JP4043687B2

JP4043687B2 - Wood cement board and method for producing the wood cement board

Info

Publication number: JP4043687B2
Application number: JP2000106366A
Authority: JP
Inventors: 正範鵜飼
Original assignee: Nichiha Corp
Current assignee: Nichiha Corp
Priority date: 2000-04-07
Filing date: 2000-04-07
Publication date: 2008-02-06
Anticipated expiration: 2020-04-07
Also published as: JP2001294473A

Description

【０００１】
【産業上の利用分野】
本発明は例えば屋根の下地材である野地板や外装材等に使用される木質セメント板に関するものである。
【０００２】
【発明の背景】
この種の木質セメント板は、木片とセメントとを主体とする原料混合物を板状に成形硬化した所謂木片セメント板と言われるものであり、防火性、木材加工性を備えた板である。しかし該木質セメント板は粗大形状の木片によってのみ補強されているので、野地板等に使用する場合に釘を打ち込むと、打込み個所によっては、裏面層に厚めの木片が存在し、釘がその木片にあたっても貫通出来ずに裏面を押し、釘のまわりの部分が欠落してしまういわゆる花咲き現象が発生する。このような花咲き現象が発生すると板の釘保持力が低下する。
【０００３】
【従来の技術】
このような木質セメント板の釘打ち性を改良する手段として、従来木片セメント板に更にドライパルプや合成繊維を添加することが提案されている（特開平９−８７００２号）。
【０００４】
【発明が解決しようとする課題】
木片セメント板は木片とセメントとを主体とする原料混合物に水を添加して基板上に撒布することによってマットをフォーミングし、該マットを圧締養生硬化せしめる半乾式法によって製造されるが、この場合ドライパルプや合成繊維を多量に添加すると繊維相互が絡み合ってダマが出来、そのために充分な補強効果が得られない。したがって木片セメント板を半乾式法によって製造する場合には多量のドライパルプや合成繊維を添加することが出来ず（通常０．１〜２．０重量％程度）、釘打ち性の改良効果は充分とは言えなかった。
【０００５】
【課題を解決するための手段】
本発明は、上記従来の課題を解決するための手段として、木片ＦＬまたは木質繊維ＦＬ’とセメント系無機材料とを含有する原料混合物の硬化物である木質セメント板であって、内部には熱可塑性有機繊維ＯＦの綿状塊中に該原料混合物が包含されている集合体Ｃに由来する該熱可塑性有機繊維網が全体的に広がっており、表層および／または裏層部分では該熱可塑性有機繊維ＯＦは相互融着している木質セメント板を提供するものである。
また該熱可塑性有機繊維ＯＦは該木質セメント板中に１．０〜８．０重量％含有されていることが望ましい。
【０００６】
更に本発明では熱可塑性有機繊維ＯＦと木片ＦＬとを高速回転攪拌によって混合することによって該熱可塑性有機繊維ＯＦを木片ＦＬに絡ませつゝ綿状とした上で他の木質セメント板原料および水とを添加混合して原料混合物を調製し、該原料混合物を基板上に撒布してマットをフォーミングし、該マットを圧締硬化養生する木質セメント板の製造方法および熱可塑性有機繊維ＯＦと木質繊維ＦＬ’とを高速回転攪拌によって混合することによって該熱可塑性有機繊維ＯＦを木質繊維ＦＬ’に絡ませつゝ綿状とした上で他の木質セメント板原料と共に水に分散させて原料スラリーを調製し、該原料スラリーを抄造してマットをフォーミングし、該マットを圧締硬化養生する製造方法を提供するものである。
【０００７】
【発明の実施の形態】
以下、本発明を詳細に説明する。
〔セメント系無機粉体〕
