JP2009235614A - Corrugating medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrugating medium for a high-quality corrugated board which is especially excellent in water resistance and strength and producible over a long time without stopping a paper machine immediately after the papermaking process, and suppresses the generation of insoluble waste stuff to prevent the accumulation of the stain in the process. <P>SOLUTION: The corrugating medium is formed of a raw pulp obtained from a defibrated pulp defibrated in conformity to JIS P 8220 by classifying or beating the pulp in a manner to attain a Canadian standard freeness of 180-350 ml in conformity to JIS P 8121, a functional treating agent at least containing a waterproofing agent is applied to at least one surface of the base paper during the drying step and before and after the drying step, and the corrugating medium has a Stoeckigt sizing degree of 0.001-0.05 sec/(g/m<SP>2</SP>) per unit basis weight in conformity to JIS P 8122 and a Dennison wax value of 7A or over in conformity to JIS P 8129. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a core sheet. More specifically, without stopping the papermaking machine immediately after papermaking, the generation of insoluble damaged paper is suppressed, papermaking is performed for a long time without accumulation of dirt in the process, and particularly excellent in water resistance and strength. The present invention relates to high quality corrugated core paper.

  Corrugated cardboard paper is classified into exterior liners and interior liners (hereinafter, these exterior liners and interior liners are collectively referred to as “liners”) and core papers that provide corrugated paper. After the paper is processed by a corrugator or the like and formed into a corrugated shape, an adhesive is applied to the top of the step and a liner is bonded to produce a cardboard such as a cardboard sheet or cardboard case.

  Conventionally, corrugated cardboard has been re-used as a raw material by recycling, and for this reason, it is generally recognized as an excellent packaging agent with low environmental impact. However, corrugated cardboard generally has the property of being vulnerable to water wetting. That is, it is a well-known fact that paper maintains its properties as paper by hydrogen bonding between pulp fibers, and that water is weakened by containing water and the strength is greatly reduced.

  For this reason, the corrugated cardboard which has not been subjected to water-resistant treatment is vulnerable to water soaking and is inappropriate as a material for packaging fresh fish and fruits and vegetables containing a large amount of moisture. Also, once the cardboard is frozen together with its contents for frozen food applications, etc., if the cardboard is left in a room temperature environment, the frost attached to the contents dissolves or the paper surface condenses, causing the cardboard to contain a large amount of moisture. The strength is greatly reduced. As a result, the cardboard, particularly the cardboard case, is swelled, crushed and buckled. For this reason, foamed polystyrene and wood have been used as materials for packing products and the like containing such a large amount of moisture.

  However, wood and polystyrene cases are not only difficult to recycle, but unlike cardboard cases that can be folded and stored when not in use, the volume changes even when the contents are not in use. Therefore, a vast space is required for storage. For this reason, from the viewpoint of distribution efficiency and recycling, in recent years, efforts to replace foamed polystyrene and wood cases with corrugated cardboard cases have become prominent.

  As a method for imparting water resistance to corrugated cardboard, a method of applying wax on the front and back surfaces of paper, a method of impregnating oil, a method of applying a water repellent, a method of laminating and the like are common. Using such a method, for example, a water-resistant liner is bonded to both surfaces of the water-resistant core base paper, and the water repellency of the bonded surface with both the front and back surfaces of the water-resistant core and the center of the water-resistant liner on both surfaces, A water-resistant cardboard sheet in which the water absorption of the cobb on the liner surface is adjusted within a predetermined range and a water-resistant paint containing a synthetic resin emulsion is applied to the surface of the water-resistant liner (Patent Document 1), and the corrugated core and the liner are water-resistant. A water-resistant corrugated cardboard (Patent Document 2) and the like, which are bonded with a conductive adhesive and whose liner is surface-treated with a coating agent mainly composed of a styrene / acrylic copolymer, have been proposed.

  However, these water-resistant corrugated cardboards do not make full use of the properties of paper that are easy to recycle, and because the main focus is on inhibiting moisture penetration on the surface of the paper, It is very difficult to prevent a decrease in strength under dew condensation conditions.

