JP2016035123A - Tissue paper for decorative board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tissue paper for a decorative board which has a good surface property and a high gravure printability, keeps a concealing property even though being the tissue paper, and can stably exhibit a desired hue in a paper making process for a short period of time.SOLUTION: A tissue paper for a decorative board is formed by coating a coating layer containing a coloring agent and an adhesive as a main component, onto base paper with a density of 0.70-1.00 g/cmwhich is formed by paper making a paper stock containing 20 mass% or more of titanium dioxide as a filler in a raw material pulp containing a pulp fiber prepared to 300-500 ml according to Canadian standard freeness, with a pond-type or transfer-type size pressing coating apparatus. CIELAB coordinates (Lvalue, avalue and bvalue) satisfy relationships of 50≤L≤100, 5≤a≤30 and 10≤b≤40.SELECTED DRAWING: None

Description

  The present invention relates to a thin paper for a decorative board. More specifically, it is excellent in productivity, excellent in concealability and printability, and is suitable for a decorative board to be printed and bonded to a base material such as plywood, particle board, fiber board, etc. Related to tissue paper.

A decorative sheet is a sheet made of thinly sliced wood, or a synthetic resin sheet or synthetic resin coated thin paper on a surface of various substrates such as plywood, particle board, and fiberboard. By sticking, it refers to a plate imparted with cosmetics at the same time as the sealing and surface protection of the substrate. In many cases, the synthetic resin sheet or decorative board base paper used as the decorative sheet is printed with a wood grain pattern to imitate wood.
Depending on the material of the decorative sheet to be bonded and the manufacturing method, the decorative panel is made of natural wood decorative panel (veneer decorative panel), high-pressure melamine decorative panel, low-pressure melamine decorative panel, diallyl phthalate (DAP) decorative panel, polyester decorative panel, chloride There are various types such as vinyl decorative boards and thin paper decorative boards, and they are used as housing members or furniture members.
Since veneer veneer using natural wood is not suitable for mass production, decorative veneer using synthetic resin sheet or base paper for decorative veneer as a veneer sheet is widely used worldwide.
In addition, polyvinyl chloride as a decorative sheet has been used extensively because it is durable and inexpensive. However, in recent years, it tends to be avoided as a cause of generation of chlorine gas, etc. during combustion. Films and thin paper for decorative boards have come to be used.
Note that some decorative boards can be obtained by laminating several base papers impregnated with resin, like a high-pressure melamine decorative board, and then heating and compressing them into a plate shape. As a board, decorative sheet thin paper is pasted on the base material surface of fiberboards such as plywood, particleboard, medium density fiberboard (MDF), etc. having a certain thickness in advance, which does not require resin impregnation or pressing in the subsequent process. However, demand is growing.
In many cases, the decorative sheet thin paper is used after being provided with a printing layer by gravure printing or the like and then attached to a substrate. On top of that, a coating layer of amino alkyd resin, polyurethane resin or the like may be provided as necessary for surface protection.
However, due to problems with the number of processes and costs, there is an increasing demand for decorative sheets that are completed as decorative sheets when the decorative sheet thin paper is pasted without providing the protective layer separately on the decorative sheet thin paper. Yes. When manufacturing such a decorative board, it is necessary that the surface of the thin paper for decorative boards has the suitability as the surface of a decorative board as it is.

The properties necessary for such a decorative sheet thin paper are required to have few white spots at the time of printing such as gravure printing, good ink deposition, and good design reproducibility.
In addition, high concealability, difficulty in fading, strong inter-paper strength, strong surface strength, good dimensional stability, and the like are required.
In particular, as for gravure printing aptitude, in recent years, “non-oak tone” with a light and delicate wood grain pattern tends to be preferred over the so-called “oak tone” decorative board with a relatively dark and distinct wood pattern. It has become.
In such light-color printing, printing defects are conspicuous, and it is a problem whether or not the light-colored portion of the ink called a highlight portion is particularly neat. In addition, there is a problem that minute gloss loss called avatar becomes noticeable.
In addition to the trend of favoring light-colored printing as described above, in recent years there has also been a progress in lowering the basis weight of thin paper for decorative boards. Opacity) is required. In addition, it is also demanded that it does not easily fade so that the cosmetic properties do not deteriorate after it becomes a decorative board.

Various techniques have been proposed to meet the above quality requirements.
Patent Document 1 discloses a decorative board paper in which a resin and a pigment are internally added and further impregnated with a resin liquid. Specifically, it is intended to improve the paper interlaminar strength by pre-adding resin and pigment to the prepared paper material and further impregnating and drying the resin liquid. It was difficult to achieve both strengths.
In Patent Document 2, the tear length is set to 4 km or more, and the L value, a value, and b value of the Lab color satisfy the relationship of 80 <L ≦ 100, −5 ≦ a <2, and −5 ≦ b <10. By controlling this, it is possible to improve the production yield by suppressing the paper breakage during the production while improving the concealment property, to suppress the change in the color of the printed pattern, and to improve the print reproducibility. A decorative board paper is disclosed. Specifically, the pulp material contains a filler, and 90% by mass or more of the entire pulp material is bleached kraft pulp. The pulp material contains 8% by mass or more of titanium dioxide as a filler, and is an ivory type. Although the color tone is adjusted, since the color tone is adjusted by internal addition, the color change loss is large and the production efficiency is insufficient.
In Patent Document 3, a coating material containing a filler and a binder is applied, the resin component in the coating material is infiltrated into the base paper, and this is calendered to improve smoothness, surface strength, concealment and printing gloss. Excellent decorative board coated paper is disclosed. However, the coating amount was as large as 8 to 25 g / m ² , which was insufficient from the viewpoint of economy.

  In other words, the decorative board paper is made to have a wood grain and marble texture efficiently, while being thin, it has sufficient concealability, gravure printing suitability, hue, resistance to fading, and impregnation with melamine resin. The current situation is that it is insufficient.

