hand, the bending resistance of the recording paper is preferably 10 mN or less, more preferably 5 mN or less, and even more preferably 3 mN or less. If the bending resistance of the recording paper is within the above range, the recording paper itself has stiffness and is easy to handle. In addition, there is a tendency that the recording paper is less likely to wrinkle when pasted on a target object. Furthermore, there is a tendency that waviness after printing can be suppressed. The bending resistance in this embodiment is based on the bending resilience A method (Gurley method) according to JIS L1096:2010. The specific method for measuring the bending resistance of the recording paper by the Gurley method will be described in the Examples section.

[0064] (Glossiness) The gloss of the receiving layer side surface of the recording paper is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. If the gloss of the receiving layer surface is equal to or more than the lower limit, it can be said that the gloss is sufficiently high compared to recording paper using a pigment coating or the like, and the image tends to be clear and look good. The gloss level in this embodiment is based on the gloss level according to JIS P 8142:1993. The specific method for measuring the glossiness of the receiving layer side surface of the recording paper will be described in the Examples section.

[0065] (Static friction coefficient) The static friction coefficient of the receiving layer side surface of the recording paper is preferably 0.10 or more, more preferably 0.20 or more, and even more preferably 0.30 or more. On the other hand, the static friction coefficient of the receiving layer side surface of the recording paper is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less. If the static friction coefficient of the receiving layer side surface of the recording paper is within the above range, the conveying accuracy of the recording paper in the printing machine is good. The friction coefficient is also affected by the arithmetic mean roughness of the receiving layer side surface, and the static friction coefficient tends to decrease as the arithmetic mean roughness increases. The static friction coefficient in this embodiment is based on JIS K7125:1999. The specific method for measuring the static friction coefficient of the receiving layer side surface of the recording paper will be described in the Examples section.

[0066] (Arithmetic mean roughness (Ra)) The arithmetic mean roughness (Ra) of the recording paper on the substrate layer side surface (on the substrate layer side when a core layer and a substrate layer are provided) is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. On the other hand, the arithmetic mean roughness of the recording paper on the substrate layer side surface is preferably 1.0 μm or less, more preferably 0.9 μm or less, and even more preferably 0.8 μm or less. If the arithmetic mean roughness (Ra) of the recording paper on the substrate layer side surface is within the above range, there is a tendency that blocking can be suppressed when the recording paper is stored in a stacked state. The arithmetic mean roughness (Ra) in this embodiment is based on JIS B0601:2003. The specific method for measuring the arithmetic mean roughness (Ra) of the surface on the base layer side of the recording paper will be described in the Examples section.

[0067] (Surface resistivity) The surface resistivity of the base layer side surface of the recording paper (the back layer side if a core layer and a back layer are provided as base layers) is 1 x 10 -1 Ω or more is preferable, 1×10 1 Ω or more is preferable, and 1×10 8 On the other hand, the surface resistivity of the surface of the base layer side of the recording paper is preferably 9×10 12 Ω or less is preferable, 5×10 12 Ω or less is preferable, and 1×10 12 If the surface resistivity of the substrate layer side surface of the recording paper is within the above range, it tends to be possible to suppress the occurrence of sticking to rolls and blocking between sheets of recording paper during the printing process. The surface resistivity in this embodiment is based on JIS K6911:2006. The specific method for measuring the surface resistivity of the substrate layer side surface of the recording paper will be described in the Examples section.

[0068] (Thickness) The recording paper of this embodiment includes at least a receiving layer and a base layer, and the overall thickness of the recording paper is preferably 40 to 200 μm. In this embodiment, in order to further add a paper-like feel, other layers, such as a layer of a propylene-based resin containing 8 to 55 mass% of an inorganic filler, may be further formed between the receiving layer and the base layer. Furthermore, the other layers may contain a small amount of a low-melting-point resin such as a propylene-based copolymer, high-density polyethylene, polystyrene, or an ethylene-vinyl acetate copolymer to improve stretchability.

[0069] [Manufacturing method of recording paper] The recording paper of the present embodiment can be manufactured by laminating a receiving layer and a base layer (a core layer and a back layer) in this order, and the manufacturing method is not particularly limited. For example, a recording paper consisting of a receiving layer, a core layer and a back layer can be manufactured by the following method.