  Therefore, for example, the water-resistant corrugated sheet disclosed in Patent Document 1 is further improved, and the liner and the water-resistant core are bonded with an adhesive, and the single facer side of the water-resistant core and the bonding surface of the liner are bonded. The surface water repellency is below a predetermined value, the surface water repellency on the double facer side of the water-resistant core is above a predetermined value, the Cobb water absorption is below a predetermined value, and the surface water repellency on at least one liner outer surface is predetermined. There has been proposed a water-resistant corrugated cardboard sheet (Patent Document 3) in which a water-resistant paint mainly composed of a synthetic resin emulsion is applied to one surface of the water-resistant core.

  The water-resistant corrugated cardboard sheet disclosed in Patent Document 3 is more corrugated than the water-resistant corrugated cardboard sheet disclosed in Patent Document 1 even under conditions where a large amount of water is contacted for a long time or a large amount of water is sprayed. Although the penetration of moisture from the flute surface of the sheet is suppressed to some extent, it is difficult to sufficiently suppress the decrease in strength and crushing particularly when used as a case.

  For this reason, not only treating the surface of the paper, but also a technique for making the paper insoluble by mixing the pulp with water-resistant chemicals and then making paper is drawing attention. Utilizing such technology, for example, each of the base paper is composed of a front base paper, a core base paper, and a back base paper, each of which is composed of three or more layers of waste paper-based raw materials. A corrugated cardboard sheet (Patent Document 4) in which a predetermined amount of a water repellent agent is coated on the outermost surface of the front base paper and the back base paper has been proposed. Yes.

  However, as in the case of the corrugated cardboard sheet disclosed in Patent Document 4, even when water resistance chemicals are internally added during papermaking to impart water resistance, the problem of reduced paper recyclability is inevitable.

  Furthermore, in the base paper manufacturing process, paper that cannot be used as a product, such as waste paper, is generated mainly at the product finishing stage. Further, the most frequently occurring trouble in a papermaking machine is paper breakage. However, paper breakage occurs at the time of paper breakage, and water resistance is imparted unintentionally to such paper breakage. Usually, immediately after papermaking, these waste papers are put into a facility called a pulper, which is made of paper and water and mixed into a raw material by stirring, and used again as a raw material. However, in the case of water-resistant paper with water resistance, it is almost insoluble in water, so it cannot be used as a raw material with a pulper, and a separate storage space is required.

  In addition, chemicals that are internally added to the raw material pulp to provide water resistance are usually not included in the base paper, but are also mixed in circulating water called white water in the process of making the pulp slurry into paper. To do. The chemicals mixed in the circulating water in this way have not lost their effectiveness, and when a general product is made after making water-resistant paper, water resistance is unintentionally given to the general product as well. Trouble occurs. For this reason, immediately after making the water-resistant paper, it is essential to stop the papermaking machine and replace the circulating water, which significantly impairs the production efficiency. Moreover, the chemical | medical agent mixed in the said circulating water reacts with the anionic tinged foreign material in a process, and will become a stain | pollution | contamination, and will form the causative substance which soils a papermaking machine or a product.

Therefore, due to the above-mentioned problems, water-resistant paper is difficult to manufacture over a long period of time, and the papermaking machine is stopped immediately after papermaking, requiring a separate place for waste paper. It is.
JP 2001-246678 A JP 2001-315230 A JP 2002-013098 A JP 2004-058181 A

  The present invention has been made in view of the background art, and without stopping the papermaking machine immediately after papermaking, the generation of insoluble damaged paper is suppressed, and dirt in the process is not accumulated for a long time. An object of the present invention is to provide a core paper for corrugated cardboard, which is made of paper and is excellent in water resistance and strength and has high quality.

The present invention
A core paper for cardboard,
It consists of raw pulp that has been classified or beaten so that the Canadian standard freeness according to JIS P 8121 of the disaggregated pulp disaggregated according to JIS P 8220 is 180 to 350 ml,
A functional treatment agent containing at least a water-resistant agent is applied to at least one side of the base paper before and after the drying step and the drying step,
In accordance with JIS P 8122, the sizing degree per basis weight of the core paper is 0.001 to 0.05 seconds / (g / m ² ),
The present invention relates to a core paper characterized in that the Denison wax value in accordance with JIS P 8129 is 7A or more.

