JP5289127B2 - liner - Google Patents

Description

  The present invention relates to a liner used for various liquid containers such as cardboard and milk cartons, and more particularly to a liner excellent in water repellency and slip resistance.

  In general, corrugated cardboard is composed of liner paper constituting the front and back surfaces, and a normal corrugated core paper located between both liner papers.

  The corrugated cardboard thus configured is used for various purposes, but has a problem that it is weak against water wetting. In particular, in the case of a box used for fruit and vegetables, in order to cope with moisture of the contents, conventionally, water repellency has been imparted to liner paper.

For example, in Patent Document 1, unlike a resin film or a composite material of polyvinyl chloride and paper, it can be reused as waste paper pulp, and a coating agent mainly composed of polyvinyl alcohol is applied to the undercoat layer, and the top coat is applied. A moisture-proof paper is disclosed in which a coating agent mainly composed of a styrene-butadiene copolymer is applied to the layer, the coating layer has a two-layer structure, the moisture permeability is 200 g / m ² or less, and the sliding angle is 29 degrees or more. Yes. However, compared with conventional film or composite material of vinyl chloride and paper, although it is easy to recycle as waste paper pulp, when used for corrugated cardboard, in addition to being inferior in heat resistance, the resin inside the paper layer Therefore, there is a problem that the surface of the coating layer is likely to get wet with water.

  In Patent Document 2, in a water-resistant liner having a three-layer structure, 0.5 to 25 parts by weight of a wet paper strength enhancer is added to an intermediate layer, and polyvinyl alcohol having a saponification degree of 93 or more is repelled. A water resistant liner coated with a coating agent mixed with a liquid composition is disclosed. However, even in the water-resistant liner according to Patent Document 2, the components of the applied water repellent composition are transferred to the inside of the paper layer due to heat due to the hot plate during box making. There is a problem that the water repellency of the coating layer surface is lowered and water wetting tends to occur.

  Patent Document 3 discloses a liner paper coated with a coating liquid in which an oil-absorbing reducing agent and a water repellent composition are mixed, and the components of the heated water repellent composition are paper. Prevents penetration into the layer. However, although the liner paper according to Patent Document 3 is satisfactory in water repellency, the frictional resistance of the surface is low, and when it is formed into a cardboard case, it has a problem that it is slippery and easily collapses.

  Furthermore, Patent Document 4 discloses an easy disaggregation / moisture proof / waterproof paper which is surface-treated with a coating agent mainly composed of a styrene / acrylic copolymer and is dried and heated at a temperature equal to or higher than the minimum film increasing temperature of the coating agent. It is disclosed. However, although the easy disaggregation / moisture proof / waterproof paper according to Patent Document 4 is satisfactory in terms of waterproofness and slip resistance, it has not yet satisfied water repellency with respect to water.

  Further, the liner paper or the like that has been subjected to water repellency as described above has a problem that the water repellency performance deteriorates with time or by heating. In particular, when a wax-based water repellent composition is applied, when used in a corrugated cardboard case, it tends to be slippery and easy to collapse, and has a problem that it is difficult to handle.

JP 2003-96697 A JP 2004-204385 A JP 2004-277897 A JP-A-5-25796

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is to prevent water repellency from being lowered over time or by heating even when subjected to water repellency, and is excellent. Another object of the present invention is to provide a liner that can maintain anti-slip properties.

The object of the present invention is a liner paper having a base paper composed of at least a front surface layer and a back surface layer, wherein the water repellent composition has a weight of 3 to 8% and a weight of 5 to 5 on at least the surface layer of the base paper. It has a coating layer coated with a coating solution containing polyvinyl alcohol having a saponification degree of 10% of 98.0 to 99.0 mol%, and the water repellent composition has a melting point of 48 to 65 ° C. The average particle size of the emulsion containing a wax resin is 300 to 600 nm, and the disintegrated pulp of the surface layer that has been separated from the surface layer and disaggregated according to JISP8220 has a kappa number measured according to JISP8211. This is accomplished by providing a liner characterized in that it is 50-70.

In addition, the above-mentioned object of the present invention is that the disintegrated pulp of the surface layer is a continuous digester outlet, and a softwood kraft pulp produced by mechanically beating and pulping with a refiner before or during the selection process. It is effectively achieved by providing a liner according to claim 1, characterized in that

  In addition, the above object of the present invention is that the disintegrated pulp of the surface layer has a freeness of 500 to 650 cc, an average fiber length of 2.0 to 3.0 mm, and a Runkel ratio of 0.8 to 1.2. This is achieved more effectively by providing a liner characterized by being.

