CN113329886A

CN113329886A - Printing sheet with a fold

Info

Publication number: CN113329886A
Application number: CN202080010399.5A
Authority: CN
Inventors: 高桥友嗣; 诸冈槙
Original assignee: Yupo Corp
Current assignee: Yupo Corp
Priority date: 2019-06-18
Filing date: 2020-02-03
Publication date: 2021-08-31
Anticipated expiration: 2040-02-03
Also published as: JP7124220B2; JPWO2020255473A1; WO2020255473A1; CN113329886B

Abstract

The invention provides a printing paper, which can perform printing even at the periphery of a folding part and can be easily seen when the printing of left and right pages is seamlessly connected when the printing paper is opened in a split mode. The printing paper (10) comprises a base layer and a printing layer laminated on at least one surface of the base layer, and has a linear folding part (11) recessed in the thickness direction of the printing paper (10), wherein the base layer is a thermoplastic resin film containing a porous layer. Since the folding section (11) is formed by heating and pressing the printing paper (10) containing the thermoplastic resin film, characters or images can be printed on the periphery of the folding section (11).

Description

Printing sheet with a fold

Technical Field

The present invention relates to a printing sheet having a fold. The printing paper according to the present invention is used, for example, as a booklet formed by stacking a plurality of printing papers. In particular, the printing paper according to the present invention is suitable for printing paper such as a photo album which is viewed in a split manner.

Background

Conventionally, the following binding methods are known: a plurality of pages printed with photographs and the like are overlapped and aligned on a back cover, and the pages are combined by a binding part arranged on the periphery of the edge of the back cover. For example, when pages for an album are to be combined, it is common to apply a hot-melt adhesive to the periphery of a back cover to join the pages, or to form a plurality of holes so as to penetrate through the binding portions of the pages, and to insert screws (binding screws) into the holes to connect the pages.

However, the above-described binding method has pointed out the following problems: when the booklet is opened in a half-open manner, the left and right pages are difficult to be flat, and if the booklet is forcibly opened in a flat manner, the pages or the staples may be damaged (patent document 1). In order to overcome such a problem, patent document 1 proposes a sheet material in which an opening is formed along a binding portion of each page, a flexible film is attached so as to cover the opening, and a folding region for facilitating folding of each page is formed by the opening and the film.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication No. 2010-520099

Disclosure of Invention

Problems to be solved by the invention

However, in the case of a sheet material as described in patent document 1, when an opening is formed in each printing paper and a flexible film is attached thereto, a level difference is generated between the printing paper and the film around the opening. In this case, when printing is performed around the opening, there is a possibility that printing may be disturbed due to a difference in level between the printing paper and the film. In addition, depending on the material of the flexible film, it is difficult to print itself thereon. Therefore, it is realistic to avoid the flexible film and to prevent printing from being performed around the opening of each printing sheet, but in this case, a region where printing cannot be performed is generated in the center portion of the facing page (the periphery of the binding portion), and the photographs printed on the right and left pages become discontinuous. This impairs the meaning of opening the left and right pages flat.

Therefore, an object of the present invention is to provide a printing sheet having a fold portion and capable of being opened flat, which can be easily printed even in the periphery of the fold portion, and in which printing of right and left pages is seamlessly continuous and easily visible when opened in a folio manner.

Means for solving the problems

The inventors of the present invention have made intensive studies on means for achieving the above object, and as a result, have found that: by forming a linear flap portion recessed in a concave shape on a printing sheet made of a thermoplastic resin film containing a porous layer, printing can be performed until the flap portion (recess portion) is located in front. The present inventors have also conceived that the problems of the prior art can be solved based on the above findings, and have completed the present invention.

More particularly, the present invention relates to printing paper. The printing paper according to the present invention is formed by laminating a base material layer and a printing layer. The base layer is composed of a thermoplastic resin film including a porous layer. The printing layer is laminated on one or both surfaces of the base material layer, and characters, images, and the like can be recorded by printing. The printing paper according to the present invention has a linear folded portion recessed in the thickness direction of the printing paper. The folding portion is preferably linear, but may be curved or folded. The folding portion can be formed by pressing the printing paper while heating, for example. By heating and pressing, the base material layer included in the printing paper is compressed, thereby forming a concave-shaped flap portion.