  According to the present invention, the water-proofing agent is not mixed in white water, the papermaking machine is not stopped immediately after papermaking, the generation of insoluble damaged paper is suppressed, and dirt is not accumulated in the process. A core sheet for corrugated cardboard, which has a particularly high water resistance and strength and is made of paper for a long time while confirming the addition amount of the treatment agent, is provided.

(Embodiment)
First, the raw material pulp used in the present invention will be described. The raw material pulp constituting the base paper of the core paper of the present invention is not particularly limited, but it is preferable to use at least used paper pulp, for example.

  The waste paper pulp is produced from, for example, tea waste paper, craft envelope waste paper, magazine waste paper, newspaper waste paper, reprint waste paper, flyer waste paper, office waste paper, corrugated waste paper, upper white waste paper, Kent waste paper, imitation waste paper, old paper waste paper, etc. Used paper pulp, and one or more of them can be appropriately selected and used.

  In the present invention, from the viewpoint of effective utilization of resources and utilization of environmentally friendly raw material pulp, among used paper pulp, corrugated used paper pulp is 20 to 100% by mass, further 40 to 100% by mass based on the total pulp components. It is preferable to contain.

  The raw material pulp used in the present invention is a Canadian standard based on a “pulp freeness test method” described in JIS P 8121 of a disaggregated pulp disaggregated in accordance with “pulp-disaggregation method” described in JIS P 8220. Classification or beating is performed so that the freeness (hereinafter referred to as “CSF”) is 180 ml or more, preferably 200 ml or more and 350 ml or less, preferably 330 ml or less.

  When the CSF of the disaggregated pulp is less than 180 ml, the strength of the front and back surfaces of the core paper is lowered, water drainage and drying properties are deteriorated during paper making, dryer adhesion unevenness occurs, and drying unevenness occurs. Conversely, even if the CSF of the disaggregated pulp exceeds 350 ml, a core paper having sufficient surface strength cannot be obtained, the number of binding fibers increases on the front and back surfaces of the core paper, and a paper for a functional treatment agent to be described later Impregnation unevenness occurs. Therefore, the CSF of the disaggregated pulp is adjusted to 180 to 350 ml, preferably 200 to 330 ml, from the viewpoint of the permeability of the functional treatment agent to the paper, the coverage on the paper surface, the balance of the paper surface strength, and the like.

  In the present invention, as a method of adjusting the CSF of disaggregated pulp to a range of 180 to 350 ml, for example, a method of classifying and removing fine fibers and ash using a cleaner, a washer, a filter, a separator, etc., a refiner, a disperser, For example, a kneader or the like may be used to subdivide the bundling fibers and ash by beating.

  In order to obtain the base paper constituting the core paper of the present invention, for example, a filler such as a pigment, a sizing agent, a cationized starch, a polyacrylamide resin, a polyamide epichlorohydrin resin and the like, a paper strength enhancer, and a yield improvement are obtained. Adopt normal paper making agents such as sizing agent, drainage improver, antifoaming agent, etc., as needed, adjusting the type and blending amount as needed, and adopting a method of making paper with a normal paper machine Can do.

  The layer configuration (number of layers) of the base paper constituting the core paper of the present invention is not particularly limited and may be appropriately adjusted according to the intended use of the core paper. It is preferable that it is a 1-2 layer structure so that it may become in the range to do.

  A functional treatment agent containing at least a water-proofing agent is applied to at least one side of the base paper obtained as described above.

  Examples of waterproofing agents contained in the functional treatment agent include glyoxal, urea formaldehyde, melamine formaldehyde, polyamide urea formaldehyde, ketone resins, polyamide epichlorohydrin, polyamide polyamine epichlorohydrin, glycerol polyglycidyl ether, and polyethyleneimine. Such resins are preferably exemplified, and these may be used alone or in combination of two or more. Among these, polyethyleneimine, a mixture of polyethyleneimine and dialdehyde, and polyamide epichlorohydrin are preferable from the viewpoint that the effect of imparting water resistance is large. In addition, when using the mixture of a polyethyleneimine and a dialdehyde, it is more preferable to use the mixture whose polyethyleneimine / dialdehyde (mass ratio) is 9/1 to 1/9. The polyethyleneimine preferably has a branched structure containing primary, secondary, and tertiary amino nitrogen, and more preferably has an average molecular weight of about 300 to 20000 and an amine value of about 20.

