TW202043050A - Liner for cardboard and manufacturing method of liner for cardboard - Google Patents

Abstract

This liner for cardboard is provided with at least a top surface layer, a subsurface layer and a back surface layer. The top surface layer contains softwood craft pulp, and the content of softwood craft pulp in the top surface layer is greater than or equal to 80 mass%; the subsurface layer contains softwood craft pulp and cardboard waste paper pulp and the content of softwood craft pulp in the subsurface layer is 25-35 mass%; the back surface layer contains cardboard waste paper pulp and magazine waste paper pulp, the content of the cardboard waste paper pulp in the back surface layer is 30-70 mass% and the content of the magazine waste paper pulp in the back surface layer is 30-70 mass%; and the ratio of the basis weight of the top surface layer to the overall basis weight is 20-35%, and the burst index in an atmosphere 80% RH and at 60 DEG C is greater than or equal to 3.45 kPa*m2/g.

Description

Corrugated board lining and manufacturing method of corrugated board lining

The invention relates to a corrugated board lining and a manufacturing method of the corrugated board lining.

In recent years, for corrugated cardboard used for packaging containers for packaging in Southeast Asia, a corrugated cardboard lining of normal quality has been used. Compared with wooden and resin containers, linings for corrugated cardboard are lighter and have cushioning properties, so the contents are hard to break, so they are used in various fields such as precision equipment.

As a multilayer papermaking used in such packaging containers for packaging, for example, Patent Document 1 discloses the following technology: In a paper substrate having a first layer, a second layer, and a third layer in this order, by making the outer layer The density of the first and third layers is higher than that of the second layer as the intermediate layer, so that a paper substrate with excellent double-sided printing adaptability and double-sided lamination processing adaptability can be obtained (refer to Patent Document 1 ). Here, it is disclosed that by changing the density characteristics of each layer structure, it is possible to improve the suitability for printing and lamination processing.

The kraft paper disclosed in Patent Document 2 discloses the following kraft paper: When processed into a bag, it is used as a kraft paper that rarely causes bag breakage. By intervening in the longitudinal and transverse breaking elongation, it becomes the kraft paper that makes the longitudinal and transverse breaking elongation etc. Kraft paper manufactured in a specific relationship has excellent elongation properties and strength properties. Patent Document 3 discloses a kraft paper for heavy packaging. The kraft pulp is viscously beaten so that the kraft pulp has a liquid pulp concentration of 4.0 to 4.5% by weight and a weight average fiber length of 2.3 to 4.0 mm, and dissociates The kraft pulp is made into paper so that the freeness becomes 600ml～680ml, so that the strength of the paper support can be maintained within the JIS standard, and the paper support can be provided with high air permeability, and the raw material cost can be reduced with a low basis weight. cost.

In this way, in the prior art, the emphasis is on tear strength, tensile strength, suppression of creasing line breakage, and improvement of printing adaptability.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2017-002433.

Patent Document 2: Japanese Patent Publication No. 2014-053372.

Patent Document 3: Japanese Patent Laid-Open Publication No. 2006-089889.

However, in Southeast Asia, there are many unpaved roads, and packaging containers are prone to breakage due to rough vibrations on the road during transportation. In addition, the high temperature and humidity environment called abnormal weather in the country often occurs in Southeast Asia. In addition, the surface of such a corrugated cardboard lining is printed with product information or the like or laminated with a laminated film. Therefore, the corrugated cardboard lining requires sufficient strength under the above-mentioned environment. Therefore, in order to be used in applications corresponding to impact on unpaved roads and use in high temperature and humidity environments, corrugated cardboard linings are required to have excellent impact resistance and improve impact resistance during transportation and in high temperature and humidity environments. Sex.

As a general method to improve the impact resistance of corrugated board linings, it is considered to use more paper strength enhancers for improving paper strength. However, in this case, the corrugated board linings become hard as a whole and compress The problem of broken traces and the high cost of medicine have become problems. In addition, in recent years, linings for corrugated cardboard have also been required to reuse waste paper to realize environmentally friendly materials.

The present invention is made based on the above circumstances. The purpose of the present invention is to provide a corrugated board for reusing waste paper pulp and improving impact resistance when transported on unpaved roads and in high temperature and humidity environments. Lining.

The corrugated cardboard lining of the embodiment of the present invention has at least a surface layer, a lower surface layer and a back layer, the surface layer contains softwood kraft pulp, and the content of the softwood kraft pulp in the surface layer is 80% by mass or more The lower surface layer contains softwood kraft pulp and waste corrugated paper pulp, the content of the softwood kraft pulp in the lower surface layer is 25% by mass or more and 35% by mass or less, and the back layer contains corrugated waste paper pulp and magazines. Waste paper pulp, wherein the content of the corrugated paper waste paper pulp in the back layer is 30% by mass or more and 70% by mass or less, and the content of the magazine waste paper pulp in the back layer is 30% by mass or more and 70% by mass or less The ratio of the basis weight of the surface layer to the total basis weight is 20% or more and 35% or less, and the burst resistance index in an atmosphere of 60° C. and 80% RH is 3.45 kPa·m ² /g or more.

In the method of manufacturing a corrugated cardboard liner according to another embodiment of the present invention, the corrugated cardboard lining includes at least a surface layer, a lower surface layer, and a back layer, and the method of manufacturing a corrugated cardboard lining includes using a paper machine to The papermaking process of raw material pulp for papermaking, the papermaking machine performs papermaking on the pulp raw material ejected onto the traveling net, the raw material pulp contains softwood kraft pulp, corrugated paper waste paper pulp, magazine waste paper pulp or a combination thereof, and the surface layer The ratio J/W of the ejection speed J of the pulp raw material to the traveling speed W of the wire in the papermaking process of the back layer is larger than J/W of the lower surface layer.

According to the present invention, it is possible to provide an inner liner for corrugated cardboard that can realize the reuse of waste paper pulp and can improve the impact resistance during transportation on unpaved roads and in high temperature and humidity environments.

