JP6196763B2 - Paperboard, cardboard sheet and box - Google Patents

Description

  The present invention relates to a paperboard, and a cardboard sheet and a box using the paperboard.

  Currently, paperboard is widely used in various fields. For example, it is often used as a material for corrugated cardboard sheets and boxes for transporting and packaging agricultural products, marine products, various industrial products, and the like. However, since the surface of the paperboard is usually flat and smooth, the box or cardboard obtained from the paperboard is easily slipped by shaking or vibration, which may cause load collapse.

  In order to solve such inconvenience, a paperboard has been developed in which a slip-proof layer containing a heat-foamable resin and a pigment is provided on the surface of the base paper and thermally foamed by a dryer in a drying process (see Patent Document 1). The use of the heat-foamable resin in Patent Document 1 causes heat-foaming at a predetermined temperature, and the surface of the anti-slip layer preferably has irregularities having a surface roughness test height (Ry) of 15.5 to 18.5 μm. In this way, an anti-slip effect is obtained. However, as described in Patent Document 1, the thermally foamable resin may cause gas to permeate and diffuse from the expanded and thin shell depending on the foaming condition, and the shell tension / external pressure may be higher than the internal pressure. The problem of shrinkage of the foamed particles occurs due to the increase in size, and the uneven state of the anti-slip layer varies, and the paperboard as a whole may not exhibit excellent anti-slip properties. Further, the foam is an independent microsphere, and when these are separated from the paperboard and dropped off, the slip resistance of the paperboard is lowered.

JP 2009-161871 A

  The present invention has been made in view of the above disadvantages, and an object thereof is to provide a paperboard excellent in slip resistance and wear resistance.

  As a result of intensive studies in order to solve the above-mentioned problems, the present inventor intentionally includes a thermal fusion product derived from a thermoplastic polymer constituting the outer shell of an already thermally expanded microcapsule, and the above By finding a suitable range of the arithmetic average roughness (Ra) of the anti-slip layer including the heat-sealed product, it was confirmed that a paperboard excellent in anti-slip and abrasion resistance could be provided, and the present invention was completed.

The invention made to solve the above problems is
A paperboard comprising a base paper and an anti-slip layer laminated on the surface of the base paper,
The anti-slip layer includes a heat-sealed product derived from a thermoplastic polymer constituting the outer shell of the already thermally expanded microcapsule, and the arithmetic average roughness (Ra) of the anti-slip layer surface is 1.0 μm or more and 6.0 μm or less. It is the board characterized by being.

  The paperboard is provided with a non-slip layer on the surface of the base paper containing a heat-sealed product derived from a thermoplastic polymer constituting the outer shell of the already thermally expanded microcapsule. In addition, by setting the arithmetic average roughness (Ra) of the surface of the anti-slip layer to 1.0 μm or more and 6.0 μm or less, the relatively uniform and strong convex portion derived from the heat-sealed product of the already thermally expanded microcapsule is anti-slip. Many can be provided on the surface of the layer. As a result, the paperboard further enhances the slip resistance and abrasion resistance of the antislip layer, and unlike the antislip layer containing only an independent preheated microcapsule alone, inadvertent bursting, destruction, separation of the preheated microcapsule, It is difficult for dropouts to occur, and it is possible to prevent the deterioration of the slip resistance over time.

  The average thickness of the anti-slip layer is preferably 10 μm or more and 35 μm or less. By setting the average thickness of the anti-slip layer in the above range, the heat-expandable microcapsules can be sufficiently foamed and heat-sealed by further heating, and suitable irregularities can be formed on the paperboard surface. . As a result, the slip resistance and abrasion resistance of the paperboard can be further improved.

  The sliding angle of the anti-slip layer is preferably 30 ° or more and 60 ° or less. The paperboard can improve such slip resistance easily and reliably.

Another invention made to solve the above problems is as follows:
A cardboard sheet comprising the paperboard as a front liner. The corrugated cardboard sheet is excellent in slip resistance and wear resistance.

Another invention made to solve the above problems is as follows:
It is a box formed from the paperboard or the cardboard sheet. The box is excellent in slip resistance and wear resistance.

  The paperboard of the present invention, and the corrugated cardboard sheet and paper using this paperboard are excellent in slip resistance and abrasion resistance as described above, and can prevent deterioration over time.

