Kulpack paper and paper processed products

Abstract

To provide Clukpak paper which has high extensibility, and prevents breakage and wrinkles at four corners thereof when molded into a tray shape.SOLUTION: Clupak paper has a paper base material containing pulp, wherein specific tensile stiffness in a longitudinal direction of the Clupak paper which is measured according to ISO / DIS 1924-3 is 1.5 kN m / g to 6.0 kN m / g, specific tensile stiffness in a lateral direction of the Clupak paper is 2.0 kN m / g to 6.0 kN m / g, a ratio (longitudinal direction / lateral direction) of the specific tensile stiffness in the longitudinal direction to the specific tensile stiffness in the lateral direction is 1.1 or less, elongation at break in the longitudinal direction of the Clupak paper which is measured according to JIS P 8113:2006 is 5.0% to 10.0%, and elongation at break in the lateral direction of the Clupak paper is 6.0% to 10.0%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to Kurapak paper and paper processed products.

Background Art

[0002] Conventionally, as packaging paper, Kurapak paper having stretchability imparted by finely shrinking the paper during papermaking has been used. As Kurapak paper, for example, Patent Document 1 discloses Kurapak paper that is difficult to break even in heavy packaging applications by controlling the specific tensile strength in the longitudinal and transverse directions.

[0003] On the other hand, for packaging containers such as food trays and packaging bodies such as pillow packaging bags, mainly plastic materials have been used. However, due to concerns about the environment, research has been conducted on packaging materials using paper instead of plastic containers.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For the production of a packaging body using paper, a material having stretchability is preferable from the viewpoint of formability. The inventors of the present invention attempted to form a food tray using conventional Kurapak paper as in Patent Document 1, but it has been found that wrinkles are likely to occur at the four corners of the tray, and furthermore, it may tear. The present disclosure relates to Kurapak paper having high stretchability and being less likely to tear and wrinkle at its four corners even when formed into a tray shape.

Means for Solving the Problems

[0006] That is, the present disclosure relates to the following <1> to <6>. <1>A Kurapak paper having a paper base material containing pulp, The specific tensile strength in the longitudinal direction of the Kurapak paper, measured in accordance with ISO / DIS 1924-3, is 1.5 kN·m / g to 6.0 kN·m / g, the specific tensile strength in the transverse direction of the Kurapak paper is 2.0 kN·m / g to 6.0 kN·m / g, and the ratio (longitudinal direction / transverse direction) of the specific tensile strength in the longitudinal direction to the specific tensile strength in the transverse direction is 1.1 or less. The elongation at break in the longitudinal direction of the Kurapak paper, measured in accordance with JIS P 8113:2006, is 5.0% to 10.0%, and the elongation at break in the transverse direction of the Kurapak paper is 6.0% to 10.0%. A Kurapak paper characterized by this. <2>The Kurapak paper according to <1>, wherein the ratio (longitudinal direction / transverse direction) of the specific tensile strength in the longitudinal direction to the specific tensile strength in the transverse direction is 0.7 to 1.0. <3>The Kurapak paper according to <1> or <2>, wherein the fiber orientation ratio measured in accordance with JIS Z0203 is 1.0 to 2.0. <4>The basis weight of the paper base material is 50 g / m 2 ~100 g / m 2 The Kurapak paper according to any one of <1> to <3>. <5>The Kurapak paper according to any one of <1> to <4>, wherein the Kurapak paper has a thermoplastic resin layer on at least one surface of the paper base material. <6>A paper processed product which is a molded body of the Kurapak paper according to any one of <1> to <5>.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a Kurapak paper having high extensibility and being less likely to have tears and wrinkles at its four corners even when molded into a tray shape.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0009] In the present disclosure, the description of "X or more and Y or less" or "X to Y" representing a numerical range means a numerical range including the lower limit and the upper limit which are the endpoints, unless otherwise specified. When numerical ranges are described stepwise, the upper and lower limits of each numerical range can be arbitrarily combined. The longitudinal direction is the papermaking direction (MD) in the paper base material and is the same as the direction in which the fibers are oriented. The transverse direction is the direction perpendicular (CD) to the papermaking direction.