[0070] The resin composition for the core layer is melt-kneaded in advance, extruded into a sheet, and stretched in the longitudinal direction by utilizing the difference in peripheral speed between rolls. Next, the resin composition for the receiving layer and the resin composition for the back layer are separately melt-kneaded in advance on the longitudinally stretched film, laminated into a sheet so as to have a desired layer structure, and stretched in the transverse direction at a specific temperature using a tenter. Then, the recording paper can be obtained by heat treatment and cooling.

[0071] (Stretching) Each layer may be stretched individually before lamination, or may be stretched together after lamination, or the unstretched layer and the stretched layer may be laminated together and then stretched again.

[0072] Examples of the stretching method for stretching a film include a longitudinal stretching method using the difference in peripheral speed between rolls, a transverse stretching method using a tenter oven, a sequential biaxial stretching method combining these, a rolling method, a simultaneous biaxial stretching method using a combination of a tenter oven and a pantograph, and a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor, etc. As a stretching method, a simultaneous biaxial stretching (inflation molding) method in which a molten resin is extruded into a tube shape using a circular die connected to a screw-type extruder and then air is blown into the extruded resin can also be used.

[0073] The stretching temperature during stretching is preferably in the range of the glass transition temperature of the thermoplastic resin or higher when the thermoplastic resin used for the film is a non-crystalline resin. When the thermoplastic resin is a crystalline resin, the stretching temperature is preferably in the range of the glass transition temperature of the non-crystalline part of the thermoplastic resin or higher and the melting point of the crystalline part of the thermoplastic resin or lower, specifically, a temperature 2 to 60° C. lower than the melting point of the thermoplastic resin is preferable.

[0074] The stretching speed is not particularly limited, but from the viewpoint of stable stretch forming, it is preferably within the range of 20 to 350 m / min. The stretching ratio can also be appropriately determined in consideration of the properties of the thermoplastic resin used. For example, when a resin film containing a propylene homopolymer or a copolymer thereof is stretched in one direction, the lower limit of the stretching ratio is usually 1.2 times or more, preferably 2 times or more, while the upper limit is usually 12 times or less, preferably 10 times or less. When biaxially stretching, the stretching ratio is an areal stretching ratio, and the lower limit is usually 1.5 times or more, preferably 10 times or more, while the upper limit is usually 60 times or less, preferably 50 times or less.

[0075] (Surface treatment) From the viewpoint of enhancing adhesion to the receiving layer, the substrate layer is preferably subjected to an oxidation treatment to activate the surface. The surface of the receiving layer may also be subjected to an oxidation treatment. The oxidation treatment tends to adjust the wettability of the surface and suppress bleeding of the print. Examples of the oxidation treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment, etc., and these treatments can be combined. Among these, the oxidation treatment is preferably corona discharge treatment or flame treatment, and more preferably corona discharge treatment.

[0076] When performing corona discharge treatment, the discharge amount is preferably 600 J / m 2 (10W min / m 2 ) or more, and more preferably 1,200 J / m 2 (20W min / m 2 ) or more, while preferably 12,000 J / m 2 (200W min / m 2 ) or less, and more preferably 10,800 J / m 2 (180W min / m 2 The discharge amount when carrying out the flame treatment is preferably 8,000 J / m 2 More preferably, 20,000 J / m2 or more, preferably 200,000 J / m 2 or less, more preferably 100,000 J / m 2 The following is the result.

[0077] As a coating method for providing a coating layer on the surface of the back layer, specifically, gravure coating, Mayer bar coating, roll coating, blade coating, size press coating, etc. can be adopted. The coating amount is generally 0.01 to 20 g / m 2 , preferably 0.1 to 15 g / m 2 It can be.

[0078] [Use of recording paper] The recording paper obtained as described above can be suitably used for solvent-based inks that use a solvent and a coloring material specific to solvent-based inks.

[0079] Examples of the solvents used in the solvent-based ink include glycol ether-based solvents such as polyoxyethylene glycol dialkyl ether, polyoxyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether. Examples of the coloring materials used in the solvent-based ink include oil-soluble dyes such as naphthol dyes, azo dyes, metal complex dyes, anthraquinone dyes, quinoimine dyes, indigo dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, carbonium dyes, naphthoquinone dyes, naphthalimide dyes, phthalocyanine dyes, and perinine dyes. Examples of the pigments used include carbon black and various color pigments, and examples of the organic pigments include insoluble azo pigments, condensed azo pigments, chelate azo pigments, perinone pigments, nitro pigments, nitroso pigments, perylene pigments, and aniline black. EXAMPLES

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the examples, the terms "parts", "%", and the like are based on mass unless otherwise specified.

