JP3836239B2

JP3836239B2 - Decorative plate manufacturing method

Info

Publication number: JP3836239B2
Application number: JP36351297A
Authority: JP
Inventors: 博清水; 泰人寺田
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 1997-12-15
Filing date: 1997-12-15
Publication date: 2006-10-25
Anticipated expiration: 2017-12-15
Also published as: JPH11170210A

Description

【０００１】
【発明の属する技術分野】
本発明は、建築物の内装材料や家具用材料、特に、床材として使用するのに好適な木質系の化粧板の製造方法に関するものである。
【０００２】
【従来の技術】
従来から、合板などの木質材からなる基板の表面に突板や合成樹脂製の化粧シート又は印刷紙等の化粧シートを貼着したり、或いは塗装等を行って、表面化粧層を施してなる化粧板が、住宅等の建築物の床材や造作材或いは家具用材料として広く使用されている。しかしながら、例えば合板の表面に突板を貼着したのち塗装仕上げしてなる一般的な化粧板を床材として使用した場合、木質基板に存在する小さな穴や抜け節、ジョイント部等の欠陥部が突板表面に現出したり、さらには湿気の吸収、放散に伴う合板の膨張、収縮によって表面の突板に細かい亀裂（干割れ）が生じたりして化粧性を著しく損なうことになり、その上、床材として使用した場合には、表面に重量の大きい家具の脚や落下物などによる局部的な荷重が加わると凹みが生じたりキャスター付きワゴンによる摺動的な負荷によって化粧板の表面が傷を受ける等の問題点がある。
【０００３】
このため、合板等の木質材料からなる基板の表面に比較的硬質の中比重木質繊維板（ＭＤＦ）からなる木質繊維製板材を接着して複合板を形成し、この複合板の木質繊維製板材の表面に突き板や合成樹脂製化粧シート又は印刷紙等の化粧シートを貼着したり、塗装等によって表面化粧層を形成してなる化粧板を床材に使用する試みがなされている。
【０００４】
上記木質繊維製板材を形成する中比重木質繊維板は、木質繊維に熱硬化性樹脂接着剤を添加し、加熱下で圧締成形することによって得られたものであるため、加熱面に直接接する表裏層部が高密度に形成され、内部は相対的に低密度に形成されることになる。従って、この中比重木質繊維板を合板などの基板に積層接着して得られた複合板の表面に上記のような表面化粧層を施すと、表面が緻密で硬質且つ平滑であり、方向性が少ない中比重木質繊維板によって表面化粧層に干割れ等の欠点が生じ難くなるものである。
【０００５】
【発明が解決しようとする課題】
しかしながら、中比重木質繊維板の厚さは通常2.5mm 以上であり、従ってこのような厚みを有する中比重木質繊維板からなる木質繊維製板材を合板等の木質基板の表面（片面）に接着すると、木質基板よりも木質繊維製板材の収縮力が大きすぎて化粧板に長手方向に凹状の反りが発生することになる。このような凹反りの発生は、化粧板に形成した時にも残存し、この化粧板を床材などに適用するに際しては、その長手方向の中央部に対して両端側が上方に浮き上がった状態となり、両端部分に対する釘や接着剤による固定作業に困難を伴うばかりでなく、隣接する床材の突き合わせ端部に段差や固着不良などが生じるという問題点があった。
【０００６】
さらに、上記のような中比重木質繊維板からなる木質繊維製板材を使用すると、高密度の表裏層部に比べて内部の低密度層の厚みの割合が大きいために、このような中比重木質繊維板を備えた上記化粧板をダイニングルームの床材に適用した場合、キャスター付ワゴン等による動的荷重を受けると木質繊維製板材の低密度層に層間剥離が生じて強度が低下すると共に表面の外観を損なうことになる。
【０００７】
また、上記反りの発生を防止するために、薄い中比重木質繊維板を使用することも考えられるが、厚みが２mm未満の中比重木質繊維板を得るには、現状の製造方法では生産性がきわめて悪く且つ高価につくという問題点があり、その上、薄くすると、中比重木質繊維板は合板に比べて硬くて脆い性質を有しているため、施工時や運送時に角欠けが生じる虞れがあり、また、薄くしても床材として使用した場合には、表面に重量の大きい家具の脚や落下物などによる局部的な荷重が加わると上述したように中比重木質繊維板からなる木質繊維製板材に層間剥離が生じるという問題点がある。