1 is an electron micrograph of the anti-slip layer surface of the paperboard according to Example 1. FIG.

  Hereinafter, embodiments of the paperboard, cardboard sheet, and box according to the present invention will be described in detail.

<Paperboard>
The paperboard includes a base paper and an anti-slip layer laminated on the surface of the base paper. In addition to the base paper surface, this anti-slip layer may be laminated on the back surface.

<Base paper>
The base paper is not particularly limited, and examples thereof include liner base paper. The base paper may be a single layer or a plurality of layers.

  The raw material pulp of the base paper is not particularly limited. For example, chemicals such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and softwood unbleached kraft pulp (NUKP) Pulp, ground pulp (GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP) and other mechanical pulp, corrugated wastepaper, liner wastepaper, magazine wastepaper, wastepaper waste paper, and old paper Waste paper pulp regenerated from the above, upper white waste paper pulp, deinked waste paper pulp, and the like.

  The manufacturing method of a base paper is not specifically limited, For example, making the paper containing the raw material pulp is mentioned. The paper making method is also not particularly limited, and examples thereof include a method having a wire part, a press part, a dryer part, a size press, a calendar part, and the like.

  When manufacturing the base paper, an external paper strength agent such as polyacrylamide may be applied to the surface of the base paper. In this case, the strength of the base paper can be further increased. When the external paper strength agent is applied to the surface of the base paper, the following anti-slip layer is formed on the impregnated layer of the external paper strength agent.

<Anti-slip layer>
The anti-slip layer includes at least a heat-fused product of the already thermally expanded microcapsules, so that a convex portion that is stronger and more excellent in anti-slip properties can be formed on the anti-slip layer compared to a single thermally expanded microcapsule alone. It can be suppressed more. In the case of preheated microcapsules, when the heating temperature is high or the heating time is long, the thermoplastic polymer constituting the outer shell of the heat expandable microcapsules is sufficiently softened so that the heat expandable microcapsules are heated with each other. It tends to fuse and become a heat-sealed product. The presence or absence of the heat-fused product can be confirmed with an electron micrograph, a real surface view microscope or the like. “Already thermally expanded microcapsules” refers to independent hollow microparticles obtained by foaming thermally expandable microcapsules by heating. “Thermal fusion material” is derived from a thermoplastic polymer constituting the outer shell of an already thermally expanded microcapsule and is integrated by thermally bonding a plurality of already thermally expanded microcapsules. Examples of the heat-sealed product include a bowl-shaped product obtained by heat-sealing a relatively small amount of already-expanded microcapsules, and an uneven planar product obtained by heat-sealing a relatively large amount of already-expanded microcapsules. included. The heat-fused product may contain a small amount of a thermally expandable microcapsule alone or an already thermally expanded microcapsule as long as the effects of the present invention are not impaired.

  The anti-slip layer may contain the heat-sealed product over the entire surface or may include a part thereof, but it is preferable that the anti-slip layer includes over the entire surface. The laminated region of the anti-slip layer is not particularly limited as long as the desired anti-slip property and wear resistance can be obtained, and may be the entire surface of the base paper or a part thereof. Moreover, when laminating | stacking one part, the planar shape is a dot shape, a line shape, a grid | lattice shape etc., for example, and it can provide with coating or a printing means.

  The thermally expandable microcapsule is a thermally expandable microsphere in which a material (core) that is vaporized by heating to generate a gas (core) is encapsulated in a substantially mononuclear form in a thermoplastic polymer (outer shell). By heating and expanding the particles at a temperature equal to or higher than the expansion start temperature, a gas derived from the above material is generated, and a relatively small amount of the pre-expanded microcapsules are heat-sealed to form a bowl-like heat. A fused material can be obtained. Further, when these are further heated, the concavo-convex planar heat-sealed product can be obtained by heat-sealing the cocoon-shaped heat-fused materials while shrinking the already thermally expanded microcapsules.

  The material is not particularly limited. For example, normal carbonization such as normal octane, isooctane, normal heptane, isoheptane, normal hexane, isohexane, normal pentane, isopentane, normal butane, isobutane, petroleum ether, etc. Examples thereof include halons such as hydrogen, methyl chloride, methylene chloride, dichloroethylene, trichloroethane, and trichloroethylene. These may be used singly or in a mixture, and may be linear or branched.

