JP2013002009A - Liner for corrugated board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liner for a corrugated board, which suitably prevents a flaw and a pinhole of a packaging bag of a product caused by contact between an inner face of a corrugated board case and the product, and also suitably suppresses paper powders produced from the inner face of the corrugated board case.SOLUTION: The liner for the corrugated board has a surface layer formed by applying a solution containing a synthetic resin and a lubricant agent on at least one face of a base paper. The synthetic resin contains a styrene-acrylic resin, and the lubricant agent is at least one substance selected from wax, a fluorine-based water repellent and a silicone-based water repellant.

Description

  The present invention relates to a liner for cardboard, and in particular, the inner surface of a cardboard case and a product (including a packaging material for packaging the product) contained in the cardboard case come into contact with each other when the cardboard case is transported. The inner surface of the corrugated cardboard case prevents damage to the product packaging bag such as pinholes due to contact with the product, and from the inner surface of the corrugated cardboard case due to contact between the inner surface of the cardboard case and the product contained in the corrugated cardboard case. The present invention relates to a corrugated liner used on the inner surface of a corrugated cardboard case that is optimal for suppressing the generation of paper dust.

  When products are put in a cardboard case and transported, the inner surface of the cardboard case and the product contained in the cardboard case rub against each other, resulting in damage to the product or damage to the product packaging bag such as pinholes. Paper dust may be generated from the inner surface of the cardboard case by contact between the inner surface and the product contained in the cardboard case. Measures to prevent damage to the product include UV varnishing and embossing on the product surface, packaging the product with shrink and laminate, and placing cushioning materials such as air caps and mirror mats. Is adopted.

  On the cardboard case side, attempts have been made to laminate the inner surface of the cardboard case that comes into contact with the product, or to use a highly smooth coated ball liner on the inner surface of the cardboard case.

  Patent Document 1 discloses a technique for making pinholes less likely to occur in a sealed packaging bag enclosed by applying an acrylic resin to the inner surface of the cardboard case. However, the acrylic resin is generally a hard resin, and this acrylic resin The friction coefficient with the contained product alone becomes high, and the product is abraded and scratched due to impact during transportation. For example, if the product is subjected to a large physical impact, the product will move rapidly in the cardboard case. There is a problem that the product is easily damaged when it collides with the inner surface of the cardboard case. In addition, there is a problem that paper dust is generated on the inner surface of the cardboard case due to contact with the product.

  In Patent Literature 2, the object is a paper curing sheet, but the friction coefficient of the front and back surfaces of the curing sheet is set to 0.18 or more, and further, flute processing causes damage or dirt to building materials, building parts, or materials. A technique for preventing this is disclosed.

  However, if the coefficient of friction on the inner surface of the cardboard case is too large, the coefficient of static friction between the inner surface of the cardboard case and the product will be high, so there is a problem that the inner surface of the cardboard case or the contained product is likely to be damaged. It is not enough to specify the lower limit of the coefficient, and if the dynamic friction coefficient is too large, if a large impact is applied during transportation, the product will move suddenly and collide with the inner surface of the cardboard case. There is a problem that pinholes occur in the product packaging bag.

JP-A-8-91359 JP 2000-273799 A

  The present invention prevents damage to the product caused by contact between the inner surface of the cardboard case and the product contained in the cardboard case during transportation or damage to the product packaging bag, such as pinholes, and the inner surface of the cardboard case. An object of the present invention is to provide a corrugated liner used on the inner surface of a corrugated cardboard case, which is optimal for suppressing the generation of paper dust from the corrugated board.

The liner for cardboard according to the present invention is
A liner for cardboard having a surface layer provided by printing a solution containing a synthetic resin and a lubricant on at least one side of a base paper,
The synthetic resin is a mixed resin composed of a styrene resin and an acrylic resin,
The lubricant is at least one selected from waxes, fluorine water repellents, and silicone water repellents.

  By having such a configuration, the present invention prevents damage to the product and damage to the product packaging bag, such as damage to the product packaging bag, caused by contact between the inner surface of the cardboard case and the product contained in the cardboard case. Thus, it is possible to provide a cardboard liner that is optimal for suppressing the generation of paper dust from the inner surface of the cardboard case.

The lubricant is contained in the solution in an amount of 0.1 to 2.0% by mass,
It is appropriate that the dynamic friction coefficient specified in JIS P 8147 “Testing method for friction coefficient of paper and paperboard” on the surface of the cardboard liner provided with the above surface layer is 0.10 to 0.30. It is preferable in order to obtain an appropriate cushioning effect when receiving a good product and receiving an impact.

  By having such a configuration, the present invention is less likely to cause uneven coating when the solution is applied to the surface of the base paper, and pinholes are less likely to occur in the product packaging bag. Further, the surface of the obtained corrugated cardboard sheet has an appropriate coefficient of dynamic friction, the cargo in the corrugated cardboard is kept stable, and even when the corrugated cardboard sheets before box making are stacked, the collapse of the cargo is difficult to occur. . Furthermore, the good bonding property at the time of assembling the cardboard can be maintained.

The surface layer is provided on at least one surface of the base paper by providing at least one layer so that the solution is 0.5 to 3.5 g / m ² per side,
It is preferable that the static friction coefficient defined by JIS P 8147 “Testing method for friction coefficient of paper and paperboard” on the surface of the corrugated board liner provided with the above surface layer is 0.10 to 0.30.