本発明に使用するセメント系無機粉体とは、ケイ酸カルシウムを主成分とした水硬性の無機材料であり、このような無機材料としては、例えばポルトランドセメント、あるいはポルトランドセメントに高炉スラグを混合した高炉セメント、フライアッシュを混合したフライアッシュセメント、火山灰や白土等のシリカ物質を混合したシリカセメント、アルミナセメント、高炉スラグ等がある。
【０００８】
〔木片〕
本発明に使用する木片としては、特に限定されないが、単層用としては平均長さが１〜２０mm、厚みが０．５〜３mmであるものが好ましく、２層構造における表層または３層構造における表層用としては平均長さ１〜１２mm、厚みが０．５〜１．５mmであるもの（細粒木片）が好ましく、２層構造における裏層用としては平均長さが１〜１５mm、厚みが０．５〜２mmであるもの（中粒木片）が好ましく、３層構造における芯層用としては平均長さが５〜２０mm、厚みが０．８〜２．５mmであるもの（粗粒木片）が好ましい。
上記のとおり、２層構造における裏層用の木片は表層用の木片よりも若干粗くてもよいが、細かい方が花咲き現象が生じにくい。
【０００９】
〔木質繊維〕
本発明の湿式法で使用する木質繊維としては、クラフトパルプ、故紙あるいはバージンパルプ等の木質繊維が望ましい。
【００１０】
〔熱可塑性有機繊維〕
本発明に使用する熱可塑性有機繊維とは、ポリアミド繊維、ポリエステル繊維、ポリエチレン繊維、ポリプロピレン繊維等の熱可塑性樹脂の繊維であるが、上記熱可塑性繊維に加えてポリビニルアルコ−ル繊維（ビニロン）、ポリ塩化ビニル、ポリ塩化ビニリデン等のポリ塩化ビニル系繊維、ポリウレタン繊維、ポリオキシメチレン繊維、ポリテトラフルオロエチレン繊維、ベンゾエ−ト繊維、ポリイミド繊維等の合成繊維等である。上記繊維は不織布、編織物、フェルト等の繊維シートのスクラップを解繊した再生繊維であってもよい。また上記繊維は望ましくは径０．１mm以下の単繊維である。
【００１１】
〔その他の成分〕
本発明の木質セメント板には、上記セメント系無機材料及び熱可塑性有機繊維以外の成分として、塩化マグネシウム、硫酸マグネシウム、塩化カルシウム、硫酸カルシウム、アルミン酸ナトリウム、アルミン酸カリウム、硫酸アルミニウム、水ガラス等の硬化促進剤、バーミキュライト、ベントナイト等の鉱物粉末、木片セメント板、木質繊維セメント板のような木質セメント板の廃材の粉砕物（リジェクト）、ワックス、パラフィン、シリコン等の防水剤、合成樹脂エマルジョン等の補給材、発泡性熱可塑性プラスチックビ−ズ、プラスチック発泡体等が添加されてもよい。
上記例示は本発明を限定するものではない。
【００１２】
〔木質セメント板の組成〕
本発明の木質セメント板の原料混合物において、上記セメント系無機材料は５５〜９０重量％であるのが好ましく、上記木片は１０〜４５重量％であるのが好ましく、上記熱可塑性有機繊維が合成繊維の場合には１．０〜５．０重量％、望ましくは１．５〜２．５重量％、木質繊維の場合には３〜２０重量％、望ましくは５〜１０重量％とする。
上記原料混合物中、木片の混合物比が１０重量％未満では該木片による補強効果は十分でなくなり、木片の混合比が４５重量％を超えると、相対的にセメント系無機材料の量が少なくなるため、該セメント系無機材料の固結が阻害され、かえって強度が低下する傾向にある。
また熱可塑性有機繊維の添加量が上記範囲を下回ると釘打ち性の改良効果が顕著でなくなり、更に上記範囲を超えると繊維相互が絡み易くなる。
【００１３】
〔木質セメント板の製造〕
本発明の木質セメント板は、半乾式法あるいは湿式抄造法によって製造するのが好ましく、特にこれらの方法によって製造した木質セメント板において、花咲き現象の防止又は抑制という効果が顕著にあらわれる。
【００１４】
半乾式法の場合にはまず上記熱可塑性有機繊維と上記木片とを例えば回転式ミキサーのような強制攪拌型ミキサーを使用して高速回転攪拌する。そうすると上記熱可塑性有機繊維が木片に絡みつきながら綿状になる。
【００１５】
