JP2007107141A - Recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide recording paper, hardly causing uneven feeding such as slip and giving a high grade recorded object. <P>SOLUTION: The recording paper is used for a recorder having a recording part for recording images on the recording paper and paper feed rollers for feeding the recording paper to the recording part, wherein the paper has at least a surface layer for recording the images thereon and a rear face layer on which none of the images is recorded, the rear face layer includes a resin layer containing a resin as a main component and formed irregularity on the surface thereof, the pitch of the projecting part is 50-200 μm and the height of the projecting part is 20-100 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording sheet used in a recording apparatus such as an ink jet printer, and more particularly to a recording sheet that is less likely to cause uneven conveyance such as slip and can provide a high-quality recorded matter.

  Some recording apparatuses such as an ink jet printer include a recording unit that records an image on a recording sheet, and a paper feed roller that sends the recording sheet to the recording unit. FIG. 4 shows an example of an ink jet printer having such a configuration. In the ink jet printer shown in FIG. 4, the recording paper M held in an inclined posture by the paper holding unit (paper feed tray) 20 is fed between the paper feed roller 22 and the driven roller 23 by the paper feed roller 21. The paper is further transported in a horizontal position to the position of the platen 25 by both transport rollers 22 and 23, and desired recording is performed by the ink jet head 24, and the paper is discharged while being nipped by the nip portion of the paper feed roller 26 and the driven roller 27. Paper.

  In the recording apparatus configured as shown in FIG. 4, contact tension between the recording sheet and the inside of the recording apparatus applies back tension in the direction opposite to the conveying direction. May occur. If slip or the like occurs while the recording paper is being transported, the paper feed amount of the recording paper will be misaligned, so that the ink adhesion position will also be misaligned, resulting in unintended dark color streaks (color unevenness) in the recorded image. Occurs, and the recorded image is disturbed.

In order to prevent uneven conveyance of the recording paper, Patent Document 1 provides a back surface layer containing a binder mainly composed of a flat pigment and having a glass transition temperature of 30 to 60 ° C. on the back surface of the recording paper. Technology is disclosed. Further, Patent Document 2 discloses a back surface containing a spherical fine particle polymer having an average particle diameter of 5 to 15 μm in a dry weight of 5 to 100 mg / m ² on the back surface of a support as an ink jet recording sheet having improved transportability in a printer. A coating layer is provided, and the thickness of the backing layer is smaller than the average particle diameter of the spherical fine particle polymer.

  By applying the above-described conventional technique, a certain improvement can be seen in the conveyance unevenness. However, when recording is performed using a high-speed printer with a high recording speed, the effect of preventing the conveyance unevenness cannot be said to be sufficient. There remains a problem with the stability of paper feed. It is expected that the recording speed will continue to increase in the future, and the user has realized a stable paper feed that does not cause slipping even in high-speed recording, and the recording paper that enables high-quality recording. Development was requested.

JP-A-4-298380 JP-A-7-179025

  Accordingly, it is an object of the present invention to provide a recording paper that is capable of providing a high-quality recorded matter that is less likely to cause uneven conveyance such as slip and has no color unevenness.

  The present invention provides a recording sheet used in a recording apparatus including a recording unit that records an image on a recording sheet and a paper feed roller that sends the recording sheet to the recording unit. And a back surface layer on which the image is not recorded. The back surface layer is made of a resin layer containing a resin as a main component and has unevenness on the surface, and the pitch of the protrusions is 50 to 200 μm. The above object is achieved by providing a recording paper characterized in that the height of the convex part is 20 to 100 μm.

  The recording paper of the present invention has excellent transportability in a recording apparatus, which is less likely to cause uneven transport such as slip, double feed, and paper feed failure due to the action of the back layer, and transport such as color unevenness. The recorded image is less likely to be disturbed due to unevenness, and a high-quality recorded matter can be provided even in high-speed recording. Further, since the unevenness is formed on the surface of the back layer, it is easy to discriminate between the front and the back, and it is possible to prevent mistakes that a person handling the recording paper mistakes to print the front and back.