[Description of the embodiment of the present invention]

The liner for corrugated cardboard of the embodiment of the present invention includes at least a surface layer, a lower surface layer, and a back layer. The surface layer contains softwood kraft pulp, and the content of the softwood kraft pulp in the surface layer is 80% by mass or more. The lower surface layer contains softwood kraft pulp and corrugated waste paper pulp, and the content of the softwood kraft pulp in the lower surface layer is 25% by mass or more and 35% by mass or less. In addition, the back layer contains corrugated paper waste paper pulp and magazine waste paper pulp, and the content of the corrugated paper waste paper pulp in the back layer is 30% by mass to 70% by mass, and the magazine waste paper pulp in the back layer The content of is 30% by mass or more and 70% by mass or less. The ratio of the basis weight of the surface layer to the total basis weight is 20% or more and 35% or less. The lining for corrugated cardboard has a burst resistance index of 3.45 kPa·m ² /g or more in an atmosphere of 60° C. and 80% RH.

In this way, the surface layer contains softwood kraft pulp, and by increasing the content of softwood kraft pulp in the surface layer located on the outermost side as a packing material for corrugated cardboard, it is not only possible to achieve resistance to high temperature and humidity. The breakage index is improved, and the surface strength under high temperature and humidity environment can be improved. In addition, for the main component of the raw material pulp of the back layer located on the backmost side as a packing material for corrugated cardboard, by combining corrugated paper pulp and magazine waste paper pulp, it is possible to set the Cobb value to a low Good adhesion, and can improve the burst index under high temperature and humidity environment. In addition, the lower surface layer contains softwood kraft pulp and corrugated paper pulp, and the content of softwood kraft pulp is within the above range to increase the content of corrugated paper pulp, thereby realizing the reuse of waste paper pulp, and It can improve the burst resistance index under high temperature and humidity environment. In addition, by allowing the surface layer to occupy 20% to 35% of the total amount of the corrugated board lining, it is possible to ensure the maintenance of impact resistance, the flexibility and cushioning properties of the corrugated board lining, and it can be used for corrugated board. The burst resistance index of the lining in a high temperature and humidity environment is 3.45kPa·m ² /g or more. Therefore, according to this corrugated cardboard lining, it is possible to provide a corrugated cardboard lining that can withstand the impact during transportation on an unpaved road and exhibit excellent impact resistance even in a high temperature and high humidity environment. In addition, according to the present invention, it is possible to obtain an inner liner for corrugated cardboard that is also excellent in carton formability. Such a corrugated cardboard liner can be used particularly well for corrugated cardboard used in packaging containers for packaging in Southeast Asia.

Preferably, the surface layer and the back surface layer contain a sizing agent, and the Cobb value of the surface layer and the back surface layer for a measurement time of 2 minutes is 10 g/m ² or more and 50 g/m ² or less. In this way, by making the surface layer and the back layer contain a sizing agent, and the Cobb value of the measurement time of the surface layer and the back layer for 2 minutes is in the above range, it can be used in a high temperature and humidity environment. The humidity in the lining for corrugated cardboard can be suppressed, and the quality of the lining for corrugated cardboard can be maintained.

Preferably, the surface layer and the lower surface layer contain a paper strength enhancer, and the added amount of the paper strength enhancer of the lower surface layer is larger than the added amount of the paper strength enhancer of the surface layer. By containing the paper strength enhancer, the impact resistance can be improved, but the inclusion of the paper strength enhancer may impair the flexibility of the paper layer. In addition, in the surface layer of the corrugated cardboard lining, there is a large content of softwood kraft pulp that contributes to the improvement of impact resistance. Therefore, by making the addition amount of the paper strength agent in the lower surface layer larger than the addition amount of the paper strength agent in the surface layer, flexibility can be ensured, and breakage of the surface layer such as indentation line breakage can be suppressed. Improve impact resistance when transported on unpaved roads and in high temperature and humidity environments.

Preferably, the density of the corrugated board lining is 0.65 g/cm ³ or more and 0.85 g/cm ³ or less. By setting the density of the liner for corrugated cardboard within the above-mentioned range, cushioning properties can be imparted, and high impact resistance can be exhibited without adding more than necessary paper strength enhancers.

Preferably, the freeness of the dissociated pulp dissociated in accordance with JIS-P8220 (1998) is 420 ml or more and 460 ml or less. By setting the freeness of the dissociated pulp of the corrugated cardboard lining to be 420 ml or more and 460 ml or less, the corrugated cardboard lining can maintain the burst resistance index in a high temperature and humidity environment and improve the carton molding suitability.

In the method of manufacturing a corrugated cardboard liner according to another embodiment of the present invention, the corrugated cardboard lining includes at least a surface layer, a lower surface layer, and a back layer, and the method of manufacturing a corrugated cardboard lining includes using a paper machine to The process of making paper with raw material pulp. The papermaking machine performs papermaking on the pulp raw material ejected onto the traveling net. The raw material pulp contains softwood kraft pulp, corrugated paper waste paper pulp, magazine waste paper pulp or a combination thereof, and the surface layer and The ratio J/W of the ejection speed J of the pulp raw material to the traveling speed W of the wire in the papermaking process of the back layer is larger than J/W of the lower surface layer.

The manufacturing method of the corrugated board lining includes a process of making paper from a raw material pulp containing softwood kraft pulp, corrugated paper waste paper pulp, magazine waste paper pulp, or a combination thereof, and the papermaking of the surface layer and the back layer The ratio J/W of the ejection speed J of the pulp raw material to the traveling speed W of the web in the process is larger than the J/W of the lower surface layer, so that a good fiber orientation ratio can be obtained. As a result, it is possible to improve the impact resistance during transportation on an unpaved road and in a high temperature and humidity environment.

[Details of the embodiment of the present invention]

The present invention will be described in detail below. The description of the constituent elements described below is based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

＜Liner for corrugated cardboard＞

The liner for corrugated cardboard of the embodiment of the present invention includes at least a surface layer, a lower surface layer, and a back layer in this order. In addition, the liner for corrugated cardboard may include a single or multiple layers between the lower surface layer and the back layer. That is, the liner for corrugated cardboard may be a multi-layer paper made of at least three layers, and in the case of a multi-layer paper made of four or more layers, it is preferable to provide a second lower surface layer between the lower surface layer and the back layer. The structure in which a second back layer is provided between the lower surface layer and the back layer. In this way, it is preferable to make the surface lower layer, the back layer or the combination thereof into a multilayer structure. By adopting such a structure, the corrugated cardboard lining can improve the flexibility of the paper layer, and can achieve carton molding adaptability and impact resistance. improve.