As described above, since the printing sheet according to the present invention is a printing sheet in which the concave hinge portion is formed in a series of printing sheets including a porous thermoplastic resin film, it is not necessary to form an opening in a sheet or attach a flexible film to the opening as in the sheet material described in patent document 1. Therefore, in the printing paper of the present invention, printing can be easily performed also in front of the folding section. Thus, when the booklet formed by binding the printed sheets of paper is opened in a half-open manner, the characters and images printed on the right and left pages are seamlessly connected and easily viewed because the printing can be performed with uniform quality even at the center portion (the periphery of the binding portion) thereof. Further, since it is not necessary to form an opening or attach a flexible film, the material cost or the manufacturing cost of the printing paper can be suppressed to a low level according to the present invention. Further, the printing paper sheet of the present invention is easily folded along the concave folding portion, and is easily and naturally opened flat when it is opened in a half.

In the printing paper according to the present invention, it is preferable that the paper thickness in the region other than the fold is 80 to 600 μm, and the paper thickness in the fold is 10 to 85% of the paper thickness in the region other than the fold. In the present specification, the term "region other than the hinge portion" refers to a flat printed portion on which characters or images are printed. When it is assumed that a printing sheet is used for a general album, the printing sheet has a thickness of 80 to 600 μm as described above, so that a moderate rigidity is generated and a concave fold portion is easily formed. In addition, by setting the paper thickness of the folding part to 10-85% of the paper thickness of the printing paper, appropriate strength is generated in the folding part, so that the printing paper is not easy to break, and the printing paper is easy to bend in the folding part.

In the printing paper according to the present invention, the width of the fold is preferably two times or more the depth of the fold. This makes it easy to maintain the folded state of the printing paper at the folding portion. The upper limit of the width of the hinge is not particularly limited, but is preferably 5 times or less or 4 times or less the depth of the hinge.

In the printing paper of the present invention, the base layer is preferably formed of a polyolefin resin. As the thermoplastic resin, a polyethylene terephthalate (PET) resin or a styrene resin may be used, but a Polyolefin (PO) resin having both strength and flexibility capable of withstanding repeated bending of the hinge portion is particularly preferably used.

In the printing paper according to the present invention, the porosity of the base material layer in the fold portion is preferably lower than the porosity of the base material layer in the region other than the fold portion. As described above, in the present invention, it is preferable to form the flap portion of a predetermined shape by heating and pressing a part of the printing paper, but in this case, the porosity of the porous layer of the base material layer is reduced. By reducing the porosity of the porous layer in the hinge portion, the strength of the hinge portion can be increased or the opacity can be reduced.

In the printing paper according to the present invention, the porosity of the base material layer in the region other than the hinge portion is preferably 10 to 45%. This enables formation of a flap portion having a preferable shape. That is, if the porosity of the base material layer is too low, the base material layer is less likely to be crushed even when heated and pressurized, and it is therefore difficult to obtain a folded portion having a desired depth. On the other hand, if the porosity of the base material layer is too high, the paper may be damaged or it may be difficult to maintain the strength of the fold portion when the fold portion is formed by heating and pressing. Therefore, the porosity of the base material layer is suitably set to the above range.

In the printing paper according to the present invention, it is preferable that the clark stiffness (S value) at the hinge portion is 10 to 250, and the clark stiffness (S value) at the region other than the hinge portion is 15 to 500. Further, the clark stiffness (S value) of the hinge portion is lower than that of the other regions. As in the above configuration, the clarke stiffness (S value) of the hinge portion is set to 10 to 250, whereby the hinge portion can be easily and naturally bent and can be provided with strength capable of withstanding repeated bending. Further, by setting the clarke stiffness (S value) of the region other than the hinge portion (particularly, the printing portion) to a high value of 15 to 500, the left and right pages are easily and naturally flattened when the sheets are opened, and thus the printing sheet can be suitably used for the purpose of an album.

In the printing paper according to the present invention, the fold portion is preferably formed in a straight line parallel to one side of the rectangular printing paper. In addition, it is preferable that a region (reinforcing portion) where the fold portion is not formed is present between the other two sides orthogonal to one side of the printing sheet parallel to the fold portion and the fold portion in the printing sheet. When printing on a printing sheet, by providing a reinforcing portion between the folding portion and the edge of the printing sheet, the printing sheet can be prevented from being accidentally bent or bent, and therefore, accurate printing processing can be performed. In addition, when binding printed sheets, the printed sheets are easily folded at the folding portion by cutting out the reinforcing portion. In this way, the reinforcing portion is provided on the printing paper on the premise that the reinforcing portion is finally cut off.

Effects of the invention

According to the present invention, printing can be easily performed even around the folding portion of the printing paper, and printing of the right and left pages is seamlessly continuous and easily visible when the printing paper is opened in a half-open manner.