JP-A-63-190094 JP-A-2005-350788 JP-A-4-314538

Therefore, the present invention has been made based on the circumstances as described above, has good surface properties, high gravure printing suitability, and maintains a concealing property that the base of the plywood is not transparent though it is a thin paper. An object of the present invention is to provide a thin paper for a decorative board that can stably develop a desired color tone in a short time in a papermaking process.

Specifically, the present invention has the following configuration.
[1] Measured according to JIS P 8118: 1998, which was made using a paper stock containing 20% by mass or more of titanium dioxide as a filler to a raw material pulp mainly composed of pulp fibers prepared to 300 to 500 ml of Canadian standard freeness. Cosmetics in which a coated layer mainly composed of a colorant and an adhesive is coated on a base paper having a density of 0.70 to 1.00 g / cm ³ using a pound type or transfer type size press type coating apparatus. Thin paper for board, and CIELAB coordinates (L ^* value, a ^* value, b ^* value) defined in JIS P 8150: 2004 are 50 ≦ L ^* ≦ 100, 5 ≦ a ^* ≦ 30, 10 ≦ b ^* Thin paper for decorative board that satisfies the relationship of ≦ 40.
[2] JAPAN TAPPI paper pulp test method no. The thin paper for decorative boards according to [1], wherein the smoothness measured according to 5-2: 2000 is 30 to 300 seconds.
[3] The thin paper for decorative board according to [1] or [2], wherein the stock contains 0.1 to 2.0% by mass of a sulfuric acid band and 0.1 to 2.0% by mass of a wet paper strength agent. .
[4] The thin paper for decorative board according to any one of [1] to [3], wherein the transfer type size press type coating apparatus is a rod metering size press coater.

  According to the present invention, it is possible to provide a thin paper for a decorative board that has good gravure printing suitability, has high concealment property even though it is a thin paper, and stably expresses a desired color tone in a short time in the paper making process.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  The pulp fibers used to make the thin paper for decorative board of the present invention include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), mechanical pulp (GP, CGP, RGP, TMP, etc.), waste paper pulp It is possible to mix them as appropriate. Waste paper pulp includes DIP and waste products generated in the papermaking process. Considering the uniformity of formation, it is preferable that the blending ratio of LBKP is large. For example, the blending ratio of LBKP and NBKP can be 3: 1 to 10: 0. Moreover, it is possible to mix | blend arbitrary synthetic fibers, a non-wood fiber, etc. as needed.

  The Canadian standard freeness of the pulp fiber used in the present invention needs to be adjusted to 300 to 500 ml. The freeness range is more preferably 300 to 450 ml, particularly preferably 300 to 400 ml. When the Canadian standard freeness exceeds 500 ml, the paper interlayer strength becomes too weak, and the paper delamination occurs when the adhesive tape or the like is adhered to the decorative sheet thin paper for a long period of time. If the Canadian standard freeness is less than 300 ml, the penetrability is lowered and uneven coloring occurs, or the amount of resin impregnation in the subsequent process is insufficient.

Moreover, in this invention, it is preferable that the freeness according to JIS P 8121: 1995 of the disaggregated pulp obtained by disaggregating by the pulp disaggregation method of JIS P 8220: 1998 is 300-600 ml (CSF). . More preferably, the freeness of the disaggregated pulp is in the range of 350 to 500 ml CSF. By setting the freeness of the disaggregated pulp to 300 to 600 ml (CSF), the tensile breaking elongation in the transverse direction during heating can be increased. Moreover, by making the freeness of the disaggregated pulp within the above range, the bonding force between the fibers can be strengthened, and the occurrence of delamination of paper can be suppressed. Furthermore, in the bonding process and the gravure printing process, shrinkage due to hot air drying can be suppressed, and generation of wrinkles and the like can be suppressed.
Furthermore, the air permeability is preferably 30 seconds or less, and more preferably 20 seconds or less. By making the air permeability within the above range, the impregnation property of the melamine resin can be enhanced, and the uniformity of the impregnation and the working efficiency can be enhanced.

  As for the beating method, if a predetermined freeness, weight-weighted average fiber length, fiber length distribution coefficient are obtained, any of beater, Jordan, deluxe finner (DF), double disc refiner (DDR), etc. A beating machine may be used, but it is preferable to adjust the weight-weighted average fiber length and fiber length distribution coefficient by combining viscous beating and cutting beating. In particular, the weight-weighted average fiber length and the fiber length distribution coefficient are adjusted by combining viscous beating using a beating blade with the blade width and groove width of the beating blade adjusted to be small and cutting beating with a larger blade width and groove width. It is preferable. Further, the degree of beating is not particularly limited as long as a predetermined weight-weighted average fiber length and fiber length distribution coefficient can be obtained, but treatment with a freeness of about 300 to 500 ml CSF is preferable in view of suitability for handling thin paper for decorative board.

  In the base paper of the present invention, the weight-weighted average fiber length of the disaggregated pulp obtained by disaggregating the base paper is preferably 0.6 to 2.0 mm, more preferably 0.6 to 1.5 mm. Preferably, it is 0.6-1.0 mm. By setting the weight-weighted average fiber length of the disaggregated pulp within the above range, the bonding area between fibers can be widened and the strength can be maintained, so that occurrence of delamination of paper can be suppressed. It becomes. In addition, by making the weight-weighted average fiber length of the disaggregated pulp within the above range, it is possible to improve the formation, and it is possible to suppress shrinkage due to hot air drying in the bonding process and the gravure printing process. Generation of wrinkles and the like can be suppressed.

  In the present invention, the fiber length distribution coefficient of the disaggregated pulp obtained by disaggregating the base paper is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, and 1.0 to 2.0. More preferably. By setting the fiber length distribution coefficient of the disaggregated pulp within the above range, the bonding area between fibers can be widened and the strength can be maintained, so that occurrence of delamination of paper can also be suppressed. In addition, when the fiber length distribution coefficient of the disaggregated pulp is within the above range, the formation can be improved, and shrinkage due to hot air drying can be suppressed in the bonding process and the gravure printing process. Etc. can be suppressed.