  The amount of the water-proofing agent added when the functional treating agent containing the water-proofing agent is applied to the base paper can be arbitrarily determined as long as the effect of imparting water resistance is sufficiently expressed. It is preferable that it is 0.1-10 mass% with respect to the whole quantity, Furthermore, it is 1-9 mass%.

  The functional treatment agent contains at least the water-resistant agent. If necessary, a paper strength enhancer, a preservative, and a sizing agent comprising, for example, acrylic compounds, starches such as oxidized starch and esterified starch. Etc. may be included. Among these, acrylic paper strength enhancers such as polyacrylamides, etc. from the viewpoint of compatibility with water-resistant agents, impregnation of each functional treatment agent in the core paper and affinity with raw pulp Synthetic paper strength enhancers such as acrylamide and aminomethylacrylamide copolymer salts or quaternary ammonium salts, acrylamide and quaternary ammonium base-containing alkyl (meth) acrylate copolymers, acrylamide and sodium acrylate copolymers A polyacrylamide-based dry paper strength enhancer having a number average molecular weight of about 500,000 to 1,500,000 can be suitably exemplified. In addition, the number average molecular weight of the polyacrylamide is a polystyrene conversion value that can be obtained by measurement by GPC (gel permeation chromatography). The polyacrylamides suitably used in the present invention can be obtained by copolymerizing a mixture of acrylamide or methacrylamide, a water-soluble cationic monomer, an α, β-unsaturated carboxylic acid and a dicarboxylic acid, For example, it is described in JP-A-4-267250.

The addition amount of the polyacrylamides is preferably adjusted in consideration of the addition amount of the water-proofing agent and appropriately adjusted so that the viscosity of the functional treatment agent is within the range described later. From the point that the paper itself has the function of increasing the paper quality strength, the polyacrylamide coating amount on the obtained core paper should be adjusted to 0.5 g / m ² or more, further 1.0 g / m ² or more. Is preferred. In addition, since the coating viscosity needs to be in a certain range because it is used in combination with the water-proofing agent, the amount of polyacrylamide applied to the core paper obtained is 2.0 g when used in combination with the water-proofing agent. / M ² or less, more preferably 1.5 g / m ² or less.

  The functional treatment agent is applied to at least one side of the base paper before and after the drying step and the drying step. The method for applying the functional treating agent is not particularly limited. For example, a known coating method such as a roll coater method, an air knife coater method, a blade coater method, a bar coater method, a spray coater method, a pound method or the like may be adopted. Can do. Among these, from the viewpoint of the smoothness of the base paper surface, the blade coater method, particularly the tip blade method and the vent blade method are preferable, but from the viewpoint of installation of new coating means to existing equipment, equipment maintenance, and equipment cost. Is preferably a spray coater method.

For example, by the above method, the functional treatment agent is preferably applied at a dry weight of 1.0 g / m ² or more, more preferably 1.5 g / m ² or more, and 5.5 g / m ^{2 on} one side of the base paper. ² or less, more preferably it is applied at 5.0 g / m ² or less. If the dry weight of the functional treatment agent is less than 1.0 g / m ² , the surface of the base paper cannot be uniformly covered, and uneven application of the functional treatment agent can occur, resulting in insufficient moisture resistance. There is a risk of becoming a thing. On the other hand, when the dry weight of the functional treatment agent exceeds 5.5 g / m ² , the coating solution becomes highly viscous and cannot be applied, or the drying rate after application is reduced and the drying rate is reduced. There is a risk of high costs.

  In addition, in order to further improve the processing suitability when the obtained core paper is subjected to corrugated flute processing and the bonding suitability when forming a corrugated cardboard sheet from the core paper, a hard calendar or It is preferable to perform a flattening process using a soft calendar or the like. The nip pressure between the rolls and the number of nip steps in the flattening treatment may be appropriately changed according to desired processing suitability and pasting suitability. Usually, the nip pressure is preferably about 145 to 250 kg / cm. The number of stages is preferably 2 to 4.