Furthermore, the above object of the present invention is more effective by providing a liner in which the water repellent composition further contains a latex having a glass transition temperature of −50 to −15 ° C. Achieved.

  The liner according to the present invention is a liner paper having a base paper composed of at least a front surface layer and a back surface layer, and a water repellent composition, particularly a cost-effective wax resin, is provided on at least the front surface layer of the base paper. Since the coating layer coated with the coating liquid contained is formed and the kappa number of the disintegrated pulp of the surface layer is 50 to 70, even if water repellent processing is performed, water repellency performance over time or by heating Can be prevented, and slip resistance can be maintained.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the liner of the present invention.

  Hereinafter, the liner according to the present invention will be described in detail by taking as an example the case where the base paper is composed of two layers of a front surface layer and a back surface layer. The liner according to the present invention is not limited to the following embodiments, and it goes without saying that the configuration can be changed as appropriate without departing from the scope of the claims.

  The liner according to the present invention (hereinafter referred to as “the present liner”) has a base paper composed of a surface layer and a back surface layer, and a coating liquid containing a wax-based resin is applied onto the surface layer of the base paper. To form a coating layer. In this embodiment, the case where the coating layer is formed only on the surface layer of the base paper will be described. However, the coating layer may be formed on the surface layer of the base paper and the back layer.

  As a raw material pulp of the base paper of this liner, various things, such as a wood pulp, a non-wood pulp, a synthetic pulp, a used paper pulp, can be used, for example. More specifically, ground wood pulp (GP), stone ground pulp (SGP), refiner ground pulp (RGP), pressurized ground wood pulp (PGW), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), bleach Mechanical pulp (MP) such as Chemi-thermomechanical pulp (BCTMP), chemical mechanical pulp (CGP), semi-chemical pulp (SCP), hardwood bleached kraft pulp (LBKP), softwood kraft pulp (NBKP), hardwood unbleached craft Kraft pulp such as pulp (LUKP, LKP), softwood unbleached kraft pulp (NUKP, NKP), chemical pulp (CP) such as soda pulp (AP), sulfite pulp (SP), dissolved pulp (DP), nylon , Rayon, polyester, polyvinyl alcohol ( VA) and other raw paper pulp such as synthetic pulp, deinked pulp (DIP) and waist pulp (WP), waste pulp (TP), cotton, flax, hemp, jute, manila hemp, ramie, etc. It is possible to select and use one or several kinds of those used in ordinary liners, such as pulp, straw pulp, esparto pulp, bagasse pulp, bamboo pulp, kenaf pulp, and other auxiliary pulp such as bast pulp. it can.

Also, the type of used paper that forms the used paper pulp that can be used for the base paper of the liner is not particularly limited. For example, in addition to used paper such as newspapers and flyers, coated paper and non-coated paper are also used. Also, used magazine paper including paper having various bleaching resistances such as color printed paper and black and white printed paper can be used. Among these, waste paper having a basis weight of 100 to 320 g / m ² , preferably 220 to 320 g / m ² and a thickness of 125 to 390 μm, preferably 250 to 390 μm can be suitably used.

  Further, the present liner may contain 30% by mass or more of waste paper pulp with respect to the weight of the pulp raw material of the entire base paper (that is, the total weight of raw material pulp constituting the front surface layer and the back surface layer in this embodiment). preferable.

  In addition, although a surface layer and a back surface layer may be comprised using the same raw material pulp, normally, a surface layer is formed with a good quality constituent material, and a back surface layer is formed with a somewhat inferior constituent material. Specifically, a method is adopted in which the surface layer is formed using a mixture of kraft pulp and waste paper pulp, and the back layer is formed only from waste paper pulp.

  Furthermore, the raw material pulp constituting the surface layer of the base paper of the liner has a softwood unbleached kraft pulp (NUKP) with respect to the weight of the raw material pulp of the surface layer from the viewpoint of improving the water repellency of the liner. It is preferable to blend 100 mass%.

  Further, the surface layer of the pulp separated from the base paper and disaggregated according to JISP8220 (hereinafter referred to as “dissolved pulp of the surface layer”) is a copper value (hereinafter referred to as “copper”) measured according to JISP8211. Value)) is 50 to 70, preferably 50 to 60. When the kappa number of the disintegrated pulp of the surface layer is less than 50, the lignin and other resin components in the raw pulp tend to decrease, so the reactivity with the water repellent composition used in this liner is weak. Thus, when heated, it easily penetrates into the paper layer, that is, the water repellency is lowered by heating. On the other hand, when the kappa number exceeds 70, the lignin and other resin components in the raw material pulp tend to increase, so the reactivity with the water repellent composition used in this liner is increased, and the water repellent Although the fixing of the composition to the pulp is improved, the penetration into the paper layer when heated is reduced, and dirt tends to adhere to the hot plate in the box making process, which is not preferable.