Drawings

Fig. 1 is a plan view schematically showing a printing sheet according to an embodiment of the present invention. Fig. 1 (a) shows a printed sheet before printing, fig. 1 (b) shows a cut portion of the printed sheet by a one-dot chain line, and fig. 1 (c) shows a state in which a reinforcing portion between a folding portion and an edge of the printed sheet is cut.

Fig. 2 schematically shows a cross-sectional configuration at line II-II shown in fig. 1. Fig. 2 (a) shows a pattern in which concave folds are formed on one side of a printing sheet, and fig. 2 (b) shows a pattern in which concave folds are formed on both sides of a printing sheet. Fig. 2 (c) shows a pattern in which the bottom surface of the hinge portion has a semicircular shape in cross section as a modification of fig. 2 (a).

Fig. 3 schematically shows a method of the suitability evaluation test of the folded portion of the printing paper.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and includes embodiments modified as appropriate within a range that is obvious to those skilled in the art from the following embodiments.

In the present specification, "a to B" means "a to B inclusive".

Fig. 1 is a plan view schematically showing a printing sheet 10 according to an embodiment of the present invention. The printing sheet 10 can print characters or images on its surface and back. In particular, the printing paper 10 according to the present embodiment is expected to be used for printing photographic images on both the front and back sides. A plurality of printing sheets 10 on which photo images are printed are stacked, and one end portion of each printing sheet 10 is bound together, whereby an album (booklet) can be created.

As shown in fig. 1 (a), the printing paper 10 has a linear fold 11 recessed in the thickness direction. That is, the paper thickness of the printing paper 10 is reduced only at the folding portion 11, and the paper thicknesses of the other regions are substantially equal. In this way, the printing paper 10 has a feature that the paper thickness of the folding portion 11 is smaller than that of the other regions, and therefore the printing paper is easily folded along the folding portion 11.

The folding portion 11 extends in parallel with one side of the printing paper 10 in the vicinity of the one side. Specifically, the printing paper 10 according to the present embodiment is rectangular, and has two

short sides

10a and 10b and two

long sides

10c and 10d orthogonal to these. Since the printing paper 10 of the present embodiment is intended to be used in the lateral direction, the flap 11 is formed in the vicinity of one of the shorter sides 10b of the four sides of the printing paper 10. When the printing paper 10 is used in the portrait orientation, the fold 11 may be formed near either of the

long sides

10c and 10 d.

The printing sheet 10 is provided with a binding portion 13 between the folding portion 11 and one of the short sides 10b near the folding portion 11, and a printing portion 12 between the folding portion 11 and the other short side 10 a. The printing unit 12 is an area for printing characters or images, and occupies most of the printing paper 10. The binding section 13 is a region for binding the printing sheets 10 together when the plurality of printing sheets 10 are stacked and bound. For example, an adhesive such as a hot melt adhesive may be applied to the binding portion 13 of each printing sheet 10 to join the short sides of each printing sheet 10. Further, small holes may be bored at a plurality of positions so as to penetrate through the binding portion 13 of each printing paper 10, and small screws (binding screws) may be inserted into the respective small holes to connect the printing papers 10. The binding portions 13 of the respective printing sheets 10 may be bound together by a thread, a wire, a staple, or the like. The binding method is not limited to the method described herein, and a known method can be appropriately used. The width of the binding part 13 may be appropriately adjusted according to the binding method, and may be set to 5 to 50mm, for example.

In the printing paper 10 before printing, a reinforcing portion 14 in which no recess is formed is provided between the folding portion 11 recessed in a concave shape and the two

long sides

10c and 10 d. That is, the paper thickness of the reinforcing portion 14 is substantially equal to the paper thickness of the region other than the hinge portion 11. In other words, the paper thickness of the reinforcing portion 14 is larger than that of the folding portion 11. The width of the reinforcing part 14 (the gap between the hinge 11 and the

long sides

10, 10d) is preferably 1 to 20mm, and particularly preferably 2 to 10 mm. In this way, in the printing paper 10 before printing, by providing the reinforcing portions 14 on both ends in the longitudinal direction of the folding portion 11, the printing paper 10 is not easily bent when the printing paper 10 is set in the printer, and thus printing can be performed accurately.