上記のようにして熱可塑性有機繊維を木片に絡ませ綿状にした後、セメント系無機材料、鉱物粉末、リジェクト等の粉体原料を添加混合し、次いで防水剤、硬化促進剤、水を添加混合して原料混合物を調製する。水の添加量は該原料混合物中の水分含有率が通常１５〜５０重量％になるようにするが、補強材が木質繊維の場合には熱可塑性有機繊維と木質繊維とを強制攪拌型ミキサー等で高速回転攪拌して熱可塑性有機繊維を木質繊維に絡ませた後、粉体原料を添加混合する時点であらかじめ少量の水を添加することが望ましい。
【００１６】
上記原料調製過程を図１(1),(2),(3),(4) に示す。(1) において木片ＦＬと熱可塑性有機繊維ＯＦとを高速回転攪拌すると、(2) に示すように木片ＦＬに熱可塑性有機繊維ＯＦが絡みついてくる。更に高速回転攪拌すると、(3) に示すように該熱可塑性有機繊維ＯＦが絡みついている木片相互の集塊化が起り始め、該集塊には空気が含まれて綿菓子状に膨れる。こゝでセメント等の粉体原料Ｐを添加し更に高速回転攪拌すると、最終的には(4) に示すように表面にセメント等の粉体原料Ｐが付着した木片ＦＬが綿菓子状の熱可塑性有機繊維即ち熱可塑性有機繊維の綿状塊中に散在包含されている集合体Ｃが生成する。
このような集合体Ｃを含む原料混合物は型板、搬送板等の基板Ｂ上に撒布され図２に示すようなマットＭがフォーミングされる。
【００１７】
以上のようにして集合体Ｃを含むマットＭがフォーミングされたら、該マットＭを基板とともに圧締して加熱状態下で一次硬化せしめる。該一次硬化において適用される温度は通常５０〜１００℃であり、圧締圧は通常２〜５MPa である。
上記一次硬化後、得られた一次硬化体は脱型した上で常温養生又はオートクレーブ養生する。常温養生は、通常常温で２〜５日間行われ、オートクレーブ養生は、通常８５％ＲＨ以上の湿度、１３０〜１８０℃の温度で４〜１８時間行われる。常温養生又はオートクレーブ養生後は、乾燥工程を経て表面処理を行い木質セメント板とする。
【００１８】
木質セメント板表面に凹凸模様を付する場合には、該基板の型面に該凹凸模様に対応した凹凸模様を形成しておけばよい。また表面に凹凸模様のない平滑な木質セメント板を製造する場合には、基板として直接搬送板を使用してもよい。
【００１９】
湿式抄造法の場合には、半乾式法と同様に熱可塑性有機繊維を木質繊維に絡ませ綿状とした上で半乾式法と同様な他の木質セメント板原料と共に水に分散させて原料スラリーとする。該原料スラリーは通常固形分濃度を１０〜２０重量％程度に調製され、濾水性のよい長尺の濾布上に流込み抄造して抄造層となし、該抄造層をメイキングロールに複数層巻取り所定厚みの段階で裁断展開した積層マットを通常平板プレスまたはロールプレスで加圧成形して成形マットとする。該成形マットは通常上記の条件下で圧締硬化され、その後上記の通り２〜５日間の常温養生もしくは通常８５％ＲＨ以上の湿度、１３０〜１８０℃の温度で４〜１８時間のオートクレーブ養生される。
【００２０】
上記半乾式法あるいは湿式抄造法によって製造された木質セメント板は、表層および／または裏層部分を熱可塑性有機繊維の軟化点以上の温度に加熱して、該表層および／または裏層部分の該熱可塑性有機繊維を相互融着せしめ部分接着もしくは点接着させる。
上記木質セメント板の表層および／または裏層部分の加熱は、オートクレーブ養生中や、熱プレート、熱ロールプレスあるいは乾燥工程での加熱室によって行われる。
【００２１】
上記製品ＰＲにあっては、図３に示すように綿状の熱可塑性有機繊維ＯＦが木片ＦＬに絡みつゝ板全体に網状に広がり、更に表裏層部分では該熱可塑性有機繊維相互が点Ｍe で融着し部分接着もしくは点接着しているので、その結果板が補強されて剛性が向上し、かつ破壊荷重がかゝったとき表面からの繊維の引き抜けが減少して表面クラックの発生が抑制され、釘打ちの際の花咲き現象が防止されて釘打ち性が改良される。そして板表面に深い凹凸模様を形成するような場合にも該凹凸模様を形成した後に熱可塑性有機繊維ＯＦを加熱融着し、部分接着もしくは点接着させるので繊維網が破壊したり、表面が崩れたりするおそれがない。