  The functional treatment agent is applied to at least one side of the base paper before and after the drying step and the drying step, but generally employs a film transfer method in a means for applying the coating liquid before and after the drying step and the drying step on-machine. In some cases, the following inconvenience may occur. That is, for example, when the coating speed is 1000 m / min or higher and the concentration of the coating liquid is high or the mechanical stability is low, in the case of the roll coater method, it is called an inner roll or an outer roll in addition to the applicator roll. A solidification phenomenon of the coating liquid called gum-up occurs on each roll, and there is a possibility that the roll may be in an inapplicable state. In addition, the paper separation between the paper and the applicator roll becomes unstable at the nip exit of the applicator roll, and there is a possibility that streaky coating unevenness called a ring pattern occurs.

  Therefore, as a method for solving the above-described problems, a method of reducing the coating concentration of the coating liquid is generally known. However, in the case of the functional treatment agent in the present invention, when it is diluted, it penetrates into the core paper. The coverage of the core paper surface by the functional treatment agent decreases, and it may be difficult to apply the functional treatment agent in an application amount necessary for sufficient expression of water resistance. There is.

  Therefore, in the present invention, the viscosity of the functional treatment agent is the same as that of the B-type viscometer. It is preferably 0.09 Pa · s or less, more preferably 0.08 Pa · s or less as measured at 60 rpm using a 4-rotor. When a functional treating agent having such a viscosity is used, it is possible to perform uniform coating without coating unevenness without impairing the advantages of the film transfer method, particularly on-machine high-speed and stable workability. Advantages can be utilized, and the surface of the core paper can be flattened under low calendar conditions, and excellent coating comparable to the blade coater method can be achieved. The viscosity of the functional treatment agent is the No. of the B-type viscometer from the viewpoint of scattering and mist formation of the functional treatment agent at the time of coating and ensuring the stability of operation. It is preferably 0.01 Pa · s or more as measured at 60 rpm using a 4-rotor.

  The viscosity of such a functional treating agent is that of the disaggregated pulp disaggregated in accordance with JIS P 8220 as described above, when the functional treating agent is quickly and uniformly impregnated from the surface of the core paper of the present invention. Combined with the configuration in which the CSF conforming to JIS P 8121 is 180 to 350 ml, it is preferable to uniformly impregnate the functional treatment agent into the core paper without unevenness.

  Furthermore, it is preferable that the core paper of the present invention contains a penetrating agent mainly composed of a surfactant. The surfactant is a wetting improver, and the functional treating agent is obtained by adding a penetrating agent mainly composed of a surfactant to the core paper in advance before the functional treating agent is applied. Can penetrate from the paper surface to the inside without delay.

  The waterproofing agent contained in the functional treating agent that can be used in the present invention is originally contained in the paper by internal addition, and when it is provided on the exposed surface of the base paper in the external addition, It is necessary to impregnate a water-proofing agent to ensure water resistance against water penetration from the thickness direction of the base paper. Therefore, it is preferable to impregnate the functional treatment agent on the exposed surface, at least one side of the base paper, immediately after impregnation, and by using such a penetrant in combination, the functional treatment agent can be impregnated more effectively and uniformly. Can be planned.

  The type of the surfactant is not particularly limited, and examples thereof include polyoxyalkylene fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene nonylphenyl ether and the like. Among these, in particular, when a polyoxyalkylene fatty acid ester is used, there is an advantage that the compatibility with the water-proofing agent contained in the functional treatment agent is good and the penetration of the functional treatment agent is further promoted.

  Examples of the method for adding a penetrating agent mainly composed of a surfactant to the core paper include a method of externally applying by a film transfer method, a spray method, and the like, and a method of making a paper by adding it to raw pulp in advance. It can be suitably employed.

  The content in the core paper of the penetrating agent mainly composed of a surfactant is 0 in terms of dry weight per ton of the core paper from the viewpoint that the effect of allowing the functional treatment agent to uniformly penetrate into the paper quality is exhibited. 0.1 kg or more, more preferably 0.2 kg or more, and the addition of an excessive amount of surfactant significantly reduces the size of the core paper and brings about a decrease in water resistance. The penetration of excess functional treatment agent is promoted by promoting penetration, resulting in uneven water resistance and increased costs. Therefore, the dry weight per ton of core paper is 2.0 kg or less, and further 1.8 kg or less. Preferably there is.

