JP6814508B2 - Thermal recording medium, its winding roll, and support for recording medium - Google Patents

Description

The present invention relates to a thermal recording medium, a winding roll thereof, and a support for a recording medium.

In various printing papers, various poster papers, and various label papers, recording media such as inkjet recording paper, heat-sensitive recording paper, heat transfer receiving paper, pressure-sensitive transfer recording paper, and electrophotographic recording paper are used. These recording media are generally required by providing a recording layer such as an ink receiving layer for an inkjet, a heat-sensitive recording layer, a heat transfer receiving layer, or a pressure-sensitive transfer layer on a base material such as paper, synthetic paper, or a plastic film. It is produced by further laminating a protective layer, an adhesive layer, a peeling layer and the like according to the above.

In recent years, there has been an increasing demand for imparting water resistance, weather resistance, or durability to these papers, and various resin films, for example, thermoplastic resin films, have come to be widely used as a base material for these recording media. (See, for example, Patent Documents 1 to 4). Among these thermoplastic resin films, for example, synthetic paper produced by the internal paper forming method is formed by blending a thermoplastic resin such as a polyolefin resin or a polyester resin with an inorganic fine powder or an organic filler and stretching the film to form a large number of voids in the film. It can be manufactured by forming it, and because of its high basic performance, it is widely used as a base film for recording media.

The various recording media described above are manufactured in the form of roll-to-roll from the viewpoint of increasing productivity, and are often conveyed and stored in the form of winding rolls. As an example, the thermal recording medium is manufactured by sequentially laminating a thermal recording layer and a protective layer on one surface of a base film. Then, the heat-sensitive recording medium thus obtained is once wound into a roll, and is conveyed, stored, or the like in the form of a winding roll. Further, in manufacturing an adhesive label for heat-sensitive recording, the heat-sensitive recording medium is pulled out again from the winding roll of the heat-sensitive recording medium, and an adhesive layer and a release layer are sequentially formed on the other surface of the base film. Laminate. Further, the heat-sensitive recording adhesive label thus obtained is wound again in a roll shape, and is transported, stored, etc. in the form of a winding roll.

When various print media are stored in the form of a winding roll in this way, contact between the front surface and the back surface of the recording medium causes, for example, electrostatic adsorption or blocking, which in turn causes scratches on the surface of the thermal recording medium. Various troubles can occur. Therefore, an attempt has been made to provide a resin layer (backcoat layer) having a predetermined thickness on the back surface of the recording medium by dispersing and blending various fillers, metal soaps, etc. as antistatic agents, lubricants, or matting agents in a resin matrix. (See, for example, Patent Documents 5 and 6).

Japanese Unexamined Patent Publication No. 4-219277 Japanese Unexamined Patent Publication No. 5-305780 Japanese Unexamined Patent Publication No. 10-119428 Japanese Unexamined Patent Publication No. 7-290654 Japanese Unexamined Patent Publication No. 2011-025652 Japanese Unexamined Patent Publication No. 2007-076254

However, for example, when the above-mentioned heat-sensitive recording medium is stored in the form of a winding roll, the wettability of the back surface side of the recording medium, that is, the exposed surface (back surface) of the base film is lowered, and the adhesive layer is formed on the exposed surface. It has been found that manufacturing troubles such as insufficient adhesion of each layer may occur in the post-process of laminating and forming the release layer and the like.

Moreover, the phenomenon of deterioration of the wettability of the exposed surface (layered surface) of the base film is not limited to the heat-sensitive recording medium described above, but also in a recording medium having a multilayer structure in which various recording layers are laminated and formed on the base film. Can occur as well.

The present invention has been made in view of such background techniques. The purpose is to provide a thermal recording medium and its winding roll, in which the deterioration of the wettability of the base film of the support for the recording medium with respect to the post-processing paint is suppressed, and the deterioration of the adhesiveness at the time of laminating each layer is suppressed. To provide. Another object of the present invention is to suppress a decrease in the wettability of the base film of the support for the recording medium with respect to the post-processing paint, thereby suppressing a decrease in the adhesiveness at the time of laminating each layer. The purpose is to provide a support for a medium.

It should be noted that the present invention is not limited to the purpose described here, and it is also an action and effect derived by each configuration shown in the embodiment for carrying out the invention described later, and the action and effect which cannot be obtained by the conventional technique can be obtained. It can be positioned as another purpose.

As a result of diligent studies to solve the above problems, the present inventors have caused the above-mentioned phenomenon of deterioration of wettability of the base film support for the recording medium to the post-processing paint, and various compounds are transferred to the base film. We have found that the above problems can be solved by using a base film that is surface-modified by nanomat particles having an average particle diameter of 5 to 800 nm and that it is caused by (adhesion). It came to be completed.

That is, the present invention provides various specific aspects shown below.
[1] A base film containing a thermoplastic resin, a heat-sensitive recording layer provided on one surface side of the base film, and a heat-sensitive recording layer provided on the surface side of the base film not facing the base film. A heat-sensitive recording medium including a protective layer, characterized in that nanomat particles having an average particle diameter of 5 to 800 nm are bonded to at least the other surface of the base film. ..
[2] The nanomat particles include at least one selected from the group consisting of inorganic nanoparticles having an average particle size of 5 to 150 nm and organic nanoparticles having an average particle size of 20 to 800 nm in the above [1]. The heat-sensitive recording medium described.
[3] The heat-sensitive recording medium according to the above [2], wherein the inorganic nanoparticles contain a metal oxide or a hydrate thereof.
[4] The heat-sensitive recording medium according to the above [2] or [3], wherein the organic nanoparticles contain thermoplastic resin particles.
[5] The nanomat particles include at least inorganic nanoparticles having an average particle size of 5 to 150 nm and organic nanoparticles having an average particle size of 20 to 800 nm, and the average particle size of the organic nanoparticles is the same. The heat-sensitive recording medium according to any one of the above [1] to [4], which is 0.1 to 160 times as much as that of inorganic nanoparticles.

[6] A winding roll in which a heat-sensitive recording medium is wound in a roll shape, and the heat-sensitive recording medium is provided on one surface side of a base film containing a thermoplastic resin and the base film. It is provided with a heat-sensitive recording layer and a protective layer provided on a surface side of the heat-sensitive recording layer that does not face the base film, and has an average particle diameter of 5 to 800 nm on at least the other surface of the base film. A winding roll characterized by the binding of nanomat particles.
Here, it is preferable that the winding roll according to the above [6] further has the technical features described in any one or all of the above [2] to [5].

[7] A support for a recording medium including at least a base film containing a thermoplastic resin, and nanomat particles having an average particle diameter of 5 to 800 nm are bound on at least one surface of the base film. A support for a recording medium, characterized in that it is used.
Here, it is preferable that the support for a recording medium according to the above [7] further has the technical features described in any one or all of the above [2] to [5].

According to the present invention, it is possible to realize a support for a recording medium having a novel structure whose surface is modified by nanomat particles. Further, by using this support for a recording medium, it is possible to realize a heat-sensitive recording medium in which a decrease in wettability of the support for the recording medium of the base film with respect to the post-processing paint is suppressed and a winding roll thereof. .. Moreover, according to the present invention, it is not necessary to provide a resin layer (backcoat layer) having a predetermined thickness as in the prior art, so that it is possible to suppress the thickening of the heat-sensitive recording medium or the like. Furthermore, the resin layer (backcoat layer) of the prior art has a large variation in wettability and surface smoothness due to the external environment (temperature, humidity, etc.) due to the resin matrix component, which is suitable for the present invention. According to the aspect, it is also possible to realize a heat-sensitive recording medium or the like in which fluctuations in wettability and surface smoothness due to an external environment (temperature, humidity, etc.) are small.

It is a schematic cross-sectional view which shows the thermal recording medium of one Embodiment. It is a schematic cross-sectional view which shows the adhesive sheet with a release sheet of one Embodiment. 6 is a surface SEM photograph showing nanomat particles of the heat-sensitive recording medium of Example 1. 3 is a surface SEM photograph showing nanomat particles of the heat-sensitive recording medium of Example 2. It is a sample of evaluation judgment of coating performance in an Example.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. It should be noted that the following embodiments are examples for explaining the present invention, and the present invention is not limited to the embodiments thereof. In the following, unless otherwise specified, the positional relationship such as up, down, left and right shall be based on the positional relationship shown in the drawings. Moreover, the dimensional ratio of the drawing is not limited to the ratio shown in the drawing. In this specification, for example, the notation of the numerical range of "1 to 100" includes both the lower limit value "1" and the upper limit value "100". The same applies to the notation of other numerical ranges.