[Surface layer]

The surface layer contains softwood kraft pulp (NUKP).

The lower limit of the content of the softwood kraft pulp in the surface layer is 80% by mass, and preferably 90% by mass. By making the surface layer contain softwood kraft pulp and corrugated paper pulp, and increasing the content of softwood kraft pulp in the surface layer located on the most surface side as a packing material for corrugated cardboard, not only can high temperature and humidity be achieved The breaking index under the environment is improved, and the surface strength under the high temperature and humidity environment can be improved. If the content of softwood kraft pulp in the surface layer is less than 80% by mass, it may be difficult to ensure the desired impact resistance. In addition, when the content of softwood kraft pulp in the surface layer is less than 80% by mass, since the content of long fibers decreases, the strength of the surface layer decreases, and there is a possibility that indentation line breakage may easily occur. In addition, from the viewpoint of recyclability, it is preferable to use waste paper pulp within a range of less than 20% and not lowering impact resistance.

[Subsurface layer]

The lower surface layer contains softwood kraft pulp (NUKP) and corrugated waste paper pulp.

The lower limit of the content of the softwood kraft pulp in the lower surface layer is 25% by mass, and more preferably 30% by mass. The upper limit of the content of softwood kraft pulp is 35% by mass, preferably 34% by mass. The lower surface layer contains softwood kraft pulp and corrugated paper pulp, and the content of softwood kraft pulp is within the above range to increase the content of corrugated paper pulp, thereby realizing the reuse of waste paper pulp and improving Bursting index under high temperature and humidity environment.

[Back layer]

The back layer contains corrugated paper waste paper pulp and magazine waste paper pulp. In addition, the back layer may also contain softwood kraft pulp.

The lower limit of the content of the waste corrugated paper pulp in the back layer is 30% by mass, and preferably 31% by mass. The upper limit of the content of the waste corrugated paper pulp is 70% by mass, preferably 60% by mass. In addition, the lower limit of the content of the magazine waste paper pulp on the back surface is 30% by mass, and preferably 50% by mass. The upper limit of the content of the magazine waste paper pulp is 70% by mass, preferably 60% by mass. In order to maintain the quality of the corrugated cardboard lining in a high-temperature and high-humidity environment, it is necessary to suppress the increase in humidity in the corrugated cardboard lining and to improve the adhesion of the back layer. Therefore, it is necessary to set a high Cobb value. However, for the main component of the raw material pulp of the back layer located on the backmost side as a packing material for corrugated cardboard, by combining corrugated paper pulp and magazine waste paper pulp, it is possible to set a lower Cobb value while having good It can improve the carton forming adaptability required for the corrugated cardboard lining.

In addition, in addition to the softwood kraft pulp, corrugated paper waste paper pulp, and magazine waste paper pulp for each layer of the corrugated board lining, other pulps such as tea paper waste paper, kraft envelope waste paper, and newspaper waste paper can also be used. , Leaflet waste paper, office waste paper, high-quality white waste paper, Kent paper waste paper, construction paper waste paper, land certificate waste paper, etc. dissociated waste paper pulp, dissociated deinked waste paper pulp, deinked bleached waste paper pulp, etc. In addition, mechanical pulp such as groundwood pulp (GP), thermomechanical pulp (TMP), and bleached chemical thermomechanical pulp (BCTMP) can also be used as needed.

[additive]

(Sizing agent)

Preferably, the lining for corrugated cardboard is added with a sizing agent in each layer. By making each layer of the corrugated cardboard lining contain a sizing agent, durability against humidity in the corrugated cardboard lining can be improved under a high temperature and high humidity environment, and the quality of the corrugated cardboard lining can be maintained. The sizing agent may include styrene-based sizing agent, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), neutral rosin sizing agent and rosin sizing agent. Among them, preferred are rosin sizing agents.

The rosin sizing agent is not particularly limited, and materials well known in the papermaking field can be used. Examples of rosin-based substances include enhanced rosins obtained by modifying rosins such as gum rosin, wood rosin, and tall oil rosin with α, β-unsaturated carboxylic acids such as fumaric acid, maleic acid, and acrylic acid or their anhydrides. ; Rosin ester obtained by reacting polyhydric alcohols such as glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, and diglycerin with the rosins. In addition, in the present invention, the rosin-based sizing agent includes a substance obtained by emulsifying them individually or a mixture thereof, and a substance obtained by mixing after emulsifying them individually. In addition, the rosin-based sizing agent obtained by the emulsification also includes a sizing agent obtained by adding various polymers in order to further improve the sizing visibility.

As the lower limit of the amount of the sizing agent added for each layer, 0.50 kg/pulp t in terms of solid content is preferable, and 1.50 kg/pulp t is more preferable. In addition, as the upper limit of the content of the sizing agent in each layer, 5.00 kg/pulp t in terms of solid content is preferable, and 4.00 kg/pulp t is more preferable. By setting the addition amount of the sizing agent within the above range, sufficient water resistance can be imparted to the corrugated cardboard lining, and durability against humidity in the corrugated cardboard lining can be improved even in a high temperature and high humidity environment. In addition, by adding cationic starch, the paper strength of each layer can be enhanced, and a corrugated board lining with high impact resistance can be obtained. In addition, "kg/pulp t" represents the addition amount (kg) relative to 1 ton of pulp.

(Paper Strength Enhancer)

Preferably, the corrugated cardboard lining is added with a paper strength enhancer in each layer. By adding a paper strength enhancer, the bond between corrugated waste paper pulp and magazine waste paper pulp, which is fatigued by the recycling process of waste paper and is composed of relatively flat pulp fibers, is strengthened, so that it can further increase 60°C and 80%RH The burst resistance index under the atmosphere.