Here, the fiber length distribution coefficient is a numerical value obtained by dividing the weight weighted average fiber length (W) by the number average fiber length (M), and is a value obtained by the following equation.
Fiber length distribution coefficient = weight-weighted average fiber length (W) / number average fiber length (M)
The larger the fiber length distribution coefficient, the wider the fiber length distribution, and the smaller the fiber length distribution coefficient, the narrower the fiber length distribution. The weight-weighted average fiber length and the number average fiber length are those of JAPAN TAPPI Paper Pulp Test Method No. It is a value measured by an optical automatic measurement method defined in 52: 2000.
The weight-weighted average fiber length and the number average fiber length are those of JAPAN TAPPI Paper Pulp Test Method No. It is a value measured by an optical automatic measuring method defined by 52: 2000 (Kayani fiber length measuring instrument [FS-200 type] manufactured by Kayani Automation Co., Ltd.).

  The weight-weighted average fiber length, fiber length distribution coefficient, and freeness of pulp from the above base paper are the weight-weighted average fiber length, fiber length distribution coefficient, and freeness of pulp used when making the base paper. Does not necessarily match. This is because when the base paper is made, some of the fine fibers in the stock come out of the wire mesh or net, and depending on the conditions in the wire part, press part, and dryer part (drying process), the aggregated state of the pulp fibers This is because may change. In addition, in the preparation process until it is sent to the wire part, in order to improve the strength between the paper layers, or to improve the yield and formation, beating or adding various internal additives, May change by adjusting the size and shape of the flocs formed by.

According to the present invention, the raw material pulp containing the pulp fiber as a main component is coated with a colorant and an adhesive as main components on a base paper made using a paper material containing 20% by mass or more of titanium dioxide as a filler. A thin paper for decorative board, which is coated with a coating device of a pound type or transfer type size press method, and has CIELAB coordinates (L ^* value, a ^* value, b ^*) defined in JIS P 8150: 2004 Value) is controlled so that 50 ≦ L ^* ≦ 100, 5 ≦ a ^* ≦ 30, 10 ≦ b ^* ≦ 40, improving the concealment property, good gravure printability, and no inferiority , The paper interlayer strength is excellent.

As the _colorant, TiO 2 -BaO-NiO and _{TiO 2 -Sb 2 O 5 -Cr 2} O 3, yellow-based composite oxide pigments such as TiO ₂ -Sb ₂ O 5 -NiO (calcined pigment), _Fe 2 O Brown complex oxide pigments such as _3- ZnO and Fe ₂ O ₃ —ZnO—Cr ₂ O ₃ , green complex oxides such as TiO ₂ —CoO—NiO—ZnO and CoO—Al ₂ O ₃ —Cr ₂ O ₃ things pigments, blue-based composite oxide pigments such as _{CoO-Al 2 O 3, CuO} -Cr 2 O 3 and _{CuO-Cr 2 O 3 -MnO,} CuO-Fe 2 O 3 -MnO, CuO-Fe 2 O 3 - black-based composite oxide pigments such as cr ₂ O _3, carbon black, chromium oxide, ultramarine, inorganic pigment other than the composite oxide pigments such as ferric oxide, aniline black, phthalocyanine blue, Fast yellow, In addition to organic pigments such as soindolinone yellow, disazo yellow, pyrazolone orange lake red C, brilliant carmine 6B, quinacridone red, and phthalocyanine green, they were finely and stably dispersed in an aqueous medium in advance using a surfactant or resin. Examples of water-dispersed pigment products include C.I. I. Pigment Blue 15: 3B (trade name: “Sandy Super Blue GLL” (pigment content 24%, manufactured by Sanyo Dye)), C.I. I. Pigment Red 146 (trade name: “Sandye Super Pink FBL” (pigment content 21.5%, manufactured by Sanyo Dye)), C.I. I. Pigment Yellow 81 (trade name: “TC Yellow FG” (pigment content: about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.)), C.I. I. Pigment Red 220/166 (trade name: “TC Red FG” [pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.]).

Examples of the colored dye include acid dyes, basic dyes, and direct dyes.
Examples of the acid dye include New Coxin (CI. 16255), Tartrazine (CI. 19140), Acid Blue Black 10B (CI. 20470), Guinea Green (CI. 42085), Brilliant Blue FCF. (CI.42090), Acid Violet 6B (C.I.42640), Soluble Blue (C.I.42755), Naphthalene Green (C.I.44025), Eosin (C.I.45380), Phloxin (C.I. 45410), erythrosin (C.I. 45430), nigrosine (C.I. 50420), acid flavin (C.I. 56205) and the like.

  Examples of basic dyes include chrysoidine (C.I. 11270), methyl violet FN (C.I. 42535), crystal violet (C.I. 42555), malachite green (C.I. 42000), Victoria blue FB ( CI. 44045), rhodamine B (C.I. 45170), acridine orange NS (C.I. 46005), methylene blue B (C.I. 52015) and the like.

  As direct dyes, Congo Red (C.I. 22120), Direct Sky Blue 5B (C.I. 24400), Violet BB (C.I. 27905), Direct Dee Black EX (C.I. 30235), Kaya Las Black G Conch (C.I. 35225), Direct Fast Black G (C.I. 35255), Phthalocyanine Blue (C.I. 74180) and the like.