[0010] As described above, the Kurpack treatment is a treatment for imparting stretchability by slightly shrinking the paper on the paper machine. Specifically, for example, a Kurpack device equipped with an endless thick elastic rubber blanket with nip rolls is installed in a part of the paper machine dryer. The wet paper web is introduced into the Kurpack device and compressed by the nip rolls and the blanket. At this time, the blanket that has been stretched in advance shrinks, thereby shrinking the running paper web (crepe application), and the elongation at break can be increased. The resulting shrinkage is dried and fixed so as not to stretch in the subsequent process.

[0011] The inventors have found that the above problems can be solved by controlling the specific tensile stiffness and elongation at break by the Kurpack treatment when manufacturing the paper base material. The tensile stiffness represents the firmness of the paper, and the elongation at break indicates the ease of stretching of the paper. The fact that the Kurpack paper has the above specific tensile stiffness and elongation at break indicates that it has an appropriate firmness and is somewhat easy to stretch. In particular, when the value of the tensile stiffness in the CD direction (transverse direction) is about the same as the value of the tensile stiffness in the MD direction (longitudinal direction), or the value in the CD direction is larger, the stretchability is high, and even when formed into a tray shape, the inventors believe that a Kurpack paper in which tearing and wrinkling are less likely to occur at its four corners can be obtained.

[0012] The specific tensile strength in the longitudinal direction of the Kurapak paper, measured in accordance with ISO / DIS 1924-3, should be 1.5 kN·m / g to 6.0 kN·m / g, and the specific tensile strength in the transverse direction of the Kurapak paper should be 2.0 kN·m / g to 6.0 kN·m / g. If the specific tensile strength is less than the above lower limit, excessive stress will be applied during forming, making wrinkles and tears likely to occur. On the other hand, if the specific tensile strength exceeds the above upper limit, the pressure required for forming will become too high, making it difficult to form, and wrinkles and tears are likely to occur if forced forming is attempted.

[0013] The specific tensile strength can be controlled by the speed difference before and after Kurapak treatment, the J / W ratio during papermaking, the adjustment of density by nip pressure during calendar treatment, the type of pulp, etc. To increase the specific tensile strength, methods such as reducing the speed difference before and after Kurapak treatment, increasing the density by increasing the nip pressure during calendar treatment, and increasing the fiber length of the pulp can be mentioned. On the other hand, to decrease the specific tensile strength, methods such as increasing the speed difference before and after Kurapak treatment, decreasing the density by decreasing the nip pressure during calendar treatment, and decreasing the fiber length of the pulp can be mentioned.

[0014] The specific tensile strength in the longitudinal direction of the Kurapak paper is preferably 1.5 kN·m / g to 4.5 kN·m / g, more preferably 1.5 kN·m / g to 4.0 kN·m / g. The specific tensile strength in the transverse direction of the Kurapak paper is preferably 2.0 kN·m / g to 5.0 k N·m / g, more preferably 2.3 kN·m / g to 4.0 kN·m / g.

[0015] The ratio of the specific tensile strength in the longitudinal direction to the specific tensile strength in the transverse direction (longitudinal direction / transverse direction) of the Kurapak paper is 1.1 or less. By satisfying the above range, Kurapak paper with high extensibility and less likely to have tears and wrinkles at its four corners even when formed into a tray shape can be obtained. From the perspective of obtaining a higher effect, it is preferably 0.7 to 1.0.

[0016] The breaking elongation in the longitudinal direction of the Kurapak paper, measured in accordance with JIS P 8113:2006, should be 5.0% to 10.0%, and the breaking elongation in the transverse direction of the Kurapak paper should be 6.0% to 10.0%. If the breaking elongation is less than the above lower limit, the elongation of the paper during forming is insufficient and it becomes difficult to form. Also, if an attempt is made to form forcibly, tearing will occur. On the other hand, if the breaking elongation exceeds the above upper limit, although forming is possible because the elongation is large, the paper becomes easy to move, wrinkles are likely to occur, and furthermore, tearing is likely to occur from there.

[0017] The breaking elongation can be controlled by basis weight, the speed difference before and after Kurapak processing, the nip pressure during Kurapak processing, etc. To increase the breaking elongation, methods such as increasing the basis weight, increasing the speed difference before and after Kurapak processing, and decreasing the nip pressure during Kurapak processing can be mentioned. On the other hand, to decrease the breaking elongation, methods such as decreasing the basis weight, decreasing the speed difference before and after Kurapak processing, and increasing the nip pressure during Kurapak processing can be mentioned.