[0081] [Test Method] (Solvent absorption) The amount of solvent absorbed by the receiving layer of the recording paper can be measured using a water absorption tester specified in JIS P 8140. The amount of solvent absorbed by the recording paper was measured by contacting the surface of the receiving layer of the test piece with a solvent (diethylene glycol ethyl methyl ether manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) for 60 seconds, removing excess solvent, and then measuring the mass of the test piece. The measured mass of the test piece was then subtracted from the original mass of the test piece, and the mass of the test piece was then calculated by subtracting the measured mass from the mass of the test piece by 1 m. 2 The mass of solvent absorbed per unit mass is called the solvent absorption (ml / m 2 ) was decided.

[0082] (Solvent absorption rate) The solvent absorption rate of the receiving layer of the recording paper can be measured using a water absorption tester specified in JIS P 8140. The solvent absorption rate of the recording paper was measured by contacting the surface of the receiving layer of a test piece with a solvent (diethylene glycol ethyl methyl ether, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) for 5 seconds, calculating the amount of absorbed solvent, and dividing the calculated amount by the solvent contact time to obtain the solvent absorption rate (ml / m 2 ·s).

[0083] <Layer strength> The layer strength of the receiving layer of the recording paper was measured by attaching cellophane tape (manufactured by Nichiban Co., Ltd., product name: CT-18) to the surface of the receiving layer side, and measuring the ink peel strength using an internal bond tester (manufactured by Kumagai Riki Kogyo Co., Ltd., product name) in accordance with JAPAN TAPPI No. 18-2 (internal bond strength test method), and the average value of two measurement results was taken as the layer strength.

[0084] <Thickness> The thickness (total thickness) of the recording paper was measured using a constant pressure thickness measuring instrument (manufactured by Techclock Co., Ltd., product name: PG-01J) in accordance with JIS K7130:1999. The thickness of each layer in the recording paper was measured by cooling the measurement sample to a temperature of -60°C or lower with liquid nitrogen, placing the sample on a glass plate, cutting it with a razor blade (manufactured by Schick Japan Co., Ltd., product name: Proline Blade) at a right angle to prepare a sample for cross-sectional observation, and observing the cross-section of the obtained sample using a scanning electron microscope (manufactured by JEOL Ltd., product name: JSM-6490), determining the boundary line for each resin composition from the composition appearance, and multiplying the total thickness of the recording paper by the thickness ratio of each layer observed.

[0085] <Gurley stiffness> The Gurley stiffness of the recording paper was measured in the MD direction in accordance with JIS L1096:2010 under an environment of a temperature of 23° C. and a humidity of 50% RH using a Gurley stiffness tester (manufactured by Daiei Scientific Instruments Co., Ltd., product name: GAS-100).

[0086] <Glossiness> The gloss of the receiving layer side surface of the recording paper was measured in accordance with JIS P 8142:1993, and the 75 degree specular gloss was measured.

[0087] <Static friction coefficient> The static friction coefficient of the receiving layer side surface of the recording paper was measured in accordance with JIS K7125:1999 using a friction coefficient tester (manufactured by Toyo Seiki Co., Ltd., product name: TR-2).

[0088] <Arithmetic mean roughness Ra> The arithmetic mean roughness Ra (μm) of the surface on the base layer side of the recording paper (on the back layer side if a core layer and a back layer are provided as the base layer) was measured in accordance with JIS B0601:2003 using a three-dimensional roughness measuring device (manufactured by Kosaka Laboratory Ltd., product name: SE-3AK) and an analyzer (manufactured by Kosaka Laboratory Ltd., product name: SPA-11).

[0089] <Surface resistivity> The surface resistivity of the base layer side surface of the recording paper (the back layer side if a core layer and a back layer are provided as base layers) is 1 x 10 7 For resistances of 1×10 Ω or more, measurements were performed using a double-ring electrode in accordance with JIS K6911:2006. 7 When the resistance is less than Ω, the resistance (R) obtained by measuring with a four-probe method in accordance with JIS K7194:1994 is multiplied by a correction coefficient F to obtain the surface resistivity.