The paper strength enhancer includes starch-based paper strength enhancers, acrylamide-based paper strength enhancers, vinyl alcohol-based paper strength enhancers, amino epoxy resin-based paper strength enhancers, etc. Among them, acrylamide-based paper strength enhancers are preferred. Paper strength enhancer. More preferred is an amphoteric polypropylene amide resin-based paper strength enhancer. Amphoteric polyacrylamide is a substance obtained by polymerizing cationic monomers, anionic monomers and acrylamide, and is directly fixed on the pulp fibers through its own cationic groups. In addition, the amphoteric polypropylene amide resin-based paper strength enhancer is characterized by being able to control the molecular structure and molecular weight.

Preferably, the addition amount of the paper strength agent in the lower surface layer is larger than the addition amount of the paper strength agent in the surface layer. By containing the paper strength enhancer, the impact resistance can be improved, but the inclusion of the paper strength enhancer may impair the flexibility of the paper layer. In addition, in the surface layer of the corrugated cardboard lining, softwood kraft pulp, which contributes to improvement of impact resistance, is added in a large amount. Therefore, by making the addition amount of the paper strength agent in the lower surface layer larger than the addition amount of the paper strength agent in the surface layer, flexibility can be ensured, and surface layer breakage such as indentation line breakage can be suppressed, which can further improve the Impact resistance when transported on unpaved roads and in high temperature and humidity environments. In addition, by making the addition amount of the paper strength agent of the back layer larger than the addition amount of the paper strength agent of the surface layer, the impact resistance in a high temperature and high humidity environment can be further improved.

The lower limit of the added amount of the paper strength agent of the surface layer is preferably 0.40 kg/pulp t in terms of solid content, and more preferably 0.8 kg/pulp t. In addition, as the upper limit of the added amount of the paper strength enhancer of each layer, 9.0 kg/pulp t in terms of solid content is preferable, and 8.0 kg/pulp t is more preferable. If the addition ratio of the paper strength enhancer of the surface layer exceeds the upper limit, the water filterability becomes poor, and the pulp raw material is easily discharged in the pressing and dewatering process in the press section of the paper machine. In addition, in the press section, the lees of the pulp raw material adhere to the doctor blade used when peeling the wet paper stuck to the roll, and the quality of the surface layer may be reduced. On the other hand, as the lower limit of the added amount of the paper strength agent of the lower surface layer and the back layer, in terms of solid content, 6.0 kg/pulp t is preferable, and 6.4 kg/pulp t is more preferable. In addition, as the upper limit of the added amount of the paper strength agent for the lower surface layer and the back layer, in terms of solid content, it is preferably 8.0 kg/pulp t, and more preferably 7.0 kg/pulp t. By setting the addition amount of the paper strength agent of each layer within the above-mentioned range, the flexibility of the corrugated board liner can be ensured, and the burst resistance index in an atmosphere of 60° C. and 80% RH can be improved.

(Other additives)

In the present invention, the liner for corrugated cardboard composed of various layers such as a surface layer, a subsurface layer, an intermediate layer, and a back layer may contain various additives for papermaking within a range that does not impair the intended effects of the present invention. For example, retention aids, pigment dispersants, pH adjusters, tackifiers, flow modifiers, defoamers, foam inhibitors, mold release agents, penetrants, UV absorbers can be added individually or in combination of two or more Agents, antioxidants, preservatives, antifungal agents, fluorescent eliminators, resin control agents, slimeicides, aluminum sulfate and other reagent fixatives, polyamides, polyamines, epichlorohydrin and other water-repellent agents, clay, Fillers such as talc and calcium carbonate, basic dyes, acid dyes, anionic direct dyes, cationic direct dyes and other well-known additives.

[Physical properties of lining for corrugated cardboard]

(Quantitative)

Quantitative measurement is performed in accordance with JIS-P8124 (2011). In a further preferred embodiment of the present invention, the total basis weight of the corrugated cardboard lining is preferably 120 g/m ² to 250 g/m ² , and more preferably 130 g/m ² to 240 g/m ² . In addition, the basis weight of the back layer constituting the corrugated cardboard liner is preferably 25 g/m ² to 115 g/m ² , and more preferably 30 g/m ² to 110 g/m ² . The basis weight of the surface layer is preferably 38 g/m ² to 52 g/m ² , and more preferably 40 g/m ² to 50 g/m ² . The basis weight of the lower surface layer is preferably 20 g/m ² to 85 g/m ² , and more preferably 39 g/m ² to 80 g/m ² . In the corrugated cardboard liner of the present invention, by setting the overall basis weight within the above-mentioned range, the moldability during carton molding can be improved, and the filling of the content after molding can be suppressed even in a high temperature and humidity environment Damage to the packaging container at the time.

In the surface layer, the lower limit of the ratio of the quantification of the surface layer to the total quantification is 20%, preferably 21%. In addition, the upper limit of the ratio of the basis weight of the surface layer to the total basis weight is 35%, preferably 32%. By setting the ratio of the basis weight of the surface layer within the above range, the impact resistance in a high temperature and high humidity environment can be maintained, and the flexibility and cushioning properties of the liner for corrugated cardboard can be ensured.

(density)

The lower limit of the density of the liner for corrugated cardboard is preferably 0.65 g/cm ³ , and more preferably 0.67 g/cm ³ . The upper limit of the density is preferably 0.85 g/cm ³ , and more preferably 0.80 g/cm ³ . By setting the density of the liner for corrugated cardboard within the above-mentioned range, cushioning properties can be imparted, and high impact resistance can be exhibited without adding more than necessary paper strength enhancers. In addition, it is preferable that the density of the lower surface layer is lower than the density of the surface layer and the density of the back layer. By making the density of the subsurface layer lower than the density of the surface layer and the density of the back layer, it is possible to further improve the impact resistance in a high temperature and high humidity environment. The lower limit of the density of the lower surface layer is preferably 0.48 g/cm ³ , and more preferably 0.50 g/cm ³ . The upper limit of the density of the lower surface layer is preferably 0.95 g/cm ³ , and more preferably 0.82 g/cm ³ .