The printed printing paper 10 is cut at a position indicated by an alternate long and short dash line in fig. 1 (b), that is, along a cutting line extending parallel to the

long sides

10c and 10d of the printing paper 10 so as to cross both ends in the longitudinal direction of the folding portion 11. Thereby, the reinforcing portions 14 located on both longitudinal end sides of the flap 11 are cut off. As shown in fig. 1 (c), the printed paper 10 after cutting has the fold 11 extending to the two

long sides

10c and 10 d. In this way, in the cut printing paper 10, the fold 11 extends in parallel with one side (10b) of the rectangular printing paper 10 between the two sides (10c, 10d) orthogonal to the one side (10b) in the vicinity of the one side (10 b). This makes it easy to fold the printing paper 10 along the folding portion 11.

Fig. 2 schematically shows a cross-sectional configuration at line II-II shown in fig. 1. Fig. 2 shows a pattern in which the folding portion 11 is formed by providing the concave portion on one surface of the printing paper 10 ((a) of fig. 2), and a pattern in which the folding portion 11 is formed by providing the concave portion on both surfaces of the printing paper 10 ((b) of fig. 2). As a feature common to both patterns, the printed paper 10 has a structure in which a base layer a including a porous layer and printing layers B1 and B2 provided on both surfaces of the base layer a are laminated in the thickness direction. In the present embodiment, printing processes are assumed to be performed on both sides of the printing paper 10, and therefore, the printing layers B1 and B1 are laminated on both front and back sides of the base layer a. However, when printing is performed only on one side of the printing paper 10, a printing layer may be laminated only on one side of the base material layer a. As shown in fig. 2 (c), the bottom surface of the hinge 11 may have a semicircular cross section.

In the present invention, the base layer a is formed of a thermoplastic resin film. By using a thermoplastic resin film as the base layer a, the printing paper 10 can be provided with mechanical strength such as hardness, water resistance, chemical resistance, opacity, and the like as needed.

The thermoplastic resin used for the base layer a is not particularly limited, and examples thereof include: polyolefin resins such as polyethylene resins and polypropylene resins; polyester resins such as polyethylene terephthalate and polylactic acid; polyamide resins such as nylon-6, 6 and nylon-612; styrene resins such AS polystyrene, acrylonitrile-styrene (AS) copolymer, and styrene-butadiene (SBR) copolymer; a polyvinyl chloride resin; a polycarbonate resin; polyphenylene sulfide, and the like. These resins may be used in combination of two or more. Among them, the thermoplastic resin constituting the base layer a is preferably a polyolefin resin from the viewpoint of having both strength and flexibility capable of withstanding repeated bending of the folded portion. In particular, from the viewpoint of film formability, a polypropylene resin is more preferably used among polyolefin resins. Examples of the polypropylene resin include isotactic polypropylene and syndiotactic polypropylene obtained by homopolymerizing propylene, and polypropylene copolymers having various stereoregularity obtained by copolymerizing ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and other α -olefins mainly composed of propylene. The polypropylene copolymer may be a binary or ternary or higher-order copolymer, and may be a random copolymer or a block copolymer.

To adjust stiffness, whiteness, and opacity, substrate layer a may contain fillers. Examples of the filler include inorganic fillers such as calcium carbonate and organic fillers such as resin particles, and these may be used alone or in combination. When the thermoplastic resin film containing a filler is stretched, a large number of fine pores with the filler as a core are formed in the base material layer a. This makes it possible to achieve whitening, opacity, and weight reduction of the base material layer a. In this way, the base material layer a contains the filler, and the porous layer is formed therein.

The average particle size of the filler is preferably large from the viewpoint of ease of mixing with the thermoplastic resin, and is preferably small from the viewpoint that when voids are generated inside by stretching, defects such as sheet breakage during stretching or a decrease in strength of the base material layer a are less likely to occur. Specifically, it is preferably 0.01 μm or more, more preferably 0.1 μm or more, and still more preferably 0.5 μm or more. Further, it is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less. The average particle size of the filler can be determined as an average dispersed particle size when the filler is dispersed in the thermoplastic resin by melt kneading and dispersing, by measuring the maximum diameter of at least 10 particles by observing the cut surface of the base material layer a with an electron microscope.

From the viewpoint of obtaining a desired porosity, the content of the filler in the base material layer a is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and further preferably 45% by mass or less, more preferably 40% by mass or less, further preferably 35% by mass or less.

The base layer a may optionally contain known additives as needed. The base layer a may have a single-layer structure or a multilayer structure. In the case of a multilayer, by providing the entire surface printing layer or the pigment-containing layer as a concealing layer on the inside, the printing on the other surface does not penetrate when viewed from one surface, and the visibility in both surface printing can be improved, whereby a recording sheet suitable for a printing sheet of a photographic image or the like can be obtained.