  The thermoplastic polymer is not particularly limited, and examples thereof include (meth) acrylonitrile polymers containing about 20% by mass or more of (meth) acrylonitrile monomers as monomer components. Other monomer components contained in the (meth) acrylonitrile-based polymer are not particularly limited, and are vinyl halide, vinylidene halide, styrene-based monomer, (meth) acrylate-based monomer, vinyl acetate, vinyl pyridine, ( (Meth) acrylic acid etc. are mentioned, A vinylidene halide, a (meth) acrylate type monomer, and (meth) acrylic acid are preferable, and a (meth) acrylate type monomer is more preferable.

  Other monomer components include divinylbenzene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate and trimethylolpropane tri (meth) acrylate, polyfunctional monomers such as butadiene and chloroprene. The body (crosslinking agent) may be included. (Meth) acrylate refers to acrylate or methacrylate, and the same applies to expressions containing other (meth).

  The above monomers may be used alone or a plurality of monomers may be used as a mixture as long as desired physical properties can be obtained. Similarly, the copolymer may be block-shaped or random.

  The volume average particle size of the thermally expandable microcapsules is not particularly limited, but is usually 10 μm or more and 40 μm or less, preferably 10 μm or more and 20 μm or less, as the volume average particle size of the thermally expandable microcapsules that obtains favorable slip resistance without impairing the appearance. is there. When the volume average particle size is within the above range, there is a tendency to have sufficient heat expandability in heating. The particle diameter of the thermally expandable microcapsule can be selected and used according to the desired anti-slip property.

  Thermally expandable microcapsules can be produced according to known methods, but are also commercially available. For example, the product name “Matsumoto Microsphere F-30” or “Matsumoto Microsphere F-36” from Matsumoto Yushi Seiyaku Co., Ltd. 031DU "or the like. Moreover, it can also be obtained as a compound containing a thermally expandable microcapsule, a resin binder, etc., and it can also be obtained as a hydrous cake of a thermally expandable microcapsule or an already thermally expanded microcapsule. More preferably, it is preferable to use a low-temperature expansion type in which the maximum expansion temperature of the heat-expandable microcapsule is about 70 ° C. or more and 150 ° C. or less. And the outer shell is preferable in terms of easy thermal fusion.

  The pre-expanded microcapsules can be obtained by thermally foaming the thermally expandable microcapsules at the above-described temperature. Although the pre-expanded microcapsules are heat-sealed by further heating after heat-foaming, the remaining pre-expanded microcapsules that are not shrunk and do not reach thermal fusion can be allowed to remain, and the remaining pre-heat-expanded microcapsules and heat-bonded materials remain. The volume average particle diameter of the preheated microcapsules contained therein is not particularly limited, and is usually 20 μm or more and 100 μm or less, preferably 25 μm or more and 50 μm or less in terms of the volume average particle diameter at the time of maximum expansion. When the upper limit of the volume average particle size at the time of maximum expansion is larger than 100 μm, the wear resistance of the antiskid layer may be reduced due to further heating shrinkage and thermal fusion of the outer shell thinned to about 1 μm or less. If the lower limit of the volume average particle diameter at the time of maximum expansion is less than 20 μm, the material that generates gas by heating from the outer shell of the thermally expanded microcapsule becomes insufficiently diffused, and the outer shell is thick and heated. Adhesion may be insufficient and the anti-slip property of the anti-slip layer may be reduced.

  The anti-slip layer includes a heat-sealed product of already thermally expanded microcapsules. By heat-sealing the pre-expanded microcapsules, it is possible to form convex portions on the surface of the anti-slip layer that exhibit even stronger anti-slip properties than the pre-expanded microcapsules alone, resulting in higher anti-slip and anti-resistance properties. Abrasion can be achieved. Moreover, since the heat-sealed material is strongly heat-sealed, the heat resistance is also good. Specifically, since the anti-slip layer containing the pre-expanded microcapsules and the binder contains a lot of resin components, when exposed to a heat history such as a corrugator, the state of unevenness may change due to insufficient heat resistance. However, according to the present invention, such inconvenience can be reduced. Preferably, by performing thermal foaming and thermal fusion of the expanded microcapsules in a heating process such as a corrugator and the like, without impairing workability such as a printing process before the corrugator processing and a functional drug coating process such as a freshness-preserving agent. Anti-slip property can be expressed.