[0018] The breaking elongation in the longitudinal direction of the Kurapak paper is preferably 7.0% or more, more preferably 8.0% or more. The upper limit of the breaking elongation in the longitudinal direction is preferably 9.7% or less, more preferably 9.0% or less. The breaking elongation in the transverse direction of the Kurapak paper is preferably 7.0% or more, more preferably 7.5% or more. The upper limit of the breaking elongation in the transverse direction is preferably 9.5% or less, more preferably 8.5% or less.

[0019] The ratio (longitudinal direction / transverse direction) of the breaking elongation in the longitudinal direction of the Kurapak paper to the breaking elongation in the transverse direction is preferably 1.01 or more, more preferably 1.03 or more, and even more preferably 1.05 or more. On the other hand, the upper limit is preferably 1.30 or less, more preferably 1.20 or less, and even more preferably 1.12 or less.

[0020] The fiber orientation ratio of the Kurapak paper, measured in accordance with JIS Z0203, is preferably from 1.0 to 2.0, more preferably from 1.1 to 1.8, and even more preferably from 1.2 to 1.6. If the value of the fiber orientation ratio is too small, it is presumed that the pulp is likely to be a mixture of vertical and horizontal directions and tends to form creases in both vertical and horizontal directions during molding. If the value of the fiber orientation ratio is too large, it is presumed that the pulp is oriented in the vertical direction and tends to form creases in the horizontal direction. Therefore, within the above numerical range, the formability can be improved. The fiber orientation ratio of the paper substrate can be controlled by the type of pulp used, the J / W ratio during papermaking, etc.

[0021] The basis weight of the paper substrate is preferably 50 g / m 2 ~100 g / m 2 more preferably 60 g / m 2 ~100 g / m 2 even more preferably 70 g / m 2 ~100 g / m 2 If the basis weight is too small, the strength is weak and it tends to break easily during molding. If the basis weight is too large, the strength is strong and it tends to form creases easily during molding. Therefore, within the above numerical range, the formability can be improved.

[0022] The thickness of the paper substrate is preferably 50 μm to 300 μm, more preferably 60 μm to 200 μm even more preferably 70 μm to 150 μm, and even more preferably 100 μm to 140 μm.

[0023] The density of the paper substrate is preferably 0.30 g / m 3 ~1.00 g / m 3 more preferably 0.40 g / m 3 ~0.90 g / m 3 even more preferably 0.50 g / m 3 ~0.90 g / m 3 even more preferably 0.60 g / m 3 ~0.85 g / m 3It is even more preferable that it is so.

[0024] Next, the materials that can be used for Kurapak paper will be described. Examples of the pulp constituting the paper base material include hardwood kraft pulp such as unbleached hardwood kraft pulp (LUKP) and bleached hardwood kraft pulp (LBKP); softwood kraft pulp such as unbleached softwood kraft pulp (NUKP) and bleached softwood kraft pulp (NBKP); mechanical pulp such as groundwood pulp (GP), pressurized groundwood pulp (PGW), refiner mechanical pulp (RMP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemimechanical pulp (CMP), and chemiground pulp (CGP); wastepaper pulp; non-wood fiber pulp such as kenaf, bagasse, bamboo, and cotton; and synthetic pulp. These pulps may be used alone or in combination of two or more.

[0025] The pulp preferably contains hardwood kraft pulp, more preferably contains unbleached hardwood kraft pulp, and even more preferably contains unbleached hardwood kraft pulp and unbleached softwood kraft pulp. It is preferable that the content of unbleached hardwood kraft pulp is greater than the content of unbleached softwood kraft pulp.

[0026] The content of softwood kraft pulp in the pulp is preferably 0% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 13% by mass or more. On the other hand, the upper limit is preferably 70% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, and even more preferably 47% by mass or less.

[0027] The content of hardwood kraft pulp in the pulp is preferably 25% by mass or more, more preferably 35% by mass or more, still more preferably 45% by mass or more, even more preferably 50% by mass or more, and even more preferably 53% by mass or more. On the other hand, the upper limit is preferably 100% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less, and even more preferably 87% by mass or less.

[0028] The beating degree of the pulp is not particularly limited, but as the Canadian Standard Freeness (CSF), 200 to 800 mL is preferable, and 450 to 700 mL is more preferable. The CSF is measured according to JIS P 8121-2:2012 "Pulp - Method for testing freeness - Part 2: Canadian standard freeness method".