The porosity indicating the ratio of voids in the base material layer a at the portion where the fold portion 11 is not formed (particularly, the printed portion 12) is preferably 10% or more, more preferably 12% or more, further preferably 15% or more, and particularly preferably 20% or more. The porosity of the printed portion 12 is preferably 45% or less, more preferably 44% or less, further preferably 42% or less, and particularly preferably 40% or less.

The porosity can be measured by observing the cross section of the base material layer with an electron microscope, as described in jp 2019-48433 a. Specifically, the porosity can be determined from the ratio of the area occupied by pores in a certain region of the cross section of the printed paper observed with an electron microscope. Specifically, any part of the printed paper is cut, embedded in an epoxy resin, cured, and then cut perpendicularly to the plane direction of the substrate with a slicer, and attached to the observation sample stage so that the cut surface becomes the observation surface. Gold, gold-palladium, or the like is evaporated on the observation surface, the pores are observed at an arbitrary magnification (for example, a magnification of 500 to 3000 times) that is easy to observe with an electron microscope, and the observed region is taken in as image data. The porosity can be obtained by performing image processing on the obtained image data with an image analysis device to obtain the area ratio of the pore portion. In this case, the porosity can be determined by averaging the measurement values of any 10 or more observation points.

The printing layers B1 and B2 are layers on which characters, images, and the like can be recorded by printing. The printed layer can be formed by corona treatment, flame treatment, plasma treatment, coating and drying of a coating material, extrusion lamination of a molten resin, or the like on the surface of the base material layer a. As the printing method for the printing layers B1 and B2, various printing methods such as an offset printing method, an ink jet method, an electrophotographic (laser) method, a thermal recording method, and a thermal transfer method can be used. In addition, the printed layer B1 or B2 may be provided in advance on one surface of the support film which is thinner and more flexible than the base material layer a and follows the base material layer a when a hinge portion described later is formed by the above-described method, and may be laminated on the base material layer a via an adhesive layer. For example, a layer made of an adhesive such as an aqueous adhesive, a solvent adhesive, or a hot-melt adhesive may be provided on the surface of the support film opposite to the printing layers B1 and B2 by a method such as coating, spreading, or melt extrusion molding to form an adhesive layer, and then the base layer a may be laminated on the adhesive layer. Further, after an adhesive layer is provided on the base material layer a, a support film having printing layers B1 and B2 on one surface may be laminated. Alternatively, the adhesive may be melt-extruded and pressure-bonded between the base layer a and the support film provided with the print layers B1 and B2 to laminate them.

In another embodiment, at least one of the printing layers B1 and B2 formed on one surface of the support film may be printed in advance and then laminated on the base layer a via an adhesive layer.

In the pattern shown in fig. 2 (a), a recess for forming the fold 11 is provided only on one side (front side) of the printing paper 10 having the above-described laminated structure. In order to form such a concave portion, it is preferable that the printing paper 10 is heated and pressed in the thickness direction by a press having a convex portion having a shape corresponding to the concave portion. The structure of the press machine is not particularly limited, and a known press machine can be suitably used. For example, the printing paper 10 may be introduced between a press roll having a heatable peripheral surface on which a convex portion of a predetermined shape is formed and an anvil roll having a flat peripheral surface. Alternatively, a flat plate may be used instead of the anvil roll. As described above, the base layer a of the printing paper 10 is formed of a thermoplastic resin film including a porous layer. Therefore, when the printing paper 10 is locally heated and pressed, the base material layer a is partially melted, and the pores in the porous layer are crushed, so that the volume of the pressed portion is reduced. Thereby, a recess is formed in the pressing portion, and the recess functions as the hinge 11.

In the pattern shown in fig. 2 (a), the width W of the recess functioning as the hinge 11 is preferably two times or more the depth D of the recess. Specifically, the lateral width W of the recess is preferably 2 to 5 times, and particularly preferably 2.1 to 4 times or 2.2 to 3 times, the depth D of the recess. By setting the lateral width W of the concave portion to be twice or more as large as the depth D, it is possible to avoid interference between the side walls of the concave portion when the printing paper 10 is folded at the center of the concave portion, and therefore, the printing paper 10 is easily folded naturally at the folding portion 11. The lateral width W of the recess is preferably 0.5 to 40mm, more preferably 1 to 30mm, and most preferably 2 to 20 mm. The depth D of the recess is preferably 40 to 400 μm, more preferably 60 to 350 μm, and most preferably 100 to 300 μm. As shown in fig. 2 (c), when the bottom surface of the recess has a semicircular cross section, the depth D of the recess means the depth of the deepest portion of the recess.