[0090] (Evaluation of printability) The recording paper was stored for one day in an atmosphere of 23°C and 50% relative humidity, and then the receiving layer surface of the recording paper was printed solid with SC10BK70 ink at a resolution of 720 x 1440 dpi using an inkjet printer "SC-S80650" (manufactured by Seiko Epson Corporation) with the drive waveform of the piezo element optimized, and then heat-treated (heat-dried) at 50°C for 30 seconds. The printability was evaluated according to the following criteria.

[0091] <Concentration> After solvent inkjet printing, the print density of nine black areas per sample was measured using a portable spectrodensitometer (manufactured by X-Rite Inc., product name "508") on the printed surface, the average value was calculated, and the density was judged according to the following criteria. 3 (Good): 1.4 or higher, good ink color development 2 (Acceptable): Below 1.4, some decrease in density is observed at 1.2 or more, but this is not a problem (lower limit of practical use) 1 (unacceptable): Less than 1.2 (not practical)

[0092] <Bleeding> After the solvent inkjet printing, the state of the image on the recording paper after printing was visually observed under magnification with a loupe. The bleeding of the recording paper was evaluated based on the observed state of the image according to the following criteria. 3 (Good): The image is clear. 2 (Acceptable): Ink bleeding is unclear to the naked eye, but the dot area is larger when observed with a magnifying glass (lowest practical limit) 1 (Not acceptable): The image is blurred (not suitable for practical use)

[0093] <Drying> After the solvent inkjet printing, one print sample was randomly taken out every hour and the state of drying of the ink in the solid image area was checked by rubbing it with a finger. The drying property was evaluated according to the following criteria. 3 (Good): Dries very quickly (dries within 10 minutes and does not stick to fingers) 2 (OK): Dries quickly and is not a problem (dries in more than 10 to 20 minutes, practical lower limit) 1 (Not good): Drying is a little slow and problematic (it doesn't dry even after 20 minutes, not suitable for practical use)

[0094] <Fixation> <<Rubbing>> After solvent inkjet printing, the image portion was cut into a size of 30 mm x 120 mm one day after printing and set in a Gakushin tester (manufactured by Suga Testing Machines Co., Ltd.). For evaluation under dry conditions, gauze dried at room temperature was attached to a weight of 215 g, the surface of the printed image portion was rubbed with this weight 100 times, and the degree of ink peeling was evaluated by visual observation. For evaluation under wet conditions, gauze soaked with 20 μL of pure water at room temperature was attached to a weight of 215 g, the surface of the printed image portion was rubbed with this weight 100 times, and the degree of ink peeling was evaluated by visual observation. Abrasion was evaluated according to the following criteria. 3 (Good): 95% or more of the rubbed image remains 2 (Acceptable): 80% or more of the rubbed image remains (lower limit of practical use) 1 (Not acceptable): Less than 80% of the rubbed image remains (not suitable for practical use)

[0095] <<Ink adhesion>> After the solvent inkjet printing, the adhesive side of cellophane tape (manufactured by Nichiban Co., Ltd., product name: Cellotape (registered trademark) CT-18) was attached to the printed surface and rubbed with a finger three times to ensure sufficient adhesion. The cellophane tape was peeled off by hand in a 180° direction at a speed of 300 m / min, and the ink remaining rate on the recording paper was calculated using a small general-purpose image analyzer (manufactured by Nireco Co., Ltd., model name: LUZEX-AP). Specifically, the image obtained by photographing the printed surface was subjected to binarization processing, and the proportion of the area occupied by the ink was calculated as the ink remaining rate. The ink adhesion was evaluated based on the calculated ink remaining rate according to the following criteria. 3 (Good): Ink remaining rate is 80% or more. 2 (Acceptable): Ink remaining rate is between 50% and 80% (lower practical limit) 1 (Not acceptable): Less than 50% of the ink remains (not suitable for practical use)

