WO2022210605A1

WO2022210605A1 - Recording paper

Info

Publication number: WO2022210605A1
Application number: PCT/JP2022/015190
Authority: WO
Inventors: 優佳北村; 祐太郎菅俣
Original assignee: 株式会社ユポ・コーポレーション
Priority date: 2021-03-31
Filing date: 2022-03-28
Publication date: 2022-10-06
Also published as: JPWO2022210605A1

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

Recording sheet

The present invention relates to recording paper.

Inkjet printing allows computer-generated full-color images to be printed as-is without the need for a printing plate. Inkjet printing is widely used in many fields because it does not require printing plates and because computer generated images can be easily modified.
Inks used in inkjet printing are generally water-based inks, such as those used in home-use inkjet printers, but solvent-based inks are also preferred due to their water resistance and ink fixability. Solvent-based inks are now being used even in indoor exhibitions and the like where water-based inks have been used in the past.

Recording paper is required to have high absorbency so that the solvent in the solvent-based ink can be dried quickly after recording. Various studies have been made to achieve such solvent absorbability (see, for example, Patent Documents 1 and 2).

JP 2010-234677 A Japanese Patent Application Laid-Open No. 2001-270238

However, the receiving layer containing a vinyl chloride copolymer as in Patent Document 1 has problems such as waviness caused by solvents, blocking, and low weather resistance. Attempts to remedy these problems with additives can adversely affect printability. Further, the pigment coating as disclosed in Patent Document 2 has problems such as easy adhesion of water and dirt, low strength of the receiving layer, low glossiness, and low sharpness of the image.

In view of the above-mentioned problems of the prior art, the present invention combines high smoothness and excellent glossiness, has high image density, is excellent in solvent-based ink absorption and drying properties, and is used when printed matter is exposed outdoors for a long period of time. To provide a recording paper which does not require water-resistant and antifouling treatment.

In order to solve these problems, the present inventors have made intensive studies. As a result, the present inventors have found that recording paper having the desired properties can be provided, and have completed the present invention.
That is, the present invention is as follows.

(1) A recording paper having a receiving layer containing a styrene-based resin provided on one side of a substrate 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 styrene resin is a copolymer of styrene monomer, ethylene and butadiene; a copolymer of styrene monomer, α-olefin and butadiene; and a styrene monomer, ethylene, α- The recording paper according to any one of (1) to (3), comprising at least one selected from the group consisting of copolymers of olefins and butadiene.
(5) The arithmetic average roughness (Ra) according to JIS B0601:2003 of the base layer side (back layer side) surface of the recording paper is 0.2 μm or more (1) to (4). Recording paper according to any one of
(6) The recording paper according to any one of (1) to (5), wherein the static friction coefficient according to JIS K7125:1999 of the receiving layer side surface of the recording paper is 0.10 to 0.70. .
(7) The surface resistivity of the substrate layer side (back layer side) surface of the recording paper measured according to JIS K6911:2006 is 1×10 ⁸ to 9×10 ¹² Ω. The recording paper according to any one of (1) to (6).
(8) According to any one of (1) to (7), the bending resistance of the recording paper according to JIS L1096:2010 bending resistance A method (Gurley method) is 0.3 to 10 mN. recording paper.

According to the present invention, it has both high smoothness and excellent glossiness, high image density, excellent ink absorption and drying properties, and is waterproof and antifouling even when the printed matter is exposed to the outdoors for a long time. It is possible to provide recording paper that does not require

1 is a schematic cross-sectional view showing an example of the layer structure of a recording sheet; FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a recording sheet; FIG.

The recording paper of the present invention will be described in detail below. The following are examples (representative examples) of the present invention, and the present invention is not limited thereto.

In the following description, the description of "(meth)acrylic" refers to both acrylic and methacrylic.

[Recording sheet]
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a recording sheet of this embodiment. A recording paper 100 shown in FIG. 1 has at least a receiving layer 10 containing a styrene resin on one side of a base layer 20 made of a thermoplastic resin film. Moreover, 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 of the receiving layer 10 side in FIGS. 1 and 2 .

(receptive layer)
The receiving layer is provided on the base material layer and positioned on the outermost surface of the recording paper of the present embodiment. The receiving layer receives solvent-based inks.

<Styrene resin>
The receiving layer contains a styrenic resin. By containing a styrene-based resin in the receiving layer, it is possible to improve the absorption and drying properties of the solvent-based ink.

Styrenic resins are polymers mainly having structural units derived from styrene, and are homopolymers of styrene monomers or copolymers with other monomer components.
In the receiving layer, from the viewpoint of suppressing bleeding during solvent inkjet printing, as the styrene resin, only homopolymers of styrene monomers and copolymers of styrene monomers and other monomers are used. It may consist of On the other hand, from the viewpoint of interlaminar strength with the substrate layer, the styrene-based resin used in the receiving layer is a homopolymer of a styrene-based monomer, and a copolymer of a styrene-based monomer and another monomer. It preferably includes coalescence.
The styrenic resins used in the receptor layer can be used singly or in combination of two or more.
Styrenic monomers include, for example, styrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, vinyltoluene, vinylxylene, and vinylnaphthalene.

Olefins are preferably used as other monomers in the copolymer. Olefins include, for example, α-olefins; diene-based monomers; and other monomers such as ethylene, propylene and cyclohexene. Specific examples of α-olefins include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, and 1-decene. is mentioned. Examples of diene-based monomers include butadiene, isoprene, and chloroprene. The copolymer may be a binary system or a multi-component system having a ternary or higher monomer component, and may be a random copolymer or a block copolymer.
Further, as other monomer components in the copolymer, for example, (meth)acrylic acid, (meth)acrylic acid ester, maleic anhydride, vinyl acetate, acrylonitrile and the like may be used.

Styrene-based resins include, for example, styrene homopolymers, styrene/ethylene copolymers, styrene/propylene copolymers, styrene/butadiene copolymers, styrene/butadiene/styrene copolymers, styrene/isoprene copolymers, styrene・Isoprene-styrene copolymer, styrene-ethylene-butylene copolymer, styrene-ethylene-propylene copolymer, styrene-ethylene-butadiene copolymer, styrene-butadiene-butylene copolymer, styrene-acrylonitrile copolymer , acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-acrylate copolymer, methacrylate-butadiene-styrene copolymer, styrene-ethylene-butylene-butadiene copolymer, and styrene-ethylene-butadiene- Styrene copolymers and the like can be mentioned. The copolymer may be a random copolymer or a block copolymer. The styrenic resin may be a hydrogenated product.