  The disintegrated pulp of the surface layer has a freeness of 500 to 650 cc, an average fiber length of 2 to 3 mm, and a Runkel ratio of 0.8 to 1.2, preferably 0.93 to 1.13. Thereby, when using this liner for a corrugated board use, it comes to have the resistance to a ruled line cracking required. In addition, when the freeness of the disintegrated pulp in the surface layer is less than 500 cc, the strength against bending stress tends to decrease, and the resistance to ruled line cracking decreases. On the other hand, if it exceeds 650 cc, the resistance to ruled line cracking tends to improve, but the pulp fibers tend to be stiff, and the entanglement between the fibers tends to deteriorate. In addition, if the average fiber length is less than 2 mm, the fibers are unlikely to sway in water, and the entanglement of the fibers becomes weak and the strength may be reduced. On the other hand, when the average fiber length exceeds 3 mm, the fibers are liable to be squeezed in water, tend to be bound, and tend to be generated as foreign matter on the paper surface. Further, if the Runkel ratio is less than 0.8, the fiber itself tends to lose its rigidity, and the paper required when the liner is used for corrugated cardboard tends to be lost. On the other hand, if the Runkel ratio exceeds 1.2, the rigidity of the fiber tends to be high and hard, so it becomes difficult to satisfy the ruled line cracking resistance required when the present liner is used for corrugated board.

  In addition, softwood unbleached kraft pulp (NUKP) used for this liner, especially NUKP most suitable for the surface layer, is used in the stock preparation process (pre-process of paper making process) in the normal kraft pulp manufacturing process. The pulp beating process is performed after the pulp cooking process and before or during the fine selection process.

  More specifically, NUKP used in this liner increases the kappa number by lowering the cooking degree of the pulp raw material, and uses a continuous digester outlet and a refiner before or during the selection process. It is a high yield NUKP produced by beating and completely pulping. In this way, by lowering the degree of cooking in the cooking process, the amount of steam and cooking chemical used in the cooking process can be reduced, and the pulp strength (particularly, the specific tear rate) can be reduced by beating at a high concentration with a refiner. ) High NUKP. Thus, if the amount of the cooking chemical solution (caustic soda, sodium sulfide, etc.) is decreased, it is possible to reduce the damage of the pulp fibers and increase the pulp strength (particularly, the specific tear rate). Further, by mechanically beating with a refiner at a pulp concentration of 10 to 20%, fibrillation of the pulp fibers can be promoted, and NUKP having high strength and few binding fibers can be produced.

  In implementing the said manufacturing method, it is good to make the kappa number which shows the cooking degree in a cooking process into 50 or more and 70 or less. If this kappa number is less than 50, the lignin and other resin components in the raw pulp tend to decrease, so the reactivity with the water repellent composition used in this liner is weakened and is subject to heating. It easily penetrates into the paper layer. On the other hand, when the kappa number exceeds 70, the lignin and other resin components in the raw material pulp tend to increase, so the reactivity with the water repellent composition used in this liner is increased, and the water repellent Although the fixing of the composition to the pulp is improved, the penetration into the paper layer when heated is reduced, and dirt tends to adhere to the hot plate in the box making process, which is not preferable. From the above viewpoint, NUKP produced by this production method is suitably used as a raw material pulp for a liner that requires water-repellent processing like the present liner.

  In addition, in the liner base paper, an intermediate layer is usually provided between the front surface layer and the back surface layer, but it is preferable to provide an intermediate layer also in the liner base paper. An intermediate | middle layer is a layer which consists of paper which uses a pulp as a main component material. Examples of the pulp include waste paper pulp, chemical pulp such as LBKP and NBKP, mechanical pulp such as GP and TMP, non-wood fibers such as kenaf and bagasse, and synthetic fibers. Can be used.

  Further, the intermediate layer may be a single layer or a multilayer as long as the desired effects such as water repellency and oil absorbability of the liner are not impaired. When it consists of multiple layers, it is particularly preferred to have 2 to 8 layers, and a functional agent such as a wet paper strength agent or a freshness preserving agent may be blended for each layer. In addition, when providing the layer which mix | blended the freshness-keeping agent, providing in the vicinity of a back surface layer is preferable taking advantage of the effect of this invention. In addition, when the intermediate layer is a multilayer, the configuration of the raw material pulp and the like of each layer may be the same or different.

  In addition, the liner is coated with a coating solution containing a water repellent composition on the surface layer of the base paper to form a coating layer, thereby imparting water repellency.