[Thermal recording medium]
FIG. 1 is a schematic cross-sectional view showing a heat-sensitive recording medium 100 according to an embodiment of the present invention. The heat-sensitive recording medium 100 as the heat-sensitive recording paper includes the base film 11, the heat-sensitive recording layer 21 provided on the surface 11a side of the base film 11, and the surface 21a of the heat-sensitive recording layer 21 (that is, the base film 11). It is provided with a protective layer 31 provided on the side (a surface that does not face the surface). That is, the thermal recording medium 100 has a multilayer structure in which the base film 11, the thermal recording layer 21, and the protective layer 31 are laminated in this order from the lower part of the drawing. Further, nanomat particles 12 having an average particle diameter of 5 to 800 nm are bound on the back surface 11b of the base film 11. Then, in the heat-sensitive recording medium 100, heat recording is performed by applying heat from the thermal head from the protective layer 31 side. Hereinafter, each component will be described in detail.

<Base film>
The base film 11 used here supports the heat-sensitive recording layer 21 and the protective layer 31 described above, and imparts printability such as mechanical strength and elasticity to the heat-sensitive recording medium 100. As the base film 11, a known one can be used, and the type thereof is not particularly limited. For example, a non-woven fabric material made of organic fibers, inorganic fibers, or a composite material combining these; a woven fabric material using organic long fibers as warp and weft; a thermoplastic resin, a thermosetting resin, or a composite material combining these. Resin film (including synthetic paper); a paper material such as pulp paper, metal-deposited paper, or resin-laminated paper; and the like.

Among these, the base film 11 preferably has a texture similar to that of paper, and preferably has excellent water resistance. From this point of view, a water resistant film such as a resin film, synthetic paper, pulp paper, metal vapor deposition paper, or resin laminated paper is preferable.

In particular, the base film 11 is suitable from the viewpoint that mechanical strength such as rigidity and tear resistance, physical properties such as smoothness and opacity, and chemical properties such as water resistance and chemical resistance can be easily adjusted. , A resin film obtained by molding a thermoplastic resin into a sheet is more preferable. For example, polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferably used. Further, for example, synthetic paper obtained by molding a thermoplastic resin into a sheet can be easily molded into a thin film by a stretching treatment, and is excellent not only in chemical properties such as mechanical strength, water resistance and chemical resistance, but also in printability. It is easy to obtain things. When synthetic paper obtained by molding a thermoplastic resin into a sheet is used as the base film 11, any of non-stretched, uniaxially stretched, and biaxially stretched resin films can be used.

Specific examples of the above thermoplastic resin include ethylene-based resins (high-density polyethylene, medium-density polyethylene, low-density polyethylene, etc.), propylene-based resins, polymethyl-1-pentene, ethylene-cyclic olefin copolymers, and other polyolefin-based resins. Resin; ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salt (ionomer) of ethylene-methacrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, Functional group-containing polyolefin resins such as ethylene-methacrylic acid alkyl ester copolymer, maleic acid-modified polyethylene, maleic acid-modified polypropylene; nylon-6, nylon-6,6, nylon-6,10, nylon-6,12, etc. Polyamide-based resin; thermoplastic polyester-based resin such as aromatic polyester (polyethylene terephthalate and its copolymer, polyethylene naphthalate, polybutylene terephthalate, etc.), aliphatic polyester (polybutylene succinate, polylactic acid, etc.); aromatic Polycarbonate resin such as polycarbonate and aliphatic polycarbonate; polystyrene-based resin such as atactic polystyrene, syndiotactic polystyrene, acrylonitrile-styrene (AS) copolymer, acrylonitrile-butadiene-styrene (ABS) copolymer; polyvinyl chloride resin ; Polyphenylene sulfide; and the like. These can be used alone or in combination of two or more.

Among these, from the viewpoints of mechanical strength, physical properties, chemical properties, productivity, etc. described above, polyolefin resins such as high-density polyethylene and propylene resin, functional machine-containing polyolefin resins, polyethylene terephthalate and the like are used. Polyester resin is preferable. In particular, from the viewpoint of excellent balance of various physical properties described above, high-density polyethylene, propylene-based resin, propylene-based resin and high-density or low-density polyethylene are more preferable, and propylene-based resin and propylene-based resin are high-density or low. A mixture with density polyethylene is even more preferred. In particular, as the base film 11, a uniaxially or biaxially stretched polyolefin-based resin film is preferable.

Further, the base film 11 is preferably a porous resin film having a large number of fine pores (foam cells, voids, etc.) inside. More specifically, as the base film 11, a uniaxially or biaxially stretched porous polyolefin resin film is more preferable. The pores inside the base film 11 can be formed by, for example, a foaming method, an internal paper forming method, a solvent extraction method, or the like. Further, as a preferable method for producing the porous resin film, an internal paper forming method can be mentioned. In this internal paper-making method, a resin composition obtained by mixing a thermoplastic resin and an inorganic filler or an organic filler which is a core of pore formation is formed into a sheet by a known method, and the obtained sheet is uniaxially or biaxially formed. By axially stretching, a large number of fine pores are formed inside. As a result, the porous resin film can be whitened, opaque, and lightened. Hereinafter, as the porous resin film, synthetic paper produced by the internal paper forming method will be taken as an example and will be described in more detail.

(Synthetic paper)
Synthetic paper produced by the internal paper forming method contains at least a thermoplastic resin and an inorganic filler or an organic filler that can be the core of pore formation. The synthetic paper may be composed of only a single layer or may be a laminated body in which a plurality of layers are laminated. Further, when the synthetic paper is made of a laminated body, the pores may be formed in only one layer, in a plurality of layers, or in all layers. As a specific example of the laminated body of synthetic paper, a biaxially stretched thermoplastic resin layer containing an inorganic filler or an organic filler is used as a base material layer, and a uniaxially stretched thermoplastic resin layer containing an inorganic filler or an organic filler on at least one surface thereof. An example is one in which a thermoplastic resin layer is laminated as a paper-like layer.

Specific examples of the thermoplastic resin contained in the synthetic paper are as described above, and duplicate description thereof will be omitted here. Particularly preferably used propylene-based resins include, for example, isotactic to syndiotactic and propylene homopolymers exhibiting various degrees of stereoregularity (homopolypropylene); propylene as a main component, ethylene, 1-. Polymers with α-olefins such as butene, 1-hexene, 1-heptene, 4-methyl-1-pentene; and the like. This copolymer may be a binary system in which the monomer component is a binary system or a plural system having a ternary system or more, and may be a random copolymer or a block copolymer. Further, it is particularly preferable to use a propylene-based resin mixed with 2 to 25% by mass of a resin having a melting point lower than that of the propylene homopolymer. As such a resin having a low melting point, high-density or low-density polyethylene can be exemplified.

The content ratio of the thermoplastic resin to the total amount of the synthetic paper is not particularly limited, but is preferably 25 to 100% by mass, more preferably 25 to 95% by mass, and further preferably 35 to 35% by mass in terms of solid content. It is 92% by mass, particularly preferably 45 to 90% by mass. By setting the above-mentioned preferable range, it tends to be easy to obtain suitable mechanical strength, water resistance and the like.

As described above, the synthetic paper may contain an inorganic filler that can be a core of pore formation. By containing an inorganic filler, the synthetic paper can be whitened or opaque. As a result, the visibility of printing can be improved, and the printing medium can be made more suitable.

Examples of the inorganic filler include heavy calcium carbonate, light calcium carbonate, calcined clay, talc, diatomaceous earth, titanium oxide, barium sulfate, alumina, silica, zinc oxide, magnesium oxide, white clay, zeolite, mica, sericite, bentonite, etc. Examples thereof include sepiolite, vermiculite, dolomite, wallastonite, glass fiber, hollow glass beads and the like, but the present invention is not particularly limited thereto. Among these, heavy calcium carbonate, light calcium carbonate, calcined clay, and talc are preferable, and heavier calcium carbonate is more preferable, from the viewpoint of pore moldability and cost.

From the viewpoint of enhancing dispersibility, the inorganic filler may be surface-treated, if necessary. The surface treatment method for the inorganic filler is not particularly limited. For example, JP-A-5-43815, JP-A-5-139728, JP-A-7-300568, JP-A-10-176079, JP-A-11-256144, JP-A-11-349846, The methods described in JP-A-2001-158863, JP-A-2002-220547, JP-A-2002-363443, and JP-A-2010-66512 are known.