On the other hand, in the pattern shown in fig. 2 (b), a recess for forming the hinge portion 11 is provided on both the front surface and the back surface of the printing paper 10 having the above-described laminated structure. The two recesses are formed at the same position when viewed in the thickness direction of the printing paper 10. In order to form such a recessed portion, it is preferable that the printing paper 10 is heated and pressed in the thickness direction by a punch having a convex portion having a shape corresponding to the recessed portion, as in the pattern of fig. 2 (a). The structure of the press machine is not particularly limited, and a known press machine can be suitably used. For example, the printing paper 10 may be introduced between two press rollers having a heating-enabled circumferential surface formed with a convex portion of a predetermined shape, and the printing paper 10 may be sandwiched between the convex portions of the press rollers. Thereby, a concave portion is formed in the pressing portion, and the concave portion functions as the hinge portion 11.

In the pattern shown in fig. 2 (b), the lateral width W1 of the recess formed on the front surface and the lateral width W2 of the recess formed on the back surface are preferably equal to each other, but may be different from each other. For example, the lateral width W1 of the front surface concave part is preferably 90 to 110% or 95 to 105% relative to the lateral width W2 of the back surface concave part, but may be 10 to 95% or 50 to 90%, for example. By making the lateral widths W1, W2 of the concave portions on the front and back surfaces different, the printing paper 10 can be easily folded in a certain direction. Similarly, the depth D1 of the concave portion formed on the front surface and the depth D2 of the concave portion formed on the back surface are preferably equal to each other, but may be different from each other. For example, the depth D1 of the concave portion on the front surface is preferably 90 to 110% or 95 to 105% of the depth D2 of the concave portion on the back surface, but may be, for example, 10 to 95% or 50 to 90%. By making the depths D1 and D2 of the recesses on the front and back surfaces different, the printing paper 10 can be easily folded in a certain direction.

In the pattern shown in fig. 2 (b), the lateral widths W1 and W2 of the recesses functioning as the hinges 11 are preferably twice or more of the depths D1 and D2 of the recesses, respectively. Specifically, the lateral widths W1, W2 of the recess are preferably 2 to 5 times, and particularly preferably 2.1 to 4 times or 2.2 to 3 times, respectively, of the depths D1, D2 of the recess. The lateral widths W1 and W2 of the concave parts are only required to be 0.5 to 40mm, preferably 1 to 30mm, and particularly preferably 2 to 20 mm.

In both the patterns of fig. 2 (a) and 2 (b), the paper thickness T of the portion where the fold 11 is formed is naturally smaller than the paper thickness P of the other region where the fold 11 is not formed (particularly, the printing portion 12). The paper thickness T of the folding portion 11 is preferably 10 to 85%, more preferably 40 to 80%, and particularly preferably 50 to 75% of the paper thickness P of the other region. By setting the paper thickness T of the folding portion 11 within the above range, both the ease of folding the printing paper 10 and the strength of the printing paper at the folding portion 11 can be satisfied. When the printing paper 10 is assumed to be used for an album, a certain thickness is required to suppress the deflection of the paper. Therefore, the paper thickness P of the printing paper is preferably 80 to 600 μm. The paper thickness P is more preferably 100 to 500 μm, particularly preferably 150 to 450 μm. As shown in fig. 2 (c), when the bottom surface of the recess has a semicircular cross section, the paper thickness T at the portion where the fold 11 is formed means the paper thickness at the deepest portion of the recess.

The stiffness of the printing portion 12 of the printing paper 10 is preferably in the range of 15 to 500, more preferably in the range of 40 to 400, and particularly preferably in the range of 80 to 300 in both the MD (flow direction) and TD (width direction) as the clark stiffness (S value) (hereinafter simply referred to as "clark stiffness") measured according to JIS-P-8143. If the clarke stiffness of the printing paper 10 is within the above range, stable on-press traveling performance without trouble can be obtained. When the clarke stiffness is less than 15 in both MD and TD directions, there is a possibility that a paper feed failure such as a paper deflection or a double feed may occur in the paper feed portion of the printing press. In addition, the printing paper tends to be wrinkled. Conversely, if the stiffness exceeds 500, the paper may not follow the running section of the printing press and may be disturbed, or it may be difficult to perform high-speed printing, or if the stiffness is too high, the blanket may be damaged by paper jam. Regardless of the grain direction of the printing paper 10, if the clarke stiffness is within the above range in both MD and TD, the degree of freedom of the imposition of printing is improved, and it is more preferable in practice in the printing process.