  By having such a configuration, the present invention makes it possible to maintain a desired coefficient of friction while maintaining the film property of the solution containing the synthetic resin and the lubricant in a liner in which used paper is frequently used. When applied to the surface of the base paper, pinholes are unlikely to occur in the product packaging bag. In addition, by obtaining a surface layer with a certain thickness, it is possible to improve the roughness of the liner and prevent problems such as damage to the product and pinholes in, for example, packaging bags and packaging members of vacuum packaged products. can do. Moreover, generation | occurrence | production of paper dust can be prevented and the favorable bonding property at the time of the assembly of a corrugated cardboard can be maintained. Further, in the present invention, as described above, since the purpose is to prevent damage to the product packaging bag characterized by high sealing properties such as damage to the product and vacuum packing, for example, oil-resistant paper Therefore, it is not necessary to apply a large amount of the solution to the surface of the base paper. In other words, there is a conventional technique for applying a solution containing a synthetic resin to the surface of a base paper in the field of oil-resistant paper or the like. In such a technique, a large amount of solution must be applied for the purpose of imparting oil resistance. On the other hand, in the present invention, as a result of earnest examination focusing on a new problem of preventing damage to the product and damage such as pinholes in the product packaging, a solution containing a specific synthetic resin and lubricant is obtained. It has the greatest feature in that it has been found that a sufficient effect can be obtained by coating with a small coating amount as described above.

  The Beck smoothness prescribed in JIS P 8119 “Smoothness test method using paper and paperboard Beck smoothness tester” on the surface of the corrugated board liner provided with the surface layer is 9.0 to 20.0 seconds. Is preferred.

  By having such a configuration, the present invention can remarkably prevent damage in “surface” contact in consideration of appropriate flatness between the inner surface of the cardboard case and the product contained in the cardboard case.

  Use soft backing in JIS P 8151 "Paper and paperboard-Surface roughness and smoothness test method (air leak method)-Print surf tester method" on the surface provided with the above surface layer of the above cardboard liner The print surf surface roughness measured by pressurizing to 1 MPa is preferably 7.0 μm to 10.0 μm.

  By having such a configuration, the present invention relieves shock contact between the inner surface of the cardboard case and the product even if an excessive impact occurs in the product enclosed in the cardboard case, and significantly damages the product. Can be prevented. In particular, when the Beck smoothness is 9.0 to 20.0 seconds and the print / surf surface roughness is in the range of 7.0 μm to 10.0 μm, the product is damaged and pinned on the product packaging bag. It has the effect of advantageously preventing damage to holes and the like and generation of paper dust from the inner surface of the cardboard case.

  According to the present invention, damage to a product (product packaging material) caused by contact between the inner surface of the cardboard case and the product and damage to a product packaging bag such as pinholes can be prevented. A liner for corrugated board that is optimal for suppressing the generation of paper dust can be provided.

The liner for cardboard according to the present invention is
A liner for corrugated board having a surface layer provided by applying a solution containing a synthetic resin and a lubricant on at least one side of a base paper,
The synthetic resin includes a styrene-acrylic resin,
The lubricant is at least one selected from waxes, fluorine water repellents, and silicone water repellents.

<About the base paper>
The base paper will be described. The base paper used in the present invention is used as a base paper to which a solution containing a synthetic resin and a lubricant is applied when producing the cardboard liner of the present invention. As the base paper, a multi-layer or single-layer liner or kraft paper satisfying LA class or LB class conforming to JIS P 3902 can be suitably used.

  As the raw material pulp used for the base paper for the cardboard liner of the present invention, various types can be used. For example, chemical pulp such as kraft pulp (KP), sulfite pulp (SP), soda pulp (AP), Semi-chemical pulp such as semi-chemical pulp (SCP), Chemi-Grandwood pulp (CGP), mechanical pulp such as groundwood pulp (GP), thermomechanical pulp (TMP, CTMP, BCTMP), refiner Grandwood pulp (RGP) Is possible.

  Other pulps include non-wood fiber pulp made from cotton linter, cocoon, cocoon, hemp, kenaf and the like, and deinked pulp made from waste paper. These pulps may be used alone or in combination of two or more. However, some tree species have a high resin content, and particularly when used as liner base paper, the surface of the glass plate may be contaminated. Therefore, it is preferable to select a tree species with as little resin content as possible. For example, the pulp which increased the purity of (alpha) cellulose by the cotton linter and the alkali treatment, the pulp etc. which gave the enzyme process by enzymes, such as a xylanase, etc. are mentioned.

  These raw material pulps are preferable because the pulp fiber bonding force is strengthened and the amount of dust generation is reduced by beating. Those which have been beaten in a viscous manner are preferred over free beating. The freeness of the pulp is preferably 600 ml or less in Canadian modified freeness (0.3 g method). In performing beating, beating conditions such as the type of beating apparatus, pulp concentration, and charging speed are not particularly limited, and each condition may be set so as to be within the above-described freeness range.

  As the internal and external additive chemicals used for making the base paper of the cardboard liner of the present invention, known chemicals can be used as needed.

  For example, sizing agents such as rosin, styrene / maleic acid resin, alkenyl succinic anhydride, alkyl ketene dimer, various paper strength enhancers, drainage retention improvers, water resistant agents such as polyamide polyamine epichlorohydrin, hygroscopic agents, flexible Agents, antistatic agents, antifoaming agents, slime control agents, fillers such as talc, dyes and the like can be used.