【０００８】
本発明はこのような問題点に鑑みてなされたもので、その目的とするところは優れた化粧性を有すると共に木質繊維板を用いているにもかかわらず、長手方向の凹状の反りや層間剥離の発生を抑制して良好な寸法安定性を発揮し、且つ強度的にも優れた化粧板を能率よく製造し得る製造方法を提供するにある。
【０００９】
【課題を解決するための手段】
上記目的を達成するために本発明の化粧板の製造方法は、厚さが2.5 〜４mmで比重が0.6 〜1.0 であり且つ表裏層の密度が芯層の密度よりも大きい木質繊維板を、その厚さ方向の中央部から２分割して一方の面側が高密度層で他方の面側が低密度層に形成された密度傾斜を有する木質繊維製板材を作製したのち、この木質繊維製板材を低密度層側を表向きにして木質基板の表面に貼着一体化することにより複合板を形成し、さらに、この複合板表面の上記木質繊維製板材の低密度層の表面を研削したのち該複合板の木質繊維製板材表面に合成樹脂液を塗布、含浸させて強化木質繊維製板材に形成し、しかるのち、この強化木質繊維製板材表面に化粧層を設けることを特徴とするものである。
【００１０】
上記化粧板の製造方法において、上記木質基板表面に貼着している木質繊維製板材の表面の研削は、請求項２に記載したようにサンディングによって行われ、該木質繊維製板材の表層部を表面から少なくとも0.2 mm厚の研削を行うことが望ましい。
【００１１】
【作用及び効果】
木質基板表面に貼着する木質繊維製板材は、表裏層が高密度で芯層が低密度に形成されている厚さが 2.5 〜４ mm で比重が 0.6 〜 1.0 の木質繊維板を低密度層の中央部から２分割することにより得られるものであるから、市販の木質繊維板から薄い木質繊維製板材を能率よく且つ確実に得ることができると共に木質繊維板を厚さ方向の中央部から２分割するので、２枚の薄い木質繊維製板材を経済的に得ることができ、安価な製品を提供できる。
【００１２】
さらに、この木質繊維製板材をその低密度層側を表向きにして木質基板の表面に積層接着することにより複合板を形成したのち、該木質繊維製板材の表面を研削するものであるから、木質繊維製板材が木質基板と一体化して厚みのある複合板を形成しているので、その表面の研削作業が容易に行えると共に木質繊維製板材の柔らかい低密度層側を研削するので、サンディング等による研削作業が能率よく行えるものである。その上、木質繊維製板材の低密度層の表面は上述したように厚い木質繊維板の分割面であって、その表面に分割した際の微細な凹凸が生じているが、この凹凸粗面を上記研削によって除去して平滑な表面に形成することができる。
【００１３】
また、上述したように木質繊維製板材の低密度層側を研削しているものであるから、極薄で且つ全体として高密度の木質繊維製板材になり、従って、該木質繊維製板材の収縮率や方向性が木質基板に殆ど影響を及ぼすことがなく、木質繊維製板材の層間剥離が生じ難くなると共に該木質繊維製板材の収縮率や方向性が木質基板に殆ど影響を及ぼすことがなく、長さ方向の中央部から両端に向かって上向きの凹反りが生じ難い化粧板を得ることができる。
【００１４】
さらに、木質基板表面に上記木質繊維製板材を貼着して複合板を形成したのち、この複合板の木質繊維製板材表面に合成樹脂液を塗布、含浸させるものであるから、木質繊維製板材の木質繊維同士が含浸された合成樹脂によって一層強固に結合されて硬質で剛性も高くなり、耐湿性、耐水性、寸法安定性が向上すると共に角欠けや層間剥離が生じるのを確実に防止でき、その上、キャスター付きワゴンによる摺動的な荷重を繰り返し受けても、表面化粧層に傷が付き難い化粧板を製造することができる。
【００１５】
また、木質繊維製板材が極薄であるにもかかわらず、上述したように床材に必要な硬さを確保できると共に木質基板の表面に節や小穴等の欠点があっても、その欠点が表面化粧層から微妙な影や色変化となって浮かび上がるという現象を抑制することができるものであり、しかも、薄い木質繊維製板材に合成樹脂液を含浸させるものであるから、合成樹脂液の含浸によって生じ易い上記凹反りの発生を極力低減することができ、従って、釘着等による床施工性が容易に且つ正確に行えると共に段差などが生じない優れた外観を呈する床構造を形成することができる。