Higher fatty acids, polymer surfactants and the like are known as surface treatment agents for inorganic fillers, but surface treatment agents known in the art can be appropriately selected and used according to required performance. Examples of the surface treatment agent for the inorganic filler include fatty acids, organic acids, sulfate ester-type anionic surfactants, sulfonic acid-type anionic surfactants, resin acids or petroleum resin acids, or salts thereof (for example, sodium salts and potassium salts). Alkali metal salts, ammonium salts, etc.), antistatic agents, diene polymers, nonionic surfactants, inert inorganic oxides such as aluminum oxides or hydroxides, titanate coupling agents, silanes Coupling agents, phosphoric acid-based coupling agents, fatty acid esters, resin acid esters, waxes, paraffins and the like can be mentioned, but are not particularly limited thereto. These can be used alone or in combination of two or more.

Examples of fatty acids include caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, and eleostearic acid. can do. Examples of the organic acid include maleic acid and sorbic acid.

Examples of the sulfate ester type anionic surfactant include long-chain alcohol sulfate ester, polyoxyethylene alkyl ether sulfate ester, sulfated oil, and salts thereof. Examples of the sulfonic acid type anionic surfactant include alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, paraffin sulfonic acid, α-olefin sulfonic acid, alkylsulfosuccinic acid, and salts thereof.

Examples of the diene polymer include polybutadiene and polyisoprene. Examples of the nonionic surfactant include polyethylene glycol ester-type surfactants and the like. Examples of the inert inorganic oxide include alumina and silica.

As described above, the synthetic paper may contain an organic filler that can be a core of pore formation. By containing an organic filler, synthetic paper can be whitened or opaque. As a result, the visibility of printing can be improved, and the printing medium can be made more suitable.

The organic filler used here is a resin of a type different from the above-mentioned thermoplastic resin which is a constituent base material of synthetic paper, and its melting point or glass transition point is the melting point or melting point of the thermoplastic resin which constitutes synthetic paper. The resin is preferably higher than the glass transition point. When such an organic filler is used, the incompatibility of the constituent base material of the synthetic paper with respect to the thermoplastic resin can be enhanced, and the porosity forming property at the time of stretch molding can be improved.

For example, when a propylene-based resin is used as a thermoplastic resin as a constituent base material of synthetic paper, preferable organic fillers are polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyamide, polycarbonate, polystyrene, and cyclic olefin homopolymer. , Ethylene-cyclic olefin copolymer, polyimide, polymethacrylate, polyethyl ether ketone, polyethylene sulfide, polyphenylene sulfide, melamine resin particles, which have a melting point higher than the melting point of the propylene-based resin of the constituent base material (for example, 170 to 300 ° C.). ) Or a glass transition temperature (for example, 170 to 280 ° C.) and incompatible with the propylene-based resin of the constituent base material can be exemplified.

The average particle size of the inorganic filler and the average particle size of the organic filler may be appropriately set according to the desired performance, and are not particularly limited. From the viewpoint of stable film stretching and uniform pore formation, 0.1 to 15 μm is preferable, 0.2 to 8 μm is more preferable, and 0.5 to 4 μm is more preferable. When the average particle size of the inorganic filler and the organic filler is 0.1 μm or more, pores are likely to be obtained during stretch molding, and opacity tends to be easily achieved. On the other hand, when the average particle size of the inorganic filler and the organic filler is 15 μm or less, the mechanical strength tends to be difficult to decrease.

The average particle size of the inorganic filler and the organic filler means the so-called median diameter D ₅₀ obtained by the laser diffraction / scattering method. This average particle size can be measured by a known laser diffraction / scattering particle size distribution measuring device such as a laser diffraction type particle measuring device "Microtrack" (manufactured by Nikkiso Co., Ltd., trade name).

The synthetic paper may contain one kind of inorganic filler alone or a combination of two or more kinds of inorganic fillers. Further, the synthetic paper may contain one kind of organic filler alone or a combination of two or more kinds of organic fillers. Further, the synthetic paper may contain a combination of one type of inorganic filler and one or more types of organic filler.

When the synthetic paper contains at least one of the inorganic filler and the organic filler, the blending ratio of the total amount of the inorganic filler and the organic filler to the total amount of the synthetic paper (sometimes referred to as the addition amount of the inorganic filler and the organic filler) is particularly high. Although not limited, it is preferably 5 to 75% by mass, more preferably 8 to 65% by mass, and further preferably 10 to 55% by mass in terms of solid content. By setting the above-mentioned preferable range, pores are easily obtained during stretch molding, and opacity tends to be easily achieved. In addition, it tends to be easy to obtain suitable mechanical strength and water resistance.

In addition to the above three components (thermoplastic resin, inorganic filler and organic filler), synthetic paper is a slip agent such as a heat stabilizer (antioxidant), a light stabilizer, an ultraviolet absorber, a dispersant, a lubricant, and a fatty acid amide. , Antiblocking agents, kneaded antistatic agents, dyes, pigments, plasticizers, crystal nucleating agents, mold release agents, flame retardants and other known additives. When the thermal recording medium 100 is used outdoors, for example, as poster paper, it is preferable to add an antioxidant, a light stabilizer, or the like from the viewpoint of improving durability.

Examples of the heat stabilizer include heat stabilizers such as steric hindrance phenolic antioxidants, phosphorus-based antioxidants, and amine-based antioxidants. The amount of the heat stabilizer added is not particularly limited, but is preferably 0.001 to 1% by mass in terms of solid content with respect to the above-mentioned thermoplastic resin.

Examples of the light stabilizer include a sterically hindered amine-based light stabilizer, a benzotriazole-based light stabilizer, a benzophenone-based light stabilizer, and a sulfur-based light stabilizer. The amount of the light stabilizer added is not particularly limited, but is preferably 0.001 to 1% by mass in terms of solid content with respect to the above-mentioned thermoplastic resin.

The dispersant is used, for example, for the purpose of highly dispersing the inorganic filler in the film layer containing the above-mentioned thermoplastic resin. Examples of the dispersant include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid or polymethacrylic acid, or salts thereof. The amount of the dispersant added is not particularly limited, but is preferably 0.01 to 4% by mass in terms of solid content with respect to the above-mentioned thermoplastic resin.

(Synthetic paper molding method)
The method for molding synthetic paper containing a thermoplastic resin is not particularly limited. For example, various known moldings such as cast molding, calendar molding, rolling molding, inflation molding, etc., which extrude a molten thermoplastic resin into a sheet using a single-layer or multi-layer T-die or I-die connected to a screw type extruder. Depending on the molding method, synthetic paper containing a thermoplastic resin can be molded. Further, a synthetic paper containing a thermoplastic resin can also be molded by using a method of casting or calendering a mixture of a thermoplastic resin and an organic solvent or oil and then removing the solvent or oil.

The synthetic paper may have a single-layer structure or a multi-layer structure having two or more layers. As a method for forming the synthetic paper into a multilayer structure, various conventionally known methods can be used and are not particularly limited. For example, a feed block, a multi-layer die method using a multi-manifold, an extrusion lamination method using a plurality of dies, and the like can be mentioned. It is also possible to use a combination of multi-layer dies and extrusion lamination.

As the base film 11 of the thermal recording medium 100, one of the preferable modes of synthetic paper is a multilayer structure in which desired characteristics are imparted to each layer. For example, synthetic paper has a three-layer structure of surface layer / base layer / surface layer, and the base layer is provided with rigidity, opacity, light weight, etc. suitable for a thermal recording medium, and one surface layer has a surface structure suitable for providing a thermal recording layer 21. The other surface layer has a surface structure suitable for binding the nanomat particles 12, so that a suitable heat-sensitive recording medium 100 can be obtained. Further, by appropriately designing the composition and thickness of one surface layer and the other surface layer, it becomes easy to control the curl within a specific range. Further, the synthetic paper has a multi-layer structure, and a concealing layer such as a solid printing layer or a pigment-containing layer is contained therein to impart high opacity to the thermal recording medium 100, so that when used for poster paper or the like, one side is used. It is possible to prevent the print from being seen through from the back surface, and it is also possible to improve the visibility of individual prints provided on both sides.

As a method for stretching and molding synthetic paper, various conventionally known methods can be used and are not particularly limited. For example, longitudinal stretching using the peripheral speed difference of the roll group, lateral stretching using a tenter oven, rolling, simultaneous biaxial stretching by a combination of a tenter oven and a linear motor, simultaneous biaxial stretching by a combination of a tenter and a pantograph, or These combinations can be used for stretching. Further, as a method for stretching and molding an inflation film, a simultaneous biaxial stretching method by a tubular method can also be used.