[0096] <Curl> After solvent inkjet printing, the recording paper was cut to a size of 100 mm x 100 mm and stored for one day under conditions of 23°C and 50% relative humidity. The recording paper was placed flat with the printed side facing up, and the curl height of the edge was evaluated according to the following criteria. 3 (Good): Curl height is -5mm to +10mm 2 (OK): Curl height is +11mm to +50mm (lowest practical limit) 1 (Not acceptable): Curl height is +51mm or more or -6mm or less (not suitable for practical use)

[0097] <Wavy> A solid black print was printed on the receiving layer surface of the recording paper using a solvent inkjet printer "RAMIREZ III: PJ-1634NX" (manufactured by Muto Industries Ltd.), and the degree of waviness in the printed area was visually evaluated according to the following criteria. 3 (Good): No waviness, extremely good level 2 (Acceptable): Slight waviness (lower limit of practical use) 1 (Unacceptable): Wavy edges are visible (not suitable for practical use)

[0098] <Blocking> The recording paper was wound into a roll and stored for one day in an atmosphere of 40°C and 50% relative humidity, after which it was observed whether the paper could be smoothly pulled out from the roll without causing blocking. Blocking was evaluated according to the following criteria. 3 (Good): Can be pulled out smoothly without any peeling noise 2 (Acceptable): There is a peeling sound, but the appearance of the base layer after removal is not impaired (lower practical limit) 1 (Unacceptable): There is a loud peeling noise and the appearance of the base layer is damaged after removal (not suitable for practical use)

[0099] <Weather resistance> In applications such as posters, peeling of the ink may be a problem when used outdoors. However, when weather resistance is evaluated by actually performing an exposure test outdoors, the results are likely to fluctuate due to various variable factors such as climate and weather. In this embodiment, the printed matter was subjected to an accelerated weather resistance treatment (exposure test) under uniform conditions in accordance with JIS K-7350-4, and then solvent inkjet printing was performed, and the ink adhesion was evaluated. More specifically, the accelerated treatment was performed under the following conditions. An ultra-accelerated weather resistance tester (manufactured by Daipla Wintes Co., Ltd., product name "Metal Weather KU-R5N-A", metal halide lamp type) and a glass filter "KF-2 Filter" (product name) that transmits ultraviolet light of 295 to 450 nm were used. The recording paper printed in the above procedure was cut to a size of 90 mm x 150 mm to obtain a test specimen, which was then attached to a stainless steel plate (100 mm x 200 mm) on all four sides with aluminum foil tape "AL-T" (manufactured by Takeuchi Kogyo Co., Ltd., product name) so that the printed side was the exposed surface, and this was then placed in the tester. The irradiance of the surface of the test specimen was 90 W / m 2 The black panel temperature was 63°C. Two cycles of accelerated treatment were performed, one cycle consisting of 5 hours of exposure at 63°C and 50% relative humidity and one cycle of 3 hours of exposure at 30°C and 98% relative humidity. Therefore, the radiation exposure to the printed surface was 5.18×106 J / m 2 It was. Next, the test pieces that had been subjected to the accelerated weather resistance treatment were subjected to a friction test and evaluation in the same manner as in the case of abrasion resistance. 3 (Good): 95% or more of the rubbed image remains 2 (Acceptable): 80% or more of the rubbed image remains (lower limit of practical use) 1 (Not acceptable): Less than 80% of the rubbed image remains (not suitable for practical use)

[0100] [Examples and Comparative Examples] (Examples 1 to 13 and Comparative Examples 1 to 3) According to the following procedures, recording papers of Examples 1 to 13 and Comparative Examples 1 to 3 were manufactured. Table 1 shows the compounding ratios (parts by mass) of the resin compositions used in manufacturing the recording papers.

[0101] [Table 1]