  Examples of the water repellent composition contained in this coating liquid include wax-based, synthetic resin-based, acrylic-based, paraffin-based, fluorine-based, silicone-based, and the like. Can be used.

  Among these, it is particularly preferable to contain a wax resin having a melting point of 48 to 65 ° C. Specifically, paraffin wax, microcrystalline wax, polyethylene wax and the like can be used as such a wax, and these can be used alone or in combination of two or more.

  Moreover, it is preferable that the water repellent composition contained in the coating liquid applied to the liner is a water repellent composition containing a wax resin and latex. Furthermore, the content of the wax resin is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, based on the solid content of the entire water repellent composition. More preferably, the latex content is 20 to 60% by weight based on the solid content of the entire water repellent composition. In addition, resin and various chemicals as needed can be added to the remaining components. By applying such a water repellent composition to the surface layer of the base paper, the liner can have both water repellency and slip resistance. Further, although heat treatment is involved in the step of processing the liner into a corrugated cardboard sheet, it is possible to prevent the water repellency from greatly decreasing due to the heat treatment.

  Further, the latex used as the water repellent composition of the coating liquid of the present liner preferably has a glass transition temperature (sometimes abbreviated as Tg) of −15 ° C. or lower, and is −50 to −15 ° C. More preferably it is. As such a latex, a styrene-butadiene copolymer latex (hereinafter sometimes abbreviated as SBR) obtained by a known polymerization method, a methyl methacrylate-butadiene copolymer latex (hereinafter sometimes abbreviated as MBR). Synthesis of acrylonitrile-butadiene copolymer latex (hereinafter sometimes abbreviated as NBR), chloroprene latex, isoprene latex, vinyl chloride latex, vinylidene chloride latex, polybutadiene latex and mixtures of one or more of these Examples thereof include rubber latex. SBR, MBR and NBR are preferred. Among these, SBR is preferable. The SBR latex may be modified such as carboxylated styrene / butadiene copolymer latex in addition to unmodified styrene / butadiene copolymer latex.

  Further, as the resin used as the water repellent composition of the coating liquid of the present liner, petroleum resin, rosin resin, terpene resin and these resin components are maleic acid, maleic anhydride, fumaric acid, itaconic acid, etc. These resins may be anion-modified with a dibasic acid or the like, and one of these may be used alone or two or more may be used as a mixture. Among these, petroleum resins, rosin resins, and resins obtained by anionic modification of these resin components are preferable.

  Examples of petroleum resins include aliphatic petroleum resins, aromatic petroleum resins, alicyclic petroleum resins, or mixed petroleum resins thereof and anion-modified products thereof. Examples of the aliphatic petroleum resin include petroleum resins obtained from butene, isobutene, pentene, pentadiene, isoprene and the like. Examples of the aromatic petroleum resin include petroleum resins obtained from indene, methylindene, vinyltoluene, styrene, α-methylstyrene, β-methylstyrene, and the like. Examples of the alicyclic petroleum resin include petroleum resins obtained from monomers such as cyclopentadiene and dicyclopentadiene (DCPD). Examples of the mixed petroleum resin include petroleum resins obtained from the aliphatic and aromatic monomers. Examples of such anion-modified products of petroleum resins include maleic acid-modified products of the petroleum resins. Among these petroleum resins, mixed petroleum resins are preferable.

  Examples of the rosin resin include gum rosin, wood rosin, tall oil rosin, and rosin obtained by anion modification with dibasic acids such as maleic acid, maleic anhydride, fumaric acid, and itaconic acid.

  Examples of terpene resins include α-pinene resins, β-pinene resins, and aromatic-modified terpene resins obtained by copolymerizing terpenes such as α-pinene and β-pinene and aromatic monomers such as styrene. .

  Further, the resin used in the liner preferably has an acid value of 10 to 60 mgKOH / g, and more preferably 20 to 50 mgKOH / g.

In addition, the resin acid value in this specification means what was measured as follows.
Measurement Method of Resin Acid Value To 1.5 g of resin, a mixed solvent of toluene / methanol = 7/3 is added and dissolved. Add 2 to 3 drops of 1% phenolphthalein as an indicator, and titrate with N / 10 potassium hydroxide alcohol solution. The end point of the titration is the point where the indicator has a slight red color that lasts for 30 seconds.
Acid value = V × F × 5.661 / S
V: Amount used of N / 10 potassium hydroxide alcohol solution (ml)
F: Potency of N / 10 potassium hydroxide alcohol solution S: Sample amount (g)

  Further, the water repellent composition of the coating liquid of the present liner can be used in combination with various surfactants in addition to the wax resin, latex, and resin. As the surfactant, a nonionic surfactant or an anionic surfactant can be used. These surfactants can be used alone or in admixture of two or more.

  Nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and polyoxyethylene alkyl phenyl ether; polyoxyethylene sorbitan monolaurate, And polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate.

  Examples of the anionic surfactant include sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene phenyl ether sulfate, and the like.

  Further, as a method of obtaining an emulsion of the water repellent composition contained in the coating liquid used in the present liner, a method of preparing a wax resin emulsion in advance and mixing with the latex emulsion, a wax resin and a latex Any of the methods of emulsifying in a mixed state can be performed. In addition, when the water repellent composition contains a resin, a wax resin and a resin emulsion are prepared in advance, and these are mixed with a latex emulsion. The wax resin, the resin, and the latex are mixed and melted. Any method of emulsifying in a state may be used.

The method for preparing the emulsion is not particularly limited, but a method in which a small amount of water is mixed with the melt to form a water-in-oil emulsion, and inversion water is added to cause phase transition to an oil-in-water emulsion (phase inversion method). ), A method of producing an oil-in-water emulsion through a homogenizer under high temperature and high pressure (for example, 130 to 200 ° C., 150 to 1000 Kg / cm ² ), etc. (mechanical method) is used.

  Moreover, it is preferable that the average particle diameter of an emulsion is 300-600 nm, and, as for the water repellent composition contained in a coating liquid, it is more preferable in it being 350-500 nm. When the average particle size of the emulsion is less than 300 nm, it easily penetrates into the paper layer and it becomes difficult to satisfy the water repellency desired by the present application. On the other hand, if the average particle diameter exceeds 600 nm, the wax resin tends to stop on the paper surface, so that it is difficult to ensure the desired anti-slip property of the present application.

  As such a water repellent composition, trade names “RIPAX A240” manufactured by Modern Chemical Co., Ltd., which are wax-based, trade names “PARATEX NS6” and “PARATEX NS630” manufactured by Hoshiko Chemical Co., Ltd., paraffin The product name “Cybinol PC-10” manufactured by Sanden Chemical Co., Ltd., which is a system, is preferably used because of its good water dispersibility during regeneration. In addition, these commercially available water repellent compositions are prepared by dissolving an active ingredient as a water repellent composition in a solvent or dispersing it in water or the like.

  Moreover, it is preferable that the coating liquid used for this liner contains polyvinyl alcohol (henceforth "PVA") whose saponification degree is 98.0-99.0 mol%. Specifically, the coating solution used for the liner is preferably a solution obtained by adding and dissolving a water repellent composition to a PVA solution dissolved in a PVA solvent. Thereby, this liner becomes easy to obtain water-repellent strength and to make the surface strength and wear resistance strength to a desired level. Moreover, the polymerization degree of PVA is preferably 450 to 2000 in terms of improvement in film strength, hygroscopicity, and crosslinking effect.

  In this case, the coating liquid preferably contains 3 to 8% by mass of the water repellent composition and 5 to 10% by mass of PVA. As described above, when the blending amount of the water repellent composition is 3% by mass or more, the water repellent performance is enhanced, water is repelled for a long time, and water does not permeate in a fast time. Further, even if the blending amount of the water repellent composition is more than 8% by mass, the effect of improving the water repellency is not changed, and only the cost is increased. Moreover, by setting the blending amount of PVA to 5% by mass or more, it is possible to prevent the water repellent composition after coating from penetrating into the paper, and effectively achieve the desired water repellent performance of the present application. Satisfaction can be satisfied, and by setting the content to 10% by mass or less, it is possible to satisfy the ruled line cracking resistance necessary for the present liner.

Further, in this liner, coating amount of the coating solution containing the water repellent composition is preferably a 0.05 to 2.0 g / ^{m 2,} and 0.07~1.5g / ^{m 2} Is more preferable. By setting the coating amount of the coating liquid to 0.07 g / m ² or more, better water repellency can be obtained, and by setting it to 1.5 g / m ² or less, slipping caused by the water repellent composition The decrease in angle can be alleviated. That is, this liner can have excellent anti-slip performance. The coating amount is based on the weight of the active ingredient.

  As described above, this liner has a base paper composed of a surface layer and a back surface layer, and a coating layer containing a water repellent composition is applied onto the surface layer of the base paper to form a coating layer. If it is, the surface layer and the back layer are provided with, for example, a surface sizing agent, an anti-slip agent after forming the packaging container, an oil resistant agent, an ultraviolet absorber, and light / weather resistance, as long as the desired effects of the present invention are not impaired. Other additive chemicals such as an agent may be further added and mixed depending on the application. Furthermore, for example, a printing layer or the like may be provided between the surface layer of the present liner and the coating layer depending on the application.