Among them, the styrene-based resin preferably contains a copolymer of a styrene-based monomer and butadiene, a copolymer of styrene-based monomer, ethylene and butadiene; and at least one selected from the group consisting of copolymers of styrenic monomers, ethylene, α-olefins and butadiene.

Examples of the styrene resin include a styrene/ethylene/butadiene copolymer, a styrene/1-butene/butadiene copolymer, a styrene/1-pentene/butadiene copolymer, a 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 copolymers, and styrene/ethylene/1-decene/butadiene copolymers.

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, from the viewpoint of improving solvent-based ink absorption and drying properties and suppressing waviness after printing. % by mass or more is more preferable. 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 interlaminar strength between the core layer and the receiving layer. Further, when the styrenic resin contains a homopolymer of a styrenic monomer, and a copolymer of a styrenic monomer and other monomers, the content of the copolymer is From the viewpoint of interlaminar strength between layers, the amount is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more relative to the total amount of the styrene resin. From the viewpoint of smoothness, 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 relative to the total amount of the styrene resin.

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 the styrene resin may be a resin compatible with the styrene resin from the viewpoint of image clarity, or a resin not compatible with the styrene resin from the viewpoint of drying. may Here, "a resin compatible with a styrene resin" refers to a resin that forms a single phase when mixed with a styrene resin in a mass ratio of 1:1 and heated at 230°C. When the thermoplastic resin in the receiving layer consists only of a styrene-based resin, or when it contains a styrene-based resin and a resin compatible with the styrene-based resin, there is a tendency that bleeding during solvent inkjet printing can be suppressed. In addition, when the thermoplastic resin in the receiving layer contains a styrene resin and a resin that is not compatible with the styrene resin, the solvent easily penetrates through the gaps between the resins, and the solvent-based ink dries. tend to improve.
Thermoplastic resins that can be used in combination include, for example, polyethylene-based resins, polypropylene-based resins, and polyolefin-based resins such as ethylene/cyclic olefin copolymers; 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 polycarbonate and aliphatic polycarbonate. Among these, polyolefin-based resins are preferable as thermoplastic resins that can be used together from the viewpoint of suppressing a decrease in interlaminar strength with the base layer when the adjacent base layer contains a polyolefin-based resin.

<Filler>
The receiving layer may contain fillers. Examples of usable fillers include inorganic fillers and organic fillers. When the base material layer contains a highly solvent-resistant resin such as polyolefin resin, the base material layer follows the shrinkage of the receiving layer due to the dissolution of the styrene resin during printing, and curling occurs on the printed surface side. There is However, by containing a filler in the receiving layer, shrinkage of the receiving layer can be suppressed even if the styrene-based resin is dissolved, and curling can be reduced. In addition, when the receiving layer contains a filler, a gap is likely to occur between the receiving layer and the surrounding thermoplastic resin such as a styrene-based resin, which tends to improve the drying property of the solvent-based ink. When the receiving layer is a stretched layer that is stretched in at least one direction, the containing of the filler tends to form pores inside the receiving layer, resulting in a stretched porous layer. If the receiving layer is a stretched porous layer, the solvent-based ink absorption and drying properties are further enhanced.

<<Inorganic filler>>
Examples of inorganic fillers include calcium carbonate, calcined clay, silica, diatomaceous earth, clay, talc, titanium oxide, barium sulfate, barium titanate, alumina, zeolite, mica, sericite, bentonite, sepiolite, vermiculite, dolomite, wax. Inorganic particles such as lastonite or glass fibers can be used. The average particle size of the inorganic filler as measured by a particle size distribution meter based on laser diffraction is usually 0.01 to 15 μm, preferably 0.1 to 5 μm.

<<Organic filler>>
Examples of organic fillers that can be used include organic particles of polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, melamine resin, polyethylene sulfite, polyimide, polyethyl ether ketone, or polyphenylene sulfite. can.

As the filler, the above inorganic filler and organic filler can be used alone or in combination.
The content of the filler in the receptive layer (when an inorganic filler and an organic filler are used together, the total amount thereof) can be, for example, 65% by mass or less, or 55% by mass or less. From the viewpoint of obtaining glossiness or smoothness, the content of the filler in the receiving layer is preferably 20% by mass or less, more preferably 10% by mass or less. From the viewpoint of obtaining solvent-based ink absorbability and drying properties when the receiving layer is 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. It is preferably 40% by mass or more, and more preferably 40% by mass or more.

<Other ingredients>
The receiving layer may further contain a curing agent, an ink-setting agent, an ultraviolet absorber, a surfactant, or the like, if necessary. These can be contained within a range that does not impair the effects of the present invention.

The receiving layer may be an unstretched film or a stretched film. From the viewpoint of facilitating control of the solvent absorption amount and solvent absorption rate, the receiving layer is preferably a stretched film stretched in at least one direction.

The surface of the receiving layer may be subjected to oxidation treatment. Oxidation treatment tends to adjust the wettability of the surface and suppress print bleeding. In addition, the oxidation treatment can adjust the polarity ratio of the surface, facilitates obtaining chemical bonding strength with the solvent-based ink, and tends to improve the adhesion between the recording paper and the ink-jet printing layer.
The oxidation treatment includes corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment and the like, 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.

<Characteristics of receptive layer>
<<Amount of solvent absorbed>>
The solvent absorption amount of the receiving layer is preferably 5 ml/m ² or more, more preferably 10 ml/m ² or more, and even more preferably 15 ml/m ² or more. On the other hand, the solvent absorption amount of the receiving layer is preferably 100 ml/m ² or less, more preferably 90 ml/m ² or less, and even more preferably 80 ml/m ² or less. If the solvent absorption amount of the receiving layer is within the above range, the drying property of the solvent-based ink is excellent, so solvent-based ink transfer can be reduced when the recording paper after solvent-inkjet printing is stacked on other paper and stored. tend to be able to
A specific method for measuring the amount of solvent absorbed by the receiving layer will be described in Examples.

<<Solvent absorption rate>>
The solvent absorption rate of the receiving layer is preferably 10 ml/m ² ·s or more, more preferably 20 ml/m ² ·s or more, and even more preferably 30 ml/m ² ·s or more. On the other hand, the solvent absorption rate of the receiving layer is preferably 100 ml/m ² ·s or less, more preferably 90 ml/m ² ·s or less, and even more preferably 80 ml/m ² ·s or less. If the solvent absorption rate of the receptive layer is within the above range, the solvent-based ink will quickly penetrate into the receptive layer. Bleeding tends to decrease when the
A specific method for measuring the solvent absorption rate of the receiving layer will be described in Examples.