(Paper thickness)

The paper thickness is measured in accordance with "Paper and board paper-Test methods for thickness and density" described in JIS-P8118 (2014). The overall paper thickness of the liner for corrugated cardboard of the present invention is preferably 178 μm to 370 μm, and more preferably 180 μm to 360 μm. In addition, the paper thickness of the back layer constituting the liner for corrugated cardboard is preferably 38 μm to 145 μm, and more preferably 40 μm to 140 μm. The paper thickness of the lower surface layer is preferably 45 μm to 165 μm, and more preferably 49 μm to 160 μm. In addition, when the lower surface layer has a multilayer structure as described above, it is preferable that the total paper thickness of the layers constituting the lower surface layer falls within the above-mentioned range. In addition, the paper thickness of the surface layer is preferably 52 μm to 62 μm, and more preferably 53 μm to 60 μm. By setting the overall paper thickness of the corrugated cardboard lining and the paper thickness of each layer within the above-mentioned ranges, impact resistance and carton formability can be improved.

(Cobb value)

The Cobb value is measured in accordance with JIS-P8140 (1998), and the measurement time is set to 2 minutes. The lower limit of the Cobb value of the corrugated cardboard lining is preferably 10 g/m ² , and more preferably 20 g/m ² . When the Cobb value of the corrugated cardboard lining is less than the lower limit, the humidity in the corrugated cardboard lining may not be sufficiently suppressed under a high temperature and humidity environment, and it may be processed into a carton, etc. Lead to poor fit. On the other hand, the upper limit of the Cobb value of the lining for corrugated cardboard is preferably 50 g/m ² , and more preferably 40 g/m ² . When the Cobb value of the corrugated cardboard lining is higher than the above-mentioned upper limit, the corrugated cardboard lining may cause ripples and wrinkles due to moisture absorption. By setting the Cobb value of the measurement time of the surface layer and the back layer to 2 minutes in the above range, the humidity in the corrugated cardboard lining can be suppressed under a high temperature and humidity environment, and the corrugated cardboard can be realized Maintain the quality of the lining. In order to maintain the quality of the corrugated cardboard lining in a high-temperature and high-humidity environment, it is necessary to suppress the increase in humidity in the corrugated cardboard lining and to improve the adhesion of the back layer. Therefore, in the past, it was necessary to set a high Cobb value. However, by realizing the combined use of corrugated paper waste paper pulp and magazine waste paper pulp as the main component of the raw material pulp of the back layer, it is possible to set a low Cobb value while having good adhesion, and can improve the high temperature and humidity environment.的rupture index.

(Bursting index)

Bursting index is specified by JIS-P8131 (2009). The burst resistance index is a value obtained by dividing the burst resistance of paper expressed in kilopascal (kPa) units by the quantitative value measured in accordance with the aforementioned JIS-P8131 (2009). The corrugated cardboard liner 60 ℃, the lower limit of the burst index at 80% RH atmosphere for 3.45kPa · m ² / g, and more preferably 3.80kPa · m ² / g. By setting the burst resistance index within the above range, the impact resistance of the corrugated cardboard lining when transported on an unpaved road surface and in a high temperature and humidity environment can be improved. The above-mentioned "60°C, 80%RH" is measured in accordance with JIS-P8111 (1998).

(Freeness of dissociated pulp)

The liner for corrugated paperboard preferably dissociates the liner for corrugated paperboard by a pulp dissociation method according to JIS-P8220-1 (2012) to become a dissociated pulp, and is in accordance with JIS-P8121-2 (2012) The Canadian Standard Freeness Test Method measured the dissociated pulp freeness after dissociation (Canadian Standard Freeness: CSF) of 420 ml or more and 460 ml or less. When the lower limit of the freeness of the dissociated pulp of the corrugated board lining is less than 420 ml, the burst resistance index in a high temperature and high humidity environment may decrease. In addition, if the upper limit of the freeness of the dissociated pulp exceeds 460 ml, there is a possibility that productivity decreases due to a decrease in papermaking properties and a carton molding suitability decreases.

(Canada standard freeness of each layer)

The Canadian standard freeness of the surface layer of the corrugated cardboard lining is preferably 480 ml or more and 600 ml or less. The Canadian standard freeness of the lower surface layer is preferably 400 ml or more and 510 ml or less. The Canadian standard freeness of the back layer is preferably 375 ml or more and 415 ml or less. By setting the freeness of the corrugated cardboard liner within the above range, it is possible to have excellent impact resistance even in a high temperature and humidity environment, and it is possible to further improve the impact resistance during transportation and in a high temperature and humidity environment. In addition, from the viewpoint of improving the suitability of carton molding, it is more preferable to obtain an inner liner for corrugated board that has a high burst resistance index and excellent impact resistance even in a high temperature and high humidity environment. The Canadian standard freeness has a relationship of surface layer>surface lower layer>back layer, and the Canadian standard freeness of each layer is adjusted.

＜Manufacturing method of lining for corrugated board＞

The manufacturing method of this corrugated cardboard lining is a method of manufacturing a corrugated cardboard lining having at least a surface layer, a lower surface layer, and a back layer. The manufacturing method of the liner for corrugated cardboard includes a process of making paper using a paper machine to make raw pulp. In addition, it is preferable that the manufacturing method of this corrugated cardboard liner includes a step of beating so that the raw material pulp constituting each layer has a desired freeness.

[Beating process]

In the beating process, beating is performed so that the raw material pulp constituting each layer has a desired freeness. The raw material pulp contains softwood kraft pulp, corrugated paper waste paper pulp, magazine waste paper pulp or a combination thereof. First, the pulp fibers are dispersed in water to obtain a slurry, and if necessary, additives corresponding to each paper layer are added to the slurry and mixed to prepare a paper stock for each paper layer.

[Papermaking process]

Next, using these raw material slurries, papermaking is performed to make the surface layer, the lower surface layer, and the back layer in multiple layers using a paper machine in the neutral region so that the pH of the corrugated cardboard lining becomes 6 or more and 8 or less. In the papermaking process, the papermaking machine is used to make paper from the pulp raw material ejected onto the traveling net to make paper from the raw pulp. The paper machine is not particularly limited, and well-known paper machines can be used. For example, paper machines such as Fourdrinier paper machines, cylinder paper machines, hybrid formers, and sandwich formers can be used to make paper in three or more layers.