  In the present liner, when reducing the oil absorption, before forming the coating layer, a coating liquid containing an oil absorption reducing agent is applied onto the surface layer of the base paper to thereby reduce the oil absorption lowering layer. Form. Examples of the oil-absorbing lowering agent include styrene-acrylic acid polymers, modified products of this material, those obtained by mixing this material with acrylic amide, and oxidized starch, modified products of starch, etc. Two or more kinds can be mixed and used. In addition, as such an oil absorptivity reducing agent, commercial items, such as a brand name "Kay Coat SA604" and a brand name "Kay Coat S-165" by Modern Chemical Industry Co., Ltd., can also be used.

  Moreover, it is preferable to set it as 1-40 weight part with respect to 100 weight part of water repellent compositions mentioned above, and it is still more preferable to set it as 3-20 weight part with respect to 100 weight part of water repellent compositions mentioned above. By making the blending amount of the oil-absorptive lowering agent 3 parts by weight or more, the oil-absorbing inhibitory effect is sufficiently exhibited, and by making it 20 parts by weight or less, there is no coating trouble caused by styrene-based aggregates. Therefore, it is preferable to be within the above range.

  Next, a preferred embodiment of the liner structure according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a preferred embodiment of a liner according to the present invention. That is, as shown in FIG. 1, the liner 1 of the present embodiment includes a surface layer 2 and a back layer 4, and an intermediate layer 3 positioned between the surface layer 2 and the back layer 4. The coating layer 5 is formed by applying the coating liquid.

  Although not particularly illustrated, in the present embodiment, the intermediate layer 3 is formed by overlapping two paper layers formed of the same constituent material. That is, the intermediate layer 3 of the present embodiment has a multilayer structure of two layers. Thus, whether the intermediate layer has a single-layer structure or a multilayer structure is arbitrary depending on the constituent materials and manufacturing equipment used. Further, in the present embodiment, the above-described two paper layers are formed of the same constituent material, but when adopting a multilayer structure, it is arbitrary whether the constituent materials of the respective layers are the same or different. is there.

  In the present embodiment, the front surface layer 2 and the back surface layer 4 are configured by the same constituent material and the same structure. The thicknesses of the surface layer 2 and the back surface layer 4 may be the same or different from each other, but in the present embodiment, the surface layer 2 is formed thinner like a normal liner. .

The basis weights of the front surface layer 2 and the back surface layer 4 may be the same or different, but the tensile strength / elongation or the bending strength characteristics within the layer is 30 to 50 g / m ^2. This is preferable. In the present embodiment, the surface layer 2 is formed with a smaller basis weight as in the case of a normal liner. The basis weight of the intermediate layer 3 is preferably 30 to 110 g / m ^{2 from} the viewpoint of maintaining various strengths (rupture / ring strength) in view of the paper layer configuration.

  Moreover, in this embodiment, the surface layer 2, the back surface layer 4, and the intermediate | middle layer 3 are each adhere | attached through the adhesive agent. In this case, as the adhesive that can be used, natural, PVA, and water-soluble polymer adhesives that are usually used for this type of liner can be used without any particular limitation. A water-dispersible adhesive that exhibits adhesiveness in the drying step can be preferably used. Specifically, corn starch, which is a natural adhesive, is particularly preferable from the viewpoint of cost, coating operability, disaggregation during regeneration, and ease of dispersion.

In addition, the amount of the adhesive applied can be arbitrarily set according to the configuration and use of the surface layer 2, the back layer 4, and the intermediate layer 3 as long as the problem of delamination does not occur. It is preferable to set it as 0.5-5 g / m < ² >.

  Further, the powdered corn starch dispersion solution does not exhibit adhesiveness during coating even when applied to or applied to the adhesive surface between the intermediate layer 3 and the front surface layer 2 or the back surface layer 4, and is a paste produced by heating in the drying process. It is particularly preferable because the adhesiveness can be expressed by the crystallization so that both can be bonded and good adhesive strength between layers can be obtained. The adhesion between the layers by the adhesive is the same in the structure of the intermediate layer 3 composed of multiple layers.

Next, the manufacturing method of the liner of this embodiment is demonstrated.
The liner manufacturing method of the present embodiment includes a base paper composed of at least the front surface layer 2 and the back surface layer 4 and the two intermediate layers 3 as described above, and the surface layer 2 contains a water repellent composition. A method for producing a liner 1 in which a coating layer 5 is formed by applying the applied coating liquid, wherein the oil absorption of the base paper of the liner 1 is reduced or at the same time as the oil absorption is reduced. This is a method of applying a coating liquid containing a liquid composition.