【００１６】
【発明の実施の形態】
次に、本発明の具体的な実施の形態を図面に基づいて詳述すると、まず、所望厚みを有する木質基板１の表面に厚さが0.5 〜２mmで比重が0.6 〜1.0 の木質繊維板からなる木質繊維製板材２を接着剤３によって一体に貼着することにより、図１（ニ）に示すような複合板A1を形成する。なお、上記木質基板１としては合板、パーティクルボード、ＯＳＢ（オリエンティドストランドボード）、ＬＶＬ（ラミネイティドベニヤランバー）等の木質板が使用され、床材を形成する場合にはこの木質基板１の厚みは通常2.3 〜25mmのものが用いられる。
【００１７】
一方、木質基板１に積層接着した木質繊維製板材２としては、図１（イ）に示すように、厚さが2.5 〜４mmで比重が0.6 〜1.0 であり且つ表裏層の密度が芯層の密度よりも大きい木質繊維板を、同図（ロ）に示すようにその厚さ方向の中央部からカッタ刃４を用いて２分割して同図（ハ）に示すように、一方の面側が高密度層で他方の面側が低密度層に形成されたものを用いる。このように、通常市販されている厚みの木質繊維板を厚さ方向の中央部から２分割するものであるから、入手が困難な薄手の木質繊維製板材２を容易に作製することができる。
【００１８】
この木質繊維製板材２をその低密度層側を表向き（上向き）にして上述したように木質基材１の表面に接着剤３を介して貼着一体化して図１（ニ）に示すように複合板A1を形成したのち、木質繊維製板材２の表面をサンディングにより研削して厚さ0.5mm 以上で２mm未満の木質繊維製板材２とする。この木質繊維製板材２の厚さが0.5mm 未満になると、薄くなりすぎて硬度等の物性が低下し、２mm以上の厚さになると木質基板１との収縮率の差が大きくなって製造すべき化粧板Ａに上述したような凹反りが生じ易くなるので、その厚みが0.5mm 以上で２mm未満、好ましくは0.7 〜1.6mm のものが使用される。このように、木質繊維製板材２を木質基板１の表面に貼着して複合板A1を作製したのち、該木質繊維製板材表面をサンディングするものであるから、薄い木質繊維製板材を単品状態で所定厚さにサンディングするのに較べ、安定して精度よく且つ加工性よく研削処理を行うことができる。
【００１９】
なお、厚みが0.5mm 以上、２mm未満の上記木質繊維製板材２を得るには、４mm以上の木質繊維板を厚さ方向の中央部から２分割したのち、サンディングすることによって作製することもできるが、この場合にはサンディング量が多くなりすぎて加工手間や歩留まりが悪くなるので好ましくない。また、この木質繊維製板材２の比重が0.6 未満であると硬さが不足する一方、1.0 を越えると剛性が高くなりすぎて上記凹反りが生じたり木質材としての触感が悪くなるので、0.6 〜1.0 、好ましくは0.65〜0.90の範囲に調整された木質繊維製板材２を用いる。
【００２０】
木質繊維製板材２を木質基板１上に接着する接着剤３としては、例えば、尿素−ホルマリン樹脂、尿素−メラミン−ホルマリン樹脂、メラミン−フェノール−ホルマリン樹脂、アルキルフェノールホルマリン樹脂、ウレタン樹脂、エポキシ樹脂、水性ビニルウレタン樹脂、酢ビ−尿素系水性樹脂、アクリル−メラミン系水性エマルジョン、ポバール−イソシアネート水性エマルジョンなど、酢酸ビニル系、尿素樹脂系、メラミン樹脂系、フェノール系、ウレタン系、エポキシ系の接着剤を使用することができる。
【００２１】
次いで、上記複合板A1における木質繊維製板材２の表面に合成樹脂液５を図１（ホ）に示すように、含浸ロール６を使用して塗布、含浸する。この合成樹脂液５の含浸、硬化によって木質繊維製板材２の表層が強化され、角欠けや層間剥離の生じ難い強化木質繊維製板材2'となると共にこの木質繊維製板材２の厚みが薄いにもかかわらず、特に、床材に必要な硬さを確保できる。なお、木質繊維製板材２に対する合成樹脂液の塗布、含浸量は、木質繊維製板材２の重量に対して固形分換算で３〜30％程度がよい。３重量％未満であると硬度や剛性等の強度が不足する一方、30重量％を超えると強度が殆ど大きくなることがなく不経済となるので、上記範囲の含浸量とすることが望ましい。
【００２２】
木質繊維製板材２に塗布、含浸させる合成樹脂としては、例えば、熱硬化性の合成樹脂としてユリア系樹脂、メラミン系樹脂、フェノール系樹脂、イソシアネート系樹脂、ポリエステル樹脂、ウレタン樹脂、エポキシ樹脂などを用いることができ、熱可塑性の合成樹脂としては酢酸ビニル系樹脂、塩化ビニル樹脂などが用いることができる。また、熱硬化性合成樹脂と熱可塑性合成樹脂との混合樹脂を使用することもでき、このような混合樹脂としては例えばＳＢＲーメラミン樹脂がある。