The ratio J/W of the ejection speed J of the pulp raw material to the traveling speed W of the web in the papermaking process of the surface layer and the back layer is larger than J/W of the lower surface layer. By making the J/W of the surface layer and the back layer larger than the J/W of the lower surface layer, a good fiber orientation ratio can be obtained. Here, the fiber orientation ratio is a scale indicating the degree of orientation (arrangement) of fibers. It is along the longitudinal direction (the pulp fiber on the papermaking machine) during the process of the pulp fiber flowing on the paper machine's wire, dewatering, and forming a paper layer. The direction of flow) arrangement tendency. The larger the value of the fiber orientation ratio, the stronger the degree of alignment. By using high-strength softwood kraft pulp for the surface layer, it is possible to increase the burst resistance index. However, by adjusting the J/W ratio of the surface layer, the subsurface layer and the back layer, that is, the fibers of the surface layer, the subsurface layer and the back layer Orientation becomes the above-mentioned relationship, and it is possible to further increase the burst resistance index in a high temperature and high humidity environment.

In addition, in order to improve printability after the papermaking process, a coating layer may be provided on the surface.

[Squeezing process]

Then, it is squeezed by a pressure roller to remove water.

[Drying process]

Next, it is dried using a dryer.

After drying, the surface strength can be improved by performing a smoothing treatment. Preferably, for example, the corrugated cardboard liner is pressurized between pressurized paper shafts to perform smoothing treatment. There are no particular limitations on the various finishing devices used to implement the smoothing treatment. For example, the paper can be passed through a mechanical calender and/or a super calender, a gloss calender, and a soft calender before the paper roll. Machine to implement product finishing.

Finally, it is wound on a paper shaft to obtain a corrugated cardboard lining.

<Other embodiments>

The present invention is not limited to the above-mentioned embodiments, and can be implemented in various modifications and improvements other than the above-mentioned modes.

For example, the liner for corrugated cardboard may be provided with a single or a plurality of intermediate layers between the lower surface layer and the back layer.

[Example]

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the following examples.

The measurement methods of the physical property values of the Examples and Comparative Examples are as follows.

[Quantitative (g/m ² )]

The measurement was performed in accordance with "Paper and Board Paper-Quantitative Measurement Method" described in JIS-P8142 (1998).

[Paper thickness (μm)]

The measurement was carried out in accordance with "Paper and cardboard-Test methods for thickness and density" described in JIS-P8118 (2014).

[Density (g/cm ³ )]

The measurement was carried out in accordance with "Paper and cardboard-Test methods for thickness and density" described in JIS-P8118 (2014).

[Freedom (ml)]

The obtained corrugated board liner was dissociated by the pulp dissociation method according to JIS-P8220-1 (2012) to make it into dissociated pulp, and the Canadian standard freeness test method according to JIS-P8121-2 (2012) The dissociated pulp was measured.

[Breaking Index]

It was placed in a constant temperature and high humidity environment with a high temperature and humidity of 60°C and a humidity of 80% for 6 hours. After a predetermined period of time, it was taken out and measured in accordance with JIS-P8131 (2009).

[Example 1]

The raw materials listed in the table were added to the liquid slurry.

(additive)

(1) Rosin sizing agent

"NS-77P" special rosin sizing agent of Harima Chemical Co., Ltd. (solid content 50%)

(2) Acrylic amide-based paper strength enhancer

"Paper Strength RB-520" of Harima Chemical Co., Ltd.: Biionic polypropylene amide (solid content 20%)

[Example 2 to Example 7 and Comparative Examples 1 to 5]

Except that the types of raw materials, addition amounts and physical properties are shown in Tables 1 to 4, the same implementation as in Example 1 was carried out to obtain Examples 2 to 6, Comparative Examples 1 to 5 and the reference corrugated board lining . In addition, "one" in Table 1 and Table 2 below indicates that the component is not used. In addition, Examples 2 to 6 include a second back surface layer.

[Table 1] Number of layers Surface layer Property value Raw Pulp Papermaking process additive Quantitative The total quantitative proportion relative to the Paper thickness density Freeness NUKP Corrugated Paper Pulp J/W ratio Sizing agent Paper Strength Enhancer g/m ² % μm g/cm ³ ml % % % kg/ pulp t kg/ pulp t Example 1 3 40.0 31 55 0.727 580 100.0 0.0 90.0 3.65 0.8 Example 2 3 50.0 twenty one 60 0.833 580 100.0 0.0 93.0 3.65 0.8 Example 3 3 45.0 twenty four 53 0.849 480 80.0 20.0 97.0 3.65 0.8 Example 4 4 46.0 twenty three 56 0.821 560 100.0 0.0 93.5 3.65 0.8 Example 5 4 44.8 28 56 0.800 560 100.0 0.0 96.0 3.65 0.8 Example 6 4 46.0 20 58 0.793 560 100.0 0.0 96.0 3.65 0.8 Example 7 3 40.0 31 55 0.727 580 100.0 0.0 90.0 3.65 0.8 Comparative example 1 3 40.0 31 50 0.800 470 70.0 30.0 90.0 3.65 0.8 Comparative example 2 3 40.0 31 50 0.800 580 100.0 0.0 90.0 3.65 0.8 Comparative example 3 3 40.0 31 50 0.800 580 100.0 0.0 90.0 3.65 0.8 Comparative example 4 3 40.0 31 50 0.727 580 100.0 0.0 90.0 3.65 0.8 Comparative example 5 3 40.0 31 50 0.727 580 100.0 0.0 90.0 3.65 0.8

