JP2015059291A - Decorative laminate original paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide decorative laminate original paper which is used in melamine decorative laminates and has consealability, weather resistance and sufficient tensile strength.SOLUTION: Decorative laminate original paper is based on wood pulp, contains rutile-type titanium dioxide doped with antimony in a content of the antimony-doped rutile-type titanium oxide of 15 mass% or higher and lower than 39.5 mass% relative to the total weight of the decorative laminate original paper, and the total ash content of the decorative laminate original paper is lower than 39.5 mass%.

Description

  The present invention relates to a decorative board base paper suitable for use as an interior material for building materials and furniture. Specifically, the present invention relates to a decorative board base paper that is impregnated with a melamine resin and used as a decorative layer, and is excellent in concealability and weather resistance.

  Decorative boards are widely used as interior materials for building materials and furniture. A decorative board is a laminate of decorative sheets on the surface of various base materials such as plywood, particle board, and fiberboard. It has been granted. There are various types of decorative boards such as natural wood decorative boards (veneer decorative boards), melamine decorative boards, diallyl phthalate (DAP) decorative boards, polyester decorative boards, vinyl chloride decorative boards, and thin paper decorative boards. It is classified according to the material and manufacturing method of the sheet.

  Among decorative panels, melamine decorative boards have high surface hardness, excellent stain resistance, wear resistance, and heat resistance, and are used where durability of furniture, top plates, tables, and the like is required. A melamine decorative board is obtained by sticking a decorative base paper impregnated with a melamine resin to a core substrate. As the core base material, a fiber board (particle board or MDF) or a plastic board formed by laminating kraft paper impregnated with phenolic resin or melamine resin and laminating at high temperature and high pressure is used. it can. In many cases, the decorative board paper laminated on the surface is bonded to a base material after a printing layer is provided by gravure printing or the like.

  Conventionally, as a decorative sheet, a sheet obtained by thinly slicing natural wood, a synthetic resin sheet such as a vinyl chloride resin film, or a decorative board sheet coated and impregnated with a synthetic resin has been used. Among them, a synthetic resin sheet such as a vinyl chloride resin film has been widely used because it has an advantage of excellent processability and printability. On the other hand, a synthetic resin sheet such as a vinyl chloride resin film has a problem that a load on the environment is large because harmful chlorine-based gas is generated during combustion. For this reason, in recent years, decorative board base paper based on paper has been used as a substitute material for vinyl chloride resin film. In addition, the decorative board base paper which used paper as the base material is used also for the melamine decorative board mentioned above.

However, since the decorative sheet base paper made of paper has a smaller elongation at break than the vinyl chloride resin film, there is a drawback that the decorative sheet base paper is easily broken in the process of attaching to a core substrate or the like. In particular, it is not suitable for bending processes that require stretching of decorative board paper, such as V-cut processing for bending a flat plate once bonded to a flat plate, and lapping processing for bonding to the surface of an adherend substrate having irregularities. there were.
As methods for solving these problems, Patent Documents 1 and 2 disclose a method in which a paper base material made of wood pulp or the like is impregnated with a solution-like synthetic resin to impart elongation. Patent Document 3 discloses a method of imparting elongation by using a paper before resin impregnation having a length weighted average fiber length of 2 mm or more.

  Moreover, the decorative layer base paper laminated | stacked on the surface may be provided with a printing layer by gravure printing etc. In this case, the decorative board base paper is required to have concealability for concealing the core substrate in addition to having printability. As a method of improving the concealment property, a method of making titanium oxide into decorative board base paper has been practiced. For example, Patent Document 4 discloses a decorative base paper containing titanium dioxide.

JP 56-44652 A Japanese Patent Laid-Open No. 10-6446 JP-A-9-67787 JP 2011-106073 A

  As described above, the decorative board base paper containing titanium oxide can improve the concealability to some extent. However, the concealment performance is not sufficient, and further improvement has been demanded. On the other hand, it is conceivable to increase the content of titanium oxide in order to improve the concealing property. However, if the content of titanium oxide is increased, the tensile strength of the decorative board base paper is weakened, which is a problem. In particular, when the decorative board base paper is subjected to V-cut processing or lapping processing, it is required to have sufficient tensile strength, and therefore it is important to have excellent tensile strength.