[0029] Additives may be used for the paper base material as needed. Examples of the additives include pH adjusters (such as sodium hydrogen carbonate and sodium hydroxide), dry paper strengthening agents (such as polyacrylamide and starch), wet paper strengthening agents (any one of polyamide polyamine epichlorohydrin resin, melamine - formaldehyde resin, and urea - formaldehyde resin), internal sizing agents (such as rosin - based and alkyl ketene dimer), drainage yield improvers (such as polyacrylamide resin), defoaming agents, fillers (such as calcium carbonate and talc), dyes, and the like. These additives may be used alone or in combination of two or more. The content of the additives is not particularly limited and may be within the range commonly used.

[0030] 〔Method for manufacturing paper base material〕 As a method for manufacturing the paper base material, a papermaking method of making a paper stock containing pulp and performing a kurp treatment during papermaking can be mentioned. Note that the paper stock may further contain additives as needed. Examples of the additives include the above - mentioned additives. The paper stock can be prepared by adding additives to the pulp slurry as needed. The pulp slurry can be obtained by beating pulp in the presence of water. The beating method and beating device of the pulp are not particularly limited, and known beating methods and beating devices can be adopted. ​

[0031] The solid content concentration of the pulp slurry during beating is not particularly limited, but is preferably about 5 to 40% by mass, more preferably about 5 to 30% by mass. Further, the pulp content in the paper stock or paper base material is not particularly limited and may be within the range commonly used. For example, it is preferably 60% by mass or more and 100% by mass or less, more preferably 80% by mass or more and less than 100% by mass, based on the total mass of the paper stock (solid content) or paper base material.

[0032] In the papermaking of the paper base material, a known wet papermaking machine can be appropriately selected and used. Examples of the papermaking machine include a Fourdrinier papermaking machine, a gap former type papermaking machine, a cylinder papermaking machine, and a Duoformer papermaking machine. A Kurpack device capable of performing Kurpack treatment may be provided in these papermaking machines to perform Kurpack treatment. For example, after papermaking the paper stock and dehydrating it by calendar treatment, Kurpack treatment can be performed.

[0033] As the Kurpack device, a known one can be used. For example, a Kurpack device equipped with a nip roll and an endless thick elastic rubber blanket can be mentioned. As described above, in Kurpack treatment, when the paper web is carried between the nip roll and the blanket and the paper web is compressed by the nip roll and the blanket, the paper web is shrunk by shrinking the blanket that has been stretched in advance to impart crepe. The Kurpack device is usually provided as a part of the dryer device of the papermaking machine, and after creping, it is dried and fixed. In the above manner, a paper base material can be obtained.

[0034] In papermaking using a Kurpack device, the specific tensile strength and elongation at break can be controlled by the difference in papermaking speed before and after Kurpack treatment and the pressure of the nip roll. The papermaking speed is not particularly limited. For example, it may preferably be controlled within the range of 200 to 1000 m / min, more preferably 300 to 800 m / min, and even more preferably 400 to 700 m / min. The nip pressure between the nip roll and the blanket during the Kurpack treatment is also not particularly limited. For example, it may be appropriately controlled within the range of 5 kN / m to 50 kN / m, more preferably 10 kN / m to 25 kN / m. The speed difference before and after the Kurpack treatment is not particularly limited and may be controlled according to the basis weight and pulp material so as to obtain the desired specific tensile strength and elongation at break. Preferably, it is -45.0 m / min to -10.0 m / min, more preferably -40.0 m / min to -15.0 m / min. The minus "-" here indicates that the speed after the Kurpack treatment is slower.

[0035] In papermaking using a Kurpack apparatus, the jet / wire ratio (hereinafter also referred to as the J / W ratio) is not particularly limited. For example, it is preferably 1.00 or more and 1.50 or less, more preferably 1.00 or more and 1.30 or less, and even more preferably 1.00 or more and 1.20 or less.

[0036] The obtained paper base material can be used as Kurpack paper as it is. From the viewpoint of improving waterproofness and stain resistance, it is preferable to provide a laminate layer (thermoplastic resin layer) on at least one surface of the paper base material as needed. Also, other resin layers or the like may be provided on the Kurpack paper to such an extent that the above effects are not impaired. The Kurpack paper may have a thermoplastic resin layer on one surface of the paper base material or may have thermoplastic resin layers on both surfaces of the paper base material.