[Table 2] Number of layers Subsurface Property value Raw Pulp Papermaking process additive Quantitative Paper thickness density Freeness NUKP Corrugated Paper Pulp J/W ratio Sizing agent Paper Strength Enhancer g/m ² μm g/cm ³ ml % % % kg/ pulp t kg/ pulp t Example 1 3 60.0 85 0.706 400 25.0 75.0 87.0 3.00 7.0 Example 2 3 80.0 160 0.500 440 35.0 65.0 90.0 3.00 7.0 Example 3 3 70.0 123 0.569 420 30.0 70.0 95.0 3.00 7.0 Example 4 4 40.0 49 0.816 507 32.5 67.5 89.5 3.00 7.0 Example 5 4 40.0 50 0.800 420 30.0 70.0 95.0 3.00 7.0 Example 6 4 39.0 49 0.796 420 30.0 70.0 95.0 3.00 7.0 Example 7 3 60.0 85 0.706 400 35.0 70.0 87.0 3.00 7.0 Comparative example 1 3 60.0 85 0.706 400 25.0 75.0 87.0 3.00 7.0 Comparative example 2 3 60.0 80 0.750 380 20.0 80.0 87.0 3.00 7.0 Comparative example 3 3 60.0 80 0.750 380 20.0 80.0 87.0 3.00 7.0 Comparative example 4 3 60.0 85 0.706 400 25.0 75.0 87.0 3.00 7.0 Comparative example 5 3 60.0 85 0.706 400 25.0 75.0 87.0 3.00 7.0

[table 3] Number of layers Second back layer Property value Raw Pulp Papermaking process additive Quantitative Paper thickness density Freeness NUKP Corrugated Paper Pulp Magazine waste paper pulp J/W ratio Sizing agent Paper Strength Enhancer g/m ² μm g/cm ³ ml % % % % kg/ pulp t kg/ pulp t Example 1 3 One One One One One One One One One One Example 2 3 One One One One One One One One One One Example 3 3 One One One One One One One One One One Example 4 4 40.0 49 0.816 400 0.0 60.0 30.0 92.5 3.00 7.0 Example 5 4 40.0 50 0.800 420 10.0 50.0 40.0 92.5 3.00 7.0 Example 6 4 39.0 49 0.796 440 20.0 10.0 70.0 92.5 3.00 7.0 Example 7 3 One One One One One One One One One One Comparative example 1 3 One One One One One One One One One One Comparative example 2 3 One One One One One One One One One One Comparative example 3 3 One One One One One One One One One One Comparative example 4 3 One One One One One One One One One One Comparative example 5 3 One One One One One One One One One One

[Table 4] Number of layers Back layer Property value Raw Pulp Papermaking process additive Quantitative Paper thickness density Freeness NUKP Corrugated Paper Pulp Magazine waste paper pulp J/W ratio Sizing agent Paper Strength Enhancer g/m ² μm g/cm ³ ml % % % % kg/ pulp t kg/ pulp t Example 1 3 30.0 40 0.750 375 0.0 30.0 70.0 88.0 2.50 8.0 Example 2 3 110.0 140 0.786 405 0.0 70.0 30.0 97.0 2.50 6.0 Example 3 3 70.0 90 0.778 395 0.0 50.0 50.0 96.0 2.50 7.0 Example 4 4 74.0 91 0.813 393 0.0 45.0 55.0 93.5 2.90 7.0 Example 5 4 35.2 44 0.800 380 0.0 40.0 60.0 96.0 2.90 7.0 Example 6 4 106.0 133 0.797 415 10.0 30.0 60.0 96.0 2.90 7.0 Example 7 3 30.0 40 0.750 375 30.0 40.0 30.0 88.0 2.50 8.0 Comparative example 1 3 30.0 40 0.750 375 0.0 30.0 70.0 88.0 2.50 8.0 Comparative example 2 3 30.0 40 0.750 375 0.0 30.0 70.0 88.0 2.50 8.0 Comparative example 3 3 30.0 35 0.857 355 0.0 20.0 70.0 88.0 2.50 8.0 Comparative example 4 3 30.0 40 0.750 375 0.0 30.0 70.0 88.0 0.00 8.0 Comparative example 5 3 30.0 40 0.750 375 50.0 25.0 25.0 88.0 2.50 8.0

[Evaluation] The following method evaluated each obtained lining for corrugated cardboard. The evaluation results are shown in Table 5. (1) Quantitative: Measured in accordance with JIS P 8124 (1998). (2) Paper thickness: Measured in accordance with JIS P 8118 (1998). (3) Density: According to JIS P 8118 (1998), it is calculated from basis weight and paper thickness. (4) Freeness after dissociation: After dissociating the corrugated cardboard liner in accordance with JIS P 8220 (1998), it was measured in accordance with the "Pulp Freeness Test Method" described in JIS P 8121 (1995). (5) Cobb value It was measured in accordance with JIS-P8140 (1998). In addition, the Cobb value in the present invention is a value measured by contacting water with the surface layer or the back surface layer on the side where the foil press printing is provided for 2 minutes. (6) Carton forming adaptability The carton moldability of the corrugated cardboard liner obtained in the examples and comparative examples was evaluated. In addition, the carton moldability in the following evaluation refers to the ease of bending at the time of carton molding and the absence of cracks in the bent portion. ◎: The carton formability is very good, and there is no practical problem at all. ○: The carton formability is good, and there is no practical problem. △: The carton formability is slightly inferior, and there is a practical problem. ×: The carton formability is extremely poor, and it is very problematic in practice. (7) Bursting resistance and bursting index After measuring the burst resistance in an atmosphere of 60° C. and 80% RH in accordance with JIS-P8131 (2009), the burst resistance was divided by the quantitative value to obtain the burst resistance index. (8) Impact resistance under high temperature and humidity environment Corrugated cardboard boxes were manufactured using the corrugated cardboard linings obtained in the Examples and Comparative Examples. The corrugated cardboard boxes were transported in the container at 60°C and 80% RH, and the corrugated cardboard boxes were visually judged. . ◎: No deformation or holes were found in the corrugated box after transportation, and there is no practical problem at all. ○: Although the corrugated box after shipping was found to be deformed and only holes in the surface paper, the contents were not damaged. Although the texture was impaired, there was no practical problem. △: The corrugated cardboard box after transportation is found to be deformed, and holes that do not reach the backing paper are found, and the possibility of damage to the contents is high, and there is a practical problem. ×: Deformed and complete holes were found in the corrugated box after shipping, and the possibility of damage to the contents is very high, which is a big practical problem.

