JP6259298B2 - Corrugated base paper for corrugated sheet on one side - Google Patents

Description

  The present invention relates to a corrugated base paper for a single-sided corrugated cardboard sheet.

  In recent years, at the processing stage of a corrugated cardboard sheet consisting of a core provided between the surface liner, the back liner, and the surface liner and the back liner, the core is applied to only one of the surface or back liner using a corrugated roll. A single-sided cardboard sheet bonded in a corrugated shape is used as a cushioning material, a cushioning material, or the like of an object to be packaged by bringing a flexible corrugated sheet side into contact with the object to be packaged. Moreover, in order to enhance the cushioning effect and the cushioning effect, a technique using an expansion / contraction sheet (see JP 2009-102031 A) and a technique for adjusting the number of steps (see JP 2002-68164 A) have been developed. . On the other hand, single-sided corrugated cardboard sheets are used as cushioning materials, cushioning materials, etc., and the stepped parts of single-sided corrugated cardboard sheets are exposed to create design, so that packaging materials for packaging of confectionery, food, electrical appliances, etc., so-called corrugated cardboard It is also used as a case.

  Originally, the core for double-sided corrugated cardboard is sandwiched between the surface liner and the back layer liner, so the core (corrugated sheet) is not visible from the outside, and strength, beauty due to deformation, breakage, peeling of the corrugated sheet, etc. Sexual decline is not often a problem. On the other hand, corrugated paper used for a single-sided corrugated cardboard sheet has a disadvantage that it is easily deformed and damaged because a so-called double-sided corrugated core paper is used as it is. Further, when the above-mentioned core base paper for double-sided cardboard is used as single-sided cardboard, for example, when it is used as a packaging exterior material, there is a disadvantage that a decrease in strength, beauty, and printability tends to be a big problem. Specifically, single-sided corrugated cardboard with deformed or damaged paperboard or single-sided corrugated cardboard with corrugated sheets peeled off is not beautiful and has a reduced cushioning property. As a result, the commercial value of single-sided cardboard is greatly reduced. Further, the smoothness of the surface is lost, and as a result, the printability is lowered. In addition, corrugated paper that is easily deformed and damaged is subjected to strong forces such as pulling, bending, and shearing from a pair of corrugated rolls during corrugation, so that the corrugated paper can be broken (corrugated) or the top of the corrugated sheet can be cut ( In an extreme case, there is a disadvantage that breakage or the like easily occurs over the entire width of the corrugated paper.

JP 2009-102031 A JP 2002-68164 A

  The present invention has been made in view of the above inconveniences, and is excellent in strength and laminating properties, cosmetic properties and printability when it is made into a single-sided corrugated cardboard sheet. An object of the present invention is to provide a corrugated base paper for a single-sided corrugated cardboard sheet that is not easily generated.

  As a result of intensive studies to solve the above problems, the present inventor has found that the corrugated paper for single-sided corrugated cardboard sheets having a specific range of surface ash content, density, and water absorption at a contact time of 120 seconds on the front and back surfaces, The present invention has been found to be a corrugated sheet for single-sided corrugated cardboard sheets that is excellent in laminating properties, cosmetics, and printability when used as a single-sided corrugated cardboard sheet, and hardly undergoes step cracking, breakage, breakage, etc. It came to complete.

The invention made to solve the above problems is a single-sided corrugated cardboard sheet for corrugated sheet having a multilayer structure of three or more layers, which is processed into a corrugated sheet and bonded to the liner on the back surface, and has a density of 0.80 g. / Cm ³ or more and 0.90 g / cm ³ or less, the ash content of the surface layer is 15% by mass or less, and the water absorption at the contact time of the surface of 120 seconds is 20 g / m ² or more and 40 g / m ² or less. The corrugated sheet base paper for a single-sided corrugated cardboard sheet has a water absorption of 175 g / m ² or more and 190 g / m ² or less at a contact time of 120 seconds.

  The corrugated base paper has a multilayer structure of three or more layers, and the strength of the corrugated base paper is balanced while maintaining the balance between the ash content of the surface layer and the density of the corrugated base paper within the above range. In addition, it is possible to improve the cosmetics and printability when a single-sided cardboard sheet is used. Further, the water absorption of the contact time of the front surface of 120 seconds is in the above range, and the water absorption of the contact time of the back surface of 120 seconds is in the above range, thereby improving the bonding property between the back surface and the liner, As a result, it is possible to further enhance the cosmetics when a single-sided cardboard sheet is used. Furthermore, by improving the strength of the corrugated paper, step breakage, step breakage, breakage, and the like are less likely to occur during setting.

  The sliding angle of the front surface is preferably smaller than the sliding angle of the back surface. Moreover, it is preferable that the Beck smoothness (A) of the said surface is 20 to 40 seconds, and the Beck smoothness (B) of the said back surface is 5 to 15 seconds. In these cases, the surface becomes more flexible than the back surface of the corrugated base paper, and step breakage, step breakage, breakage, and the like are less likely to occur during setting.

  It is preferable that the corrugated base paper satisfies the LC class or higher specified in JIS-P-3902: 2011. Thus, by making the corrugated sheet paper LC grade or higher, the corrugated sheet paper exhibits a suitable range of basis weight, compressive strength, burst strength, and moisture, and can be widely used in various applications.

  Here, “the surface of the corrugated paper for a single-sided corrugated cardboard sheet” refers to a surface on which the corrugated paper sheet is exposed when producing a single-sided corrugated cardboard sheet. “The reverse side of the corrugated paper for a single-sided corrugated cardboard sheet” refers to the surface on which the corrugated paper sheet and the liner are bonded together when the single-sided corrugated sheet is produced.