【００２３】
次いで、この強化木質繊維製板材2'の表面に図１（ヘ）に示すように、化粧層７を設けることによって化粧板Ａを作製するものである。化粧層７としては、強化木質繊維製板材2'の表面に印刷紙を接着したのちクリアー塗装などの塗装を施したもの、或いは、突き板を貼着したのちクリアー塗装などの塗装を施したもの、又は、ダイレクトプリントをしたのちクリアー塗装などの塗装を施したもの、化粧シートを貼着して形成した化粧層、ＷＰＣ処理突き板を貼着したのちクリアー塗装などの塗装を施したもの等を採用することができる。次に本発明の具体的な実施例と比較例を示す。
【００２４】
〔実施例〕
厚さが2.7mm で全体の比重が0.74であり、且つ表裏層の比重が芯層の比重に較べて高い中比重木質繊維板を、その厚さが略半分となるように厚さ方向の中央部から上下に２分割することにより、厚さが約1.35mmで分割面が粗面となっている木質繊維製板材を得た。この木質繊維製板材を、厚さが10.5mmで５プライの合板基板の表面に該木質繊維製板材の分割面が表面側となるように積み重ね、その重ね面に塗布している水性ビニルウレタン樹脂接着剤を介して冷圧により接着し、複合板を得た。
【００２５】
次いで、この複合板における木質繊維製板材の表面をサンディングして該木質繊維製板材の厚さを1.0mm にしたのち、この木質繊維製板材の表面に硬化剤として塩化アルモニウムを0.5 ％内添しているメラミン樹脂液をスポンジロールを使用して塗布すると共に押圧して樹脂液を固形分換算で木質繊維製板材に対し６重量％、含浸させ、しかるのち、木質繊維製板材の表面に厚さが0.43mmの不飽和ポリエステル樹脂含浸処理突板（ＷＰＣ板）をビニルウレタン樹脂接着剤を介して載置し、ホットプレスにより加熱、加圧して木質繊維製板材に塗布、含浸している上記メラミン樹脂液を硬化させると共に突板を一体に接着させた。その後、突板の表面にポリエステル系クリア塗料を塗布することにより化粧板を形成した。
【００２６】
〔比較例〕
上記実施例において、木質繊維製板材に塩化アルモニウムを0.5 ％内添しているメラミン樹脂液を塗布、含浸させる以外は全て材料や処理条件を同じにして化粧板を得た。即ち、厚さが10.5mmで５プライの合板基板の表面に厚さが1.0mm に調整した木質繊維製板材を貼着したのち、該木質繊維製板材に合成樹脂液を含浸させることなくその表面に厚さが0.43mmの不飽和ポリエステル樹脂含浸処理突板をビニルウレタン樹脂接着剤を介して加熱、加圧することにより接着し、該突板の表面にポリエステル系クリア塗料を塗布してなる化粧板を得た。
【００２７】
上記実施例と比較例とで示した製造方法によって幅240mm ×長さ750mm ×厚さ12mmの床材としての化粧板をそれぞれ作製し、これらの床材の耐圧試験と耐キャスター試験および角欠け試験を行った結果を次表に示す。
【００２８】
【表１】

【００２９】
上記表からも明らかなように、比較例で得た床材の木質繊維製板材にはキャスターの摺動荷重によって層間剥離が生じると共に角欠けも発生し易く、また、硬度も床材として不足しているが、実施例で得た床材においてはその木質繊維製板材には層間剥離が生じていなく、その上、角欠けもなく、床材としての充分な強度を有するものである。なお、耐圧試験は直径10mmの鋼球を１／π(mm)食い込ませるのに必要な荷重を測定（ブリネル強度試験）によって行い、耐キャスター試験は床材の平行方向と直行方向に80Kgの荷重を有する車輪４個を備えたキャスターを最大10万回、往復走行させることによって行った。
【図面の簡単な説明】
【図１】化粧板の製造工程を示す簡略工程図。
【符号の説明】
１木質基板
２木質繊維製板材
2' 強化木質繊維製板材
５合成樹脂含浸
７化粧層
A1 複合板
Ａ化粧板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a wood-based decorative board suitable for use as an interior material of a building or a furniture material, particularly as a flooring material.