Among the colorants, the colorants used in the present invention include brown complex oxides such as Fe ₂ O ₃ —ZnO, Fe ₂ TiO ₄ —Al ₂ O _3, and Fe ₂ O ₃ —ZnO—Cr ₂ O ₃ . Pigments, black complex oxide pigments such as CuO—Cr ₂ O ₃ , CuO—Cr ₂ O ₃ —MnO, CuO—Fe ₂ O ₃ —MnO, CuO—Fe ₂ O ₃ —Cr ₂ O ₃ , Zn, Sn , Ti oxide composite pigment (orange), carbon black, chromium oxide, ferric oxide, aniline black, pyrazolone orange lake red C, brilliant carmine 6B, quinacridone red, yellow ferric oxide, yellow titanium oxide (mainly Ingredients: Titanium oxide and Ni, Sb oxide composite), Nippon Kayaku Levercell Orange, Yellow, Kayafect Yellow, etc. Azo direct dyes, and the like are preferable, such as Direct paper yellow.

  In the present invention, a water-soluble adhesive or a water-dispersible adhesive can be used alone or in combination as the adhesive used for the coating layer coating liquid provided on the base paper. The blending ratio in the case of using a water-soluble adhesive and a water-dispersible adhesive in combination is not particularly limited.

  Examples of the water-soluble adhesive include starch derivatives such as oxidized starch, esterified starch, etherified starch, dextrin and cold water soluble starch, proteins such as casein, soy protein, and synthetic protein, cellulose derivatives such as hydroxyethyl cellulose, Polyvinyl alcohol, modified products thereof, and the like can be used. Among them, starch derivatives that provide good fluidity of the coating liquid are preferable.

  Water-dispersible adhesives include styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer, conjugated diene copolymer latex such as styrene-methyl methacrylate-butadiene copolymer latex, alkyl acrylate ester or methacrylic ester. An acrylic polymer latex such as a polymer or copolymer latex of an acid alkyl ester, a vinyl polymer latex such as an ethylene-vinyl acetate copolymer, or a polymer containing a functional group such as a carboxyl group. Examples thereof include a polymer or copolymer latex modified with a monomer.

  In the present invention, the auxiliary agent used in the coating layer coating liquid includes one or more kinds of dispersants, antifoaming agents, preservatives, viscosity improvers, lubricants, water-proofing agents, and the like. It can be appropriately selected and used.

The solid content concentration of the coating layer coating liquid used in the present invention is preferably in the range of 1 to 20% by mass, and in the range of 2 to 10% by mass in consideration of adjustment of the coating amount and operability. More preferably.
In the present invention, a colored coating layer is provided by external addition. For this reason, compared with the case where a colorant is added by internal addition, the colorant amount can be reduced by about 10 to 40% by mass. In addition, when the L ^* value, a ^* value, and b ^* value specified by the present invention are internally added, it takes a long time until the color disappears from the papermaking system when switching from the product of the present invention to the next product. And a large amount of product loss occurs.

  The titanium dioxide contained in the base paper of the present invention preferably has an average particle size of 5 to 500 nm, more preferably 10 to 400 nm, and still more preferably 20 to 300 nm. By making the average particle diameter of titanium dioxide within the above range, the concealability of the thin paper for decorative board can be enhanced.

The content of titanium dioxide needs to be 20% by mass or more based on the total mass of the base paper. More preferably, it is 20-45 mass%, More preferably, it is 20-39.5 mass%, Most preferably, it is 30-39.5 mass%. In addition, it is preferable to set it as 1-150 mass parts with respect to 100 mass parts of pulp amounts, and, as for the addition amount of the titanium dioxide to a pulp slurry, it is more preferable to set it as 40-120 mass parts.
Titanium dioxide has anatase type and rutile type as crystal types. In the present invention, either type of titanium dioxide can be used, but rutile type is preferred from the viewpoint of light resistance when used as a decorative board. Of these, rutile type titanium dioxide doped with antimony is particularly preferable.

Here, the rutile type titanium dioxide doped with antimony is rutile type titanium dioxide in which antimony is contained on the surface of the rutile type titanium dioxide.
Specifically, for example, on the surface of titanium dioxide particles as described in JP-A-2008-81578, JP-A-2007-9156, JP-A-9-48931, JP-A-2-214783, and the like. Titanium dioxide having an anhydrous inorganic compound coating layer containing at least dense anhydrous silica and a hydrous inorganic compound coating layer which is a hydrous oxide of at least one element selected from silicon, zirconium, titanium, tin, antimony and aluminum in this order A pigment etc. can be mentioned. Specific examples of rutile titanium dioxide doped with antimony include titanium dioxide (trade name: “R-3L”) manufactured by Sakai Chemical Co., Ltd.

In the present invention, it is preferable that the base paper contains a wet paper strength enhancer. Examples of the wet paper strength enhancer include polyamide epichlorohydrin resin, melamine formaldehyde resin, urea formaldehyde resin, vegetable gum, latex, polyethyleneimine and the like. In particular, the polyamide epichlorohydrin resin can be used in a wide pH range, and a high wet paper strength can be obtained with a low addition amount. Therefore, it can be preferably used as the wet paper strength enhancer of the present invention.
In combination with the wet paper strength enhancer, paper strength enhancers such as glyoxal, gum, guar gum, mannogalactan, polyethyleneimine, polyacrylamide resin, polyvinyl alcohol, starch, carboxymethylcellulose, urea resin and the like may be used.

  The content of the wet paper strength enhancer is preferably 0.1 to 2.0% by mass, more preferably 0.1 to 1.8% by mass, based on the total mass of the base paper. It is more preferable that it is 3-1.5 mass%. The amount of the wet paper strength enhancer added to the pulp slurry is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the pulp. More preferably, it is 0.1-1 mass part. By making the addition amount of the wet paper strength enhancer within the above range, the processability when impregnating melamine can be improved.

  Examples of the filler internally added to the base paper in the present invention include, in addition to the above-mentioned titanium dioxide, for example, kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, gypsum, calcined kaolin, white carbon, amorphous Examples include inorganic pigments such as silica, delaminated kaolin, diatomaceous earth, magnesium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, and organic pigments such as urea / formalin resin particles and fine hollow particles. be able to. In addition, fillers contained in waste paper and waste paper can be reused.