[0102] Example 1 Resin composition a listed in Table 1 was melt-kneaded in an extruder set at 230 ° C, then fed to an extrusion die set at 250 ° C, extruded into a sheet, and cooled to 60 ° C by a cooling device to obtain an unstretched sheet. This unstretched sheet was heated to 135 ° C, and stretched 5 times in the longitudinal direction using the difference in peripheral speed of the roll group to obtain a single-layer uniaxially stretched sheet. Next, resin composition c was melt-kneaded in an extruder set at 230 ° C, extruded into a sheet and laminated on the first surface of the single-layer uniaxially stretched sheet, and at the same time, resin composition a was melt-kneaded in one extruder set at 230 ° C, extruded into a sheet and laminated on the second surface of the single-layer uniaxially stretched sheet to obtain a three-layer laminate sheet. Next, this three-layer laminate sheet was cooled to 60 ° C, and the three-layer laminate sheet was heated to about 150 ° C using a tenter oven to stretch 8.5 times in the transverse direction, and then further heated to 160 ° C to perform heat treatment. It was then cooled to 60°C and the edge portions were slit to obtain a laminated resin film having a uniaxially stretched layer of resin composition a as the back layer, a thickness of 140 μm, resin compositions of each layer (c / a / a), thicknesses of each layer (20 μm / 100 μm / 20 μm), and number of stretching axes for each layer (uniaxial / biaxial / uniaxial).

[0103] In a container equipped with a stirrer, 50 parts by mass of a polyethyleneimine solution (manufactured by Nippon Shokubai Co., Ltd., product name: Epomin P-1000) and 50 parts by mass of a polymer solution having an antistatic function, which is a cationic methacrylic acid ester copolymer containing a quaternary ammonium salt structure represented by the following formula in its molecular chain, were added in that order, and then the mixture was diluted with water to a solids concentration of 20% by mass. The mixture was stirred and mixed for 20 minutes to prepare coating solution b.

[0104] [ka]

[0105] The surface of the back layer of the above laminated resin film was subjected to a surface treatment by corona discharge, and coating liquid b was applied to the corona discharge treated surface and dried to provide a coating layer with a thickness of 0.1 μm. After drying in an oven at 70° C. for 60 seconds, the recording paper of Example 1 was obtained.

[0106] (Examples 2 to 6, 10, and 11) Recording papers of Examples 2 to 6, 10, and 11 were obtained in the same manner as in Example 1, except that resin composition d, e, f, g, h, j, or k for the receiving layer shown in Table 2 was used instead of resin composition c.

[0107] Example 7 The recording paper of Example 7 was obtained in the same manner as in Example 1, except that in Example 1, resin composition i for the receiving layer shown in Table 2 was used instead of resin composition c, the thickness was 170 μm, and the thickness of each layer was (50 μm / 100 μm / 20 μm).

[0108] Example 8 A recording paper of Example 8 was obtained in the same manner as in Example 7, except that the thickness was 130 μm and the thicknesses of the individual layers were (10 μm / 100 μm / 20 μm).

[0109] Example 9 A recording paper of Example 9 was obtained in the same manner as in Example 7, except that the thickness was 125 μm and the thicknesses of the individual layers were (5 μm / 100 μm / 20 μm).

[0110] Example 12 Resin composition b shown in Table 1 was melt-kneaded in an extruder set at 230 ° C., then fed to an extrusion die set at 250 ° C. and extruded into a sheet, which was cooled to 60 ° C. by a cooling device to obtain an unstretched sheet. This unstretched sheet was heated to 135 ° C., and stretched 5 times in the longitudinal direction using the difference in peripheral speed of the roll group to obtain a single-layer uniaxially stretched sheet. Next, resin composition a was melt-kneaded in an extruder set at 230 ° C., extruded into a sheet and laminated on the first surface of the single-layer uniaxially stretched sheet to obtain a two-layer laminated sheet. Next, this two-layer laminated sheet was cooled to 60 ° C., and the two-layer laminated sheet was heated to about 150 ° C. using a tenter oven to stretch 8.5 times in the transverse direction, and then further heated to 160 ° C. to perform heat treatment, thereby obtaining a two-layer laminated stretched sheet. Next, resin composition d was melt-kneaded in an extruder set at 230 ° C., extruded into a sheet and laminated on the surface of the layer side of the resin composition b of the two-layer laminated stretched sheet to obtain a three-layer laminated sheet. It was then cooled to 60°C and the edge portions were slit to obtain a laminated resin film having a thickness of 140 μm, a uniaxially stretched layer of resin composition a as the back layer, resin compositions of each layer (d / b / a), thicknesses of each layer (20 μm / 100 μm / 20 μm), and number of stretching axes for each layer (unstretched / biaxial / uniaxial).