The clarke stiffness of the fold 11 of the printing paper 10 is preferably in the range of 10 to 250, more preferably in the range of 20 to 200, and particularly preferably in the range of 50 to 150 in both the MD and TD directions. The clark stiffness of the folding portion 11 is naturally lower than that of the printing portion 12, but by being limited to the above range, strength capable of withstanding repeated bending is maintained, and the left and right pages are easily and naturally maintained in a flat state when opened in a half-opened state in a state of being bound into a booklet. That is, if the clarke stiffness of the hinge portion 11 is less than 10, the strength of the paper surface becomes weak, and the paper surface may be broken during repeated bending. On the other hand, if the clark stiffness of the folding portion 11 exceeds 250, it is difficult to fold the printing paper 10 at the folding portion 11, and it is difficult to maintain a state of being opened in a half-opened manner after binding into a booklet. Therefore, by adjusting the clark stiffness of the folding portion 11 to the above range, the usability of the booklet made using the printing paper 10 can be improved.

The porosity of the base material layer a in the fold 11 of the printing paper 10 is lower than the porosity of the base material layer a in other regions (particularly, the printing section 12). For example, when the porosity of the printing portion 12 is 100%, the porosity of the folding portion 11 is preferably 0 to 90%, more preferably 5 to 60%, and particularly preferably 10 to 50%. Specifically, the porosity of the folded portion 11 measured by the above method is preferably 0 to 20%, more preferably 1 to 10% or 1 to 5%. Since the density of the base material layer a in the fold portion 11 is increased by reducing the porosity of the fold portion 11 as compared with other portions, the strength of the fold portion 11 can be maintained accordingly. That is, the thickness of the folded portion 11 is smaller than that of the other portions, and therefore a decrease in strength associated therewith is inevitable, but the tendency of the decrease in strength associated with the decrease in thickness can be alleviated by increasing the density of the resin by decreasing the porosity of the base material layer a in the folded portion 11.

The opacity of the printed paper 10 at the fold 11 is preferably lower than the opacity of the other regions (especially the printed portion 12). That is, the printing section 12 needs to increase opacity in order to clearly display characters and images and to prevent printing on the opposite surface side from transmitting. On the other hand, when a plurality of printing sheets 10 are stacked, the position alignment of the folding portions 11 of the printing sheets 11 becomes easy by making the opacity of the folding portions 11 relatively low (that is, making the folding portions 11 translucent). In addition, when the printing paper 10 is set in a printer, the folding portion 11 and the printing portion 12 of the printing paper 10 may be recognized in the printer, and an image or the like may be printed on the printing portion 12. In this case, the opacity of the folding portion 11 is reduced to cause a difference from the opacity of the printing portion 12, and the folding portion 11 and the printing portion 12 are easily distinguished by an image sensor in the printer, for example. For example, when the opacity of the printed portion 12 is 100%, the opacity of the folded portion 11 is preferably 10 to 95%, more preferably 20 to 90%, and particularly preferably 30 to 80%. Specifically, the opacity of the folded portion 11 is preferably 80% or less, and particularly preferably 75% or less or 70% or less, when measured by the opacity measurement method defined in JIS-P-8149. On the other hand, when measured by the same measuring method, the opacity of the printed portion 12 is preferably 85% or more, and particularly preferably 87% or more or 89% or more.

[ examples ] A method for producing a compound

The following verification is performed on the printing paper according to the present invention in order to obtain an appropriate ratio of the paper thickness T of the fold portion to the paper thickness P of the printing paper (see fig. 2 for each symbol).

Specifically, as the printing paper, in examples 1 to 3 and comparative example 1, a polyolefin synthetic paper "YPI 250" (paper thickness 250 μm, Clark stiffness (S value) MD: 180, TD: 370) manufactured by Yupo Corporation was used. In examples 4 to 9 and comparative example 2, polyolefin synthetic paper "Ultra Yupo (R) FEB 250" (thickness 250 μm, Clark stiffness (S value) MD: 210 and TD: 439) manufactured by Yupo Corporation was used. The printing paper was cut into a rectangular shape having a TD direction of 21cm and an MD direction of 30cm, and sandwiched between silicon release papers, and a folded portion having a width of 5mm parallel to the TD direction was formed from one end portion to the other end portion of one surface of the printing paper by hot pressing at 140 ℃ and 0.1 MPa. The width of the binding portion was set to 10mm, and the depth of the folding portion was adjusted so that "the ratio of the paper thickness of the folding portion to the paper thickness of the printing paper" became the value shown in table 1. For the obtained printing sheet with a folded portion, the sheet thickness T of the folded portion, the ratio of the sheet thickness T of the folded portion to the sheet thickness P of the printing sheet, and the clark stiffness (S value) in the TD direction were measured, respectively. In addition, for each example and each comparative example, the folding suitability was evaluated by the following method. The results are shown in table 1.