<<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 receptive layer is within the above range, the receptive layer is less likely to be scraped by sand or the like when the recording paper is posted outdoors, and the weather resistance is high, so the printed pattern can be maintained for a long period of time. tend to be able to
A specific method for measuring the layer strength of the receiving layer will be described in Examples.

<<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. A porosity of 5% or more tends to increase solvent absorption and improve ink drying properties. Further, when the porosity is 70% or less, smoothness and glossiness tend to be improved.

<<Thickness>>
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, from the viewpoint of sufficiently absorbing the solvent. On the other hand, 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.

(Base material layer)
The base material layer is a resin film containing a thermoplastic resin, and is provided as a support for recording paper. The substrate layer may have a single-layer structure, or may have a multi-layer structure of two or more layers. In addition, since the receiving layer is laminated on at least one surface of the base layer, the base layer may be subjected to corona discharge treatment in order to improve adhesion to the receiving layer.

As the thermoplastic resin, the thermoplastic resins listed for the receiving layer can be used. Among them, from the viewpoint of mechanical strength, the thermoplastic resin is preferably a polyolefin resin.

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

The polypropylene-based resin is not particularly limited as long as propylene is used as the main monomer. Examples of polypropylene-based resins include isotactic polymers and syndiotactic polymers obtained by homopolymerizing propylene. Further, as the polypropylene resin, propylene as a main component and α-olefin such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene It is also possible to use a propylene-α-olefin copolymer, etc., which is a copolymer with. The copolymer may be a binary system or a multi-component system having three or more monomer components, and may be a random copolymer or a block copolymer. Also, a propylene homopolymer and a propylene copolymer may be used in combination.

Examples of polyethylene-based resins include high density polyethylene with a density of 0.940 to 0.965 g/cm ³ , medium density polyethylene with a density of 0.920 to 0.935 g/cm ³ , and density of 0.900 g/cm ³ or more. Linear low-density polyethylene of less than 0.920 g/cm ³ , a copolymer mainly composed of ethylene, etc., and copolymerized with an α-olefin such as propylene, butene, hexene, heptene, octene, 4-methylpentene-1, etc. , 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, ethylene- Examples thereof include metal salts of methacrylic acid copolymers (metals include zinc, aluminum, lithium, sodium, potassium, etc.), ethylene/cyclic olefin copolymers, and maleic acid-modified polyethylene.

Further, as the polyolefin resin, a graft-modified product thereof can be used as needed from the viewpoint of improving the adhesiveness or moldability of the resin film.
A known technique can be used for graft modification. Specifically, a graft-modified product 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 unsaturated carboxylic acid derivatives include acid anhydrides, esterified products, amidated products, imidized products, and metal salts of the above unsaturated carboxylic acids.

Specific graft monomers include, for example, 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-N-mono Ethylamide, 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 (meth)acrylic Potassium acid and the like can be mentioned.

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

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

From the viewpoint of film moldability, it is possible to use a resin with a melting point equal to or lower than that of a propylene homopolymer in a polypropylene resin film. Such resins include polyethylene-based resins, specifically high density or low density polyethylene. The content of polyethylene-based resin can be, for example, 2 to 25% by mass.

The base material layer may be a resin film using only a polyolefin-based resin as the thermoplastic resin, or may contain a thermoplastic resin other than the polyolefin-based resin within a range that does not impair the effects of the present invention.

<Filler>
The base material layer may contain a filler. When the base material layer is a stretched film, the base material layer contains a filler, and voids originating from the filler are formed by stretching to form a porous layer. When the substrate layer is a porous layer, it is possible to reduce the weight of the substrate layer and the recording paper. Furthermore, since the substrate layer is a porous layer, it becomes easier to obtain a white film having a texture of paper. Therefore, it becomes easy to adjust the whiteness or opacity of the film depending on the presence or absence of the filler contained in the base material layer.

As the filler that can be used in the substrate layer, the same fillers as those listed in the receiving layer can be used. 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 material layer (the total amount when an inorganic filler and an organic filler are used together) is preferably 0 to 60% by mass, more preferably 0 to 50% by mass.

<Other ingredients>
The substrate layer may further contain a heat stabilizer (antioxidant), light stabilizer, dispersant, lubricant, nucleating agent, or the like, if necessary.
As the heat stabilizer, for example, a sterically hindered phenolic antioxidant, a phosphorus antioxidant, an amine antioxidant, or the like 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 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. For the purpose of dispersing fillers, for example, these can be used within the range of 0.01 to 4% by mass.

The substrate layer may be an unstretched film or a stretched film. From the viewpoint of increasing the strength of the recording paper, the substrate layer is preferably a stretched film stretched in at least one direction.
When the substrate layer has a multilayer structure, it preferably contains a stretched film stretched in at least one direction, and more preferably contains a porous stretched film having pores therein. Since the base layer containing the stretched film has high mechanical strength and excellent thickness uniformity, it is possible to obtain a recording paper having excellent post-processing properties.
When the substrate layer has a multilayer structure, the number of stretching axes of each layer is 1 axis/1 axis, 1 axis/2 axes, 2 axes/1 axis, 1 axis/1 axis/2 axes, 1 axis/2 axes/ It may be 1-axis, 2-axis/1-axis/1-axis, 1-axis/2-axis/2-axis, 2-axis/2-axis/1-axis, or 2-axis/2-axis/2-axis.

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

(ρ ₀ indicates the true density of the substrate layer, ρ indicates the density of the substrate layer)

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

<Core layer and back layer>
The substrate layer may have a single-layer structure as described above, or may have a multi-layer structure of two or more layers. When the substrate layer has a multi-layer structure, each layer can have different properties to exhibit various functions, which is preferable. In particular, the base material layer 20 preferably has a core layer 21 and a back layer 22 as shown in FIG.

<Core layer>
The core layer is a resin film containing a thermoplastic resin and provided as a support for the recording paper. The composition of the core layer is the same as the composition of the substrate layer.

The thickness of the core layer can be appropriately determined according to the thickness of the back layer described later. The thickness of the core layer is preferably 40 to 200 μm, more preferably 50 to 150 μm, from the viewpoint of obtaining sufficient stiffness.