  “Density” refers to a value measured according to JIS-P-8118: 1998 “Paper and paperboard—Test method for thickness and density”. “Water absorption” refers to a value measured according to JIS-P-8140: 1998 “Paper and paperboard—Water absorption test method—Cobb method”. “Ash content” refers to a value measured in accordance with JIS-P-8251: 2003 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”. “Beck smoothness” refers to a value measured in accordance with JIS-P-8119: 1998 “Paper and paperboard—Smoothness test method using Beck smoothness tester”. The “compressive strength” refers to a value measured according to JIS-P-8126: 2005 “paper and paperboard—compressive strength test method—ring crush method”.

  As described above, the corrugated paper for a single-sided corrugated cardboard sheet is excellent in strength and bonding properties when used as a single-faced corrugated cardboard sheet, cosmetics, and printability. Not likely to occur. Therefore, the single-sided cardboard sheet using the corrugated paper for single-sided cardboard sheets can be suitably used as a packaging exterior material for confectionery, food, electrical appliances and the like.

  Hereinafter, an embodiment of the corrugated paper for a single-sided corrugated board sheet of the present invention will be described.

The corrugated paper for a single-sided corrugated sheet is a corrugated sheet for single-sided corrugated sheet that has a multilayer structure of three or more layers, and is processed into a corrugated sheet and bonded to a liner on the back surface. The corrugated paper for single-sided corrugated cardboard sheet has a density of 0.80 g / cm ³ or more and 0.90 g / cm ³ or less, an ash content of the surface layer of 15% by mass or less, and a water absorption of 120 seconds on the surface contact time. 20 g / m ² or more and 40 g / m ² or less, and the water absorption at the contact time of 120 seconds on the back surface is 175 g / m ² or more and 190 g / m ² or less. Hereinafter, the corrugated paper for single-sided cardboard sheets will be described in detail.

<Corrugated paper for single-sided cardboard sheets>
The corrugated base paper contains raw fiber. Examples of the raw fiber include pulp fiber and chemical fiber. The corrugated base paper may contain other papermaking chemicals as long as the effects of the present invention are not impaired, and may be coated with a coating solution on the surface thereof.

  The corrugated paper has a multilayer structure of three or more layers. The multi-layer structure of the corrugated base paper has three or more layers of a surface layer, at least one middle layer and a back layer. The upper limit of the number of layers is preferably 5 layers. When the number of layers is less than three, the corrugated sheet paper is stepped, stepped, broken or the like when stepped. If the multilayer structure exceeds 5 layers, the production process may be complicated. When the middle layer has a plurality of paper layers, they may be the same or different.

(Raw fiber)
As pulp fiber, for example,
Chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP),
Stone Grand Pulp (SGP), Pressurized Stone Grand Pulp (PGW), Refiner Grand Pulp (RGP), Chemi Grand Pulp (CGP), Thermo Grand Pulp (TGP), Grand Pulp (GP), Thermo Mechanical Pulp (TMP), Mechanical pulp such as Chemi thermomechanical pulp (CTMP), refiner mechanical pulp (RMP),
Waste paper pulp made from waste tea paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated waste paper, upper white waste paper, medium white waste paper, Kent waste paper, imitation waste paper, local paper waste paper, recycle paper waste paper, etc. ,
Examples include deinked pulp (DIP) obtained by deinking waste paper pulp.

As chemical fiber, for example,
Polyester fibers such as polyethylene terephthalate,
Polyamide fibers such as nylon,
Cellulosic fibers such as acetate,
Protein fiber such as promix,
Cellulosic regenerated fibers such as rayon, cupra, polynosic,
Examples include acrylonitrile fiber, carbon fiber, polyolefin fiber, and vinylon fiber. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  Among these, pulp fibers are preferable as raw material fibers, chemical pulp and waste paper pulp are more preferable, and softwood bleached kraft pulp (NBKP), upper white waste paper pulp, local paper waste paper pulp, and corrugated waste paper pulp are more preferable. Waste paper pulp has a tendency to make the pulp fibers flat in the recycling process, softening the paper layer and making the paper layer dense, and improving the hydrophilicity through the recycling process. In addition, it is preferable from the viewpoint of improving the absorption of the adhesive by capillary action. On the other hand, chemical pulp is preferable from the viewpoint of increasing strength.

  As content with respect to the raw material fiber of a pulp fiber, 50 mass% or more is preferable, 70 mass% or more is more preferable, and 100 mass% is further more preferable. If the content is less than the lower limit, it becomes difficult to recycle, and it may be necessary to produce the paper with a dedicated paper machine.

(Paper making chemicals)
Examples of papermaking agents include pigments, dyes, fillers, internal sizing agents, internal paper strength improvers, yield improvers (coagulants, flocculants), internal sizing agents, and internal paper strength improvers. It is done. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

(Coating fluid)
On the surface of the corrugated paper, a paperboard conforming to the LC class suitably used in the present invention is used, and a coating liquid may be optionally applied mainly for the purpose of ensuring corrugated workability. . The coating liquid may be applied to the back surface of the corrugated sheet base paper and the liner as long as it does not hinder the bonding with the liner, or may be applied to any one of them. The coating solution may be in the form of a solution or an emulsion.

  As the coating agent contained in the coating liquid, a lubricant is preferably used, but other examples include pigments, dyes, lubricants, binders, surface sizing agents, external paper strength improvers, and fluorescent brighteners. , Antifoaming agents, colorants, water retention agents, surfactants and the like. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  The coating liquid preferably contains a lubricant as a coating agent. By improving the resistance to deformation and breakage of the corrugated base paper, step breakage, step breakage, breakage, and the like can be reduced during setting.

  Examples of lubricants include petroleum waxes such as paraffin wax and microcrystalline wax, higher fatty acid metal salts such as calcium stearate, alkyl ketene dimers such as cationic alkyl ketene dimers, polyvinyl alcohol (PVA), low molecular weight polyethylene, and liquid hydrocarbon oils. Higher fatty acids, higher alcohols, higher fatty acid sulfated oils, aliphatic phosphate esters, polyalkylene glycols or derivatives thereof.