The draw ratio when the synthetic paper is stretch-molded is not particularly limited, and may be appropriately determined in consideration of the characteristics of the thermoplastic resin to be used and the like. For example, when a homopolymer of propylene or a copolymer thereof is used as the thermoplastic resin and the resin is stretched in the uniaxial direction, the stretching ratio is preferably about 1.2 to 12 times, more preferably 2 to 10 times. When stretching in the biaxial direction, the stretching ratio is preferably 1.5 to 60 times, more preferably 10 to 50 times in terms of area magnification. When high-density polyethylene or polyethylene terephthalate is used as the thermoplastic resin and the resin is stretched in the uniaxial direction, the draw ratio is preferably about 1.2 to 10 times, more preferably 2 to 5 times, and in the biaxial direction. In the case of stretching, the stretching ratio is preferably 1.5 to 20 times, more preferably 4 to 12 times in terms of area ratio. By setting the above-mentioned preferable range, stable stretch molding can be performed, desired pores can be easily obtained, and lightness and opacity tend to be improved.

The stretching temperature at the time of stretching and molding the synthetic paper is not particularly limited, but it is preferably carried out within a temperature range suitable for stretching the thermoplastic resin as the constituent base material. For example, when the thermoplastic resin is a non-crystalline resin, the stretching temperature is preferably equal to or higher than the glass transition temperature of the thermoplastic resin. When the thermoplastic resin is a crystalline resin, the stretching temperature is preferably equal to or higher than the glass transition point of the non-crystalline portion of the same thermoplastic resin and lower than the melting point of the crystalline portion of the same thermoplastic resin. .. Generally, the stretching temperature of synthetic paper is preferably 2 to 60 ° C. lower than the melting point of the thermoplastic resin used.

More specifically, when the thermoplastic resin is a homopolymer of propylene (melting point 155 to 167 ° C.), the stretching temperature is preferably 100 to 165 ° C. When the thermoplastic resin is high-density polyethylene (melting point 121 to 136 ° C.), the stretching temperature is preferably 70 to 134 ° C. Further, when the thermoplastic resin is polyethylene terephthalate (melting point 246 to 252 ° C.), the stretching temperature is preferably 104 to 115 ° C. After the stretching treatment, heat treatment at a temperature higher than the above stretching temperature may be performed, if necessary.

The stretching speed when the synthetic paper is stretch-molded is not particularly limited, but is preferably 20 to 350 m / min from the viewpoint of stable stretch molding and productivity.

When the synthetic paper is composed of a plurality of layers, it is preferable that at least one layer is stretched. When a plurality of layers are stretched, they may be stretched individually before laminating each layer, or may be stretched together after laminating each layer. Further, the stretched layer may be stretched again after laminating. One of the preferred methods for producing synthetic paper includes a step of laminating a plurality of layers constituting the synthetic paper and then stretching them together. Compared to the case of separately stretching and laminating, it tends to be simple and the manufacturing cost is low.

When the synthetic paper is composed of a plurality of layers, the number of stretch axes of each layer constituting the synthetic paper may be unstretched or unstretched, uniaxially stretched, or biaxially stretched. For example, when synthetic paper has a three-layer structure of surface layer / base layer / surface layer, the number of stretch axes of each layer is non-stretched / non-stretched / non-stretched, non-stretched / uniaxial / non-stretched, non-stretched / biaxial / non-stretched. Unstretched / uniaxial / uniaxial, unstretched / uniaxial / biaxial, unstretched / biaxial / uniaxial, unstretched / biaxial / biaxial, uniaxial / uniaxial / uniaxial, uniaxial / uniaxial / biaxial, uniaxial / biaxial / It can be arbitrarily combined with one axis, one axis / two axes / two axes, two axes / two axes / two axes, and the like.

When the synthetic paper has holes inside, it is easy to impart opacity and lightness as described above. The ratio of pores to the synthetic paper can be expressed by the pore ratio. The porosity of the synthetic paper is preferably 10% or more, more preferably 12% or more, still more preferably 15% or more, and particularly preferably 20% or more, from the viewpoint of obtaining opacity. On the other hand, the porosity of the synthetic paper is preferably 45% or less, more preferably 44% or less, still more preferably 42% or less, and particularly preferably 40% or less, from the viewpoint of maintaining mechanical strength. ..

The method for measuring the pore ratio of synthetic paper is based on the assumption that the pores are evenly distributed in the synthetic paper, and the cut surface of the synthetic paper is observed with an electron microscope, and the ratio of the area occupied by the pores in the observation area is used. You can ask. Specifically, an arbitrary part of the synthetic paper sample is cut out, embedded in an epoxy resin and solidified, and then a cut surface perpendicular to the surface direction of the synthetic paper is prepared using a microscope, and the cut surface is observed. Attach it to the observation sample table so that it becomes a surface, deposit gold or gold-palladium, etc. on the observation surface, and cut at an arbitrary magnification (for example, 500 to 3000 times magnification) that is easy to observe with an electron microscope. It is possible to observe the pores on the surface, capture the observed region as image data, perform image processing on the image with an image analyzer, obtain the area ratio of the pore portion, and obtain the pore ratio. In this case, the vacancy rate can be the average of the measured values at any of 10 or more observation points.

Such synthetic papers are described in, for example, Japanese Patent Application Laid-Open No. 46-40794, Japanese Patent Application Laid-Open No. 57-149363, Japanese Patent Application Laid-Open No. 57-181829 and the like. In addition, a commercially available product (trade name: Yupo) of Yupo Corporation can be used.

(Thickness of base film)
The thickness of the base film 11 is an element that affects the mechanical strength (for example, rigidity, tear strength, etc.) and weight of the heat-sensitive recording medium 100. The thickness of the base film 11 can be measured according to JIS P8118. The thickness of the base film 11 may be appropriately set according to the material used, the application, and the desired performance, and is not particularly limited. For example, in the case of synthetic paper, the thickness is preferably 20 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more. If the thickness of the synthetic paper is 20 μm or more, sufficient mechanical strength tends to be easily obtained even when it is posted outdoors as a large printed matter. On the other hand, the thickness of the synthetic paper is preferably 500 μm or less, more preferably 400 μm or less, still more preferably 300 μm or less. When the thickness of the synthetic paper is 500 μm or less, the thermal recording medium 100 does not become too heavy and tends to be easy to handle.

(Surface treatment of base film)
Before the heat-sensitive recording layer 21 (and the protective layer 31) is provided on the surface of the base film 11 to form the heat-sensitive recording medium 100, the surface 11a of the base film 11 may be surface-oxidized to modify the surface. preferable. By performing the surface oxidation treatment, the adhesion between the base film 11 and the heat-sensitive recording layer 21 can be further improved.

Examples of the surface oxidation treatment include corona discharge treatment, frame treatment, plasma treatment, glow discharge treatment, ozone treatment and the like. These can be performed individually by 1 type or in combination of 2 or more types. When the surface oxidation treatment is carried out, it is preferable to carry out the corona discharge treatment or the frame treatment because of its high effect.

When the corona discharge treatment is carried out, the treatment amount is not particularly limited, but 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, preferably 12,000 J / m ² (200 W / min / m ² ) or less, and more preferably 10,800 J / m ² (180 W / min / m ² ) or less. When performing frame processing, the processing amount is not particularly limited, preferably 8,000J / ^{m 2} or more, more preferably 20,000J / ^{m 2} or more, and preferably 200,000 J / ^{m 2} Below, it is more preferably 100,000 J / m ² or less.

<Nanomat particles>
A large number of nanomat particles 12 are separated from each other and bonded in an island shape on at least the back surface 11b of the base film 11. The average particle size of the nanomat particles 12 is 5 to 800 nm, and the base film 11 and the nanomat particles 12 constitute a support 101 for a recording medium. Here, a support 101 for a recording medium in which a large number of nanomat particles 12 are bonded on the base film 11 is used as a recording medium, and a recording layer provided on the support 101 is used as a recording medium. In particular, the recording layer is a thermal recording layer. The heat-sensitive recording medium 100 is a medium 21 and a protective layer 31 in which a large number of nanomat particles 12 are bonded to the surface of the base film 11 on the side where the recording layer is not provided. By binding a large number of nano-order nanomat particles 12 to the base film 11, the back surface 11b of the base film 11 is modified into an ultrafine uneven shape that could not be achieved by the prior art. It becomes. The nanomat particles 12 provided so as to project outward from the back surface 11b of the base film 11 function as a so-called spacer member, and are in direct contact (face contact) from the outside with respect to the back surface 11b of the base film 11. ), And reduces the contact area with other recording media, interleaving paper, etc. Therefore, it becomes difficult for a compound or the like from the outside to adhere to or be transferred to the back surface 11b of the base film 11, thereby suppressing a decrease in the wettability of the back surface 11b of the base film 11. Here, the average particle size of the nanomat particles 12 is preferably 8 to 720 nm from the viewpoint of maintaining good wettability, weather resistance, etc. of the back surface 11b of the base film 11 in addition to the function as a spacer member. Yes, more preferably 10 to 100 nm. In the present embodiment, an example in which the nanomat particles 12 are provided only on the back surface 11b of the base film 11, but the nanomat particles 12 are provided on both sides of the base film 11, that is, on the front surface 11a and the back surface 11b. It may have been. In this case, at least a part of the recording layer such as the thermal recording layer 21 is provided on the base film 11 via the nanomat particles.