繊維網を板内部とくに表面近くに挿入した後、板裏面に深い凹凸模様を形成すると、繊維網が破壊したり表面が崩れたりする。繊維網を板内に形成させることは通常湿式抄造法では困難であるが、本発明では湿式抄造法でも板内に繊維網のかわりに熱可塑性有機繊維の融着によるネット効果が得られる。
【００２２】
〔実施例〕
表１に各材料の原料組成を示す。
【表１】

【００２３】
上記原料組成のうち熱可塑性有機繊維と木片または木質繊維のみをアイリッヒミキサーにて回転混合すると、該熱可塑性有機繊維はほぐされつゝ木片に絡まり綿菓子のような綿状になる。こゝでセメントとリジェクトを添加して更に混合し、最後に硬化促進剤と防水剤および水を添加し混合して原料混合物を調製した。
表１において、比較例１は熱可塑性有機繊維を添加しない試料、比較例２は熱可塑性有機繊維と木片を予じめ混合せず、原料全部を一度に混合して原料混合物を調製した試料である。
【００２４】
実施例１〜２は上記原料混合物を基板上に撒布してマットをフォーミングし、面圧３．９ＭＰa で圧締し、５０℃，１２時間加熱して該マットを一次硬化させ、常温で４日間の二次硬化を行なった。その後熱間ロールプレスで板の表裏面を実施例１では１８０℃、２〜３分間加熱し、実施例２では１４０℃、２〜３分間加熱し、板の表裏面部分の熱可塑性有機繊維を相互融着せしめ点接着させた。実施例３は実施例１、２と同条件の一次硬化の後図４のようなプログラムのオートクレーブ養生中で、実施例４は実施例１、２と同条件の一次および二次硬化の後図５のようなプログラムの乾燥工程中で、それぞれ熱可塑性有機繊維を融着せしめ点接着させた。また実施例５は湿式抄造法により作成した。
このようにして製造した木質セメント板試料の物性を表２に示す。
【００２５】
【表２】

【００２６】
表２に示すように、熱可塑性有機繊維を添加しない比較例１は釘保持力に劣り、また熱可塑性有機繊維と木片とを予かじめ混合せず、原料全部を一度に混合した比較例２では熱可塑性有機繊維相互が絡み合ってダマとなり、板全体に網状に広がらないので、熱可塑性有機繊維の補強効果が小さく、釘保持力は本発明試料よりも小さくなる。
【００２７】
【発明の効果】
本発明ではフォーミングされたマット中に熱可塑性有機繊維の綿状塊中に原料混合物が包含された状態の集合体が存在し、該マットを圧締硬化養生して板とする際に、該熱可塑性有機繊維の綿状塊が板全体に網状に広がり、更に表層および裏層部分では該熱可塑性有機繊維相互が融着し、部分接着もしくは点接着しているから該板が補強されかつ表面クラックの発生が抑制される。
また表面に深い凹凸模様を形成するような場合にも、深い凹凸模様を形成した後に熱可塑性有機繊維を相互に融着し、部分接着もしくは点接着するので表面の崩れもなくなり鮮明な凹凸模様が容易に得られる。そして釘打ちの際の外力が該網状に広がった熱可塑性有機繊維によって分散緩和され、更に木片または木質繊維のまわりに絡みついている熱可塑性有機繊維よって木片または木質繊維が拘束されて割れにくゝなり、また打ち込まれた釘に該熱可塑性有機繊維が絡みつくので、裏面の花咲き現象が抑制されかつ釘保持力が向上する。
【図面の簡単な説明】
【図１】 (1)(2)(3)(4)、熱可塑性有機繊維と木片との混合過程を示す説明図
【図２】基板上にフォ−ミングされたマットの説明図
【図３】板の側断面図
【図４】実施例３における一次硬化後のオートクレーブ養生プログラム図
【図５】実施例４における二次硬化後の乾燥工程プログラム図
【符号の説明】
ＯＦ熱可塑性有機繊維
ＦＬ木片
ＦＬ’ 木質繊維
Ｐ粉体
Ｃ集合体
ＰＲ製品（板)
Ｍe 融着点[0001]
[Industrial application fields]
The present invention relates to a wood cement board used for, for example, a field board or an exterior material as a roof base material.