Hereinafter, the recording paper of the present invention will be described in detail based on a preferred embodiment thereof with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of the recording paper of this embodiment, and FIG. 2 is an enlarged cross-sectional view of a part (back surface layer) of the recording paper shown in FIG.

  A recording paper 1 shown in FIG. 1 has a surface layer 2 on which an image is recorded by a recording apparatus such as an ink jet printer, and a back surface layer 3 on which no image is recorded. Further, the surface layer 2 and the back surface layer 3 A sheet-like support 4 is provided therebetween. Below, the back surface layer 3 is demonstrated in detail.

  The back surface layer 3 is a non-recording layer on which no image is recorded, and is a layer that comes into contact with a paper feed roller of the recording apparatus (paper feed rollers indicated by reference numerals 22 and 26 in the ink jet printer shown in FIG. 4). The back surface layer 3 contains a resin as a main component, that is, a resin layer in which 50% by weight or more of the total solid content of the back surface layer is a resin, and unevenness is formed on the entire surface. The unevenness is formed by a plurality of convex portions (peak portions) 31 and a plurality of concave portions (valley portions) 32.

  The pitch of the convex and concave portions 31 formed on the surface of the back surface layer 3 (the distance between the vertex of one convex portion and the vertex of the other convex portion in the two adjacent convex portions), and the convex portion 31 The height (the distance between the top of the convex portion and the top of the concave portion forming the irregularities) is a very important factor that affects the conveyance of the recording paper. Unless the pitch p and the height h of the convex portions are within appropriate ranges, it is not possible to effectively prevent conveyance unevenness such as slip. In the present invention, the pitch p of the protrusions 31 is adjusted to 50 to 200 μm, preferably 70 to 150 μm, and the height h of the protrusions 31 is adjusted to 20 to 100 μm, preferably 35 to 75 μm. Therefore, even in high-speed recording, excellent transportability is realized that is less likely to cause transport unevenness such as slip, double feed, and paper feed failure.

  Further, in order to obtain a recording sheet with more excellent transportability, it is preferable that the back layer 3 (resin layer) has appropriate flexibility. From such a viewpoint, the hardness specified by JIS K6253-1997 of the back surface layer 3 is preferably in the range of A20 to A95, and more preferably in the range of A50 to A90.

  Examples of the resin that is the main component of the back layer 3 include vinyl chloride, vinyl acetate, acrylic, urethane, polyester, polyolefin, vinyl chloride-vinyl acetate, vinyl chloride-acrylic, vinyl chloride- Latex particles comprising any one of vinylidene chloride, vinylidene chloride-acryl, styrene butadiene rubber (SBR), and nitrile rubber (NBR), or a copolymer of two or more of these, or , Polyolefins such as polyethylene, polypropylene, and polyisobutylene, polyvinyl chloride, polyvinyl acetate, polystyrene, polyacrylate, polyamide, polyimide, polyester, cellulose resin, and the like. These are used alone or in combination of two or more. It can be used by mixing. Among these, polyurethane such as hydrophilic urethane resin, SBR, polyisoprene, and polybutadiene are particularly preferably used in the present invention because they can impart the above-described appropriate flexibility to the back layer.

  As necessary, the back layer 3 may contain a hardening agent, pigment, dispersant, surfactant, antistatic agent, leveling agent, antioxidant, antifoaming agent, antifoaming agent, etc. as components other than the resin. It can be contained in combination.

  The back surface layer 3 can be formed by applying a coating solution containing the various components described above by a known coating method and drying it. As a method of forming the unevenness on the surface of the back surface layer 3, for example, (1) a predetermined unevenness is formed in advance on the back surface layer forming surface of the support by embossing or the like, and the uneven surface is formed on the surface. , A method of applying and drying the coating solution for the back layer, (2) coating and drying the coating solution for the back layer on the support to form a coating layer once, and then embossing the coating layer Although the method of giving a process, etc. are mentioned, the point should just be a method which can adjust the pitch and height of a convex part to the said range.