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

<Back layer>
The back layer is provided on the surface of the core layer opposite to the receiving layer. The back layer mainly has a function of promoting the evaporation of the solvent after printing from the receiving layer and suppressing waviness of the paper surface due to the solvent when the recording sheets are stacked and stored. Further, the surface of the back surface layer has moderate surface roughness unlike the receiving layer which has smoothness. When the recording paper is stacked and stored, the occurrence of blocking can be prevented by providing the surface of the back surface layer with a suitable surface roughness.

In addition, the back layer imparts antistatic properties to the recording paper, thereby making it difficult for troubles to occur in the printing process and improving handling properties.
Because the back layer has antistatic properties, even if the recording paper has an electric charge inside, the back layer surface has a low electrostatic adsorption force, which prevents sticking to the roll and the sheet during the printing process. This makes it difficult for troubles such as mutual blocking to occur.

<Composition of Back Layer>
The same material as the base layer can be used for the back layer. However, the content of the filler in the back layer (the total amount when an inorganic filler and an organic filler are used together) is preferably 5 to 60% by mass from the viewpoint of surface roughness and static friction coefficient, and 10 to 10% by mass. 50% by mass is more preferred.

The thickness of the back layer can be appropriately determined according to the thickness of the core layer described above. The thickness of the back layer is preferably 1 to 50 μm, more preferably 1 to 20 μm, and still more preferably 2 to 10 μm, from the viewpoint of developing appropriate surface roughness.

The porosity of the back layer is preferably 5-60%, more preferably 5-50%, and more preferably 10-40%. Due to the presence of pores, there is a tendency that the surface roughness of the back layer can be controlled within a predetermined range.

A coating layer can also be provided on the surface of the back layer. The coating layer can contain an anchoring agent, a polymeric antistatic agent, and the like. By including the anchoring agent in the coating layer, when the inkjet printing layer is provided on the coating layer, there is a tendency that the adhesion between the coating layer and the inkjet printing layer can be improved. In addition, when the coating layer contains an antistatic agent, there is a tendency that the antistatic performance of the back layer side can be improved. Examples of anchoring agents include polyimine-based polymers and ethyleneimine adducts of polyamine polyamides. Polymer-type antistatic agents include those having an ammonium salt structure or a phosphonium salt structure. When an anchoring agent and an antistatic agent are used in combination, from the viewpoint of fully exhibiting the performance of each component, the solid content ratio is preferably 0 to 200 parts by mass of the antistatic agent with respect to 100 parts by mass of the anchoring agent, more preferably. 20 to 150 parts by mass, more preferably 30 to 100 parts by mass.

[Characteristics of recording paper]
(bending resistance)
The recording paper is also suitable for use in posters and other notices, and in the case of use for notices, it is preferable that it has a certain degree of rigidity from the viewpoint of ease of handling at the time of 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 is stiff and easy to handle. In addition, there is a tendency that wrinkles are less likely to occur when sticking to a sticking object. Furthermore, there is a tendency that waviness after printing can be suppressed.
The bending resistance in this embodiment is based on the bending repulsion A method (Gurley method) according to JIS L1096:2010.
A specific method for measuring the bending resistance of recording paper by the Gurley method will be described in Examples.

(Glossiness)
The glossiness 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 glossiness of the surface of the receiving layer is equal to or higher than the above lower limit, it can be said that a sufficiently high glossiness is obtained at least as compared with recording paper using a pigment coating or the like, and images tend to be sharp and have good appearance. There is
The glossiness in this embodiment is based on the glossiness according to JIS P 8142:1993.
A specific method for measuring the glossiness of the receiving layer side surface of the recording paper will be described in Examples.

(Static friction coefficient)
The coefficient of static friction 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 coefficient of static friction 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 coefficient of static friction 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 will be good. The coefficient of friction is also affected by the arithmetic mean roughness of the receiving layer side surface, and the coefficient of static friction tends to decrease as the arithmetic mean roughness increases.
The static friction coefficient in this embodiment is based on JIS K7125:1999.
A specific method for measuring the coefficient of static friction of the receiving layer side surface of the recording paper will be described in Examples.

(Arithmetic mean roughness (Ra))
The arithmetic mean roughness (Ra) of the substrate layer side surface of the recording paper (the back surface layer side when the core layer and the back surface layer are provided as the substrate layer) is preferably 0.1 μm or more, and more preferably 0.2 μm or more. It is preferably 0.3 μm or more, and more preferably 0.3 μm or more. On the other hand, the arithmetic mean roughness of the substrate layer side surface of the recording paper 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 surface of the recording paper on the substrate layer side is within the above range, the occurrence of blocking tends to be suppressed when the recording papers are stacked and stored.
The arithmetic mean roughness (Ra) in this embodiment is based on JIS B0601:2003.
A specific method for measuring the arithmetic mean roughness (Ra) of the substrate layer side surface of the recording paper will be described in Examples.

(Surface resistivity)
The surface resistivity of the substrate layer side surface of the recording paper (or the back layer side when a core layer and a back layer are provided as the substrate layer) is preferably 1×10 ⁻¹ Ω or more, and preferably 1×10 ¹ Ω or more. More preferably, it is 1×10 ⁸ Ω or more. On the other hand, the surface resistivity of the substrate layer side surface of the recording paper is preferably 9×10 ¹² Ω or less, more preferably 5×10 ¹² Ω or less, and even more preferably 1×10 ¹² Ω or less. 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 recording papers in the printing process.
The surface resistivity in this embodiment is based on JIS K6911:2006.
A specific method for measuring the surface resistivity of the surface of the recording paper on the substrate layer side will be described in Examples.

(thickness)
The recording paper of this embodiment includes at least a receiving layer and a substrate layer, and the total thickness of the recording paper is preferably 40 to 200 μm. In the present embodiment, another layer such as a propylene-based resin layer containing 8 to 55% by mass of an inorganic filler is further added between the receiving layer and the substrate layer in order to further add a paper-like texture. may be formed. Further, other layers may contain a small amount of propylene copolymer, high-density polyethylene, polystyrene, low-melting-point resin such as ethylene-vinyl acetate copolymer, etc., in order to improve stretchability.

[Manufacturing method of recording paper]
The recording paper of the present embodiment can be produced by laminating a receiving layer and a substrate layer (core layer and back layer) in this order, and the production method is not particularly limited. For example, a recording paper comprising a receptor layer, a core layer and a back layer can be produced by the following method.