[0002]
BACKGROUND OF THE INVENTION
This kind of wood cement board is a so-called wood chip cement board obtained by molding and hardening a raw material mixture mainly composed of wood pieces and cement into a plate shape, and is a board having fire resistance and wood workability. However, since the wood cement board is reinforced only by a coarse piece of wood, when a nail is driven when used for a field board or the like, a thick piece of wood exists in the back layer depending on the place of placement, and the nail is a piece of wood. In so doing, a so-called flower bloom phenomenon occurs where the back side is pushed without being penetrated and the part around the nail is missing. When such a flowering phenomenon occurs, the nail holding power of the plate decreases.
[0003]
[Prior art]
As a means for improving the nailing property of such a wood cement board, it has been proposed to add dry pulp or synthetic fiber to a conventional wood chip cement board (Japanese Patent Laid-Open No. 9-87002).
[0004]
[Problems to be solved by the invention]
A wood cement board is manufactured by a semi-dry method in which a mat is formed by adding water to a raw material mixture mainly composed of wood chips and cement and spreading it on a substrate, and the mat is pressed and cured. In some cases, when a large amount of dry pulp or synthetic fiber is added, the fibers are entangled with each other, resulting in lumps and a sufficient reinforcing effect cannot be obtained. Therefore, when a wood chip cement board is manufactured by a semi-dry method, a large amount of dry pulp or synthetic fiber cannot be added (usually about 0.1 to 2.0% by weight), and the effect of improving nailability is sufficient. I couldn't say that.
[0005]
[Means for Solving the Problems]
The present invention provides, as means for solving the above-described conventional problems, a wood cement board that is a cured product of a raw material mixture containing wood chips FL or wood fibers FL ′ and a cementitious inorganic material, and has a heat The thermoplastic organic fiber network derived from the aggregate C in which the raw material mixture is contained in the flocculent mass of the plastic organic fiber OF is spread out as a whole, and in the surface layer and / or the back layer portion, the thermoplastic organic fiber The fiber OF provides a wood cement board that is fused together.
The thermoplastic organic fiber OF is preferably contained in the wood cement board in an amount of 1.0 to 8.0% by weight.
[0006]
Further, in the present invention, the thermoplastic organic fiber OF and the wood piece FL are mixed by high-speed rotation stirring to form a spongy form in which the thermoplastic organic fiber OF is entangled with the wood piece FL, and then other wood cement board raw materials and water To prepare a raw material mixture, spread the raw material mixture on a substrate, form a mat, press-harden the mat, and a method for producing a wood cement board, and thermoplastic organic fiber OF and wood fiber FL 'And mixing the mixture with high-speed rotating agitation to make the thermoplastic organic fiber OF entangled with the wood fiber FL' and then dispersing it in water together with other wood cement board materials to prepare a raw material slurry, The present invention provides a manufacturing method in which the raw material slurry is made to form a mat and the mat is pressed and cured.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[Cement-based inorganic powder]
The cement-based inorganic powder used in the present invention is a hydraulic inorganic material mainly composed of calcium silicate. As such an inorganic material, for example, Portland cement or Portland cement mixed with blast furnace slag is used. There are blast furnace cement, fly ash cement mixed with fly ash, silica cement mixed with silica materials such as volcanic ash and clay, alumina cement, blast furnace slag and the like.
[0008]
[Wood pieces]
The wood piece used in the present invention is not particularly limited, but for a single layer, an average length of 1 to 20 mm and a thickness of 0.5 to 3 mm are preferable, and a surface layer in a two-layer structure or a three-layer structure. For the surface layer, those having an average length of 1 to 12 mm and a thickness of 0.5 to 1.5 mm (fine grained wood pieces) are preferred, and for the back layer in a two-layer structure, the average length is 1 to 15 mm and the thickness is What is 0.5 to 2 mm (medium grain piece) is preferable, and for core layers in a three-layer structure, the average length is 5 to 20 mm and the thickness is 0.8 to 2.5 mm (coarse grain piece) Is preferred.
As described above, the wood piece for the back layer in the two-layer structure may be slightly rougher than the wood piece for the surface layer, but the finer one is less likely to cause a flower bloom phenomenon.
[0009]
[Wood fiber]
The wood fiber used in the wet method of the present invention is preferably wood fiber such as kraft pulp, waste paper or virgin pulp.