[0111] Coating solution b was prepared in the same manner as in Example 1. The surface of the back layer of the laminated resin film was subjected to a surface treatment by corona discharge, and coating solution b was applied to the corona discharge-treated surface and dried to provide a coating layer with a thickness of 0.1 μm. After drying in an oven at 70° C. for 60 seconds, a recording paper of Example 12 was obtained.

[0112] (Example 13) The resin composition a shown in Table 1 was melt-kneaded in an extruder set at 230 ° C, then fed to an extrusion die set at 250 ° C, extruded into a sheet, and cooled to 60 ° C by a cooling device to obtain an unstretched sheet. Next, the resin composition d was melt-kneaded in an extruder set at 230 ° C, then extruded into a sheet and laminated on the first surface of the unstretched sheet, and at the same time, the plastic resin composition a was melt-kneaded in one extruder set at 230 ° C, then extruded into a sheet and laminated on the second surface of the unstretched sheet to obtain a three-layer laminated sheet. Next, the ears were slit to obtain a laminated resin film in which the unstretched layer of the resin composition a was the back layer, the thickness was 120 μm, the resin composition of each layer (d / a / a), the thickness of each layer (20 μm / 80 μm / 20 μm), and the number of stretching axes of each layer (unstretched / unstretched / unstretched).

[0113] Coating solution b was prepared in the same manner as in Example 1. The surface of the back layer of the laminated resin film was subjected to a surface treatment by corona discharge, and coating solution b was applied to the corona discharge-treated surface and dried to provide a coating layer with a thickness of 0.1 μm. After drying in an oven at 70° C. for 60 seconds, a recording paper of Example 13 was obtained.

[0114] Comparative Example 1 Resin composition b shown in Table 1 was melt-kneaded in an extruder set at 230°C, then fed to an extrusion die set at 250°C, extruded into a sheet, and cooled to 60°C by a cooling device to obtain an unstretched sheet. This unstretched sheet was heated to 135°C and stretched 5 times in the machine direction using the difference in peripheral speed between the rolls to obtain a single-layer uniaxially stretched sheet. Next, resin composition b was melt-kneaded in an extruder set at 230°C, extruded into a sheet, and laminated on the first surface of the single-layer uniaxially stretched sheet to obtain a two-layer laminate sheet. On the other hand, 55 parts by weight of water, 20 parts by weight of finely powdered silica ("Mizukasil P-78F" manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size 12.5 μm) and 25 parts by weight of hydrophobic resin (acrylic resin emulsion) ("Acronal YJ-2870D" manufactured by BASF Japan Ltd., solids concentration 50% by weight) were mixed and dispersed to prepare coating solution a. One side of the two-layer laminate sheet obtained above was subjected to a surface treatment by corona discharge, and coating liquid a was applied to the corona discharge treated side and dried to provide a coating layer with a thickness of 40 μm. After drying in an oven at 70° C. for 60 seconds, a recording paper of Comparative Example 1 with a thickness of 140 μm was obtained.

[0115] Comparative Example 2 The resin composition 1 shown in Table 1 was kneaded and rolled for 5 minutes using two 9-inch test rolls (steam-heated type manufactured by Nishimura Koki Co., Ltd.) set at 160°C to produce a vinyl chloride resin sheet having a thickness of 140 μm (calendering). The vinyl chloride resin sheet thus obtained was subjected to a maximum pressure of 70 kg / cm at a temperature of 170°C in a 37 ton hydraulic molding machine (manufactured by Oji Machine Co., Ltd.). 2 The surface was mirror-finished to obtain a recording paper of Comparative Example 2 having a thickness of 140 μm.

[0116] Comparative Example 3 A recording paper of Comparative Example 3 was obtained in the same manner as in Example 1, except that resin composition b was used instead of resin composition c for the receiving layer and resin composition b was used instead of resin composition a for the base layer.

[0117] [Table 2]

[0118] [Table 3]

[0119] The results in Tables 2 and 3 show that the recording papers of Examples 1 to 13, in which a receiving layer containing a styrene-based resin is provided on either side of a base layer made of a thermoplastic resin film, are recording papers that combine high smoothness and excellent gloss, have high image density, and are excellent in ink absorption and drying properties, and do not require water-resistant or stain-resistant treatment even when printed matter is exposed outdoors for long periods of time.