  In addition to the above chemicals, there are polyvinyl alcohol, polyacrylamide, starch and the like. Among them, high saponification degree PVA, low saponification degree PVA, modified PVA, modified polyacrylamide, raw starch, oxidized starch, modified It is also possible to apply or impregnate an aqueous solution of starch or the like on the surface of the base paper as necessary.

In particular, in the liner for corrugated board in which damage such as scratches and paper dust do not occur in the present invention, it is preferable to use paper having a dense surface, high smoothness, high cushioning properties and a desired friction coefficient. As a more preferable structure satisfying such properties, for example, the cobb water absorption on the inner surface of the corrugated cardboard case specified by JIS P 8140 “Paper and paperboard—Water absorption test method—Cobb method” is 20 to 80 g / m ² · 2 minutes. The cobb water absorption on the side in contact with the flute comprising the core that forms the corrugated cardboard sheet is 100 to 190 g / m ² · 2 minutes, so that it is suitable for molding into a corrugated cardboard box and the synthetic resin and lubrication according to the present invention. The solution containing the agent is suitable for maintaining a desired coefficient of friction, flatness, and cushioning properties in contact between the appropriate coating on the surface of the cardboard liner and the product contained in the cardboard case.

Further, the basis weight measured in accordance with JIS P 8124 “Paper and paperboard—basis weight measurement method” is 100 to 350 g / m ² , so that the present invention can be applied to the present invention by a printing machine after forming a cardboard box or processing a cardboard sheet. It is preferable from the viewpoint of workability to provide a solution containing such a synthetic resin and a lubricant. For example, JEK liners 170 to 280 g / m ² manufactured by Daio Paper Co., Ltd. can be suitably used.

  More specifically, when the Cobb water absorption is out of the above range, when the solution described later is applied, the applied solution excessively penetrates the inside of the base paper, and the surface sufficient for the surface of the base paper. There is a tendency that the layer cannot be formed. In addition, when the Beck smoothness is outside the above range, the contact between the inner surface of the cardboard case and the product contained in the cardboard case is changed from the “surface” to the “point”, and the product packaging bag is damaged at the contact portion. In addition, problems such as generation of paper dust from the inner surface of the corrugated cardboard case and damage to the contained product are likely to occur. In addition, foreign matter derived from raw material pulp cannot be covered with the surface layer (film) of the base paper, and scratches caused by waste paper-derived plastic, binding fibers, etc., especially when using a liner containing 50% or more of waste paper pulp There is a tendency that the effect of preventing entry is difficult to obtain.

  As will be described later, the present invention is characterized by the synthetic resin and the lubricant contained in the solution, and also by the surface properties of the surface layer obtained.

<About the solution>
The solution will be described. The solution used in the present invention includes a synthetic resin and a lubricant, the synthetic resin includes a styrene-acrylic resin, and the lubricant is selected from wax, a fluorine-based water repellent, and a silicone-based water repellent. It is characterized by being at least one kind.

  Examples of the styrene-acrylic resin include those obtained by polymerizing the following vinyl monomers.

  Examples of vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethyl. Styrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene Styrene or styrene derivatives such as: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , Lauryl methacrylate, methacrylate Methacrylic acid ester derivatives such as phenyl phosphate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, acrylic Acrylic acid ester derivatives such as n-octyl acid, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; olefins such as ethylene, propylene, and isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, fluorine Halogenated vinyls such as vinyl fluoride and vinylidene fluoride; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether Ters; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide; These vinyl monomers can be used alone or in combination of two or more.

  As a vinyl-type monomer for forming said styrene-acrylic-type resin, it is preferable to use what has an ionic dissociation group in combination. Examples of the vinyl monomer having an ionic dissociation group include a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of the monomer. Specifically, acrylic acid, Methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid Examples thereof include phosphooxyethyl methacrylate and 3-chloro-2-acid phosphooxypropyl methacrylate. In addition, as vinyl monomers for forming styrene-acrylic resins, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate are used. Polyfunctional vinyls such as acrylate, neopentyl glycol dimethacrylate, and neopentyl glycol diacrylate may be used, and the styrene-acrylic resin may be made of a vinyl polymer having a crosslinked structure.

  The synthetic resin used in the present invention can contain an appropriate amount of other resins in addition to the styrene-acrylic resin described above. As other resins, for example, styrene resin, acrylic resin, methacrylic resin, urethane resin, epoxy resin, vinyl ester resin, polyethylene resin, polypropylene resin, polyester resin, polyethylene terephthalate resin and the like can be used in combination.

  Although it does not specifically limit as a styrene resin, What contains 3-40 mass% of styrene components in resin can be illustrated. Among the components of the styrene resin, examples of components other than the styrene component include monofunctional unsaturated monomer components copolymerizable with styrene, other than the above-described styrene-acrylic resin. Examples of the monofunctional unsaturated monomer include acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and the like. Moreover, this copolymer may further contain a glutaric anhydride unit and a glutarimide unit. Furthermore, you may use what blended diene rubber, silicone rubber, etc. as a rubber-like polymer to the above-mentioned polymer and copolymer.

  Although it does not specifically limit as an acrylic resin, The thing containing 60-95 mass% of acrylic components can be illustrated, and in order to improve the dispersibility in a solution, it is emulsion polymerization of an unsaturated monomer. An acrylic resin in the form of an emulsion (acrylic emulsion) of the obtained resin particles is preferred. The acrylic emulsion can be obtained by a known emulsion polymerization method. For example, it can be obtained by emulsion polymerization of an unsaturated monomer (such as an unsaturated vinyl monomer) in water containing a polymerization initiator and a surfactant. Specific examples include acrylic resins such as VS-1028 manufactured by Seiko PMC.