  In the present invention, the composition of the raw material pulp constituting the core paper, particularly the freeness of the core paper (the disaggregation freeness in the paper-made state), the constitution of the functional treatment agent for improving various functions, particularly the chemical ( The content of the component)), conditions such as concentration, viscosity, etc., and more preferably, by using in combination with a penetrant that further promotes the effect of the functional treatment agent, the waterproofing agent is not mixed into white water, immediately after papermaking In addition, the generation of insoluble damaged paper is suppressed without stopping the papermaking machine, and the paper is made over a long period of time while the amount of the functional treatment agent added is confirmed without accumulation of dirt in the process. Provided is a core sheet for corrugated cardboard having excellent properties and strength and high quality.

The thus obtained core paper of the present invention has a physique sizing degree per basis weight (conforming to JIS P 8122) measured in accordance with “paper and paperboard—size test method—Steecht method” described in JIS P 8122. The value obtained by dividing the Steecht sizing degree (seconds) by the basis weight was 0.001 second / (g / m ² ) or more, preferably 0.002 second / (g / m ² ) or more. Further, it is 0.05 second / (g / m ² ) or less, preferably 0.04 second / (g / m ² ) or less.

The core paper of the present invention is composed of raw pulp that has been classified or beaten so that the Canadian standard freeness according to JIS P 8121 of the disaggregated pulp according to JIS P 8220 is 180 to 350 ml. The functional treatment agent is absorbed into the base paper very quickly, and the functional treatment agent uniformly penetrates into the base paper and becomes easy to dry, in the functional treatment agent including a water-resistant agent. The effect unevenness of each component does not occur excessively, and the degree of sizing of the core paper is suitably adjusted in the range of 0.001 to 0.05 seconds / (g / m ² ).

  Accordingly, unlike conventional core paper, problems such as uneven bonding with the front and back liners constituting the corrugated cardboard and processing suitability are solved. That is, the core paper of the present invention in which a functional treatment agent containing at least a water-proofing agent is applied on at least one side of the base paper has a steecht sizing degree in such a range, and thus is suitable for cardboard and particularly effective. It has a high water resistance and can constitute an excellent water-resistant cardboard.

  In addition, in this specification, the Steecht sizing degree means the value which divided the value measured based on JISP8122 by basic weight as mentioned above.

  Further, the core paper of the present invention has a Denison wax value of 7 A or more measured according to “Paper and paperboard—paper peeling test method—accelerated printing method using an electric IGT tester” described in JIS P 8129, Preferably it is 8A or more. Since the core paper of the present invention has a Denison wax value in this range, that is, surface strength, sufficient strength necessary for conveyance when a corrugated cardboard is formed and excellent bonding suitability with front and back liners are imparted. . When such a Denison wax value is less than 7A, there arises a problem that the bonding part is carelessly peeled off and a bonding part with the surface layer sheet is peeled off in corrugated board formation.

  In the present invention, the Denison wax value is preferably as large as possible, but it is actually about 15 A or less from the viewpoint that it is a core paper that is originally high-mixed with used paper as a raw material.

  Further, the core paper of the present invention has a Beck smoothness of 8 seconds or more, preferably 9 measured according to “Smoothness test method using paper and paperboard-Beck smoothness tester” described in JIS P 8119. It is desirable that it is not less than 2 seconds, more preferably not less than 10 seconds, and not more than 25 seconds, preferably not more than 24 seconds. When the Beck smoothness is less than 8 seconds, the flatness of the surface of the core paper is deteriorated, and not only the effect of the functional treatment agent is uneven, but also the processing suitability during corrugated cardboard processing and the application to the front and back liners. The suitability may be insufficient and the operability may be reduced. On the contrary, if the Beck smoothness exceeds 25 seconds, the drying property of the applied functional treating agent may be impaired. In order to control the Beck smoothness of the core paper so as to fall within such a range, for example, the raw pulp constituting the base paper of the core paper is disaggregated in accordance with JIS P 8220 as described above. What is necessary is just to adjust so that the CSF based on JISP8121 of the disaggregated pulp may be 180-350 ml.