[0010]
[Thermoplastic organic fibers]
The thermoplastic organic fiber used in the present invention is a fiber of a thermoplastic resin such as a polyamide fiber, a polyester fiber, a polyethylene fiber, or a polypropylene fiber, but in addition to the thermoplastic fiber, a polyvinyl alcohol fiber (vinylon), Examples thereof include polyvinyl chloride fibers such as polyvinyl chloride and polyvinylidene chloride, synthetic fibers such as polyurethane fibers, polyoxymethylene fibers, polytetrafluoroethylene fibers, benzoate fibers, and polyimide fibers. The fibers may be recycled fibers obtained by defibrating scraps of fiber sheets such as nonwoven fabrics, knitted fabrics, and felts. The fiber is preferably a single fiber having a diameter of 0.1 mm or less.
[0011]
[Other ingredients]
In the wood cement board of the present invention, magnesium chloride, magnesium sulfate, calcium chloride, calcium sulfate, sodium aluminate, potassium aluminate, aluminum sulfate, water glass, etc., as components other than the above-mentioned cement-based inorganic material and thermoplastic organic fiber Hardening accelerator, mineral powder such as vermiculite, bentonite, wood cement board, wood cement board waste material such as wood fiber cement board (reject), waterproofing agent such as wax, paraffin, silicon, synthetic resin emulsion, etc. A replenishing material, a foamable thermoplastic bead, a plastic foam or the like may be added.
The above examples are not intended to limit the present invention.
[0012]
[Composition of wood cement board]
In the raw material mixture of the wood cement board of the present invention, the cement-based inorganic material is preferably 55 to 90% by weight, the wood piece is preferably 10 to 45% by weight, and the thermoplastic organic fiber is a synthetic fiber. Is 1.0 to 5.0% by weight, preferably 1.5 to 2.5% by weight, and in the case of wood fiber, 3 to 20% by weight, preferably 5 to 10% by weight.
In the raw material mixture, if the mixture ratio of the wood pieces is less than 10% by weight, the reinforcing effect by the wood pieces is not sufficient, and if the mixture ratio of the wood pieces exceeds 45% by weight, the amount of the cement-based inorganic material is relatively reduced. The consolidation of the cement-based inorganic material is hindered, and the strength tends to decrease.
If the amount of the thermoplastic organic fiber added is less than the above range, the effect of improving the nailability is not significant, and if it exceeds the above range, the fibers are easily entangled with each other.
[0013]
[Manufacture of wood cement board]
The wood cement board of the present invention is preferably produced by a semi-dry method or a wet papermaking method. Particularly, in the wood cement board produced by these methods, the effect of preventing or suppressing the flowering phenomenon is remarkable.
[0014]
In the case of the semi-dry method, first, the thermoplastic organic fiber and the wood piece are stirred at high speed using a forced stirring type mixer such as a rotary mixer. If it does so, the said thermoplastic organic fiber will become cotton shape, entangled with a piece of wood.
[0015]
After the thermoplastic organic fiber is entangled with wood pieces and made into a cotton shape as described above, powder raw materials such as cement-based inorganic material, mineral powder, reject, etc. are added and mixed, and then water-proofing agent, hardening accelerator and water are added and mixed To prepare a raw material mixture. The amount of water added is such that the water content in the raw material mixture is usually 15 to 50% by weight. However, when the reinforcing material is wood fiber, a thermoplastic organic fiber and wood fiber are forcibly stirred. It is desirable to add a small amount of water in advance when the powder raw material is added and mixed after the thermoplastic organic fiber is entangled with the wood fiber by stirring at high speed.
[0016]
The raw material preparation process is shown in Fig. 1 (1), (2), (3) and (4). When the wood piece FL and the thermoplastic organic fiber OF are stirred at high speed in (1), the thermoplastic organic fiber OF is entangled with the wood piece FL as shown in (2). When stirring at a higher speed, as shown in (3), agglomeration of the pieces of wood entangled with the thermoplastic organic fibers OF begins to occur, and the agglomerates contain air and swell into a cotton candy shape. When the powder raw material P such as cement is added and stirred at a high speed, the wood piece FL having the powder raw material P such as cement attached to the surface is heated like cotton candy as shown in (4). Aggregates C are formed which are scattered and contained in a flocculent mass of plastic organic fibers or thermoplastic organic fibers.
Such a raw material mixture including the aggregate C is distributed on a substrate B such as a template or a conveying plate, and a mat M as shown in FIG. 2 is formed.