  Examples of unsaturated monomers include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl cyanide compounds generally used in emulsion polymerization. Examples include monomers, halogenated monomers, olefin monomers, and diene monomers. Furthermore, specific examples include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate. Acrylic acid esters such as dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl Methacrylate, n-hexyl methacrylate, 2-ethyl Hexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, methacrylic esters such as phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, and vinyl esters such as vinyl acetate; vinyl such as acrylonitrile and methacrylonitrile Cyanides; halogenated monomers such as vinylidene chloride and vinyl chloride; simple aromatic vinyl such as styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene Olefins such as ethylene and propylene; dienes such as butadiene and chloroprene; vinyl ethers, vinyl ketones, vinyl pyrroles Vinyl monomers such as Don; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; acrylamides such as acrylamide, methacrylamide and N, N′-dimethylacrylamide; 2-hydroxy Examples include hydroxyl group-containing monomers such as ethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc., and these may be used alone or in combination of two or more to be used as a mixed resin. Can do.

  Further, as the resin particles of the emulsion resin, any of a single phase structure and a multiphase structure (core-shell type) can be used.

  The content of the styrene-acrylic resin in the solution is not particularly limited, but is highly compatible with the lubricant, and prevents damage to the product and pinholes in the product packaging bag, which are the problems of the present invention. At the same time, from the viewpoint of moderate film properties and flexibility to suppress the generation of paper dust from the inner surface of the cardboard case, it is preferably 3.0 to 40.0% by mass, and 5.0 to 30.0% by mass. More preferably. If it is less than 3.0% by mass, it will be difficult to control the sufficient film properties and the hardness of the acrylic resin, thereby preventing damage to the product and damage to the product packaging bag such as pinholes, and from the inner surface of the cardboard case. There is a tendency that paper dust tends to be generated. On the other hand, if it exceeds 40.0 mass%, the strength of the inner surface of the corrugated cardboard case will be reduced, and paper dust from the inner surface of the corrugated cardboard case will be easily generated due to contact with the product. There is a tendency to cause damage problems.

  As described above, in the present invention, the synthetic resin includes a styrene-acrylic resin and is used in combination with a lubricant. Thereby, for example, even when a large impact is applied during transportation, the product does not move suddenly, and it is possible to prevent damage to the product and occurrence of pinholes in the product packaging bag. For this reason, since the content of the lubricant described later can be minimized and the bonding property is not lowered, a cardboard liner capable of obtaining a high-strength cardboard case can be manufactured.

  The blending ratio of the styrene-acrylic resin and the lubricant is not particularly limited, but it prevents damage to the product, which is a problem of the present invention, and damage to the product packaging bag, such as pinholes, and from the inner surface of the cardboard case. From the viewpoint of securing appropriate film properties and flexibility to suppress the generation of paper dust, the styrene resin-acrylic resin is 95.0-99.9% by mass, and the lubricant is 0.1-5.0% by mass. It is preferable that 98.0 to 99.8% by mass, and the lubricant is more preferably 0.2 to 2.0% by mass.

  Next, the lubricant will be described. As the lubricant, at least one selected from waxes, fluorine-based water repellents, and silicone-based water repellents is preferably used, and the wax is not particularly limited, and conventionally used ones can be used. .

  For example, waxes such as natural wax and synthetic wax can be contained. Natural waxes include plant-based natural waxes such as candelilla wax, carnauba wax, rice wax, wood wax, and jojoba solid wax, animal-based natural waxes such as beeswax, lanolin, and whale wax, and minerals such as montan wax, ozokerite, and ceresin. And natural petroleum wax such as natural wax, paraffin wax, microcrystalline wax and petrolatum wax. Synthetic waxes include synthetic hydrocarbons such as Fischer-Tropsch wax and polyethylene wax, modified waxes such as montan wax derivatives, paraffin wax derivatives and microcrystalline wax derivatives, hydrogenated waxes such as hardened castor oil and hardened castor oil derivatives, 12 -Hydroxy stearic acid, stearic acid amide, phthalic anhydride imide and the like.

  Commercially available paraffin wax-based water repellents such as HA-541 manufactured by Arakawa Chemical Industry Co., Ltd., and pull knit 101Z manufactured by Shin Nakamura Chemical Co., Ltd., a fatty acid ester / paraffin wax system, can be obtained. .

  As the fluorine-based water repellent, there is a fluorine-based water / oil repellent containing a perfluoroalkyl acrylate copolymer. These are obtained as commercial products such as NK guard series (manufactured by Nikka Chemical Co., Ltd.), Asahi guard series (manufactured by Meisei Chemical Industry Co., Ltd.), and Dickguard series (manufactured by Dainippon Ink Co., Ltd.). be able to.

  Examples of the silicone water repellent include dimethyl silicone, amino-modified silicone, epoxy-modified silicone, carboxyl-modified silicone, and polyether-modified silicone.

  For example, it can be obtained as a commercial product such as SM7060 manufactured by Toray Dow Corning Silicone Co., Ltd., Polon-C, Polon-MWS, Polon-MR manufactured by Shin-Etsu Chemical Co., Ltd., TSW831 manufactured by Toshiba Silicone Co., Ltd. Can do. These lubricants can be used alone or in combination of two or more.