Specifically, the liner of the embodiment shown in FIG. 1 is manufactured through the following four steps.
(1) Formation process of the surface layer 2 and the back surface layer 4 First, a pulp is disperse | distributed to water and a slurry is created. If necessary, other chemicals are added to the obtained slurry and dissolved and mixed. Next, paper making is performed to obtain paper as each layer.
(2) Formation process of the intermediate | middle layer 3 A pulp is disperse | distributed to water and a slurry is created. If necessary, other chemicals are added to the obtained slurry and dissolved and mixed. Next, paper making is performed to obtain paper as the intermediate layer 3.
(3) Paper making process The paper for forming the front surface layer 2 and the back surface layer 4 and the paper for forming the intermediate layer 3 are made together to obtain the liner base paper of this embodiment.
(4) Coating liquid application process The coating liquid 5 containing the water repellent composition is applied on the surface layer 2 of the base paper to form the coating layer 5 to obtain the liner 1.

  As a coating apparatus that can be used in the coating liquid coating step, when applying a coating liquid containing a water repellent composition after reducing the oil absorption of the base paper, a bar coater, a spray shower, A roll bar coater, shim sizer, gate roll coater, etc. are used to reduce the oil absorbency of the base paper and at the same time apply a coating solution containing a water repellent composition. , Shim sizers, gate roll coaters, calendar water doctors, etc. are used.

  The liner of this embodiment can be used as a corrugated cardboard by combining the core paper used for a normal corrugated cardboard. That is, this liner can be used as a cardboard having a three-layer structure formed by sandwiching a corrugated core paper with two liners.

  And according to this liner, since the coating liquid containing a water repellent composition is applied to the surface layer blended with the softwood unbleached kraft pulp (NUKP) used in the present invention, synergistically It is possible to effectively prevent the water repellent composition from penetrating into the base paper and reducing the water repellency.

  Therefore, the cardboard using this liner is excellent in water repellency, and the water repellency does not decrease over time. In addition, this liner is not restrict | limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the meaning of this invention. For example, the prescription which does not use the above-mentioned interlayer adhesive is also included.

  In order to confirm the effect of the liner according to the present invention, the following various samples were prepared, and a test for evaluating the quality of each sample was performed. In addition, in a present Example, the numerical value which shows a mixing | blending, a density | concentration, etc. is a numerical value of solid content or the mass reference | standard of an active ingredient. Moreover, since the pulp, chemical | medical agent, etc. which are shown in a present Example are only examples, it cannot be overemphasized that this invention is not restrict | limited by these Examples, and can be selected suitably.

  35 types of liners according to the present invention (hereinafter referred to as “Example 1” to “Example 35”) and two types of liners (this) Are referred to as “Comparative Example 1” and “Comparative Example 2”).

[Example 1]
Using the following raw materials, in accordance with the following manufacturing method, a liner was obtained in which the base paper was composed of four paper layers, a front surface layer, two intermediate layers, and a back layer.
<Base paper>
-Surface layer A raw material pulp comprising 100% by mass of NUKP was blended with a sizing agent, starch for enhancing internal paper strength, and a sulfuric acid band as internal additives to obtain a raw material pulp slurry for the surface layer. Moreover, the raw material pulp for the surface layer has a kappa value of 70 according to JISP8211, a disintegration freeness of the surface layer of 630 cc, and a disintegration freeness of the surface layer of the disintegrated pulp of the surface layer peeled according to JISP8220. The average fiber length of the disaggregated pulp is adjusted to be 2.20 mm and the Runkel ratio is 1.03.
-Back layer A raw material pulp slurry consisting of 100% by mass of used paper pulp was blended with a sizing agent, starch for enhancing internal paper strength, and a sulfuric acid band as internal additives to obtain a raw material pulp slurry for the back layer.
Intermediate layer A raw material pulp slurry consisting of 100% by mass of waste paper pulp was blended with a sulfuric acid band, starch for enhancing internal paper strength, and a sizing agent as internal additives to obtain a raw material pulp slurry for an intermediate layer.
<Coating fluid>
6% by mass of wax resin (trade name “Ripax A-240” manufactured by Modern Chemical Industries, Ltd.) having a melting point of 52 ° C. and SBR (Nippon A & L Co., Ltd.) having a glass transition temperature (Tg) of −25.0 ° C. A water repellent composition is obtained containing 30.0% by mass of a trade name “Nalstar SR-110” manufactured by the company. Then, this water-repellent composition was mixed with a PVA aqueous solution containing 5% by mass of PVA having a saponification degree of 98 mol% and 54% by mass of water, and the average particle diameter of the wax resin emulsion was 350 nm. Obtain a working solution.
<Creating a liner>
Using the above-described pulp slurry of each layer, after making paper constituting each layer under the manufacturing conditions of a paper making speed of 700 m / min on a reel, a temperature condition of 65 ° C. on a reel, and a slurry pH of 6.0, an adhesive As a result, the layers were combined using a corn starch dispersion solution to obtain a base paper. In this example, for the convenience of the manufacturing equipment used, two paper layers for forming the intermediate layer were produced using the same constituent material, and the obtained two paper layers were bonded together to form the intermediate layer. Is forming.
Next, on the surface layer of the obtained base paper, the coating liquid was applied using a bar coater # 3 (10 to 11 g / m ² ), and then a dryer (manufactured by Yamato Chemical Co., Ltd., constant temperature and constant temperature). The liner (Example 1) was obtained by drying for 1 minute at a temperature in the dryer of 90 ° C. using a container DNG810).