[0002]
[Prior art]
Conventionally, a makeup made by applying a surface decorative layer by sticking a decorative sheet such as a veneer or a synthetic resin decorative sheet or printing paper to the surface of a substrate made of a woody material such as plywood, or by painting or the like. A board is widely used as a flooring material, a building material or a furniture material of a building such as a house. However, for example, when a general decorative board is applied as a floor covering after sticking a veneer on the surface of a plywood, defective parts such as small holes, gaps and joints on the wooden board Appearance on the surface, and also the absorption of moisture, the expansion and contraction of the plywood due to the diffusion, the surface veneer may cause fine cracks (dry cracks), which will significantly impair the cosmetics, in addition, flooring If the load is applied as a heavy load on the surface of the furniture, such as a heavy furniture leg or a falling object, the surface of the decorative board may be damaged by a dent or a sliding load caused by a wagon with casters. There are problems.
[0003]
For this reason, a composite board is formed by adhering a relatively hard wood fiber board made of medium specific gravity wood fiber board (MDF) to the surface of a board made of wood material such as plywood, and this composite board wood fiber board material Attempts have been made to use a decorative board formed by attaching a decorative sheet such as a veneer, a synthetic resin decorative sheet or printing paper on the surface of the sheet, or forming a surface decorative layer by painting or the like.
[0004]
The medium specific gravity wood fiber board forming the wood fiber board is obtained by adding a thermosetting resin adhesive to the wood fiber and press-molding under heating, so that it directly contacts the heating surface. The front and back layer portions are formed with a high density, and the inside is formed with a relatively low density. Therefore, when the above-mentioned surface decorative layer is applied to the surface of the composite board obtained by laminating and bonding this medium specific gravity wood fiber board to a substrate such as plywood, the surface is dense, hard and smooth, and the directionality is The small medium specific gravity wood fiber board makes it difficult to cause defects such as dry cracks in the surface decorative layer.
[0005]
[Problems to be solved by the invention]
However, the thickness of the medium specific gravity wood fiber board is usually 2.5 mm or more. Therefore, when the wood fiber plate made of medium specific gravity wood fiber board having such a thickness is bonded to the surface (one side) of a wood substrate such as plywood. The contraction force of the wood fiber plate material is too large compared to the wood substrate, and a concave warp occurs in the longitudinal direction on the decorative board. The occurrence of such a concave warp remains even when it is formed on a decorative board.When this decorative board is applied to a flooring or the like, both end sides are lifted upward with respect to the central portion in the longitudinal direction. There is a problem that not only the fixing work by the nail or the adhesive to the both end portions is accompanied by difficulty, but also a step or an improper fixing occurs at the abutting end portion of the adjacent flooring material.
[0006]
Furthermore, when using a wood fiber plate made of medium specific gravity wood fiber as described above, the ratio of the thickness of the internal low density layer is larger than that of the high density front and back layer parts, so such medium specific gravity wood When the above decorative board with fiberboard is applied to the flooring of a dining room, when subjected to a dynamic load such as a wagon with casters, delamination occurs in the low-density layer of the wood fiber board and the strength decreases and the surface Will damage the appearance.
[0007]
In order to prevent the occurrence of the warp, it is conceivable to use a thin medium specific gravity wood fiber board. However, in order to obtain a medium specific gravity wood fiber board having a thickness of less than 2 mm, the current manufacturing method has a high productivity. There is a problem that it is very bad and expensive. Moreover, if it is made thin, medium specific gravity wood fiberboard has a harder and more brittle nature than plywood, so there is a risk of corner breakage during construction and transportation. In addition, when used as a flooring, even if it is thin, if a local load is applied to the surface due to heavy furniture legs or fallen objects, etc. There is a problem that delamination occurs in the fiber plate material.