  The content of the lubricant in the solution is preferably 0.1 to 5.0% by mass, and more preferably 0.2 to 2.0% by mass. When the lubricant content is less than 0.1% by mass, uneven coating tends to occur when a surface layer (coating layer) is provided on the surface of the base paper by coating, and pinholes tend to occur in product packaging bags. There is. Further, since the dynamic friction coefficient on the surface of the surface layer (dynamic friction coefficient defined in JIS P 8147 “Testing method for friction coefficient of paper and paperboard”) easily exceeds 0.30, the product tends to be damaged. . On the other hand, when it exceeds 5.0% by mass, the coefficient of dynamic friction on the surface of the surface layer tends to be less than 0.10, and when cardboard sheets before box making are stacked, load collapse tends to occur and the handling tends to be hindered. There is. In addition, since the lubricant is easy to play the glue, the sticking property tends to deteriorate. In addition, as said dynamic friction coefficient, it is preferable that it is 0.10-0.30, and it is more preferable that it is 0.15-0.25. As described above, when the dynamic friction coefficient is less than 0.1, when the corrugated cardboard sheets before box making are stacked, load collapse tends to occur, and the handling tends to be hindered. On the other hand, when the coefficient of dynamic friction exceeds 0.3, the product that is the contents of the boxed cardboard tends to slip, and the product tends to be damaged.

<About application of solution>
The solution is applied to at least one side of the base paper, and a surface layer is provided on the surface of the base paper. As a method of applying the solution to the base paper, as a method of impregnating the base paper into the solution, or as a method of applying the solution to the base paper, size press coat, blade coat, bar coat, air knife coat, curtain coat, roll coat, Although general means such as gravure coating is used, according to the knowledge of the present inventor, the method of applying by printing such as flexographic printing is uniform without solution loss by printing on the surface of the cardboard liner. In addition to being excellent in forming a coating film, it is possible to apply the minimum necessary amount according to the form of various cardboard boxes, and it is preferable that it can be easily applied to a predetermined site or in multiple layers.

  In addition, when multiple layers are applied more than once, the first layer of synthetic resin plays a role in sealing, and almost all of the synthetic resin and lubricant applied after the second time contribute to film formation. However, the surface layer (coating layer) can be applied using a printing machine capable of multi-layer coating. It is preferable to form. In addition, when applying multilayer, the composition of the solution applied to the first layer and the second and subsequent layers may be changed or the same. According to the inventor's knowledge, by providing the predetermined amount in two or more layers rather than in one layer, the first coating layer exerts a function of suppressing the penetration of the coating liquid into the base paper. Creates a function to promote film formation of the solution when the solution after the layer is applied, can obtain a surface property suitable for preventing scratches without damaging the flexibility of the surface of the base paper, and laminates solutions of the same composition From the viewpoint of increasing the affinity between layers and maintaining the coating strength, it is preferable to apply a solution having the same composition in multiple layers. When applying the solution with a flexographic printing machine, the Zahn cup no. The viscosity of the solution is adjusted so that the value measured at 4 (25 ° C.) is 10 to 30 seconds, preferably 15 to 20 seconds. When the viscosity of the solution is less than 10 seconds, the penetration of the base paper into the surface tends to increase, and the surface film property tends to decrease. On the other hand, when the viscosity of the solution exceeds 30 seconds, it is difficult to uniformly supply the solution, and uneven coating tends to occur.

The applied amount of the solution is preferably 0.5 to 3.0 g / m ² , more preferably 1.0 to 2.5 g / m ^{2 in} terms of solid content per one side of the base paper. If the applied amount is less than 0.5 g / m ² , not only pinholes are likely to occur in the product packaging bag, but the coating layer is thin, so it is difficult to improve the roughness of the liner, and the product is likely to be damaged. Tends to be exposed to paper, and tends to reduce static wear resistance. In addition, since the static friction coefficient on the surface of the surface layer (dynamic friction coefficient specified in JIS P 8147 “Friction coefficient test method for paper and paperboard”) easily exceeds 0.30, the product tends to be damaged. . On the other hand, when it exceeds 3.0 g / m ² , the surface layer tends to be hardened by the solution, and the adhesiveness tends to be deteriorated by the lubricant contained in the solution. In particular, when a corrugated sheet is used as a partition pad (a partition plate stored in the corrugated sheet), it is necessary to provide the surface layer of the present invention on both sides of the sheet. The imparting surface tends to be damaged, and there is a tendency that a sufficient damage prevention effect cannot be obtained. In addition, the surface layer melts and adheres to the corrugator hot plate and may easily become a foreign substance, and the workability of sheet formation tends to be reduced. Furthermore, the static friction coefficient on the surface of the surface layer tends to be less than 0.10, and when the corrugated cardboard sheets before box making are stacked, load collapse tends to occur and the handling tends to be hindered. Furthermore, in the present invention, as described above, since the purpose is to prevent damage to the product and damage to the product packaging bag such as pinholes, a large amount of solution is applied as required for oil-resistant paper, for example. There is no need, and by setting the upper limit of the blending amount to 3.0 g / m ² , the above object can be sufficiently achieved. That is, when attention is paid to a new problem (new use) of preventing damage to the product and damage to the product packaging bag such as pinholes, a solution containing the above specific synthetic resin and lubricant is used. It has the greatest feature in that it has been found that a sufficient effect can be obtained by coating with a small coating amount as described above. In other words, the present invention proposes a cardboard liner obtained by applying a solution with a formulation particularly effective for new applications.