  According to the inventor's knowledge, the arithmetic average roughness (Ra) of the anti-slip layer containing the heat-sealed product is 1.0 μm or more and 6.0 μm or less, preferably 2.0 μm or more and 5.5 μm or less, more preferably 2. 5 μm or more and 5.0 μm or less. When the arithmetic average roughness (Ra) is in the above range, the anti-slip layer has sufficient anti-slip properties and wear resistance.

  The volume average particle diameter and the foamed portion of the already thermally expanded microcapsule greatly depend on the foaming conditions and the type of the thermally expandable microcapsule, and greatly affect the slip resistance and wear resistance of the slip resistant layer. Specifically, a large convex portion may exist only in a part of the anti-slip layer because a part of the thermally expandable microcapsule is greatly foamed. In addition, the thermally expandable microcapsule does not sufficiently foam, and there are cases where the number of convex portions is relatively small or many small convex portions are included. In these cases, the paperboard as a whole may not have excellent slip resistance and wear resistance. In view of such a situation, an anti-slip layer is provided even if the irregularity situation is slightly changed by providing a heat-sealed product of pre-expanded microcapsules and setting the arithmetic average of the surface roughness within a desired range. Has been found to exhibit suitable slip resistance and wear resistance.

  More specifically, if the upper limit of the arithmetic average roughness (Ra) is larger than 6.0 μm, the contact point between the heat-fused product and the laminated object becomes a pinpoint, and the wear resistance is lowered. Further, when the arithmetic average roughness (Ra) increases, blocking between the anti-slip layers and contamination with dust or the like may become a problem. However, when the upper limit is within the above range, the anti-slip layer has appropriate anti-slip properties and wear resistance, and thus such a problem tends to hardly occur. In addition, workability problems during cardboard box production hardly occur. When the lower limit of the arithmetic average roughness (Ra) is smaller than 1.0 μm, the unevenness due to the heat-sealed product of the already thermally expanded microcapsules becomes insufficient, and the slip resistance is lowered.

  The ten-point average roughness (Rz) of the anti-slip layer is not particularly limited, and is usually 5 μm or more and 40 μm or less, preferably 20 μm or more and 40 μm or less. When the upper limit of the ten-point average roughness (Rz) is larger than 40 μm, the smoothness may be lowered. If the lower limit of the ten-point average roughness (Rz) is smaller than 5 μm, the slip resistance may be lowered.

  Since the anti-slip layer according to the present invention exhibits excellent anti-slip properties and wear resistance, the slip angle of the anti-slip layer is preferably 30 ° to 60 °, more preferably 45 ° to 50 °. If the upper limit of the sliding angle is larger than 60 °, the paperboards may block each other. If the lower limit of the slip angle is less than 30 °, a sufficient anti-slip function may not be exhibited.

  According to the present invention, it is possible to reduce the deterioration of slip resistance and wear resistance over time. Since the preheated microcapsules are independent microspheres, if the paperboard is scratched or rubbed, the preheated microcapsules are separated from the paperboard and fall off, and the slip resistance and abrasion resistance of the paperboard are likely to be lowered. However, since the anti-slip layer of the paperboard according to the present invention includes a heat-sealed product of already thermally expanded microcapsules that are firmly fused, the anti-slip layer is excellent in wear resistance and can suppress a decrease in anti-slip property. Specifically, even when the anti-slip layer is repeatedly used for a long time in transshipment work or the like, and the anti-slip surface is rubbed, the anti-slip property is hardly lowered.

  The anti-slip layer can contain a resin binder as a component other than the thermally expandable microcapsules. In this case, a material such as a heat-expandable microcapsule can be uniformly dispersed in the anti-slip layer. Further, when the anti-slip layer includes a heat-sealed product of the already thermally expanded microcapsules and the resin binder, the anti-slip property and the wear resistance of the anti-slip layer may be further improved. The resin binder is not particularly limited. For example, styrene-butadiene latex, acrylic emulsion, acrylic-styrene emulsion, vinyl acetate emulsion, ethylene-vinyl acetate emulsion, urethane emulsion, starch, modified starch, polyvinyl alcohol ( PVA) and other latexes, emulsions, water-soluble binders, and the like.