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

(stretching)
Each layer may be stretched individually prior to lamination or may be stretched together after lamination. Alternatively, the unstretched layer and the stretched layer may be laminated and then stretched again.

Examples of stretching methods for stretching a film include a longitudinal stretching method utilizing a peripheral speed difference between rolls, a transverse stretching method utilizing a tenter oven, a sequential biaxial stretching method combining these methods, a rolling method, and a tenter oven. A simultaneous biaxial stretching method using a combination of pantographs and a simultaneous biaxial stretching method using a combination of a tenter oven and a linear motor can be used. In addition, as a stretching method, a simultaneous biaxial stretching (inflation molding) method of extruding a molten resin into a tubular shape using a circular die connected to a screw type extruder and then blowing air into it can also be used. .

When the thermoplastic resin used for the film is an amorphous resin, the stretching temperature when stretching is preferably in the range of the glass transition temperature of the thermoplastic resin or higher. Also, when the thermoplastic resin is a crystalline resin, the stretching temperature should be above the glass transition point of the non-crystalline portion of the thermoplastic resin and below the melting point of the crystalline portion of the thermoplastic resin. is preferred, and specifically, a temperature lower than the melting point of the thermoplastic resin by 2 to 60°C is preferred.

The stretching speed is not particularly limited, but from the viewpoint of stable stretching molding, it is preferably in the range of 20 to 350 m/min.
In addition, the draw ratio can also be appropriately determined in consideration of the properties of the thermoplastic resin to be 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 draw ratio is usually 1.2 times or more, preferably 2 times or more. The upper limit is usually 12 times or less, preferably 10 times or less. The draw ratio in the case of biaxial stretching is an area draw 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. It is below.

(surface treatment)
From the viewpoint of enhancing adhesion to the receiving layer, the substrate layer is preferably subjected to an oxidation treatment to activate its surface. Moreover, the surface of the receiving layer may be subjected to an oxidation treatment. Oxidation treatment tends to adjust the wettability of the surface and suppress print bleeding.
Examples of oxidation treatment include corona discharge treatment, flame treatment, plasma treatment, glow discharge treatment, ozone treatment, and the like, and these treatments can be combined. Among them, the oxidation treatment is preferably corona discharge treatment or flame treatment, and more preferably corona discharge treatment.

The amount of discharge when performing corona discharge treatment is preferably 600 J/m ² (10 W·min/m ² ) or more, more preferably 1,200 J/m ² (20 W·min/m ² ) or more. On the other hand, it is preferably 12,000 J/m ² (200 W·min/m ² ) or less, more preferably 10,800 J/m ² (180 W·min/m ² ) or less. The discharge amount when flame treatment is performed is preferably 8,000 J/m ² or more, more preferably 20,000 J/m ² or more, and preferably 200,000 J/m ² or less. It is preferably 100,000 J/m ² or less.

Specific examples of coating means for providing a coating layer on the surface of the back layer include gravure coating, Meyer bar coating, roll coating, blade coating, size press coating, and the like. can be adopted. Also, the coating amount can be generally 0.01 to 20 g/m ² , preferably 0.1 to 15 g/m ² .

[Use of recording paper]
The recording paper obtained as described above can be suitably used for a solvent-based ink using a solvent and a coloring material peculiar to the solvent-based ink.

Examples of solvents used for solvent-based inks include glycol ether-based solvents such as polyoxyethylene glycol dialkyl ether, polyoxyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether. Examples of coloring materials used in solvent-based inks 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, and benzoquinone dyes. , carbonium dyes, naphthoquinone dyes, naphthalimide dyes, phthalocyanine dyes, and perine dyes. Carbon black and various color pigments are used as pigments, and organic pigments include insoluble azo pigments, condensed azo pigments, chelate azo pigments, perinone pigments, nitro pigments, nitroso pigments, perylene pigments, and aniline black.

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. Descriptions of "parts", "%", etc. in the examples are based on mass unless otherwise specified.

[Test method]
(Amount of solvent absorbed)
The solvent absorption amount of 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 determined by contacting the surface of the receptive 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 measuring the weight of the test piece. It was measured. Then, the mass of the test piece measured was subtracted from the original mass of the test piece, and the mass of the solvent absorbed per 1 m ² was taken as the solvent absorption amount (ml/m ² ).

(solvent absorption speed)
The solvent absorption rate of the receiving layer of the recording paper can be measured using a water absorption tester specified in JIS P8140. The solvent absorption speed of the recording paper was determined 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 5 seconds, calculating the amount of solvent absorption, and calculating the solvent contact time. The value obtained by dividing was taken as the solvent absorption rate (ml/m ² ·s).

<Layer strength>
The layer strength of the receiving layer of the recording paper was measured by sticking cellophane tape (manufactured by Nichiban Co., Ltd., trade name: CT-18) on the surface of the receiving layer, and measuring JAPAN TAPPI No. 1. Using an internal bond tester (manufactured by Kumagai Riki Kogyo Co., Ltd., trade name) according to 18-2 (internal bond strength test method), the peel strength of the ink is measured, and the average of the two measurement results The value was taken as the layer strength.

<Thickness>
The thickness (total thickness) of the recording paper was measured according to JIS K7130:1999 using a constant pressure thickness measuring instrument (trade name: PG-01J, manufactured by Teclock Co., Ltd.). In addition, the thickness of each layer in the recording paper can be measured by cooling the sample to be measured with liquid nitrogen to a temperature of -60°C or lower and placing it on a glass plate with a razor blade (manufactured by Sic Japan Co., Ltd. A sample for cross-sectional observation is prepared by cutting at a right angle with a proline blade), and the obtained sample is cross-sectioned using a scanning electron microscope (manufactured by JEOL Ltd., trade name: JSM-6490). Observation was performed, and the boundary line for each resin composition was determined from the appearance of the composition, and the total thickness of the recording paper was multiplied by the thickness ratio of each layer observed.

<Gurley hardness>
The Gurley bending resistance of the recording paper conforms to JIS L1096:2010 and is measured in the MD direction using a Gurley bending resistance tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.; (trade name: GAS-100)).

<Glossiness>
The glossiness of the receiving layer side surface of the recording paper was measured according to JIS P 8142:1993, and the 75 degree specular glossiness was measured.