In the present invention, as described above, as the surface property of the base paper, the Cobb water absorption on the inner surface of the corrugated cardboard case defined by JIS P 8140 “Paper and paperboard—Water absorption test method—Cobb method” is 20 to 80 g / m ^2.・ It is 2 minutes, and it is one of the features that the Cobb water absorption on the side in contact with the flute formed of the core forming the corrugated cardboard sheet is 100 to 190 g / m ² · 2 minutes. This is because in the use of oil-resistant paper, it is not necessary to impart oil resistance to the surface of the base paper, and it is sufficient that the entire paper including the base paper has oil resistance. Cobb water absorption on the surface is not so important, but the present invention is not intended for oil resistance and focuses on a new problem of preventing damage to the product and damage to the product packaging bag such as pinholes. Since the solution applied on the surface needs to form a film, the water absorption on the surface of the base paper is an important feature.

After applying the solution to the surface of the base paper, it is heated and dried in a drying step to form a surface layer. The drying temperature in the drying step is preferably 100 to 120 ° C. When the drying temperature is less than 100 ° C., the affinity between the solution and the raw material pulp constituting the base paper is lowered, and it is necessary to increase the coating amount in order to secure a desired coefficient of friction. The coefficient of friction tends to be high. On the other hand, when the temperature exceeds 120 ° C., depending on the drying time, it is difficult to obtain a desired coating with excessive penetration of the synthetic resin or lubricant into the base paper by heating, and the flatness of the surface of the base paper tends to be lowered. .
In particular, drying exceeding 120 ° C. in the drying step facilitates the penetration of the lubricant, which is the constitution of the present invention, into the base paper, and makes it difficult to adjust the dynamic friction coefficient and the static friction coefficient to a desired range.

  The cardboard liner obtained as described above is bonded to the core with a corrugator to obtain a cardboard sheet. The temperature of the corrugator hot plate is preferably 150 to 180 ° C, and preferably adjusted so that the temperature of the paper surface is 80 to 130 ° C. It can be adjusted so that the surface layer melts and adheres and does not become foreign matter.

  The cardboard liner according to the present invention does not prevent the product from being damaged or the pinhole of the product packaging bag from being generated simply by increasing the coefficient of friction to prevent the product from slipping. In other words, if the coefficient of friction is too large, if a large impact is applied during transportation, the product will move suddenly and collide with the inner surface of the cardboard case, which may cause scratches on the inner surface of the product or box and pinholes on the product packaging bag. Therefore, the friction coefficient is adjusted to the above range by containing a lubricant so that the product does not move rapidly.

  In the cardboard liner according to the present invention provided with the above surface layer, the Beck smoothness defined by JIS P 8119 “Paper and paperboard—Smoothness test method using Beck smoothness tester” on the surface provided with the surface layer ( Contrast with Beck smoothness (B2) specified in JIS P-8119 “Paper and paperboard—Smoothness test method with Beck smoothness tester” of B1) is 9.0 to 20.0 The relationship between Beck smoothness (B1) and Beck smoothness (B2) is preferably (B1)> (B2). Thus, the present invention is characterized in that the value of Beck smoothness is improved before and after the surface layer is formed.

  Further, in the cardboard liner according to the present invention provided with the above surface layer, JIS P 8151 “paper and paperboard—surface roughness and smoothness test method (air leak method) —printing of the surface provided with the surface layer In the “surf tester method”, it is preferable that the print surf surface roughness measured by applying pressure to 1 MPa using a soft backing is 7.0 μm to 10.0 μm. When the print surf surface roughness is less than 7.0 μm, the effect of suppressing the generation of pinholes in the product packaging bag tends to be difficult to obtain. On the other hand, if it exceeds 10.0, the contact area between the inner surface of the corrugated cardboard case and the product becomes excessively large, and the corrugated cardboard is formed by contacting the inner surface of the corrugated cardboard case with the product in a “surface”. There is a tendency to promote the generation of paper dust from the inner surface of the case.

  The ratio of the Beck smoothness and the print surf surface roughness are set to satisfy a range of 7.0 μm to 10.0 μm with a Beck smoothness of 9.0 to 20.0 seconds and a print surf surface roughness of 7.0 μm to 10.0 μm. By producing a cardboard liner using the above-mentioned synthetic resin and lubricant so as to have a surface property in the range of the above, it is possible to suppress the occurrence of product damage and pinholes in product packaging bags, It is possible to provide an optimal corrugated board liner for suppressing the generation of paper dust from the inner surface of the case.

<About other additives>
Other additives include antifoaming agents, dissolution aids, penetration control agents, viscosity modifiers, pH adjusters, antioxidants, antifungal agents, for the purpose of ensuring friction resistance and leaving stability, etc. Various additives such as a corrosion inhibitor and a chelating agent for capturing metal ions that affect dispersion may be added.

  EXAMPLES Hereinafter, although this invention is further demonstrated using an Example, this invention is not limited by this.