  In addition, the anti-slip layer may contain a colorant such as a pigment or a dye. In this case, the presence of the anti-slip layer can be easily recognized and the workability can be improved, and the surface can be made beautiful by providing, for example, a designed anti-slip layer. The colorant is not particularly limited, and examples thereof include an anionic direct dye, a cationic direct dye, and a basic dye. When the anti-slip layer contains inorganic fine particles such as a pigment as a colorant, the anti-slip property may be further improved.

  Ingredients other than those in the coating liquid are not particularly limited. For example, surfactants, waxes, sizing agents, fillers, rust inhibitors, conductive agents, antifoaming agents, dispersants, viscosity modifiers, flocculants, and coagulants. Agents, paper strength enhancers, yield improvers, paper powder fall-off preventing agents, bulking agents and the like.

<Manufacturing method of paperboard>
The method for producing paperboard is also not particularly limited, and can be performed according to a known method. As an example, paperboard can be manufactured according to the following method.

((1) Preparation of surface layer raw material slurry)
After blending 70% by weight of hardwood bleached kraft pulp (LBKP) and 30% by weight of Kamikoshi old paper pulp, 0.5% by weight of sulfuric acid band, Product name: R-22, manufactured by Modern Chemical Co., Ltd.) 0.5 mass% in terms of solid content, and dry paper strength enhancer (product name: Hermide RB-32, manufactured by Harima Kasei Co., Ltd.) 0 in terms of solid content .3 mass%, wet paper strength enhancer (manufactured by Seiko PMC, epichlorohydrin) is added in an amount of 0.18 mass% in terms of solid content to prepare a raw material slurry for the surface layer.

((2) Preparation of raw material slurry for intermediate layer)
Raw material pulp for an intermediate layer in which 30% by mass of softwood bleached kraft pulp (NBKP), 10% by mass of hardwood bleached kraft pulp (LBKP) and 60% by weight of upper white waste paper pulp are mixed, and the disaggregation freeness is adjusted to 400cc. In addition, 0.7% by mass of a sulfuric acid band, 0.5% by mass of a sizing agent (product name: R-22, manufactured by Modern Chemical Co., Ltd.) in terms of solid content, and a dry paper strength enhancer (product name: Hermide RB-) 32, manufactured by Harima Chemicals Co., Ltd.) in terms of solid content and 0.7% by mass, and a wet paper strength enhancer (manufactured by Seiko PMC Co., Ltd., epichlorohydrin) is added in an amount of 0.3% by mass in terms of solid content. Moreover, 5 mass% of heat-heat fusible fibers (product name: Sophit N720, manufactured by Kuraray Co., Ltd.) are added. Thereafter, the pH of the intermediate layer raw material pulp is adjusted to 6.8, and the intermediate layer raw material slurry is adjusted.

((3) Preparation of raw material slurry for back layer)
After blending 70% by weight of cardboard waste paper pulp and 30% by weight of old paper waste paper pulp, 0.5% by weight of sulfuric acid band, sizing agent (product name: R-22, manufactured by Modern Chemical Co., Ltd.) in terms of solids content of 0.5% by mass, and a dry paper strength enhancer (product name: Hermide RB-32, manufactured by Harima Kasei Co., Ltd.) in terms of solids content of 0.4% by mass % To adjust the raw material slurry for the back layer.

((4) Papermaking)
Using these raw material slurries, a surface layer, an intermediate layer, and a back layer paper layer are made together by a circular three-layer paper machine, and the basis weight of the surface layer is 30 g / m ² , and the basis weight of the intermediate layer is 60 g / m ² . A multilayer paperboard having a three-layer structure is obtained in which m ² , the basis weight of the back layer is 130 g / m ² , and the basis weight of the entire multilayer paperboard is 220 g / m ² .

((5) Formation of anti-slip layer)
The anti-slip layer in the present invention is provided in a printing machine when printing on a paperboard after papermaking, or provided in a coating process in which a coating liquid containing a thermally expandable microcapsule and a resin binder is applied to the surface of the base paper. Thus, the anti-slip layer can be formed by printing on the necessary portions. Subsequently, the anti-slip layer having irregularities can be formed in a heating step of heating the anti-slip layer formed on the surface of the base paper.