  Further, when a decorative base paper containing titanium oxide is impregnated with a melamine resin, there is a problem that the melamine resin is discolored when exposed to light for a long period of time. When the melamine resin is discolored, the design of the melamine decorative board is remarkably deteriorated, which is a problem.

  Therefore, in order to solve such problems of the prior art, the present inventors are a decorative board base paper used for a melamine decorative board, which has a concealing property and weather resistance, but has a sufficient tensile strength. The study was advanced with the aim of providing the base paper. In addition, investigations were made for the purpose of obtaining decorative board base paper that does not impair the impregnation of melamine resin.

As a result of diligent studies to solve the above problems, the present inventors have added rutile type titanium oxide doped with antimony to a decorative board base paper mainly composed of wood pulp, and thereby obtained rutile type titanium oxide. It has been found that the concealability and weather resistance can be improved by prescribing the content and total ash content. Furthermore, the present inventors have found that the decorative board base paper having the above configuration has sufficient tensile strength, and has completed the present invention.
Specifically, the present invention has the following configuration.

[1] A decorative base paper comprising wood pulp as a main component, comprising rutile titanium oxide doped with antimony, and the content of the rutile titanium oxide doped with antimony is based on the total mass of the decorative base paper 15% by mass or more and less than 39.5% by mass, and the total ash content of the decorative board base paper is less than 39.5% by mass.
[2] The makeup according to [1], wherein the content of the antimony-doped rutile titanium oxide is 20% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper. Board base paper.
[3] The content of the rutile-type titanium oxide doped with antimony is 30% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper [1] or [2] The decorative board base paper described in 1.
[4] JAPAN TAPPI paper pulp test method no. The decorative board base paper according to any one of [1] to [3], wherein the Oken smoothness according to 5-2 is 30 to 300 seconds.
[5] The decorative board base paper according to any one of [1] to [4], wherein the tensile strength in the longitudinal direction is 2.0 kN / m or more.
[6] The decorative board base paper according to any one of [1] to [5], wherein the film thickness is 50 to 200 μm.
[7] A melamine resin-containing decorative board base paper, wherein the decorative board base paper according to any one of [1] to [6] is impregnated with a melamine resin.
[8] The whiteness of the melamine resin-containing decorative board base paper before ultraviolet irradiation is (E1), and the whiteness of the melamine resin-containing decorative board base paper after irradiation with ultraviolet light at an illuminance of 180 W / m ² for 48 hours is (E2). The melamine resin-containing decorative board base paper according to [7], wherein ΔE is less than 3.0 when the whiteness color difference represented by (E2)-(E1) is ΔE.
[9] A decorative board obtained by bonding the melamine resin-containing decorative board base paper according to [7] or [8] to a core substrate.

  According to the present invention, a decorative board base paper having high concealability and weather resistance can be obtained. Furthermore, the decorative board base paper of the present invention has a sufficient tensile strength and is preferably used as a decorative board base paper for a melamine decorative board.

  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.

(Decorative board base paper)
The present invention relates to a decorative board base paper containing wood pulp as a main component and containing rutile-type titanium oxide doped with antimony. The content of rutile-type titanium oxide doped with antimony in the decorative board base paper of the present invention is 15% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper, and the total ash content of the decorative board base paper is It is less than 39.5% by mass. Here, the rutile type titanium oxide doped with antimony is internally added to the decorative board base paper.

  The content of the antimony-doped rutile titanium oxide may be 15% by mass or more and less than 39.5% by mass, and 20% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper. It is more preferable that it is 30 mass% or more and less than 39.5 mass%.

  As described above, in the present invention, rutile-type titanium oxide doped with a predetermined amount of antimony is internally added to the decorative board base paper, and the total ash content of the decorative board base paper is set within a predetermined range. Concealment and weather resistance can be improved. By adding rutile type titanium oxide doped with a predetermined amount of antimony to the decorative base paper, the opacity can be enhanced. Further, even when the decorative board base paper is impregnated with the melamine resin, the decorative board base paper can be prevented from being discolored.

  The decorative board base paper of the present invention has a JAPAN TAPPI paper pulp test method No. It is preferable to control the Oken type smoothness according to 5-2 to 30 seconds or more. Usually, the decorative board base 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. The preferred Oken smoothness range is 30 to 300 seconds, and particularly preferably 50 to 200 seconds.