  Of these, alkyl ketene dimer and polyvinyl alcohol (PVA) are preferable, and cationic alkyl ketene dimer is more preferable, from the viewpoint that high slipperiness can be imparted to the corrugated base paper. In particular, by applying a coating solution containing a cationic alkyl ketene dimer on the surface layer of the corrugated base paper having a multilayer structure, the cationic alkyl ketene dimer is fixed in the surface layer rather than the middle layer of the corrugated base paper. It becomes easy to do. Therefore, by utilizing the hydrophobic interaction between the hydrocarbon groups in the cationic alkyl ketene dimer, it is possible to reduce the density of the surface layer of the base paper and improve the cushioning property.

  When a cationic alkyl ketene dimer is used as a lubricant, the freeness of the corrugated base paper surface is preferably 200 mL or more and 300 mL or less, more preferably 220 mL or more and 280 mL or less, and the freeness of the corrugated base paper middle layer is 300 mL or more and 400 mL or less are preferable, and 320 mL or more and 380 mL or less are more preferable. Thus, by setting the freeness of the surface layer alone and the freeness of the middle layer within the above range, the cationic alkyl ketene dimer tends to be more easily fixed in the surface layer alone.

  The alkyl ketene dimer may be produced according to a known method, or a commercially available product may be used. As a commercial item of the alkyl ketene dimer, for example, “Dimer S-20” from Daiwa Chemical Co., Ltd. and the like can be mentioned.

The coating amount of the lubricant is preferably 0.06 g / m ² or more and 0.54 g / m ² or less, more preferably 0.08 g / m ² or more and 0.52 g / m ² or less. There exists a tendency which can give still higher lubricity to the said corrugated sheet paper by making the coating of a lubricant into the said range.

(Surface)
The basis weight of the surface layer is preferably 15 g / m ² or more and 40 g / m ² or less, and more preferably 20 g / m ² or more and 35 g / m ² or less. Thus, there exists a tendency for the softness | flexibility of the said corrugated sheet paper to improve by making the basic weight of a surface layer into the said range. In addition, basic weight (g / m < ² >) is measured based on JIS-P-8124: 1998 "Measuring method of paper and paperboard-basic weight".

The density of the surface layer is preferably 0.65 g / cm ³ or more and 1.00 g / cm ³ or less, and more preferably 0.69 g / cm ³ or more and 0.89 g / cm ³ or less. Thus, there exists a tendency for the softness | flexibility of the said corrugated sheet paper to improve by making the density of a surface layer into the said range. In addition, a density (g / cm < ³ >) is measured based on JIS-P-8118: 1998 "Test method of paper and board-thickness and density".

  The freeness of the surface layer is preferably 200 mL or more and 300 mL or less, and more preferably 220 mL or more and 280 mL or less. There exists a tendency for the softness | flexibility of the said corrugated sheet paper to improve by making the freeness of the said surface layer into the said range. The freeness can be adjusted by, for example, selecting a used paper used as a raw material, or adjusting means such as a known beating process. The freeness was measured at 10 ° C. or higher and 40 ° C. or lower. The freeness (mL) of the paper layer was disaggregated according to JIS-P-8220: 1998 “pulp-disaggregation method”, and the obtained disaggregated pulp was JIS-P-8121: 1995 “pulp drainage. Measured in accordance with “degree test method”.

  The ash content of the surface layer of the corrugated paper is 15% by mass or less, and preferably 13% by mass or less. Further, the ash content of the surface layer of the corrugated paper is preferably 0.5% by mass or more, more preferably 4% by mass or more, and further preferably 8% by mass or more. In this way, by making the ash content in the above range, the ash content can inhibit the bond between the raw pulp fibers in the surface layer and soften the paper layer. Breakage and the like are less likely to occur. When the ash content exceeds the above upper limit, there is a problem that the paper quality ability of the surface layer is deteriorated, and there is a possibility that paper dust, wear, and surface strength are reduced. There exists a possibility that the effect of softening may become inadequate that the said ash content is less than a minimum. The ash content (mass%) is measured according to JIS-P-8251: 2003 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”.

  In order to ensure flexibility in corrugated sheet processing, the surface layer preferably contains a pigment. By including a pigment in the surface layer of the corrugated base paper, the cosmetic properties and printability of the corrugated base paper are improved.

As a pigment, for example,
Carbon black, calcium carbonate, clay, talc, kaolin, satin white, calcium sulfite, gypsum, barium sulfate, white carbon, calcined kaolin, structured kaolin, diatomaceous earth, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, silica Colored or white inorganic pigments such as magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bentonite and sericite;
Examples thereof include organic pigments such as polystyrene resin fine particles and urea formalin resin fine particles. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  Among these, inorganic pigments are preferable and carbon black and talc are more preferable from the viewpoint of further improving the cosmetic properties and printability of the corrugated base paper.

The amount of the pigment, 1 g / ^{m 2} or more 5 g / ^{m 2} or less are preferred in terms of ash content, more preferably 2 g / ^{m 2} or more 4g / ^{m 2} or less. By making the blending amount of the pigment within the above range, the cosmetic property and printability of the corrugated base paper tend to be further improved.

  When the surface layer contains a pigment and the ash content of the surface layer is 15% by mass or less, it is possible to obtain a corrugated paper for a single-sided corrugated cardboard sheet that is further excellent in cosmetics and printability while maintaining a balance with strength.

  It is possible to include a dye in the surface layer, but considering the exudation of the dye caused by rubbing or inadvertent water wetting, etc. to be packaged or transported in contact with the corrugated sheet, a pigment is used as a colorant. It is preferable to use it for obtaining corrugated paper for a single-sided corrugated cardboard sheet that is difficult to cause step breakage, step breakage, breakage, etc., when ensuring cosmetics and printability, which are the problems of the present invention, and setting.