[0017]
When the mat M including the aggregate C is formed as described above, the mat M is pressed together with the substrate to be primarily cured in a heated state. The temperature applied in the primary curing is usually 50 to 100 ° C., and the pressing pressure is usually 2 to 5 MPa.
After the primary curing, the obtained primary cured body is demolded and then subjected to normal temperature curing or autoclave curing. The normal temperature curing is usually performed at normal temperature for 2 to 5 days, and the autoclave curing is normally performed at a humidity of 85% RH or higher and a temperature of 130 to 180 ° C. for 4 to 18 hours. After normal temperature curing or autoclave curing, a surface treatment is performed through a drying process to obtain a wood cement board.
[0018]
When a concavo-convex pattern is provided on the surface of the wood cement board, a concavo-convex pattern corresponding to the concavo-convex pattern may be formed on the mold surface of the substrate. Moreover, when manufacturing a smooth wooden cement board without an uneven | corrugated pattern on the surface, you may use a conveyance board directly as a board | substrate.
[0019]
In the case of the wet papermaking method, similar to the semi-dry method, thermoplastic organic fibers are entangled with wood fibers to form a cotton, and then dispersed in water together with other wood cement board raw materials similar to the semi-dry method to form a raw material slurry. To do. The raw slurry is usually prepared with a solid content concentration of about 10 to 20% by weight, poured onto a long filter cloth with good drainage to form a papermaking layer, and the papermaking layer is wound into a plurality of layers on a making roll. The laminated mat that has been cut and developed at a predetermined thickness is usually formed by pressure forming with a flat plate press or roll press to form a formed mat. The molding mat is usually press-cured under the above conditions, and then cured at room temperature for 2 to 5 days as described above, or autoclaved for 4 to 18 hours at a temperature of 130 to 180 ° C. at a humidity of 85% RH or higher. The
[0020]
The wood cement board produced by the semi-dry method or the wet papermaking method, the surface layer and / or the back layer part is heated to a temperature higher than the softening point of the thermoplastic organic fiber, and the surface layer and / or the back layer part Thermoplastic organic fibers are fused together and partially bonded or spot bonded.
The surface layer and / or the back layer portion of the wood cement board is heated during autoclave curing, in a heating plate, in a hot roll press, or in a heating process in a drying process.
[0021]
In the product PR, as shown in FIG. 3, the cotton-like thermoplastic organic fiber OF is entangled with the wood piece FL and spreads in a net-like manner on the entire board, and in the front and back layer portions, the thermoplastic organic fibers are point Me. As a result, the plate is reinforced and the rigidity is improved, and when the breaking load is applied, fiber pull-out from the surface is reduced and surface cracks are generated. Is suppressed, the flower bloom phenomenon at the time of nailing is prevented, and the nailability is improved. And even when forming a deep concavo-convex pattern on the surface of the plate, after forming the concavo-convex pattern, the thermoplastic organic fiber OF is heat-fused and partially bonded or spot-bonded, so the fiber network breaks or the surface collapses. There is no fear of
If a deep concavo-convex pattern is formed on the back side of the plate after the fiber net is inserted inside the plate, particularly near the surface, the fiber network is broken or the surface is broken. It is usually difficult to form a fiber network in a plate by a wet papermaking method, but in the present invention, a net effect can be obtained by fusing thermoplastic organic fibers in place of a fiber network in the plate even in the wet papermaking method.
[0022]
〔Example〕
Table 1 shows the raw material composition of each material.
[Table 1]

[0023]
When only thermoplastic organic fibers and wood pieces or wood fibers of the above raw material composition are rotated and mixed with an Eirich mixer, the thermoplastic organic fibers are entangled with the wood pieces and become cottony like cotton candy. Cement and reject were added thereto and further mixed. Finally, a hardening accelerator, a waterproofing agent and water were added and mixed to prepare a raw material mixture.
In Table 1, Comparative Example 1 is a sample to which no thermoplastic organic fiber is added, and Comparative Example 2 is a sample in which a raw material mixture is prepared by mixing all the raw materials at once without mixing thermoplastic organic fibers and wood pieces in advance. is there.