The thickness of the back surface layer 3 is preferably 1 to 50 μm, more preferably 5 to 40 μm, from the viewpoint of preventing curling of the paper and preventing slipping during paper conveyance. The coating amount of the back layer 3 is preferably 1 to 50 g / m ² and more preferably 5 to 40 g / m ² in terms of solid content. Here, “the thickness of the back surface layer 3” and “the coating amount of the back surface layer 3” are those in the case where the support 4 having the configuration described later is present. The thickness and the coating amount of the back layer when the recording paper does not have a support and consists of only the front layer and the back layer will be described later.

  Hereinafter, constituent members (surface layer 2, support 4) other than the back surface layer 3 of the recording paper of the present embodiment will be described in detail.

  The surface layer 2 is a recording layer on which an image is recorded on the surface when ink is directly applied. In the present embodiment, the surface layer 2 is a so-called void-type ink receiving layer that contains inorganic particles and a binder for the inorganic particles and has a void structure such as a sponge. The void-type ink receiving layer has high ink absorbability due to the voids between adjacent inorganic particles in the layer and the pores of the inorganic particles themselves. Can be formed.

  Examples of the inorganic particles contained in the surface layer 2 include silica, alumina, calcium carbonate, magnesium carbonate, barium sulfate, aluminum oxide, aluminum hydroxide, kaolin, talc, clay, fired clay, satin white, aluminum silicate, Examples include magnesium silicate, titanium dioxide, zinc oxide, and diatomaceous earth. In this invention, these 1 type may be used independently and 2 or more types may be used together.

  Among the inorganic particles, silica and alumina are particularly preferable, and it is particularly preferable to use only alumina as the inorganic particles. As inorganic particles in this type of void-type ink-receiving layer, silica is often used, and it is rare to use only alumina. However, depending on how alumina is used, alumina is more than the case of using silica. In the preferred embodiment of the invention, alumina is used alone as the inorganic particles.

  Examples of the alumina used in the present invention include α-alumina, transition alumina (alumina having γ, δ, and θ-alumina as a main phase), boehmite, pseudoboehmite, diaspore, gibbsite, bayerite, and amorphous alumina. These may be used alone or in combination of two or more. Among these aluminas, boehmite, pseudoboehmite, and α-alumina are particularly preferably used in the present invention because they have a suitable pore radius that can impart a good ink absorbing ability to the surface layer.

  The average primary particle diameter of alumina used in the present invention is preferably 3 to 50 nm, more preferably 3 to 30 nm, from the viewpoint of the balance between the ink absorbability of the surface layer, surface glossiness, and color developability. The average primary particle diameter of alumina can be measured using a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like.

  In addition, the average pore radius of alumina used in the present invention is preferably 3 to 20 nm, more preferably 3 to 15 nm, from the viewpoint of obtaining good ink color material fixability and ink absorbability. The average pore radius of alumina can be determined by a mercury intrusion method.

  The content of the inorganic particles is preferably 70 to 97% by weight with respect to the dry weight of the surface layer from the viewpoint of the balance between ink absorbency and coating film strength.

  As the binder (binder) of the inorganic particles contained in the surface layer 2, a water-soluble or water-insoluble polymer compound having affinity with ink can be contained. Specifically, for example, cellulosic adhesives such as methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, and hydroxyethylcellulose, starch and modified products thereof, gelatin and modified products thereof, casein, pullulan, gum arabic, and albumin Natural polymer resins or derivatives thereof, polyvinyl alcohol and modified products thereof, styrene-butadiene copolymer, styrene-acrylic copolymer, methyl methacrylate-butadiene copolymer, latex of ethylene-vinyl acetate copolymer, etc. Emulsions, vinyl polymers such as polyacrylamide and polyvinyl pyrrolidone, polyethyleneimine, polypropylene glycol, polyethylene glycol, and maleic anhydride or copolymers thereof, vinyl pyro Don / vinyl acetate copolymer, polyvinyl butyral, include acetal resins such as polyvinyl formal, it is possible to use these alone or in combination of two or more.