Further, as described above, since the surface contact of the base film 11 with respect to the back surface 11b from the outside is inhibited, the nanomat particles 12 not only have a function of suppressing a decrease in wettability of the exposed surface (back surface), but also. It has a scratch resistance function, an anti-blocking function, an antistatic function, and an antifouling function. On the other hand, when other functional layers such as a resin layer and an adhesive layer are laminated and formed on the back surface 11b of the base film 11, the other functional layers are sufficiently adhered to the back surface 11b of the base film 11. By doing so, it is possible to exert an anchoring effect due to the uneven shape of the nanomat particles 12, so that the nanomat particles 12 also have an anchoring agent function of improving the adhesion to each layer to be laminated.

The constituent material of the nanomat particles 12 is not particularly limited. This is because the deterioration of the wettability of the back surface 11b of the base film 11 can be suppressed by the above-mentioned modification to the ultrafine uneven shape. Specific examples of the constituent materials of the nanomat particles 12 include inorganic materials such as metals, alloys, metal oxides or hydrates thereof; organic materials such as thermoplastic resins and thermosetting resins; and inorganic-organic composites which are hybrids thereof. Materials and the like can be mentioned.

Among these, when the base film 11 is a synthetic paper containing a thermoplastic resin, it is easy to stably obtain good binding properties of the base film 11 to the back surface 11b and the above-mentioned nano size. From the above viewpoints, the inorganic material is preferably a metal oxide or a hydrate thereof, and the organic material is preferably a thermoplastic resin.
Examples of the metal oxide or its hydrate as a constituent material of the nanomat particles 12 include, but are not limited to, silica, colloidal silica, silica sol, alumina, alumina sol, titania, titania sol, zirconia, zirconia sol and the like. Further, as the thermoplastic resin as a constituent material of the nanomat particles 12, a polyolefin resin such as an ethylene resin, a propylene resin, a polymethyl-1-pentene, or an ethylene-cyclic olefin copolymer; an ethylene-vinyl acetate copolymer; , Ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, metal salt (ionomer) of ethylene-methacrylic acid copolymer, ethylene-acrylic acid alkyl ester copolymer, ethylene-methacrylic acid alkyl ester copolymer , Maleic acid-modified polyethylene, maleic acid-modified polypropylene and other functional group-containing polyolefin resins; Nylon-6, Nylon-6,6, Nylon-6,10, Nylon-6,12 and other polyamide-based resins; Thermoplastic polyester-based resins such as polyethylene terephthalate and its copolymers, polyethylene naphthalate, polybutylene terephthalate, etc.), aliphatic polyesters (polybutylene succinate, polylactic acid, etc.); polycarbonate resins such as aromatic polycarbonate and aliphatic polycarbonate. Polystyrene-based resins such as atactic polystyrene, syndiotactic polystyrene, acrylonitrile-styrene (AS) copolymer, acrylonitrile-butadiene-styrene (ABS) copolymer; polyurethane-based resin; polyvinyl chloride resin; polyphenylene sulfide, etc. Can be mentioned. Among these, (meth) acrylic acid-based copolymers such as acrylic acid ester-based copolymers and ethylene-methacrylic acid copolymers, and polyurethane-based resins such as polyester polyurethane resins and polycarbonate polyurethane resins are preferable. As the nanoparticles made of thermoplastic resin, various commercially available products such as dispersions and emulsions can be obtained.

The nanomat particles 12 may be used alone or in combination of two or more. In particular, from the viewpoint of controlling wettability, it is preferable to use inorganic nanoparticles having an average particle size of 5 to 150 nm and organic nanoparticles having an average particle size of 20 to 800 nm in combination. More preferably, it is a combination of inorganic nanoparticles having an average particle size of 8 to 120 nm and organic nanoparticles containing a thermoplastic resin having an average particle size of 50 to 720 nm. The nanomat particles 12 may be a combination of inorganic nanoparticles having an average particle diameter of 10 to 120 nm and organic nanoparticles containing a thermoplastic resin having an average particle diameter of 50 to 100 nm. At this time, from the viewpoint of achieving both the properties of the organic nanoparticles and the properties of the inorganic nanoparticles, the average particle size of the organic nanoparticles is preferably 0.1 to 160 times that of the inorganic nanoparticles, which is more preferable. Is 0.4 to 90 times, more preferably 0.7 to 20 times.

The coating amount of the nanomat particles 12 can be appropriately set according to the required performance and is not particularly limited, but is preferably 0.001 to 0.03 g / m ² , and more preferably 0.002 to 0.025 g / m ^2. It is m ² . As described above, even with such a small amount of coating, it is possible to exhibit the function of suppressing deterioration of wettability, the function of preventing scratch resistance, the anti-blocking function, the antistatic function, the antifouling function, the anchoring agent function, and the like. it can. Although it depends on the type of nanomat particles 12 used, when the coating amount is 0.03 g / m ² or more, the nanomat particles 12 are bonded to each other to form a thin film that substantially completely covers the back surface 11b of the base film 11. It is easy, and when the nanomat particles 12 are bound in a thin film form in this way, direct contact (surface contact) is likely to occur from the outside, and the function of reducing the contact area with other recording media, interleaving paper, etc. may be weakened. ..

The bound state of the nanomat particles 12 is not particularly limited, and even if the particles of the single nanomat particles 12 are scattered in an island shape, the plurality of nanomat particles 12 are aggregated and the secondary particles It may be scattered in an island shape in the state, or it may be in a mixed state. From the viewpoint of suppressing the thickening of the heat-sensitive recording medium 100 and enhancing the economic efficiency, it is preferable that the nanomat particles 12 are bonded to the back surface 11b of the base film 11 with a thickness of 5 to 800 nm.

The arrangement of the nanomat particles 12 on the back surface 11b of the base film 11 is not particularly limited and may be randomly arranged without any regularity, but has a certain regularity as in the staggered arrangement. It may be held and arranged.

Here, when the nanomat particles 12 are bound onto the back surface 11b of the base film 11, from the viewpoints of moisture resistance, chemical resistance, improvement of the binding properties of the nanoparticles, etc., a water resistant agent, a cross-linking agent, or the like is used. Three components may be used. In a preferred embodiment, the nanomat particles 12 are bonded to the back surface 11b of the base film 11 substantially without a resin binder. In this way, the resin binder-less mode not only enhances economic efficiency, but also makes the heat-sensitive recording medium 100 thinner, and further depends on the external environment (temperature, humidity, etc.) caused by the resin binder component. Performance fluctuations such as wettability and surface smoothness can be reduced. Here, the substantially resin binderless, abundance of the resin binder after drying means that a 0~0.03g / ^{m 2,} more preferably 0~0.01g / ^{m 2,} More preferably, it is 0 to 0.005 g / m ² .

<Thermal recording layer>
As the heat-sensitive recording layer 21, known heat-sensitive recording layers such as a direct heat-sensitive recording method, a thermal transfer recording method, and a sublimation recording method can be used, and are not particularly limited. Among these, the direct thermal recording layer is preferable. Hereinafter, this direct thermal recording layer will be described in detail.

The direct heat-sensitive recording layer used here includes an electron-donating compound (hereinafter, also referred to as “color former”) such as leuco dye, which is itself a colorless or light-colored dye precursor, and an electron-accepting compound (hereinafter, “revealing agent”). It also contains at least "coloring agent"), and develops color when the coloring agent reacts with the developing agent by heat energy. The combination of the color former and the color developer is not particularly limited as long as it is a combination that causes a color reaction when they come into contact with each other. For example, a combination of a colorless to pale white basic dye and an inorganic or organic acidic substance, a combination of a higher fatty acid metal salt such as ferric stearate and a phenol such as gallic acid, a diazonium salt compound and a coupler and a basic substance. The combination with and the like can be mentioned. This diazonium salt compound may be contained in microcapsules having a polyurea, urethane or gelatin shell.