  Examples of the pH adjuster used in the production of the base paper in the present invention include sulfuric acid band, aluminum chloride, sulfuric acid, hydrochloric acid, sodium aluminate, basic aluminum compound, sodium hydroxide (sodium hydroxide), potassium hydroxide, ammonia, various kinds And alkaline compounds such as primary, secondary and tertiary amines. Of these, a sulfuric acid band is preferred from the viewpoint of versatility and economy.

The content of the sulfuric acid band (pH adjusting agent) is preferably 0.1 to 2.0% by mass, preferably 0.1 to 1.8% by mass, based on the total mass of the base paper. It is preferable that it is 0.3-1.5 mass%. The addition amount of the sulfuric acid band (pH adjuster) to the pulp slurry is preferably 0.1 to 5 parts by mass, and preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the pulp. More preferably, the content is 0.1 to 1 part by mass. By making the addition amount of the sulfuric acid band (pH adjusting agent) within the above range, the processability when impregnating melamine can be improved.

  In the present invention, in addition to pulp and fillers, internal additives for papermaking such as an internal sizing agent, anionic, nonionic, cationic or amphoteric retention improver, freeness improver are required in the base paper. It can be added depending on. Specific examples of the internal sizing agent include rosin, alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, petroleum resin, and the like.

In the production process of the base paper of the present invention, titanium dioxide and wet paper strength enhancer are continuously added. Adding continuously is a method of adding a wet paper strength enhancer and titanium dioxide before or after dilution with white water without any gap. The wet paper strength enhancer and titanium dioxide may be added continuously before diluting with white water or may be added continuously after diluting with white water, but are preferably added continuously after diluting with white water. The wet paper strength enhancer and titanium dioxide may be added almost simultaneously either before or after dilution with white water.
Specifically, when the wet paper strength enhancer and titanium dioxide are continuously added, the difference in the addition time of the wet paper strength enhancer and titanium dioxide is preferably within 5 minutes, and within 3 minutes. Is more preferable, and it is still more preferable that it is within 1 minute.
In the present invention, by adding the titanium dioxide and the wet paper strength enhancer as described above, the formation of the base paper can be improved and the wet paper strength can be improved.

  In the present invention, as the base paper, a known wet paper machine, for example, a long paper machine, a gap former type paper machine, a circular paper machine, a short paper machine, or the like can be appropriately selected. Next, the formed paper layer is conveyed with felt and dried with a dryer. There is no problem even if a multi-stage cylinder dryer is provided as pre-dryer equipment before drying the dryer.

  In the present invention, the temperature of the dryer hot air is preferably in the range of 100 to 400 ° C, preferably in the range of 150 to 300 ° C. By setting the temperature of the hot air within the above range, water vapor generated between the surface of the dryer and the paper can be uniformly and rapidly evaporated. Further, the smoothness of the surface can be kept good without reducing the strength of the pulp.

  Also, in order to prevent the condensation of water vapor generated in the dryer hood, to improve thermal efficiency, and to prevent the occurrence of avatar (fine gloss loss), at least one step of blowing hot air and sucking hot air containing water vapor is performed at least once Do. Usually, proper moisture is required for the paper to stick to the dryer, and its moisture range is 45-65%. By setting the moisture range to the appropriate range, the drying process can be performed smoothly.

  Even if the paper has adequate moisture to be attached to the dryer, the water vapor present between the paper and the dryer may be unevenly evaporated in the drying process, resulting in avatars. For this reason, it is necessary to uniformly and promptly remove moisture from the paper adhered to the dryer. Therefore, in the present invention, it is preferable to perform the step of sucking hot air containing water vapor at least once.

The basis weight of the decorative sheet thin paper in the present invention is generally about 30 to 100 g / m ² , and can be appropriately set according to the use and purpose, but 31 to 90 g / m ² is preferable. 35 to 85 g / m ² is more preferable. If the basis weight exceeds 100 g / m ² , the mass is too large, and there is a problem in terms of handling suitability and economy. Moreover, there exists a possibility that sufficient intensity | strength cannot be provided when basic weight is less than 30 g / m < ² >.

Moreover, the base paper of the thin paper for decorative board of the present invention needs to control the density measured according to JIS P 8118: 1998 to 0.70 to 1.00 g / cm ³ . By setting the density to 0.70 to 1.00 g / cm ³ , it is possible to give the decorative sheet thin paper a certain degree of cushioning and appropriate penetrability, and to perform colorant coating and gravure printing well. It becomes possible. A preferable density range is 0.75 to 0.95 g / cm ³ , and particularly preferably 0.80 to 0.90 g / cm ³ .

  In the present invention, as a coating apparatus for forming a coating layer on a base paper, in consideration of productivity, quality such as high-speed coating suitability, paper-breaking prevention effect, and the like, a pound-type size press method or a transfer-type size press An apparatus of a method is mentioned. The transfer-type size press type coating device here is a device that applies a coating material for a colored coating layer to a base paper by a pre-measuring method, and is a gate roll coater composed of two or more rolls and an applicator roll. , A rod metering size press coater that measures the paint on the applicator roll with a winding bar or rod, and a blade metering size press coater that measures with a blade. Productivity by high-speed coating among these coating devices In this respect, it is more preferable to use a rod metering size press coater. In addition, although the manufacturing apparatus of the thin paper for decorative boards of this invention may be an on-machine system or an off-machine system, an on-machine system is preferable from a viewpoint of production efficiency.

  When a rod metering size press coater is used, a rod with a smooth surface, a grooved rod, a wire wire winding rod, etc. can be used as the rod. preferable. The diameter of the rod having a smooth surface is preferably 10 to 50 mm. This is because if the rod diameter is less than 10 mm, the quality of the coated surface may be inferior, and even if it exceeds 50 mm, the quality of the coated surface does not change, so it is not necessary to increase the quality.

  As the material of the rod holder used in the rod metering size press coater, rubber, polyurethane, polyethylene and the like are generally used. In the present invention, it is preferable to use a polyethylene material. This is because the polyethylene material is particularly excellent in wear resistance among the above materials.