  Preferable examples of the binder are polyvinyl alcohol and a modified product thereof (modified polyvinyl alcohol). Particularly, polyvinyl alcohol having a saponification degree of 75 to 98 mol% and an average polymerization degree of 500 to 5000 and a modified product thereof are preferable. Examples of the modified product include a cation modified product and a silanol modified product. Such polyvinyl alcohol or the like can increase the layer strength by adding a relatively small amount without inhibiting the water-based ink absorbability of the surface layer.

  The content of the binder is preferably 3 to 30 parts by weight with respect to 100 parts by weight of the inorganic particles contained in the surface layer, from the viewpoint of the balance between the coating strength of the ink receiving layer and the ink absorbability. More preferably, it is 5 to 25 parts by weight.

In addition to the above-described inorganic particles and binder, the surface layer 2 may include a crosslinking agent, an ink fixing agent (cationic substance), a pigment dispersant, a thickener, a fluidity improver, and an antifoaming agent as necessary. Various additives such as foam suppressors, mold release agents, foaming agents, penetrants, coloring dyes, coloring pigments, fluorescent brighteners, UV absorbers, antioxidants, preservatives, and antibacterial agents. Can do.
The surface layer 2 can be formed by applying a coating liquid containing the above-described various components by a known coating method and drying it.

The thickness of the surface layer 2 is preferably 20 to 70 μm, more preferably 30 to 50 μm, from the viewpoint of the balance between ink absorbency and prevention of powder falling. The coating amount of the surface layer 2 is preferably 20 to 70 g / m ² and more preferably 30 to 50 g / m ² in terms of solid content.

As the support 4 on which the surface layer 2 and the back layer 3 described above are formed, a support for the coating layer used in this type of coated paper can be used without particular limitation. For example, fine paper, recycled paper Paper such as size-treated paper; art paper, coated paper, cast-coated paper, resin-coated paper, resin-impregnated paper; polyethylene, polypropylene, polystyrene, polyethylene terephthalate film or sheet plastic substrate; metal film, metal plate; A composite substrate or the like in which these are bonded can be used. The thickness of the support is preferably 100 to 250 μm, and the weight (basis weight) per unit area of the support is preferably 100 to 300 g / m ² .

  In the present invention, a particularly preferable support is a resin-coated paper. The resin-coated paper is one in which both sides of the base paper are respectively coated with a polyolefin resin, and is particularly effective in improving gloss, texture and water resistance.

  As the base paper constituting the resin-coated paper, paper is preferably used. Examples of the pulp constituting this paper include natural pulp, recycled pulp, synthetic pulp, and the like, and one or more of these can be used in combination. If necessary, the paper can contain various additives such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, a fluorescent whitening agent, and a dye that are generally used in papermaking. Further, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchor agent, and the like may be applied to the paper. Further, the paper surface may be subjected to a surface smoothing treatment as usual using a calendar device or the like during or after paper making.

  Examples of the polyolefin resin include olefin homopolymers such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, and polypentene, copolymers composed of two or more olefins such as ethylene-propylene copolymer, or the like. These may be used, and various types of density and melt viscosity index (melt index) can be used alone or as a mixture thereof. Among these, low density or high density polyethylene is particularly preferable in terms of texture, strength, water resistance and cost.

  For the above polyolefin resin, white pigment such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amide such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, stearic acid Fatty acid metal salts such as magnesium, antioxidants such as Irganox 1010 and Irganox 1076, coloring pigments and coloring dyes, fluorescent brighteners, ultraviolet absorbers and the like can be contained in appropriate combinations.

  The resin-coated paper can be produced by a so-called extrusion coating method in which a polyolefin resin heated and melted is cast on a traveled base paper. Before the base paper is coated with the polyolefin resin, the base paper may be subjected to an activation treatment such as corona discharge treatment or flame treatment. The thickness of the polyolefin resin layer covering both surfaces of the base paper is preferably 10 to 50 μm.