[ evaluation criteria for folding suitability ]

Fig. 3 shows a method of the fitness evaluation test of the folding portion. The end of the produced printed sheet with the folded portion on the side of the binding portion was fixed by a fixing member, and after the printed sheet was raised in the vertical direction, the angle formed between the binding portion and the printing portion when the hand was released was measured (test 1). Further, the fracture of the folding portion was confirmed when the operation of strongly bending the binding portion and the printing portion at an angle of 180 ° to 0 ° was repeated 50 times (test 2). From the results of test 1 and test 2, the flexibility of the fold portion was evaluated as follows.

A: the angle formed by the binding part and the printing part is less than 90 degrees, and the binding part can not be broken after being repeatedly bent.

B: the angle formed by the binding part and the printing part is larger than 90 degrees and less than 135 degrees, and the binding part can not be broken after being repeatedly bent.

C: the angle formed by the binding part and the printing part is larger than 90 degrees and less than 135 degrees, and after repeated bending, cracks are slightly generated in the folding part.

D: the angle formed by the binding part and the printing part is more than 135 degrees. Alternatively, although the angle formed by the binding portion and the printing portion is 90 ° or less, cracks are generated in the folding portion after repeated bending.

[ TABLE 1 ]

As shown in the above test results, when the paper thickness P of the printing paper is 250 μm, the bending performance of the printing paper at the fold portion becomes a practical level by setting the ratio of the paper thickness T of the fold portion to the paper thickness P of the printing paper to a range of about 10 to 85%, specifically about 38 to 80%. In particular, by setting the ratio to a range of about 40 to 80%, specifically about 44 to 80%, the following effects are confirmed: the folding portion of the printing paper is provided with strength capable of enduring repeated bending, and the left and right pages are naturally flattened when the printing paper is in the folio state. The effect is more remarkable by setting the ratio to a range of about 50 to 75%, specifically about 52 to 72%.

In the present specification, embodiments and examples of the present invention have been described above with reference to the accompanying drawings in order to represent the contents of the present invention. However, the present invention is not limited to the above-described embodiments and examples, and includes modifications and improvements that are obvious to those skilled in the art based on the matters described in the present specification.

Industrial applicability

The present invention relates to a printing sheet having a fold. When the printing paper according to the present invention is used, a booklet (e.g., an album) can be created in which the printing of the right and left pages is seamlessly continuous when the booklet is opened in a half-open manner and easily viewed. Therefore, the present invention can be suitably used in, for example, printing industry or paper industry.

Description of the symbols

10 … printing sheet

10a, 10b … short side

10c, 10d … Long side

11 … hinge part

12 … printing part

13 … binding part

14 … Reinforcement

A … base material layer

B (B1, B2) … printing layer.

Claims

1. A printing paper having a printing layer laminated on at least one surface of a base material layer, the base material layer being a thermoplastic resin film comprising a porous layer,

the printing paper has a linear folded portion recessed in a thickness direction of the printing paper.

2. The printing sheet of claim 1,

the thickness of the paper in the region other than the hinge part is 80 to 600 μm,

the thickness of paper at the fold is 10-85% of the thickness of paper at a region other than the fold.

3. The printing sheet of claim 1,

the width of the hinge part is more than twice of the depth of the hinge part.

4. The printing sheet of claim 1,

the base layer is formed of a polyolefin resin.

5. The printing sheet of claim 1,

the porosity of the base material layer in the flap portion is lower than the porosity of the base material layer in a region other than the flap portion.

6. The printing sheet of claim 5,

the porosity of the base material layer in a region other than the hinge portion is 10-45%.

7. The printing sheet of claim 1,

the S value which is the Clark stiffness at the folding part is 10-250,

the S value, which is the Clark stiffness, in the region other than the hinge portion is 15 to 500.

8. The printing sheet of claim 1,

the folding portion is formed in a straight line parallel to one side of the rectangular printing paper,

an area where the fold portion is not formed exists between the other two sides orthogonal to the one side and the fold portion.