  In addition, the decorative board base paper of the present invention is preferably controlled to have a tightness of 1.05 or less. By setting the tension to 1.05 or less, the decorative board base paper can have a certain degree of cushioning properties, and gravure printing can be performed satisfactorily. A preferable range of the tension is 0.70 to 1.05, and particularly preferably 0.75 to 1.00.

  The tensile strength in the longitudinal direction of the decorative board base paper of the present invention is preferably 2.0 kN / m or more, and more preferably 2.2 kN / m or more. As described above, the decorative board base paper of the present invention has a high tensile strength in the longitudinal direction, and therefore, when the decorative board base paper is processed in a roll state, it has excellent tensile properties in the flow direction and may be broken by tension adjustment. As a result, the processability and the like can be improved. In addition, the tensile strength of the decorative board base paper can be measured according to JIS P 8113: 2006 paper and paperboard-a test method for tensile properties.

  The decorative board base paper of the present invention is characterized in that it has a sufficient concealment property even though it is a thin film. Specifically, the film thickness of the decorative board base paper 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 film thickness of the decorative board base paper within the above range, it is possible to improve the printability of the decorative board base paper, and it is possible to maintain a good bonding state with the decorative board.

(Wood pulp)
As the wood pulp used for making the decorative board paper of the present invention, hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), and waste paper pulp can be appropriately mixed and used. Waste paper pulp includes DIP and waste products generated in the papermaking process. Considering the uniformity of formation, it is preferable that the ratio of LBKP is large. For example, the mixing ratio of LBKP and NBKP can be 3: 1 to 9: 1. Moreover, it is possible to mix | blend arbitrary synthetic fibers, a non-wood fiber, etc. as needed.

  The beating degree of the wood pulp used in the present invention is preferably 150 to 400 ml CSF. Thereby, the paper interlayer strength can be expressed. Further, 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.

  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 100-400 mlCSF. In particular, the freeness is more preferably 150 to 350 ml CSF. By setting the freeness of the disaggregated pulp within the above range, the tensile elongation at break 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 increased, and delamination 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.

  In the present invention, the weight-weighted average fiber length of the disaggregated pulp obtained by disaggregating the decorative board base paper is preferably 0.6 to 2.0 mm, more preferably 0.6 to 1.5 mm. More preferably, the thickness is 0.6 to 1.0 mm. By setting the weight-weighted average fiber length of the disaggregated pulp within the above range, the interfiber bonding area can be widened and the strength can be maintained, so that delamination can be suppressed. Moreover, by making the weight-weighted average fiber length of the disaggregated pulp within the above range, the texture can be improved, and in the bonding process and the gravure printing process, it is possible to suppress shrinkage due to hot air drying, Generation | occurrence | production of wrinkles etc. can be suppressed.

  In the present invention, the fiber length distribution coefficient of the disaggregated pulp obtained by disaggregating the decorative board base paper is preferably 1.5 to 4.0, more preferably 1.5 to 3.0, and 1.5 to 2 More preferably, it is 0.0. 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 delamination can be suppressed. In addition, by making the fiber length distribution coefficient of the disaggregated pulp within the above range, the texture can be improved, and shrinkage due to hot air drying can be suppressed in the bonding process and the gravure printing process. 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 No. It is a value measured by an optical automatic measurement method defined in 52: 2000.

  Weight-weighted average fiber length of disaggregated pulp from the above decorative board base paper, fiber length distribution coefficient, freeness is the weight-weighted average fiber length of pulp used when making decorative board base paper, fiber length distribution coefficient, It does not necessarily match the freeness. This is because when the decorative board base paper is made, some of the fine fibers come out of the wire mesh or net, and the aggregation state of the pulp fibers changes depending on the conditions in the wire part, press part, and dryer part (drying process). This is because there is something to do. 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 chemicals, May change by adjusting the size and shape of the flocs formed by.

(Internal additive)
Examples of the filler internally added to the decorative base paper used in the present invention include, in addition to the above-described rutile-type titanium dioxide doped with antimony, for example, titanium dioxide, kaolin, talc, heavy calcium carbonate, light calcium carbonate, sulfurous acid. Calcium, gypsum, calcined kaolin, white carbon, amorphous silica, delaminated kaolin, diatomaceous earth, magnesium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide and other inorganic pigments, urea / formalin resin Examples thereof include organic pigments such as particles and fine hollow particles. In addition, fillers contained in waste paper and waste paper can be reused.