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

<Arithmetic mean roughness Ra>
The arithmetic mean roughness Ra (μm) of the substrate layer side surface of the recording paper (the back layer side when the core layer and the back layer are provided as the substrate layer) is in accordance with JIS B0601: 2003, and the three-dimensional roughness Measurement was performed using a measuring device (manufactured by Kosaka Laboratory Co., Ltd., trade name: SE-3AK) and an analysis device (manufactured by Kosaka Laboratory Co., Ltd., trade name: SPA-11).

<Surface resistivity>
The surface resistivity of the substrate layer side surface of the recording paper (the back surface layer side when the core layer and the back layer are provided as the substrate layer) is 1 under the conditions of 23° C. and 50% relative humidity. In the case of ×10 ⁷ Ω or more, it was measured using an electrode of the double ring method according to JIS K6911:2006. When the surface resistivity is less than 1×10 ⁷ Ω, the resistance (R) obtained by measuring with the 4-probe method in accordance with JIS K7194:1994 is multiplied by the correction factor F to obtain the surface resistivity. and

(Evaluation of printability)
After storing the recording paper in an atmosphere of 23 ° C. and 50% relative humidity for 1 day, an inkjet printer "SC-S80650" (manufactured by Seiko Epson Corporation) was applied to the receiving layer surface of the recording paper. Solid printing was performed with SC10BK70 ink at a resolution of 720×1440 dpi with the drive waveform of the element optimized, and then heat treatment (heat drying) was performed at 50° C.×30 seconds. The printability was evaluated according to the following criteria.

<Density>
After solvent inkjet printing, the printed surface is measured for print density at 9 black areas per sample using a portable spectral densitometer (manufactured by X-Rite Co., Ltd., trade name "508"), and the average value is obtained. Concentration was determined according to the following criteria.
3 (Good): 1.4 or higher, ink color development is good 2 (Acceptable): Less than 1.4, slight decrease in density is observed at 1.2 or higher, but no problem (practical lower limit)
1 (impossible): less than 1.2 (not practical)

<Bleeding>
After the solvent ink jet printing, the state of the printed image on the recording paper was visually observed by enlarging it with a magnifying glass. The blurring of the recording paper was evaluated according to the following criteria based on the state of the observed image.
3 (Good): The image is clear. 2 (Fair): Ink bleeding is unclear visually, but the dot area is widened when observed with a magnifying glass (lower limit for practical use).
1 (impossible): The image is blurred (not suitable for practical use)

<Drying>
After the solvent ink jet printing, one print sample was arbitrarily taken out every hour, and the dried state of the ink in the solid image area was checked by rubbing with a finger. Dryness was evaluated according to the following criteria.
3 (good): Very fast drying (dries within 10 minutes and does not stick to fingers)
2 (Possible): Drying is fast and not a problem (drying within 20 minutes over 10 minutes, practical lower limit)
1 (impossible): Drying is a little slow and becomes a problem (does not dry even in 20 minutes, not suitable for practical use)

<Fixation>
<< Scrape >>
After solvent inkjet printing, the image portion was cut into a size of 30 mm×120 mm one day after printing, and set in a Gakushin tester (manufactured by Suga Test Instruments Co., Ltd.). As an evaluation under dry conditions, a piece of gauze dried at room temperature was attached to a weight of 215 g, and the surface of the printed image portion was rubbed 100 times with this weight. As an evaluation under wet conditions, gauze impregnated with 20 μL of pure water at room temperature was attached to a weight of 215 g. Observed. Scratching was evaluated according to the following criteria.
3 (good): 95% or more of the rubbed image remains 2 (good): 80% or more of the rubbed image remains (practical lower limit)
1 (impossible): residual rate of rubbed image portion is less than 80% (not suitable for practical use)

<<Ink Adhesion>>
After solvent inkjet printing, the adhesive side of cellophane tape (manufactured by Nichiban Co., Ltd., trade name: Cellotape (registered trademark) CT-18) was attached to the printed surface, and rubbed three times with a finger to ensure sufficient adhesion. After manually peeling the adhered cellophane tape at a speed of 300 m / min in the direction of 180 degrees, using a small general-purpose image analysis device (manufactured by Nireco, model name: LUZEX-AP), the residual rate of ink on the recording paper was calculated. Specifically, an image obtained by photographing the printed surface was subjected to binarization processing, and the ratio of the area occupied by the ink was calculated as the residual ratio. The ink adhesion was evaluated according to the following criteria from the calculated ink residual ratio.
3 (good): 80% or more of ink remaining rate 2 (acceptable): 50% or more and less than 80% of ink remaining rate (practical lower limit)
1 (impossible): ink residual rate is less than 50% (not suitable for practical use)

<Curl>
After solvent ink jet printing, the recording paper was cut into a size of 100 mm×100 mm and stored for 1 day at 23° C. and 50% relative humidity. The recording paper was laid flat with the printed surface facing up, and the curl height at the edge was evaluated according to the following criteria.
3 (Good): Curl height -5 mm to +10 mm
2 (Possible): Curl height +11 mm to +50 mm (practical lower limit)
1 (impossible): Curl height is +51 mm or more, or -6 mm or less (not suitable for practical use)

<waves>
On the receiving layer side of the recording paper, a solid black image is printed using a solvent inkjet printer "Ramires III: PJ-1634NX" (Muto Kogyo Co., Ltd.), and the degree of waviness in the printed area is visually evaluated according to the following criteria. did.
3 (Good): No waviness, very good level 2 (Fair): Slight waviness (lower limit for practical use)
1 (impossible): Occurrence of waviness is observed (not suitable for practical use)

<Blocking>
After the recording paper was wound into a roll and stored for one day in an atmosphere of 40° C. and 50% relative humidity, it was observed whether the paper could be pulled out smoothly without causing blocking when pulled out from the roll. . Blocking was evaluated according to the following criteria.
3 (good): can be pulled out smoothly without a peeling sound 2 (acceptable): there is a peeling sound, but the appearance of the base layer after picking up is not impaired (practical lower limit)
1 (improper): there is a loud peeling sound, and the appearance of the substrate layer after picking up is impaired (not suitable for practical use)