[0024]
In Examples 1 and 2, the above raw material mixture was spread on a substrate, the mat was formed, pressed at a surface pressure of 3.9 MPa, heated at 50 ° C. for 12 hours to primarily cure the mat, and then at room temperature for 4 days. Secondary curing was performed. Thereafter, the front and back surfaces of the plate are heated at 180 ° C. for 2 to 3 minutes in Example 1 with a hot roll press, and the thermoplastic organic fibers on the front and back surfaces of the plate are heated at 140 ° C. for 2 to 3 minutes in Example 2. They were fused together to make point bonds. Example 3 is the autoclave curing of the program as shown in FIG. 4 after the primary curing under the same conditions as in Examples 1 and 2, and Example 4 is the figure after the primary and secondary curing under the same conditions as in Examples 1 and 2. In the drying process of the program as in No. 5, the thermoplastic organic fibers were fused and adhered to each other. Example 5 was prepared by a wet papermaking method.
Table 2 shows the physical properties of the wood cement board samples thus produced.
[0025]
[Table 2]

[0026]
As shown in Table 2, Comparative Example 1 in which the thermoplastic organic fiber was not added was inferior in nail holding power, and the thermoplastic organic fiber and the wood piece were not preliminarily mixed, but all the raw materials were mixed at one time. Then, the thermoplastic organic fibers are entangled with each other and become lumps and do not spread in a net shape on the entire plate. Therefore, the reinforcing effect of the thermoplastic organic fibers is small, and the nail holding force is smaller than that of the sample of the present invention.
[0027]
【The invention's effect】
In the present invention, there is an aggregate in which a raw material mixture is contained in a cotton-like lump of thermoplastic organic fibers in a formed mat, and when the mat is pressed and cured to form a plate, A cotton-like lump of plastic organic fibers spreads in a net-like pattern throughout the board, and the thermoplastic organic fibers are fused to each other in the surface layer and back layer part, so that the board is reinforced and surface cracked. Is suppressed.
Also, when forming a deep concavo-convex pattern on the surface, after forming the deep concavo-convex pattern, the thermoplastic organic fibers are fused to each other and partially bonded or spot-bonded, so the surface does not collapse and a clear concavo-convex pattern is formed. Easy to get. The external force at the time of nailing is dispersed and relaxed by the thermoplastic organic fibers spread like a net, and the wooden pieces or wood fibers are restrained by the thermoplastic organic fibers entwined around the wood pieces or wood fibers, so that they are not easily broken. In addition, since the thermoplastic organic fibers are entangled with the nail that is driven, the flower bloom phenomenon on the back surface is suppressed and the nail holding power is improved.
[Brief description of the drawings]
[Fig. 1] (1) (2) (3) (4), explanatory diagram showing the mixing process of thermoplastic organic fibers and wood pieces [Fig. 2] explanatory diagram of the mat formed on the substrate [Fig. [Figure 4] Side cross-sectional view of the plate [Fig. 4] Autoclave curing program diagram after primary curing in Example 3 [Fig. 5] Drying process program diagram after secondary curing in Example 4 [Explanation of symbols]
OF Thermoplastic organic fiber FL Wood piece FL 'Wood fiber P Powder C Aggregate PR Product (board)
Me fusion point

Claims

A wood cement board, which is a cured product of a raw material mixture containing wood chips or wood fibers and a cement-based inorganic material, wherein the raw material mixture is contained in a cotton-like lump of thermoplastic organic fibers inside The thermoplastic organic fiber network derived from the above is spread as a whole, and the thermoplastic organic fibers are fused to each other in the surface layer and / or the back layer portion.

2. The wood cement board according to claim 1, wherein the thermoplastic organic fiber is contained in the wood cement board in an amount of 1.0 to 8.0% by weight.

A thermoplastic organic fiber and wood pieces are mixed by high-speed rotational stirring to form a cotton-like form in which the thermoplastic organic fibers are entangled with the wood pieces, and another wood cement board raw material and water are added and mixed to form a raw material mixture. 3. The method for producing a wood cement board according to claim 1 or 2, wherein the raw material mixture is prepared and spread on a substrate to form a mat, and the mat is pressed and cured.

The thermoplastic organic fiber and wood fiber are mixed by high-speed rotation stirring to form a cotton-like entangled thermoplastic fiber and then dispersed in water together with other wood cement board materials to form a raw material slurry. The method for producing a wood cement board according to claim 1 or 2, wherein the raw slurry is prepared, the mat is formed, the mat is formed, and the mat is pressed and cured.