  In addition, Examples 2 to 35 and Comparative Examples 1 and 2 were produced in the same manner as Example 1 except that changes were made as shown in Table 1.

  In Table 1, “fiber length (mm)” means that a sample in a slurry state was prepared from the prepared liner in accordance with JISP8220, and then JAPAN TAPPI No. 52 (2000) is a value obtained by measuring the weight average fiber length. In addition, the fiber length distribution measuring machine FS-100 made from Kayani company was used for the measurement.

  Table 2 shows the results of quality evaluation for all of these Examples and Comparative Examples. This quality evaluation test was performed under environmental conditions of temperature 23 ± 2 ° C. and humidity 50 ± 2% in accordance with JIS-P8111.

  “Water repellency” in Table 2 means that the liner according to each of the produced examples was dried for 1 minute at 90 ° C. in a dryer (Yamato Chemical Co., Ltd., blown constant temperature thermostatic device DNG810), and then JISP8137 Is a value measured based on

  “Water repellency after heating” means that the liner according to each of the produced examples was dried for 1 minute at a temperature of 90 ° C. in a dryer (Yamato Chemical Co., Ltd., blown constant temperature thermostatic device DNG810). The temperature in the dryer (Yamato Chemical Co., Ltd., blown constant temperature thermostatic device DNG810) is 180 ° C. and further dried for 10 minutes, and then measured based on JISP8137.

  The “slip angle (degree)” is a value measured according to the gradient method described in JISP8147 (1994).

  The “slip angle after heating (degree)” means that the sample according to each example having the same dimensions as the sample for which the “slip angle” was measured is a dryer (manufactured by Yamato Chemical Co., Ltd., blower constant temperature thermostat DNG810). ) Is set to 90 ° C. and dried for 1 minute, and then the temperature in the dryer (manufactured by Yamato Chemical Co., Ltd., blown constant temperature thermostatic device DNG810) is set to 180 ° C. and further dried for 10 minutes. ) Is a sliding angle measured by a tilt method measured according to).

From Table 2, the liner according to the present invention, that is, the liner according to Examples 1 to 35, can effectively prevent the water-repellent composition from penetrating into the base paper, and as a result. Even if waste paper pulp, which is advantageous in terms of cost, is mixed, the water-repellent performance does not deteriorate with time or by heating , and a liner having excellent slip resistance can be obtained.

1 Liner 2 Surface layer 3 Intermediate layer 4 Back layer 5 Coating layer

Claims (4)

A liner paper having a base paper comprising at least a front surface layer and a back surface layer,
A coating solution containing a water repellent composition having a mass of 3 to 8 % and a polyvinyl alcohol having a saponification degree of 98.0 to 99.0 mol% and a mass of 5 to 10% on at least the surface layer of the base paper. Having a coating layer coated with
The water repellent composition contains a wax resin having a melting point of 48 to 65 ° C. , and the average particle size of the emulsion is 300 to 600 nm,
Further, the liner layer according to claim 1, wherein the disintegrated pulp of the surface layer which has been separated from the surface layer and disaggregated according to JISP8220 has a kappa value of 50 to 70 measured according to JISP8211. The disaggregated pulp of the surface layer is a conifer kraft pulp manufactured by mechanically beating and pulping with a refiner before or during the continuous selection process and at the outlet of the continuous digester. The liner according to 1.   The disintegrated pulp of the surface layer has a freeness of 500 to 650 cc, an average fiber length of 2.0 to 3.0 mm, and a Runkel ratio of 0.8 to 1.2. Or the liner of Claim 2. The liner according to any one of claims 1 to 3, wherein the water repellent composition further contains a latex having a glass transition temperature of -50 to -15 ° C.

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