<Weather resistance>
In applications such as posters, the ink may peel off due to outdoor use, which may pose a problem. However, weather resistance evaluation results tend to fluctuate due to various factors such as climate and weather when exposure tests are actually performed outdoors. In this embodiment, the printed matter was subjected to a weather resistance acceleration treatment (exposure test) under uniform conditions in accordance with JIS K-7350-4, and then subjected to solvent inkjet printing to evaluate ink adhesion. More specifically, the acceleration treatment was performed under the following conditions.
A super-accelerated weathering tester (manufactured by Daipla Wintes Co., Ltd., trade name "Metal Weather KU-R5N-A", metal halide lamp type) and a glass filter "KF-2 filter" that transmits ultraviolet light of 295 to 450 nm ( product name) was used. Aluminum foil tape "AL-T" (Takeuchi Kogyo Co., Ltd.) (trade name)) was attached to a stainless steel plate (100 mm x 200 mm) and fixed, and this was installed in the tester. The irradiance on the surface of the test piece was set at 90 W/m ² and the black panel temperature was set at 63°C. Two cycles of accelerated treatment were carried out, one cycle consisting of exposure for 5 hours at a temperature of 63° C. and a relative humidity of 50% and exposure for 3 hours at a temperature of 30° C. and a relative humidity of 98%. The radiation exposure to the printed surface was therefore 5.18 x 106 J/ ^m2 .
Then, the test piece subjected to the accelerated weather resistance treatment was subjected to a friction test and evaluation in the same manner as in the case of scratch resistance.
3 (good): 95% or more of the rubbed image remains 2 (good): 80% or more of the rubbed image remains (practical lower limit)
1 (impossible): residual rate of rubbed image portion is less than 80% (not suitable for practical use)

[Examples and Comparative Examples]
(Examples 1 to 13 and Comparative Examples 1 to 3)
Recording papers of Examples 1 to 13 and Comparative Examples 1 to 3 were manufactured according to the following procedure. Table 1 shows the compounding ratio (mass parts) of the resin composition used in the production of the recording paper.

(Example 1)
After melt-kneading the resin composition a described in Table 1 with an extruder set at 230°C, it is supplied to an extrusion die set at 250°C and extruded into a sheet, which is cooled to 60°C with a cooling device. An unstretched sheet was obtained. This unstretched sheet was heated to 135° C. and stretched 5 times in the machine direction by utilizing the difference in peripheral speed of the roll group to obtain a monolayer uniaxially stretched sheet. Next, the resin composition c is melt-kneaded with an extruder set at 230°C, extruded into a sheet shape and laminated on the first surface of the single-layer uniaxially stretched sheet, and at the same time, the resin composition a is heated to 230°C. After melt-kneading with one set extruder, the mixture was extruded into a sheet and laminated on the second surface of the monolayer uniaxially stretched sheet to obtain a three-layer laminated sheet. Next, the three-layer laminated sheet is cooled to 60°C, heated to about 150°C using a tenter oven, stretched 8.5 times in the horizontal direction, and then heated to 160°C for heat treatment. did Then, the uniaxially stretched layer of the resin composition a is the back layer, the thickness is 140 μm, the resin composition (c/a/a) of each layer, the thickness of each layer ( 20 μm/100 μm/20 μm) and the number of stretching axes of each layer (1 axis/2 axes/1 axis)].

In a container equipped with a stirrer, 50 parts by mass of a polyethyleneimine solution (manufactured by Nippon Shokubai Co., Ltd., trade name: Epomin P-1000) and a cationic system containing a quaternary ammonium salt structure represented by the following formula in its molecular chain 50 parts by mass of a polymer solution having an antistatic function of a methacrylic acid ester copolymer is added in this order, then diluted with water so that the solid content concentration is 20% by mass, and stirred for 20 minutes to mix and disperse. Then, a coating liquid b was prepared.

The surface of the back layer of the laminated resin film is subjected to surface treatment by corona discharge, and the coating solution b is applied to the corona discharge-treated surface side and dried to form a coating layer having a thickness of 0.1 μm. After drying in an oven for 60 seconds, the recording paper of Example 1 was obtained.

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

(Example 7)
Example 1 except that the resin composition i of the receiving layer described in Table 2 was used instead of the resin composition c in Example 1, the thickness was 170 μm, and the thickness of each layer was (50 μm/100 μm/20 μm). Recording paper of Example 7 was obtained in the same manner as above.

(Example 8)
A recording paper of Example 8 was obtained in the same manner as in Example 7, except that the thickness was changed to 130 μm and the thickness of each layer was changed to (10 μm/100 μm/20 μm).

(Example 9)
A recording paper of Example 9 was obtained in the same manner as in Example 7 except that the thickness was changed to 125 μm and the thickness of each layer was changed to (5 μm/100 μm/20 μm).

(Example 12)
After melt-kneading the resin composition b shown in Table 1 with an extruder set at 230°C, it is supplied to an extrusion die set at 250°C and extruded into a sheet, which is cooled to 60°C by a cooling device. An unstretched sheet was obtained. This unstretched sheet was heated to 135° C. and stretched 5 times in the machine direction by utilizing the difference in peripheral speed of the roll group to obtain a monolayer uniaxially stretched sheet. Next, the resin composition a was melt-kneaded by an extruder set at 230° C., extruded into a sheet shape, and laminated on the first surface of the monolayer uniaxially stretched sheet to obtain a two-layer laminated sheet. Next, the two-layer laminate sheet is cooled to 60°C, heated to about 150°C using a tenter oven, stretched 8.5 times in the horizontal direction, and then heated to 160°C for heat treatment. to obtain a two-layer laminated stretched sheet. Next, after melt-kneading the resin composition d with an extruder set at 230° C., it is extruded into a sheet and laminated on the surface of the layer side composed of the resin composition b of the two-layer laminated stretched sheet, and three layers are laminated. got a sheet. Then, the uniaxially stretched layer of the resin composition a is the back layer, the thickness is 140 μm, the resin composition (d/b/a) of each layer, the thickness of each layer ( 20 μm/100 μm/20 μm) and the number of stretching axes for each layer (non-stretching/biaxial/uniaxial)] to obtain a laminated resin film.

A coating liquid b was prepared using the same method as in Example 1 described above. The surface of the back layer of the laminated resin film is subjected to surface treatment by corona discharge, and the coating solution b is applied to the corona discharge-treated surface side and dried to form a coating layer having a thickness of 0.1 μm. After drying in an oven for 60 seconds, the recording paper of Example 12 was obtained.