As the leuco dye, those applied to this kind of recording material are arbitrarily applied, for example, triphenylmethanephthalide type, triarylmethane type, fluorane type, phenothidian type, thioferolane type, xanthene type, indophthalyl type. , Spiropyran type, Azaphthalide type, Chromenopyrazole type, Methine type, Rhodamine anilinolactum type, Rhodamine lactam type, Kinazoline type, Diazaxanthene type, Bislactone type and other leuco compounds are preferably used. These can be performed individually by 1 type or in combination of 2 or more types.

Specific examples of the leuco dye include 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, and 3,3-bis. (P-Dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino- 6-Chlorfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3- (N-methyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-) N-isobutylamino) -6-methyl-7-anilinofluorane, 3- (N-p-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-) N-amylamino) -6-methyl-7-anilinofluorane, 3- (N, N-di-n-amylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-) Cyclohexylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-iso-propylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-) Tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorine, 3 -Diethylamino-6-methyl-7-chlorofluorine, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (m-trichloroanilino) fluorane, 3-diethylamino- 7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-ani Renofluorane, 3-diethylamino-6-methyl-7- (2', 4'-dimethylanilino) fluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzyl) Amino) Fluolan, Benoxyl Leukomethylene Blue 6'-Chloro-8'-Methylbenzoindolinospyropyrane, 6'-Bromo-8'-Methylbenzoindolinospyropyrane, 3- (2'-Hydroxy-4'-dimethylaminophenyl) -3- (2) '-Methyl-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy -4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4' -Chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyltrifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro -7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) ) Fluolane, 3- (N-ethyl-N-p-toluizino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylethylfluorane, 3-diethylamino-5- Methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piberidinoaminofluorane, 2-chloro-3- (N-methyltoluidino) -7- (p-N-butylanilino) fluorane, 3 , 6-Bis (Dimethylamino) Fluolenspyro (9,3') -6'-Dimethylaminophthalide, 3- (N-ethyl-N-Cyclohexylamino) -5,6-Benzo-7-α-naphthylamino -4'-Bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-ethyl-N-2-ethoxypropylamino) -6-methyl-7-anilinofluorane, 3- (N-Ethyl-N-Tetrafurfurylamino) -6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-methidino-4', 5'-benzofluorine, 3- (P-Dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) p-Dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-phenylethylene-2-) Il) Futari Do, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino -2'-methoxy) -3- (1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3- (4'-dimethylamino-" 2'-benzyloxy) -3- (1 "-p-dimethylaminophenyl-1" -phenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluorene -9-Spiro-3'(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5,6,7 -Tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromophthalide, bis (p-dimethylaminostyryl) ) -1-Naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like, but are not particularly limited thereto.

As the color developer, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof are preferably used. These can be performed individually by 1 type or in combination of 2 or more types.

Specific examples of the developer include 4,4'-isopropyridene diphenol, 4,4'-isopropyridenebis-o-methylphenol, 4,4'-sec-butylidenebisphenol, 4,4'. -Isopropyridenebis (2-tert-butylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2 -(3,4'-Dihydroxyphenyl) propanbis (4-hydroxy-3-methylphenyl) sulfide, 4- (β- (p-methoxyphenoxy) ethoxy) salicylic acid, 1,7-bis (4-hydroxyphenylthio) ) -3,5-Dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, phthalic acid monobenzyl ester monocalcium salt, 4,4'-cyclohexylidenediphenol, 4,4 '-Isopropyridenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2-methylphenol), 1 , 1,3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2-methylphenol), 4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfonedo, isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, Stearyl Phenolate, Lauryl Phenolate, Octyl Phenolate, 1,3-bis (4-Hydroxyphenylthio) Propane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) Thiourea, Salicyl Anilide, bis- (4-hydroxyphenyl) methyl acetate, bis (4-hydroxyphenyl) benzyl acetate, 1,3-bis (4-hydroxyphenyl) benzene, 1,4-bis (4-hydroxyphenyl) benzene, 2 , 4'-diphenol sulfone, 2,2'-diallyl-4,4'-hydroxyphenyl sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, 1-acetyloxy-2-naphthoate zinc, 2- Zinc Acetyloxy-3-naphthoethane, 2-Acetyloxy-1-naphtho Zinc ate, α, α-bis (4-hydroxyphenyl) α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol), Examples thereof include 4,4'-thiobis (2-chlorophenol), but the present invention is not particularly limited thereto.

The thermal recording layer 21 may further contain a sensitizer. As the sensitizer, conventionally known ones can be used. Specifically, for example, fatty acids such as stearic acid and bechenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, and fatty acids such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate. Examples thereof include metal salts, p-benzylbiphenyl, tarphenyl, triphenylmethane, benzyl p-benzyloxybenzoate and the like, but the present invention is not particularly limited thereto. Further, the heat-sensitive recording layer 21 may further contain various additives such as a binder, a color-developing agent, a fluorescent whitening agent, a lubricant, and a curing agent, if necessary.

The coating amount of the heat-sensitive recording layer 21 can be appropriately set according to the required performance and is not particularly limited, but the solid content after drying is preferably ² to ²⁰ g / m ² , and more preferably 3 to 15 g / m. It is ² .

<Protective layer>
The protective layer 31 protects the above-mentioned heat-sensitive recording layer 21 from the external environment, suppresses a decrease in color development, and is provided to improve wear resistance to the thermal head and high-temperature transportability. As the protective layer 31, those known in the art can be used and are not particularly limited. Generally, the protective layer 31 containing a water-soluble polymer is preferably used.

Examples of the water-soluble polymer used for the protective layer 31 include polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose and carboxymethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, and styrene-maleic anhydride copolymer alkali. Examples thereof include salts, isobutylene-maleic anhydride copolymer alkaline salts, polyacrylamide, gelatin, casein and the like, but the present invention is not particularly limited thereto. These can be performed individually by 1 type or in combination of 2 or more types. Among these, polyvinyl alcohol is preferable, and specific examples thereof include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol. Be done. A water resistant agent can also be used in combination to increase the water resistance of the protective layer 31. Specific examples of the water resistant agent include, but are not limited to, glyoxal, melamine-formaldehyde resin, polyamide resin, polyamide-epicchlorohydrin resin and the like.

The content (usage amount) of the water-soluble polymer such as polyvinyl alcohol is not particularly limited. It may be appropriately blended according to the above-mentioned various performances.

Further, the protective layer 31 may contain a filler from the viewpoint of improving wear resistance to the thermal head and high temperature transportability. Examples of the filler of the protective layer 31 include aluminum hydroxide, kaolin, calcined clay, calcium carbonate, silica, zinc oxide, titanium oxide, zinc hydroxide, barium sulfate, clay, talc, mica, and surface-treated calcium and silica. In addition to the inorganic fine powders of the above, organic fine powders such as silicone resin, melamine-formaldehyde resin, urea formalin resin, styrene-methacrylic acid copolymer, polymethyl methacrylate resin, and polystyrene resin can be used. These can be used alone or in combination of two or more.

Among these, aluminum hydroxide, kaolin, and calcium carbonate are preferable, and aluminum hydroxide is more preferable, as the filler of the protective layer 31 from the viewpoint of abrasion resistance to the thermal head and the like. The average particle size of the filler used for the protective layer 31 is not particularly limited. Generally, it is preferably about 1.0 to 3.0 μm. The content of the filler in the protective layer 31 is not particularly limited. It may be appropriately blended according to the above-mentioned various performances.

Further, the protective layer 31 may contain auxiliary components commonly used in this kind of recording material, such as a surfactant, a pigment dispersant, and a lubricant, if necessary. For example, by blending dialkylsulfosuccinate as a surfactant or pigment dispersant in the protective layer 31, the film-forming property of the protective layer 31 can be enhanced, and the sensitivity and print storage stability can be further enhanced. As the dialkylsulfosuccinate, an alkali metal salt or an ammonium salt is preferably used, and a sodium salt is particularly preferably used. Further, as the alkyl group of the dialkyl sulfosuccinate, an alkyl group having 2 to 20 carbon atoms is preferable, and an alkyl group having 4 to 10 carbon atoms is particularly preferable. Specific examples thereof include an isobutyl group, a hexyl group, a cyclohexyl group, an octyl group, an isooctyl group, a 2-ethylhexyl group and the like, but the present invention is not particularly limited thereto. Among these, an octyl group or a 2-ethylhexyl group having 8 carbon atoms is particularly preferable. The content of the dialkylsulfosuccinate is not particularly limited, but is preferably 0.05 to 3% by mass, more preferably 0.1 to 2% by mass, based on the total amount of the protective layer 31.