  In addition to pulp and filler, paper for decorative board base paper such as internal sizing agent, anionic, nonionic, cationic or amphoteric retention improver, drainage improver, paper strength enhancer, pH adjuster, etc. The internal additive aid can be added as necessary. Specific examples of the internal sizing agent include rosin type, alkyl ketene dimer type, alkenyl succinic anhydride type, styrene-acrylic type, higher fatty acid type, petroleum resin type and the like.

Examples of the paper strength enhancer include anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, graft copolymer of polyacrylamide and starch, various starches, urea resin, polyamide / polyamine resin. , Polyvinyl alcohol, polyethylene oxide and the like. Among them, in order to achieve high paper interlayer strength, it is preferable to use at least one selected from anionic polyacrylamide, cationic polyacrylamide, amphoteric polyacrylamide, cationic starch, and a graft copolymer of polyacrylamide and starch. .
Examples of the wet paper strength enhancer include polyamide epichlorohydrin resin, melamine formaldehyde resin, urea formaldehyde resin 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.

  Examples of the yield improver include polyacrylamide compounds, polyethylene glycol compounds, and polyvinylamine compounds. When titanium is used as the filler, the overall yield decreases and the productivity tends to decrease. Therefore, an appropriate retention agent can be appropriately selected in order to maintain the productivity.

  Examples of pH adjusters include sulfuric acid bands, aluminum chloride, sulfuric acid, hydrochloric acid, sodium aluminate, basic aluminum compounds, caustic soda (sodium hydroxide), potassium hydroxide, ammonia, various primary, secondary, and tertiary. Examples include alkaline compounds such as secondary amines. Of these, sulfuric acid band, sulfuric acid, and caustic soda are preferable in view of versatility and economy.

  In the present invention, it is preferable to make a paper with a pulp fiber blended with at least a filler, a paper strength enhancer, a sizing agent, a yield improver, and a pH adjuster. Moreover, in order to give the texture of wood grain or marble, it is usually carried out to color yellow. As the yellow colorant, a colorant such as a dye or a pigment is preferably used. In particular, iron oxide is preferably used as the colorant because of less fading upon long-term light exposure.

(Rutyl-type titanium dioxide doped with antimony)
The rutile type titanium dioxide doped with antimony is rutile type titanium dioxide containing antimony on the surface of the rutile type titanium dioxide.
Examples of the rutile type titanium dioxide doped with antimony that can be used in the present invention include, for example, JP-A-2008-81578, JP-A-2007-9156, JP-A-9-48931, and JP-A-2-214784. An anhydrous inorganic compound coating layer containing at least dense anhydrous silica on the surface of titanium dioxide particles as described in the publication, etc., and a hydrous oxide of at least one element selected from silicon, zirconium, titanium, tin, antimony and aluminum And a titanium dioxide pigment having a hydrous inorganic compound coating layer in this order. Specific examples of rutile titanium dioxide doped with antimony include R-3L manufactured by Sakai Chemical Co., Ltd.

(Method for producing decorative board base paper)
The paper for the decorative board base paper of the present invention can be appropriately selected from known wet paper machines, for example, a paper machine such as a long net paper machine, a gap former type paper machine, a circular net type paper machine, and a short net type paper machine. it can. 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.

  In order to prevent condensation of water vapor generated in the dryer hood, improve thermal efficiency, and prevent the generation of avatar, the process of blowing hot air and sucking hot air containing water vapor is performed at least once. Usually, appropriate moisture is required for the paper to stick to the dryer, and the moisture range is preferably 45 to 65%. By setting the moisture range to an appropriate range, the drying process can be performed smoothly.

  Even if the paper has the proper amount of moisture to stick to the dryer, the water vapor that exists between the paper and the dryer may evaporate unevenly during the drying process, resulting in avatars (small gloss loss). is there. For this reason, it is necessary to uniformly and promptly remove moisture from the paper stuck 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.