[0037] The thermoplastic resin used for the thermoplastic resin layer is not particularly limited as long as it can be laminated on the paper base material, and it may be appropriately selected from known thermoplastic resins without particular limitation. Specifically, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate; polyolefin resins such as polyvinyl chloride, polyvinylidene chloride, polybutene, polybutadiene, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, ethylene-propylene copolymer, polymethylpentene; polycarbonate; polyurethane; polyamide; polyacrylonitrile; poly(meth)acrylate, etc. may be mentioned.

[0038] Among these, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, and polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate are preferred. Polyethylene, polypropylene, polyethylene terephthalate, polylactic acid, polybutylene succinate are more preferred. Polyethylene and polypropylene are even more preferred, and polyethylene is even more preferred. In addition to the above materials, biomass resins or biodegradable resins may be used as the resin. These resins may be used alone or in combination of two or more.

[0039] The thermoplastic resin is preferably one that can be laminated on a sheet substrate as a laminate layer. Among thermoplastic resins, polyethylene is preferred because of its excellent extrusion lamination property and barrier property. Polyethylene (PE) is roughly classified into linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc. Among these, low-density polyethylene (LDPE) is preferred because of its excellent extrusion lamination property and foaming property.

[0040] The thermoplastic resin layer may be manufactured by appropriately selecting from known manufacturing methods. For example, it may be appropriately selected from among the melt extrusion method, the melt casting method, the calendar method, etc. The thickness of the thermoplastic resin layer is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and still more preferably 5 μm or more. On the other hand, the upper limit of the thickness is preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less.

[0041] The use of the obtained curpack paper is not particularly limited, and by appropriately forming it into a molded body, it can be used for paper processed products such as packaging papers, packaging bags, packaging containers, and various containers such as cups and trays. For example, it can be formed into paper containers such as paper plates, paper cups, and paper trays, and bags for horizontal pillow packaging, vertical pillow packaging, three-side seal packaging, four-side seal packaging, bag-in-box filling packaging, tube packaging, and stick packaging, and used. The method of forming is not particularly limited, and a known method can be adopted. For example, it can be formed into a desired shape by press molding.

[0042] Hereinafter, the measurement methods for each physical property will be described. <Specific Tensile Strength> The specific tensile strength in the longitudinal and transverse directions of the curpack paper is measured in accordance with ISO / DIS 1924-3. Specifically, it is as follows. Samples with a test piece length of 150 mm and a test piece width of 15 mm are prepared for both the longitudinal and transverse directions, and conditioned for 1 day in an environment of 23 ± 5°C and 50 ± 10% Rh. Then, in that environment, using a tensile testing machine (model RTC-1210A, manufactured by A&D Company, Limited), the samples are set so that the distance between the chucks is 100 mm, and the test is conducted at a speed of 100 mm / min.

[0043] <Elongation at Break> The elongation at break in the longitudinal and transverse directions of the curpack paper is measured in accordance with JIS P 8113:2006 (Test Methods for Tensile Properties of Paper and Paperboard). Specifically, as the temperature and humidity conditioning treatment, prepare a sample by cutting out Kurapak paper that has been left standing in an environment of 23 ± 5°C and 50 ± 10% for 1 day into a width of 15 mm and a length of 150 mm. Using a tensile testing machine (model RTC-1210A, manufactured by A&D Company, Limited), attach the sample so that the distance between the chucks is 100 mm, conduct a tensile test at a speed of 20 mm / min, and measure the elongation at break in the MD (longitudinal direction) and CD (transverse direction) respectively.

[0044] <Fiber orientation ratio of the paper substrate> The fiber orientation ratio of the paper substrate is measured in accordance with JIS Z0203. Specifically, prepare a sample cut into a 200 mm square, and as the temperature and humidity conditioning treatment, measure the paper substrate that has been left standing in an environment of 23 ± 5°C and 50 ± 10% for 1 day using a fiber orientation characteristic evaluation device (model SST-2500, manufactured by Nomura Shoji Co., Ltd.).

[0045] <Grammage> The grammage of the paper substrate is measured in accordance with JIS P 8124:2011. In addition, when the Kurapak paper has a resin layer in addition to the paper substrate, after identifying the material, thickness, density, etc. of the resin layer by known methods and the following procedure, the grammage of the paper substrate can be calculated. Specifically, measure the weight of the paper substrate provided with the resin layer cut into a predetermined size (total weight), and then immerse the paper substrate with the resin layer in an enzyme such as cellulase and confirm that the paper substrate is completely dissolved. Then, measure the weight of only the resin layer (resin layer weight), calculate the weight of only the paper substrate by subtracting the resin layer weight from the total weight, and measure the grammage of the paper substrate.