(Middle layer)
The basis weight of the middle layer is preferably 20 g / m ² or more and 120 g / m ² or less, and more preferably 36 g / m ² or more and 120 g / m ² or less. Thus, there exists a tendency for the intensity | strength of the said corrugated sheet paper to improve by making the basic weight of a middle layer into the said range.

The density of the middle layer is preferably 0.80 g / cm ³ or more and 1.00 g / cm ³ or less, and more preferably 0.82 g / cm ³ or more and 0.90 g / cm ³ or less. Thus, there exists a tendency for the softness | flexibility of the said corrugated sheet paper to improve by making the density of a middle layer into the said range.

  The freeness of the middle layer is preferably from 300 mL to 400 mL, and more preferably from 320 mL to 380 mL. There exists a tendency for the intensity | strength of the said corrugated sheet paper to improve by making the freeness of the said middle layer into the said range.

(Back layer)
The basis weight of the back layer is preferably 25 g / m ² or more and 50 g / m ² or less, and more preferably 30 g / m ² or more and 40 g / m ² or less. Thus, there exists a tendency for the intensity | strength of the said corrugated sheet base paper to improve by making the basic weight of a surface layer into the said range.

The basis weight of the back layer is preferably larger than the basis weight of the surface layer. The difference between the basis weight of the surface layer and the basis weight of the back layer is preferably 5 g / m ² or more and 20 g / m ² or less, more preferably 7 g / m ² or more and 15 g / m ² . When the basis weight of the back layer is larger than the basis weight of the surface layer, step breakage, step breakage, breakage, and the like can be reduced at the time of setting while balancing the strength and flexibility of the corrugated base paper.

The density of the back layer is preferably 0.65 g / cm ³ or more and 0.85 g / cm ³ or less, more preferably 0.70 g / cm ³ or more and 0.80 g / cm ³ or less. Thus, there exists a tendency for the intensity | strength of the said corrugated sheet paper to improve by making the density of a back layer into the said range.

  The freeness of the back layer is preferably from 300 mL to 450 mL, more preferably from 320 mL to 430 mL. By setting the freeness of the back layer in the above range, the water absorption of the corrugated sheet paper is improved, and as a result, the bonding property with the liner tends to be improved.

  The freeness of the back layer is preferably larger than the freeness of the surface layer. The difference between the freeness of the back layer and the freeness of the surface layer is preferably 30 mL to 120 mL, and more preferably 40 mL to 110 mL. When the density of the back layer is larger than the density of the surface layer, in this case also, step cracking, step breakage, breakage, and the like can be reduced while balancing, while balancing the strength and flexibility of the corrugated sheet paper.

<Method for producing corrugated base paper for single-sided cardboard sheet>
The corrugated base paper can be obtained by making a raw pulp slurry containing raw pulp or the like into three or more layers and making paper. When the corrugated base paper has a multilayer structure of three or more layers, it becomes easy to satisfy the LC class or more specified in JIS-P-3902: 2011 in terms of basis weight, to adjust the density, and the like. In addition, the surface layer, at least one middle layer and the back layer can be easily characterized.

The corrugated base paper manufacturing method is, for example,
A step of disaggregating and dispersing raw pulp (disaggregation dispersing step);
And a step of making the raw pulp slurry into three or more layers (paper making step).

The manufacturing method of the corrugated paper is as follows:
After the paper making process, a step (coating step) of applying a coating liquid on the surface of the corrugated base paper may be optionally provided. Hereinafter, each step will be described in detail.

(Disaggregation dispersion process)
In this step, raw pulp slurry can be obtained by disaggregating and dispersing raw pulp and the like. At that time, other papermaking chemicals may be optionally dispersed together with the raw material pulp. Examples of other papermaking chemicals include the above papermaking chemicals.

  Examples of the disaggregation dispersion method include a method of dispersing raw pulp and other papermaking chemicals in a tank equipped with a stirrer.

(Paper making process)
In this step, corrugated base paper having a multilayer structure of three or more layers can be obtained by making the paper pulp slurry into three or more layers and making paper. Moreover, the multilayer structure from which the characteristic of a surface layer and a back layer differs can be easily obtained by changing basic weight, raw material pulp kind, etc. More specifically, it is possible to easily obtain a multilayer paper having different water absorption, sliding angle, Beck smoothness and the like between the respective layers.

  Examples of the papermaking method include an acidic papermaking method, a neutral papermaking method, and an alkaline papermaking method. Examples of paper machines include wire part, press part, dryer part, size press part and calendar part, long net multilayer paper machine, twin wire paper machine, circular net paper machine, circular net short net combination paper machine, etc. A circular paper machine is preferred.

  Then, the obtained corrugated sheet paper may be dried by a drying means, for example, using a multi-cylinder dryer, a Yankee dryer, or the like.

(Coating process)
In this step, the cosmetic property, smoothness, etc. of the corrugated paper base surface are improved by applying the coating liquid to the corrugated base paper surface.

  Examples of the coating apparatus include a size press, a blade metering size press, a rod metalling size press, a blade coater, a bar coater, a gate roll coater, a rod coater, and a spray coater.

  Of these, a bar coater is preferable from the viewpoint of easier application.

  The coating concentration of the coating solution is adjusted by the coating means. However, when a clear coating solution such as a lubricant is applied, the solid content concentration of the coating solution is 0.5% by mass or more and 5.0%. % By mass or less is preferable, and 0.8% by mass or more and 4.0% by mass or less is more preferable. Thus, there exists a tendency which can perform coating efficiently by making solid content concentration of a coating liquid into the said range.

  The number of times of coating may be one time, or may be divided into a plurality of times.

  The obtained base paper is subjected to drying.

  Before winding the dried base paper as colored paper, it may be subjected to a calendar process. By applying a calendar process to the base paper, the flatness of the base paper can be improved.