  In the recording paper of the present invention represented by the embodiment having the above-described configuration, two recording papers are laminated so that the back layer of one recording paper and the top layer of the other recording paper overlap. The static friction coefficient between the back surface layer and the front surface layer in the state is preferably 0.3 to 0.8, more preferably 0.4 to 0.7. By adjusting the static friction coefficient to such a range, when used in a recording apparatus, it is excellent in continuous paper feeding, less likely to cause uneven conveyance such as slip, paper jam, double feeding, etc. Recording paper is obtained. The static friction coefficient is adjusted to such a range by adopting the same configuration as that of the embodiment including the surface layer 2, the back surface layer 3 and the support 4 described above, in particular, the same configuration as that of the surface layer 2 and the back surface layer 3. Is possible.

  The recording sheet of the present invention can be suitably used in a recording apparatus including a recording unit that records an image on a recording sheet and a paper feed roller that feeds the recording sheet to the recording unit. However, it can be preferably used in an ink jet printer having an ink jet head for recording an image by ejecting ink onto a recording paper, that is, an ink jet printer having a configuration as shown in FIG. Ink jet heads include those equipped with electro-mechanical conversion elements (piezoelectric elements) such as piezo elements, and those equipped with electromechanical-heat conversion elements as means for forming ink droplets. Any ink jet head equipped with any droplet forming means can be applied.

  The recording apparatus in which the recording sheet of the present invention can exert its effect most is a recording apparatus in which the roller surface that contacts the recording sheet of the paper feed roller is formed of ceramics. Examples of the ceramic include ceramic powder such as alumina and silicon carbide (SiC). Such a ceramic paper feed roller has good compatibility with the back layer according to the present invention, and by combining the ceramic paper feed roller and the recording paper of the present invention, conveyance unevenness such as slips can be more effectively prevented. be able to.

The recording paper of the present invention is not limited to the above-described configuration, that is, the recording paper having the surface layer 2 on one side of the support 4 and the back layer 3 on the other side of the support 4. Various modifications can be made without departing from the spirit of the present invention.
For example, an anchor coat layer may be formed between the support 4 and the surface layer 2 and / or between the support 4 and the back surface layer 3 in order to enhance the adhesion between adjacent layers. The anchor coat layer is particularly effective when the resin-coated paper is used as a support.
Further, the surface layer 2 may have a single-layer structure having a single composition, or may be configured by laminating multiple layers having different compositions.

Further, the recording paper of the present invention can be composed of only the front surface layer 2 and the back surface layer 3 ′ as in the recording paper 1 ′ shown in FIG. In such a configuration, the thickness of the back surface layer 3 ′ is desirably larger than the thickness of the back surface layer 3 in the above embodiment (recording paper 1) having the support 4, preferably 50 to 300 μm, more preferably 100. ˜250 μm. The coating amount of the back surface layer 3 ′ is preferably 50 to 300 g / m ² , more preferably 100 to 250 g / m ² in terms of solid content. The configuration other than the thickness (coating amount) of the front surface layer 2 and the back surface layer 3 ′ in the recording paper 1 ′ can be the same as that in the above-described embodiment.

  Hereinafter, the present invention will be described more specifically with reference to examples of the present invention and test examples showing the effects of the present invention. However, the present invention is not limited to the examples.

(Manufacture of resin-coated paper (support))
To 100 parts by weight of LBKP pulp having a beating degree of 300 mlcsf, 0.5 part by weight of epoxidized behenamide, 1.0 part by weight of anionic polyacrylamide, 0.1 part by weight of polyamide polyamine epichlorohydrin, 0.5 part by weight of cationic polyacrylamide, In any case, a slurry was obtained by adding at an absolute dry weight ratio with respect to the pulp, and this was applied to a long net paper machine to produce a base paper of 170 g / m ² . Furthermore, in order to adjust the surface size of the base paper, 0.04% by weight of a fluorescent whitening agent (Whiteex BB, manufactured by Sumitomo Chemical Co., Ltd.) is added to a 4% aqueous solution of polyvinyl alcohol, and this is 0.5 g in terms of absolute dry weight. The base paper was impregnated so as to be / m ² , dried, and then calendered to obtain a base paper adjusted to a density of 1.05 g / ml.