[0046] <Thickness> The thickness (paper thickness) of the paper substrate is measured in accordance with JIS P 8118:2014. When the Kurapak paper has a resin layer in addition to the paper substrate, measure the thickness of each of the paper substrate layer and the thermoplastic resin layer from the observation image of the electron microscope (SEM) of the cross-section of the Kurapak paper.

[0047] <Density> The density of the paper base material is calculated from the thickness and basis weight obtained by the above-described measurement method.

Example

[0048] The features of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited specifically by the specific examples shown below. Also, unless otherwise specified, "parts" represents "parts by mass". In addition, the operations in the examples and comparative examples were carried out under the conditions of room temperature (20 - 25°C) and normal humidity (40 - 50% RH) unless otherwise specified.

[0049] <Example 1> NUKP (softwood unbleached kraft pulp) and LUKP (hardwood unbleached kraft pulp) obtained by pulping (cooking) wood were used at a ratio (mass ratio) of 30:70, and beaten at a slurry concentration of 12% by mass during beating until the Canadian Standard Freeness (CSF) reached 600 mL to prepare pulp. Using the above pulp, 0.15 part by mass of a synthetic sizing agent (SPS400, manufactured by Arakawa Chemical Industries, Ltd.), 1.2 parts by mass of aluminum sulfate, 0.65 part by mass of a polyacrylamide resin (DS4433, manufactured by Seiko PMC Co., Ltd.) as a retention aid, and 0.035 part by mass of a nonionic polyacrylamide (Percol 47, manufactured by Allied Colloid) as a polymer flocculant (retention aid) were added based on 100 parts by mass of the pulp in terms of solid content to prepare a paper stock. Using the above paper stock, a wet paper machine (Bellform III type, manufactured by Mitsubishi Heavy Industries, Ltd.) equipped with a stretching device (manufactured by Kurpack) was used for papermaking at a papermaking speed of 600 m / min, a speed difference before and after Kurpack treatment of -35.0 m / min, a nip pressure between the nip roll and the blanket during Kurpack treatment of 15 kN / m, and a J / W ratio of 1.00, and crepe was imparted to the surface of the paper to obtain a paper base material with a basis weight of 80 g / m 2 The obtained paper base material was used as the Kurpack paper of Example 1.

[0050] <Example 2> The points where the slurry concentration during beating was set to 10% by mass, beating was continued until the CSF reached 550 mL, and the J / W ratio during papermaking was set to 1.05 were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0051] <Example 3> The points where the slurry concentration during beating was set to 8% by mass, beating was continued until the CSF reached 450 mL, and the J / W ratio during papermaking was set to 1.10 were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0052] <Example 4> The points where the slurry concentration during beating was set to 5% by mass, beating was continued until the CSF reached 400 mL, the speed difference before and after Kurapak treatment during papermaking was set to -20.0 m / min, and the J / W ratio during papermaking was set to 1.20 were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0053] <Example 5> The points where the slurry concentration during beating was set to 5% by mass, beating was continued until the CSF reached 400 mL, and the J / W ratio during papermaking was set to 1.20 were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0054] <Example 6> The points where the slurry concentration during beating was set to 5% by mass, beating was continued until the CSF reached 400 mL, and the J / W ratio during papermaking was set to 1.50 were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0055] <Example 7> The points where the slurry concentration during beating was set to 8% by mass, beating was continued until the CSF reached 450 mL, the J / W ratio during papermaking was set to 1.10, and LDPE was melt-extrusion coated on one side of the manufactured paper base material so that the coating thickness after drying was 20 μm were changed. Otherwise, Kurapak paper was obtained under the same conditions as in Example 1.