  In addition, it does not specifically limit as a method of drying the coating liquid for coating layers, Various systems, such as vapor | steam drying, gas heater drying, electric heater drying, and infrared heater drying, are employable.

The absolute dry coating amount of the coating layer provided on the base paper is 0.1 to 7.5 g / m ² , preferably 0.5 to 6.0 g / m ² per side. If the coating amount is less than 0.1 g / m ² , the desired hue may not be obtained. In addition, when the coating amount exceeds 7.5 g / m ² , operational troubles such as misting may occur, and coating unevenness is likely to occur during coating.

In the decorative sheet thin paper of the present invention, after forming a coating layer on the base paper, smoothing is performed in various calendar devices, such as a super calendar, soft calendar, gloss calendar, Conventionally known calendar devices such as a compact calendar, a mat super calendar, and a mat calendar are appropriately used.
As the calendar finishing conditions, the temperature of the rigid roll, the calendar pressure, the number of nips, the roll speed, the moisture before the calendar, and the like are appropriately selected according to the required quality. The material of the calendar apparatus to be used is a roll whose surface is mirror-finished with a metal or a hard chrome plating on the surface of the rigid roll. As the elastic roll, a roll formed of a resin roll such as urethane resin, epoxy resin, polyamide resin, phenol resin, or polyacrylate resin, cotton, nylon, aramid resin, or the like is appropriately used.
Among them, the soft calender can set the heat resistance temperature of the surface of the synthetic resin roll higher than that of the cotton roll, and the temperature of the paired metal roll (chilled roll) should be processed at a high temperature (50 to 150 ° C). When the same smoothness is targeted, the treatment linear pressure can be set lower than that of the super calendar, which is a preferable mode. Although the processing conditions depend on the calendar to be employed, the linear pressure is generally 10 to 400 kgf / cm, more preferably 10 to 200 kgf / cm.
In addition, it is also possible to use a suitable combination of a water coating device, an electrostatic humidifier, a steam humidifier, and the like for humidity control and humidification of the decorative sheet thin paper after finishing with a calendar.

The JAPAN TAPPI paper pulp test method No. of the thin paper for decorative board of the present invention produced as described above. It is preferable to control the smoothness (Oken method) measured according to 5-2: 2000 to 30 seconds or more. Usually, a decorative sheet thin paper is printed with a single color, a wood grain pattern, an abstract pattern or the like by gravure printing. It is generally known that the halftone dot reproducibility of gravure printing depends on the smoothness of the printed paper surface, and that the halftone dot reproducibility is improved when the smoothness is increased. By setting the smoothness to 30 seconds or more, the finish of gravure printing can be improved. In addition, the range of preferable smoothness is 30 to 300 seconds, Most preferably, it is 50 to 300 seconds.

  The thin paper for decorative board of the present invention is characterized in that it has a sufficient concealing property even if it is thin. Specifically, the paper thickness of the thin paper for decorative board of the present invention is preferably 50 to 200 μm, more preferably 60 to 180 μm, and further preferably 70 to 150 μm. By making the paper thickness of the decorative sheet thin paper within the above range, the printability of the decorative sheet thin paper can be enhanced, and the state of being bonded to the decorative board can be kept good.

The thin paper for decorative board of the present invention has an L ^* value, a ^* value, and b ^* value of CIELAB coordinates defined in JIS P 8150: 2004 of 50 ≦ L ^* ≦ 100, 5 ≦ a ^* ≦ 30, 10 ≦. Since the control is performed so as to satisfy the relationship of b ^* ≦ 40, it is easy to produce a texture such as wood grain or marble, which greatly contributes to improvement of production efficiency.

In the present invention, the interlaminar strength of the decorative sheet thin paper is preferably 50 N / m or more, more preferably 55 N / m or more, and particularly preferably 60 N / m or more.
When the strength between paper layers is less than 50 N / m, it becomes easy to peel off between paper layers when it is peeled off after sticking a commonly used adhesive tape, etc., and it is pasted onto a substrate such as particle board and used as a decorative board. Not suitable for Further, when the decorative board is processed, there is a possibility that peeling between the paper layers of the thin paper for decorative board from the cross section of the decorative board may occur.
As described above, by controlling the freeness, weight-weighted average fiber length, and fiber length distribution coefficient of the disaggregated pulp of the decorative sheet thin paper, without changing the basis weight or density of the decorative sheet thin paper, Physical properties such as bond strength can be satisfied.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these. In addition, the numerical value which shows a mixing | blending, a density | concentration, etc. is a numerical value of the solid content or the mass reference | standard of an active ingredient.

<Example 1>
In 400 ml of Canadian Standard Freeness pulp slurry made of LBKP, 0.5% sulfuric acid band, 0.5% wet paper strength agent (trade name: “WS4024”, manufactured by Seiko PMC) After 40% of rutile type titanium dioxide doped with antimony (trade name: “R-3L”, manufactured by Sakai Chemical Industry Co., Ltd.) was added and fixed, the paper was made with a long paper machine at a papermaking concentration of 1.0%. . The density of the base paper before coating was 0.80 g / cm ³ . Using an on-machine gate roll coater, 49 parts by weight of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “Levercell Orange WS-” N ", manufactured by Nippon Kayaku Co., Ltd.) 1% by weight and oxidized starch (trade name:" Oji Ace A ", manufactured by Oji Corn Starch Co., Ltd.) 50% by weight of 3% mixed solution with a dry weight of 3.0 g / It was applied m ² and made like. Subsequently, the thin paper for decorative board of the present invention was prepared by calendaring and smoothing. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured in accordance with 5-2: 2000 is 95 seconds, and the Oken type air permeability is 18 seconds. The coating amount of the colorant alone is 1.5 g / m ² in terms of dry mass.