(Other)
Process conditions such as temperature, pressure, time, and equipment in the production process are appropriately set according to the raw materials used. The number of stages of the manufacturing process may be performed in one stage or in multiple stages.

<Physical properties of corrugated paper for single-sided cardboard sheets>
The contact time of 120 seconds of the water of the surface of the wave plate base paper, 20 g / ^{m 2} or more 40 g / ^{m 2} or less, 21g / ^{m 2} or more 38 g / ^{m 2} or less is preferable, 24 g / ^{m 2} or more 34g / m ² or less is more preferable. By making the said water absorption degree into the said range, the strength fall accompanying the careless wetting of the said corrugated sheet paper can be reduced. Further, the surface of the surface layer becomes smooth, and the printability can be improved. When the water absorption exceeds the upper limit, the strength of the corrugated base paper decreases due to inadvertent wetting. If the water absorption is less than the lower limit, the cosmetic properties of the corrugated base paper are deteriorated due to careless wetting. In addition, a water absorption (g / m < ² >) is measured based on JIS-P-8140: 1998 "Paper and paperboard-Water absorption test method-Cobb method".

The back surface of the contact time of 120 seconds water absorption of the wave plate base paper, 175 g / ^{m 2} or more 190 g / ^{m 2} or less, 177 g / ^m is preferably ² or more 190 g / ^{m 2} or less, 180 g / ^{m 2} or more 190 g / m ² or less is more preferable. By making the said water absorption into the said range, the water | moisture content contained in an adhesive agent can fully be absorbed, As a result, the intensity | strength fall of a corrugated sheet can be reduced. When the water absorption exceeds the upper limit, the strength of the corrugated base paper decreases due to inadvertent wetting. When the water absorption is less than the lower limit, the bonding property of the corrugated base paper is lowered.

The water absorption at the contact time of 120 seconds on the back surface of the corrugated paper is higher than that of the front surface, preferably 145 g / m ² or more and 170 g / m ² or less, more preferably 147 g / m ² or more and 161 g / m ^2. By increasing the height below, the back surface becomes more flexible than the front surface, and the corrugated form of the corrugated paper is further improved. In the present invention, various characteristics can be improved by setting a difference between the front surface and the back surface with respect to the water absorption and the following slip angle.

  Further, the water absorption of the contact time of the front surface of 120 seconds is in the above range, and the water absorption of the contact time of the back surface of 120 seconds is in the above range, thereby improving the bonding property between the back surface and the liner, As a result, it is possible to improve the laminating properties, cosmetics, and printability when a single-sided cardboard sheet is formed.

  The slip angle of the corrugated sheet base paper is preferably 12 degrees or more and 22 degrees or less, and more preferably 14 degrees or more and 20 degrees or less. There exists a tendency which can ensure the lubricity of the surface of the said corrugated paper by making the said slip angle into the said range. The sliding angle (degrees) is measured according to JIS-P-8147: 2010 “Paper and paperboard—Static and dynamic friction coefficient measurement method”.

  The slip angle of the back surface of the corrugated paper is preferably 20 degrees or more and 25 degrees or less, and more preferably 22 degrees or more and 24 degrees or less. There exists a tendency which can ensure the slipperiness of the back surface of the said corrugated paper by making the said slip angle into the said range.

  The sliding angle on the front surface is preferably smaller than the sliding angle on the back surface. The difference between the sliding angle on the front surface and the sliding angle on the back surface is preferably 2 degrees or more and 16 degrees or less, and more preferably 4 degrees or more and 14 degrees or less. The slip angle of the front surface is smaller than the slip angle of the back surface, so that when corrugated rolls are stepped into a corrugated sheet shape, the corrugated sheet is likely to be shifted between the corrugated rolls on one surface of the corrugated sheet. During attachment, step cracks, step breaks, breaks, and the like are less likely to occur.

  It is preferable that the Beck smoothness (A) on the surface of the corrugated paper is 20 seconds to 40 seconds and the Beck smoothness (B) on the back surface is 5 seconds to 15 seconds, and the Beck smoothness (A) is More preferably, the Beck smoothness (B) of the back surface is from 25 seconds to 38 seconds and from 6 seconds to 14 seconds. By making the Beck smoothness within the above range, the corrugated base paper surface becomes smooth, and its cosmetic properties and printability are improved. It is possible to cope with a recent processing method in which the corrugated sheet is placed in close contact with the corrugated roll by making a pseudo-vacuum inside the corrugated roll provided as a measure for improving the adhesion with the corrugated roll during the corrugating process. If the Beck smoothness exceeds the upper limit, machining unevenness may occur during step machining. When the Beck smoothness is less than the lower limit, a problem of poor adhesion to the corrugating roll occurs, and as a result, there is a risk that step cracking, step breakage, breakage, and the like are more likely to occur. The Beck smoothness (seconds) is measured according to JIS-P-8119: 1998 “Paper and paperboard—Smoothness test method using Beck smoothness tester”.

  The difference (A−B) between the Beck smoothness on the front surface and the Beck smoothness on the back surface is preferably 10 seconds or longer and 30 seconds or shorter, and more preferably 14 seconds or longer and 27 seconds or shorter. Thus, by providing a difference in the Beck smoothness and setting the Beck smoothness on the back surface low, step breakage, step breakage, breakage, and the like are less likely to occur at the time of stepping similarly to the slip angle. If the difference exceeds the upper limit, the surface smoothness may decrease. If the difference is less than the lower limit, step breakage, step breakage, breakage or the like may easily occur during setting.

  The front Beck smoothness (A) is 20 seconds to 40 seconds and the back Beck smoothness (B) is 5 seconds to 15 seconds, and the difference between the front Beck smoothness and the back Beck smoothness. (A-B) is preferably 10 seconds or longer and 30 seconds or shorter. In this way, by setting a difference in the Beck smoothness between the front and back surfaces of the corrugated sheet and setting the back surface smoothness to a low level, as in the case of the slip angle, step cracks, step breaks, breaks Etc. are less likely to occur.