  The method for forming the anti-slip layer is not particularly limited, and examples thereof include a coating method such as calendar coating, bar coater, rod coater, air knife, gate roll coater, and 2 roll size press, and a printing method such as gravure printing and flexographic printing. Can be mentioned. In particular, the means for providing the anti-slip layer by the printing method can be selectively provided only on the back side of the box in the box making or the place where the anti-slip property is desired, which is advantageous in terms of workability and cost. Further, printing and coating may be performed once or a plurality of times. An anti-slip layer may be laminated on the base paper manufactured through the above-described steps, or an anti-slip layer may be laminated on a commercially available base paper. Examples of commercially available base paper include Daio Paper Co., Ltd. liner JEK (product name).

  The solvent in the coating liquid for forming the anti-slip layer is not particularly limited, and may be an organic solvent or an aqueous solvent, but an aqueous solvent is preferable. In this case, a small amount of a water-soluble organic solvent such as alcohol may be contained.

The coating amount of the coating liquid is appropriately determined by a coating method such as calendar coating, bar coater, rod coater, air knife, gate roll coater, and 2 roll size press, and a printing method such as gravure printing and flexographic printing. However, in order to effectively exhibit anti-slip properties, the solid content ratio is usually 3.0 g / m ² or more and 10.0 g / m ² or less, preferably 5.0 g / m ² or more and 10.0 g / m. ² or less. If the upper limit of the coating amount is greater than 10.0 g / m ² , the production cost may increase. If the lower limit of the coating amount is less than 3.0 g / m ² , sufficient anti-slip properties may not be exhibited.

  The compounding quantity with respect to the coating liquid of a thermally expansible microcapsule is not specifically limited, It is 5 to 30 mass% normally in conversion of solid content, Preferably it is 10 to 20 mass%. When the blending amount is within the above range, the heat-expandable microcapsule tends to be applied substantially uniformly.

  The compounding quantity with respect to the coating liquid of a resin binder is not specifically limited, It is 70 to 95 mass% normally in conversion of solid content, Preferably it is 80 to 90 mass%. When the blending amount is within the above range, the resin binder tends to be applied substantially uniformly. Since the anti-slip layer contains at least the heat-fused product of the already thermally expanded microcapsules, the blending amount of the resin binder may be reduced.

  The average thickness of the anti-slip layer is preferably 10 μm to 35 μm, more preferably 15 μm to 30 μm. If the upper limit of the average thickness is larger than 35 μm, the manufacturing cost may increase. When the lower limit of the average thickness is less than 10 μm, the slip resistance may be lowered. Further, although the anti-slip layer is considerably thin relative to the base paper, it can exhibit excellent anti-slip properties and wear resistance.

  When forming a cardboard box from the paperboard, it is preferable to provide a relatively thick anti-slip layer when the contents are heavy, and provide a relatively thin anti-slip layer when the contents are light. The thickness of the anti-slip layer is appropriately adjusted according to the contents, and it is preferable from the viewpoint of recycling and resource saving without fear of falling into workability and excessive quality.

  The heat drying method is not particularly limited. For example, hot air may be blown onto the paperboard using a dryer, the paperboard may be left in the dryer, the paperboard may pass through the dryer, or corrugator processing. You may heat with the hotplate at the time of bonding the core of time and paperboard. Furthermore, the anti-slip layer can also be formed by thermally fusing the already-expanded microcapsules with a household appliance such as a hair dryer at the time of use after final production.

  As described above, in the heat drying step, it is preferable that the thermally expandable microcapsules are heated and foamed simultaneously with drying, and then the obtained already thermally expanded microcapsules are thermally fused. In this case, the manufacturing process can be simplified. By intentionally applying excessive heat to the pre-expanded microcapsules to form a heat-bonded product, a large number of strong protrusions derived from the heat-bonded product of the pre-expanded microcapsules are provided on the surface of the anti-slip layer. These can be formed relatively uniformly and firmly by heat fusion of the surface of the anti-slip layer with an appropriate heat.