Furthermore, the core paper of the present invention has a basis weight measured in accordance with the “basis weight measurement method” described in JIS P 8124 of about 70 to 200 g / m ² , and “thickness and density The density measured according to “Test method” is about 0.5 to 0.8 g / cm ³ and the paper thickness is about 120 to 280 μm. It is preferable in terms of the operability and the utilization efficiency of the obtained cardboard.

  Next, the core sheet of the present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples.

Examples 1-32 and Comparative Examples 1-7 (Manufacture of core paper)
The raw material pulp blended with waste paper pulp at the ratio shown in Tables 1-2 is disaggregated according to the method described in JIS P 8220, and the CSF based on JIS P 8121 of the disaggregated pulp is the value shown in Tables 1-2. It adjusted so that it might become. The surfactant shown below was added to the resulting cored paper so as to be contained at a dry weight shown in Tables 1 to 2 to obtain a pulp slurry, and then a long paper machine. A base paper having a basis weight of about 80 to 185 g / m ² was produced by paper making at 500 m / min. In Example 8 and Comparative Examples 7 to 10, a long net multilayer paper machine was used, and the layer configuration shown in Tables 1 and 2 was employed.

  Next, in the pre-dryer part, the dryer part, and the after-dryer part, the functional treatment agents shown in Tables 3 to 4 were applied on the one side shown in Tables 3 to 4 (dry weight) by the coating method shown in Tables 3 to 4 ) Was applied to the front and back surfaces of this base paper to obtain a core paper.

  The viscosity of the functional treating agent is the same as that of the B-type viscometer. It is the value measured at 60 rpm using 4 rotors. Moreover, in Tables 3-4, the addition amount of the water-resistant agent with respect to raw material pulp whole quantity is also shown collectively.

  The surfactants shown in Tables 1 and 2 and the waterproofing agents and coating methods shown in Tables 3 and 4 are as follows. Each functional treatment agent is blended with the following polyacrylamides together with a water resistance agent.

(Surfactant)
・ Nonionic low molecular surfactant (polyoxyalkylene fatty acid ester which is an alkylene oxide addition product of a fatty acid usually having 6 to 22 carbon atoms)

(Waterproofing agent)
PEI / DA: polyethyleneimine / dialdehyde (100/10 to 300 by mass ratio)
Range) mixture.
・ PEI: Polyethyleneimine ・ PAEH: Polyamide epichlorohydrin

(Polyacrylamides)
・ Polyacrylamide (Product number: PS-273, manufactured by Arakawa Chemical Industries, Ltd.)

(Coating method)
・ G: Gate roll coater method ・ P: Pound method ・ B: Blade coater method

  Each physical property of the obtained core paper was measured by the following method. These results are shown in Tables 5-6.

  Further, commercially available core papers A to C were used as Comparative Examples 8 to 10, and each physical property was measured in the same manner. These results are also shown in Table 6. Moreover, about these commercially available core paper AC, the CSF of disaggregated pulp and the layer structure of a base paper are shown together in Table 2. In addition, in the commercially available core papers A to C, a modified polyamide / polyamine resin was detected as an internally added waterproofing agent.

(A) Basis weight It measured based on JISP8124.

(B) Density and paper thickness Measured according to JIS P 8118.

  Next, quality evaluation was performed on the core sheets of Examples 1 to 32 and Comparative Examples 1 to 10 by the following method. The results are shown in Tables 7-8.

(1) Degree of squeecht per basis weight (adhesion suitability with front and back liner)
The measurement was made according to JIS P 8122 (2004).

(2) Denison wax value Measured according to JIS P 8129 (1997).

(3) Beck smoothness Measured according to JIS P 8119 (1998).

(4) Strength (A) Tensile strength (longitudinal)
Measurement was performed according to JIS P 8113 (1998).
(I) Compressive strength (horizontal)
It measured based on JIS P 8126 (2005).
(C) Wet tensile strength (longitudinal)
It measured based on JIS P 8135 (1998).
In addition, based on the results of the above (a) to (c), the strength was comprehensively evaluated in four stages of ◎, ○, Δ, and ×. Of these, ◎ and ○ are judged to be actually usable.