Further, by blending the metal soap as a lubricant in the protective layer 31, the friction coefficient of the protective layer 31 can be lowered and the running performance of the thermal head can be improved. As the metal soap, a metal salt of a fatty acid having 12 to 18 carbon atoms is preferably used, and examples of the salt include calcium, magnesium, zinc, aluminum and the like, and aluminum salt and zinc salt are particularly preferably used. Specific examples of the metal soap include aluminum stearate, zinc stearate, aluminum distearate, aluminum oleate, aluminum palmitate, aluminum laurate, aluminum myristate, aluminum dimyristate, and the like, but are particularly limited thereto. Not done. The content of the metal soap is not particularly limited, but is preferably 0.05 to 3% by mass, more preferably 0.1 to 2% by mass, based on the total amount of the protective layer 31.

Here, when the auxiliary components such as the above-mentioned surfactant, pigment dispersant, and lubricant are blended in the protective layer 31, since these are relatively low molecular weight compounds, the auxiliary components (particularly, metal salts of fatty acids, etc.) Tends to easily bleed out to the surface of the protective layer 31. Therefore, when such a protective layer 31 is provided, when the heat-sensitive recording media 100 are overlapped with each other and the back surface 11b of the base film 11 and the protective layer 31 come into contact with each other, these auxiliary components are released from the back surface 11b of the base film 11. It is attached (transferred) to the film and can reduce its wettability. However, in the heat-sensitive recording medium 100 of the present embodiment, since the above-mentioned nanomat particles 12 hinder the surface contact between the back surface 11b of the base film 11 and the protective layer 31, the heat-sensitive recording medium 100 is placed on top of each other. Even in a situation where the back surface 11b of the base film 11 and the protective layer 31 are arranged close to each other by winding as a winding roll or the like, the base material of these auxiliary components bleeding out from the protective layer 31. Adhesion of the film 11 to the back surface 11b is effectively suppressed. Therefore, in the heat-sensitive recording medium 100 of the present embodiment, the wettability of the back surface 11b of the base film 11 is maintained high. Therefore, for example, a mode in which the thermal recording medium 100 is overlapped between the back surface 11b of the base film 11 and the protective layer 31 without interposing a slip sheet for preventing transfer of auxiliary components, that is, a form in which the heat-sensitive recording medium 100 is not inserted. Can also be realized.

The coating amount of the protective layer can be appropriately set according to the required performance and is not particularly limited, but the solid content after drying is preferably 0.1 to 10 g / m ² , and more preferably 1 to 8 g / m. It is ² .

<Manufacturing method of thermal recording medium>
The heat-sensitive recording medium 100 can be manufactured according to a conventional method, and the manufacturing method is not particularly limited. For example, as a method for producing the heat-sensitive recording medium 100 in the form shown in FIG. 1, a step of applying a coating liquid containing the nanomat particles 12 on at least the back surface 11b of the base film 11 and drying and solidifying the coating liquid (of the nanomat particles 12). (Bundling step), a step of applying a coating liquid containing each of the above components constituting the heat-sensitive recording layer 21 on the surface 11a of the base film 11 and drying and solidifying (a step of producing the heat-sensitive recording layer 21), and protection. The heat-sensitive recording medium 100 can be obtained through a step of applying a coating liquid containing each of the above components constituting the layer 31 on the surface 21a of the heat-sensitive recording layer 21 and drying and solidifying it (a step of producing the protective layer 31). it can. According to this method, the heat-sensitive recording medium 100 can be manufactured by roll-to-roll, and the thicknesses of the heat-sensitive recording layer 21 and the protective layer 31 can be adjusted relatively easily, so that the productivity can be adjusted. Can be improved. Hereinafter, this preferable manufacturing method will be described in detail.

When preparing each coating liquid, a solvent known in the art can be used as appropriate. The solvent is not particularly limited, but water, an organic solvent, and a mixed solvent thereof can be used. For example, ester solvents such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol and n-butanol; Carbohydrate-based solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; aromatic hydrocarbon-based solvents such as toluene and xylene; or mixed solvents thereof; are mentioned, but are not particularly limited thereto. These can be used alone or in combination of two or more.

The solid content concentration of each coating liquid may be appropriately set in consideration of the coating equipment to be used, handleability, productivity, etc., and is not particularly limited, but the solid content concentration of each coating liquid is coated. It is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, based on the total amount of the working liquid.

Here, the coating liquid of the nanomat particles 12 is preferably a dispersion or an emulsion in which the nanomat particles 12 are dispersed in the above-mentioned solvent from the viewpoint of keeping the nano-order particles uniformly dispersed. At this time, from the viewpoint of the adhesion of the coating layer for post-processing, a cationic water-based dispersion or an emulsion is preferable.

The method of applying each coating liquid is not particularly limited, and can be carried out according to a conventional method. For example, any known method such as die coating method, bar coating method, spin coating method, knife coating method, roll coating method, lip coating method, gravure coating method, spray coating method, inkjet method, dip coating method, etc. can be adopted. it can. At this time, use a coating device such as a die coater, a bar coater, a spin coater, a knife coater, a roll coater, a lip coater, a gravure coater, a spray coater, a blade coater, a reverse coater, an inkjet coater, an air knife coater, and an impregnation coater. You can also.

[Adhesive sheet 200 with release sheet]
The heat-sensitive recording medium 100 of the present embodiment can be attached to an adherend by providing an adhesive layer 41 and a release layer 51 on the back surface 11b side of the base film 11, for example, as shown in FIG. The aspect of the pressure-sensitive adhesive sheet 200 with a release sheet can be adopted. Hereinafter, the pressure-sensitive adhesive layer 41 and the release layer 51 will be described in detail.

<Adhesive layer>
The pressure-sensitive adhesive layer 41 can be formed, for example, by applying a generally used solvent-based or water-based pressure-sensitive adhesive onto the base film 11 and performing a smoothing step or a drying step as necessary. The type of pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 41 and the thickness (coating amount) of the pressure-sensitive adhesive layer 41 can be variously selected according to the type of adherend, the usage environment, the adhesive strength, and the like. As the pressure-sensitive adhesive, for example, a synthetic polymer pressure-sensitive adhesive such as a natural rubber type, a synthetic rubber type, a vinyl ether type, or an acrylic type can be used. When the pressure-sensitive adhesive is applied, it can be used in the form of a solution dissolved in an organic solvent, a dispersion dispersed in an aqueous solvent, an emulsion, or the like, if necessary. Among these, the acrylic emulsion type adhesive is preferable from the viewpoint of safety, quality, and cost.

Further, in the pressure-sensitive adhesive layer 41, a solution-state pressure-sensitive adhesive is applied onto a silicone-treated surface of a release sheet or process paper, and dried to form a layer, which is transferred onto the back surface 11b of the thermal recording medium 100. Can also be provided. For the coating of the adhesive, a known coating device such as a die coater, a bar coater, a roll coater, a lip coater, a gravure coater, a spray coater, a blade coater, a reverse coater, and an air knife coater can be used. The thickness of the pressure-sensitive adhesive layer can be appropriately set and is not particularly limited, but is usually preferably 2 to 30 μm, more preferably 5 to 20 μm.

<Peeling layer>
Further, the release layer 51 may be further provided on the pressure-sensitive adhesive layer 41 described above. By providing the release layer 51, the pressure-sensitive adhesive layer 41 can be protected when the pressure-sensitive adhesive sheet 200 is not used. Further, it is also possible to leave the release layer 51 provided at the time of printing and remove the release layer 51 at the time of attachment to the adherend. As the release layer 51, a release sheet known in the art can be used, and the type thereof is not particularly limited. For example, high-quality paper or kraft paper can be used as it is, calendered, resin-coated or film-laminated, and plastic films such as glassin paper, coated paper, and polyethylene film can be used. The release sheet used here is provided with a release agent such as silicone or a fluorine compound on the surface in contact with the pressure-sensitive adhesive layer 41 in order to improve the peelability from the pressure-sensitive adhesive layer 41 when the release sheet is attached to the heat-sensitive recording medium 100. It is preferable to use one.

Hereinafter, the present invention will be specifically described with reference to Examples and the like. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the present invention is not limited to the following examples.