(Example 13)
After melt-kneading the resin composition a described in Table 1 with an extruder set at 230°C, it is supplied to an extrusion die set at 250°C and extruded into a sheet, which is cooled to 60°C by a cooling device. An unstretched sheet was obtained. Next, the resin composition d was melt-kneaded in an extruder set at 230°C, extruded into a sheet and laminated on the first surface of the non-stretched sheet, and at the same time, the plastic resin composition a was set at 230°C. After melt-kneading with one extruder, the mixture was extruded into a sheet and laminated on the second surface of the unstretched sheet to obtain a three-layer laminated sheet. Next, the edge portion was slit, and the unstretched layer of the resin composition a was the back layer, the thickness was 120 μm, the resin composition (d/a/a) of each layer, and the thickness of each layer (20 μm/80 μm/20 μm). , and the number of stretching axes for each layer (unstretched/unstretched/unstretched)].

A coating liquid b was prepared using the same method as in Example 1 described above. The surface of the back layer of the laminated resin film is subjected to surface treatment by corona discharge, and the coating solution b is applied to the corona discharge-treated surface side and dried to form a coating layer having a thickness of 0.1 μm. After drying in an oven for 60 seconds, the recording paper of Example 13 was obtained.

(Comparative example 1)
After melt-kneading the resin composition b shown in Table 1 with an extruder set at 230°C, it is supplied to an extrusion die set at 250°C and extruded into a sheet, which is cooled to 60°C by a cooling device. An unstretched sheet was obtained. This unstretched sheet was heated to 135° C. and stretched 5 times in the machine direction by utilizing the difference in peripheral speed of the roll group to obtain a monolayer uniaxially stretched sheet. Next, the resin composition b was melt-kneaded by an extruder set at 230° C., extruded into a sheet shape and laminated on the first surface of the monolayer uniaxially stretched sheet to obtain a two-layer laminated sheet.
On the other hand, 55 parts by weight of water, 20 parts by weight of fine powder silica ["Mizukasil P-78F" manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size 12.5 μm] and hydrophobic resin (acrylic resin emulsion) [BASF Japan Co., Ltd. ) manufactured by Acronal YJ-2870D, solid concentration 50% by weight] were mixed and dispersed to prepare a coating solution a.
One surface of the two-layer laminated sheet obtained above was subjected to surface treatment by corona discharge, and the corona discharge-treated surface side was coated with coating liquid a and dried to form a coating layer with a thickness of 40 μm. After drying in an oven for 60 seconds, a recording paper of Comparative Example 1 having a thickness of 140 μm was obtained.

(Comparative example 2)
The resin composition 1 shown in Table 1 was kneaded and rolled for 5 minutes with two 9-inch test rolls (steam heating type manufactured by Nishimura Koki Co., Ltd.) set at 160 ° C. to obtain a vinyl chloride-based resin having a thickness of 140 µm. A resin sheet was produced (calendering). The obtained vinyl chloride resin sheet was pressed with a 37t hydraulic molding machine (manufactured by Oji Kikai Co., Ltd.) at a temperature of 170° C. with a maximum pressure of 70 kg/cm ² to mirror-finish the surface to a thickness of 140 μm. A recording paper of Comparative Example 2 was obtained.

(Comparative Example 3)
In the same manner as in Example 1, except that the resin composition b was used instead of the resin composition c for the receiving layer, and the resin composition b was used instead of the resin composition a for the substrate layer. A recording paper of Comparative Example 3 was obtained.

From the results in Tables 2 and 3, the recording papers of Examples 1 to 13, in which a receiving layer containing a styrene resin was provided on one side of the base layer made of a thermoplastic resin film, had high smoothness. and excellent glossiness, high image density, excellent ink absorption and drying properties, and does not require waterproofing or antifouling treatment even when printed matter is exposed outdoors for a long time. I found out.

On the other hand, the recording paper of Comparative Example 1, which was not provided with a receiving layer containing a styrene resin but was provided with a pigment coating layer, was excellent in ink absorption and drying properties, and was able to prevent waviness and blocking. However, the glossiness and image density are low, and the fixability of the ink is poor. Therefore, when the printed matter is exposed to the outdoors for a long period of time, water-resistant and antifouling treatment is required. In addition, the recording paper of Comparative Example 2 provided with a receiving layer containing a vinyl chloride copolymer, not provided with a receiving layer containing a styrene resin, had excellent glossiness and ink absorbency. • Although it had excellent drying property and excellent image density, the occurrence of waviness and blocking could not be prevented, and the weather resistance was poor. Furthermore, the recording paper of Comparative Example 3, which was not provided with a receiving layer containing a styrene resin but was provided with a receiving layer containing a propylene homopolymer, was inferior in ink absorption and drying properties, and solvent ink jet printing was used. It was also inferior to appropriateness.

The recording paper according to the present invention has both high smoothness and excellent glossiness, high image density, excellent ink absorption and drying properties, and is waterproof and waterproof even when printed matter is exposed outdoors for a long period of time. This recording paper does not require soiling. Therefore, the recording paper according to the present invention is very useful as a sign, label, sign, poster, advertisement, or the like.
Moreover, the recording paper according to the present invention is very useful as a recording paper for solvent inkjet using solvent-based ink.

This application claims priority based on Japanese Patent Application No. 2021-060712, which is a Japanese patent application filed on March 31, 2021, and all descriptions of the Japanese patent application are incorporated.

DESCRIPTION OF SYMBOLS 100... Recording paper, 10... Receiving layer, 20... Base material layer, 21... Core layer, 22... Back layer

Claims

A recording paper 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.
The recording paper according to claim 1, wherein the receiving layer is stretched in at least one direction.
The recording paper according to claim 1 or 2, wherein the receiving layer has a thickness of 3 µm or more.
The styrene-based resin is a copolymer of styrene-based monomer, ethylene and butadiene; a copolymer of styrene-based monomer, α-olefin and butadiene; and a styrene-based monomer, ethylene, α-olefin and butadiene. 4. The recording paper according to any one of claims 1 to 3, comprising at least one selected from the group consisting of copolymers of
The arithmetic mean roughness (Ra) according to JIS B0601:2003 of the base layer side (back layer side) surface of the recording paper is 0.2 μm or more, according to any one of claims 1 to 4. Recording paper described in .
The recording paper according to any one of claims 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.
1. The surface resistivity of the base layer side (back layer side) surface of the recording paper measured according to JIS K6911:2006 is 1×10 8 to 9×10 12 Ω. The recording paper according to any one of -6.
The recording paper according to any one of claims 1 to 7, wherein the bending resistance of the recording paper according to JIS L1096:2010 bending resistance A method (Gurley method) is 0.3 to 10 mN. .