[0056] <Example 8> The points where the slurry concentration during beating was set to 8% by mass, beating was carried out until the CSF reached 450 mL, the J / W ratio during papermaking was set to 1.10, and LDPE was melt-extrusion coated on both sides of the produced paper substrate so that the coating thickness after drying became 10 μm were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0057] <Comparative Example 1> The points where the slurry concentration during beating was set to 10% by mass, beating was carried out until the CSF reached 650 mL, and the J / W ratio during papermaking was set to 1.10 were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0058] <Comparative Example 2> The points where the slurry concentration during beating was set to 8% by mass, beating was carried out until the CSF reached 550 mL, the speed difference before and after the Kurapak treatment during papermaking was set to -15.0 m / min, and the J / W ratio during papermaking was set to 1.10 were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0059] <Comparative Example 3> The points where the slurry concentration during beating was set to 8% by mass, beating was carried out until the CSF reached 330 mL, the speed difference before and after the Kurapak treatment during papermaking was set to -35.0 m / min, and the J / W ratio during papermaking was set to 1.10 were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0060] <Comparative Example 4> The points where the slurry concentration during beating was set to 2% by mass, beating was carried out until the CSF reached 450 mL, the speed difference before and after the Kurapak treatment during papermaking was set to -35.0 m / min, and the J / W ratio during papermaking was set to 1.10 were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0061] <Comparative Example 5> The points where the slurry concentration during beating was set to 2% by mass, beating was carried out until the CSF reached 350 mL, the speed difference before and after the Kurapak treatment during papermaking was set to -15.0 m / min, and the J / W ratio during papermaking was set to 1.10 were changed. Except for these changes, Kurapak paper was obtained under the same conditions as in Example 1.

[0062] <Comparative Example 6> A paper base material was obtained under the same conditions as in Example 1, except that the slurry concentration during beating was changed to 2% by mass, beating was continued until the CSF reached 300 mL, no Kurapak treatment was applied, and the J / W ratio during papermaking was changed to 1.10.

[0063] <Comparative Example 7> A Kurapak paper was obtained under the same conditions as in Example 1, except that the slurry concentration during beating was changed to 10% by mass, beating was continued until the CSF reached 500 mL, the speed difference before and after the Kurapak treatment during papermaking was changed to -48.0 m / min, and the J / W ratio during papermaking was changed to 1.10.

[0064] The following evaluations were carried out using the obtained Kurapak paper or paper base material. The obtained Kurapak paper or paper base material of the examples and comparative examples was cut out to obtain three A4 blank sheets with the longitudinal direction (MD) as the long side. Using the molding dies (1 and 2) and the press molding machine (FVT400, manufactured by Wakisaka Engineering Co., Ltd.), the blank sheets were pressed under the conditions of a press pressure of 35 kgf / cm 2 , a press temperature of 150 °C, and a press time of 5 seconds, and molded into the tray shape as shown in Fig. 2 as shown in Fig. 1. For the obtained trays, the presence or absence of wrinkles and breaks in the four-corner molded parts was evaluated according to the following criteria. As shown in Fig. 1, the tapered part of the opening of the tray was evaluated as the molded part 4 (broken line in the figure). The larger the numerical value, the better. 4: No breaks or wrinkles occur in the four-corner molded part. 3: No breaks occur in the four-corner molded part, but wrinkles occur. 2: Breaks occur in 1 to 3 places in the four-corner molded part. 1: Breaks occur in all of the four-corner molded parts.

[0065] Table 1 shows the physical properties and evaluation results of Examples 1 to 8 and Comparative Examples 1 to 7.

Table 1

Explanation of Symbols

[0066] 1,2: Mold for forming 3: Blank sheet 4: Four-corner forming part

Claims

1. A kurpack paper having a paper base material containing pulp, wherein the specific tensile strength in the longitudinal direction of the kurpack paper, measured in accordance with ISO / DIS 1924-3, is 1.5 kN·m / g to 6.0 kN·m / g, the specific tensile strength in the transverse direction of the kurpack paper is 2.0 kN·m / g to 6.0 kN·m / g, and the ratio (longitudinal direction / transverse direction) of the specific tensile strength in the longitudinal direction to the specific tensile strength in the transverse direction is 0.7 to 0.9; the elongation at break in the longitudinal direction of the kurpack paper, measured in accordance with JIS P 8113:2006, is 5.0% to 10.0%, and the elongation at break in the transverse direction of the kurpack paper is 6.0% to 10.0% A kurpack paper characterized by the above.

2. The kurpack paper according to Claim 1, wherein the fiber orientation ratio measured in accordance with JIS Z0203 is 1.0 to 2.

0.

3. The basis weight of the paper base material is 50 g / m ２ to 100 g / m ２ The Kurapak paper according to claim 1 or 2, wherein the basis weight is as defined above.

4. The kurpack paper according to any one of Claims 1 to 3, wherein the kurpack paper has a thermoplastic resin layer on at least one surface of the paper base material.

5. A paper processed product which is a molded body of the kurpack paper according to any one of Claims 1 to 4.

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