The raw materials used are shown below.
(solution)
Styrene-acrylic resin (Johncrill 631, manufactured by BASF Japan Ltd.)
Acrylic resin (VS-1028, manufactured by Seiko PMC)
Lubricant (paraffinic wax, HA-541, manufactured by Arakawa Chemical Industries, Ltd.)
Lubricant (fluorinated water repellent, NK guard SR-200, manufactured by Nikka Chemical Co., Ltd.)
Lubricant (silicone water repellent, Polon-C, manufactured by Shin-Etsu Chemical Co., Ltd.)
(Base paper)
JEK liner 170 (basis weight: about 170, Cobb water absorption: 50 g / 2 minutes, Beck smoothness (B1): 11 seconds, manufactured by Daio Paper Co., Ltd.)
JEK liner 210 (basis weight: about 210, Cobb water absorption: 60 g / 2 minutes, Beck smoothness (B1): 12 seconds, manufactured by Daio Paper Co., Ltd.)
JEK liner 280 (basis weight: about 280, Cobb water absorption: 65 g / 2 minutes, Beck smoothness (B1): 14 seconds, manufactured by Daio Paper Co., Ltd.)
The Cobb water absorption is adjusted by adjusting the surface sizing agent at the time of making each JEK liner.

<Example 1>
On one side of a liner (trade name: JEK liner, manufactured by Daio Paper Co., Ltd.) having a basis weight of 170 g / m ² , VS-1028 made by Seiko PMC Co., Ltd. as an acrylic resin and BASF Japan Co., Ltd. made by a styrene-acrylic resin A solution obtained by mixing paraffin wax (HA-541 manufactured by Arakawa Chemical Industry Co., Ltd.) at a ratio shown in Table 1 with the use of Joncrill 631 as a lubricant was applied at 5 g / m ² as an absolutely dry solid content with a hand proofer. did. After application, it was put into a blower dryer adjusted to 130 ° C. and dried for 60 seconds. Zaan Cup No. The viscosity measured at 4 (25 ° C.) was 8 seconds to 35 seconds.

<Examples 2 to 21, Comparative Examples 1 to 8 and Reference Examples 1 to 2>
A cardboard liner was prepared in the same manner as in Example 1 except that the conditions described in Table 1 and Table 2 were changed. In Example 21, a styrene-maleic acid resin X-228 made by Seiko PMC was used instead of VS-1028 made by Seiko PMC. In addition, as a reference example, compared with the present invention, although it is inferior in cost and recyclability, it is used as an existing scratch prevention treatment, and a product in which paraffin wax is further applied on the laminate layer after lamination and lamination Contrast. “Lamination” includes polyolefin resins such as polyethylene resins and polypropylene resins, vinyl chloride resins, vinylidene chloride resins, halogen-containing resins such as fluororesins, polyester resins, polyvinyl alcohol (PVA) resins, Examples thereof include copolymer resins such as acrylic resins and acrylonitrile-butadiene copolymers, and polyethylene resins are preferred from the viewpoints of low cost, excellent water resistance and durability. This laminating process can be formed by laminating a molten resin on one side of the base paper to a thickness of 5 to 100 μm, preferably about 10 to 15 μm, using a T die or the like. In this comparative example, a polyethylene resin is used, and a resin melted on one side of the base paper is laminated with a thickness of 15 μm using a T die or the like. Then, 1.5 g / m @ 2 of paraffin was applied using a coating rod.

  The following tests were conducted on the cardboard liners obtained in the examples and comparative examples. The results are shown in Table 3 and Table 4.

The test method is shown below.
a) Friction coefficient The static friction coefficient and the dynamic friction coefficient specified in JIS P 8147 “Test method for friction coefficient of paper and paperboard” are measured. If the static friction coefficient and the dynamic friction coefficient are 0.10 to 0.30, the friction coefficient is excellent, and if it is 0.15 to 0.20, the friction coefficient is good. If it is less than 0.10, the friction coefficient is low and slipping tends to occur, which is not preferable, and if it exceeds 0.30, the friction coefficient is large and scratching is likely to occur.

b) Paper powder In accordance with JIS P 8136 “Testing method for resistance to abrasion resistance of paperboard”, the coated surfaces are brought into contact with each other and the number of times until paper dust is generated from the inner surface of the cardboard case is measured. The evaluation criteria are shown below.
A: No occurrence of paper dust was observed at 50,000 times.
○: The occurrence of paper dust was observed at the number of times of 10,000 to less than 50,000.
(Triangle | delta): Generation | occurrence | production of paper dust is recognized by frequency | count 1,000 or more and less than 10,000, and the minimum level which can be actually used.
X: The occurrence of paper dust was observed when the number of times was less than 1,000, and the paper was not practically usable.

c) A scratched JEK liner (basis weight: 210 g / m ² , manufactured by Daio Paper Co., Ltd.) was prepared with a test piece obtained by applying 5 g / m ² of water-based ink with a hand proofer. In accordance with the “Abrasion Strength Test Method”, the surface layer of the base paper and the test piece are brought into contact with each other, a load of 500 g is applied, and a 500 times wear resistance test is performed. The state of the test piece with scratches is visually evaluated as follows.
A: No scratch was observed.
○: Some scratches occurred.
(Triangle | delta): Although the crack generate | occur | produced somewhat, the lower limit level which can be actually used.
X: Many scratches occur, and a large amount of paper peeling is seen, so that it cannot be used in practice.