  As the corrugated paper, it is preferable to satisfy LC class or higher as defined in JIS-P-3902: 2011 in terms of basis weight. Thus, by making the corrugated base paper LC grade or higher, the corrugated base paper exhibits a suitable range of basis weight, compressive strength, burst strength and moisture, and can be widely used in various applications. .

The density of the wave plate base paper, 0.80 g / cm ³ or more 0.90 g / cm ³ or less, 0.81 g / cm ³ or more 0.89 g / cm ³ or less is preferred, 0.82 g / cm ³ or more 0.87 g / cm ³ or less is more preferable. Thus, the intensity | strength of the said corrugated base paper improves by making the density of the said corrugated base paper into the said range. When the density of the corrugated base paper exceeds the upper limit, the flexibility of the corrugated base paper decreases. When the density of the corrugated base paper is less than the lower limit, the strength of the corrugated base paper decreases.

  In addition, when the corrugated base paper has a multilayer structure of three or more layers and the density is in the above range, the balance between the flexibility and strength of the corrugated base paper is obtained, and the strength and single-sided corrugated cardboard sheet are obtained. The cosmetics can be improved.

Conventionally, corrugated base paper has been reduced to a density of about 0.45 g / cm ³ as a countermeasure for molding defects such as step cracking and step crushing in the forming process. Has a problem of degrading the strength performance of the corrugated sheet, and the knowledge of the present inventors has found that the performance can be maintained by setting the density of the corrugated sheet constituting the step to 0.80 g / cm ³ or more. However, if the density of the corrugated base paper is 0.80 g / cm ³ or more, there is a risk of forming defects such as step cracking and step crushing in step formation. The above problem can be improved even if the density of the base paper is 0.80 g / cm ³ or more.

The basis weight of the corrugated paper is preferably 80 g / m ² or more and 180 g / m ² or less, more preferably 90 g / m ² or more and 180 g / m ² or less. In this way, the basis weight of the corrugated sheet paper is within the above range, and the strength as the corrugated sheet base paper is obtained by securing the quality of LC class or higher in basis weight conversion, and damage such as scratches tends not to occur. .

  The average thickness of the corrugated paper is preferably 100 μm or more and 210 μm or less, and more preferably 105 μm or more and 207 μm or less. Thus, there exists a tendency for the intensity | strength of the said corrugated sheet paper to improve by making the average thickness of the said corrugated sheet paper into the said range.

  The compressive strength in the longitudinal direction of the corrugated paper is preferably 1.6 kN / m or more and 3.2 kN / m or less, and more preferably 1.8 kN / m or more and 3.0 kN / m or less. On the other hand, the compressive strength in the transverse direction of the corrugated base paper is preferably 1.0 kN / m or more and 3.5 kN / m or less, and more preferably 1.5 kN / m or more and 3.0 kN / m or less.

  As the compressive strength in the longitudinal direction of the corrugated base paper, the strength of the corrugated base paper is improved by setting the compressive strength to satisfy the LC class or more specified in JIS-P-3902: 2011 in terms of basis weight. Tend. The compressive strength (kN / m) is measured in accordance with JIS-P-8126: 2005 “Paper and paperboard—Compressive strength test method—Ring crush method”.

  The compression strength ratio (longitudinal direction / horizontal direction) is preferably 1.06 or more and 1.54 or less, and more preferably 1.08 or more and 1.52 or less. By setting the compression strength ratio within the above range, the strength of the corrugated paper tends to be improved while maintaining a balance in both directions.

  Moreover, the strength of the corrugated paper is further improved by making the corrugated base paper into an LC class or higher as defined in JIS-P-3902: 2011 in terms of basis weight and making the ratio of the compressive strength to the liner within the above range. Tend to.

The corrugated paper has a specific compressive strength in the longitudinal direction of the corrugated base paper of 135 N · m ² / g or more while satisfying the LC class or more specified in JIS-P-3902: 2011 in terms of basis weight. is preferably from 220N · ^m 2 / g, more preferably at most 139N · ^m 2 / g or more 211N · ^m 2 / g. On the other hand, the specific compressive strength in the transverse direction of the corrugated paper is preferably 100 N · m ² / g or more and 125 N · m ² / g or less, more preferably 108 N · m ² / g or more and 115 N · m ² / g or less. preferable. In addition, specific compressive strength (N * g / m < ² >) is measured based on JIS-P-8126: 2005 "Paper and paperboard-Compression strength test method-Ring crush method".

  The tensile breaking elongation in the longitudinal direction of the corrugated paper is preferably 2.0% or more and 3.5% or less, and more preferably 2.0% or more and 3.3% or less. On the other hand, the tensile breaking elongation in the transverse direction of the corrugated base paper is preferably 5.0% or more and 9.0% or less, and more preferably 7.0% or more and 8.0% or less. In this way, by setting the tensile breaking elongation of the corrugated base paper within the above range, the corrugated sheet shape is stepped while having a performance higher than the LC class specified in JIS-P-3902: 2011 having a relatively high density. There is a tendency that a corrugated sheet for a single-sided corrugated cardboard sheet having excellent cosmetic properties, which is excellent in the shape followability of the corrugated roll to be performed, and is less likely to cause step cracking, step breakage, breakage, or the like during setting. If the tensile elongation at break exceeds the above upper limit, resilience is likely to occur during molding, which may cause a problem of molding failure. When the tensile elongation at break is less than the lower limit, step cracking, step breakage, breakage and the like may easily occur during setting. The tensile elongation at break (%) is measured according to JIS-P-8113: 2006 “Paper and paperboard—Test method for tensile properties—Part 2: Constant speed extension method”.