[0120] On the other hand, the recording paper of Comparative Example 1, which is provided with a pigment coating layer and does not have a receiving layer containing a styrene resin, has excellent ink absorption and drying properties and can prevent waviness and blocking, but has low gloss and image density, and is poor in ink fixation, so that it requires water resistance and antifouling treatment when the printed matter is exposed outdoors for a long period of time. The recording paper of Comparative Example 2, which is provided with a receiving layer containing a vinyl chloride copolymer and does not have a receiving layer containing a styrene resin, has excellent gloss, excellent ink absorption and drying properties, and excellent image density, but cannot prevent waviness and blocking, and is poor in weather resistance. Furthermore, the recording paper of Comparative Example 3, which is provided with a receiving layer containing a propylene homopolymer and does not have a receiving layer containing a styrene resin, has poor ink absorption and drying properties and is poor in suitability for solvent inkjet printing. [Industrial Applicability]

[0121] The recording paper according to the present invention is a recording paper that combines high smoothness and excellent glossiness, has high image density, is excellent in ink absorption and drying properties, and does not require water resistance or stain resistance treatment even when the printed matter is exposed outdoors for a long period of time. Therefore, the recording paper according to the present invention is very useful as a display such as a sticker, label, sign, poster, advertisement, etc. The recording paper according to the present invention is also very useful as a recording paper for solvent ink-jet printing using solvent-based inks.

[0122] This application claims priority to Japanese patent application No. 2021-060712, filed on March 31, 2021, and incorporates all of the contents of that Japanese patent application by reference. [Explanation of symbols]

[0123] 100 Recording paper, 10 Receptive layer, 20 Base layer, 21 Core layer, 22 Back layer

Claims

1. A recording paper for solvent inkjet recording, comprising a substrate layer made of a thermoplastic resin film and a receiving layer containing a styrene-based resin provided on one side of the substrate layer, The recording paper, wherein the receiving layer is a stretched porous layer stretched in at least one direction.

2. A recording paper for solvent inkjet recording, comprising a receiving layer containing a styrene-based resin on either side of a base layer made of a thermoplastic resin film, A recording paper in which the receiving layer does not contain an inorganic filler or an organic filler, or the receiving layer contains an inorganic filler or an organic filler and the total content of the inorganic filler and the organic filler in the receiving layer is 20 mass% or less.

3. A recording paper for solvent inkjet recording, comprising a receiving layer containing a styrene-based resin on either side of a base layer made of a thermoplastic resin film, The recording paper, wherein the styrene-based resin comprises at least one selected from the group consisting of a copolymer of a styrene-based monomer, ethylene, and butadiene; a copolymer of a styrene-based monomer, an α-olefin, and butadiene; and a copolymer of a styrene-based monomer, ethylene, an α-olefin, and butadiene.

4. A recording paper for solvent inkjet recording, comprising a receiving layer containing a styrene-based resin on either side of a base layer made of a thermoplastic resin film, the base layer is a thermoplastic resin film containing a polyolefin-based resin as the thermoplastic resin, The recording paper, wherein the receiving layer further contains a polyolefin resin.

5. 5. The solvent ink-jet recording paper according to claim 1, wherein the receiving layer has a thickness of 3 μm or more.

6. 6. The recording paper for solvent ink jet recording according to claim 1, wherein the receiving layer has a layer strength of 0.9 to 2.0 kgf / cm.

7. The recording paper for solvent inkjet according to any one of claims 1 to 6, characterized in that the arithmetic average roughness (Ra) of the surface on the base layer side (back layer side) of the recording paper for solvent inkjet according to JIS B0601:2003 is 0.2 μm or more.

8. 8. The recording paper for solvent ink-jet recording according to claim 1, wherein the static friction coefficient of the surface of the receiving layer side of the recording paper for solvent ink-jet recording is 0.10 to 0.70 according to JIS K7125:1999.

9. The recording paper for solvent inkjet according to any one of claims 1 to 8, characterized in that the surface resistivity of the surface of the base layer side (back layer side) of the recording paper for solvent inkjet, measured in accordance with JIS K6911:2006, is 1 x 10 to 9 x 10 Ω.

10. The solvent inkjet recording paper according to any one of claims 1 to 9, characterized in that the bending resistance of the solvent inkjet recording paper measured by bending rebound A method (Gurley method) according to JIS L1096:2010 is 0.3 to 10 mN.

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