  In the present invention, the decorative board base paper obtained as described above may be subjected to a surface treatment with a calendar to make the thickness profile uniform, thereby further imparting gravure printing aptitude. As the calendar process, a known calendar process can be appropriately performed, but it is preferable not to perform a strong press process or a long-time press process so that the melamine resin can be impregnated. The calender is not particularly specified, and it improves the surface smoothness such as a machine calender, a super calender in which chilled rolls and elastic rolls (cotton rolls) are stacked in multiple stages, and a soft nip calender using synthetic resin rolls as elastic rolls. Any one can be used. The soft nip calender can set the heat-resistant temperature of the surface of the synthetic resin roll higher than that of the cotton roll, and the paired metal roll can be processed at a high temperature (50 to 150 ° C.). The soft nip calender is a preferable mode because the treatment linear pressure can be set lower than that of the super calender when the same smoothness is targeted. 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.

(Melamine resin-containing decorative base paper)
The decorative board base paper of the present invention can be impregnated with melamine resin or phenol resin. Among them, the melamine resin-containing decorative board base paper obtained by impregnating the decorative board base paper of the present invention with a melamine resin is preferably used for the melamine decorative board. As the melamine resin used in the present invention, basically, a synthetic resin obtained by addition condensation reaction of melamine and formaldehyde in a neutral or alkaline environment can be used. Resins described in JP-A Nos. 2002-212389 and 2008-73979 are preferably used.

  Examples of the method of impregnating the decorative board base paper with the melamine resin include a method of immersing the decorative board base paper in an aqueous solution of melamine resin for about 10 to 300 seconds. After immersion, it is preferable to scrape off excess resin and dry it. In the drying step, for example, it is preferable to dry at 90 to 180 ° C. for about 1 to 200 minutes.

The impregnation rate of the melamine resin in the melamine resin-containing decorative board base paper is preferably 80 to 180%, and more preferably 100 to 150%. Here, the impregnation rate of the melamine resin can be calculated by the following formula.
Impregnation rate (%) = {(absolute dry weight of impregnated paper) − (absolute dry weight of decorative board base paper)} / (absolute dry weight of decorative board base paper) × 100

The melamine resin-containing decorative board base paper of the present invention has an advantage that it does not change color even when used for a long time under harsh conditions such as outdoors.
Specifically, the whiteness of the melamine resin-containing decorative board base paper before ultraviolet irradiation is defined as (E1), and the whiteness of the melamine resin-containing decorative board base paper after irradiation with ultraviolet light at an illuminance of 180 W / m ² for 48 hours ( E2), and when the whiteness color difference represented by (E2)-(E1) is ΔE, ΔE is preferably less than 3.0, more preferably less than 2.8. More preferably, it is less than 5. Thus, in the present invention, the change in whiteness before and after UV irradiation can be kept small, so that the design and the like deteriorate even when used for a long time under harsh conditions such as outdoors. There is no.

(Decorative board)
The decorative board of the present invention is formed by laminating a melamine resin-containing decorative board base paper to a core substrate. Such a melamine decorative board has a high surface hardness and is excellent in stain resistance, abrasion resistance, and heat resistance, and is used where durability of furniture, a top board, a table and the like is required.
As the core substrate, plywood, particle board, hard board, MDF, gypsum board, various cement boards or steel sheets can be used. Further, as the core substrate, a plastic plate can be used in which kraft paper impregnated with phenol resin or melamine resin is laminated in layers and laminated at high temperature and high pressure. In this case, a plastic plate obtained by laminating the above-mentioned decorative board base paper impregnated with phenol resin or melamine resin into a plurality of layers may be formed at a high temperature and high pressure. Moreover, such a plastic board may be bonded to a fiber board and used as a core substrate.

When the decorative sheet base paper is bonded to the core base material, it is preferable to perform a heat treatment at about 100 ° C. Moreover, when using several layers of kraft paper impregnated with phenol resin or melamine resin, these core base material and decorative board base paper may be pressed. As pressing conditions in this case, for example, the pressure is preferably 80 to 120 kg / cm ² , the temperature is 150 to 170 ° C., and the heating time is 1 to 1.5 hours. Note that the decorative board base paper of the present invention contains a predetermined amount of rutile-type titanium oxide doped with antimony. Therefore, even when the processing is performed under the high temperature and high pressure conditions as described above, the decorative board base paper is processed during the process. Is suppressed from discoloring.