[table 5] Evaluation Quantitative Paper thickness density Freeness after dissociation Cobb value Carton forming adaptability Bursting resistance under high temperature and humidity Bursting index under high temperature and humidity Impact resistance under high temperature and humidity Surface layer Back layer g/m ² μm g/cm ³ ml g/m ² g/m ² One kPa kPa ・ m ² /g One Example 1 130.0 180 0.722 420 30 25 ◎ 468.0 3.60 ○ Example 2 240.0 360 0.667 460 50 45 ○ 972.0 4.05 ◎ Example 3 185.0 266 0.695 440 40 35 ◎ 703.0 3.80 ◎ Example 4 200.0 245 0.816 460 12 10 ◎ 840.0 4.20 ○ Example 5 160.0 200 0.800 440 15 20 ◎ 600.0 3.75 ○ Example 6 230.0 289 0.796 440 20 25 ○ 920.0 4.00 ◎ Example 7 130.0 180 0.722 420 28 25 ◎ 520.0 4.40 ◎ Comparative example 1 130.0 175 0.743 418 55 25 ◎ 429.0 3.30 × Comparative example 2 130.0 170 0.765 409 60 25 △ 442.0 3.40 △ Comparative example 3 130.0 165 0.788 395 60 35 △ 416.0 3.20 × Comparative example 4 130.0 180 0.722 420 30 160 ◎ 435.5 3.35 × Comparative example 5 130.0 180 0.722 420 30 25 △ 520.0 4.40 ◎

As shown in Table 5 above, the content of softwood kraft pulp in the surface layer is 80% by mass or more, the content of softwood kraft pulp in the lower surface layer is 25% by mass or more and 35% by mass or less, and the content in the back layer The content of corrugated paper waste paper pulp is 30 mass% or more and 70 mass% or less, the magazine waste paper pulp content in the back layer is 30 mass% or more and 70 mass% or less, and the ratio of the basis weight of the surface layer to the total basis weight is 20% or more And in Examples 1 to 7, in which the burst resistance index in an atmosphere of 35% or less, 60°C and 80%RH is 3.45kPa·m ² /g or more, carton molding suitability and impact resistance under high temperature and humidity environment Excellent performance.

On the other hand, the content of softwood kraft pulp in the surface layer is less than 80% by mass and the burst resistance index is less than 3.45kPa·m ² /g in Comparative Example 1; the content of softwood kraft pulp in the lower surface layer is less than 25% by mass %, the content of corrugated paper waste paper pulp in the back layer is less than 30% by mass and the burst resistance index is less than 3.45kPa·m ² /g in Comparative Example 2; the content of softwood kraft pulp in the lower surface layer is less than 25% by mass and is resistant burst index of less than 3.45kPa · m ² / g in Comparative Example 3; burst index of less than 3.45kPa · m ² / g in Comparative Example 4; and Journal of content and content in the back layer of corrugated waste paper pulp waste paper pulp is less than 30 mass In Comparative Example 5 of %, the carton molding adaptability and impact resistance under high temperature and humidity environment are not good.

Industrial applicability

The liner for corrugated cardboard of the present invention is suitably used as an inner liner for corrugated cardboard used for packaging containers for packaging, packaging bags, and containers for storing solids. In particular, it is suitable for use as corrugated cardboard for packaging containers for packaging in Southeast Asia, and can also be used as industrial paper in various fields such as the circulation field in a high-temperature and high-humidity environment.

Although the present invention is disclosed in the foregoing embodiments, it is not intended to limit the present invention. All changes and modifications made without departing from the spirit and scope of the present invention fall within the scope of patent protection of the present invention. For the scope of protection defined by the present invention, please refer to the attached patent scope.

no

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Claims (6)

A corrugated cardboard lining, characterized in that the corrugated cardboard lining has at least a surface layer, a lower surface layer and a back layer, the surface layer contains softwood kraft pulp, and the softwood kraft in the surface layer The content of the pulp is 80% by mass or more, the lower surface layer contains the softwood kraft pulp and corrugated waste paper pulp, and the content of the softwood kraft pulp in the lower surface layer is 25% by mass or more and 35% by mass or less, The back layer contains the corrugated paper waste paper pulp and magazine waste paper pulp, and the content of the corrugated paper waste paper pulp in the back layer is 30% by mass to 70% by mass, and the magazine waste paper pulp in the back layer The content of the surface layer is 30% by mass or more and 70% by mass or less, the ratio of the quantitative value of the surface layer to the total quantitative value is 20% or more and 35% or less, and the burst resistance index under an atmosphere of 60°C and 80%RH is 3.45 kPa·m ² /g or more. The corrugated board lining according to claim 1, wherein the surface layer and the back layer contain a sizing agent, and the Cobb value of the surface layer and the back layer is 2 minutes. 10 g/m ² or more and 50 g/m ² or less. The corrugated board lining according to claim 1, wherein the surface layer and the lower surface layer contain a paper strength enhancer, and the addition amount of the paper strength enhancer in the lower surface layer is greater than that of the surface layer. The added amount of the paper strength enhancer of the layer is large. The lining for corrugated cardboard according to claim 1, wherein the density is 0.65 g/cm3 or more and 0.85 g/cm3 or less. The corrugated board lining according to claim 1, wherein the freeness of the dissociated pulp dissociated in accordance with JIS-P8220 (1998) is 420 ml or more and 460 ml or less. A method for manufacturing an inner liner for corrugated cardboard, characterized in that the inner liner for corrugated cardboard has at least a surface layer, a lower surface layer, and a back layer, and the method for manufacturing the inner liner for corrugated cardboard includes using a paper machine to process raw pulp In the papermaking process of papermaking, the papermaking machine performs papermaking on the pulp raw material ejected onto the traveling net, the raw material pulp contains softwood kraft pulp, corrugated paper waste paper pulp, magazine waste paper pulp or a combination thereof, the surface layer and the The ratio J/W of the ejection speed J of the pulp raw material to the traveling speed W of the wire in the papermaking process of the back layer is larger than J/W of the lower surface layer.