<Example 2>
In the production of thin paper for decorative board, in an on-machine gate roll coater, 47 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ "Levercell Orange WS-N" (made by Nippon Kayaku Co., Ltd.) 3 parts by mass and oxidized starch (trade name: "Oji Ace A", made by Oji Cornstarch Co., Ltd.) A thin paper for decorative board was prepared in the same manner as in Example 1 except that the coating was applied at 3.0 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured in accordance with 5-2: 2000 is 75 seconds, and the Oken type air permeability is 17 seconds.

<Example 3>
In the production of thin paper for decorative board, 40 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ Levercell Orange WS-N "(manufactured by Nippon Kayaku Co., Ltd.) 10 parts by mass and oxidized starch (trade name:" Oji Ace A ", manufactured by Oji Cornstarch Co., Ltd.) 50 parts by mass A 3% mixture is applied in a dry mass. A thin paper for decorative board was prepared in the same manner as in Example 1 except that the coating was applied at 3.0 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 102 seconds, and the Oken type air permeability is 17 seconds.

<Example 4>
In the production of thin paper for decorative board, in an on-machine gate roll coater, 49 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ Levercell Orange WS-N "(manufactured by Nippon Kayaku Co., Ltd.) 1 part by weight and oxidized starch (trade name:" Oji Ace A ", made by Oji Cornstarch Co., Ltd.) 50 parts by weight 3% mixed liquid with a coating weight of dry mass A thin paper for decorative board was prepared in the same manner as in Example 1 except that the coating was applied at 2.0 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured in accordance with 5-2: 2000 is 120 seconds, and the Oken type air permeability is 13 seconds.

<Example 5>
For the production of decorative sheet thin paper, the same as in Example 1, except that 24% of rutile titanium dioxide doped with antimony (trade name: “R-3L”, manufactured by Sakai Chemical Industry Co., Ltd.) was added. Tissue paper was made. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 82 seconds, and the Oken type air permeability is 29 seconds.

<Example 6>
In the production of the decorative sheet thin paper, the decorative sheet thin paper was prepared in the same manner as in Example 1 except that the press linear pressure was lowered to make paper and the density as the base paper before coating was 0.70 g / cm ³ . . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured in accordance with 5-2: 2000 is 115 seconds, and the Oken type air permeability is 19 seconds.

<Example 7>
In the production of the decorative sheet thin paper, the decorative sheet thin paper was prepared in the same manner as in Example 1 except that the press linear pressure was increased to make paper, and the density of the base paper before coating was 0.90 g / cm ³ . . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 162 seconds, and the Oken type air permeability is 20 seconds.

<Example 8>
In the production of thin paper for decorative board, in an on-machine gate roll coater, 49 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ Levercell Orange WS-N ”(manufactured by Nippon Kayaku Co., Ltd.) 1 part by weight and styrene copolymer latex (trade name:“ A6160 ”, manufactured by Asahi Kasei Co., Ltd.) 50% by weight 3% mixed liquid is dried A decorative sheet thin paper was prepared in the same manner as in Example 1 except that the coating weight was 3.0 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 96 seconds, and the Oken type air permeability is 20 seconds.

<Example 9>
The decorative sheet thin paper was prepared in the same manner as in Example 1 except that 350 ml of pulp slurry of Canadian Standard Freeness made of LBKP was used in the preparation of the decorative sheet thin paper. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 101 seconds, and the Oken type air permeability is 22 seconds.

<Example 10>
In the production of thin paper for decorative board, 37 parts by mass of azo direct dye (trade name: “Kayafect Yellow AW”, manufactured by Nippon Kayaku Co., Ltd.) and on-machine gate roll coater and azo direct dye (trade name: “Lever” Cell orange WS-N "(manufactured by Nippon Kayaku Co., Ltd.) 13 parts by mass and oxidized starch (trade name:" Oji Ace A ", Oji Cornstarch Co., Ltd.) 50 parts by mass 0.4% mixed liquid is dried. A thin paper for decorative board was prepared in the same manner as in Example 1 except that it was applied so as to have a mass of 0.5 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 88 seconds, and the Oken type air permeability is 11 seconds.

<Comparative Example 1>
In the production of the decorative sheet thin paper, a decorative sheet thin paper was prepared in the same manner as in Example 1 except that the on-machine gate roll coater was used for water coating. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 100 seconds, and the Oken type air permeability is 12 seconds.

<Comparative Example 2>
In the production of thin paper for decorative board, 50 parts by mass of iron sesquioxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and oxidized starch (trade name: “Oji Ace” were used on an on-machine gate roll coater. A ", manufactured by Oji Cornstarch Co., Ltd.) A thin paper for decorative board was prepared in the same manner as in Example 1 except that 50% by mass of a 1% mixed solution was applied so that the coating amount was 0.5 g / m ² in terms of dry mass. did. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 77 seconds, and the Oken type air permeability is 12 seconds.

<Comparative Example 3>
In the production of thin paper for decorative board, in an on-machine gate roll coater, 49 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ Levercell Orange WS-N ”(manufactured by Nippon Kayaku Co., Ltd.) 1 part by weight and oxidized starch (trade name:“ Oji Ace A ”, manufactured by Oji Cornstarch Co., Ltd.) A decorative sheet thin paper was prepared in the same manner as in Example 1 except that it was applied at a dry mass of 0.5 g / m ² . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 104 seconds, and the Oken type air permeability is 13 seconds.

<Comparative example 4>
In the production of the decorative sheet thin paper, the decorative sheet thin paper was prepared in the same manner as in Example 1 except that the press line pressure was increased to make paper, and the density of the base paper before coating was 1.05 g / cm ³ . The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 182 seconds, and the Oken type air permeability is 33 seconds.

<Comparative Example 5>
The decorative sheet thin paper was prepared in the same manner as in Example 1 except that 300 ml pulp slurry of Canadian Standard Freeness made of LBKP was used. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 110 seconds, and the Oken type air permeability is 30 seconds.