  In the present invention, the tensile elongation at break in the transverse direction at a temperature of 100 ° C. and a preheating time of 1 minute is preferably controlled to 5% or more according to JIS P 8113: 1998. By controlling as described above, the decorative board base paper can be prevented from breaking when the decorative board is subjected to V-cut processing or lapping processing.

  The decorative board may be provided with a layer having other functions in addition to the core base material and the decorative board base paper. For example, an overlay paper may be provided on a melamine resin-containing decorative board base paper for the purpose of improving wear resistance and chemical resistance and protecting the printed pattern. Overlay paper is generally made by adding a large amount of wet paper strength enhancer to high alpha cellulose pulp, requiring little impurities, high transparency, and wet strength that can withstand impregnation even when thin. Is done.

  Further, the decorative plate may be provided with balance paper, barrier paper, or the like. The balance paper is provided on the back surface of the decorative board and is provided in order to suppress warpage of the entire decorative board. The barrier paper is provided to shield the color of the core substrate.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Example 1>
45% of rutile type titanium dioxide (R-3L, manufactured by Sakai Chemical Industry Co., Ltd.) doped with antimony in a 3% pulp suspension containing 9: 1 L-BKP and N-BKP and beaten to 350 ml freeness. %, 0.04% by mass of Kayafect Yellow AW (Nippon Kayaku Co., Ltd.) and diluted water as a yellow dye, and 1 addition of polyamide epichlorohydrin wet paper strength enhancer WS-4052 (manufactured by Seiko PMC) Mass%, polyamine-based yield improver Kathiofast VFH (manufactured by Seiko PMC) was added in the order of 1.2 mass%, and hand-pulling was performed with a square hand-pulling machine, and the basis weight was about 30 g / m ^2. The base paper for decorative board was made. The obtained decorative board base paper had an ash content of 39% by mass.
The obtained ash was subjected to EDS analysis with an electron microscope, and the content of rutile titanium dioxide doped with antimony relative to the total mass was determined to be 38.5% by mass.
The obtained decorative board base paper was impregnated with melamine formaldehyde resin (Nicaridine S-176, manufactured by Nippon Carbide Co., Ltd.) at 20% by mass with mangle roll, and dried at 95 ° C. for 10 minutes. Resin-containing decorative board base paper 1 was obtained. In addition, there was no problem in the melamine resin impregnation property of the melamine resin-containing decorative board base paper 1.

<Example 2>
The amount of addition of antimony-doped rutile-type titanium dioxide in Example 1 was 20% by mass, and 25% by mass of talc (trade name: NK-PUC, manufactured by Kanematsu Chemical Co.) was added. Thus, a melamine resin-containing decorative board base paper 2 was obtained. The obtained decorative board base paper had an ash content of 38% by mass. The content of rutile-type titanium dioxide doped with antimony with respect to the total mass was 17% by mass. In addition, there was no problem in the melamine resin impregnation property of the melamine resin-containing decorative board base paper 3.

<Example 3>
A melamine resin-containing decorative board base paper 2 was obtained by performing the same operation as in Example 1 except that the addition amount of rutile-type titanium dioxide doped with antimony in Example 1 was 20% by mass. The ash content of the obtained decorative board base paper was 18% by mass. The content of rutile-type titanium dioxide doped with antimony with respect to the total mass was 17% by mass. In addition, there was no problem in the melamine resin impregnation property of the melamine resin-containing decorative board base paper 3.

<Comparative Example 1>
A melamine resin-containing decorative board base paper 4 was obtained in the same manner as in Example 1 except that the addition of rutile-type titanium dioxide doped with antimony in Example 1 was changed to 50% by mass. The obtained decorative board base paper had an ash content of 42% by mass. The content of rutile titanium dioxide doped with antimony with respect to the total mass was 41% by mass.

<Comparative Example 2>
The rutile type titanium dioxide doped with antimony in Example 1 was changed to anatase type titanium dioxide not doped with antimony (A-100, manufactured by Ishihara Sangyo Co., Ltd.), and the addition amount was 45% by mass to 18% by mass. Changed. Otherwise, the same operation as in Example 1 was performed to obtain a melamine resin-containing decorative board base paper 5. The ash content of the obtained decorative board base paper was 13% by mass.