<Corrugated sheet for single-sided cardboard sheet>
The single-sided corrugated sheet for corrugated sheet (hereinafter also referred to as “corrugated sheet”) refers to a corrugated sheet of corrugated sheet for single-sided corrugated sheet.

The corrugated plate is, for example,
The corrugated base paper can be obtained by a production method including a step (stepping step) for stepping the corrugated paper. More specifically, the corrugated sheet is obtained by passing the corrugated base paper through a pair of corrugated rolls, that is, by engaging the meshing portions of the upper corrugated roll and the lower corrugated roll.

  In general, the corrugated paper is subjected to a strong force such as pulling, bending, and shearing from a pair of corrugated rolls, and the outer side is tensile stressed and the inner side is compressed by bending during corrugating in the thickness direction of the corrugated paper. Due to force and shear stress, step cracking, step breakage, breakage, etc. are likely to occur during setting. However, since the corrugated base paper has the above-described configuration, it is difficult to cause step breakage, step breakage, breakage, or the like during setting by balancing strength and flexibility.

  The number of corrugated plates is preferably 30/30 cm to 80/30 cm, more preferably 40/30 cm to 70/30 cm. By setting the number of steps to be in the above range, there is a tendency that step cracks, step breaks, breaks, and the like do not easily occur during setting.

  The step height of the corrugated plate is preferably 1.0 mm or more and 1.5 mm or less, and more preferably 1.05 mm or more and 1.45 mm or less. By setting the number of steps to be in the above range, there is a tendency that step cracks, step breaks, breaks, and the like do not easily occur during setting.

<Single-sided cardboard sheet>
The single-sided cardboard sheet is a sheet in which the back surface of the corrugated sheet and a liner are bonded together.

The single-sided cardboard sheet is, for example,
It can obtain by the manufacturing method provided with the process (bonding process) which bonds the back surface of the corrugated sheet for single-sided cardboard sheets, and a liner using an adhesive agent.

  The stepping step and the bonding step may be performed separately, for example, as a series of steps using a corrugator or the like.

  Examples of the adhesive include synthetic resins such as polyethylene, polypropylene, polyamide, and polyester, starch, gum arabic, polyvinyl alcohol, carboxymethyl cellulose, and vinyl acetate alcohol. These may be used singly or may be used in combination of plural kinds as long as the effects of the present invention are not impaired.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited by these. In addition, the evaluation method of quality and performance performed in the present Example is as follows.

<Evaluation method>
Various physical properties in Examples and Comparative Examples were measured according to the following evaluation methods.

(Basis weight (g / m ² ))
The basis weight (g / m ² ) was measured in accordance with JIS-P-8124: 1998 “Paper and paperboard—Method of measuring basis weight”.

(Density (g / cm ³ ))
The density (g / cm ³ ) was measured according to JIS-P-8118: 1998 “Paper and paperboard—Test method for thickness and density”.

(Freeness (mL))
The freeness (mL) of the paper layer was disaggregated according to JIS-P-8220: 1998 “pulp-disaggregation method”, and the obtained disaggregated pulp was subjected to JIS-P-8121: 1995 “pulp freeness test. Evaluation was made according to “Method”.

(Ash (mass%))
Ash content (mass%) was measured according to JIS-P-8251: 2003 “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method”.

(Water absorption (g / m ² ))
The water absorption (g / m ² ) was measured in accordance with JIS-P-8140: 1998 “Paper and paperboard—Water absorption test method—Cobb method”.

(Slip angle (degree))
The sliding angle (degree) was measured according to JIS-P-8147: 2010 “Paper and paperboard—Static and dynamic friction coefficient measurement method”.

(Beck smoothness (seconds))
The Beck smoothness (seconds) was measured according to JIS-P-8119: 1998 “Paper and paperboard—Smoothness test method using Beck smoothness tester”.

(grade)
The grade was determined in accordance with JIS-P-3902: 2011 “corrugated liner”.

(Average thickness (μm))
The average thickness (μm) was measured in accordance with JIS-P-8118: 1998 “Paper and paperboard—Test method for thickness and density”.

(Compressive strength (kN / m))
The compressive strength (kN / m) was measured according to JIS-P-8126: 2005 “Paper and paperboard—Compressive strength test method—Ring crush method”.

(Specific compression strength (N · m ² / g))
The specific compressive strength (N · m ² / g) was measured in accordance with JIS-P-8126: 2005 “Paper and paperboard—Compressive strength test method—Ring crush method”.

(Tensile breaking elongation (%))
The tensile elongation at break (%) was measured in accordance with JIS-P-8113: 2006 “Paper and paperboard—Test method for tensile properties—Part 2: Constant speed extension method”.

(Step cracks, step breaks, breaks during stepping)
Step cracks, step breaks, and breaks during stepping were visually evaluated based on the following criteria.
(Double-circle): There is no step crack, step break, and a fracture | rupture.
○: Step cracks, step breaks, and breakage occurred slightly.
Δ: Step cracks, step breaks, and breakage occurred somewhat.
X: Many step cracks, step breaks, and breaks occurred.
In addition, ◎ and ○ were actually usable.

(Beauty)
The cosmetic properties of the single-sided cardboard sheet were visually evaluated based on the following criteria.
(Double-circle): There is no step crack, a step break, a fracture | rupture, and poor bonding, and it is excellent in cosmetics.
○: Step cracks, step breaks, breakage, and poor bonding occurred slightly, but the cosmetics were good.
Δ: Step cracks, step breaks, breakage, and poor bonding occurred to some extent, but the cosmetics were slightly inferior.
X: Many step cracks, step breaks, breakage and poor bonding occur, resulting in poor cosmetic properties.
In addition, ◎ and ○ were actually usable.