After the corona discharge treatment was performed on the wire surface (back surface) side of the base paper thus obtained, the entire surface of the corona discharge treatment surface was uniformly coated with high-density polyethylene using a melt extruder, and a resin layer having a thickness of 29 μm Formed. Further, after corona discharge treatment was applied to the surface of the resin layer, aluminum oxide (Nissan Chemical Industries, Alumina Sol 100) and silicon dioxide (Nissan Chemical Industries, Snowtex O) were added to the corona discharge treatment surface. A dispersion (antistatic agent) dispersed in water at a weight ratio of ^{2 was} applied at a dry weight of 0.2 g / m ² .

  Next, after the corona discharge treatment is performed on the felt surface (front surface) side of the base paper, the entire surface of the corona discharge treatment surface is coated with a low density polyethylene of MFR (melt flow rate) 3.8 using a melt extruder. And uniformly coated to form a resin layer having a thickness of 29 μm. The low-density polyethylene used here contains 10% by weight of anatase-type titanium dioxide with respect to polyethylene, 0.01% by weight of fluorescent brightening agent with respect to polyethylene, and a trace amount of ultramarine blue.

Further, 0.6 g / m ^{2 of} polyallylamine (manufactured by Nitto Boseki Co., Ltd.) as a mordant is applied to the surface of the resin layer formed on the felt surface (front surface) side of the above base paper and dried to provide an anchor coat layer (a mordant-containing layer). Formed.
Thus, a resin-coated paper with an anchor coat layer, in which both surfaces of the base paper were coated with a resin layer, was produced.

(Preparation of coating liquid for surface layer, coating liquids A to B for back layer)
A surface layer coating solution and a back layer coating solution A to B having the following compositions were respectively prepared.

<Composition of coating solution for surface layer>
・ Alumina (pseudo boehmite powder, average primary particle size 15 nm) 12% by weight
・ Binder (Kuraray, PVA235) 2.2% by weight
(Polyvinyl alcohol, saponification degree 88 mol%, average polymerization degree 3500)
・ Cation polymer 0.5% by weight
(Daiichi Kogyo Seiyaku Co., Ltd., Charol DC902P, 51.5% aqueous solution)
・ Boric acid (crosslinking agent) 0.5% by weight
・ Polyoxyethylene lauryl ether (surfactant) 0.03% by weight
(Kao, Emulgen 109P, 10% aqueous solution)
・ Ion exchange water balance
100% by weight

<Composition of coating liquid A for back layer>
・ 10% by weight of hydrophilic urethane resin
(Da Nippon Ink Chemical Industries, Patera Coal IJ-70)
・ Ion exchange water 90% by weight
100% by weight

<Composition of coating liquid B for back layer>
・ SBR latex 14% by weight
(Manufactured by JSR, 0696, solid concentration 50 wt% liquid)
・ Process oil 86% by weight
(Fujikosan, Fukkor Flex # 2050N)
100% by weight

[Example 1]
The surface of the resin-coated paper (support) opposite to the anchor coat layer side was embossed using an embossing roll to form irregularities on the entire surface. Next, on the anchor coat layer of the resin-coated paper, the surface layer coating solution is applied and dried so that the coating amount after drying is 40 g / m ^2. Type ink receiving layer), and the coating amount after drying the back layer coating liquid A on the uneven surface (embossed surface) of the resin-coated paper is 10 g / m ^2. Coating and drying were performed to form a back surface layer having a thickness of 10 μm. The recording paper obtained by the above procedure was used as a sample of Example 1.

[Examples 2 to 6 and Comparative Examples 1 to 6]
In Example 1, the embossing conditions, the back surface layer coating liquid were appropriately selected, and the pitch and height of the convex portions on the back layer surface and the hardness of the back layer were variously changed. In this way, recording paper was manufactured and used as samples of Examples 2 to 6 and Comparative Examples 1 to 4, respectively. In addition, in the sample of Example 6 manufactured without applying the coating liquid for the back surface layer, the resin layer formed on the wire surface side of the base paper in the resin-coated paper is the back surface layer referred to in the present invention. .
Moreover, in Example 1, what was manufactured similarly to Example 1 except not having applied the said embossing to the resin-coated paper, and not having applied the said back surface coating liquid A was used as the sample of Comparative Example 5. did.
Further, in Example 1, a sample produced in the same manner as in Example 1 except that the resin-coated paper was not embossed was used as a sample of Comparative Example 6.