[0008]
The present invention has been made in view of such problems. The object of the present invention is to have excellent cosmetic properties and use of a wood fiberboard, but in the longitudinal concave warp and delamination. It is an object of the present invention to provide a production method capable of efficiently producing a decorative board exhibiting good dimensional stability by suppressing the occurrence of the above and having excellent strength.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing a decorative board of the present invention comprises a wood fiber board having a thickness of 2.5 to 4 mm, a specific gravity of 0.6 to 1.0, and a density of front and back layers larger than that of the core layer. After producing a wood fiber plate material having a density gradient in which one surface side is formed into a high density layer and the other surface side is formed into a low density layer by dividing into two from the central portion in the thickness direction, this wood fiber plate material is A composite board is formed by sticking and integrating to the surface of the wood substrate with the density layer side facing up. Further, after grinding the surface of the low density layer of the wood fiber plate material on the surface of the composite board, the composite board A synthetic resin liquid is applied to and impregnated on the surface of the wood fiber plate material to form a reinforced wood fiber plate material, and then a decorative layer is provided on the surface of the reinforced wood fiber plate material.
[0010]
In the method for manufacturing the decorative board, the surface of the wood fiber sheet material adhered to the surface of the wood substrate is ground by sanding as described in claim 2, and the surface layer portion of the wood fiber sheet material is formed. It is desirable to grind at least 0.2 mm thick from the surface.
[0011]
[Action and effect]
Wood fiber sheet material to adhere to the wood substrate surface, front and back layers are low density layer wood fiberboard 0.6-1.0 specific gravity in a high density a thickness that the core layer is formed on the low-density 2.5 to 4 mm Therefore, it is possible to efficiently and reliably obtain a thin wood fiber board material from a commercially available wood fiber board and to remove the wood fiber board from the center part in the thickness direction. Since it divides | segments, the two thin wood fiber board | plate materials can be obtained economically and an inexpensive product can be provided.
[0012]
Furthermore, after forming the composite board by laminating and bonding the wood fiber plate material to the surface of the wood substrate with the low density layer side facing up, the surface of the wood fiber plate material is ground. Since the fiber board is integrated with the wood substrate to form a thick composite board, the surface can be easily ground and the soft low density layer side of the wood fiber board is ground. Grinding work can be performed efficiently. In addition, the surface of the low-density layer of the wood fiber plate material is a divided surface of the thick wood fiber board as described above, and there are fine irregularities when divided on the surface. It can be removed by grinding to form a smooth surface.
[0013]
Further, since the low-density layer side of the wood fiber board is ground as described above, it becomes an extremely thin and high-density wood fiber board as a whole, and therefore the shrinkage of the wood fiber board The rate and direction have little influence on the wood substrate, and the delamination of the wood fiber board is less likely to occur, and the shrinkage rate and direction of the wood fiber board have little influence on the wood board. A decorative board in which upward concave warpage hardly occurs from the central portion in the length direction toward both ends can be obtained.
[0014]
Furthermore, after the above-mentioned wood fiber plate material is bonded to the surface of the wood substrate to form a composite plate, a synthetic resin solution is applied to and impregnated on the surface of the wood fiber plate material of this composite plate. It is harder and more rigid due to the synthetic resin impregnated with wood fibers, making it harder and more rigid, improving moisture resistance, water resistance and dimensional stability, and reliably preventing corner chipping and delamination. Moreover, it is possible to manufacture a decorative board in which the surface decorative layer is hardly damaged even when it is repeatedly subjected to a sliding load by a wagon with casters.
[0015]
In addition, despite the fact that the wood fiber plate is extremely thin, it is possible to secure the necessary hardness for the flooring as described above, and even if there are defects such as nodes and small holes on the surface of the wooden substrate, the defects are It is possible to suppress the phenomenon of subtle shadows and color changes from the surface decorative layer, and to impregnate the synthetic resin solution into a thin wood fiber board. It is possible to reduce the occurrence of the above-described concave warp that is likely to occur due to impregnation, and therefore, to form a floor structure that can easily and accurately perform floor construction by nail attachment or the like and that has an excellent appearance without causing a step or the like. Can do.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, a specific embodiment of the present invention will be described in detail with reference to the drawings. First, from a wooden fiberboard having a thickness of 0.5 to 2 mm and a specific gravity of 0.6 to 1.0 on the surface of a wooden substrate 1 having a desired thickness. The wood fiber plate material 2 to be formed is bonded together with an adhesive 3 to form a composite plate A1 as shown in FIG. The wooden board 1 is a wooden board such as plywood, particle board, OSB (orientated strand board), LVL (laminated veneer lumbar), and the wooden board 1 is used when forming a flooring. The thickness is usually 2.3 to 25 mm.