<Comparative Example 6>
A decorative board was prepared in the same manner as in Example 1 except that 19% of rutile type titanium dioxide doped with antimony (trade name: “R-3L”, manufactured by Sakai Chemical Industry Co., Ltd.) was added in the preparation of the thin paper for the decorative board. Tissue paper was made. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 74 seconds, and the Oken type air permeability is 70 seconds.

<Comparative Example 7>
In the production of thin paper for decorative board, 98 parts by mass of yellow ferric oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) and an azo-based direct dye (trade name: “ Levercell Orange WS-N "(manufactured by Nippon Kayaku Co., Ltd.) Similar to Example 1 except that 2 parts by mass of a 1.0% mixed solution was applied so that the coating amount was 1.5 g / m ² by dry mass. Thus, a thin paper for a decorative board was prepared. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 96 seconds, and the Oken type air permeability is 15 seconds. In addition, roll contamination due to the detachment of the colorant occurred.

<Comparative Example 8>
In the production of thin paper for decorative board, yellow iron oxide (trade name: “DP-1056”, manufactured by Dainichi Seika Kogyo Co., Ltd.) so that the CIELAB coordinates defined in JIS P 8150: 2004 are the same as those in Example 1. Example 1 except that 98 parts by mass and an azo-based direct dye (trade name: “Levercel Orange WS-N”, Nippon Kayaku Co., Ltd.) 2 parts by mass of a 3.0% mixed solution were added internally. Thus, a thin paper for a decorative board was prepared. The resulting thin paper for decorative board has a moisture conditioning basis weight of 82 g / m ² , JAPAN TAPPI paper pulp test method no. The Oken type smoothness measured according to 5-2: 2000 is 102 seconds, and the Oken type air permeability is 14 seconds. The yield of the internally added colorant was 56%. The yield of the colorant was calculated by dividing the quantitative value of iron oxide by an X-ray fluorescence analyzer by the addition amount.

<Evaluation of thin paper for decorative board>
The obtained thin paper for decorative boards was evaluated by the following method.

[ash(%)]
Ash content was measured in accordance with “Paper, paperboard and pulp-ash content test method—525 ° C. combustion method” described in JIS P 8251 (2003).

[L ^* , a ^* , b ^* , opacity]
L ^* , a ^* , and b ^* were measured according to JIS P 8150, and the opacity was measured according to JIS P 8149 using a spectral whiteness colorimeter (manufactured by Suga Test Instruments Co., Ltd., model SC-10WN type). .

[Evaluation of concealment]
Mangle roll was used to impregnate water-soluble melamine resin (trade name: “Nikaresin S260”, manufactured by Nippon Carbide Co., Ltd.) to 20% by mass with respect to the thin paper for decorative board, and dried at 95 ° C. for 10 minutes. Impregnated paper was obtained.
Melamine impregnated paper was placed on a black iron plate, and the black transparency of the base was visually evaluated.
◯: The base black is hardly transparent and the paper does not look black.
Δ: The base black is slightly transparent, and the paper looks slightly blackish.
×: The black transparency of the base is strong, and the paper looks blackish.

[Evaluation of uneven coloring]
The coloring unevenness of the thin paper for decorative board was visually evaluated.
○: No unevenness and no problem △: There is a slightly lightly colored part ×: There are many lightly colored parts and there is a problem in appearance

[Evaluation of impregnation]
A thin paper for decorative board was floated on a 55% aqueous solution of a water-soluble melamine resin (trade name: “Nikaresin S260”, manufactured by Nippon Carbide Corporation), and the time until the resin penetrated into all layers was evaluated according to the following criteria.
Less than 20 seconds: good resin impregnation 20 seconds or more: poor resin impregnation, not suitable for practical use

[Gravure printing aptitude evaluation]
The base paper for decorative board is printed with water-based ink (trade name: “PIO-W97 Black”, manufactured by Dainichi Seika Co., Ltd.) using a gravure printing tester (PM9004GP, manufactured by SMT). Amount) was visually evaluated.
○: Almost no white spots Δ: Some white spots ×: Many white spots

[Operability evaluation]
Judgment was made comprehensively based on the contamination of the cylinder dryer, paper roll, etc., the yield of the colorant, and the time taken for switching.
○: No problem in operation △: Dirt, yield, switching loss, etc. are low and operation is difficult ×: Operation not possible

As shown in Table 1 and Table 2, the decorative sheet thin papers of the present invention produced in Examples 1 to 10 have good impregnation properties and high concealment properties, and provide a desired color tone in a short time in the papermaking process. It can be expressed stably.
On the other hand, the thin paper for decorative board of Comparative Examples 1 to 8 has insufficient characteristics with respect to the characteristics comprehensively required for decorative board applications.

Claims (4)

The density measured according to JIS P 8118: 1998, which was made using a paper stock containing 20% by mass or more of titanium dioxide as a filler in a raw pulp mainly composed of pulp fibers prepared to 300 to 500 ml of Canadian standard freeness. Thin paper for decorative board, in which a coating layer mainly composed of a colorant and an adhesive is applied to a base paper of 0.70 to 1.00 g / cm ³ using a coating apparatus of a pound type or transfer type size press system. The CIELAB coordinates (L ^* value, a ^* value, b ^* value) specified in JIS P 8150: 2004 are 50 ≦ L ^* ≦ 100, 5 ≦ a ^* ≦ 30, 10 ≦ b ^* ≦ 40. A thin paper for a decorative board characterized by satisfying the above relationship. JAPAN TAPPI paper pulp test method no. The thin paper for decorative board according to claim 1, wherein the smoothness measured according to 5-2: 2000 is 30 to 300 seconds. The decorative board according to claim 1 or 2, wherein the paper stock contains 0.1 to 2.0% by mass of a sulfuric acid band and 0.1 to 2.0% by mass of a wet paper strength agent. Tissue paper. The thin paper for decorative board according to any one of claims 1 to 3, wherein the transfer type size press type coating apparatus is a rod metering size press coater.