<Comparative Example 3>
The same procedure as in Example 1 was carried out except that the rutile-type titanium dioxide doped with antimony of Example 1 was changed to talc (trade name: NK-PUC, manufactured by Kanematsu Chemical Co., Ltd.), and the melamine resin-containing decorative board base paper 6 Got. The obtained decorative board base paper had an ash content of 39% by mass.

(Evaluation)
Each melamine resin-containing decorative board base paper obtained in Examples and Comparative Examples was evaluated by the following method.

1) Concealment property A decorative base 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.

2) Weather resistance A decorative base paper was treated with a xenon fade meter (manufactured by Suga Test Instruments) under conditions of a black panel temperature of 63 ° C., a humidity of 50% RH, and an ultraviolet irradiance of 180 W / m ² for 48 hours. With a Hunter whiteness meter, the whiteness (E1) of the decorative board base paper before ultraviolet irradiation and the whiteness (E2) of the decorative board base paper after ultraviolet irradiation were measured, and the color difference (ΔE = E2-E1) was calculated.
The weather resistance was evaluated according to the following criteria.
◎: 0.5 or more and less than 2.0 ○: 2.0 or more and less than 3.0 ×: 3.0 or more

3) Tensile strength A test piece obtained by trimming a decorative board base paper to a width of 15 mm in the CD direction and a length of 180 mm in the MD direction under conditions of 23 ° C. and 50% RH for 2 hours, and then a tensile tester Was pulled in the MD direction at a speed of 10 mm / min, and the load to break the decorative board base paper was measured.
The evaluation of tensile strength was performed according to the following criteria.
○: 2.0 kN / m or more ×: Less than 2.0 kN / m

As is clear from Table 1, in Examples 1 and 2 in which a predetermined amount of rutile-type titanium oxide doped with antimony was used, good results were obtained in all items of hiding property, weather resistance, and tensile strength. . In addition, the decorative board base paper obtained in Examples 1 to 3 also had excellent printability.
On the other hand, in Comparative Example 1 using a predetermined amount or more of rutile type titanium oxide doped with antimony, the tensile strength is remarkably deteriorated. Further, in Comparative Example 2 in which no antimony-doped rutile-type titanium oxide agent is used, the weather resistance is extremely deteriorated, and the level is not practical for use as a melamine resin-impregnated decorative board paper. Although Comparative Example 3 using talc as a filler is excellent in weather resistance, the concealability is extremely inferior.

  The decorative board base paper according to the present invention is excellent in concealability and weather resistance and has a sufficient tensile strength. Moreover, since it is excellent also in the impregnation property of a melamine resin, it is preferably used as a decorative board base paper for a melamine decorative board and has high industrial applicability.

Claims (9)

A decorative board base paper mainly composed of wood pulp,
Including rutile titanium oxide doped with antimony,
The content of the rutile-type titanium oxide doped with antimony is 15% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper, and the total ash content of the decorative board base paper is 39.5% by mass. A decorative board base paper characterized by being less than%.   2. The decorative board base paper according to claim 1, wherein the content of the antimony-doped rutile-type titanium oxide is 20% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper.   The decorative board according to claim 1 or 2, wherein the content of the antimony-doped rutile titanium oxide is 30% by mass or more and less than 39.5% by mass with respect to the total mass of the decorative board base paper. Base paper.   JAPAN TAPPI paper pulp test method No. of the decorative board base paper. The decorative board base paper according to any one of claims 1 to 3, wherein the Oken smoothness according to 5-2 is 30 to 300 seconds.   The decorative board base paper according to any one of claims 1 to 4, wherein a tensile strength in a longitudinal direction is 2.0 kN / m or more.   The decorative board base paper according to any one of claims 1 to 5, wherein the film thickness is 50 to 200 µm.   A melamine resin-containing decorative board base paper, wherein the decorative board base paper according to any one of claims 1 to 6 is impregnated with a melamine resin. The whiteness of the melamine resin-containing decorative board base paper before ultraviolet irradiation is (E1), and the whiteness of the melamine resin-containing decorative board base paper after irradiation with ultraviolet light at an illuminance of 180 W / m ² for 48 hours is (E2). The melamine resin-containing decorative board base paper according to claim 7, wherein ΔE is less than 3.0 when the whiteness color difference represented by E2)-(E1) is ΔE.   A decorative board obtained by bonding the melamine resin-containing decorative board base paper according to claim 7 or 8 to a core substrate.