(Example 1)
(1) Preparation of base film propylene homopolymer (trade name: Novatec PP FY6C, MFR (230 ° C, 2.16 kg load): 2.4 g / 10 minutes, melting point: 167 ° C (DSC peak temperature), Japan Polypropylene A resin composition (A) containing 85% by mass of heavy calcium carbonate powder having an average particle diameter of 2.7 μm and 15% by mass of heavy calcium carbonate powder was prepared by melt-kneading at 250 ° C. using an extruder. This melt-kneaded product was melt-extruded from a die into a sheet and cooled to about 60 ° C. with a cooling roll. The obtained thermoplastic resin sheet was reheated to 145 ° C. and then stretched 4.5 times in the vertical direction by utilizing the difference in peripheral speeds of the roll groups to obtain a uniaxially stretched film as a base layer.
Next, the resin composition (B) containing 55% by mass of the propylene homopolymer and 45% by mass of the heavy calcium carbonate powder, 85% by mass of the propylene homopolymer and the heavy calcium carbonate The resin composition (C) containing 15% by mass of the powder was melt-kneaded at 250 ° C. using two extruders to prepare each. These melt-kneaded products were melt-extruded from a die onto both sides of the uniaxially stretched film to obtain a three-layer structure laminate having a composition in the order of (B) / (A) / (C).
This three-layer structure laminate was introduced into a tenter oven, reheated to 160 ° C., stretched 8.5 times in the lateral direction using a tenter, and then heat-set (annealed) at 160 ° C. After that, the film was further cooled to 60 ° C., and the ears were slit to obtain a base film having a thickness of 100 μm. The porosity of this base film was 30%.

(2) Preparation of Support for Recording Medium Both sides of the obtained base film were subjected to corona discharge treatment at an intensity of 30 W / min / m ² . Next, an aqueous dispersion of cationic polyurethane resin (trade name: Hydran CP7050, average particle size: 75 nm, manufactured by DIC) and colloidal silica (trade name: Snowtex AK, average particle size: 10 to 15 nm, manufactured by Nissan Chemical Industries, Ltd.). ) Was mixed in water at the ratios shown in Table 2 and stirred to uniformly disperse to prepare a coating solution of nanomat particles. The obtained coating liquid was applied to both sides of the base film with a spray coater so as to have a solid content after drying as shown in Table 2, and dried, and nanomat particles were bound to both sides of the base film. A support for a recording medium was obtained.

(3) Preparation of Thermal Recording Layer and Protective Layer A coating liquid for the thermal recording layer was prepared according to the examples of JP2015-150764. The obtained coating liquid was applied to one side of the obtained support for recording media with a roll coater and dried so that the solid content would be 10 g / m ² after drying, and a heat-sensitive recording layer was provided.
Next, 600 parts by mass of a 10% by mass aqueous solution of polyvinyl alcohol (trade name: Gosenol NH-18, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and an aqueous dispersion of zinc stearate (trade name: Hydrin Z-8-36). , Solid content concentration 36%, manufactured by Chukyo Yushi Co., Ltd.) and 0.5 parts by mass of sodium dioctyl sulfosuccinate solution (trade name: Lapizol A-80, manufactured by Nichiyu Co., Ltd.) are mixed in water. Then, the mixture was stirred and uniformly dispersed to prepare a coating solution for the protective layer. The obtained coating liquid is applied on the above-mentioned heat-sensitive recording layer with a roll coater and dried so that the solid content becomes 5 g / m ² after drying, and a protective layer is provided, whereby the heat-sensitive recording medium is provided. Obtained.

(Examples 2 to 14)
When producing the support for recording media, the same procedure as in Example 1 was carried out except that the materials and blending ratios of the nanomat particles used were changed as shown in Tables 1 and 2, and the support for recording media and thermal recording were performed. I got the medium.

(Comparative Example 1)
A support for a recording medium and a heat-sensitive recording medium were obtained in the same manner as in Example 1 except that the step of providing the nanomat particles on the support was omitted when the support for the recording medium was produced.

(Comparative Example 2)
When manufacturing a support for a recording medium, the step of providing nanomat particles on the support is omitted, and instead, an ionic acrylic resin coating agent (trade name: Saftmer ST1000, manufactured by Mitsubishi Chemical Corporation) is applied to both sides of the base film. After drying, the process was carried out in the same manner as in Example 1 except that the solid content was 0.01 g / m ² per side, coated with a roll coater, dried and provided with a back coat layer. A heat-sensitive recording medium was obtained.

(Comparative Example 3)
When producing a support for a recording medium, the step of providing nanomat particles on the support was omitted, and instead, butyl-modified polyethyleneimine (trade name: Saftmer AC-72, manufactured by Mitsubishi Chemical Corporation) was used on both sides of the base film. A dispersion liquid in which micron-order crosslinked acrylic particles are dispersed is applied with a roll coater so that the solid content is 0.01 g / m ² per side after drying, and dried to provide a backcoat layer. The same procedure as in Example 1 was carried out to obtain a support for a recording medium and a heat-sensitive recording medium.

<Evaluation method>
The performance of the obtained thermal recording medium was evaluated by the following method.
[Humidification promotion conditions for thermal recording media]
Ten evaluation samples obtained by cutting the heat-sensitive recording media obtained in Examples 1 to 14 and Comparative Examples 1 to 3 into A4 size were prepared, and in a high temperature and high humidity environment (temperature) so as to prevent dew condensation from adhering to these. Pretreatment was performed at 40 ° C. and 90% humidity for 1 day, and then the front surface protective layer 31 surface and the back surface 11b surface of each heat-sensitive recording medium were overlapped so as to be in contact with each other, and placed above and below each layered heat-sensitive recording medium. It is sandwiched between iron plates large enough to cover A4 size, placed on a horizontal table, loaded from above with a weight of 10 kg, and in a high temperature and high humidity environment (temperature 40 ° C, humidity 90% RH). ), A humidification promotion test was conducted for 4 days.
[Measurement of wetness index]
According to the wetting tension test method described in JIS K6768: 1999, the wetting index on the back surface 11b side of the base film 11 to which the nanomat particles 12 were bound was measured using a plurality of wetting index solutions. Here, the wetting index immediately after coating was first measured, and then the wetting index after the above-mentioned humidification promotion test was measured.

[Evaluation of coating performance]
A test piece (5 cm x 15 cm) was cut out from the evaluation sample of each heat-sensitive recording medium after the humidification promotion test. On the back surface 11b of the base film 11 to which the nanomat particles 12 of the test piece were bound, a bar coater and a Mayer bar # 10 were used to obtain a wet tension test mixture No. 38.0 (manufactured by Wako Pure Chemical Industries, Ltd.) was applied. The liquid repellent at this time was visually observed and evaluated according to the following criteria. FIG. 5 shows a sample of evaluation determination. The wet tension test mixed solution used for the evaluation here was selected as a model for post-processing paints, especially water-based adhesives.
○ Good Liquid repellent does not occur and good wettability is maintained △ Fair Local liquid repellent occurs slightly × Poor Liquid repellent occurs widely

Table 1 shows the details of each material used.

Table 2 shows the prescriptions of Examples and Comparative Examples, and the evaluation results.

Further, FIGS. 3 and 4 show enlarged SEM photographs of the back surface side of the base film of the heat-sensitive recording medium of Examples 1 and 2, respectively.

100 Thermal recording medium 11 Base film 11a Front surface 11b Back surface 12 Nanomat particles 21 Thermal recording layer 21a Surface 31 Protective layer 41 Adhesive layer 51 Peeling layer 101 Supporting material for recording medium 200 Adhesive sheet with peeling sheet

Claims (4)

A base film containing a thermoplastic resin, a heat-sensitive recording layer provided on one surface side of the base film, and a protective layer provided on the surface side of the heat-sensitive recording layer not facing the base film. It is a thermal recording medium equipped with
Nanomat particles having an average particle diameter of 5 to 800 nm are bound on at least the other surface of the base film.
The nanoparticles include at least inorganic nanoparticles having an average particle diameter of 5 to 150 nm and organic nanoparticles having an average particle diameter of 20 to 800 nm.
A heat-sensitive recording medium characterized in that the average particle size of the organic nanoparticles is 0.1 to 160 times that of the inorganic nanoparticles. The heat-sensitive recording medium according to claim 1, wherein the inorganic nanoparticles contain a metal oxide or a hydrate thereof. The heat-sensitive recording medium according to claim 1 or 2, wherein the organic nanoparticles include thermoplastic resin particles. It is a winding roll in which a heat-sensitive recording medium is wound in a roll shape.
The thermal recording medium is
A base film containing a thermoplastic resin, a heat-sensitive recording layer provided on one surface side of the base film, and a protective layer provided on the surface side of the heat-sensitive recording layer not facing the base film. With
Nanomat particles having an average particle diameter of 5 to 800 nm are bound on at least the other surface of the base film.
The nanoparticles include at least inorganic nanoparticles having an average particle size of 5 to 150 nm and organic nanoparticles having an average particle size of 20 to 800 nm.
A winding roll characterized in that the average particle size of the organic nanoparticles is 0.1 to 160 times that of the inorganic nanoparticles .

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