  Although depending on the foaming start temperature and the maximum foaming temperature of the thermally expandable microcapsule, the temperature in the heat drying step is usually 70 ° C. or higher and 200 ° C. or lower, preferably 130 ° C. or higher and 180 ° C. or lower. Similarly, the time for the hot drying step is usually 1 second to 20 seconds, preferably 2 seconds to 10 seconds. By setting the temperature and time within the above ranges, a desired heat-sealed product can be easily obtained without deteriorating workability.

  Preferably, a drying process is performed at a low temperature during the drying process at the time of paperboard making, and the product is manufactured without heat expansion of the heat-expandable microcapsules or heat fusion of the existing heat-expandable microcapsules, and a slip-proof layer needs to be formed. In some cases, a heating step for obtaining a heat-sealed product that forms irregularities on the anti-slip layer may be provided.

  In the coating process, instead of the thermally expandable microcapsule, the thermally expandable microcapsule is separately heated and expanded, and in that case, an inorganic substance such as calcium carbonate or titanium oxide is attached to the surface, or A heat-sealed product obtained by further heat-sealing them can be mixed with the coating liquid. In these cases, the drying process can be simplified.

  A printed layer may be formed on the paperboard. For example, a method of forming a pattern or letters for a box on the surface of the base paper, and then forming an anti-slip layer by coating (printing), or conversely, forming an anti-slip layer on the surface of the base paper, and then the anti-slip layer And a method of performing printing on the surface of the base paper including at least a part of the surface. The printing method used in printing is not particularly limited, and examples thereof include gravure printing and flexographic printing.

  Other process conditions such as temperature, pressure, time and equipment in each process are not particularly limited, and are appropriately set according to the raw materials used. The number of steps in each step is not particularly limited, and may be performed in one step or in multiple steps. The quantification and qualification of raw materials and products can be performed according to known methods such as NMR, IR, elemental analysis, and mass spectrum. Moreover, the raw material to be used may be used independently and may be used combining multiple types of raw material.

<Cardboard sheet>
Since the paperboard according to the present invention is excellent in slip resistance and abrasion resistance, the paperboard can be suitably used as a paperboard for cardboard sheets. Corrugated cardboard sheets having the above paperboard as a front liner are also excellent in slip resistance and wear resistance. The anti-slip layer of the paperboard is disposed on the surface side of the cardboard sheet.

  The corrugated cardboard sheet is a plate-like sheet in which a corrugated core is attached to the back surface of a paperboard on which an anti-slip layer is formed. In the corrugated cardboard sheet, a back liner is usually pasted on the opposite side of the core front liner, and the back liner can be pasted arbitrarily.

  The manufacturing method of a corrugated cardboard sheet is not particularly limited, and examples thereof include a method of bonding a core and a liner using a corrugator. Also, in the pre-process of bonding the core and liner using a corrugator, an anti-slip layer is provided by a means such as printing or stamping at the required location, and the heat-expandable microcapsule is foamed in the heating process at the time of bonding. It is also possible to form a heat fusion product.

<Box>
Since the paperboard according to the present invention is excellent in slip resistance and wear resistance, a box formed from the paperboard or the corrugated cardboard sheet and provided with the slipproof layer on the surface side is also excellent in slip resistance and wear resistance. Specifically, the box or cardboard obtained from the paperboard is not easily slipped due to shaking or vibration during transportation, and as a result, damage to the product or product can be reduced. For this reason, a paperboard can be used conveniently as a paperboard for boxes, and a corrugated cardboard sheet can also be used conveniently as a cardboard sheet for boxes. Therefore, the box according to the present invention can be suitably used as a packaging container, a storage container, a transport container, a package, a packaging material, and the like.

  The paperboard according to the present invention is excellent in slip resistance and wear resistance. For this reason, the said paperboard can be used conveniently as a material of a corrugated cardboard sheet or a box.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited by these.

(Presence / absence of heat-sealed material)
The presence or absence of the heat-sealed product was confirmed using a real surface view microscope (manufactured by Keyence Corporation, product name VE-7800).

(Arithmetic average roughness (Ra) and ten-point average roughness (Rz))
Arithmetic average roughness (Ra) and ten-point average roughness (Rz) are in accordance with JIS B 0601: 1994 “Product geometric property specification (GPS)-Surface property: Contour curve method-Terminology, definition and surface property parameter” Then, ten samples were measured using a surface roughness measuring instrument (product name SJ-201P, manufactured by Mitutoyo Corporation), and the average value thereof was taken as the value.