(Printability)
The surface was printed using a “K printing proofer” from PK Print Coat Instruments. As the ink, DANEC3-indigo manufactured by Toyo Ink was used, and the amount of ink was 5 mL. Evaluation was performed according to the following criteria.
A: Uneven coloring of ink, poor transfer of ink, etc. cannot be visually observed.
○: Ink coloring unevenness, ink transfer failure, etc. are slightly visible.
Δ: Ink uneven coloring, poor ink transfer, etc.
X: There are many uneven coloring of ink, poor transfer of ink, and the like.
In addition, ◎ and ○ were actually usable.

(Adhesion (workability))
Single-sided corrugated cardboard liner and corrugated paper for single-sided cardboard are bonded at a bonding speed of 180 m / min using a corrugator machine (“Corrugator CWDX” from ISOWA) and glue (“Low Cons” from Nippon Starch). A sheet was obtained. The bonding part (joint part of a sheet | seat) of the single-sided cardboard sheet | seat obtained after 1 minute was peeled by hand, and it evaluated based on the following references | standards.
(Double-circle): The part where the paste pasting part did not peel (the corrugated cardboard sheet was destroyed) is 2/3 or more of the entire paste pasting area, and is excellent in paste pasting ability.
◯: The portion where the paste application part did not peel (the corrugated cardboard sheet was destroyed) was 1/3 or more of the entire paste application area, and the paste application property was good.
(Triangle | delta): The part which the paste pasting part did not peel (the corrugated cardboard sheet was destroyed) is 1/3 or less of the whole paste pasting area, and paste pasting ability is somewhat bad.
X: There is no portion where the paste application part was not peeled off (the corrugated cardboard sheet was destroyed), and the paste application property was poor.
In addition, ◎ and ○ were actually usable.

<Example 1>
Using the following raw materials, a corrugated base paper for a single-sided corrugated cardboard sheet having three layers consisting of a surface layer, a middle layer and a back layer was obtained according to the following production method.

(Disaggregation dispersion process)
[Surface pulp slurry for surface layer]
After blending 2% by mass of carbon black (“Grand Black YT-100” from Gokoku Dye Co., Ltd.) as a pigment with Kamihaku old paper pulp, a raw material pulp slurry for the surface layer was prepared using a double disc refiner.

[Raw material pulp slurry for middle layer]
After blending the old paper pulp, the middle layer raw material pulp slurry was prepared using a double disc refiner.

[Raw material pulp slurry]
After blending the local paper waste paper pulp, the back layer raw material pulp slurry was prepared using a double disc refiner.

(Paper making process)
Using these raw material pulp slurries, the paper layers of the surface layer, middle layer and back layer are made with a circular paper machine, adjusted to 51% moisture, and dried while being pressed against the mirror-finished Yankee dryer surface. did.

(Coating process)
A cationic alkyl ketene dimer (“Dimmer S-20” from Daiwa Chemical Co., Ltd.) as a lubricant was diluted to produce a coating solution having a solid content of 3% by mass. Subsequently, the coating liquid was applied to the surface of the corrugated sheet for single-sided cardboard sheets using a bar coater to produce corrugated sheet for single-sided cardboard sheets.

(Stepping process and bonding process)
Using corrugator machine ("Corrugator CWDX" from ISOWA), corrugated base paper after application was stepped, and then obtained corrugated board and liner ("Just Economy" from Daio Paper Corporation, 120g / m ² ) Single-sided corrugated cardboard using a starch ("Laucons" from Nippon Starch Co., Ltd.) and a coated surface (3.2 g / m ² ) at a bonding speed of 180 m / min. A sheet was produced.

<Examples 2 to 15 and Comparative Examples 1 to 5>
Corrugated base paper, corrugated sheet and single-sided cardboard sheet were produced in the same manner as in Example 1 except that the raw materials and the like of Example 1 were changed as shown in Tables 1 to 3. Tables 1 to 3 show the physical properties and evaluation of the corrugated base paper, corrugated sheet and single-sided cardboard sheet, and the raw materials used.

  As is apparent from the above results, in the examples, the corrugated paper for single-sided corrugated cardboard sheet has excellent compressive strength, specific compressive strength and tensile elongation at break, and cosmetics when used as a single-faced corrugated sheet. Step cracks, step breaks, breaks, etc. are unlikely to occur. Moreover, the single-sided corrugated cardboard sheet was excellent in bonding property and printability. On the other hand, in the comparative example, these performances were insufficient.

  The corrugated paper for single-sided corrugated cardboard sheet is excellent in strength and bonding properties, cosmetics and printability when used as a single-sided corrugated cardboard sheet, and does not easily cause step breakage, breakage, breakage, and the like. Therefore, the single-sided cardboard sheet using the corrugated paper for single-sided cardboard sheets can be suitably used as a packaging exterior material for confectionery, food, electrical appliances and the like.

Claims (3)

A corrugated base paper for a single-sided corrugated cardboard sheet that has a multilayer structure of three or more layers, is processed into a corrugated sheet, and is bonded to the liner on the back surface,
At least a coating solution containing a lubricant is applied to the surface,
The density is 0.80 g / cm ³ or more and 0.90 g / cm ³ or less,
The ash content of the surface layer is 15% by mass or less,
The water absorption at a surface contact time of 120 seconds is 20 g / m ² or more and 40 g / m ² or less,
Faced cardboard corrugated base paper sheet, wherein the contact time of 120 seconds water absorption of the back surface is not more than 175 g / ^{m 2} or more 190 g / ^{m 2.} The sliding angle of the front surface is smaller than the sliding angle of the back surface,
The surface Beck smoothness (A) is 20 seconds or more and 40 seconds or less,
The corrugated paper for a single-sided cardboard sheet according to claim 1, wherein the back surface Beck smoothness (B) is 5 seconds or more and 15 seconds or less.   The corrugated paper base sheet for a single-sided corrugated cardboard sheet according to claim 1 or 2, wherein the compressive strength is not less than the LC class specified in JIS-P-3902: 2011 in terms of basis weight.