[Test example]
For each sample of the recording paper thus obtained, the color unevenness prevention property was evaluated by the following method in order to evaluate the difficulty of occurrence of transport unevenness such as slip. It can be said that the better the color unevenness prevention property, the less likely the transport unevenness such as slip occurs.
Moreover, the hardness of the back surface layer of each sample was measured according to the durometer A method prescribed | regulated by JISK6253-1997.
Furthermore, the coefficient of static friction between the back surface and the front surface of each sample was determined by J. Tensilon using two recording papers for each sample. TAPPI paper pulp test method no. It measured according to 30-79.
These results are shown in Table 1 below.

(Evaluation method for color unevenness prevention)
The sample is set in an ink jet printer having a paper feed roller and the roller surface of the paper feed roller is made of ceramics (manufactured by Seiko Epson, PM-A900), and the surface of the surface layer (recording surface) In addition, each color ink of cyan, magenta, and yellow was ejected at a duty of 33% to print a gray color patch. Then, this gray color patch was observed by 20 monitors selected arbitrarily from the printing industry, and those with less than 5 monitors that said that dark color streaks (color unevenness) were conspicuous were A (color unevenness prevention) 5) who answered that color unevenness was conspicuous, and B (no practical problem), and C where more than 10 people answered that color unevenness was conspicuous.

It is a cross-sectional schematic diagram of one embodiment of the recording paper of the present invention. FIG. 2 is an enlarged cross-sectional view of a part (back surface layer) of the recording paper illustrated in FIG. 1. It is a cross-sectional schematic diagram of another embodiment of the recording paper of the present invention. It is a schematic side view of an example (inkjet printer) of a recording apparatus that can suitably use the recording paper of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 '... Recording paper, 2 ... Front surface layer, 3, 3' ... Back surface layer, 4 ... Support body, 20 ... Paper holding part (paper feed tray), 21 ... Paper feed roller, 22, 26 ... Paper feed roller , 23, 27 ... driven roller, 24 ... inkjet head, 25 ... platen, 31 ... convex part, 32 ... concave part, M ... recording paper

Claims (9)

In a recording sheet used in a recording apparatus including a recording unit that records an image on a recording sheet and a paper feed roller that sends the recording sheet to the recording unit.
At least a surface layer on which the image is recorded and a back surface layer on which the image is not recorded, the back surface layer is made of a resin layer containing a resin as a main component, and unevenness is formed on the surface, A recording paper, wherein the pitch of the convex portions is 50 to 200 μm, and the height of the convex portions is 20 to 100 μm.   2. The recording paper according to claim 1, wherein the hardness of the back layer defined by JIS K6253-1997 is A20 to A95.   3. The recording paper according to claim 1, wherein the back layer contains at least one selected from the group consisting of polyurethane, styrene butadiene rubber (SBR), polyisoprene and polybutadiene as the resin.   The recording sheet according to claim 1, wherein the surface layer contains inorganic particles and a binder for the inorganic particles and has a void structure.   The recording paper according to claim 4, wherein the inorganic particles are alumina.   6. The support according to claim 1, wherein the support is a resin-coated paper in which both surfaces of the base paper are respectively coated with a polyolefin resin. The support has a support between the front surface layer and the back surface layer. Recording paper as described in Crab.   The static friction coefficient between the back layer and the surface layer in a state where the two recording sheets are laminated so that the back layer of one recording sheet and the top layer of the other recording sheet overlap. The recording paper according to any one of claims 1 to 6, wherein the recording paper is 0.3 to 0.8.   The recording sheet according to claim 1, wherein the recording unit of the recording apparatus includes an inkjet head that records an image by ejecting ink onto the recording sheet. The recording paper according to any one of claims 1 to 8, wherein the paper feed roller in the recording apparatus has at least a roller surface in contact with the recording paper made of ceramics.

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