[0017]
On the other hand, as shown in FIG. 1 (a), the wood fiber sheet material 2 laminated and adhered to the wood substrate 1 has a thickness of 2.5 to 4 mm, a specific gravity of 0.6 to 1.0, and a density of the front and back layers of the core layer. A wood fiber board having a density larger than that of the density is divided into two parts by using a cutter blade 4 from the central portion in the thickness direction as shown in the same figure (b), and as shown in FIG. A high-density layer in which the other surface side is a low-density layer is used. Thus, since the wood fiber board of thickness normally marketed is divided into 2 from the center part of the thickness direction, the thin wood fiber board | plate material 2 which is difficult to obtain can be produced easily.
[0018]
As shown in FIG. 1 (D), the wood fiber plate 2 is bonded and integrated on the surface of the wood substrate 1 with the adhesive 3 as described above with the low density layer side facing up (upward). After forming the composite board A1, the surface of the wood fiber board material 2 is ground by sanding to obtain a wood fiber board material 2 having a thickness of 0.5 mm or more and less than 2 mm. If the thickness of this wood fiber plate 2 is less than 0.5 mm, it will become too thin and the physical properties such as hardness will decrease, and if it becomes 2 mm or more, the difference in shrinkage from the wood substrate 1 will increase. Since the concave warp as described above is likely to occur in the decorative decorative plate A, a thickness of 0.5 mm or more and less than 2 mm, preferably 0.7 to 1.6 mm is used. In this way, after the wood fiber board 2 is adhered to the surface of the wood substrate 1 and the composite board A1 is manufactured, the surface of the wood fiber board is sanded. Compared with sanding to a predetermined thickness, the grinding process can be performed stably, accurately and with good workability.
[0019]
In addition, in order to obtain the above-mentioned wood fiber sheet material 2 having a thickness of 0.5 mm or more and less than 2 mm, the wood fiber board of 4 mm or more can be produced by dividing into two from the central portion in the thickness direction and then sanding. However, in this case, the amount of sanding is excessively increased, so that the processing effort and the yield are deteriorated. On the other hand, if the specific gravity of the wood fiber plate material 2 is less than 0.6, the hardness is insufficient, while if it exceeds 1.0, the rigidity becomes too high and the above-described concave warpage occurs or the tactile sensation as a wood material becomes poor. A wood fiber plate 2 adjusted to a range of ˜1.0, preferably 0.65 to 0.90 is used.
[0020]
Examples of the adhesive 3 for bonding the wood fiber plate material 2 onto the wood substrate 1 include, for example, urea-formalin resin, urea-melamine-formalin resin, melamine-phenol-formalin resin, alkylphenol formalin resin, urethane resin, epoxy resin, Aqueous vinyl urethane resin, vinyl acetate-urea aqueous resin, acrylic-melamine aqueous emulsion, poval-isocyanate aqueous emulsion, vinyl acetate, urea resin, melamine resin, phenolic, urethane, epoxy adhesive Can be used.
[0021]
Next, the synthetic resin liquid 5 is applied and impregnated on the surface of the wood fiber plate member 2 in the composite board A1 using an impregnation roll 6 as shown in FIG. By impregnating and curing the synthetic resin liquid 5, the surface layer of the wood fiber plate 2 is reinforced, resulting in a reinforced wood fiber plate 2 'in which corner chipping and delamination are unlikely to occur, and the thickness of the wood fiber plate 2 is thin. Nevertheless, the hardness necessary for the flooring can be secured. The amount of the synthetic resin solution applied and impregnated on the wood fiber plate material 2 is preferably about 3 to 30% in terms of solid content with respect to the weight of the wood fiber plate material 2. If it is less than 3% by weight, the strength such as hardness and rigidity is insufficient. On the other hand, if it exceeds 30% by weight, the strength hardly increases and becomes uneconomical.
[0022]
Examples of the synthetic resin to be applied and impregnated on the wood fiber plate 2 include, for example, urea resins, melamine resins, phenol resins, isocyanate resins, polyester resins, urethane resins, and epoxy resins as thermosetting synthetic resins. A vinyl acetate resin, a vinyl chloride resin, etc. can be used as a thermoplastic synthetic resin. Also, a mixed resin of a thermosetting synthetic resin and a thermoplastic synthetic resin can be used, and an example of such a mixed resin is SBR-melamine resin.
[0023]
Next, as shown in FIG. 1 (f), a decorative board A is prepared by providing a decorative layer 7 on the surface of the reinforcing wood fiber plate 2 '. As the decorative layer 7, the surface of the reinforcing wood fiber board 2 'is coated with printing paper and then applied with a clear coating, or the veneer is pasted and then applied with a clear coating or the like. Or, after applying a direct print and applying a clear coating, etc., a decorative layer formed by attaching a decorative sheet, or applying a clear coating after applying a WPC treated veneer, etc. Can be adopted. Next, specific examples and comparative examples of the present invention will be shown.