(Average thickness)
For the average thickness, 10 samples were measured using a real surface view microscope (manufactured by Keyence Corporation, product name VE-7800), and the average value thereof was taken as the value.

(Slip angle)
The sliding angle was measured according to JIS P 8147: 1994 “Friction coefficient test method for paper and paperboard” using a sliding angle measuring device (manufactured by Toyo Seiki Co., Ltd.), and the average value of them was measured. It was.

(Abrasion resistance)
Abrasion resistance is determined according to JIS P 8136: 1994 “Abrasion resistance test method for paperboard” using 10 pieces of Gakken type friction fastness tester (manufactured by Japan TMC Co.). Measured, and the average value thereof was taken as the value. Specifically, a base paper was attached to a friction part with a load of 500 g, and a sample was attached to the base part, and the coated surface and the surface of the base paper were brought into contact with a load of 500 g, and a wear test was performed 500 times.

The state of the coated surface and the base paper surface after 500 round-trip wears was evaluated according to the following evaluation criteria.
◎: No change on the coated surface and the base paper surface ○: Slight scratches are observed on the coated surface, but there is no problem △: There are scratches on the coated surface ×: There are scratches on the coated surface, and the coated surface on the base paper surface Color stick

Example 1
The used base paper, coating liquid, and printing machine are as follows.
Base paper: Liner JEK (210 g / m ² ) manufactured by Daio Paper
Coating liquid: Matsumoto Yushi Seiyaku Co., Ltd. thermal expansion microcapsule (product name Matsumoto Microsphere F-36) and Dow Chemical Co., Ltd. styrene-butadiene latex (product name XQ-83302)
Printing machine: Flexo rotary printing machine (product name: DF93) manufactured by F & K

Using the printing machine, an anti-slip layer was formed on the base paper by printing using a coating liquid, and the paper of Example 1 was obtained. The coating liquid was applied (printed) on the entire upper surface. The coating solution was adjusted to 8 g / m ² (in terms of solid content). Next, in a drier, hot air of 150 ° C. is blown for 8.0 seconds to dry the paper, and an anti-slip layer having unevenness derived from the heat-sealed microcapsule is formed on the surface of the surface of the base paper. A paperboard was prepared.

Example 2 to Example 20 and Comparative Example 1 to Comparative Example 6
Example 2 to Example 20 and Comparative Example 1 to Comparative Example 6 were performed in the same manner as Example 1 except that the raw materials and the like of Example 1 were as shown in Table 1.

  Table 1 shows the raw materials and coating conditions of the examples and comparative examples.

  It can be seen from Table 1 that the paper obtained in the examples is superior in slip resistance and abrasion resistance as compared with the comparative example.

  The paper according to the present invention is excellent in slip resistance and abrasion resistance. For this reason, the paper can be suitably used as a material for corrugated cardboard sheets and boxes.

Claims (6)

A paperboard comprising a base paper and an anti-slip layer laminated on the surface of the base paper,
The anti-slip layer includes a heat-softening adhesive formed by thermally bonding thermoplastic polymers constituting the outer shell of a thermally expanded microcapsule having a maximum expansion temperature of 70 ° C. or higher and 150 ° C. or lower, and a resin binder,
The coating amount of the anti- slip layer is 5.0 g / m ² or more and 10.0 g / m ² or less, and the blending amount of the thermal expansion microcapsule with respect to this coating solution is 5% by mass or more and 30% by mass or less in terms of solid content. And
An arithmetic average roughness (Ra) of the surface of the anti-slip layer is 1.0 μm or more and 6.0 μm or less.   The paperboard according to claim 1, wherein an average thickness of the anti-slip layer is 10 µm or more and 35 µm or less.   The paperboard according to claim 1 or 2, wherein the slip angle of the anti-slip layer is 30 ° or more and 60 ° or less. The paperboard of claim 1, claim 2 or claim 3 amount for the coating liquid of the above resins binder is not more than 95 mass% 70 mass% or more in terms of solid content.   A cardboard sheet comprising the paperboard according to any one of claims 1 to 4 as a front liner.   A box formed from the paperboard according to any one of claims 1 to 4 or the corrugated cardboard sheet according to claim 5.