d) Occurrence of pinholes According to JIS P 8136 “Abrasion Resistance Test Method for Paperboard”, a stretched PP film (friction part side) having a thickness of 0.05 mm and the solution according to the present invention used on the inner surface of the cardboard case were applied. The coating surface of a JEK liner (basis weight: 210 g / m ² , manufactured by Daio Paper Co., Ltd.) is point-contacted with a contact area of 1.0 mm ² to measure the number of times the film is torn (until pinholes are generated).
A: Generation of pinholes is not observed after 10,000 times.
○: Generation of pinholes is observed at 1,000 times or more and less than 10,000 times.
(Triangle | delta): Generation | occurrence | production of a pinhole is recognized by the frequency | count 500 times or more-less than 1,000 times.
X: Generation of pinholes is observed in less than 500 times.

e) Sheet handling after bonding 100 cardboard sheets of 100 x 150 cm square are stacked and placed on a carriage, moved 5 meters at walking speed (about 4 km / h), and the cardboard sheet collapsed when stopped Visual evaluation is performed as follows.
A: There was no collapse of the cargo, and there was no displacement of the cardboard sheet.
○: Although there was no collapse of the cargo, the cardboard sheet was slightly displaced.
△: There is no load collapse, but there is some misalignment of the corrugated cardboard sheet, and the lower limit level that can be used practically.

f) Wear resistance strength In the scratch test, the state of the coated surface is evaluated as follows.
A: No transfer of black ink is observed, and no scratches are observed.
○: Transfer of black ink is not observed, but scratches are observed.
Δ: Transfer of black ink is recognized to some extent, but it is the lower limit level that can be used practically.
X: A large amount of black ink transfer was seen, and the actual use was impossible.

g) Adhesive paste suitability Using a corrugated liner as a surface layer and a back layer, using a core (120 g / m ² , manufactured by Daio Paper Co., Ltd.) and a corrugator machine (model number: Belton Press 60G, manufactured by Mitsubishi Heavy Industries, Ltd.) At a speed of 180 m / min, the surface having the coating layer is bonded so as to be the front side of the corrugated cardboard sheet (not to bond the coating layer to the core liner) to produce an A-stage corrugated cardboard sheet. The obtained corrugated cardboard sheet is used as a type A corrugated board at a processing speed of 200 sheets / min using a box making machine (Flexo Folder Gluer Summit 100 manufactured by Mitsubishi Heavy Industries, Ltd.) and glue (Sebian A56104 manufactured by Daicel Chemical Industries, Ltd.). The case is processed into a box, and after 1 minute, the pasting part (the joint part of the sheet) is peeled off by hand, and the paste applicability is evaluated as follows.
(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 where the paste pasting part did not peel (the corrugated cardboard sheet was destroyed) has 1/3 or less of the whole glue pasting area, and paste pasting is good.
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.

h) Beck smoothness Beck smoothness is measured according to JIS P-8119 “Paper and paperboard—Smoothness test method using Beck smoothness tester”.

i) Print Surf Surface Roughness JIS P 8151 “Paper and Paperboard—Surface Roughness and Smoothness Test Method (Air Leak Method) —Print Surf Surfing Tester Method” using a soft backing and pressurizing to 1 MPa Measure the surface roughness of the print surf. It is preferable that the surface roughness of the print surf is 7.0 μm to 10.0 μm, and if the surface roughness of the print surf is less than 7.0 μm, it prevents the product from being damaged and pinholes in the product packaging bag. There is a tendency that it is difficult to obtain the effect. On the other hand, when it exceeds 10.0 μm, there is a tendency that damage such as pinholes in the product packaging bag or paper dust from the inner surface of the cardboard case occurs.

j) Cobb water absorbency Measure the Cobb water absorbency at a measurement time of 2 minutes in accordance with JIS P 8140 “Paper and paperboard water absorbency test method Cobb method”.

  As for the corrugated cardboard sheet of each example, good results were obtained in the above evaluation items. That is, the corrugated cardboard sheet according to each example can solve the problems of the present invention.

  On the other hand, since none of the corrugated cardboard sheets of the comparative examples satisfy the configuration of the present invention, good results cannot be obtained in any of the evaluation items, and the problems of the present invention cannot always be solved. .

Claims (5)

A liner for cardboard having a surface layer provided by printing a solution containing a synthetic resin and a lubricant on at least one side of a base paper,
The synthetic resin includes a styrene-acrylic resin,
The liner for corrugated board, wherein the lubricant is at least one selected from wax, fluorine-based water repellent, and silicone-based water repellent. The lubricant is contained in the solution in an amount of 0.1 to 2.0% by mass,
The dynamic friction coefficient specified in JIS P 8147 “Friction coefficient test method for paper and paperboard” on the surface of the corrugated board liner provided with the surface layer is 0.10 to 0.30. The liner for cardboard as described. The surface layer is provided on at least one surface of a base paper by providing at least one layer so that the solution is 0.5 to 3.5 g / m ² per side,
2. The coefficient of static friction defined by JIS P 8147 “Friction coefficient test method for paper and paperboard” on the surface of the corrugated liner provided with the surface layer is 0.10 to 0.30. Or the liner for cardboards of 2.   The Beck smoothness defined by JIS P 8119 “Smoothness test method using Beck smoothness tester” on the surface of the corrugated board liner provided with the surface layer is 9.0 to 20.0. The cardboard liner according to any one of claims 1 to 3, wherein:   Use soft backing in JIS P 8151 "Paper and paperboard-Surface roughness and smoothness test method (air leak method)-Print surf tester method" on the surface of the cardboard liner provided with the surface layer The corrugated liner according to any one of claims 1 to 4, wherein the surface roughness of the print surf measured by pressurizing to 1 MPa is 7.0 µm to 10.0 µm.