[0024]
〔Example〕
A medium specific gravity wood fiberboard with a thickness of 2.7mm and an overall specific gravity of 0.74 and a high specific gravity of the front and back layers compared to the specific gravity of the core layer. By dividing into two parts from top to bottom, a wood fiber plate material having a thickness of about 1.35 mm and a rough divided surface was obtained. This wood fiber board is stacked on the surface of a 5-ply plywood board with a thickness of 10.5mm so that the split surface of the wood fiber board is on the surface side, and the water-based vinyl urethane resin applied to the stack The composite plate was obtained by bonding with cold pressure through an adhesive.
[0025]
Next, after sanding the surface of the wood fiber board material in this composite board to make the thickness of the wood fiber board material 1.0 mm, 0.5% of aluminum chloride as a hardener is internally added to the surface of the wood fiber board material. The melamine resin solution is applied using a sponge roll and pressed to impregnate 6% by weight of the resin solution in terms of solid content with respect to the wood fiber plate material. The above-mentioned melamine resin, in which an impregnated polyester resin impregnated veneer (WPC board) with a thickness of 0.43mm is placed via a vinyl urethane resin adhesive, and heated and pressed by a hot press to apply and impregnate the wood fiber board The liquid was cured and the veneer was bonded together. Then, the decorative board was formed by apply | coating a polyester-type clear coating material on the surface of a veneer.
[0026]
[Comparative Example]
In the above examples, a decorative board was obtained in the same manner as in the materials and treatment conditions except that a melamine resin solution containing 0.5% aluminum chloride was applied and impregnated onto the wood fiber board. That is, after sticking a wood fiber board with a thickness of 1mm to a 5-ply plywood substrate and adjusting the thickness to 1.0 mm, the surface of the wood fiber board is not impregnated with a synthetic resin solution. A veneer with an impregnated polyester resin impregnated with a thickness of 0.43 mm is bonded by heating and pressurizing via a vinyl urethane resin adhesive, and a polyester-based clear paint is applied to the surface of the veneer to obtain a decorative board It was.
[0027]
A decorative board as a flooring material having a width of 240 mm, a length of 750 mm, and a thickness of 12 mm was produced by the manufacturing methods shown in the above examples and comparative examples, and a pressure resistance test, a caster resistance test, and a corner chipping test of these floor materials. The results are shown in the following table.
[0028]
[Table 1]

[0029]
As is clear from the above table, the wood fiber board material of the floor material obtained in the comparative example is likely to cause delamination and corner breakage due to the sliding load of the casters, and the hardness is insufficient as the floor material. However, in the flooring materials obtained in the examples, delamination does not occur in the wood fiber plate material, and furthermore, there is no corner chipping and the flooring material has sufficient strength as a flooring material. The pressure test is performed by measuring the load required to bite a steel ball with a diameter of 10 mm (1 / B) (Brinell strength test). The caster test is a load of 80 kg in the parallel and perpendicular directions of the flooring. This was carried out by reciprocating a caster equipped with four wheels having a maximum of 100,000 times.
[Brief description of the drawings]
FIG. 1 is a simplified process diagram illustrating a manufacturing process of a decorative board.
[Explanation of symbols]
1 Wood substrate 2 Wood fiber board
2 'Reinforced wood fiber board 5 Synthetic resin impregnation 7 Cosmetic layer
A1 Composite board A decorative board

Claims

A wood fiberboard having a thickness of 2.5 to 4 mm, a specific gravity of 0.6 to 1.0, and a density of the front and back layers larger than that of the core layer is divided into two from the central portion in the thickness direction, and one surface side has a high density. After producing a wood fiber board having a density gradient in which the other surface side is formed as a low density layer, the wood fiber board is bonded and integrated to the surface of the wood substrate with the low density layer side facing up. To form a composite board, and after grinding the surface of the low-density layer of the wood fiber board on the surface of the composite board, a synthetic resin solution is applied to the wood fiber board surface of the composite board and impregnated to strengthen A method for producing a decorative board, comprising: forming a wood fiber board, and then providing a decorative layer on the surface of the reinforced wood fiber board.

2. The method for manufacturing a decorative board according to claim 1, wherein the surface of the wood fiber plate material adhered to the surface of the wood substrate is ground by sanding and is ground to a thickness of at least 0.2 mm.