(4) Dust generation amount Based on SEMI G67-0996, the dust generation amount (number of generated paper dust) at the time of 100L suction was measured with a particle counter (RION Co., Ltd., model KC-20). The numbers shown in Tables 7 to 8 are converted per 1 m ³ .

(5) Manufacturing cost In the production line for core paper, the necessity of stopping the papermaking machine immediately after papermaking, the presence or absence of insoluble damaged paper, the state of dirt in the process and the time for papermaking were investigated, and the following evaluations were made. Evaluation was based on criteria.
(Evaluation criteria)
A: It was not necessary to stop the papermaking machine immediately after papermaking, no insoluble damaged paper was generated, and papermaking was possible for a long time without accumulation of dirt in the process.
○: It was not necessary to stop the papermaking machine immediately after papermaking, almost no insoluble damaged paper was generated, and papermaking was possible for a relatively long time with little accumulation of dirt in the process.
Δ: The papermaking machine was not stopped immediately after papermaking, but insoluble damaged paper was generated, and the dirt in the process was slightly noticeable, so that the papermaking time was relatively short.
X: The papermaking machine had to be stopped immediately after the paper making, and there were many insoluble waste papers, and the dirt in the process was accumulated, so the paper making time was very short.
Of the above evaluation criteria, the cases of ○ and ○ are judged to be actually usable.

  In each of the core sheets of Examples 1 to 32, a functional treatment agent containing a water-resistant agent is applied to the front and back surfaces of the base paper made of raw pulp whose disaggregated pulp CSF is adjusted to 180 to 350 ml. It has a specific range of Steecht sizing and Denison wax values. Therefore, all of the core sheets of Examples 1 to 32 do not stop the papermaking machine immediately after the paper making, and the generation of insoluble damaged paper is sufficiently suppressed, and the contamination in the process is not accumulated for a long time. Since the paper is made over time, the manufacturing cost is sufficiently suppressed, it is excellent in bonding with the front and back liners, has high strength, and has excellent water resistance, so it has high wet strength. It turns out that it is a core paper.

  On the other hand, the core papers of Comparative Examples 1 to 6 are particularly wet because they are low in strength and inferior in water resistance because a functional treatment agent that does not contain a waterproofing agent is applied to the front and back surfaces of the base paper. It can be seen that this is a very low-quality, core paper. In addition, since the core paper of Comparative Example 7 is not coated with a functional treatment agent on the front and back surfaces of the base paper, the paper-making machine is stopped immediately after the paper making, or a large amount of insoluble damaged paper is generated, causing contamination in the process. Is accumulated and cannot be made over a long period of time, indicating that it is a core sheet with high manufacturing cost.

  In addition, the core paper of Comparative Examples 8 to 10 is internally added without applying the water-proofing agent to the surface of the base paper, and because the degree of steecht is large, the papermaking machine is stopped immediately after papermaking, Since the amount of insoluble waste paper generated is large and dirt in the process accumulates and papermaking cannot be performed for a long time, it can be seen that the core paper is high in production cost.

  The core paper of the present invention can be suitably used for corrugated cardboard such as corrugated cardboard sheets and cardboard cases that require particularly high water resistance.

Claims (3)

A core paper for cardboard,
It consists of raw pulp that has been classified or beaten so that the Canadian standard freeness according to JIS P 8121 of the disaggregated pulp disaggregated according to JIS P 8220 is 180 to 350 ml,
A functional treatment agent containing at least a water-resistant agent is applied to at least one side of the base paper before and after the drying step and the drying step,
In accordance with JIS P 8122, the sizing degree per basis weight of the core paper is 0.001 to 0.05 seconds / (g / m ² ),
A core paper having a Denison wax value of 7A or more in accordance with JIS P 8129.   Before the functional treatment agent is applied, a penetrant mainly composed of a surfactant is previously contained in an amount of 0.1 to 2.0 kg in dry weight per ton of the core paper. The core paper described.   No. B-type viscometer The core sheet according to claim 1, wherein the viscosity of the functional treatment agent is 0.01 to 0.09 Pa · s measured at 60 rpm using a four rotor.